Driving circuit for motor and device equipped with driving circuit
View Patent ↗The circuit structured to drive a motor is provided. The circuit includes: a division signal generator that generates a division signal dividing each of a high level period and a low level period of a binary position signal representing a relative position of a magnetic coil to a permanent magnet into a preset number of multiple divisions; a pulse width setter that sets a pulse width for PWM control corresponding to each of the multiple divisions represented by the division signal; and a PWM signal generator that performs PWM control with the set pulse width, thereby generating a PWM signal as a driving signal for driving the motor.
1. A circuit structured to drive a motor, comprising:
a division signal generator that generates a division signal dividing each of a high level period and a low level period of a binary position signal representing a relative position of a magnetic coil to a permanent magnet into a preset number of multiple divisions;
a pulse width setter that sets a pulse width for PWM control corresponding to each of the multiple divisions represented by the division signal;
a PWM signal generator that performs PWM control with the set pulse width, thereby generating a PWM signal as a driving signal for driving the motor; and
a speed signal generator that generates a speed signal representing a relative speed of the permanent magnet to the magnetic coil, based on the position signal,
wherein the pulse width setter sets the pulse width corresponding to each of the multiple divisions based on the speed signal.
2. The circuit according to claim 1 , wherein
the pulse width setter sets the pulse width to a predetermined maximum value in all the multiple divisions when the speed signal does not exceed a preset first threshold value.
3. The circuit according to claim 1 , wherein
the pulse width setter sets the pulse width so as to have a largest value in a specific division corresponding to an approximate center of the high level period or the low level period of the position signal, and to decrease with an increase in temporal distance of the division from the specific division corresponding to the approximate center when the speed signal is in a range from a preset first threshold value to a preset second threshold value which is greater than the first threshold value.
4. The circuit according to claim 1 , wherein
the pulse width setter sets the pulse width so as to make a division having a maximum pulse width appear at an earlier timing than a specific division corresponding to an approximate center of the high level period or the low level period of the position signal when the speed signal exceeds a preset second threshold value.
5. The circuit according to claim 1 , further comprising:
an excitation period setter that sets a preset part of the multiple divisions as a non-excitation period where the PWM signal is disabled as the driving signal and sets a residual part of the multiple divisions as an excitation period where the PWM signal is enabled as the driving signal.
6. The circuit according to claim 5 , wherein
the excitation period setter sets the excitation period and the non-excitation period according to the speed signal.
7. An electric motor, comprising the circuit according to claim 1 .
8. An electric device, comprising the electric motor according to claim 7 .
9. The electric device according to claim 8 , wherein
the electric device is a projector.
10. A fuel cell device, comprising the electric motor according to claim 7 .