Abstract

With the increasing importance of power accumulator batteries in electric vehicles, the accurate characteristics of power accumulator batteries have an important role. In order to evaluate the power accumulator battery, battery charging and discharging is indispensable. In this article, a H-bridge bidirectional DC-DC converter is presented which can charge and discharge the battery with different voltage levels and one of the merits of this topology is that a wide output voltage range can be easily achieved. In the control part, a proportional-integral (PI) control strategy is adopted to ensure a stable and reliable operation of the converter. Furthermore, compared with the PI control strategy, a duty ratio feedforward control is utilized to obtain the rapid current dynamic response. In this article, firstly, the system configuration for battery charging and discharging is introduced, then the operating principles and mathematical model of the DC-DC converter are analyzed and derived. Secondly, for bidirectional DC-DC converters, the PI control method and duty ratio feedforward control method are put forward and designed. Finally, the simulation model is established based on PSIM software and the experiment platform is also built in lab. The results of the simulation and experiment research show that the H-bridge bidirectional DC-DC converter can operate reliably and stably during the charging, discharging and power flow reverse modes. In addition, the dynamic response of the charging and discharging current can also be further improved by introducing the duty ratio feedforward control method.

Highlights

  • In recent times, bidirectional DC-DC converters and power accumulator batteries have rapidly enlarged their application areas, such as (i) microgrid systems [1,2,3,4,5], (ii) energy storage systems [6,7], and (iii) electric vehicle (EV) systems [8,9,10]

  • The dynamic response of the charging and discharging current can be further improved by introducing the duty ratio feedforward control method

  • In conventional power accumulator battery charging and discharging processes, a DC power supply can be obtained from the grid by rectifiers and charges the battery through an isolated bidirectional DC-DC converter during the charging mode

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Summary

Introduction

Bidirectional DC-DC converters and power accumulator batteries have rapidly enlarged their application areas, such as (i) microgrid systems [1,2,3,4,5], (ii) energy storage systems [6,7], and (iii) electric vehicle (EV) systems [8,9,10]. One of the drawbacks of this converter is that a wide output voltage range cannot be achieved with a fixed DC bus voltage to charge and discharge the battery at different voltage levels. To solve the aforementioned problems, the literature [28] presents a two-stage DC-DC converter, which is composed of a H-bridge converter and two-phase interleaved buck converter It can obtain a wide output voltage range, but the efficiency is limited. The main contribution of this article is that a wide range output voltage for different battery voltage levels can be obtained by the bidirectional H-bridge DC-DC converter and the duty ratio feedforward control strategy is applied to improve the dynamic response of the output current.

System Structure
System
Operational Principles
Model of the Bidirectional DC-DC Converter
Small-signal
Controller Design of Bidirectional
Simulation Study
LPI I LFFC
LPI response
LPI -50
Experiment Results
Results
Full Text
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