Electrical machines are prone to various faults and require constant monitoring to ensure safe and dependable functioning. A potential fault in electrical machinery results in unscheduled downtime, necessitating the prompt assessment of any abnormal circumstances in rotating electrical machines. This paper provides an in-depth analysis as well as the most recent trends in the application of condition monitoring and fault detection techniques in the disciplines of electrical machinery. It first investigates the evolution of traditional monitoring techniques, followed by signal-based techniques such as spectrum, vibration, and temperature analysis, and the most recent trends in its signal processing techniques for assessing faults. Then, it investigates and details the implementation and evolution of modern approaches that employ intelligence-based techniques such as neural networks and support vector machines. All these applicable and state-of-art techniques in condition monitoring and fault diagnosis aid in predictive maintenance and identification and have the highly reliable operation of a motor drive system. Furthermore, this paper focuses on the possible transformational impact of electrical machine condition monitoring by thoroughly analyzing each of the monitoring techniques, their corresponding pros and cons, their approaches, and their applicability. It offers strong and useful insights into proactive maintenance measures, improved operating efficiency, and specific recommendations for future applications in the field of diagnostics.

Due to their efficiency and control capabilities, induction motors fed with inverters have become prevalent in various industrial applications. However, ensuring the reliable operation of the motor and diagnosing faults on time are crucial for preventing unexpected failures and minimizing downtime. This paper systematically analyzes condition monitoring and practical diagnostic techniques for inverter-fed motor drive systems. This study encompasses a thorough evaluation of different methods used for condition monitoring and diagnostics of induction motors, with the most crucial faults in their stator, rotor, bearings, eccentricity, shaft currents, and partial discharges. It also includes an assessment of their applicability. The presented analysis includes a focus on the challenges associated with inverter-fed systems, such as high-frequency harmonics, common-mode voltages causing the bearing currents, and high voltage gradients (dv/dt) due to fast switching frequency, which can impact the motor operation, as well as its faults analysis. Furthermore, this research explores the usefulness and efficiency of various available diagnostic methods, such as motor current signature analysis and other useful analyses using advanced signal processing techniques. This study aims to present findings that provide valuable insights for developing comprehensive condition monitoring strategies, and practical diagnostic techniques that enable proactive maintenance, enhanced system performance, and improved operational reliability of inverter-fed motor drive systems.

In this paper, a novel dual port counter rotating dual rotor wound field flux switching generator (DPCRDR-WFFSG) is proposed for direct drive counter rotating wind power generation. Mechanism of gearless and brushless counter rotating operation of DPCRDR-WFFSG is discussed and simplified formulation is opted for possible combination of the rotor poles number $(N_r)$ . In proposed DPCRDR-WFFSG, dual electrical ports are formed of non-overlapped armature winding having shared toroidal field excitation winding whereas inner and outer rotors act as inner and outer port. These inner and outer port are thoroughly investigated for electromagnetic performance to search out optimum rotor poles combination. The rotor poles combinations are examined under uniform and non-uniform poles and comparatively studied. Based on simplified formulation, various combinations of the rotor pole numbers are searched out and found that under uniform poles operation, $N_r= 10$ and $N_r = 14$ offers comparatively better electromagnetic performance whereas in case of non-uniform rotor poles $N_r = 10/14$ further improves electromagnetic performance. Furthermore, analysis evident that in comparison with the inner port, outer port shows dominant contribution in electromagnetic performance whereas, in comparison with uniform rotor poles, the new approach of adopting non-uniform rotor poles improve electromagnetic performance. It is worth noting that non-uniform rotor poles in inner ports improves efficiency and power factor whereas in outer port, average torque and output power are enhanced. Finally, validity of uniform and non-uniform rotor poles design approach for DPCRDR-WFFSG is verified with four prototype that validated finite element analysis.

To overcome drastic increase in rare-earth permanent magnet cost, avoid the requirements of brushes, slip rings, and eliminate gear-box mechanism, a novel magnet-less dual electrical and dual mechanical port wound field-excited flux switching generator (DEDMP-WFEFSG) for direct-drive counter rotating wind turbine (D ² CRWT) application is proposed in this paper. The proposed DEDMP-WFEFSG encompasses a stator with dual non-overlapped armature and toroidal field excitation windings; thus, offers reduced overhang and makes the design compact. To ease the design process, lumped parametric magnetic circuit model (LPMCM) for one magnetic pole is formulated. To evaluate the LPMCM design, finite element analysis (FEA) study is undertaken in co-rotation and counter rotation with focus on power distribution between the inner and outer ports. From detailed analysis, it is evident that in comparison with the inner port, the outer port machine offers better average torque, power factor and efficiency. Compared with co-rotation, counter rotation shows improved electromagnetic performance. Finally, to validate the LPMCM and FEA based simulation, a prototype is developed and tested with satisfactory results.

Switched Flux Permanent Magnet Machine (SFPMM) encompass unique features of conventional direct current machine, permanent magnet (PM) synchronous machine and switch reluctance machine therefore, applicable for high-speed applications. However, conventional SFPMM exhibits demerits of high PM volume ( V_PM ), high torque ripples ( T_rip ), higher cogging torque ( T_cog ), lower torque density ( T_den ) and significant stator flux leakage. In this paper, a new topology of consequent pole (CP) SFPMM (CPSFPMM) is proposed having partitioned PM that improved flux modulation phenomena utilizing flux barriers. Moreover, due to non-linear behaviour of PM and complex stator structure alternate analytical sub-domain model is utilizes for initial design. However, initial design offers lower open-circuit phase flux linkage (Φ), average mechanical torque ( T_avg ) and T_den . Aforementioned electromagnetic key performance indicator with T_cog , T_rip , total harmonics distortion in Φ (Φ _THD ), average power ( P_avg ) and power density ( P_den ) are refined utilizing Geometric-Based Deterministic Optimization (GBDO). Analysis reveals that proposed new topology of CPSFPMM with flux barriers reduces T_cog by 34.90%, T_rip by 20.27%, Φ _THD by 28.08% whereas it enhanced P_avg by 17.79%, T_den and P_den by 34.38%.

This paper proposes a new modular hybrid excited flux switching motor (MHEFSM) with flux gaps, adding the fault-tolerant capability to the proposed motor. The proposed motor uses an E-Shaped stator, as the middle teeth of E-core produce fault-tolerant capability, and in C-core, this capability is eradicated. The no-load flux linkage is calculated by the magnetic network model (MNM) to reduce time and disk storage. The drawback of the constant flux linkage of PM motors is overcome by employing field excitation (FE). The FE helps in regulation flux at higher speeds. The motor leading geometry variables are optimized by using Genetic Global Optimization (GGO). The GGO helped in refining the structure of the motor and has improved the flux linkage by 68.18%, average torque and torque density by 62.35% each, reduced torque ripples by 20.62%, and cogging torque by 18.52%. The volume of permanent magnet (PM) in the proposed MHEFSM is reduced by 36.24%, and 48.49% higher average torque and torque density is obtained compared to the state of art motor proposed in the literature. Furthermore, a 3D analysis of the proposed MHEFSM is done to further evaluate the electromagnetic performance.