Control apparatus for brush-less motor
First Claim
1. A control apparatus for a brush-less motor, comprising:
- inverter means for energizing the brush-less motor;
β
control means for controlling an operation of said inverter means, in accordance with an internal control signal;
detector means for detecting a counterelectromotive force generated by said brush-less motor, and providing an EMF signal representing said counterelectromotive force;
PLL means for comparing a phase of said EMF signal with that of said internal control signal, and controlling said β
control means by said internal control signal, such that a phase difference between said internal control signal and said EMF signal becomes minimal; and
check means, coupled to said PLL means and said β
control means, for checking an amount of the phase difference between said internal control signal and said EMF signal, and when a checked amount of the phase difference is found to have reached or exceeded a predetermined amount, modifying the operation of said β
control means so that a commutation failure of said inverter means is prevented.
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Abstract
Disclosed is a control apparatus for a brush-less motor, which can prevent commutation failure of an inverter for driving the motor. The control apparatus, according to the invention detects a counter EMF of the motor, and the detected counter EMF is applied to a PLL circuit. In the course of normal operation of the motor, an output of the PLL circuit is used for controlling the advanced control angle of a motor drive inverter. Any abnormality in the condition of the motor, such as that arising from an abrupt change in load of the motor, causes a sudden and substantial variation in the magnitude and phase of the counter EMF. Since the internal condition of the PLL circuit changes in response to this counter EMF variation, a signal generated by the PLL circuit is therefore used to detect the counter EMF variation. This internal signal is compared with a predetermined limit level, and when its signal level is found to exceed this limit level, operation of the motor drive inverter is stopped, whereby commutation failure of the inverter is prevented.
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Citations
15 Claims
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1. A control apparatus for a brush-less motor, comprising:
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inverter means for energizing the brush-less motor; β
control means for controlling an operation of said inverter means, in accordance with an internal control signal;detector means for detecting a counterelectromotive force generated by said brush-less motor, and providing an EMF signal representing said counterelectromotive force; PLL means for comparing a phase of said EMF signal with that of said internal control signal, and controlling said β
control means by said internal control signal, such that a phase difference between said internal control signal and said EMF signal becomes minimal; andcheck means, coupled to said PLL means and said β
control means, for checking an amount of the phase difference between said internal control signal and said EMF signal, and when a checked amount of the phase difference is found to have reached or exceeded a predetermined amount, modifying the operation of said β
control means so that a commutation failure of said inverter means is prevented. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. A method for controlling a brush-less motor, comprising:
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energizing the brush-less motor by means of an inverter; controlling an operation of said inverter by means of a β
controller, in accordance with an internal control signal;detecting a counterelectromotive force generated by said motor, and providing an EMF signal representing said counterelectromotive force; comparing a phase of said EMF signal with that of said internal control signal, and controlling said β
controller in accordance with said internal control signal such that a phase difference between said internal control signal and said EMF signal becomes minimal; andchecking an amount of the phase difference between said internal control signal and said EMF signal, and when a checked amount of the phase difference is found to have reached or exceeded a predetermined limit level, modifying the operation of said β
controller so that a commutation failure of said inverter is prevented. - View Dependent Claims (11, 12, 13, 14, 15)
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Specification