Digital isolators, as important safety devices for achieving electrical isolation between the low-voltage control side and the high-voltage power side, suppressing common-mode interference, and ensuring high-speed and reliable communication, are widely used in photovoltaic/wind power inverters, energy storage battery management systems (BMS), and energy storage converters.
They not only protect the safety of sensitive components and personal electricity use, but also ensure the stability and smooth operation of power conversion and communication links. They are one of the important underlying devices supporting the safe operation of new energy power supply systems and the stable power supply of computing infrastructure.
As shown in the figure below, in electrical isolation schemes for wind, solar, and energy storage systems, digital isolators are widely distributed between the control layer and the power layer, undertaking the dual tasks of signal transmission and electrical isolation.
From bus current/voltage monitoring, photovoltaic MPPT control, wind power rectification control, energy storage bidirectional converters, inverters, to interface communication nodes, almost all critical nodes involving high-voltage power conversion and high-speed communication require reliable isolation protection from digital isolators.
Schematic diagram of electrical isolation scheme for wind, solar and energy storage systems
The PWM control signal generated by the MCU needs to be driven by an isolation driver chip to drive power devices such as IGBTs and SiC MOSFETs to complete the energy conversion.
Since the power side bus voltage usually reaches hundreds or even thousands of volts, the isolation driver chip can effectively cut off the electrical connection between the high-voltage side and the low-voltage control side, preventing surges, voltage spikes and common-mode noise from intruding into the control system, thereby improving system reliability and safety.
The isolation amplifier is responsible for collecting key data such as the voltage and current of photovoltaic/wind power bus, the voltage and current of energy storage battery pack, and the voltage and current of grid-connected side. It also safely and accurately transmits the high-voltage side analog signal to the MCU control unit to realize functions such as system status monitoring, closed-loop control, and fault protection.
In the high common-mode voltage environment, the isolation amplifier can also effectively suppress noise interference, improve measurement accuracy and system stability, and provide a guarantee for the long-term reliable operation of new energy equipment.
General-purpose digital isolators are responsible for providing isolation protection for communication interfaces such as CAN and RS485 in the communication link, while also undertaking the task of isolating and transmitting digital signals to ensure that various types of data can be transmitted stably .
It is worth mentioning that, in addition to the wind, solar, and energy storage equipment mentioned above, the use of high-performance digital isolators can effectively enhance electrical safety protection, significantly improve the operational reliability of the system, and meet safety regulations in various power electronic systems involving the coexistence of high and low voltage.
For example, the CMT812X, CMT804X, and CMT826X are a series of general-purpose digital isolators with different numbers of channels and signal direction configurations, which can flexibly adapt to different control and communication architecture requirements.
In high-voltage and high-noise environments, they can effectively suppress the impact of surges, electromagnetic interference, and common-mode noise on low-voltage logic systems, ensuring stable, accurate, and efficient transmission of digital control signals, thereby improving the system's control precision and real-time response capability.
The CMT8602X is a series of isolation driver chips with best-in-class propagation delay and pulse width distortion. They support isolation voltages up to 5.75kVrms and possess high common-mode transient immunity exceeding 150kV/μs, effectively suppressing the risks of false triggering and logic switching in high dV/dt environments, thus enhancing the safety of power stage and control stage operation.
Furthermore, they support 4A peak source current and 6A peak sink current, enabling the driving of power devices with switching frequencies up to 5MHz.
The CMT130X series is a family of isolated operational amplifiers/ADC chips. Based on capacitive isolation technology, they isolate the output from the input and integrate system-level diagnostic capabilities, supporting VDD1/AVDD missing detection and input common-mode overvoltage detection.
They can operate stably in a wide temperature range of -40℃ to 125℃. Currently, chips such as the CMT1300D05 and CMT1306M05 are mainly used in high-voltage isolation scenarios such as industrial drives, new energy, automotive electronics, and BMS, providing high-precision and high-safety isolated sampling solutions for various complex power systems.
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