A power converter having a first switch and a first unidirectional current device that conducts current unidirectionally. The first switch and first unidirectional current device are interconnected such that when interconnected with a dc voltage supply, battery, and first phase winding of an electrical machine: (1) a first operational state exists in which a conductive state of the first switch causes the dc voltage supply to conduct current through the first switch and first phase winding, so as to store energy within the first phase winding and (2) a second operational state exists in which a non-conductive state of the first switch causes the first phase winding to discharge its stored energy by conducting current through the first unidirectional current device and battery, so as to store energy in the battery.