Vector Pulse Width Modulation Method Research Articles

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 space vector pulse width modulation method for switched reluctance motor driven by full bridge power converter

AbstractThis study proposes a space vector pulse width modulation (SVPWM) driving method for the switched reluctance motor (SRM), which enables the use of a standard full‐bridge power converter to drive a three‐phase SRM with a ring structure, in place of the traditional asymmetric H‐bridge (AHB). Based on this driving topology, the SVPWM approach is employed to drive the SRM, and its performance is compared with that of the conventional SRM driving method utilising the AHB. The findings indicate that the SVPWM method can effectively reduce torque ripple in the SRM. Moreover, the experimental validation performed to verify the proposed driving topology and method yields results that closely align with the simulated outcomes.

Novel SVPWM Method Based on Zero-Voltage Notch of Resonant DC-Link Inverter

In order to decrease the switching loss of the auxiliary circuit of the resonant DC link (RDCL) inverter and improve the voltage utilization and system efficiency, this paper presents a new space vector pulse width modulation (SVPWM) method based on the zero-voltage notch of the resonant DC link inverter. This resonant DC link inverter reduces the current stress in the main circuit by paralleling auxiliary switch. And this method makes the operation of the auxiliary resonant circuit (ARC) less frequent, thus reducing the losses of the ARC and therefore improving the system efficiency. At the same time, this method analyzes and compensates for the missing voltage vectors based on the ideal output voltage, so that the inverter output voltage vector under this modulation is the same as the ideal SVPWM output voltage vector. Compared with the original modulation of RDCL inverter, this method does not change the switching sequence, the switching times, and the action time of the vector, while reducing the switching ripple. The effectiveness and feasibility of the modulation strategy is verified in the paper through theoretical analysis as well as experiments.

Research on control system for improving the grid-connected efficiency of small hydropower

Aiming at the problem of low efficiency at low flow in small hydropower stations, a permanent magnet direct-drive hydropower generation control system based on dual PWM converters is proposed to realize wide-range variable-speed constant-frequency hydropower generation of hydraulic turbine units and improve the comprehensive power generation efficiency of small hydropower stations. In this control system, the hydraulic turbine is coaxially connected to the permanent magnet synchronous generator(PMSG) through the flywheel, and the power grid is connected by back-to-back dual PWM converters, and the bidirectional energy flow is realized by the voltage space vector pulse width modulation method. The generator-side converter controls the rotating speed of hydraulic turbine units and tracks the optimal speed point of the hydraulic turbine units in real time to realize the maximum power output of hydraulic turbine units. The grid-side converter adopts active power and reactive power decomposition control method to stabilize the DC bus voltage and provide the reactive power required by the grid. Finally, the effectiveness of the proposed control system was proved by comparative experiments in a 400V/200kW/428rpm small hydropower station.

An optimization method for reducing the voltage fluctuation of the floating‐capacitor in ANPC five‐level inverter

AbstractThe excessive fluctuation of the floating capacitance's (FCs) voltage affects the output performance and output power of the 3P‐5L‐ANPC converter. In order to minimize the fluctuation of the FCs voltage, an optimization control method based on zero‐sequence voltage (ZSV) injection is proposed. The method takes reducing the maximum amplitude of the voltage fluctuation of the three‐phase floating capacitor as the control target. Firstly, the mathematical equation between the modulation voltage and the voltage fluctuation of the FCs are established, and then the maximum fluctuation amplitude of the FCs voltage is obtained by using the established mathematical equations. Secondly, the range of ZSV injection is determined according to the conditions such as the control of neutral point voltage and the limitation of high‐phase voltage leaps. Finally, the equations of the maximum amplitude in the voltage fluctuation of the three‐phase FCs are established, and the ZSV with the minimum voltage amplitude fluctuation of the FCs is obtained within the effective range of the ZSV injection. Compared with the traditional shifted pulse width modulation (SPWM)/space vector pulse width modulation (SVPWM) method, the proposed method can effectively reduce the fluctuation of the FC voltage by 50%. Simulation and experimental results are presented to verify the effectiveness of the proposed method.

PSO based Solar PV system for SVPWM Controlled Induction Motor for Agricultural Applications

Nowadays, renewable energy sources play a major role in agricultural applications. The recommended Particle Swarm Optimization (PSO) algorithm with DC-DC converter supports in refining the output voltage. This is beneficial however since the partial shading condition of PSO technique has high output power with fewer searching steps of MPPT. The objective of this work is to propose a PSO based boost converter using Space Vector Pulse Width Modulation (SVPWM) method. PSO has been anticipated to track the Global Maximum Point (GMP) under the partial shading condition. The welfares of the SVPWM technique are fixed switching frequency and lower harmonic content. The centrifugal pump used in agricultural system is obsessed by SVPWM controlled three-phase induction motor. The extent of the motor as well as the photovoltaic array evaluations are certain as the water could be pumped out even at temperature fluctuations and irradiation levels. The efficacy of the proposed design is observed under the MATLAB/SIMULINK.

A Novel Junction Temperature Balance Control Method for Typical Three-Phase Converters Based on a Hybrid Modulation Strategy

Unbalanced junction temperature ( <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">T_j</i> ) distribution of a bridge leg can accelerate the development of aging defects and reduce the lifetime of the converter. Therefore, <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">T_j</i> balance control (TBC) is important for high reliability operation. Conventional TBC methods based on parameter adjustment cannot avoid reducing the efficiency and the power quality of converters. Other TBC methods can only be used in some switching devices in special packages. In this article, a novel TBC method is proposed based on a hybrid modulation strategy. First, temperature distributions in three space vector pulse width modulation (SVM) methods are analyzed theoretically and verified by experiments. This is the basis for <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">T_j</i> balancing. Second, a hybrid modulation strategy is proposed based on the bang-bang control. It can switch from these three SVMs adaptively according to the maximum <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">T_j</i> difference. In this way, the <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">T_j</i> difference of a bridge leg can be controlled to a fixed range. Third, the effectiveness of the proposed TBC method is verified by experiments. The <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">T_j</i> difference caused by unbalanced aging can be controlled from over 20 °C to 3 °C. Compared with conventional TBC methods, the proposed method has almost no effect on the efficiency and output power quality of the converter.

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.

Decentralized space vector pulse width modulation method for multilevel single-phase half bridge converters

This study presents a space vector pulse width modulation (PWM) method for a multilevel single-phase decentralized power converter (DPC) called MSPDPC. The proposed model is built by connecting half-bridge cells in series. The output voltage can be adjusted according to demand by adding or subtracting cells. Cells use communication protocols to transmit and receive information with two neighboring cells. The received data contains information for the decentralized space vector pulse width modulation (DSVPWM) method proposed in this paper. In the proposed DSVPWM method, cells set up links to exchange information such as cell position, total cells in a phase, reference voltage amplitude, and reference frequency. The PWM control signals of each cell are calculated based on the information received. The study also focuses on evaluating the ability to adjust the switching vector and the corresponding dwell time of the cells when the structure of the DPC changes. The ability to dynamically reconfigure the DPC is a crucial feature that ensures uninterrupted power supply in case of one or several cell failures. The system automatically establishes a new state with the active cells. The proposed configuration and communication method between cells provide very fast configuration times. The load voltage of the DPC is adjusted to 0.5 times the voltage per cell, which allows the modulation voltage amplitude to be adjusted best according to the load requirements. The study used Matlab/Simulink software to review the initial assessments. The proposed model and algorithms will be verified on the Digital Signal Processor (DSP) platform with a 220V/500W load.

Research on error self‐correction complementary non‐zero vector pulse width modulation strategy

AbstractThe DC link single sensor phase current reconstruction method has brought several challenges, which consist of the unobservable area and current zero drift error, where the duration of the effective vector is too short to measure, and current zero drift error leads to reconstruction error. An error self‐correction complementary non‐zero vector pulse width modulation (ESC2N‐PWM) method is proposed. Through the analysis of the DC link sampling principle, the minimum sample time is defined. Then applying complementary non‐zero vectors to replace zero voltage vector, the current sampling window is extended, and the sector boundary unobservable area is eliminated. At the same time, through the dynamic double sampling of the complementary effective voltage vectors, the zero drift of current is self‐detected and self‐corrected. The experimental results show that the reconstruction error of the proposed method is lower than 2.84%, and the current THD is lower than 6.20%.

Experimental Study of F2833x/Texas Ins. for Constructing Speed Controller on a Synchronous Motor Based on SVPWM Method

Microprocessor programming algorithms in electrical inverter drive systems are essential in developing and formulating modern methods in closed control circuits. The microprocessor used in the current research, TMS320f28335, has a high system clock s frequency (150 MHz) that reaches up to, which gives an almost perfect ability to output the three-voltage sinewave generated from the inverter under consideration. Obtaining a sinewave voltage means the lowest possible harmonics (THD) and thus the best performance of the induction motor at starting and dynamic stability. The current research used the directional inclusion method to implement the six inverter switches (IGBTs) mechanism. Mathematical calculations were made for Space Vector Pulse Width Modulation (SVPWM) method, and then the microprocessor was programmed to implement it. The practical board Voltage Source inverter (VSI) was tested extensively

A New Decentralized Space Vector PWM Method for Multilevel Single-Phase Full Bridge Converters

This paper proposes a decentralized control structure and method for a multilevel single-phase power converter using space vector pulse width modulation (SVPWM). The focus of this paper is on the decentralized control structure for the power converter cells that will exchange information with neighboring cells in order to adjust the switching vector and switching time for each cell. In this study, the switching vectors and the corresponding switching times of each cell will be self-determined based on the phase angle of two neighboring cells. Normally, SVPWM applied to the multilevel power converters need complete information about the total cells and cell’s position to build a control algorithm. Meanwhile, a decentralized space vector pulse width modulation (DSVPWM) method is proposed that can be applied to power converters with any number of cells and can be considered as a multilevel SVPWM method. In addition, the decentralized multilevel single-phase power converter has high flexibility with which it is possible to easily adjust the number of active cells, so that the output voltage can be adjusted quickly; this provides the ability to dynamically reconfigure without interrupting the power energy supply process. The proposed control structure and method are effectively verified based on simulation and experimental results. Experimental results are evaluated based on a 9-level single-phase power converter, which has an RL load with rated parameters 220 V/500 W.

Investigation and Experimental Validation of Sideband Harmonic Vibration of IPMSM with and without Skewed Slots for EVs

Due to their advantages of high power density and high efficiency, permanent magnet synchronous machines (PMSMs) are widely used in the field of electric vehicles (EVs). Vibration and noise are important indicators for evaluating the performance of PMSMs, and the skewed slot method is now widely used to mitigate the torque ripple and noise of motors. In the vector control strategy, the space vector pulse width modulation (SVPWM) method produces sideband voltage harmonics with a frequency near the switching frequency. These harmonics act on the magnetic field to generate an excitation force with a frequency near the switching frequency. This paper compares and analyzes the sideband harmonic current and the exciting force of a skewed slot motor and a straight slot motor during steady-state operation. The research results show that the skewed slot method can effectively mitigate the vibration and noise caused by sideband harmonics.

A simplified SVPWM method for cascaded multilevel inverters

A highly popular alternative in medium voltage and high-power applications is multilevel converters because of their superior performance over conventional two-level converters. The most commonly used control methods in the case of multilevel inverters are sine pulse width modulation (SPWM) and space vector pulse width modulation (SVPWM) methods. Among these two control strategies, SVPWM has superior performance over SPWM in terms of DC bus voltage utilization along with a reduction in total harmonic distortion (THD) of line voltages. The classical SVPWM method has various drawbacks such as computational complexity for identifying the location of reference voltage vector, sector identification, region identification, memory requirement to store lookup tables for switching vectors. The novel simplified SVPWM technique is presented for cascaded H-Bridge multilevel inverter (CHBMLI) in this paper. This simplified SVPWM method has overcome the drawbacks of the classical SVPWM method. This new technique has been implemented into a five-level CHBMLI to evaluate performance and also to compare with the SPWM method. The simulation has been performed in MATLAB software.

A Hybrid Method to Eliminate Leakage Current and Balance Neutral Point Voltage for Photovoltaic Three-Level T-Type Inverter

Nowadays, neutral point voltage (NPV) balancing control and leakage current (LC) reduction methods are considered to improve the reliability of transformerless three-level T-type (3LT <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> ) inverter. Medium vector pulse width modulation (MVPWM) method can control the inverter operation to eliminate the LC; however, is powerless to balance the NPV. Alternatively, discontinuous PWM (DPWM) methods can be implemented to balance the NPV. In this article, a hybrid method for transformerless 3LT <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> inverter is proposed to simultaneously minimize the LC and accomplish balancing control in case of NPV unbalancing. The proposed method applies MVPWM switching patterns to eliminate LC while the NPV is balanced. If the NPV becomes unbalanced, it applies specific switching patterns of the DPWM methods as alternative patterns to balance the NPV with minimal LC. Accordingly, the proposed method not only maintains the LC elimination advantage of the MVPWM method but also realizes the NPV balancing capability without any topology modification or adding electrical components. Noteworthy, even the NPV balancing is accomplished with minimal flow of the LC. The proposed method is carrier-based PWM, which shortens execution time and simplifies practical implementation. Experimental tests have been accomplished and results demonstrate the effectiveness of the proposed method on adding the NPV balancing capability with minimal LC to the MVPWM method.

Comparison of voltage source converters and Z-source converters for electric vehicles

Voltage source and current source converters are used in industrial applications as either boost or buck converters for a defined power flow direction. These operational modes limit these converters to be utilized on their own in hybrid and electric vehicle (EV) applications. Z-source (impedance source) converters, on the other hand, have the capability to be operated as buck and boost converters to have a wide range of output levels. The boost ratio of the direct current link voltage of a Z-source converter is set by short-circuiting the phase legs of the converter and defining the overlap duration at each switching period. In order to have the optimum efficiency with the lowest possible total harmonic distortion, a modified space vector pulse width modulation method with an impedance network could be selected for closed-loop control of the quasi-resonant Z-source converter to drive permanent magnet synchronous motors (PMSMs). In this study, closed-loop vector-controlled drive systems built with two-level and three-level boosted voltage source converter topologies and two- and three-level quasi Z-source converters for field-oriented control of a PMSM in EV motor drive applications were compared under constant motor speed–constant load, constant speed–variable load and variable speed–constant load operating conditions.

A novel fast SVPWM method based on two-stage transformation for three-level inverter

Compared with the two-level inverter, the three-level inverter has excellent performance in pressure voltage switching loss and harmonic applied to the fields of the speed regulation and new energy generation. However, the computational complexity of the space vector pulse width modulation (SVPWM) method for multilevel inverter restricts the implementation on low cost microprocessor. This paper proposes a novel fast SVPWM method for three-level inverter to convert the space voltage vector in the three-level space to the two-level by vector subtraction with the central vector. The conduction time of each switch can be computed quickly so that the runtime is reduced significantly. Finally, the experimental results verify the effectiveness and practicability of the new space vector modulation algorithm based on two-stage transformation.

Comparative analysis of switching losses and current ripple of continuous and discontinuous SVPWM strategies for unbalanced two‐phase four‐leg VSI Fed unsymmetrical two‐phase induction motor

This paper presents a comparative analysis of the continuous space vector pulse width modulation and the discontinuous space vector pulse width modulation in terms of the switching losses and current ripple reduction for the unbalanced two-phase four-leg voltage source inverter fed unsymmetrical two-phase induction motor. The main function of both space vector pulse width modulation strategies is to produce unbalanced two-output voltages with constant phase shift of 90° for main and auxiliary windings. The discontinuous space vector pulse width modulation principle is modified from a traditional two-phase four-leg voltage source inverter by placement of the space vectors to alternatively eliminate zero space vector in each switching sequence. As a consequence, the proposed unmodulation region or clamping zone of the discontinuous modulation strategy has 180° all the time. The experimental results illustrate the modulation waveforms of both methods, output voltage spectrum, normalized switching losses, output current ripple and inverter efficiency at high modulation index. The evaluation of the normalized average switching losses and the current ripple of the discontinuous space vector pulse width modulation method can be reduced more than that of the continuous space vector pulse width modulation method.

A novel PWM scheme for grid-tied inverter in micro-grid with enhanced power quality using silicon cells

This paper presents a cost effective solution to reduce harmonics and improved power factor in grid tied inverter by varying the control pulses instead of using hardware components like filtering and multilevel inverter. A two-level inverter is taken for simulation study and a new pulse width modulation method is proposed by tying altered space vector pulse width modulation method and hysteresis current control. This novel scheme provides low harmonic content, improved power factor, enhanced power management, enriched storage and maxim extraction of power. The simulation work of grid-tied inverter integrated with micro-grid is carried out with MATLAB/Simulink 2018 and the performance of the proposed novel pulse width modulation approach is analysed in terms of harmonics content in output current.

DC Voltage Balancing Strategy of a Bipolar-Output Active Rectifier for More Electric Aircraft Based on Zero Vector Redistribution

The ±270 V bipolar dc distribution has become an attractive power supply scheme in more electric aircraft (MEA). In this paper, a dc voltage balancing strategy based on zero vector redistribution (ZVR) is proposed for a three-phase coupled inductor-based bipolar-output active rectifier (TCIBAR) to achieve balanced ±270 V power supply for MEAs. First, the mathematical model of the TCIBAR is developed in the rotating reference frame and the zero-sequence equivalent circuit of the three-phase coupled inductor (TCI) branch is derived. On this basis, the effect mechanism of the zero-sequence voltage is analyzed in balancing the output dc voltages of the TCIBAR. Second, a voltage balancing control scheme is designed to control the zero-sequence voltage and maintain the dc voltage balance of the TCIBAR under unbalanced load condition. Finally, a ZVR - space vector pulse width modulation (ZVR-SVPWM) method is proposed. With the ZVR-SVPWM method, the duration time of zero vectors can be redistributed to modulate the desired zero-sequence voltage for the TCIBAR. The proposed dc voltage balancing strategy for the TCIBAR is implemented on an experimental platform, and the experimental results verify the feasibility and effectiveness of the proposed control scheme and ZVR-SVPWM method.