Emerging Trends in EV ChargingUPDATED OCTOBER 20, 2021 - 15 MIN READ
Topic of Contents
- Different aspects of EV charging
- Comparing AC charging and DC charging
- EV charging Trends
Electric vehicles are emerging as alternate mode of transport system during the last decade. Experts believe that this industry is going to reshape the overall automobile sector in the coming years. The adoption of electric vehicle is also encouraged to achieve a sustainable environment for living. In addition, it also reduces the dependence on the imported oil for the road transport system. The last year sales data indicates that we are at the cusp of this shift towards EV Charging trends
The expansion of EV industry demands that the interrelated businesses such as charging, battery manufacturing, energy management, etc. need to be extended accordingly. Among all, the EV charging is one of the key areas which demands comprehensive planning for creating a reliable EV charging ecosystem. The government, private stakeholders and the leading charging infrastructure providers need to collaborate and put in the necessary efforts for the successful implementation of charging network across different locations in the country.
Different aspects of EV charging
Battery is integral to the successful operation in an electric vehicle. The size and capacity of the battery pack decide the charging cycle in electric vehicle. The charging requirements vary from one vehicle to another depending on the use-case scenario, type of vehicle, etc. Therefore, charging system should be selected in accordance with the following criteria:
1. Type of vehicle (private or public)
The charging demands for private and public electric vehicles are different. Usually, the public vehicle covers more distance per day as compared to a private vehicle. Most of the private vehicles such as 4 wheeler electric car will require less time and charge and therefore can be charged at home. On the other hand, the public vehicle such as 4 wheeler small bus have public charging typically for fast charging in minimum time.
2. Type of load (passenger or goods)
Charging requirements can vary depending upon whether vehicle carries passengers or goods. The passenger fleet is further classified as on-demand cab and staff transport and their charging preferences can be different. The on-demand cab driver prefer to recharge the vehicle at the public charging system whereas the staff transport vehicle can be recharged at their office premises. The EV charging is created for certain vehicles such as employees’ vehicle or transit fleets, with specific needs. The usage of these charging is limited to specific users only and not shared publicly. On the other hand, the vehicles carrying goods can be charged at a public charging station on their route.
3. Location (home, corporate premises or public places) –
The charging facilities vary for one location to another. The home charging is slowest method of charging and mostly preferred by private vehicle owners. The second category comprises corporate office charging that is faster and smarter method as compared to home charging and is manly created to provide charging facility for employee’s vehicles during the working hours. The public charging is the most expensive out of three alternatives and is located in public areas or along the highways. This facility is open to all EV drivers for charging their electric vehicles.
4. Type of battery (detachable or fixed) –
As the battery technology has improved a lot, the battery can be detached from the vehicle for reducing the waiting time for EV drivers. This helps in overcoming the two major challenges of high ownership cost of the electric vehicle and long charging time.
5. Vehicle segment (2 wheeler, 3 wheeler or 4 wheeler) -
The charging time and requirement of each segment is different. For instance, the size and capacity of battery in 2 wheeler vehicle are different from the dimensions of 3 wheeler and 4 wheeler vehicle. Accordingly, the time duration for full charging of these batteries will vary.
Comparing AC charging and DC charging
The electric vehicle needs to be connected to charging station for charging operation. The EV battery needs DC power for its functioning but the grid power is AC in nature. So, AC to DC converter and supporting circuitry is employed to covert the AC power to DC power and supply controlled DC to charge the battery. The physical location of these components for converting the power decides the type of charger:
In AC charging, this conversion takes place inside the vehicle and it is called an on-board charger. Once the connection is established between the charging station and vehicle, the charger controller starts communicating with the vehicle. The information regarding connectivity, current limits etc. are exchanged. The AC power from the grid is converted into DC power through a rectifier, inside the vehicle. The power control unit adjusts the current and voltage level of DC converter. This controls the delivery of charging power to the battery. The power control unit in turn gets input from Battery Management System (BMS) for the purpose of controlling the battery charging parameters. The BMS monitors the battery pack parameters for safe and reliable charging process and it then provide information to PCU to control charging power delivered by DC-DC converter. The safety interlocks ensure the safe charging operation and abort the process in case of improper connection and fault detection. For the convenience of charging an electric vehicle, there are some standards for the vehicle inlet and charging cable. The AC charging supports two levels of charging:
- • Level 1 Charging is the most popular type and the battery can be charged anywhere with a standard electrical outlet available at home. Level 1 charging supports 120 V and 1 hour of charging give maximum of 5 miles of range. The standard for Level 1 charging includes the Bharat AC 001, a low charging technology. Level 1 charging can simply be installed at home through a standard outlet. It is cost effective and slow method of charging.
- • Level 2 charging is another case of AC charging but it is faster as compared to Level 1 charging. This standard involves special hardware and intelligent software provisions to ensure effective use of charging facility at apartments, shopping malls and office premises. Level 2 charging supports 240 V for operation and 1 hour of charging allows a maximum of 20 miles of range. The station owner gets the information about the vehicles and owners utilising the facility.
Fig: AC Charging Process
The AC to DC conversion takes place outside the car and DC power is directly provided for the charging of the EV battery. These large power charging operations require high power and expensive circuits such as AC-DC converter, DC-DC converter and power control unit. The size of the circuit becomes large and it is difficult to implement this inside the vehicle.
Therefore, these are outside the vehicle and can be shared by multiple users. This charging process provides highest power output in minimum time, thus making the charging cost high. This type of charging supports 480 volts and 20 minutes of charging gives a maximum of 80 miles of range. Fast charging is available at public places and highways.
Fig: DC Charging
EV Charging Trends
Like the other segments in the EV industry, there is a continuous improvement undergoing in the charging systems and technology. The latest technology innovations in EV charging is providing a reliable and safe charging experience to consumers. These methods are taking care of the challenges such as long charging time, high tariffs and ownership cost in the current EV charging and allows a wider acceptance of electric vehicles in the country.
1. Inductive charging
This type of charging allows wireless charging in the electric vehicles. In inductive charging, drivers charge their vehicles by parking on specified charging spots such as parking areas, garages or driving lanes. This charging method makes use of two coils, one is underneath the ground where 220V AC is converted into high frequency AC resulting into the generation of magnetic field that cuts the second coil which is placed inside the vehicle. This produces electric current in the vehicle coil. In the car itself, this AC is converted into DC power and BMS controls the DC power for the vehicle battery. According to the motion status of the vehicle, the inductive charging can be classified as:
- • Static charging -
- • Dynamic charging –
This type of inductive charging is employed for charging of vehicle in a static condition. The static charging operation involves the use of to two electromagnetically linked coils namely primary and secondary coils. The primary coil is fitted underneath the ground, in a pad-like construction and is linked to the electricity network. The secondary coil is placed on the bottom of the car. The vehicle and the charging facility under the ground need to be aligned for the charging the EV. The charging time in static charging depends on AC supply power level, distance between the two coils and the size of the charging pad on the ground.
This type of inductive charging is employed for moving vehicles. This technology makes use of transferring power over the air The electromagnetic field produced by the primary coil arrangement under the road is picked up by the vehicles driving over them and thus charging the electric vehicle through the electricity. This is suitable for charging the vehicle continuously, while on roads and highways. Additionally, this technology also allows the use of light weight vehicles because of smaller size batteries.
2. Smart charging
The power for charging the electric vehicle is of prime importance. Therefore its effective and efficient use is vital for satisfying the charging demands of EVs in future. Smart charging technology controls the charging power through a set of intelligent functionalities incorporated in the charging environment, thereby providing flexibility, sustainability and low cost charging technique. This charging technology supports real time balancing of the girds by adjusting the charging time of EVs in accordance with the condition of power system and needs of the vehicle owners. Once the vehicle is programmed to charge at a specified time, the energy will automatically start flowing through EV only at the set time slot.
There are different types of balancing mechanisms such as V1G, V2G, V2H, V2B etc.
- • Vehicle-to-grid (V1G) is an improved version of smart charging as it allows additional features such as setting of charge rate and access energy markets for a more efficient charging process.
- • Vehicle-to-grid (V2G) is a type of smart charging which allows bidirectional flow of electrical energy from the grid to the vehicle and vice versa. This flow of energy back to grid balances the energy demand on the grid and supports efficient utilisation of energy. This technology not only encourages active way of utilizing energy but also opens up newer chemistries for drivers, fleet operators and vehicle manufacturers.
- • Vehicle-to-home (V2H) and Vehicle-to-building (V2B) are such two technologies that can play a vital role in this act of balancing the energy. These versions of Vehicle-to-everything (V2X) allow use of electricity from the battery of electric vehicle to the electrical loads at your home or building.
Fig: Vehicle-to-Grid (V2G)
There are few concerns such as limited support from roaming protocols, lack of standardization and regulatory framework and effect on battery performance that need to be addressed for using these technologies in best possible manner.
The strong government push and incentive schemes, R&D activities, up-gradation of technology, etc. in the EV sector are taking us towards the goal of a sustainable environment. The latest developments in EV charging resolve some of the major issues of traditional charging methods and improve the driver experience. The recent ways to charge an EV and development of advanced chargers offer a painless and cost effective way of charging an electric vehicle. But still there is a long way towards global electrification and the various stakeholders need to continue exploring new areas to provide more convenient, affordable and efficient way of charging an electric vehicle.
EV - Electric Vehicle
BMS - Battery Management System
PCU - Power Control Unit
V2G - Vehicle-to-grid
V2X - Vehicle-to-everything
V2H - Vehicle-to-home
V2B - Vehicle-to-building