Voltage converter and operating method thereof

Abstract

The invention discloses a voltage converter which is used for converting direct-current voltage output by a direct-current power supply into alternating voltage provided for an alternating-current load. The voltage converter comprises a bypass unit, a boosted circuit, a first energy-storage filtering unit, a voltage-reduction circuit and an inverter circuit. The boosted circuit, the first energy-storage filtering unit, the voltage-reduction circuit and the inverter circuit are sequentially parallelly connected between the direct-current power supply and the alternating-current load. The bypass unit is used for bypassing the boosted circuit when the direct-current voltage is not smaller than the absolute value of an instantaneous value of the power grid voltage. The inverter circuit actuates at power frequency in each work cycle of the alternating-current voltage. The booster circuit operates only when the direct-current voltage is smaller than the absolute value of instantaneous value of the power grid voltage. Compared with the prior art, the voltage converter is wide in direct-current voltage working range, high in converting efficiency and low in cost.

Description

technical field [0001] The invention belongs to the field of power electronics, and in particular relates to a voltage converter for converting DC voltage into AC voltage and an operating method thereof. Background technique [0002] With the increasing depletion of energy, renewable energy power generation technologies, such as photovoltaic power generation and wind power generation, have received widespread attention, in which the unstable power generated by renewable energy is converted into stable AC power for AC loads or AC power grids. The device is particularly important, and must adapt to various working conditions where the input voltage varies within a wide range, while achieving efficient energy conversion. [0003] As far as photovoltaic inverters are concerned, they can be divided into isolated and non-isolated types. Among them, non-isolated inverters with high efficiency and low cost have received the most attention. Commonly used non-isolated inverters use ...

AI Technical Summary

Problems solved by technology

Commonly used non-isolated inverters use the front-stage DC / DC boost circuit to adjust the DC voltage, and the rear-stage full-bridge circuit to realize the inverter. Both the front and rear circuits work at high frequency, and the switching loss is relatively high. , the conversion efficiency is low; moreover, the switching devices of the front and rear two-stage circuits need to use high-speed switching tubes, and the cost is high

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