Commutation Angles Research Articles

Reduction of Torque Ripple in Switched Reluctance Motor Drives Through Optimum Commutation Angles Control

Reduction of Torque Ripple in Switched Reluctance Motor Drives Through Optimum Commutation Angles Control

Maximum Torque per Ampere Technique for Switched Reluctance Motor Drive

Numerous researchers have investigated switched reluctance motors (SRMs) as a competitor to other electrical motors for usage in electric and hybrid vehicle appliances. SRMs are fault-tolerant and have a broad operating speed range. However, they have numerous drawbacks, such as high nonlinearity in machine models, complex control, and torque ripple. This study aims to improve the SRM drive system to attain maximum torque per ampere in a wide speed range. In the design and control of SRMs, maximizing torque per ampere (MTPA) is a crucial objective. MTPA refers to the strategy of achieving the maximum possible torque output for a given current input (amperes). This is essential for enhancing the efficiency and performance of the motor. The paper focuses on achieving MTPA in an SRM drive system-based commutation angle control. Utilizing a bacterial foraging optimization algorithm (BFOA), the suitable commutation angles at each operation point are determined. The intended technique is straightforward to realize and does not require complex algorithms. Simulation comparisons on an 8/6 SRM are also presented to validate the intended control technique. The results indicate that the MTPA has been enhanced by 6.961% compared to the conventional method.

Fulfillment of Some Important Voltage Harmonic Standards in a FPGA Controlled CHB Multilevel Inverter Utilizing Improved SHM-PAM Technique

In the area of medium voltage and high power multilevel inverter applications, good quality power output can be achieved by minimizing lower-order harmonic components, and the SHM-PAM scheme produces best results in this context. The minimization of selective lower-order harmonics rather than their complete elimination makes it more useful to comply certain grid code standard. This article proposes an improved SHM-PAM scheme for a 3-phase 7-level CHB-MLI utilizing three new half-wave (HW) symmetry waveforms to comply with six well-known grid code standards, namely CIGRE WG 36-05, EN 50160, NRS 048-2, IEC 61000-2-12, IEC 61000-3-6, and ER G5/4. The optimal switching transients and necessary dc-link voltages have been determined for controlling the CHB MLI using the recently reported dragonfly algorithm (DA). The efficacy of the reported scheme is evaluated satisfactorily by simulation study and hardware investigation on a CHB-MLI laboratory prototype. The power loss analysis of the CHB inverter for the proposed schemes is evaluated for the entire power factor range. Additionally, to demonstrate the suggested method's superiority in terms of necessary commutation angles for grid code fulfilment, a comparative study has been carried out with a number of pre-existing modulation-schemes.

A Novel Multi-Criteria Local Latin Hypercube Refinement System for Commutation Angle Improvement in IPMSMs

The commutation angle, γ, of an interior permanent magnet synchronous motor's (IPMSM) vector diagram, plays an important role in compensating the back electromotive force (back-EMF); both under phase current variations and an extended speed range, is required by the application. This commutation angle is defined as the angle between the fundamental of the motor phase current and the fundamental of the back-EMF. It can be utilised to provide a compensating effect in IPMSMs. This is due to the reluctance torque component being dependent on the commutation angle of the phase current even before entering the extended speed range. A real-time maximum torque per current and voltage strategy is demonstrated to find the trajectory and optimum commutation angles, <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">γ</i> , where the level of accuracy depends on the application and available computational speed. A magnet volume reduction using a novel multi-criteria local Latin hypercube refinement (MLHR) sampling system is also presented to improve the optimisation process. The proposed new technique minimises the magnet mass to motor torque density whilst maintaining a similar phase current level. A mapping of <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">γ</i> allows the determination of the optimum angles, as shown in this paper. The 3 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">rd</sup> generation Toyota Prius IPMSM is considered as the reference motor, where the rotor configuration is altered to allow for an individual assessment.

Quantification of Noise Benefits in Torque Control Strategies of SRM Drives

Torque Sharing Function (TSF) based control is a well-established method for the reduction of torque ripple in Switched Reluctance Motor (SRM) drives. There have not been much investigations carried out in the literature on the noise benefits of TSF based control and on the impact of the commutation angles of TSF definition on the acoustic noise in SRM. In this paper, the advantages of TSF based control in noise reduction of SRM are investigated in detail. A new TSF profile, which is characterized by a slower variation of the radial force and hence reduced vibration on the stator, is introduced. Further, the effects of variation of turn-on and overlap angles of TSF definition on the vibration and torque ripple in a closed loop control are analysed in detail, using simulations and experimental methods. Based on the analysis and experimental studies, a new strategy for the selection of turn-on and overlap angles of TSF definition has been developed for achieving reduced acoustic noise, in addition to low torque ripple. Simulation and experimental results are presented to demonstrate the effectiveness of the proposed TSF definition and angle selection strategy.

Analysis and Experimental Validation of Selective Harmonic Elimination in Single-Phase Five-Level Inverter using Particle Swarm Optimization Algorithm

This paper presents the analysis and experimental validation of selective harmonic elimination in single-phase multilevel inverter using one of the most effective optimization algorithms known as particle swarm optimization. The presented inverter is one of the popular emerging topologies composed of a few switches compared to conventional topologies in order to produce a five-level output voltage. The optimization algorithm is applied to find the optimal commutation angles to implement the selective harmonic elimination by solving a system of transcendental non-linear equations. The results of the computational simulations are in good agreement with the theoretical analysis. The method is simple compared with the analytical methods, effective for driving the inverters and inexpensive to apply in real-time using a low-price DSP–Delfino-C2000-TMS320F28379D Chip. The theoretical analysis is verified by simulation using MATLAB/ Simulink environment and an experimental prototype composed of efficient electronic components, respectively. The obtained results of simulations and experiments confirm the effectiveness of the presented modulation method.

Investigation on Torque Sharing Function for Torque Ripple Minimization of Switched Reluctance Motor: A Flower Pollination Algorithm Based Approach

ABSTRACT Switched reluctance motor (SRM) drive has outstanding features like robust construction, double saliency, fault tolerance capability, and heat withstanding capability. Despite these, torque ripple is an intrinsic characteristic of SRM because of double salient geometry, air gap length, and switching sequence of motor phase currents, making it unsuitable for slick torque and high dynamic performances applications. This paper discusses the novel Torque Sharing Function (TSF) implementation and the flower pollination algorithm-based intelligent controller to minimize the torque ripples in Switched Reluctance Motor (SRM). TSF values depend on commutation angles during turn on, turn off, and overlapping angles. The proposed TSF and flower pollination algorithm evaluates the performance parameters using the machine model and controls the torque ripples for a wide range of speeds. Additionally, optimal results are obtained using three TSFs functions with valuable guidance provided for TSF selection. The proposed TSF with flower pollination algorithm-based intelligent controller finds its suitability for online evaluation of optimal turn on, turn off, and overlapping angles. The performance of the proposed method has effectively reduced the torque ripple in SRM than the Differential Evolution (DE) algorithm.

An enhanced control method for torque ripple minimization of switched reluctance motor using hybrid technique

In this manuscript, a hybrid technique is proposed for Torque Ripple (TR) minimization of Switched Reluctance Motor (SRM). The proposed technique is the consolidation of Wingsuit flying search (WFS) optimization and Gradient Boosting Decision Tree (GBDT) algorithm, hence it is known as WFS-GBDT technique. The control mechanisms consists of fractional order proportional integral derivative (FOPID) speed controller on external loop as well as current controller on internal loop with controlling turn activate and deactivate angles for SRM. The complexity of acquiring the ideal evaluation of proportional, integral and derivative gains for speed and current controller including turn activate and deactivate angles are deemed as a multi-objective optimization issue. Here, the WFS optimize the gain parameters of external speed loop along internal current loop with commutation angles for turn activate and deactivate switches. The WFS optimization processing is used to productive machine learning dataset under the types of SRM parameter. By using the satisfied dataset, the GBDT is predicted and mandatory forecasting is implemented in the entire machine operating stage. The optimized gain parameters based, the fractional order proportional integral derivative controller is tuned exactly. The proposed WFS-GBDT control technique lessens the torque ripple and quick settling time with this proper control, because of its systematic random search capabilities, thereby enhancing the dynamic execution of SRM drive. Finally, the proposed technique is activated in MATLAB/Simulink site, its performance is analyzed with existing techniques, like Base, ALO and WFS. The best, worst, mean, standard deviation for ISEspeed using proposed technique attains 230.5364, 231.5934, 230.952 and 0.05314. The best, worst, mean and standard deviation for torque ripple using proposed technique attains 0.4571, 0.6548, 0.585 and 0.472. The best, worst, mean, standard deviation for ISEcurrent using proposed technique attains 3.1257, 3.9754, 3.5783 and 0.0472.

A Switched Reluctance Motor Drive Controller Based on an FPGA Device with a Complex PID Regulator

This paper presents a proposal for a new type of regulator for switched reluctance motor (SRM) drives. The proposed regulator enables a significant extension of the rotational speed range and drive output power. This regulator is characterized by a complex structure, including two regulation modules: voltage and phase supply switch-on angle. The voltage module includes a proportional integral derivative (PID) voltage regulator. During its operation, the value of the phase supply switch-on angle and the width of the phase supply range are determined as a result of interpolation of the data previously determined in the simulation program. The other module contains the PID controller of the phase supply switch-on angle. The values of the angles included in the tables have been determined so as to ensure that the drive works with the greatest possible efficiency. The control method is determined based on the current operating parameters of the drive, i.e., torque and speed. The operation of the regulator was simulated in the MATLAB Simulink program. The regulator presented here was implemented in a field programmable gate array (FPGA). Tests of the regulator’s operation in the prototype system were carried out in the field of control of commutation angles.

Mathematical-physical modeling for analytical calculation of multilevel pulse-width modulations

Currently there is a great interest from the electronic physical point of view in reducing losses and optimizing the harmonic content of power converters. Especially of the multilevel ones that have great advantages since they can work with low commutations. That is why, this paper proposes and verifies a methodology for the development of equations for the analytical calculation of the effective value and the total harmonic distortion of step and Pulse width modulations type multilevel. The equations are obtained by analysis in the frequency domain using Fourier theory. A generalized mathematical expression is obtained as a function of the switching angles, which is theoretically verified by comparing the calculated with the expression and the MATLAB fast Fourier transform algorithm. These equations allow the modification of the upper limit of calculation of the series, a characteristic that can be used to determine a vector of commutation angles with the minimum value of harmonic distortion for a range of harmonics.

An Improved Torque Sharing Function to Minimize Torque Ripple and Increase Average Torque for Switched Reluctance Motor Drives

—This article presents a novel torque ripple minimization approach based on the genetic algorithm (GA) for the switched reluctance motor (SRM) drives. The fitness function of the GA is designed on the basis of two main optimization criteria. The first optimization criteria; three objectives are defined to optimize commutation angles minimizing torque ripple and copper loss. The second optimization criteria; an objective is defined to eliminate the negative torque which decreases the average torque in SRM drives. The achievement of all objectives depends on the adjusting appropriate the commutation angles of the torque sharing functions (TSF) during the commutation period. All of conventional TSFs are dependent on three different commutation angles, namely turn-on, turn-off, and overlapping. Due to the nonlinear phase inductances of SRM, the delay of current rising and falling time are not unity in overlapping commutation region. To overcome the separation of the incoming and outgoing phase currents during the commutation region, rise angle, and fall angle are used instead of overlapping angle. GA is used to optimize the commutation angles of conventional (sinusoidal) TSF and improved (sinusoidal) TSF. At the same time, the elimination negative torque effects on torque ripple, average torque, and copper loss is investigated.

Maximum Output Torque Control in Improved Flux Path Homopolar Brushless DC Motor With Axillary Field by Using Optimal Control of Turn-ON and Turn-OFF Angles in Variable Speed Applications

This paper presents the principles of operation, electromagnetic behavior analysis, and a search technique based on the finite-element analysis in order to determine the optimum control parameters of an improved flux path Homopolar brushless dc motor (IFP-HBLDC). In the proposed IFP-HBLDC structure, a permanent magnet is replaced by a dc excited assisted field coil to control and regulate the flux. In this paper, for different values of speed, maximum torque is determined by calculating the optimal turn-on and turn-off angles and the optimal field current which provides more flexible control over wide ranges of speed. To such aim, the behavior of the commutation angles is analyzed first by a numerical technique using the 3-D electromagnetic field analysis, in which the analysis of the collected data has shown that the commutation angles providing the maximum electromagnetic torque. The technique was successfully used offline to determine the optimum firing angles for achieving the highest drive efficiency to maximize the electromagnetic torque in a prototype 1.5-kW three-phase IFP-HBLDC motor drive intended for variable speed application. The performance prediction and test results are found in good correlation.

A fast switched reluctance motor controller based on FPGA

The paper presents the concept and practical implementation of a switched reluctance motor control system in an FPGA programmable device. The developed control system was designed for testing high-speed motors in order to limit the delays of output signals in relation to the signals from the encoder. The controller enables the values of commutation angles and PWM voltage to be set along with current limit values, measures the values of voltages and currents, and sends the results to the computer to be archived.

A switched-reluctance motor for aerospace application: Design, analysis and results

This paper presents a five-phase switched reluctance motor designed to satisfy the requirements of flap actuators in medium size aircrafts, a real example of the more electric aircraft trend. In normal conditions the machine operates with two phases conducting simultaneously but it is designed to satisfy the load specifications also with one or two phases open as consequence of fault remedial strategies. A finite-element study, aiming to predict both the healthy and faulty-mode performance, is presented. The mean torque vs. current capability and the torque ripple are investigated and optimum commutation angles are evaluated in static conditions. Experimental tests on the motor prototype are included, which confirm its capability to satisfy the planned degraded modes of operation and validate the design.

Multi-Objective Optimized Controller for Torque Ripple Minimization of Switched Reluctance Motor Drive System

Background/Objectives: In this paper, BC based optimized PID controller is developed for torque ripple minimization of SRM drive system. The proposed control algorithm comprised two optimized PID controllers for speed error and current error regulation loops of the SRMD control system. The proposed control algorithm is also optimizes the commutation angles for reducing the high torque ripples. Methods/Statistical Analysis: A new control algorithm for Torque Ripple Minimization of Switched Reluctance Motor (SRM) Drive system is proposed. The proposed control algorithm comprised two optimized Proportional, Integral and Derivative (PID) controllers for speed error and current error regulation loops of the SRMD control system. The proposed control algorithm is also optimizes the commutation angles for reducing the high torque ripples. In the proposed optimized controller, Artificial Bees Colony algorithm (ABC) is the optimization algorithm implemented to tune the gains of both PID controllers and commutation angles of the converter circuit. For tuning the accurate gains and angles, the multi objective functions are developed. The effectiveness of the proposed BC algorithm is implemented in the MATLAB/SIMULINK platform. Findings: The proposed control algorithm is based on the optimized PID controller for the speed and the current loops of the SRM drive system. The proposed control algorithm was used to optimize the gain parameters of the PID controller along with the commutation angles of the inverter. Here, the minimization of the error values of speed and torque serves as the objective functions. The advantages of the proposed method are robust performance as well as the increased level of reliability and flexibility in solving more complex problems. Applications/Improvements: The results obtained include superior performance with degradation in torque ripple and settling time. These merits are produced with elitism and a high-speed global search methodology, thus enhancing the dynamic performance of the SRM drives.

Commutation angles adjustment in SRM drives to reduce torque ripple below the motor base speed

This paper investigates the problem of high torque ripple in switched reluctance motor (SRM) drives. A method is proposed for below the base speed operation of SRM that determines both the turn-off and the turn-on angles for reducing motor torque ripple. Determination of the turn-off angle is an offline process performed through solving a multiobjective optimization function consisting of two criteria: torque ripple and copper loss. Turn-on angle adjustment, however, is an online process based on the intersection approach of consecutive phase currents, particularly proposed in this paper. Simulation and experimental results are presented to validate the reduction in torque ripple gained from the proposed angles control scheme.

Characteristics Analysis of an Excitation Assistance Switched Reluctance Wind Power Generator

In order to fully analyze the characteristics of an excitation assistance switched reluctance generator (EASRG) applied in wind power generation, a static model and a dynamic model are proposed. The static model is based on the 3-D finite-element method (FEM), which can be used to obtain the static magnetization and torque characteristics. The dynamic model, consisting of two lookup tables to describe the EASRG under different current and rotor positions, is built in Simulink to avoid the long computation time of a 3-D FEM model. The dynamic model is able to provide a more realistic assessment of the performance of the EASRG by considering the transient current, while the static model can only consider one constant current. The torque characteristics of the EASRG with different phase currents and commutation angles are studied. The turn-ON angle is found to have a more significant impact on the EASRG performance than the turn-OFF angle. Furthermore, the impact of the width of the rotor pole on the characteristics of the EASRG is studied with the help of the dynamic model. The design with the highest average torque can be achieved if the rotor pole width equals the stator pole width.

Driving Performance Advancement for SRM Using a Novel Adaptive Learning Control on Dominant Parameters

In this paper, an adaptive learning control (ALC) based on the repetitive tuning of the dominant energized parameters is proposed to minimize the torque ripple and energy conversion loss of the switched reluctance motors (SRMs). A simple and effective modulating strategy on excitation commutation angles and duty cycle is repeatedly applied to the SRM until desired performance tracking is achieved. According to the load variation, an initial suboptimum operating condition, derived from the expert’s knowledge and experience as well as accurate magnetization characteristics of the SRM, is offered to promise a well starting dynamics, learning ratio and convergence speed. Driving performance enhancement can be obtained on account of the best programming of phase current profiles via the well-tuned parameters to make minimum energy conversion loss and torque ripple reachable. Evolution and simulation based on the DSP-based processor has been developed to realize the proposed control approach and setup the SRM drive system. Experimental results on a 4-phase 8/6 pole SRM are given to show the effectiveness and performance enhancements of the presented control mechanism.

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.

Harmonic analysis of AC/DC systems based on phase-domain multi-port network approach

This paper describes a phase-domain frequency domain technique to the harmonic analysis of a three-phase AC/DC system. The methodology is based on the harmonic multi-port network concept, expressed in terms of an ABCD parameter matrix which links voltage and current harmonics of different orders on both sides of the converter. Since the commutation angles are unknown, the harmonic interactions are computed by a sequential solution of the AC/DC system state variables, related by the ABCD matrix, and the updating of the commutation periods. A set of analytical equations has been derived to compute commutation times taking place in the converter. Test results are presented which demonstrate the effectiveness of the proposed methodology to assess harmonic interactions on both balanced and unbalanced operating conditions. The results are validated to those obtained by a time domain simulation.