Abstract: Control apparatus includes an inverter having a plurality of switches arranged to generate a plurality of different voltage phases, and a switch arrangement having a rectifier arranged to be coupled to the respective plurality of coil windings. The rectifier is arranged to rectify an alternating current flowing in respective coil windings and provide the rectified AC current to a DC output, and a switch is coupled across the DC output. The switch is operable to electrically isolate the plurality of coil windings from each other. A controller is arranged to operate the switch to electrically isolate the plurality of coil windings upon a failure of an inverter switch or upon detection of a current flow in the inverter or the switch that is greater than a predetermined threshold.

Abstract: A switch arrangement for an electric motor or generator having a plurality of coil windings that during operation of the electric motor or generator are electrically coupled to form a star point connection and that are arranged to have different voltage phases applied across the respective coil windings, the switch arrangement comprising a rectifier arranged to be coupled to the respective plurality of coil windings, wherein the rectifier is arranged to rectify an alternating current flowing in the respective coil windings and provide the rectified AC current to a DC output; and a switch coupled across the rectifier DC output, wherein the switch is operable to electrically isolate the plurality of coil windings.