Design and Optimization of Direct-Drive Drilling Permanent Magnet Synchronous Motor

Abstract A direct-drive drilling electric drilling tool is developed due to the problems of long transmission link, low efficiency, and high failure rate of traditional electric drilling tools. In this paper, the key components of the direct-drive drilling permanent magnet synchronous motor (DPMSM) are designed and calculated, and the robust parameters optimization is performed by Taguchi method with efficiency and cogging torque as the optimization objectives. The air-gap length, thickness of permanent magnets, pole-arc coefficient, and width of slot top are selected as significant factors, and the impact of the optimized parameters on the efficiency and cogging torque of the DPMSM is calculated with orthogonal experiment to obtain the optimal combination of factors. Comparing the DPMSM’s performance before and after optimization, the cogging torque is reduced by 80.1% and the efficiency is improved by 0.24% after optimization. Finite element simulation of the electromagnetic characteristics of the optimized DPMSM under no-load and load conditions is carried out to verify the rationality of the optimization. Calculate the main losses of the DPMSM and the heat generation rate of key components. The analysis model of the DPMSM’s temperature field is established, and the temperature field simulation is carried out with and without drilling fluid respectively to further verify the rationality of the motor’s design. This work can promote the engineering application of downhole direct-drive electric drilling tools and provide technical support for the innovation of drilling equipments for marine energy.