Driving circuit for brushless DC motors
First Claim
1. A driving circuit for a brushless DC motor, comprising:
- a magnetic pole position detecting circuit for detecting postions of magnetic poles of a rotor magnet of the motor and delivering polyphase signals indicative of the positions;
a rectifier adder circuit for producing a sum of positive or negative portions of the polyphase signals from the magnetic pole position detecting circuit;
an instruction signal producing circuit for producing a torque instruction signal instructing a torque to be produced by the motor;
a first error amplifier for adjusting a gain of the magnetic pole position detecting circuit so as to make an output signal from the rectifier adder circuit be proportional to the torque instruction signal;
a power supply circuit responsive to the polyphase signals for supplying currents to polyphase armature coils of the motor;
a current detecting means for detecting the currents supplied to the armature coils;
a modulating signal producing circuit for modulating the currents supplied to the armature coils; and
a second error amplifier for adjusting a gain of the power supply circuit so as to make an output signal from the current detecting means equal to an output signal from the modulating signal producing circuit.
1 Assignment
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Accused Products
Abstract
A driving circuit for a brushless DC motor having a small amount of torque ripple comprises a magnetic pole position detecting circuit for detecting positions of magnetic poles of a rotor magnet and delivering polyphase signals indicating the positions, a rectifier adder circuit for producing a sum of positive or negative portions of the polyphase signals from the magnetic pole position detecting circuit, a first error amplifier for adjusting a gain of the magnetic pole position detecting circuit to make an output signal of the rectifier adder circuit to be proportional to an instruction signal, a power supply circuit for supplying currents to armature coils in response to the polyphase signals, a modulating signal producing circuit for producing a modulating signal synchronized with the rotation of the motor, and a second error amplifier for adjusting a gain of the power supply circuit to make the currents supplied to the armature coils to be proportional to the modulating signal.
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Citations
17 Claims
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1. A driving circuit for a brushless DC motor, comprising:
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a magnetic pole position detecting circuit for detecting postions of magnetic poles of a rotor magnet of the motor and delivering polyphase signals indicative of the positions; a rectifier adder circuit for producing a sum of positive or negative portions of the polyphase signals from the magnetic pole position detecting circuit; an instruction signal producing circuit for producing a torque instruction signal instructing a torque to be produced by the motor; a first error amplifier for adjusting a gain of the magnetic pole position detecting circuit so as to make an output signal from the rectifier adder circuit be proportional to the torque instruction signal; a power supply circuit responsive to the polyphase signals for supplying currents to polyphase armature coils of the motor; a current detecting means for detecting the currents supplied to the armature coils; a modulating signal producing circuit for modulating the currents supplied to the armature coils; and a second error amplifier for adjusting a gain of the power supply circuit so as to make an output signal from the current detecting means equal to an output signal from the modulating signal producing circuit. - View Dependent Claims (2, 3, 4, 5)
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6. The driving circuit as set forth in calim 1, wherein said current detecting means passes the currents to be supplied to the polyphase armature coils through a common resistor so as to convert a sum of the currents into a voltage.
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7. A driving circuit for a brushless DC motor, comprising:
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a magnetic pole position detecting circuit for detecting positions of magnetic poles of a rotor magnet of the motor and delivering polyphase signals indicative of the positions; a subractor citcuit for producing difference signals corresponding to the difference between two of the polyphase signals from the magnetic pole position detecting circuit; a rectifier adder circuit for producing a sum of positive or negative portions of the difference signals from the subtractor circuit; an instruction signal producing circuit for producing a torque instruction signal instructing a torque to be proudced by the motor; a first error amplifier for adjusting a gain of the magnetic pole position detecting circuit so as to make an output signal from the rectifier adder circuit be proportional to the torque instruction signal; a power supply circuit responsive to the difference signals for supplying currents to polyphase armature coils of the motor; a current detecting means for detecting the currents supplied to the armature coils; a modulating signal producing circuit for modulating the currents supplied to the armature coils; and a second error amplifier for adjusting a gain of the power supply circuit so as to make an output signal from the current detecting means equal to an output signal from the modulating signal producing circuit. - View Dependent Claims (8, 9, 10, 11)
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12. A driving circuit for a brushless DC motor, comprising:
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a plurality of a magnetoelectric converter devices mounted on a stator of the motor for detecting a magnetic field generated by a rotor magnet of the motor; buffer amplifiers for amplifying output signals from the magnetoelectric converter devices; a subtractor circuit for producing different signals corresponding to the difference between two of the output signal from the buffer amplifiers; a rectifier adder circuit for producing a sum of positive or negative portions of the difference signals from the subtractor circuit; an instruction signal producing circuit for producing a torque instruction signal indicating a torque to be produced by the motor; a first error amplifier for adjusting gains of the buffer amplifiers so as to make an output signal from the rectifier adder circuit be proportional to the torque instruction signal; a power supply circuit responsive to the difference signals from the subtractor circuit for supplying currents to polyphase armature coils of the motor; a current detecting means for detecting the currents supplied to the armature coils; a modulating signal producing circuit for modulating the currents supplied to the armature coils; and a second error amplifier for adjusting a gain of the power supply circuit so as to make an output signal from the current detecting means equal to an output signal from the modulating signal producing circuit. - View Dependent Claims (15, 16, 17)
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- 13. The driving circuit as set forth inclaim 12, wherein said modulating signal producing circuit comprises an absolute value adder circuit for converting the output signals from the buffer amplifiers into absolute values and summing said values, and a combining circuit for producing a combination signal from the absolute value adder circuit and the instruction signal producing circuit.
Specification