Driving apparatus for brushless motor
First Claim
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1. A driving apparatus for a brushless motor having a plurality of driving coils for different phases, comprising:
- switching means for switching voltages to said driving coils of said brushless motor,a switching signal generation circuit for controlling said switching means and for generating a switching signal,a phase difference detector for detecting a phase difference between a counter-electromotive voltage induced by one of said switching voltages in one of said plurality of driving coils and said switching signal in a time period that said induced voltage equals said one switching voltage,an amplifier for amplifying a detected signal of said phase difference detector and outputting an amplified signal, anda voltage-controlled oscillator for oscillating a signal controlled in frequency by said amplified signal and for supplying said oscillated signal to said switching signal generation circuit.
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Abstract
A phase difference between a counter-electromotive voltage induced in a driving coil and a voltage which is applied to the driving coil is detected by comparison of a terminal voltage of the driving coil and a reference voltage. A frequency of a voltage-control oscillator which controls switching of the voltage applied to the driving coil is varied by an output signal made by the comparison, and the phase difference is controlled to be reduced to zero.
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Citations
12 Claims
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1. A driving apparatus for a brushless motor having a plurality of driving coils for different phases, comprising:
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switching means for switching voltages to said driving coils of said brushless motor, a switching signal generation circuit for controlling said switching means and for generating a switching signal, a phase difference detector for detecting a phase difference between a counter-electromotive voltage induced by one of said switching voltages in one of said plurality of driving coils and said switching signal in a time period that said induced voltage equals said one switching voltage, an amplifier for amplifying a detected signal of said phase difference detector and outputting an amplified signal, and a voltage-controlled oscillator for oscillating a signal controlled in frequency by said amplified signal and for supplying said oscillated signal to said switching signal generation circuit. - View Dependent Claims (2, 3, 4, 5)
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6. A driving apparatus for a brushless motor having a plurality of driving coils for different phases, comprising:
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switching means for switching currents to said driving coils of said brushless motor, a switching signal generation circuit for controlling said switching means and for generating a switching signal, a phase difference detector for detecting a phase difference between a counter-electromotive voltage induced by one of said switching currents in one of said respective driving coils and said switching signal in a time period that said induced voltage corresponds to said one switching current, an amplifier for amplifying a detected signal by said phase difference detector and outputting an amplified signal, and a voltage control oscillator for oscillating a signal controlled in frequency by said amplified signal and for supplying said oscillated signal to said switching signal generation circuit, and a lowest frequency limiting circuit for limiting a lowest frequency of said voltage control oscillator. - View Dependent Claims (7)
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8. A driving apparatus for a brushless motor having a plurality of driving coils for different phases, comprising:
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switching means for switching currents to said driving coils of said brushless motor, a switching signal generation circuit for controlling said switching means and for generating a switching signal, a phase difference detector for detecting a phase difference between a counter-electromotive voltage induced by one of said switching currents in one of said respective driving coils and said switching signal in a time period that said induced voltage corresponds to said one switching current, an amplifier for amplifying a detected signal by said phase difference detector and outputting an amplified signal, and a voltage control oscillator for oscillating a signal controlled in frequency by said amplified signal and for supplying said oscillated signal to said switching signal generation circuit, and an oscillation frequency initializing means for initializing an oscillation frequency of said voltage control oscillator into a predetermined value. - View Dependent Claims (9, 10)
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11. A driving apparatus for a brushless motor having a plurality of driving coils for different phases, comprising:
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switching means for switching currents to said driving coils of said brushless motor, a switching signal generation circuit for controlling said switching means and for generating a switching signal, a phase difference detector for detecting a phase difference between a counter-electromotive voltage induced by one of said switching currents in one of said respective driving coils and said switching signal in a time period that said induced voltage corresponds to said one switching current, an amplifier for amplifying a detected signal by said phase difference detector and outputting an amplified signal, and a voltage control oscillator for oscillating a signal controlled in frequency by said amplified signal and for supplying said oscillated signal to said switching signal generation circuit, an oscillation frequency initializing means for initializing an oscillation frequency of said voltage control oscillator into a predetermined value, and an abnormal state detecting circuit for detecting an abnormal state of frequency of said voltage control oscillator and for controlling said oscillation frequency initializing means during said abnormal state. - View Dependent Claims (12)
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Specification