Motor control device and motor controlling method

Patent metadata

Field	Value
Publication number	US-10530284-B2
Application number	US-201515538823-A
Country	US
Kind code	B2
Filing date	Dec 25, 2015
Priority date	Dec 26, 2014
Publication date	Jan 7, 2020
Grant date	Jan 7, 2020

Abstract

This motor control device has an inexpensive configuration and enhances motor current target value tracking. This motor control device has an H bridge circuit that has a switching element and is connected to a motor coil provided in a motor, and a control means that drives the switching element at each prescribed PWM period and specifies an operation mode for the H bridge circuit from among a charge mode for increasing the motor current (Icoil) flowing through the motor coil, a fast decay mode for decreasing the motor current, and a slow decay mode. In each PWM period, the control means selects one of the operation modes on the basis of the result of comparing the motor current and a current reference value (Iref) before the time that has passed from the start of the PWM period reaches a prescribed current control re-execution time (Tr) and selects one of the operation modes on the basis of the result of comparing the motor current and the current reference value after the time that has passed reaches the current control re-execution time.

First claim

The invention claimed is:

1. A motor control device comprising:
an H-bridge circuit that includes a switching element for switching an operation mode and is connected to a motor coil provided in a motor, the operation mode including a charge mode, in which a motor current flowing in the motor coil increases, a fast decay mode, in which the motor current is decreased, a slow decay mode, in which the motor current is decreased at a decay speed slower than that of the fast decay mode for the H-bridge circuit, and a shoot through protection mode for preventing the H-bridge circuit from a short circuit; and
a controller that drives the switching element at every predetermined PWM period and designates the operation mode from among a plurality of modes including the charge mode, the fast decay mode, and the slow decay mode,
wherein before an elapsed time from a start of a pulse in each PWM period reaches a predetermined current control re-execution time, which is set to be shorter than each PWM period, the controller switches the H-bridge circuit to start operation in one of the operation modes based on a comparison result between the motor current and a current reference value, wherein the comparison result between the motor current and the current reference value comprises a determination of whether or not the motor current reaches the current reference value,
wherein after the elapsed time reaches the current control re-execution time and before an end of each PWM period, the controller switches the H-bridge circuit to start operation in one of the operation modes based on a comparison result between the motor current and the current reference value, wherein the comparison result between the motor current and the current reference value comprises a determination of whether or not the motor current reaches the current reference value, and
wherein the operation mode is switched to start operation in one of the operation modes based on a comparison result between the motor current and the current reference value when the elapsed time reaches the current control re-execution time, wherein the comparison result between the motor current and the current reference value comprises a determination of whether or not the motor current reaches the current reference value.

2. The motor control device according to claim 1 ,
wherein the controller switches the H-bridge circuit to start operation in the charge mode until a minimum duty time shorter than the current control re-execution time has elapsed from the start of each PWM period.

3. The motor control device according to claim 1 , further comprising:
a current generator that generates a current proportional to a current flowing in the switching element; and
a current detector that measures a value of the current generated in the current generator according to a direction in which the current flows, the value of the current being used as a measured current value of the motor current,
wherein based on the current generated in the current generator and measured by the current detector, the controller: switches the H-bridge circuit to start operation in one of the operation modes based on the comparison result between the motor current and the current reference value before the elapsed time from the start of the pulse in each PWM period reaches the predetermined current control re-execution time; and switches the H-bridge circuit to start operation in one of the operation modes based on the comparison result between the motor current and the current reference value after the elapsed time reaches the current control re-execution time and before the end of each PWM period.

4. The motor control device according to claim 2
wherein, when it is detected that the motor current becomes equal to or higher than the current reference value before the current control re-execution time after the minimum duty time in a period during which the current reference value is rising, the controller switches the H-bridge circuit to start operation in the slow decay mode, and
wherein, when it is detected that the operation mode is the slow decay mode and the motor current becomes less than the current reference value in the current control re-execution time, the controller switches the H-bridge circuit to start operation in the charge mode.

5. The motor control device according to claim 2
wherein, when it is detected that the motor current becomes equal to or higher than the current reference value before the current control re-execution time after the minimum duty time in a period during which the current reference value is decreasing, the controller switches the H-bridge circuit to start operation in the fast decay mode, and
wherein, when it is detected that the motor current becomes less than the current reference value in the current control re-execution time, the controller switches the H-bridge circuit to start operation in the slow decay mode.

6. A motor controlling method for controlling a motor control device including: an H-bridge circuit that includes a switching element for switching an operation mode and is connected to a motor coil provided in a motor, the operation mode including a charge mode, in which a motor current flowing in the motor coil increases, a fast decay mode, in which the motor current is decreased, a slow decay mode, in which the motor current is decreased at a decay speed slower than that of the fast decay mode for the H-bridge circuit, and a shoot through protection mode for preventing the H-bridge circuit from a short circuit; and a controller that drives the switching element at every predetermined PWM period and designates the operation mode from among a plurality of modes including the charge mode, the fast decay mode, and the slow decay mode, the method comprising:
setting a current reference value for each PWM period based on a positional relationship between a rotor and a stator of the motor;
switching the H-bridge circuit to start operation in one of the operation modes based on a comparison result of the motor current and the current reference value before an elapsed time from a start of a pulse in each PWM period reaches a predetermined current control re-execution time, which is set to be shorter than each PWM period; and
switching the H-bridge circuit to start operation in one of the operation modes based on a comparison result of the motor current and the current reference value after the current control re-execution time has elapsed in each PWM period and before an end of each PWM period,
wherein the operation mode is switched to start operation in one of the operation modes based on a comparison result between the motor current and the current reference value when the elapsed time reaches the current control re-execution time.

7. A motor control device comprising:
an H-bridge circuit that includes a switching element and is connected to a motor coil provided in a motor; and
a controller that drives the switching element at every predetermined PWM period and designates an operation mode from among a plurality of modes including a charge mode, in which a motor current flowing in the motor coil increases, a fast decay mode, in which the motor current is decreased, and a slow decay mode, in which the motor current is decreased at a decay speed slower than that of the fast decay mode for the H-bridge circuit,
wherein the controller switches the H-bridge circuit to start operation in one of the operation modes at least twice in each PWM period—once before an elapsed time from a start of a pulse in each PWM period reaches a predetermined current control re-execution time, which is set to be shorter than each PWM period, and again after the elapsed time reaches the current control re-execution time and before an end

Assignees

• Minebea Mitsumi Inc

Inventors

• Hijikata Hidetoshi

Classifications

• H02P8/22 Primary

  Control of step size; Intermediate stepping, e.g. microstepping · CPC title

• H02P2205/01

  Current loop, i.e. comparison of the motor current with a current reference · CPC title

• H02P29/40

  Regulating or controlling the amount of current drawn or delivered by the motor for controlling the mechanical load · CPC title

• H02P7/29

  using pulse modulation · CPC title

• H02P8/18

  Shaping of pulses, e.g. to reduce torque ripple {(Reducing overshoot H02P8/32 takes precedence)} · CPC title