Bidirectional DC-DC Converter For Modeling,Modulation And Power Optimization Research And Design

In the context of the development of global energy interconnection,power electronic equipment has been developed to a certain extent.The energy converter is proposed to solve the problems of power transmission and fault isolation of distributed energy storage elements.As a key component of the energy converter,whether the bidirectional DC converter can operate safely and reliably is related to the safety of the entire system.This paper mainly researches and designs the modeling,modulation and power optimization of bidirectional DC converter.This paper mainly studies the topology of the bidirectional DC converter,analyzes the converter’s operation mode under the direction control,and analyzes the working principle and power flow process of the PWM+(Pulse Width Modulation)single phase-shift control method in detail.Then it introduces the double and triple phase-shift control.The system analyzes the effect of multiple phase-shift control of phase-shift angle on the system voltage and current,and to and analyze the relationship between the phase of the voltage and current and the phase-shift angle under the FFT transform.The study of traditional DC converter only gives energy flow diagram of the system.In this paper,a differential model of the bidirectional DC converter is established under the fundamental wave equivalent circuit of the topology.The fundamental wave equivalent principle is used to equivalently convert a square wave into a sine wave.Because the single-phase sine waveform is essentially different from the three-phase sine waveform,an SVPWM(Space Vector Pulse Width Modulation)modulation method applied to a bidirectional DC-DC converter is proposed.The SVPWM modulation algorithm can reduce the switching frequency loss at the same switching frequency,and solve the thermal power imbalance caused by the excessive use of the switching tube in the single-cycle switching process.SVPWM modulation can improve the utilization of the DC power of the full-bridge circuit,effectively increase the output voltage on the secondary side of the full-bridge circuit,and enable the ZVS(Zero Voltage Switch)turn on and off of some switching tubes at the same time,which can effectively reduce the switching losses of the switching tube.A power optimization control method for the established mathematical differential model is proposed to improve the power transmission efficiency from the primary side to the secondary side.This method simulates a sine wave with the principle of impulse equivalence in the inertial link.The high-frequency voltage and current waveforms are equivalent to a sine wave.Through vector control of the sine wave,the ideal voltage and current output can be achieved,and the voltage utilization rate can be improved.Based on this,a method of maximum power output control is proposed.The process of power transmission in the system is obtained by systematically deriving the power equation of the DC converter.Experiments verify the soft switching problem of DC converters.Finally,a two-way converter simulation model was built in PLECS,and the software and hardware of the two-way converter prototype were designed and selected.For the DC-DC stage,including the selection of DC capacitors and power switching devices on both sides,the design of power inductors and high-frequency transformers,system control part,complete the software and hardware design of the control system with DSP and CPLD as the core.Finally,a two-way converter simulation model was built in PLECS,and the software and hardware of the two-way converter prototype were designed and selected.For the DC-DC stage,including the selection of DC capacitors and power switching devices on both sides,the design of power inductors and high-frequency transformers,system control part,complete the software and hardware design of the control system with DSP and CPLD as the core.Simulation and experimental results show that the control system has good dynamic response and steady-state accuracy.It proves that the system has higher practical application value.