Overmodulation method implemented based on carrier

An overmodulation and carrier technology, applied in the field of carrier-based overmodulation, can solve the problems of complex, complex, and unfavorable engineering implementation of multilevel converter overmodulation, and avoid mathematical operations and a large number of logical judgments and implementation methods. simple effect

Active Publication Date: 2015-02-04
HEFEI UNIV OF TECH
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Problems solved by technology

[0006] It can be seen that the existing technology needs to calculate the holding angle and the action time of each vector, and then judge the position of the reference vector according to the holding angle and correct the amplitude and phase of the reference voltage. At the same time, the action time of the voltage vector needs to be corrected, and There is a problem of considering sector div

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  • Overmodulation method implemented based on carrier
  • Overmodulation method implemented based on carrier
  • Overmodulation method implemented based on carrier

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Embodiment Construction

[0057] In order to make the purpose, technical solution and advantages of the present invention more clear, the present invention will be further described in detail below in conjunction with the accompanying drawings and embodiments. Here, a typical overmodulation strategy of three-level converter is selected for illustration.

[0058] Such as figure 2 , 3 As shown, the three-level topology and space vector diagram are respectively. The inverter has 27 working states, corresponding to 27 basic space vectors, including 3 zero vectors and 12 amplitudes of A small vector with 6 magnitudes of The medium vector and 12 magnitudes are big vector.

[0059] Such as figure 1 Shown, technical scheme of the present invention is as follows:

[0060] Step 1, define the degree of modulation and calculate the three-phase original modulation wave

[0061] Let the modulation degree be M, and the three-phase original modulation wave be U 1i , where i=a, b and c, then

[0062] ...

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Abstract

The invention discloses an overmodulation method implemented based on a carrier. The method includes determining a three-phase original modulated wave U1i according to amplitude and phase of a reference vector in an overmodulation area; superposing a zero-sequence component V0 to the original modulated wave to acquire corresponding three-phase saddle modulated waves U2i, and sorting the three-phase saddle modulated waves U2i; in the overmodulation area, judging whether or not the reference vector is positioned in a linear modulation section, a hexagonal modulation section or a six-pulse wave modulation section according to the magnitude relationship between Umax and 2-|Umid|; correcting the three-phase saddle modulated waves in different modulation sections respectively to acquire a final three-phase modulated wave Ui; comparing the Ui with the triangular carrier to generate PWM (pulse-width modulation) waves, and distributing the PWM waves to corresponding pins. The overmodulation method has the advantages that sector division and vector action time calculation are not needed, so that the overmodulation method is simple to implement, easy to apply to engineering and applicable to overmodulation of any level number converters; accuracy of the overmodulation method is proved by simulation results.

Description

technical field [0001] The invention relates to an overmodulation method for a converter with an arbitrary level number, especially an overmodulation method for an arbitrary level converter based on a carrier wave; it is applicable to the field of photovoltaic power generation grid connection, the field of motor control, and the power system and other converter fields. Background technique [0002] When the converter works at a lower DC voltage or in the field-weakening area of ​​the AC drive system and outputs high torque, the converter is required to have a higher DC voltage utilization rate, and the working state of the converter is also changed from linear to linear. The modulation area enters the over-modulation area. Compared with the linear modulation region, the maximum fundamental voltage amplitude that can be output by the overmodulated multilevel converter can be increased by 9.3%, which can significantly increase the inverter operating range or improve the contr...

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Application Information

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IPC IPC(8): H02M7/48
Inventor 王付胜杨乐王东毅张兴欧阳秋文鹏田龙翔唐瑭
Owner HEFEI UNIV OF TECH
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