Electric drive systems

Fault-tolerant four-phase electric drive systems are provided. One such system comprises: a rotary electric machine 112 having a permanent magnet rotor 301 and an alternate-wound stator 302 having eight evenly-spaced coils 303-310 arranged in pairs, each coil in each pair being separated by 180 degrees; a first phase (ΦA) comprising a first one of the coil pairs and a first phase drive circuit 201 connected therewith; a second phase (ΦB) separated by +45 degrees from the first phase and comprising a second one of the coil pairs and a second phase drive circuit 202 connected therewith; a third phase (ΦC) separated by +90 degrees from the first phase and comprising a third one of the coil pairs and a third phase drive circuit 203 connected therewith; a fourth phase (ΦD) separated by +135 degrees from the first phase and comprising a fourth one of the coil pairs and a fourth phase drive circuit 204 connected therewith; and a controller 205 connected with the first, second, third and fourth phase drive circuits 201-204 to control operation thereof.