For electric car charging pile, we always see the words AC charging pile and DC charging pile, so what is AC and what is DC, what are their advantages and disadvantages, it is worth to understand and discuss in depth.
There are two types of electric currents: direct current (DC) and alternating current (AC). Before determining the advantages and disadvantages, let's find out the difference between direct and alternating current.
What Is the Difference Between DC and AC Current?
In DC or direct current, electric charge flow in one direction only because of the rotating magnet along the wire. The electrons move forward or in one direction steadily. In contrast, electric current changes its direction periodically in AC current because of the steady magnetism along the wire. The electrons keep on changing directions from forward to backward.
The DC current cannot travel long distances due to larger energy losses compared to AC. The voltage of DC can only travel far until it begins to lose energy. While AC can provide more power and make it safe to travel over long distances.
The frequency of DC is zero, while the frequency of alternating current depends on the country, but mostly it is 50 to 60 Hz. The availability of DC is battery or cell, whereas AC is obtained from AC generator and mains. DC circuit only has a resistor as a basic element, whereas the AC circuit has two new circuit elements, namely capacitor, and inductor, in addition to a resistor. The current of magnitude varying with time is constant in DC, while AC is the current of magnitude varying with time.
Advantages of AC Over DC
AC charging with a plug is the most common method for electric vehicles. Since the converter is built inside the vehicle, the power is converted from AC to DC inside the car before feeding it into the battery. The speed of charging depends on the output power of a charge point and the convertor's ability to convert into DC.
AC charging is mostly suitable for parking spots where the vehicle will stay parked for more time.
AC's generation, installation, and operation are cheaper than that of DC.
AC machines are robust and not complicated. They do not require much care for their repairs and maintenance when used.
Since the current magnitude is not constant, it can be reduced using an inductor or a conductor without much energy loss.
AC power can easily be converted into DC by using rectifiers.
A wide range of voltages can be obtained with the help of a transformer.
The line losses are minor compared to a DC transmission when AC is supplied at higher voltages for longer city distances.
Advantages of DC Over AC
Unlike AC chargers, a DC charger can feed power directly to the car's battery without requiring the onboard charger to convert it as it has the convertor inside the charger itself. It is expensive because it requires a power supply or transformer (a lot of power like 125A from the grid), resulting in higher tariffs for charging.Some of the advantages of DC when it comes to EVs are:DC chargers are bigger and faster as compared to AC
It can covert the power before it enters the car, and the power goes directly to the car battery by passing the vehicle's converter.
Suitable to recharge quickly over long-distance travel for cars that support DC charging.
It is more dangerous to work with AC than DC at high voltages.
Alternating voltages are not applicable for charging certain batteries, electroplating, electric traction, etc.
Most chargers use AC power because of the lower costs required in production, installation, and operation compared to DC. It is safe and transmitted economically over long distances. Although DC is more expensive to install, the power is much faster than an AC charging station and a suitable charging method to quickly recharge during long-distance trips.