How to check the condition of the rectifier and inverter in an inverter

Detection method for three-phase rectifier bridge modules: Set the digital multimeter to the diode test mode, and use the red and black test leads to measure the forward and reverse diode characteristics between phases R, S, T and poles P, N respectively, in order to determine whether the rectifier bridge is intact. The greater the difference between the forward and reverse characteristics measured, the better ； If the forward and reverse values are zero, it indicates that the phase being tested has been broken down and short-circuited ； If both the forward and reverse values are infinite, it indicates that the phase being tested is open-circuited. If even one phase of the rectifier bridge module is damaged, it must be replaced. IGBT module testing method: Set the digital multimeter to the diode test mode, and test the forward and reverse diode characteristics between c1, e1, c2, e2 of the IGBT module, as well as between the gate g and e1, e2, in order to determine whether the IGBT module is intact. Take the six-phase module as an example. Remove the wires for the u, v, and w phases on the load side. Use the diode test function: connect the black probe to P (collector C1), and use the red probe to test u, v, and w in sequence. The multimeter will display an infinite value ； Reverse the test leads: connect the red lead to P, and the black lead to U, V, and W. The multimeter shows a value of around 400. Then connect the black test lead to N (emitter e2), and use the red test lead to measure U, V, and W; the multimeter shows a value of around 400 ； Connect the red test lead to P, and use the black test lead to measure U, V, and W; the multimeter shows an infinite value. The forward and reverse characteristics between the various phases should be identical; any differences indicate that the IGBT module’s performance has declined and it should be replaced.

It would be better if there were illustrations.

Reply to 2# zyz8438: If the multimeter doesn’t have a diode setting, how should one determine it?

Measure the forward and reverse resistances, and apply a trigger voltage to the trigger terminal as appropriate; for example, touch the trigger terminal and the positive terminal with the tip of the tongue to observe any changes in the load. Judge good or bad