Electric drive systems encounter significant challenges in mitigating motor shaft voltage and bearing currents, primarily due to common-mode voltage (CMV) effects. While many studies have explored pulse width modulation (PWM) strategies to reduce CMV, the majority have focused on low-frequency domain analysis. This paper evaluates the high-frequency performance of the electric drive system considering various PWM techniques, including Space Vector PWM (SVPWM), various discontinuous PWM (DSPWM) methods, Active Zero-State PWM (AZSPWM), Remote-State PWM (RSPWM), and Near-State PWM (NSPWM). To ensure the applicability of the study, a detailed electric drive system model (including inverter, cable, and motor models) has been implemented and simulated. Moreover, a comparative analysis is conducted across a wide motor speed range (500 rpm to 3000 rpm), analyzing CMV dynamics, motor line-line voltage, shaft voltage, and total harmonic distortion (THD) of motor current. From the results, AZSPWM, RSPWM, and NSPWM demonstrate superior CMV and shaft voltage mitigation, making them suitable for reducing bearing current, while SVPWM offers the best current quality. The findings provide insights for selecting appropriate PWM strategies at different operating conditions. The simulation was conducted using MATLAB software, and the data was post-processed using ModeFRONTIER.

When an electric drivetrain is ordered for deployment under load conditions different from those encountered during its design and testing phases, it is crucial to evaluate its performance beforehand. However, the experimental validation of the efficiency of an electric drivetrain for a new load profile is time-consuming and costly. This article proposes a digital twin approach to estimate the efficiency of an entire drivetrain for a new load profile—one that has not yet been tested on the physical asset. The parameters of the digital twin are determined through a system-level optimization study, utilizing measured data from the load cycles in the time domain. Utilizing this digital twin, the efficiency of the drivetrain is estimated for a new load profile. Subsequently, experimental validation is conducted. The results demonstrate that the proposed approach is accurately assessing drivetrain performance in terms of efficiency for new load profiles, facilitating informed decision-making in deployment scenarios.

In this study, six promising interior permanent magnet (IPM) motors are designed as a spindle motor for computer numerical control (CNC) milling machine application. An existing surface-mounted permanent magnet (SPM) motor in a CNC is selected for a baseline motor. In order to reach more high speeds as to SPM motor, six different IPM rotor topologies are investigated while keeping the exact stator structure and windings of the reference motor. A comprehensive comparison of the IPM rotor topologies is performed, and the benefits and drawbacks of the designs are highlighted. The best performance design is selected and manufactured for experimental studies. No-load and on-load tests are performed by a motor test system, and the obtained results are compared with the finite element analysis (FEA) results. It is observed that the results are in good agreement. It is shown that it is possible to have an optimized IPM motor for such high speed spindle application by using same stator and winding structure with reference SPM motor.

This paper presents magnetic equivalent circuit (MEC) modeling approaches for an unbalanced and asymmetric winding 39-slot 12-pole permanent magnet (PM) motor. Such unconventional slot-pole configuration has certain benefits over conventional integral slot PM motors such as low cogging and torque ripple, and low rotor manufacturing cost. This slot-pole combination leads difficulty in analytical modeling since the motor symmetry is different from conventional PM motors. Simpler MEC modeling approaches would be useful in designing such motors with unconventional combinations. Four different MEC modeling approaches are investigated in this paper for an experimentally verified 39-slot 12-pole motor. Benefits and drawbacks of each approach are presented. No-load and on-load results obtained from MEC modeling approaches are compared with the finite element analysis (FEA) and test data to illustrate the benefits of the modeling approaches.