Space Vector Modulation Method Research Articles

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

Four-Leg Inverter Based on Three-Dimensional Space Vector Modulation Method for Desired Output Frequency

Four-Leg Inverter Based on Three-Dimensional Space Vector Modulation Method for Desired Output Frequency

A Novel Common-Mode Voltage Suppression Strategy for Current Source Converter

The problem of common-mode voltage (CMV) in current source converter (CSC) has been concerned with the development and application of CSC, such as in the transformerless motor drive system. Using a common-mode choke is a popular solution to suppressing CMV. The high-frequency harmonics of the CMV can be eliminated by the common-mode filter. However, the low-order harmonics cannot be eliminated effectively, especially at low modulation index, which may cause common-mode resonance and increase the size of the choke. In this paper, a novel virtual space vector modulation (VSVM) method is proposed, which constructs virtual space vectors by the original vectors. The average value of the CMV produced by each virtual vector is zero. The proposed method can reduce the amplitude and third-order harmonic component of the CMV. In addition, the number of switching transitions in a switching sequence of the proposed method is the same as the conventional 5-segment SVM. The suppression effects of different methods on the low-order harmonics of CMV are compared through simulation and experiments, and the effectiveness of the proposed methods is verified.

Predictive Control Scheme With Adaptive Overmodulation for a Five-Leg VSI Driving Dual PMSMs

A dual permanent magnet synchronous motors (PMSMs) system, driven by a five-leg voltage source inverter (VSI), is considered as a feasible option for low-cost and fault tolerance application. The traditional finite-control-set model predictive control (FCS-MPC) schemes without modulator generate heavy computational burden and larger current ripple. In this article, an improved predictive control method with space vector modulation (SVM) scheme is proposed for independent control of dual-motor system. Firstly, the expected voltage vectors (VVs) of dual motors are obtained with deadbeat (DB) solution, which yields a faster dynamic response. Then, in order to reduce current ripple and eliminate candidate voltage vector traversal process, an improved modulator with adaptive overmodulation is adopted to synthesize the expected VVs. The presented SVM method solves the problem caused by the conflicting switching-states demands of common leg from dual PMSMs. Moreover, an extensive comparison is performed among the proposed control method, the existing model-based control methods, and the field-oriented control (FOC) method with proportional-integral (PI) controller. All methods are experimentally carried out in steady state and transient state. The test results indicate that the proposed control scheme with adaptive overmodulation can effectively reduce current ripple, improve voltage utilization, and preserve good dynamic performance.

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.

An Improved Modulation Scheme of Isolated Matrix Converter for Common-Mode Voltage Reduction and DC-Bias Current Mitigation

In this paper, an optimized space vector modulation (SVM) method is proposed for the isolated three-phase matrix-type AC/DC converter, where the four-quadrant operation ability of the bidirectional power switch can be fully used. The primary-side transformer current can be eliminated naturally during zero current vectors without extra switching actions. Therefore, the conduction loss of matrix converter (MC) is reduced and the efficiency can be increased. Moreover, the proposed method can avoid the shoot-through operation in MC, and the common-mode voltage can be mitigated effectively. As the zero current vector is kept with the proposed modulation strategy, the current harmonics will not be increased. Thirdly, both the DC-link inductor current and DC-bias current of high-frequency transformer (HFT) are measured through the secondary-side current of HFT. Therefore, the DC-bias current and the saturation of HFT are avoided by closed-loop control with the proposed modulation strategy. The experiments have been carried on a 1-kW laboratory prototype to verify the validity of the proposed modulation scheme.

Influence of switching sequences on the neutral point voltage balance in a three-level voltage source invertor

BACKGROUND:Ensuring the voltage balance of the neutral point of the DC link within acceptable limits is one of the mandatory requirements during the operation of a three-level autonomous neutral point clamped voltage source inverter. It is known that neutral point voltage imbalance can adversely affect the operation of the inverter and the load at all, lead to the failure of both power switches and capacitors in the DC link. Neutral point voltage imbalance mostly often occurs due to the asymmetry of the nominal values of DC capacitors, inconsistent properties of switching devices, asymmetric three-phase load, and also due to the imperfection of the converter control algorithm.
 AIMS:Selection of the optimal switching sequence that ensures the smallest deviation of the neutral point voltage and the number of switching of power switches in a three-level voltage source inverter.
 METHODS:For an objective comparison of the considered switching sequences and their influence on the neutral point voltage balance, a simulation model of a three-level neutral point clamped voltage source inverter was developed in theMATLAB/Simulinksoftware. To control this inverter, a space vector modulation method was used with three different switching sequences: five-segment, seven-segment and standard.
 RESULTS:The topology of a three-level neutral point clamped voltage source inverter is presented. The experimental dependencies of the neutral point voltage deviation error was taken with a change in the modulation coefficient, the frequency of the fundamental harmonic at the inverter output, and load characteristics for three different switching sequences.
 CONCLUSIONS:In this paper, the influence of the basic vectors and the influence of switching sequences on the neutral point voltage balance are studied. Combinations of states of large and zero basic vectors do not affect the neutral point voltage. For the medium basic vectors, the neutral point voltage can increase or decrease depending on the operating conditions of the inverter. The small basic vectors significantly affect the neutral point voltage. Considering the abovementioned, the seven-segment sequence that ensures both the optimal balance of the neutral point voltage and the level of switching losses should be considered as the best switching sequence for a three-level inverter.

Quasi Z-Source Neutral-Point-Clamped Inverter Using SVM Technique to Eliminate Common Mode Voltage

In recent year, common mode voltage (CMV) elimination methods are considered to improve the reliability of three-level quasi-switched boost T-type inverter (TL-qSBT2I). The space-vector modulation method (SVM) can control the inverter operation to eliminate the CMV. The proposed method applies medium vectors and zero vector to synthesize the reference vector to eliminate CMV while the output voltage is unchanged compared to SinPWM technique. In order to prevent the active vectors and the output voltage from being affected, the shoot-through vector is inserted inside the zero vector. Accordingly, the proposed method not only maintains the CMV elimination advantage of the SVM technique for TL-qSBT2I but also reduces the inductor current ripple and enhances the voltage gain without any topology modification or adding electrical components. Results from simulations and experiments are used to evaluate the efficiency of the suggested strategy. Additionally, by comparing the proposed scheme with the traditional pulse-width modulation technique, the superiority of the proposed scheme is shown.

Topology and Space Vector Modulation Method for the Reduced Switch Count Quasi-Z-Source Three-Level Inverter

This paper proposes the topology and space vector modulation (SVM) method of a reduced switch count (RSC) quasi-Z-source (QZS) three-level inverter, which can realize voltage buck-boost operation by adopting ten power switches. Compared with the QZS three-level T-type inverter, the presented inverter can further reduce the number of power switches. The SVM method for the proposed topology is designed, which introduces a distribution factor to balance the neutral-point voltage (NPV) actively. In addition, the up-shoot-through (UST) and down-shoot-through (DST) states are inserted within the durations of redundant small vectors to boost the dc input voltage, while the normal ac output voltage is not affected. Detailed comparisons of the RSC QZS three-level inverter and the existing impedance-source-based three-level inverters are conducted, and design guidelines and recommendations for selecting different components are given as well. Simulated tests based on MATLAB software and experimental tests based on a hardware-based test rig are conducted to validate the operating performance of the proposed topology and modulation method, which reveal that single-stage power conversion is achieved. Moreover, the NPV balance is actively controlled by using the proposed method.

Flux Weakening Controller Design for Series-Winding Three-Phase PMSM Drive Systems

Series-winding three-phase PMSMs have a higher bus voltage utilization than the conventional three-phase PMSMs with star connection. This topology is suitable for applications with a limited bus voltage. However, the zero-sequence current controller will reduce the bus voltage utilization of the series-winding PMSMs, which causes problems in the flux-weakening controller design. The conventional flux-weakening control algorithms will cause the series-winding PMSMs to enter the overmodulation region early and degrade the performance of the zero-sequence current suppression algorithm. In this paper, a new flux-weakening controller with a dynamic fundamental voltage limit (FW-DFVL) is designed for the series-winding three-phase PMSM traction system. Firstly, the space vector modulation method combines the proposed virtual zero-sequence vectors to realize both the fundamental current generation and the zero-sequence current suppression. The accurate bus voltage utilization in the fundamental current subspace can be derived from the proposed modulation method. Secondly, the gradient descent method generates the flux-weakening d-axis reference current with the dynamic fundamental voltage, which will converge faster than the conventional PI-based flux-weakening control scheme. Thirdly, the flux-weakening controller in the overmodulation region is also designed where the zero-sequence current will no longer be suppressed. The bus voltage utilization is Vdc in this operation mode. Finally, both the simulation and experimental results are utilized to verify the effectiveness of the proposed FW-DFVL, where faster dynamic performance and higher bus utilization are observed.

Single-phase grid-connected power control in dq synchronous reference frame with space vector modulation using FPGA

This paper presents the performance of controlling the active and reactive power of single-phase grid connected inverter by dq synchronous reference frame and space vector modulation (SVM) which is implemented by using field programmable gate array (FPGA) due to the flexibility they offer in comparison to other digital signal processors, hence it become the standard instruments for implementing various types of pulse width modulation (PWM) digital signal processors (DSPs). The SVM method has used because of its superiority in terms of harmonic distortion, switching losses and utilization of direct current (DC) bus. The synchronization is achieved by using second order generalized integrator (SOGI) due to its simple structure, certain filtering ability and frequency adaptability, in which the phase locked loop (PLL) ensures high performance for single-phase inverter. The active and reactive inverter current has been controlled and decoupled from each other and the dynamic response has been improved and became fast with proper feed-forward and decoupling grid voltage term. The system has simulated by MATLAB and the result shows robust control of injected grid current, active and reactive power control and DC link voltage control.

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.

Synchronous Multi-Zone Modulation for Control of Inverter-Based Power Electronic Systems: Overview of Recent Research

This publication provides a brief overview of the results of recent research works by the author in the field of power electronics, carried out and published mainly in 2019–2021, and awarded with the Premium “Boris Lazarenko” of the Academy of Sciences of Moldova in the field of engineering. The methodological basis of those investigations is an original alternative method of the synchronous multi-zone space-vector modulation of signals of voltage source inverters as the main workhorses of adjustable speed electric drives and renewable energy systems. Therefore, basic strategies, schemes, and algorithms of synchronous multi-zone modulation have been further developed, modernized, modified, and disseminated for the control of novel promising topologies of power conversion systems for variable speed drives and for photovoltaic installations. It is shown that the developed schemes and algorithms of the synchronous space-vector modulation applied for control of inverter-based systems provide continuous synchronization and symmetry of the basic voltage waveforms of systems during the whole control range. It provides minimization of even harmonics and undesirable subharmonics (of the fundamental frequency) in spectra of the basic voltages of systems, leading to reducing the losses in the systems and to increasing their efficiency. Based on a comparative analysis of the integral spectral characteristics of the phase voltage of the systems, recommendations are formulated for the rational choice of schemes and algorithms of the synchronous space-vector modulation for the relevant installations, depending on the modes of their operation.

Type-1 and type-2 fuzzy logic-based space vector modulation for two-level inverter fed induction motor

Two-level inverter control with type-1 and type-2 fuzzy logic-based space vector pulse-width modulation (PWM) method for induction motor drive (IMD) is presented in this paper. A new sampling time independent strategy with type-1 and type-2 fuzzy based methods are used in generating three phase duty ratios which are directly obtained without mathematical equations. The conventional method of space vector modulation (SVM) produces the duty ratios for the inverter which are sampling time dependent. However, in type-1 and type-2 fuzzy based space vector PWM algorithms, the three phases duty ratios generated are sampling time independent and with a new integrated dead-time insertion in SVM itself, can be implemented practically for any switching frequency. As the rule-base for Mamdani non-singleton interval type-1 and type-2 fuzzy inference systems are designed manually, with the expert knowledge of conventional space vector PWM, the duty ratios of the inverter are generated such that the performance of the IMD is improved. The simulation studies for aforementioned cases is performed in matrix laboratory (MATLAB) and experimental validation for the proposed space vector PWM algorithms is validated using real-time sacraetheologiae magister (STM) hardware with STM32F429I Cortex M4 processor for a 1 hp IMD.

A Compensation Component Injection Method Based on a Hybrid Modulation for Minimizing the Neutral-Point Voltage Oscillations in a Five-Level Flying Capacitor Rectifier

Neutral-point (NP) voltage oscillating is an inherent problem for multilevel converters with split dc-link capacitors. In this article, a compensation component injection method based on a hybrid modulation for minimizing the NP voltage oscillations in a five-level flying capacitor rectifier is proposed. In specific, the equivalent modulation waves are first obtained by adopting an existing simplified space-vector modulation method. And a hybrid modulation which gives both the same optimal harmonic performance as phase-disposition pulse width modulation (PWM) and the same superiority of flying capacitor voltage regulation as phase-shifted PWM is adopted. Meanwhile, the solved optimal compensation component in each subsector is injected to make the average NP current equal to zero for minimizing the NP voltage oscillations. Simulations and experiments were conducted to verify the performance of the proposed compensation method based on the hybrid modulation.

Modulation Technique for Modified Active Quasi-Z-Source Inverter with Common-Mode Voltage Reduction

In Z-source topologies, a high-amplitude common-mode voltage can occur when shoot-through states are inserted. In this study, a new space vector pulse-width modulation for an active quasi-Z-source topology is proposed to operate at a high modulation index and reduce the common-mode voltage to one-third of the DC-link voltage. Moreover, the quality of the output voltage is improved by operation with a high modulation index and decreasing the switching loss of the H-bridge switches. The detailed operating principles of the active quasi-Z-source topology using the proposed space vector modulation (SVM) method are presented. A simulation model was built, and an experimental prototype was verified to correct the theoretical analysis.

Evaluation of SVM modulation methods for indirect two-level three-phase frequency converter and direct frequency converter

In current practice, indirectly structured frequency converters are popular because of the simple switch and control circuit diagram, and pulse width modulation (PWM) can be used to control the semiconductor switches. The PWM method has the advantage of a simple control circuit but has large switching losses and generates a common-mode voltage that causes motor damage. The development of the space vector modulation (SVM) method takes advantage of the PWM method, reducing the switching loss of the switches and reducing the harmonic at the output of the inverter. With direct converters, there are many types depending on the circuit structure and semiconductor key structure, including matrix frequency converters which are widely studied. The classical modulation method according to the duty-cycle matrix approach for matrix converter has disadvantages such as complex computational algorithms, which require many trigonometric calculations. Based on the PWM and SVM modulation algorithms for indirect converters, a space vector modulation method for matrix converters will be developed. Compared with the indirect converter, the SVM modulation method for the matrix converter will be based on two separate modulation principles: control the input current vector and control the output voltage vector. The relationship between current and voltage at the converter input is closely related to the voltage and current at the output. The relationship between current and voltage at the converter input is closely related to the voltage and current at the output. Make sure at the input of the converter, the power factor cosφ = 1 and can be adjusted, it has the quality of sine input and outputs current and the exchange power in two directions.

Finite Set Model Predictive Control of a Dual-Motor Torque Synchronization System Fed by an Indirect Matrix Converter

In the dual-motor torque synchronization system fed by an indirect matrix converter (IMC), a finite set model predictive control (FCS-MPC) strategy based on a standard quadratic cost function was proposed to solve the open-loop problem of the torque synchronization error in a traditional closed-loop control strategy. Through the unified modeling of a dual-motor system, the torque synchronization error as a new state variable was involved in the switching state selection of the inverter stages, and the space vector modulation method was still used in the rectifier stage. At the same time, based on the unified prediction model, the auxiliary diagonal matrix was constructed, and the weight coefficients were solved offline by using the Lyapunov stability theory to ensure the convergence of each error term in the continuous control period. The proposed FCS-MPC strategy not only solves the problem of weight coefficient setting, but also makes it possible for a multi-motor synchronization system to expand the number of motors. The simulation and experimental results verified the effectiveness and feasibility of the control strategy. In addition, the proposed FCS-MPC strategy can ensure good torque tracking performance and synchronization performance of each motor.

A Modified SVM Strategy for Single-Phase Cascaded Photovoltaic Inverter

The DC voltage imbalance of a single-phase cascaded photovoltaic inverter will decrease the quality of output voltage. The general modulation method needs to add power balance control to restrain the imbalance and make the control system complicated. To address the issue, a modified Space Vector Modulation (SVM) method is presented in this paper. The modulation method combines the DC voltage control of each unit with the modulation method to achieve DC voltage control of each unit in vector selection, eliminating the need for additional power balance control, thereby simplifying the control system. The modified space vector modulation can not only make the DC voltage rapidly track the DC voltage instruction of each cell through vector selection but also ensure the quality of output voltage waveform when the DC voltage of each cell is imbalanced. The effectiveness of the modified SVM method is verified, and the simulation model has built by using MATLAB/Simulink.

Comparative Analysis of Control Methods with Model Reference Adaptive System Estimators of a Seven-Phase Induction Motor with Encoder Failure

This article presents a comparative analysis of the direct torque control with space vector modulation method for seven-phase squirrel-cage induction motor during the encoder failure. The direct torque control with space vector modulation method with model reference adaptive system with current model and current estimator and model reference adaptive system—flux based estimator applied in the control loop of the motor speed have been analyzed. The mathematical model of the seven-phase induction motor and model reference adaptive system-type estimators have been described. The method of space vector modulation applied to the seven-phase voltage source inverter, controlled seven-phase induction motor, has been described. The operation of direct torque control with space vector modulation has been verified via simulation tests, and the results of performed simulation studies have been analyzed and presented. The authors’ original contribution and work novelty includes comparison studies of the performance of the direct torque control method with space vector modulation of a seven-phase induction motor with two estimators: model reference adaptive system—flux based estimator and the novel model reference adaptive system with current model and current estimator.