Motor driving circuit, a method for driving a motor, and a semiconductor integrated circuit device

A semiconductor integrated circuit device, comprising in the same semiconductor substrate:

• a semiconductor switching element for supplying a motor with pulse-width modulated power;
• a means for generating a plurality of instruction signals in response to a deviation of a rotational speed signal of the motor from a speed instruction;
• a means for selecting one of the plurality of instruction signals to generate modulated waves, in response to a magnetic-pole position detection signal of the motor;
• and
• a means for controlling the semiconductor switching element by means of pulse width modulation according to the modulated waves.

A motor driving system comprising:

• a motor having a stator with winding and having a permanent magnetic rotor that is placed inside the stator;
• a power converter for supplying the motor with pulse-width modulation controlled driving power;
• a magnetic-pole position detector for detecting a magnetic-pole position of the motor rotor;
• a speed detecting means for detecting a rotational speed of the motor according to an output signal of the magnetic-pole position detector;
• a speed control operation means for outputting a deviation of an output signal of the speed detecting means from a speed instruction;
• a means for generating a plurality of instruction signals in response to an output signal of the speed control operation means;
• a means for generating modulated waves by selecting one of the plurality of instruction signals according to the output signal of the speed control operation means;
• and
• a means for controlling the power converter by means of pulse width modulation according to the modulated waves.

A motor comprising a stator with winding, a permanent magnetic rotor that is placed inside the stator, and an enclosure for accommodating the stator and the rotor, wherein the motor is driven by a driving circuit, said driving circuit comprising:

• a power converter for supplying the motor with pulse-width modulated driving power;
• a means for detecting a magnetic-pole position of the rotor of the motor;
• a means for detecting a rotational speed of the motor from output of the means for detecting magnetic-pole position;
• a means for outputting a deviation of the detected rotational speed of the motor from a speed instruction;
• a means for generating a plurality of instruction signals in response to the deviation;
• a signal selection means that selects one of the plurality of instruction signals according to the magnetic-pole position of the motor, and that outputs a selection signal group;
• a means for generating modulated waves from the selection signal group and a carrier wave signal;
• and
• a means for controlling the power converter by means of pulse width modulation according to the modulated waves;
• wherein said motor driving circuit is built into the enclosure.

A method for driving a brushless motor using a power converter that is controlled by means of pulse width modulation, comprising the steps of:

• generating a deviation of a motor rotational speed, which has been generated from a magnetic-pole position detection signal group of a motor rotor, from a speed instruction;
• generating a plurality of instruction signals according to the deviation;
• selecting one of the plurality of instruction signals to generate modulated waves, according to the magnetic-pole position of the motor rotor;
• and
• controlling the power converter by means of pulse width modulation according to the modulated waves.