The term "recuperation" itself has been known for a long time and implies the possibility of partial recovery of used energy (heat, water, gases) to reuse it. In this sense, regenerative braking also implies the process of returning part of the expended energy.
What is regenerative braking?
When choosing an electric vehicle, one of its most important parameters is the range per charge. Manufacturers of electric cars are actively researching and introducing new developments that can increase the range of an electric car on a single charge. Regenerative braking, as one of the possibilities of partial recovery of the battery charge, is an important nuance when choosing an electric car.
In a few words, regenerative braking in electric vehicles can be described as the process of obtaining energy during the braking of a car, i.e. in fact, this is recharging the battery of an electric car right in the direction of travel.
Principle of operation
To understand how the regenerative braking system works, it is necessary to remember that every moving body has kinetic energy. When braking a car with an internal combustion engine, this energy is consumed during the contact of the brake pads and brake discs, erasing them, i.e. just "nowhere." Electric vehicles are taking a more thoughtful approach to energy use. The recovery process is presented here as follows:
- When braking starts, the electric motor changes its operating mode: instead of being powered by a battery, it starts to work as a generator, generating energy. At this moment, opposite currents appear in the rotor and stator windings.
- The decrease in the speed of the vehicle occurs because a braking torque appears on the shaft of the electric motor.
- The kinetic energy available before the start of braking is transformed into electrical and thermal energy.
- The emerging additional electricity flows into the battery, thereby increasing its charge.
Regeneration of the electric motor from the point of view of the physical process is quite effective since its efficiency is about 70%. Those. about 70% of the energy expended in braking is converted into electrical energy. However, the efficiency of regenerative braking in terms of increasing the vehicle's range is not so great, since the increase in mileage is only within 10-20%, depending on the conditions: type of car and asynchronous engine, vehicle size, travel speed, battery characteristics, road conditions, etc.
Conditions under which regenerative braking of a DC motor is most effective:
- suburban tracks that allow you to develop good speed;
- hilly terrain and steep slopes;
- in urban conditions when moving in the "start-stop" mode;
- the large size and weight of the car;
In this case, the rule is true: the more often the electric car slows down, the more its battery is charged.
When not effective
Situations where regenerative braking of the electric motor is not effective:
- movement on a flat surface at one speed (in this mode of movement, the machine brake is rarely activated);
- low battery temperature (at a low battery temperature, recuperative electricity will be generated in a limited amount);
- 100% battery power (it is impossible to charge the battery if it is already 100% charged).
In a situation where the range of an electric vehicle is limited by the battery charge, any source other than the charging station that can generate additional energy is important. Therefore, regenerative braking DPT is a good and promising way to increase mileage. And 70% of the saved energy is a good indicator, given that just 10-15 years ago such losses were not paid attention at all.
Additional Information! Moreover, the process of modernization and optimization of recuperation does not stop. Development is currently underway to improve recuperative systems to increase their efficiency, as well as to provide the possibility of recuperation not only in braking mode. In particular, a special suspension is being actively developed, the device of which allows the use of recuperation during normal driving. In this case, the recuperation efficiency will almost double, and the increase in mileage of the electric car due to such additional recharging will be up to 40-50%. However, it is not yet clear when such a scheme will be implemented on production machines.
Some manufacturers have stepped a little further than others and have been producing cars with a recuperation option for a long time: Nissan Leaf, BMWi3, Hyundai Loniq, Chevrolet Bolt. Others are only planning to do so. Nevertheless, it is safe to say that today recuperation as a form of replenishing the battery charge is already one of the competitive advantages of an electric vehicle.
Note! Of course, such a recuperator cannot be compared to a charging station, however, perhaps this small additional charge will allow the car to get to the charging point and not stop somewhere on the road with zero energy level.