How to test an igbt with a multimeter

I. How to measure the quality of IGBT

1. First determine the polarity

Before measuring whether the IGBT is good or bad, the polarity of the IGBT must be determined first.

Set the multimeter to the R×1KQ position. When measuring with a multimeter, if the resistance value of one pole and the other two poles is infinite, and the resistance value of this pole and the other two poles is still infinite after changing the test leads, then it is judged that this pole is the grid (G).

Use a multimeter to measure the remaining two poles. If the measured resistance is infinite, the measured resistance becomes smaller after changing the test leads. When a small resistance value is measured for the first time, judge that the red test lead is connected to the collector (C), and the black test lead is connected to the emitter (E).

2.The simple method - gate trigger

Short the 3 terminals together to discharge the IGBT. Do not touch any terminals during the test, keep the IGBT on the black case at all times.

1) Take the smallest lead as the connection, then use a resistor to provide the trigger voltage from the C (collector) terminal to the trigger G (gate) terminal, the best IGBT will move the pointer of the multimeter forward and point to a certain resistor.

IGBT good or bad measurement diagram:

Resistor connection to IGBT diagram

2) Then remove the resistor (trigger voltage), the IGBT still lets current flow and the pointer still points to the same position when the gate is triggered.After removing the trigger voltage, the pointer still points to the same position (it is a good IGBT), otherwise it is a bad IGBT.

IGBT good or bad measurement diagram:

Diagram of IGBT good or bad measurement--remove the resistor from the G terminal

II. Diode file test--the method of measuring the quality of IGBT

IGBT has 3 feet, namely G (Gate), C (Collector) and E (Emitter), and its working principle is that the input voltage controls the output current.We can use this basic deviation to test whether it is a bad or good IGBT.

Important note: The analogue multimeter used here is the version where the black test lead is V+ and the red test lead is V-, when it is set to the resistance test function.

Diagram of IGBT good or bad measurement - multimeter to measure IGBT good or bad

Sample IGBT Diagram

1. Test the quality of IGBT by analog multimeter

1) Get the IGBT pin diagram from the datasheet.

2) Connect the test wires to the pins of the IGBT, as shown in the figure below.

IGBT good or bad test diagram - test connection diagram

3) Set the analog multimeter to Rx10K as this scope will be supplied with 9VDC by the internal battery. 9VDC is high enough to bias the gate so the IGBT is on.

4) Temporarily connect the pin of the resistor between the G pin and the C pin, and move the pointer of the multimeter forward to the low resistance, as shown in the figure below.

IGBT good or bad test diagram--temporarily connect the resistor to the G terminal and C terminal of the IGBT

5) After removing the resistor pin, the pointer position of the multimeter remains unchanged, because the IGBT is still working in the ON state, which means that the IGBT indicates good, but the bad IGBT cannot keep the ON state, so the pointer of the multimeter moves backward to the ∞ position to remove the resistor after the pin.

IGBT good or bad test diagram - test after removing the resistor

6) To test the OFF state, temporarily connect the G (gate) pin and the E (emitter) pin with a resistor pin. A good IGBT can be biased to both ON and OFF states, but a bad IGBT cannot be biased to both ON and OFF states.

IGBT good or bad test diagram - test off state

2.Digital multimeter test IGBT is good or bad

Steps to test whether the IGBT is good or bad with a digital multimeter:

1) Find the pin function in the datasheet (datasheet) according to the IGBT model.

2) Short the 3 pins of the IGBT or connect them together to discharge, then do not touch the pins.

IGBT pin diagram

3) If the C and E pins have diodes, set the digital multimeter to the diode test function, a good diode will show a voltage of 0.5-0.8 V when it is forward biased, and it will show "OL" when it reverses the deviation. A bad IGBT (short circuit) will show 000V, and a bad IGBT (open circuit) will show "OL" 2 times.

IGBT good and bad test diagram - CE pin test with diode

IGBT good or bad test diagram - CE pin test with diode (reverse test line)

4) If there are no diodes on the C and E pins, set the digital multimeter to the resistance test function, and a good IGBT will have results. A good IGBT will show high resistance 1 time and "OL" 1 time. A bad IGBT (short circuit) shows 0 ohm 2 times, a bad IGBT (open circuit) shows "OL" 2 times.

IGBT good or bad test diagram - CE pin test, no diode connected to the CE pin

IGBT good or bad test chart - CE pin test (reverse test line), there is no diode connected to the CE pin

5) To check the G (Gate) and C (Collector) pins, connect the test leads to the G (Gate) and C (Collector) pins.

6) Set the digital multimeter to the resistance test function, a good IGBT will show "OL" 2 times, because there is an insulator at the gate pin junction, so the multimeter can't measure the resistance (show "OL") is very very high The resistance. A bad IGBT (gate leakage) will show some resistance.

IGBT good or bad test diagram - G and C tube pin test

7) Check the G (gate) and E (emitter) pins, set the digital multimeter to the resistance test function.

8) Connect test leads to G (Gate) and E (Emitter) pins, test, then switch test leads to retest. Good IGBTs will show "OL" 2 times because the gate pin junction has an insulator so the multimeter can't measure this resistance is very very high resistance. A bad IGBT (gate leakage) will exhibit some resistance.

IGBT good or bad test diagram - G and E pin test