Electric drivetrains represent a significant shift in the automotive industry. This transition renders many components of internal combustion engine (ICE) cars irrelevant for electric vehicles (EVs). This article outlines the key differences and some similarities between ICE and electric cars.
Key Innovations
We begin with a fundamental component found only in electric vehicles—the high voltage battery. This battery serves as the equivalent of a fuel tank in an ICE vehicle, supplying the necessary electric energy to the electric motor.
The electric motor is another unique aspect of electric cars, responsible for converting electric energy into mechanical energy to propel the vehicle. However, the relationship between the high voltage battery and the electric motor is not straightforward. The battery uses direct current (DC), while the electric motor operates on three-phase alternating current (AC).
An “interpreter” is necessary between these two components, a role fulfilled by the inverter. This power electronics device converts DC from the high voltage battery into three-phase AC for the electric motor during operation. Conversely, during regenerative braking, the process reverses, as AC is converted back into DC to recharge the high voltage battery.
The inverter's efficiency is critical for the overall performance of an electric vehicle. Additionally, the onboard charger acts as another essential connection, converting AC (from the grid) to DC to charge the battery. During high power DC charging, the onboard charger is bypassed.
Heating the cabin also differs significantly between the two types of vehicles. Electric cars use PTC heaters (Positive Temperature Coefficient) or heat pumps since they don’t have the abundant thermal energy that ICE vehicles produce from their inefficient engines.
Furthermore, the DC/DC converter is a vital new component in electric vehicles, responsible for converting the high voltage DC from the battery into 12V for lower voltage systems such as lights and infotainment.
The charging socket is also a distinctive feature of electric cars.
Differences in Power Systems
While both ICE and electric vehicles utilize air conditioning compressors, their operation diverges significantly. In electric cars, the compressor is a high voltage device powered by the battery. In contrast, ICE vehicles have a mechanical compressor driven by the engine’s crankshaft. Thus, activating the air conditioning in an ICE car can result in a noticeable power reduction.
Both vehicle types incorporate gearboxes, but electric vehicles typically feature a simpler transmission that generally has just one speed, aside from a few exceptions, whereas many modern ICE cars use complex multi-speed automatic transmissions.
The braking systems also differ in philosophy. In most electric vehicles, pressing the brake pedal engages the electric motor as a generator, initiating braking while recharging the battery—a process known as regenerative braking. Conventional hydraulic brakes are used only when greater stopping power is necessary. Conversely, ICE vehicles rely on hydraulic brakes every time the driver engages the brake pedal.
The design simplicity of the motors themselves is another point of contrast. Electric motors require little maintenance with only two moving parts, whereas internal combustion engines consist of many components—typically at least 40 in a four-cylinder engine—and require regular maintenance, such as oil and filter changes.
High voltage A/C compressor from Rheinmetall AutomotiveSimilarities in Design
Suspension, wheels, and tires share significant similarities across ICE and electric vehicles. Both types often employ similar suspension architectures, with electric cars based on ICE platforms typically retaining the same suspension design. Dedicated electric platforms generally utilize fully independent suspension systems such as multi-link, double wishbones, and McPherson struts.
Tires designed for low rolling resistance are available for both vehicle types. Although wheel designs initially diverged due to aerodynamic considerations, recent ICE models now frequently feature “aero” wheels similar to those on electric cars, aiding in the reduction of aerodynamic drag, which can account for a third of total drag.
Finally, steering systems in both ICE and electric vehicles rely on electromechanical systems, necessary for integrating advanced driver assistance technologies such as lane assist and autonomous parking.
Tesla Model 3 and Skoda Fabia aero wheels designConclusion
In summary, the primary differences between internal combustion and electric vehicles arise from their fundamentally distinct propulsion systems, necessitating different components. However, despite these differences, many similarities exist, as both are automobiles and share several common parts. This overlap is beneficial, as it enables more economical production and speeds up the adoption of electric vehicles.
