Electric motor control device and electric motor control method

Patent metadata

Field	Value
Publication number	US-9425722-B2
Application number	US-201314384264-A
Country	US
Kind code	B2
Filing date	Mar 8, 2013
Priority date	Mar 14, 2012
Publication date	Aug 23, 2016
Grant date	Aug 23, 2016

Abstract

An electric motor control device includes: a motor constant generator configured to generate a motor constant by using a temperature; a current control unit configured to generate a current command value to an electric motor based on the motor constant and a torque command value and execute a current control mode; a voltage phase control unit configured to calculate a torque estimation value of the electric motor and execute a voltage phase control mode in which a feedback operation is performed for a voltage phase based on the difference between the torque estimation value and the torque command value; and a control mode switching unit configured to switch to the voltage phase control mode in a high rotation area where a flux weakening control is performed. The torque estimation value is calculated using the motor constant common to generation of the current command value in the current control mode.

First claim

The invention claimed is:

1. An electric motor control device comprising:
a motor constant generator configured to generate a motor constant by using a temperature as a parameter;
a current control unit that has an electric current generator configured to generate a current command value to an electric motor based on at least a torque command value by referring to a table prepared in advance and that is configured to execute a current control mode in which a voltage applied to the electric motor is controlled to match the current command value;
a torque calculator configured to calculate a torque estimation value of the electric motor based on a torque computation formula using the motor constant;
a voltage phase control unit configured to execute a voltage phase control mode in which a feedback operation is performed for a voltage phase based on a difference between the torque estimation value and the torque command value; and
a control mode switching unit configured to switch to the voltage phase control mode in a high rotation area where a flux weakening control is performed,
wherein the electric current generator is configured to generate the current command value under the same temperature environment as the temperature parameter of the motor constant used when the torque calculator calculates the torque estimation value.

2. The electric motor control device according to claim 1 , wherein the electric current generator generates the current command value to the electric motor based on the motor constant and the torque command value by referring to a table prepared in advance.

3. The electric motor control device according to claim 1 , wherein the motor constant generator generates the motor constant by using, as a parameter, an electric current value of the electric motor in addition to the temperature.

4. The electric motor control device according to claim 1 , wherein the table prepared in advance is a first table storing a relationship between a current command value and a torque of the electric motor at a predetermined temperature,
the electric current generator generates the current command value using the first table in the current control mode,
the motor constant generator has a second table storing a relationship between an electric current value and an inductance value at a predetermined temperature and is configured to generate the motor inductance value as the motor constant, and
the torque calculator estimates a torque of the electric motor using a magnetic flux value prepared in advance at the predetermined temperature and the motor inductance value generated using the second table in the voltage phase control mode.

5. The electric motor control device according to claim 1 , wherein the motor constant is obtained by using, as a parameter, a torque of the electric motor in addition to the temperature.

6. The electric motor control device according to claim 1 , wherein the table prepared in advance is a first table storing a relationship between a current command value and a torque of the electric motor at a predetermined temperature,
the electric current generator generates the current command value using the first table in the current control mode,
the motor constant generator has a second table storing a relationship between a motor inductance value and a torque command value at a predetermined temperature and is configured to generate the motor inductance value as the motor constant, and
the torque calculator estimates a torque of the electric motor using a magnetic flux value obtained in advance at the predetermined temperature and the motor inductance value generated by referring to the second table in the voltage phase control mode.

7. The electric motor control device according to claim 1 , wherein the table prepared in advance is a first table storing a relationship between a current command value and a torque of the electric motor at a predetermined temperature,
the electric current generator generates the current command value using the first table in the current control mode, and
in the voltage phase control mode, the motor constant generator generates a motor inductance value as the motor constant based on a relationship between a torque command value as an input of the first table and an electric current value as an output of the first table, and the torque calculator estimates a torque of the electric motor using the generated motor inductance value and a magnetic flux value obtained in advance at the predetermined temperature.

8. The electric motor control device according to claim 1 , wherein the temperature is a detected or estimated magnet temperature of the electric motor.

9. An electric motor control method comprising:
executing a current control mode in which a current command value to an electric motor is generated based on at least a torque command value by referring to a table prepared in advance, and a voltage applied to the electric motor is controlled to match the current command value;
executing a voltage phase control mode in which a torque estimation value of the electric motor is calculated based on a torque computation formula based on a motor constant obtained by using a temperature as a parameter, and a feedback operation is performed for a voltage phase based on a difference between the torque estimation value and the torque command value; and
switching to the voltage phase control mode in a high rotation area where a flux weakening control is performed,
wherein in generation of the current command value, the current command value under the same temperature environment as a temperature parameter of the motor constant used when the torque estimation value is calculated is generated.

10. An electric motor control device comprising:
a motor constant generation means for generating a motor constant by using a temperature as a parameter;
a current control means, that has an electric current generation means for generating a current command value to an electric motor based on at least a torque command value by referring to a table prepared in advance, for executing a current control mode in which a voltage applied to the electric motor is controlled to match the current command value;
a torque calculation means for calculating a torque estimation value of the electric motor based on a torque computation formula using the motor constant;
a voltage phase control means for executing a voltage phase control mode in which a feedback operation is performed for a voltage phase based on a difference between the torque estimation value and the torque command value; and
a control mode switching means for switching to the voltage phase control mode in a high rotation area where a flux weakening control is performed,
wherein the electric current generation means generates the current command value under the same temperature environment as the temperature parameter of the motor constant used when the torque calculation means calculates the torque estimation value.

Assignees

• Nissan Motor

Inventors

• Shouji Mitsuhiro

Classifications

• H02P21/20

  Estimation of torque · CPC title

• H02P21/0089

  using field weakening · CPC title

• H02P29/662

  the rotor having permanent magnets (H02P29/67 takes precedence) · CPC title

• H02P21/16 Primary

  Estimation of constants, e.g. the rotor time constant · CPC title

• H02P29/0066

  Electricity · mapped topic