Wireless Sensor Power Supply for Rotating Shaft Using DC-Side Diode Array With Stable Output

24 x 7 health monitoring of rotating shaft is very important for the safe operation of automotive axles. Wireless sensor power supply technology is one of the promising power supply means for monitoring systems. Since the radius of many rotation shafts is large up to 1 m, segmented coils are adopted to reduce the magnetic interference and power loss compared to single receiver coils, but this will lead to output voltage fluctuation causing the monitoring system failures. This letter proposes a fluctuation suppression method by a dc-side diode array and parameter optimization. Using multiple reverse parallel diode groups to connect the dc side of multiple receivers and the load, the diodes will be conducted when corresponding coils are activated, while those without induced voltage will not be conducted. In this way, the mutual inductance fluctuation as per different rotation angles can be greatly reduced. In addition, a detuned system has been designed, rendering the output gain insensitive to variations in mutual inductance, thereby enhancing the output stability. A prototype was built to verify the theoretical analysis. The experimental results indicate that the output voltage fluctuation is only 5.0%. The proposed method can achieve significant output stability without complex control and dedicated coil design.