Motor control device

Patent metadata

Field	Value
Publication number	US-10560046-B2
Application number	US-201816185856-A
Country	US
Kind code	B2
Filing date	Nov 9, 2018
Priority date	Nov 16, 2017
Publication date	Feb 11, 2020
Grant date	Feb 11, 2020

Abstract

A first PWM count computation unit computes a first PWM count for each of three phases in a first system. A second PWM count computation unit computes a second PWM count for each of three phases in a second system. Upper and lower switching elements for each phase in the first system are controlled in accordance with a first pattern in which the upper and lower switching elements are varied in the order of an upper on state, a lower on state, and the upper on state from the time of start of PWM cycles. Upper and lower switching elements for each phase in the second system are controlled in accordance with a second pattern in which the upper and lower switching elements are varied in the order of a lower on state, an upper on state, and the lower on state from the time of start of PWM cycles.

First claim

What is claimed is:

1. A motor control device that controls an electric motor that has three-phase motor coils in two systems with a phase difference of 60 degrees, 180 degrees, or 300 degrees between the two systems via a first drive circuit that drives three-phase motor coils in a first system, which is one of the two systems, and a second drive circuit that drives three-phase motor coils in a second system, which is the other system, the first drive circuit and the second drive circuit each having sets of upper and lower switching elements for three phases, the motor control device comprising:
a setting unit that sets a two-phase current command value corresponding to a target current value for a current that is to flow through the electric motor;
an actual current value computation unit that computes an actual two-phase current value that matches a current that flows through the electric motor;
a first PWM count computation unit that computes a first PWM count for each of three phases in the first system in each PWM cycle on the basis of the two-phase current command value and the actual two-phase current value; and
a second PWM count computation unit that computes a second PWM count for each of three phases in the second system in each PWM cycle in accordance with the phase difference on the basis of the first PWM count for each of the three phases in the first system, wherein
the upper and lower switching elements for each phase in one of the first system and the second system are controlled in accordance with a first pattern in which the upper and lower switching elements are varied in an order of an upper on state, a lower on state, and the upper on state from a time of start of PWM cycles, and the upper and lower switching elements for each phase in the other system are controlled in accordance with a second pattern in which the upper and lower switching elements are varied in an order of a lower on state, an upper on state, and the lower on state from a time of start of PWM cycles.

2. The motor control device according to claim 1 , wherein:
the phase difference between the three-phase motor coils in the first system and the three-phase motor coils in the second system is 180 degrees;
the actual current value computation unit includes
a three-phase current computation unit that computes a total U-phase current on the basis of a U-phase current that flows through the three-phase motor coils in the first system and a U-phase current that flows through the three-phase motor coils in the second system, a total V-phase current on the basis of a V-phase current that flows through the three-phase motor coils in the first system and a V-phase current that flows through the three-phase motor coils in the second system, and a total W-phase current on the basis of a W-phase current that flows through the three-phase motor coils in the first system and a W-phase current that flows through the three-phase motor coils in the second system, and
a three-phase/two-phase conversion unit that computes the actual two-phase current value by performing a three-phase/two-phase conversion on three-phase currents that include the total U-phase current, the total V-phase current, and the total W-phase current which are computed by the three-phase current computation unit; and

the second PWM count computation unit is configured to compute the first PWM counts for U-phase, V-phase, and W-phase in the first system as the second PWM counts for U-phase, V-phase, and W-phase in the second system.

3. The motor control device according to claim 1 , wherein:
the phase difference between the three-phase motor coils in the first system and the three-phase motor coils in the second system is 300 degrees;
the actual current value computation unit includes
a three-phase current computation unit that computes a total U-phase current on the basis of a U-phase current that flows through the three-phase motor coils in the first system and a V-phase current that flows through the three-phase motor coils in the second system, a total V-phase current on the basis of a V-phase current that flows through the three-phase motor coils in the first system and a W-phase current that flows through the three-phase motor coils in the second system, and a total W-phase current on the basis of a W-phase current that flows through the three-phase motor coils in the first system and a U-phase current that flows through the three-phase motor coils in the second system, and
a three-phase/two-phase conversion unit that computes the actual two-phase current value by performing a three-phase/two-phase conversion on three-phase currents that include the total U-phase current, the total V-phase current, and the total W-phase current which are computed by the three-phase current computation unit; and

the second PWM count computation unit is configured to compute the first PWM counts for U-phase, V-phase, and W-phase in the first system as the second PWM counts for V-phase, W-phase, and U-phase in the second system.

4. The motor control device according to claim 1 , wherein:
the phase difference between the three-phase motor coils in the first system and the three-phase motor coils in the second system is 60 degrees;
the actual current value computation unit includes
a three-phase current computation unit that computes a total U-phase current on the basis of a U-phase current that flows through the three-phase motor coils in the first system and a W-phase current that flows through the three-phase motor coils in the second system, a total V-phase current on the basis of a V-phase current that flows through the three-phase motor coils in the first system and a U-phase current that flows through the three-phase motor coils in the second system, and a total W-phase current on the basis of a W-phase current that flows through the three-phase motor coils in the first system and a V-phase current that flows through the three-phase motor coils in the second system, and
a three-phase/two-phase conversion unit that computes the actual two-phase current value by performing a three-phase/two-phase conversion on three-phase currents that include the total U-phase current, the total V-phase current, and the total W-phase current which are computed by the three-phase current computation unit; and

the second PWM count computation unit is configured to compute the first PWM counts for U-phase, V-phase, and W-phase in the first system as the second PWM counts for W-phase, U-phase, and V-phase in the second system.

5. The motor control device according to claim 1 , wherein:
the first PWM count for each phase in the first system is a PWM count for control for controlling the upper and lower switching elements for the corresponding phase in the first system; and
the second PWM count for each phase in the second system is a PWM count for control for controlling the upper and lower switching elements for the corresponding phase in the second system.

6. The motor control device according to claim 1 , wherein:
the first PWM count for each phase in the first system is a PWM count corresponding to a phase voltage that is a target value for a PWM count corresponding to a level variation timing of a phase voltage for the corresponding phase in the first system;
the second PWM count for each phase in the second system is a PWM count corresponding to a phase voltage that is a target value for a PWM count corresponding to a level variation timing of a phase voltage for the corresponding phase in the second system; and
the motor control device further includes a third PWM count computation unit that computes a PWM count for switching element control for each phase in the first system such that the level variation timing of the phase voltage for each phase in the firs

Assignees

• Jtekt Corp

Inventors

• Sumasu Hiroshi
• Kitamoto Hiroshi

Classifications

• H02P21/00

  Arrangements or methods for the control of electric machines by vector control, e.g. by control of field orientation · CPC title

• H02M1/44

  Circuits or arrangements for compensating for electromagnetic interference in converters or inverters · CPC title

• B62D5/04

  electrical, e.g. using an electric servo-motor connected to, or forming part of, the steering gear · CPC title

• H02P27/08 Primary

  with pulse width modulation · CPC title

• H02P21/22

  Current control, e.g. using a current control loop · CPC title