Research And Design Of High Power Low Frequency Transmitter Power Parallel System Supply Based On Digital Current Sharing

Low frequency electromagnetic communication technology is an important technical means of submarine communication.Submarine communication distance,communication depth and communication accuracy are important development directions in low frequency electromagnetic communication.Megawatt high-precision high-power power supply as energy supply in the system is the key to ensure this index.The high-power power supply developed in this dissertation uses multiple power modules in parallel to achieve high-power output,each module equalizes the current output to balance the thermal stress,and when a module fails,it can be quickly and automatically isolated to ensure the normal operation of the whole system.The power module used in this dissertation is composed of a front-end three-phase rectifier and a back-end DC-DC converter.The DC-DC converter researched in this dissertation is directly connected to the load after being connected in parallel in the system,which is the key part of the power system to achieve multi module parallel current sharing.The zero voltage switching technology of the converter is also the key to improve the power efficiency.Based on the topology of half bridge three-level converter,this dissertation designs a modular parallel system with good steady-state and dynamic performance based on digital current sharing.This dissertation first describes the main circuit principle of the half bridge three-level converter,through the analysis of the switch control strategy,selects the phase-shift control method to realize the zero voltage switching of the converter,and analyzes the switching mode principle in the working cycle of the converter,and discusses the feasibility of realizing the zero voltage switching combined with practical problems.The small signal model of the half bridge three-level converter is built by the state space average method.After the main circuit parameters of the converter are designed,matlab simulation is built based on the voltage and current double closed-loop control strategy to verify the zero voltage switching condition and the dynamic response speed of the double closed-loop control of the converter.In the parallel power supply system,in order to balance the output current of each power module,balance the thermal stress of each module and improve the operation reliability,it is necessary to adopt appropriate current sharing measures.Through the analysis of the analog current sharing method,combined with the characteristics of the digital current sharing method,based on the idea of the digital current sharing method of the average current method,the three loop control method of adding the current sharing loop on the basis of the double closed loop control is adopted,Combined with the small signal model of the converter,the three loop control model of the parallel system is given,and the performance of the double closed-loop and three loop control strategies is verified by building the parallel system in MATLAB,which verifies that the three loop control system can effectively realize the current sharing between modules and improve the response speed of the system.In this dissertation,the domestic jdspf28335 digital controller chip is used as the main control chip,and the built-in ECAN module is used to realize the can communication between modules in the system to complete the current sharing control of the system,and the relevant software programs and key hardware circuits are designed.According to the design,an experimental platform is built to verify the current sharing effect,and the experimental waveform and performance test results of the experimental prototype are given,which achieves good current sharing effect.