You must have already heard this concept of “regenerative braking.” To break the two words down, “regeneration” involves recovery while “braking” refers to the braking system present in automobiles. Well, regenerative braking is not a new technology. It’s been there for almost 60 years! However, today we will discuss its implementation on the latest revolution- electric vehicles.
So, I’ve broken down the article into eight major categories. These should sort out your basics if you’re a beginner in this domain. For more detailed analogies, check out our other articles.
So, here are the topics we’ll be covering:
- Types of EVs
- Energy Storing Systems in EVs
- Regenerative Braking- An Introduction
- Major Components of RBS
- Principle of RBS
- Working Phenomenon of RBS
- Advantages and Disadvantages of RBS
So, let’s start!
Types of Electric Vehicles
Well, broadly discussing, EVs can be categorized as:
- Hybrid Electric Vehicles or HEVs
- Plug-in Hybrid Vehicles or PHEVs
- Battery Electric Vehicles or BEVs
So, the significant difference between these types is their transmission energy and charging properties. HEVs consist of a combustion engine as well as a battery-driven motor mechanism. The same goes for a PHEV. However, Hybrid vehicles cannot be charged through an external source at home or a charging station. The battery is continuously charged through the energy generated due to the IC engine and regenerative braking.
On the other hand, PHEVs have various forms of charging mechanism- IC engine, regenerative braking, external source, and it has got it all.
Lastly, let us come to BEVs, also known as all-electric vehicles. As the name suggests, these do not have any IC engine and are entirely driven by electricity. They can be charged at home, charging stations, or any other external power supply.
Here are some examples:
- HEV: Honda Accord Hybrid, Toyota Camry Hybrid
- PHEV: Jeep Compass PHEV, BMW i8
- BEV: Tesla Model X, Tata Nexon EV
Energy Storage Systems in EVs
Now that you have an idea regarding the types lets slowly shift towards our main topic. Energy is usually stored in these four forms in the Electric Vehicles of today:
- Batteries: Most common
- Ultra Flywheel: This is a very high-efficiency form of energy conversion and storage, mostly used in the aerospace industry. However, recently EVs OEMs have also started exploring this option. However, it is only used in heavy-duty vehicles like electric trucks.
- Fuel Cells: This is something on which a lot of research is going on. These cells use the exothermic reaction between hydrogen and oxygen to generate the required energy. However, as of now, most vehicles go for Li-ion batteries.
- Super Capacitors: The electrostatic energy stored in the capacitor is converted into electrical energy. As we all know, capacitors charge and discharge very quickly. Hence, a lot of the motorsport companies use this supercapacitor tech to boost their acceleration for a short period.
In the automotive sector, KERS or Kinetic Energy Recovery System is used. The brief characteristics are as follows:
- Uses a motor-generation unit for the generation of energy
- Regenerative braking is the primary method of energy recovery used in KERS
- HEVs also have an energy-saving system to increase the efficiency of the vehicle. An example is a Start-Stop system.
Regenerative Braking- An Introduction
The direct energy conversion used here is the transformation of Kinetic Energy into Electrical Energy.
The Motor-Generator Unit(MGU) converts the vehicle’s momentum/state of motion to recover the energy that would otherwise be lost as heat in the brake discs. This type of system increases the efficiency of the vehicles. It also prevents the mechanical parts of the car from wearing away quickly.
RBS works on the fundamental law of conservation of energy.
This was first developed by American Motor Corp way back in 1967. However, It was popularised by companies like Toyota, Ford, and BMW.
Significant Components of Regenerative Braking
- Motor-Generator Unit (MGU)
- Power Converter Unit (PCU)
- Energy Storage System
- Regenerative Braking Controller (RBC)
- Energy Management System (EMS)
- Wiring Harness
- Wheel Speed Sensors
Working Phenomenon of Regenerative Braking
- During acceleration, the MGU acts as an Electric Motor (EM), taking electrical energy from the battery for propulsion.
- While braking, the Motor starts experiencing torque in the opposite direction- hence it starts acting like a generator. However, the MGU must be carefully designed for such a mechanism.
- The Motor turned Generator now charges the battery for a short period.
- Regenerative braking lets the vehicle speed shed; however, friction brakes are also required. This is because the braking torque under regenerative braking gradually decreases with time. Hence, it is just a supplementary system!
- Reduces wear and tear in the braking system
- Reduces wastage of energy
- Improves braking performance
- Increases efficiency
- RBS increases the number of components and the complexity of the system
- Enhances the weight of the system
- Increases cost of maintenance
- Increases the cost of the automobile
I hope now you have a basic idea about how this technology works.
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