Research Of Control Strategy Based On Capacitor Charge Balance For The Multi-port Converter

With the increasingly severe energy crisis and environmental pollution,renewable energy generation has attracted more and more attention due to its environmental protection and renewable characteristics.The application of multi-port converters(MPC)in new energy power generation systems can simplify the structure,improve efficiency,and reduce costs.However,it is difficult to design the PI parameters of MPC and MPC can not achieve optimal dynamic performance.Therefore,this paper introduces the charge balance control(CBC)to the MPC to optimize the dynamic performance.The FBFPC is taken as an example to verify the validity of the proposed control strategy.A load step change control algorithm based on capacitor charge balance is proposed.Based on the capacitor charge balance and the relationship between the output voltage and the output inductor current,the ideal waveform of the output inductor current and output voltage are derived.The output inductor current and output voltage can reach the steady state after two stage.By analyzing the change rate of the output inductor current in each switching mode,the optimal switching mode combination is obtained,the capacitor charge balance control of load step is realized.The integrated multi-port converter not only needs to regulate the output voltage,but also needs to distribute the power between different terminal.Since the average value of the output inductor current does not change in power distribution,the CBC scheme for load step changes is no longer applicable.Therefore,a power distribution control algorithm based on capacitor charge balance is proposed,the ideal waveforms of the excitation inductor current,output inductor current and output voltage are derived,the output can reach steady state after output inductor current adjusted three times and the output voltage adjusted twice.The method of capacitor charge balance control can be extended to other DC converter topologies.The model of DC/DC converter and MPC under the control of capacitor charge balance are derived,the algorithm of capacitor charge balance which suitable for general DC converters are proposed and the application of one cycle control and capacitor charge balance control in FB-TPC is compared.Finally,a digital control system based on DSP and a FB-TPC are designed,and the effectiveness and feasibility of this control strategy are verified by comparisons.