Patent ID: 7193378

Claim:
A circuit for controlling a multi-phase machine having a stator with plural stator windings, the circuit comprising: a controller; a plurality of primary commutation switch pairs, each switch pair including first and second primary commutation switches connected at a respective node; a neutral terminal; and a plurality of commutation control switches, each commutation control switch being coupled to a corresponding winding of the stator windings so that a corresponding stator winding circuit is formed between the neural terminal and a respective one of the nodes, wherein each commutation control switch includes a first diode connected in parallel with a series switch circuit, wherein each series switch circuit includes a second diode and a switch element, the switch element being connected in series with the second diode, and wherein the controller is coupled to the switch element in each of the commutation control switches and to the primary commutation switch pairs to control an on time and an off time of the primary commutation switches relative to a point where a supply voltage is equal to the back emf.