Inverter emergency power inverter supply capability test is a verification method of providing DC power to the inverters to ensure that the required emergency power supply capability of the inverters can be achieved when the emergency power supply mode of the inverters is running. During the test, the main power supply is cut off to make the emergency power supply work in the emergency power supply mode. Under the condition that the voltage of the intermediate DC circuit is not lower than the rated value, the resistance load with the same capacity is applied at the output end, and the time duration of the output power is measured and recorded during the operation of the equipment. It should not be shorter than the prescribed emergency power supply time. For equipment using only batteries (batteries) as DC power supply, this test can be omitted after the previous test.
Batteries (batteries) are used as emergency power supply for DC inverters. Energy recovery time test is needed. During the test, the battery (group) is discharged to make its voltage lower than the cut-off voltage, the emergency power supply is connected to the main power supply that meets the requirements, and the built-in charger of the emergency power inverter supply is charged automatically with constant current. At this time, the initial charging current should be measured in accordance with the charging specifications stipulated by the battery (group) supplier. Constant current requirement. The time required for charging should meet the stipulated time, that is, the time required for the emergency power supply with the capacity of 100 kW or less should not exceed 24 hours, and the time required for the emergency power supply with the capacity of 100 kW or more should not exceed 72 hours. To disconnect the charging circuit of the battery (group) and measure the charging voltage, it should meet the constant voltage requirements of the battery (group) supplier’s charging specifications. If necessary, the charge can be verified by the re-discharge test.
Through the corresponding method, power inverter after the test, check whether the built-in charger has the required functions according to the requirements. If it is an external charger, the test of the charger shall be carried out according to the corresponding standards, but for the charging function of the batteries (batteries) of the inverter emergency power supply, it shall be carried out in accordance with the provisions of this standard.

The DC switching power inverter supply uses high-speed conduction and cut-off through the circuit control switch tube, and the AC power is supplied to the transformer for voltage transformation into high-frequency DC power, thereby generating one or more sets of voltages required! The reason for the conversion to high-frequency AC is that the efficiency of high-frequency AC in the transformer transformer circuit is much higher than that of 50HZ, so the switching transformer can be made very small, and it is not very hot when working! The cost is very low. If you do not turn 50HZ into a high frequency, then there is no point in switching the power supply.
working principle

1. The AC power inverter input is rectified and filtered into DC;
2. Control the switching tube by high frequency PWM (pulse width modulation) signal, and add that DC to the primary of the switching transformer;
3. The secondary of the switching transformer induces a high-frequency voltage, which is supplied to the load through rectification and filtering;
4. The output part is fed back to the control circuit through a certain circuit to control the PWM duty cycle to achieve the purpose of stable output. When the AC power input is input, it generally passes through something like the E-flow circle to filter out the interference on the power grid and also filter out the interference of the power supply to the power grid. When the power is the same, the higher the switching frequency, the smaller the volume of the switching transformer. However, the requirements for the switching tube are higher; the secondary of the switching transformer can have multiple windings or one winding with multiple taps to obtain the required output; generally, some protection circuits, such as no-load, short-circuit, etc., should be added. Otherwise, the switching power supply may be burned out. Mainly used in industry and some household appliances, such as televisions, computers, etc.
   DC switching power supply
   Straight and main circuit The entire process from the AC grid input, DC output:
5. Input filter: Its function is to filter the clutter existing in the power grid, and also hinder the clutter generated by the machine from being fed back to the public power grid.
6. Rectification and filtering: The AC power supply of the power grid is directly rectified into a smoother DC power inverter for the next level of transformation.
7. Inverter: The rectified DC power is changed into high frequency AC power, which is the core part of the high frequency switching power supply. The higher the frequency, the smaller the ratio of volume, weight and output power.
8. Output rectification and filtering: Provide stable and reliable DC power supply according to load requirements.
   Application characteristics
9. Reduce the porosity, the formation speed of the crystal nucleus is greater than the growth rate, and promote the refinement of the crystal nucleus.
10. Improve the bonding force and break through the passivation film, which is beneficial to the firm bonding between the substrate and the plating layer.
11. Improve coverage and dispersion ability. The high cathode negative potential can also deposit the passivated parts in ordinary electroplating, and slow down the “scorch” and “dendritic” caused by the excessive consumption of deposited ions. The defects of deposition can be reduced to 1/3~1/2 of the thickness of the coating (for example, color, no porosity, etc.) for a given characteristic, saving raw materials.
    4, reduce the internal stress of the coating, improve lattice defects, impurities, voids, tumors, etc., easy to obtain crack-free coating, reduce additives.
    5, is conducive to obtaining a stable alloy coating.
12. Improve the dissolution of the anode without the need for an anodic activator.
13. Improve the mechanical and physical properties of the coating, such as increasing the density, reducing the surface resistance and bulk resistance, improving the toughness, wear resistance, corrosion resistance and controlling the hardness of the coating.
    High frequency switching DC power inverter supply
    The high-frequency switching DC power supply is based on high-quality imported IGBT as the main power device, and the ultra-microcrystalline (also known as nanocrystalline) soft magnetic alloy material is the main transformer core. The main control system adopts multi-loop control technology, and the structure adopts prevention. Salt spray acidification measures. The power product has a reasonable structure and high reliability. The power supply has become a new generation of thyristor power supply with its small size, light weight, high efficiency and high reliability. Suitable for various precision surface treatment sites such as experiment, oxidation, electrolysis, galvanizing, nickel plating, tin plating, chrome plating, photoelectric, smelting, chemical formation and corrosion. It has also been well received by users in anodizing, vacuum coating, electrolysis, electrophoresis, water treatment, electronic product aging, electric heating, and electrochemistry. Especially in the field of PCB, electroplating and electrolysis, it has become the power supply of choice for many customers.

The electrical performance of the module power supply is presented through a series of tests. The following are general functional test items, as detailed below:
Line Regulation
Load Regulation
Conmine Regulation
Output ripple and noise (Ripple & Noise)
Input power inverter , Efficiency (Input Power, Efficiency)
Dynamic load or transient load (Dynamic or Transient Response)
Set-Up and Hold-Up time
General function (Functions) test
1, power adjustment rate
Power regulation is defined as the ability of a power supply to provide its regulated output voltage as the input voltage changes. The test procedure is as follows: After the heat supply is stabilized under normal input voltage and load conditions, the power supply is measured and recorded under low input voltage (Min), normal input voltage (Normal), and high input voltage (Max). Output voltage value. The power regulation rate is usually a percentage of the output voltage deviation caused by the input voltage change under a normal fixed load (Nominal Load), as shown in the following formula:
[Vo(max)-Vo(min)] / Vo(normal)
2, load adjustment rate
Load regulation is defined as the ability of a switching power supply to provide a stable output voltage when the output load current changes. The test procedure is as follows: after the heat supply of the power supply to be tested is stable under normal input voltage and load conditions, the output voltage value under normal load is measured, and then measured under light load (Min) and heavy load (Max) load respectively. Record the output voltage values ??(Vo(max) and Vo(min), respectively). The load regulation is usually the percentage of the output voltage deviation caused by the load current change at a normal fixed input voltage, as shown in the following formula. :
[Vo(max)-Vo(min)] / Vo(normal)

1. Comprehensive adjustment rate
   The integrated regulation is defined as the ability of the power inverter supply to provide a stable output voltage when the input voltage and output load current change. This is a combination of power regulation and load regulation. This test is a combination of the above power regulation and load regulation, which provides a more accurate performance verification of the power supply under varying input voltage and load conditions. The comprehensive adjustment rate is expressed in the following way: under the input voltage and output load current change, the deviation of the output voltage shall be within the specified upper and lower voltage range (ie, within the absolute value of the upper and lower limits of the output voltage) or within a certain percentage limit. .
   4, output noise
   Output noise (PARD) is the voltage value of the periodicity and random deviation of the average DC output voltage when the input voltage and the output load current are constant. The output noise is all the unwanted AC and noise components on the regulated and filtered DC output voltage (including the low frequency 50/60Hz power frequency multiplier signal, the high frequency switching signal above 20 KHz and its harmonics). Waves, which are combined with other random signals)), are usually expressed in units of peak voltages in mVp-p peaks.
   The specifications of general switching power supplies are within the specification of output noise of less than 1% of the output DC output voltage, and the bandwidth is 20Hz to 20MHz. The worst case of the actual operation of the power supply (such as the maximum output load current, the lowest input power inverter supply voltage, etc.), if the power supply is in a harsh environment, its output DC voltage plus the instantaneous output voltage after the noise can still maintain stability. The output voltage does not exceed the output high and low voltage limit. Otherwise, the power supply voltage may exceed or fall below the logic voltage of the logic circuit (such as TTL circuit) and cause malfunction.
   At the same time, the measuring circuit must have good isolation processing and impedance matching. In order to avoid unnecessary interference, ringing and standing waves on the wires, the double coaxial cable is generally used with 50Ω at its end point, and the differential amount is used. The measurement method (which avoids the noise current of the ground loop) is used to obtain the correct measurement result.
   5, input power and efficiency
   The input power inverter of the power supply is defined as the following formula:
   True Power = Pav(watt) = Vrms x Arms x Power Factor is the integral value of the product of the input voltage and current in one week. Note that Watt≠VrmsArms is Watt=VrmsArmsxP.F., where PF is power. Power Factor, usually no power factor correction circuit power supply power factor is about 0.6 ~ 0.7, the power factor is between 1 ~ 0.
   The efficiency of a power supply is defined as the ratio of the sum of the output DC power to the input power. Efficiency provides verification of the correct operation of the power supply. If the efficiency exceeds the specified range, it means that there is a problem in the design or the material of the part. If the efficiency is too low, the heat dissipation will increase and the service life will be affected.
   6, dynamic load or transient load
   A constant voltage output power supply is designed with a feedback control loop that continuously maintains a stable output voltage from its output voltage. Since the feedback control loop actually has a certain bandwidth, it limits the response of the power supply to changes in load current. If the phase of the control loop input and output is 1 when the gain (Unity Gain) is 1, more than 180 degrees, the output of the power supply will be unstable, out of control or oscillating. In fact, the load current when the power supply is working is also dynamically changing, rather than always maintaining the same (such as hard disk, floppy drive, CPU or RAM actions, etc.), so dynamic load testing is extremely important for the power inverter supply. The programmable electronic load can be used to simulate the worst load conditions in the actual operation of the power supply, such as the rapid rise of the load current, the slope of the drop, the period, etc. If the power supply is under severe load conditions, it can maintain a stable output voltage. Does not produce overshoot or undershoot.

Switching power inverter supplies are widely used in almost all electronic devices due to their small size, light weight and high efficiency. It is an indispensable power supply method for the rapid development of the electronic information industry.
1, should pay attention to when choosing switching power supply
1) Select the appropriate input voltage specifications;
2) Choose the right power. In order to increase the life of the power supply, a model with a maximum output power rating of 30% can be selected.
Switching power supply adapter
3) Consider the load characteristics. If the load is a motor, a bulb or a capacitive load, the current is large when the power is turned on. A suitable power source should be used to avoid overload. If the load is a motor, consider the voltage backflow at shutdown.
4) In addition, it is necessary to consider the working environment temperature of the power inverter supply, and whether there is additional auxiliary heat dissipation equipment. In the case of excessively high temperature, the power supply needs to be derated. The derating curve of the ring temperature to the output power.
5) Select each function according to the application:
Protection functions: over voltage protection (OVP), over temperature protection (OTP), overload protection (OLP), etc.
Application functions: signal function (normal power supply, power failure), remote control function, telemetry function, parallel function, etc.
Special features: power factor correction (PFC), uninterruptible power (UPS)
6) Select the required safety and electromagnetic compatibility (EMC) certification.
2, the use of switching power supply precautions
1) Before using the power supply, first determine whether the input and output voltage specifications match the nominal value of the power supply used;
2) Before power-on, check whether the input and output leads are connected correctly to avoid damage to the user equipment;
3) Check whether the installation is firm, whether the mounting screws are in contact with the power inverter board device, and measure the insulation resistance of the housing and the input and output to avoid electric shock;
4) To ensure the safety of use and reduce interference, please ensure that the grounding terminal is reliably grounded;
5) The power supply of multi-output is generally divided into main and auxiliary outputs, and the main output characteristic is superior to the auxiliary output. Under normal circumstances, the output current is large as the main output. In order to ensure the output load regulation rate and output dynamics and other indicators, it is generally required to have at least 10% load per channel. If the auxiliary road is not used, the main road must be added with a proper dummy load. For details, refer to the specifications of the corresponding model;
6) Please note: Frequent switching of the power supply will affect its life;
7) The working environment and the degree of loading will also affect its life.
3, common faults
Fuse blown
In general, a blown fuse indicates a problem with the internal wiring of the power supply. Due to the high voltage and high current of the power supply, the fluctuations and surges of the power grid voltage will cause the current in the power supply to increase instantaneously and the fuse will be blown. The key points should be to check the rectifier diode of the power input terminal, high-voltage filter electrolytic capacitor, inverter power switch tube, etc., check whether the component has breakdown, open circuit, damage, etc. If the fuse is really blown, you should first check the components on the board to see if the appearance of these components is burnt and there is no electrolyte overflow. If the above is not found, use a multimeter to measure whether the switch has a breakdown short circuit. . It is necessary to pay special attention to: Do ??not directly detect the damage of a component when it is damaged. It is very likely that the other high-voltage components will still be damaged and the replacement components will be damaged. It is necessary to comprehensively apply all the high-voltage components of the above circuit. After the measurement is checked, the fuse blowout can be completely eliminated.
No DC voltage output or unstable voltage output
If the fuse is intact, there is no output of DC voltage at all levels under load. This situation is mainly caused by the following reasons: open circuit, short circuit phenomenon in the power supply, overvoltage, overcurrent protection circuit failure, auxiliary power failure, oscillating circuit not working, power supply overload, rectifier diode in high frequency rectification and filtering circuit It is broken down, the filter capacitor is leaking, and so on. After measuring the secondary component with a multimeter and eliminating the breakdown of the high-frequency rectifier diode and the short-circuit of the load, if the output is zero at this time, it is sure that the control circuit of the power supply has failed. If some of the voltage output indicates that the pre-stage circuit is working properly, the fault is in the high-frequency rectification and filtering circuit. The high-frequency filter circuit mainly consists of a rectifier diode and a low-voltage filter capacitor to form a DC voltage output. The breakdown of the rectifier diode causes the circuit to have no voltage output, and the leakage of the filter capacitor causes the output voltage to be unstable. Statically measure the corresponding component with a multimeter to check the damaged component.
Poor power load capacity
Poor power inverter load capacity is a common fault. It is usually found in old-fashioned or long-running power supplies. The main reason is that the components are aging, the switching tube is unstable, and there is no heat dissipation in time. It is important to check whether the Zener diode is hot or leaky, the rectifier diode is damaged, and the high voltage filter capacitor is damaged.

Switching power inverter supplies are widely used in almost all electronic devices due to their small size, light weight and high efficiency. It is an indispensable power supply method for the rapid development of the electronic information industry.

1. When repairing the switching power supply, first use a multimeter to check whether the power components are short-circuited, such as the power rectifier bridge, the switch, the high-frequency high-power rectifier; whether the high-power resistor that suppresses the inrush current is blown. Then check whether the resistance of each output voltage port is abnormal. If the above components are damaged, they need to be replaced.
2. After the first step is completed, it will not work normally after the power is turned on. Then, the power factor module (PFC) and the pulse width modulation component (PWM) should be detected. Check the relevant information and familiarize with the functions of each pin of the PFC and PWM modules. The prerequisites for the normal operation of the module.
3. Then, for a power inverter supply with a PFC circuit, it is necessary to measure whether the voltage across the filter capacitor is about 380 VDC. If there is a voltage of about 380 VDC, the PFC module works normally, and then the working state of the PWM component is detected, and the power input terminal VC is measured. The reference voltage output terminal VR starts to control whether the voltage of the Vstart/Vcontrol terminal is normal. The 220VAC/220VAC isolation transformer is used to supply power to the switching power supply. The oscilloscope is used to observe whether the waveform of the PWM module CT to ground is a linear sawtooth wave or triangle, such as TL494. The CT end is a sawtooth wave, and the FA5310 has a CT wave at the CT end. Whether the waveform of the output terminal V0 is an ordered narrow pulse signal.
4. In the practice of switching power supply maintenance, many switching power supplies use UC38×× series 8-pin PWM components. Most power supplies cannot work because the power-on resistors are damaged or the performance of the chips is degraded. When there is no VC after R is disconnected, the PWM component cannot work, and the same resistance as the original power resistance needs to be replaced. When the PWM component startup current increases, the R value can be reduced until the PWM component can operate normally. When repairing a GE DR power supply, the PWM module is UC3843, and no other abnormalities are detected. After a 220K resistor is connected to R (220K), the PWM component works and the output voltage is normal. Sometimes due to peripheral circuit failure, the VR terminal 5V voltage is 0V, the PWM component does not work. When the Kodak 8900 camera power supply is repaired, this situation is encountered, the external circuit connected to the VR terminal is disconnected, and the VR changes from 0V. 5V, PWM components work normally, and the output voltage is normal.
5. When there is no voltage of 380VDC on the filter capacitor, it means that the PFC circuit does not work normally. The key detection pin of PFC module is power input pin VC, start pin Vstart/control, CT and RT pin and V0 pin. When repairing a Fuji 3000 camera, test that there is no 380VDC voltage on the filter capacitor on the board. VC, Vstart/control, CT and RT waveforms and V0 waveforms are normal. The measured field effect power switch tube G has no V0 waveform. Since FA5331 (PFC) is a patch component, the machine will appear between the V0 terminal and the board after a long time. Solder, the V0 signal is not sent to the FET of the FET. Solder the V0 end to the solder joint on the board, and measure the filter capacitor with a 380 VDC voltage with a multimeter. When the Vstart/control terminal is low and the PFC is not working, the relevant circuit whose terminal is connected to the periphery is detected.
   In short, the switching power supply circuit is easy to have, the power is large and small, and the output voltage is various. As long as you grasp the core things, that is, fully familiar with the basic structure of the switching power supply and the characteristics of the PFC and PWM modules, the basic conditions for their operation, according to the above steps and methods, more hands-on maintenance of the switching power inverter supply, you can quickly eliminate the switch Power failure, achieve twice the result with half the effort.

The 5V2A power inverter supply is a type of application on the market that supports comprehensive functions and is stable. But choosing a power solution is a business that confuses companies. Many times they don’t know how to make a choice.
I believe that everyone on the Internet search “power solution selection method”, you can see a lot of solutions to promote products and technology. Today, we don’t talk about technology, we talk about skills, and use our vision to outline the important parts:

1. First of all, we must have a comparison. We have to compare the different schemes of the same manufacturer, the schemes between different manufacturers, the advantages of the comparison scheme, and the stability performance.
   2, look at the strength of the power inverter plan manufacturers, whether it is in line with the development process of our entire project.
2. The operation mode of the solution manufacturer is also a part of our consideration. If a solution developer has a complete production and sales system, its strength is very strong and the product quality can be guaranteed.
   Therefore, it can also be said that the strength of the power solution provider is an important part of determining whether the solution is desirable or not. Juquan is also vigorously promoting an equal and true market atmosphere.
   Today, the small series of UnionPay Technology introduces several 5V2A power inverter solutions for you to teach you how to choose a solution.
   Features of the 5V2A power solution U6315a:
   QR-PSR control improves work efficiency.
   ± 4% constant current and constant voltage accuracy, PSR control mode.
   System efficiency meets ‘DoE six energy efficiency & rsquo; Tier2 requirements, standby <70mW.
   Primary feedback / built-in triode, built-in patented line loss voltage compensation.
   Features of the 5V2A power solution U6773S:
   Efficiency meets six energy efficiency requirements
   Primary feedback / built-in 650V power MOSFET
   Automatically compensates for input voltage. Inductive inductance changes, achieving high precision
   Multi-mode PSR control improves reliability and efficiency
   Features of the 5V2A power inverter solution U6117SA:
   Primary feedback / built-in MOSFET
   Efficiency meets six energy efficiency requirements
   Low standby power consumption is less than 70mW
   Built-in 600V power MOSFET
   The above article was provided by UnionPay Technology. Elanpo UnionPay Technology has focused on various types of chip development and design for 20 years. The unique low-power and high-efficiency power supply solution has been recognized by customers and successfully put into use in the market. UnionPay has low price, high efficiency and low power. The purpose of high effect is to push a better power adapter solution to the market. At the same time, we will provide you with efficient and convenient service. Elanpo UnionPay team will provide you with reasonable suggestions. I hope that Elanpo UnionPay team can give you yours. Life brings energy-saving changes.
   The quality of survival, the credibility of development, the serious work, sincere people is the company’s business philosophy.

The car power inverter is a power product that works in high current and high frequency environments, and its potential failure rate is quite high. Therefore, consumers must be cautious when purchasing. First, select from the output waveform of the inverter, preferably not lower than the quasi-sine wave; secondly, the inverter must have complete circuit protection function; third, the manufacturer must have a good after-sales service commitment; fourth, the circuit and The product has been tested for a while.

1. In addition to the price factor, the main requirement for the vehicle power supply is the input voltage requirement and the output power of the vehicle power supply. In addition, since the power of various electrical appliances varies greatly, it is necessary to select the vehicle power supply according to the use requirements. It is enough to use.
2. According to the type of electrical appliance used, it is necessary to select a suitable vehicle power supply. For daily resistive electrical appliances, square wave, correction wave and sine wave can be used together. For sensitive electrical appliances, sine wave inverter must be selected. The device is over.
   3, square wave / modified wave inverter power supply can not carry inductive load and capacitive load, can not drive air conditioning, refrigerator, it is difficult to provide power for high-quality audio TV. Strictly speaking, the square wave/corrected wave inverter power supply will affect the service life of the electrical appliances. These problems do not occur when using a sine wave inverter.
3. The cigarette lighter insurance in the general car is 10A or 15A (10A insurance is mostly old models or imported models), which means that the car power inverter power supply that can be used in a general car is 120W or 180W. . If you need a high-power inverter (more than 180W or 200W), you must look at whether there is a battery clamp in the package. There is a limit to the use of a high-power inverter without a battery clamp in a car.
   5, the general car power supply will have insurance at the cigarette lighter end, the car supplies Qiqi network reminds you must open the purchase when you check this insurance and the car cigarette lighter insurance does not match (theoretically less than or equal to the cigarette) The insurance of the device), so that the insurance of the cigarette lighter can play a role, and vice versa, the insurance of the car cigarette lighter will be burned, which will cause unnecessary trouble.

For this kind of fault phenomenon, according to the maintenance experience, in addition to the voltage regulator control circuit will cause the output voltage to be too low, there are some reasons that will cause the output voltage to be too low, mainly the following:

1. The switching power inverter supply load has a short circuit fault. At this time, all the loads of the switching power supply circuit should be disconnected to distinguish whether the switching power supply circuit or the load circuit is faulty. If the voltage output of the load circuit is disconnected, it means that the load is too heavy; if it is still not normal, the switching power supply circuit is faulty.
2. The output voltage terminal rectifier diode, filter capacitor failure, etc., can be judged by the substitution method.
3. The performance of the switching power tube is degraded, which will inevitably lead to the switch tube not being able to conduct normally, which will increase the internal resistance of the power supply and reduce the load capacity.
4. The source (S pole) of the switching power tube is usually connected to a resistor with a small resistance but a large power. As an overcurrent protection detection resistor, the resistance of this resistor is generally between 0.2 and 0.8. If the resistor is changed or soldered, poor contact may cause the output voltage to be too low.
5. The high-frequency transformer is not good, which not only causes the output voltage to drop, but also causes the switching power tube to be insufficiently excited to damage the switch tube.
6. The high-voltage DC filter capacitor is poor, resulting in poor power supply load capacity, and the output voltage of the load will drop.
7. The power supply output line has poor contact and has a certain contact resistance, which causes the output voltage to be too low.
8. Is the grid voltage too low? Although the switching power supply can still output the rated voltage value under low voltage, when the grid voltage is lower than the minimum voltage limit of the switching power supply, the output voltage will be too low.
   Maintenance method: For this kind of failure, we can check one by one according to the above reasons. However, in actual maintenance, it can be checked according to the actual situation, and it is not necessary to check one by one. First, use a multimeter to check whether the high-voltage DC filter capacitor is degraded, whether the capacity is reduced, and whether it can be charged and discharged normally. If there is no such phenomenon, measure the current limiting resistance of the gate (G pole) of the switching power tube and the overcurrent protection detection resistance of the source (S pole) for deterioration, power inverter deterioration or open soldering, and poor contact. After the discrimination, if there is no problem, we will check whether the core of the high-frequency transformer is intact. Due to the inevitable heavy fall or heavy building in daily life, the core of the high-frequency transformer is damaged. The magnetic flux, magnetic induction, and magnetic circuit of the high-frequency transformer are greatly affected, resulting in transmission efficiency and greatly reduced energy. In order to reduce the eddy current and increase the transmission efficiency of high-frequency alternating current, the high-frequency transformer is made of soft ferrite. This magnetic material has high magnetic permeability but is brittle and brittle. Therefore, its damage rate is also very high. Therefore, don’t forget to check here during maintenance to avoid detours. In addition to this, there may be a decrease in the output filter capacitor capacity, or even loss of capacity or open soldering, virtual connection; power supply output current limiting resistor variable value or virtual connection, power supply output line virtual connection. In the actual maintenance, these factors should not be let go, should be checked to ensure that nothing is lost.

This phenomenon indicates that the switching power inverter supply is not working or has entered the protection state after working.
Maintenance method: First of all, it should be judged whether the main control chip UC3842 of the switching power supply is in working condition or damaged. The judgment method is as follows: powering up the voltage of the 7th pin of the UC3842 to the ground. If the 8th pin has a +5V voltage, and the 1, 2, 4, and 6 pins also have different voltages, the circuit has started to vibrate, and the UC3842 is basically Normal; if the voltage of pin 7 is low and the other pins have no voltage or wave, the UC3842 is damaged. The most common damage to the UC3842 chip is the breakdown of the 6 and 7 feet to the ground, the breakdown of the 5, 7 feet to the ground and the breakdown of the 1, 7 feet to the ground. If these feet are broken down and the switching power inverter supply still does not start normally, the UC3842 will be broken and should be replaced directly. If it is judged that the chip is not broken, it is important to check whether the current limiting resistor of the gate (G pole) of the switching power tube is open, soldered, variable, deteriorated, and whether the switching power tube itself has poor performance. In addition, the power inverter output line may also be disconnected or poorly contacted. Therefore, you should also pay attention to check when repairing.

In the learning design of switching power supplies, we often encounter names that are not well explained or difficult to distinguish. For example, the AC switching power supply and the DC switching power supply, what is the difference between the two, what is the difference? Let’s first understand the AC power supply. AC power is a proper term, usually referred to as a plug and socket finger used to connect the AC power provided by the utility, to make the home appliance and the portable small device energized and usable. Knowing the AC power, then we continue to talk about AC switching power supplies and DC switching power supplies.
The DC switching power supply uses high-speed conduction and cut-off through the circuit control switch tube, and the AC power is supplied to the transformer for voltage transformation into high-frequency DC power, thereby generating one or more sets of voltages required! The reason for the conversion to high-frequency AC is that the efficiency of high-frequency AC in the transformer transformer circuit is much higher than that of 50HZ, so the switching transformer can be made very small, and it is not very hot when working! The cost is very low. If you do not turn 50HZ into a high frequency, then there is no point in switching the power supply.
Usually, when the surface is understood, the AC switching power supply input voltage is AC. The DC switching power supply input voltage is DC. The AC power is also equal to DC AC power inverter , and the DC power is equal to DC/DC, but sometimes DC/AC is also called DC power. The DC switching power supply is generally said to be relative to the alternating current. The switching power supply is a method of changing from alternating current to direct current, that is to say, the switching power supply is actually a converter that converts the power supply to the direct current. Therefore, in practical terms, AC switching power supply is only a general term, and there is no actual principle.
The difference between DC and AC switches is essentially the same. DC AC power inverter It is the same function, controlling the disconnection and connection of the power input line.
In actual use, the AC switch is generally installed on the positive circuit of the front end of the appliance, and the AC switch is installed on the live line of the front end of the appliance.
The only difference between the two is.
Usually, when the surface is understood, the AC switching power supply input voltage is AC. The DC switching power supply input voltage is DC. The AC power is also equal to AC/DC, and the DC power is equal to DC/DC, but sometimes DC/AC is also called DC power. The DC switching power supply is generally said to be relative to the alternating current. The switching power supply is a method of changing from alternating current to direct current, that is to say, the switching power supply is actually a converter that converts the power supply to the direct current. Therefore, in the practical sense, the AC switching power supply is only a general term, and there is no practical principle.
Sixth, the working principle of switching power supply
First of all, as the name suggests, switching power supplies use electronic switching devices (such as transistors, FETs, thyristors, etc.), through the control circuit, so that the electronic switching device is constantly “on” and “off”, let The electronic switching device modulates the input voltage to achieve DC/AC, DC/DC voltage conversion, and adjustable output voltage and automatic regulation.
The working process of the switching power supply is:
Power → Input Filter → Full Bridge Rectifier → DC Filter → Switch Tube (Oscillation Inverter) → Switching Transformer → Output Rectification and Filtering.
AC power input is rectified and filtered into DC
The switching tube is controlled by a high frequency PWM (Pulse Width Modulation) signal, and that DC is applied to the switching transformer primary
The secondary of the switching transformer induces a high-frequency voltage, which is supplied to the load through rectification and filtering.
The output part is fed back to the control circuit through a certain circuit to control the PWM duty cycle to achieve stable output.
When the AC power input is input, it generally passes through something like the E-flow circle to filter out the interference on the power grid and also filter out the interference of the power supply to the power grid;
When the power is the same, the higher the switching frequency, the smaller the volume of the switching transformer, but the higher the requirements for the switching tube;
The secondary of the switching transformer can have multiple windings or one winding with multiple taps to obtain the desired output;
Generally, some protection circuits should be added, such as no-load, short-circuit, etc., otherwise the switching power supply may be burnt.
Mainly used in industry and some household appliances, such as televisions, computers, etc.
The switching power inverter supply uses high-speed conduction and cut-off through the circuit control switch.
Converting DC power to high frequency AC power is supplied to the transformer for voltage transformation to produce one or more sets of voltages required! The reason for switching to high-frequency AC is that the efficiency of high-frequency AC in the transformer transformer circuit is much higher than that of 50HZ. So the switching transformer can be done very small, and it is not very hot when working! ! The cost is very low. If you do not turn 50HZ into a high frequency, then there is no point in switching the power supply.