Motor drive circuit, fan motor, electronic device, and notebook personal computer
First Claim
Patent Images
1. A motor drive circuit comprising:
- a pulse generation circuit that receives a variable drive voltage and generates a pulse width modulation signal having a first duty ratio, wherein the first duty ratio is increased as the drive voltage is increased; and
a drive control circuit configuredto supply to a motor coil a drive current at a second duty ratio higher than the first duty ratio when a rotation detection signal indicates the motor is starting from a stopped state, andto supply to the motor coil the drive current according to the drive voltage modulated by the pulse width modulation signal when the rotation detection signal indicates the motor has started rotating.
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Abstract
A motor drive circuit includes: a pulse generation circuit configured to generate a pulse signal whose duty ratio of one logic level is increased as a drive voltage is increased in accordance with a target rotation speed of a motor; and a drive control circuit that configured to drive the motor with the drive voltage using a duty ratio higher than the duty ratio of the pulse signal when the motor starts rotating from the stopped state, and configured to drive the motor with the drive voltage during a period when the pulse signal is at the one logic level after the motor starts rotating, based on a rotation signal corresponding to the rotation of the motor.
8 Citations
15 Claims
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1. A motor drive circuit comprising:
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a pulse generation circuit that receives a variable drive voltage and generates a pulse width modulation signal having a first duty ratio, wherein the first duty ratio is increased as the drive voltage is increased; and a drive control circuit configured to supply to a motor coil a drive current at a second duty ratio higher than the first duty ratio when a rotation detection signal indicates the motor is starting from a stopped state, and to supply to the motor coil the drive current according to the drive voltage modulated by the pulse width modulation signal when the rotation detection signal indicates the motor has started rotating. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. A fan motor comprising:
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a fan; a motor configured to drive the fan; and a motor drive circuit configured to drive the motor, the motor drive circuit including; a pulse generation circuit that receives a variable drive voltage and generates a pulse width modulation signal having a first duty ratio, wherein the first duty ratio is increased as the drive voltage is increased; and a drive control circuit configured to supply to a motor coil a drive current at a second duty ratio higher than the first duty ratio when a rotation detection signal indicates the motor is starting from a stopped state, and to supply to the motor coil the drive current according to the drive voltage modulated by the pulse width modulation signal when the rotation detection signal indicates the motor has started rotating.
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9. An electronic device comprising:
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a fan; a motor configured to drive the fan; a motor drive circuit configured to drive the motor; and an apparatus to be cooled by the fan, the motor drive circuit including; a pulse generation circuit that receives a variable drive voltage and generates a pulse width modulation signal having a first duty ratio, wherein the first duty ratio is increased as the drive voltage is increased; and a drive control circuit configured to supply to a motor coil a drive current at a second duty ratio higher than the first duty ratio when a rotation detection signal indicates the motor is starting from a stopped state, and to supply to the motor coil the drive current according to the drive voltage modulated by the pulse width modulation signal when the rotation detection signal indicates the motor has started rotating.
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10. A notebook personal computer comprising:
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a fan; a motor configured to drive the fan; a motor drive circuit configured to drive the motor; and a processor to be cooled by the fan, the motor drive circuit including; a pulse generation circuit that receives a variable drive voltage and generates a pulse width modulation signal having a first duty ratio, wherein the first duty ratio is increased as the drive voltage is increased; and a drive control circuit configured to supply to a motor coil a drive current at a second duty ratio higher than the first duty ratio when a rotation detection signal indicates the motor is starting from a stopped state, and to supply to the motor coil the drive current according to the drive voltage modulated by the pulse width modulation signal when the rotation detection signal indicates the motor has started rotating.
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11. A motor drive circuit that receives a variable drive voltage, comprising:
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a pulse generation circuit to generate a pulse width modulation signal whose duty ratio is increased as the drive voltage is increased; a rotation detection circuit to output a rotation detection signal indicating whether or not the motor has started rotating from a stopped state; a logic circuit to logically sum the pulse width modulation signal and the rotation detection signal to output a drive signal; and a control circuit to drive the motor with the drive voltage modulated by the drive signal, whereby the control circuit drives the motor with the drive voltage at 100% duty ratio when the motor starts rotating from the stopped state, and the control circuit drives the motor with the drive voltage at the duty ratio of the pulse width modulation signal after the motor starts rotating. - View Dependent Claims (12, 13, 14)
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15. A motor drive circuit that receives a variable drive voltage and a rotation detection signal indicating whether or not a motor has started rotating from a stopped state, the motor drive circuit comprising:
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a pulse generation circuit to generate a pulse width modulation signal whose duty ratio is increased as the drive voltage is increased; a logic circuit to logically sum the pulse width modulation signal and the rotation detection signal to output a drive signal; and a control circuit to drive the motor with the drive voltage modulated by the drive signal, wherein the control circuit drives the motor with the drive voltage at 100% duty ratio when the rotation detection signal indicates the motor is starting from a stopped state, and the control circuit drives the motor with the drive voltage at the duty ratio of the pulse width modulation signal when the rotation detection signal indicates the motor has started rotating.
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Specification