High Speed Switched Reluctance Motor Research Articles

Dynamic circuit model considering core losses and phase interaction for switched reluctance machines

This study sets forth an equivalent electric circuit (EEC) model including core losses and phase interactions to obtain a more accurate steady and dynamic performance of the high speed switched reluctance motor (SRM) during the design, analysis, and control of the SRM drive system. The magnetic equivalent circuit (MEC) method is used to calculate the flux linkage and torque quickly and relative accurately. Based on the principle of transformation between the MEC and EEC, the EEC model is derived from the MEC model. To enhance the model precision, the dynamic core losses and phase interactions are analysed and added to the EEC model. The relationship between the phase current and virtual current corresponding to different parts is deduced. Then the simulation model of the whole SRM driver systems is established in MATLAB/Simulink to obtain the phase current and virtual current corresponding to a different portion. The experimental and simulated results of the static MEC model and the whole SRM drive system including the EEC model provide the conclusive evidence for validating their practicability.

Development of High-Speed Switched Reluctance Motor for Electric Power Tools

This paper presents design and experimental evaluation of a switched reluctance (SR) motor used for electric power tools. First, characteristics of a previous designed 6/4-pole SR motor is shown and compared to a permanent magnet (PM) motor used in present electric power tools. Next, to further improve characteristics, a 12/8-pole SR motor is designed and evaluated in experiment. It is proved that the performance of the prototype 12/8-pole SR motor is almost comparable or superior to the present PM motor.

Effects Observed in the Characterization of Soft Magnetic Composite for High Frequency, High Flux Density Applications

This paper forms part of a broader study on the design optimization of a high speed switched reluctance motor for automotive traction applications. Due to the high speed operation and resulting high electrical frequency, it is of extreme importance that the different loss components of this motor are accurately calculated. In this study, several effects are observed that influence the accurate measurement of the core loss data used in the calculation of the iron loss in the motor design. It is shown that especially at high frequency and flux density, the loss measurement can be significantly influenced by effects such as temperature, winding AC loss, flux density saturation, and flux waveform shape. The proposed fundamental frequency of the case study motor is 4 kHz, and flux density values of up to 2 T can be obtained under certain load conditions.

Control method of high-speed switched reluctance motor with an asymmetric rotor magnetic circuit

Abstract In the paper, the modified (compared to the classical asymmetric half-bridge) converter for a switched reluctance machine with an asymmetric rotor magnetic circuit was analysed. An analysis for two various structures of switched reluctance motors was conducted. The rotor shaping was used to obtain required start-up torque or/and to obtain less electromagnetic torque ripple. The discussed converter gives a possibility to turn a phase off much later while reduced time of a current flows in a negative slope of inductance. The results of the research in the form of waveforms of currents, voltages and electromagnetic torque were presented. Conclusions were formulated concerning the comparison of the characteristics of SRM supplied by the classic converter and by the one supplied by the analysed converter.

The Design of the Simple Structure-Specified Controller of Magnetic Bearings for the High-Speed SRM

Magnetic bearing system controllers using H <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">∞</sub> algorithms provide excellent interference rejection capability and robustness. However, in the conventional H <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">∞</sub> control design, the order of the controller is much higher than that of the plant, making implementation in practical engineering applications difficult. To solve the problem, based on the requirements of the theory of mixed sensitivity design method, this paper designs a simple structure-specified controller of magnetic bearings for the highspeed magnetic levitated switched reluctance motor (SRM) using backpropagation neural network function approximation characteristics. The proposed controller is of lower order than the traditional H <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">∞</sub> controller, and meets performance of H <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">∞</sub> controller, which is more suitable for practical implementation. By contrast with the traditional mixed sensitivity controller, results of simulations verify that the controller is reasonable. The controller is applied on the high-speed magnetic levitated SRM platform, and experimental results verify that the controller can achieve control of magnetic bearing systems with good disturbance rejection and robustness.

Optimum Design of Rotor for High-Speed Switched Reluctance Motor Using Level Set Method

This paper presents a novel rotor structure optimized by using the level set method (LSM) to improve the static torque characteristics of a two-phase 4/2 high-speed switched reluctance motor. The magnetic equivalent circuit approach is used to analyze the influence factors on the static torque. The inner material boundary contained in the rotor saliency, which will be optimized, is implicitly represented by an embedded level set function. The evolution of the inner material boundaries is driven by the normal velocity derived through sensitivity analysis and adjoint variable computation. Optimal rotor configuration produces the nonuniform distribution of magnetic flux density in the air gap at aligned position, which can make the ratio of maximum and minimum inductances increased. High-permeability material is applied to enhance the mean torque. In order to achieve the optimal static torque, the strategy combining finite-element electromagnetic computation with LSM is conducted to optimize the rotor saliency at different rotor positions. The comparison of the optimized rotor configuration using LSM with that using density-based method suggests that the optimized rotor structure obtained using this presented method is easier to implement.

CONTROL STRATEGY FOR A HIGH SPEED SRM FED FROM A PHOTOVOLTAIC SOURCE

High speed Switched Reluctance Motors (SRMs) have recently been gaining attention as contenders in many variable speed drive applications. This has also been stimulated by recent advances in power electronic technology which enables this drive system for many applications such as high speed water pump and space and military applications. This study presents the design and control of high speed four phases SRM suitable for high speed water pumping and other high speed variable load applications. The dynamic load characteristic and the SRM operation modes have been studied and a novel cascade control strategy is designed and implemented using the MathLap Simulink. The SRM drive system is tested and encouraging results were obtained. The results are of prime importance in the developments of rural and remote areas and also for space and military applications.

Control Strategy for a High Speed SRM Fed from a Photovoltaic Source

High speed Switched Reluctance Motors (SRMs) have recently been gaining attention as contenders in many variable speed drive applications. This has also been stimulated by recent advances in power electronic technology which enables this drive system for many applications such as high speed water pump and space and military applications. This study presents the design and control of high speed four phases SRM suitable for high speed water pumping and other high speed variable load applications. The dynamic load characteristic and the SRM operation modes have been studied and a novel cascade control strategy is designed and implemented using the MathLap Simulink. The SRM drive system is tested and encouraging results were obtained. The results are of prime importance in the developments of rural and remote areas and also for space and military applications.

Design and Operation Characteristics of Four-Two Pole High-Speed SRM for Torque Ripple Reduction

This paper presents the design and operation of a two-phase four-two pole switched reluctance motor (SRM) for a high-speed air blower. The air blower has unidirectional rotation and requires a wide positive torque region without torque dead zone. In order to achieve the requirements, a nonuniform air gap with asymmetric inductance profile is considered. For a flattop torque with a low torque ripple, the nonuniform air gap is also effective. Based on the output torque analysis at the rotor position for the given air gap, the air gap is modified to reduce the torque ripple. The optimized air gap at a given position cannot feel the effect of the air gap at a previous rotor position. Therefore, the output torque cannot fully satisfy the target torque in one optimization process. In order to satisfy the target torque and reduce the torque ripple, the second optimization process is implemented considering the output torque of the initial optimization process. The second target torque is determined by the torque error of the initial output torque and target torque of the first process. From this optimization sequence, the final air gap, as a function of the rotor position, can be determined to satisfy the torque ripple requirement. The proposed high-speed four-two pole SRM is tested to verify the high-efficiency and low-acoustic-noise characteristics.

A SIMPLIFIED SPEED CONTROLLER FOR HIGH SPEED SWITCHED RELUCTANCE MOTORS

This paper presents a simplified speed controller (SSC) for high speed Switched Reluctance Motors (SRM). The controller is designed to overcome difficulties estimating control variables and motor operation over a wide range of speeds. The controller combines the advantages of the simplicity of conventional controllers and the intelligent properties of the fuzzy logic controller. The controller use only two control variables which are calculated via the perturbation of the mechanical equation and pre-defined SRM speed performance. The controller is designed and implemented by computer simulation. The performance of the motor with the controller is assessed using dynamic loads and various types of disturbances. The results illustrate that the controller represent an ultimate solution for the operation of high speed switched reluctance motors.

A Simple Negative Torque Compensation Scheme for a High Speed Switched Reluctance Motor

SRMs(Switched Reluctance Motors) are much interested in high speed applications due to the mechanical robustness, simple structure and high efficiency. In spite of many advantages of SRMs, a higher torque ripple discourages the adoption of SRMs in a high speed application. This paper presents a simple negative torque of tail current compensation scheme using a modified TSF(Torque Sharing Function) for the high speed SRMs. Because of the short commutation in the high speed region, the negative torque from the tail current makes the high torque ripple. In order to reduce and compensate the negative torque from tail current, the proposed control scheme produces an additional compensating torque with a reference torque in the active phase winding. And the compensating value is dependent on the tail current of the inactive phase winding. Furthermore, the switching signals of the outgoing phase are fully turned off to restrict the extended tail current, and the torque error of the outgoing phase is compensated by the incoming phase. The proposed modified TSF control scheme is verified by the computer simulations with 30,000[rpm] high speed 4/2 SRM. The simulation and experimental results show the effectiveness of the proposed control scheme.

Current Control Scheme of High Speed SRM Using Low Resolution Encoder

This paper presents a balanced soft-chopping circuit and a modified PI controller for a high speed 4/2 Switched Reluctance Motor (SRM) with a 16 pulse per revolution encoder. The proposed balanced soft-chopping circuit can supply double the switching frequency in the fixed switching frequency of power devices to reduce current ripple. The modified PI controller uses maximum voltage, back-emf voltage and PI control modes to overcome the over-shoot current due to the time delay effect of current sensing. The maximum voltage mode can supply a fast excitation current with consideration of the hardware time delay. Then the back-emf voltage mode can suppress the current over-shoot with consideration of the feedback signal delay. Finally, the PI control mode can adjust the phase current to a desired value with a fast switching frequency due to the proposed balanced soft-chopping technology.

Windage Loss Reduction of High-Speed SRM Using Rotor Magnetic Saturation

This paper presents a new approach to reduce windage loss of switched reluctance motor (SRM) by changing the rotor shape. To predict the performance of improved SRM rotor, the parametric finite element analyses are needed to get inductance profiles of the proposed rotor shape. The calculated values are compared with the measurement values, in order to evaluate a validity of the proposed method.

A Novel Four-Level Converter and Instantaneous Switching Angle Detector for High Speed SRM Drive

A novel four-level converter and instantaneous switching angle detector for a high speed switched reluctance motor are proposed. Since the excitation time is very short compared to the general speed range of a high speed drive, the excitation current can not be built-up sufficiently. Also, the demagnetization current can be easily extended to the negative torque region. To obtain a fast current buildup and suitable demagnetization, a novel four-level converter is proposed. The proposed converter has an additional charge capacitor and an active power switch compared to a conventional asymmetric converter. The high voltage of the additional capacitor is applied to the phase winding in the fast excitation mode and the phase current is rapidly decreased during the recharging of capacitor in demagnetization mode. In addition, an instantaneous switching angle detector separated by main digital controller is designed for precise switching angle control. During high speed operation, rotor position error increases due to the constant sampling period of digital controller. The proposed instantaneous switching angle detector operates with optical encoders pulse and pre-set switching position regardless of sampling time. So, it determines the precise switching pattern without time delay from sampling time. The proposed high speed control system is verified by computer simulation and experimental results.