A Novel Co-Simulation Strategy for Electric Motors across Electromagnetic, Circuit, and Mechanical Domains

Co-simulation plays a critical role in motor research and development. However, existing co-simulation methods fail to adequately simulate the loads experienced by motors under real operating conditions. To analyze electric motor behavior under realistic loads, this paper proposes a co-simulation strategy to form a closed loop across circuit, electromagnetic, and mechanical domains. Using a permanent magnet synchronous motor as an example, a finite-element electromagnetic model is established, while the inverter and control algorithm are implemented. A realistic mechanical load is modeled in Adams, replacing the step‑load commonly assumed in conventional studies. This study experimentally validates the proposed method using a 5840-36ZY brushed DC motor with a gearbox as the physical load. In addition, the effectiveness and accuracy of the method are further verified through comparisons with results reported in the literature. Compared with conventional simulations, the inclusion of the mechanical domain enables more realistic load interaction and significantly improves simulation fidelity. The framework is then used to study abnormal load scenarios, including gear tooth breakage, gear wear, and gear eccentricity. In the time domain, the electrical responses of the motor differ significantly under these faults. In the frequency domain, Fourier analysis of the stator current reveals distinct low‑frequency signatures: additional low‑frequency components for broken teeth, reduced fundamental amplitude for wear, and symmetric sidebands around the fundamental for eccentricity. The proposed method offers a practical route to more realistic and accurate multiphysics co-simulation of electric motors, and facilitates the detection and analysis of abnormal loads. This strategy allows for accurate condition evaluation and early fault identification of motor systems at the design and development stage, thereby offering substantial engineering value in improving the safety and reliability of the overall drive system.