Research On Current Sharing Technology Of Interleaved Parallel Bidirectional DC-DC Converters

High-power bidirectional DC-DC converters are widely used in new energy power generation and new energy vehicles,among which converters based on interleaved parallel technology are more favored by users.The interleaved parallel technology can greatly reduce the output current ripple of the converter and the current stress of each phase,and has important engineering value for improving the output power quality,reducing the design cost,and improving the steady state and dynamic performance of the circuit.However,due to the unequal parasitic parameters of each phase,it is easy to make the phase currents unbalanced,resulting in reduced reliability and shortened service life of the converter.Therefore,the study of multi-phase interleaved parallel converters and their current sharing control strategies has important practical significance.First of all,this article selects three-phase interleaved parallel bidirectional DC-DC converter as the research object.The working mode and inductor current waveform under the two modes are analyzed in detail,and the relationship between output current ripple and single-phase inductor current ripple and duty cycle,and the relationship between output voltage ripple and single-phase output voltage ripple and duty cycle is given.Expression,and use MATLAB to make a graph,vividly analyze the advantages brought by the staggered parallel technology.Secondly,through Thevenin’s equivalent theorem,the equivalent circuits of the two converter modes are established,and the relationship between phase current and parasitic parameters,duty cycle,and other phase currents is analyzed.Aiming at the problems of low power density,high cost and complex control loop design due to the excessive number of sensors in the current sharing control of multi-phase interleaved parallel DC converters,a single current sensor current sharing is proposed using the principle of active current sharing Control Strategy.The concept of reconstructed phase current and reconstruction deviation is given.According to KCL,the relationship between the reconstructed phase current and the average value of the phase current is explored to achieve the purpose of obtaining accurate phase current for a single sensor,and use its phase current difference value for duty cycle compensation.,In order to realize the phase current balance.Then,the two modes of the converter are established through small signal disturbance,and the voltage loop is corrected by the type III compensation network to achieve the control target.The design block diagram of the duty cycle compensation module is given,the integral separation method is introduced to optimize the dynamic and steady-state performance of the control system,and the correctness of the control of the converter working under full duty is verified through simulation.Finally,a 10 kW experimental prototype was built,and the discrete control model built in Simulink was burned into the DSP using code generation to form a closed-loop control loop.The necessary steady-state and dynamic experiments were performed on the two modes of the converter to further verify the contents of this article.Improve the correctness and feasibility of the control strategy.