Permanent magnet machine fault protection

A system comprising:

• a permanent magnet (PM) machine including a first phase winding, a second phase winding, and a third phase winding and a permanent magnet configured to rotate relative to the first, second, and third phase windings, wherein the first phase winding has a first main leg and a first return leg extending from the first phase winding, wherein the second phase winding has a second main leg and a second return leg extending from the second phase winding, and wherein the third phase winding has a third main phase leg and a third return leg extending from the third phase winding;
• and
• a return switch unit operatively connected to the return legs of the first, second, and third phase windings, wherein the return switch unit includes a switch;
• wherein the switch is a triple pole single throw (3PST) switch configured to (i) connect the return legs of the first, second, and third phase windings to a neutral node in a normal state and (ii) disconnect the return legs of the first, second, and third phase windings from the neutral node in a fault protection state.

A method of fault protection comprising:

• rotating a permanent magnet relative to a plurality of phase windings in a permanent magnet (PM) machine;
• detecting a fault between at least two of the phase windings or a ground fault of one or more of the phase windings;
• disconnecting respective return legs of all of the phase windings from a neutral node;
• and
• allowing the permanent magnet to continue to rotate relative to the plurality of phase windings after the return legs are disconnected from the neutral node;
• wherein the neutral node is a floating or grounded neutral node that is connected only to the return legs of the phase windings via a switch.