Simplified Space Vector Research Articles

A Simplified Space Vector Modulation in abc Coordinate for Four-Leg Current Source Inverters

A Simplified Space Vector Modulation in abc Coordinate for Four-Leg Current Source Inverters

A Simplified Space Vector Pulse Width Modulation Strategy for NPC Six-Phase Three-Level Inverter Considering Neutral-Point Potential Balancing

A Simplified Space Vector Pulse Width Modulation Strategy for NPC Six-Phase Three-Level Inverter Considering Neutral-Point Potential Balancing

A simplified space vector modulation for the single-phase active power decoupling quasi-Z-source inverter

The double-line frequency ripple power of the single-phase quasi-Z source inverter (qZSI) will result in a large designed qZS impedance on the dc side, which can be greatly reduced by the coupled-type active power decoupling (APD) method. However, the traditional sinusoidal pulse width modulation (SPWM) for the APD-qZSI needs extravagant APD storage capacitance and may cause abnormal operation under low load conditions. Classical space vector modulation (SVM) has higher flexibility and dc-link voltage utilization, but it cannot be directly applied to the APD-qZSI. In this paper, a simplified SVM method for the coupled-type APD-qZSI is proposed, where the switching time sequence is transformed to carrier-based pulse width modulation, so the shoot-through control of the qZSI is easy to implement. Next, the passive component parameters and normal operation range of the traditional SPWM and the proposed SVM are analyzed and compared. The proposed SVM has a smaller APD storage capacitance but a slightly larger ac side filter inductance. In addition, the decreased current of the APD branch under SVM can help suppress the abnormal operation of the inverter, so the APD-qZSI can operate at a lower load condition. Finally, experimental results validate the effectiveness and superiority of the proposed SVM method.

Open-Circuit Fault-Tolerant Control of a Six-Phase Asymmetric Permanent Magnet Synchronous Motor Drive System

One innovative composite fault-tolerant control tactic is presented for the reliable operation of a power transmission system, which consists of both an asymmetric six-phase permanent magnet synchronous motor (PMSM) and a T-type mid-point clamp type (T-NPC) three-level inverter. First, in order to inherit the better harmonic property of simplified space vector modulation (SVM) and the rapid dynamic capability of direct torque control (DTC), the SVM-DTC control scheme was determined, and the harmonic electric current suppression unit was added to the basic control scheme to obtain good harmonic electric current suppression. In addition, a strategy for open-circuit fault-tolerant control under the SVM-DTC scheme was designed by analyzing the mutual influence between the stator flux linkage and the stator voltage of each phase under an open-circuit fault. Finally, the PMSM drive system principle prototype was tested. By comparing the waveforms of output torque and current of each phase before and after fault tolerance, it shows that the large torque fluctuation (±5%) before fault tolerance was suppressed to ±2% and smoothed out, verifying the effectiveness of fault tolerance control.

Low Computational Burden Predictive Direct Power Control of Quasi Z-Source Inverter for Grid-Tied PV Applications

This paper proposes a simplified predictive direct power control for the grid-tied quasi Z-source inverter. The proposed control implements a model predictive control structure to achieve the maximum obtainable power from the collected PV source. The power delivered to the grid is managed to compensate for the reactive power and, as needed, to ensure the grid’s stability. A predictive power model for a quasi Z-source inverter is developed in which the proposed control can operate with a fixed switching frequency without a weighting factor. The simplified space vector modulation uses the three appropriate switching vectors that are selected and applied using precalculated switching times during each switching period, in which the required switching vectors are determined only from one sector in the space vector diagram, taking all of the information of the other sectors, which leads to reducing the computational burden. Simulation results and comparative study are used to confirm the proposed control performance for the grid-tied quasi Z-source inverter capable of tracking and generating the maximum power from PV with fast-tracking dynamics, ensuring the ac voltage desired, and better tracking of the active and reactive power reference with the lowest power ripple. The grid current harmonics were tested and conformed to the IEEE-519 standard. Additionally, the proposed simplified PDPC is experimentally validated using the Hardware-in-the-Loop emulator and the C2000TM-microcontroller-LaunchPadXL TMS320F28379D kit, establishing the usability and good result of our proposed control approach in terms of requirements.

A simplified space vector pulse width modulation method for a three‐level four‐leg inverter considering the neutral point potential balance

AbstractThis paper presents a simple three‐dimensional space vector modulation method in ghγ coordinates for a three‐level four‐leg neutral‐point‐clamped inverter. The idea uses redundant vectors as centre points to establish two‐level space vector diagrams simplifying the original space, the first sector of which is designated as subspaces, where a modulation process is implemented. The duty cycle and all possible switching sequences in a tetrahedron can be calculated automatically without manual storage and can avoid a full‐scale search process. Additionally, the neutral point potential can be balanced by three types of charge through cancellation. Such features enable the inverter to demonstrate good performance under closed‐loop control. Moreover, the proposed method can be applied to a multilevel inverter. Simulation and experimental results demonstrate the effectiveness of the proposed concept.

Unified Strategy for Fault-Tolerant Operation of MMC with Multiple SMs Failure Based on SMs Grouping Management

Modular multilevel converter (MMC) is distinguished by its modularity. In order to improve its reliability and avoid unscheduled maintenance, it requires the MMC to continue operating even though some of its submodules (SMs) have failed. In this paper, a grouping management method of SMs in MMC is first presented where every six SMs are conceptually grouped into a virtual subunit (SU), and on this basis, a simplified space vector modulation (SVM) implementation is developed. Then, the fault-tolerant solutions are proposed by investigating the post-fault operation of the MMC based on the virtual SU concept. It is analyzed that the SU failures can be categorized into three basic types, according to the phase where the failed SMs are located, and also multiple SM failures can be decomposed into one or multiple basic fault types. In this way, the fault-tolerant solutions are unified regardless of the number of faulty SMs. Further, the sorting capacitor voltage control is combined into the proposed methods to balance all of the SM capacitor voltages. With the proposed fault-tolerant method, the amplitude and THD of the line voltages are almost unchanged under fault conditions when compared with normal operations. The simulation and experiment verify the propositions.

A Simple SVM Technique on Three-Phase MPUC7 Inverter for Solar Photovoltaic System

In This paper, a simple single-dimension Space Vector Modulation (SVM) technique is introduced to implement on three-phase thirteen-level Modified Packed U-Cell (MPUC) inverter for photovoltaic system in which many DC sources are available. The three-phase thirteen-level converter consists of three single-phase seven-level MPUCs that each phase has six switches and two isolated DC sources. One major advantage of proposed method is to produce an output voltage with nearly constant amplitude in desired range in case of input DC voltage fluctuations, which is common in renewable sources like Photovoltaic Systems (PV). On the other hand, the conventional Pulse Width Modulation (PWM) strategies do not have such capability. Thus, the converter behavior is investigated for the proposed control method and Level Shift PWM (LS-PWM) and it is shown that the LS-PWM method does not function properly when the DC voltage varies. In order to produce an output voltage with seven equal levels, which results in reduction of the switching losses and Total Harmonic Distortion (THD), it is necessary to trigger switches in proper way. Consequently, two switching patterns are introduced and the significant decrease in power loss due to the second switching pattern is shown. Furthermore, it is investigated that in three-phase mode, the 3rd order line-voltage harmonics are eliminated well and the voltage and current THD are further improved by the proposed method. To validate the proposed SVM technique, MATLAB Simulink simulation results are presented and a comparative analysis is done between the proposed method and LS-PWM.

A Simplified Space Vector Pulse Width Modulation Algorithm of a High-Speed Permanent Magnet Synchronous Machine Drive for a Flywheel Energy Storage System

A space vector pulse width modulation (SVPWM) algorithm is an important part of the permanent magnet synchronous machine (PMSM) drive to achieve direct current (DC) to alternating current (AC) conversion. The execution of the conventional SVPWM algorithm is a complex process which will limit the sampling frequency of the high-speed PMSM drive. Low sampling frequency will cause high current total harmonic distortion (THD) and eddy current loss. To increase the sampling frequency, this paper proposes a novel simplified SVPWM algorithm. The proposed SVPWM algorithm turns the vector composition problem of the conventional SVPWM algorithm into an optimization problem of the dwell time of the basic vector. The proposed SVPWM algorithm has an optimal vector dwell time (OVDT). The dwell time of the basic vector can be directly calculated by solving the optimization problem. The proposed SVPWM algorithm does not need sector identification compared to the conventional algorithm. The experiments of the proposed SVPWM algorithm are performed in a high-speed PMSM drive of a flywheel energy storage system (FESS). Compared to the conventional SVPWM algorithm, the execution time of the proposed SVPWM algorithm is reduced by 38%. By using the proposed SVPWM algorithm, the sampling frequency can be increased from 33 kHz to 40 kHz. With the higher sampling frequency, the current THD is reduced by 25.6%. The effectiveness of the proposed simplified SVPWM algorithm is verified experimentally.

Simplified Super Twisting Sliding Mode Approaches of the Double-Powered Induction Generator-Based Multi-Rotor Wind Turbine System

This work proposes a new indirect filed-oriented control (IFOC) scheme for double-powered induction generators (DPIGs) in multi-rotor wind turbine systems (MRWTS). The IFOC strategy is characterized by its simplicity, ease of use, and fast dynamic speed. However, there are drawbacks to this method. Among its disadvantages is the presence of ripples in the level of torque, active power, and current. In addition, the total harmonic distortion (THD) value of the electric current is higher compared to the direct torque control method. In order to overcome these shortcomings and in terms of improving the effectiveness and performance of this method, a new algorithm is proposed for the super twisting algorithm (STA). In this work, a new STA method called simplified STA (SSTA) algorithm is proposed and applied to the traditional IFOC strategy in order to reduce the ripples of torque, current, and active power. On the other hand, the inverter of the DPIG is controlled by using a five-level fuzzy simplified space vector modulation (FSSVM) technique to obtain a signal at the inverter output of a fixed frequency. The results obtained from this proposed IFOC-SSTA method with FSSVM strategy are compared with the classical IFOC method which uses the classical controller based on a proportional-integral (PI) controller. The proposed method is achieved using the Matlab/Simulink software, where a generator with a large capacity of 1.5 megawatts is used. The generator is placed in a multi-rotor electric power generation system. On the other hand, the two methods are compared in terms of ripple ratio, dynamic response, durability, and total harmonic distortion (THD) value of the electric current. Through the results obtained from this work, the proposed method based on SSTA provided better results in terms of ripple ratio, response dynamic, and even THD value compared to the classical method, and this shows the robustness of the proposed method in improving the performance and efficiency of the generator in the multi-rotor wind system.

A Simplified Space Vector Pulse Density Modulation Scheme Without Coordinate Transformation and Sector Identification

A simplified space vector pulse density modulation (SVPDM) scheme for any odd-level inverter-based induction motor drive is proposed in this article. The control strategy uses three sigma delta modulators, wherein the reference space vector is vector quantized to generate the output switching vectors. The switching vectors for the inverters are derived without coordinate transformation and sector identification in this scheme, making the algorithm computationally simpler. The proposed SVPDM scheme retains the advantages over SVPWM scheme such as freedom from minimum pulsewidth problem, improved spectral features, convenience of digital implementation, avoidance of complex timing calculations, and less annoying acoustic noise pattern of motor. The scheme is experimentally verified for an open-end winding-based five-level induction motor drive. The performance of the proposed scheme is compared with the deterministic and nondeterministic schemes and the results obtained substantiate the efficiency of proposed scheme.

Design and implementation of three-level T-type inverter based on simplified SVPWM using cost-effective STM32F4 board

This paper investigates the design and validation of simplified space vector pulse width modulation (SVPWM) as a switching control for a three-phase three-level T-type inverter using STM32F4 board interfaced with MATLAB/Simulink environment. Usually, the SVPWM algorithm implemented using either DSP card or Dspace platform, which affects the cost of the system. On the contrary, the proposed algorithm offers a great reduction of computations compared with the conventional one, which grants an easy digital implementation. Thanks to the geometrical symmetry of six sectors, in which exists a close relationship between on-time calculations and on-time arrangement of the switching states. This can be exploited for the remaining sectors based on a single computation that relies on the first sector only. The proposed algorithm has been validated in both simulation and experimental tests. The results show the ability and the flexibility of using the STM32F4 board to drive a three-level T-type inverter.

Design and implementation of three-level T-type inverter based on simplified SVPWM using cost-effective STM32F4 board

This paper investigates the design and validation of simplified space vector pulse width modulation (SVPWM) as a switching control for a three-phase three-level T-type inverter using STM32F4 board interfaced with MATLAB/Simulink environment. Usually, the SVPWM algorithm implemented using either DSP card or Dspace platform, which affects the cost of the system. On the contrary, the proposed algorithm offers a great reduction of computations compared with the conventional one, which grants an easy digital implementation. Thanks to the geometrical symmetry of six sectors, in which exists a close relationship between on-time calculations and on-time arrangement of the switching states. This can be exploited for the remaining sectors based on a single computation that relies on the first sector only. The proposed algorithm has been validated in both simulation and experimental tests. The results show the ability and the flexibility of using the STM32F4 board to drive a three-level T-type inverter.

A Simple Space Vector Modulation Method With DC-Link Voltage Balancing and Reduced Common-Mode Voltage Strategy for a Three-Level T-Type Quasi-Z Source Inverter

Single-stage converters based on an impedance source (IS) network merged with a multilevel inverter remain a trending research topic, from both the topological and control perspectives, because of their potential in applications involving renewable energy. This paper presents a new, simplified space vector pulse-width modulation (SVPWM) for a three-phase three-level T-type quasi-impedance source inverter (3L-T-type qZSI). The benefits of the proposed modulation strategy include functionalities, such as boosting the input voltage and controlling the neutral-point (NP) voltage using the redundant small vectors, to mitigate the inner capacitors voltages imbalance. The proposed SVPWM guarantees a minimum common-mode voltage while preserving a very simple implementation, thus reducing the complex computations and cascaded proportional-integral (PI) control loops of the conventional SVPWM methods. The proposed algorithm can be applied to different multilevel inverter configurations combined with an IS network. A comprehensive simulation study and experimental results demonstrated the good performance of the proposed control method for dynamic response and imbalance conditions.

A Novel Volt-Second Self-Balancing SVPWM Scheme to Eliminate Steady-State DC Bias for a Three-Phase Isolated AC–DC Matrix Converter

For a three-phase isolated ac-dc matrix converter, the slight volt-second imbalance caused by variable input voltage is an inherent defect and has been neglected in most PWM schemes. The analysis in this paper shows that the imbalance lies in a single direction during the entire input cycle, and it might generate a large dc bias to severely decrease the efficiency of the steady-state operation. Therefore, the imbalance phenomenon is first investigated, and the generation mechanism of the steady-state dc bias is derived in detail. To eliminate such a dc bias, a novel transformer primary-side voltage pulse is originally defined. Based on the special crisscrossing operation mode with the above pulse, a simple but effective four-segment space vector PWM (4S-SVPWM) scheme is proposed. Compared with the conventional more-segment SVPWM schemes, the novel 4S-SVPWM scheme can achieve volt-second self-balancing without auxiliary methods, as well as a 1/2 reduction in the common-mode voltage (CMV) peak value and a 1/3 reduction in the switching actions. The overall efficiency and power density of the converter are greatly improved. Finally, an experimental prototype is built to validate the correctness and effectiveness of the novel scheme.

A Simplified SVM-Based Fault-Tolerant Strategy for Cascaded H-Bridge Multilevel Converters

The cascaded H-bridge multilevel converter (CHMC) is a promising topology for medium- and high-voltage applications, as it features modularity and scalability. In this letter, a simplified space vector modulation (SVM)-based reconfiguration strategy is proposed to enable fault-tolerant operation of a CHMC. Assuming that the faulty power cells are bypassed, the proposed strategy decomposes the asymmetric CHMC into two parts, i.e., healthy part with healthy modules and unhealthy part with faulty modules. Consequently, the basic reference vector (BRV) and the remainder reference vector (RRV) are generated from the reference vector (RV) to achieve balanced line-to-line voltages and currents with optimized harmonic performance. The proposed strategy can be easily implemented online. Performance and effectiveness of the proposed strategy is verified by experimental results.

Grid interfaced solar water pumping system with improved space vector modulated direct torque control

Abstract In this paper, a new simplified space vector modulated direct torque control (SVM-DTC) method for induction motor drive is used in solar water pumping system for agricultural and irrigational loads that have smart sharing of power between grid and solar photovoltaic array is proposed. A boost converter with variable step size MPPT that automatically tracks the next step size to maximize the power output is used. Four distinct types of modes with grid operative system and SPV array are proposed such that the unceasing performance of pump is guaranteed and surfeit power is fed back to the grid. The proposed system is modeled in Matlab/Simulink, and the plausibility and novelty of the system in amalgamating the SPV source into the grid can be verified by the results.

Design and Validation of a Generalized Multilevel Inverter with Simplified Switching Technique

—This paper proposes a generalized 3-phase cascaded multilevel inverter (CMLI) along with a simplified space vector pulse width modulation (SVPWM) based on 2-level inverter (2LI) topology. While conventional cascaded H-bridge inverters (CHBIs) call for a number of DC sources which increase the cost and complexity of their implementation, the proposed CMLI requires one DC source only. On the other hand, the complexity of SVPWM lies in the switching diagram that consists of a large number of triangles comprising uneven numbers of switching vectors. The generalized 3-phase CMLI proposed in this paper is aimed at reducing the number of switching vectors of each triangle. The hypothesis of the proposed CMLI-SVPWM is firstly illustrated through extensive simulation analysis using MATLAB/SIMULINK software. Feasibility of the proposed inverter is then validated through experimental measurements on a hardware prototype. Results reveal the superiority of the proposed inverter over existing ones in terms of the quality of the output voltage and current waveforms and the overall efficiency.

A Novel Low Common-Mode Voltage Modulation Strategy for ANPC-5L Inverter

In order to suppress the leakage current of the active neutral point clamed five-level (ANPC-5L) inverter, this paper proposes a novel low common-mode voltage (CMV) modulation strategy based on the space vector modulation thought. Only the 55 voltage vectors with low CMV amplitude instead of all 125 voltage vectors are utilized. The CMV amplitude is suppressed to one-twelfth of the DC bus voltage (Vdc). In the simplified five-level space vector diagram, “obtuse triangle” synthesis principle is used to control the CMV changes twice in each carrier cycle, and get lower output current total harmonic distortion (THD). According to the vector thought, a carrier implementation method based on zero sequence voltage injection and carrier splitting is proposed. This method simplifies the calculation and is easy to implement.Simulation results prove the correctness and feasibility of this low CMV modulation strategy.

Fast and simple space vector modulation method for multilevel converters

This study proposes a simplified space vector pulse-width modulation (SVPWM) method for multilevel converters. To avoid unnecessary coordination transformations, firstly, a further derivation is conducted on the basis of the 60° coordinate transformation. Then, all the nearest three vectors (NTVs), duty cycles and optimal switching sequence within one switching period can be identified through a simple comparison of three-phase modulation waves. To further reduce the switching frequency, detailed steps to achieve the minimum number of transitions among different NTVs are constructed. Combined with the optimal switching sequence within one switching period, the minimum number of transitions within a fundamental period can be achieved easily. Finally, a thorough discussion is conducted to simplify the procedure further and the flowchart for the proposed SVPWM is also presented. Compared with the previous methods, the proposed method does not require any iterative calculation or coordinate transformation. To the best of the authors' knowledge, the calculation amount is reduced by almost seven times compared with the methods proposed. In addition, the switching frequency and total harmonic distortions remain at the same level without any deterioration. Finally, the simulation and experiment for modular multilevel converter are performed to verify the correctness and efficiency of the proposed method.