Control method for PI (power to loop) resonance of photovoltaic grid-connected inverter based on switching of CCM (continuous current mode) and DCM (discontinuous current mode)

Abstract

The invention relates to a control method for PI (power to loop) resonance of a photovoltaic grid-connected inverter based on switching of CCM (continuous current mode) and DCM (discontinuous current mode). When the absolute value of grid-connected voltage Vo outputted by the photovoltaic inverter is higher than or equal to boundary voltage Vbo, the CCM control method is adopted; when the absolute value of the grid-connected voltage Vo outputted by the photovoltaic inverter is lower than the boundary voltage Vbo, the DCM control method is adopted. Under different working modes, the occupation space ratio of an alternating current small signal is adjusted by a PI resonance controller, so as to obtain the total occupation space ratio. According to the total occupation space ratio, the corresponding PWM (pulse width modulation) wave is generated to control the action of a pre-stage MOS (metal oxide semiconductor) tube, so as to enable the photovoltaic inverter to realize grid-connected output. The control method has the advantages that the harmonics of grid-connected current flowing through a zero point can be effectively eliminated, and the grid-connecting efficiency and grid-connecting quality of the inverter are improved.

Description

technical field [0001] The invention belongs to the field of new energy electronic control, in particular to a PI resonance control method of a photovoltaic grid-connected inverter. Background technique [0002] Grid-connected current control technology mainly includes traditional control technology and control technology based on modern control theory. Among them, the traditional grid-connected current control technologies mainly include PI control, hysteresis control, repetitive control, predictive current control, and single-cycle control methods. The grid-connected current control technologies based on modern control theory mainly include fuzzy control, sliding mode variable structure control, adaptive control and so on. For the existing micro-inverter products, due to cost considerations, PI controllers with simple algorithm, low implementation cost and good stability are basically used, but there are two problems in PI control: it is difficult to realize the reference...

AI Technical Summary

Problems solved by technology

[0004] In order to overcome the shortcomings of the existing photovoltaic inverter single-mode mode, when the input power is relatively low, the grid-connected efficiency is relatively low, and the harmonics at the zero-crossing point will be relatively large, the present invention provides a method that effectively improves the grid-connected power of the inverter. PI resonance control method of photovoltaic grid-connected inverter based on switching between current continuous mode and current discontinuous mode for efficiency and reduction of harmonics of grid-connected current

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