Modulation method of three-phase Z-source neutral point clamped multi-level photovoltaic inverter

A technology of photovoltaic inverter and modulation method, which is applied in photovoltaic power generation, electrical components, and conversion of AC power input to DC power output, etc. It can solve the problems of complex implementation and large amount of calculation, and achieve system leakage current suppression and common mode The effect of constant voltage and simple structure

Active Publication Date: 2013-04-17
华夏天信智能物联股份有限公司
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  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

The first modulation method needs to judge the sector, calculate the vector action time and vector sequence distribution and other links, the amount of calculation is large, and the realization is more complicated; the second modulation method also needs to judge the sector, and then realize it through multi-carrier modulation and other links. also more complex

Method used

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  • Modulation method of three-phase Z-source neutral point clamped multi-level photovoltaic inverter
  • Modulation method of three-phase Z-source neutral point clamped multi-level photovoltaic inverter
  • Modulation method of three-phase Z-source neutral point clamped multi-level photovoltaic inverter

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Embodiment Construction

[0028] The present invention will be described in further detail below in conjunction with the accompanying drawings and specific embodiments.

[0029] (1) figure 1 is the circuit schematic diagram of the three-phase Z-source midpoint clamped three-level photovoltaic inverter, figure 2 The switching signal generation logic circuit proposed for the present invention. Initial modulating wave Get their phase-to-phase signals, that is, line-to-line voltage signals Then multiply by the coefficient K to get

[0030] (2) by The zero-sequence signal v is obtained by the zero-sequence signal calculation unit 0 ;

[0031] (3) Will Respectively with the zero sequence signal v 0 Adding to get the final modulated wave

[0032] (4) by modulating wave respectively with the triangular carrier V C The logic signal S is obtained through comparator 1, comparator 2 and comparator 3 a , S b , S c ;

[0033] (5) The logic signal S a , S b , S c The simple logic circuit s...

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Abstract

The invention discloses a modulation method of a three-phase Z-source neutral point clamped multi-level photovoltaic inverter. The method comprises the following steps of: obtaining line voltage signals Vac*, Vba* and Vcb* through initial modulating waves Va*, Vb* and Vc* and multiplying by a coefficient K respectively; obtaining a zero sequence signal v0 through a zero sequence signal calculating unit; adding zero-sequence signal with KVac*, KVba* and KVcb* to obtain final modulating waves Va**, Vb**, and Vc**, and comparing the modulating waves Va**, Vb** and Vc** with a carrier wave to obtain logical signals Sa, Sb and Sc; comparing the carrier wave with VH and VL to obtain a through connect signal ST; and making the logical signals Sa, Sb and Sc and the through connect signal ST pass through a logic circuit to obtain a switching signal. The invention has the beneficial effects that a single-carrier-wave modulation method is provided, so that the problem of excessive complexity in realizing the conventional multi-carrier-wave modulation and space vector modulation is solved; and meanwhile, the common-mode voltage of a system is kept constant, so that the drain current of the system is effectively restrained. A switching signal generating circuit is simple in structure, and can be realized by adopting an analog circuit as well as a digital circuit.

Description

technical field [0001] The invention relates to a modulation method for a three-phase Z-source midpoint clamp multilevel photovoltaic inverter. Background technique [0002] Compared with the traditional two-level inverter, the neutral-point clamped multi-level inverter has the advantages of lower requirements on the withstand voltage level of switching devices and less harmonic content in the output waveform, and has been applied in photovoltaic power generation systems. Due to the low rated output voltage of photovoltaic cells, it is usually necessary to connect multiple photovoltaic cell panels in series to obtain the required voltage level, resulting in an increase in the cost of the photovoltaic power generation system. In order to solve this problem, a Z-source boost network can be added to the front end of the inverter to form a three-phase Z-source midpoint clamped multilevel photovoltaic inverter. Due to the parasitic capacitance between the photovoltaic system and...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H02M7/483H02M7/5387H02M1/08
CPCY02E10/56
Inventor 郭小强魏宝泽
Owner 华夏天信智能物联股份有限公司
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