High Speed Switched Reluctance Machine Research Articles

High-Switching-Frequency SiC Power Converter for High-Speed Switched Reluctance Machine

This article reports design and testing of silicon carbide) devices-based three-phase asymmetric H-bridge converter capable of switching at 50 kHz and intended to drive high-speed switched reluctance machine. Electromagnetic designs of a 7.5-kW, 30 000-r/min and a 20-kW, 50 000-r/min Switched reluctance machine are presented. The 30 000-r/min machine is fabricated and characterized. A machine model is obtained from the measured characteristics. Based on the machine model, as well as drive operating variables and device data-sheet parameters, two methods are proposed for evaluating the losses in the power devices. The first method relies on machine model to obtain machine current and converter duty ratio, and thereby estimate the device losses. A second simplified method provides closed-form expressions for device losses. The proposed analytical expressions relate the machine characteristics such as inductance and saturation current with converter losses. The estimated loss is further used to predict device junction temperature. The power converter and device ratings are chosen so that the converter is suitable for both machines. The capacitor selection and sizing are discussed. Further, the power converter architecture and other subsystems of the converter are described. Test results are presented for the asymmetric H-bridge converter at 800 V dc bus voltage, 50 A of load current, and 50 kHz of switching frequency. Thermal image is presented for validation of estimated heat-sink temperature. The predicted heat-sink temperature is found to agree well with the measured temperature. The power converter is used to operate the 30 000-r/min machine at various speeds.

Acoustic Modeling and Prediction of Ultrahigh-Speed Switched Reluctance Machines Based on Multiphysics Finite Element Analysis

High-speed switched reluctance machines (SRMs) have been a timely topic recently. However, for ultrahigh-speed SRMs over 100,000 rpm, the acoustic noise is a significant issue in many applications such as high speed spindles, compressors/ turbochargers, flywheels, and etc. In this article, a multiphysics acoustic modeling of ultrahigh-speed SRMs is presented based on finite element analysis (FEA). First, a three-dimensional electromagnetic FEA is conducted to calculate the radial force on the stator teeth. Then, a modal analysis and a harmonic response analysis are shown in the frequency domain to estimate the natural frequencies and vibration of the whole motor. An acoustic response analysis is done to estimate the sound pressure level (SPL) using the superposition of the surface vibration. To verify the model, experiments are done to measure and compare the natural frequencies and the SPL of a 4/2 ultrahigh-speed SRM at 100,000 rpm. The results show that the SPL of the motor is as high as 115 dB at 10 mm away from the motor, which matches the simulation result (113 dB) well. The impact of the bearing is proven to be negligible compared with the noise generated by the radial force. Finally, a parametric study example of using the proposed model to guide the design of SRMs has been conducted. It is shown that “hot dog” shaped motors have less noise than “pancake” shaped motors under the same motor volume, speed, and power.

Iron loss and start‐up ability of a 6/2 switched reluctance machine with different magnetic polarity of windings

This study presents an investigation on iron loss and start-up ability of a 1.5 kW output power with rated speed 5850 r/min 6/2 switched reluctance machine (SRM), which is used as a prime motor to directly drive centrifugal blower. Two winding connection types of the SRM are investigated, including the symmetrical magnetic topology (SyMT) and asymmetrical magnetic topology (ASyMT). The two types are proposed to settle poor self-start ability of the 6/2 SRM and high iron loss density of high-speed SRM. According to the simulation results, the SyMT has merit of self-start ability, i.e. no risk of start-up failure, whereas the ASyMT has advantage of low iron loss, i.e. low iron loss density on stator and rotor. Prototypes are manufactured to confirm and verify the predicted results and the test results prove the correctness of the analyses.

Optimal segmented rotor design for the embedded electrical machine for the more electric aircraft

This study presents the design and analysis of the segmented rotor design for an electrical machine embedded onto the more electric aircraft gas turbine engine shaft. The high-speed operational environment imposes high stress levels due to centrifugal forces; thus, the feasibility of this segmented rotor topology for such application is explored and a suitable design is proposed to overcome mechanical stresses. Finite element structural analysis was performed to compare the mechanical behaviour of a different rotor segment fixing structure and the proposed design. Also, electromagnetic analysis is carried out on a high-speed switched reluctance machine to study the impact of a new design on machine electromagnetic performance.

Direct Position Control for Ultrahigh-Speed Switched-Reluctance Machines Based on Low-Cost Nonintrusive Reflective Sensors

High-speed switched-reluctance machines (SRMs) are gaining popularity in both academia and industrial communities. One of the reasons that limit the maximum speed of SRMs is the speed limit of commercial rotary encoders due to mechanical considerations. In this paper, a novel direct position control for ultrahigh-speed SRMs is proposed based on nonintrusive reflective sensors. It uses reflective optical sensors to detect the relative position between the rotor and the stator so as to control the on and off states of the switches directly through the analog output trigger signals generated by the optical sensors. In order to generate the maximum output torque, the switching- on and switching- off angles are optimized based on the equivalent Simulink model with the torque- and flux-linkage characteristics obtained from a corresponding finite-element analysis of a high-speed SRM. Finally, the proposed method is validated by experiments with a 500-W 4/2 SRM running up to 100 000 r/min. The proposed control system has many advantages such as low cost and virtually no speed limit, which makes it suitable for ultrahigh-speed applications.

Experimental Validation of a Thermal Model for High-Speed Switched Reluctance Machines for Traction Applications

This paper presents the experimental validation of a novel cooling concept applied to a high-speed switched reluctance machine topology for traction applications. By circulating the coolant between the coils and the stator poles, the winding and the stator iron are virtually thermally decoupled. A number of test motorettes are used to demonstrate the potential of the cooling concept at current density values up to 27 A/mm2 continuously. The measurements are also used to validate a thermal model of the machine, and further improvements of both the model and the experimental setup are proposed.

High-power density switched reluctance machine development for high-speed spindle applications

In this study, a high-speed switched reluctance machine (HS-SRM) with cobalt-iron lamination material is proposed for spindle motors, which are used in computer numerical control machines. Wide torque-speed range, high power density, high efficiency, and low cost are the crucial issues in spindle applications. Three types of electric machine candidates, the permanent magnet synchronous machine (PMSM), induction machine (IM), and switched reluctance machine (SRM), are compared with their outstanding features. The SRM spindle motor will offer a more robust, reliable, compact, and cost-effective solution compared to the IM or PMSM spindle applications. Moreover, advancement on cobalt-iron laminations gives a chance to the SRM for competing with the PMSM and IM in terms of power density and efficiency. In this study, a high-speed SRM is designed, optimized, and analyzed. Its performance metrics are obtained based on torque-speed range and efficiency over a wide speed range. The proposed SRM is compared with existing industrial products in terms of power densities. Then the design is verified via experimental study. The results show that the HS-SRM with cobalt-iron lamination material offers ultimate power density and efficiency in wide operating conditions.

High-speed switched reluctance machine: natural frequency calculation and acoustic noise prediction

In this study, an analytical model is proposed for natural frequency calculation and acoustic noise prediction for high speed switched reluctance machines. The developed natural frequency model results are compared with the mechanical finite element analysis results in terms of 6 different mode shapes that cause the majority of the acoustic noise in switched reluctance machines. The results show that the analytical results are consistent with the numerical method results with minimum 90% matching. Based on the natural frequency calculation model, a new acoustic noise prediction method is developed that only needs a radial force waveform as an input emerging on stator pole surfaces. The comparison of the developed and the numerical results clearly indicates that the acoustic noise level of the switched reluctance machine can be effectively found during the design process without using time-consuming numerical methods.

Loss analysis of high speed switched reluctance machine with integrated simulation methods

Loss analysis of high speed switched reluctance machine with integrated simulation methods

손실 패턴에 따른 고속 스위치드 릴럭턴스 전동기의 SMC 분말을 이용한 효율 개선

손실 패턴에 따른 고속 스위치드 릴럭턴스 전동기의 SMC 분말을 이용한 효율 개선

Acoustic Noise Analysis of a High-Speed High-Power Switched Reluctance Machine: Frame Effects

This paper examines the effect of frame on the acoustic noise and vibration of a high-speed and high-power switched reluctance machine (SRM). Five types of frame/ribs are investigated, where different frame thicknesses, types of cooling ribs, and frame shapes have been analyzed. For this purpose, a 12/8 SRM has been designed at 22 000 r/min and 150 kW and two stages have been applied. In the first stage, a new equivalent stiffness of the frame is utilized in order to estimate the resonant frequencies for different frame shapes. The paper provides a mathematical calculation method and evaluates its effectiveness with finite-element simulations. The results indicate an improvement between 4% and 25% in the estimation natural frequencies. The second stage includes the vibration and acoustic noise analysis using 3-D finite-element method. Considerations for acoustic noise reduction in high-speed SRM using different frame types and cooling ribs are discussed. Particularly, radial and screw-type configurations represent a better solution to decrease the sound pressure level up to 12 dB.

Retracted: Design and control of a high‐speed switched reluctance machine with conical magnetic bearings for aircraft application

The following article published in IET Electric Power Applications, Ding, Wen; Liu, Ling: Lou, Jianyong: 'Design and control of a high-speed switched reluctance machine with conical magnetic bearings for aircraft application', IET IET Electric Power Applications, 2013, Volume 7, Issue 3, doi: 10.1049/iet-epa.2012.0319 has been retracted. Following a rigorous and considered review of this content, this paper has been found to be in violation of the IET’s Policy in Relation to Plagiarism, Infringement of Copyright and Infringement of Moral Rights and Submission to Multiple Publications.

Thermal Modeling of a High-Speed Switched Reluctance Machine with Axial Air-gap Flow for Vacuum Cleaners

Knowing the precise thermal behavior of switched reluctance machines (SRM) is important to increase the power density of such machines. Up to now, literature is lacking about how to model in detail switched reluctance machines at high speed with axial air-gap flow. The aim of this paper is to present a model showing the effects of varied air-gap flow on temperature distribution in vacuum cleaner machines with a power of 1kW and 60.000 rpm.First, a simulation model was set up, illustrating various operating points of the drive. Then the results of this model were verified on a test bench. Hereby, a simulation was found for high-speed switched reluctance machines that ideally reflects the temperature distribution within the machine and also depicts the effects of changing axial air-gap flow. In conclusion, this presented model indicates that even at high speed and with reduced air-gap flow, these switched reluctance machines can be operated within established temperature limits. Ultimately, this model is very good for predicting the thermal behavior of similar switched reluctance machines with air-gap flow.

Detailed Design of a High Speed Switched Reluctance Starter/Generator for More/All Electric Aircraft

The basic concepts and advantages of more/all electric aircraft (M/AEA) are briefly addressed. The combined starter/generator (CS/G) system is introduced as a key technology to enable M/AEA. Some important performance requirements for CS/G system are obtained. Based on these requirements, a high speed switched reluctance machine (SRM) is designed to operate as a starter/generator. The entire design process is mainly divided into two stages: electromagnetic design and thermal design. In electromagnetic design stage, the electromagnetic structure and dimensions of the machine and the number of phase winding turns per pole are obtained; the topology and main technical details of the converter are briefly introduced as well. In thermal design stage, a liquid-cooling system is designed based on the thermal analysis of the machine. In the end, the performances of the designed SRM are basically verified by simulation. To get high performances, the exciting angles are optimized in two different operating modes respectively, and the optimized performances in the motoring mode are given as well.

Prediction and measurement of core losses in a high-speed switched-reluctance Machine

We describe a procedure for calculating the core loss in high-speed switched-reluctance machines. The technique calculates core losses within a switched-reluctance machine to a high degree of spatial resolution over a wide range of operating conditions. We confirmed the calculations experimentally, using a loss segregation method, and found good correlation.