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A Space Pulse Width Modulation Method for Three-level Converter

A pulse width modulation, converter technology, applied in the direction of converting AC power input to DC power output, electrical components, output power conversion devices, etc., can solve the three-level converter midpoint potential offset, influence control Problems such as real-time performance and large amount of calculation

Inactive Publication Date: 2016-03-30
CHINA UNIV OF MINING & TECH
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  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

[0005] The purpose of the present invention is to provide a space pulse width modulation method for a three-level converter, which combines a simplified modulation algorithm of a three-level converter with a midpoint potential control strategy to solve the computational burden of traditional modulation algorithms Solve the problem of midpoint potential offset of three-level converters while solving problems such as large size, low calculation efficiency, and affecting real-time control

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  • A Space Pulse Width Modulation Method for Three-level Converter
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  • A Space Pulse Width Modulation Method for Three-level Converter

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Embodiment Construction

[0032] The present invention will be further described below in conjunction with the accompanying drawings and specific embodiments.

[0033] figure 1 It is the circuit diagram of the diode-clamped (NPC) three-level converter. Each bridge arm is composed of four sets of switching devices connected in series and a pair of clamping diodes connected in series. The center tap of the clamping diode is connected to the neutral point of the DC side to realize neutral point clamping. The converter has 27 switch states in total, among which, the switch tube S x1 and S x3 Can not be turned on at the same time, the switch tube S x2 and S x4 cannot be turned on at the same time (x=a,b,c), therefore, only need to calculate S x1 and S x2 The control signals of the four switch tubes of the bridge arm can be obtained at the conduction moment of the bridge arm.

[0034] figure 2 It is the voltage space vector distribution diagram of the three-level converter.

[0035] Such as figure...

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Abstract

The invention discloses a space pulse width modulation scheme for a three-level converter. The scheme comprises the steps of firstly, taking three-phase reference voltage and direct-current side voltage Vdc as reference values for per-unit treatment to obtain voltages Va, Vb and Vc; secondly, judging the maximum values of the absolute values of the Va, Vb and Vc and correcting the Va, Vb and Vc according to the judgment results to obtain Va', Vb'and Vc'; thirdly, calculating time variables ta, tb and tc according to the maximum value and the minimum value in the Va', Vb'and Vc'; fourthly, getting an adjustment factor k and regulating the ta, tb and tc by the k to obtain Ta, Tb and Tc; and fifthly, switching a converter switching device according to the Ta, Tb and Tc to enable the output voltage of the three-level converter and the reference voltage to be equivalent. According to the modulation scheme, section judgment, action time calculation and other processes in the traditional method are not required, the scheme is arranged clearly and can be realized simply, the scheme has the capability of inhibiting midpoint potential shifting, and does not require hardware facility, so that the cost is saved.

Description

technical field [0001] The invention relates to a three-level converter space pulse width modulation method and a midpoint potential control strategy, in particular to a three-level converter space pulse width modulation method based on a simplified algorithm. Background technique [0002] Among the existing three-phase converter control methods, the voltage space vector modulation (SVPWM) technology has a higher DC voltage utilization rate than the SPWM modulation technology, and has the advantages of high quality waveforms, low harmonic content, and convenient digital signal processing. The advantages of real-time control of the processor are widely used. [0003] Diode-clamped (NPC) three-level converters can output better voltage and current waveforms than two-level converters, and their withstand voltage performance is stronger than that of two-level converters, so they have been widely used in recent years. The three-level converter has many switching states, and the ...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): H02M7/487
Inventor 周娟刘马隆楚程媛王晓莹汪山林孟鑫王福均陈映杨宇杜少通
Owner CHINA UNIV OF MINING & TECH
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