Electric motor control device, electric motor system and electric motor control method

Patent metadata

Field	Value
Publication number	US-10447189-B2
Application number	US-201715667766-A
Country	US
Kind code	B2
Filing date	Aug 3, 2017
Priority date	Sep 6, 2016
Publication date	Oct 15, 2019
Grant date	Oct 15, 2019

Abstract

An electric motor control device includes a drive waveform generating unit configured to generate a drive waveform (a sine wave or a pseudo-trapezoidal wave) to an electric motor. A plurality of photo interrupters detect a rotational phase of an electric motor, and a information of rotational speed is detected by an encoder circuit based on a detected signal of the rotational phase of the electric motor. The control unit controls the drive waveform generating unit on the basis of detection information of the rotational phase of the electric motor and performs control so that a phase relationship between the rotational phase of the electric motor and the phase of the drive waveform is kept constant. Furthermore, the control unit sets an amplitude value of the drive waveform generated by the drive waveform generating unit in accordance with a difference between a target speed and the detected information of rotational speed and performs speed control so that a speed of the electric motor is kept constant. The control unit calculates an amplitude setting value with which correction for suppressing non-linearity is performed in a region in which an amplitude setting value of the drive waveform and actual work given to the electric motor is non-linear and controls the speed.

First claim

What is claimed is:

1. An electric motor control device comprising:
at least one processor or circuit programmed to function as:
a generating unit configured to generate a drive waveform to an electric motor;
a position detecting unit configured to detect a rotational phase of the electric motor and to output a detected signal;
a speed detecting unit configured to detect information of a rotational speed of the electric motor based on the detected signal output by the position detecting unit; and
a control unit configured to control a phase relationship between the rotational phase of the electric motor and a phase of the drive waveform and set an amplitude of the drive waveform corresponding to a difference between a target speed and the information of rotational speed detected by the speed detecting unit to control a speed of the electric motor,
wherein characteristics of the amplitude of the drive waveform corresponding to an output of the electric motor have a first region in which a relationship between an integrated value obtained by integrating an output voltage of the electric motor and a setting value of the amplitude is linear and a second region in which the relationship between the integrated value and the setting value of the amplitude is non-linear,
wherein the control unit holds data indicating the characteristics and performs correction on the setting value of the amplitude based on the data in the second region to suppress non-linearity of the setting value of the amplitude of the drive waveform and the output of the electric motor.

2. The electric motor control device according to claim 1 , wherein the generating unit generates a drive waveform of a sine wave or a pseudo-trapezoidal wave in accordance with a frequency and the amplitude set by the control unit.

3. The electric motor control device according to claim 2 , wherein the control unit performs the correction when the drive waveform of the pseudo-trapezoidal wave is generated by the generating unit.

4. The electric motor control device according to claim 3 , wherein the generating unit outputs the drive waveform of the sine wave when the setting value of the amplitude is less than or equal to a threshold value, and outputs the drive waveform of the pseudo-trapezoidal wave when the setting value of the amplitude is greater than the threshold value.

5. The electric motor control device according to claim 1 , wherein the control unit performs correction for suppressing non-linearity of a relationship between the setting value of the amplitude and rotational torque of the electric motor.

6. The electric motor control device according to claim 5 , wherein the control unit identifies a relationship between the setting value of the amplitude and the rotational torque of the electric motor based on an advance angle state of the electric motor corresponding to a phase difference between the rotational phase detected by the position detecting unit and the phase of the drive waveform, determines correction characteristics corresponding to the advance angle state of the electric motor using the advance angle state when maximum rotational torque is generated as a reference, and sets the amplitude based on the correction characteristics.

7. The electric motor control device according to claim 6 , wherein each of the correction characteristics indicates a setting value of an amplitude corresponding to the rotational torque of the electric motor, and the control unit determines characteristics in the advance angle state when the maximum rotational torque is generated and the correction characteristics from an advance angle value indicating the advance angle state of the electric motor.

8. The electric motor control device according to claim 1 , wherein the control unit identifies a phase delay between a drive voltage waveform generated by the generating unit and a current waveform generated in an armature of the electric motor and sets the amplitude to correct the phase delay.

9. The electric motor control device according to claim 2 , further comprising:
a memory configured to store individual difference information of speed characteristics of the electric motor,
wherein the control unit sets an amplitude in a region in which a relationship between the setting value of the amplitude and an integrated value obtained by integrating an output of the drive waveform is linear when it is determined that the target speed can be accomplished using a drive waveform of a sine wave from the individual difference information acquired from the storage unit and the target speed.

10. The electric motor control device according to claim 1 , wherein the control unit controls the generating unit in accordance with the detected signal using the position detection unit to control the phase relationship between the rotational phase of the electric motor and the phase of the drive waveform.

11. An electric motor system comprising an electric motor control device and an electric motor, the electric motor control device comprising:
at least one processor or circuit programmed to function as:
a generating unit configured to generate a drive waveform to an electric motor;
a position detecting unit configured to detect a rotational phase of the electric motor and to output a detected signal;
a speed detecting unit configured to detect information of a rotational speed of the electric motor based on the detected signal output by the position detecting unit; and
a control unit configured to control a phase relationship between the rotational phase of the electric motor and a phase of the drive waveform and set an amplitude of the drive waveform corresponding to a difference between a target speed and the information of rotational speed detected by the speed detecting unit to control a speed of the electric motor,
wherein characteristics of the amplitude of the drive waveform corresponding to an output of the electric motor have a first region in which a relationship between an integrated value obtained by integrating an output voltage of the electric motor and a setting value of the amplitude is linear and a second region in which the relationship between the integrated value and the setting value of the amplitude is non-linear,
wherein the control unit holds data indicating the characteristics and performs correction on the setting value of the amplitude based on the data in the second region to suppress non-linearity of the setting value of the amplitude of the drive waveform and the output of the electric motor.

12. An electric motor control method which controls an electric motor, the electric motor control method comprising:
generating a drive waveform to an electric motor;
detecting a rotational phase of the electric motor and outputting a detected signal;
detecting an information of rotational speed of the electric motor based on the detected signal detected in the detecting;
controlling a phase relationship between the rotational phase of the electric motor and a phase of the drive waveform and setting an amplitude of a drive waveform corresponding to a difference between a target speed and the information of rotational speed detected by the speed detection step to control a speed,
wherein characteristics of the amplitude of the drive waveform corresponding to an output of the electric motor have a first region in which a relationship between an integrated value obtained by integrating an output voltage of the electric motor and a setting value of the amplitude is linear and a second region in which the relationship between the integrated value and the setting value of the amplitude is non-linear, and
wherein, in the contr

Assignees

• Canon Kk

Inventors

• Mizuo Yoshihiro

Classifications

• H02P7/02

  the DC motors being of the linear type · CPC title

• H02P2209/11

  Sinusoidal waveform · CPC title

• H02P23/18

  Controlling the angular speed together with angular position or phase · CPC title

• H02P7/305 Primary

  whereby the speed is regulated by measuring the motor speed and comparing it with a given physical value · CPC title

• H02P6/08

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