Controller for brushless DC motor with low torque ripple and method therefor
AssigneeSilicon Laboratories Inc.
InventorKok Hong Soh
Life of this patent
Estimating the term…
Abstract
A controller for a BLDC motor includes a pulse width modulator and a control circuit. The pulse width modulator provides at least one phase control signal for a corresponding phase of the BLDC motor with a pulse width determined by a duty cycle signal. The duty cycle adjustment circuit has an input for receiving the at least one phase control signal, and an output for providing a corresponding modified phase control signal by adjusting widths of pulses of the at least one phase control signal when an average current in said corresponding phase exceeds a threshold.
Claims20
A controller for a BLDC motor, comprising:
- a pulse width modulator for providing at least one phase control signal for a corresponding phase of the BLDC motor with a pulse width determined by a duty cycle signal;
- and
- a duty cycle adjustment circuit having a first input for receiving said at least one phase control signal, a second input for receiving a measured current signal, and an output, wherein said duty cycle adjustment circuit integrates said measured current signal to form an average current signal, and provides a corresponding modified phase control signal by adjusting widths of pulses of said at least one phase control signal when said average current signal in said corresponding phase exceeds a threshold.
A BLDC motor system, comprising:
- a processor having a first output for providing a duty cycle signal;
- a pulse width modulator having an input for receiving said duty cycle signal, and an output for providing a plurality of phase control signals to control corresponding ones of a plurality of phases of a BLDC motor, each phase control signal active for a time corresponding to said duty cycle signal;
- and
- a duty cycle adjustment circuit having first inputs for receiving said plurality of phase control signals, a second input for receiving a measured current signal, and an output for providing a corresponding plurality of modified phase control signals by deactivating pulses of said plurality of phase control signals in response to an average of said measured current signal.
A method for use with a BLDC motor comprising:
- driving a plurality of phases of the BLDC motor by generating a corresponding plurality of pulse width modulated control signals each having a duty cycle;
- measuring current in the BLDC motor to determine a measured current;
- integrating said measured current to provide an average current signal;
- and
- reducing said duty cycle of said pulse width modulated control signals based on a time when said average current signal exceeds a threshold, wherein reducing said duty cycle occurs by modifying said pulse width modulated control signals.
Dependencies are inferred from the claim text.