In fact, the reason is very simple, AC charging is basically directly connected to the charger inside the car, and the internal charger is responsible for converting it into the corresponding charging voltage according to the current voltage of the battery.
Although ordinary mains lines have safety restrictions, the voltage remains unchanged and the current is limited, but this limit is not so difficult to increase.
The main limitation is in the charger in the car. Due to size, weight and heat dissipation limitations, the charger in the car is generally the size of a suitcase and weighs in the order of ten kilograms.
And DC charging, in order to solve the problem of on-board charger limitations, has been changed to another way.
Through the communication protocol of the charging socket, the vehicle detects the current battery status, calculates the optimal charging voltage, and transmits it back to the charging pile through the charging cable, which is directly converted into direct current of the corresponding voltage by the charger inside the charging pile, and directly in.
The charging socket in the DC charging state, the two large terminals in it are directly connected to the positive and negative poles of the car's power bus, and the voltage is directly hundreds of volts, which is just a little higher than the current battery pack voltage, and the current changes according to the charging demand, and the upper limit is also hundreds of amps.
That's why I said before that the safety regulations of the charging cable and the socket itself are not a problem at all, and the high-current and high-voltage charging cable that can be used safely is completely made.
But in order to convert such a high-power mains power into high-voltage DC, this converter is not small.
The overcharged substation facilities look about the same size as the community substation.
After coming out of the substation, enter the supercharging cabinet, which is actually a car charger, but it is directly installed with a stack, parallel layout, and at the same time, it must be equipped with the cooling facilities of the charger and charging cable, otherwise the capacity of hundreds of kilowatts, even if it is 1% loss, the waste heat is at the level of several kilowatts, and it will take a few seconds to barbecue it.