Rotating Electrical Machines: Types, Applications and Recent Advances

: The Rotating Electrical Machines (REMs) are classified into Motors and Generators. They powered the industrial, domestic and commercial loads. Because of their importance. This paper discussed different types of REMs, their applications and recent advances. REMs are applied in Teaching, Domestic, Mechatronics, Motorcycle, Three-wheelers, Electric Vehicle, Healthcare, Flywheel Energy Storage and Wind Energy Conversion Systems. It periscopes the advances of REMs in design, Fault diagnostic, control and condition monitoring . Its significance is to shed light on some advances made in REM.


Introduction
Electrical Rotating Machines are the driven horses in power plants, construction, transportation, agriculture and automation sectors (Dineva, et al., 2019).REMs are the sources of mechanical power in industries because of their robustness and reliability (Martinez-Roman, et al., 2021).Electrical Machines can be broadly classified into Stationery and Rotational Electric Machines.The stationary Electrical Machines are the Transformers (Figure 1) their operation is not based on motional-Electro-Motive-Force (EMF).The Rotating Electrical Machines are AC and DC Generators and Motors which operate based on motional EMF (Figures 2,3,4 and 5).The main components of REM that can fail are the rotor and stator windings, rotor and stator laminated core, bearings, magnets, airgap, load and auxiliaries (Frosini, 2020).

Related studies
There is new research and development on REM which makes them more and more relevant to our lives.The diagnostic methods for REM were classified and reviewed in Djagarov, et al., (2020).Frosini, (2020) reviewed the current methods of diagnosis of Electrical Machines.The techniques of condition monitoring of Electrical Machines were reviewed by Kande, et al., (2017).The magnetic flux analysis for condition monitoring of Electrical Machines was reviewed by Zamudio-Ramirez, et al., (2022).The different technologies of high-speed Electrical Machines were presented by Gerada, et al., (2014).The different models and measurements of core losses of soft Magnetic Materials for Electrical Machines were discussed by Guo, et al., (2008).This paper presents the types of REM, their Applications and Recent Advances and it ends with a conclusion.

Types of Rotating Electrical Machines
The different types of REM are the Brushless DC Machines (BLDCM) (Kethiri, & Charrouf, 2023;Akar, Eker, & Akin, 2021), Induction Machines, Synchronous Machines, and Switched Reluctance Machines (SRM) (Akar, Eker, & Akin, 2021).Others are the Doubly Fed Induction Machine and the Brushless Doubly Fed Induction Machine (Frosini, 2020).There are also Synchronous Reluctance Machines (SynRM), AC Homopolar Machines (ACHM) and Bearing-less Machines (Cristea, 2023).The Induction Motor is a very popular REM because it is cheap and rugged (Dineva, et al., 2019).The electric traction machines consisting of Voltage Source Inviters driving electric machines are REM (Dineva, et al., 2019).Other types of electric traction machines in electric vehicles are the permanent magnet and variable reluctance machines which possess high power density and simple control methods (Kethiri, & Charrouf, 2023).Section 3.0 discusses the applications of REM.

Applications of Rotating Electrical Machines
The REMs find applications as generators in power generation, in gas compressors for oil, chemical and gas industries, in industrial Air Compressors, in Air Blowers in the pharmaceutical industry and in turbomolecular pumps (Gerada, et al., 2014).This section briefly discussed the applications of REM.

Application in Teaching, Domestic and Mechatronics
The DC Motor was applied in a closed-loop control system to teach students the function of the PID Controller (Dume, & Metalla, 2023).The REMs are applied in hardware in the loop to teach students the virtual instrument measurements in electrical laboratories (Dume, & Metalla, 2023).The Rotating Electrical Machines are applied in teaching the characterization of the three-phase-induction motor (Torrent, Martinez, & Perat, 2020).The Induction Motors are applied in vacuum cleaners, and ceiling Fans (Vishwakarma,. & Keshri, 2023).The small-sized rotating electric machines are applied in the actuation of mechatronic systems (Akawung, Ebot, & Fujimoto, 2023).

Application in three-wheelers and Scooters.
The small-size Rotating Electrical Motors are used in in-wheel systems like Moto/Scooters, because of improved torque which increases acceleration in slope conditions (Gong, et al., 2022).The switched Reluctant Motors are widely used in three-wheelers because they are efficient in reducing windage loss of the wheelers (Seshadri, & Natesan, 2023).

Application in Electric Vehicles and Healthcare
The induction motor based on Direct Torque Control is applied in Electric Vehicle (EV) propulsion systems due to its simplicity in construction and rapid response (Singh, et al., 2006).The Brushless Direct Current (BLDC) Motors are applied in Light Electric Vehicle (Akar, Eker, & Akin, 2021).The Permanent Magnet Synchronous Motor(PMSM) finds application in Electric Vehicles because of its high efficiency (Keshari, & Jarariya, 2023).The DC Motor is applied in the crank-shaft to turn the arm of a ventilator system while delivering oxygen to patients (Raffik, et al., 2023).

Application in Flywheel Energy Storage and Wind Energy Conversion Systems
The electrical Rotating machines are applied in the Flywheel Energy Storage System (FESS) which has advantages such as high efficiency, long lifetime, scalability, high power density, and fast dynamic, over other energy storage systems (Takarli, et al., 2023).The DC Electric Machine driven by a traction Motor was applied in the Flywheel Energy Storage System to increase the efficiency of mining and lifting machines (Barbashov, Polyantseva, & Smirnov, 2023).The Synchronous Machines have been very efficient and are applied in the Wind Energy Conversion Systems which are environment friendly (Fager, & Kosanlioglu, 2023).

Recent Advances in Rotating Electrical Machines
This paper briefly discussed the recent trends in the Fault Diagnosis of REMs, control and condition monitoring of REM, and Design of REM.

Trend in Fault Diagnosis
Fault Diagnosis consists of filtering, preprocessing, feature extraction and pattern recognition (Djagarov, et al., 2020).Protecting critical Machines against failure is vital for improved availability of Machines in industrial settings leading to reduced maintenance costs (Alshorman, et al., 2020)

Trends in control and condition monitoring
The Adaptive Neural Fuzzy Inference System (ANFIS) was reported by Djagarov, et al., (2020) as a new method for monitoring faults in electric machine bearings.A new trend in the estimation of the operating temperature of the Stator, Rotor, Winding and Yoke of Permanent Magnet Synchronous Motors is by applying the deep recurrent convolution Neural Networks (Kirchgässner, Wallscheid, & Böcker, 2021).The hardware platform of Electric Motors finds application in the emulation system to collect enough data to train Machine Learning Models (Zhang, Wallscheid, & Porrmann, 2023) for control and monitoring of electrical machine drives.The search-coil and hall sensors are applied to monitor the condition of electrical machines based on internal magnetic flux measurement, while ferromagnetic core and fluxgate sensors are better options for external flux sensing (Gurusamy, et al., 2022).

Trends in the Design of Rotating Electrical Machines
The recent improvement of Permanent Magnet materials, microelectronics and solid-state devices has increased the efficiency of brushless Motors (Dineva, et al., 2019).The present trend in selecting material for laminated rotors is the utilization of high-strength electrical steel grades to fabricate high-speed Induction Motors (Gerada, et al., 2014).Another trend is the replacement of laminated steel sheets with soft Magnetic Composite Materials for the fabrication of rotor and stator cores of rotating electrical generators for high-frequency operation (Dias, et al., 2020).In Ajamloo, Ibrahim, & Sergeant, ( 2023) the rotor T-shape of a Permanent Magnet Electric Machine was modified, leading to reduced harmonics in the air-gap, and reduced torque ripples in the machine.A cost-effective prototype slot-less toroidal stator wind machine was fabricated in Garrido, & Silveyra, (2023).The wiring stages consist, of the winding of a primary copper spool, the transfer of the primary copper spool onto the secondary spool, and it is unwinding onto the toroidal core.In Ashouri-Zadeh, & Nasiri-Gheidari, (2023) the Global search, additional stator and stator teeth shifting methods were applied to reduce force ripples in the Tubular Permanent Magnet Linear Machines(TPMLM).
The low magnetization rate of narrow space in designing of spoke-type Permanent Magnet Synchronous Motors (PMSMs) using postassembly method was solved using a novel yoke structure that reduced the gap between the coil and magnet (Jeong, et al., 2023).Besides the eddy current loss model, Pyrhönen, et al., (2015) added the hysteresis loss model in calculating the losses in the Permanent Magnetic Core of REM.(Fujimoto, Senington, & Holmberg, 2023).

Conclusion
The single-phase Generators and Motors are applied in lightening, heating and cooling appliances, while the three-phase Generators are applied to power three-phase loads.

Table 1 . Summary of Applications of Rotating Electrical Machines
The switched Reluctant Motors are applied in threewheelers because of their efficiency in reducing windage loss in the wheelers while the PMSMs are applied in Electric Vehicles due to efficiency.The recent types of Rotating Electrical Machines are AC Homopolar Machines (ACHM) and Bearing-less Machines.Image Processing, Machine Learning Data Acquisition, multi-level classification and Artificial Intelligence are the recent techniques for detecting faults in Rotating Electrical Machines.Machine Learning, ANFIS, Deep Recurrent Convolution Neural Networks, search-coil and hall sensors, are new methods for monitoring faults in Rotating Electrical Machines.The recent trend in materials for fabricating rotor and stator cores of high-speed rotating electrical generators is the use of highstrength electrical steel grades and soft Magnetic Composite Materials.A new design method for calculating the losses in the Permanent Magnetic Core of Rotating Electrical Machines is the addition of a hysteresis loss model with an eddy current loss model.