Optimisation of the dual-contra-rotating motor dependent on propulsion characteristics of underwater vehicles

This paper proposes a dependent optimisation (DO) method for the dual-contra-rotating motor to improve the full-cycle efficiency and increase the space utilizstion rate of the autonomous underwater vehicle (AUV). Particularly, using the DO not only improves the efficiency of the machine at low speed and high speed, but also reduces its total weight by 6.2%, which is beneficial to the heavy-buoyancy matching and range improvement of the AUV. Moreover, the dependent optimized machine can leave about 5.5 L more space for other AUV systems. Firstly, the geometric constraints and the load characteristics of the dual-contra-rotating motor are presented. Based on the analytical model of the electromagnetic field and electromagnetic performance, this paper compares two analytical optimization methods for the machine. One is the independent optimization, that is, the geometric association between the dual-contra-rotating motors and the AUV is not considered in the optimization process. The other is DO, which considers the geometric association in the optimization process. After verifying the electromagnetic performance and temperature field with the FEA method, the dual-contra-rotating motor prototype was developed. Finally, the consistency of the optimization results and the prototype is verified through experiments.