A Novel Wireless Hall Signal Detector for Wireless Brushless DC Motors

This article proposes and implements a novel wireless Hall position signal detector with full primary control for wireless brushless direct current (BLDC) motors. The crucial aspect is to combine the standard Hall-effect position sensor with wireless sensor coils. The sensor coils possess functions of detector excitation and wireless information transfer (WIT) regulated by secondary-side bidirectional switches. A novel combination of unipolar, horizontal bipolar, vertical bipolar, and quadrupole coils is employed to achieve four-channel decoupling, thus realizing coil integration. A new snubber, consisting of two resistor-capacitor-diode (RCD) snubbers connected in antiparallel, is proposed to suppress the significant bidirectional voltage spikes across bidirectional switches. This detector possesses strong robustness against motor power and commutation as its excitation is independent from the wireless power transfer (WPT) channel of wireless BLDC. Besides, it enables extremely low delay since no complex commutation protocols like those in Bluetooth are involved. Moreover, its binary output signals can be directly recognized by the primary-side controller, not requiring additional algorithms or circuits for decoding or filtering. This detector holds the highest experimental speed record at 10 000 rpm among all existing wireless position sensors for wireless motors, with a delay of only 0.9% of the minimum Bluetooth communication latency.