Vector Modulation Research Articles

Delay drift compensation of an optoelectronic oscillator over a large temperature range through continuous tuning

Phase noise reduces target sensitivity in radar and increases bit error rate in telecommunications systems. Optoelectronic oscillators are known for using optical fibre technology to realise the large delay required to attain superior phase noise performance compared to conventional microwave source technology. However, the long fibre is vulnerable to environmentally induced phase perturbations, while conventional phase shifters have insufficient range to compensate for the phase drift over the operational temperature range without the use of a temperature-controlled enclosure. Here we introduce a vector modulator controlled by a Stuart-Landau integrator, as a solution to non-efficient tuning for the phase shift. The concept is verified by simulation and experimentally demonstrated using an optoelectronic oscillator phase-locked to a system reference. Phase lock is maintained over four free spectral ranges equivalent to a tuning phase range of 1440° when the optoelectronic oscillator is cycled over a 10 °C to 85 °C temperature range. These demonstrations highlight the practical potential of our continuous tuning method.

IMPLEMENTATION OF VECTOR MODULATION APPLIED TO THE THREE-PHASE DC-AC CONVERTER VSI USING A FOUR-STATE SWITCHING CELL

This article presents the implementation of spatial vector modulation applied to the three-phase VSI converter with four-state switching cell. The methodology used is shown in detail, indicating the vectors used, the applied switching sequence and the calculations of the vector activation times. It also contains the results of the converter operation in simulation, showing the main waveforms. The following presents the results obtained by experimentation with the assembled prototype.

Modulation Strategy with Minimum Switching Losses for Three-Phase Non-Isolated AC–DC Matrix Converters

This paper presents an analysis of the operational characteristics of three-phase AC–DC matrix converters, which operate as rectifiers but possess a range of additional capabilities. These include the ability to reverse the power flow, control the input power factor, and generate a multilevel output voltage. The analysis yields a modulation strategy that minimizes switching losses. The proposed modulation strategy is compared with seven well-known space vector modulation strategies in terms of efficiency and distortion of input and output current. The performance is experimentally validated.

Vector modulation of fully-polarized phase conjugate light field through scattering media

Vector modulation of the light field through scattering media holds significant scientific and application value in areas such as optical imaging, optical communications, nonlinear optics, and biomedicine. Digital optical phase conjugation (DOPC), grounded in the time reversal principle, has been extensively investigated for wavefront shaping in scattering media. Nonetheless, reports on vector modulation of phase conjugate beams via DOPC remain scarce. In this study, we propose a vector DOPC to recover and modulate the polarization state of the phase conjugate beams based on vector decomposition and superimposition of light field. First, pre-set two orthogonal polarization basis probe beams to pass through a multimode fiber and use digital holography to record the phase distribution of their orthogonal polarization components in the speckle field. Then, perform polarization-preserving phase conjugation and vector superposition of both components simultaneously. By altering the phase difference and amplitude ratio between the two, vector modulation of the synthesized phase conjugate beam can be achieved. Theoretical analysis aligns well with experimental results, demonstrating a positive impact on understanding the physical properties of scattering media and expanding the applications of the DOPC technique.

Enhanced Active Voltage Regulation Capability for Three-Level NPC Converters with the Space Vector Modulation Method

Enhanced Active Voltage Regulation Capability for Three-Level NPC Converters with the Space Vector Modulation Method

Direct Torque Control Space Vector Modulation for Induction Motor Driven by Matrix Converter

This study proposes enhancing induction motor (IM) drive systems by developing a DTC-MC with SVPWM integration to reduce ripple. DTC-MC is effective for precise torque control in AC drives, offering high control accuracy by isolating stator flux and torque. The method excels in sensor-less speed control, maintaining unity input power factor at low speeds, and constant switching frequency for rapid torque adjustments. Combining DTC-MC with SVPWM improves simplicity, dynamic behavior, and torque response. The DTC-SVM approach further refines the torque response by correcting flux and torque discrepancies. MATLAB/SIMULINK simulations validated the approach, showing a robust dynamic response and significantly reduced motor torque ripple and control of speed.

Dynamic overmodulation strategy based on torque and flux optimal tracking for DTC‐SVM of surface‐mounted PMSM drives

AbstractDirect torque control with space vector modulation has been increasingly attracting emphasis for permanent‐magnet synchronous machine control, benefiting from a high dynamic response and low torque ripple. However, the rapid tracking performance of torque and stator flux linkage is gradually deteriorating as the machine enters the overmodulation region because of the output‐voltage limitation of the inverter. Therefore, to enhance the system tracking performance in the overmodulation region, an innovative overmodulation method based on torque and flux optimal tracking is proposed. In contrast to the conventional overmodulation method where only one of the torque and stator flux linkage tracking is considered, the proposed strategy first constructs the weightless cost function to achieve a trade‐off control between the torque and stator flux linkage. Then, by using an equivalent geometric path to intuitively express the weightless cost function, the minimum cost function can be easily solved and the optimal output voltage vector can be determined correspondingly, to achieve the fast‐tracking of both the torque and stator flux linkage. Additionally, the voltage utilization of different overmodulation schemes is also analysed. Finally, the experimental results demonstrate the efficiency and practicality of the proposed strategy.

Comparison of space vector and switching frequency optimal pulse width modulation for diode free F‐type multi level inverter

AbstractThis study presents a comprehensive examination of space vector pulse width modulation (SVPWM) and switching frequency optimal PWM (SFOPWM) for an F‐type multilevel inverter (FTMLI). SVPWM offers a simple, digital implementation for three‐phase, three‐level inverter structures, and carrier‐based SFOPWM allows for maximum use of switching frequency with a simple construction. This approach reveals the underlying relationship between the above two PWM techniques with various amplitude and frequency modulation indices to ensure the performance of FTMLI. A suitable comparative study was carried out to verify the PWM techniques based on the inverter output voltage, total harmonic distortion, switching stress, and filter size. The analytical conclusions are supported by the simulation results and their experimental validation.

A review on modulation techniques of Quasi-Z-source inverter for grid-connected photovoltaic systems

Photovoltaic (PV) is a promising way to meet the increasing global energy demand due to its sustainability, efficiency, and cost-effectiveness. For the wide-scale adoption of PV systems, converters with reliable input sources, stable control strategies and appropriate modulation techniques must be designed. In the literature, various modulation techniques have been developed that help to boost the voltage of the PV modules by implementing shoot-through (ST) in which the upper and lower switches of an inverter conduct simultaneously and short-circuit occurs. Various optimised modulation techniques have been implemented to enhance its performance. Among those, the quasi-Z-source inverter (qZSI) has attracted much attention due to its ability to achieve higher conversion ratios for grid-connected PV applications. In this paper, a detailed comparison of the modulation schemes for the qZSI PV systems has been done to understand the trade-off and select the most suitable approach. Upon the selection of the space vector modulation with unique switching sequences and rearranging upper ST and lower ST states, the inverter can achieve ST with reduced switching losses. Furthermore, a 600 VA three-phase grid-connected system utilizing a three-level neutral-point-clamped qZSI topology is modulated and simulated. It has been demonstrated that the constant boost control offers good performance in terms of reduced voltage stresses on switches, lower total harmonic distortion, and hence, higher efficiency.

Direct torque control of a dual star induction generator based on a modified space vector PWM under fault conditions

Recent studies have shown that electrical systems in wind power conversion are subject to a 67 % failure rate, and conventional three-phase generators are considered to be the most sensitive to these faults. Induction generator current harmonics are a major source of torque ripples causing acoustic noise and vibrations. These ripples can progressively increase under faulty operating conditions. In six-phase machines, there is appearance of high harmonic currents in the air gap as space harmonics. Power electronic converters are also subject to faults, the most common being Short-Circuit (SC) and Open-Circuit (OC) faults. SC faults cause large peaks in the line currents, which trigger the protection devices, resulting in a complete shutdown of the production system. OC faults, on the other hand, cause imbalances in the phases, but the system remains in operation.Direct Torque Control (DTC) based on Space Vector Modulation (SVM) at constant switching frequency is an effective solution to tackle induction generator current harmonics. This paper proposes a DTC combined with a Proportional Integral Fuzzy Logic Controller (PIFLC) optimized by Particle Swarm Optimization (PSO) in order to overcome the problems of torque ripples. Furthermore, using Vector Space Decomposition (VSD) and the Modified Space Vector Pulse Width Modulation (MSVPWM) strategy, a significant reduction of harmonics in the air-gap can be achieved.Simulations were carried out under MATLAB/Simulink, and the results obtained demonstrate the superiority of the proposed DTC-PIFLC-PSO controller in terms of robustness against wind speed variations and under faulty switch conditions in the power converter of the Dual Star Induction Generator (DSIG) generator. In addition, a comparative study with the classical PI controller is presented to show the effectiveness of the DTC-PIFLC-PSO controller against faults with a significant reduction in the Total Harmonic Distortion (THD) during both faulty and non-faulty conditions.

Identifying Gravity-Related Artifacts on Ballistocardiography Signals by Comparing Weightlessness and Normal Gravity Recordings (ARTIFACTS): Protocol for an Observational Study.

Modern ballistocardiography (BCG) and seismocardiography (SCG) use acceleration sensors to measure oscillating recoil movements of the body caused by the heartbeat and blood flow, which are transmitted to the body surface. Acceleration artifacts occur through intrinsic sensor roll, pitch, and yaw movements, assessed by the angular velocities of the respective sensor, during measurements that bias the signal interpretation. This observational study aims to generate hypotheses on the detection and elimination of acceleration artifacts due to the intrinsic rotation of accelerometers and their differentiation from heart-induced sensor accelerations. Multimodal data from 4 healthy participants (3 male and 1 female) using BCG-SCG and an electrocardiogram will be collected and serve as a basis for signal characterization, model modulation, and location vector derivation under parabolic flight conditions from µg to 1.8g. The data will be obtained during a parabolic flight campaign (3 times 30 parabolas) between September 24 and July 25 (depending on the flight schedule). To detect the described acceleration artifacts, accelerometers and gyroscopes (6-degree-of-freedom sensors) will be used for measuring acceleration and angular velocities attributed to intrinsic sensor rotation. Changes in acceleration and angular velocities will be explored by conducting descriptive data analysis of resting participants sitting upright in varying gravitational states. A multimodal data set will serve as a basis for research into a noninvasive and gentle method of BCG-SCG with the aid of low-noise and synchronous 3D gyroscopes and 3D acceleration sensors. Hypotheses will be generated related to detecting and eliminating acceleration artifacts due to the intrinsic rotation of accelerometers and gyroscopes (6-degree-of-freedom sensors) and their differentiation from heart-induced sensor accelerations. Data will be collected entirely and exclusively during the parabolic flights, taking place between September 2024 and July 2025. Thus, as of June 2024, no data have been collected yet. The data will be analyzed until December 2025. The results are expected to be published by June 2026. The study will contribute to understanding artificial acceleration bias to signal readings. It will be a first approach for a detection and elimination method. Deutsches Register Klinische Studien DRKS00034402; https://drks.de/search/en/trial/DRKS00034402. PRR1-10.2196/63306.

Backstepping control of multilevel modified SVM inverter in variable speed DFIG-based dual-rotor wind power system

The backstepping control (BC) scheme has been successfully used in a variety of high-effectiveness industrial AC drives. This study presents the application of the BC technique based on multilevel modified space vector modulation (BC-MSVM) to get better the energy performance of a dual-rotor wind turbine system (DRWT). Two techniques are suggested to command the stator power of a doubly-fed induction generator (DFIG) driven by a DRWT. This work addresses the problems of the DRWT-based energy production system, such as stream fineness, power overshoot, and torque ripples. The use of a multilevel inverter in BC-MSVM led to an enhancement in the competence of the multilevel BC-MSVM technique and the system as a whole, and this is proven by the results performed using MATLAB software on a 1500 kW DFIG-DRWT. The use of a seven-level inverter led to a minimization in the rates of overshoot, ripples, steady-state error, and response time of active power by 26.66%, 53.84%, 2.09%, and 9.09%, respectively. Regarding the reactive power, the ratios were estimated at 18.12%, 34%, 25%, and 1.41%, respectively. These ratios prove that using a higher-level inverter significantly improves the voltage quality and characteristics of the DFIG-DRWT.

Improved Control Strategy for Dual-PWM Converter Based on Equivalent Input Disturbance

Aiming at the problems of jittering waveforms and poor power quality caused by external disturbances during the operation of a dual-pulse-width-modulation (PWM) converter, an improved terminal sliding mode control and an improved active disturbance rejection control (ADRC) are investigated. The method is based on mathematical models of grid-side and machine-side converters to design the controllers separately, and the balance between the two sides is maintained by the capacitor voltage. An improved terminal fuzzy sliding mode control and equivalent input disturbance (EID)-error-estimation-based active disturbance rejection control are presented on the grid side to improve the voltage response rate, and an improved support vector modulation (SVM)–direct torque control (DTC)–ADRC method is developed on the motor side to improve the robustness against disturbances. Finally, theoretical simulation experiments are built in MATLAB R2023a/Simulink to verify the effectiveness and superiority of this method.

Robust fuzzy controller design with FPGA implementation for matrix converter based induction motor drive

This paper aims to design a controller for a matrix converter fed induction motor drive providing less torque ripples and eliminating peak overshoots with good transient and steady state responses utilizing fuzzy and direct torque control. The proposed controller utilizes Direct Torque Control (DTC) strategy with space vector modulation for regulating stator flux and electromagnetic torque. Due to the superior control capabilities of the matrix converter such as bidirectional power flow, sinusoidal input/output waveforms, high power density and lesser volume, it has attracted significant research interest in the field of adjustable speed drive. Hence the proposed matrix converter based controller is developed in MATLAB/Simulink and tested in different input/output conditions. To validate simulation results, a laboratory prototype is built around the Altium Nano Board 3000 equipped with a Xilinx Spartan using Field Programmable Gate Array (FPGA) is employed. The proposed control scheme, validated through simulation and hardware testing, ensures stable, robust drive system with significant reductions in input side harmonics and enhances induction motor drive's performance.

A Novel Model Predictive Current Control With Reduced Computational Burden Based on Discrete Space Vector Modulation for PMSM Drives

A Novel Model Predictive Current Control With Reduced Computational Burden Based on Discrete Space Vector Modulation for PMSM Drives

Quantum Sugawara operators in type A

The quantum Sugawara operators associated with a simple Lie algebra g are elements of the center of a completion of the quantum affine algebra Uq(gˆ) at the critical level. By the foundational work of Reshetikhin and Semenov-Tian-Shansky (1990), such operators occur as coefficients of a formal Laurent series ℓV(z) associated with every finite-dimensional representation V of the quantum affine algebra. As demonstrated by Ding and Etingof (1994), the quantum Sugawara operators generate all singular vectors in generic Verma modules over Uq(gˆ) at the critical level and give rise to a commuting family of transfer matrices. Furthermore, as observed by E. Frenkel and Reshetikhin (1999), the operators are closely related with the q-characters and q-deformed W-algebras via the Harish-Chandra homomorphism.We produce explicit quantum Sugawara operators for the quantum affine algebra of type A which are associated with primitive idempotents of the Hecke algebra and parameterized by Young diagrams. This opens a way to understand all the related objects via their explicit constructions. We consider one application by calculating the Harish-Chandra images of the quantum Sugawara operators. The operators act by scalar multiplication in the q-deformed Wakimoto modules and we calculate the eigenvalues by identifying them with the Harish-Chandra images.

Modified load angle direct torque control for dual star motor using fuzzy logic

Space Vector Modulation (SVM) has emerged as a prominent alternative for motor control, particularly within the framework of Direct Torque Control (DTC-SVM). SVM leverages variations in the load angle, which result from changes in motor torque, to generate the appropriate voltage vectors. The conventional approach to this method involves a single Proportional-Integral (PI) regulator, which is characterized by a constant switching frequency and the capability to reduce ripples in torque, flux, and current. Despite these advantages, the PI regulator may face challenges in maintaining optimal performance under varying load conditions. This study seeks to enhance the performance of the DTC-SVM strategy by integrating Fuzzy Logic into the PI regulator. The primary objective is to improve the accuracy and responsiveness of the load angle control, thereby optimizing the motor's operational efficiency. The proposed SVM-Fuzzy control scheme is designed to address the limitations of the traditional PI regulator, offering a more adaptive and robust solution for motor control. To evaluate the effectiveness of the proposed approach, extensive simulations were conducted using Matlab Simulink. The SVM-Fuzzy strategy was compared against the conventional SVM-PI approach to assess its performance in terms of torque, flux, and current regulation. The SVM-Fuzzy control scheme significantly enhances efficiency, stability, and load angle precision, particularly in Double Star Induction Motors (DSIM). It also ensures the durability and reliability of the motor control system under different operating conditions.

Ab initio calculations and crystal structure simulations for mixed layer compounds from the tetradymite series

Abstract Density functional theory (DFT) is used to obtain structural information of seven members of the tetradymite homologous series: Bi2Te3 (tellurobismuthite), BiTe (tsumoite), Bi4Te3 (pilsenite), Bi5Te3, Bi2Te, Bi7Te3 (hedleyite), and Bi8Te3. We use the formula S(Bi2kTe3)·L[Bi2(k+1)Te3] as a working model (k = 1–4) where S and L are short and long modules in the structures. The relaxed structures show an increase in the a parameter and decrease in the interlayer distance (dsub) from Bi2Te3 (2.029 Å) to Bi8Te3 (1.975 Å). DFT-derived formation energy for each phase indicates that they are all thermodynamically stable. Scanning transmission electron microscopy (STEM) simulations for each of the relaxed structures show an excellent match with atom models. Simulated electron diffractions and reflection modulation along c* are concordant with published data, where they exist, and with the theory underpinning mixed-layer compounds. Two modulation vectors, q = γ·csub* (γ = 1.800–1.640) and qF = γF·dsub* (γF = 0.200–0.091), describe the distribution of reflections and their intensity variation along dsub* = 1/dsub. The γF parameter reinforces the concept of Bi2kTe3 and Bi2(k+1)Te3 blocks in the double module structures, and γ relates to dsub variation. Our model describing the relationship between γ and dsub allows prediction of dsub beyond the compositional range considered in this study, showing that phases with k >5 have values dsub within the analytical range of interlayer distance in bismuth. This, in turn, allows us to constrain the tetradymite homologous series between γ values of 1.800 (Bi2Te3) and 1.588 (Bi14Te3). Phase compositions with higher Bi/Te should be considered as disordered alloys of bismuth. These results have implications for mineral systematics and classification as they underpin predictive models for all intermediate structures in the group and can be equally applied to other mixed-layer series. Our structural models will also assist in understanding variation in the thermoelectric and topological insulating properties of new compounds in the broader tetradymite group and can support experimental work targeting a refined phase diagram for the system Bi-Te.

A Novel 3-D Space Vector Modulation Strategy for Open-End Winding PMSM

A Novel 3-D Space Vector Modulation Strategy for Open-End Winding PMSM

Passivity-based adaptive current control loop of cascaded H-bridge multilevel converter for grid-tied photovoltaic system

This paper proposes an algorithm to passivity-based control (PBC) for the current control loop of the cascaded H-bridge converter (CHB) connecting the grid-connected PV system with the space vector modulation (SVM) algorithm using the law of expanding any number of voltage levels. The algorithm SVM in this paper is suitable for CHB converters. It can create a number of high levels of alternating voltage that other methods cannot do. Passivity-based control (PBC) algorithm aims to create a flexible controller that can change its structure or parameters to adapt to changes in the system, ensuring stable system quality, reducing switching losses and gaining energy conversion efficiency. It enhances the capability of accurately delivering power on demand to the grid with the CHB inverter in situations in which the grid demands the mobilization of maximum power from the photovoltaics (PV) system. The simulation results of the 9-level CHB system performed by MATLAB/Simulink software have proved the feasibility of the proposed algorithm.