Can dual-code magnetic encoders be used in wind turbine pitch systems?

The double code magnetic encoder can be effectively applied to wind turbine pitch control systems, and its design and functional characteristics significantly improve the control accuracy and reliability of the system. The following is a specific analysis:

1. High precision angle feedback and control
The double code magnetic encoder adopts the principle of magnetic induction, and directly outputs real-time angle and velocity signals of the blade by non-contact detection of magnetic stripe displacement changes. Its accuracy can reach 0.1 °, far higher than traditional encoders (usually 0.5 ° -1 °). High precision feedback enables the main control system to accurately adjust the pitch angle, optimize wind energy capture efficiency, and maintain stable power generation especially during wind speed fluctuations.

2. Anti interference and environmental adaptability
Magnetic encoders do not require mechanical meshing components (such as gears), and the gap design between the magnetic head and the magnetic strip (≤ 4mm) avoids direct contact with dust and oil. Magnetic field signals are not easily affected by dust, humidity, or electrical noise interference, making them suitable for harsh environments with high dust and vibration inside fan hubs. Compared to traditional photoelectric encoders that are prone to signal distortion due to pollution, magnetic encoders have significantly improved stability.

3. Redundant backup and fault tolerance
In the double drive variable pitch system, the double code magnetic encoder can be integrated separately into the pitch motors of the master and slave drive units, forming independent feedback channels. If one of the encoders fails or the signal is lost, the system automatically switches to the signal of the other encoder, maintains PID closed-loop control, and only triggers an alarm without stopping the machine. This redundant design significantly reduces the risk of unit shutdown caused by single point failures, ensuring the continuity of power generation.

4. Simplify installation and maintenance
The magnetic encoder has a compact structure, with the magnetic strip directly embedded in the groove of the variable pitch flange and fixed with a cover plate. The magnetic head is installed on the stationary part of the bearing, saving space inside the wheel hub. No gear meshing requirement, avoiding the problem of frequent calibration of traditional encoders due to tooth wear and reducing maintenance costs. The debugging process only requires ensuring the gap between the magnetic heads, making it easy to operate.

5. Collaborative control and system optimization
The double code signal can be cross checked with the position sensor data of the hydraulic pitch cylinder to calibrate the angle deviation in real time. For example, the main control system compares the feedback values of the double encoders to determine whether they are within the allowable deviation range (usually set as a threshold range), and selectively uses the arithmetic mean or root mean square value as the actual angle to improve the robustness of the control algorithm. This mechanism effectively suppresses the accumulation of single encoder errors and extends the system's lifespan.

6. Emergency feathering safety guarantee
When the feedback angle deviation of the double encoder exceeds the limit, the system triggers a fault shutdown and executes emergency feathering (blade reverse to 90 ° position) based on the main encoder signal, quickly reducing the wind turbine speed and minimizing mechanical load impact. The fast response characteristic (millisecond level) of the magnetic encoder ensures safety under emergency conditions.