Popular Science Explanation of the Working Process of Electric Vehicle Charger

Hello everyone, today we are going to discuss the working process of the electric vehicle charger, also known as the OBC (On-board Charger). I hope that through today's sharing, you can better understand how the OBC converts external AC power into DC power that can be used by the battery, and ensure the safety and efficiency of the entire charging process.

The charging process of electric vehicles is not as simple as charging a mobile phone. The core task of OBC is to convert the AC power input from the power grid into DC power suitable for battery charging. This process involves multiple links, and each link is crucial. Next, we will disassemble this process step by step and explain it in detail.

First, the entire charging process begins with the input of AC power. When charging an electric vehicle at home, it usually starts with a 220V single-phase AC power supply, while a higher voltage three-phase AC power supply may be connected to a public charging station. The AC input port of the OBC directly receives these currents, and the currents pass through the first component of the OBC - the EMC filter.

The function of EMC filter is to eliminate electromagnetic interference in the current. When the current is connected from the power grid, it may be accompanied by various noises or interference signals, such as radio interference or noise generated by other electronic devices. If these interference signals are not processed, they will have adverse effects on the subsequent power conversion process and even affect the normal operation of other electronic systems in electric vehicles.

For example, models like the BYD Song Plus DM-i include very efficient EMC filters in their OBC systems, which can ensure current stability and avoid system anomalies caused by electromagnetic interference.

Next, the current enters the PFC circuit, which is the power factor correction circuit. The working principle of this part is relatively complicated, but it can be simply understood as a technology to improve the efficiency of electric energy utilization. Generally speaking, the AC current and voltage of the power grid are not completely synchronized. If this current is used directly, a lot of useless work will be generated, resulting in energy waste. The function of the PFC circuit is to synchronize the current and voltage phases, improve the power factor, thereby reducing energy consumption and improving system efficiency.

For example, in high-performance electric vehicles such as the Tesla Model 3, the PFC circuit design in the OBC system is very advanced and can increase the power factor to close to 1, which means that almost all the input electrical energy can be used efficiently.

After passing through the EMC filter and PFC correction, the current enters the core part of the OBC system - the DC-DC converter. At this stage, the OBC converts the optimized AC power into DC power suitable for battery charging.

The power battery of an electric vehicle can only be charged with direct current, but the power grid receives alternating current. The DC-DC converter converts this alternating current into stable direct current through complex power electronics technology. The efficiency and stability of this process are crucial, because if the conversion process is not efficient enough, it will lead to longer charging time and even generate excessive heat, affecting charging safety.

For example, the OBC system of the Wenjie M7 adopts a high-efficiency DC-DC converter design, which can quickly and stably complete current conversion at higher power, ensuring that the vehicle can obtain sufficient power in a short time.

The last key link is the control circuit. It can be said to be the "brain" of the OBC, responsible for real-time monitoring and adjustment of the entire charging process. During the entire current conversion process, the control circuit will continuously monitor key parameters such as voltage, current, temperature, and dynamically adjust the charging state based on these data.

For example, when the battery temperature is too high, the control circuit will automatically reduce the charging power to prevent the battery from overheating; in a low temperature environment, it will adjust the charging voltage to ensure that the charging efficiency is not affected by the environment. Tesla Model Y is a typical example. The control circuit in its OBC system can intelligently adjust the charging mode according to the battery status to provide the fastest and safest charging experience.

In summary, the working process of the electric vehicle charger OBC includes several important steps: starting from the AC input, the EMC filter eliminates electromagnetic interference, and then the PFC circuit improves the power factor to ensure efficient use of electrical energy. Subsequently, the DC-DC converter converts the optimized AC into DC, and finally the control circuit monitors and dynamically adjusts the entire charging process to ensure efficient and safe charging of the battery.

These links work together to ensure that the entire charging process is smooth and efficient. Whether it is ordinary home charging or fast charging at public charging piles, OBC can play a vital role in it.

I hope that through today's explanation, everyone has a clearer understanding of the working process of electric vehicle chargers. OBC is not just a simple current converter, it is a complex and sophisticated system, and each link is indispensable. For electric vehicle users and practitioners, understanding the working principle of OBC can help us better use and maintain the vehicle and improve the overall car experience.