Apparatus and method for controlling brushless DC motor
First Claim
1. An apparatus for controlling a brushless direct current (DC) motor having a rotator, comprising:
- a power converting unit to convert alternating current (AC) power to polyphase AC power and supply the polyphase AC power to the brushless DC motor;
a rotator position/speed detecting unit to detect status information of the rotator of the brushless DC motor;
a terminal voltage detecting unit to detect variations of terminal voltages of the polyphase AC power supplied to the brushless DC motor; and
a control unit to detect phase commutation periods of the polyphase AC power using the status information of the rotator provided from the rotator position/speed detecting unit and terminal voltage variation information of the polyphase AC power provided from the terminal voltage detecting unit, and to control the power converting unit to supply to the brushless DC motor a compensation voltage used to constantly maintain a mean voltage of a non-commutation phase of the polyphase AC power during the detected phase commutation periods, wherein the control unit comprises;
a speed control unit to generate a first current control signal providing a non-commutation phase current during non-commutation periods of the polyphase AC power based on a speed command inputted from an outside and current speed information provided from the rotator position/speed detecting unit;
a commutation period detecting unit to detect the phase commutation periods using the terminal voltage information provided from the terminal voltage detecting unit, and to generate a commutation period detection signal;
a control signal converting unit to input the first current control signal, to generate a second current control signal, and output one of the first and second current control signals as a third current control signal in response to the commutation period detection signal generated by the phase commutation detecting unit; and
an inverter control unit to generate one or more inverter control signals each having a time ratio determined in response to the third current control signal outputted from the control signal converting unit.
1 Assignment
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Accused Products
Abstract
An apparatus and method for controlling a brushless DC motor, which minimizes a torque ripple thereof, and includes a power converting unit to convert alternating current (AC) power to polyphase AC power and to supply the polyphase AC power to the brushless DC motor. A rotator position/speed detecting unit detects status information of a rotator. A terminal voltage detecting unit detects variations of terminal voltages of the polyphase AC power. A control unit detects phase commutation periods of the polyphase AC power using the status information provided from the rotator position/speed detecting unit and the terminal voltage variation information of the polyphase AC power provided from the terminal voltage detecting unit. The control unit controls the power converting unit to supply a compensation voltage used to constantly maintain a mean voltage of a non-commutation phase of the polyphase AC power during the detected phase commutation periods.
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Citations
44 Claims
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1. An apparatus for controlling a brushless direct current (DC) motor having a rotator, comprising:
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a power converting unit to convert alternating current (AC) power to polyphase AC power and supply the polyphase AC power to the brushless DC motor; a rotator position/speed detecting unit to detect status information of the rotator of the brushless DC motor; a terminal voltage detecting unit to detect variations of terminal voltages of the polyphase AC power supplied to the brushless DC motor; and a control unit to detect phase commutation periods of the polyphase AC power using the status information of the rotator provided from the rotator position/speed detecting unit and terminal voltage variation information of the polyphase AC power provided from the terminal voltage detecting unit, and to control the power converting unit to supply to the brushless DC motor a compensation voltage used to constantly maintain a mean voltage of a non-commutation phase of the polyphase AC power during the detected phase commutation periods, wherein the control unit comprises; a speed control unit to generate a first current control signal providing a non-commutation phase current during non-commutation periods of the polyphase AC power based on a speed command inputted from an outside and current speed information provided from the rotator position/speed detecting unit; a commutation period detecting unit to detect the phase commutation periods using the terminal voltage information provided from the terminal voltage detecting unit, and to generate a commutation period detection signal; a control signal converting unit to input the first current control signal, to generate a second current control signal, and output one of the first and second current control signals as a third current control signal in response to the commutation period detection signal generated by the phase commutation detecting unit; and an inverter control unit to generate one or more inverter control signals each having a time ratio determined in response to the third current control signal outputted from the control signal converting unit. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. A method of controlling a rotation of a brushless DC motor, the brushless DC motor being supplied with power from a power converting unit to convert AC power to polyphase AC power, comprising:
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driving the brushless DC motor by supplying the polyphase AC power thereto; monitoring a starting time of a phase commutation using position information of a rotator; supplying a compensation voltage to the brushless DC motor to constantly maintain a mean voltage of a non-commutation phase of the polyphase AC power to minimize a torque ripple due to the phase commutation when the phase commutation starts; and detecting an ending time of the phase commutation using information on a time when a trigger of a terminal voltage waveform is generated to stop the supply of the compensation voltage. - View Dependent Claims (9, 11)
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10. A method of controlling a rotation of a brushless DC motor, the brushless DC motor being supplied with power from a power converting unit to convert AC power to polyphase AC power, comprising:
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driving the brushless DC motor by supplying a non-commutation phase current thereto; monitoring a starting time of a phase commutation using position information of a rotator; supplying a compensation voltage to the brushless DC motor to minimize a torque ripple due to the phase commutation when the phase commutation starts; and detecting an ending time of the phase commutation using information on a time when a trigger of a terminal voltage waveform is generated to stop the supply of the compensation voltage, wherein the detecting of the phase commutation ending time comprises; comparing each of phase voltages of the polyphase AC power with a reference voltage; and generating terminal voltage information, corresponding to each of the terminal voltages, and, respectively, having a first logic level when a respective terminal voltage of the polyphase AC power is greater than the reference voltage, and having a second logic level when the respective terminal voltage of the polyphase AC power is less than the reference voltage, and wherein; the reference voltage is ½
of a DC-link voltage across a DC-link capacitor; andthe first logic level is greater than ½
of the DC-link voltage, and the second logic level is less than ½
of the DC-link voltage.
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12. An apparatus for controlling a brushless direct current (DC) motor having a rotator, comprising:
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a converting unit to convert alternating current (AC) power to polyphase AC power and to supply the polyphase AC power to the brushless DC motor; a rotator operation detecting unit to detect operational information of the rotator; a variation detecting unit to detect variation information of terminal voltages of the polyphase AC power supplied to the brushless DC motor; and a control unit to detect phase commutation periods of the polyphase AC power using the operational information of the rotator and the variation information of the polyphase AC power supplied to the brushless DC motor and to control a supply of a compensation voltage to the brushless DC motor to maintain a mean voltage of a non-commutation phase of the polyphase AC cower during the detected phase commutation periods, wherein the control unit comprises; a speed control unit to generate a first control signal to provide a non-commutation phase current during non-commutation periods of the polyphase AC power based on a speed command inputted from an external source and current speed information provided from the rotator operation detecting unit; a commutation period detecting unit to detect the phase commutation periods using the variation information of terminal voltages provided from the variation detecting unit and to generate a commutation period detection signal; a control signal converting unit to input the first control signal, to generate a second control signal, and to output one of the first and second control signals in response to the commutation period detection signal generated by the phase commutation detecting unit; and an inverter control unit to generate one or more inverter control signals each having a time ratio determined in response to the output from the control signal converting unit.
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13. An apparatus for controlling a brushless direct current (DC) motor having a rotator, comprising:
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a converting unit to convert alternating current (AC) power to polyphase AC power and to supply the polyphase AC power to the brushless DC motor; a rotator operation detecting unit to detect operational information of the rotator; a variation detecting unit to detect variation information of terminal voltages of the polyphase AC power supplied to the brushless DC motor; and a control unit to detect chase commutation periods of the polyphase AC power using the operational information of the rotator and the variation information of the polyphase AC power supplied to the brushless DC motor and to control a supply of a compensation voltage to the brushless DC motor to maintain a mean voltage of a non-commutation phase of the polyphase AC power during the detected phase commutation periods, wherein the compensation voltage is provided only during the phase commutation periods to prevent an undercompensation or an overcompensation of phase currents, and wherein the compensation voltage compensates for a reduction in the phase currents occurring during the phase commutation periods to minimize a torque ripple of the brushless DC motor. - View Dependent Claims (14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 38)
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27. An apparatus for controlling a brushless direct current (DC) motor having a rotator, comprising:
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a converting unit to convert alternating current (AC) power to polyphase AC power and to supply the polyphase AC power to the brushless DC motor; a rotator operation detecting unit to detect operational information of the rotator; a variation detecting unit to detect variation information of terminal voltages of the polyphase AC power supplied to the brushless DC motor; and a control unit to detect phase commutation periods of the polyphase AC power using the operational information of the rotator and the variation information of the polyphase AC power supplied to the brushless DC motor and to control a supply of a compensation voltage to the brush less DC motor to maintain a mean voltage of a non-commutation phase of the polyphase AC power during the detected phase commutation periods, wherein the rotator operation detecting unit detects position information and speed information of the rotator, as the operational information, by using one of a position sensor and phase commutation information of each of the terminal voltages supplied to the brushless DC motor, and wherein the control unit comprises; a speed control unit generating a first current control signal to allow a rotation speed of the rotator of the brushless DC motor to comply with a speed command provided from an external source in accordance with a difference between the speed command provided from the external source and the speed information provided from the rotator operation detecting unit; and a control signal converting unit converting the first current control signal outputted from the speed control unit to generate a second current control signal and selecting one of the first current control signal and the generated second current control signal, and outputting the selected one as a third current control signal. - View Dependent Claims (28, 29, 30, 31, 32, 33, 34, 37)
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35. An apparatus for controlling a brushless direct current (DC) motor having a rotator, comprising:
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a converting unit to convert alternating current (AC) power to polyphase AC power and to supply the polyphase AC power to the brushless DC motor; a rotator operation detecting unit to detect operational information of the rotator; a variation detecting unit to detect variation information of terminal voltages of the polyphase AC power supplied to the brushless DC motor; and a control unit to detect phase commutation periods of the polyphase AC power using the operational information of the rotator and the variation information of the polyphase AC power supplied to the brushless DC motor and to control a supply of a compensation voltage to the brushless DC motor to maintain a mean voltage of a non-commutation chase of the polyphase AC power during the detected phase commutation periods, wherein the control unit generates inverter control signals outputted to an inverter to control a rotation speed of the brushless DC motor according to the variation information of the polyphase AC power, provided from the variation detecting unit, and the rotator operation information, provided from the rotator operation detecting unit, and wherein a torque ripple due to a phase commutation is reduced by adjusting a time ratio of each of the inverter control signals provided to an inverter during the phase commutation period.
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36. An apparatus for controlling a brushless direct current (DC) motor having a rotator, comprising:
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a converting unit to convert alternating current (AC) power to polyphase AC power and to supply the polyphase AC power to the brushless DC motor; a rotator operation detecting unit to detect operational information of the rotator; a variation detecting unit to detect variation information of terminal voltages of the polyphase AC power supplied to the brushless DC motor; and a control unit to detect phase commutation periods of the polyphase AC power using the operational information of the rotator and the variation information of the polyphase AC power supplied to the brushless DC motor and to control a supply of a compensation voltage to the brush less DC motor to maintain a mean voltage of a non-commutation phase of the polyphase AC power during the detected phase commutation periods, wherein the control unit generates inverter control signals outputted to an inverter to control a rotation speed of the brushless DC motor according to the variation information of the polyphase AC power, provided from the variation detecting unit, and the rotator operation information, provided from the rotator operation detecting unit, and wherein the time ratio of each of the inverter control signals is adjusted simultaneously with the phase commutation.
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39. A method of controlling a brushless DC motor, which is supplied with polyphase AC power, the brushless DC motor having a rotator therein, comprising:
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supplying the polyphase AC power to the brushless DC motor; detecting a starting time of a phase commutation using operational information of the rotator and an ending time of the phase commutation using information on a time when a trigger of a terminal voltage waveform is generated to stop the supply of the compensation voltage, a phase commutation period being defined by the starting and ending times of the phase commutation; and supplying a compensation voltage to the brushless DC motor to substantially eliminate a torque ripple thereof during the phase commutation period, wherein the torque ripple is substantially eliminated by using the compensation voltage to constantly maintain a mean voltage of a non-commutation phase of the polyphase AC power. - View Dependent Claims (40, 41, 42, 43)
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44. An apparatus for controlling a brushless direct current (DC) motor having a rotator, comprising:
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a converting unit to convert alternating current (AC) power to polyphase AC power and to supply the polyphase AC power to the brushless DC motor; a rotator operation detecting unit to detect operational information of the rotator; a terminal voltage detecting unit to detect variations of terminal voltages of the polyphase AC power supplied to the brushless DC motor; a variation detecting unit to detect variation information of terminal voltages of the polyphase AC power supplied to the brushless DC motor; and a control unit to detect phase commutation periods of the polyphase AC power using the operational information of the rotator and the variation information of the polyphase AC power supplied to the brushless DC motor and to control a supply of a compensation voltage to the brushless DC motor to substantially eliminate a torque ripple thereof, wherein the control unit comprises; a speed control unit to generate a first current control signal providing a non-commutation phase current during non-commutation periods of the polyphase AC power based on a speed command inputted from an outside and current speed information provided from the rotator operation detecting unit; a commutation period detecting unit to detect the phase commutation periods using the terminal voltage information provided from the terminal voltage detecting unit, and to generate a commutation period detection signal; a control signal converting unit to input the first current control signal, to generate a second current control signal, and output one of the first and second current control signals as a third current control signal in response to the commutation period detection signal generated by the phase commutation detecting unit; and an inverter control unit to generate one or more inverter control signals each having a time ratio determined in response to the third current control signal outputted from the control signal converting unit.
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Specification