Control method applied to active-clamp flyback miniature photovoltaic grid-connected inverter device

Abstract

The invention relates to a control method which can be applied to an active-clamp flyback miniature photovoltaic grid-connected inverter device. The active-clamp flyback miniature photovoltaic grid-connected inverter device comprises a flyback converter and a power frequency polarity conversion circuit. In the device, a current reference is used for controlling a flyback primary-side current peak value so that the device can output a half-wave sinusoidal current, and the output voltage is clamped by a grid voltage. When the instantaneous power is lower, a constant frequency current discontinuous mode in combined with a variable frequency current critical continuous mode is adopted in the flyback control method. When the flyback converter works in a variable frequency current critical discontinuous mode, an auxiliary switching tube can be conducted for a period of time when the secondary-side current of the flyback converter reaches zero, the conduction time can be accurately controlled by a digital chip, thus realizing the leakage inductance energy feedback and the soft switch of a master switching tube under the condition of wide-range output voltages and different instantaneous powers and greatly improving the efficiency under the condition of full loads.

Description

technical field [0001] The present invention is a control method applied to an active clamp flyback miniature photovoltaic grid-connected inverter device Background technique [0002] For photovoltaic power generation systems, there are two potential markets: megawatt-level large-scale photovoltaic power plants and small-scale building and household photovoltaic power generation systems. Micro photovoltaic grid-connected inverters have broad application prospects in the latter. [0003] The main factors affecting the efficiency of the micro photovoltaic grid-connected inverter using flyback topology on the DC side are the leakage inductance of the transformer and the loss of the main switching tube, so further optimization of the two is required. [0004] To deal with the leakage inductance energy of the transformer, passive snubber circuits and active snubber circuits can be used. For passive snubber circuits, such as RCD snubber circuits or LC snubber circuits, when the f...

AI Technical Summary

Problems solved by technology

In this case, it is difficult for the clamping circuit controlled by analog to achieve the desired effect.

Images