Research On Predictive Control Of Interleaved Parallel Two-Switch Buck-Boost Converter

The two-switch Buck-Boost converter is widely used in non-isolated wide-range voltage input occasions due to its advantages of low voltage stress and less energy storage components.In order to further improve the power level of the converter,the interleaved parallel technology is applied to the two-switch Buck-Boost converter,which reduces the converter loss and improves the conversion efficiency.However,the interleaved parallel two-switch Buck-Boost converter needs to consider different operations.When the traditional control method is adopted for the mode switching and the current sharing of each phase in each working mode,the controller is generally more complicated.As a new control method,model predictive control is more flexible.Applying it to the interleaved parallel two-switch Buck-Boost converter is more conducive to simplifying the controller structure and improving the performance of the converter.A continuous control set model predictive control method for the interleaved parallel two-switch Buck-Boost converters is proposed.Based on the the current predictive control of each phase,a voltage outer loop controller including predictive model and voltage error is constructed to realize the multi-phase parallel constant voltage and current sharing output under different working modes.First,for the three working modes of the two-switch Buck-Boost converter,the corresponding prediction models are established respectively.To study the influence of the inductor current predictive control under the staggered situation,a method of introducing current compensation coefficients into the predictive model is proposed.The method to obtain the current compensation coefficient under different working modes is given.On this basis,the offline optimal duty cycle expression is obtained by constructing the cost function as the predictive control law,and then real-time online calculation is used to realize the current predictive control.In order to realize the voltage control,the input voltage feedforward is constructed based on the predictive model to realize the fast response of the inductor current when the input voltage changes,and the output voltage error is introduced on the basis of the input voltage feedforward.Combined with the control effect of the two on the inductor current reference,the output voltage off-line predictive control law including current control is given.Thus,the multi-phase parallel constant voltage current sharing output is realized.A four-phase interleaved parallel two-switch Buck-Boost converter is designed.In order to reduce the influence of sampling noise and sampling deviation on the stability of predictive control in the sampling process,the method of using Kalman filter to suppress sampling noise and correct sampling deviation is studied.Based on the standard Kalman filter equation,according to the characteristics of different working modes,the Kalman filter equations under three working modes are given,and the Kalman filter is verified through experiments.Finally,based on the four-phase interleaved parallel two-switch Buck-Boost converter,the current predictive control,voltage predictive control and mode switching experiments are carried out respectively,and the experiments verify the feasibility of the proposed model predictive control strategy.