Space Vector Research Articles

FPGA Implementation of a Multiphase Space Vector Modulation for Asymmetrical Dual Three–phase AC Machines

Current control in conventional motor drives is normally based on controllers with sub harmonic voltage modulation techniques. Space vector modulation (SVM) for three–leg VSI and conventional motor drives has recently become a standard current control technique due to its benefits. That’s why modern microcontrollers and DSPs offer internal peripheral to implement SVM technique for conventional drives. Multiphase (more than three phases) drives possess interesting advantages over conventional three–phase drives. Over the last years, topics related to the extension of control schemes to these specific drives have been covered in depth in literature. However, implementation of SVM for multiphase drives is rare due to its complexity and the specific control peripherals absence. This paper presents the FPGA implementation of a SVM strategy for a very interesting and discussed multiphase drive: the asymmetrical dual three–phase AC machine.

A Control Strategy for Combined Series-Parallel Active Filter System under Non-Periodic Conditions

In this study, generalized non-active power theory based control strategy is proposed for a 3-phase 4-wire Combined Series-Parallel Active Filter (CSPAF) system using a Three-Dimensional (3D) Space Vector Pulse Width Modulation (SVPWM). The CSPAF system consists of a Series Active Filter (SAF) and a Parallel Active Filter (PAF) combination connected a common Direct Current (DC) link for simultaneous compensating the source voltage and the load current. The generalized non-active power theory was applied in previous studies for the PAF control, in this study the theory is used for the CSPAF system control under non-sinusoidal and nonperiodic current and voltage conditions. The closed loop control algorithm for the proposed CSPAF system has been described to direct control of filtering performance by measuring source currents and load voltages for the PAF and the SAF, respectively. The proposed control strategy has been verified by simulating the CSPAF system in Matlab/Simulink environment.

A Power-Decoupled Three-Phase Current Source Inverter with Model Predictive Control in An Unbalanced Grid

The current source inverter (CSI) is a promising interface between the Photovoltaic (PV) panel and the three-phase AC grid. It boosts the PV panel voltage by a DC-link inductor and converts the maximum available PV power. In an unbalanced grid, double-line-frequency pulsating powers will be generated in the CSI, increasing the rating of the DC-link inductor and impeding the maximum power point tracking (MPPT) operation. To address this issue, a power decoupling (PD) circuit for a three-phase CSI is proposed in this paper. By using the DC-link inductor and active switches multiplex, the proposed PD circuit can reduce the current rating of the DC-link inductor with fewer active switches, and no detrimental power components are introduced to the utility grid. Moreover, to concurrently control multiple objectives without multiple loops, a model predictive control (MPC) method is further proposed for the PD-CSI, achieving a rapid response of PD-CSI. Besides, a space vector pulse width modulation (SVPWM) method is proposed for the PD-CSI to enhance the utilization of DC voltage, helping to reduce the voltage stress of the ripple storage capacitor. The priorities of the proposed topology and the corresponding control and modulation methods are finally verified by comparative experimental results.

A Simple Method for Detection of Voltage Sags and their Mitigation using a Dynamic Voltage Restorer

Power quality is the major focus of progressive nations.In the era of smart grid,power quality receives a lot of thrust at all voltage levels namely,medium ,high and low.The objective of this paper is to present a simple and cost effective method of sag detection and mitigation in three phase systems at the consumer's end. The use of the concept of space vector representation of three phase quantities, effectively in the detection ,quantification and mitigation of short duration voltage disturbances such as sags in three phase supply systems under both balanced and unbalanced conditions of operation is presented.Three phase balanced quantities can be represented by a synchronously rotating space vector of constant magnitude .The two phase equivalent of which on a stationary reference frame are orthogonal to each other.When balanced sags occur,the magnitude of the rotating space vector obtained as a resultant of its orthogonal components is sensed for magnitude deviations from its constant nominal value.A trigger signal of varying amplitude is generated in proportional response to the detection of the deviation in its magnitude . In case of sags occurring on one or two phases of the supply, (unblanced),the positive sequence components of the unbalanced three phase quanities are determined using mathematical transformations and the magnitude of the resultant is found out. This resultant is sensed and its deviations from nominal value are measured and used to generate the trigger after processing.The trigger thus generated, initiates the control system of a Dynamic Voltage Restorer(DVR).When a sag is detected,the trigger signal generated, switches on the control circuit of the inverter which uses the space vector pwm control using sampled phase amplitudes of the control signal to generate the modulating wave in proportion to the deviation of the sag voltage from the reference value.The fundamental component of the output voltage which in proportion to the deviation from the nominal value is injected in series with the three phase disturbed signal through a transformer of suitable gain .The results show the successful operation of the DVR in maintaining nominal value of the voltage across the load through out the duration of the disturbance for all cases of balanced and unbalanced operation. The paper presents the detection algorithm as well as the control algorithm for restoration of voltage which are simple and easy to implement .

A Novel Method to Eliminate Negative Time Period of SVPWM using DSP TMS320F2812

Conventional SVPWM method generates negative time period during lower switching frequency at higher voltage magnitudes. This paper presents a simplified method for implementation of Space Vector PWM technique for two level VSI using DSP TMS320F2812. Methodology presented is to implement SVPWM without lookup table and to calculate time periods independent of voltage magnitude. Experimental results show that proposed method overcomes problem of negative time period for said conditions. An experimental setup is developed in the laboratory around TMS320F2812 to obtain and verify the desired results. This work is a part of project titled “Development of FPGA-DSP Controlled Multilevel Inverter Interface for Grid connection of Wind Turbine Generators” funded by AICTE New Delhi.

Space Vector Fundamental Frequency Modulation Compared with the Selective Harmonic Elimination Method

A new modulation strategy for three-phase multilevel-converters, called Space Vector Fundamental Frequency Modulation will be presented. Derived from conventional Space Vector PWM, it was developed to overcome Selective Harmonic Elimination Method in mathematical complexity. Besides the harmonic optimization, the method offers a variable modulation index and is applicable for real-time applications. But in contrast to Selective Harmonic Elimination Method it is an approximation procedure. In this paper, both methods are compared, concerning several criteria such as voltage quality and mathematical complexity. Also, a classification with reference to EN 50160 is presented.

Robust Voltage Vector-Controlled Three-Phase SAPF-based BPMVF and SVM for Power Quality Improvement

The multiplication of nonlinear loads leads to significant degradation of the energy quality, thus the interconnection network is subject to being polluted by the generation of harmonic components and reactive power, which causes a weakening efficiency, especially for the power factor. In three-phase systems, they can cause imbalances by causing excessive currents at the neutral. This research treats the operation of robust voltage-oriented control (VOC) for a shunt active power filter (SAPF). The main benefit of this technique is to guarantee a decoupled control of the active and reactive input currents, as well as the input reference voltage. To sustain the DC voltage, a robust PI-structure-based antiwindup is inserted to ensure active power control. Besides, a robust phase-locked loop (PLL)-based bandpass multivariable filter (BPMVF) is used to improve the network voltage quality. Furthermore, a space vector modulation (SVM) is designed to replace the conventional one. A sinusoidal network current and unitary power factor are achieved with fewer harmonics. The harmonics have been reduced from 27.98% to 1.55% which respects the IEEE 519-1992 standard. Expanded simulation results obtained from the transient and steady-state have demonstrated the high performance of the suggested control scheme.

A new method for the characterization and type detection of voltage sag using active voltage component

ABSTRACT In this paper, a new power quality (PQ) index, namely active voltage component (AVC), has been developed using the help of symmetrical component analysis (SCA). Furthermore, the developed PQ index, i.e., AVC, has been used for the identification of the faulted phase and characterization of the voltage sags. The effectiveness and accuracy of the developed technique have been revealed by considering the voltage sag signals from IEEE database. Through the outcomes, as attained with the AVC, it is revealed that the sag duration and type are exactly same as the real recorded test signals. Also, it is shown that the developed index, i.e. AVC, is sufficient for the simultaneous characterization, classification, and detection of the voltage sag. The error in sag duration with the proposed index is found to be zero while the other existing methods either under-or over-estimate the sag duration. Finally, the shortfalls of the existing methods, based on SCA and space vector (SV), have also been discussed. Through the comparative studies, it is shown that the existing methods, based on SCA and SV, provide the erroneous characterization due to oscillation and noise present in the voltage sag signals while the proposed index provides accurate characterization, classification, and detection.

Analytical investigation of induction motor drive under DC-link voltage ripple in voltage source inverter.

Analytical analysis and mathematical model of ripple components of the DC-link voltage of three-phase voltage source inverter and its influence on an induction motor drive both in time and frequency domain are presented in this paper. The analytical expressions for the voltage and current space-vectors as a function of the DC-link voltage pulsation are derived. From the current space vectors the torque behavior is estimated again as a function of DC-link voltage pulsation. The proposed analytical method is based on the mixed p-z approach enabling presentation of the results in closed-form.

Comparison of the effect of output filters on the total harmonic distortion of line current in voltage source line converter - simulation study.

Two different output filter topologies are considered, namely the LCL- and L+LC-filter. The space vector modulation (SVM) is used to control the power switches of the converter. Design methods for both filter types are proposed. The methods are used to dimension the filter components. The performances of the filters designed are verified by simulations to meet the given line current total harmonic distortion (THD) requirement. The study reveals that the LCL-filter is more effective a filter topology in attenuating line current harmonic components than the L+LC-filter.

DSP based space vector PWM control for solar electric vehicle

Solar Electric Vehicles (SEV) are considered the future vehicles to solve the issues of air pollution, global warming, and the rapid decreases of the petroleum resources facing the current transportation technology. However, SEV are still facing important technical obstacles to overcome. They include batteries energy storage capacity, charging times, efficiency of the solar panels and electrical propulsion systems. Solving any of those problems and electric vehicles will compete-complement the internal combustion engines vehicles. In the present work, we propose an electrical propulsion system based on three phase induction motor in order to obtain the desired speed and torque with less power loss. Because of the need to lightweight nature, small volume, low cost, less maintenance and high efficiency system, a three phase squirrel cage induction motor (IM) is selected in the electrical propulsion system. The IM is fed from three phase inverter operated by a constant V/F control method and Space Vector Pulse Width Modulation (SVPWM) algorithm. The proposed control strategy has been implemented on the texas instruments TM320F2812 Digital Signal Processor (DSP) to generate SVPWM signal needed to trigger the gates of IGBT based inverter. The inverter used in this work is a three phase inverter IRAMY20UP60B type. The experimental results show the ability of the proposed control strategy to generate a three-phase sine wave signal with desired frequency. The proposed control strategy is experimented on a locally manufactured EV prototype. The results show that the EV prototype can be propelled to speed up to 60km/h under different road conditions.

Bidirectional PWM Converter to Interface AC Part to DC Microgrid with Neutral Potential Balancing

This research presents a description of a bidirectional pulse width modulated converter that functions as a rectifier by using the direct power control strategy and space vector modulation technology. In contrast to the voltage-oriented control strategy, this method minimises the number of internal current loops and requires more tuning. While functioning as an inverter, it applies the space vector modulation technique as well. The approach, on the other hand, is not the same as rectifiers since it calculates the duty ratio of the neighbouring voltage vectors in each small triangle that is generated in each sector that has a period of 60 degrees. In both situations, the neutral point potential has been brought back into equilibrium.

Vector control strategy of the 5-Phase 2-Level VSI

The paper describes an example of the vector control strategy applied to five-phase two-level inverters. Two base methods are discussed. The first one is based on the standard space vector transformation, while the other uses state vectors which enable the definition of the basic physical quantities of the inverter. The proposed notation system offers an universal simplification of vector identification. It comprises a standardized proposal of notation and vector marking. This tool may be really useful for the description of inverter states and makes it possible to reach correlation between state and space vectors. All vectors are defined by use of the same digits. The proposed mathematical tool has been verified during simulation tests performed with the use of the PLECS program.

Image scanning microscopy: a vectorial physical optics analysis.

Image scanning microscopy (ISM) achieves resolution beyond the diffraction limit by a factor of 2. However, prior ISM research predominantly employs scalar diffraction theory, neglecting critical physical effects such as polarization, aberrations, and Stokes shift. This paper presents a comprehensive vectorial ISM point spread function (PSF) model that accounts for these phenomena. By considering the effect of polarization in emission and excitation paths, as well as aberrations and Stokes shift, our model provides a more accurate representation of ISM. We analyze the differences between scalar and vectorial theories in ISM and investigate the impact of pinhole size and aberration strength on resolution. At a numerical aperture of 1.2, the full width half maximum (FWHM) discrepancy between scalar and vectorial ISM PSFs can reach 45 nm, representing a 30% deviation from the vectorial model. Additionally, we explore multiphoton excitation in ISM and observe increased FWHM for 2-photon and 3-photon excitation compared to 1-photon excitation. The FWHM of the 2-photon excitation ISM PSF increases by 20% and the FWHM of the 3-photon excitation ISM PSF increases by 28% compared to the 1-photon excitation ISM. In addition, we found that the optimal sweep factor for 2-photon ISM is 1.22, and the optimal sweep factor of 3-photon ISM is 1.12 instead of the 2 predicted by the one-photon scalar ISM theory. Our work improves the understanding of ISM and contributes to its advancement as a high-resolution imaging technique.

Simple Control Schme of Three-Level PWM Converter Connecting Wind Turbine with Grid.

This paper proposes a simple direct power control using space vector modulation (DPC-SVM) for three-phase three level neutral point clamped (3L-NPC) PWM converter connecting a wind turbine generator with grid. The active and reactive power are used as the control variables instead of the currents applied in conventional control method. Moreover, grid voltage sensors are replaced by a virtual flux (VF) estimator. The theoretical principle of this method as well as the synthesis of the active and reactive power controllers are discussed. It is shown that the proposed method exhibits several features as: simple and robust algorithm as well as simple tuning procedure of PI power controllers. Furthermore the paper presents a LCL-filter design, which fulfils IEEE-SCR 20-50 recommendation. Simulation results have proven an excellent performance and verified the validity of the proposed system.

Improved Feedback Quantizer with Discrete Space Vector.

The use of advanced modulation and control schemes for power converters, such as a Feedback Quantizer and Predictive Control, is widely studied in the literature. This work focuses on improving the closed-loop modulation scheme called Feedback Quantizer, which is applied to a three-phase voltage source inverter. This scheme has the natural behavior of mitigating harmonics at low frequencies, which are detrimental to electrical equipment such as transformers. This modulation scheme also provides good tracking for the voltage reference at the fundamental frequency. On the other hand, the disadvantage of this scheme is that it has a variable switching frequency, creating a harmonic spectrum in frequency dispersion, and it also needs a small sampling time to obtain good results. The proposed scheme to improve the modulation scheme is based on a Discrete Space Vector with virtual vectors to obtain a better approximation of the optimal vectors for use in the algorithm. The proposal improves the conventional scheme at a high sampling time (200 μs), obtaining a THD less than 2% in the load current, decreases the noise created by the conventional scheme, and provides a fixed switching frequency. Experimental tests demonstrate the correct operation of the proposed scheme.

Improved virtual space vector modulation for neutral point voltage oscillation and common-mode voltage reduction in neutral point clamped three-level inverter

Improved virtual space vector modulation for neutral point voltage oscillation and common-mode voltage reduction in neutral point clamped three-level inverter

Minimisation of AC Grid Side Input Power Factor Angle for Three-phase AC to Three-phase AC Matrix Converter under Varying Load

Abstract Minimisation of AC grid side input power factor angle for a ‘matrix converter (MC)’ improves the efficiency of the grid. Input volt-ampere requirement is minimum if the current drawn by the ‘MC’ is sinusoidal and input displacement power factor (IDPF) is unity. A MC is inherently capable of maintaining a unity displacement power factor (UDPF) angle at its input terminals. However, the input currents drawn from the grid are not sinusoidal. The high-frequency ripples are suppressed by input current filters (ICFs).These filters additionally introduce a leading phase angle for the current which varies with the loading. This phase lead can be compensated by adjusting the angle between the input current space vector and the input voltage space vector of the MC. The computation of this adjustment angle depends on the estimation of power losses in the switching devices. A simple method is proposed in this paper to estimate the switching losses without measuring device voltages and currents using the perturbation technique. The perturbation logic depends on input current, instantaneous active and reactive power computed at regular intervals of time. The proposed method effectively minimises the IDPF angle very close to zero. The experimental results are included for validation,

A symplectic approach to Schrödinger equations in the infinite-dimensional unbounded setting

<p>By using the theory of analytic vectors and manifolds modeled on normed spaces, we provide a rigorous symplectic differential geometric approach to $ t $-dependent Schrödinger equations on separable (possibly infinite-dimensional) Hilbert spaces determined by families of unbounded self-adjoint Hamiltonians admitting a common domain of analytic vectors. This allows one to cope with the lack of smoothness of structures appearing in quantum mechanical problems while using differential geometric techniques. Our techniques also allow for the analysis of problems related to unbounded operators that are not self-adjoint. As an application, the Marsden-Weinstein reduction procedure was employed to map the above-mentioned $ t $-dependent Schrödinger equations onto their projective spaces. We also analyzed other physically and mathematically relevant applications, demonstrating the usefulness of our techniques.</p>

A robust PQ-controlled three-phase SAPF-based SVM and PI anti-windup for power quality improvement

The use of power electronics devices in electrical energy conversion installations has significantly contributed to improving the performance and efficiency of these systems. On the other hand, static converters have contributed to the deterioration of the quality of current and voltage in distribution networks. These converters consume non-sinusoidal currents, and they behave like harmonic current generators. The power factor and overall system efficiency are weakened by these injected harmonics, reactive power, and other issues. Meanwhile, those loads’ harmonic difficulties must be resolved. The research presented in this paper particularly concerns the study of a shunt active power filter (SAPF) intended to compensate for the harmonic currents generated by nonlinear loads and the compensation of reactive energy. The theory of PQ control is the subject of this research. A robust structure is proposed for that purpose. To sustain the DC-link voltage at the desired interval, a robust PI-regulator-based antiwindup is inserted to ensure active power control. Besides, space vector modulation (SVM) is designed to replace classical pulse width modulation (PWM). The principal benefits of this technique are that it supplies a unitary power factor and sinusoidal network current with no requirement for a PWM generator and fewer harmonics. A comparison between the conventional and the proposed control is established to demonstrate the superiority of the PQ-SVM scheme. The comparison mainly concerns the bus voltage as it is the responsible for the whole system stability Expanded simulation results obtained from the transient and steady-state have demonstrated high performance and have confirmed the robustness and effectiveness of the suggested method.