Closed loop control of PWM duty cycle
AssigneeMTS Systems Corporation
InventorsKenneth W. Goff, Jerry K. Goff, Brian J. Fenstermacher
Life of this patent
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Abstract
A system and method for controlling energization of an electric motor (rotating or linear). The system and method includes producing a pulse-width modulated command signal to control switching devices that connect the motor to an energization source. A pulse-width modulated duty cycle value is formed as a function of the pulse-width modulated command signal. A leading current with respect to the phase angle of the back EMF is provided to the motor as a function comparing the pulse-width modulated duty cycle value with a selected threshold.
Claims22
A system for controlling energization of an electric motor from an electric power source, the system comprising:
- a switching circuit including switching devices to selectively connect windings of the motor to the power source;
- a pulse-width modulator capable of producing a pulse-width modulated command signal to control the switching devices;
- and
- a circuit receiving the pulse-width modulated command signal and comparing a parameter thereof with a selected threshold to generate a phase adjustment signal, the phase adjustment signal being indicative of a selected leading current to be provided to windings of the motor.
A motor control system comprising:
- a brushless direct current motor including:
- a set of stator windings;
- a rotor movable relative -to the set of stator windings;
- a sensor providing a signal indicative of a phase angle of a back EMF of the motor;
- a switching circuit including switching devices to selectively connect windings of the motor to a power source;
- a pulse-width modulator capable of producing a pulse-width modulated command signal to control the switching circuit;
- a circuit receiving the pulse-width modulated command signal and comparing a parameter thereof with a selected threshold to generate a phase adjustment signal;
- and
- means for adjusting a phase of current provided to the motor with respect to the phase angle of the back EMF as a function of the phase adjustment signal.
A method for controlling energization of an electric motor from an electric power source using a switching circuit including switching devices to selectively connect windings of the motor to the power source, the method comprising:
- producing a pulse-width modulated command signal to control the switching devices;
- forming a pulse-width modulated duty cycle value as a function of the pulse-width modulated command signal;
- and
- adjusting a phase relationship of current provided to the motor as a function of comparing the pulse-width modulated duty cycle value with a selected threshold.
Dependencies are inferred from the claim text.