Design Of Half-Bridge Three-Level ZVS DC Converter

With the rapid development of modern power electronics technology,switching power supply to higher frequency,more reliable,lower power consumption and modular direction,especially the improvement of device loss.High-frequency switching power supply will inevitably change the traditional PWM switching technology.In order to improve the efficiency of switching power supply,the realization of ZVS and ZCS soft-switching technology has become the mainstream of switching power supply research in recent years.The three-level topology studied in this paper is developed from the two-level topology.It has many advantages in performance.The greatest advantage is that it can reduce the voltage stress of each switch and reduce the harmonics in the circuit.Therefore,it is more suitable for the case of high input voltage.Compared with the traditional circuit series-parallel method,it can be greatly improved.Reduce volume and weight.However,the three-level neutral point potential also has the inherent shortcomings of unbalanced,so it should be fully considered to eliminate the effect of neutral point offset in the control.This paper combines soft-switching technology with three-level technology,which can not only widen the input range of voltage,increase the power of DC converter,but also reduce the switching loss to the minimum,greatly improve the reliability of the circuit and reduce the cost of the converter.Firstly,this paper introduces the topology of half-bridge three-level ZVS converter,then analyzes the operating modes of the converter under active bipolarity control,and establishes a model on PSIM simulation software,which is seldom mentioned in the literature.However,the common flying capacitors in the products are discussed,which proves that there is no flying capacitor as well.Can achieve ZVS.Then the control method of the circuit is analyzed,and the finite bipolarity control method is compared with the phase shift control method.Then the output characteristics of the analog circuit are analyzed under the conditions of light load,full load and unbalanced input.The design goal of this paper is 100 kHz and the output power is 4 kW half-bridge three-level ZVS high-power supply.The hardware design is completed on the basis of PSIM simulation,including the selection of main power circuit components,minimum system design,sampling circuit design,over-current protection circuit design,PWM drive circuit design and DSP TMS320F28069 as the core.The control circuit design of the heart.The rationality of the selection is verified by the simulation data.Finally,the experimental results are compared with the simulation structure to verify the correctness of the analysis and design method.