Switching power supply test items

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Switching power supply test items [Copy link]

1. Repeated short circuit test Test description Under various input and output states, the module output will be short-circuited. The module should be able to achieve protection or retraction. After repeated short circuits, the module should automatically resume normal operation after the fault is eliminated.

Test method

a. No-load to short-circuit: Within the full range of input voltage, turn the module from no-load to short-circuit. The module should be able to achieve output current limiting or retraction normally. After the short-circuit is eliminated, the module should be able to resume normal operation. Let the module work repeatedly from no-load to short-circuit. The short-circuit time is 1s, the release time is 1s, and the duration is 2 hours. After that, release the short-circuit to determine whether the module can work normally.

b. Full load to short circuit: Within the full range of input voltage, the module is changed from full load to short circuit. The module should be able to achieve normal output current limiting or retraction. After the short circuit is eliminated, the module should be able to resume normal operation. Let the module go from full load to short circuit and then keep the short circuit state for 2 hours. Then release the short circuit to determine whether the module can work normally.

c. Short circuit startup: Short circuit the module output first, then connect to the mains, and then power on within 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 eliminated, the module should be able to resume normal operation. Repeat the above test 10 times, release the short circuit, and determine whether the module can work normally.

Judgment standard

After the above test, if the power module can work normally when turned on; open the case for inspection, if there is no abnormality in the circuit board and other parts (such as whether the input relay is stuck during the short circuit process, etc.), it is qualified; otherwise, it is unqualified. 2. Repeated power on and off test Test description When the power module outputs with maximum load, the input voltage is 220V, (input overvoltage point -5V) and (input undervoltage point +5V), the input is repeatedly switched on and off to test the performance of the power module's repeated power on and off. a. The input voltage is 220V, the power module is fast with the maximum load, the voltage input is controlled by the contactor, the power module is closed for 15s and disconnected for 5s (or it can be simulated by AC source), and it runs continuously for 2 hours. The power module should be able to work normally; b. The input voltage is the overvoltage point of -5V, the power module is with the maximum load, the voltage input is controlled by the contactor, the power module is closed for 15s and disconnected for 5s (or it can be simulated by AC source), and it runs continuously for 2 hours. The power module should be able to work normally;

c. Input voltage is undervoltage point -5V, power module carries maximum load, use contactor to control voltage input, close for 15s, disconnect for 5s (or can use ac source for simulation), run continuously for 2 hours, the power module should be able to work normally.

Judgment standard

In the above test, if the power module works normally, and after the test, the power module can work normally, and there is no obvious change in performance, it is qualified; otherwise, it is unqualified. 3. Input low voltage point cycle test

Test description

The setting hysteresis of the input undervoltage point protection of the primary power module often causes the following situations: the input voltage is low, close to the undervoltage point of the primary power module to shut down, undervoltage when loaded, and after disconnection, due to the internal resistance of the power supply, the voltage will rise after the load is removed, which may cause the primary power module to be in a state of repeated development at low voltage.

Test method

The power module is running at full load, and the input voltage changes slowly from (input undervoltage point -3v) to (input undervoltage point +3v). The time is set to 5 to 8 minutes. Repeat the cycle. The power module should be able to work normally and stably, and run continuously for at least 0.If the power module runs normally and continuously for at least 0.5 hours and there is no obvious change in performance, it is qualified; otherwise, it is unqualified. 4. Input transient high voltage test Test description The PFC circuit uses an average value circuit for over-voltage and under-voltage protection. Therefore, when a transient high voltage is input, the PFC circuit may quickly implement protection, causing damage. This test is used to test the stable operation capability of the power module under transient conditions to evaluate its reliability.

Test method

a. Rated voltage input, use a dual-trace oscilloscope to test the input voltage waveform and overvoltage protection signal, the input voltage jumps from the power limit point plus 5V to 300V, read the number of cycles n of 300V before overvoltage protection from the oscilloscope, as the basis for the following test.

b. Rated input voltage, the power module runs with full load, superimposes a 300V voltage jump on the input, the number of superimposed cycles is (n-1), the superimposed frequency is 1 time/30s, and the total operation time is 3 hours.

Judgment Standard

If the primary power module can operate stably under the above conditions without damage or other abnormal phenomena, it is qualified; otherwise, it is unqualified. 5. Input voltage drop and output dynamic load Test description During the actual use of the primary module, when the input voltage drops, the extreme condition of sudden load on the power module may occur. At this time, the power devices and magnetic components operate in the maximum transient current state. The test can verify the rationality of the circuit and software design of control timing, current limiting protection, etc.

Test method

a. Adjust the input voltage to jump between the undervoltage point +5V (duration of 5s) and the overvoltage point -5V (duration of 5s), and adjust the output to jump between the maximum load (maximum rated capacity, duration of 500ms) and no-load (duration of 500ms), and run for 1 hour;

[font=Arial, b. Adjust the input voltage to jump between the undervoltage point +5V (duration of 5s) and the overvoltage point -5V (duration of 5s), and adjust the output to jump between the maximum load (maximum rated capacity, duration of 1s) and no-load (duration of 500ms), and run for 1 hour.

Judgment criteria

Under the above conditions, it should be able to run stably without damage or other abnormal phenomena, and it is qualified; otherwise, it is unqualified. If damage occurs, record the fault problem to provide a basis for analyzing the cause of the damage.

6. High-voltage no-load, low-voltage current-limited operation test

Test description

High-voltage no-load operation is to test the loss of the 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 to test the loss of the module at the maximum input current. Under normal conditions, the module is at its lowest efficiency when it is at low voltage input and full load output, and the heating of the module is the most serious at this time.

Test method

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 runs at no load. At this time, the duty cycle of the module is the minimum. The module should not be damaged after running for 2 hours continuously.

[font=Arial,b. Adjust the input voltage of the module to the undervoltage point +3v, the output of the module is the inflection point of the highest output voltage, at this time the duty cycle of the module is the maximum, and the module should not be damaged after running for 2 hours continuously; c. Adjust the input voltage of the module to the input voltage at the lowest efficiency point, the output of the module is the inflection point of the highest output voltage, and the module should not be damaged after running for 2 hours continuously; d. Adjust the input voltage of the module to the overvoltage point -3v, the output of the module is the inflection point of the highest output voltage, at this time the duty cycle of the module is the maximum, and the module should not be damaged after running for 2 hours continuously; e. Adjust the input voltage of the module to the input voltage at the lowest efficiency point, and the module output to the inflection point state of the highest output voltage. After running for 2 hours continuously, the module should not be damaged. Note: The above test must be carried out at the highest operating temperature specified in the specification. Criteria for judgment: If the module is not damaged under the above conditions, it is qualified; otherwise, it is unqualified. 7. Special power waveform test

Test description

To check the stable operation capability of the power module under the spikes, glitches and harmonics that may be caused by the grid waveform distortion. The following waveforms must be input 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 on the size and amplitude of the glitch. In general, the oscillation wave input test and the ringing input waveform can basically simulate the glitch input in the power grid, but the following glitch input test is still required. Features: The power grid spike has overshoot and will drop to 0V. The overshoot and drop pulse width are very narrow, generally not greater than 100ms, and the overshoot amplitude generally does not exceed 100V. The phase of the drop is not limited to the peak point, and it may occur at any phase. This waveform is very common in the actual power grid, and any switch will cause this phenomenon. (2) Voltage clipping waveform input This waveform is also very common in the power grid, and its characteristics are: the power grid suddenly drops to 0V from an uncertain phase, and then does not recover until the next half wave begins. In IEC1004-4-11, the drop of the waveform starts from more than half a cycle, but there are still many similar waveforms with a drop time of less than half a cycle in the actual power grid. The test requires that the input voltage waveform starts to drop from 90 degrees, drops 1/4 cycle, and works for a long time of 2 hours. (3) The half wave head of the power grid rises to double the 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 impact is dangerous for the circuit with PFC. Test content: a. When the input voltage is 180V and the output is full load, use AC source to simulate this waveform. It is required to work at 180V for 3 minutes, then the voltage suddenly increases to 380V for 100ms, and then returns to 180V. Let the module work for a long time for 1 hour in this case, and it should not be damaged; b. Set the AC source so that the input voltage is 0V for 5 minutes, then the voltage suddenly increases to 380V for 100ms, and then returns to 0V. Let the module work for a long time for 1 hour in this case, and it should not be damaged.

Test method

Use AC source to power the module, and the module outputs at full load; use AC source to simulate spike, burr and harmonic voltage input, each special voltage input works for 2 hours, and measures input current and output voltage. The module should be able to run stably. During the test, pay attention to other possible problems such as x capacitor, auxiliary power supply, soft start resistor, etc.

Judgment criteria

If it can run stably and without damage under the conditions of spikes, glitches and harmonic voltages that may appear in practice, it is qualified; otherwise it is unqualified.

8. Active PFC performance test

Test Description

The power module with active PFC is sensitive to grid spikes, glitches and harmonics, and should be tested comprehensively and carefully.

Test Method

Use AC source as the input voltage source, and output with half load and full load respectively, test the input current waveform and voltage waveform, and monitor the voltage after PFC at the same time; test the phase and amplitude relationship of input voltage and current of the power grid under spikes, glitches and harmonics; measure the current and voltage of the PFC switch tube, and verify the safety of the switch tube and other power devices and the ability of current to track voltage changes under the full voltage range and glitches, spikes, harmonics, etc.

Judgment criteria

The PFC test can be used as a reference for reliability. When serious problems occur, they should be resolved in a timely manner. 9. Operation voltage test

Test description

There are various operation overvoltages in the power grid. The most common one is the closing overvoltage of the unloaded line. This overvoltage poses a great threat to the module. This test is to verify the module's ability to resist operation overvoltage.

Test method

The simulation of the overvoltage line is very simple, the principle is as follows:

The inductor parameter is 10mh (for reference: in the ees module test method, there is no grounding capacitor, the input resistor is connected in series with the inductor, and the resistance value is 0 ohm, the inductor is 8mh and the resistance is 79 ohm, the inductor is 10mh), the capacitor is 16.7uf, and the test waveform is as follows (not drawn).

The device under test is connected to both ends of the capacitor. At the moment of closing the K switch, an overvoltage will be generated at both ends of the capacitor to simulate the degree of damage to the device caused by overvoltage during the power-on process. As an extreme test item, the input is connected to the l and n lines, the device under test is connected to both ends of the capacitor, and the machine is frequently turned on and off, with a repetition frequency of 1 time/5 minutes, and the test is continuous for 5 hours. For three-phase input devices, the input is connected to the l and l lines, the device under test is connected to both ends of the capacitor, with a repetition frequency of 1 time/5 minutes, and the test is continuous for 2 hours.

Judgment criteria

If there is a short-term functional decline or performance degradation during the test, but it can be automatically recovered, it is qualified; but if there is permanent performance degradation or manual intervention is required to recover, it is unqualified.

The simulation of overvoltage circuit is very simple, the principle is as follows: The inductor parameter is 10mh (for reference: in the module test method of ees, there is no grounding capacitor, the input resistor is connected in series with the inductor, and the resistance value is 0 ohm, the inductor is 8mh and the resistance is 79 ohm, the inductor is 10mh), the capacitor is 16.7uf, and the test waveform is as follows (not drawn). The device to be tested is connected to both ends of the capacitor. At the moment of K closing, overvoltage will be generated at both ends of the capacitor to simulate the degree of damage to the device caused by overvoltage during the power-on process. As an extreme test item, the input is connected to the l and n lines, the device under test is connected to both ends of the capacitor, and the machine is frequently turned on and off, with a repetition frequency of 1 time/5 minutes, and the test is continuous for 5 hours. For three-phase input equipment, the input is connected to the l and l lines, the device under test is connected to both ends of the capacitor, with a repetition frequency of 1 time/5 minutes, and the test is continuous for 2 hours.

Judgment criteria

If there is a short-term functional decline or performance degradation during the test, but it can be automatically restored, it is qualified; but if there is permanent performance degradation or manual intervention is required to recover, it is unqualified.

The simulation of overvoltage circuit is very simple, the principle is as follows: The inductor parameter is 10mh (for reference: in the module test method of ees, there is no grounding capacitor, the input resistor is connected in series with the inductor, and the resistance value is 0 ohm, the inductor is 8mh and the resistance is 79 ohm, the inductor is 10mh), the capacitor is 16.7uf, and the test waveform is as follows (not drawn). The device to be tested is connected to both ends of the capacitor. At the moment of K closing, overvoltage will be generated at both ends of the capacitor to simulate the degree of damage to the device caused by overvoltage during the power-on process. As an extreme test item, the input is connected to the l and n lines, the device under test is connected to both ends of the capacitor, and the machine is frequently turned on and off, with a repetition frequency of 1 time/5 minutes, and the test is continuous for 5 hours. For three-phase input equipment, the input is connected to the l and l lines, the device under test is connected to both ends of the capacitor, with a repetition frequency of 1 time/5 minutes, and the test is continuous for 2 hours.

Judgment criteria

If there is a short-term functional decline or performance degradation during the test, but it can be automatically restored, it is qualified; but if there is permanent performance degradation or manual intervention is required to recover, it is unqualified.