Question

In a blended regenerative braking system, what is the mathematical relationship between the vehicle&#x27;s kinetic energy, the inverter efficiency, and the total energy returned to the battery during a deceleration event?

Accepted Answer

The total energy returned to the battery during a regenerative braking event is defined by the product of the vehicle&#x27;s change in kinetic energy and the efficiencies of the energy conversion path. Kinetic energy is the energy an object possesses due to its motion, calculated as one-half the product of the vehicle mass and the square of its velocity. During deceleration, the electric motor acts as a generator, converting this mechanical kinetic energy into electrical energy. The inverter, which is an electronic device that manages the flow of electricity between the motor and the battery, has an efficiency factor representing the percentage of electrical power successfully transferred without being lost as heat. The mathematical relationship is expressed as E_returned = (Delta_KE) multiplied by (Efficiency_drivetrain) multiplied by (Efficiency_inverter) multiplied by (Efficiency_battery_charging). Delta_KE represents the total mechanical energy available to be harvested from the change in vehicle speed. The drivetrain efficiency accounts for losses in gears and bearings, the inverter efficiency accounts for electrical conversion losses, and the battery charging efficiency accounts for internal chemical and resistance losses. Consequently, the energy recovered is always less than the initial kinetic energy because each stage of the conversion process dissipates a portion of the energy as thermal waste.

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In a blended regenerative braking system, what is the mathematical relationship between the vehicle's kinetic energy, the inverter efficiency, and the total energy returned to the battery during a deceleration event?