Pawel Szczesniak

Generation of matrix-reactance frequency converters based on unipolar PWM AC matrix-reactance choppers

This paper deals with three-phase direct matrix- reactance frequency converters (MRFC) based on unipolar PWM AC matrix-reactance choppers (MRC). The topologies of the proposed MRFC are based on a three- phase unipolar MRC structure. Each MRC with conventional topology has two synchronous-connected switches [SCS] sets. In the MRFC, unlike the MRC topology, one of SCS sets is replaced by a matrix-connected switches (MCS) set in order to make possible of the load voltage frequency change. Six new topologies of the MRFC based on MRC boost, buck-boost, Cuk, Zeta or SEPIC structures are presented. Through the generation concept of the proposed converters both the description of above- mentioned converter topologies and general description of the control strategies are presented. The structure of the proposed MRFC contains a three-phase matrix converter (MC), which is introduced instead of the source or load SCS used in unipolar MRC. The step-down or step-up of the MC set is dependent on the input and output voltage or current source configurations. Analysis determining the location where the MC should be introduced is realized by means of the one-cycle switched models with suitable voltage and current sources introduced instead of the capacitors and inductors respectively. Furthermore, exemplary results of the simplified theoretical analysis, based on the averaged state space method, as well as simulation test results obtained for a classical Venturini control strategy of MC, are also presented as an initial verification of the properties of the proposed converters.

Matrix-Reactance Frequency Converter Based on Buck-Boost Topology

This paper deals with a three-phase direct matrix-reactance frequency converter (MRFC) with buck-boost topology and includes a description of its topology and operation plus presentation of the results of an investigation of its properties. Presented too is a conceptual development of the frequency converter based on a buck-boost matrix-reactance chopper (MRC) with source switches arranged as in a matrix converter (MC). The averaged state space method is used in the analysis. In the control circuit, a classical control strategy, attributable to Venturini, is used for the study of the presented conception. The simulation test results are also presented in order to verify the results of the theoretical analysis. Furthermore, simplified description of the experimental setup, which will be used in next investigations is also presented.

Modelling and analysis of a matrix-reactance frequency converter based on buck-boost topology by DQ0 transformation

This paper deals with a three-phase matrix-reactance frequency converter (MRFC). The analysed MRFC topology is based on buck-boost matrix-reactance chopper (MRC) one with source synchronous connected switches (LSCS) set arranged as in the step-up matrix converter (MC). The MRFC in question makes it possible to obtain a load output voltage much greater than the input voltage. Presented in this paper is a description a method for the analysis of the steady and transient state properties of presented MRFC. The static and dynamic characteristics of the presented converter under the control strategy proposed by Venturini are fully analysed on the basis of the circuit model development by the DQ0 transformation. Various static converter characteristics such as voltage and current gain, input power factor are completely analysed. Transition characteristics are also analysed by a small-signal model. The usefulness of the models is verified through computer simulations with good agreements.

New family of matrix-reactance frequency converters based on unipolar PWM AC matrix-reactance choppers

This paper deals with three-phase direct matrix-reactance frequency converters (MRFC) based on unipolar PWM AC matrix-reactance choppers (MRC). The topologies of the proposed MRFC are based on a three-phase unipolar MRC structure. Each MRC with conventional topology has two synchronous-connected switches (SCS) sets. In the MRFC, unlike the MRC topology, one of SCS sets is replaced by a matrix-connected switches (MCS) set in order to make possible of the load voltage frequency change. Six new topologies of the MRFC based on MRC boost, buck-boost, Cuk, Zeta or SEPIC structures are presented. Through the generation concept of the proposed converters both the description of above-mentioned converter topologies and general description of the control strategies are presented. The structure of the proposed MRFC contains a three-phase matrix converter (MC), which is introduced instead of the source or load SCS used in unipolar MRC. The step-down or step-up of the MC set is dependent on the input and output voltage or current source configurations. Analysis determining the location where the MC should be introduced is realized by means of the one-cycle switched models with suitable voltage and current sources introduced instead of the capacitors and inductors respectively. Furthermore, exemplary results of the simplified theoretical analysis, based on the averaged state space method, as well as simulation test results obtained for a classical Venturini control strategy of MC, are also presented as an initial verification of the properties of the proposed converters.

Hybrid Voltage Sag\/Swell Compensators: A Review of Hybrid AC\/AC Converters

The parameters of electrical energy, such as supply voltage amplitude, are very important, especially from the viewpoint of the final consumer with respect to sensitive loads connected to the grid. Dynamic states in the power grid-voltage sags and swells-might cause faults and defects to develop in sensitive loads. To mitigate unwanted effects, many topologies of ac/ac converters are implemented as voltage compensators. This article presents a review of hybrid ac/ac converters designed to compensate voltage sags and swells with the aim of protecting sensitive loads against sudden and severe changes in supply voltage amplitude. In this article, only solutions without galvanic separation between source and load are described. To assess the properties and to compare different topologies of voltage compensators, some common parameters, such as range of voltage sag and swell compensation, reliability, quantity of switches and transformers, and required power ratings of power electronic units in relation to power of load, are introduced. In addition, we discuss possibilities for compensation of voltage interruption, time of compensation, the efficiency, and the effect on the supply network of the described circuits. The results of the analysis have been collected and compared in tabular form and represented in graphical form. Furthermore, we show potential areas of application for particular solutions of ac voltage compensators.

A voltage regulator/conditioner based on a hybrid transformer with matrix converter

This paper deals with a voltage regulator based on a hybrid transformer with matrix converter realizing an electrical coupling in the hybrid transformer unit. The parameters of electrical energy such as voltage amplitude are very important, particularly from the viewpoint of the final consumer and sensitive loads connected to the grid. Furthermore, a hybrid transformer using matrix converter can be used for power flow control and for transient stability improvement in AC transmission systems. Active power flow and voltage magnitude in transmission lines can be varied using a conventional or thyristor controlled regulators. However, the control parameters can be executed only in steps depending on the taps available in the transformer. An approach for obtaining continuous control of the voltage magnitude and phase shift using a conventional transformer with two windings and a pulse width modulated matrix converter is presented in this paper. The operating principles and steady state properties are discussed. Detailed computer simulation results are presented in the paper. Furthermore, experimental test results obtained from a three-phase 3 kVA laboratory model with passive load are also presented.

Steady and transient state analysis of a matrix-reactance frequency converter based on a boost PWM AC matrix-reactance chopper

This paper deals with a three-phase matrix-reactance frequency converter (MRFC). The analysed MRFC topology is based on the boost matrix-reactance chopper (MRC) with a load synchronous connected switch (LSCS) set arranged as in the step-up matrix converter (MC). The MRFC in question makes it possible to obtain a load output voltage much greater than the input voltage. Presented in this paper is a description of a new method for the analysis of the steady and transient state properties of the presented MRFC. The analytical method based on d-q transformation is proposed for solving non-stationary equations, which we derive as a mathematical model of the state-space averaged method applying to the analysis of the discussed MRFC. The analysis results are obtained for a classical Venturini control strategy. Furthermore, for the verification of the theoretical analysis the simulation test results are also presented.

A comparison of basic properties of single-phase serial AC voltage controllers using bipolar PWM chopper

This paper deals with two solutions for single-phase serial AC voltage controllers with bipolar PWM chopper. In these converters, either the bipolar PWM AC matrix chopper (MC) based on full-bridge topology or the bipolar PWM AC matrix-reactance chopper (MRC) based on Cuk B2 topology and auxiliary transformer is applied. The MRC, in distinction to MC, has a magnitude of voltage transformation function greater than one. The peak detection method in the control circuit of both controller solutions is applied for fast control of the load voltage changes. The steady state theoretical analysis based on averaged models and transient state analysis based on small-signal averaged models of the presented controllers are employed. Furthermore, simulation and experimental test results are provided to confirm and verify the theoretical approach. On the basis of these investigations a comparative study of the results showing performance of both controller solutions is presented

Hybrid Transformer With Matrix Converter

This paper deals with an ac-ac voltage regulator/compensator based on a hybrid transformer with a matrix converter realizing electrical coupling in the hybrid transformer unit. The parameters of electrical energy, such as voltage amplitude, are very important, particularly from the viewpoint of the final consumer and sensitive loads connected to the grid. Furthermore, a hybrid transformer using a matrix converter can be used for power-flow control and for transient stability improvement in ac transmission systems. Active power flow and voltage magnitude in transmission lines can vary by using a conventional mechanical or thyristor-controlled regulator. However, the control parameters can be executed only in steps depending on the taps available in the electromagnetic transformer. An approach for obtaining continuous control of the voltage magnitude and phase shift using a conventional transformer with two windings and a pulsewidth-modulated matrix converter is presented in this paper. The operating principles and steady-state properties are discussed. Detailed computer simulation results are presented in this paper. Furthermore, experimental test results obtained from a three-phase 3 kVA laboratory model are also presented.

A comparison of basic properties of the integrated and cascade matrix-reactance frequency converters

The paper deals with three-phase AC/AC frequency converters without DC storage. The integrated and cascade matrix-reactance frequency converters (MRFC) are analysed and discussed. The integrated MRFC are based on PWM AC unipolar matrix-reactance choppers (MRCs) with integrated voltage or current source matrix converter (MC). In the second solution of the MRFC the cascade connection of the MRC with MC is used. Results of the theoretical analysis and simulation test results are taking into account in order to comparison the steady state properties of mentioned converters. Experimental test results of ca 1 kVA laboratory models are presented to validate the theoretical and simulation ones.