Design and Control of Battery Charger for Electric Vehicle Applications

The interest in electric vehicles has increased rapidly over the past few years. International energy outlook report 2012 reported that more than 100,000 hybrid and all-electric vehicles sold globally, and sales figures are approximately doubling each year. And, according to the international energy

Project Title

Design and Control of Battery Charger for Electric Vehicle Applications

Project Area of Specialization

Electrical/Electronic Engineering

Project Summary

The interest in electric vehicles has increased rapidly over the past few years. International energy outlook report 2012 reported that more than 100,000 hybrid and all-electric vehicles sold globally, and sales figures are approximately doubling each year. And, according to the international energy outlook report 2015, alternative vehicle technologies are replacing conventional vehicles. These alternative vehicle technologies, that include hybrid electric vehicles (HEVs), Plug-in HEVs (PHEVs), and Electric Vehicles (EVs), have gained popularity because of their advantages, such as more environmentally friendly, less noisy and more efficient. Many automobile manufacturers like Nissan, Tesla, Chevrolet, BMW, VW, Audi, Volvo and Mercedes have at this point developed and commercialized their first modern electric models, proving that the electric drive is technically viable, environmentally friendly and affordable. 

The system architecture of EV is shown in Fig.1.1. There are two main parts in an EV, the Battery and Traction Motor. The Battery is the only source of energy in an EV. The Battery Management System (BMS) continuously monitor the cells inside the battery and it makes sure the battery is operated in the safest conditions. Some EVs have on-board chargers that charge the battery. To reduce the weight and size of the EV, most of the vehicles do not have onboard charges. They are charged using off-board chargers. 

Fig.  1.1. The system architecture of HEV and EV

These battery chargers, whether on-board or off-board, convert the input power to the dc power and charge the batteries inside these vehicles. Usually, battery chargers are unidirectional transferring power from the grid to the battery only. The input power can be AC from the grid or unregulated DC from the Photovoltaic (PV). 

There are many types of batteries such as Lead-Acid, Nickel and Cadmium, Lithium-ion/polymer, Sodium and Nickel Chloride, Nickel and Zinc. Each battery has its own charging profile. Fig.1.2 shows the typical charging profile of Li-ion and Lead-Acid based battery cell. The constant current mode is followed by the constant voltage mode. During constant current charging, the current is regulated at a constant value until the battery cell voltage reaches a certain reference voltage. Then, the charging is switched to constant voltage charging, and the battery is charged with a trickle current applied by a constant voltage output of the charger. 

Fig.  1.2. Typical charging profile of Li-Ion cell

Project Objectives

The goal of this project is to design an off-board battery charger that is capable of charging the batteries for EV applications. The proposed project will mainly focus on the following objectives:

1. Develop a battery charger capable of charging both Lead-Acid and Li-ion batteries.
2. The proposed battery charger will have both Constant-Current (CC) and Constant Voltage (CV) mode.
3. The battery charger will have the capability to get power from both AC grid as well as Photovoltaic (PV) panels. 
4. There will be closed-loop controls with both hardware and software protections.

Project Implementation Method

This project will be implemented in the following steps.

1. First a simulation model will be built in Proteus and PSIM to select the topology and to validate the design.

2. Then, a loss model will be developed for the system to predict the efficiency and optimal operating range of the system.

3. The small-signal model of the converter will be derived. This model will be used to design the current loop compensator and voltage loop compensator. 

4. Hardware components will be chosen and will be procured for the system.

5. A Printed Circuit Board (PCB) will be designed and fabricated for the power stage.

6. The components will be soldered on the PCB boards to build them.

7. The PCB will be tested at Low-Voltage and Low-Power with dummy load.

8. The PCB will be tested at rated voltage and full-power with dummy load.

9. The PCB will be tested at Low-Voltage and Low-Power with battery load.

10. The PCB will be tested at rated voltage and full-power with battery load.

11. To reduce the size and cost of the system, the voltage and current measuring sensors are designed.

12. The system is tested with the indigenously designed sensors. 

13. The system is tested in the electric bike.

Benefits of the Project

To reduce the dependence on fossil fuels and to reduce environmental pollution, many countries including Pakistan is trying to develop electric vehicles like electric-bikes, electric-rickshaws and electric-cars. These electric vehicles are driven off the energy stored in the batteries. Since the batteries store a limited amount of energy, they need to be charged after every operation. So, in the near future, there will a need for battery chargers in the cities. Currently, these chargers are not developed in Pakistan. Now, these chargers are developed locally, it will reduce the cost as well as it will save the foreign exchange. 

Technical Details of Final Deliverable

The final deliverables are both Hardware and Software. 

A. Hardware deliverables:

    1. Voltage Sensor

    2. Current Sensor

    3. Temperature sensors

    4. Printed Circuit boards

    5. Microcontroller

    6. Batteries    

B. Software:

    1. Firmware in Microcontrollers

Final Deliverable of the Project

HW/SW integrated system

Core Industry

Energy

Other Industries

Manufacturing , Transportation

Core Technology

Artificial Intelligence(AI)

Other Technologies

Shared Economy, Clean Tech

Sustainable Development Goals

Affordable and Clean Energy, Climate Action

Required Resources

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