Grid-connected control method of z-source inverter based on single cycle and double current loop control

Abstract

The invention relates to a Z-source inverter grid-connected control method based on single-cycle and double current loop control. LCL is used to filter the grid-connected current, and the grid-connected current loop and capacitor current loop are used for double-loop control, which can effectively suppress The resonance peak of the LCL filter is reduced, and the adverse effect of the resonance peak on the Z-source inverter grid-connected system is reduced. The outer loop of grid-connected current adopts PI controller, and the inner loop of capacitive current adopts P controller, which increases the stability of the system and improves the control accuracy of the system; single-cycle control is used instead of traditional PWM control for Z-source inverter The control of the switch can effectively suppress high-order harmonics; the proposed Z-source inverter grid-connected control scheme with single-cycle control and double current loop control can effectively suppress the influence of the resonance peak value of the LCL filter on system stability. The stability of the system is improved, and the harmonic distortion rate of the grid-connected current is effectively reduced, and the quality of the grid-connected electric energy is greatly improved.

Description

technical field [0001] The invention relates to an inverter control technology, in particular to a grid-connected control method of a Z-source inverter based on single-cycle and double-current loop control. Background technique [0002] With the development of industry, the energy crisis has become more and more prominent. The pollution caused by traditional fossil energy and its own depletion problem are inevitable. Humans pay more attention to clean and renewable new energy such as wind energy and solar energy. In order to improve the conversion efficiency of electric energy, inverter control technology is one of the extremely important technologies in the process of connecting new energy to the grid. [0003] The inherent characteristics of traditional voltage-based inverters limit it to only step-down, but not step-up. To realize the buck-boost conversion, additional circuits must be added, which increases the cost and reduces the power conversion efficiency. The Z-sour...

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Problems solved by technology

[0004] The present invention aims at the problems of traditional voltage / current type inverters that can only step down / boost voltage and poor output power quality, and proposes a grid-connected Z-source inverter based on single-cycle and double-current loop control The control method adopts the Z-source inverter to convert DC to AC. Since the Z-source inverter allows the addition of the through signal and cancels the addition of the dead time, the inverter can realize the conversion of buck-boost and improve the efficiency. quality of electrical energy conversion

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