Patent attributes
A drive circuit for an electric motor includes a variable frequency drive (VFD), a drive contactor, and a controller. The VFD is configured to receive line frequency current from a power source and apply a fixed frequency voltage to convert the line frequency current to a fixed frequency current. The drive contactor is configured to selectively couple the drive circuit to windings of the motor. The controller is configured to monitor for presence of a control signal applied to the drive contactor, wherein presence of the control signal closes the drive contactor to couple the drive circuit to the windings of the electric motor. The controller applies the fixed frequency voltage from the VFD to the windings upon determining presence of the control signal, determines whether the motor is motoring or regenerating after applying the fixed frequency voltage, and gradually increases the fixed frequency voltage applied to the windings when the motor is motoring.
