Switching power must pass these limit tests!

1, input low pressure point cycle test

Test specification

The setting back difference of the input undervoltage point protection of the primary power module usually occurs in the following situations: The input voltage is low and close to the undervoltage point of the primary power module. When the load is loaded, the voltage will rise after the load is removed due to the internal resistance of the power supply. As a result, the primary power module may be in the state of repeated development at low voltage.

Test method

The power module runs with full load, and the input voltage changes slowly from (input undervoltage point -3v) to (input undervoltage point +3v). The time is set to 5 ~ 8 minutes, and the power module runs repeatedly. The power module should work normally and stably.

Decision criteria

The primary power module runs normally and continuously, and the performance does not change significantly after at least 0.5 hours. Qualified; Otherwise, it is not qualified.

2, input transient high voltage test

Test specification

The pfc circuit uses the average value circuit for over and under voltage protection. Therefore, when the input transient high voltage, the pfc circuit may realize protection quickly and cause damage. Test the stable operation ability of the primary power module under the transient condition to evaluate the reliability.

Test method

a. For rated voltage input, use the dual-trace oscilloscope to test the input voltage waveform and the overvoltage protection signal, and the input voltage jumps from the power limit point to 300v by adding 5v. Read the 300v cycle number n before the overvoltage protection from the oscilloscope as the basis for the following tests.

b. Rated input voltage: The power module runs with full load and superimpose 300v voltage jump on the input. The stacking period is (n-1), the stacking frequency is 1 time /30s, and the operation lasts for 3 hours.

Decision criteria

The primary power module can run stably under the above conditions without damage or other abnormal phenomena. Qualified. Otherwise, it is not qualified.

3, input voltage drop and output dynamic load

Test specification

When the input voltage drops during the actual use of the primary module, the limit condition of sudden load on the power module may occur. At this time, the power components and magnetic components work in the maximum transient current state. The test can verify the rationality of the control timing sequence, current limiting protection and other circuits and software design.

Test method

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

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

Decision criteria

Under the above conditions, it should be able to operate stably, without damage or other abnormal phenomena, qualified; Otherwise, it is not qualified. If damage occurs, record the fault to provide a basis for analyzing the cause of damage.