Impact of Hall sensors positioning on symmetry of BLDC control signals

The paper presents results of investigating symmetry of signals used to determine motor shalt angular position and generated by two different sensors. One group of sensors was built into the motor and consisted of six single Hall sensors placed inside rotor slots. The other group consisted of six Hall sensors positioned in the same way as in the first group with respect to each other, but assembled outside the motor and operating with additional magnet device (independent magnetic field source) mirroring rotor magnets. A special dedicated recorder was constructed, helping to record durations of different shaft positions. Exemplary efficiency curve of the motor is shown, depicting efficiency vs. control angle shift. Investigation of motor efficiency was conducted for wide range of control angles, in the neighbourhood of one particular angle where efficiency is maximum.