Drive control device of motor and a method of start-up

A drive control device of motor in which such a current that a rotor of a three-phase direct-current motor does not react is passed through any two phase coils of the three-phase direct-current motor in succession, a polarity of voltage induced in the non-conducting phase is detected, a phase coil of the three-phase direct-current motor through which a current should be passed to rotate the rotor and the direction of energization are determined, and a current is passed in accordance with the determination to rotate and start up the rotor, the drive control device comprising:

• a first holding circuit that holds a detection value of induced voltage that occurs in the coil in a third phase as non-conducting phase of the three-phase direct-current motor when a current is passed through the coils in a first phase and in a second phase of the three-phase direct-current motor, a second holding circuit that holds a detection value of induced voltage that occurs in the coil in the first phase as non-conducting phase when a current is passed through the coils in the second phase and the third phase, and a third holding circuit that holds a detection value of induced voltage that occurs in the coil in the second phase as non-conducting phase when a current is passed through the coils in the third phase and the first phase,
• the drive control device further comprising:
• an arithmetic circuit that determines a value equivalent to a average value of the values held in the first, second, and third holding circuits therefrom;
• and
• a polarity determination circuit that determines a polarity of induced voltage in each phase of the three-phase direct-current motor with a value determined by the arithmetic circuit taken as a threshold value.

A method of start-up of motor in which such a current that a rotor does not react is passed through any two phase coils in succession, a polarity of voltage induced in the non-conducting phase is detected, a phase coil through which a current should be passed to rotate the rotor and the direction of energization are determined, and a current is passed in accordance with the determination to rotate and start up the motor,

• wherein, when the phase coil through which a current should be passed and the direction of energization are determined based on results of detection of induced voltages in respective phases of the motor, a value equivalent to average value of the detected induced voltages in all phases of the motor is determined, the polarity of induced voltage in each phase of the motor is determined with the value equivalent to the average value taken as a threshold value, a phase coil of the motor through which a current should be passed to rotate the rotor and the direction of energization are determined based on results of determination to carry out energization in accordance with the determination, thereafter, the polarity of the induced voltage is determined with respect to the coil in any one phase, and a phase coil of the motor through which a current should be passed to rotate the rotor and the direction of energization are determined and energization is carried out in accordance with the determination.