Feedback circuit for eliminating DC offset in drive current of an AC motor
First Claim
Patent Images
1. A motor control for an electric motor powered by an AC pulse source which applies current pulses to stator windings of the motor to cause rotation of a rotor comprising:
- means for sensing a net DC current in the current pulses over a period of time flowing to the stator windings and producing a negative feedback signal which is a function of the sensed net DC current during rotation of the motor; and
a pulse width modulator, coupled to the net DC current sensing means varying pulse width modulation of the current pulses in response to the negative feedback signal to reduce the net DC current toward zero during rotation of the motor.
0 Assignments
0 Petitions
Accused Products
Abstract
A motor control (10) for a motor (12) powered by an AC pulse source which applies current pulses to stator windings of the motor to cause rotation of the motor in accordance with the invention includes a current sensor (18) for sensing a DC net current in the current pulses flowing to the stator windings; a pulse width modulator (26-58) for pulse width modulating the current pulses; and wherein the width of the pulses is modulated in response to the sensed net current to reduce the net current towards zero.
39 Citations
18 Claims
-
1. A motor control for an electric motor powered by an AC pulse source which applies current pulses to stator windings of the motor to cause rotation of a rotor comprising:
-
means for sensing a net DC current in the current pulses over a period of time flowing to the stator windings and producing a negative feedback signal which is a function of the sensed net DC current during rotation of the motor; and a pulse width modulator, coupled to the net DC current sensing means varying pulse width modulation of the current pulses in response to the negative feedback signal to reduce the net DC current toward zero during rotation of the motor. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17)
-
-
18. A method of controlling an electric motor powered by an AC pulse source which applies current pulses to stator windings of the motor to cause rotation of a rotor comprising:
-
sensing a net DC current in the current pulses over a period of time flowing to the stator windings during rotation of the motor and producing a negative feedback signal which is a function of the sensed net DC current; and varying pulse width modulation of the current pulses in response to the negative feedback signal to reduce the net DC current toward zero during rotation of the motor.
-
Specification