High-efficiency Hybrid Soft-Switching Inversion Technique Based On Hysteresis Current Control

At present,China's wind power installed capacity and PV installed capacity continue to rank the first in the world after 2017.In the past few decades,the rapid development of the economy has not only brought about rapid construction of industry and the improvement of people's lives,but also brought about a series of negative effects such as deterioration of the ecological environment and depletion of energy.In terms of power usage,in order to achieve the goal of sustainable development and green development,new energy generation based on distributed energy technology will inevitably occupy an increasing proportion of the entire energy production.As a hub connecting distributed power and large power grids,the development and application of the inverters will play a vital role in this energy revolutionAs an energy conversion unit,inverters are widely used in microgrids,industrial control systems and other power supply systems.The topological characteristics and control perfonnance of the inverter determine whether the entire energy conversion system can be more efficient,whether it can have higher power density and lower cost.This paper synthesizes the research status of grid-connected micro-inverters.Based on the theoretical and mathematical models of the system's efficient control method for inverters,a set of single-phase inverter control strategy based on principle analysis,simulation construction and circuit design is proposed.In order to verify the effectiveness of the control strategy,a new hybrid soft-switching current control scheme for inverter is built.The experimental implementation and efficiency analysis of the proposed control scheme is carried out with a fully digitally-controlled full-bridge inverter hardware experimental platform.This paper summarizes the design steps of LC filter for the problem of filter design under hysteresis control.The mathematical relationship between hysteresis width and output THD is established by simulation experiments,which is convenient for the design of hysteresis width in hysteresis control.Firs tly,after comparing many analog and digital control methods of the inverter,the paper introduces the working principle and control characteristics of the real-time control method of hysteresis control.The optimization process from the traditional hysteresis current control method to hysteresis boundary control modulation(BC M)is analyzed.The mathematical models of three different boundary current control methods are established.The frequency variation characteristics and conduction loss characteristics of three different methods are analyzed.Based on the advantages of the zero-voltage soft-switching of the traditional boundary control method,a mathematical model of the mixed zero-current zero-voltage control strategy is established.This method combines two different soft-switching modes to preserve the soft-switching environment.On the basis of the above,the problems of high on-state current value and large frequency variation range existing in the traditional boundary control efficiency are optimized,the efficiency of the inverter system is improved,and the operating frequency range of the switch tube is reduced.The problem of possible dead band influence on the output voltage in PWM current modulation is analyzed and optimized.The double closed-loop control scheme of the inverter with the hybrid soft-switch current control mode as die inner loop is established,and the scheme is verified by si,mulation.The article introduces the design process of the new inverter system.In the aspect of hardware circuit,the article introduces the design process and parameter selection of some important hardware circuit.In terms of software design,the system uses an all-digital y-controlled method based on DSP TMS320F28035Finally,on the established full-digitally-controlled full-bridge inverter platform,the traditional boundary current modulation methods and the new hybrid control method are compared experimentally to prove that the experimental waveform output is ideal.The four different modulation methods are compared and analyzed in terms of working efficiency,on-state inductor current,and frequency range.It turns out that the new strategy can improve the efficiency of the inverter and optimize other functional parameters.The digital control strategy adopted does not need additional auxiliary circuit and has the advantages of simple control,convenient algorithm modification.The cost of inverter production is reduced.