Orient Photoelectric coupler new energy vehicle field and related field recommendation and benchmarking table

The wind of new energy vehicles is sweeping the world, and China has begun to gradually support the manufacturing of new energy vehicles and supporting facilities. Therefore, the current stage can be said to be the outbreak period of charging pile and new energy vehicles. Some traditional technologies are also joining the emerging market. Taking the optocoupler isolation as an example, using the optocoupler isolation circuit can achieve better security. This article describes this technique.

Charging piles can provide charging services for new energy vehicles, similar to refueling machines at gas stations. It can be fixed on the ground or wall, installed in public buildings (public buildings, shopping malls, public parking lots, etc.) and residential parking lots or charging stations, and can charge all kinds of electric vehicles according to different voltage levels. The input end of the charging pile is directly connected to the AC power grid, and the output end is equipped with a charging plug to charge the electric vehicle. Charging piles generally provide two charging methods: conventional charging and fast charging. People can use a specific charging card to swipe the card on the human-computer interaction interface of the charging pile for corresponding charging mode, charging time, cost data printing and other operations. Charging pile display can display charging amount, cost, charging time and other data.

After the alternating current flows through the rectifier, it is converted to direct current, which is boosted by PFC and then isolated and converted by DCTODC to get the output voltage for charging the car. The main control MCU controls the on and off of the power supply equipment by sampling and monitoring the voltage and current information of the strong current side to ensure the safe and reliable operation of the system.

In addition to providing insulation and isolation, the optocoupler can also ensure signal integrity. In the charging pile, it is necessary to collect external information and then communicate with the external system of the charging pile. In this case, need a digital isolation optical coupling, digital isolation decoupling charging will pile the weak part of the light (including control section) and the external port and insulation isolation, on the one hand, to prevent the weak part of the charging pile (including control part) interference, on the other hand to prevent the interference of communication information, ensure the integrity of the information signal.

In product design, the reliability of industrial products is very high, and the products need to pass a variety of safety certification and electromagnetic compatibility test certification. Strong side interference is generally larger, it is easy to produce interference to the weak current. In more serious cases, the main control part of the system will be interfered, and the system will not work normally. To prevent the interference of the strong current side from affecting the weak current side, the designer needs to isolate the strong and weak current. In charging pile system, it is necessary to monitor the voltage and current of bus and output port. In this case, an isolated voltage and current sampling device is required. Optocoupler isolation is a good choice.

Secondly, the traction inverter system in electric vehicles is likely to operate at a DC voltage of about 800V. This high DC voltage is converted to AC to drive the traction motor. However, the traction battery in an EV is not simply connected in series with multiple 12V batteries to generate 800V voltage; it is a sealed unit. The addition of this high voltage system and its role in the vehicle means that the 12V system is now commonly used as an auxiliary system. It powers all the auxiliary equipment of the traction system, including the traction control system.

The main high voltage battery is now responsible for powering the 12V auxiliary system to keep the battery charged. For safety reasons, it is necessary to maintain electrical isolation between the two voltage domains during operation.

Isolation is critical.

Typical electric vehicles have many functional units, including traction inverters, temperature control and heating systems, and on-board chargers. These systems operate at completely different voltage levels and must be electrically isolated. Electrical isolation prevents current from flowing between different voltage domains while still supporting data transmission and power flow.

To sum up, optocoupler isolation is indispensable in new energy