Brushless motor drive circuit including a linear amplifier for sending and output signal based upon the detected back electromotive force voltage
First Claim
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1. A motor drive circuit for driving a motor, comprising:
- an output amplifier for feeding a drive current for a winding of said motor;
an amplifier for detecting a sinusoidal back electromotive force voltage induced on the winding of said motor;
a phase compensation circuit for implementing a phase compensation for the detected back electromotive force voltage;
a matrix circuit for producing a digital pulse signal; and
a switching circuit having a first input terminal for receiving the phase compensated back electromotive force voltage as an output signal of said phase compensation circuit, a second input terminal for receiving the digital pulse signal as an output signal of said matrix circuit and an output terminal connected to an input terminal of said output amplifier, and operating to deliver one of the output signal of said phase compensation circuit and the output signal of said matrix circuit selectively to the input terminal of said output amplifier in response to a switching signal.
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Abstract
In a d.c. brushless motor drive circuit, the output amplifier produces a motor winding drive current with dulled rise/fall edges from a detected sinusoidal back e.m.f. voltage induced on the winding during the steady-state operation when the motor runs at the rated speed. The output amplifier includes a set of transistors each brought to a saturated conductive state or a cutoff state in accordance with the phase conduction sequence to connect one end of each motor winding to a ground voltage source, and another transistor operated continuously to connect the neutral point, which is opposite ends of the motor windings connected together, to a power voltage source.
27 Citations
32 Claims
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1. A motor drive circuit for driving a motor, comprising:
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an output amplifier for feeding a drive current for a winding of said motor; an amplifier for detecting a sinusoidal back electromotive force voltage induced on the winding of said motor; a phase compensation circuit for implementing a phase compensation for the detected back electromotive force voltage; a matrix circuit for producing a digital pulse signal; and a switching circuit having a first input terminal for receiving the phase compensated back electromotive force voltage as an output signal of said phase compensation circuit, a second input terminal for receiving the digital pulse signal as an output signal of said matrix circuit and an output terminal connected to an input terminal of said output amplifier, and operating to deliver one of the output signal of said phase compensation circuit and the output signal of said matrix circuit selectively to the input terminal of said output amplifier in response to a switching signal. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. A method of driving a Hall-sensorless motor comprising:
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a first step of driving windings of said motor in synchronism with a clock signal at a starting of said motor; a second step of detecting zero-cross points of back electromotive force voltages induced on the windings of said motor with respect to a voltage of a neutral point defining a common connection point of said windings and driving the windings of said motor based on the detected zero-cross points during a period after said motor has started until a motor speed reaches a rated speed; and a third step of driving the windings of said motor based on phase information and amplitude information of the back electromotive force voltages after said motor speed reaches the rated speed. - View Dependent Claims (11)
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12. A motor drive circuit on a semiconductor substrate, for use with a motor including first, second and third coils, having first and second ends, wherein the first ends are commonly connected to form a neutral point, the motor drive circuit comprising:
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first, second and third external terminals to be coupled to the second ends of the first, second and third coils, respectively; a fourth external terminal to be coupled to the neutral point; first, second and third output amplifiers having outputs coupled to the first, second and third external terminals, respectively; first, second and third detection amplifiers detecting back electromotive force voltages to be induced on the first, second and third coils, and each having a first input, a second input and an output, the first inputs thereof being coupled to the fourth external terminal, and the second inputs thereof being coupled to the first, second and third external terminals, respectively; first, second and third phase compensation circuits having inputs coupled to the outputs of the first, second and third detection amplifiers, respectively, and implementing phase compensations for the detected back electromotive force voltage; a matrix circuit responsive to input signals and producing digital pulse signals; and a switching circuit including first, second and third switching elements having first inputs coupled to the outputs of the first, second and third compensation circuits, respectively, to receive the phase compensated back electromotive force voltages from the first, second and third compensation circuits, second inputs coupled to receive the digital pulse signals from the matrix circuit, respectively, and outputs coupled to the inputs of the first, second and third output amplifiers, respectively, wherein the switching circuit is responsive to a switching signal and outputs one of the phase compensated back electromotive force voltages and the digital pulse signals to the inputs of the first, second and third output amplifiers, respectively. - View Dependent Claims (13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23)
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24. A motor drive system comprising:
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a motor having first, second and third coils each having a first end and a second end, wherein the second end of each of the first, second and third coils is commonly connected to form a neutral point; a motor drive circuit, on a semiconductor substrate, having first, second, third and fourth external terminals coupled to the first end of each of the first, second and third coils and the neutral point, respectively, and fifth and sixth external terminals; and a microcomputer, coupled to the fifth and sixth external terminals, controlling operations of the motor drive circuit; wherein the motor drive circuit further comprises; first, second and third output amplifiers having outputs coupled to the first, second and third external terminals, respectively; first, second and third detection amplifiers detecting back electromotive force voltages induced on the first, second and third coils, and each having a first input, a second input and an output, the first inputs thereof being coupled to the fourth external terminal, and the second inputs thereof being coupled to the first, second and third external terminals, respectively; first, second and third phase compensation circuits having inputs coupled to the outputs of the first, second and third detection amplifiers, respectively, and implementing phase compensations for the detected back electromotive force voltage; a matrix circuit responsive to input signals and producing digital pulse signals; a switching circuit including first, second and third switching elements having first inputs coupled to the outputs of the first, second and third compensation circuits, respectively, to receive the phase compensated back electromotive force voltages from the first, second and third compensation circuits, second inputs coupled to receive the digital pulse signals from the matrix circuit, respectively, and outputs coupled to the inputs of the first, second and third output amplifiers, respectively, wherein the switching circuit is responsive to a switching signal and outputs one of the phase compensated back electromotive force voltages and the digital pulse signals to the inputs of the first, second and third output amplifiers, respectively; a zero-cross detection circuit, coupled to the first, second, third and fourth external terminals, detecting zero-cross points of the back electromotive force voltages with respect to a voltage on the fourth external terminal and providing an output signal representing the detected zero-cross points to the fifth external terminal so that the microcomputer uses the output signal of the zero-cross detection circuit as a rotation speed signal of the motor; and a circuit, coupled to the sixth external terminal, responsive to a speed control signal from the microcomputer responding to the output signal and providing the switching signal to the switching circuit in accordance with the speed control signal so that the switching circuit provides the digital pulse signals to the inputs of the first, second and third output amplifiers, respectively, during the period after said motor has started until a rotation speed of the motor (M) reaches a predetermined speed and provides the phase compensated back electromotive force voltages to the inputs of the first, second and third output amplifiers, respectively, after the rotation speed of the motor reaches the predetermined speed. - View Dependent Claims (25, 26, 27, 28, 29, 30, 31, 32)
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Specification