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Three-Phase Inverter with Wide Input DC Voltage Range

IP.com Disclosure Number: IPCOM000245648D
Publication Date: 2016-Mar-24
Document File: 7 page(s) / 596K

Publishing Venue

The IP.com Prior Art Database

Related People

Carl Ho: AUTHOR [+4]

Abstract

This disclosure presents an inverter to transform direct-current (DC) voltage to three-phase alternative- current (AC) voltage. The inverter consists of four stages (2 + 2 stages) but it can manage wide input dc voltage variation. There is only one power stage which employs high frequency, high voltage and high current semiconductor switching cells, which effectively reduces BOM cost. Besides, the inverter does not require any transformer for grid connection. The performance of the proposed inverter is verified by computer simulation. The results show that the proposed inverter guarantees sinusoidal output current, operates over a wide input voltage range and has a good agreement with the theoretical findings.

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Page 01 of 7

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Three-Phase Inverter with Wide Input DC Voltage Range

Abstract

This disclosure presents an inverter to transform direct-current (DC) voltage to three-phase al- ternative-current (AC) voltage. The inverter consists of four stages (2 + 2 stages) but it can manage wide input dc voltage variation. There is only one power stage which employs high fre- quency, high voltage and high current semiconductor switching cells, which effectively reduces BOM cost. Besides, the inverter does not require any transformer for grid connection. The per- formance of the proposed inverter is verified by computer simulation. The results show that the proposed inverter guarantees sinusoidal output current, operates over a wide input voltage range and has a good agreement with the theoretical findings.

1 Field

The present invention is a three-phase voltage source inverter to convert DC voltage to AC voltage. It is in the field of power electronics converter / inverter circuit topology. The invention is for any inverter applications with transformer-less connection, such as solar energy application.


2 Introduction

The technology of three-phase inverter can be applied to Photovoltaic business, Wind business, Power Quality business and Drive business.

Earlier (Figure 1) it has been demonstrated the operating principle of the inverter showing that the inverter just needs two high current and high frequency semiconductor switching cells. This helps to reduce the BOM cost in the product. Moreover, since the neutral of grid connects to the middle point of the input capacitors, leakage current can be avoided. However, the input voltage range is limited, because the inverter is based on buck conversion technique. For some applica- tions, such as PV inverter, the input voltage can be lower than the peak value of grid voltage, a boosting pre-regulator has to be used to sustain the input voltage of the inverter (Figure 1). This configuration leads to increase BOM cost and system loss in this additional power stage.

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FI-1218301


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Figure 1 Prior system structure for three-phase inverter with wide input voltage range

This invention proposes a single high switching frequency power stage instead of two high switching frequency stages in the inverter. The inverter can operate with a reasonably wide in- put voltage range. This enhanced main power stage consists of only two switching cells, two flying capacitors and two input inductors. The circuit structure and simulated results will be demonstrated in this disclosure.


3 Description


3.1 Statement of problem

In this invention, a converter connected between the DC power source and a three-phase AC grid (or resistive load) is considered.

For example in PV applications, the converter just can manage the input dc voltage from 700V to 850V for the case of 230V output voltage. A pre-regulation (boost) power stage has to be added when the syst...