Design & Performance of Components of Electrical Vehicles P M V Subbarao Professor Mechanical Engineering Department Eligibility Test for A Reliable Horse …

Proposed configurations for an Electric Vehicle

Energy Flow of A Battery Electric Vehicle

Functional Block Diagram of A Typical Electric Propulsion System

Powertrain The vehicle powertrain consists of An inverter, An AC induction motor, a reduction gear differential, drive shaft and wheels. The conversion from electrical energy to mechanical energy is not 100% efficient. The energy losses within the powertrain have to be considered. The motor and inverter losses are considered together, as it is difficult to determine them individually.

Distribution of Energy Losses in Powertrain The energy loss can be divided into four parts: copper loss, iron loss, friction and windage loss and stray loss. Each type of energy loss is determined by different factors, which makes it difficult to be calculated by physical or mechanical laws and also detailed information on the motor is required. To determine the power loss, a dynamometer test is done. The motor loss, inverter loss and powertrain friction loss are considered together as the powertrain loss and an empirical equation is used to describe this.

The dynamometer test

Motor Power Vs Power Train Losses

Energy Efficiency of Power Train

Electro-chemistry of Battery

Details of A Typical EV Battery

A typical model of the charge/discharge profile of a Li/LiCoO2 full cell. Fluid, Fluid,

Battery model The 85 kWh battery pack weighs 540 kg and contains 7,104 Lithium-ion battery cells in 16 modules wired in series.

Energy Consumption The energy consumption per unit distance in kWh/km is generally used to evaluate the vehicle energy consumption. Energy consumption is an integration of the power output at the battery terminals. For propelling, the battery power output is equal to resistance power and any power losses in the transmission and the motor drive, including power losses in electronics. The power losses in transmission and motor drive are represented by their efficiencies ηt and ηm respectively. Thus, the battery power output can be expressed as

City Cycle : Total traction energy and energies consumed by drags and brakin

Regeneration The major advantage of EV is the possibility of regeneration during breaking. When regenerative braking is effective on an EV, a part of that braking energy is recovered by operating the motor drive as a generator and restoring it into the batteries. The regenerative braking power at the battery terminals can also be expressed as where road grade or deceleration (dV/dt) or both of them are negative. α (0 < α <1) is the fraction of the total braking energy that can be applied by the electric generator, called the regenerative braking factor

Net Energy Consumption The regenerative braking factor α is a function of the applied braking strength and the design of the power train. The net energy consumption from the batteries is

Travel Range The travelling distance between two charges is called effective travel range. This is determined by the total energy carried by the batteries, the resistance power, and the effectiveness of the regenerative braking (α). The efficiency of a traction motor varies with its operating points on the speed–torque, where the most efficient operating area exists. In power train design, most efficient area should overlap with or at least be as close as possible to the area of the greatest operation.

Motors in 2017 EVS Tesla Models S & X : Three phase, four pole AC induction motor with copper rotor Drive inverter with variable frequency drive and regenerative braking system.

The Model X's all-wheel drive system uses two motors (one for the front and the other for the rear wheels). The Tesla Model X 100D features an official EPA rated range of up to 295 mi, and a European NEDC testing cycle estimated range of 565 km.

Tractive effort vs. vehicle speed with a traction motor of x =2 and three-gear transmission

Tractive effort vs. vehicle speed with a traction motor of x =4

Energy and Power Needs Rate is a problem. Example: refill a gas tank with 15 gal in 5 min. The energy rate is roughly that of 20 major campus buildings! It is costly and problematic to fill batteries quickly.