Control Of Matrix Converter Research Articles

Constant Switching Frequency DTC for Matrix Converter Fed Speed Sensorless Induction Motor Drive

The paper presents a constant switching frequency scheme for speed sensorless Direct Torque Control (DTC) of Matrix Converter fed Induction Motor Drive. The use of matrix converter facilitates improved power quality on input as well as motor side, along with Input Power Factor control, besides eliminating the need for heavy passive elements. Moreover, DTC through Space Vector Modulation helps in achieving a fast control over the torque and flux of the motor, with added benefit of constant switching frequency. A constant switching frequency aids in maintaining desired power quality of AC mains current even at low motor speeds, and simplifies input filter design of the matrix converter, as compared to conventional hysteresis based DTC. Further, stator voltage estimation from sensed input voltage, and subsequent stator (and rotor) flux estimation is done. For speed sensorless operation, a Model Reference Adaptive System is used, which emulates the speed dependent rotor flux equations of the induction motor. The error between conventionally estimated rotor flux (reference model) and the rotor flux estimated through the adaptive observer is processed through PI controller to generate the rotor speed estimate.

Research on the modulation and control of multilevel matrix converter

This paper discusses the effects of different space vector modulation (SVM) hexagon partition on common mode voltage suppression at high modulation index and presents an improved capacitor voltage balance strategy for multilevel matrix converter. Matrix converter is a compact designed converter which allows direct AC–AC power transfer without an intermediate DC link. Multilevel matrix converters, which utilises a multilevel structure on a traditional matrix converter, expand these characters to high-voltage and high-power situations. This paper is concerned with SVM of three-level matrix converter and concentrates on the comparison between different hexagon partitions; the improved balancing strategy is employed to improve the performance of flying capacitor voltage control. Simulation from Matlab/Simulink and results from a small-scale experimental prototype are presented to validate the theoretical results.

An Experimental Evaluation of Predictive Current Control and Predictive Torque Control for a PMSM Fed by a Matrix Converter

Predictive control has emerged as an attractive alternative for the control of matrix converters. The predictive control is a flexible method to control different variables through the minimization of a cost function. In drive system, the predictive control can be divided to predictive current control (PCC) and predictive torque control (PTC). In PCC, the stator current is evaluated in cost function, but in PTC the torque and stator flux are evaluated in the cost function. On the other hand, the ability of matrix converter in control of input source current can be easily included in both PCC and PTC. This paper introduces the methodology and the results of a comprehensive comparison of PCC and PTC techniques for a permanent-magnet synchronous motor (PMSM) fed by a matrix converter. The comparison involves the investigation of the torque and stator flux ripples, the total harmonic distortion of input and output currents, and the input filter resonance as figures of merit. Different performance indicators that present an instruction for the selection of predictive control methods for PMSM drive applications by matrix converters for engineering practices are provided with this comparative evaluation.

Experimental evaluation of model predictive current control for a modified three‐level four‐leg indirect matrix converter

This study presents an experimental validation and robustness evaluation of predictive current control and reactive power minimisation strategy for a three-level three-phase four-wire indirect matrix converter. The proposed topology features a unification of conventional four-leg indirect matrix converter with an additional four switches circuit resembling a back-to-back buck circuit to synthesise multi-level variable dual dc-link voltage. A systematic rectifier switching strategy is elaborated to ensure positive fictitious dc-link voltage at any instant. The proposed control and topology have been tested under various transient and steady-state conditions for comprehensive robustness evaluation. The experimental results reveal an outstanding independent load current reference tracking with low ripple current and the reactive power minimisation has been achieved by tuning the weighting factor. The load current tracking and reactive power minimisation have been achieved by properly tuning the weighting factor. The load current harmonics distortion is recorded <5% during normal operating conditions.

Reverse matrix converter control method for PMSM drives using DPC

ABSTRACTThis paper proposes a control method for a reverse matrix converter (RMC) that drives a three-phase permanent magnet synchronous motor (PMSM). In this proposed method, direct power control (DPC) is used to control the voltage source rectifier of the RMC. The RMC is an indirect matrix converter operating in the boost mode, in which the power-flow directions of the input and output are switched. It has a minimum voltage transfer ratio of 1/0.866 in a linear-modulation region. In this paper, a control method that uses DPC as an additional control method is proposed in order to control the RMC driving a PMSM in the output stage. Simulations and experimental results verify the effectiveness of the proposed control method.

Small-signal stability analysis, and predictive control of Z-Source Matrix Converter feeding a PMSG-WECS

The modeling, small-signal stability analysis, and control of quasi-Z-Source Matrix Converter (qZSMC), and also its application in Wind Energy Conversion System (WECS) are discussed. First, the small-signal model of the qZSMC, composed of an input filter, a Three-Phase Quasi-Z-Source Network (TPQZSN), and a Matrix Converter (MC), is derived. Then, a comprehensive stability study is carried out and it is shown that, unlike the conventional MC, the qZSMC does not have problem working stable for its entire range of operation. The small-signal model is used to obtain system transfer functions and perform a frequency domain analysis. A guide to choose proper passive components of qZSMC is also presented. The qZSMC is further employed as grid interface by a Permanent Magnet Synchronous Generator (PMSG) based WECS (PMSG-WECS). A modified predictive control (MPC) is developed, allowing shoot-through states to be inserted within the deliberately made sequences of zero switching states in MC switching pulses. The proposed MPC is then compared to its conventional version, showing that by the MPC, the grid-current ripples are reduced considerably. Simulation study is used to assess the effectiveness of proposed WECS and MPC, and to highlight the promising features of the proposed WECS in comparison to Conventional MC-based PMSG-WECS (CMC-WECS).

Modulated Predictive Control for Indirect Matrix Converter

Finite State Model Predictive Control (MPC) has been recently applied to several converter topologies as it can provide many advantages over other MPC techniques. The advantages of MPC include fast dynamics, multi-target control capability and relatively easy implementation on digital control platforms. However, its inherent variable switching frequency and lower steady state waveform quality, with respect to standard control which includes an appropriate modulation technique, represent a limitation to its applicability. Modulated Model Predictive Control (M2PC) combines all the advantages of MPC with the fixed switching frequency characteristic of PWM algorithms. The work presented in this paper focuses on the Indirect Matrix Converter (IMC), where the tight coupling between rectifier stage and inverter stage has to be taken into account in the M2PC design. This paper proposes an M2PC solution, suitable for IMC, with a switching pattern which emulates the desired waveform quality features of Space Vector Modulation (SVM) for matrix converters. The switching sequences of the rectifier stage and inverter stage are rearranged in order to always achieve zero-current switching on the rectifier stage, thus simplifying the current commutation strategy.

Comparative study on Predictive Current Control and Space Vector Modulation Techniques of Direct Matrix Converter in Wind Energy Conversion System

Comparative study on Predictive Current Control and Space Vector Modulation Techniques of Direct Matrix Converter in Wind Energy Conversion System

Model Predictive Control of a Capacitorless Matrix Converter-Based STATCOM

This paper presents the concept of a capacitorless static synchronous compensator (STATCOM) that uses a matrix converter (MC) and model predictive control (MPC) to compensate lagging power factor (p.f.) loads using inductors instead of electrolytic capacitors (e-caps) for energy storage. Although ubiquitous in power electronic converters, e-caps have well-known failure modes and wear-out mechanisms. In practice, the bus capacitors in a voltage-sourced inverter reactive power compensator may require monitoring and replacement, which can increase the cost of ownership of a traditional reactive power compensation method. The proposed MPC-MC-STATCOM uses a $3\times3$ direct MC, which when properly controlled using finite-set MPC, creates a phase shift of 180° from the input to output current, and thus supplies reactive power to the utility grid using inductors instead of the e-caps. This paper presents the fundamental concept and model derivation. The theoretical analysis is accompanied by simulation and experimental results that verify the intended operation of the controls and circuity in steady state under ideal grid conditions and dynamically to demonstrate robustness of the MPC control under step changes in grid voltage distortion and load characteristics. The conclusion is that the capacitorless STATCOM can provide the reactive power needed to compensate lagging p.f. load.

Real-time implementation of finite control set model predictive control for matrix converter based solid state transformer

Solid state transformer formed by back-to-back connection of two three-to-single-phase matrix converter, so called MC-SST, owns ac–ac power conversion in a single stage and an absence of the bulky line-frequency transformer when linking ac sources of different voltage amplitudes and frequencies. Current modulation methods for this topology include sophisticated computation of current and voltage vectors besides duty cycle composition. Moreover, extra control design is required to manage the power exchange. In this paper, the easy-to-perform finite control set model predictive control (FCS-MPC) for this type of MC-SST is implemented in real-time platform and compared with the proportional–integral control strategy. The active power changes, different voltage amplitudes and phases, and parameter variations are investigated. Simulation and real-time implementation results demonstrate the simplicity and validity of the MPC approach for power management of the MC-SST system.

Preselection algorithm based on predictive control for direct matrix converter

This study presents an enhanced predictive control strategy to reduce the calculation effort for direct matrix converters. The main idea is to preselect the switching states to decrease the calculation effort during each sample period. The proposed preselection algorithm enables a predefined cost function to consider only the preselected switching states to perform the expected control. On the basis of the preselection of switching states at each sample period, the proposed method can effectively reduce the calculation effort as well as show a good performance. The proposed predictive control scheme uses only preselected switching states to generate the desired source/load current waveforms and control the input power factor. The feasibility of the proposed method is experimentally verified and results are presented in the study.

A Modified Open Loop Control of a Matrix Converter Connected to Wind Energy System

Wind energy conversion system (WECS) is bit by bit gaining interest as a suitable source of renewable energy. In this paper a direct AC-AC matrix converter is utilized to interface an isolated static load fed from WECS. A self-excited induction generator is utilized as it has many advantages in terms of ease of maintenance, self-protection against short circuits. This paper proposes a modified open loop control of matrix converter with indirect space vector modulation. The modified open loop provides constant output voltage and constant frequency even if the wind speed changed. Matrix converter (MC) is used rather than AC-DC-AC converter as it eliminates the bulky capacitors. Finally, simulation results for different operating points are displayed which are consistent with the expected results.

Design and Dimensioning of Essential Passive Components for the Matrix Converter Prototype

The continuous popularity of the research in the area of the matrix converter control theory has been supported by steady technological improvements. It is still common to use discrete semiconductor switches in an anti-serial connection, even though some integrated solutions have been presented by various vendors already. Furthermore, recently experimental all-in-one matrix converter power modules based on reverse blocking transistors were introduced. However, this development has not eliminated the need of the protection circuit and other passive components in the converter’s power part. This article strives to describe design procedure for one kind of the matrix converter protection circuits and the design of the input filter for the 3x3 matrix converter prototype.

Novel bacterial foraging-based ANFIS for speed control of matrix converter-fed industrial BLDC motors operated under low speed and high torque

In this paper, a novel adaptive neuro-fuzzy inference system (ANFIS)-based control technique optimized by Bacterial Foraging Optimization Algorithm for speed control of matrix converter (MC)-fed brushless direct current (BLDC) motor is presented. ANFIS is considered to be one of the most promising technologies for control of electrical drives fed by MC. Optimizing the training parameters of ANFIS, to improve its performance, is still being considered by several researchers recently. Parameters of the online ANFIS controller such as learning rate (η), forgetting factor (λ) and steepest descent momentum constant (α) are optimized by using the proposed algorithm. For the purpose of comparison, proportional integral derivative controller, fuzzy logic controller, PSO-ANFIS and BAT-ANFIS are considered. Set point tracking performances of the proposed system are carried out at various operating points for an industrial BLDC motor operating at a maximum rated speed of 380 rpm and torque of 6.4 N m. Time domain specifications such as rise time, settling time, peak time, steady-state error and peak overshoot in the presence and absence of load torque disturbances are presented. Time integral performance measures such as integral square error, integral absolute error, and integral time multiplied absolute error are analyzed for various operating conditions. Speed fluctuation in the output of BLDC motor is dependent on the source current harmonics of the inverter/converter. To illustrate this, total harmonic distortion (THD) analysis is carried out for the existing PWM inverter and the proposed MC, and it is proved that MC results in reduced THD, as compared to PWM inverter. Simulation results confirm that the proposed controller outperforms the other existing control techniques under various set speed and torque conditions. Statistical analysis is effectively carried out to prove the effectiveness of the proposed controller. Experimental analysis is performed to validate the performance of the proposed control scheme.

FPGA-Based Model Predictive Controller for Direct Matrix Converter

Recently, there has been an increase in the use of finite control set model predictive control (FCS-MPC) for power converters. Model predictive control (MPC) uses the discrete-time model of the system to predict future values of control variables for all possible control actions and computes a cost function related to control objectives. This control technique can provide fast dynamic response. However, MPC method implementation imposes a very high computational burden and causes significant hardware requirements for real-time implementation. In this paper, a fully field-programmable gate array (FPGA)-based real-time implementation of MPC is proposed for direct matrix converter (DMC). In the proposed method, all control calculations and the safe commutation scheme for DMC are fully implemented in the FPGA and the need for another digital control platform, such as digital signal processors (DSP) or dSPACE, is eliminated. The proposed scheme takes full advantages of the parallel computation capability of FPGAs.

A current controlled matrix converter for wind energy conversion systems based on permanent magnet synchronous generator

The main challenges of wind energy conversion systems (WECS) are to maximize the energy capture from the wind and injecting reactive power during the fault. This paper presents a current controlled matrix converter to interface Permanent Magnet Synchronous Generators (PMSG) based WECS with the grid. To achieve fast dynamic response with reduced current ripples, a hysteresis current control is utilized. The proposed control system decouples the active and reactive components of the PMSG current to extract the maximum power from the wind at a given wind velocity and to inject reactive power to the grid. Reactive power injection during the fault satisfying the grid-codes requirement. The proposed WECS has been modeled and simulated using PSCAD/EMTDC software package.

Hybrid Control Strategy for Matrix Converter Fed Wind Energy Conversion System

In this paper, a hybrid control strategy for a matrix converter fed wind energy conversion system is presented. Since the wind speed may vary, output parameters like power, frequency and voltage may fluctuate. Hence it is necessary to design a system that regulates output parameters, such as voltage and frequency, and thereby provides a constant voltage and frequency output from the wind energy conversion system. Matrix converter is used in the proposed solution as the main power conditioner as a more efficient alternative when compared to traditional back-back converter structure. To control the output voltage, a vector modulation based refined control structure is used. A power tracker is included to maximize the mechanical output power of the turbine. Over current protection and clamp circuit input protection have been introduced to protect the system from over current. It reduces the spikes generated at the output of the converter. The designed system is capable of supplying an output voltage of constant frequency and amplitude within the expected ranges of input during the operation. The matrix converter control using direct modulation method, modified Venturini modulation method and vector modulation method was simulated, the results were compared and it was inferred that vector modulation method was superior to the other two methods. With the proposed technique, voltage transfer ratio and harmonic profile have been improved compared to the other two modulation techniques. The behaviour of the system is corroborated by MATLAB Simulink, and hardware is realized using an FPGA controller. Experimental results are found to be matching with the simulation results.

Improvement of output current waveforms using SVM technique and fuzzy logic controller for matrix converter

Purpose – The use of power electronic equipment such as conventional AC-DC-AC converters cause several problems in electrical networks and its components. They generate harmonic currents and disturb the electrical power sources; so, it is necessary to research alternative topologies of power electronic converters based on advanced intelligent controllers, which reduce or even eliminate harmonics to achieve energy-saving and environmental protection. The use of matrix converter (MC) is, considered as an attractive solution to maintain pure sinusoidal input and output current waveforms. The paper aims to discuss this issue. Design/methodology/approach – The studied system is composed of a three phase matrix converter (TMC) feeding a linear R, L load and a trees phase rectifier considered as a non-linear load; the proposed control strategy is based on a fuzzy logic controller (FLC) associated to the (space vector modulation) SVM modulation technique, this choice is motivated by the advantages that represent the combination of FLC and SVM in term of power quality enhancement in both input and output sides of MC. Findings – The model is validated based on simulation results that illustrate the effectiveness of the proposed system in term of power quality amelioration. The high performance of the proposed FLC is illustrated in all study cases especially in the case of perturbed input voltage, it is not only able to keep the whole system stable, but also it reduces harmonic distortion THD to respect international standards recommendation. Originality/value – In this paper, an associated linear (RL), non-linear loads and TMC is studied. From the mathematical point of view, the MC is modeled and analyzed. From the technique point of view, the MC allows sinusoidal current absorbance from the network with good qualities in term of harmonic distortion compensation, and high reliability under various loads and disturbed input voltage.

Control of Indirect Matrix Converter by Using Improved SVM Method

&lt;span style="font-family: &amp;quot;TimesNewRoman,Bold&amp;quot;,&amp;quot;Arial&amp;quot;; font-size: 9pt;"&gt;A novel space vector modulation (SVM) method for an indirect matrix converter (IMC) is used to reduce the common -mode voltage (CMV) in the output. The process of selecting required active vectors and to describe the switching sequence in the inverter stage of the IMC is explained in this paper. This novel SVM method used to decrease the peak -to-peak amplitude voltage of CMV without using any external hardware. The other advantage of this SVM method is to reduce the total harmonic distortion of line-to-line output voltage. This new modulation technique is easily implemented through simulation and its results are used to demonstrate the improved performance of the input/output waveforms.&lt;/span&gt;

Development of a Novel Control for a Matrix Converter Interfaced Wind Energy Conversion System for Dynamic Performance Enhancement

This article presents the development of a novel control for matrix converter interfaced permanent magnet wind energy conversion system. Here, an adaptive fuzzy control algorithm incorporated with a reversed matrix converter is proposed to yield maximum energy with enhanced dynamic performance and low harmonic characteristics. The control algorithm is implemented using a dSPACE DS1104 real-time board (dSPACE, Paderborn, Germany). Feasibility of the proposed system has been verified through simulation and experiment results using a laboratory 1.2-kW prototype of a wind energy conversion system under dynamic conditions.