Programmable pulse width modulated waveform generator for a spindle motor controller
AssigneeAgere Systems Guardian Corp.
InventorsDavid W. Kelly, Jason P. Brenden, Michael J. Peterson
Life of this patent
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Abstract
A motor controller for a three-phase spindle motor used in the hard disc drive provides pulse width modulated (PWM) signals used to drive the motor. The PWM signals have duty cycles which are a function of rotational position of the motor, a magnitude control signal, a stored set of main waveform coefficients, a stored set of modifier coefficients, and a modifier signal. By varying the modifier signal, the duty cycle of the PWM signals can be varied to adjust the shape of the motor current waveform to match the torque profile of the motor.
Claims11
A motor controller for an electric motor which provides pulse width modulated drive signals to the electric motor, the motor controlling including:
- a pulse width modulation (PWM) controller for controlling duty cycles of the pulse width modulated drive signals as a function of a set of main waveform coefficients, a set of modifier coefficients, a rotational position of the motor, a magnitude control signal, and a modifier signal.
A motor controller for an electrical motor, the motor controller comprising:
- a plurality of motor drivers for connection to the electrical motor;
- commutation logic for providing motor drive signals to the motor drivers as a function of the a commutation state code and pulse width modulation clock signals;
- and
- a pulse width modulation controller for providing the pulse width modulation clock signals as a function of a first set of coefficients, a second set of coefficients, a first control signal which represents a current demand, and a second control signal which represents a selected waveform shape formed by a combination of the first and second sets of coefficients.
A method of producing a pulse width modulation clock signal having a variable duty cycle as a function of rotational position of a motor, the method comprising:
- storing a first set of coefficients for different rotational positions;
- storing a second set of coefficients for different rotational positions;
- selecting coefficients from the first and second sets based upon rotational position;
- combining the coefficients selected as a function of an adjust signal to produce a combined coefficient;
- and
- providing the pulse width modulation clock signal with a duty cycle which is a function of the combined coefficient.
Dependencies are inferred from the claim text.