Based on the 9 limit tests that the switching power supply has to go through
1, repeated short circuit test Test instruction The module output should be short-circuited under various input and output states. The module should be able to protect or retract, and repeatedly short-circuit. After the fault is removed, the module should automatically resume normal operation. Test Methods a, no load to short circuit: within the full range of input voltage, the module from no load to short circuit, the module should be able to achieve normal output current limit or retraction, after the short circuit is removed, the module should be able to resume normal operation. Let the module repeatedly work from no load to short circuit, the short circuit time is 1s, the release time is 1s, and the duration is 2 hours. After this, the short circuit is released and it is judged whether the module can work normally. b. Full load to short circuit: In the full range of input voltage, the module should be able to realize output current limiting or retraction from full load to short circuit. After short circuit elimination, the module should be able to resume normal operation. Let the module go from full load to short circuit and then keep short circuit for 2 hours. Then short out and let go, judge whether the module can work normally. c. Short-circuit boot: short-circuit the output of the module, then go on the power, and then power on the input voltage range of the module. The module should be able to achieve normal current limiting or retraction. After the short-circuit fault is removed, the module should be able to resume normal operation. After repeating the above test 10 times, let the short circuit go out and judge whether the module can work normally. judgement standard After the above test, the power module can be turned on normally; the boot case is checked, the circuit board and other parts are free of abnormal phenomena (such as whether the input relay is stuck during the short circuit, etc.), and it is qualified; otherwise it is unqualified. 2, repeated switch test Test instruction When the power module output has the maximum load, the input voltage is 220v, (input overvoltage point -5v) and (input undervoltage point +5v), the input is repeatedly switched, and the performance of the power module is repeatedly turned on and off. Test Methods a, the input voltage is 220v, the power module is fast with the maximum load, use the contactor to control the voltage input, 15s, disconnected for 5s (or can be simulated with ac source), continuous operation for 2 hours, the power module should work normally; b, the input voltage is overvoltage point -5v, the power module has the maximum load, use the contactor to control the voltage input, 15s, disconnected for 5s (or can be simulated with ac source), continuous operation for 2 hours, the power module should be normal jobs; c, the input voltage is undervoltage point -5v, the power module has the maximum load, use the contactor to control the voltage input, 15s, disconnected for 5s (or can be simulated with ac source), continuous operation for 2 hours, the power module should be normal jobs. judgement standard In the above test, the power module works normally. After the test, the power module can work normally, the performance has no obvious change, and it is qualified; otherwise it is unqualified. 3, input low pressure point cycle test Test instruction The setting hysteresis of the input undervoltage protection of the primary power module often occurs as follows: the input voltage is low, close to the undervoltage point of the power module, and the undervoltage at the time of loading, after the disconnection, the load is unloaded due to the internal resistance of the power supply. The voltage will rise after the drop, which may cause the power module to be repeatedly developed at low voltage. Test Methods The power module is running at full load. The input voltage changes slowly from (input undervoltage point -3v) to (input undervoltage point +3v). The time is set to 5~8 minutes. Repeated cycle operation, the power module should be able to work normally and continuously. At least 0.5 hours, there is no significant change in the performance of the power module. judgement standard Once the power module is in normal continuous operation, the performance does not change significantly after at least 0.5 hours, and it is qualified; otherwise it is unqualified. 4, input transient high voltage test Test instruction The pfc circuit uses the averaging circuit for over-voltage protection. Therefore, when the transient high voltage is input, the pfc circuit may be protected quickly, causing damage. Test the stability of the power module under transient conditions to evaluate the reliability. . Test Methods a, rated voltage input, use the dual trace oscilloscope to test the input voltage waveform and overvoltage protection signal, the input voltage from the limit power point plus 5v jump to 300v, read the cycle number n of the 300v before the overvoltage protection from the oscilloscope, as the following Basis for the test. b, rated input voltage, power module with full load operation, superimposed 300v voltage jump on the input, the number of superimposed cycles is (n-1), the superimposed frequency is 1 time / 30s, a total of 3 hours. judgement standard The primary power module can operate stably under the above conditions without any damage or other abnormalities; otherwise it is unqualified. 5, input voltage drop and output dynamic load Test instruction During the actual use of the module, when the input voltage drops, the limit condition of the power module sudden load may occur. At this time, the power device and the magnetic component work in the maximum transient current state, and the test can verify the control timing and current limit. The rationality of protection circuit and software design. Test Methods a. Adjust the input voltage to jump between the undervoltage point +5v (duration 5s) and the overvoltage point -5v (duration 5s). The output is adjusted at the maximum load (maximum rated capacity, duration is 500ms) Jump between no-load (with a duration of 500ms) and run for 1 hour; b. Adjust the input voltage to between +5v (duration time 5s) and overvoltage point -5v (duration time 5s). The output is adjusted at the maximum load (maximum rated capacity, duration is 1s). Jump between no-load (with a duration of 500ms) and run for 1 hour. judgement standard Under the above conditions, it should be able to operate stably without damage or other abnormal phenomena; otherwise it is unqualified. In the event of damage, record the problem to provide a basis for analyzing the cause of the damage. 6, high pressure no load, low pressure limit flow test Test instruction The high-voltage no-load operation is the loss of the test module, especially the module with soft-switching technology. Under no-load conditions, the soft switch becomes a hard switch, and the loss of the module increases accordingly. Low-voltage full-load operation is the loss of the module when the module is at the maximum input current. Under normal conditions, the module has the lowest efficiency at low-voltage input and full-load output. At this time, the module has the most heat. Test Methods a. Adjust the input voltage of the module to the input overvoltage protection point -3v, the output of the module is the lowest output voltage, and run at no load. At this time, the duty ratio of the module is the minimum, continuous operation for 2 hours, the module should not be damaged; b. Adjust the input voltage of the module to the undervoltage point +3v, and the output of the module is the inflection point state of the highest output voltage. At this time, the duty ratio of the module is the maximum, and the module should not be damaged if it is continuously operated for 2 hours. c. Adjust the input voltage of the module to the input voltage at the lowest efficiency point, and the module output is the inflection point state of the highest output voltage, and the module should not be damaged if it is continuously operated for 2 hours; d. Adjust the input voltage of the module to the overvoltage point -3v. The output of the module is the inflection point state of the highest output voltage. At this time, the duty ratio of the module is the maximum, and the module should not be damaged if it is continuously operated for 2 hours. e. Adjust the input voltage of the module to the input voltage at the lowest efficiency point. The module output is the inflection point of the highest output voltage. If the operation is continuous for 2 hours, the module should not be damaged. Note: The above tests must be performed at the maximum operating temperature specified in the data sheet. judgement standard Under the above conditions, the module did not appear damaged, qualified; otherwise it was not qualified. 7, power supply special waveform test Test instruction Verify that the power module is stable in the presence of spikes, spurs, and harmonics that may be caused by grid distortion. The following waveforms must be entered for testing: (1) Glitch input test waveform The glitch of the power grid is the most common waveform in the power grid. There is no limit to the size and amplitude of the glitch. In general, the input of the oscillating wave input and the ringing input waveform can basically simulate the glitch input in the power grid, but it still needs Do the following burr input test Features: The power grid spike has overshoot and will fall to 0v. The overshoot and drop pulse width is very narrow, generally not more than 100ms, and the overshoot range generally does not exceed 100v. The phase of the fall is not limited to the peak point and can occur at any phase. This type of waveform is common in real-world power grids, and turning it on can cause this phenomenon. (2) Voltage clipping waveform input This type of waveform is also very common in the power grid. The characteristic is that the grid suddenly drops from an indefinite phase to 0v and then resumes until the next half wave begins. In iec1004-4-11, the drop for the waveform starts from more than half a cycle, but there are still many similar waveforms with a drop time less than half a cycle. During the test, the input voltage waveform starts to fall from 90 degrees, falls by 1/4 cycle, and works for 2 hours for a long time. (3) The half wave head of the power grid rises steeply to double voltage. This waveform is mainly used to simulate the resonant overvoltage that will suddenly appear in the actual power grid. In this case, the input overvoltage protection circuit of the module does not work. This kind of shock is dangerous for circuits with pfc. Test content: a. When the input voltage is 180v and the output is full, simulate the waveform with ac source, require 180v to work for 3 minutes, then suddenly increase the voltage to 380v for 100ms, then restore to 180v, let the module in this In case of working for 1 hour, it should not be damaged; b. Set ac source so that the input voltage is 0v for 5 minutes, then the voltage suddenly increases to 380v for 100ms, then return to 0v, let the module grow in this case. Work for 1 hour and should not be damaged. Test Methods Use ac source to power the module, the module is fully loaded; use ac source to simulate spike, glitch and harmonic voltage input, each special voltage input works for 2 hours, measuring input current and output voltage. The module should be able to operate stably. Pay attention to x capacitors, auxiliary power supplies, soft start resistors and other places where problems may occur. judgement standard In practice, there may be spikes, burrs, harmonic voltages, stable operation, no damage, qualified; otherwise unqualified. 8, active pfc performance test Test instruction Power modules with source pfc are sensitive to grid spikes, burrs and harmonics and should be thoroughly tested. Test Methods Use ac source AC source as input voltage source, output with half load, full load, test input current waveform and voltage waveform, and monitor voltage after pfc; test grid input voltage and current under sharp, glitch, harmonic Phase and amplitude relationship; measure the current and voltage of the pfc switch tube to verify the safety of the switch and other power devices and the ability to track current changes in the full voltage range and glitch, spike, harmonics, etc. judgement standard The pfc test can be used as a reliability reference, and should be resolved in time when serious problems occur. 9, operating voltage test Test instruction There are a variety of operating overvoltages in the grid, the most common of which is the overvoltage of the time-space line. This overvoltage poses a greater threat to the module. This test is to verify the module's ability to withstand overvoltage. Test Methods The simulation of the overvoltage line is very simple, the principle is as follows: The inductance parameter is 10mh (for reference: ees module test method, there is no grounding capacitor, the input resistance is connected in series with the inductor, the resistance value is 0 ohm, the inductance is 8mh, the resistance is 79 ohm, the inductance is 10mh. ), the capacitance is 16.7 uf, and the test waveform is as follows (not shown). The device to be tested is connected at both ends of the capacitor. At the instant of k closing, an overvoltage is generated across the capacitor to simulate the damage of the overvoltage to the device during the power-on process. As the limit test item, input the l and n lines, connect the tested device to both ends of the capacitor, frequently switch the machine, repeat the frequency for 1 time / 5 minutes, and continuously test for 5 hours. For the three-phase input device, the input is connected to the l and l lines, and the device under test is connected to both ends of the capacitor. The repetition frequency is 1 time/5 minutes, and the test is continuous for 2 hours. judgement standard In the test process, there is a short-term decline in function or performance degradation, but it can be automatically recovered, and it is qualified; however, if the performance is permanently degraded or requires manual intervention to recover, it is unqualified. Suizhou simi intelligent technology development co., LTD , https://www.msmvape.com