Today, the majority of the commercial electrified vehicles use Interior Permanent Magnet Motors (IPMSMs) for propulsion. An IPMSM can deliver high starting torque and high efficiency in the low- and medium-speed operation, which makes it attractive for propulsion applications. However, IPMSMs generally utilize rare-earth permanent magnets and there are growing concerns about the price volatility and supply chain of these materials. Switched Reluctance Motors (SRMs) can potentially replace IPMSMs in various applications including propulsion. An SRM has a simple and low-cost construction, and it can provide reliable operation at high-speed and high-temperature conditions. Compared to IPMSMs, SRMs radiate considerably higher acoustic noise, which have historically hindered their widespread acceptance. Various approaches to mitigate acoustic noise and vibration at the source level have already been explored in the literarture by improving the electromagnetic design and current control. This paper explores multiple noise and vibration mitigation methods that can be applied at the transmission stage. First, the noise comparison between the Internal Combustion Engine (ICE) and SRMs is discussed, and then the methods used for ICEs are presented for their applicability to SRMs.

Interior permanent magnet synchronous motors (IPMSMs) are extensively used as traction motors today because of their exceptional torque, power density, and wide, constant power operating range. Under real-world usage, an IPMSM rotor undergoes varying electromagnetic, thermal, and mechanical loads. Under such conditions, fatigue life-based design criteria should be used over stress-based design criteria to ensure the structural integrity of the rotor. Moreover, the driving dynamics can change the rotor temperature continuously, which affects the electromagnetic, mechanical, and fatigue properties of the rotor material. This paper proposes a robust thermomechanical rotor fatigue simulation workflow considering significant loads acting on an IPMSM rotor and the temperature variation throughout a drive cycle. It discusses an accelerated fatigue life estimation approach based on the peak valley extraction method to reduce the simulation time significantly for the stress and fatigue analysis. Then, it presents a method for a stress-life curve generation for variable loading. It also presents a sensitivity study with a median S-N curve, and a 90% reliability and 95% confidence (R90C95) S-N curve.

Interior Permanent Magnet Synchronous Motors (IPMSM) are widely used as traction motors today because they can deliver high torque at low speeds, and high efficiency at low- and medium-speed ranges. Air flux barriers and bridges of an IPMSM have contradictory electromagnetic and structural requirements. The rotor undergoes a fluctuating load due to varying speeds in a drive cycle. Designing the rotor with the yield strength as a design criterion might not be sufficient. Fatigue life should be evaluated considering the mean value and amplitude of the fluctuating load profile, and the acceptance criteria should be derived based on field operations. This paper proposes a constant amplitude load cycle as an accelerated fatigue analysis approach for an IPMSM rotor and presents a fatigue analysis workflow considering the thermal and mechanical loads. It also presents the loads and boundary conditions for rotor stress analysis and the effect of elastic and elastic-plastic material properties on stress calculation.

This paper introduces a technique aimed at improving the performance of an interior permanent magnet synchronous machine (IPMSM) by reducing torque ripple and radial force harmonics. Unlike conventional IPMSMs, the proposed method employs a variable airgap length that is defined by a mathematical function. Two distinct rotor shapes are investigated to determine the most efficient design. Finite Element Analysis is employed to assess both the electromagnetic and mechanical attributes of the proposed motors. It compares the results for three operating points of the shaped motor with those of a conventional one. The investigation delves into the influence of rotor geometry on key output parameters, including Back Electromotive Force (back‐EMF) harmonics, average torque, cogging torque, torque ripple, efficiency, power factor, and radial force harmonics. The findings indicate that optimising rotor shape can significantly enhance IPMSM performance by reducing torque ripples and radial force harmonics, while simultaneously increasing average torque and efficiency at different operating points.

This paper presents the mechanical design of a 70 kW Switched Reluctance Motor prototype with a nominal airgap length of 0.4 mm with a relatively large stator outer diameter of 280 mm. It presents the mechanical design considerations and manufacturing tolerances that are vital for an electric motor to maintain component integrity and meet performance requirements. Multi-stage design of the mechanical components and fittings for the complete mechanical system are presented and justified with finite element analysis results. The radial and axial stack-up analysis are presented which account for the dimensional variations during the manufacturing of motor components. The assembly of the motor prototype is described, which demonstrates that the axial and radial alignment of the motor components are achieved while maintaining the small airgap length required. The motor assembly is then verified with static end-of-line tests, such as winding insulation and housing leakage tests. Additionally, experimental modal analysis of the housing assembly is performed to examine the influence of the winding, housing, and potting on its modal frequencies and damping characteristics.

There is an increasing research focus on computationally evaluating the acoustic noise and vibration of Switched Reluctance Motors (SRMs) using Finite Element (FE) tools. The accuracy of the calculated acoustic behavior of an electric motor relies heavily on the fidelity of the finite element model. The finite element model of a stator-housing assembly poses a challenge due to the orthotropic behavior of electrical steel and the non-uniform geometry of the windings. This paper introduces an experimental modal analysis approach to calculate the modal characteristics of a 12/8 SRM stator-housing assembly, investigating the effects of winding and housing on these characteristics. Additionally, the study involves analytical calculation and finite element modeling, correlating the results with experimental values to enhance understanding and accuracy in predicting acoustic behavior. It also presents a polynomial function to calculate modal damping parameters and investigates the applicability of the analytical equations commonly used in the literature to the tested SRM.