Study on the Rotor Bar Curvature to Increase Starting Torque in Cryogenic Induction Motor

Induction motors in Liquefied Natural Gas (LNG) pumps located inside LNG vessels operate submerged in -163°C LNG. Consequently, when the pump is not in use, components including bearings freeze, necessitating a design focus for cryogenic induction motors on achieving high starting torque over other aspects like efficiency. This paper has investigated the rotor bar design that maximizes starting torque in cryogenic environments for induction motors. Contrary to typical induction motors, it was found that in cryogenic conditions, the highest starting torque occurs where the front curvature of radius of the rotor bar is larger. This phenomenon is attributed to the greater influence of leakage inductance in cryogenic conditions compared to room temperature.