Grid-connected seamless switching controller based on capacitive current inner ring and control method thereof

Abstract

The invention discloses a grid-connected seamless switching controller based on a capacitive current inner ring and a control method thereof. The controller comprises a microcontroller, a voltage sampling circuit, a grid-connected switch driving circuit and an inverter power tube driving circuit, wherein the microcontroller comprises an electricity grid synchronous module, an output voltage controller, a capacitive reference current generator under a grid-connected mode, a grid inlet current controller, a capacitive current controller, a control command selecting switch and an inverter power tube logic generator. The grid-connected seamless switching controller is connected with an inverter of an electricity grid through a grid-connected switch, is in an output voltage control mode when in dependent operation with load and is in a grid inlet current control mode when in grid-connected operation. The grid-connected seamless switching controller is adaptable to a grid-connected invertercapable of independently operating with grid-connected double modes, increases output voltage load adjustment rate under an independent mode, increases power factors and grid inlet current waveform quality on the condition of non-linear load and electricity grid voltage distortion under a grid-connected mode, and then realizes seamless switching of two work modes.

Description

technical field [0001] The invention relates to a control method of a grid-connected inverter capable of independent and grid-connected dual-mode operation, in particular to a grid-connected seamless switching controller and a control method thereof based on a capacitive current inner loop. Background technique [0002] With the continuous shortage of fossil energy and the increasing environmental pollution, the distributed generation system based on renewable energy has become a research hotspot, and the grid-connected inverter is an important part of it. In order to provide uninterrupted power supply for critical loads, grid-connected inverters with critical loads are required to work in both grid-connected and independent modes. In grid-connected mode, the excess energy is supplied to the grid while supplying power to key loads; in independent mode, power is supplied to key loads. However, when the key load is a nonlinear load, the traditional grid-connected control meth...

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