Charging an Electric Cars
With the Tesla wave, the sales of electric cars have seen a steep rise. An important aspect of electric cars is charging and it needs it I mean a hell lot of it. Charging electric car is a hurdle for many drivers as charging can be boring. With a conventional vehicle, you stop by a fuel station and refill your fuel in minutes and carry on. But wait in electric vehicles we have SUPERCHARGERS, they can practically boost your mileage to 250+miles in a short 30mins of Break and that’s not bad at all. Well, all-electric cars don’t support supercharging, let get to the depths of the types and Cars supported.
Types of Electric Chargers
- Level 1– It refers to 120 volts of AC charging which is found in, house wall outlet. Level 1 charging needed most of the times. It requires a dedicated circuit and offers 5 miles per hour of charging. This method isn’t suitable for vehicles with more mileage as the charging time rises indefinitely. Due to less voltage and Single Phase limitation, the charging capabilities on this source gets considerably reduced. A standard J plug defined in SAE J1772 as level 1 with a maximum of 16Amp and power of 1.92KW is provided in this mode of charging.
- Level 2– It refers to 240 volts of AC charging which would be most public charging stations. It usually supplies 15-40 amps of current. They are capable of recharging the exhausted batteries for most EVs in 4-10 hours depending on the car. They offer 10-20 miles of range for every hour of charging.3.
- Level 3– Level 3 charging is the fastest level of charging. It supplies a high voltage DC right into the vehicle’s battery so that they can replenish the depleted batteries of the cars to 80% of charge level in 30 minutes or less. It uses 480 volts direct current plug. They provide 170-200 miles of range for every hour of charging.
Types of connectors in fast charging
- Tesla superchargers- It is used only in Tesla cars. There are 1308 supercharging stations with 10622 superchargers. The superchargers transfer the energy very quickly into the battery. As it sees
the battery approaching the full capacity, it slows down. The vehicle will give the information when it has enough energy to continue the trip. With the enormous amount of superchargers present across the globe, charging above 80% is not necessary.
Combined Charging System (CCS) – There are US, Asian and German automakers who have adopted CCS. It is recent so it does not have the same mass utilisation as CHAdeMO. It is built with stations containing CHAdeMOs too, so it serves well for short range EVs. The power given by CCS stations are 20-50kW. Automobile companies that support CCS are Jaguar, Volkswagen, General Motors, BMW, Daimler, Ford, FCA, Tesla and Hyundai.
CHAdeMO- CHAdeMO stands for ‘Charge de Move’. It is primarily used by Nissan, Mitsubishi and Toyota. It can also be found in Kia Soul and Honda EVs. They are well spread in many places. Tesla also makes the CHAdeMO adapter for their cars so that Tesla can make use of this network as well as their supercharger.
The charging stations are embedded with ground fault detectors that will reduce the injury from electric shocks. The current does not flow in the connectors until they are properly inserted into the socket of the EV. The connector is sealed to protect the live components from the weather. A locking mechanism (latch) prevents accidental disconnection if the cable is pulled. Few charging stations are equipped with an emergency shut off facility.
Infrastructure for Fast Charging
With the shift in EVs, the transportation will achieve sustainable means of movement. Although there are still some charging limitations, predominantly something called as ‘range anxiety’. Range anxiety is the fear of running out of charge before approaching the charging point. There can be many psychological reasons that can supplement range anxiety. To curb this issue, we need fast chargers in abundance.
Slow charging facility would extend the travel time. With the help of fast chargers within 15–20 minutes we can recharge for approximately 200 km range, while slow chargers operating at 3 kW, would approximately take 3 hours for 100 km range. Hence, with fast charging, a 500 km trip could imply two charging stops of 15–20 minutes each, compared to internal combustion vehicle only stopping once for 10 minutes.
The infrastructure for slow chargers is already present. It can be done by the sockets present in our homes. The power requirement could require low voltage infrastructure. Specific charging connectors are needed to adapt to normal EV charging.
In the event of building the infrastructure for fast chargers, a mass adoption of the EVs is to be taken into consideration. There is a constant debate on what to promote, the fast charging hubs or the electric cars. Investors claim that investing in fast charging hubs is a highly unprofitable investment as there no mass adoption for electric vehicles. The private fast charging hubs are fast but highly expensive as compared to the ones in public sector.
- Role of Connectors
The standard norms of J-1772 have been universally applicable to all three levels of charging. Level I and level II fall into the category of slow charging. Only level III enables fast charging. In Europe, International Electrotechnical Commission (IEC) 61851 applies to equipment for charging electric road vehicles at standard AC supply voltages (as per IEC 60038) up to 690 volts and at DC voltages up to 1000 volts. The Japan Automotive Research Institute (JARI) actively participates in setting EV charging standards. IEC 61851 promotes different charging levels analogous to SAE (Society of Automotive Engineers) J1772. Coordination between SAE J1772 and IEC 61851 is going on.
2. Charger/Vehicle Communication
Communication protocols between DC chargers and EVs have been set up. Communications overcharging power lines have been made possible. The SAE J2836 committee is developing communication protocols between Level II outlets and PHEV onboard charger.
3. Time-of-use Electricity Costs
Advanced Metering Infrastructure (AMI) will allow time-of-use electricity costs. During the day, the AMI will enable the utilities to charge more as it is quite crowded as compared to the night. This will enable the consumers to use charging stations at night where it will be more convenient as it is less crowded. This is where the level 1 and level 2 infrastructure will be used a lot more than expected. It will also reduce the delay caused during the day. The consumers will also be billed according to the time taken by them for charging. For example, a slow charge at 120V, 15A would cost less per kWh than a DC fast charge at 125kW.
4. Grid Impact and Synergies
A grid is an interconnected network that delivers electricity to the consumers. AMI can be used to control the grid. Seeing how much power the grid has been loaded with, it can be used accordingly. If the grid has less power then, the use of chargers could be avoided.
The electric current is transferred by creating a magnetic field between a transmitting pad which is placed on the ground and the receiving pad that is located under the vehicle. The system is 90-93% efficient while charging at three times the power rating of a conventional charger. This means that an electric vehicle can be charged in one to two hours or a hybrid plug-in less than an hour.
Electromagnetic fields can be used to transfer the current to electric cars while they are in motion once the setup will be installed in the road surface. A company from Israel named ElectRoad is building roads that could charge vehicles on the move. It has designed a system that charges electric vehicles by embedding energy transfer coils in the road. As a vehicle such as travels over the coils, its battery is charged wirelessly.
Companies working on EV charging infrastructure
Walmart signed up with a Volkswagen subsidiary Electrify America to provide over 200 EV fast-charging stations at 100 new locations in America by 2019. Each charging station will include multiple ports of varying capacity that charge according to their power capacity. The company has an expenditure of 500 million dollars, outfitting for both new and old charging stations.
Electrify America is using vendors from ABB, Signet EV, Efacec Electric Mobility and BTC Power that will deliver time range in required to charge vehicles. Few would be slow using 50 kW chargers whereas few could be ultra-fast chargers with a speed of 350 kW.
Out of the 16000 public charging stations in the US, only 13% were DC fast chargers. Companies such as Electrify America, ChargePoint and evGO are building out charging networks, several utilities are also investing in public charging infrastructure. Tesla is building out its own proprietary charging network compatible for only Tesla cars.
Vehicle to Grid
Vehicle to grid technology helps us in energy management. It allows us to store the energy when not in use so that we can reduce our carbon footprint. It turns the EVs into mobile energy hubs. Using the V2G technology the drivers can store electricity in their vehicle’s battery and return it to the grid when needed.
By using sources of energy, houses, offices or electric vehicles can be powered. It can be during the day where solar power is used or any arbitrary method. Now in case of emergency when energy is in high demand and there are no alternative sources of energy for the grid, the electric vehicle could transfer the energy from it to power the grid. The grids that support this two-way communication between the utility and consumers are called smart grids.
This will support helping infrastructure more user-friendly. During peak times and in cases of dire emergency, when some car needs a charge and the charging stations are out of power, the car containing the charge can give the power to the grid and it can be used by the other car who is in need of power. Thus energy can be transferred from one car to the other. This technology can be used to power houses and offices too.
- It provides cleaner power
- Lower energy costs
- Greater stability of energy
Stedin, Renault, Nissan and General Electric are a few companies working on a wholly sustainable, self-supporting energy system.
Fast Charging using Sunlight
Wiocor Energy utilises a 3-D photovoltaic Solar Tower that provides high energy production using sunlight. It charges an EV in up to 30 minutes. It uses DC of up to 50 kW and AC of up to 43 kW. It uses CHAdeMO fast chargers and CCS/Combo.
TU Delft has developed a fast charger using with the help of Power Research Electronics and Last Mile Solutions which can charge cars directly with electricity from solar panels. The solar panels produce Direct Current which has to be converted to Alternating Current and then it can be used to charge the Electric car. This DC-AC conversion results in energy loss and it requires two DC-AC converters (for vehicle and solar panel respectively), which results in increased cost.
A more viable solution would be to use a single converter, which could vehicles from DC link while also being connected to the AC electricity grid. Therefore this company has designed a 10kW converter that is one-third of the existing AC converter. It has internal DC link and 3 terminals that charge the vehicles from both solar panels and the electricity grid. With the inclusion of the charger, the electric grid is not needed as the intermediate stage. This can also work as a smart grid.
Level 1 and Level 2 will be predominantly used because of its low cost which gives it greater access to the public. Level 3 provides a cushion to the consumers in terms of curbing their problem of range anxiety. It will be an utmost necessity for most public transport drivers. The concept of level 3 where in a few minutes you are provided the energy for the entire day, but the cost remains an undisputed factor. If somehow the cost is reduced, more and more investors will be attracted to invest in fast charging setups which will give mass availability of fast chargers sooner than expected.
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