Electric vehicles
and it determines the speed of the car. The difference in the synchronous speed and the rotor speed is termed slip (S) which can be expressed as a percentage: (𝑁 𝑠 −𝑁 𝑟 ) 𝑁 𝑠 ∗100% . 8
The effectiveness of induction motors can differ depending on the type (single-phase or three-phase) and materials (copper or aluminium) used, but most are highly efficient in transforming electrical energy into mechanical energy at a wide range of RPMs as there is little friction between parts. The clever design of the induction motor also gives it a huge comparative advantage to ICEs, as ICEs are only efficient within certain RPMs and the power output is unstable, meaning additional accessories are required, increasing the weight of the car. 9
3.2 Inverter
Inverters handle intelligent power supply and energy management by applying conversions to the current. As most cars use lithium-ion batteries which store DC and an AC induction motor, inverters in these types of cars will change the DC from the batteries into AC to supply the motor. To do this, there is a DC input part that receives varying voltages. Power electronic switches then convert the current through PWM which is the effect of switching the voltage on and off at high frequencies to generate a sequence of voltage pushes which is achieved using insulated gate bipolar transistors . Controllers in the circuitry of the inverter aid in adjusting the timing and pattern of switching to produce desired wave properties. Once the previous steps are undergone, the inverter provides a one or three phase AC output to the motor depending on the motor type. 10 ( everythingPE editorial team, Working of Electric Vehicle Drivetrain 2023 ) Another benefit that EVs have over ICE cars is that they are much more efficient since during deceleration, the kinetic energy of the car can be transferred into electrical energy as AC and then converted to DC by the inverter which is then stored in the battery. This effectively recharges the battery and is called regenerative braking. The use of thermal management systems such as heat sinks and high-efficiency components with advanced switching techniques further enhance the performance of EVs, allowing them to stay cool. 11
3.3 Battery
Most EVs in our world today use lithium-ion batteries which are electrochemical cells that include an anode, a cathode, and an electrolyte. Typically, a graphite anode and a lithium cobalt oxide or lithium iron phosphate cathode are used as they can store and release ions. The electrolyte on the other hand is the medium through which ions move and is usually a gel or liquid. Batteries also have a separator that prevents short circuiting by disallowing the anode and cathode to have any physical contact with each
8 Chapman 2012. 9 Fitzgerald 2013. 10 Hava 2009 . 11 Mohan 2003.
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