Testing an IGBT

What is an IGBT?

An insulated gate bipolar transistor (IGBT) is a three-terminal power semiconductor used as a high-efficiency electronic switch. They are often used in high-voltage, high-current situations with low-power inputs. They are often used in applications like induction cooktops, AC and DC motor drives, and in our P7000 PowerSync™ Series power supply used with our surface treaters. Let's learn how to test an IGBT:

1. Check For Shorted IGBT

Using a digital ohmmeter on the diode scale:

1. Measure resistance between C2/E1 and E2.
2. Measure resistance between C2/E1 and C1.

If you measure a short (0 ohms) in step 1a. or 1b., the IGBT is not usable.

2. Turn On Q1, Q2

Using a digital ohmmeter on the diode scale:

1. Touch the + (red) meter lead to G1 and the - (black) to E1.
2. Touch the + (red) meter lead to G2 and the - (black) to E2.
3. Measure resistance between C1 and C2/E1. Should read a low resistance (about a diode drop). Reverse meter leads, reading should be the same.
4. Measure resistance between E2 and C2/E1. Should read a low resistance (about a diode drop). Reverse meter leads, reading should be the same.

3. Turn Off Q1, Q2

Using a ohmmeter on the diode scale:

1. Touch the + (red) meter lead to E1 and the - (black) to G1.
2. Touch the + (red) meter lead to E2 and the - (black) to G2.
3. Measure resistance between C2/E1 (+) and C1 (-). Should read a low resistance (same as in step 2c.). Reverse meter leads. Read infinite resistance.
4. Measure resistance between C2/E1 (-) and E2 (+). Should read a low resistance (same as in step 2d.). Reverse meter leads. Read infinite resistance.

Note: Some digital ohmmeters do not have enough power to turn on an IGBT. A 9 volt battery may be used instead.