Driving circuit and driving method for DC motor

Patent metadata

Field	Value
Publication number	US-10879819-B2
Application number	US-201816176412-A
Country	US
Kind code	B2
Filing date	Oct 31, 2018
Priority date	Nov 2, 2017
Publication date	Dec 29, 2020
Grant date	Dec 29, 2020

Abstract

An error detector generates a position error value ERR that corresponds to a difference between a position instruction value P_REF indicative of a target position of a rotor based on a clock signal CLK and a position detection value P_FB indicative of the current position of the rotor based on pulse signals EN_A and EN_B received from an encoder. A feedback controller generates a torque instruction value T_REF such that a position error value ERR approaches zero. The driving IC is capable of switching modes between a rotational driving control mode and a holding mode. Control characteristics set for the feedback controller are switched according to switching between the rotational driving control mode and the holding mode.

First claim

What is claimed is:

1. A driving circuit for a DC motor, comprising:
an error detector coupled to receive a clock signal from a host controller and a pulse signal from an encoder, and structured to generate a position error value that is a difference between a current position of a rotor of the DC motor based on the pulse signal and a target position of the rotor based on the clock signal;
a feedback controller structured as a logic circuit, and structured to generate an instruction value such that the position error value approaches zero; and
a driving signal generating unit structured as a logic circuit, and structured to generate a driving signal that corresponds to the instruction value,
wherein the driving circuit is integrated on a single semiconductor substrate, and
wherein the feedback controller comprises a PI (Proportional Integral) controller.

2. The driving circuit according to claim 1 , wherein control characteristics of the PI controller are dynamically changed according to a frequency of the clock signal.

3. The driving circuit according to claim 2 , wherein an integral gain set for the PI controller is maintained at a constant value, and a proportional gain thereof is changed according to the frequency of the clock signal.

4. The driving circuit according to claim 1 , wherein the error detector comprises:
a position instruction value generating unit structured to generate a target value that corresponds to an integrated value of a number of edges of the clock signal;
a position detection value generating unit structured to generate a feedback value indicative of a current position of the rotor based on the pulse signal; and
a subtractor structured to generate a difference between the target value and the feedback value.

5. The driving circuit according to claim 4 , wherein the position instruction value generating unit is structured to select a change amount of the target value for each edge of the clock signal from among a plurality of values.

6. The driving circuit according to claim 4 , wherein the position instruction value generating unit is structured to select a change amount of the feedback value for each pulse of the pulse signal from among a plurality of values.

7. The driving circuit according to claim 5 , further comprising a setting pin for setting the change amount.

8. The driving circuit according to claim 1 , further comprising a pre-driver structured to control an inverter that drives the DC motor.

9. An electronic device comprising:
a DC motor;
a driver comprising an inverter structured to drive the DC motor; and
the driving circuit according to claim 1 , structured to control the driver.

10. The driving circuit according to claim 1 , integrated on a single semiconductor substrate.

11. A driving circuit structured to drive a DC motor according to a clock signal received from a host controller and a pulse signal indicative of a current position of a rotor of the DC motor received from an encoder, the driving circuit comprising:
an error detector structured to generate a position error value that corresponds to a difference between a position instruction value indicative of a target position of the rotor based on the clock signal and a position detection value indicative of the current position of the rotor based on the pulse signal;
a feedback controller structured to generate a torque instruction value such that the position error value approaches zero; and
a driving signal generating unit structured to generate a driving signal that corresponds to the torque instruction value,
wherein a mode is switchable between a rotational driving control mode and a holding mode,
and wherein at least one from among control characteristics set for the feedback controller and a generating method for the driving signal employed in the driving signal generating unit is switched according to switching between the rotational driving control mode and the holding mode.

12. The driving circuit according to claim 11 , wherein the feedback controller comprises a PI (Proportional Integral) controller,
and wherein at least one from among a proportional gain and an integral gain to be set for the PI controller is switched to a different value according to switching between the rotational driving control mode and the holding mode.

13. The driving circuit according to claim 12 , wherein an integrated value is reset to zero when a mode is switched between the rotational driving control mode and the holding mode.

14. The driving circuit according to claim 11 , further comprising a mode judgment unit structured to judge whether a mode is set to the rotational driving control mode or the holding mode based on an input state of the clock signal.

15. The driving circuit according to claim 14 , wherein the mode judgment unit comprises a counter structured to measure a duration of a non-input state of the clock signal,
and wherein, when the non-input state of the clock signal has continued for a predetermined period of time, the mode judgment unit switches the mode from the rotational driving control mode to the holding mode.

16. The driving circuit according to claim 11 , wherein the feedback controller comprises a first controller that relates to the rotational driving control mode and a second controller that relates to the holding mode.

17. The driving circuit according to claim 11 , wherein the feedback controller comprises a single controller,
and wherein a gain is switched according to switching between the rotational driving control mode and the holding mode.

18. The driving circuit according to claim 11 , wherein, in the rotational driving control mode, the driving signal generating unit determines a rotational direction according to a direction instruction signal received from the host controller,
and wherein, in the holding mode, the driving signal generating unit determines the rotational direction based on a sign of the torque instruction value.

19. The driving circuit according to claim 11 , wherein the driving signal generating unit comprises:
a pulse width modulator structured to generate a PWM (Pulse Width Modulation) signal having a duty ratio that corresponds to the torque instruction value; and
an energization logic structured to generate the driving signal based on the PWM signal and an output of a Hall comparator.

20. The driving circuit according to claim 11 , further comprising a pre-driver structured to control an inverter structured to drive the DC motor.

21. An electronic device comprising:
a DC motor;
a driver comprising an inverter structured to drive the DC motor; and
the driving circuit according to claim 11 , structured to control the driver.

22. A driving method for a DC motor, comprising:
generating a position instruction value indicative of a target position of a rotor of the DC motor, based on a clock signal received from a host controller;
generating a position detection value indicative of a current position of the rotor, based on a pulse signal indicative of a position of the rotor of the DC motor received from an encoder;
selecting a mode from among a rotational driving control mode and a holding mode; and
generating a torque instruction value such that a difference between the position detection value and the position instruction value approaches zero with control characteristics that are switched according to switching between the rotational driving control mode and the holding mode.

Assignees

• Rohm Co Ltd

Inventors

• Hashimoto Hiroki
• Tsuchihashi Masanori

Classifications

• H02P6/06 Primary

  Arrangements for speed regulation of a single motor wherein the motor speed is measured and compared with a given physical value so as to adjust the motor speed · CPC title

• G05B1/00

  Comparing elements, i.e. elements for effecting comparison directly or indirectly between a desired value and existing or anticipated values · CPC title

• H02P6/08

  Arrangements for controlling the speed or torque of a single motor (H02P6/10, H02P6/28 take precedence) · CPC title

• H02P29/10

  for preventing overspeed or under speed · CPC title

• H02P6/153 Primary

  wherein the commutation is advanced from position signals phase in function of the speed · CPC title