Motor winding neutral switching

A motor system, comprising:

• a stator including a plurality of permanent magnets;
• a rotor situated to rotate relative to the stator;
• a plurality of phase windings including first, second and third phase windings situated in the stator;
• a power circuit connected to the phase windings, wherein the power circuit includes a power inverter;
• a controller configured to output control signals to the power circuit to selectively energize the phase windings to cause the rotor to rotate relative to the stator;
• a neutral switch circuit connected between the phase windings and a neutral node and configured to selectively disconnect the phase windings from the neutral node;
• first, second and third sense resistors connected between the power inverter and the respective first, second and third phase windings, and
• wherein the controller is configured to output a control signal to the neutral switch circuit to selectively disconnect the phase windings from the neutral node.

A motor control system, comprising:

• a first switch having a first terminal and a second terminal, the first terminal configured for connection to a first phase winding of a three phase brushless DC (BLDC) motor;
• a second switch having a first terminal and a second terminal, the first terminal configured for connection to a neutral node of the BLDC motor, the second terminal connected to the second terminal of the first switch;
• a third switch having a first terminal and a second terminal, the first terminal configured for connection to a second phase winding of the BLDC motor;
• a fourth switch having a first terminal and a second terminal, the first terminal configured for connection to the neutral node of the BLDC motor, the second terminal connected to the second terminal of the third switch;
• and
• a controller configured to output a control signal to the first, second, third and fourth switches to selectively disconnect the first and second phase windings of the BLDC motor from the neutral node in response to a fault in at least one phase winding of the BLDC motor.

A method, comprising:

• providing a three phase brushless DC (BLDC) motor having first, second and third phase windings;
• providing a first MOSFET having a drain terminal and a source terminal, the drain terminal connected to the first phase winding;
• providing a second MOSFET having a drain terminal and a source terminal, the drain terminal connected to a neutral node of the BLDC motor, the source terminal connected to the source terminal of the first MOSFET;
• providing a third MOSFET having a drain terminal and a source terminal, the drain terminal connected to the second phase winding;
• providing a fourth MOSFET having a drain terminal and a source terminal, the drain terminal connected to the neutral node of the BLDC motor, the source terminal connected to the source terminal of the third MOSFET;
• outputting a first control signal to the first, second, third and fourth MOSFETs to connect the first and second phase windings to the neutral node;
• and
• outputting a second control signal to the first, second, third and fourth MOSFETs to selectively disconnect the first and second phase windings from the neutral node in response to a fault in at least one of the first, second and/or third phase windings.