Since the introduction of the first electric vehicle in the 19th century, rechargeable batteries have been used as their power source. For an electric car, battery charging equipment is one of the indispensable subsystems. Its function is to convert the electrical energy of the grid into the electrical energy of the electric vehicle's vehicle battery. There are different methods for classifying electric vehicle charging devices, which can be generally classified into in-vehicle charging devices and off-board charging devices.

The in-vehicle charging device refers to a device installed on an electric vehicle that uses a ground AC power grid and a vehicle power source to charge the battery pack, including an in-vehicle charger (Fig. 1-13), an in-vehicle charging generator set, and an operating energy recovery charging device. The AC power cable with plug is plugged directly into the charging socket of the electric vehicle to charge the battery. The in-vehicle charging device usually uses a contact charger with a simple structure and convenient control, or an inductive charger. It is designed according to the type of vehicle battery, and it is highly targeted. The off-board charging device, that is, the ground charging device, mainly includes a dedicated charger, a dedicated charging station, a universal charger, a charging station for a public place (Fig. 1-14), and the like. It can meet a variety of charging methods for a variety of batteries. Generally, the power, volume and weight of the off-board charger are relatively large, so that it can adapt to various charging methods.

In addition, depending on the manner in which the energy is converted during charging of the electric vehicle battery, the charging device can be classified into a contact type and an inductive type. With the rapid development of power electronics technology and variable current control technology, the high-precision controllable converter technology has matured and popularized. The phase-by-stage constant current charging mode has been basically replaced by the constant voltage current-limiting charging mode in which the charging current and charging voltage are continuously changed. . The dominant charging process is also a constant voltage current limiting charging mode. The biggest problem with contact charging is its safety and versatility. In order to meet the strict safety charging standards, many measures must be taken on the circuit to enable the charging device to be safely charged in various environments. Constant voltage current limiting charging and phased constant current charging are all contact charging technologies. The new type of induction charging technology for electric vehicles is developing rapidly. The inductive charger is a transformer principle that uses a high-frequency alternating magnetic field to sense electrical energy from the original side of the vehicle to the secondary side of the vehicle to achieve the purpose of charging the battery. The biggest advantage of inductive charging is safety. This is because there is no direct point contact between the charger and the vehicle. Even if the vehicle is in a bad climate, such as rain or snow, there is no danger of charging.