A synchronous machine with 3-phase sensors set 120.degree. apart and 90.degree. advanced is used to provide commutation from a direct current source. A time delay circuit with an electronically implemented algorithm controls torque by delaying the 90.degree. advance. This delay is controlled by a linear voltage, independent of frequency, and can be used to control position, speed, or acceleration. A delay beyond 90.degree. advance causes commutation to cease, and the alternating current machine switches to a generator, indicative of motive power being applied. If motive power ceases, the alternating current machine switches to a motor. Controlled switching can be less than half of one hertz.