Electric vehicle chargers are divided into two categories: on-board chargers and off-board chargers, according to whether they are fixed to the vehicle or not. Non-vehicle chargers are further divided into two types: AC charging posts and DC charging posts.
On-board chargers, with AC power as input and DC output, directly charge the power battery; off-board DC chargers, with AC input and DC output, can directly charge the power battery. The former is less powerful, and the latter is larger. The other one, AC charging pile, with AC as input and AC output, cannot charge the power battery directly, and needs to be connected to vehicle charger for AC/DC conversion to achieve charging. The AC charging post is relatively simple inside, and its basic function is to lead the grid AC power to a convenient location for electric vehicle charging and provide a standard charging interface. The power of the AC charging post is generally not too large due to the limitations of the on-board charger capacity.
2 The location of the on-board charger in the electric vehicle
The on-board charger is fixed to the chassis as part of the electric system of the EV. The input of the on-board charger, in the form of a standard charging interface, is fixed to the body of the vehicle and is used to connect to an external power source. The output of the on-board charger is directly connected to the slow charging interface of the power pack.
In the electric vehicle CAN bus communication topology, the on-board charger is hooked up to the CAN bus as a node and exchanges data with the vehicle controller through CAN.
3 Charging Mode
Charging mode refers to the prescriptive way in which current and voltage are provided to the battery during charging. Charging mode, on the charging efficiency, battery life will have a significant impact.
The main charging modes are constant current charging, constant voltage charging, constant current followed by constant voltage charging, isotropic pulse charging and positive and negative pulse charging.
Based on the basic types, there have been researchers exploring more reasonable and efficient charging methods. For example, the combination of constant-current and constant-voltage charging with positive and negative pulse charging is used in the middle. After a longer period of pulse forward charging, a short period of negative pulse charging is interspersed to eliminate the polarization phenomenon generated during the forward charging process and reduce the circuit resistance, which in turn improves the charging efficiency and also has a positive effect on reducing the charging temperature. The diagram is shown in the case illustration that follows.
The diagram below shows the most common current form of charging, constant-current-constant-voltage charging. Higher current charging is used when the charge level is low to increase the charging speed; when the charge level is high, constant voltage charging is used to avoid causing damage to the battery.
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