Research methods of V/F control for matrix converter use direct space vector modulation

Matrix converter (MC) is direct AC to AC converter built on bidirectional switches with more outstanding advantages compared to the indirect AC - DC-AC converter such as power exchange in two directions, allowing regenerative braking performance amount returned grid. However, the modulation method for Matrix converter has the disadvantage of low voltage transmission ratio, current at the input and output current, the voltage of converter has many high-order harmonic components. The paper presents the technique of directly modulating the space vector which will improve the quality of matrix converter such as input and output currents with sine form, power factor input is nearly 1 and can be adjusted. Also, build V/F control method for matrix converter to control three-phase alternating current induction motors. Research results are tested by Matlab & Simulink software

Design and Development of Novel Matrix Converter Performance Enhancement Technique for Induction Motor Drive

Matrix converter is a direct AC-AC converter topology that directly converts energy from an AC source to an AC load without the need of a bulky and limited lifetime energy storage element. Due to the significant advantages offered by matrix converter, such as adjustable power factor, capability of regeneration and high quality sinusoidal input/output waveforms. Matrix converter has been one of the AC–AC topologies that hasreceived extensive research attention for being an alternative to replace traditional AC-DC-AC converters in the variable voltage and variable frequency AC drive applications. In the present paper an indirect space vector modulated matrix converter is proposed. The basic idea of an indirect modulation scheme is to separately apply SVM to the rectification and inversion stages, before combining their switching states to produce the final gating signals. The paper encompasses development of a laboratory prototype of 230V, 250VA three phase to three phase DSP controlled matrix converter fed induction motor drive. The observations and real time testings have been carried out to evaluate and improve the stability of system under various typical abnormal input voltage condition

Development of a direct matrix converter for micro-grid applications

University of Technology Sydney. Faculty of Engineering and Information Technology.Matrix converter is a direct ac-ac converter topology which does not contain a dc-link passive component, unlike conventional ac-ac frequency converters. Electrolytic capacitors which are used as the energy storage component have a limited lifetime. They are also bulky and unreliable at very high temperatures. Matrix converter is able to generate controllable sinusoidal ac outputs regarding magnitude and frequency directly from an ac power supply. The other significant advantages offered by matrix converters are the capability of regeneration and adjustable input power factor. The main objective of this thesis is design, implementation and the stability analysis of the matrix converter for power flow control applications in the context of the microgrids. In this regard, different applications with bidirectional or unidirectional power flow capabilities are considered as the case study. These include using the matrix converter as an interface link between a microgrid and the utility grid, between a variable frequency source such as wind turbine and the microgrid ac bus, and between a variable frequency load such as induction machine and microgrid ac bus. As bidirectional power flow control between the utility grid and the microgrid is significantly affected by the stability issue, the stability analysis has become an essential part of this research. Details of the input filter design are presented due to the considerable effect of the filter components on the system stability. The effects of the system parameters on the matrix converter stability are investigated using the small-signal model of the converter. Two methods of stability improvement using the damping resistor and the digital filter are studied in detail. In order to increase the efficiency of the converter, an optimum solution based on the combination of the damping resistor and the digital filter is suggested, and the performance of the proposed method is analyzed. The operation of the matrix converter as an interface between the utility and a microgrid for bidirectional active and reactive power flow control is studied in detail. To control the active and reactive bidirectional power flows, a vector-oriented control method is used. Two main modulation strategies, the Venturini and space vector modulation, are analyzed and the simulation and experimental results are compared. Due to the better performance of the space vector modulation, this technique is selected for modulation of the designed matrix converter. Different current commutation methods are studied in detail and the simulation and experimental results of four-step semisoft current commutation are presented as the selected commutation method in this work. Furthermore, a comprehensive simulation study is carried out to investigate the operation of the proposed strategies for modulation, protection, stabilisation and bidirectional power flow control of the matrix converter. To validate the proposed stability analysis and numerical simulations, a prototype direct matrix converter has been developed. The simulation results related to each of the research sections are confirmed through the experimental tests

Fuzzy Controller for Matrix Converter System to Improve its Quality of Output

In this paper, Fuzzy Logic controller is developed for ac/ac Matrix Converter. Furthermore, Total Harmonic Distortion is reduced significantly. Space Vector Algorithm is a method to improve power quality of the converter output. But its quality is limited to 86.7%.We are introduced a Cross coupled DQ axis controller to improve power quality. The Matrix Converter is an attractive topology for High voltage transformation ratio. A Matlab / Simulink simulation analysis of the Matrix Converter system is provided. The design and implementation of fuzzy controlled Matrix Converter is described. This AC-AC system is proposed as an effective replacement for the conventional AC-DC-AC system which employs a two-step power conversion.Comment: 11 page

Multilevel Multiphase Feedforward Space-Vector Modulation Technique

Multiphase converters have been applied to an increasing number of industrial applications in recent years. On the other hand, multilevel converters have become a mature technology mainly in medium- and high-power applications. One of the problems of multilevel converters is the dc voltage unbalance of the dc bus. Depending on the loading conditions and the number of levels of the converter, oscillations appear in the dc voltages of the dc link. This paper presents a feedforward modulation technique for multilevel multiphase converters that reduces the distortion under balanced or unbalanced dc conditions. The proposed modulation method can be applied to any multilevel-converter topology with any number of levels and phases. Experimental results are shown in order to validate the proposed feedforward modulation technique.Ministerio de Ciencia e Innovación DPI2009-07004Ministerio de Eduación y Ciencia TEC2007-6187

Conventional Space-Vector Modulation Techniques versus the Single-Phase Modulator for Multilevel Converters

Space-vector modulation is a well-suited technique to be applied to multilevel converters and is an important research focus in the last 25 years. Recently, a single-phase multilevel modulator has been introduced showing its conceptual simplicity and its very low computational cost. In this paper, some of the most conventional multilevel space-vector modulation techniques have been chosen to compare their results with those obtained with single-phase multilevel modulators. The obtained results demonstrate that the single-phase multilevel modulators applied to each phase are equivalent with the chosen wellknown multilevel space-vector modulation techniques. In this way, single-phase multilevel modulators can be applied to a converter with any number of levels and phases avoiding the use of conceptually and mathematically complex space-vector modulation strategies. Analytical calculations and experimental results are shown validating the proposed concepts

New Modulation Technique to Mitigate Common Mode Voltage Effects in Star-Connected Five-Phase AC Drives

Star-connected multiphase AC drives are being considered for electromovility applications such as electromechanical actuators (EMA), where high power density and fault tolerance is demanded. As for three-phase systems, common-mode voltage (CMV) is an issue for multiphase drives. CMV leads to shaft voltages between rotor and stator windings, generating bearing currents which accelerate bearing degradation and produce high electromagnetic interferences (EMI). CMV effects can be mitigated by using appropriate modulation techniques. Thus, this work proposes a new Hybrid PWM algorithm that effectively reduces CMV in five-phase AC electric drives, improving their reliability. All the mathematical background required to understand the proposal, i.e., vector transformations, vector sequences and calculation of analytical expressions for duty cycle determination are detailed. Additionally, practical details that simplify the implementation of the proposal in an FPGA are also included. This technique, HAZSL5M5-PWM, extends the linear range of the AZSL5M5-PWM modulation, providing a full linear range. Simulation results obtained in an accurate multiphase EMA model are provided, showing the validity of the proposed modulation approach.This work has been supported in part by the Government of the Basque Country within the fund for research groups of the Basque University system IT978-16 and in part by the Government of the Basque Country within the research program ELKARTEK as the project ENSOL (KK-2018/00040)

Feed-forward Space Vector Modulation for Single-Phase Multilevel Cascade Converters with any DC voltage ratio

Modulation techniques for multilevel converters can create distorted output voltages and currents if the DC link voltages are unbalanced. This situation can be avoided if the instantaneous DC voltage error is not taken into account in the modulation process. This paper proposes a feed-forward space vector modulation method for a single-phase multilevel cascade converter. Using this modulation technique, the modulated output voltage of the power converter always generates the reference determined by the controller even in worst case voltage unbalance conditions. In addition the possibility of optimizing the DC voltage ratio between the H-bridges of the power converter is introduced. Experimental results from a 5kVA prototype are presented in order to validate the proposed modulation technique