Zinc Whiskers - What You Should Know Now!

BACKGROUND Metal whiskers have long been a known problem for electronics.For the last 10 years, the article Are Zinc Whiskers Growing in Your Computer Room?

has been used as a guide to investigate and remediate Zinc Whiskers from data centers around the globe.Unfortunately, despite significant effort, Zinc Whiskers haven't gone away. As an industry it was generally considered that the only serious source of Zinc Whiskers in computer facilities was certain types of access floor panels.Facilities without these specific panel types were assumed ineligible for whisker contamination. How wrong was that assumption!Zinc Whiskers have been found on a variety of metal components within all types of facilities, including:steel building studs; electrical conduit; suspended ceiling T-bar grid and hanger wires; and of course access floor panels, pedestals, pedestal heads, and stringers.This may be surprising, but it's not really news.

PART I - Zinc Whisker Susceptibility The real news is Zinc Whiskers are being discovered every day on cabinets, racks, and the servers and computers themselves.That's right! Zinc Whiskers may be growing on and in computer hardware. How is this possible?It's simple really.Computer systems are a combination of electronic circuit cards mounted and contained within metal boxes and enclosures.The metal of choice is steel because it is conductive, strong, and reasonably inexpensive.The steel is often plated to prevent oxidation or rust.Zinc is still the plating material of choice because it's relatively inexpensive, is conductive, and yields a good finish appearance.Many computer enclosures are zinc plated; so are rack rails, cabinet shelf supports, and other structural elements. If Zinc Whiskers are everywhere, aren't they noticeable?Remember that Zinc Whiskers are thinner than a human hair and roughly 0.5 - 5.0mm long.You have to be looking for them to find them.Look for them growing en masse.Seeing a single whisker is like looking for the proverbial needle in a haystack. Zinc Whisker contamination should be considered whenever there are abnormally high failure rates - both catastrophic and less severe soft failures.The failure rate may peak within 72 hours of performing invasive maintenance work in or around the equipment. Many factors determine the probability of Zinc Whisker failures.These include but are not limited to:

Many users wrongly conclude only power supplies are susceptible to whisker related failures.This is likely because power supply failure tends to occur with a dramatically loud 'pop' and cause a system outage.Unfortunately, power supplies are not the only exposed electronics in a computer system.There are a myriad of integrated circuits (chips), leads, circuit traces, and other components.To be sure, parts of all the items on this list may be concealed by plastic or solder mask and generally unexposed.

But not everything is protected, and these uncovered leads are just as susceptible as the power supply.Zinc whisker bridges and shorts of exposed circuitry still have the potential to wreak havoc on a system.What happens if leads on the memory bus are intermittently shorted during the critical setup and latch portion of the clock cycle?Perhaps data will be corrupted.Perhaps the corruption will be detected and corrected by error correction algorithms.Perhaps the affected data is really an instruction for the processor.What if the processor tries to load and execute this corrupted instruction? Will the system failover or hang?Any engineer will agree that finding and fixing intermittent failures is one of the hardest things to do."If you can't see it, you can't fix it."Whisker related failures fit into this category.

Many system anomalies are not logged or tracked.If a reset clears the situation, the problem is quickly dismissed as annoying but non-critical.Often, these on-the-floor fixes don't get the visibility of management.Ask an IT manager if equipment needs to be reset and they'll say, "...no, why do you ask?"Ask an operator if equipment needs to be reset and they'll answer, "...of course, all the time, why do you ask?" So, if Zinc Whiskers are everywhere and affecting equipment, how come it is not common knowledge?Most users get their information from personal experience or from trusted sources.If personal experiences are not memorable, it's human nature to discount and discard them.If resetting a stuck machine is no more memorable than filling a coffee cup, it isn't remembered.A power supply popping is unusual and memorable.Clicking the button is not.

In the IT world, trusted resources are typically associates and vendors.Neither one is talking because neither one has an incentive to talk.Users don't admit they have Zinc Whisker problems because of fear of condemnation and repercussions from vendors.Users are supposed to honor their equipment contracts by maintaining suitable computing environments.Zinc Whisker contamination does not contribute to a suitable environment.Likewise, vendors aren't talking for fear of liability.Vendors are supposed to honor explicit and implied warranties that the equipment they produce and sell is free from defects.If the very equipment is vulnerable and or producing the whiskers, there is a legitimate fear of legal liability.

The result of all this silence is customer ignorance about a very serious topic.

PART II - The Reach of Zinc Whiskers and What to Do Next How bad is it?

Evidence suggests that Zinc Whiskers may affect one or more components in 50% or more of the racks and cabinets in any given environment.Historically, manufacturers only tested equipment when problems were suspected. Users only tested when the manufacturers weren't providing answers.Recently, large users have been willing to sponsor broader, facility-wide testing.Unfortunately, for the reasons indicated above, the specific results of these tests remain confidential.Suffice it to say, Zinc Whiskers affect or have affected virtually all vendors.

If whiskers abound, why aren't there more problems?

The evidence suggests that Zinc Whiskers tend to remain reasonably well connected to the host surface.Until they reach a certain length, Zinc Whiskers will remain connected until they are liberated by mechanical means such as rubbing and scraping.After they reach a certain length, not only is liberation possible from direct mechanical means but also from more passive means such as vibration or airflow.Once dislodged, Zinc Whiskers are free to migrate within the environment.

Zinc Whisker failures need not be catastrophic.Bit errors, soft failures, and other anomalies may be attributed to Zinc Whiskers.

What is the cure for Zinc Whiskers?

Generally, the accepted cure for Zinc Whiskers is to remove and replace the root source material with an uncontaminated version.It is not reasonable to replace every contaminated piece of equipment, either from a logistics or financial perspective.That doesn't mean the problem should be ignored. .Zinc Whiskers will continue to grow.As they become longer,they become potentially more harmful.

Users can't stop using their equipment nor can they stop meeting the needs of the business through hardware migrations, moves and rearrangements. Users who want to proactively address the issue should develop a plan for managing the issue through staff training, vendor management, and equipment and facility handling procedures.

There are many suitable healthcare analogies that can realistically be applied: don't stop working with a sick patient; don't ignore the patient's condition.Rather, take proactive steps to help the patient while preventing the patient from infecting or sickening others.

Part III - Addressing Zinc Whisker Contamination The following recommendations are based on a logical argument that to do nothing is neither proactive nor rational in the long term.Something must be done.Outlined below is one possible approach to dealing with broad Zinc Whisker contamination.

Users should require:

Users will:

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How Much Power Supply Voltage Regulator
How Much Power Supply Voltage Regulator
There are different electric bikes with different experiences.Some are heavy and powerful, and move with a push of a button. Their pedals are more about legal status than about human power. I'd call them "scooters".Some are designed to supply power only when the pedals are turning. In that case you have to do a little work for the electric motor to kick in. These are usually called pedelec (from "pedal electric cycle").Some use sensors in the drivetrain to decide when to apply the power. Those often have a switch so you can get them to drive the motor without pedaling, giving them a "scooter mode".Some (like the StokeMonkey) apply the power directly to the drivetrain, so you always have to pedal to get them to work. If you're looking for exercise this is a good idea - no temptation to just cruise under power aloneWith new battery technologies a new kind of "bicycle" has emerged - so-called e-bike.It usually has an electric motor on one of its wheels. The motor is powered by a rather huge (size of a small bag) battery. Pedals, star wheels and the chain are still in place, so the user canuse it as a normal bicycle oruse pedals to assist the vehicle orjust rely on the motor and use it as a scooter.Speeds like 20 kmph witout using pedals are typically promised.What I don't get is in which scenario and how I use such vehicle.Do I use is as a scooter with ability to be driven by pedals once it runs out of the battery or do I use it as a bicycle with the motor assisting me and letting go faster without too much of activity?·OTHER ANSWER:With new battery technologies a new kind of "bicycle" has emerged - so-called e-bike.It usually has an electric motor on one of its wheels. The motor is powered by a rather huge (size of a small bag) battery. Pedals, star wheels and the chain are still in place, so the user canuse it as a normal bicycle oruse pedals to assist the vehicle orjust rely on the motor and use it as a scooter.Speeds like 20 kmph witout using pedals are typically promised.What I don't get is in which scenario and how I use such vehicle.Do I use is as a scooter with ability to be driven by pedals once it runs out of the battery or do I use it as a bicycle with the motor assisting me and letting go faster without too much of activity?
Detailed Anatomy of Various Protection Circuit Examples of Switching Power Supply
Detailed Anatomy of Various Protection Circuit Examples of Switching Power Supply
1、 Input undervoltage protection circuit 11. Overview (circuit category and description of main functions): this circuit belongs to the input undervoltage circuit. When the input voltage is lower than the protection voltage, pull down the power supply VCC of the control chip to close the output.2. Circuit composition (schematic diagram):3. Working principle analysis (main functions, performance indicators and implementation principle):When the power input voltage is higher than the undervoltage protection set point, the voltage at point a is higher than the VREF of U4, U4 is on, the voltage at point B is low, Q4 is on, and VCC power supply is normal; When the input voltage is lower than the protection voltage, the voltage at point a is lower than the VREF of U4, U4 is cut off, the voltage at point B is high level, and Q4 is cut off, so that VCC has no voltage. At this time, VREF is also low level. When the input voltage gradually increases, the voltage at point a also gradually increases. When it is higher than the VREF of U4, the module works normally. R4 can set the return difference of undervoltage protection point.4. Advantages and disadvantages of the circuit: the advantages of the circuit: simple circuit and accurate protection point; Disadvantages: high cost.5. Precautions for application: when using, pay attention to the values of R1 and R2. Sometimes two resistors need to be connected in parallel to obtain the required protection point. It is also necessary to pay attention to the temperature coefficients of R1 and R2, otherwise the undervoltage protection points will differ greatly at high and low temperatures.2、 Input undervoltage protection circuit 21. Overview (circuit category, description of main functions): input undervoltage protection circuit. When the input voltage is lower than the set undervoltage value, turn off the output; When the input voltage rises to the set recovery value, the output automatically returns to normal.2. Circuit composition (schematic diagram):3. Working principle analysis (main functions, performance indicators and implementation principle):When the input voltage is within the normal working range, VA is greater than the regulated value of VD4, vt4 is on, VB is 0 potential, vT5 is off, and the protection circuit does not work at this time; When the input voltage is lower than the set undervoltage value, VA is less than the regulated value of VD4, vt4 is cut off, VB is high potential, vT5 is turned on, comp (pin 1 of the chip) is pulled to 0 potential, and the chip closes the output, so as to realize the undervoltage protection function. R21, VT6 and R23 constitute the return differential circuit during undervoltage shutdown and recovery. When undervoltage is turned off, VT6 is turned on and R21 and R2 are connected in parallel,; On recovery, VT6 is off,, the return difference voltage is (VIN '- VIN).4. Advantages and disadvantages of the circuit:Advantages: simple circuit form and low cost.Disadvantages: the undervoltage protection point fluctuates up and down due to the difference of voltage stabilizing value between VD4 batches of voltage stabilizing tube. Relevant parameters need to be debugged frequently during mass production.5. Precautions for application:VD4 should select a voltage stabilizing tube with good temperature coefficient, and multiple components to be debugged, such as R2, should be considered in parallel to facilitate debugging.Output overvoltage protection circuit1、 Output overvoltage protection circuit 11. Overview (circuit category, description of main functions): output overvoltage protection circuit. When an applied voltage higher than the normal output voltage range is applied to the output terminal or the output voltage is higher than the regulated value due to the fault of the circuit itself (open-loop or other), the circuit will clamp the output voltage at the set value.2. Circuit composition (schematic diagram):3. Working principle analysis (main functions, performance indicators and implementation principle): when the output voltage is over-voltage, when the voltage applied to VD3 is greater than its regulated value, VD3 is turned on, the output voltage is clamped, and feedback to the primary side through iC4.4. Advantages and disadvantages of the circuit:Advantages: simple circuit form and low cost.Disadvantages: due to the difference of voltage stabilizing value between VD3 batches of voltage stabilizing tube, the overvoltage clamp position fluctuates up and down, and relevant parameters need to be debugged frequently during mass production.5. Precautions for application: VD3 should select a voltage stabilizing tube with good temperature coefficient, and multiple components to be debugged, such as R32, should be considered in parallel to facilitate debugging. When the overvoltage protection circuit works, the circuit is in an abnormal working state. For the circuit with the function of up and down regulation of output voltage, the overvoltage protection point shall be greater than the maximum value of up regulation of output voltage.2、 Output overvoltage protection circuit 21. Overview (circuit category, description of main functions): output overvoltage protection circuit. When an applied voltage higher than the normal output voltage range is applied to the output terminal or the output voltage is higher than the normal value due to the fault of the circuit itself (open-loop or other), the circuit will stabilize the output voltage at the set value.2. Circuit composition (schematic diagram):3. Working principle analysis (main functions, performance indicators and implementation principle): when outputting overvoltage, VA > VREF, IC3 is on, and iC4 feeds back to the primary side, and the output voltage is stable at the set overvoltage protection value.4. Advantages and disadvantages of the circuit:Advantages: the output overvoltage protection value can be set accurately.Disadvantages: the cost is slightly higher than that of the clamping mode of the pressure stabilizing tube.5. Precautions for application: when the overvoltage protection circuit works, the circuit is in abnormal working state. For the circuit with the function of up and down regulation of output voltage, the overvoltage protection point shall be greater than the maximum value of up regulation of output voltage.Overvoltage protection self-locking control circuit1. Overview (circuit category and description of main functions realized): in the power supply system, when the feedback circuit fails, the output voltage is uncontrolled and the voltage rise exceeds the specified range. At this time, the excessive output voltage may cause damage to subsequent electrical equipment. In order to solve this problem, an overvoltage protection circuit is usually added to the power supply. There are generally three ways of overvoltage protection.A. Clamp type: when the feedback fails, clamp the output voltage at a fixed value through the overvoltage clamp circuit.B. Intermittent protection type: when the feedback fails, the output voltage is restarted back and forth through the protection circuit, and the highest point of the output voltage is the overvoltage protection point.C. Self locking type: when the output voltage reaches the overvoltage protection point, the circuit acts and turns off PWM so that the module has no output. After troubleshooting, restart the power output to supply power normally. The following circuits are self-locking control circuits.2. Circuit composition (schematic diagram):3. Working principle analysis (main functions, performance indicators and implementation principle):The figure above shows the isolated self-locking control circuit. When the overvoltage protection signal control terminal gives a high level, the triode in U1 is turned on, and VCC is the power supply terminal of the whole circuit. VCC sends a base current to Q2 through R5, Q1 turns on and enters the saturation state, the shut end is pulled to the low level by Q2, PWM is turned off, and there is no output. Q2 simultaneously controls the conduction of Q1. When Q2 is on, the base current of Q1 reaches the ground through R2, Q1 is on, and a base current is provided to Q2 through R3 to maintain Q2 on. Q1, R1, R2 and R3 constitute the positive feedback circuit of Q2.4. Advantages and disadvantages of the circuit:Advantages: it can effectively carry out self-locking protection, and the whole circuit is equivalent to a thyristor.Disadvantages: the whole circuit needs a fixed VCC. When there is no power supply at the PWM power supply terminal, it is also necessary to ensure the existence of VCC voltage in the figure above.5. Precautions for application:1. The self-locking of this circuit is effective only when there is continuous power supply.2. This circuit should not be used in unattended power supply system.Over temperature protection circuit1. Overview (circuit category and description of main functions): the circuit belongs to over temperature protection circuit, but when the temperature is higher than the set protection point, close the module output, and automatically open the module when the temperature recovers.2. Circuit composition (schematic diagram):3. Analysis of working principle (main functions, performance indicators and implementation principle): the regulator provides 5V voltage to u103max6501. When the temperature is normal, the five pins of u103 output high level. When the temperature exceeds the protection point, the five pins of u103 output low level. When the temperature is restored, the five pins of u103 output high level.4. Advantages and disadvantages of the circuit:The circuit has the advantages of simple circuit and high accuracy.Disadvantages: high cost.5. Precautions for application:5.1 when the 3-pin and 1-pin of max6501 are connected, the return difference temperature is 10 ℃, and when the 3-pin is connected to the ground, the return difference temperature is 2 ℃.5.2 the power supply voltage of max6501 shall not exceed 7V, otherwise it will be damaged.5.3 max6501 must be placed near the hottest part.Over temperature protection circuit - Thermistor1. Overview (circuit category and description of main functions): this circuit uses thermistor to detect the substrate temperature. The thermistor resistance changes with the substrate temperature. The change of thermistor resistance leads to the change of input voltage of operational amplifier, so as to realize the turnover of operational amplifier, control the output of PWM chip, and then close the module.2. Circuit composition (schematic diagram):3. Working principle analysis (main functions, performance indicators and implementation principle, calculation and analysis of key parameters):R99 thermistor is a thermistor with negative temperature coefficient. At room temperature, R99 = 100k, and the partial voltage of R99 and r94 is 0.45V, which is the negative input of U2 operational amplifier, which is much lower than the positive input of 2.5V (R23 and r97 partial voltage). Therefore, the output of operational amplifier is high level, has no impact on the SS terminal of lm5025, and the module works normally. As the substrate temperature increases, the R99 resistance decreases. When it decreases to a certain value, so that the negative input of the operational amplifier is greater than the positive input, the operational amplifier outputs a low level and pulls down the SS of lm5025, so as to close the module output; The temperature protection point can be adjusted accordingly by appropriately adjusting the resistance values of r94, R23 and r97.After the module turns off the output (overtemperature protection), the substrate temperature will decrease, the R99 resistance will increase, and the negative input of the operational amplifier will decrease. In order to turn the operational amplifier over normally, the resistance r98 is introduced. The principle is that after the output of the operational amplifier is low, r98 is equivalent to being connected in parallel with r97 to lower the reference of the operational amplifier and open the voltage gap between the positive and negative inputs of the operational amplifier, so as to realize the temperature difference. For example, the substrate is protected at 90 ℃ and turned on at 80 ℃.4. Calculation and analysis of key parameters:4.1 positive input voltage of operational amplifier: vr97 = VREF2 = 5 / (1 R23 / r97) = 5 / (1 10 / 10) = 2.5V4.2 negative input voltage of operational amplifier: vr94 0.007 = vr97 = 5 * r94 / (R99 r94) 0.007,4.3 obtain the resistance value of thermistor during temperature protection: R99 (T) = (VREF * R24 / (VREF * r97 / (R23 r97) - 0.007)) - r944.4 see the following table for the calculation when considering the tolerance:4.5 value of R99 during over temperature protection4.6 r99-sdnt2012x104j4250ht (f) is a thermistor with negative temperature coefficient, 100k at 25 ° C and about 10K during over temperature protection (see the table above). The calculated temperature is:Rt=R*e(B(1/T1-1/T2)) T1=1/(ln(Rt/R)/B1/T2))T2: normal temperature 25 ° C, where T2 = 273.15 25 = 298.15; B:4250±3%; R: The resistance value at 25 ° C is 100k, and the calculated T1 value is also the value after adding 273.15. Therefore, T1 = t1-273.15 in the following table is Celsius. RT: resistance value after temperature change, 10K, 9.704k, 10.304k, see the above table4.7 return differenceWhen the output of the operational amplifier is low, the resistor r98 (51K) will be connected to r97 and the reference will be pulled down. The new reference voltage vref1 = VREF * (r98 / / r97) / (R23 r98 / / r97) = 2.28v. When it reaches 2.44v, the resistance value R99 = VREF * r94 / vref1-r94 = 11.9k, and when R99 reaches 10.49k, the temperature will be calculated according to the following tableTemperature return difference = 82.6-77.3 = 5.3 ℃5. Advantages and disadvantages of the circuit:Advantages: the temperature protection point and temperature return difference can be adjusted easilyDisadvantages: low temperature accuracyThe circuit is slightly more complex than using temperature switchThe temperature protection reflects the substrate temperature near the thermistor and cannot reflect the maximum device temperature of the module. However, this can be solved in the design. For example, if the substrate temperature is protected at 90 ℃, and the maximum device temperature on the actual board has reached 130 ℃, the temperature protection point can be adjusted appropriately to play a protective role.6. Precautions for application:Try to place the thermistor near the heating device.fqj
Why Use Gallium Nitride in Smartphone Power Supply?
Why Use Gallium Nitride in Smartphone Power Supply?
Not long ago, STMicroelectronics released a new mastergan1 product, which integrates a half bridge driver and two enhanced mode gallium nitride (GAN) transistors. Similar competitive products only contain a single gallium nitride transistor, which makes ST's mastergan1 have obvious advantages in half bridge topology applications. For example, LLC resonant converter, active clamp flyback or forward, totem pole PFC and so on in common AC-DC systems.The new device is highly symbolic because of higher integration and easier design and application. At present, when the industry uses such power devices, they are mainly used in the power supply of telecom equipment or data center. Today, with mastergan1, engineers can design smaller and more efficient power supplies for Smartphone chargers and usb-pd adapters.In recent years, the power of smart phones, tablets or laptops has increased exponentially. In order for consumers to have a better use experience, manufacturers have to increase battery capacity. However, due to the limitation of battery material technology, it is difficult to make a major breakthrough in battery capacity. Therefore, the development of fast charging technology has become the first choice of manufacturers. With USB power delivery (usb-pd) and fast charging technology, you can reach 50% power in less than ten minutes. This requires that the charger can output 100W or even higher power in a short time. On the premise of keeping the size of charger unchanged, it is imperative to improve the switching frequency. At present, chargers with Gan transistors are not popular, and the high design difficulty bears the brunt. Taking the engineers of medium-sized or even large companies as an example, it is not easy to persuade the leadership to use new technology, so it is very important to help decision makers understand this technology. At the same time, the design of Gan transistor printed circuit board is different from ordinary silicon tube. Designing a stable and reliable Gan transistor printed circuit board is also a major challenge. The significance of mastergan1 is that it can solve all these problems and make the whole design simple and reliable. Understanding the electrical properties of gallium nitride Gan[evalmastergan1] gallium nitride, with its inherent characteristics, can play an important role when small equipment needs high power. The material itself is not new. We have used it for LEDs since the 1990s and blue light readers since the 21st century. Today, the founders can produce a thin layer of gallium nitride on silicon wafer to produce transistors with unique properties. The band gap of gallium nitride is 3.39 EV, which is much higher than that of silicon (1.1 EV) and silicon carbide (2.86 EV). Therefore, its critical electric field is much higher, which means that it can provide higher efficiency at high frequency. The fundamental reason for these properties comes from the molecular structure of GaN. Gallium itself is an electrical conductor with low conductivity. However, when the nitrogen atom destroys the gallium lattice, it will significantly increase the electron mobility of the structure (1700cm2 / VS), so the electrons can move at a higher speed with less loss. When applied in the scene where the switching frequency is higher than 200 kHz, the efficiency of using Gan is higher. It enables smaller, more cost-effective systems.Evalmastergan1, seeing is believingDespite this theoretical knowledge, it may still be difficult to convince decision makers. Although Gan transistors are not new, their use in the power supply of large quantities of products is still novel. To make the functional display of GaN and mastergan1 easier, we must rely on the evalmastergan1 board. It is a real and visible physical platform and shows the appearance of a single package in the power supply. The user can choose to add a low-end shunt or an external bootstrap diode to better suit the terminal design. In addition, all pins of mastergan1 can be accessed to help developers with initial debugging and application. Mastergan1: design with gallium nitride to reduce design complexity[mastergan1] from proof of concept to custom design may be challenging. The schematic diagram of the evaluation board is a good starting point, but high-frequency applications are difficult. If the wiring on the PCB is too long, the parasitic inductance will lead to false switching. For half bridge converters, two Gan transistors are necessary, but most competing devices provide only one. Mastergan1 is a unique product because it is a single chip integrating two Gan transistors. Therefore, engineers do not have to deal with the complexity associated with such applications. Similarly, the specific Gan technology and the optimal design on the gate driver also mean that the system does not need negative voltage shutdown. Mastergan1 also has an input pin compatible with 20V signal, which can be applied to a variety of existing and upcoming controllers. The engineer must also address critical dimensional constraints. Smart phone chargers must remain miniaturized. Therefore, the size of mastergan1 package is only 9 mm x9 mm, which is very advantageous. In addition, iterative products will be launched in the coming months, and we will make them compatible with existing pins. This makes it easier to create a new design based on a PCB using mastergan1. As manufacturers compete to provide more affordable solutions, mastergan1 will make the design more cost-effective. This also explains why mastergan1 has won the design award.Improve reliabilityAnother major challenge for engineers is reliability. Unstable systems will seriously affect the user experience and even reduce consumers' trust in products. Common is a common cause of failure in half bridge topology. To this end, mastergan1 integrates interlock function, matched transmission delay and gate current of differential on and off, which can help to realize clean and effective switching. Finally, we specially designed the gate driver of mastergan1 for e-mode Gan FET, so as to improve the performance and durability. Mastergan1 is also equipped with undervoltage locking (UVLO) protection, which can prevent the increase of loss and some potential problems in case of insufficient power supply. Similarly, OTP can prevent damage caused by equipment overheating. The level converter and effective input buffer function of the gate driver make the Gan gate driver very durable and anti noise. Finally, it is also equipped with a special pin, which can set mastergan1 to idle mode, reduce loss and improve standby efficiency.
How Does the Internet of Things Help Power Companies Obtain Sufficient Power Supply
How Does the Internet of Things Help Power Companies Obtain Sufficient Power Supply
Global energy consumption is expected to soar by 40% in the next 25 years. Unless we can find a huge coal mine, we will not be able to meet this demand.You might think, "renewable energy will do the job."Yes, renewable energy is paving the way for a more sustainable future, but their large-scale adoption is still limited by some obstacles, such as their high dependence on natural phenomena, large capital investment and lack of flexibility to traditional energy networks.Until we overcome these obstacles and fully adopt renewable energy, the best and effective utilization of non renewable energy is the only important choice for us to rely on power supply for survival.Power companies have been looking for technologies that can help them optimize processes and remotely manage assets, and the Internet of things is such a technology that can help them achieve this goal.With its advanced telemetry and cognitive capabilities, power companies can improve their energy transmission and distribution processes to promote effective power flow and reduce energy waste.Let's look at how the Internet of things can help power companies obtain sufficient power supply:1. Asset monitoring and managementThis is the most concerned Internet of things application. It enables power companies to manage their equipment remotely: from generators to transmission lines. Sensors embedded in assets can measure parameters such as temperature, vibration, pressure and wear, which can be read by power companies to determine possible fault points.This allows power companies to monitor the overall health of their transmission and distribution facilities. By interpreting continuously stored data, insights and trends can also be generated to estimate failure time, and inspection and maintenance procedures can then be scheduled to eliminate failures and reduce downtime.In addition, power generation companies can plan their repair and maintenance tasks according to the real-time alarm system of the Internet of things, so as to reduce energy loss and improve operational efficiency. This helps to optimize resource consumption and promote the efficient flow of electricity from power plants to consumer facilities.2. Grid balancing and rerouting / restoration of power supply linesSmart grid is a modern Internet of things variant of the existing power grid, including a variety of energy measures and smart meters (such as smart meters). Their implementation in the distribution and transmission infrastructure makes the flow of power from power plants to end users more efficient and reliable.However, their benefits go far beyond simply supplying electricity from one place to another. They allow power companies to reduce operating costs and help users manage household electricity.In terms of improving power flow efficiency and promoting optimal resource utilization, smart grid is the first choice. When they interact in two directions, they can effectively manage congestion on power lines. They can even ensure the connection requirements of the power station, such as frequency and voltage control, to prevent instability.In addition, smart grid also has amazing power line rerouting and restoration advantages. In case the transmission line is interrupted due to bad weather conditions or voltage fluctuations, the smart grid can find another transmission line to the local area. In addition to facilitating continuous power supply, power companies can also use this feature of smart grid to identify the causes of voltage fluctuation, which enables power companies to reduce the fluctuation leading to line fault, so as to effectively improve their asset utilization.Smart grid can also promote the development of renewable energy. Let's see how to:3. Renewable energy managementAs mentioned earlier, the Internet of things introduces a two-way interactive system into the existing distribution channels. This means that the Internet of things system can not only provide power for users, but also allow power companies and consumers to share information.In other words, even end users can now contribute to the smart grid.The biggest advantage of using smart grid is its ability to integrate renewable energy into the existing grid. Therefore, end consumers who use solar panels to power their household appliances can release excess power into the grid in exchange for money. Many countries, such as the United States and India, are providing subsidies to end consumers to help them build small solar power stations on roofs.This is conducive to the large-scale adoption of renewable energy. In addition to alleviating energy shortage, it can also help reduce greenhouse gas emissions. Since smart grids are a stable infrastructure for maintaining voltage fluctuations, they can be used to manage the current generated by renewable energy and conventional methods.My personal opinion:"According to the report of markets and markets, the Internet of things in the energy market is expected to grow at a rate of 24.1% and reach US $22.34 billion by the end of 2020."This shows the potential of the Internet of things in the field of power transmission and distribution. Its implementation will help promote our energy demand and reduce our energy consumption to a great extent. (from IOT home) according to a study of environmental impact assessment (EIA), the United States has reduced its coal energy consumption for power generation by 14% to 22% through the effective use of existing Internet of things technologies.Similarly, as smart consumers, we can also implement smart meters and Internet of things based energy monitoring solutions in our homes to monitor overall power consumption and manage demand accordingly.This may be the first step in enjoying unlimited power. Let's join the revolution of the Internet of things and contribute to a sustainable future.
Design of EMI Filter Power Supply
Design of EMI Filter Power Supply
The function of EMI filter is bi directional, which can not only effectively prevent external electromagnetic interference from entering the equipment through the power line, but also prevent the electromagnetic disturbance generated in the operation of the equipment from entering the power grid through the power line and transmitting it to other sensitive equipment. Therefore, it is a device used in anti-interference and interference suppression.In the figure, the two coils of the inductor are wound on the same magnetic core (both ends of the same name are on the left side of the coil). This wiring cancels the magnetic flux generated by the differential mode current (including the power supply current) and will not produce magnetic circuit saturation; For the common mode current, a large inductance is reflected to achieve large filtering effect, so this inductance is called common mode inductance. This structural feature of the filter shows that it is used to deal with common mode interference to a great extent. For a certain size filter, after the magnetic core is selected, the inductance of the inductance coil will depend on the wire diameter of the wire used. The wire diameter with small current is smaller, the number of coil turns can be a little more, and the inductance will be a little larger; On the contrary. Its typical value is a few MH to a few tenths of MH.Since the two coils cannot be completely symmetrical, the magnetic lines of force generated by the two coils will not be all concentrated in the magnetic core, resulting in a part of irreducible leakage flux, resulting in the existence of a certain parasitic differential mode inductance, which is good for overcoming differential mode interference (since leakage inductance can remove differential mode interference, it is hoped to have a moderate leakage inductance). The inductance of parasitic differential mode inductance can be measured from the outgoing side of the two coils when the incoming side of the two coils is shorted to each other. The inductance varies with the shape of the common mode choke and the winding method. Generally speaking, it is 0.1% - 1% of the common mode inductance.Since the supply voltage is applied to the two coils of EMI common mode inductance, the insulation characteristics are also important. Therefore, the shape shown in the figure below is mostly used, which is beneficial to leakage inductance and insulation withstand voltage.Common mode interference: current disturbance caused by potential difference. Disturbance to ground is called common mode interference.C2 and C6 are located between the live line and the zero line and are used to attenuate differential mode interference, so they are called differential mode capacitors. The capacitance has no adverse effect on the equipment because it relates to the capacitive differential mode current in the line used. The withstand voltage of capacitor is equivalent to the voltage of live line and zero line. Commonly used 250VAC cbb (polypropylene) capacitor, typical value is tens to hundreds of NF. Generally, a resistor with a resistance value of 1m Ω will be connected in parallel at both ends of the capacitor to discharge the static charge on the capacitor and prevent the capacitor from discharging through the human body and causing personal electric shock when unplugging the power supply. This resistance is not required.X (C2, C6) capacitor and common mode inductor form Pai filter circuit, which mainly solves EMI, conduction, secondary emission, etc. The pin spacing of X capacitor, i.e. safety spacing, is required in the safety regulations. The maximum x capacitance shall not be greater than 1.5uf.Note: when there is no common mode inductance, the power supply returns to the N line through fuse, diode and ground. It can be seen that there is no resistance in the circuit. At the start-up time, the capacitance is equivalent to a short circuit, which will produce surge; Due to the existence of common mode inductance, it can effectively suppress the surge current. The common mode inductance plays the role of reactance at startup, makes the capacitor charge slowly, and plays the role of protecting components and insurance.C5 and C10 are located at live line to ground and zero line to ground, and are used to attenuate common mode interference together with common mode inductance, so they are called common mode capacitance. Because they involve the inspection of DC withstand voltage and power frequency withstand voltage, the capacitor withstand voltage shall be at least 3KVDC. At the same time, it also involves the problem of leakage current to the ground, so the capacitance is limited and can not be arbitrarily large, which is generally 1-4nf (typical value is 2.2nf).Y (C5, C10) capacitance: X capacitance for L, n differential filtering; 50. Y capacitance for filtering between N and ground.The circuit structure of EMI filter only determines its low-frequency characteristics (equivalent to the action of a low-pass filter). In order to improve the high-frequency characteristics of the filter, the key is to pay attention to its manufacturing process.For example, the main reasons for poor high-frequency characteristics are: A. poor structure, resulting in high-frequency coupling between input and output. B. The high frequency characteristics of the selected devices are not good.Generally, the structural design of EMI filter circuit requires to follow one direction. When space allows, the inductance and capacitance should keep a certain distance.In terms of device selection, in order to control the distributed capacitance of the inductor, the inductor shall be wound in a single layer as far as possible. If necessary, multiple inductors can be connected in series to achieve the required inductance. For the lead of the capacitor, it is required to be short ("short" means that the lead inductance is small). Capacitors with small parasitic inductance and inductors with small parasitic capacitance shall be selected; During welding, the lead of capacitor shall be as short as possible. Here, the common mode capacitor is particularly important to ensure the common mode filtering characteristics. In practical use, the frequency of common mode interference is relatively high, so the selection of the characteristics of common mode capacitor is the key. In addition to using high-frequency ceramic capacitors, there are also three terminal capacitors and through core capacitors on the market, which is very helpful to improve the high-frequency characteristics of the filter. In addition, the ground wire of the filter should be thick and short, and ensure that it is connected with the ground with low impedance.EMI common mode inductance suppresses the interference to ground. The size of common mode inductance and X capacitance and Y capacitance shall be adjusted after field test. The principle of common mode inductance suppressing common mode current is that if interference occurs on line L, the magnetic field will change, and the magnetic field on line n will also change, which also suppresses the interference. 50. N there will be no potential difference and no current disturbance caused by potential difference.What if the secondary shot can't pass during the test? The solution is to increase the common mode inductance and X capacitance. But if the X capacitance is too large, the leakage current will become larger. The same can't pass the secondary shot. There is a standard for leakage current in the national standard. For wet places, the leakage current can be larger, and the standard is less than 0.76ma. For places with dry noise, it is required to be less than 0.2 mA.When wiring at the transformer and MOS tube, it covers the ground and is connected to the ground of Y capacitor. This is of great benefit to EMI suppression.EMI filter is more suitable for high-frequency conducted interference, but not for lightning surge interference. Therefore, in order to suppress the interference of lightning surge, interference absorbing devices such as varistors must also be used.Selection of capacitor C7 withstand voltage: 220V * 1.414 = 311V, allowance is reserved, and the capacitor is 450V.The insurance requires a slow break type. T stands for slow break type.
Nine Precautions for Small Power UPS Power Supply
Nine Precautions for Small Power UPS Power Supply
1、 Estimate the power of UPS power supplyCalculate the total power consumption of the equipment according to the power consumption of the microcomputer and its external equipment. The total power consumption multiplied by the safety factor is the estimated power of UPS power supply. The safety factor is generally 1.2-1.3.2、 Selection of domestic and imported UPS power supplyIn the selection of domestic and imported UPS power supply, it is generally recommended to select domestic UPS power supply. In recent years, the quality of domestic small UPS power supply has been greatly improved. The selection of domestic small UPS power supply, on the one hand, is to support the domestic economic and technological development, on the other hand, it is very convenient in maintenance, such as complete spare parts, satisfactory maintenance capacity and speed. The quality of imported UPS power supply is generally good, but due to the difficulties in maintenance technology and spare parts, once it fails, it can not be repaired in time and can not be used for a long time. In terms of working performance, domestic UPS power supply is more in line with domestic power supply conditions. For example, some models of u and UPS power supply have a wide input voltage range and have voltage stabilizing output function, which can adapt to some environments with poor power supply conditions in China. The policy of adopting domestic UPS power supply is undoubtedly a good start in the construction of the electronic project of the people's Bank of China.3、 Selection of on-line and backup UPS power supplyThe selection of on-line or backup UPS power supply shall be determined according to the needs and economic conditions of microcomputer equipment. If the economic conditions are good, online UPS power supply can be selected; If the economic conditions are poor without affecting the normal operation of the microcomputer, the backup UPS power supply can also be selected.4、 Selection of UPS power supply for long-time power supply and short-time power supplyIn the selection of UPS power supply for long-time power supply and UPS power supply for short-time power supply, it mainly depends on economic conditions and use needs. With good economic conditions, long-term UPS power supply can be selected, otherwise short-term ups power supply plus small generator set can be selected as standby power supply.5、 Understand the power supply status of UPS power supply siteBefore selecting the UPS power supply, understand the power supply status of the site where the UPS power supply is used. The requirements of general UPS power supply for mains power input are: input voltage 38ov ± 10%, 220V ± 10%; The frequency is 50 ± 0.5Hz. If the power supply condition of the site is lower than this standard, another UPS power supply with wide input range shall be selected, or a regulated power supply or voltage regulating device can be added at the front end of the UPS power supply.6、 Problems needing attention in selecting backup UPS power supplyWhen selecting backup UPS power supply, special attention shall be paid to the switching time of power supply. The switching time mainly reflects the switching time of UPS power supply and the requirements of microcomputer for switching time. If it is not selected properly, the microcomputer will be shut down in case of mains power failure, which will not play the role of APC UPS power supply.7、 We should "shop around" and choose the bestAt present, there are many manufacturers and sellers of small UPS power supply, the product quality is good and beautiful, and the price difference is also great. Therefore, we should consult and investigate more, and carefully compare the technical indexes and performance price ratio of different products; Do "shop around" and choose the best.8、 Problems needing attention in selecting imported UPS power supplyThe wiring mode of input and output of some imported UPS power supplies is different from that in China. Attention should be paid to the improved method when selecting. The input and output wiring mode of UPS power supply in the United States, such as pulse and exide, is opposite to that of Chinese standards. In short, China's single-phase power supply is left zero and right fire, while the United States is left fire and right zero. In addition, it should be noted that the style of American standard socket plug is also different from that in China. When the American national standard plug and socket is changed to China's national standard plug and socket, we should pay attention to the internal joint relationship and can't simply adjust the line.9、 Convenience in maintenance is also a factor in model selectionFailure of UPS power supply is a normal phenomenon. During model selection, the convenience of maintenance is also a factor that can not be ignored, otherwise it will bring inconvenience to maintenance in use.
Characteristics and System Structure of High Frequency Switching Power Supply
Characteristics and System Structure of High Frequency Switching Power Supply
High frequency switching power supply (also known as switching rectifier SMR) works at high frequency through MOSFET or IGBT, and the switching frequency is generally controlled in the range of 50-100khz to achieve high efficiency and miniaturization.High frequency switching power supply system is usually composed of four parts: AC distribution module, rectifier module, DC distribution module and centralized monitoring module.1. The AC power distribution module processes, protects and monitors the AC power supply and interfaces with the rectifier module.2. The rectifier module changes AC to DC.3. The DC power distribution module is responsible for supplying power to the DC load.4. The centralized monitoring module is used to intelligently manage the AC input power supply, rectifier module, output power supply and battery pack, and realize data monitoring, constant value setting and out of limit alarm. Rs-232ct and RS-485 serial communication interfaces are also set to realize remote signaling, telemetry, remote adjustment and remote control.characteristic:This product is made of imported famous brand components and international advanced full bridge inverter technology, so that the performance of the whole machine is stable and the quality is more reliable.2. The whole machine has the functions of over-voltage, over-current, over temperature, short circuit, lack of equality, automatic protection alarm and soft start. Time control and computer interface can be added.3. The DC output waveform is a high-frequency square wave with a ripple coefficient of 1%, which can improve the number of plating, refuse passivation, enhance the gloss of the coating surface and the core drilling of the dark angle of the plated parts, reduce the loss of raw materials and meet various special requirements of the electroplating industry.4. The high-frequency switching power supply adopts air-cooled design, which is easy to install. It is equipped with remote control device, which is simple to operate. It can switch the machine with load and reduce the cumbersome procedure of adjustment.With small volume and light weight, the whole machine is made by all-round anti-corrosion technology, which enhances the anti-corrosion ability of the product and prolongs the service life.6. High efficiency, energy saving, work efficiency of more than 90%, and any voltage current ratio always matches linearly. It saves the loss of voltage regulator and main transformer of traditional rectifier, saves energy by more than 35%, and greatly reduces the electroplating cost. In fact, it is the most rational choice in the surface treatment industry.Recommended reading: http://m.elecfans.com/article/721173.html
Disconnect the Power Cord and Decrypt the Mystery of USB Power Supply
Disconnect the Power Cord and Decrypt the Mystery of USB Power Supply
USB is one of the most widely used transmission interfaces in the daily life of ordinary modern people. Due to the convenience, small size and reasonable cost of USB interface, USB can be seen everywhere in different life or work fields. Whether it is the core entertainment device in the family - TV, personal laptop / smart phone / lithography device, working computer / printer in the office, and even the vehicle mounted information communication and entertainment system in the car, all rely on USB for data transmission.In addition to providing convenient, fast and reliable data transmission, USB also has a very convenient function, that is, power transmission through the interface, that is, the so-called charging. However, the current USB charging can only provide up to 7.5 watts of power; Referring to figure 1, we can understand the power transmission limitations of various mainstream USB technical specifications. At this stage, USB 2.0 specification can transmit 2.5 watts of power (providing 500mA current through 5V voltage), USB 3.0 specification can transmit 4.5 watts of power (providing 900 ma current through 5V voltage), and battery charging 1.2 allows 7.5 watts of power (provide 1500 ma current through 5V voltage). Although such power supply specification evolution can meet the charging requirements of portable devices such as mobile phones or MP3, it usually takes a long time, and it is not enough to meet the power supply of large-size products that need to consume large power, such as screen displays or notebook computers.100 watt power delivery creates the possibility of diversified applicationsIn order to popularize the application of USB in power supply of different devices and reduce the configuration of power cord, a new USB power delivery came into being. Usb-if recently announced this project called USB power delivery (PD) The purpose of the power transmission specification is to enable various devices to meet the power supply demand through a single USB cable through the power transmission capacity of up to 100 watts, shorten the charging time of the device, and optimize the convenience of mobile applications. Its basic technical architecture is shown in Figure 2 Through the power storage function in the chipset, the power can be temporarily stored and transmitted to the devices that need power. At the same time, the power delivery has the characteristics of two-way, allowing the devices to charge while transmitting data. The time-saving and convenient method further improves its use efficiency, eliminates the need for traditional power lines and unifies the power wires.Taking the practical application scenario in Figure 3 as an example, in the traditional use scenario, the host, as the power supplier, can provide power to the connected screen display, laptop, or hard disk; while the mobile phone and hard disk, as the power supplier, can eat the power of the host or laptop; if both the screen display and laptop support USB power delivery, the screen display will be displayed under this technical architecture Both the display and the laptop can be both the power supplier and the powered one. Therefore, when the laptop is low or does not carry a power supply, it can supply power through the screen. When the screen needs power, it can also supply power through the host or laptop. These two can also transmit power through the USB interface and communicate with other devices such as mobile phones and hard disks when they need power At the same time, it can still carry out the task of data transmission. The flexible application of such two-way also makes the specification of USB power delivery a new technology application expected by all manufacturers.Complete supporting facilities to ensure seamless connection of technologiesThe technical specification of USB power delivery was officially formulated by the USB 3.0 and USB 2.0 promotion team in July 2012. At present, the specification version is 1.0, which can be compatible with the two mainstream specifications of USB 2.0 and 3.0 at the same time. At present, it has been placed on the usb-if website for download. In order to make this technology seamlessly connect with the existing USB specification and the whole application ecosystem, USB power delivery The design pays special attention to compatibility and reliability, so it has the following characteristics:*It can operate completely on the existing USB device.*Compatible with existing USB 2.0 and USB 3.0 cables and connectors that meet the specifications.*It is forbidden to act on illegal cables (such as y cable, which is common in the market), so the risk and potential damage factors to the device can be reduced.*The design architecture of high efficiency and low cost is adopted at the transmitter and receiver. The power management mechanism can adjust the power supply between different devices, so as to optimize the work efficiency*The voltage and current values between USB devices can be communicated through the existing VBUS pin without additional complicated device settings.*The source and sink can be interchanged. They are two-way power supply and have high elasticity in power transmission.*It can coexist with the current USB battery charging 1.2 without conflict.It can be seen that USB power delivery not only provides a strong vision of power supply, but also pays attention to whether manufacturers can smoothly import PD function in the simplest way and without consuming a lot of cost at the level of practical application; and whether users can directly enjoy the convenient experience brought by PD under the condition of least adaptation.Easy to use market popularity is just around the cornerIn terms of the market situation, in addition to Intel as the main technology proponents, Texas Instruments (TI) and SMSC will also be the pioneers of the chip specification to develop the USB power delivery chipset; and the power chipset will also include on semiconductor and NXP The International Consumer Electronics Show (CES), which just ended at the beginning of this year , usb-if has also demonstrated the actual technical application in the meeting. Through a screen display connected to power and conforming to the USB power delivery function, it can supply power to a laptop with a power of 65 watts through USB cable, and can be connected with another screen as an extended desktop display. Through such a simple display, people can have unlimited imagination of its application.In the dispute over high-speed transmission interface, although thuderbolt has a faster transmission speed than USB, USB has found another way in function. The great leap forward in power supply capacity has created a more convenient use situation in the future. In addition, the cost advantage of USB interface and the high acceptance of consumers in the whole market will inevitably continue to occupy the dominant position in the market in the short term. I believe that in the future In the long future, the logo of USB power delivery (as shown in Figure 4) will gradually penetrate all kinds of electronic products and application fields.
Is It Possible to Use a ULN2003A Darlinghton Array Instead of Multiple TIP120 Transistors?
Is It Possible to Use a ULN2003A Darlinghton Array Instead of Multiple TIP120 Transistors?
For the most part, yes, the ULN2003A will work in this circuit, but with some caveats.The VCE(sat) is slightly higher for the ULN2003A vs the TIP120, which means the LEDs will have slightly less voltage across them (and so slightly dimmer). But that may not matter for your application.My biggest concern is the total current through the ULN2003A chip when all three LEDs are on. Figure 14 of the datasheet shows the maximum current you can drive through each of the Darlington pairs. As you can see, if you have all three LEDs on at 100% duty cycle, each color can only draw a little more than 150mA. That's 450mA total. Any more than that and the chip will overheat. It's important to get a handle on how much current your LED strip pulls.If, as you said in your comment, the strip is 1.5W with a 12V power supply, then presumably that translates to 125mA total. If that's true, you're probably ok then.EDIT: You indicated you're using a 5V power supply. Since your LED strip is sized for 12V, the LEDs may not even light up. Especially the blue LED. If they do light up, they'll be significantly dimmer than they were designed to be.Looking at the datasheets, I'm not sure their specifics match;TIP127 and ULN2003AMy intention is to do something like this, but with the ULN2003A, that I have already:The reason why is that I want to remove the provided driver/power supply (5V 12V, driving 6 LEDs 0,25W each) and use PWM with the RPi to dim the strip's leds (using an external 5V power supply). I've already done this to regulate a 12V fan (but I understand this is another story).·OTHER ANSWER:Looking at the datasheets, I'm not sure their specifics match;TIP127 and ULN2003AMy intention is to do something like this, but with the ULN2003A, that I have already:The reason why is that I want to remove the provided driver/power supply (5V 12V, driving 6 LEDs 0,25W each) and use PWM with the RPi to dim the strip's leds (using an external 5V power supply). I've already done this to regulate a 12V fan (but I understand this is another story).
Application and Development of High Frequency Switching Power Supply
Application and Development of High Frequency Switching Power Supply
On ApplicaTIon and Development of High- frequency SMPS1 block diagram of high frequency power supply systemHigh frequency switching rectifier generally converts AC directly into DC through diode rectification and filtering, and then into high-frequency AC through switching power supply. After voltage transformation and isolation through high-frequency transformer, it is output after fast recovery diode high-frequency rectification and inductor capacitor filtering, as shown in Figure 1.Figure 12. High frequency is adopted, with high technical and economic indicatorsTheoretical analysis and practical experience show that the volume weight of electrical products is inversely proportional to the square root of power supply frequency. Therefore, when we increase the frequency from power frequency 50Hz to 20kHz, the volume and weight of electrical equipment are generally reduced to (5 10)% of power frequency design. This is the basic reason for the obvious benefits brought by the realization of frequency conversion of switching power supply. Inverter or rectifier welding machine and switching rectifier of floating charge power supply for communication power supply are all based on this principle.Then, based on the same principle, the traditional DC power supplies such as electroplating, electrolysis, electromachining, floating charge and power switching on are transformed into "switching power supply", which can save 90% or more of its main materials and 30% or more of its power. Due to the gradual increase of the upper limit of the working frequency of power electronic devices, many traditional high-frequency equipment using electronic tubes are made solid, which can not only bring significant economic benefits of energy saving and material saving, but also reflect the value of technical content.3. Modular design - free combination and capacity expansion, mutual standbyImprove safety factorModularization has two meanings, one is the modularization of power devices, the other is the modularization of power supply units. In fact, due to the continuous increase of frequency, the influence of lead parasitic inductance and parasitic capacitance becomes more and more serious, causing greater stress to the device (manifested as overvoltage and overcurrent Burr). In order to improve the reliability of the system, the relevant parts are made into modules.The driving and protection circuits of switching devices are also installed in the power module to form an "intelligent" power module (IPM), which not only reduces the volume of the whole machine, but also facilitates the design and manufacture of the whole machine.Multiple independent module units work in parallel and adopt current sharing technology. All modules share the load current. Once one module fails, other modules share the load current equally. In this way, it not only improves the power capacity and meets the requirements of high current output when the device capacity is limited, but also greatly improves the system reliability by adding redundant power modules with small power relative to the whole system. Even if a single module failure occurs, it will not affect the normal operation of the system, and provides sufficient time for repair.4. Product specification of high frequency switching power supply(see Table 1 and table 2)Table 1 power 500W 3000WTable 2 power 5000W 20000wThe weight of the above products is only 1 / 5 1 / 8 of the weight of traditional products.5 development of IGBT inverter welding machine at home and abroadIGBT inverter welding machine has the advantages of good dynamic characteristics, small volume, light weight, high efficiency and energy saving, material saving and conducive to welding automation. Since the 1970s, it has been highly valued by the welding machine industry at home and abroad. Nowadays, many industrial countries, such as the United States and Western Europe, apply "insulated gate bipolar transistor" (IGBT) to welding machines. Its indexes are better than other types of welding machines. It has formed a scale, occupied the market and become the development direction of welding machines. At present, most of the welding machines imported from China are such welding machines.According to relevant statistics, in recent years, the annual sales volume of welding machines in China has increased at a rate of about 40%. At the same time, relevant departments have decided to eliminate old-fashioned welding machines. IGBT inverter welding machines have become the preferred products for users to update with their advantages.5.1 principle block diagramSee Figure 2Figure 25.2 principle description380 (220) V AC, rectified into DC power supply through full bridge; High frequency rectangular wave of 20kHz is formed through IGBT inverter; Then, it is reduced from high-frequency transformer to tens of volts, and becomes DC welding power supply through fast recovery diode rectification and filtering.5.3 main advantages of IGBT welding machine:·Good dynamic characteristics and high welding quality·Small size and light weight·Low noise·High efficiency and energy savingIn recent years, many manufacturers in China are engaged in the development and production of IGBT welding machines. Compared with imported products, domestic welding machines have the advantage of low price. However, due to various reasons, the domestic IGBT inverter welding machine has different degrees of problems in design technology, manufacturing process and component reliability, resulting in a high failure rate. So far, no manufacturer's products have established a reliable product image in the eyes of the majority of users. It can be said that "Whoever can make a breakthrough, master high-quality products and solve the reliability problem of domestic IGBT welding machines can occupy this market".6 power intelligent high frequency switching rectifierAt present, most of the DC power supply equipment used in power plants, hydropower stations and 500kV, 220kV, 110KV, 35kV and other substations in China (including power for circuit breaker opening and closing, backup battery charging, secondary circuit instruments and meters, relay protection, control of emergency light lighting and other low-voltage equipment), are phase controlled power supply or magnetic saturation power supply, Due to the limitations of process level and device characteristics, the above power supply has been in the situation of low technical indicators and difficult maintenance for a long time. Due to the limitation of the parameters of the transformer or thyristor, the above power supply has many shortcomings, such as unstable initial charging current and floating charging current, too high system ripple voltage, poor control characteristics, inconvenient to be connected with the computer system to realize monitoring, etc. At the same time, at present, the charging equipment operates in parallel with the battery. When the ripple coefficient of the power supply is large and the floating charge voltage fluctuates or is low, there will be pulsating charging and discharging of the battery, resulting in premature damage of the battery pack or monomer. In addition to the defects in many technical indicators, the above power supply also has shortcomings such as large volume, low efficiency and large 1 1 redundancy investment. It should be said that it is far from meeting the needs of the rapid development of power engineering. With small volume, light weight, high efficiency, low output ripple, fast dynamic response, high control accuracy, module superposition output It is a general trend for high-frequency switching power supply characterized by N 1 redundancy to gradually replace phase controlled power supply or magnetic saturation power supply. In particular, the rapid development of power electronics technology and the improvement of power device manufacturing technology in recent ten years have made the reliability and application of high-frequency switching power supply much better than phase controlled power supply and magnetic saturation power supply. Therefore, after the 1990s, the United States Germany and other western developed countries have adopted high-frequency switching power supply for all relevant equipment of new power plants and substations, and completed the transformation of old power supply equipment. The module adopts three-phase three wire 380V balanced input withoutTable 4 characteristics and technical parameters of high frequency power moduleTable 5 Comparison between high frequency switching power supply DC system and conventional power supply DC systemShenzhen Xinneng Technology Co., LtdAfter decades of development, the national power industry has made remarkable achievements. DC operating power supply has also experienced from magnetic saturation power supply to thyristor power supply to current high-frequency switching power supply. Each progress in the development process is a revolution in the field of power application.High frequency switching rectifier technology is a high-tech project with priority development issued by the state. New capability Technology Co., Ltd. has always been at the forefront of high-frequency switch technology, combined with national conditions, developed high-frequency switch rectifier series products to meet the needs of the market to the greatest extent, and has been listed as a key enterprise supported by the Ministry of science and technology of the people's Republic of China.The new capability company not only provides products with reliable performance and rich varieties and specifications, but also contains excellent service concept. Taking the realization of national industry as its responsibility, it has become a new force in the field of power high-frequency switch rectification, reflecting the new capability of Chinese people!For the loss of neutral current, at the AC input end, advanced peak suppression devices and EMI filter circuit are adopted. The three-phase AC is rectified into DC by the full bridge rectifier circuit, and then the obtained DC is inverted into a stable and adjustable DC output by the DC / DC high-frequency conversion circuit (300kHz). Pulse width modulation circuit (PWM) and soft switching resonant circuit automatically adjust the pulse width and phase shift angle of high-frequency switch according to the changes of power grid and load, so that the output voltage and current can remain stable under any allowable conditions.7 development trend of switching power supplyIn the application of power electronics technology and basic power supply system, switching power supply technology is in the core position. The traditional phase controlled power supply is very large and bulky, such as inverter welding machine, communication power supply, high-frequency heating power supply, laser power supply and electric operation power supply. If the high-frequency switching power supply technology is adopted, its volume and weight will be greatly reduced, and it can greatly improve the utilization rate of electric energy, save materials and reduce costs. In electric vehicles and AC drives, switching power supply technology is indispensable. Switching power supply changes the power frequency, so as to achieve almost ideal load matching and drive control.Now, the switching power supply technology is in the ascendant, and in recent years, it has been promoted by the large market demand, which will bring the great development of switching power supply technology. In recent years, with the development of the communication industry, the communication power supply with switching power supply technology as the core will have a large market demand in China. It is a general trend for switching power supply to replace linear power supply and phase controlled power supply. Therefore, the domestic market of power operation power supply system with the demand of billions of output value is starting and will develop soon. Many other special power supplies and industrial power supplies with switching power supply technology as the core will also develop rapidly.
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