MANY ROADS LEAD TO DRIVING RANGE – ENERGY MANAGEMENT IN EVs

In EV development, improving individual automotive systems and aspects in isolation is insufficient. Without a holistic view, it will not be possible to achieve a comprehensive optimum.

One of the primary goals of developing a battery electric vehicle (BEV) is maximizing the vehicle’s driving range via optimal energy management. It is mostly determined by a combination of efficiency and battery size. However, implementing a bigger battery with greater energy reserves does improve driving range, but it also increases the overall weight of the vehicle, and therefore actually decreases efficiency. However, efficiency is an important criterion for the end customer because it determines the cost of each kilometer driven in vehicle operation.

The development team’s aim is not only to maximize the nominal range under the normal and favorable conditions of WLTP testing, but also improving the real driving range and cost factors which are relevant for the customers. High customer satisfaction can only be ensured long-term if a vehicle shows good performance in these factors, within a close range of WLTP test scores.  And that is, of course, of central interest to vehicle manufacturers.

Compared to internal combustion engine vehicles (ICE) with its multi-step transmission, electric vehicles come with significantly fewer adjusting screws within the powertrain itself to minimize real energy consumption and thus optimize driving range. Therefore, factors that influence the complete vehicle are of particular importance here. These factors include, among others, aerodynamics, reducing friction losses, and minimizing rolling resistance.

A HOLISTIC CONSIDERATION OF THE COMPLETE VEHICLE

Even if the same type of battery and power train are used, there is a significant difference in energy consumption and driving range depending on the vehicle’s basic concept and design. For example, SUVs are designed for greater spatial proportions, better aptitude for rough terrain, and powerful tractive output for pulling trailers. Of course, these use cases do not allow much leeway for energy efficiency. Hence, an SUV will never range the same efficiency levels as an aerodynamically advantageous, minimal weight vehicle optimized for high driving range.

Nonetheless, even the energy management of a vehicle with high consumption can be improved by optimizing elements of all divisions. One such approach to improve driving range is the efficient construction of the engine. In the next step, frictional resistance is minimized in the remaining power train. Then, tractive resistance (which consists of aerodynamics, rolling resistance, and complete vehicle weight) is reduced as much as possible. Thermal management also plays an important role in increasing the efficiency and therefore, the driving range of a battery electric vehicle (BEV) because unlike with ICE vehicles, energy for heating must also be borrowed from the battery.

A DRIVE FORMULA, TAILORED TO THE DESTINATION – ALL-WHEEL DRIVE CAN BE EFFICIENT

A power train’s basic concept must be suited to the needs of the intended target customer group. Hence, it should be designed in a way that solves target conflicts regarding the different customer’s expectations of the vehicle. One customer group might prefer good driving performance while another group is focused more on energy efficiency. A modular power train building block system offers a great solution for this problem. With this modular system, it is easily possible to build a version of a vehicle with one powered axle and another version of the same vehicle with two powered axles. While the vehicle with one powered axle can be offered as an entry level model build for driving range, the all-wheel drive vehicle acts as an alternative with higher overall performance. Moreover, the all-wheel drive feature provides an attractive additional selling point for any battery electric vehicle. The active torque distribution between the two drive axles presents another possibility to positively influence driving dynamics.

Optimizing power train design

On the surface, an electrified all-wheel drive has certain disadvantages conditioned by principle, like how two powered axles can increase overall weight and decrease available space within the vehicle’s design. However, higher performance potentials also enable better output levels in BEVs, since they perform better in partial load scenarios than internal combustion engine vehicles. This is already in use today with serialized vehicles. Also, even vehicles with one powered axle are usually outfitted with an overdesigned engine since the real use of BEVs incurs fewer high loads. This is especially important for constant driving as this use case is the most common type of normal driving operation.

There are more advantages to harness from all-wheel drives by decoupling one axle, for example the secondary axle, during phases of constant driving. This proves especially effective in combination with complementary rating of the primary and secondary drives.

Here, the rating of the drives occurs in a way that the efficiency sweet spots lie in different velocity ranges, which makes them complementary to each other. This way, two drives can create a far broader efficiency sweet spot through the complementary usage than only one drive ever could, resulting in a simultaneous increase of performance potential.

These advantages are of particular use to vehicle segments that need high performance anyway due to high driving range and consequently, heavier batteries. Usually, this also coincidently overlaps with vehicle use cases which are defined by higher customer expectations of traction and drive dynamics. Hence, it depends on the individual use case which solution makes more sense. However, contrary to ICE vehicles, an electric all-wheel drive can actually prove more economical.

CONVERGING NOMINAL RANGE AND REAL DRIVING RANGE

How much the WLTP nominal range and the real driving range of a BEV deviate from one another heavily depends upon usage profile: How similar is the expected vehicle usage to the standardized measurement methods according to the WLTP driven run? Generally, nominal range can be useful information for the end customer to objectively compare different vehicles. However, standardized measurements can never accurately reproduce the real vehicle usage of a specific end customer since nominal range is determined by a fixed run simulating urban traffic, rural traffic and highway traffic. That is why there can inevitably be higher values if the real usage varies from this particular route type allocation. For example, driving primarily on the highway will increase energy consumption and shorten the driving range. Thus, the aim of holistic energy management is to converge these two values in the development phase already.

The way this is achieved varies greatly depending on the vehicle’s concept and must be specified in the cooperation between OEM and development partner. On one hand, aerodynamics and the tires’ rolling resistance are much more important for vehicles meant for frequent long-distance travelling at higher velocity. On the other hand, a battery electric vehicle meant primarily for urban short-distance traffic with frequent deceleration, stagnancy, and subsequent run-ups must be optimized in terms of minimizing overall weight, maximizing the recuperation of braking energy, and optimizing energy demand for the vehicle’s A/C.

ARE TIRES PART OF ENERGY MANAGEMENT?

Minimizing tractive resistance as a central element of energy management determines the choice and design of individual vehicle components. Tires play a key role in that matter. On one hand, wheels and tires are an important design element and must match the vehicle’s overall style. On the other hand, they also heavily influence tractive resistance. This not only applies to rolling resistance itself, but also to air resistance and weight. A tire that bears on a small surface area and barely churns minimizes not only rolling resistance, but also decreases air resistance due to its low width. However, a tire with relatively hard rollover reduces driving comfort and negatively influences driving dynamics. Therefore, a higher effort must be made while developing the chassis and modulating control systems for driving dynamics to ensure an acceptable comfort experience and safe driving behavior of the vehicle. Depending on the OEM’s requirements, tradeoffs in one area are necessary in order to optimize another area.

That is why OEMs can profit greatly from a development partner like Magna since they not only provide decades-long experience in all areas of vehicle development and adjusting components, but can also validate the systems’ performance and robustness in on-location test sites and test rigs. 

THERMAL MANAGEMENT AS AN IMPORTANT ELEMENT OF ANY ENERGY STRATEGY

The design and adjustment of the thermal system plays a particularly important role in the energy management of battery electric vehicles. Since the WLTP measurements of the nominal range are run in 23°C environmental temperature and without climatization, there is no consideration for energy consumption due to the climatization of the vehicle and the electric batteries. However, this aspect can have a great impact on the real driving range since the thermal system influences both climatization and performance potential while charging and driving. On one hand, the higher energy demand due to heating the passenger cabin during cold environmental temperatures increases energy consumption and battery strain, and negatively impacts the energy balance. On the other hand, efficient battery cooling can greatly benefit fast-charging capabilities and the high-performance aptitude of the power train.

However, even in this area, compromises are necessary and must be made according to the requirements of the individual vehicle project which the OEM and development expert have defined together. Involving the development partner in an early stage of the project can not only shorten the overall development duration, but also decrease development costs since challenges and design problems can be avoided on time.

DRIVER COACHING AS A CHANCE TO IMPROVE REAL EFFICIENCY

Even when the vehicle’s systems provide all requirements for optimal energy management and maximum efficiency, the individual driver can experience a real driving range that undercuts the WLTP measured nominal range. This can happen when a battery electric vehicle is willfully or unknowingly operated by the driver in an energy-adverse fashion. This is where the so-called driver coaching via the vehicle’s infotainment systems can make a difference and exceed pure entertainment and information service in the near future. It can provide the drivers with guidance about operating the vehicle with utmost energy efficiency, by offering different driving modes like energy saving mode, normal mode or performance mode, for example.

The driver coaching will be adapted according to the chosen driving mode – for example, it can be assumed that the driver is knowingly forfeiting maximum driving range when choosing performance mode, so there will be no or less guidance from the system. On the contrary, guidance will be offered when drivers choose the energy saving mode, efficiency mode or economy mode to ensure actual optimal energy savings and maximum driving range. It can be assumed that the driver is not excepting a high-velocity driving experience while choosing these modes.

Route planning and driving habits as factors of energy management

Interconnectivity with the navigation system and observation of frequent driving habits offer further possibilities to increase real efficiency. For example, if the system detects a commuting habit of operating the vehicle for a short distance for the duration of ten minutes each morning, it may hint that the complete vehicle does not need to be fully heated up or cooled down to optimal operating temperatures, thus saving energy. In contrast, climatizing the passenger cabin and the batteries to optimal temperature makes sense if the goal of the route navigation is 300 kilometers away, since a battery in optimal operating conditions can provide more energy and improve fast-charging capabilities if necessary. Interconnectivity with route navigation and information can also improve efficiency in some cases. For example, it could determine if it is better to use the vehicle’s momentum or to increase recuperation strength for a purposeful deceleration.

In this aspect too, Magna as a development partner can act as an intersection between subsystem suppliers to ensure that the driver coaching can provide guidance for actual utmost efficiency. To provide another example, it can be more energy efficient to concentrate the passenger cabin climatization on only one seat if the vehicle is operated only by one person instead of opening the window or roof-light since this measure can decrease aerodynamics and negatively impact efficiency more than the usage of the A/C.

No exhaust gas clearing system, no multi-step gearbox: EVs are quite different from conventional ICEs in several areas, and often appear less complex than them as a result. However, thermal dynamics are the opposite: The need to integrate several additional functions and its expanded range of functions beyond passenger amenities make the BEV’s thermal system considerably more sophisticated than that of ICE variants.

BREAKING A SWEAT WHILE FAST CHARGING? – CHALLENGES OF THERMAL MANAGEMENT IN BEVs

The thermal management of a battery electric vehicle (BEV) directly influences its mileage, its charging duration, and its operational strategy. In a combustion car, the lost heat of the engine is diverted to the environment via exhaust and cooler, or it can be reused to heat the passenger cabin. Usually, the cooling energy for the cabin’s A/C is generated in an entirely separate refrigeration circuit.

In an electric vehicle however, the thermal system becomes an integral part of the vehicle’s complete system. This is because the lost heat generated by the high voltage battery cannot be directly diverted through the environmental air alone. Since its target temperature can be below the environmental temperature, the high voltage battery must be further cooled down via the refrigeration circuit.

So, on one hand thermal management systems of BEVs must be more effective overall. And on the other hand, heating and cooling the passenger cabin becomes more complex than in combustion cars. Arising challenges and their solutions will be discussed in this article.

Table of Contents:

• Development and Validation – in Simulation and on the test rig
• Fast charging as the greatest challenge of thermal management
• Heating a BEV – Will all future cars have a heat pump?
• Expedient conception prevents the need for re-development later

DEVELOPMENT AND VALIDATION – IN SIMULATION AND ON THE TEST RIG

Generally, when designing a new vehicle, the thermal system development should not start later than the concept phase. As soon as the vehicle’s basic architecture, design and performance requirements are defined, the conceptualization of the thermal system can begin. After that, the development is carried out in three stages, with the physical testing of the actual vehicle occurring in the last stage.

The simulation phase offers the most freedom to determine relevant parameters across the whole thermal management system. On the system test rig, the thermal system’s performance as well as its long-term stability is validated. For example, the robustness of oil flow in the refrigeration circuit. The compressor needs oil for lubrication, which circulates together with the cooling agent. But the more complex the system and the longer the lines, the more oil will accumulate and settle throughout the system – and will then be missing from the compressor.

Consequently, it is of utmost importance to identify potential challenges beforehand so the system can interfere in time in case of danger, even from the software side.

Expertise and the right equipment make all the difference

Magna can provide new entrants into the BEV market with everything they need to develop a new vehicle. Established OEMs have the goal of using available system concepts from already serially produced vehicles, even for new models.

However, an already existing system cannot be fully integrated into a different vehicle, and many components must be re-constructed and re-developed from scratch. This can be the case if vehicle requirements change or if the vehicle’s installation space makes it necessary to rearrange components due to the car’s design. Even changing the conduits may require redoing preliminary validation of the overall system to prevent problems during the installation process.

For this reason, Magna has developed an intricate system test rig with two independent, but couplable climate chambers for comprehensive validation. The rig can reproduce any imaginable scenario of thermal management, even especially challenging constellations of high environmental temperature, a cabin with intense need for cooling and active fast charging at the same time.

FAST CHARGING AS THE GREATEST CHALLENGE OF THERMAL MANAGEMENT

When constructing the thermal system, the combination of fast charging the traction battery and maintaining the driver’s cabin comfort poses the greatest challenge. This is because the battery generates a large amount of heat that needs to be diverted when fast charging. At the same time, it is in the passenger’s interest to keep the cabin nicely climatized.

Therefore, compromises need to be made. An enormous cooling system would be required to keep the battery at optimal operating temperature while fast charging, especially during high environmental temperatures and while simultaneously cooling the cabin. Depending on the manufacturer’s requirements, the middle ground needs to be found or a decision needs to be made: Should charging times be extended or does the passenger compromise for less comfort?

Of course, the vehicle’s target group focus plays a major role in these types of decisions. A comfortable upper-class vehicle cannot compromise on cabin comfort as much as an inexpensive car can.

Higher power output does not have to come with lower efficiency

Another challenge for the thermal management system is the combination of a higher demand for power output with a lower target temperature inside the driver’s cabin. Usually, the cabin is cooled down by inlet air between 2°C and 10°C, which causes low pressure and hence, low density in the cooling agent.

This decreases its efficiency and means that the cooling agent compressor has to have greater dimensions or be able to spin much faster. The battery cooling requires higher target temperatures, and due to the suction pressure, the system can work more efficiently and perform better.

In principle, the regulation in EVs is facilitated by electrically powered scroll compressors. Their performance can be regulated directly and electrically over a wide area, contrary to the belt drive-powered combustion vehicle, which is regulated through valves on the piston compressors. Spiral compressors excel due to better regulation and quieter operation, which is especially important for BEVs.

HEATING A BEV – WILL ALL FUTURE BEVS HAVE A HEAT PUMP?

Heating the BEV’s driver’s cabin usually poses no problem. However, truly efficient heating is a different topic. At first glance, the solution seems simple enough: A high voltage heater immediately generates warm air. This principle works in both a parked and a driving car and enables a heating behavior that has not been possible with conventional vehicles.

Additionally, the maximum demand for heat can be reduced through preconditioning. In simple thermal management systems, the battery’s lost heat is diverted towards the environment. However, this thermal energy can be reused by utilizing it for the cabin’s heating via a heat pump. This way, either the heat pump’s condenser warms the cooling agent’s circuit, which heats the cabin’s air through a recuperator like in petrol-fueled cars, or a cooling agent condenser in the A/C transfers the lost heat directly to the cabin.

Fitting use cases for heat pumps

From the perspective of thermodynamics, a heat pump seems to be the ideal solution for cabin heating because it utilizes the electrical propulsion system’s lost heat. In practice, a heat pump is not applicable for every use case – at least not as the only thermal management system. A heat pump can fully make use of its advantages when the vehicle is driven for longer distances and is seldom parked.

Its theoretical advantages do not come into play with short distance driving or typical commuting behavior. Depending on the implemented type of heat pump system, the slower warm-up phase can have negative effects on efficiency. Components and fluids have to reach operational temperature until usable thermal energy becomes available. This process takes a certain amount of time and requires a certain amount of energy itself. In contrast, high voltage heating can provide thermal output immediately after turn-on and therefore, provides unbeatable comfort.

As the sole thermal management system, the heat pump cannot completely satisfy, especially since the increased complexity also raises overall costs. Consequently, high voltage heating is still viable for short-haul vehicle classes. For vehicles in more expensive market segments, a combination is used to provide both swift heating for the driver’s cabin through resistance heating, and a heat pump for efficient thermal management while driving long distances. Ideally, the end customer does not notice the switching between both systems and only enjoys their seamlessly interconnected benefits.

EXPEDIENT CONCEPTION PREVENTS THE NEED OF RE-DEVELOPMENT LATER

An extensively competent development partner can make the best use of, and even possibly shorten, the required development time frame if they are included in the process as soon as possible. In cooperation with the OEM, they can help identify optimal conception and construction of thermal management systems regarding the specific use case. In doing so, it is generally wise to reduce the number of variants. Sensibly defined requirements account for satisfactory impact on all target markets.

EV CHARGING TECHNOLOGY AS KEY FACTOR FOR POSITIVE USER EXPERIENCE

Many people are pleased by the driving experience in an EV car. It offers spontaneous power generation, quiet driving, and little drive vibration. Additionally, there is the reassurance that operating an emission-free vehicle is helping preserve the environment. However, EV charging technology is often perceived as tiresome and time-consuming. The customer is still confronted with charging stations that are difficult to find and charging elements can occasionally be in the wrong place. Even activating the charging point can cost a lot of time and be an annoyance. That is because there are no EV charging standards regarding associated authorization and payment options – in Germany or internationally.

A more user-friendly EV charging system tailored to market and customer needs is crucial for increasing the acceptance of electric vehicles among end customers. An optimal charging strategy not only guarantees a fast, simple, and convenient charging process for end customers, it can also be a decisive contribution to an optimal overall EV operating strategy. With the appropriate equipment, EVs could even help stabilize the public energy supply in the future.

Nonetheless, automatically self-charging EVs remain a vision for the foreseeable future. There have been a wide variety of concepts for EV charging technology for years, ranging from inductive charging loops embedded in the road to solar self-charging vehicles. In the near future, however, there will be no alternative to conductive charging like plugging the charging cable into the parked vehicle.

CONDUCTIVE CHARGING - THE FUTURE METHOD OF CHOICE

In recent years, there has been a rising focus on expanding the range of EVs with a single battery charge. This was primarily achieved by installing increasingly larger energy storage systems, although the physical limits are being exhausted with the current technology. Even though this continuous development enables ever higher energy densities, large, heavy batteries negatively affect the overall energy requirements of vehicles. To make EVs as viable for long-distance journeys as combustion vehicles, the charging process itself is gaining importance. Fast and convenient recharging on longer journeys is particularly important because short breaks in the journey could be used to replenish energy supplies.

The practical relevance of charging speed is not only determined by the maximum charging power, but also by the range regained per unit of time. Future EV charging technology will solve how many additional kilometers can be recharged “into the EV” during a charging break. For the customer, the final “gross time cost” for the charging break is decisive, from driving up to the charging point, to unplugging and continuing the drive. That is why seemingly marginal aspects such as the best possible positioning and accessibility of the charging connection on the car are also important. Of course, the matter of authentication and payment at the charging station could also be more irritating than convenient.

The perfect solution for these problems is the so-called Plug & Charge function. Here, the charging process starts automatically after plugging in the charging cable, as well as user recognition and billing. With this, there is no need for further user action.

AUTOMATIC EV CHARGING TECHNOLOGY - THE FULLY SELF-CHARGING CAR

Fully automatic charging is the solution to the most convenient EV experience for the customer. As an extension to Plug & Charge with automatic authentication, the EV can also independently connect to the charging device. Stationary charging robots are not only suitable for public charging stations, but are especially suited for private charging points at home. The charging cable is automatically led to the vehicle's port and connected to it. Technically, the best solution is attaching the designated charging point to the underside of the EV. That way, the charging cable can be plugged into the vehicle from below.

For automated charging in public parking garages, concepts with mobile charging robots that approach the vehicles autonomously are also conceivable. However, recharging the EV is limited by the energy storage capacity built into the robot. A full charge could potentially require several charging cycles.

Another challenge in automated conductive charging is the lack of (international) EV charging standards. There is currently no uniform standard for either the position of the vehicle-side charging plug or its type. Manufacturers must therefore adapt their EV charging technology to respective regional conditions. This can be especially problematic for an electric vehicle that is being developed for the global market. Right now, implementation of EV charging still depends on prevalent practice in the respective regions and the arrangement and design of existing charging stations.

TREND TOWARDS DRIVE-BY-CHARGING PILLARS

Another strong trend in the development of EV charging infrastructure is increasingly changing from current approachable charging points towards drive-by charging stations. These charging stations are approached from the side rather than the usual front, not unlike conventional gas stations. Thus, charging connections will have to be accordingly positioned on the side of the vehicle. However, this seemingly trivial aspect must be considered as early in development as the basic EV architecture.

To incorporate these requirements, developers must possess local market knowledge, as existing EV charging standards vary greatly around the world. An EV with difficult to reach charging elements will face little acceptance in the respective market. As a solution, it is possible to attach different charging connections for maximum adaptability. For example, an EV could be outfitted with both the AC connection on one side of the vehicle and the DC connection on the other. These design decisions must be made together with the OEM, depending on the market prioritization and cost specifications.

CONNECTION & COMMUNICATION - A VARIETY OF SYSTEMS

The variety of different plug systems is almost as diverse as their positions when it comes to EV charging technology. The four or five most common plug types are quite easy to assign regionally. In Europe and the US, two variants of the Combined Charging System (CCS) are used – CCS1 and CCS2. There, the two charging variants, alternating current (AC) and direct current (DC), are combined in a single charging connection at the side of the EV. However, the type 1 plug used in the US is only suitable for single-phase AC charging, while the European type 2 plug is also suitable for three-phase AC charging. Hence, different cabling on the vehicle side is required.

For DC fast charging, the two AC plug types are further expanded by two additional pins and thus become CCS1 or CCS2 plugs, respectively. With both CCS variants, the communication between the charging station and the EV always takes place via a powerline system and according to the same communication protocol. However, a conflation and standardization of the two CCS systems with uniform plugs is not in sight in the near future. Due to the different AC charging capabilities of type 1 and type 2 plugs, adaptation is also difficult to achieve.

MAGNA’S INSIGHT INTO LOCAL AND GLOBAL MARKETS & REQUIREMENTS

In Asia, the prevalent EV charging standards are the Japanese CHAdeMO and the Chinese GB/T. Both standards basically use the same Controller Area Network (CAN) bus-based data exchange between charging station and vehicle. However, the plugs themselves look and work differently. But efforts to merge the CHAdeMO and GB/T standard into the ChaoJi standard using the same connector and communication protocol have already begun.

It is also worth mentioning that some manufacturers pursue their own isolated EV charging technology that is solely suitable for their own vehicles and charging stations. Nonetheless, the manufacturer's own charging parks are usually also accessible to other vehicles.

Further standardization across continents is not likely to happen. Therefore, OEMs must offer different charging options depending on the market. As a development partner, Magna has the advantage of having local market insight around the globe. In addition, there are also deviations from charging station to charging station even within the same charging system. That is because existing EV charging standards and their implementation leave a certain amount of leeway. This means that a high validation effort for the different markets is required. Magna is a member of both the CCS and the CHAdeMO consortium, has development facilities in all relevant regions, and as such, is very familiar with the respective requirements to ensure reliable function on any EV charging technology.

BIDIRECTIONAL POWER TRANSFER - VEHICLE AS MOBILE STORAGE

The current feeling of insecurity regarding energy supply draws more attention to the possibility of using the vehicle itself as a type of mobile energy store. The vehicle can serve as a personal backup energy storage if temporary failure of external power suppliers occurs. It can also serve as a buffer storage for grid stabilization for the energy supplier. This makes the so-called bidirectional power transfer increasingly attractive. The interaction between EV and energy infrastructure must be possible, both for the vehicle itself and for the network-side wall box.

The possibility of not only charging energy into the EV, but also removing it from its storage opens up four different usage scenarios:

• Easy and convenient off-grid supply of electrical devices
  e.g., in the leisure and camping sector (charging electronic devices and e-bikes, operating cooling and heating devices)
• Vehicle-to-vehicle connection (V2V)
  e.g., emergency charging of broken-down EVs
• Vehicle-to-house integration (V2H)
  e.g., to supply an energy self-sufficient home in the event that solar or wind power systems supply less power than currently required
• Vehicle-to-grid function (V2G)

VEHICLE-TO-GRID FUNCTION BENEFITS PUBLIC ENERGY SUPPLIERS

The vehicle-to-grid function (V2G) is of particular interest to public energy suppliers, because the EV can feed energy back into the public grid and thus increase its stability. Energy supply companies can then outsource part of their load management to private individuals. However, this requires full external control of the charging and discharging process of the vehicle battery, which can pose problems for the customer.

If a lot of energy has just been taken from the traction battery to stabilize the grid, the EV’s immediate use can become limited. Frequent and externally controlled removal of energy can also put the battery in an unfavorable charging state. Being in this charging state frequently can negatively affect the service life of the energy storage device. For this reason, both the end customer and the energy supplier must find a compromise that is attractive, or at least acceptable, to both parties.

INTEGRATION OF EV CHARGING TECHNOLOGY INTO ON-BOARD-SYSTEMS

An optimal overall operating strategy for battery electric vehicles requires carefully thinking about EV charging technology. It is important not only to consider optimal battery conditioning, but also to choose the right moment for charging.

For example, efficiency can be increased by charging the vehicle in cool ambient temperatures immediately after arriving at the destination. In this case, the battery still has its optimal operating temperature and does not have to be preheated again, which requires a lot of energy. In contrast, if outside temperatures are high, it may be advisable to charge after the battery has had time to cool down. Intelligent networking of the charging system with the EV’s on-board infotainment system can help the customer choose the optimal moment for charging. The system itself could make suggestions to either start the charging process immediately or to carry it out at a later time.

Integrating charging strategy into the complete vehicle system offers advantages when planning longer journeys while also improving charging speed effectiveness. The system not only takes the most traffic-efficient route into account but can also consider the optimal distribution of charging breaks depending on the individual driving style and resulting energy consumption. Drivers are not only guided to free suitable charging stations, but the system also reserves a charging point there in advance. This way, driving breaks are used as best as possible for optimal recharging.

INDUCTIVE & SOLAR - VISIONS FOR FUTURE EV CHARGING TECHNOLOGY

In addition to wired charging, there are more EV charging technologies that are being developed and tested. The idea of ​​quickly exchanging batteries at special exchange stations was considered promising at first, but lost importance due to faster conventional wired charging. The time saved by replacing the battery compared to charging the built-in, optimally conditioned storage system did not justify setting up a network of exchange stations. Hence, battery exchange concepts are unlikely to be significant in the future.

Inductive Charging

Concepts for wireless charging are in development and some are already being tested in pilot systems for special applications. Inductive charging, which is already used to charge mobile phones and other devices, seems very promising. So far, however, only single-point solutions have been possible since EV and infrastructure must be perfectly compatible. This concept is most attractive for exceptional cases, such as bus services and taxis. In the future, it could also be a viable option for autonomous local transportation or commuting systems. Automated charging systems with overhead line sections to which electric buses can be connected are already being evaluated.

Solar Power

Another innovative idea is to equip the EV with on-board solar systems and to integrate photovoltaic cells into parts of the top hat. When the vehicle is parked in sunlight, energy can be generated. This way, at least a certain share of the daily driving range could be covered by solar power. However, solar energy can only sufficiently cover the EV’s entire energy demand in exceptional cases. Nevertheless, such visionary ideas should be considered in the development of future EV charging technologies.

CONSIDER CHARGING SYSTEMS AS EARLY AS POSSIBLE IN VEHICLE DEVELOPMENT

In any case, the development of EV charging systems should be integrated into the complete vehicle development as early as possible. Desired charging times are particularly important because they are influenced both by the components’ dimensions as well as their interaction with thermal management. Due to a high degree of flexibility, an experienced development partner like Magna can help OEMs put together a coherent complete vehicle concept – whether it is a new entrant into e-mobility or if existing elements and assemblies need to be integrated into a new vehicle. Magna has expertise in all areas and stages of development – not only in ​​alternative drives.

The vehicle of the future is increasingly software-defined. From central driving functions to sophisticated comfort functions, the vehicle will be comprehensively controlled by the Vehicle Control Unit (VCU). In BEVs, this digital control center must perform even more tasks in addition to drive control.