Multimeter testing of inverter power modules
Power module in the road test (off the grid), with a pointer multimeter R × l block respectively positive and negative measurements of the six diodes of the rectifier bridge and the output bridge of the six IGBT tubes of the collector and the emitter can be judged to be whether or not the breakdown, otherwise there is a breakdown element inside. Pointer multimeter Bx1k block to measure the six IGBT tube gate and emitter resistance (drive signal input) should be the same, there are different when the drive circuit or IGBT tube damage. The above measurements can only measure the IGBT tube breakdown damage. Can not measure open-circuit damage. After removing the power module from the circuit board, you can make further measurements on each IGBT tube, and the needle on the left side indicates that it does not conduct. Table needle on the right side of the conductive. If you can not make it conductive and cut-off, then the tube is damaged.
TLP251 is commonly used inverter optocoupler drive circuit, when the power module breakdown is often spilled over the circuit. Its internal circuit and measurement method shown in Figure 2. When the ② foot by 3kΩ resistor and 10V power supply is disconnected or connected. Pin ⑥ has 0V or 9V high and low voltage changes.
Structure of the inverter power module:
The internal package of the inverter power module is partly a single-phase or three-phase bridge rectifier circuit composed of diodes, and partly a three-phase bridge output circuit composed of six IGBT tubes (insulated gate bipolar transistors) and six damping diodes used in conjunction with them.
P1 is +300V rectified output positive terminal, N1 is rectified output negative terminal, the two legs external filter electrolytic capacitor, and through the mutual inductance coil P1 and P2 connected, N l and N2 connected to the six IGBT tubes composed of the output bridge power supply.
Three-phase output bridge of the upper half of the bridge three IGBT tube collector are connected to the positive end of the power supply, the emitter was U, V, W three-phase output, three tube emitter and gate and constitute a three-phase upper half of the bridge drive signal inputs GU-U, GV-V, GW-W. Three-phase output bridge of the lower half of the bridge three IGBT tube collector were connected to the U, V, W, the emitter is connected to the negative end of the power supply, the three tube gate and the negative end of the power supply. The gates of the three tubes are connected to the negative side of the power supply, and the negative side of the power supply constitutes the three-phase lower half-bridge drive signal inputs GX, GY, GZ, and B is the braking control terminal.
TH is the internal thermistor protection output. Other models of general-purpose inverter power module pins and labelling on the circuit board, although different, but it is not difficult to identify the main function of the foot position. High-end products using intelligent power modules, internal drive circuit and braking circuit, pin corresponding to more.
Inverter power module as the name suggests is the inverter power electronic power devices according to a certain combination of functions and then encapsulated into a module. The inverter itself is composed of control unit and power module. In general, the inverter power module is through the use of shell and external electrode terminals of the integrated structure, to reduce the number of parts and reduce the internal wiring inductance of the purpose.
