Control methods for the synchronization and phase shift of the pulse width modulation (PWM) strategy of power converters

A technology of power converter and pulse width modulation, which is applied in the direction of irreversible DC power input conversion to AC power output, AC power input conversion to AC power output, AC power input conversion to DC power output, etc., which can solve the problem of total harmonic Wave voltage distortion and other problems, to achieve the effect of reducing harmonic distortion

Active Publication Date: 2008-11-19
CONVERTEAM TECH LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

Mixing between the nominal fixed frequency of the power grid or supply network and the switching frequency of the PWM strategy can cause harmonics in the AC output voltage of the bridge
If two or more power converters are connected to the common supply network or the power grid (for example, in the case of wind farms, where several wind turbines may be connected to the supply network in parallel), the total Harmonic voltage distortion has the potential to exceed the required limits defined for the common point

Method used

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  • Control methods for the synchronization and phase shift of the pulse width modulation (PWM) strategy of power converters
  • Control methods for the synchronization and phase shift of the pulse width modulation (PWM) strategy of power converters
  • Control methods for the synchronization and phase shift of the pulse width modulation (PWM) strategy of power converters

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Embodiment Construction

[0066] public time signal

[0067] The basic topology of a power converter arrangement for wind turbine applications using a common time signal is described with reference to FIG. 1 .

[0068] In the basic topology of Fig. 1, three parallel-connected power converters 1a, 1b and 1c are used to connect wind turbines 2 each driving a variable-speed AC induction generator 4 into a common power supply network (denoted as HV NETWORK). Each wind turbine typically includes three turbine blades (other numbers are possible) mounted on a rotating shaft, the pitch between the blades can be controlled by pitch actuators to optimize and / or limit wind energy capture to generator 4. A gearbox 8 is used to connect the rotating shaft to the rotor of each variable speed generator 4 . In some cases, the rotating shaft can be directly connected to the rotor of a variable speed generator.

[0069] It is readily understood that the induction generator 4 may be replaced by other types of generato...

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Abstract

The present invention provides a method of controlling a plurality of power converters (1a... 1c) that can be used to interface to a supply network, ac busbar etc. Each power converter includes a network bridge (14) operating in accordance with a pulse width modulation (PWM) strategy having the same switching period and which causes at least one unwanted harmonic in the supply network voltage. The method includes the step of providing the switching period of the PWM strategy of each network bridge with a different time offset relative to a time datum such that the at least one unwanted harmonic in the supply network voltage is at least partially cancelled. Two alternative ways of providing the time offset are described.

Description

technical field [0001] The present invention relates to a method of controlling the synchronization of power converters operating using a pulse width modulation (PWM) strategy, which power converters can be used to switch into a generator providing a variable frequency variable voltage with a nominal fixed voltage and Frequency grid or supply network. However, these methods can also be used for the synchronization of power converters operating using PWM strategies, where these power converters can be used, for example, to connect electric motors requiring frequency-variable voltage into a supply network with nominally fixed voltage and frequency (AC busbar). Other applications include the synchronization of power converters operating using PWM strategies configured to provide static volt-ampere passive (VAR) compensation. Background technique [0002] Regarding the first of the potential applications mentioned above, it is possible to convert wind energy into electrical en...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H02J3/38
CPCH02J3/1814Y02E10/763Y02E40/18H02M7/493H02J3/386H02J3/40H02J3/01H02J2310/42H02J2300/28H02J3/381Y02E10/76H02M1/0043H02M1/12H02M5/458H02M7/497H02M7/48Y02E40/40
Inventor 罗德尼·琼斯罗伯特·弗农·富尔彻亨里克·斯蒂斯达尔
Owner CONVERTEAM TECH LTD
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