US Patent 9276447 Electrical machines

An electrical machine (10) has three phase windings (12). Each phase winding (12) is connected to a respective current source (18). Each current source 18 provides alternating current to the corresponding winding (12). The current source 18 is connected independently to the respective winding (12). The electrical angles of the phase windings (12) are so arranged that none of the phase windings (12) has a zero torque angle which coincides with a zero torque angle of another phase winding (12).