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Apparatus and method for controlling brushless DC motor

  • US 7,112,936 B2
  • Filed: 08/08/2003
  • Issued: 09/26/2006
  • Est. Priority Date: 01/08/2003
  • Status: Expired due to Fees
First Claim
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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.

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