| Although the existing current following control strategy possesses high stable precision and fast response speed, its transient performance is not very ideal while the load changes. In order to reduce the dynamic response time and improve the load regulation, a modification based on exsiting current following control strategy is proposed. A control scheme which is the combination of stable state and transient is developed. When the Buck-Boost converter is working in steady state, the existing current following control strategy is used. However, when the converter is working in transient state,both the inductor current and capacitor charge balance should be taken into account. According to the work principle and the differential equations of each stage in the transient state to work out the reasonable time points when switch turns on or off, so it could be controlled more accurately. Therefore, dynamic performance of converter will be improved. In the same time, the boot process of Buck-Boost dc-dc converter is analyzed in detail.The existing and modified model were simulated by the Matlab/Simulink software seperately, the waveforms were received and analysized. An example is given to show the parameter design steps based on STM32F407VGT6. The existing and modified current following control strategies were adopted respectively. Experiments are made on the example. The influence on the output voltage when the input voltage and the load suddenly changes are tested, also the waveforms were received and analysized.Both the simulating result and the experiment result show that the improved current following control strategy effectively solves the problems existing in the current control method before improvement. It improves the performance of transient state. Mainly shortening the dynamic response time and improving the load regulation. It indicates that the proposed approach is feasible and the analysis is correct. Also the converter meets design index. |
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