Wuhan University of Technology

Undergraduate Graduation Design

(Thesis)

Design of New Energy Vehicle Battery Pack

Testing System

School: School of International Education

Specialty amp; Class: Automotive Engineering gj1603

Name: Yu Wang

Tutor: Qizhong Li

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Abstract

The power battery plays a more and more important role in the electric vehicle. For the electric vehicle, the battery is the heart of the vehicle. More in-depth detection and research on the battery can effectively improve the stability and efficiency of the battery work, and further promote the development of the electric vehicle.

The testing of power battery performance is the basis of battery application. With the rapid growth of power battery demand, the demand for power battery testing system is also growing rapidly. At present, most of the testing systems on the market only have a single function, and most of them are under normal temperature environment. Based on the idea of “improvement”, this paper adds a set of high and low temperature testing system for battery pack to the existing test system, which not only meets the needs of battery performance testing at different temperatures, but also meets the needs of the current vehicle factory, and takes the battery pack as the tested target.

In this design, the equipment is mainly composed of four parts: refrigeration system, heating system, circulation system and control system. R22 is selected as refrigerant in the refrigeration system, which is composed of screw compressor, tube fin air-cooled condenser, shell evaporator, and the required model is designed and calculated according to the requirements of refrigeration capacity. The external hexagonal heating rod is selected as the heating equipment. According to the functional requirements of the equipment, two sets of circulation are set up in the circulation system, and the brushless DC magnetic isolation type water pump is used. Multiple sensors are set around the equipment pipeline to monitor the temperature, pressure and other signals in real time, and the system is controlled with Siemens SIMATIC S7-200 PLC system. Through Modbus protocol, the communication code information is compiled to meet the functional requirements of the equipment.

Key Words：electric vehicle; power battery; testing system; PLC

Content

Chapter 1 Introduction 1

1.1 Research background and significance 1

1.2 Research Status 3

1.2.1 Technical Route of Power Battery 3

1.2.2 Thermal Characteristics of Battery 3

1.2.3 Cooling and Heating Mode of Battery 4

1.2.4 Battery Testing System 4

1.3 Research Content of This Paper 6

Chapter 2 Design Scheme 7

2.1 Technical Requirement 7

2.2 Overall Structure 7

2.3 System Function 9

Chapter 3 Refrigeration System 9

3.1 Overview 9

3.2 Refrigerant Type Selection 10

3.3 Determination of Design Conditions of Refrigeration System 11

3.4 Thermodynamic Calculation of Refrigeration System 12

3.5 Selection of Refrigeration Compressor 15

3.5.1 Cooling Capacity Calculation 15

3.5.2 Compressor Type Selection 15

3.5.3 Selection of Compressor Stages 19

3.5.4 Compressor Selection and Parameters 20

3.6 Selection and Calculation of Condenser 20

3.6.1 Condenser Selection Principle 20

3.6.2 Setting of Relevant Parameters of Condenser 20

3.6.3 Condenser Design Calculation 21

3.7 Selection and Calculation of Evaporator 23

3.7.1 Selection of Evaporator 23

3.7.2 Evaporator Design and Calculation 23

3.8 Selection of Expansion Valve 24

Chapter 4 Heating System and Circulation System 25

4.1 Circulating Water Tank 25

4.2 Layout of Heating System 26

4.3 Layout of Circulation System 27

Chapter 5 Control System 29

5.1 Control System Functional Requirements 29

5.2 Layout of Control system 30

5.3 Control System Communication Protocol 31

Chapter 6 Other Equipment 38

Chapter 7 Summary and Prospect 39