Slot Combinations Research Articles

유도전동기의 슬롯 조합에 따른 진동/소음 특성 분석

The objective of this study is to examine the vibration and noise characteristics of a four-pole induction motor regarding the number of rotor slots. There are thirty six stator slots in the reference model, and its results are theoretically verified in case of a twenty-four-slot stator. Radial force density is obtained from two magnetic flux densities in the radial and tangential direction, and vibration performance is comparatively evaluated in terms of a rotor slot number by dividing radial force density into its temporal and spatial components through Fast Fourier Transform (FFT). Noise as the definition of sound pressure level is estimated in the units of decibels, and the noise of each motor is correlated with its vibration acceleration regarding temporal and/or spatial harmonic orders. In conclusion, the combination of stator and rotor slot numbers is critical since the 2nd orders lead to the deterioration of vibration and/or noise. As a result, the existence of the 2nd orders has to be carefully checked in advance by using several equations before the determination of physical dimensions in an induction motor in detail. In this paper, those equations have been given, and the comparison of vibration and noise in terms of a slot combination has been detailed in the step-by-step manner.

계자권선형 동기전동기의 극 슬롯 조합에 따른 전자계 특성 비교

This paper analyzes the electromagnetic characteristics of wound field synchronous motor (WFSM) for home appliances according to pole slot combination. The analyzed factors are output torque, total harmonic distortion (THD) of back-EMF, cogging torque, efficiency and power factor (PF) which should be considered when designing motors. The pole slot combinations are selected with same number of slots per pole per phase (NSPP) of prototype interior permanent magnet synchronous motor (IPMSM). Because the electromagnetic performances show specific tendencies depending on the number of poles and each performance tends to be different, this study can be a reference in determining pole slot combinations of WFSM.

Influence of Slot Combination on the Vibration of Low-Noise Asynchronous Motor

The slot combination of stator and rotor plays a decisive role in the tangential force and radial force of the motor, to obtain the influence of slot combination on motor vibration and noise, taking a 55kW asynchronous motor with a maximum speed of 1500 r/min as an example, and four kinds of motors with different slot combination were designed. The order and frequency of electromagnetic force waves with different slot combinations were estimated by numerical method, and the influence of slot combination on the vibration of the motor was studied by test.

Using combined slots as a new approach for optimizing erodible bed changes around the spur dikes in series

ABSTRACT The common spur dikes, which are used for river path control and bank protection, are utilized without any slots or with additional structures such as a collar or vane. The present research has been conducted to optimize the slot position in the spur dikes’ body, reduce the scour depth, and improve the sedimentation conditions using the CFD model. The numerical result was compared with the Nayyer et al. 2019. A numerical and experimental investigation of the effects of combination of spur dikes in series on a flow field. Journal of the Brazilian Society of Mechanical Sciences and Engineering, 41(6), 1–11) experimental outcome. Results showed that the (LS-W-Wi, TS-W, TS-W-Wi ) combination contained the slots in the web and wing of the first and third spur dike, and the slot at the web of the middle spur dike was found as the best combination of slots under clear-water conditions. This combination was conducted to reduce the scour depth by 6.8% and increase deposition by 52% compared to the spur dikes without slots, which causes reducing scour depth and an increase in the sedimentation rate of materials between two consecutive spur dikes in series. Also, the maximum scours depth decreases by up to 20%. The results revealed that the presence of slots in spur dike and their different positions have complicated and considerable influences on the form and morphology of the bed.

Improvement of Integrated-Induction-Based Hybrid Excitation Brushless DC Generator by Employing Novel Consequent-Pole Rotor

In order to achieve both the brushless excitation and flexible regulation of output voltage, the integrated-induction-based hybrid excitation brushless dc generator (II-HEBDCG) combining the main generator part with the induced excitation part is presented in this article. Moreover, the novel consequent-pole rotor featuring the pole sequence of iron-S-iron-iron-N-iron (I-S-I-I-N-I) is proposed to enhance the flux regulation capability because each coil of the main field winding (MFW) can regulate the flux of two iron poles simultaneously, where the flux paths of permanent magnet and MFW exhibit in parallel. The selection rules of pole and slot combination are summarized theoretically, and the principle of flux regulation is revealed based on the equivalent magnetic circuit, which are confirmed by finite element analysis. Then, the influences of key parameters on the performance are discussed. Furthermore, the electromagnetic performance of the proposed II-HEBDCG with the pole sequence of I-S-I-I-N-I, including the no-load flux density distribution, no-load voltage regulation, output characteristics, loss and efficiency, are comprehensively investigated and compared with that of the II-HEBDCG with conventional pole sequence of N-iron-iron-iron. It is demonstrated that the proposed II-HEBDCG obtains not only better flux (or voltage) regulation capability but also higher output power, and hence, obtains higher efficiency than the conventional one. Finally, a prototype is built and tested to verify the analyses.

Reduced Axial Length Pole-Specific Rotor for Bearingless Induction Machines

The induction machine has proven to be one of the most difficult motor technologies to transform into a bearingless motor due to currents that are induced in the squirrel cage rotor by the suspension field. This paper develops a new rotor for use in a bearingless induction motor to solve this problem. The rotor is described as “pole-specific” because its winding couples to the motor field but not the suspension field. This new structure uses a common end-ring to reduce the rotor’s axial length, solving rotor dynamic challenges present in previous efforts to develop a pole-specific rotor. This paper presents the new rotor concept and leverages traditional cage rotor design theory to develop equivalent circuit models and a theoretical framework that reveals which combinations of poles and slots can be used to implement the new rotor. Experimental results validate the new rotor concept and demonstrate its performance improvement over the classical squirrel cage rotor. A case study is presented of a high performance 50 kW, 30,000 r/min design for an industrial compressor with a modeled efficiency of 96.8%.

Cogging Torque Minimization of PMBLDC Motor for Application in Battery Electric Vehicle

Since the beginning, researchers have focused globally on the automotive industry, which recently yielded a notable increase in the development of electric vehicles. The cogging torque of the motor is the leading cause of acoustic noise and vibration. Therefore, this paper aims to reduce the cogging torque of Brushless DC motors in electric vehicles. The power rating of the two-wheeler battery electric vehicle is determined with kinematic dynamic equations. The choice of material and the combination of pole slots impact the vehicle’s overall performance, particularly in raising the average torque of the motor. Finite element based Ansys Maxwell electromagnetic field simulation software has been used to design and analyze the electric and magnetic field parameters of BLDC motor using several rotor poles embrace factor values. The findings of this study are expected to reduce vibration and noise in electric vehicles with increased average torque.

Trapezium backed dual circularly polarised hepta-band monopole antenna

ABSTRACT This paper presents a hepta-band planar monopole antenna which exhibits circular polarization (CP) at two bands and linear polarization at other five bands. Combination of rectangular slots to form a single E-shaped structure has been introduced in half ground to excite hepta-band operations. Asymmetric trapezoidal parasitic element is also placed under the monopole radiator positioned at upper half ground plane of antenna. Due to asymmetric effect attained by the placement of trapezium, CP is achieved at 4.2 GHz and 10 GHz with 3-dB axial ratio bandwidth of 4.21–4.29 GHz and 9.92–10.01 GHz, respectively. The antenna acquires remaining five resonant modes at 2.4 GHz, 5.4 GHz, 7.2 GHz, 8.86 GHz and 11.8 GHz with 10-dB impedance bandwidth of 90 MHz, 160 MHz, 100 MHz, 200 MHz and 410 MHz, respectively. Sensitive study of the E slot and trapezoidal structured geometry is conducted. The proposed antenna is designed on low cost FR4 (εr = 4.4, tanδ = 0.02). To ensure the practicability, the proposed antenna design is fabricated and measured. A good agreement of simulation and measurement validates the proposed designed. The antenna has potential to cover frequency bands of IEEE802.11, Bluetooth, WLAN, WiMAX, Satellite Communication, Short Range RADARs and Radio band applications.

Planar Dual-Mode Dipole Antenna Formed by Artificial Microstrip Arms Loaded With Multiple H-Slots for Broadband Operation of Vertically Polarized Radiation on UAV Platform

An antenna design is presented for long-distance transmission in the unmanned aerial vehicle (UAV) application. This antenna is in a dipole configuration but with dual-mode operations of both dipole and monopole mechanisms. The monopole behavior becomes apparent when installed on the UAV platform to provide a large ground. To ensure both modes’ good integration to produce a broad bandwidth, the dipole arms are formed by H-slot loaded microstrips to create a slower phase velocity. The separation between adjacent harmonic resonances can be decreased. This antenna has good vertically polarized radiation and maximum gains near the horizontal plane to provide better long-distance connections. Various combinations of H-shaped slots are applied to examine the bandwidth behaviors. The achieved size is 90 mm, roughly 1/3 wavelengths at 1.25 GHz and 1/4 at 0.8 GHz. The bandwidth is larger than 50%. Numerical HFSS full-wave simulation and measurement results are compared to validate the feasibility.

Simple Clock Drift Estimation and Compensation for Packet-Level Index Modulation and Its Implementation in LoRaWAN

Low-power wide-area network (LPWAN), which includes the long-range wide-area network (LoRaWAN) protocol, is an enabling technology that satisfy low power consumption and long-range communication. In many applications of LPWAN, an end node (EN) transmits data at regular intervals. Based on this, we had previously proposed the concept of packet-level index modulation (PLIM) to increase the number of information bits transmitted by one data packet. In PLIM, the generation interval between two consecutive packets is split into multiple time slots. Each EN transmits its packet in a specific combination of time slot and frequency channel, which represents the index, to convey additional information bits. To retrieve additional information, the gateway (GW) detects the time slot in which the data packet is being transmitted. Therefore, accurate synchronization between EN and GW is essential. However, clock drift occurs due to the inexpensive real-time clock oscillator on each EN, which results in timing misalignment between each node and the GW. This article proposes a simple clock drift estimation and compensation method for the PLIM. An experimental measurement is performed to model the clock drift. The numerical results obtained using the clock drift model show that it can accurately detect the time slot index under the influence of clock drift. Furthermore, PLIM is implemented on a commercial LoRaWAN node and GW to demonstrate its practicability.

Reduced-order modelling for approximated analytical calculation of linear permanent magnet machines

In this paper, we propose an order reduction method which can be applied in the approximated analytical model for linear permanent magnet machines (LPMMs). The proposed model takes the periodic boundary condition into account the Poisson and Laplace equations, hence, the analytical solution requires low harmonic orders in each subdomain. The magnetic results show that the proposed model can maintain high accuracy while taking low computational time. 2D finite element computations, as well as measurements, validate the proposed model. The proposed model in this paper can also be further applied in permanent magnet machines with high pole and slot combination, to reduce the computational time.

High capacity chipless RFID tags for biomass tracking application

AbstractThe design of a low-cost, flexible, miniaturized, and a high code density chipless radio-frequency identification (RFID) tag is presented as a solution for tracking the transportation of biomass fuel pellets. The performance of the tag is presented and demonstrates the applicability of the design for different material systems, while maintaining a compact size of 5.06 cm2. The tag consists of nested concentric hexagonal elements and a central spiral resonator suitable for ID encoding. The tag presented demonstrates code density of 3.6-bits/cm2, possesses angular stability up to 60°, and high radar cross section (RCS). The tag performance was also observed for tracking 5 kg of fly-ash biomass. Additionally, as the tag mass mostly consists of FR4, PET, or Taconic TLX-0 with a minute mass of either copper, gold, or silver, the tag can be easily combusted and disposed of during biomass combustion. The novel features of this tag are the combination of hexagonal and spiral shape slots for maximum space utilization thereby achieving high RCS signatures along with high code density. All these properties of the proposed chipless RFID tag provide a pioneering pathway for a real-time biomass tracking application.

Design Considerations of Spoke-Array Brushless Dual-Electrical-Port Dual-Mechanical-Port Machine

Spoke-array brushless dual-electrical-port dual-mechanical-port (SA-DEP-DMP) machine is a good candidate for continuously variable transmission device, because of its high compactness, contactless torque transmission, and decoupled rotors. Due to the specific features, including two independent controllable rotors, two set windings, and complex magnetic field coupling, some unique design considerations of SA-DEP-DMP machine are analyzed in this article. First, there is a little accurate analytical model for DEP-DMP machine. An applicable analytical model is proposed to directly describe the characteristic of air-gap magnetic field and calculate the sizing equation. The key innovation is that the inner air-gap permeance with the slot effect is mapped into the magnetic potential by air-gap mapping model, which simplifies the double air-gap structure into a single air-gap structure. Second, the torques of two rotors are always optimized separately at the same time. Using this design method, the optimal torques of two rotors cannot achieve simultaneously for many parameters. In order to solve this problem, a novel constant torque ratio design method is proposed where two windings electric loading distributions are considered. The influences of key parameters, such as combination of slot and pole, stator split ratio, permanent magnet size, etc., on the torque performances are analyzed based on finite-element analysis. Finally, an SA-DEP-DMP prototype is manufactured.

Integrated-Induction-Based Hybrid Excitation Brushless DC Generator With Consequent-Pole Rotor

This article proposes a novel hybrid excitation brushless dc generator (HEBDCG), in which the main generator part and the induced excitation part share one set of the stator/rotor core (namely integrated-induction-based HEBDCG, i.e., II-HEBDCG). Hence the auxiliary magnetic path and additional airgap do not exist and then high space utilization are achieved. Moreover, the consequent-pole rotor featuring permanent magnet (PM) pole-iron pole-iron pole-iron pole (N-I-I-I) is adopted to utilize the high permeability of iron poles, which is favorable to the flux and voltage regulation. The selection rules of pole and slot combination are given by comprehensively considering the unbalance magnetic force and the relationship of the electrical coupling between the main generator part and the induction excitation part. Then, the principle of flux regulation is revealed by equivalent magnetic circuit, and validated by finite element (FE) analysis. In addition, the influences of key factors including the distribution of induction winding on the performance are discussed, and both the no-load regulation, load characteristics and armature reaction are investigated. Furthermore, the proposed II-HEBDCG is compared to the conventional three-stage brushless dc generator (TSBDCG). It is shown that the proposed II-HEBDCG achieves steady excitation current and flexible regulation of output voltage, and obtains both the higher output power and efficiency than the TSBDCG. Finally, a prototype is manufactured and measured to validate these analyses.

Vibration Performance of an Induction Motor with Respect to a Slot Number

In this paper, two four-pole induction motors having 36 and 24 stator slots are analyzed in terms of vibration performance with respect to the number of rotor slots. Radial and tangential flux densities in air gap are obtained by finite element analysis, and by using the flux densities, radial force density is calculated and separated into its temporal and spatial harmonic orders through Fast Fourier Transform (FFT). The variation of radial force density regarding a slot combination is investigated, and vibration acceleration is estimated by radial force density from FFT. The relation of vibration acceleration with a rotor slot number is scrutinized in terms of temporal and/or spatial harmonic orders. Main and diagonal orders among harmonics are defined, and it is found that vibration performance deteriorates in a rotor slot number creating the 2SUPnd/SUP diagonal orders. In this paper, it is claimed that the existence of the 2SUPnd/SUP diagonal orders is determined by several simple equations, and a slot combination is easily evaluated in terms of vibration performance by the equations obtained from this research.

Investigation of Torque Ripple in an Induction Motor with Respect to Slot Number Combinations

In this study, the harmonic orders of varying magnetic flux density with respect to slot combinations are scrutinized through a spatial and temporal fast Fourier transform. A three-phase four-pole induction motor is selected, and, as its base model, 36 and 28 slots are set up in the stator and rotor, respectively. Eleven models with different numbers of rotor slots were designed to study torque ripples with respect to slot combinations. The correlation between torque ripple and slot harmonics in a stator and rotor is described thoroughly by comparing the tangential and radial magnetic flux densities in the air gap, tangential force density, and harmonic orders in torque. Some models having deteriorated torque ripples have one or more slot harmonic orders in common in the stator and rotor. The other models exhibit the same commonalities, but a small torque ripple occurs because of the high harmonic orders. Models with 24 stator slots are investigated through the same procedure to generalize the relationship between torque ripple and slot harmonics in 36 stator slots.

극 슬롯 조합에 따른 영구자석 표면 부착형 동기전동기의 특성 분석 연구

In this paper, the characteristics of SPMSM (Surface mounted Permanent Magnet Synchronous Motor) applied to EPS(Electric Power Steering) systems were analyzed according to the combination of pole slots. In general, fractional-slot permanent magnet synchronous motors using concentrated windings have advantages such as being more economical than distributed windings, having shorter end windings, and high copper fill factor. However, traditional permanent magnet synchronous motor having the fractional slot has a relatively low winding factor due to the slot pitch and pole pitch ratio. One way to compensate for this is to use a modular motor with fewer slots for a given number of poles. The modular motor is a motor with the number of slots per pole per phase less than 0.5, and the winding factor is larger than that of the traditional motor. Therefore, in this paper, three types of motors: fractional slot modular motors, traditional motors, and integer slot motors, were analyzed and the power characteristics were compared using the FEM(Finite Element method).

Study on the Design of Six-Phase Surface Inset Permanent Magnet Synchronous Generator and Motor Considering the Power Factor and Torque Ripple

In this article, a design of six-phase surface inset permanent magnet synchronous machine (SIPMSM) with the open slots is performed considering the power factor and torque ripple. Because of the reluctance torque component by the <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$q$ </tex-math></inline-formula> -axis core thickness of rotor, an SIPMSM has the high torque density but the large torque ripple. To overcome the large torque ripple, there are various design methods. In case of SIPMSM with the open slots, the tapering of shoe and the notch of stator and rotor cannot apply the tapering that is applied to magnet, but the torque density and power factor decrease because the linkage flux by the permanent magnet reduces. Therefore, the thickness of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$q$ </tex-math></inline-formula> -axis core and tapering magnet has the tradeoff between the performance and the torque ripple. In this article, the characteristic according to the <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$q$ </tex-math></inline-formula> -axis core thickness and tapering magnet is analyzed based on a finite element analysis (FEA). Furthermore, the optimal design is proposed using the performance map based on the tapering of magnet and <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$q$ </tex-math></inline-formula> -axis thickness of core. For the design of a basic model, pole–slot combinations are compared with the torque of SIPMSM according to the current phase angle. Considering the performance, the basic SIPMSM is selected for the optimal design. Based on the basic SIPMSM, the optimal design is performed based on the optimal design parameters considering the power factor and torque ripple.

Vibration Enhancement or Weakening Effect Caused by Permanent Magnet Synchronous Motor Radial and Tangential Force Formed by Tooth Harmonics

This paper investigates the vibration enhancement or weakening effect caused by permanent magnet synchronous motor radial and tangential force formed by tooth harmonics. First, the analytical expressions of an air gap magnetic field are deduced based on a permanent magnet synchronous motor model. Then, the Maxwell stress tensor method is employed to calculate the radial and tangential force density produced by permanent magnet magnetomotive force harmonics and tooth harmonics. Moreover, the spatial phase difference between the minimum non-zero spatial order radial and tangential force waves under loading operation are also obtained. It is followed by stator vibration deformation induced by radial and tangential force waves, and the vibration enhancement or weakening effect is discussed. This study shows that the tangential force wave has a significant influence on the vibration performance similar to the radial force wave. At specific frequencies, superposition of the radial and tangential force waves can intensify the vibration while weakening each other to reduce the vibration at other specific frequencies. Numerical simulation and a vibration measurement experiment of the prototype motor were carried out to confirm the proposed theory, which can guide motor designers in selecting an appropriate pole and slot combination to apply the weakening effect between radial and tangential force waves and improve PMSM vibration performance.

Comparative investigation on multi-band antenna using FR-4 and RT-Duroid

The comparative design and investigation of the multiple resonances are analysed on two substrates using flame retardant FR-4 glass epoxy with the dielectric value of 4.4 and RT-Duroid with the dielectric value of 2.2. To attain the multiple bands for multiple applications with a single antenna is the main aim concluded in this paper. The defected ground structure (DGS) is designed on the ground plane with the combination of slots getting into shaped as E-shape and stacked U-shape. The proposed model has responded to multiple resonances on two substrates. Once the DGS has been inserted, the various parameters are improved such as multiple bands, return loss, gain and bandwidth. The dimensions for FR-4 substrate and RT-Duroid are 30 × 20 × 1.6 mm3 and 30 × 20 × 1.2 mm3, respectively. The main goal of the proposed antenna is to use it for multiple applications. This can be achieved by tuning the defective ground structure. In this proposed antenna, the 50 ohm line feed technique has been utilised for both designs.