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Space vector modulation method for reducing common-mode voltage of non-isolated three-phase quasi-single-stage inverter

A voltage space vector and space vector modulation technology, which is applied to electrical components, output power conversion devices, and AC power input to DC power output, etc., to reduce the amount of common-mode voltage variation, reduce leakage current, and ensure common-mode The effect of constant voltage and frequency

Active Publication Date: 2020-01-10
HOHAI UNIV
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  • Summary
  • Abstract
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  • Application Information

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Problems solved by technology

The literatures "Research on New Non-isolated Three-phase Three-level Photovoltaic Grid-connected Inverter and Its Leakage Current Suppression" and "Flying Capacitor Multi-level Photovoltaic Inverter Common Mode Current Suppression Technology" respectively studied the forward cascading modulation of the carrier method and the carrier reverse cascade modulation method, on this basis a new single carrier modulation strategy is proposed to keep the common-mode voltage constant at half of the DC voltage, but it is not suitable for three-phase quasi-single-stage inverters

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  • Space vector modulation method for reducing common-mode voltage of non-isolated three-phase quasi-single-stage inverter
  • Space vector modulation method for reducing common-mode voltage of non-isolated three-phase quasi-single-stage inverter
  • Space vector modulation method for reducing common-mode voltage of non-isolated three-phase quasi-single-stage inverter

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Embodiment Construction

[0043] The technical solutions of the present invention will be described in detail below in conjunction with the accompanying drawings.

[0044] This example is aimed at figure 1 The non-isolated three-phase quasi-single-stage inverter topology shown. In the figure, S 1 , S 2 , S La1 , S La2 , S Lb1 , S Lb2 , S Lc1 , S Lc2 , S Ha , S Hb , S Hc , S Za , S Zb and S Zc is the power switch tube, L 1 , L a , L b and L c is the inductance, C L and C H for the capacitance.

[0045] Voltage space vector available state quantity (St a ,St b ,St c ) to represent, let the switch state quantity St of each phase x The expression of is as follows:

[0046]

[0047]Among them, x=a, b, c, means a, b, c three-phase, v xn Indicates the midpoint voltage of each phase of the bridge arm of the non-isolated three-phase quasi-single-stage inverter, V H Indicates the high-voltage DC port voltage of the non-isolated three-phase quasi-single-stage inverter, V L Indicates...

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Abstract

The invention discloses a space vector modulation method for reducing common-mode voltage of a non-isolated three-phase quasi-single-stage inverter. In the process of synthesizing the output voltage space vector of the inverter, when the input voltage is smaller than the power grid line voltage peak value, zero vectors, positive small vectors, medium vectors and large vectors are used for synthesizing reference vectors, the zero vectors (0, 0, 0) are replaced with (1, 1, 1), and the positive small vectors (1, 0, 0), (0, 1, 0) and (0, 0, 1) with common-mode voltage mode lengths of VL / 3 are discarded; when the input voltage is greater than or equal to the power grid line voltage peak value, a zero vector is discarded, and a reference vector is synthesized only by using adjacent small vectors; and the reference vector is used as an output voltage space vector of the inverter. Thus, the common-mode voltage variation is reduced, and the common-mode voltage frequency is ensured to be unchanged, so that the leakage current is reduced.

Description

technical field [0001] The invention belongs to the technical field of inverters, and in particular relates to a space vector modulation method for common-mode voltage of three-phase inverters. Background technique [0002] The inverter is a device that uses power tube devices to convert DC power into AC power for AC loads. In photovoltaic power generation grid-connected systems, three-phase three-level inverters are widely used due to their advantages such as small current harmonics, small filter volume, and low device voltage stress. The output voltage of photovoltaic panels is usually between 200-1000V, so a booster circuit is usually added in the front stage of the inverter. In a traditional two-stage three-phase inverter, power is converted and transmitted in two stages. In order to reduce the number of power conversion stages, a non-isolated three-phase quasi-single-stage inverter topology was proposed in the document "Modified SVPWM-Controlled Three-Port Three-Phase...

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Application Information

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IPC IPC(8): H02M7/5387H02M1/12
CPCH02M1/12H02M7/53871H02M1/123
Inventor 张犁张涛马天睿雷峥子吴峰王楚扬
Owner HOHAI UNIV