Active deadtime control for improved torque ripple performance in electric machines

• US 6,914,399 B2
• Filed: 10/14/2002
• Issued: 07/05/2005
• Est. Priority Date: 07/09/2002
• Status: Expired due to Term

• Current Assignee: GM Global Technology Operations Incorporated (General Motors Company), Steering Solutions IP Holding Corporation (Nexteer Automotive Group Ltd.)
• Original Assignee: Delphi Technologies, Inc. (BorgWarner Incorporated)
• Inventors: Kushion, Mark D., Skellenger, Dennis B.
• Primary Examiner(s): Leykin, Rita
• Application Number:
  US10/269,740
• Publication Number:
  US 20040007999A1
• Time in Patent Office: 995 Days
• Field of Search: 318/434, 318/254, 318/437, 318/713, 318/801, 318/810, 318/715
• US Class Current: 318/434
• CPC Class Codes: B62D 5/0463 calculating assisting torque from the motor based on driver input
• CPC Class Codes: H02P 6/10 Arrangements for controlling torque ripple, e.g. providing reduced torque ripple

Abstract

A method for implementing active deadtime control of an inverter associated with an electric motor is disclosed. In an exemplary embodiment, the method includes receiving a command voltage signal indicative of a desired load to be driven by the motor. Based upon the value of the command voltage signal, a determined value of deadtime is applied to switching circuitry in the inverter, wherein the value of deadtime relates to an amount of time in which the switching of a device in the switching circuitry is delayed so as to prevent a short circuit condition within the inverter.

Claims

1. A method for implementing active deadtime control of an inverter associated with an electric motor, the method comprising:

receiving a command voltage signal indicative of a desired load to be driven by the motor;

determining, based upon the value of said command voltage signal, a value of deadtime to be applied to switching circuitry in the inverter;

adjusting the value of said command voltage signal in response to said value of deadtime, thereby producing a compensated command voltage signal to be applied to the motor through the switching circuitry in the inverter; and

wherein said value of deadtime relates to an amount of time in which the switching of a device in the switching circuitry is delayed so as to prevent a short circuit condition within the inverter.

2. The method of claim 1, wherein said value of deadtime decreases as the value of said command voltage signal decreases.

3. The method of claim 1, wherein said value of deadtime is obtained through a lookup table.

4. A method for controlling an inverter associated with a brushless electric motor, the method comprising:

generating a command voltage signal indicative of a desired load to be driven by the motor, said command voltage signal based upon an input torque command signal and a motor speed signal;

determining, based upon the value of said command voltage signal, a value of deadtime to be applied to switching circuitry included within the inverter;

adjusting the value of said command voltage signal in response to said value of deadtime, thereby producing a compensated command voltage signal to be applied to the motor through the switching circuitry in the inverter; and

wherein said value of deadtime relates to an amount of time in which the switching of a device in the switching circuitry is delayed so as to prevent a short circuit condition within the inverter.

5. The method of claim 4, wherein said value of deadtime decreases as the value of said command voltage signal decreases.

6. The method of claim 4, wherein said value of deadtime is obtained through a lookup table.

7. The method claim 4, further comprising:

inputting said command voltage signal into a linearization block, thereby producing a first level compensated command voltage therefrom; and

inputting said first level compensated command voltage into an active deadtime control block, thereby producing a deadtime command signal and a second level compensated command voltage therefrom.

8. An electric power steering system, comprising:

a steering input device coupled to one or more steerable wheels;

an assist actuator including an electric motor for providing an assist torque to said one or more steerable wheels, said motor further including an inverter for applying a series of phase voltages thereto; and

a controller for generating a set of control signals to be applied to said inverter, said controller further comprising;

means for receiving a command voltage signal indicative of a desired load to be driven by said electric motor;

means for determining, based upon the value of said command voltage signal, a value of deadtime to be applied to switching circuitry in said inverter;

means for adjusting the value of said command voltage signal in response to said value of deadtime, thereby producing a compensated command voltage signal to be applied to the motor through the switching circuitry in the inverter; and

wherein said value of deadtime relates to an amount of time in which the switching of a device in said switching circuitry is delayed so as to prevent a short circuit condition within said inverter.

9. A storage medium, comprising:

a machine readable computer program code for implementing active deadtime control of an inverter associated with an electric motor; and

instructions for causing a computer to implement a method, the method further comprising;

receiving a command voltage signal indicative of a desired load to be driven by the motor;

determining, based upon the value of said command voltage signal, a value of deadtime to be applied to switching circuitry in the inverter;

adjusting the value of said command voltage signal in response to said value of deadtime, thereby producing a compensated command voltage signal to be applied to the motor through the switching circuitry in the inverter; and

wherein said value of deadtime relates to an amount of time in which the switching of a device in the switching circuitry is delayed so as to prevent a short circuit condition within the inverter.

10. A computer data signal, comprising:

code configured to cause a processor to implement a method for implementing active deadtime control of an inverter associated with an electric motor, the method further comprising;

receiving a command voltage signal indicative of a desired load to be driven by the motor;

determining, based upon the value of said command voltage signal, a value of deadtime to be applied to switching circuitry in the inverter;

adjusting the value of said command voltage signal in response to said value of deadtime, thereby producing a compensated command voltage signal to be applied to the motor through the switching circuitry in the inverter; and

wherein said value of deadtime relates to an amount of time in which the switching of a device in the switching circuitry is delayed so as to prevent a short circuit condition within the inverter.