Analysis Of Sliding Mode Control In Peak Current Mode PFC Boost Converters

In recent years,power converters are widely used in electric power,transportation,aerospace and other industries.Because of nonlinear electronic devices,such as inductance,capacitance,switch,and other nonlinear components,the converter system appears strong nonlinear phenomena.In the PFC Boost converters,power frequency and switching frequency co-existing results in two kinds of bifurcation phenomena,fast scale bifurcations and slow scale bifurcation.In order to suppress the two bifurcations,on one hand,high performance switching devices are selected for the circuit and the circuits are optimized.On the other hand,appropriate control strategy is adopted to avoid the nonlinear phenomena in PFC Boost converter.Although the traditional slope compensation control can effectively restrain the bifurcation,but it often leads to the dead zone of the inductor current,which reduces the PF value of the input current.According to the fast time scale bifurcation phenomenon in PFC boost converter,the bifurcation condition of the system is derived by using the Jacobian matrix in this paper.Based on experiments and simulation,the intermittent bifurcation and chaos phenomena in the power frequency period of 1/2 under the condition of traditional slope compensation are studied.Two methods are applied in the control of PFC Boost converter.One is the integral sliding mode control method,the voltage outer loop PI control is combined with the sliding mode variable structure current loop to suppress the bifurcation phenomenon effectively,and solve the dead zone phenomenon.Another improvement lies in the current loop,double integral sliding mode current loop control is used to increase the order of the controller,which improves the stability of the system and achieves higher power factors.Simulation results show that without adding external compensation,the sliding mode control can solve the bifurcation phenomenon effectively,obtain a higher PF value at the same time,make up for the shortcomings of traditional slope and avoid dead zone to make the system work stably in a single cycle.