According to the equivalent circuit diagram of the IGBT, if a positive driving voltage is applied between the gate G and the emitter E of the IGBT, the MOSFET is turned on, so that the collector C and the base of the PNP transistor are in a low resistance state, which makes the The transistor is turned on; if the voltage between the gate and the emitter of the IGBT is 0V, the MOS is turned off, and the supply of the base current of the PNP transistor is cut off, so that the transistor is turned off. IGBT, like MOSFET, is also a voltage-controlled device. A DC voltage of more than ten V is applied between its gate G and emitter E. Only the leakage current at the uA level flows, and basically no power is consumed.
The method of detecting IGBT module:
Take two units as an example, measure with an analog multimeter, as follows.
1. Static measurement
Put the multimeter in the multiplication gear of 100, measure the black test lead to terminal 1, the red test lead to the 2 terminal, the display resistance should be infinite; if the test leads are reversed, the display resistance should be about 400 ohms. In the same way, measure the black test lead to the 3 terminal, The red test lead is connected to terminal 1, and the display resistance should be infinite; if the test leads are reversed, the display resistance should be about 400 ohms. If the above conditions are met, it means that the two units of this IGBT have no obvious faults.
2. Dynamic test
Put the gear of the multimeter in the multiplier 10K gear, connect the black test lead to terminal 4 and the red test lead to terminal 5. At this time, the black test lead is connected to the 3 terminal and the red test lead is connected to the 1 terminal. At this time, the resistance should be 300-400 ohms, and the test leads should be reversed. There is also a resistance of about 300-400 ohms indicating that this IGBT cell is intact.
Use the same method to test the IGBT between terminals 1 and 2. If the above conditions are met, the IGBT is also intact. Set the multimeter to the R×10KΩ block, connect the black test lead to the drain D of the IGBT, and the red test lead to the source S of the IGBT. At this time, the pointer of the multimeter points to infinity. Touch the gate G and drain D at the same time with your finger, then the IGBT is triggered and turned on, the pointer of the multimeter swings to the direction with the smaller resistance value, and can stand to indicate a certain position. Then touch the source S and the gate G at the same time with your finger, at this time the IGBT is blocked, the pointer of the multimeter returns to infinity, and it can be judged that the IGBT is good.
It should be noted here that if the second measurement is performed, the source S and the gate G should be short-circuited. Any analog multimeter can be used to detect IGBTs. Note that when judging the quality of the IGBT, be sure to set the multimeter to the R×10KΩ block, because the internal battery voltage of the multimeter below the R×1KΩ block is too low, the IGBT cannot be turned on when the test is good, and the IGBT cannot be judged. Bad.
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