Step wave pulse width modulation method based on nonlinear programming

A non-linear programming and pulse width modulation technology, applied in the direction of output power conversion devices, electrical components, AC power input conversion to DC power output, etc.

Active Publication Date: 2012-07-18
ELECTRIC POWER RESEARCH INSTITUTE, CHINA SOUTHERN POWER GRID CO LTD +1
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Problems solved by technology

Its disadvantage is that the calculation of the trigger angle is based on the Fourier series of the steady-state waveform, which is obtained by solving a series of transcendental equations
Therefore, for higher level conve

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  • Step wave pulse width modulation method based on nonlinear programming
  • Step wave pulse width modulation method based on nonlinear programming
  • Step wave pulse width modulation method based on nonlinear programming

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[0061] to combine figure 1 (d) shows the schematic diagram of the topology of the modular multilevel converter. After analysis, it can be seen that the principle of phase voltage waveform generation using NP-DPWM modulation is as follows: image 3 shown. because N The phase voltage waveform output by the level MMC has 1 / 4 cycle odd symmetry, so the working principle of NP-DPWM is to select the appropriate within the cycle M firing angle ( ), so that the fundamental wave component in the ladder wave output by the converter is close to the given modulation wave (see Figure 4 ). The following first introduces M Value selection principle.

[0062] (1) OK M value

[0063] For the mainstream two-level or three-level voltage source converters on the market (HVDC Light produced by ABB), due to the use of planar pressure-bonded IGBTs, the devices are directly crimped without leads. Once the IGBT fails, it must be Take the inverter out of service to complete the replacement...

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Abstract

The invention relates to a step wave pulse width modulation method based on nonlinear programming. The step wave pulse width modulation method comprises the following steps of: correspondingly calculating the number of sub-modules in a part to be added or cut according to increase or decrease of a modulation degree so as to reach required alternating current voltage output; secondly, establishing a nonlinear programming mathematical model of the modulation method with a goal that the approximate error of a fundamental wave component in the step wave outputted by a current converter is minimum relative to a given modulation wave on the basis of a theoretically output step waveform Fourier transform result by selecting an initial value of a triggering angle; finally obtaining the solution of the triggering angle under a corresponding level number and modulation degree. The step wave pulse width modulation method based on the nonlinear programming, disclosed by the invention, overcomes defects of a specific sub-harmonic elimination method that calculation amount is huge and on-line real-time calculation cannot be carried out. A switch device is only switched on and off once in one cyclic wave, the remarkable advantage of small switching loss is achieved. The step wave pulse width modulation method based on the nonlinear programming, disclosed by the invention, has better expandability, can theoretically finish trigger impulse control tasks of voltage source current converters with any quantity of levels, has stronger transportability, is suitable for modularized multi-level converters and is also suitable for cascaded H-shaped bridge type voltage source current converters with a large quantity of levels.

Description

technical field [0001] The invention belongs to the field of high-voltage direct current transmission and FACTS based on a voltage source converter (Voltage Source Converter, VSC), and specifically relates to a modular multilevel converter (Modular Multilevel Converter, MMC) or a cascaded H-bridge voltage source converter. Direct Pulse Width Modulation (DPWM) technology of converters, especially a step wave pulse width modulation method based on nonlinear programming. Background technique [0002] In 1990, Boon-Teck Ooi and others from McGill University in Canada first proposed the concept of DC transmission using a voltage source converter (Voltage Source Converter, VSC) and PWM modulation technology based on fully controlled power switching devices. This new generation of DC transmission technology based on voltage source converters, turn-off devices and pulse width modulation (PWM) technology is officially called VSC-HVDC by CIGRE and IEEE, the authoritative academic orga...

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Application Information

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IPC IPC(8): H02M7/501
CPCH02M7/5395H02M7/4835H02M7/4837
Inventor 李广凯赵成勇徐政李科许树楷
Owner ELECTRIC POWER RESEARCH INSTITUTE, CHINA SOUTHERN POWER GRID CO LTD
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