Permanent magnets (PMs) have been widely used in different types of electrical machines to improve their performance. This article introduces a novel multi-tooth hybrid-excited switched reluctance ...motor (MT-HESRM) with PMs placed between the end teeth of the adjacent modules. Thanks to the innovative method of embedding PMs, a unique design is developed. First, the operating principle of the motor is explained, and the magnetic circuit model of the motor is analyzed. The magnetic characteristics in terms of flux density, flux linkage, inductance, and torque are obtained and compared with those of its PM-less counterpart. The mathematical model of the reluctance and PM torques is presented. The reluctance and PM torques are decoupled using the finite-element analysis, and the torque contribution of the PMs is discussed. The steady-state operations of both motors with both current chopping and single-pulse controls are analyzed and compared under different speeds. Finally, both motors are manufactured, the laboratory tests are done, and the experimental results are extracted. Both the simulation and test results elucidate that the MT-HESRM, which has only three small PMs as auxiliary flux sources, has unique features in terms of high output power and torque with a negligible cogging torque.
This study elaborates upon a new modular split‐tooth permanent magnet‐assisted switched reluctance motor (MSTPM‐SRM). In the proposed topology, the stator comprises six modular E‐cores in which the ...middle poles are split into two teeth. Two permanent magnets (PMs) are placed between each module's middle and side poles. Primarily, the proposed topology is introduced. Next, the principle of operation of the proposed topology are elucidated, and the magnetic equivalent circuit analysis is adopted in order to validate the operational basics. It is proved that the embedded PMs significantly increase the air‐gap's flux density and adjusts the poles' flux density. The flux density distributions, static, and steady‐state characteristics of the proposed MSTPM‐SRM motor and its PMless counterpart are extracted by utilising 2‐D finite element analysis. It is illustrated that the average torque of the proposed MSTPM‐SRM is dramatically increased compared to its PMless counterpart, especially at high excitation currents. Furthermore, the cogging torque analysis is done and it is shown that the proposed structure has approximately zero cogging torque. Finally, a prototyping version of the proposed motor is fabricated, and the experimental results are elicited. It is shown that the experimental results endorse the simulation results.
This paper elaborates upon a new modular split‐tooth permanent magnet‐assisted switched reluctance motor. In the proposed topology, the stator comprises six modular E‐cores in which the middle poles are split into two teeth. The results show that the proposed structure dramatically increases the average torque of the motor.
In this article, a novel exterior-rotor multiple teeth enhanced-torque switched reluctance motor (SRM) is proposed, which exploits permanent magnets (PMs) inside the end teeth of the neighboring ...stator poles. First, the topology of the proposed motor, namely PM-SRM, is introduced and its working principle is illustrated. Then, based on the magnetic equivalent circuit (MEC) of the motor, it is proven that the PMs contribute to increase the air-gap flux density and regulate the stator poles flux density. As a result, the output torque of the motor is increased as well. The electromagnetic analyses of the proposed PM-SRM are performed using 3-D finite-element analysis. To validate the improved performance of the proposed PM-SRM, it is compared with its PMless counterpart and a classical 12/10-pole SRM in terms of the output torque and power, losses, and efficiency. It is shown that the proposed motor outperforms the two compared motors in terms of the output power and torque, and efficiency. Finally, a prototype of the motor is fabricated and tested to evaluate the predicted results. Both simulation and experimental results demonstrate the high torque and power production capability of the proposed PM-SRM.
This article proposes an enhanced-torque switched reluctance motor with two sets of permanent magnets (PM-SRM) embedded inside the stator yoke and the end teeth of the neighboring modules. The PMs ...contribute to intensify the air-gap flux density and reduce the magnetic saturation in the stator poles. As a result, the output torque can be enhanced to a significant extent. The working principle of the proposed PM-SRM is clarified using its magnetic circuit model (MCM). The characteristics of the PM-SRM are obtained and compared with classical 12/8 and 6/5 SRMs and hybrid reluctance motors (HRMs) in terms of static and average torque and average torque per PMs volume. The steady-state performance of the PM-SRM in terms of current and torque waveforms is carried out, and the PM-SRM is compared with considered SRMs and HRMs in terms of output torque, power, and efficiency. All the comparisons demonstrate the out-performance of the proposed PM-SRM over other SRMs and HRMs. To validate the simulation results, a prototype of the PM-SRM is manufactured and the experimental results are obtained. Both the simulation and experimental results are indicative of the fact that the proposed PM-SRM can gain high torque and high PM utilization factor, simultaneously.
In this paper, a new multi-tooth switched reluctance motor (MT-SRM) is proposed and then based on the original topology, three novel multi-tooth hybrid reluctance motors (MT-HRMs) are introduced to ...improve the torque characteristics of the SRM. The proposed structures are an MT-HRM with permanent magnets (PMs) between the side teeth of the adjacent modules, an MT-HRM with PMs in the yoke, and finally an MT-HRM with dual-PM configuration. The operating principles of the MT-HRMs are illustrated and the flux adjusting effect and outstanding torque production ability of the PMs are demonstrated through the theoretical and simulation results. The flux distributions and static torque and flux linkage profiles of the motors are obtained and compared. The four proposed motors are compared in terms of the steady-state current and torque waveforms. All the simulation results indicate that the PM-assisted structures can achieve higher torque and power than their PMless counterpart with deploying only three/six small PMs. The four motors are prototyped and the experimental results are carried out. Both the experimental and simulation results prove the effectiveness of the proposed MT-HRMs.
This article proposes an improved biased-flux motor in which the permanent magnets (PMs) are placed between the stator modules, therefore called intermodular PM (IMPM) motor. The proposed structure ...has increased the torque density while maintaining a low torque ripple. Moreover, due to the specific placement of PMs, the PMs are extensively protected from demagnetization. The operation principle of the proposed IMPM motor is thoroughly discussed using flux modulation theory (FMT) and is comparatively analyzed with other biased-flux structures. Based on this analysis, a new theoretical formulation is also drawn to calculate the power factor (PF), which involves design-related parameters. It has been studied that since the PMs are far from armature winding in the proposed structure, the PMs' thermal stress is even less than other stator-PM structures. Due to this placement, the PF of the proposed motor is drastically improved compared with other biased-flux motors. The no-load and full-load performances of the IMPM motor are studied using the finite element method (FEM). A comprehensive comparative study is also conducted to better locate the proposed structure in the biased-flux motors. Finally, a 6/11 IMPM motor is prototyped and tested to experimentally validate the theoretical and FEM analyses.
Net zero and electrification targets are continuing to enforce a need for the development of high-performance electrical machines, increasingly based on the use of rare earth permanent magnets. ...Biased flux motors have the potential to overcome some of the disadvantages associated with more conventional electrical machines. Since their introduction, there has been a consistent trend towards new and improved topologies, all relying on the same principles of operation. In this paper, a new alternative operation is proposed where the magnetic flux density offset of each module is different. The resulting asymmetric biased excitations of the magnets leads to a flux concentration in the air gap. Placement of magnets in the slot-opening area is shown to produce a higher average torque at a higher power factor. It is mathematically shown that the conventional methods used to investigate the effect of each group of magnets separately cannot be used for the explanation of this operation principle. Therefore, it is necessary to simultaneously consider both groups of magnets in the magnetic equivalent circuit. Due to the use of magnets in these motors, thermal conditions are also investigated. Finally, a comprehensive comparison between several stator-situated-magnet motors is presented. The performance of the proposed motor is improved in terms of average torque, torque density, PM torque density, power factor, and overload capability. The torque density specifically has increased by 9%. Moreover, both motors have suitable thermal behaviour which confirms the validity of the demagnetization analysis.
A comprehensive study on divided-teeth permanent-magnet assisted outer-rotor switched reluctance motors (SRMs) is carried out. Foremost, it looks into the impact of the number of teeth per stator ...pole. The average and maximum torque profiles of the compared structures are obtained using finite-element simulations. It is shown that as the number of teeth increases, higher torque is obtained. Then, six small PMs are inserted inside the teeth of neighbouring modules to form new hybrid reluctance motors (HRMs). The four permanent-magnet assisted SRMs are compared in terms of the average and maximum torques using finite-element simulations. Based on the comparison results, the 48/50 HRM is selected as the best candidate among all compared SRMs and HRMs. The magnetic flux density distributions, static torque, and flux linkage characteristics of the proposed HRM are obtained. Moreover, the cogging torque profile of the motor is obtained, which approximates to zero. Next, the steady-state performances of the proposed HRM are obtained under low- and high-operating speeds. Finally, a prototype of the machine is constructed and the test results are obtained and compared with those of the simulations, which show that there is a good agreement between these results.
Natural and forced instabilities have a significant influence on the performance and efficiency of biomass-fueled combustion systems, where oscillatory behaviors cannot be ignored. This work ...concentrated on the analytical modeling of pulsating biomass-fueled diffusion flames in the non-premixed counter-flow arrangement, accounting for the effects of Lewis and Zeldovich numbers. Preheating, post-vaporization, reaction, and oxidizer zones were considered in the model derivation. In order to model the oscillatory characteristics, oscillations were mathematically modeled using a sinusoidal function. Transient mass and energy balance equations were formulated and analytically solved considering different Lewis and Zeldovich numbers. To preserve continuity and obtain the flame front position, jump conditions were given. After validating the derived analytical model, transient characteristics of flame temperature and position and time-varying distributions of reactants temperature and mass fraction were presented under pulsating conditions. Results show that Lewis number is the main parameter controlling the oscillatory and pulsating behaviors of the flame. Furthermore, Zeldovich number seems to escalate the effects of Lewis number.
