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Three-level converter neutral point potential balancing control method and device

A potential balance and control device technology, applied in the direction of output power conversion device, AC power input conversion to DC power output, electrical components, etc., can solve problems such as different power factors and poor load adaptability, and achieve good robustness With fast response, to achieve the effect of neutral point potential balance control

Active Publication Date: 2014-09-24
XUJI GRP +3
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Problems solved by technology

[0007] The purpose of the present invention is to provide a midpoint potential balance control method and device for an NPC three-level converter, which is used to solve the problem that the existing multi-carrier pulse width modulation method for zero-sequence voltage injection has poor adaptability to different power factors and loads. bad question

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  • Three-level converter neutral point potential balancing control method and device
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  • Three-level converter neutral point potential balancing control method and device

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Embodiment Construction

[0027] The present invention will be described in further detail below in conjunction with the accompanying drawings.

[0028] The topology of a three-level converter with diode midpoint clamping is as follows: figure 1 As shown, the variable names and symbols are as follows:

[0029] N--the midpoint of the DC bus of the converter; U dc1 -- DC bus voltage on the upper side of the converter midpoint; U dc2 -- DC bus voltage on the lower side of the converter midpoint.

[0030] Reasons for midpoint potential imbalance:

[0031] a) Differences in the hardware parameters of the DC bus capacitors, that is, due to errors in hardware manufacturing, the capacitance and voltage distribution on the two capacitors on the DC side are uneven.

[0032] b) The hardware difference of the power switching device, that is, the manufacturing difference of the power switching device will cause switching delay and uneven pulse distribution, which will affect the midpoint voltage of the DC side....

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Abstract

The invention relates to a three-level converter neutral point potential balancing control method and device which can be used to realize the zero potential control of the neutral point potential and has important practical significance. According to the invention, the multi-carrier CBPWM method based on zero sequence voltage injection is adopted to realize the neutral point potential balancing control. The upper voltage and the lower voltage of a direct-current bus neutral point are acquired, the different of the two voltages is inputted into a sliding mode variable structure controller to obtain the zero sequence voltage, and the zero sequence voltage is superimposed to the original three-phase modulation wave, so the neutral point voltage balancing control effect can be realized. The scheme has advantages of fast response speed and good robustness, and can be adapt to working conditions of different power factors and loads.

Description

technical field [0001] The invention relates to a method and device for controlling midpoint potential balance of an NPC three-level converter. Background technique [0002] In recent years, with the development of high-power power electronics technology, multi-level converters have been widely used, which have the characteristics of low harmonic content, high efficiency, and large capacity. The common topology of the three-level converter is the diode neutral point clamp (NPC) structure, such as figure 1 shown. Compared with the two-level topology, it has the following advantages: 1) Under the same switching frequency, the harmonic content of the output voltage and current is greatly reduced; 2) The voltage borne by the power tube is half of the bus voltage; 3) The switching loss of the power tube is low. [0003] The problem of midpoint potential balance is a hot and difficult point in the research of three-level. In the three-level modulation algorithm, multi-carrier p...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H02M7/487
Inventor 赵宇肖鹏刘刚孙健梁燕许恩泽刘海舰郜亚秋
Owner XUJI GRP
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