Turn-on Angle Research Articles

Design Optimization of a Double-Sided Hybrid Excited Linear Flux Switching PM Motor With Low Force Ripple

This paper describes design techniques for a doublesided hybrid excited linear flux switching permanent magnet motor to achieve low force ripple while satisfying the required average thrust force. In this paper, we employ auxiliary poles fixed to both sides of the mover and determine the switching signal turn-on angle to reduce the force ripple in the initial design. Then, the sensitivity analysis of two split ratios is conducted to provide a feasible search direction for the optimization process. Finally, a finite-element-based optimization is utilized to minimize the force ripple and to satisfy the required average thrust force. Simulation results are validated by experimental measurement.

퍼지 이론과 슬라이딩모드 제어를 이용한 스위치드 릴럭턴스 전동기의 토크리플 저감

This paper presents a torque ripple reduction algorithm for the switched reluctance motor drives using the fuzzy logic and the sliding mode control. A turn-on angle controller based on the fuzzy logic determines the optimal turn-on angle. In addition, a sliding mode torque control (SMTC) methods reduces torque ripples instantaneously in the commutation region. The proposed algorithm does not require complex system models considering nonlinear magnetizing or demagnetizing periods of the phase current. According to the rotor speed and torque, the proposed controller changes the turn-on angle and reference torque instantaneously until the torque ripples are minimized. The simulation and experimental results verify the validity of minimizing the torque ripple performance.

Analysis and Experimental Setup of a Switched Reluctance Generator for Maximum Output Power

Output power of a switched reluctance generator (SRG) in single pulse mode operation depends on control variables which consist of dc bus voltage, shaft speed, and excitation angles (turn-on and turn-off angles).This paper presents a model using equations to express maximum output power in terms of the control variables. The proposed analytical model is applied from a nonlinear magnetization curve that is used to mathematically demonstrate relationship of the control variables and to find the optimal control variables of the SRG for maximum output power. The validity of the analytical model has been confirmed by experimental results

Control Optimization of a Slotted Switched Reluctance Generator for High-torque Applications

This article describes the control optimization of a slotted switched reluctance generator for low-speed applications. The machine is simulated with the finite-element method. The turn-off and turn-on angles are optimized by means of a genetic algorithm to maximize the output power and minimize the torque ripple. First, these two criteria are optimized separately with a mono-objective genetic algorithm, and then a multi-objective Pareto genetic algorithm is used. An analysis of optimized parameters and resulting current waveforms is also performed. Experimental results based on a 6/4 switched reluctance generator are also presented.

Minimization of Torque-Ripple in Switched Reluctance Motors Over Wide Speed Range

Torque pulsation mechanism and highly nonlinear magnetic characterization of switched reluctance motors(SRM) lead to unfavorable torque ripple and limit the variety of applications in industry. In this paper, a modification method proposed for torque ripple minimization of SRM based on conventional torque sharing functions(TSF) to improve maximum speed of torque ripple-free operation considering converter limitations. Due to increasing phase inductance in outgoing phase during the commutation region, reference current tracking can be deteriorated especially when the speed increased. Moreover, phase torque production in incoming phase may not be reached to the reference value near the turn-on angle in which the incremental inductance would be dramatically decreased. Torque error for outgoing phase can cause increasing the resultant motor torque while it would be negative for incoming phase and yields reducing the motor torque. In this paper, a modification method is proposed in which phase torque tracking error for each phase under the commutation added to the other phase so that the resultant torque remained in constant level. This yields to extend constant torque region and reduce peak phase current when the speed increased. Simulation and experimental results for four phase 4 KW, 8/6 SRM validate the effectiveness of the proposed scheme.

The Research of an Energy Recovery with SRM during Backflow Period

Facing the situation that battery life mileage is short and energy efficiency is low, The principle is introduced; control method of energy recovery during the backflow period and of improving the energy recovery efficiency in electronic operation are proposed. On the basis of a 500w switched reluctance motor, the mathematical model of SRM is built. In the model, we use the PWM, APC, and CCC control methods at the same time. The best turn-on angle and the turn-off angle are measured in the light load and heavy load conditions through simulation. The energy efficiency in the heavy load and high speed increases 6 percent; energy efficiency in the heavy load and low speed increases 4.5 percent; energy efficiency in the light load and high speed increases 14.5 percent; energy efficiency in the light load and low speed increases 2 percent. This is instructive to improve the efficiency of energy recovery reduce the cost.

A Research for Angle Optimization of the SRM Used in Electric Actuator of Valves

This paper uses TMS320F28335 DSP and MAX3032S CPLD as the controller of the 6/4 pole switched reluctance motor (SRM), and controls the motor by the method of current chopping control (CCC) in low speed and the method of angle position control (APC) in high speed. About the optimization of turn-on angle and turn-off angle when SRM is controlled by the method of APC, this paper discusses the optimal design of the two parameters by ways of theory research, simulation and experimental testing. The results show optimal switching angle can make speeded-up of the motor better and improve the performance of SRM.

Acceleration Closed-Loop Control on a Switched Reluctance Linear Launcher

In this paper we describe a developed switched reluctance linear launcher system with diagrams and photographs, which consists of a three-phase 6/4 structure simple side-switched reluctance linear motor, a three-phase asymmetric bridge power converter, and a TMS320F28335 DSP digital controller. The acceleration closed-loop control of the mover is proposed and verified for the first time. The acceleration closed-loop control of the mover is implemented by a fuzzy control algorithm. The turn-on angle and the turn-off angle of the main switches in the power converter are fixed, and the triggering signals of the main switches are modulated by the pulse width modulation (PWM) signal. The deviation of the acceleration between the given acceleration and the feedback practical acceleration, and the variation from the deviation of the acceleration are the two input control parameters. The increment of the duty ratio of the PWM signal is the output control parameter. The duty ratio of the PWM signal is regulated based on the fuzzy control algorithm. Flow diagrams of the software, such as the main program, the encoder unit time interrupt subroutine, analog-to-digital converter interrupt subroutine, and the fuzzy control algorithm subroutine are given. The developed prototype is tested experimentally. It is shown that the velocity response of the mover is satisfactory.

Multi-Objective Differential Evolution Based PerformanceOptimisation for Switched Reluctance Motor Drives

The simple structure, low manufacturing cost, rugged behavior, high torque per unit volume, and wide torque-speed range make a switched reluctance motor (SRM) very attractive for industrial applications. However, these advantages are overshadowed by its inherent high torque ripple, acoustic noise, and difficulty to control. The controlled parameters in SRM drives can be selected as the turn-on angle, the turn-off angle, and the current reference. This paper investigates the problem of optimal control parameters considering the maximum average torque, minimum copper losses, and minimum torque ripple as the main objectives in SRM drives. The use of evolutionary algorithms (EAs) to solve problems with multiple objectives has attracted much attention recently. Differential evolution (DE) is an EA that was developed to handle optimization problems over continuous domains. A multiobjective DE (MODE) technique is introduced here to find the optimal firing angles under multiple operating conditions. The simulation results carried out on a 4-phase 8/6 pole SRM show that the proposed MODE can be a reliable alternative for generating optimal control in the multiobjective optimization of SRM drive systems.

A Sensorless Switched Reluctance Drive System Based on the Improved Simplified Flux Method

This paper describes a new rotor position sensorless control method for SRM drives based on an improved simplified flux linkage method. In the traditional simplified flux linkage method, every phases take turns conduction and current chopping control method is used. Every phases take turns conduction means turning on the incoming working phase while turning off the working phase. This conduction mode causes coupling between turn-on and turn-off angles, which goes against optimal efficiency or torque ripple minimization with sensorless speed control. In the improved simplified flux linkage method, turn-off angle is calculated by flux loop, the turn-on angle can be given arbitrarily and has no relations with the turn-off angle, and the current chopping control method is used. The speed and rotor position can be estimated then. Finally, a sensorless SRM speed control system and an experiment platform with DSP are built and validity of this method is confirmed.

Analytical method to optimise turn-on angle and turn-off angle for switched reluctance motor drives

A new analytical method is proposed to produce optimal turn-on and turn-off angles, based on a non-linear inductance model of low-inductance region for switched reluctance motor (SRM). The optimal turn-on angle is derived from the non-linear model and electrical equation of SRM instead of the linear model while optimal turn-off angle is derived from the turn-on angle and flux-linkage. Considering the back electromotive force, the proposed method has more accuracy than the conventional analytical method and improves the efficiencies both at low speed and high speed. Simulation and experimental results demonstrate the validity and effectiveness of the proposed method, which is suited for low- and high-speed conditions both.

Switched Reluctance Generator Controls for Optimal Power Generation and Battery Charging

This paper presents the control strategy for varying the turn-on and turn-off angles of three-phase switched reluctance generators (SRGs) to maximize the efficiency as well as to reduce the dc-link ripple current resulting from the commutation of the phases at high speeds. The behavior of the commutation angles is analyzed first through the offline measurement of dc-link current and voltage, generator speed, and phase currents. The analysis of the collected data has shown that the commutation angles providing the minimum ripple on the dc-link current achieve the maximum generating efficiencies. A novel control technique, developed based on the finding, achieves the desired generating set point with maximum efficiency and minimum ripple on the charging current. The control algorithm actively searches the turn-off angles to reduce the amount of normalized ripple on the dc-link current, which also ensures the generation with the maximum efficiency. The turn-on angle is controlled through a proportional-integral controller to generate a desired power level. The algorithm is implemented successfully on a 1-kW three-phase SRG charging a NiMH battery pack.

Sensorless Control of Switched Reluctance Motor Based on Dynamic Thresholds of Phase Inductance

A new sensorless control scheme for switched reluctance motor drives is presented in this article. This scheme is based on the basic characteristics that the phase inductance changes periodically with the rotor position. First, according to the inductance characteristics, the inductance model can be constructed. Based on the inductance model, the phase inductance at the turn-off angle of the active phase and the turn-on angle of the next phase can be calculated as the two dynamic thresholds. The real inductance is estimated using the terminal measurements of the active phases. By comparing the estimated phase inductance of the active phase with the dynamic thresholds, the drive signals of each phase can be obtained for controlling the switched reluctance motor directly without rotor position information. This sensorless method is quite easy for implementation and possesses good speed-regulating performance. Besides, in order to start the switched reluctance motor from standstill or start those with initial rotor speed conditions without any hesitation, a full-cycle phase inductance subregion method is utilized. Simulation and experimental results are presented and compared for verification.

Impact Analysis of Dwell Angles on Current Shape and Torque in Switched Reluctance Motors

The reduction of torque ripple is the main target in research for designing a variable drive system with switched reluctance motors (SRM) for higher torque density and better efficiency. This ripple is due to the transition of excitation current between the adjacent phases. Precise control of turn-on and turn off angle is required to smooth the torque. In this paper, the effects of selecting the turn-on and turn-off angles are simulated in detail. It is observed that with the extended turn-on and turn off angles, the precise selection of turn-on and turn off angle can alter the shape of the excitation current in the stator coil and its point of overlapping with the adjacent coil. Therefore the transition between different phases can be smoothed out. The impact of this alteration on the excitation current and torque ripple as a function of different parameters of dwell angle is studied in detail in this paper. It is found that a sinusoidal current shape can also be obtained with the proper selection of these parameters. DOI: http://dx.doi.org/10.11591/ijpeds.v2i2.236

Speed Closed-Loop Control for Switched Reluctance Motor with Segmental Rotors Based on Angle Position Regulation

This paper describes the structure and the magnetic circuit of switched reluctance motor with segmental rotors (SSRM), and presents the control strategy of speed closed-loop by regulating the turn-on angle of the main switches in the power converter based on PI algorithm. The turn-off angle is optimized according to different speeds of the motor. The deviation of the rotor speed is the input control parameter of PI controller, and the turn-on angle is the output control parameter. The strategy of current chopping control is used for comparing with angle position control when rotor speed is high. Both the simulation and experimental results show the well transient, steady performance and robustness of SSRM based on the angle position controller.

Switched Reluctance Motor Drive System Model and Simulation Based on ANSYS and SIMULINK

This paper provided a kind of method to analyze the flux of the switched reluctance motor(SRM) at different rotor position and current by ANSYS. Then the derivative of static inductance with rotor position angle was computed by cubic spline interpolating function, on this basis, the non-linear inductance model with the lookup table of Switched reluctance motor drive system(SRD) was established by SIMULINK. The dynamic properties of SRM was studied comprehensively. Through a prototype simulation of three phase 12/8 SRM, analyzing the characteristics of torque and current to establish reasonable control strategy at the different turn-on angle and turn-off angle. Simulation results showed that the SRM model was reasonable and efficacious, a new idea was proposed for design and debugging of the actual motor control system.

Low-cost microprocessor-based alternating current voltage controller using genetic algorithms and neural network

A low-cost, high-performance microprocessor-based pulse width modulated (PWM) AC voltage controller with a novel harmonic reduction technique is proposed. Genetic algorithm is adopted to evaluate the optimal turn-on and turn-off angles in the PWM pattern such that the total current harmonic distortion is minimised. The evolved angles are only optimised at a desired output voltage. In the proposed design, an artificial neural network trained by sets of optimal angles is utilised, making the designed system applicable to all operating points. The simulation and experimental results verify that the proposed technique is a suitable technique, and its performance is comparable to the conventional techniques.

Implementation of the Three-Phase Switched Reluctance Machine System for Motors and Generators

This paper presents two three-phase switched reluctance machine systems. One is the dual motors drive for the electric locomotive traction; the other is the variable-speed generator system for wind power applications. The principles of the switched reluctance machine system operated at four quadrants, the scheme of the symmetrical traction at quadrant I and quadrant III, and the scheme of the symmetrical regenerative braking control at quadrant II and quadrant IV, are given. The transient phase current analysis and the energy analysis of the switched reluctance machine system at the operational state of braking or generating are evaluated, and the rotor position and the peak value of the phase current at three different conditions are given. The closed-loop rotor speed control of the main motor, synchronization of the rotor speed, and balance distribution of loads between the main motor and the subordinate motor have been implemented by the fuzzy logic algorithm. The closed-loop output power control of the switched reluctance wind power generator system implemented by regulating the turn-on angle of the main switches with fuzzy logic algorithm and fixed turn-off angle of the main switches is also presented. The major components of the two prototypes are explained in detail. The experimental results of the dual 7.5-kW three-phase 6/4 structure switched reluctance motors (SRMs) parallel drive system prototype are included. It is shown that the maximum difference in the output torque of the two motors at the same given rotor speeds is within 10.00% and the maximum difference in the practical rotor speed of the two motors is within 5.00%. The tested results of three-phase 12/8 structure switched reluctance variable-speed wind power generator system show that the error of the closed-loop output power control is within 2.2%, while the rotor speed range is close to the ratio of 1:3 with the low rotor speed 405 r/min. The average dc line current of the power converter can be utilized as a feedback signal for the actual output torque of SRM drive or a feedback signal for the actual output power of switched reluctance generator system.

Optimal Control Method of Motoring Operation for SRM Drives in Electric Vehicles

This paper presents three criteria for evaluating the motoring operations of switched reluctance motor (SRM) drives for electric vehicles (EVs). They imply motoring torque, copper loss, and torque ripple, respectively. The effects of the turn-off and turn-on angles on these criteria are investigated under hysteresis current control. To fulfill the best motoring operation, consequently, the multiobjective optimization function is developed by using three weight factors and three groups of base values: the correct balance between the maximum average torque, the maximum average torque per root mean square current, and the maximum torque smoothness factor. The study in this paper shows that the turn-off and the turn-on angles can be optimized to maximize the developed multiobjective function. In addition, the control method for the best motoring operation of SRM drives in EVs is proposed. In this method, two angular controllers are proposed to automatically tune the turn-off and turn-on angles to obtain high motoring torque, low copper loss, and low torque ripple. Simulations and experimental results have demonstrated the proposed optimal control method. Therefore, this paper offers a valuable and feasible approach for implementing the best motoring operation of SRM drives for EVs.

Optimization and Evaluation of Torque-Sharing Functions for Torque Ripple Minimization in Switched Reluctance Motor Drives

Two improved torque-sharing functions for implementing torque ripple minimization (TRM) control are presented in this paper. The proposed torque-sharing functions are dependent on the turn-on angle, overlap angle, and the expected torque. This study shows that for a given torque the turn-on angle and the overlap angle have significant effects upon speed range, maximum speed, copper loss, and efficiency. Hence, genetic algorithm is used to optimize the turn-on angle and the overlap angle at various expected torque demands operating under the proposed TRM control in order to maximize the speed range and minimize the copper loss. Furthermore, four torque-sharing functions are used to derive the optimized results. At the same time, a fast and accurate online approach to compute the optimal turn-on and overlap angles is proposed. Therefore, this paper provides a valuable method to improve the performances of switched reluctance motor drives operating under TRM control.