Adjustable frequency drives using normalized modulation control signals to compensate for phase imbalance and methods of operating the same

Patent metadata

Field	Value
Publication number	US-2023412105-A1
Application number	US-202217807162-A
Country	US
Kind code	A1
Filing date	Jun 16, 2022
Priority date	Jun 16, 2022
Publication date	Dec 21, 2023
Grant date	—

Abstract

An apparatus includes a plurality of DC buses and a plurality of inverter circuits, respective ones of which are coupled to respective ones of the plurality of DC buses. The apparatus further includes a control circuit configured to generate a representative DC voltage signal based on DC voltage signals for respective ones of the DC buses, to generate a first modulation control signal from the representative DC voltage signal, to generate second modulation control signals for the respective inverter circuits from the representative DC voltage signal and the first modulation control signal that are normalized based on the DC voltage signals for the buses and the representative DC voltage signal, and to modulate the inverter circuits responsive to respective ones of the second modulation control signals. The representative DC voltage signal may represent a maximum of the DC voltages for the respective DC buses.

First claim

1 . An apparatus comprising:
a plurality of DC buses; a plurality of inverter circuits, respective ones of which are coupled to respective ones of the plurality of DC buses; and a control circuit configured to generate a representative DC voltage signal based on DC voltage signals for respective ones of the DC buses, to generate a first modulation control signal from the representative DC voltage signal, to generate second modulation control signals for the respective inverter circuits from the representative DC voltage signal and the first modulation control signal that are normalized based on the DC voltage signals for the buses and the representative DC voltage signal, and to modulate the inverter circuits responsive to respective ones of the second modulation control signals.

2 . The apparatus of claim 1 , wherein the representative DC voltage signal represents a maximum of the DC voltages for the respective DC buses.

3 . The apparatus of claim 2 , wherein the control circuit is configured to control an output frequency of the inverter circuits to limit DC voltages on the buses responsive to the representative DC voltage signal meeting a predetermined criterion.

4 . The apparatus of claim 1 , wherein the plurality of DC buses comprises a plurality of pairs of positive and negative DC buses, and wherein the DC voltage signals for the DC buses represent voltages between the positive and negative busses of the respective pairs of DC buses.

5 . The apparatus of claim 1 , wherein the first modulation control signal comprises a first modulation amplitude index signal and an angle signal and wherein the control circuit is configured to apply an inverse Clarke transformation to the first modulation amplitude index signal and angle signal to generate respective second modulation amplitude index signals, to generate respective gain factors for the respective inverter circuits based on the voltage signals for the DC buses and the representative DC voltage signal, and to scale respective ones of the second modulation amplitude index signals by the respective gain factors to generate respective ones of the second modulation control signals.

6 . The apparatus of claim 1 configured as a motor drive, wherein respective ones of the inverter circuits are configured to be coupled to respective phases of a motor.

7 . An apparatus comprising:
a plurality of DC buses; a plurality of inverter circuits, respective ones of which are coupled to respective ones of the plurality of DC buses; and a control circuit configured to generate a maximum DC voltage signal corresponding to a maximum DC voltage of the DC buses, to generate modulation control signals for respective ones of the inverter circuits responsive to the maximum DC voltage signal, to modulate the inverter circuits responsive to respective ones of the modulation control signals and to control an output frequency of the inverter circuits to limit DC voltages on the buses responsive to the maximum DC voltage signal meeting a predetermined criterion.

8 . The apparatus of claim 7 , wherein the control circuit is configured to generate the maximum voltage signal responsive to respective DC voltage signals for respective ones of the DC busses.

9 . The apparatus of claim 8 , wherein the plurality of DC buses comprises a plurality of pairs of positive and negative DC buses, and wherein the DC voltage signals for the respective DC buses represent voltages between the positive and negative busses of the respective pairs of DC buses.

10 . The apparatus of claim 8 , wherein the control circuit is configured to scale the modulation control signals based on a relationship between the DC voltage signals for the buses and the maximum DC voltage signal.

11 . The apparatus of claim 7 configured as a motor drive, wherein respective ones of the inverter circuits are configured to be coupled to respective phases of a motor.

12 . A method of operating a motor drive comprising a plurality of DC buses and a plurality of inverter circuits, respective ones of which are coupled to respective ones of the plurality of DC buses, the method comprising:
generating a representative DC voltage signal based on DC voltage signals for respective ones of the DC buses; generating a first modulation control signal from the representative DC voltage signal; generating second modulation control signals for respective ones of the inverter circuits from the representative DC voltage signal and the first modulation control signal that are normalized based on the DC voltage signals for the buses and the representative DC voltage signal; and modulating the inverter circuits responsive to respective ones of the second modulation control signals.

13 . The method of claim 12 , wherein the representative DC voltage signal represents a maximum of the DC voltages for the respective DC buses.

14 . The method of claim 13 , further comprising controlling an output frequency of the inverter circuits to limit DC voltages on the buses responsive to the representative DC voltage signal meeting a predetermined criterion.

15 . The method of claim 12 , wherein the plurality of DC buses comprises a plurality of pairs of positive and negative DC buses, and wherein the DC voltage signals for the DC buses represent voltages between the positive and negative busses of the respective pairs of DC buses.

16 . The method of claim 12 , wherein the first modulation control signal comprises a first modulation amplitude index signal and an angle signal, and wherein generating second modulation control signals comprises:
applying an inverse Clarke transformation to the first modulation amplitude index signal and angle signal to generate respective second modulation amplitude index signals for the respective inverter circuits; generating respective gain factors for the respective inverter circuits based on the voltage signals for the DC buses and the representative DC voltage signal; and scaling respective ones of the second modulation amplitude index signals by the respective gain factors to generate respective ones of the second modulation control signals.

17 . A method of operating a motor drive comprising a plurality of DC buses and a plurality of inverter circuits, respective ones of which are coupled to respective ones of the plurality of DC buses, the method comprising:
generating a maximum DC voltage signal corresponding to a maximum DC voltage of the DC buses; generating modulation control signals for respective ones of the inverter circuits responsive to the maximum DC voltage signal; modulating the inverter circuits responsive to respective ones of the modulation control signals; and controlling an output frequency of the inverter circuits to limit DC voltages on the buses responsive to the maximum DC voltage signal meeting a predetermined criterion.

18 . The method of claim 17 , wherein generating a maximum DC voltage signal corresponding to a maximum DC voltage of the DC buses comprises generating the maximum voltage signal responsive to respective DC voltage signals for respective ones of the DC busses.

19 . The method of claim 18 , wherein the plurality of DC buses comprises a plurality of pairs of positive and negative DC buses, and wherein the DC voltage signals for the respective DC buses represent voltages between the positive and negative busses of the respective pairs of DC buses.

20 . The method of claim 19 , comprising scaling the modulation control signals based on a relationship between the DC vo

Assignees

• Eaton Intelligent Power Ltd

Inventors

• Gibbs Irving A
• Nojima Geraldo
• Simms Stan Rex
• Farr Thomas A
• Braga Gabriel

Classifications

• H02P27/06 Primary

  using DC to AC converters or inverters (H02P27/05 takes precedence) · CPC title

• H02P27/085 Primary

  wherein the PWM mode is adapted on the running conditions of the motor, e.g. the switching frequency · CPC title