Research On Three-port Converter With Pulse Load And Its Control Strategy

With the rapid development of power electronics technology in military industry and civil field,more and more equipment loads take the form of pulse state.Pulse load generally presents the characteristics of wide frequency band and pulse variation,which puts forward higher requirements for the stability of power supply system.When the power supply system is a limited capacity system,its own regulation is difficult to respond to the change of pulse load power in a timely manner,so that the power supply system will produce voltage and current fluctuation is too large,affecting the stability of the power supply system.By taking advantage of the characteristics of capacitor's quick charge and discharge,the excess power is stored in the capacitor in light load,and the insufficient power is replenished in heavy load,so as to balance the instantaneous power difference between input and output and solve the problem of power supply adaptability.In this paper,a bidirectional converter is connected in parallel between the front-stage power supply and the pulse load.The other port of the converter is connected to the energy storage capacitor.This paper adopts the traditional Buck/Boost bidirectional converter.The working mode of the converter is analyzed,and an adaptive current feedback control strategy based on the detection of capacitor voltage valley value is proposed.In addition,in order to ensure the normal operation of the converter,it is necessary to ensure that the terminal voltage of the energy storage capacitor is always higher than the output voltage of the front-stage power supply system.Therefore,on the basis of the adaptive current feedback,the capacitor voltage valley value detection ring is added.When the capacitor voltage valley value is lower than the reference value of the voltage loop,the valley value voltage ring is involved in the work to raise the capacitor voltage to the reference value and ensure that the converter can work normally at any pulse frequency and duty cycle.in order to solve the problem of current spike in front output current caused by non-mutation of inductor current,a three-state two-inductor bidirectional converter was proposed.By adjusting the working mode of three-state two-inductor bidirectional converter according to pulse load characteristics,the problem of current spike could be eliminated.Finally,the proposed scheme is verified by building a simulation model and making an experimental prototype.The simulation and experimental results verify that the problem of instantaneous power difference between the front stage output and the pulse load can be solved by adding a bidirectional converter and utilizing the charge-discharge characteristics of capacitor.The adaptive current feedback control strategy based on capacitor voltage valley detection can automatically adjust with the change of pulse load frequency and load duty ratio to achieve the adaptive tracking effect.The proposed three-state two-inductor bidirectional converter can eliminate the problem that the front-stage output current has a current peak because the inductor current cannot be mutated.