Beware of These Electric Vehicle Charging Challenges
The batteries and charging systems associated with electric vehicles play a crucial role in determining the efficiency and cost of these vehicles. This article discusses the potential challenges of wired and wireless electric vehicle charging methods.
Battery electric vehicles (BEVs) are gaining interest due to their promising attributes. These charging technologies can be classified into two categories: wired charging technologies (contact charging) and wireless charging technologies (contactless charging). Advances have been challenging because various elements must be considered, such as an optimal structural design with fewer components, thermal safety measures, high efficiency, rapid charging, cost efficiency, etc.
Figure 1. Overall charging system for BEVs using wired/wireless charging technologies. Image used courtesy of IEEE Access
Wired Charging Technology Challenges
The following are some of the active research concerns of wired charging techniques for BEVs.
Standardization of Inlets, Plugs, Charging Types, Communication Protocols, and Safety Requirements
It is crucial to ensure more efficient charging to create a market that is sustainable, safe, and widely accepted. This can be done by unifying inlets, plugs, communication standards, charging types (i.e., types 1, 2, and 3), and safety standards, as listed in Table 1. Many companies, including Tesla, BMW, and others, have adopted these charging methods. The unification is very interesting because it might increase BEV universality and make them available everywhere, irrespective of manufacturer.
For instance, the international electrotechnical commission (IEC) and society of automotive engineers (SAE) unification standards constitute the foundation for the most popular and approved charging systems. According to SAE, IEC, Combo, and CHAdeMO, Type 1 (i.e., 1ϕ vehicle couplers that do not exceed 250 V, 32 A), Type 2 (i.e., 1ϕ or 3ϕ vehicle couplers that do not exceed 480 V, 63 A (3ϕ ) or 70 A (1ϕ) ), and Type 3 (i.e., 3ϕ vehicle couplers that do not exceed 480 V, 63 A with two pilots) are the three most often used charging types.
Table 1. Unified Items for Wired Charging Technology
SAE J1772, IEC 62196-1, IEC 62196-2, IEC 62196-3, GBT20234-2, GBT20234-3
IEC 62196-2 Type 1, IEC 62196-2 Type 2, IEC 62196-2 Type 3
SAE J2931/1, SAE J2931/2, SAE J2931/3, SAE J2931/4, SAE J2931/5, SAE J2931/6, SAE J2931/7, etc.
IEC 60529, IEC 60364-7-722, ISO 6469-3, ISO 17409, SAE JI766, SAE J2344, SAE J2929, SAE J2578, etc.
Reliable Charging Technologies
One of the significant elements in enhancing wired charging solutions for BEVs is creating and maintaining a reliable infrastructure. It can be achieved by using affordable components and effective handling of charging BEVs (i.e., improving the structure of the charging system through the use of simple topologies with a reduced number of power control switches). Hence, efforts like longer battery lifetimes and reduced maintenance requirements are being made to provide effective charging methods to increase the dependability of BEVs.
First, some crucial information (such as monitoring shared stops and daily operation hours) must be considered for the operating period to improve and reliably charge a device. To improve charging capacity, information about landmarked sites, energy grids that are not capable, and appropriate bus stops should be gathered.
Second, statistics on battery parameters and charging power are also highly crucial. For instance, the energy at charging stations is significantly influenced by various variables, such as the time specified by operational planning, the available infrastructure for charging (such as charging power and grid power), and the state of charge (SOC) or type of battery. Hence, the proper management of daily operating hours and the accurate identification of landmarked regions should be properly considered to reduce the maintenance demand and produce a battery with a longer lifespan.
Smart Charging Technology
The demand for smart charging stations has increased due to the dramatic rise in the number of EVs on the road (120 million EVs are anticipated by 2030). The wired charging infrastructure should be improved by managing the overloading of the grid, especially at night when most EVs are typically plugged in. The development of wired charging technologies by monitoring the shared data connection between BEVs and charging stations is highly demanded.
Electric vehicle charging. Image used courtesy of Pixabay
Smart charging technologies (e.g., scheduled charging, customer choice products that facilitate different electricity pricing for BEV charging, etc.) are in high demand. For instance, the owner of a charging station can efficiently manage the overload placed on the grid and optimize energy usage to monitor and control the use of their BEV systems remotely. In the end, good communication between BEVs and the charging station is crucial to improving smart charging.
Advanced Battery Management Systems
An advanced battery management system (BMS) is needed to ensure that wired charging technologies work better and the electrical energy stored in Li-ion batteries can be used safely from the first time through the end of the electrochemical system life. For example, the BMS lets consumers set the maximum charging and discharging currents (called charge maximal intensity (CMI) and discharge maximal intensity (DMI)) that the BMS can safely take in or give out at different SOCs and temperatures (T).
Different types of conventional BMS, such as cell balancing, overcharge/discharge protection, CMI, and DMI, work based on the current intensity or the amount of current that can be safely added to or taken from the battery system at any given time. On the other hand, to ensure BEVs are charged better, the intensity of the current can be accurately estimated by some recently reported advanced methods that don't need to use current sensors, adding to the cost of BEV systems as a whole.
The advanced BMS approaches are SOC-based methods that can estimate the intensity of the current based on specific model parameters. Some examples of SOC-based methods are neural network-based SOC and Kalman filter-based SOC, among others. In conclusion, the estimation-based BMS approaches must be enhanced even more to address issues such as faults between turns, self-commissioning, and other similar problems.
Wireless Charging Technology Challenges
The common power source for wireless BEVs (e.g., 3–11 kW, 11–50 kW, and >50 kW) can be installed at homes, businesses, and distribution channels. Over the past few years, the global market for EVs that can be charged wirelessly has grown, and it is expected to reach $701.38 million by 2030. Most people trust Qualcomm Inc., Continental AG, Witricity Corporation, Powermat Technologies Ltd., Elix Wireless, and other companies that make wireless BEVs.
High Power Level Transfer Capability
The power transmission capability for BEV charging using wireless charging technologies is restricted to a specified kilowatt value (about 30 kW). The capacity to transfer power levels has been improved by strengthening the magnetic field coupling between the transmitting and receiving coils. Inductive wireless charging has improved battery charging times and enabled safe, completely automated operations over the past few decades. Development efforts over the past few years have demonstrated an increased wireless power transfer capability of up to 200 kW.
Long Distance Charging Capability With Safety Concerns
Although it was mostly accomplished with near-field charging methods in previous years, wireless charging for BEVs had only been limited by a small distance (a few millimeters). Far-field charging technologies should be further developed for increased efficiency and eventually implemented globally to improve the charging distance capabilities for BEVs.
High-power wireless charging should, however, take a few safety precautions into account, such as shielding people from radiation exposure. These far-field charging solutions, though, cannot provide the most useful amount of power. For instance, only roughly 20 to 25 percent of the current used in laser charging can be transferred. The transmitter side should have a robust design to ensure a strong wave and proper use of the power utility to address the identified issues.
Optimized Static/Dynamic Wireless Charging
While becoming widely available for BEVs over the past few years, static wireless charging (SWC) technology can only occur when the BEV is on the spotting points at charging stations, street parking, etc. Hence, the advancement of dynamic wireless charging can enhance SWC-based techniques (DWC). DWC, in contrast to SWC, enables the charging of BEVs while they are in motion.
By removing any safety concerns like trip dangers and electric shock risks, recent developments in SWC (i.e., employing optimized designs of the primary/secondary pads with cutting-edge power converters and circuits) can successfully overcome the issues associated with wired-based charging systems. In DWC, BEVs are traveling over charging stations positioned beneath the roadbed. For future roadway-powered/in-motion EV systems, they are the only technologies that show promise.
This is accomplished by using a high-voltage/high-frequency AC source to embed advanced transmitter pads at a specific distance from the surface into the road's concrete. Similar to those for SWC systems, the receiver pads are positioned beneath the BEVs that will be charged. DWC should ultimately be made readily accessible in a variety of settings in the near future to successfully overcome the shortcomings of SWC.
Takeaways of Electric Vehicle Charging Challenges
This article has discussed the potential challenges of electric vehicle charging technologies. Some of the takeaways follow.
- Besides electric vehicles becoming more popular, it has been hard to make improvements to their charging systems because of the need for an optimal structural design, thermal safety measures, high efficiency, fast charging, low cost, etc.
- Standardizing of inlets, plugs, communication standards, charging types (i.e., type 1, 2 and 3), and safety requirements are important to make sure that charging works.
- To make electric vehicles more reliable, efforts are being made to provide effective and reliable charging methods, such as making batteries last longer and requiring less maintenance.
- The wired charging infrastructure should be enhanced by managing the overloading of the grid, especially at night when most electric vehicles are normally plugged in. The need for smart charging stations has risen.
- Li-ion batteries need an advanced battery management system to be used safely from the first time they are used until the end of the electrochemical system.
- The global market for electric vehicles that can be charged wirelessly has grown, and 3–11 kW, 11–50 kW, and >50 kW are the most common power sources for wireless battery electric vehicles.
- Wireless charging has cut down on the time it takes to charge a battery and made it possible for operations to be safe and fully automated. However, there are still problems, such as high power level transfer, long-distance charging, faults between turns, self-commissioning, and others.
- Dynamic wireless charging allows electric vehicles to be charged while moving. This can solve some of the problems with wired charging systems. Advanced transmitter pads are embedded using a high-voltage/high-frequency AC source to achieve this.
This post is based on an IEEE Access research article.
This article confirms that it is not a good time to buy a BEV. All their kinks have yet to be worked out which means Murphy’s laws will prevail and at a time you least expect. My advice is to wait for the Fuel cell-powered vehicles which in my opinion (backed by over 50 years of dedicated DC power systems engineering) will soon overshadow the BEVs and will eventually force them right out of the marketplace. Don’t believe me? check out the tested fuel cell-powered passenger plane. Be prepared, the fuel cell is coming. Honestly compare the pros and cons of batteries to fuel cells and your result will be stunning.