/ /

Electric Vehicle On-board Chargers and Charging Stations

Jan 03,2023 | TCcharger

As the arena is gearing as much as unharness an EV revolution, it is nonetheless actual that the charge of adaption is slow. Electric powered motors (EVs) despite being a greener, smoother and inexpensive mode of transport does now not seem to be practical but. The reason is two words, price and ecosystem. Currently EV’s are priced substantially at par with gasoline cars making it a much less enormous choice for customers, the advancement in battery era and authorities schemes are predicted to carry down the cost of EV in future.

The second one element could be, there's no proper ecosystem for the shoppers to use an electric powered car without a great deal problem. With “surroundings” i am regarding the charging stations to rate your EV when you run out of battery juice. Imagine the usage of a gasoline automobile when you have no gas stations on your town and the handiest vicinity you could replenish is you home, including to that you will need not less than 6-eight hours to rate a normal EV. Many businesses like Tesla, EVgo, charge point and so forth have already stated this problem by putting in charging stations across the usa. With international locations like Netherland, who promised to give up petrol engine with the aid of 2035 it's far positive that the roads of destiny will get replaced with EVs over inner combustion engines and  quite a few EV charging stations might pop up around us.

But, how does a EV charging stations work? Can a unmarried charging station fee all varieties of electric powered motors? What are the varieties of electric car charger? What protocols are observed for EV chargers? In this newsletter we will talk the solution for these types of questions and additionally understand what constitutes an electric automobile Charging Station and the subsystems in the back of it. Before going in addition you ought to read approximately  the batteries used in electric powered car and how Battery control gadget works inside Electrics car.


Electric Vehicle Supply Equipment (EVSE)

The equipments that represent an electric vehicle Charging Station are together called an electric car delivery device (EVSE). The term is extra famous, and it refers not anything but to the charging stations. A few human beings additionally refer it as ECS which stands for electric-powered charging station.

An EVSE is designed and engineered to charge a battery % via using the grid for energy delivery; those battery packs is probably found in an electric automobile (EV) or in a Plug-in electric-powered vehicle (PEV). The energy, connector, and protocol for these EVSEs will range primarily based on it design which we are able to talk in this newsletter.


On-Board Chargers and Charging Stations

Earlier than we step into charging stations it is essential to recognize what's gift in the EV and to which element the charger can be related to. Most EVs nowadays come with an On-Board charger (OBC) and the producer also presents a Charger along side the vehicle. These chargers at the side of the on-board charger can be used by the patron to rate his EV from his house energy outlet as quickly as he/she receives it domestic. But those chargers are very fundamental and do not come with any advanced features and therefore would typically take round 8 hours to fee a typical EV.

Types of EV Charging Stations (EVSE)

Charging Stations can be broadly classified into  types, AC charging Station and DC charging Station.

An AC charging Station because the name implies offers AC power shape the grid to the EV which is then converted to DC the usage of the On-board charger to price the car. These chargers are also known as the level 1 and degree 2 Chargers that is utilized in residential and commercial places. The benefit of an AC charging station is that the on-board charger will regulate the voltage and modern-day as required for the EV as a result it isn't always mandatory for the charging station to talk to the EV. The drawback is its low output power which growth the charging time. An average AC charging machine is show within the under picture. As we will see the AC from grid is supplied at once to OBC through EVSE, the OBC then converts it to DC and chargers the battery thru the BMS. The Pilot twine is used to experience the form of charger related to the EV and set the desired enter contemporary for the OBC. We will discuss greater on this later.

Types of EV Charging Stations Level 1 and 2

A DC charging Station gets AC energy form the grid and converts it to DC voltage and uses it charge the  Battery percent without delay with the aid of by way of-passing the On-board Charger (OBS). Those chargers commonly output excessive voltage of upto 600V and current upto 400A which enables the EV to be charged in much less than 30 minutes in comparison with eight-16 hours on AC charger. These are also known as stage 3 chargers and generally known as DC fast Chargers (DCFC) or high-quality chargers. The gain of this type of charger is its speedy charging time while the downside is its complicated engineering wherein it wishes to speak with EV to fee it correctly and appropriately. An ordinary DC charging system is shown beneath, as you may see the EVSE affords DC immediately to Battery p.C. Bypassing the OBS. The EVSE is organized in stacks to offer excessive modern-day a unmarried stack will no longer be able to offer high modern due to energy transfer limitations.

Types of EV Charging Stations Level 3 and 4

Typically the level 1 chargers are intended for residential use, these are the chargers which are furnished via the producers along side the EV which may be used to charge the EV through widespread residence power outlets. So they work on unmarried phase AC supply and might output everywhere among 12A to 16A and takes approximately 17 hours to rate an EV of 24kWH. A degree 1 charger has now not much role in charging stations.

The extent 2 charger is provided as an update for stage 1 charger it could both be set up in residence, on special request supplied the house has split section electricity deliver or can be used in public/industrial charging stations as nicely. Those chargers can offer upto 80A output modern due to its excessive enter voltage and might fee an EV in 8 hours. The level 3 charger or amazing chargers are meant for public charging stations by myself. They require poly section AC enter from the grid and eat extra than 240 kW which almost 10 instances greater than a standard air con unit in our home. So those chargers require unique permission from the grid to function.

The level 2 and level three chargers are taken into consideration to be extra efficient than the extent 1 charger because the AC/DC and DC/DC conversion takes location in the EVSE itself. Due to the huge length and complexity of a degree 2 and degree 3 chargers they can not be constructed inside a EV as it might increase the load and decrease the efficiency of the EV.

Charging Station Type

Charger Level

AC Supply Voltage and Current

Charger Power

Time to charge a 24kWH battery Pack

AC charging Station

Level 1 - Residential

Single Phase – 120/230V and ~12 to 16A

~1.44 kW to ~1.92kW

~ 17 Hours

AC charging Station

Level 2 - Commercial

Split Phase – 208/240V and ~15 to 80A

~3.1 kW to ~19.2 kW

~ 8 Hours

DC charging Station

Level 3 – Supercharger

Single Phase – 300/600V and ~400A

~120 kW to ~240 kW

~ 30 minutes

Types of EV Charging Connectors

Similar to the Europeans function at 220V 50Hz and the individuals operate at 110V 60Hz the EVs additionally have special varieties of charging connectors based totally on the usa it's far synthetic shape. This has result in confusion amongst ESVE manufacturers as they cannot be made everyday effortlessly for all EVs. The primary classifications of Connectors for AC chargers and DC chargers is given underneath.

AC Charging Sockets for Electric Vehicle:

AC Charging Sockets for Electric Vehicle

Most of the three the maximum not unusual type of AC charging socket is the JSAE1772 socket with is famous in North the us. As you can see the Plug /connector have a couple of connections the 3 broad pins are for section, impartial and ground at the same time as the 2 small pins are used for communication between the Charger and the EV (Pilot Interface), we can speak extra about this later. The Mennekes or VDE-AR-E is used in Europe for three segment AC charging device and subsequently can output high strength upto 44kW. The Le-Grand is likewise a similar socket with protection shutter to save you debris from coming into the charging socket. According to technical requirements most effective the HSAE 1772 and the VDE-AR-E sockets are advised for use in all AC chargers of future.

DC Charging Sockets for Electrical Vehicle:

DC Charging Sockets for Electric Vehicle

On the DC charger Side we have the CHAdeMO charger socket which is the most popular type of socket. It was introduced by Japan and soon adapted by France and Korea. Today most EVs like the Nissan Leaf, Kia etc have these types of sockets. The socket has two broad pins for the DC power rails and communication pins for CAN protocol. As we know Level 3 DC chargers do not use the on-board charger and hence have to provide the required voltage and current for the battery pack of the EV by itself. This is done by establishing a communication link (Pilot link) though Control Area Network (CAN) protocol with the BMS of the battery pack. The BMS then instructs the Charger to begin the charging process, monitors it and then requests the charger to stop charging.

CHAdeMO charger socket

The Tesla cars have their own type of chargers called the super chargers and hence have their own type of connectors as shown above. But they do sell an adapter which can convert their port to be charged with CHAdeMO or CSS chargers. The CDD charger is another popular charger socket which combines both AC and DC types of chargers. As you can see in the image he charger is split into two segments to support both DC and AC. It can support CAN and Power Line Communication (PLC) and is widely used in European Cars like Audi, BMW, Ford, GM, Porsche etc. It can support upto 400kW DC output and 43kW AC output.  

EVSE AC Charging Station - Level 1 and Level 2 Chargers

The Level 1 and Level 2 Charging station simply has to supply AC power to the on-board charger in an Electric Vehicle which would then take care of the charging process; this might look on a first look. But they bear the responsibility of proving right amount of Power from the Grid as required by the EV battery Pack by communicating to it through Pilot wire. The subsystems present in a typical AC charging station represented in TI Training document is shown below.

EVSE AC Charging Station

The level 1 chargers have a maximum output current of 16A due to the restrictions of household energy sockets, whilst the level 2 chargers can provide upto 80A whilst operated in 3 segment deliver. Each the level 1 and stage 2 AC chargers generally use the SAEJ1772 popular plug connectors.

As you may see the AC energy Line (L1 and L2) are linked to the J1772 connector though a Relay. This relay can be closed to start the charging method and opened whilst charging is finished. The Pilot signal verbal exchange is used to come across battery reputation and the host processing system decides how a great deal power should be furnished to the on-board charger. We will talk more on this later.

The strength supply unit encompass an AC/DC converter which take in the AC power shape grid and converters it to DC 15V the use of a switching circuit. This 15V is then supplied to the Regulator which includes a DC/DC converter which makes use of three extraordinary buck Regulators to regulate 12V, 5V and 3.3V that is used to energy the sensors, presentations and controllers in the Charger Unit. The measurement gadget includes V/I sense circuits which is used to measure the AC present day and AC voltage. Inside the above block diagram a modern transformer (CT) is used to degree the input current however shunt or Flux method also can be used. The voltage is measured on either facet of the relay to understand if the relay is current open or closed. Since the measurement subsystem deals with AC voltage and current it's miles digitally remoted from the Host Processing Subsystem.

The Host Processing Subsystem consists of the main Microcontroller which receives the facts from pilot verbal exchange and primarily based at the facts it triggers the Relay the use of Relay motive force circuits. It also monitors the modern-day and voltage using the values provided through dimension subsystem and takes corrective movements each time required. This controller will also have a show unit, EEPROM and RTC to offer beneficial statistics like charging time, current repute and many others to the person.


Pilot Wire Communication in EVSE (AC charger)

In AC chargers the charging rate, this is the specified enter current, is absolutely determined by means of the EV itself. Not All EV’s require the same quantity of input charging cutting-edge and consequently the AC Charger should speak with the EV to recognize the specified input contemporary and carry out a handshake earlier than the charging could virtually begin, this communique is known as the Pilot twine conversation.

Normally the AC chargers use the J1772 cable which has  factors at the charger apart from energy lines. These  sign lines help the charger to talk with the EV via +/-12V PWM alerts. By default the sign pins on the EVSE output +12V, this while related to an EV will get reduced to 9V due to a load resistor present within the electric powered car, this indicators the EVSE that the connector has been plugged into a EV. After this the EVSE will send a PWM signal of value 12V and a responsibility cycle fee corresponding to the most contemporary it may deliver. If the EV is ok with that price of modern-day then it plays a handshake via converting the load resistance and dropping the PWM voltage to 6V after which the charging starts.

Pilot Wire Communication in EVSE

The above graph illustrates the communication taking place among the EV and the EVSE. As you may see first of all whilst EVSE isn't always plugged within the EVSE output 12V, as quickly as it receives plugged in it drops to 9V and the PWM sign is began. Right here in this example, the obligation cycle of the PWM signal is 50% that means the to be had enter cutting-edge is 30A (maximum capacity 60A). If the EVs on-board charger ought to work with this modern then the EV alerts a handshake by using converting the burden resistance and the PWM signal now drops to 6V. The charging starts offevolved at this factor and will continue as long as the PWM signal oscillates among 6V and -12V. The EV will alternate its load resistance once more while the charging procedure is entire to sign the charger to shut down.

EVSE DC Charging Station - Level 3 Chargers

The level three charging stations are more complex than the Level 1 and Level 2 since the DC/DC conversion for the battery pack has to be done by the EVSE itself. Since a DC EVSE bypasses the on-board charger it should know all vital parameters of the battery pack to charge it safely hence a CAN or PLC (Power Line Communication) should be established between a EVSE and  the BMS of the EV. A Level 3 charger normally uses the CHAdeMO charger socket but other connectors like the J1772 Combined charging connector, Tesla connector are also being adapted by different manufacturers, these chargers can deliver upto 200A directly to your battery pack to charge the EV in less than 30 minutes. A typical simplified DC charging station Subsystem block diagram is shown below.

EVSE DC Charging Station

The system here is over simplified by removing the systems that we discussed earlier in the AC charging system. The Level 3 charger always works on a three phase AC supply, so the AC/DC converter has to take in the 3 Phase supply and convert it to 40V or higher DC. This DC voltage will then be stepped up to higher level (350 -700 V) as required by the battery pack. The Output Voltage and Current will be decided by the BMS of the EV which will then be communicated to the EVSE through CAN/PLC communication. Most of these level 3 chargers will be placed in charging stations for public access and hence a Human Machine Interface (HMI) arrangement gets mandatory. Some EVSE will also have wireless features like NFC, Bluetooth and Online payment gateway features etc to facilitate easy public usage.

The technology challenge lies with the AC/DC converter and DC/DC converter subsystems of the module. Since the charger draws in high current form the grid a proper Power Factor Correction system is required. Also the Converters are dealing with very high current and the power electronic switches inside them like MOSFET and IGBT cannot handle as a single unit. Hence normally the converter units are split into small units which are then combined in parallel to provide high current.

EVSE DC Charging Station - Level 3 Chargers

Advancements in EVSE

Few people arguably put forward that EVs aren't absolutely inexperienced if they may be powered by way of energy generated from non-renewable power stations like Coal, Nuclear and many others. Good aspect is that solar Powered EVSEs are slowly getting popular. Due to the scale, efficiency and weight of solar panel it isn't feasible to have EV’s at once run via sun electricity. However EVSE alternatively can draw strength from the solar panel in place of grid. The downside although is massive initial value and terrible performance, because the electricity from sun needs to be saved in batteries and then must be transferred to EVs once more. Additionally the performance of sun panel is very low (44.5% is the best till date) and its technology nevertheless must be developed to make it a affordable improve.

Every other great development is the vehicle to Grid (V2G) machine. Wherein the Battery p.C. In a EV could act a power supply for household equipments. Today’s EVs include a massive battery percent upto 100kWh or extra making it an clean portable energy residence. So with the right inverter the power from those battery packs may be supplied to the grid all through height demand hours. Then those EVs may be pushed to solar powered stations to get them charged again, constructing a totally green eco system.

Setting up an Electric Vehicle Charging Station in India

With EVs getting quickly famous in India, we are able to already word many EVSE set-u.S.Popping up in primary cities of India. With policies nevertheless being standardized for India the subsequent are the commonplace issues with setting up an EVSE in India.

1. Low fee rate for Indian EVs:   The EVs in India are still not ready for degree three or extremely good chargers as their battery packs do no longer help speedy charging. How rapid a battery could fee depends on its C score, Indian EVs nonetheless have very low C score that even a level 2 charger isn't always required for maximum EVs. This can create less call for for public EVSE

2. Strength Re-Sale hassle: according to norms you are not allowed for direct Re-Sale of electricity. Only the DISCOM is authorized to promote strength. However with strain from ISGF the Charging stations might be considered as an expectation for this in the destiny.

3. Susceptible Distribution Transformers: most of the Distribution Transformers (DT) in India is already overloaded. An EVSE will devour high electricity from the grid making it a heavy trouble. For this reason the whole DT in that region has to be replaced with higher score ones. This may be a main hassle as new EVSE begins doping up inside the city. You may study this whitepaper from ISGF to recognise more information about putting in place an EV charging station in India.