Designing of regenerative braking system for electric vehicle

Project Title

Designing of regenerative braking system for electric vehicle

Project Area of Specialization Electrical/Electronic EngineeringProject Summary

The increased concerns over the impact of conventional (fossil fuel-based) cars on the environment have reinstated the interest and advancements in the electric vehicles (EV). Electric vehicles use a DC motor powered by a battery bank. The capability of any motor to work as a generator gives rise to an opportunity for regenerative braking system. This capability is lacking in traditional vehicles that use internal combustion engines. In conventional braking, all the kinetic energy of a vehicle is thermally dissipated while in regenerative braking system some part of this kinetic energy is converted to electricity and stored in a battery. Whenever breaks are applied to stop a vehicle all of its kinetic energy is lost as heat. Considering the large number of vehicles being operated globally overall huge energy is wasted through the braking process. Using regenerative braking a portion of this wasted energy can be converted into electrical energy. This energy can easily charge an onboard battery bank already available in the electric vehicle. This stored energy can be reutilized to run the electric vehicle. This will result in two advantages (1) increasing the overall efficiency and (2) minimizing thermal loss hence reducing global warming. Regenerative braking is proven to be effective and it can be used for increasing the mileage of electric vehicles (EVs). It is reported that usage of regenerative braking system can result in 15% - 20% range extension of EVs [1]. 

In this research the design and development of a small electric vehicle having the capability of producing energy using regenerative braking system and reutilized it for increased mileage. Initially an extensive literature review is carried out to determine what research has been done so far on regenerative breaking system in general and then specifically the research done on power electronic aspects of the electric regenerative braking systems. A prototype system will be developed to validate the claims.

[1] Nugroho, Ignatius Wisnu Adi, and Slamet Riyadi. "Regenerative Braking with Duty Cycle Settings for Brushless DC Motor." In 2019 International Conference on Electrical Engineering and Informatics (ICEEI), pp. 336-341. IEEE, 2019.

Project Objectives

This project targets the following main objectives:

1. In an electric vehicle the main goal is to run a mechenical load (structure of the vehicle along with the driver and passengers). Therefore our first objective is designing a mechanism to operate a motor to run a mechanical load.
2. For regenerative mechenism an electricity generator is required. for this purpose either a seperate generator should be installed or the already installed motor that is running the electric vehicle should be used. The cost effective solution is to use the same motor as a generator. therefore our second objective is designing a mechenism to operate the primary motor as as a generator as soon as the breaks are applied.
3. The regenerated energy needs to be stored in a battery bank in order to be utilized as and when required. Therefore our third objective is designing a mechenism to store the regenerated energy in a battery bank.
4. Batteries are among the heaviest equipment that an electric vehicle carries. In order to avoid additional load on the vehile our fourth objective is designing a mechninsm to use a single battery bank that can be charged using conventional source as well as regenerative source simultaneously.
5. Application of breakes results in gradual reduction of speed of the electric vehicle. This results in gradual reduction in the kinetic energy of the vehicle and hence the voltages generated are also gradually reduced. Therefore a regulation mechenism is mandatory to be used in order to chare the battery at variable available voltages. So our fifth objective is designing a mechenism to charge the battery bank at variable input voltages.
6. Finally this system will be installed on a vehicle and tested for efficiency improvement.

Project Implementation Method

The purpose of this project was to develop a regenerative braking system for an electric vehicle so that it can recover wasted energy which cannot be done in conventional vehicles. Regenerated energy can be used to improve energy utilization for vehicle batteries.

This project mainly follows the following steps to design and develop regenerative braking system.H-bridge is used as the motor driving circuit MOSFETs with MOSFET driving ICs. Switching of MOSFETs is controlled through arduino and electric brake pedals are the analog input to the arduino which is converted into PWM to control the MOSFETs. The flow the project is as follows:

1- Electric brake pedals give analog signal to the controller(Arduino)

2- Controller converts the signal into PWM to controller the switching of the MOSFETs.

3- In forward commutation battery drives the motor. And in reverse commutation battery current is cut-off and motor acts as a generator producing current in reverse direction.

4- The regenerate voltage is then regulated to the battery level through a regulator circuit.

5- The current is then stored in a battery after regulation.

DC motor commutation is achieved by control of conduction on the inverter bridge arm. The basic of an equivalent circuit of a DC motor with a drive system is in the form of H-bridge inverter. Forward commutation of the DC motor happens when acceleration pedal is pressed and controller converts the analogue signal into PWM and the PWM is than applied to MOSFET driving ICs and the ICs control the switching of the MOSFETs according to the applied signal. Regenerative braking can be achieved by the reversal of current in the battery during deceleration, taking advantage of the motor acting as a generator, redirecting the current flow into the supply battery.

In regenerative phase all the switches of the H-bridge are turned off except one which will determine the amount of current that flows to the battery. And by controlling the amount of current we can control the braking intensity on the vehicle.The regenerated voltage level is not equal to the level of battery and it is decreasing in nature, So to recharge the battery effectively a voltage regulator is used that will give a constant output with a variable input.Voltage regulator used is LM78 series which will give constant 15v on variable input voltage.This regulated voltage is than stored in the battery for further utilization.

Benefits of the Project

Moving vehicles like cars and buses include lots of kinetic energy. and its movement can be controlled by applying brakes, then the energy within the vehicle will go somewhere. In the early days, the brakes used in an internal combustion engine cars were simply based on friction & changed the vehicle’s kinetic energy can be changed into exhausting heat to slow down a car. All of that energy was just gone to the surroundings. Auspiciously, we have developed a system in a better way namely a regenerative braking system.Regenerative braking technology, to recover energy from masses in motion, has been studied on before. This could be in either electrical means or mechanical means. Hybrid and electric vehicles currently in use have some means of regenerative braking to recover energy. But still the braking technology is not a fully electrical regenerative braking (there are mechanical regenerative braking means as well). This chapter provides an overview of research done so far in the field of regenerative braking

Conventional vehicles (fossil fueled) is a cause of continuous and uncontrolled emission of hazardous and polluting elements to the atmosphere.The scarce supply and harmful effects  of fossil fuel ihas driven the development of electric vehicles (EV) worldwide.

A key advantage of electric vehicles is regenerative braking, which recovers kinetic energy, typically lost during friction braking as heat, as electricity restored to the on-board battery. 

The Traditional braking system for a vehicle is based on hydraulic braking technology. Hydraulic braking method causes a lot of kinetic energy wastage. This wasted energy can otherwise be utilized to recharge the battery.

The electricity generated through this method is cost free and also the motor turned generator will act as brake to slow down the vehicle. And by recharging the battery during braking we can inprove the milage the battery.

The project plays a vital role in the betterment of the battery usage capacity. Pollution and the reduction amount of fossil fuels has become a global challenge. This project helps to increases the charge storage in the battery in every instant when brakes are applied on 4 the vehicles. The project improves the fuel economy of the electric vehicles. It reduces the wear and tear on the braking system. So this project overcomes pollution related to the electricity generation.

Technical Details of Final Deliverable

Block diagram:

The system uses the H-bridge circuit as motor driving circuit and Power MOSFETs are used as switches with MOSFET driving ICs.Due to high power requirements several MOSFETs are used in-parallel. 

Signal from the accelerator (electric pedal) drives the motor is forward and reverse direction. And brake pedal controls the current being stored in the battery as well as the total brake on the vehicle.

Electro-machanical pedal with power source of 5V and 0-5V variable voltage is used to supply analog signal to the controller (Arduino), Arduino then converts the anaolg signal into corresponding PWM signal that is supplied to MOSFET driving ICs( IR2110) which will convert 0-5V PWM signal to a 0-10V low side PWM and 0-35V( as we are using 24V battery source) high side signal. When the signals are applied to the opposite high side and low side MOSFETs the motor rotates in forward or reverse direction. And we can control the speed of the motor by controlling the duty cycle of the switches.when the acceleration signal is zero and control is given to braking electric pedal(0-5V) and the brakes are applied the controller will invert the signal so that when no brakes are applied controller will give full PWM and when full brakes are applied controller gives zero PWM. During braking process low side MOSFET adjacent to high side MOSFET which was turned on during driving commutation is controlled. When the switch(MOSFET) is fully turned on(No brakes) the regenerated current rotates in the circuit and when we apply brakes the switch is off and it the path is broken and current is forced to flow through free-wheel diode of high side MOSFET and through the battery thus recharging it. The voltage regenerated is of level not equal to the battery and is variable which requires furtther regulation. For this purpose a voltage regulation ICs is used with its own circuit. The output of the voltage regulation circuit is set at a constant 15V(for recharging 12V battery) through resistor combination and it gives this constant voltage on variable input voltage. The regulated voltage is then stored in a battery for further utilization. This battery will act as a load on the motor turn generator and it will slow down the rotation the generator resuting it slowing the prime mover(vehicle) thus acting as brakes on the vechicle.

Mathematical model:

Components :

1-  Power Mosfets

2-  Arduino

3-  Motor driving ICS LM2101

4-  DC Motor

5-  Batteries

6-  Electromechanical brake pedals

7-  Relays

Circuit diagram:

Simulations:

Hardware Prototype:

Final Deliverable of the Project Hardware SystemCore Industry Energy Other Industries Transportation Core Technology OthersOther TechnologiesSustainable Development Goals Affordable and Clean Energy, Responsible Consumption and Production, Climate ActionRequired Resources

Item Name	Type	No. of Units	Per Unit Cost (in Rs)	Total (in Rs)
			Total in (Rs)	80000
DC motor	Equipment	1	16000	16000
Batteries	Equipment	2	8000	16000
Tachometer	Equipment	1	3000	3000
Brake pedals	Equipment	2	2500	5000
Machanical Structure	Equipment	1	24000	24000
ICs	Equipment	4	250	1000
MOSFETs	Equipment	15	80	1200
Arduino Mega	Equipment	1	2800	2800
step-down converter for Arduino and ICs	Equipment	2	500	1000
transportation	Miscellaneous	1	3000	3000
printing	Miscellaneous	1	3000	3000
overheads	Miscellaneous	1	4000	4000