Two-stage three-phase four-bridge-arm inverter system with BOOST and control strategy thereof

Abstract

The invention discloses a two-stage three-phase four-bridge-arm inverter system with BOOST and a control strategy thereof. The system comprises a BOOST DC-DC converter, a three-phase four-bridge-arm inverter, an LC filter, a sampling unit, a load unit, and a control chip. Direct current power supply passes through the BOOST DC-DC converter and direct current bus voltage is provided for the three-phase four-bridge-arm inverter. After the inversion of the direct current bus voltage by the three-phase four-bridge-arm inverter, the direct current bus voltage is filtered by the LC filter and then is connected to the load unit. A sampling signal obtained by the sampling unit goes through the filter and then is inputted into the control chip for processing. The control chip outputs an MOSFET driving signal, the MOSFET driving signal passes through an optocoupler isolation circuit and a MOSFET driving circuit and then is connected to the BOOST DC-DC converter and the three-phase four-bridge-arm inverter. According to the system and the control strategy, sequence component separation control based on three-dimensional space vector pulse width modulation technology is used, the symmetry of output voltage waveforms can be ensured by each harmonic compensation control, and problems of asymmetry and distortion of voltage waveforms in an asymmetric load and a nonlinear load are solved.

Description

technical field [0001] The invention belongs to the field of power electronic converters, and relates to a widely used two-stage three-phase four-arm inverter system with BOOST boost, in particular to a two-stage three-phase four-arm inverter system with BOOST boost Change system and control strategy. Background technique [0002] The excessive use of fossil energy has brought a series of energy problems: environmental pollution, energy shortage, and the utilization of new and clean energy has received more and more attention, among which solar energy is the most widely used. At present, the DC voltage that solar photovoltaic panels can provide is low, and the voltage value varies with the output power, which is very unstable. Therefore, measures need to be taken to meet the stable and high voltage DC bus voltage required by the inverter. [0003] Since the balance of the three-phase voltage is a very important indicator for measuring the power quality, the load on the actu...

AI Technical Summary

Problems solved by technology

The Chinese patent with the authorized announcement number CN103812375B realizes the independent control of A, B, C three-phase voltage and neutral point voltage through three control strategies of fundamental wave proportional resonance, repetitive control and pure proportional control, and improves the output under asymmetrical load Voltage balance, but the control steps of this method are cumbersome, the actual operation is difficult, the calculation time of the existing controller is long, and it is difficult to suppress the harmonics under the nonlinear load within one control cycle

[0005] To sum up, most of the existing studies on three-phase system loads are linear and asymmetrical loads. There are few studies on nonlinear loads and the control strategy is complex, which is difficult to implement. For two-stage booster with BOOST There is no report on the three-phase four-leg inverter system, so it is necessary to study the requirements of ensuring the stability of the DC bus voltage and high voltage value of the inverter stage under the condition of low and unstable DC voltage, and the linear asymmetry, asymmetric Guaranteed three-phase output voltage balance and sinusoidal under linear load

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