A three-level shepwm method for suppressing common-mode voltage

A common-mode and three-level suppression technology, which is applied to electrical components, output power conversion devices, and conversion of AC power input to DC power output, can solve problems such as inability to effectively suppress common-mode voltage, and achieve common-mode voltage suppression Effect

Active Publication Date: 2018-08-14
ANHUI UNIVERSITY
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Problems solved by technology

[0004] The existing three-level SHEPWM method cannot effectively suppress the common-mode voltage

Method used

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  • A three-level shepwm method for suppressing common-mode voltage
  • A three-level shepwm method for suppressing common-mode voltage
  • A three-level shepwm method for suppressing common-mode voltage

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Embodiment Construction

[0036] Such as figure 1 As shown, a kind of three-level specific harmonic elimination pulse width modulation method for suppressing common-mode voltage of the present invention comprises the following steps:

[0037] S1. Determine the number of switching angles and the degree of modulation according to the performance requirements of the control system; in this embodiment, the number of switching angles is 4, and the degree of modulation is 1.0;

[0038] S2, establish a three-level SHEPWM model,

[0039]

[0040] where U d is the power supply voltage on the DC side, and the modulation degree of the fundamental wave N is the number of switching angles taken in 1 / 4 cycle, and the switching angles should meet the conditions:

[0041] Taking one of the three-level inverters that can eliminate the 5th, 7th, and 11th harmonics, the SHEPWM solution set is described as an example. The solution set is α1=14°, α2=63°, α3=67°, α4= 83°. And draw the three-phase output waveform ...

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Abstract

The invention relates to a three-level SHEPWM method for suppressing a common-mode voltage, comprising the following steps: obtaining the switching angle, drawing a three-phase output waveform diagram; considering the three-phase output of the SHEPWM as a space vector set consistent with the SVPWM, and calculating the large The common mode voltage corresponding to the vector, medium vector, positive small vector, negative small vector and zero vector; according to the three-phase voltage output waveform, the output vector change and action range within a cycle of 360° can be obtained by calculation; the three-phase output in the current time period can be judged Vector type; when the type of the three-phase output vector is a positive small vector, switch its three-phase switch state to the negative small vector paired with the same position of the positive small vector; when the type of the three-phase output vector is the other 4 types In the vector type, the three-phase SHEPWM switch state is output as usual. The invention can maintain the self-balancing characteristic of the midpoint voltage and effectively reduce the common-mode voltage output by the inverter without affecting the elimination of specific harmonics of the line voltage.

Description

technical field [0001] The invention relates to a three-level converter modulation method, in particular to a three-level specific harmonic elimination pulse width modulation (SHEPWM) method for suppressing common-mode voltage. Background technique [0002] With the advancement of science and technology and the improvement of living standards, people's requirements for power quality are also constantly improving. Multi-level converters such as three-level converters are more and more used in industries and social life to provide better quality. of electric energy. [0003] SHEPWM makes certain low-order harmonics not exist in the output voltage by setting a "gap" at a specific position of the output voltage waveform. Since the phase voltage waveform satisfies odd symmetry and π / 2 symmetry. The basic principle is to expand the inverter output voltage waveform into the form of Fourier series, make the Fourier coefficients of the low-order harmonics zero, obtain a set of nonl...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): H02M1/12H02M7/483
Inventor 胡存刚胡军王群京李国丽陆寅郑常宝
Owner ANHUI UNIVERSITY
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