Abstract: An auxiliary power supply device includes: a plurality of channels of auxiliary power supplies; a charging circuit; and an auxiliary power supply switching circuit disposed between the charging circuit and positive electrode terminals of the plurality of channels of auxiliary power supplies and configured to switch one channel of auxiliary power supply connected to the charging circuit among the plurality of channels of auxiliary power supplies and to simultaneously switch one channel of auxiliary power supply connected to a power supply destination so as not to match the channel of auxiliary power supply connected to the charging circuit.

Abstract: An auxiliary power supply device includes: a plurality of channels of auxiliary power supplies; a charging circuit; and an auxiliary power supply switching circuit disposed between the charging circuit and positive electrode terminals of the plurality of channels of auxiliary power supplies and configured to switch one channel of auxiliary power supply connected to the charging circuit among the plurality of channels of auxiliary power supplies and to simultaneously switch one channel of auxiliary power supply connected to a power supply destination so as not to match the channel of auxiliary power supply connected to the charging circuit.

Abstract: When one of six FETs has short-circuit faulted, a controllable region identification unit stops driving of an electric motor, and then performs processes for determining whether a short-circuit fault has occurred, and when a short-circuit fault has occurred, for identifying the position of the FET that has short-circuit faulted based on phase voltages (induced voltages) VU, VV, and VW of phases. When the position of the FET that has short-circuit faulted is identified, the controllable region identification unit performs a controllable region identification process. In detail, the controllable region identification unit identifies a “possible region,” an “indeterminate region,” and a “impossible region” based on phase voltages VU, VV, and VW of the phases.

Abstract: When one of six FETs has short-circuit faulted, a controllable region identification unit stops driving of an electric motor, and then performs processes for determining whether a short-circuit fault has occurred, and when a short-circuit fault has occurred, for identifying the position of the FET that has short-circuit faulted based on phase voltages (induced voltages) VU, VV, and VW of phases. When the position of the FET that has short-circuit faulted is identified, the controllable region identification unit performs a controllable region identification process. In detail, the controllable region identification unit identifies a “possible region,” an “indeterminate region,” and a “impossible region” based on phase voltages VU, VV, and VW of the phases.