Transformer-free type single-phase photovoltaic inverter with mixed voltage clamping

Abstract

The invention discloses a transformer-free type single-phase photovoltaic inverter with mixed voltage clamping. The transformer-free type single-phase photovoltaic inverter comprises an energy storage voltage dividing unit, a power inversion unit, a mixed clamping unit and a filter unit. When the inverter works, with the help of six diodes, five power switches with antiparallel diodes are cooperated to enable an alternating current side to be continuous and clamp common-mode voltage of the same to be half of direct current input voltage when the inverter outputs zero level, and thereby complete elimination of the common-mode voltage is achieved, and required bus voltage is only half of a half-bridge type circuit. Meanwhile, the transformer-free type single-phase photovoltaic inverter adopts a unipolar pulse width modulation mode, so that output current is small in ripple, volume and weight of a filter are reduced, and loss of a magnetic element is reduced at the same time; the switch operates less frequently in a switching period, so that switching loss is reduced; and therefore, the inverter provided by the invention is high in output efficiency that inversion efficiency up to 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 hybrid 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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