Recently, six departments, including the National Development and Reform Commission and the National Energy Administration, issued the "Action Plan for Doubling the Service Capacity of Electric Vehicle Charging Facilities in Three Years (2025-2027)". The main goal of the Action Plan is to build 28 million charging facilities nationwide by the end of 2027, providing more than 300 million kilowatts of public charging capacity to meet the charging needs of more than 80 million electric vehicles, thereby doubling the charging service capacity, further boosting consumer confidence and promoting the purchase and use of electric vehicles on a larger scale.
It is worth mentioning that while deploying a nationwide electric vehicle charging network on a large scale, further improving the "safety," "reliability," and "energy efficiency" of electric vehicle charging piles is also one of the key points in building high-quality electric vehicle charging service capabilities. Among them, digital isolators, as the key bridge connecting the high-voltage power side and the low-voltage control side in electric vehicle charging piles, are becoming an important "core" that allows new energy vehicle owners to charge with peace of mind, thanks to their core characteristics such as high isolation voltage, high CMTI (common-mode transient immunity), high data rate, and low transmission latency.
Electrical isolation is crucial during electric vehicle charging. Any isolation failure or noise coupling problem can lead to malfunctions, communication interruptions, or even safety accidents. In particular, when insulation degradation or leakage occurs, the circuit must be disconnected and an alarm triggered immediately.
Digital isolators are perfectly suited to address this scenario. They can not only transmit control and communication signals stably and safely in the harsh environment of high dV/dt and high noise at car charging stations, reducing the risk of false triggering and system failure from the source, but also monitor the electrical parameters of the primary and secondary circuits in real time, thereby ensuring that the charging station can complete the entire charging process safely and reliably.
Diagram of new energy vehicle charging stations (AC/DC charging piles)
For electric vehicle owners, digital isolators bring "visible" peace of mind and "tangible" reliability to the car charging process. When the owner plugs in the charging gun and starts the charging process, the digital isolator ensures the stable transmission of control commands and communication data between the charging pile and the vehicle, thereby accurately matching parameters such as charging power and voltage, and avoiding charging interruptions or parameter abnormalities caused by signal interference.
Meanwhile, the electric vehicle charging station can also safely and in real time monitor the insulation status between the high-voltage power side and the low-voltage control side through a digital isolator. Once an electrical risk is detected, the protection system will be activated immediately to cut off the circuit and trigger an alarm, thus preventing accidents such as electric shock and equipment burnout from the source.
The working principle of a car charging station (DC) is to rectify the AC power from the grid into DC power, and improve the energy utilization rate and reduce harmonic pollution through a PFC (Power Factor Correction) circuit. At the same time, the rectified DC power is boosted to a stable DC bus voltage (up to 750~850V). Then, the DC/DC isolation converter is used to adjust the bus voltage to the output voltage adapted to the electric vehicle battery, and a high-frequency transformer is used to achieve strong and weak current isolation to block interference, thereby providing a stable charging environment for the car.
Schematic diagram of electrical isolation scheme in electric vehicle charging piles (DC)
As shown in the figure above, in the electrical isolation solution provided by HOPERF for car charging piles (DC), the CMT8602X series isolation driver chip is the "nerve center" of the car charging pile power conversion system. It ensures safety through electrical isolation, improves efficiency through signal driving, reduces the risk of failure through multiple protections, and optimizes coordination through timing control. It directly affects the reliability, efficiency and safety of car charging piles and is a key component for realizing high-voltage fast charging.
The CMT8602X supports isolation voltages up to 5.75kV, effectively suppressing common-mode transients (CMTI > 150 kV/µs), preventing false triggering and logic flipping caused by dV/dt, and ensuring the stability of gate drive and control signals. In addition, the CMT8602X supports 4A peak pull-up current and 6A peak sink current, enabling efficient control of switching devices (such as IGBTs and SiC MOSFETs), achieving efficient power factor correction, and suppressing false turn-on caused by the Miller effect.
The CMT812X and CMT804X series of basic digital isolation chips serve as "safe communication bridges" connecting modules with different potentials. Between the primary and secondary DSPs, high-voltage isolation blocks surges and suppresses common-mode interference, ensuring real-time synchronous control of both DSPs. Between the primary DSP and the human-machine interface unit, it isolates high-voltage noise and prevents ground potential difference interference, ensuring accurate transmission of operating commands and status signals. Between the secondary DSP and the CAN bus, it suppresses external electromagnetic interference and blocks fault backflow, ensuring reliable communication with external devices.
The CMT812X and CMT804X support isolation voltages up to 5kV, transmission delays as low as 9ns, and maximum speeds of 150Mbps. They can effectively improve the control precision and system response of car charging pile systems, ensure stable transmission of digital signals, and solve problems such as potential differences between the high-voltage and low-voltage sides, high-frequency interference, and external communication reliability. They are key components for achieving "safe, stable, and accurate" charging in car charging piles.
In addition, HOPERF also offers isolated sampling chips such as CMT1300 and CMT1311, which can be used in PFC circuits and DC-DC circuits in car charging piles to block the direct connection between the high-voltage bus and the low-voltage control circuit (MCU/DSP), preventing the risk of electric shock and equipment damage. At the same time, it accurately converts the current signal of the high-voltage bus into a data signal that can be processed by the low-voltage control circuit (MCU/DSP), thereby meeting the loop control requirements and ensuring the stable operation of the charging pile system.
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