How are electric cars different? Some parts of the car are missing, others are missing. The developer of DEVINN s.r.o. summarizes the basic specifics of the electric car design and its features in a simple and factual way.
How are electric cars different? Some parts of the car are missing, others are missing. DEVINN's developer summarises the basic specifics of electric car design and features in a simple and to the point manner.
First, let's take a quick look at the internal combustion engine, which draws air from the surroundings and fuel from the tank, burning their mixture in the combustion chamber causes the mixture to expand and the pistons to move. This movement turns the shaft, which is connected to the gearbox via a clutch, which then turns the wheels of the vehicle. The exhaust gases leave the combustion chambers via the exhaust pipe. Simplistically, the following components are needed to power the vehicle: air filter, intake manifold, fuel tank, engine block with pistons and shaft, clutch, gearbox and exhaust pipe. It works on a completely different principle. A chemical reaction in the battery generates electrical energy, which is fed into the power electronics, which adjusts the voltage and current for the actual needs of the electric motor. Electromagnetic fields are generated in the electric motor and interact to spin the motor shaft, which is connected directly to the vehicle's wheels via a simple single-stage reducer. No gases are produced during driving and no exhaust pipe is needed.
Today's internal combustion engines have become very complex devices with dozens of different sensors, sensors and actuators. This is due to the natural desire of the developers to make the best engine possible, and due to various environmental regulations (particulate filters, AdBlue, etc.).In contrast, the electric motor is a very simple machine, requiring one rotor position sensor and one temperature sensor in the winding to function. While in an internal combustion engine dozens or hundreds of parts can fail, in an electric motor, if properly designed, only the bearings wear out. However, this too should outlast the life of the entire vehicle. Therefore, an electric motor should not require any maintenance during the life of the electric vehicle.
For vehicles with an internal combustion engine, the concept of a front engine and front-wheel drive or all-wheel drive has gradually become established. For the internal combustion engine, this concept was advantageous for several reasons. These include the need for a crumple zone at the front, the proximity of the driven axle to the engine, the length of the exhaust pipe required, the size of the combustion engine, the need for cooling, and more.An electric engine of the same power takes up less space, and does not need exhaust and intake pipes, and does not heat up to such high temperatures. It can therefore be positioned in multiple ways with fewer design constraints compared to an internal combustion engine. This is where the approach of different manufacturers differs slightly. While Tesla and more recently VW, for example, are going down the route of a pure electric platform, where it works out better to place the main engine to the rear axle, or two engines (front and rear) for 4x4 drive, Peugeot and Hyundai, for example, use a common platform for electric and internal combustion vehicles. So they replace the internal combustion engine with an electric one, hence it is located at the front axle.
An electric car doesn't have a clutch. The internal combustion engine must have a certain non-zero speed when starting, and the internal combustion engine uses a clutch to gradually balance the engine and wheel speeds. In contrast, an electric motor is able to set the whole vehicle in motion from zero speed. The clutch is therefore not needed. Similarly, there is no need for a flywheel and no need for a gearbox, even an automatic one. Only a permanent transmission between the engine and the wheels is applied.
The response of an electric vehicle to gas is almost instantaneous. The electric motor has significantly less rotating inertial mass, and there is no need to increase turbocharger speed, shift gears, etc. to increase speed. Simply change the switching logic of the transistors, which switch, say, 20,000 times per second. So the acceleration is almost instantaneous.
A negative feature of electric vehicles is the size and weight of the battery. To give you an idea, Tesla's Model 3 battery, which is enough for a range of 400-500 km, weighs around 500 kg. And Tesla is probably the best of all manufacturers with its battery storage. The increased weight of the vehicle adversely affects its driveability. To minimise the impact, the battery is placed as close to the road as possible. The centre of gravity of electric cars is therefore very low, which has a positive effect on cornering behaviour and partly compensates for the increased weight of the vehicle. To reduce the overall weight of electric vehicles, manufacturers also try to reduce the weight of the body and other components by using aluminium (Tesla X and S) and composite materials (BMW i3), or high-strength steel (Tesla Model 3).
An electric vehicle requires minimal maintenance. Unlike an internal combustion engine vehicle, there is no need to change the oil, air filter, fuel filter, spark plugs, timing belt with pulleys and water pump. The vehicle does not have an alternator and pulleys, thanks to the regeneration, there is minimal wear on the brake pads and discs.On the other hand, it should be mentioned that there is a gradual degradation of the battery, which will sooner or later need to be replaced or refurbished. The degradation of the battery and the associated reduction in range is likely to be slightly different for each vehicle. It depends primarily on driving style, ambient temperature, use of fast charging and more. Most manufacturers provide a warranty of around 160,000 km or 8 years for a maximum of 25% capacity reduction. How it will run and how much it will cost to repair or replace the battery, if any, will depend on the manufacturers' programs and the price of lithium cells. In extreme cases, the cost of replacement could reach hundreds of thousands of crowns.
What about security? Electric vehicle batteries are highly flammable. But so is petrol, and it has become such a common part of our transport that we no longer even perceive any danger. In addition, electric vehicles have an electrical system with a voltage of around 400 volts, which can lead to fatal injuries in humans if touched. But so can the 230 V that we have in most electrical equipment in the home. In electric vehicles, this electrical system is isolated from the ground and from the bodywork. To be electrocuted, it would be necessary to touch the plus wire with one part of the body and the minus wire with the other (i.e. two different damaged wires at the same time). Unlike a house socket, where you only need to stick one "nail". In addition, all the wires are made in multiple insulation and the electronics watch for damage that would put voltage on the body of the vehicle.
Electric cars can be considerably simpler with less maintenance and more comfort for the user (apart from charging on long journeys). The biggest current challenge for developers is to reduce the weight and cost of the battery. But even here, there is a glimmer of hope for better times, and not long ago it was much worse.
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