To ensure efficient charging, the recommendation of the selection of charging pile optocouplers

As new energy vehicles are booming, charging piles are key infrastructures, and their performance and stability are of vital importance. Optocouplers, as core components in charging pile circuits, play an irreplaceable role in ensuring the reliable operation of charging piles. This article will deeply analyze the key points of selecting charging pile optocouplers and recommend several high-quality optocouplers suitable for different scenarios.

1. The key role of optocouplers in charging piles

Charging piles involve the interaction of strong and weak electricity, as well as complex signal transmission and control. As a device that transmits electrical signals using light as a medium, optocouplers play two core functions here.

On the one hand, electrical isolation is achieved. The charging module of the charging pile often involves high voltages of hundreds of volts or even thousands of volts, while the control circuit is a low-voltage weak current area. If the two are directly connected, the high and low voltages may instantly break through the weak voltage control circuit, causing serious faults. The optocoupler is like a solid electrical firewall, which effectively isolates the high and low voltage circuits, prevents the high voltage from interfering with and damaging the low voltage circuit, and ensures the safety and stability of the use of the charging pile. On the other hand, it can accurately transmit signals. During the operation of the charging pile, the control unit needs to interact with the charging module, communication module, etc. in a large number of signals, such as signals to control the start and stop of charging, PWM signals to adjust the charging power, and feedback signals for real-time monitoring of power. In a noisy electromagnetic environment, ordinary signal transmission methods are easily interfered with, resulting in signal distortion or loss. Optocouplers, with their characteristics of optical signal transmission, have extremely strong anti-interference capabilities, which can ensure accurate transmission between modules and ensure the smoothness and accuracy of the charging process.

2. Key factors for selecting optocouplers for charging piles

(1) Isolation voltage Isolation voltage is a key parameter to measure the voltage resistance of optocouplers. Charging piles have a large operating voltage span, especially DC fast charging piles. To ensure effective isolation under extreme voltage conditions, it is recommended to select optocouplers with an isolation voltage of 5000Vrms or above. For example, in an 800V high-voltage charging system, an optocoupler with a high isolation voltage can act like a solid shield to resist high-voltage shocks and prevent electrical accidents.

(2) Signal transmission speed Fast-response optocouplers can greatly improve the performance of charging piles. During the charging process, PWM signals are used to accurately control the charging current and voltage. High-speed optocouplers can quickly respond to changes in PWM signals, allowing the charging pile to adjust the output in real time according to the battery status. Therefore, when selecting products, products with a response time of microseconds or even nanoseconds should be selected. Optocouplers with a response time of less than 10μs can make charging adjustments more timely, significantly shorten charging time, and improve user experience.

(3) Current transfer ratio The current transfer ratio (CTR) determines the proportional relationship between the input and output currents of the optocoupler. Different charging pile circuits have different requirements for signal strength. Optocouplers with a CTR range of 50%-200% are widely applicable. If the CTR is too low, the output signal is weak and cannot effectively drive the subsequent circuit; if the CTR is too high, the circuit may work unstably. The appropriate CTR ensures perfect matching of signals between modules and stable transmission.

(4) Operating temperature range Charging piles are widely distributed, from hot deserts to cold polar regions, from humid seashores to dry inland areas. This requires the optocoupler to have excellent environmental adaptability. The operating temperature range should cover -40℃ to 125℃ to cope with extremely cold and high temperature environments, ensuring that the charging piles can operate reliably all day long.

3. Recommended Optocoupler Part numbers

(1) High-speed optocoupler: 6N137 6N137 is a leader in the field of high-speed optocouplers, especially suitable for high-speed signal transmission scenarios of charging piles. Its rise and fall time is only about 80ns, which can accurately capture high-frequency PWM signals and provide guarantee for accurate regulation of charging current. The isolation voltage of 3750Vrms is sufficient to meet the common high and low voltage isolation requirements of charging piles. In the charging module control circuit of the charging pile, 6N137 can quickly transmit the high-speed signal sent by the control unit to the power device to achieve efficient charging control.

(2) General optocoupler: PC817 As a universal optocoupler, PC817 occupies an important position in charging piles due to its high cost-effectiveness and wide applicability. It has a wide current transfer ratio range and can flexibly adapt to the signal gain requirements of different circuits. The isolation voltage of up to 5000Vrms ensures the reliability of electrical isolation. In the auxiliary power control, status indicator light drive and other circuits of the charging pile, PC817 silently plays an indispensable role with its stable performance.

4. Selection Recommendations

When selecting an optocoupler for a charging pile, it is necessary to fully consider the actual application requirements, circuit design characteristics, and cost budget. It is recommended to fully test and verify different types of optocouplers during the new product development stage to ensure their compatibility and stability with the overall charging pile system.