CPC H02P 27/047 (2013.01) [H02P 23/28 (2016.02); H02P 27/08 (2013.01)] | 20 Claims |
1. An electric motor system comprising:
a drive circuit comprising a contactor, an inverter, and an H-bridge comprising at least two phases of the inverter, wherein the drive circuit is configured to supply variable frequency current and line frequency current; and
a controller communicatively coupled to the drive circuit, wherein the controller is configured to:
determine a polarity of a sensed alternating current (AC) voltage while the drive circuit is supplying variable frequency current;
disable, based upon the determined polarity of the sensed AC voltage, at least two switches of the H-bridge; and
control the contactor to close, thereby preventing the contactor and the inverter from energizing an electric motor at the same time.
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