Indirect Matrix Converter Research Articles

Carrier-Based Randomized Pulse Position Modulation of an Indirect Matrix Converter for Attenuating the Harmonic Peaks

To attenuate the peaks of harmonics, three carrier-based randomized pulse position modulation schemes are proposed for an indirect matrix converter (IMC), which, to date, have not been discussed in existing literatures. In the first scheme, to avoid commutation of a rectifier stage at instants of carrier transition, one of four different pulse positions of the rectifier stage is selected randomly based on the Markov chain. The second scheme randomly places the center of the pulse position with a limited degree of freedom, which has a lower harmonic spectrum but higher commutation frequency. The maximum degree of freedom is achieved in the third scheme, which randomly varies the pulse position by delaying its edge along entire carrier cycle, resulting in a continuous and flat harmonic spectrum, but the maximum commutation frequency in three proposed schemes. An alternative carrier of an inverter stage is applied in all the schemes to maintain smooth operation at instants of carrier transition. Effectiveness of the proposed schemes is validated through experimental tests on an IMC prototype.

An All-DC Offshore Wind Farm With Series-Connected Turbines: An Alternative to the Classical Parallel AC Model?

In this paper, the concept of an all-dc wind park with series-connected turbines is investigated as an alternative to the classical ac parallel or radial wind park. This paper presents a literature overview of all-dc wind park concepts with series connection. A three-phase conversion system with permanent magnet machine, ac-ac converter, high-frequency transformer, and diode bridge rectifier is suggested in this paper for the series connection of dc turbines. The dc series park with the suggested conversion system is compared in terms of losses, cost, and reliability to the state-of-the-art park configuration which is the ac radial park with HVDC transmission. It is found that the dc series park becomes comparable with the ac radial design for high ratings of the dc turbines. Furthermore, the comparison shows that emphasis must be put on reducing the losses in the conversion system of the dc turbine and, particularly, the ac-ac converter. Therefore, the efficiency of the ac-ac converter is compared for three different topologies: the direct matrix converter, the indirect matrix converter, and the conventional back-to-back converter. The direct matrix converter is found to be the most efficient, suitable for the suggested conversion system.

Distributed Generation Using Indirect Matrix Converter in Reverse Power Mode

Indirect matrix converter (IMC) is an alternative for ac/ac energy conversion, usually operated with a voltage stepped-down gain of only 0.866. For applications like distribution generation where voltage-boost functionality is required, the traditional style of operating the IMC is therefore not appropriate. Like most power converters, the operation of the IMC can surely be reversed to produce a boosted gain, but so far its relevant control principles have not been discussed. These challenges are now addressed in this paper with distributed generation suggested as a potential application. Simulation and experimental results for validating various performance aspects of the proposed control schemes can be found in a later section of this paper.

Induction Motor Speed Control Using Indirect Z-source Matrix Converter with PSO-PI Controller under Various Break Conditions

Since induction motors are preferred over direct current machines in the view of cost and simplicity, they have widely been used in industry. In this paper, the speed of the three-phase induction motor has been controlled using an indirect z-source matrix converter. The method used for this purpose is flux control keeping the V/f ratio and regulating slippage. The effect of flux changes and reference velocity in this method has been taken into consideration and various electric break methods on the motor have been studied accordingly. Coefficients of PI controllers have been obtained in the proposed system for desirable response by PSO Algorithm. The proposed system with the respective converter has been simulated in SIMULINK environment using the information of an induction machine by MATLAB Software. The results show to using the proposed system and indirect z-source matrix converter, appropriate velocity and desirable torque are obtained in a short time. DOI: http://dx.doi.org/10.11591/ijpeds.v3i1.1783

High-performance doubly fed induction machine drive system using predictive direct torque control drive system fed by indirect matrix converters

SUMMARY This paper presents a novel predictive direct torque control for doubly fed induction machine based on indirect matrix converter (IMC), which is characterized by its simple structure, minimal-torque ripple, and constant switching frequency. Nowadays, the control strategies based on predictive methods have proved their efficiency to improve drive systems capabilities. So, in this paper, one of the best predictive methods that have recently been suggested for doubly fed induction machine drive systems is applied to IMC. The purpose of this combination is to modify the control parameters and size/volume reduction of drive system structure, which is difficult to achieve in conventional systems based on voltage source inverters. The good tracking behavior with reduced torque and flux ripple for both motoring and generating modes as well as removing bulky electrolytic capacitor from the DC link of a converter resulted by using three vectors, two active vectors together with one zero vector per switching period, and applying these vectors to the inverter stage of IMC. To improve the motor drive system performance and reduce losses caused by snubber circuits, the rectifier four-step commutation method in rectifier bridge is used. In the inverter stage, the predictive direct torque control method is employed. The simulation results of the proposed model confirm its effectiveness and accuracy. Copyright © 2013 John Wiley & Sons, Ltd.

Comparison of Two Overmodulation Strategies in an Indirect Matrix Converter

This paper discusses two overmodulation controls, namely, square wave and trapezoidal, in the indirect matrix converter (IMC) for motor drive application. The differences between these two modulations are analyzed based on the output-input voltage transfer ratio (VTR), the efficiency, and the current total harmonic distortions under two load conditions. Moreover, the performance is then improved by implementing four-step commutation methods in the primary side of the IMC. The validity of the proposed methods will be demonstrated through simulation and experimentally. The experimental results show that the VTR can be improved from 0.866 to 0.97 in the square wave modulation and 0.92 for the trapezoidal wave modulation in an induction motor drive system.

Evaluating the Dynamic Stability of Power System Using UPFC based on Indirect Matrix Converter

 Abstract—In this paper, the affects of the newly presented structures of unified power flow controller (UPFC) on power system dynamic stability are investigated. The newly presented UPFC structure is based on indirect matrix converter (IMC) controlled by the space vector method (SVM). A non-linear modeling is accomplished for a sample power system possessing UPFC-IMC in order to investigate the affects of it on the dynamic stability. The linear model of the power system is then mentioned in state equations form defining system elements and linearizing the non-linear model around the operation point. A Heffron-Philips model is presented according to the mentioned state equations for the sample power system possesses UPFC-IMC. The accuracy of the mentioned theoretical cases is reconfirmed through the simulation results in MATLAB/Simulink.

Multi-objective Design of a Modular Power Converter based on Medium Frequency AC-link for Offshore DC Wind Park

The design of a modular power converter based on medium frequency AC-Link for offshore wind turbines regarding efficiency, power density and power to mass ratio is described in this paper. The impact of four design parameters in the three objectives is studied. Such parameters are the AC-AC converter topology, the number of modules, and the number of phases and frequency of the AC-link. Six topologies are investigated and compared. The conventional back-to-back (B2B) converter, the B2B with three phase squared wave output, the B2B with single phase squared wave output, the direct matrix converter, the indirect matrix converter, and the reduced matrix converter are the selected topologies. The Pareto surface of the three objectives is obtained for a set of design parameters. It has been found that a wind energy conversion system based on a medium frequency AC-link will lead the best trade-off between efficiency, power density and power to mass ratio when the AC-AC converter topology is the direct matrix converter, the AC-link frequency is selected around 1kHz and the power per module is in the range of 2.5 to 4 MW.

Operation Characteristics Improvement of Simplified Indirect Matrix Converter Based on Leading Current Compensation

Operation Characteristics Improvement of Simplified Indirect Matrix Converter Based on Leading Current Compensation

A Three-Phase Dual-Input Matrix Converter for Grid Integration of Two AC Type Energy Resources

This paper proposes a novel dual-input matrix converter (DIMC) to integrate two three-phase ac type energy resources to a power grid. The proposed matrix converter is developed based on the traditional indirect matrix converter under reverse power flow operation mode, but with its six-switch voltage source converter replaced by a nine-switch configuration. With the additional three switches, the proposed DIMC can provide six input terminals, which make it possible to integrate two independent ac sources into a single grid-tied power electronics interface. The proposed converter has input-to-output voltage boost capability since power flows from the converter's voltage source side to its current source side. Commanded currents can be extracted from the two input sources to the grid. The proposed control and modulation schemes guarantee sinusoidal input and output waveforms as well as unity input power factors. The simulation and experimental results using a laboratory prototype are provided to validate the effectiveness of the proposed control and modulation schemes for the proposed converter.

Indirect matrix converter with unity voltage transfer ratio for AC to AC power conversion

Having a voltage transfer ratio lower than unity with a 0.866 upper limit, even lower than 0.866 in the course of experiments because of parasitic components of real power circuits, is one of the shortcomings of matrix converters. This deficiency is one of the greatest impediments to industry adaptation of matrix converters. To surmount this barrier this paper proposes a novel modification in circuit topology of indirect matrix converters (IMC) achieving voltage boosting and unity voltage transfer ratio. Besides preserving the inherent advantages of the conventional matrix converters, such as controllability of input power factor, sinusoidal input/output currents and the ability of bidirectional power flow, the remarkable feature of this solution is that, unlike the other research in this field no special control strategy or additional reactive elements at the DC-link is used and the integrity of the converter has been kept as much as possible. Furthermore a new efficient switching strategy is proposed for the new converter. Simulation results are shown to support the given theoretical analyses and experimental results obtained from a 5kW converter verify the full functionality of the proposed topology.

Comparative Evaluation of Three-Phase AC–AC Matrix Converter and Voltage DC-Link Back-to-Back Converter Systems

This paper introduces the methodology and the results of a comprehensive comparison of a direct matrix converter (MC), an indirect MC, and a voltage dc-link back-to-back converter for a 15-kW permanent magnet synchronous motor drive. The comparison involves the investigation of the passive components, including the EMI input filter, the required silicon chip area for a defined maximum admissible thermal loading of the power semiconductors, the total losses and/or achievable efficiency, a prediction of the resulting volume and weight of the passive components, and, finally, a tradeoff study between the efficiency, volume, and weight of the converters. Different performance indicators that ultimately allow a systematic determination of the application area of each converter topology are provided with this comparative evaluation.

Imposed Sinusoidal Source and Load Currents for an Indirect Matrix Converter

A new strategy for indirect matrix converters which allows an optimal control of source and load currents is presented in this paper. This method uses the commutation state of the converter in the subsequent sampling time according to an optimization algorithm given by a simple cost functional and the discrete system model. The control goals are regulation of output current according to an arbitrary reference and also a good tracking of the source current to its reference which is imposed to have a sinusoidal waveform with low distortion. Experimental results support the theoretical development.

Instantaneous Reactive Power Minimization and Current Control for an Indirect Matrix Converter Under a Distorted AC Supply

This paper presents a current control scheme with instantaneous reactive power minimization for an indirect matrix converter. The strategy uses the commutation state of the converter in the subsequent sampling time according to an optimization algorithm given by a simple cost function and the discrete system model. Using this strategy, harmonics in the input current generated by the resonance of the input filter are strongly reduced. Simulation and experimental results with a laboratory prototype are provided in order to validate the control scheme, and the effects of a distorted source voltage and filter resonance are analyzed.

Control of indirect matrix converter with bidirectional output stage for micro-turbine

In this study, a new AC-DC-AC matrix converter is developed. This matrix converter is designed to connect a micro-turbine to the grid, to replace the traditional system used in micro-turbines, which is based on an inverter-rectifier system (VSR/VSI) with energy storage elements. A specific power circuit is introduced. The circuit consists of two stages, where the second stage is bidirectional. Also, a new switching technique is presented for the circuit mentioned above, which works with two voltage space vectors. The first vector corresponds to the input voltages (variable frequency) and second one to the output voltages (fixed frequency). This technique switching allowing to replace the VSR/VSI regarding operational concerns, with less loss, at lower cost and lower weight. For verifying the control algorithm, a laboratory prototype has been developed, using among other elements a Spectrum Digital eZdspTM TMS320F2812 card. In addition, the model predictive control (MPC) is used to control the electrical power of the micro-turbine generator by manipulating the fuel flow. The suggested method provided the optimal functioning not only for the small step changes but also for large random step changes.

A Carrier-Based Pulse Width Modulation Method for Indirect Matrix Converters

This paper proposes a carrier-based pulse width modulation (PWM) method to control an indirect matrix converter (IMC) by analyzing the relationship between the space vector PWM (SVPWM) and the carrier-based PWM. The complexity of the SVPWM method for an IMC can be reduced by using an equivalent carrier-based PWM method. The advantage of the proposed algorithm is its ability use only one symmetrical triangular carrier signal to generate the gate signals for all of the power switches in both the rectifier and inverter stages as compared to the conventional method where the carrier signal used in the rectifier stage is different from that of the inverter stage. In addition, by using a suitable offset voltage component in the modulation signals, the output voltage magnitude reaches 0.866 of the input voltage magnitude. Simulation and experimental results are provided in order to validate the proposed method.

Motor performance investigation of an indirect matrix converter with a reactor‐free boost converter

AbstractThis paper describes a three‐phase power converter which utilizes the neutral point of an induction motor and demonstrates the performance of the motor using the proposed method under various operating conditions. Several motor test results, such as the speed–torque characteristic, the torque impact, and the acceleration–deceleration characteristic, are included to confirm the performance of the induction motor. The structure of the proposed circuit consists primarily of an AC/AC converter [indirect matrix converter (IMC)] and a boost converter connected to the neutral point of the induction motor. In addition, this paper also proposes a method to reduce the ripple found in the battery current. Several experimental results show that the motor works well, and even the leakage inductance is utilized in the boost converter. © 2012 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc.

Fault-Tolerant Matrix Converter Motor Drives With Fault Detection of Open Switch Faults

This paper describes a novel fault-tolerant matrix converter motor drive system which requires an appropriate control strategy and the application of an effective fault detection technique. Two types of fault-tolerant matrix converter, a direct matrix converter and an indirect matrix converter, are proposed for a permanent magnet synchronous motor drive against open-circuit faults in safety-critical applications. A fault-tolerant control strategy is developed in order to maintain the continuous operation of the drive system with satisfactory performance. A high-speed fault detection strategy for detecting and identifying the faulty open-circuited switches located in the fault-tolerant four-phase direct matrix converter is also proposed. Simulation and experimental results are shown to demonstrate the effectiveness of the proposed fault-tolerant matrix converters and the developed fault detection strategy applied to the motor drive system under faulty operating conditions.

Current Control for an Indirect Matrix Converter With Filter Resonance Mitigation

A predictive control scheme for the indirect matrix converter including a method to mitigate the resonance effect of the input filter is presented. A discrete-time model of the converter, the input filter, and the load is used to predict the behavior of the instantaneous input reactive power and the output currents for each valid switching state. The control scheme selects the state that minimizes the value of a cost function in order to generate input currents with unity power factor and output currents with a low error with respect to a reference. The active damping method is based on a virtual harmonic resistor which damps the filter resonance. This paper shows experimental results to demonstrate that the proposed control method can generate good tracking of the output-current references, achieve unity input displacement power factor, and reduce the input-current distortion caused by the input filter resonance.

A Compact Three-Phase Single-Input/Dual-Output Matrix Converter

This paper presents a novel matrix converter with one ac input and two ac outputs. The presented topology is based on the traditional indirect matrix converter, but with its rear-end six-switch inverter replaced by a compact nine-switch inverter. With only three extra switches added, the proposed converter can produce two sets of three-phase ac outputs, whose amplitudes, frequencies, and phases can appropriately be regulated. Features such as sinusoidal input and outputs, unity input power factor and minimum commutation count are all retained by the proposed topology, despite having an additional output. Its modulation is realized by the computationally less intensive carrier-based method, whose unique carrier requirements can easily be managed within a programmable logic device. Mathematical proof for validating sinusoidal input and outputs achieved by this modulation technique is also discussed, before being verified in simulation and experimentally, together with other findings.