Drive apparatus and drive method for brushless motor
AssigneeHitachi Automotive Systems, Ltd.
InventorMasaki Hano
Life of this patent
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Abstract
A drive apparatus and a drive method for a brushless motor, capable of reducing noise occurring due to pulse shift processing, is provided. The drive apparatus for the brushless motor comprises one shunt resistor and a controller. The shunt resistor measures a phase current of the three-phase brushless motor. The controller measures the phase current of the brushless motor in a one-shunt system by using the shunt resistor, and controls driving of the brushless motor based on the measured phase current. The controller performs pulse shift when a voltage pulse width in a drive wire of the brushless motor is greater than a predetermined value, whereas the controller does not perform the pulse shift when the voltage pulse width is less than the predetermined value.
Claims17
A drive apparatus for a three-phase brushless motor, comprising:
- a shunt resistor for measuring a phase current of the brushless motor;
- and
- a controller that measures the phase current of the brushless motor in a one-shunt system by using the shunt resistor, and controls driving of the brushless motor based on the measured phase current, in which the controller performs pulse shift when a voltage pulse width in a drive wire of the brushless motor is greater than a predetermined value, whereas the controller does not perform the pulse shift when the voltage pulse width is less than the predetermined value;
- wherein the controller comprises a drive circuit that drives the brushless motor, and a control unit that controls the drive circuit;
- and
- wherein the control unit includes a pulse shift processing unit that performs pulse shift processing, wherein the pulse shift processing unit corrects a voltage with a first correction amount during a monotonically increasing period of a triangular-wave carrier, and corrects the corrected voltage with a second correction amount during a monotonically decreasing period following the monotonically increasing period, so that an average of the first and second correction amounts becomes zero.
A method for driving a three-phase brushless motor by measuring a phase current in a one-shunt system, the method comprising the steps of:
- measuring a voltage pulse width in a drive wire of the brushless motor;
- comparing the measured voltage pulse width with a predetermined value;
- and
- performing pulse shift when the measured voltage pulse width is greater than the predetermined value, whereas not performing the pulse shift when the measured voltage pulse width is less than the predetermined value;
- wherein performing the pulse shift comprises correcting a voltage during a monotonically increasing period of a triangular-wave carrier, subtracting the correction amount from the corrected voltage during a monotonically decreasing period following the monotonically increasing period, so that an averaged voltage becomes zero, to perform a current measurement.
Dependencies are inferred from the claim text.