Variable speed drive

摘要

A converter module for a variable speed drive having a semiconductor device for precharge is described. The precharge circuit includes switching modules, one switching module with a first semiconductor switch connected in parallel or series with a second semiconductor switch. The second semiconductor switch is switched on and off during the precharge operation in order to limit the inrush current into the DC Link. After the precharge operation, the second semiconductor switch is turned on all the time and acts like a diode. The second semiconductor device may have a lower maximum current rating than the main semi-conductor devices. The lower current rated semiconductor device experience the same short circuit current as the higher current rated semiconductor device. The lower current rated semiconductor device can be supplied with a larger gate to emitter voltage than the higher current rated semiconductor device to equalize current between semiconductor devices.

主权项

1. A converter module for a variable speed drive comprising: a plurality of switching modules, one switching module of the plurality of switching modules comprising a first semiconductor switch connected in anti-parallel or series with a second semiconductor switch, the second semiconductor switch being controllably switched during a precharge operation of the variable speed drive to limit an inrush current into the DC link, and the second semiconductor switch comprising a maximum current rating less than a maximum current rating of the first semiconductor switch;
wherein the first semiconductor switch is controlled by applying a first voltage, and the second semiconductor switch is controlled by a second voltage greater than the first voltage.