Electromobility enters potentially most critical phase in terms of mass adoption. The key factor here is the charging infrastructure, including its intelligent functions. One of the biggest challenges is to integrate them into official standards and specifications.
E-mobility offers the opportunity for a comprehensive transformation away from the internal combustion engine. The key factor here is the charging infrastructure with intelligent functions, for which there is still a lack of official standards and specifications. (image: shutterstock 1771562054)
Everything about the charging station of the future
electric vehicles promise a more ecological transportation system than the previous combustion vehicles. However, there are still a number of hurdles to overcome before electromobility actually becomes a mass market. Issues of charging standards compatibility and uniform technical specifications are still not conclusively resolved, which, among other things, also complicates the testing of charging infrastructure. In addition, more and more new functions are being added, e.g., for the electric vehicle.B. Smart charging, automatic connection devices or high-power charging. Industry and standardization bodies are now struggling to integrate new functions into official standards and specifications, while also ensuring backward compatibility.
E-mobility offers the opportunity for a comprehensive transformation away from mobility based on fossil fuels to mobility based on renewable energies. National and international policy frameworks aimed at supporting the deployment of EV supply equipment (EVSE) are driving the growth of the EV charging market. Countries such as germany, china, the netherlands and france are some of the key nations that are expanding their EV charging infrastructure through various policy support measures.
For example, germany is pursuing a target of 50.000 additional fast and standard charging stations, so that the next fast charging station can be reached within ten minutes. In addition, a public fast-charging network with 1,000 sites is to be established by the end of 2023. This fast-charging network is to consist of several charging points per location, each offering a minimum power of 150 kw. This makes long-distance driving and fast charging in densely populated areas possible without any problems.
However, the current reality is sobering. In the fourth quarter of 2020, the German charging infrastructure will comprise around 35.600 charging stations. In order to achieve these ambitious goals, the federal government has introduced numerous measures to promote e-mobility in recent years. This includes z. B. The purchase premium for e-vehicles, the vehicle tax exemption and the electromobility act. The political framework conditions have u.A. Leading to a record number of new registrations of e-vehicles in germany. In 2020, around 194.200 battery electric vehicles (bevs) newly registered, about three times as many as the previous year (2019 worldwide about 2.320.000).
Why charging station compatibility is still a problem
As the battery capacity of newer mid-range evs reaches 60 to 80 kwh, range anxiety plays an increasingly minor role. But this superior range and the aforementioned rapid growth in overall public EVSE deployments are now leading to e-mobility taking over the global mass market, if implementation is mature enough. To make internal combustion engine cars completely obsolete, e-vehicles need to have a really long range. For this, an e-driver must be able to rely on the next charging station on his route being operational and compatible with his vehicle. This may sound trivial, but in reality it is very complex to realize.
While most of the relevant normative specifications were published between 2014 and 2015 (Fig. 1), they did not include corresponding tests to verify the conformity of implementation. In the following, we will take a closer look at the combined charging system (CCS) charging protocol, as it is the de facto standard in europe and north america and is achieving greater market acceptance in other countries outside Japan and china.
2021, amid a wave of evs of the 2. generation of all major automakers, charging interoperability issues are not yet solved. The reason is clear: a CCS charging interface is very complex, as it involves high voltage and the transmission of a significant amount of electrical energy. Second: the design of cars is done according to specific automotive standards, while the charging infrastructure follows more generic electrotechnical standards.
As a result, the technical specification for DC charging of evs is divided into several documents from the IEC (international electrotechnical commission), the ISO (international organization for standardization) and the DIN (deutsches institut fur normung). Figure 1 illustrates the most relevant standards in terms of interoperability for conductive charging with CCS (simplified, as z. B. Mechanical compatibility of plugs and EMC are not considered).
As can be seen, there is still no conformance test specification that addresses EV and EVSE system and safety requirements in addition to communication protocols. This means that all currently established CCS products cannot be subjected to harmonized testing.
Fortunately, this will soon change. The main industrial stakeholders involved in the charging interface initiative e.V. (charin) are organized, publish an interoperability test program shortly. It will initially focus on EVSE compliance testing and will allow oems to test their products.
Figure 1: the most relevant standards in terms of interoperability for conductive charging with CCS and their chronological order. (image: keysight)
Outlook for the near future of charging stations for e-cars
While the focus is on today’s interoperability challenges, the e-mobility market is already seeking new developments and technologies to achieve two overarching goals: to become mass-market and "green". The aim is to offer the e-driver a comfortable experience when charging his e-vehicle that is comparable to the familiar refueling of internal combustion engines. Relevant concepts in this case are easy access and communication between the electric vehicle and the charging station that is as automated as possible, as well as the shortest possible charging time.
How plug and charge simplifies the charging of e-cars
Currently, e-vehicles must be identified at the charging station by RFID (radio frequency identification) cards or other means by the e-vehicle driver in order to verify, initiate, and successfully make a payment for a charging session. This process is error-prone and cumbersome, as many different means of identification and payment services exist on the market. With plug and charge, specified in the ISO 15118 series, the process of identification and payment will be automated so that the EV driver only has to plug the charging cable into his vehicle.
To support such a feature, charging communication and especially payment information must be encrypted to provide the user with a secure charging experience. In addition, payment information must also be securely communicated via the backend infrastructure to other parties involved, further increasing the complexity of the ecosystem.
A second step toward automating EV charging is wireless charging. If no charging cable is needed, the EV driver only has to park his vehicle and the charging process, communication and energy transfer, will happen automatically.
Plug& charge: that’s where the e-car charging infrastructure is heading
On the one hand, the charging infrastructure should grow as quickly as possible. On the other hand, charging stations should also be intelligent and convenient – and thus be able to do today what will only be introduced on the vehicle side with the next generation. What is needed are suitable solutions – including plug& charge. Read here what these look like.
How smart charging will help achieve CO2 neutrality
To fulfill the idea of CO2 neutrality, intelligent charging is an important aspect. Smart charging describes the scheduling of charging processes for electric vehicles, controlled by intelligent load management. Criteria for control are the (minimum) amount of energy needed by the connected vehicle to enable the owner/user’s range or to minimize the total power consumption in the grid. The challenge of such load balancing is the complexity and degree of difficulty of control when dealing with numerous connected charging points and fluctuating amounts of renewable energy such as sun or wind.
Such relatively unpredictable fluctuations in renewable energy sources require buffers. EV batteries can make an important contribution in such situations if they are regarded as energy storage systems. This enables scenarios such as vehicle to grid (V2G) or vehicle to home (V2H), where the EV battery serves as a power source for other household consumers when renewable energy sources are limited or cannot provide the amount of energy needed. When energy consumption is reported to the grid operator via smart meters and an IT cloud system, evs and their batteries also help minimize spikes in conventional power generation (figure 2).
Figure 2: electric vehicles and their batteries can help minimize peaks in conventional energy generation. Vehicle to grid and vehicle to home are such concepts. (image: keysight)
Automated charging without getting out of the car increases user comfort
With conductive charging, the next logical step in increasing user comfort is to eliminate the need to get out of the car and plug the charging gun into the car, which would be particularly inconvenient in cold or wet weather conditions. In addition, DC charging can be cumbersome to handle due to the weight and stiffness of the cable.
Therefore, the upcoming ISO 15118-20 standard will introduce support for automatic connection devices (ACD), which can be implemented in a number of ways (e.g. B. current collector, specific underbody connector or conventional connector plugged in by a robotic system).
High-power charging reduces charging time
An additional aspect when comparing fueling an internal combustion engine with charging an electric vehicle is the charging time. The charin e.V. Currently provides a classification for CCS, called DC CCS power classes, starting with power class DC5 and ending with HPC350, for 5 kw and. 350 kw maximum charging power. Charging voltages are specified at a maximum of 920 V and currents of 500 A (DC). Chaoji-1/-2, a new charging standard developed by chinese and japanese institutions to replace the previous GB/T and chademo standards, specifies a maximum charging power of 900 kw, at 1500 V and 600 A (DC).
These significantly increased DC charging currents are still manageable thanks to liquid-cooled charging cables, which are sufficiently light and flexible compared to conventional variants. In combination with the doubling of the battery voltage, the typical charging time can be decisively reduced to a conventional refueling time (Fig. 3).
Fig. 3: typical charging times depending on the power of the charging station. In combination with the doubling of the battery voltage, times similar to a conventional refueling time can be achieved. (image: keysight)
Fast-charging technology for e-cars with up to 1.000 kilowatts
TH lubeck has developed a fast-charging technology for electric cars that can charge batteries with up to 1.000 kw can be fully charged within a few minutes. Now a practical e-charging station is being developed and tested. Read here how this can work.
Commercial vehicles should also be able to be charged
When people talk about the challenges of e-mobility today, the focus is usually on passenger cars with an electrified powertrain. While there are many existing DC charging standards, none is sufficient to charge commercial vehicles in a reasonable amount of time. to charge a vehicle battery of 200 to 600 kwh in 20 to 30 minutes (the charging time requested by the user), a power of more than 1 MW and a current of more than 1000 A is required.
For this reason, the truck and bus industry is trying to create a new solution for charging their heavy electric vehicles. Due to the need for a plug for charging electric commercial vehicles, charin initiated the megawatt charging system (MCS) working group back in 2018 to fulfill a holistic system approach based on CCS. Currently discussed technical requirements for a global MCS are a maximum of 1500 V and 3000 A (DC), which is based on PLC + ISO/IEC 15118, but only as a single conductive plug.
What the charging station of the future could bring
In summary, e-mobility is entering potentially the most critical phase in terms of mass adoption, and charging infrastructure is a key factor in this. Thanks to government policies and huge investments, the total number of charging points, including very high-capacity, long-distance charging stations, will increase massively by 2025.
Intelligent new features are expected to transform what has often been an inconvenient loading experience into a seamless and highly automated one that is far superior to visiting a gas station. But to get there, you have to face an invisible but crucial challenge. Industry and standardization bodies are struggling to integrate all these new advanced smart charging features into official standards and specifications while maintaining backward compatibility with products already set up.
Keysight develops test solutions for evs and evses. With its scienlab charging test solutions, keysight enables automotive manufacturers and charging station providers to test charging interfaces of evs and evses during the charging process with high performance.