Patent ID: 7339394
Filing Date: 2008-03-04
Classification: H02M,H02P

Abstract:
1. An apparatus for measuring current by a single sensor for two motor phases, the apparatus comprising: a pulse width modulation controller; a switching circuit including a first set of upper and lower switches to drive a first phase of a motor using a voltage from a power source, the first set of switches being controlled by a plurality of pulse width modulation signals from the pulse width modulation controller, and the switching circuit including a second set of upper and lower switches to drive a second phase of the motor using the voltage from the power source, the second set of switches being controlled by a plurality of pulse width modulation signals from the pulse width modulation controller, wherein the pulse width modulation controller is operable to gate the first and second set of switches to provide a relative timing offset of approximately one-half cycle between the pulse width modulation signals driving a first winding and a second winding of the motor, and wherein the controller configures the pulse width modulation signals to provide at least one timing window wherein at least of one of the windings of the motor is being driven while the other winding is not being driven; and a current sensor connected between the power source and the switching circuit to sample a current in the at least one of the windings during the at least one timing window.