Development Of Power Supply Applied In Power Lithium Battery Equalization Control

Lithium-ion battery has been widely used in various fields,which plays a critical role especially in rail transit field as the power system and energy power system.But in the process of circulation charge and discharge,the single cells in the battery pack will present the inconsistency phenomenon.This is because the low production process and the poor using environment of the battery.The inconsistency of the battery may result in its low capacity and energy utilization,the limited power capacity and even will shorten the lifetime of the battery.In order to solve the above problem,the battery equalization is necessary.There has been exists many methods to balance the battery,the bi-directional DC/DC isolation conversion equalization method has been widely used in practice due to its high precision,fast speed and high efficiency.In this paper,a bi-directional DC/DC converter combined with the actual power parameters of the battery pack is developed on the application background of battery equalization.The specific research content and work are presented as follows:Firstly,select the topology of the bi-directional DC/DC converter.The transformer is divided into high side and low side.The comparison and screening of the two sides,which are rectifier and inverter units,has been given in this paper.The integrated-filter push-pull forward current doubler converter is finally chosen as the topology.And then,analyze the principle of the selected topology,which are mainly including the working principle of the Buck and Boost models of the topology,and introduce the role of the clamp capacitance and the coupling inductor.What's more,the integrated magnetics method is described.Two common modeling methods for magnetic parts are described in this paper,which are "Magnetic Path-Electronic Circuit Dual Transformation Method" and "Magnetic Conductance-Capacitor Analogy Modeling Method".And the analysis method of magnetic named "Source Shifting Equivalent Transformation Method" is introcuced.The steps of magnetic integration whith the inductor of current doubler circuit and transformer is detailedly described.Secondly,the circuit design of isolated bidirectional DC/DC converter is given in this paper,which are including the parameter calculation of the integrated transformer,the calculation of the clamp capacitances in high side and low side,the selection and loss calculation of power switch,the main circuit design,the snubber circuit design,the drive circuit design,the voltage and current detecting circuit design and the soft design of the control circuit.Finally,according to the above analysis and design,the simulation analysis is carried out for the converter after integration;the corresponding experimental platform has been built.Then,the current of the battery charge and discharge has been debugged to satisfy the target parameters of the input and output voltage and current.Finally,the experimental waveforms are measured with oscilloscope,and the experimental results are also analyzed.