A method for operating a plurality of chopper circuits

Patent metadata

Field	Value
Publication number	US-2020362823-A1
Application number	US-201816956462-A
Country	US
Kind code	A1
Filing date	Nov 30, 2018
Priority date	Dec 19, 2017
Publication date	Nov 19, 2020
Grant date	—

Abstract

The present invention relates to a method for simultaneous operation of a plurality of chopper circuits of a wind turbine power converter, the method comprising the steps of operating a controllable switching member of a first chopper circuit in accordance with a first switching pattern, and operating a controllable switching member of a second chopper circuit in accordance with a second switching pattern, wherein the first switching pattern is different from the second switching pattern during a first time period. In order to reduce switching losses the first switching pattern may involve that the controllable switching member of the first chopper circuit is clamped during the first time period. Additional chopper circuits may be provided in parallel to the first and second chopper circuits. The present invention further relates to a power dissipation chopper being operated in accordance with the before mentioned method.

First claim

1 . A method for simultaneous operation of a plurality of chopper circuits of a wind turbine power converter, the method comprising:
operating a controllable switching member of a first chopper circuit in accordance with a first switching pattern, and operating a controllable switching member of a second chopper circuit in accordance with a second switching pattern,
wherein the first switching pattern is different from the second switching pattern during a first time period, and wherein the first switching pattern involves that the controllable switching member of the first chopper circuit is clamped during the first time period.

2 . The method of claim 1 , wherein clamping of the controllable switching member of the first chopper circuit involves that this controllable switching member is either constantly on or off during the first time period.

3 . The method of claim 2 , wherein the second switching pattern involves that a modulation pattern having a given switching frequency is applied to the controllable switching member of the second chopper circuit during the first time period.

4 . The method of claim 3 , wherein the switching frequency applied to the controllable switching member of the second chopper circuit has a switching period being at least 10 times shorter than the first time period, such as 15 times shorter than the first time period, such as 20 times shorter than the first time period.

5 . The method of claim 4 , wherein, during a second time period immediately following the first time period, the second switching pattern involves that the controllable switching member of the second chopper circuit is clamped.

6 . The method of claim 5 , wherein clamping of the controllable switching member of the second chopper circuit involves that this controllable switching member is either constantly on or off during the second time period.

7 . The method of claim 6 , wherein the first switching pattern involves that a modulation pattern having a given switching frequency is applied to the controllable switching member of the first chopper circuit during the second time period.

8 . The method of claim 7 , wherein the switching frequency applied to the controllable switching member of the first chopper circuit has a switching period being at least 10 times shorter than the second time period, such as 15 times shorter than the second time period, such as 20 times shorter than the second time period.

9 . The method of claim 5 , wherein the second time period is triggered in response to a measured temperature of the controllable switching member of the second chopper circuit.

10 . A The method of claim 1 , wherein additional chopper circuits are provided, and wherein the first, second and additional chopper circuits are coupled in parallel.

11 . A power dissipation chopper assembly for a wind turbine power converter, the power dissipation chopper assembly comprising:
a first chopper circuit comprising a power dissipation member and controllable switching member configured to be operated in accordance with a first switching pattern, a second chopper circuit comprising a power dissipation member and controllable switching member configured to be operated in accordance with a second switching pattern, and a control unit configured for simultaneous operation of the controllable switching members in accordance with the first and second switching patterns, wherein the first switching pattern is different from the second switching pattern during a first time period, and wherein the first switching pattern involves that the controllable switching member of the first chopper circuit is clamped during the first time period.

12 . A power dissipation chopper assembly according to claim 11 , wherein additional chopper circuits are provided, and wherein the first, second and additional chopper circuits are coupled in parallel.

13 . A power dissipation chopper assembly according to claim 11 or 12 , wherein the first switching pattern involves that the controllable switching member of the first chopper circuit is either constantly on or off during the first time period, and wherein the second switching pattern involves that a modulation pattern having a given switching frequency is applied to the controllable switching member of the second chopper circuit during the first time period.

14 . A power dissipation chopper assembly according to claim 13 , wherein, during a second time period immediately following the first time period, the second switching pattern involves that the controllable switching member of the second chopper circuit is either constantly on or off during the second time period, and wherein the first switching pattern involves that a modulation pattern having a given switching frequency is applied to the controllable switching member of the first chopper circuit during the second time period, and wherein the second time period is triggered in response to a measured temperature of the controllable switching member of the second chopper circuit.

15 . (canceled)

16 . A wind turbine power converter comprising a power dissipation chopper assembly connected to a DC-link between a rectifier and an inverter of the wind turbine power converter; the power dispensation chopper assembly, comprising:
a first chopper circuit comprising a power dissipation member and controllable switching member configured to be operated in accordance with a first switching pattern; a second chopper circuit comprising a power dissipation member and controllable switching member configured to be operated in accordance with a second switching pattern; and a control unit configured for simultaneous operation of the controllable switching members in accordance with the first and second switching patterns, wherein the first switching pattern is different from the second switching pattern during a first time period, and wherein the first switching pattern involves that the controllable switching member of the first chopper circuit is clamped during the first time period.

17 . A wind turbine power converter of claim 15 further comprising additional chopper circuits, and wherein the first, second and additional chopper circuits are coupled in parallel.

18 . A wind turbine power converter of claim 15 wherein the first switching pattern involves that the controllable switching member of the first chopper circuit is either constantly on or off during the first time period, and wherein the second switching pattern involves that a modulation pattern having a given switching frequency is applied to the controllable switching member of the second chopper circuit during the first time period.

Assignees

• Vestas Wind Sys As

Inventors

• Helle Lars
• Lund Torsten

Classifications

• H02J2101/28

  Wind energy · CPC title

• H02M5/44 Primary

  using discharge tubes or semiconductor devices to convert the intermediate DC into AC · CPC title

• H02M1/0054

  Transistor switching losses (periodically suspending operation of switching converter in low power mode H02M1/0035) · CPC title

• H02J3/381

  Dispersed generators · CPC title

• H02M5/4585

  having a rectifier with controlled elements · CPC title