Current measurement using switch voltage drop in IGBT DC circuit breaker application

Electrical systems using solid-state devices and controlled by computer are being developed. The new architecture opens up possibilities of measuring current. In static DC circuit breaker, the current measurement can be carried out by means of switch voltage drop rather than other classical methods. This paper describes the design and the test results of this measuring principle in an IGBT DC circuit breaker. A computer along with an analogue circuit is used to estimate the IGBT junction temperature, to compensate the IGBT on-state characteristic drift, and then to compute the current from the voltage drop measurement. It is shown that such a design gives a good measure of precision in the current range of static circuit breaker applications