Method for controlling a motor using pulse width modulation (PWM)

Patent metadata

Field	Value
Publication number	US-9628000-B2
Application number	US-201214357343-A
Country	US
Kind code	B2
Filing date	Nov 2, 2012
Priority date	Nov 9, 2011
Publication date	Apr 18, 2017
Grant date	Apr 18, 2017

Abstract

A method controls a motor using pulse width modulation (PWM). The method involves measuring the PWM frequency; determining the carrier frequency of a set radio transmitter; and matching the PWM frequency to the carrier frequency of the radio transmitter in such a manner that an integer multiple of the PWM frequency corresponds to the carrier frequency or an integer multiple of the PWM frequency lies in the middle between two carrier frequencies.

First claim

The invention claimed is:

1. A method for controlling a motor using pulse width modulation (PWM), comprising:
measuring, by a controller, a PWM frequency;
determining, by the controller, one or more currently set carrier frequencies of a radio transmitter; and
trimming, by a prescaler, the PWM frequency to a select carrier frequency of the one or more currently set carrier frequencies, so that an integer multiple of the PWM frequency coincides with the select carrier frequency, or when there are at least two currently set carrier frequencies, so that an integer multiple of the PWM frequency lies in a middle between the two currently set carrier frequencies,
wherein
the select carrier frequency corresponds to a radio signal currently broadcast by the radio transmitter,
when there are at least two currently set carrier frequencies at least one other integer multiple of the PWM frequency coincides with at least one of the at least two currently set carrier frequencies, and
a currently set carrier frequency among the at least two currently set carrier frequencies which coincides with an integer multiple of the PWM frequency corresponds to a radio signal currently broadcast by the radio transmitter.

2. The method according to claim 1 , wherein the PWM frequency is trimmed using a digital prescaler.

3. The method according to claim 1 , further comprising:
determining a difference between the multiple of the PWM frequency and the select carrier frequency of the radio transmitter; and
slightly changing the PWM frequency if the difference exceeds a defined limit value.

4. The method according to claim 3 , wherein the PWM frequency is cyclically changed for adaptation purposes.

5. The method according to claim 3 , wherein the PWM frequency is changed by one or two bits to slightly change the PWM frequency.

6. The method according to claim 1 , wherein the PWM frequency is trimmed at defined time intervals.

7. The method as claimed in claim 1 , wherein
there are two currently set carrier frequencies,
for each currently set carrier frequency, audio information is transmitted in audio frequency bands adjacent to the carrier frequency,
the PWM frequency is trimmed so that integer multiples of the PWM frequency each fall outside the audio frequency bands, and
the PWM frequency is trimmed so that integer multiples of the PWM frequency falls on both of the currently set carrier frequencies respectively, and at least one integer multiple of the PWM frequency falls in the middle between the two currently carrier frequencies.

8. A method for controlling a motor using pulse width modulation (PWM), comprising:
supplying power to the motor via a pulse width modulated signal having a PWM frequency;
measuring, by a controller, the PWM frequency;
identifying, by the controller, at least two currently set carrier frequencies of a radio transmitter; and
trimming, by a prescaler, the PWM frequency so that an integer multiple of the PWM frequency lies in a middle between the two currently set carrier frequencies,
wherein
for each currently set carrier frequency, audio information is transmitted in audio frequency bands adjacent to the carrier frequency,
the PWM frequency is trimmed so that a first integer multiple of the PWM frequency falls in the middle between the two currently set carrier frequencies and so that a second integer multiple of the PWM frequency coincides with one of the currently set carrier frequencies, and
a currently set carrier frequency among the at least two currently set carrier frequencies which coincides with the second integer multiple of the PWM frequency corresponds to a radio signal currently broadcast by the radio transmitter.

9. The method as claimed in claim 8 , wherein the PWM frequency is trimmed so that integer multiples of the PWM frequency each fall outside the audio frequency bands.

10. The method according to claim 8 , wherein
for each currently set carrier frequency, audio information is transmitted in audio frequency bands adjacent to the carrier frequency, and
if the PWM frequency cannot be adjusted such that all integer multiples of the PWM frequency fall outside of the audio frequency bands, the PWM frequency is cyclically changed for adaptation purposes, to distribute interference energy over a plurality of frequencies.

11. A controller for an electric motor, comprising:
a quartz crystal or resonator to generate a pulse width modulation (PWM) signal to power the motor, the PWM signal having a PWM frequency;
a device to measure one or more currently set carrier frequencies of a radio transmitter; and
a prescaler to trim the PWM frequency to a select carrier frequency of the one or more currently set carrier frequencies, so that an integer multiple of the PWM frequency coincides with the select carrier frequency, or when there are at least two currently set carrier frequencies, so that an integer multiple of the PWM frequency lies in a middle between the two currently set carrier frequencies,
wherein
the select carrier frequency corresponds to a radio signal currently broadcast by the radio transmitter,
when there are at least two currently set carrier frequencies at least one other integer multiple of the PWM frequency coincides with at least one of the two currently set carrier frequencies, and
a currently set carrier frequency among the at least two currently set carrier frequencies which coincides with an integer multiple of the PWM frequency corresponds to a radio signal currently broadcast by the radio transmitter.

12. The controller according to claim 11 , wherein the prescaler to trim the PWM frequency is a digital prescaler.

13. The controller according to claim 11 , wherein the PWM frequency is cyclically changed by one or two bits for adaptation purposes.

14. A motor vehicle, comprising a controller according to claim 11 .

Assignees

• Audi Ag
• Conti Temic Microelectronic Gmbh

Inventors

• Schwantner Bernhard
• Kaeufl Georg

Classifications

• H02P29/50

  Reduction of harmonics · CPC title

• H02P6/28 Primary

  Arrangements for controlling current (H02P6/10 takes precedence) · CPC title

• H02P6/002 Primary

  Electricity · mapped topic

• H04B15/025 Primary

  Reducing interference from ignition apparatus of fuel engines (cables with high resistance H01B) · CPC title