Preliminary design of rim-electric driven propeller and effect factor analysis on cogging torque

  Objectives  Cogging torque has an important influence on the blade vibration of a Rim-Electric Driven Propeller (REDP). In order to investigate a method for reducing the cogging torque of REDP, this paper analyzes the combination of slot number, pole number, tooth shape and pole arc coefficient on the influence of cogging torque.

  Methods  First, according to the Ka4-50 propeller model parameters and the design standards of the Permanent Magnet Brushless DC Motor, a 36-slot and 26-pole driven motor is designed. The magnetic circuit calculation software Maxwell Rmxprt is then used to analyze the influence of different slot number and pole number combinations, tooth shape and pole arc coefficient on the motor.

  Results  The results show that for a frictional slot and concentrated windings motor, the amplitude of the cogging torque is inversely proportional to the lowest common multiple. Among opening slots, closed slots and half-closed slots, half-closed slots have the greatest torque, opening slots have less and closed slots have the least. The influence of pole arc coefficient on cogging torque shows a fluctuation rule. In the design, it is necessary to find the extreme pole arc coefficient corresponding to the minimum value of the cogging torque through specific analysis.

  Conclusions  This paper provides references for the overall design of REDP and a theoretical basis for further exploring the influence of the motor on the vibration and noise of REDP.