Electronic commutator circuits

• US 20070145928A1
• Filed: 12/11/2006
• Published: 06/28/2007
• Est. Priority Date: 12/17/2005
• Status: Active Grant

• Current Assignee: GE Energy Power Conversion Technology Limited (GE Vernova, Inc.)
• Original Assignee: Converteam UK Limited (General Electric Company)
• Inventors: Crane, Allan
• Granted Patent: US 7,852,025 B2
• Time in Patent Office: Days
• US Class Current: 318/400.260
• CPC Class Codes: H02P 25/024 controlled by supply frequency
• CPC Class Codes: H02P 8/00 Arrangements for controlling dynamo-electric motors rotating step by step
• CPC Class Codes: H03K 17/06 Modifications for ensuring a fully conducting state
• CPC Class Codes: H03K 2217/0036 Means reducing energy consumption

Abstract

The present invention provides an electronic commutator circuit for use with a stator winding of an electrical machine. The stator winding of the electrical machine includes a number of coils linked by the same number of points of common coupling. The electronic commutator circuit comprising the same number of switching stages, each switching stage being connected between a respective one of the points of common coupling and first and second dc terminals. Each switching stage further includes a first reverse blocking semiconductor power device (such as a Reverse Blocking Gate Turn Off Thyristor (RB-GTO 1) capable of being turned on and off by gate control having its anode connected to the first dc terminal, and a second reverse blocking semiconductor power device (RB-GTO 2) capable of being turned on and off by gate control having its cathode connected to the second dc terminal.

Claims

1. An electronic commutator circuit for use with a stator winding of an electrical machine, the stator winding having a number of coils linked by the same number of points of common coupling, the electronic commutator circuit comprising the same number of switching stages, each switching stage being connected between a respective one of the points of common coupling and first and second dc terminals and including:

a first reverse blocking semiconductor power device capable of being turned on and off by gate control having its anode connected to the first dc terminal; and

a second reverse blocking semiconductor power device capable of being turned on and off by gate control having its cathode connected to the second dc terminal.

2. An electronic commutator circuit according to claim 1, wherein the first and second semiconductor power devices have internal regenerative properties.

3. An electronic commutator circuit according to claim 1, wherein the first and second semiconductor power devices have unity gain turn off properties.

4. An electronic commutator circuit according to claim 1, further comprising a first polarised switching aid network connected in parallel with the first semiconductor power device and a second polarised switching aid network connected in parallel with the second semiconductor power device.

5. An electronic commutator circuit according to claim 1, wherein each switching stage further comprises a reactor having a winding that is connected between:

(i) the cathode of the first semiconductor power device and the associated point of common coupling, and

(ii) the anode of the second semiconductor power device and the associated point of common coupling.

6. An electronic commutator circuit according to claim 5, wherein the reactor includes a core that saturates at a small fraction of the rated machine winding current of the electrical machine.

7. An electrical machine comprising a moving part, a stator, a stator winding having a number of coils linked by the same number of points of common coupling, and an electronic commutator circuit comprising the same number of switching stages, each switching stage being connected between a respective one of the points of common coupling and first and second dc terminals and including:

a first reverse blocking semiconductor power device capable of being turned on and off by gate control having its anode connected to the first dc terminal; and

a second reverse blocking semiconductor power device capable of being turned on and off by gate control having its cathode connected to the second dc terminal;

wherein each switching stage of the electronic commutator circuit is connected between a respective one of the points of common coupling and first and second dc terminals.

8. An electrical machine according to claim 7, further comprising a controller for receiving a phase position signal and supplying a sequence of firing commands to the first and second semiconductor power devices of each switching stage of the electronic commutator circuit in order to cause a stepwise rotation of the stator MMF.

9. An electrical machine according to claim 8, wherein the controller further comprises a phase reference generator for receiving the phase position signal and supplying a phase reference signal in the form of a rotating vector to a firing sequence generator.

10. An electrical machine according to claim 9, wherein the sequence of firing commands has a fixed phase relationship with the phase reference signal.

11. An electrical machine according to claim 8, wherein the controller further comprises:

a phase reference generator for receiving the phase position signal, and

a phase controller for receiving;

(i) a phase reference signal from the phase reference generator, (ii) a load angle demand signal and (iii) a signal that represents the stepwise rotation of the stator MMF, and supplying a processed phase reference signal in the form of a rotating vector to a firing sequence generator.

12. An electrical machine according to claim 8, wherein the phase position signal is time-dependent.

13. An electrical machine according to claim 8, wherein the phase position signal is synchronised to the progression of voltage waveforms between adjacent points of common coupling of the stator winding.

14. An electrical machine according to claim 8, wherein the phase position signal is synchronised to the absolute position of the moving part.

15. An electrical machine according to claim 8, wherein the phase position signal is synchronised to the incremental position and direction of the moving part.

16. An electrical machine according to claim 11, wherein the phase controller determines the load angle between the rotating vector representing the processed phase reference signal and a vector that represents the stator MMF, and regulates the load angle in response to the load angle demand signal.

17. An electrical machine according to claim 16, wherein the phase controller regulates the load angle by closed loop means.

18. An electrical machine according to claim 16, wherein the phase controller regulates the load angle to be substantially zero.

19. An electrical machine according to claim 16, wherein the phase controller regulates the load angle in order to achieve a desired level of machine excitation.

20. An electrical machine according to claim 16, wherein the phase controller regulates the load angle in order to achieve a desired relationship between the respective magnitudes of:

(i) the mean voltage between the first and second dc terminals of the electronic commutator circuit, and

(ii) a stator winding voltage,

in order to regulate the mean voltage between the first and second dc terminals and/or the mean current flowing in the first and second dc terminals.

21. An electrical machine according to claim 11, being a synchronous rotating machine with a permanent magnet type rotor providing a machine excitation, wherein the phase controller determines the load angle between the rotating vector representing the phase reference signal and a vector that represents the stator MMF, and regulates the load angle in response to the load angle demand signal to achieve a desired superimposed component of machine excitation that can be added to, or subtracted from, the machine excitation provided by the permanent magnet type rotor.

22. An electrical machine according to claim 7, being a rotating electrical machine and where the moving part is a rotor.

23. An electrical machine according to claim 22, being an induction machine with a cage type rotor.

24. An electrical machine according to claim 22, being an induction machine with a wound type rotor.

25. An electrical machine according to claim 22, being a synchronous machine with a wound type rotor.

26. An electrical machine according to claim 22, being a synchronous machine with a permanent magnet type rotor.

27. An electrical machine according to claim 7, being a linear electrical machine and where the moving part is a translator.