How to use a multimeter to detect the power module of an inverter
When the power module is tested on the road (off the grid), use a pointer multimeter R×l block to measure the collectors and emitters of the six diodes of the rectifier bridge and the six IGBT tubes of the output bridge in forward and reverse directions to determine whether they have broken down. The table l and Table 2 are normal measurement results, otherwise there are breakdown components inside. Use a pointer multimeter Bx1k to measure the resistance between the gate and emitter of the six IGBT tubes (drive signal input terminal). They should be the same. If there is a difference, the drive circuit or IGBT tube is damaged. The above measurements can only detect breakdown damage of IGBT tubes. No open circuit damage can be detected. After removing the power module from the circuit board, each IGBT tube can be further measured. The needle on the left indicates no conduction. The needle on the right indicates continuity. If it cannot be turned on and off, the tube is damaged.
The structure of the inverter power module:
Part of the internal package of the inverter power module is a single-phase or three-phase bridge rectifier circuit composed of diodes, and the other part is a three-phase bridge composed of six IGBT tubes (insulated gate bipolar transistors) and six damping diodes used together. output circuit.
The collectors of the three IGBT tubes in the upper half of the three-phase output bridge are connected to the positive terminal of the power supply. The emitters are the three-phase output terminals of U, V and W respectively. The emitters and gates of the three tubes form the upper half of the three-phase Bridge drive signal input terminals GU-U, GV-V, GW-W. The collectors of the three IGBT tubes of the lower half-bridge of the three-phase output bridge are connected to U, V, and W respectively, and the emitters are connected to the negative terminal of the power supply. The gates of the three tubes and the negative terminal of the power supply constitute the three-phase lower half-bridge drive signal. Input terminals GX, GY, GZ, and B are the brake control terminals.
There is no braking circuit inside this module. TH is the internal thermistor protection output terminal. Although the pins of other models of universal inverter power modules and the markings on the circuit board are different, it is not difficult to identify the main functional pin locations. High-end products use intelligent power modules, which contain drive circuits and braking circuits, and have more pins.
As the name suggests, the frequency converter power module is the power electronic power device in the frequency converter that is potted into a module according to a certain functional combination. The frequency converter itself is composed of a control unit and a power module. Generally, the inverter power module uses an integrated structure of the housing and external electrode terminals to reduce the number of components and reduce the internal wiring inductance.
