Electric drive systems

A fault-tolerant four-phase electric drive system, comprising:

• a rotary electric machine having a permanent magnet rotor and an alternate-wound stator having eight evenly-spaced coils 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 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 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 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 connected therewith;
• and
• a controller connected with the first, second, third and fourth phase drive circuits to control operation thereof,
• wherein the controller is configured to:
• cease operation of both the first phase and the third phase in response to loss of operation of one of the first phase and the third phase;
• and
• cease operation of both the second phase and the fourth phase in response to loss of operation of one of the second phase and the fourth phase,
• wherein the first phase drive circuit and third phase drive circuit are connected with a first dc bus;
• and the second phase drive circuit and the fourth phase drive circuit are connected with a second dc bus.