Modulated Matrix Converter Research Articles

Distortion Analysis and Duty Ratio Correction Algorithm for Asymmetric Modulation of Two-Stage Matrix Converter

When applying the two-stage matrix converter (TSMC) to the aero variable-speed constant-frequency generation system, the high input frequency varying between 360 and 800 Hz becomes a great challenge to its control. One of the most commonly used modulation methods for TSMC is the dual space vector modulation (DSVM). Simulation and experiments show that despite its advantages such as simplicity and low switching loss, the asymmetric DSVM causes distortion both in the output voltages and input currents of the TSMC. In this paper, the conception of “pulse orthocenter” (PO) is introduced via a BUCK model, and the influence of PO's fluctuation upon the actual output is revealed. Based on the PO theory, the spectra of TSMC's output voltages and input currents are then analyzed, indicating that asymmetric modulation causes $3n\omega_{\rm in}\pm(3m\pm 1)\omega_{o}$ harmonics in the output voltages and $(3n\pm 1)\omega_{\rm in}$ harmonics in the input currents. In order to suppress these harmonics, a duty ratio correction (DRC) algorithm is proposed to improve the waveform quality without increasing switching loss. The DRC formula is provided and the available range of related parameters discussed. The correctness of distortion analysis is testified via simulation, and the validity and feasibility of the DRC algorithm is verified via experiments.

Indirect matrix converter modulation strategies for open-end winding induction machine

In this paper an Indirect Matrix Converter (IMC) topology suitable for controlling an open-end winding induction machine is presented. The IMC is a direct power converter having no bulky energy storage elements with an input or current rectifying stage and a voltage source inverter as an output stage. To provide energy to an open-end winding induction machine two output stages are needed. Then, it is possible to obtain a voltage across any phase of the load up to 1.5 times the input phase voltage without over modulation. Two pulse width modulation strategies are presented: the first one is based on space vector modulation that suppresses the zero sequence voltage in the load whereas the second one is a carrier-based modulation which generates lower distorted input converter currents. Results are presented and discussed.

Review of Matrix Converter Modulation Topology (Venturini Method) and Its Application

This paper presents an overview of the matrix converter and its modulation techniques with application. Matrix converter is one of the most interesting members of power converter family; provide direct AC-AC conversion. A matrix converter is an ac-ac power frequency converter that received extension research attention due to its single stage power conversion technique, which is an alternate to ac-dc-ac converter.MC (matrix converter) is capable to convert energy from an ac source to ac load without the need of bulky and life- time limited energy storage elements. Here the purpose of most of these modulation methods is to generate sinusoidal current on the input and output sides. These methods are compared on the basis of theoretical complexities and performance.

Comparative Studies of Different Switching Patterns for Direct and Indirect Space Vector Modulated Matrix Converter

This paper presents a MATLAB/Simulink simulation of direct and indirect space vector modulation for matrix converter. Different switching patterns for both direct and indirect methods are simulated and compared. Three criteria are chosen to compare the performance of switching patterns: (1) total harmonic distortion (THD); (2) harmonic spectrum analysis of output voltages; and (3) number of switching in each switching period. Switching strategies are completely implemented using the power library in MATLAB/Simulink environment.

Extending the reactive compensation range of a direct AC–AC FACTS device for offshore grids

The authors suggest to use hybrid modulation schemes to improve the reactive power compensation capabilities of the direct AC–AC FACTS device composed of a matrix converter and a permanent magnet machine. Because of the intrinsic limitations of the conventional matrix converter modulation schemes, the device has so far displayed a poor reactive power compensation capability when the output power factor is low. Even worse, the direct AC–AC FACTS device could not provide pure reactive power compensation. The paper presents an analysis demonstrating how the hybrid Three-Vector-Scheme extends the reactive compensation range beyond the level that the conventional indirect space vector modulation exhibits. The reactive power compensation capabilities of the FACTS device with both modulations are computed and compared analytically and finally verified by a simulation study.

A Novel MC-DTC Method For Induction Motor Based on Fuzzy-neural network Space Vector Modulation

To improve the low speed performance of the direct torque control(DTC) system. The advantages of DTC method are combined with the advantages of the matrix converter based on space vector modulation technique. The design process of the neural network controller which generating the flux reference voltage vector and fuzzy controller which applying the torque reference voltage vector were represented. This proposed novel method provides a precious input power factor control capability beside the high control performances. Furthermore, Conventional principles of DTC and space vector modulation(SVM) of matrix converter(MC) were described. The combination of the two was given in detail. Finally, the simulation and experiment research were carried out to identify the new method effectiveness. The results of induction motor control at both steady state and transient state are shown to improve the low-speed performance and strong adaptabiIity of novel control strategy

Improvement of pulse pattern for space vector modulated matrix converters

AbstractNovel modulation which consists of conventional space vector modulation (SVM) based on a virtual AC/DC/AC conversion and carrier signal modulation for matrix converters is proposed. In this proposed modulation, duties for the switching pattern decided by conventional SVM are changed into those for each switch of matrix converter. The new duties for each output phase are compared with the triangle carrier. By using proposed modulation, switchings between the input phase voltage with minimum value and the voltage with maximum value are eliminated.In this paper, the conventional SVM and proposed modulation are explained. Next, for both conventional and proposed modulations waveforms of input current, output voltage and output current and their frequency spectra are calculated by PSIM simulation program. Simulation results show the proposed modulation can reduce harmonics of output voltage waveforms. © 2010 Wiley Periodicals, Inc. Electr Eng Jpn, 171(1): 46–54, 2010; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/eej.20903

Digital Carrier Modulation and Sampling Issues of Matrix Converters

Although the modulation of AC-AC matrix converters using space vector theory has long been established, their carrier-based modulation principles have only recently attracted some attention. Reasons commonly stated for evaluating the carrier-based alternative include simpler converter control because of its inherent autosequencing process, and easier implementation using fast on-chip timers embedded in most modern digital signal processors. Motivated by these likely merits, which have previously been proven for DC-AC inverters, an investigation is now pursued here to develop appropriate digital carrier modulation schemes for controlling conventional (direct) and indirect matrix converters with minimized semiconductor commutation count and smooth sextant transitions with no erroneous states produced. For guaranteeing the latter two features, correct digital sampling instants and state sequence reversal must be chosen appropriately, as demonstrated in the paper for the two different topological options, which, to date, have not yet been discussed in the existing literature. To validate the concepts discussed, experimental testing on the implemented conventional and indirect matrix laboratory prototypes was performed with their respective results captured and presented in the paper for visual confirmation.

Impact of sideband harmonic pattern on losses in laminated non-oriented steel

Losses in laminated non-oriented steel under the effect of two high harmonic clusters, caused by voltage excitation typical of two-level pulse-with-modulated (PWM) DC-link and space-vector modulated (SVM) matrix converters, were analyzed. The predicting method proposed, which incorporates anisotropy of loss K a and grain size g s, describes the magnetizing process within the steel by the means of Poisson statistical distribution. Results are then compared to losses determined by Bertotti's model. The two methods confirmed that spreading of sideband harmonics in the kilohertz range can reduce harmonic losses by up to 40% at low power frequencies.

Improvement of Pulse Pattern for Space Vector Modulated Matrix Converters

Novel modulation which consists of conventional space vector modulation (SVM) based on a virtual AC/DC/AC conversion and carrier signal modulation for matrix converters is proposed. In this proposed modulation, duties for the switching pattern decided by conventional SVM are changed into those for each switch of matrix converter. The new duties for each output phase are compared with the triangle carrier. By using proposed modulation, switchings between the input phase voltage with minimum value and the voltage with maximum value are eliminated.In this paper, the conventional SVM and proposed modulation are explained. Next, for both conventional and proposed modulations waveforms of input current, output voltage and output current and their frequency spectra are calculated by PSIM simulation program. Simulation results show the proposed modulation can reduce harmonics of output voltage waveforms.

Carrier-Based Modulation Technique for Matrix Converter

This paper presents a carrier-based modulation method for a matrix converter. By using the offset voltage and changing the slope of carrier, it is possible to synthesize the sinusoidal input currents with the unity power factor and desired output voltages. The proposed method is equivalent to the so called space vector pulsewidth modulation method. The proposed method uses a new point of view to understand the matrix converter modulation method such as the voltage source inverter (VSI) modulation method. Using the proposed method, this paper presents the two-phase/three-phase modulation method and dynamic/steady-state overmodulation method for the matrix converter. These methods are well developed in the study of a VSI. By the proposed steady-state overmodulation method, it is possible to synthesize the fundamental component of output voltage to be equal to that of input voltage at the cost of some distortion of input current. The feasibility of the proposed modulation method has been verified by a computer simulation and experimental results. These results show that the proposed carrier-based modulation method can be implemented easily without any tables. It can be used for the application where a higher voltage transfer ratio is essential

Matrix converter-FED ASDs

In this paper, a new ride-through module for a matrix converter has been proposed. The proposed module has been shown to maintain the rotor flux and synchronization between the motor and matrix converter during momentary power interruption. The ride-through system for matrix converter consists of two parts they are conventional matrix converter module and add-on ride through module. The principle of operation and advantages of matrix converter-fed ASDs are discussed in this paper.

A Control Technique for Compensating the Effects of Input Voltage Variations on Matrix Converter Modulation Algorithms

Many of the existing algorithms for the matrix converter are formulated in a way that makes their practical incorporation into the closed-loop control scheme difficult. Since these algorithms make assumptions about the input voltage for generating the switching actuation signals, it is not possible to compensate the input voltage variations, which result in incorrect voltage waveforms being applied to the load. In this article, a novel control technique for compensating the effects of the input voltage variations on the matrix converter algorithms is described. Simulation and experimental results demonstrating the performance of the proposed control algorithm are presented.

Matrix converter modulation strategies: a new general approach based on space-vector representation of the switch state

In this paper, a novel representation of the switch state of a three-phase to three-phase matrix converter is presented. This approach, based on space-vector notation, simplifies the study of the modulation strategies, leading to a complete general solution of the problem and providing a very useful unitary point of view. The already established strategies can be considered as particular cases of the proposed general solution. Using this approach, it can be verified that the space-vector modulation technique, owing to the intrinsic two degrees of freedom, represents the general solution of the modulation problem of matrix converters. This technique can be considered the best solution for the possibility to achieve the highest voltage transfer ratio and to optimize the switching pattern through a suitable use of the zero configurations.

Soft-switched matrix converter for high frequency direct AC-to-AC power conversion

Abstract A soft-switched matrix converter is proposed using the zero voltage switching technique in some resonant pole inverters. A high operating frequency with safe and efficient switching improves the dynamic and spectral performances and simplifies the protection logics and snubber networks. Further, it can be implemented using simple analogue circuits, having similar transfer characteristics to those of the modern pulse width modulated matrix converters, such as maximum voltage transfer ratio and unity input displacement factor. Analyses, design and simulation results are presented to verify the operating principle.