Control circuit for a multi-phase motor

A control circuit for a multi-phase motor, the control circuit comprising:

• a plurality of inverter bridges, each inverter bridge being arranged to provide an output voltage for a phase of the motor;
• a plurality of outputs, each output being arranged to be coupled to one phase of the motor to provide the output voltage to that phase of the motor;
• and
• at least one isolation switch, each isolation switch being coupled between one of the inverter bridges and one of the outputs, so as to selectively isolate the output from the inverter bridge;
• in which the each isolation switch comprises a Gallium Nitride (GaN) transistor.

A motor apparatus comprising a motor having a plurality of phases and a control circuit, wherein the control circuit comprises

• a plurality of inverter bridges, each inverter bridge being arranged to provide an output voltage for a phase of the motor;
• a plurality of outputs, each output being arranged to be coupled to one phase of the motor to provide the output voltage to that phase of the motor;
• and
• at least one isolation switch, each isolation switch being coupled between one of the inverter bridges and one of the outputs, so as to selectively isolate the output from the inverter bridge;
• in which the each isolation switch comprises a Gallium Nitride (GaN) transistor, and wherein
• each phase is coupled to one of the outputs of the control circuit.

A method of controlling a control circuit for a multi-phase motor, the control circuit comprising:

• a plurality of inverter bridges, each inverter bridge being arranged to provide an output voltage for a phase of the motor;
• a plurality of outputs, each output being arranged to be coupled to one phase of the motor to provide the output voltage to that phase of the motor;
• and
• at least one isolation switch, each isolation switch being coupled between one of the inverter bridges and one of the outputs, so as to selectively isolate the output from the inverter bridge;
• in which the each isolation switch comprises a Gallium Nitride (GaN) transistor;
• the method comprising, in a normal mode of operation, closing each isolation switch by causing each GaN transistor to conduct, and in a phase isolation mode of operation, isolating at least one output from the inverter bridge to which it is coupled by opening at least one isolation switch by causing each GaN transistor to cease conducting.