Turn-on Angle Research Articles

Improved Efficiency Optimization Control of SRM Based on Redefined Optimal Turn-On Angle and Its Corresponding Analytical Formula

Improved Efficiency Optimization Control of SRM Based on Redefined Optimal Turn-On Angle and Its Corresponding Analytical Formula

A novel direct instantaneous torque control strategy in permanent magnet-assisted switched reluctance motor based on optimization of conduction angle

A novel direct instantaneous torque control (DITC) strategy based on optimized conduction angle is proposed with the aim of reducing the torque ripple of permanent magnet-assisted switched reluctance motor (PMa-SRM) during the two-phase exchange (TpE) region in this paper. Firstly, according to the inductance characteristics, the TpE region is subdivided into TpE I and TpE II region where the turn-off angle is acted as the region separation point, and the corresponding torque hysteresis strategies are formulated in different regions. Secondly, K-fold extreme learning machine (ELM) method is used to optimize the turn-on angle in order that the current of incoming phase can quickly increase to maintain torque balance. In order to make full use of the ability of torque generation of two adjacent phases, the position where the torque of adjacent phases is equal is used as the turn-off angle of incoming phase. Finally, a 6/20 PMa-SRM prototype is simulated and verified. Compared with the conventional DITC strategy, the novel strategy not only diminish torque ripple and negative torque under different operating conditions, but also expands the operating range of the motor and improves the motor efficiency.

Comprehensive Performance Improvement of SRG by Turn-ON Angle Optimization Using Linear Normalized Model

Comprehensive Performance Improvement of SRG by Turn-ON Angle Optimization Using Linear Normalized Model

A novel direct torque control method for switched reluctance motors based on optimal turn-on angle

A novel direct torque control method for switched reluctance motors based on optimal turn-on angle

An Improved DITC Control Method Based on Turn-On Angle Optimization

An Improved DITC Control Method Based on Turn-On Angle Optimization

Efficient Multi-Hop Wireless Power Transfer for the Indoor Environment.

With the rapid development of the Internet of Things (IoT) and wireless sensor networks (WSN), the modern world requires advanced solutions for the wireless powering of low-power autonomous devices. The present study addresses the wireless power transfer (WPT) efficiency problem by exploiting a multi-hop concept-based technique to increase the received power at the end sensor node (ESN). The current work adopts efficient multi-hop technology from the communications field to examine its impact on WPT performance. The investigation involves power transfer modeling and experimental measurements in a sub-GHz frequency range, chosen for being capable of providing a greater distance to transmit power. The paper proposes a multi-hop (MH) WPT concept based on signal amplification and demonstrates the fabricated multi-hop node (MHN) prototype. The experimental verification of the MHN is performed in the laboratory environment. The present paper examines two WPT scenarios: line-of-sight (LoS) and non-line-of-sight (NLoS). The turn-on angle of 90 degrees on MHN is used for the NLoS case. The received power and RF-DC converted voltage on the ESN are measured for all investigated scenarios. Moreover, the paper proposes an efficient simulation approach for the performance evaluation of MH WPT technology, providing an opportunity to analyze and optimize wireless sensor nodes' spatial distribution to increase the received power.

Multi-Objective Control Strategy for Switched Reluctance Generators in Small-Scale Wind Power Generations

Switched reluctance generators (SRGs) are widely used in wind power generation. However, due to the natural tendency of SRG, there are always nonnegligible conflicts to achieve high efficiency and low output voltage ripple at the same time. This creates difficulties for the high-performance of SRG. Thus, a multi-objective optimization control strategy is proposed in this paper to improve the static performance of SRG. The proposed control strategy contains following steps. First, in order to gain the maximum output power range at different rotor speeds, the turn-off angle is optimized off-line by simulated annealing algorithm (SAA). The optimized results are fitted as a function of rotor speed for on-line regulating; then, a closed-loop controller is built, and the reference current is regulated according to the difference between actual output power and required output power. Second, a multi-objective function is constructed as the evaluation result of SRG performance, which takes system efficiency, output voltage ripple and power converter loss into consideration. In the end, the turn-on angle is tuned by SAA according to the real-time multi-objective evaluation result. The proposed control strategy can be flexibly applied to SRGs with different structures and avoids the disadvantage of single-objective optimization. The simulation and experiments results show that the overall performance of SRG is improved.

An Online Torque Sharing Function Method Involving Current Dynamics for Switched Reluctance Motor Drives

This article proposes an online torque sharing function (TSF) method for torque ripple reduction in switched reluctance machines (SRMs). The proposed TSF takes the current dynamics and induced electromotive force (EMF) into account by establishing a new online current profile generation technique. First, a primary phase current reference derived from the torque reference is applied to the SRM. Then, the decaying phase current after the turn-off angle is sampled and it is used to update the current reference. A new online optimization strategy is performed to shape the current reference during the operation of the machine. Due to the proposed current profile generation technique, the optimization process is decoupled to independently minimize the torque ripple by optimizing the turn-on angle and minimizing copper losses by optimizing the turn-off angle. Compared to the conventional TSFs and existing optimization-based TSFs, the proposed TSF achieves accurate torque control, improved torque–speed capability, reduced torque ripple, and better current tracking performance. Simulations and experiments are performed on a three-phase 12/8 SRM under various operating conditions to validate the proposed online TSF method.

Automatic and real time phase advancing in BLDC motor by employing an electronic governor for a desired speed-torque/angle profile

When the BLDC motors speed increases, the shape of the current waveform changes in such a way that limits the production of motoring torque and increases torque ripple. At high speeds, the phase current can't reach the desired value due to the self EMF of the motor. Therefore, the torque falls off and the amount of torque ripple increases. To obviate this problem, the phase turn-on angle is advanced in such a way that the phase commutation begins sooner. Since the BLDC drive is a variable speed motor then, the amount of advancing for the turn-on angle should be accomplished automatically according to the speed of the motor. In this respect, this paper introduces an automatic and real-time electronic governor using a microcontroller to achieve this task for a desired speed-torque/advancement angle profile, which is considered to be linear in this study. A linear analysis of the current waveform for the motor under different advancements of the turn-on angle has been performed and the plots are shown. Finally, the experimental results of employing the governor BLDC drive are presented.

Improved DITC strategy of switched reluctance motor based on adaptive turn-on angle TSF

Aiming at the problem of large torque ripple and low efficiency of traditional direct instantaneous torque control (DITC) of switched reluctance motor (SRM), an improved DITC method based on adaptive turn-on angle torque sharing function (TSF) is proposed. This method not only introduces TSF, but also divides a working cycle into six sectors, and gives the corresponding candidate voltage states of different sectors. In addition, the adaptive turn-on angle function is designed, so that the TSF curve and the sector position of DITC can be adjusted adaptively according to the changes of speed and load torque, so as to suppress torque ripple and improve efficiency. Finally, in order to prove the correctness of the proposed method, the traditional DITC and improved method are simulated and compared. The results confirmed that the improved method avoids the negative torque of the traditional DITC method at high speed, limits the torque ripple and improves the operation efficiency of the drive system.

Speed Control of Switched Reluctance Motor Based on Regulation Region of Switching Angle

This paper studies the speed control strategy of a switched reluctance motor based on angle-position control (APC). The switched reluctance motor has three control parameters: turn-on angle, turn-off angle and voltage PWM duty cycle. This paper studies the function of the three parameters and designs the control algorithms of the parameters, respectively, which can reduce the coupling degree, simplify the control process, and realize the optimal control of the switched reluctance motor. By studying the nonlinear characteristics of the switched reluctance motor, the optimal current waveform in the effective working range of the inductor is obtained, and then a control strategy of the turn-on angle is designed to realize the ideal winding current waveform. According to the torque characteristics of the motor, taking the coincidence of the freewheeling zero point and the position angle at the end of the maximum inductance interval as the control target, a control strategy for the turn-off angle that makes full use of the effective inductance working interval is proposed, which improves the efficiency of the system. For the nonlinear and time-variant switched reluctance motor running process, a data-driven model-free adaptive control algorithm is introduced, and a switched reluctance motor speed control algorithm based on voltage PWM duty cycle is designed. The main contribution of this paper is to propose a control strategy that is generally applicable to switched reluctance motors, which does not depend on the precise mathematical model of the motor. The control algorithms are designed separately for the three control parameters according to the characteristics of the motor, which reduces the degree of coupling among them. A switched reluctance motor drive system based on angle-position control is designed. This strategy is especially suitable for driving the load with sudden large torque pulsation.

Sensorless Control With Fault-Tolerant Ability for Switched Reluctance Motors

This paper presents a new sensorless control strategy with the fault-tolerant ability for switched reluctance motors (SRMs). Nowadays, many rotor position detection methods are utilized, but most of them increase the system cost due to the additional hardware or complex calculations. To address this problem, various methods of using phase inductance to estimate the rotor position and speed have been proposed. However, the traditional inductance detection method will cause signal distortion due to the presence of interference signals and the unbalanced phase inductance. In particular, the turn-ON angle is advanced. To further improve the stability of the control system, the interference signals are eliminated via establishing the reference time of the inductance characteristic point and the error band in this work. When the position signal disappears, the inductance characteristic points of adjacent phases will be adopted for signal compensation to realize fault-tolerant control. Finally, an SRM drive system is used to verify the effectiveness of the proposed control strategy.

Research on Influence of Switching Angle on the Vibration of Switched Reluctance Motor

Switched Reluctance Motors (SRMs) have emerged as a viable competitor to other established electrical machines. Although SRMs have many advantages, such as a rare earth free nature, simple structure, high fault tolerance capability and low cost, vibration problems due to radial force variations is still a major issue faced by SRMs. Hence, aimed at the problem of vibration suppression for SRMs, this paper proposes a method that focuses on the influence of the change of the turn-on angle and turn-off angle on the vibration of the SRM under the switching angle control (SAC) strategy. Firstly, the influence of the turn-on and turn-off angles on the harmonic components of the current is analyzed in detail. Then, the vibration caused by the frequency of the harmonic components of the current and the natural frequency of the motor is mainly studied. The results show that the harmonic order affecting vibration is related to the rotational speed, and by analyzing the value of this harmonic order, the variation law of vibration with the switching angle can be obtained. When the turn-off angle is constant, the amplitudes of the current harmonic component and vibration first decrease and then increase with the increase of the turn-on angle. Additionally, when the turn-on angle is constant, the current harmonic and vibration show the tendency of periodic oscillation with the variation of the turn-off angle, and the oscillation period is related to the harmonic order. The combination of switching angles that minimizes the certain current harmonic component also minimizes vibration. The effectiveness of the variation law was verified on a 12/8 poles and 1.5 KW SRM drive system test bench, which provide a new perspective on vibration suppression of SRMs.

Torque Ripple Control Strategy of Switched Reluctance Motor Based on BP Neural Network

Switched reluctance motor (SRM) has many advantages, but when the motor is running, the fixed turn-on angle will cause the torque ripple of the motor at different speeds and loads. Therefore, an torque ripple control strategy of switched reluctance motor based on BP neural network is proposed. Firstly, the nonlinear relationship among speed, load torque and opening angle is established by using the fitting generalization ability of BP neural network. In this step, the optimal angle data under the minimum pulsation needs to be obtained by simulation. After collecting data, select and classify the data, and then train and improve the neural network, That nonlinear relationship is introduced into the motor control strategy, so that the motor can automatically adjust its opening angle according to different rotational speeds and load torques and achieve the purpose of reducing torque ripple under different working conditions. Finally, the motor simulation model is built in Matlab/Simulink, and the results are analyzed. This control strategy can control and reduce torque ripple.

Performance improvement based on adaptive commutation strategy for switched reluctance motors using direct torque control

This research presents an improved direct instantaneous torque controller (DITC) for switched reluctance motors (SRMs). It incorporates a novel adaptive real-time commutation mechanism. The proposed method can effectively enhance the torque profile and efficiency of the machine by proper real-time adjustment of both the turn-on and the turn-off angles. First, an initial value of the turn-on angle is selected to achieve the highest torque generation capability. Then, with a real-time adjustment around the pre-selected initial angle, the instantaneous torque error can be further compensated. Hence, the torque ripple is minimized.Regarding the turn-off angle, an initial value is selected to satisfy the minimum required conduction angle of SRM. Then, this value is continuously adjusted at each electrical cycle by utilizing a phase current detector to force the outgoing phase current to decay to a less effective value before the negative slope of the inductance profile. Therefore, this prevents serious negative torque generation. The proposed strategy fully utilizes the torque generation capability of the motor with a minimized torque ripple, besides the phase currents, are generated in optimal conduction range to enhance the motor efficiency. The simulations and experiments have been carried out on a 3-phase 750 W 12/8 SRM to validate the proposed method's feasibility and effectiveness.

ОЦЕНКА УСТОЙЧИВОСТИ СИНХРОННЫХ ДВИГАТЕЛЕЙ В ПЛОСКОСТИ ДВУХ УГЛОВ

Relevance The main technological installations of the oil and gas industry require power supply of the first category and are fed from two independent sources. Possible short-term interruptions of power supply of such installations by their duration should not lead to a violation of the stability of electric motors and disruption of technological processes. The problem of stability at enterprises equipped with automatic standby switching devices with self-starting of synchronous motors after a short interruption of power supply is especially relevant. Therefore, the assessment of conditions for preserving the dynamic stability of synchronous motors after a short interruption of power supply is an urgent task. Aim of research Based on the method of areas, develop a method for assessing the dynamic stability of synchronous motors in the plane of two parameters. Methods The article uses dynamic stability areas in the plane of two angles to assess the dynamic stability of synchronous motors: the load angle of the synchronous motor in the pre-emergency mode δ0 and the inclusion angle δвкл between the mains voltage vectors and the residual voltage on the section that lost power, in the emergency mode. Results The dynamic stability area in the plane of two angles is plotted: the load angle δ0 and the turn-on angle δвкл. The boundary lines of dynamic stability area are plotted for the range of values of load angles, in which the static stability of the synchronous motor in the pre-emergency mode is preserved. On the example of synchronous motor of STD-2500 type, the definition of the dynamic stability area in the plane of parameters under study is shown. It is shown that the region of dynamic stability in the plane of two angles can be transformed into the dynamic stability area of other investigated parameters.

Numerical Investigation on Vibration Performance of an Improved Switched Reluctance Machine with Double Auxiliary Slots

Considerable vibration and acoustic noise limit the further application of Switched Reluctance Machine (SRM) due to its structural characteristics and working principle. An improved SRM model with double auxiliary slots (DAS) was proposed, in which the direction of the magnetic line of force was adjusted, and the radial magnetic density in the air gap was reduced by changing the local tooth profiles of the stator and the rotor. The effects of initial rotor position and turn-on angle and turn-off angle on radial Electromagnetic Force (EMF) and maximum torque were investigated. The results indicate the radial EMF and torque increase significantly with the advancement of the turn-on angle or the delay of the turn-off angle. In the orthogonal experimental design, initial rotor position, turn-on angle, and turn-off angle were taken as the factors, and the optimal set of parameters that minimized radial EMF was determined according to a greater output torque. In contrast to conventional SRM, the radial EMF of the SRM with DAS significantly reduces when the optimal set is applied.

Comparative Evaluation for an Improved Direct Instantaneous Torque Control Strategy of Switched Reluctance Motor Drives for Electric Vehicles

Due to the expected increase in the electric vehicles (EVs) sales and hence the increase of the price of rare-earth permanent magnets, the switched reluctance motors (SRMs) are gaining increasing research interest currently and in the future. The SRMs offer numerous advantages regarding their structure and converter topologies. However, they suffer from the high torque ripple and complex control algorithms. This paper presents an improved direct instantaneous torque control (DITC) strategy of SRMs for EVs. The improved DITC can fulfill the vehicle requirements. It involves a simple online torque estimator and a torque error compensator. The turn-on angle is defined analytically to achieve wide speed operation and maximum torque per ampere (MTPA) production. Moreover, the turn-off angles are optimized for minimum torque ripples and the highest efficiency. In addition, this paper provides a detailed comparison between the proposed DITC and the most applicable torque control techniques of SRMs for EVs, including indirect instantaneous torque control (IITC), using torque sharing function (TSF) strategy and average torque control (ATC). The results show the superior performance of the proposed DITC because it has the lowest torque ripples, the highest torque tor current ratio, and the best efficiency over the low and medium speed ranges. Moreover, the comparison shows the advantages of each control technique over the range of speed control. It provides a very clear overview to develop a universal control technique of SRM for EVs by merging two or more control techniques.

An improved indirect instantaneous torque control strategy of switched reluctance motor drives for light electric vehicles

The switched reluctance motors (SRMs) are powerful alternatives for electric vehicles (EVs). However, the high torque ripple is the main obstacle for their acceptance in high-performance applications. This paper introduces an improved indirect instantaneous torque control (IITC) strategy of SRMs for EVs. It aims to achieve the vehicle requirements including maximum torque per ampere (MTPA), minimum torque ripple, high efficiency, and extended speed range. First, a simple analytical formulation that determines the most efficient turn-on angle for torque production is developed. Second, A modified torque sharing function (TSF) is introduced to compensate for torque tracking errors. To accurately represent the SRM, its magnetic characteristics are calculated using finite element method (FEM). They are employed to build machine model and implement the required transformations. Finally, the particle swarm optimization (PSO) algorithm is adopted to determine the best control parameters for the conventional IITC. This is done basically for comparison and verification purposes. The results show the feasibility and effectiveness of the proposed control over extended speed range.

Optimal control strategy for excitation parameters of SRGs

To solve the inherent contradiction between convergence speed and optimization accuracy in the traditional optimal control strategy for the excitation parameters of SRGs, a novel optimal control strategy for the excitation parameters is proposed. In this strategy, the turn-off angle is fixed at its optimal value and kept constant, and the turn-on angle is optimized through two steps. In the first step, the optimal searching region of the turn-on angle is calculated by a fitting formula. Then in the second step, the golden section algorithm is used to optimize the turn-on angle. Meanwhile, the phase current amplitude is used as the degree of freedom necessary to regulate the generation power. Experimental results indicate that the novel optimal control strategy for excitation parameters can effectively improve convergence speed and efficiency of SRGs.