Electric motor temperature compensation

Patent metadata

Field	Value
Publication number	US-9724997-B2
Application number	US-201213607013-A
Country	US
Kind code	B2
Filing date	Sep 7, 2012
Priority date	Sep 7, 2012
Publication date	Aug 8, 2017
Grant date	Aug 8, 2017

Abstract

A vehicle includes one or more inverter-fed electric machines such as permanent magnet synchronous motors. In response to a torque request, a controller issues commands to an inverter calculated to cause the motor to produce the requested torque at the current temperature. A method adjusts the direct component of the winding current such that the requested torque is delivered efficiently. For a given rotor speed, bus voltage, and torque, the direct component increases as the temperature increases.

First claim

What is claimed is:

1. A vehicle comprising:
a bus;
an electric machine having a temperature;
an inverter configured to supply the electric machine a winding current having a direct component (Id) and a quadrature component (Iq); and
a controller configured to issue pulse width modulation commands to the inverter to adjust the winding current such that for a given speed and torque of the electric machine and voltage of the bus, the direct component increases as the temperature increases.

2. The vehicle of claim 1 wherein the controller is further configured to operate the inverter in a six-step mode wherein the winding current is adjusted by adjusting a voltage angle such that for a given speed and torque of the electric machine and voltage of the bus, the voltage angle varies as the temperature varies.

3. The vehicle of claim 1 wherein the direct component of the winding current is less than zero at the given speed, torque, and voltage.

4. The vehicle of claim 1 wherein the given speed is greater than zero.

5. A controller comprising:
an input interface configured to receive signals indicating a voltage of an electrical bus and a temperature and a rotor speed of an electric machine;
an output interface configured to send pulse width modulation commands to an inverter such that the inverter supplies the electric machine with a winding current having a direct component (Id) and a quadrature component (Iq), the winding current causing the electric machine to produce a torque; and
control logic programmed to adjust the pulse width modulation commands such that for a given rotor speed, bus voltage, and torque, the direct component increases as the temperature increases.

6. The controller of claim 5 wherein the direct component of the winding current is less than zero at the given rotor speed, bus voltage, and torque.

7. The controller of claim 5 wherein the given rotor speed is greater than zero.

8. A method of operating an electric machine having a temperature, the method comprising:
receiving a torque request;
adjusting the torque request based on the temperature;
calculating a direct component (Id) and a quadrature component (Iq) of a target winding current based on the adjusted torque request;
adjusting the calculated direct component based on the temperature; and
issuing commands to an inverter to supply a winding current generally equal to the adjusted target winding current.

9. The method of claim 8 wherein the calculated direct component of the winding current is not adjusted based on temperature when the torque request is less than a threshold.

10. The method of claim 9 wherein the threshold is based on a rotor speed of the electric machine.

11. The method of claim 10 wherein the threshold is also based on a bus voltage of the inverter.

12. The method of claim 8 wherein the direct component and quadrature component are based on a rotor speed of the electric machine.

13. The method of claim 12 wherein the direct component and quadrature component are also based on a bus voltage of the inverter.

Assignees

• Luedtke Daniel
• Ford Global Tech Llc

Inventors

• Luedtke Daniel

Classifications

• Y02T10/72

  Electric energy management in electromobility · CPC title

• Y02T10/70

  Energy storage systems for electromobility, e.g. batteries · CPC title

• B60L2240/425

  Temperature · CPC title

• H02P29/68

  based on the temperature of a drive component or a semiconductor component · CPC title

• Y02T10/7077

  Cross-Sectional Technologies · mapped topic