Recuperation in electric Vehicles
Recuperation in the e-up!How does energy recuperation work when braking?
The drive motor of the e-up! selectively operates as a generator for producing electricity during coasting and braking phases, instead of charging the battery permanently using an alternator as in conventional vehicles. The recuperated energy is used for supplying comfort and secondary consumption systems with any excess energy stored in the high-voltage battery. At the same time, the resistance caused by the electricity generation is utilised as an electromagnetic brake for slowing the vehicle down. At lower speeds, the electromagnet braking torque caused by the generator is reduced. Recuperation is not possible if the vehicle is fully charged and thus the car cannot be slowed down in this fashion: so in this situation to slow the car the driver just applies the brake as in a conventional car.What possibilities does the e-up! offer to drivers?
The driver can individually preselect the desired braking effect of the generator with the recuperation settings D1 to D3 and the setting B. The setting D1 only causes slight deceleration. The braking effect of the generator is progressively increased in the settings D2 to D3. The setting B offers the greatest coasting deceleration. The recuperation potential is determined by the car’s kinetic energy and therefore stays the same in all recuperation settings. The level of deceleration can be flexibly adjusted to handle any given traffic situation and partially recuperate energy. Another alternative is offered by the setting D, which allows the driver to utilise the kinetic energy of the car and stay in the coasting phase for as long as possible: in this way the car runs without active braking torque and is comparable to a declutched combustion engine.
In this setting it is also possible for energy recuperation to be activated when the driver applies the brake. In this case, the electronic brake booster automatically controls the balance of the ratio of braking caused by the generator and the wheel brakes. The brake function necessary for doing so is called brake blending.