“The electric vehicle (EV) charging industry has grown rapidly as automakers around the world pledge to sell only electric vehicles in the future, and governments help build fast, reliable charging networks. These EVs will require fast, efficient and powerful EV charging stations.
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The electric vehicle (EV) charging industry has grown rapidly as automakers around the world pledge to sell only electric vehicles in the future, and governments help build fast, reliable charging networks. These EVs will require fast, efficient and powerful EV charging stations.
In this article, I will dispel 11 myths about EV charging.
Myth 1: It is possible to charge electric vehicles directly from AC power
Yes, there are EV chargers that directly use AC power to charge EVs, such chargers rely ON the on-board charger to first convert AC to DC and then use DC to charge the EV battery. However, some EV chargers also convert AC to DC first, and then do AC/DC conversion without an on-board charger to directly charge the EV battery. Typically, DC chargers operate at higher power levels, so charging times can be shortened.
Myth 2: All EV charging stations use the same charging technology
Electric vehicle charging stations use a variety of technologies. Some chargers convert AC power to DC power by using on-board chargers to directly charge electric vehicles with AC power.
However, there are EV chargers (called DC chargers) that first convert AC to DC and then charge the EV battery directly without the need for an on-board charger for AC/DC conversion. AC/DC conversion can use different power topologies.
Myth #3: EV chargers all have the same power level
Electric vehicle chargers (also known as charging stations) come in a variety of power levels, as shown in Figure 1. Levels 1 and 2 are AC chargers up to 20kW. Tier 3 includes fast DC chargers typically 50kW and above (up to 350kW).
Figure 1: Electric Vehicle Charger Rating Chart
Myth #4: Electric vehicle charging stations are operated by the grid or utility company
But in fact, it’s not. While grid and utility-run charging stations can operate charging stations, some automakers run their own network of charging stations, and other brands of electric vehicles can also be used. There are also third-party charging station network operators who are neither utility companies nor EV OEMs.
Myth #5: High-power-level chargers are more efficient
Power topology, control method, design, and component selection have a significant impact on the overall efficacy of a charger. For example, zero-voltage switching and zero-current switching power supply topologies can greatly reduce switching losses and thus improve power efficiency.
On the other hand, low power class chargers are not more efficient than high power class chargers. Low-power-level chargers rely on on-board chargers to convert AC to DC power before charging the EV battery. Since the efficacy of a charger is determined by a variety of components, it is not clear that one charger power level is more efficient than others. Typical efficiencies are between 95% and 99%, depending on implementation.
Myth #6: High-Voltage EV chargers are notoriously unreliable
With the advent of new battery technologies, car batteries can reach voltages of 800V and beyond. Following this trend, EV charger designers will face a common problem of maintaining isolation levels and system reliability.
Solar technologies (photovoltaic inverters) with DC bus voltages in the range of 1,000V to 1,200V are widely used in electric vehicle charging designs. These isolation technologies have been proven for over a decade and are well known for their reliability.
Myth #7: EVs still require drivers to go to a charging station to “power up,” just like going to a gas station
There are now many different ways to charge at home, and consumers can choose to automatically charge their EVs when electricity bills are lower, such as at night. Most modern homes or homes with garages are equipped with 240V plugs that can provide 100 to 200 miles of range on a charge.
Even an ultra-low-power charger installed in a home garage that connects to a standard 120V plug can achieve 40 to 60 miles of range on an overnight charge. For most drivers, charging at home every day is the easiest and most convenient way to charge.
Myth No. 8: Electric vehicles take too long to charge, and DC charging stations will not significantly improve charging speed
DC charging stations are Class 3 chargers with power levels ranging from 120kW to 240kW. These charging stations use an external charger to supply high-voltage (300V to 750V) DC power directly to the vehicle battery, up to 400A. Level 3 chargers typically charge the battery to 80% in 30 minutes.
Higher power levels can be achieved by stacking modular converters. There are several standards around the world (such as the ChaoJi standard) that allow Level 3 chargers to power levels up to 900kW, which reduces charging time to 10 minutes, depending on battery capacity.
Myth #9: Wi-Fi connection of EV chargers to the cloud is unnecessary
Given that buildings are equipped with limited power sources, it is necessary to connect EV chargers to the cloud via a wireless network. The wireless network allows users to manage the total charging load of the electric vehicle in real time.
In addition, the wireless network helps control power distribution at each EV charging point. Wireless networks can also charge electric vehicles during off-peak hours, saving on electricity bills.
Myth #10: Existing building infrastructure and parking lots are pre-wired for EV charging
Wireless connectivity is the most convenient solution when installing a new EV charging station. Wireless connectivity standards need to meet high RF environment and data throughput and latency requirements, with typical requirements including charging data update rates of 1 per second. With wireless connectivity (mesh networking), the system can be expanded to accommodate hundreds or even thousands of EV chargers.
Myth #11: Connectivity doesn’t play a role in EV charging
Connectivity can assist with EV charging by meeting user interface and access control requirements. This feature enables access control to be managed from the cloud (usually via the user’s smartphone app). Additionally, the connectivity feature supports uploading billing information and placeholder data to the cloud.