Electric machine torque capability determination

Patent metadata

Field	Value
Publication number	US-9929688-B2
Application number	US-201213607008-A
Country	US
Kind code	B2
Filing date	Sep 7, 2012
Priority date	Sep 7, 2012
Publication date	Mar 27, 2018
Grant date	Mar 27, 2018

Abstract

A vehicle comprises an electric machine configured with at least one controller issuing torque commands with the use of a voltage bus. The controller may be configured to respond to a torque requests based on multiple vehicle system inputs including vehicle speed, position of the accelerator pedal and brake pedal, and various other vehicle data. The controller may respond to a torque request that exceeds a threshold value by issuing torque commands for the electric machine based on a speed of the electric machine and a voltage on the bus. Based on the speed of the electric machine and voltage on the bus, the controller may issue a constant torque output by the electric machine as the speed and voltage vary. Calculating a ratio using speed of the electric machine to voltage on the bus to determine torque capability may result as a constant torque when the ratio is constant.

First claim

What is claimed is:

1. A vehicle comprising:
an electric machine;
a bus; and
at least one controller configured to,
in response to torque requests that exceed a torque capability threshold value of the electric machine retrieved from a single independent variable look-up table as a function of a normalized speed, issue torque commands based on the normalized speed of the electric machine by dividing a rotor speed by a voltage on the bus.

2. The vehicle of claim 1 wherein the controller comprises a variable voltage controller programmed to adjust the voltage on the bus.

3. The vehicle of claim 1 wherein the electric machine is a synchronous motor.

4. The vehicle of claim 1 wherein the controller comprises a vehicle system controller, an engine controller, a variable voltage controller and a motor controller.

5. The vehicle of claim 1 wherein a torque of the electric machine is equal to the torque capability threshold value as the rotor speed and voltage vary with a constant ratio of the rotor speed to the voltage.

6. The vehicle of claim 1 wherein a magnitude and phase of a current through windings of the electric machine is constant as the rotor speed and voltage vary with a constant ratio of the rotor speed to the voltage.

7. A vehicle comprising:
an electric machine having windings;
a bus; and
a controller configured to, in response to torque requests that exceed a torque capability threshold value of the electric machine retrieved from a single independent variable look-up table as a function of a rotor speed divided by a voltage on the bus, issue torque commands for the electric machine such that a magnitude and phase of current through the windings remains unaltered as the speed and voltage vary with a constant ratio of the speed to the voltage.

8. The vehicle of claim 7 wherein the controller includes a variable voltage controller.

9. The vehicle of claim 7 wherein the electric machine is a permanent magnet synchronous motor.

10. The vehicle of claim 7 wherein the controller comprises a vehicle system controller, an engine controller, a variable voltage controller and a motor controller.

11. A method comprising:
retrieving from a single independent variable look-up table a maximum torque capability based on a rotor speed divided by a voltage on a bus;
in response to torque requests that exceed the maximum torque capability, issuing torque commands for an electric machine such that an electric machine torque is equal to the maximum torque capability as the speed and voltage vary with a constant ratio of the speed to the voltage.

12. The method of claim 11 wherein a magnitude and phase of current through the windings of the electric machine is constant as the speed and voltage vary with the constant ratio of the speed to the voltage.

Assignees

• Luedtke Daniel
• Ford Global Tech Llc

Inventors

• Luedtke Daniel

Classifications

• B60W10/26

  for electrical energy, e.g. batteries or capacitors · CPC title

• B60W20/00

  Control systems specially adapted for hybrid vehicles {(hybrid vehicle design, B60K6/00; electric vehicles B60L)} · CPC title

• Y02T10/72

  Electric energy management in electromobility · CPC title

• H02P23/14 Primary

  Estimation or adaptation of motor parameters, e.g. rotor time constant, flux, speed, current or voltage · CPC title

• B60W2710/083

  Torque · CPC title