Electric power converter

• US 20060256587A1
• Filed: 04/28/2006
• Published: 11/16/2006
• Est. Priority Date: 04/29/2005
• Status: Active Grant

• Current Assignee: Hitachi Energy Limited
• Original Assignee: ABB Technology Limited (ABB Ltd.)
• Inventors: Lundberg, Peter, Svensson, Jan, Lindberg, Johan, Hafner, Ying Jiang, Palsson, Rolf, Asplund, Gunnar
• Granted Patent: US 7,321,500 B2
• Time in Patent Office: Days
• US Class Current: 363/37
• CPC Class Codes: H02J 3/36 Arrangements for transfer of electric power between ac networks via a high-tension dc link
• CPC Class Codes: H02M 1/0054 Transistor switching losses periodically suspending operation of switching converter in low power mode H02M1/0035
• CPC Class Codes: H02M 5/4585 having a rectifier with controlled elements
• CPC Class Codes: H02M 7/5395 by pulse-width modulation
• CPC Class Codes: H02M 7/7575 for high voltage direct transmission link
• CPC Class Codes: Y02B 70/10 Technologies improving the efficiency by using switched-mode power supplies [SMPS], i.e. efficient power electronics conversion e.g. power factor correction or reduction of losses in power supplies or efficient standby modes
• CPC Class Codes: Y02E 60/60 Arrangements for transfer of electric power between AC networks or generators via a high voltage DC link [HVCD]

Abstract

A voltage source converter for high power application containing a plurality of valves, each valve containing a plurality of extinguishable semiconducting elements, and a valve control unit containing a computer and a pulse-width modulator providing an executing control signal for controlling the semiconducting elements. The valve control unit includes a first control containing a first pulse-width modulator for providing a first pulse-width modulation signal, a second control containing a second pulse-width modulator for providing, a second pulse-width modulation signal, a mode detector, and a selector connected to the first and second pulse-width modulator for selecting in dependence of the mode detector the executing pulse-width modulation signal.

Claims

1. A voltage source converter for high power application, comprising:

a plurality of valves, each valve comprising a plurality of extinguishable semiconducting elements,

a valve control unit comprising computer means and

a pulse-width modulator providing an executing control signal for controlling the semiconducting elements,

wherein the valve control unit comprises a first control comprising a first pulse-width modulator for providing a first pulse-width modulation signal a second control comprising a second pulse-width modulator for providing, a second pulse-width modulation signal, a mode detector, and a selector connected to the first and second pulse-width modulator for selecting in dependence of the mode detector the executing pulse-width modulation signal.

2. The voltage source converter according to claim 1, wherein the first pulse-width modulator comprises a carrier based pulse-width modulator.

3. The voltage source converter according to claim 1, wherein the second pulse-width modulator comprises an optimum pulse-width modulator.

4. The voltage source converter according to claim 1, wherein the second pulse-width modulator comprises a carrier based pulse-width modulator with a switching frequency different from the first pulse-width modulator.

5. The voltage source converter according to claim 1, wherein the first control comprises a transient control.

6. The voltage source converter according to claim 1, wherein the second control comprises a steady-state control.

7. The voltage source converter according to claim 1, wherein the valve control unit comprises a phase-locked loop unit common to the first control and the second control.

8. The voltage source converter according to claim 1, wherein the valve control comprises an outer control and an inner control common to the first control and the second control.

9. The voltage source converter according to claim 1, wherein the first control comprises a reference transformer.

10. The voltage source converter according to claim 9, wherein the first control further comprises an outer controller and an inner control.

11. The voltage source converter according to claim 1, wherein the second control comprises a reference transformer.

12. The voltage source converter according to claim 11, wherein the second control further comprises an outer control.

20. Use of a voltage source converter according to claim 1 or a method according to claim 14 in a HVDC transmission system for controlling the operation.

21. Use of a voltage source converter according to claim 1 or a method according to claim 14 in a static var compensation system for controlling the operation.

13. A method for controlling a voltage source converter comprising a plurality of valves, each comprising a plurality of extinguishable semiconducting elements in a high power application, the method comprising:

providing an executing pulse width modulation signal for controlling the voltage source converter,

controlling the voltage source converter during a first period of time wherein the executing signal comprises a first pulse-width modulation signal, and

controlling the voltage source converter during a second period of time, following the first period of time, wherein the executing signal comprises a second pulse-width modulation signal.

14. The method according to claim 13, wherein the second period of time comprises a steady state mode and the second pulse-width modulation signal comprises an optimum pulse-width modulation signal.

15. The method according to claim 13, wherein the second period of time comprises a steady state mode and the second pulse-width modulation signal comprises a carrier based pulse-width modulation signal.

16. The method according to claim 13, wherein the first period of time comprises a transient mode and the first pulse-width modulation signal comprises a carrier based pulse-width modulation signal.

17. A computer program product storable on a computer readable medium containing computer program instructions executable by a processor for performing the steps of

providing an executing pulse width modulation signal for controlling the voltage source converter,

controlling the voltage source converter during a first period of time wherein the executing signal comprises a first pulse-width modulation signal, and

controlling the voltage source converter during a second period of time, following the first period of time, wherein the executing signal comprises a second pulse-width modulation signal.

18. The computer program product according to claim 17 provided at least in part over a network, such as the Internet.

19. (canceled)