E-cars are becoming more powerful, battery and engine technology is developing further, assistance systems are becoming more intelligent. We can now give you an overview of the current technology trends in electromobility.
E-cars are far from being fully developed. More and more powerful electric motors, batteries and assistance systems are now widely in use. Global competition vying for more range, performance and comfort is in full swing. Power-to-weight ratio plays a major role here; batteries are heavy. E-cars weigh up to 30 per cent more than their combustion engine counterparts, regardless of vehicle class. So the big challenge is to reduce weight, to increase battery power and to extend the range achieved. Ultimately, however, an e-car should remain affordable and accessible to everyone. This is a conflict of goals, but one which can be optimised by means of intelligent technologies and an increase in production output.
At first glance, the e-drive appears less complex than an internal combustion engine. And indeed, at first glance, this is correct because such complex engine and transmission technology is not present. It is, of course, a fact that no exhaust gas aftertreatment is necessary. On the other hand, the electric drive train includes complex power electronics and the equally complex charging and thermal management.
There are different methods of implementing the electric motor and the power electronics: separately or in one unit. In order to reduce costs, many car manufacturers go for complete drive units. In addition to the electric motor (400-800V) and the power electronics, they also have single-speed or two-speed transmission. In the commercial vehicle sector, even the brake systems including the recuperation function are sometimes part of the drive unit, i.e. creating a complete e-axle.
Alongside weight and cost reduction, energy density is the decisive factor when it comes to batteries. At the moment, lithium-ion batteries are mostly used. The technology is mature, their lifetime is good, they function safely and reliably. But there are also disadvantages: Li-ion batteries are relatively heavy and charging times are relatively long. Fast charging technologies first have to be further established, a development which also depends on the performance of the network infrastructure. The costs are also relatively high. However, they will decrease by ramping up production quantities. In addition, Li-ion batteries contain materials that can be harmful to the environment if recycled incorrectly. But recycling processes are also being improved all the time.
Promising alternatives to Li-ion batteries are the solid-state batteries. No liquid electrolytes are used with these. The advantage is the higher energy density and the higher degree of safety. Sodium-ion and zinc-air batteries are also under development.
The management of the system temperatures of the batteries, the cooling of the e-motor and the power electronics are all aspects that are essential for electric vehicles. The batteries must be kept within a certain temperature window in order to achieve optimum efficiency. Above an operating temperature of +40 °C, the battery lifetime is reduced, while below -10 °C, its efficiency and performance decrease sharply.
In addition, there are peak loads as a result of boosting or recuperation of braking energy, which cause the system temperatures to rise. The temperature difference between the individual cells must also not exceed a certain value: 20 °C is optimal. In addition, the heat must be dissipated at the power electronics and at the e-motor in order to prevent damage and maintain efficiency.
In conjunction with the vehicle's air-conditioning system, electric cars consequently have a highly complex and sophisticated thermal management system made up of several cooling circuits and various cooling media systems. For that reason HELLA connects the cooling circuits for the battery, the electric motor and the vehicle interior in one unit with the so-called Coolant Control Hub (CCH). As a result of such centralisation, the CCH provides for a higher degree of efficiency, shorter charging times and also for longer ranges to be achieved. And all the thermal energies can be optimally distributed.
In modern electric cars, electric low-voltage or high-voltage heaters and air or water heaters are used to heat the interior and to condition the high-voltage batteries. With air heating, similar to the system used by a hair dryer, air flows over heating coils, which then warm it. PTC (Positive Temperature Coefficients) heating elements are used. With a water heater, water is heated in a circuit – also electrically – and in this way heat is then released into the vehicle interior.
A more efficient solution is the additional use of a heat pump. A PTC auxiliary heater is only used for high heating requirements or when heat is needed quickly. The heat pump extracts thermal energy even from the cold, outside air in winter. It is thus possible to convert up to three kilowatt-hours of energy into heat from one kilowatt-hour from the battery cells of an e-car. And it can be done even more effectively: the electric motor and the batteries themselves also generate heat, albeit to a small extent. This waste heat can also be used to augment vehicle interior heating.
Comfort and assistance systems play a central role with electric cars, too. As we know from the classic combustion engine cars, ABS, ESP, anti-slip systems (ASR) and many other ADAS are similarly integrated here. In addition, there are numerous distance control and traffic detection systems, rain-light assistants and parking aids. HELLA is the innovation leader when it comes to the relevant sensors, actuators and camera solutions and the company offers a wide range of system solutions. Moreover, HELLA focuses specifically on components that make autonomous driving safe for traffic and safe for the future at every level.
It goes without saying that the charging process is specifically electric: the electronic charge lid actuator (eLA) from HELLA, for example, aids the charging process. With the help of the charge lid actuator, more individual special functions can be integrated for extra comfort and safety. Innovative light components visualise the status of the battery and also the charging mode.
Tyres of combustion engine vehicles and those of electric cars do not basically differ. The same requirements appear in the specifications. For example, a good grip on wet roads and good braking performance are equally important. However, there are four e-specific features to mention, aspects which play a special role for electric vehicles.
-Low-noise rolling behaviour as the e-vehicle itself generates hardly any driving noise
With the e-car, there are fewer drive components that need to be regularly checked and maintained. Engine and gear oil is not needed, although non-conductive oils are used for lubrication and temperature dissipation in electric drive units. One essential aspect, however, is thermal management, which will be a focus of attention in the automotive service of the future. Experts speak of the new "oil change" for the servicing of e-cars, as it were, when it comes to maintaining the thermal management system and changing the cooling media system. In addition, it can be assumed that, for example, chassis components such as bearings or dampers are subject to higher wear. E-cars are simply heavier and sometimes have a more powerful performance.
In order to master "e-technology", mechanics in automotive workshops must undergo appropriate further training. Various qualifications are necessary in order to be allowed to work on high-voltage vehicles at all. HELLA offers comprehensive training courses for this purpose. Then there is the appropriate workshop equipment. For those who are still in some doubt, this starts with the lifting platform, which has to bear heavier weight; the workplace must also be equipped with appropriate safety precautions. The result of all this, however, is that automotive businesses will not be short of work. On the contrary: new and exciting "high voltage" tasks are just waiting for them!