A case of saving money for inverter repair

An Alpha ALPHA2000 2.2kW frequency converter, the power switch is tripped during operation and cannot be closed for operation. Send it for repair. Measure the resistance of R, T, S terminals, short Circuit between T and S terminals, short circuit between S, P, T and P, and open circuit between S, N, T and N. The user declares that if it is too expensive to repair, it is only willing to pay a repair fee of about 300 yuan, and it can be used for half a year after repair.

I carefully inspected the internal inverter circuit part of the module and the energy storage capacitor. No problem was found. The DC 500V power supply was directly fed to the DC loop, and the start-up operation test was performed, and it was normal. It was judged that the fault was only in the internal rectifier circuit of the module, and based on the measured short-circuit and open circuit conditions of the internal rectifier bridge, it was decided to overlap two IS2510 rectifier Circuits from the outside to repair the machine. The purpose of not using a single rectifier tube is the rectifier bridge component, which is a chip plastic package and has a fixed hole, which is good for heat dissipation and fixation during work.

The partial repair of the above power module only repairs the rectifier circuit, and the repair success rate is relatively high. The integrated module contains a temperature detection circuit. The temperature detection signal of the module is led out through two terminals. When the internal rectifier circuit or inverter circuit of the module is damaged, it may affect the temperature detection circuit and also be damaged at the same time. It can also be used by an external temperature detection circuit. Implement repairs. The common module temperature detection circuit forms are as follows:

The module temperature detection circuit is composed of components such as thermistors inside the module, and the output is a linear voltage temperature signal. After the signal is output, some are directly input to the CPU pin, and some are further processed by the subsequent temperature detection circuit, and then sent to the CPU circuit. TECO 7300PA 3.7kW inverter module temperature detection circuit, the two pins T1 and T2 of the inverter module are the module temperature detection signal output pins, the T2 pin is directly grounded, and the T1 pin is connected to a +5V pull-up resistor. When the circuit is normal and the module temperature is within the normal range, the voltage range of pin T1 is low. When the temperature of the module rises abnormally, after the voltage of pin T1 rises to a certain range, the inverter will report the module overheating fault and the inverter will stop automatically.