Patent ID: 8552672
Filing Date: 2013-10-08
Classification: H02P

Abstract:
1. A method of controlling a motor drive for a two phase motor having two motor phase windings, each motor phase winding having a first end and a second end, the motor drive comprising a controller having at least one input and a plurality of outputs; a first half-bridge output stage, a second half-bridge output stage and a third half-bridge output stage, each half bridge output stage comprising: an output for coupling to a winding of a motor; a first switch having an input coupled to a DC voltage source, an output coupled to the output of the half-bridge, and a control input coupled to an output of the controller, such that a signal on the control input of the first switch couples the output of the first switch to the DC voltage source; and a second switch having an input coupled to a DC voltage source return, an output coupled to the output of the half-bridge, and a control input coupled to an output of the controller, such that a signal on the control input of the second switch couples the output of the second switch to the DC voltage source return, the method comprising: sending control signals to the control input of the first switch of the third half-bridge and to the control input of the second switch of the third half-bridge to produce a voltage at the output of the third half-bridge with an arbitrary duty cycle; sending control signals to the control input of the first switch of the first half-bridge and to the control input of the second switch of the first half-bridge to produce a voltage at the output of the first half-bridge with a selected duty cycle and a phase relative to the voltage at the output of the third half-bridge; sending control signals to the control input of the first switch of the second half-bridge and to the control input of the second switch of the second half-bridge to produce a voltage at the output of the second half-bridge with a selected duty cycle and a phase relative to the voltage at the output of the third half-bridge; modulating the phase and duty cycle of the first and second half bridge to form phase voltages to control the current in the motor phase windings of the two phase motor.