Patent ID: 6163120
Filing Date: 2000-12-19
Classification: H02P

Abstract:
A back electromotive force (emf) reconstruction circuit for reconstructing the back emf on a floating coil of a polyphase direct current (dc) motor in a pulse width modulation (PWM) mode, the back emf reconstruction circuit comprising:a first capacitor having a first side coupled to a first power supply voltage and a second side switchably coupled to a floating phase voltage of the floating coil of the motor;a first current source switchably coupled to the second side of the first capacitor in response to a back emf control signal when in a second logic state and for charging the first capacitor; anda second current source switchably coupled to the second side of the first capacitor in response to the back emf control signal when in a second logic state and for discharging the first capacitor.