Method and system for controlling a control installation of an electric motor

Patent metadata

Field	Value
Publication number	US-10141871-B2
Application number	US-201715397983-A
Country	US
Kind code	B2
Filing date	Jan 4, 2017
Priority date	Feb 18, 2016
Publication date	Nov 27, 2018
Grant date	Nov 27, 2018

Abstract

A control method which is deployed in a control installation of an electric motor, the control installation including a first converter controlled for the application of the first voltage pulse edges to an electric motor of a first pulse width modulation, obtained by comparing a first carrier signal, applied at a first chopping frequency, with a first modulating signal, a second converter controlled of a second pulse width modulation, obtained by comparing a second carrier signal, applied at a second chopping frequency, with a second modulating signal. The control method involves the determination of a notional optimum phase-shift angle on the basis of the first chopping frequency and the second chopping frequency.

First claim

The invention claimed is:

1. A control method deployed in a control installation of an electric motor, wherein said control installation includes:
a number of input phases, which are designed for connection to an electric grid system for the delivery of an AC voltage,
a common mode filter connected on the input phases, comprising at least one inductance,
a DC supply bus, which is arranged for the delivery of a DC voltage,
a first converter connected to said DC supply bus, controlled for the application of the first voltage pulse edges to an electric motor by a first pulse width modulation, obtained by comparing a first carrier signal, described as the reference carrier signal, applied at a first chopping frequency, with a first modulating signal,
a second converter connected to said DC supply bus and controlled by a second pulse width modulation, obtained by comparing a second carrier signal, applied at a second chopping frequency, with a second modulating signal, and
said second carrier signal being designed to be out-of-phase with the reference carrier signal by a phase-shift angle,
the control method comprising:
determining an optimum phase-shift angle from the first chopping frequency and the second chopping frequency, wherein said optimum phase-shift angle corresponds to a phase-shift angle for which the maximum magnetic flux received by the inductance of the common mode filter is at a minimum.

2. The method according to claim 1 , further comprising determining a ratio between the first chopping frequency and the second chopping frequency.

3. The method according to claim 2 , further comprising reading off a predefined data table containing a number of stored values for the ratio and, for each ratio value, a notional optimum phase-shift angle corresponding to a maximum magnetic flux.

4. The method according to claim 3 , wherein the optimum phase-shift angle corresponds to said notional optimum phase-shift angle when the control installation has a symmetrical architecture with regard to the ground.

5. The method according to claim 3 , wherein the optimum phase-shift angle corresponds to said notional optimum phase-shift angle, subject to addition of a corrective value, when the control installation has an asymmetrical architecture with regard to the ground.

6. The method according to claim 3 , wherein the optimum phase-shift angle corresponds to the notional optimum phase-shift angle, subject to addition of a value of 180°, when the second converter in the control installation is of the active rectifier type.

7. The method according to claim 3 , wherein, when the control installation comprises a third converter which is controlled by a third pulse width modulation, obtained by comparing a third carrier signal, applied at a third chopping frequency, with a third modulating signal, the method further comprising:
determining a first ratio between the chopping frequency of the first carrier signal and the chopping frequency of the second carrier signal;
determining a second ratio between the chopping frequency of the first carrier signal and the chopping frequency of the third carrier signal; and
determining a series of two notional optimum phase-shift angles associated with a series formed by the first ratio and by the second ratio thus determined.

8. The method according to claim 4 , further comprising detecting achievement by the first carrier signal of a minimum value, and synchronizing the second carrier signal in relation to the first carrier signal, in order to take account of the determined optimum phase-shift angle.

9. The method according to claim 5 , wherein the corrective value is determined on the basis of the difference between a notional magnetic flux and an actual magnetic flux measured for the inductance of the common mode filter.

10. A control system associated with a control installation, which includes:
a number of input phases, which are designed for connection to an electric grid system for the delivery of an AC voltage,
a common mode filter connected on the input phases, comprising at least one inductance,
a DC supply bus, which is arranged for the delivery of a DC voltage,
a first converter connected to said DC supply bus, controlled for the application of the first voltage pulse edges to an electric motor by a first pulse width modulation, obtained by comparing a first carrier signal, described as the reference carrier signal, applied at a first chopping frequency, with a first modulating signal,
a second converter connected to said DC supply bus and controlled by a second pulse width modulation, obtained by comparing a second carrier signal, applied at a second chopping frequency, with a second modulating signal, and
said second carrier signal being designed to be out-of-phase with the reference carrier signal by a phase-shift angle, the control system comprising:
circuitry configured to determine an optimum phase-shift angle from the first chopping frequency and the second chopping frequency, wherein said optimum phase-shift angle corresponds to a phase-shift angle for which a maximum magnetic flux received by the inductance of the common mode filter is at a minimum.

11. The system according to claim 10 , wherein the circuitry is further configured to determine a ratio between the first chopping frequency and the second chopping frequency.

12. The system according to claim 11 , wherein the circuitry is further configured to read-off a predefined data table containing a number of stored values for a ratio and, for each ratio value, a notional optimum phase-shift angle corresponding to said maximum magnetic flux thus determined.

13. The system according to claim 12 , wherein the optimum phase-shift angle corresponds to said notional optimum phase-shift angle when the control installation has a symmetrical architecture with regard to the ground.

14. The system according to claim 12 , wherein the optimum phase-shift angle corresponds to said notional optimum phase-shift angle, subject to addition of a corrective value when the control installation has an asymmetrical architecture with regard to the ground.

15. The system according to claim 12 , wherein the circuitry is further configured to detect achievement by the first carrier signal of a minimum value, and synchronize the second carrier signal in relation to the first carrier signal, in order to take account of the optimum phase-shift angle thus determined.

16. The system according to claim 12 , wherein the optimum phase-shift angle corresponds to the notional optimum phase-shift angle, subject to addition of a value of 180°, when the second converter in the control installation is of the active rectifier type.

17. The system according to claim 12 , wherein, when the control installation comprises a third converter which is controlled by a third pulse width modulation, obtained by the comparison of a third carrier signal, applied at a third chopping frequency, with a third modulating signal, the circuitry is further configure to
determine a first ratio between the chopping frequency of the first carrier signal and the chopping frequency of the second carrier signal,
determine a second ratio between the chopping frequency of the first carrier signal and the chopping frequency of the third carrier signal, and
determine a series of two notional optimum phase-shift angles associated with a series formed by the first ratio and the second ratio thus determined.

18. The system according to claim 14 , wherein the corrective value is determined on the basis of the differen

Assignees

• Schneider Toshiba Inverter Europe Sas

Inventors

• Messaoudi Mehdi
• Boulharts Hocine

Classifications

• H02M7/46

  using discharge tubes without control electrode or semiconductor devices without control electrode · CPC title

• H02P5/74 Primary

  controlling two or more AC dynamo-electric motors (H02P5/46, H02P5/60 take precedence) · CPC title

• H02M1/126

  using passive filters · CPC title

• H02M2001/123

  Electricity · mapped topic

• H02M7/23

  arranged for operation in parallel {(H02M7/2176 takes precedence)} · CPC title