Voltage-active-clamping non-transformer-type single-phase photovoltaic inverter

Abstract

The invention discloses a voltage-active-clamping non-transformer-type single-phase photovoltaic inverter which comprises an energy storage voltage dividing unit, a full-bridge inverting unit, an active-clamping unit and a filtering unit. When the inverter works, seven power switches with anti-parallel diodes work in an coordinated-action mode, so that when the inverter outputs the zero level, an alternating side carries out current following, the common-mode voltage is subjected to clamping to reach 1 / 2 of direct-current input voltage, accordingly, the fact that the common-mode voltage is constant in the whole cycle is guaranteed, then complete removing of common-mode current is achieved, and needed bus voltage is only half of a half-bridge type circuit. Meanwhile, unipolarity pulse width modulation is used, output current ripples are small, the size and the weight of a filter are reduced, meanwhile, loss on a magnetic element is lowered, on-off action frequency is low during an on-off cycle, switch loss is lowered, accordingly, the inverter is high in output efficiency, and the inverting efficiency as high as 98% can be obtained.

Description

technical field [0001] The invention belongs to the technical field of power electronics, and in particular relates to a transformerless single-phase photovoltaic inverter with voltage active clamping. Background technique [0002] Nowadays, the problems of energy depletion and environmental pollution are becoming more and more serious, and the development and utilization of various new energy sources are getting more and more attention. Solar energy is currently one of the cleanest and most promising renewable energy sources for large-scale development and utilization, and its photovoltaic utilization has attracted widespread attention from all over the world. Solar photovoltaic power generation is the main development trend of solar photovoltaic utilization, and it will develop more and more rapidly in the future. [0003] As the last or only energy conversion device in the photovoltaic power generation system, the inverter's efficiency and safety performance will directl...

AI Technical Summary

Problems solved by technology

This circuit is similar to the HERIC circuit and cannot completely eliminate the common mode leakage current

In addition, its circuit structure is asymmetrical, and the working hours of the five switching transistors are not equal, resulting in unbalanced heat generation of the switching devices, and high requirements for device heat dissipation design; in the energy transfer stage, three power devices are in the on state (2 in the HERIC topology). ), reducing the overall efficiency of the inverter

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