Charging Infrastructure for Electric Vehicles

Introduction: 

The move to electric mobility is a promising global approach for reducing carbon emissions in the transportation industry. India is one of only a few countries to back the global EV30@30 initiative, which aims to have at least 30% of new vehicle sales be electric by 2030. To achieve this ambitious change, an accessible and reliable network of electric vehicle (EV) charging infrastructure is a must. The Indian government has implemented a number of policies to encourage the establishment of a charging infrastructure network. Given the specific qualities of this new infrastructure type, however, it is necessary to tailor it to the unique Indian transportation environment and establish stakeholder capacity to support its on-ground deployment. To enable the efficient and timely development of EV charging infrastructure that fits local requirements and is ideally integrated within the electrical supply and transportation networks, a contextual approach is required. 

Fig.1 Fast Charging Station

 

To achieve this ambitious change, an accessible and reliable network of electric vehicle (EV) charging infrastructure is a must. The Indian government has implemented a number of policies to encourage the establishment of a charging infrastructure network. Given the specific qualities of this new infrastructure type, however, it is necessary to tailor it to the unique Indian transportation environment and establish stakeholder capacity to support its on-ground deployment. To enable the efficient and timely development of EV charging infrastructure that fits local requirements and is ideally integrated within the electrical supply and transportation networks, a contextual approach is required.

Characteristics of EV Supply Chain :

The basic unit of EV charging infrastructure is the electric vehicle supply equipment (EVSE). The EVSE draws power from the local power grid and uses a control system and a connected connection to safely charge electric vehicles. User authentication, charging authorisation, information recording and exchange for network management, and data privacy and security are all possible with an EVSE control system. For all charging reasons, EVSEs with at least basic control and management functions are advised. 

The most common charging technology is conductive charging, often known as plug-in (wired) charging. The conductive charging requirements of an EVSE are determined by parameters such as vehicle type, battery capacity, charging techniques, and power ratings.

Battery specifications for different EV Segments :

Light electric vehicles (LEVs), which include two-wheelers (scooters, motorbikes) and three-wheelers, are predicted to drive transport electrification in India during the next decade (passenger and cargo). Cars and light commercial vehicles (LCVs) are the other major vehicle sectors that are being electrified. Electric buses will also be present in large numbers, however they are not included in this manual.

Electric vehicle charging needs are determined by the specifications of electric vehicle batteries, as power must be given to the battery at the correct voltage and current levels to allow charging. As indicated in Table 1, the typical capacity and voltage of EV batteries varies by EV segment.

Low-voltage batteries power the E-2Ws and e-3Ws.

Low-voltage batteries are also used in the first generation of electric vehicles. Even if they continue to be used in specialised use cases like taxis, these are likely to be phased away in the future. High-voltage batteries power the second generation of e-cars, as evidenced in upcoming e-car models. Depending on their load-carrying capacity, electric LCVs will include both low-voltage and high-voltage vehicles.

Vehicle Segment	Battery Capacity	Battery Voltage
Electric 2 wheeler	1.2-3.3 kWh	48-72V
Electric 3 wheeler	3.6-8 kWh	48-60V
E-cars (1st Generation)	21 kWh	72V
E-cars(2nd Generation)	30-80 kWh	350-500V

Table 1 : EV battery requirement

 

Charging Method and Power Ratings :

The supply of direct current (DC) to the battery pack is required for EV charging. A converter is necessary to give DC power to the battery since electrical distribution systems provide alternating current (AC) power.

Fig.2 A.C Charger

 

AC and DC charging are further divided into four charging modes, with AC charging being categorised as Modes 1-3 and DC charging as Mode 4. When using a cable and plug to connect an EV to a conventional socket outlet, Modes 1 and 2 are appropriate. Mode 1, often known as dumb charging, allows for no communication between the EV and the EVSE and is not advised for use. The portable cable used in Mode 2 is commonly utilised for home charging and has built-in protection and control capabilities. Modes 3 and 4, which employ a separate charger device to give electricity to the electric vehicle, offer better control systems and are used for commercial or public charging. 

EVSE Power Ratings :

	Power level	Current Type	Compatible EV Segment
Normal Power Charging	P<= 7KW	AC & DC	E-2Ws, e-3Ws, e-cars, other LCVs (up to 1 ton)
	7KW<P<=22KW	AC & DC
High Power Charging	22KW<P<=50KW	DC	E-cars, LCVs and MCVs (1-6 tons)
	50KW<P<=200KW	DC

Table 2: Power ratings

The input power needs for charging infrastructure are determined by the power ratings or levels of EVSEs, which are dependent on charging requirements.

Table 2 shows how EV charging is classified by power level, with regular power charging reaching 22kW and high power charging reaching 200kW. While EVSEs with power ratings up to 500kW are available worldwide, they are primarily designed for larger vehicles such as buses and trucks. For e-2Ws, e-3Ws, and e-cars, standard AC charging is sufficient. Due to the predominance of LEVs and the usage of low-voltage batteries in e-cars, normal power DC charging is unique to India. LEVs and automobiles with single phase on-board chargers can use single-phase AC chargers with a maximum power rating of 7kW. For e-cars with larger onboard chargers, three-phase AC chargers with a power rating of up to 22kW are required. High-power DC charging of 50kW is utilised for high-voltage e-cars with battery capacities ranging from 30-80kWh. DC chargers are available in power levels ranging from 25kW to 60kW. However, in the near future, higher-powered DC chargers will be accessible.

Battery Swapping :

Battery swapping, in which a low EV battery is removed from the car and replaced with a fully charged one, is an alternate battery recharging method that is gaining traction throughout the world. The technology is being tested for e-2Ws, e-3Ws, e-cars, and even e-buses, among other EV categories.

Fig.3 Swappable battery infrastructure

Types of Battery Swapping :

1. Manual :

The battery changing station is a stand-alone device that allows batteries to be manually installed and withdrawn from specific slots. Manual changing stations are modular and take up very little space. Because the battery pack sizes are smaller and the weight can be handled by one or two people, these are employed for 2W and 3W battery applications.

 

2. Autonomous:

In these sorts of switching stations, a robotic arm is used, and the battery swapping operation is semi/fully automated. 4W and e-bus applications use robotic swapping since battery packs are larger and heavier and require mechanical help. These exchanging stations are likewise more expensive and necessitate more land.

Advantages and disadvantages of Battery Swapping :

Advantages	Barriers
Recharging an electric vehicle takes only a few minutes.	There is a lack of consistency among electric vehicle batteries.
Batteries may be charged away from the swapping point, giving you greater flexibility when it comes to setting up exchange stations.	Battery pack design is not ideal for easy switching (weight, dimensions, and ergonomics)
Battery leasing replaces battery ownership, lowering the upfront cost of an electric vehicle.	To power the same number of electric vehicles, a larger number of batteries are required.
Controlled charging conditions improve battery life predictability.	Because customers want new batteries with a longer range, battery packs have a shorter commercial life.

 

Indian Standards for AC Charging:

The major EV charging standard in India is IS 17017, which is divided into three parts and six sections. IS-17017-Part-1 specifies the basic characteristics of all electric vehicle charging systems. This standard, as well as specific AC connector specifications in the IS-17017-Part-2, must be followed by an AC EVSE.

Fig.4 Charging Stations

 

The technical standards IS-17017-Parts 21 & 22 apply to both AC and DC EVSE. Additional Indian requirements for AC EVSEs have been certified for usage in parking areas by light EVs and e-cars (in the form of low-cost charging points).

Indian Standards for DC Charging:

The specifications for DC charging stations with a power output of 50kW to 200kW are described in IS-17017-Part-23. Furthermore, to accommodate buses and other big vehicles, high-power charging standards are required.

The IS-17017-Part-25, which is designed for providing low DC power of less than 7kW for light EVs, was just finalized by the BIS.

Data communication standards are provided in IS-17017-Part 24 due to the requirement of digital communications between the DC EVSE and the EV. Communications will follow the IS-15118 series when the Combined Charging System (CCS) standard is implemented, which can support both AC and DC charging.

Indian Standards for Battery Swapping :

For LEVs and buses, separate efforts have been launched to develop battery swapping standards. The battery pack form factor, interoperable connection technologies, communication between the battery management system (BMS) and the EV and charging station, and network management will all be covered in two series of standards documents. Any electric vehicle (EV) can use a battery pack that meets these requirements. AC or DC charging systems can be used to charge the removable battery packs.

Indian standards for EV roaming and grid-related management functions are yet to be developed by the BIS.

References 

[1]Government of India Ministry of Power. (2021). HANDBOOK of ELECTRIC VEHICLE CHARGING INFRASTRUCTURE IMPLEMENTATION. Retrieved December 24, 2021. 

[2]Sh. Yang, J. Yao, T. Kang, X. Zhu, “Dynamic Operation Model of the Battery Swapping Station for EV (Electric Vehicle) in Electricity Market,” (Energy, vol. 65,pp. 544–549, Feb. 2014).

[3] O. Worley, D. Klabjan, “Optimization of Battery Charging and Purchasing at Electric Vehicle Battery Swap Stations,” (IEEE Vehicle Power and Propu