Necessary Knowledge When Frequency Converter Failure (III)

In general, the main circuit devices of medium and small capacity inverter usually adopt integrated module or intelligent module. The intelligent module has a high degree of integration of rectifier module, inverter module, various sensors, protection circuit and drive circuit. For example, IPMPM50RSA120 produced by Mitsubishi, 7MBP50RA060 produced by Fuji, BSM50GD120 produced by Siemens, etc. are integrated with rectifier module, power factor correction circuit, IGBT inverter module and various detection and protection functions. The typical switching frequency of the module is 20kHz, and the protection function is to output the fault signal lamp under voltage, overvoltage and overheating fault.

The inverter circuit is provided with a continuous current circuit. The function of the circuit is that when the frequency drops, the synchronous speed of the asynchronous motor also drops. Provides the channel for the regenerative electric energy of the asynchronous motor to feed back to the DC circuit. In the inverter process, the parasitic inductor releases energy to provide the channel. In addition, when two switches located on the same bridge arm are on at the same time, the phenomenon of short circuit will occur and the converter device will be destroyed. In order to ensure the normal operation of the circuit and protect the converter in the event of accident, there are various auxiliary circuits such as buffer circuit in the practical universal frequency converter.

When your frequency converter is abnormal, in order to reduce the frequency converter due to abnormal losses to the minimum, or even reduce to zero. Each brand of frequency converter attaches great importance to the protection function, try to increase the protection function, improve the effectiveness of the protection function. In the field of inverter protection function, manufacturers can do their best to do a good job of the article. In this way, it forms the diversity and complexity of inverter protection circuit. It has routine detection and protection circuit and comprehensive protection function of software. Some inverter drive circuit module, intelligent power module, rectifier inverter combination module, etc. have the protection function inside.