Carbon black reinforced magnetorheological gel enabled high-performance magneto-resistor for motor soft start-up

Excessive starting current, caused by full voltage start of motor, has a negative impact on the power supply network and motors' mechanical structure. With good magnetic field-dependent and magnetic-controlled electrical properties, magnetorheological gel (MRG) can be capsulated as a magneto-resistor to regulate the starting current in motor soft start-up. However, the inherent resistance of MRG magneto-resistor is too large to make current pass. In view of this, this paper improved the conductivity of MRG through doping carbon black (CB). The viscosity and magnetoresistance of MRG magneto-resistor under magnetic fields were studied systematically, and the conductive mechanism was qualitatively analyzed in this work. The results showed that the CB could significantly improve the magnetoresistance of MRG. The sample with 4 wt% CB was able to reduce the magnetoresistance more than 60% compared with sample with no CB. In addition, a soft start-up experimental system for motors had been established to verify the feasibility of MRG magneto-resistor. Verification test results showed that the rotating speed of a motor increased smoothly with the decrement of magnetoresistance. These findings indicate CB reinforced MRG magneto-resistor possesses excellent magnetoresistance and it can provide a novel and effectively mean for the motor's soft start-up. (paper)