Research On Backstepping Control Strategy Of Voltage Source Inverter

Voltage source inverters are widely used in photovoltaic power generation,safe backup power(UPS)and industrial automation fields.Due to the higher and higher requirements for the characteristics of industrial inverters,the traditional linear control strategy is difficult to meet the requirements for such a time-varying nonlinear system as the inverter.Therefore,the study of reasonable and effective control algorithms is of great significance to its high-performance applications in industrial situations.This paper takes the voltage source inverter as the control object and studies its backstepping control method.The main contents are as follows:Firstly,the state-space averaging method is used to unify the state equations of different topologies in one switching cycle of the inverter,and establish the dynamic mathematical model of single-phase and three-phase voltage source inverters.For the LC filter parameters’ appearing in the model of inverter,according to the power factor of the system and the power factor constraints of the load,the theoretical basis for optimizing the filter parameters is given,lay a theoretical foundation for subsequent control strategy research.Secondly,according to the design idea of backstepping control,combining virtual control and Lyapunov function selection,the backstepping design steps of MIMO(Multiple Input Multiple Output)system are discussed,and the control vector of MIMO system with strict parameter feedback form’s Mathematical expressions is given.This method is applied to the nonlinear system of a three-phase voltage inverter,and its backstepping control mathematical model is established.In order to overcome the limitation of load property parameters in the backstepping control model,a mathematical model for wide-load backstepping control of a single-phase voltage source inverter was established to make the control algorithm universal.And use DSP28335 microprocessor as the controller,intelligent power module IPM(Intelligent Power Modules)as the main power device,AD7656 as the signal processing chip,etc.to form a three-phase voltage inverter closed-loop automatic control system,through the disturbance experiment Wait to verify the rationality of the theoretical design.Finally,due to the strong dependence of backstepping control on system parameters,it cannot guarantee the better control performance of the system under internal and external disturbance conditions.The sliding mode variable structure control strategy has characteristics of low mathematical model dependence and strong robustness.Therefore,combining the two,a backstepping sliding mode control model of the second-order MIMO system is proposed,and this method is applied to a three-phase voltage inverter system,and its backstepping sliding mode control model is established.Finally,the rationality of the design method is verified through simulation experiments.