Three-phase inverter system including control circuit to detect failure in an output current sensor

Abstract

A three-phase inverter system, in one configuration, includes an inverter main circuit and a control circuit. The inverter system includes current sensors which detect output currents in, for example, U- and W-phases, respectively, the inverter main circuit includes a semiconductor switching device with a current sense which is provided in, for example, the V-phase. The control circuit is configured to detect current values from the current sensors inputted thereto and produce driving signals, which drive the upper-arm and lower-arm semiconductor switching devices of the inverter main circuit, based on the detected current values, estimate, based on a detected signal from the semiconductor switching device with the current sense, an output current value in the one of the three series circuits, and detect failure in at least one of the current sensors based on the detected current values from the two current sensors and the estimated output current value.