Torque Ripple Reduction of Switched Reluctance Motor with Non-Uniform Air-Gap and a Rotor Hole

A switched reluctance motor has a very simple structure which becomes its key signature and leads to various advantages. However, because of its double saliency and switching principle, the motor is also known to have a relatively high torque ripple, and this hinders its use as a high-performance drive. In this paper, a method to reduce torque ripple while maintaining average torque is introduced. Two elements are used to achieve this, namely, a non-uniform air-gap on the rotor-pole face and one hole in each non-uniform region, which maintains the saturation level of the air-gap. This approach preserves the mechanical simplicity of the motor and is easy to implement. Simulations and experiments were performed to verify the effectiveness of the proposed design.

Performances analysis of interior permanent magnet motors having different rotor iron pole shapes

<p><span lang="EN-US">Interior permanent magnet motors (IPMMs) have been increasing in popularity, since the emergence of permanent magnet material with high energy products, i.e. rare earth permanent magnet material. This paper analyses the performances of IPMMs having different rotor iron pole shapes including eccentric, sinusoidal and sinusoidal with 3th order harmonic injected rotor pole arc shapes IPMMs. Cogging torque, static torque, torque ripple, torque-speed and power-speed curves of the mentioned motors have been compared. It must be noted that the mentioned motors have been designed with the same stator, PM shape and the same dimensions, in order to highlight the effect of the rotor pole arc shape on the performance of the such motors. Two-dimensional (2D) finite element analysis (FEA) has been utilized to design and analyze the mentioned machines. It has been found that rotor iron pole shape of the IPM has notably influence on the machine performance, practically on output electromagnetic torque and its ripple. The highest value of average electromagnetic torque as well as torque capability in the constant torque reign is delivered by 3th order harmonic injected rotor pole arc shapes machine, while the lowest torque ripple is obtained by the sinusoidal rotor pole arc machine.</span></p>

INVESTIGATING INFLUENCES OF TAPPED SHOE ROTOR POLES ON ELECTROMAGNETIC TORQUES AND RADIAL FORCES OF SWITCHED RELUCTANCE MOTORS

The shape of rotor poles has a significant influence on the performance of electromagnetic torques and radial forces, because the air-gap flux density is depent on the stator and rotor areas and surfaces. Serveral articles have studied influences of the stator/rotor designs on radial forces and electromagnetic torque waveforms as well. Moreover, the electromangetic characteristics of switched reluctance motors are also defined by tapped-shoe-skewing of the stator and rotor poles with the inner holes. However, the total solution designs of the tapped-shoe rotor with diferent tapped angles have not yet implemented by those papers so far. For that, in this paper, the tapped shoe rotor pole design is proposed by different angles for the high speed switched reluctance motor of 30 kW and 18000 rpm.

Design analysis and fabrication of side-drive electrostatic micromotor by UV-SLIGA

In the present work, a micro-electro-mechanical system (MEMS)-based electrostatic micromotor is designed and fabricated. Finite element analysis is done and various parameters affecting the torque are studied. Maximum torque is achieved at 120° phase angle. The effect of change in voltage, micromotor height and frequency is analysed and discussed. UV-SLIGA, a microfabrication technique, is used for the fabrication of electrostatic micromotor of height 30µm and higher. UV lithography is conducted by both positive AZ P4620 and negative (SU-8 10 and SU-8 2150) photoresists. Copper (Cu) is used as a sacrificial layer to release the rotor (the movable part) of the electrostatic micromotor. Electroformed nickel (Ni) is used for making stator, rotor and axle, whereas chromium (Cr) is used as a seed layer. The micromotor is fabricated with a stator-rotor pole having configuration ratio of 3:2. The gap between the rotor and axle is 20 µm. Wet chemical etching is used to etch the deposited metal layers (Cr, Ni and Cu). Challenges such as the adhesion between the photoresist mould and substrate, cracks, seepage and misalignment are faced during the microfabrication. These challenges are overcome by optimizing the various parameters. The fabrication of electrostatic micromotor is done successfully and the results are discussed in the article.

MOTION CHARACTERIZATION OF A SWITCHED RELUCTANCE ACTUATOR – A SIGNAL DRIVEN APPROACH

In this paper, the researchers have described the development, design and characterization of a Switched Reluctance (SR) actuator, with a rotary motion, having a single-excitation activity. This SR actuator design consisted of a stator and rotor core and was based on the simplest SR actuator model design, with a Stator-to-Rotor pole ratio (S: R) of 6:4. In this design, the winding was coiled at Phase A, which enabled the single step motion characterization based on a single excitation. This SR actuator prototype showed a compact size, with a 36 mm stack length and a 60 mm outer diameter. This feature allowed small machine applications like the precision robotic machining, but required a low production cost, as it lacked a permanent magnet. On the other hand, the SR actuator consisted of highly non-linear characteristics and showed uncontrolled motion behavior. While achieving a very precise motion, it is important to suppress the non-linear characteristics of an actuator. Hence, the researchers designed the linearizer unit based on its characterization at Position 0°, which was related to the excitation current and the rotary angles for the various initial rotor positions. This initial position was chosen as it reflected the characteristics which indicated the self-starting characteristics. Thereafter, the researchers experimentally investigated the appropriate driving signal for this SR actuator as the normal step input signal showed a lower precision motion because of the discharging effect-related issues.

Design and Analysis of the 45kW-Class Magnetic Geared Permanent Magnet Synchronous Motor for Traction of Tram Vehicles

The magnetic geared permanent magnet synchronous motor (MG-PMSM) is a PMSM that has two rotors with different rotation speeds and includes the function of magnetic gear. The design studies of the 45kW-class MG-PMSM are conducted for the application of the driving system for a tram. In this research, first, to derive the detailed model of the 45kW-class MG-PMSM for the tram, the analysis of the characteristics according to the stator winding method was performed. After selecting the winding method that can reduce the size of the MG-PMSM, two design topologies were applied to determine the number of stator poles, the number of outer rotor pole pieces, and the number of inner rotor poles of the MG-PMSM. A 45kW-class MG-PMSM detailed model was derived by applying a design topology that can minimize the size of the MG-PMSM, and it was confirmed that the required performance is satisfied through electromagnetic characteristics analysis. In addition, the 4.5kW-class small-scaled MG-PMSM prototype with concentrated winding was manufactured to verify the validity of the analytical model, and performance verification was performed.

Electromagnetic Torque Analysis of SRM 12/8 by Rotor/Stator Pole Angle

This paper presents the harmonic torque reduction by the different rotor pole angles of a three-phase 12/8 switched reluctance motor via an analytical model and simulation method. Improving torque performance by stator and rotor angles was applied for three-phase switched reluctance motor at stator pole/rotor pole ratios of 6/4, 8/12, 18/12, and 24/18. The average torque and the torque ripple effect by stator and rotor pole embrace have been recently studied in many projects. Due to the fact that leakage flux, flux density, and inductance are affected by the stator and rotor pole angles non-linear and linear leakage flux curves occur. Many stator and rotor pole angle combinations for the three-phase switched reluctance motor have already been done via a finite element method. In this paper, turn-on and turn-off angles will be figured based on stator and rotor pole embraces.