DIGITAL PWM OF AC-AC MATRIX CONVERTER BASED ON OUTPUT-VOLTAGE ERROR FUNCTION

Based on the output-voltage error function, a novel time discrete modulation technique is proposed for matrix converters （MCs） and time-discrete difference equations of a MC circuit are derived. Switch states of MC are obtained when the output voltage error function is minimized, thus the optimum combination of switch states is derived for the closed-loop control of MC. Meanwhile, advantages of the least calculation workload, the simple process, and the convenient for implementation are brought while switch states are described as space vectors in the α-β coordination system. Simulation and experimental results demonstrate the validity of the time-discrete modulation technique and the feasibility of the control approach.

Model predictive torque control of permanent magnet synchronous motor system driven by matrix converter

Employing matrix converter （MC） as driving mode, the strategy of model predictive torque control （MPTC） is proposed for three phase permanent magnet synchronous motor （PMSM） system. MC is applied instead of conventional AC DC AC converter to increase the power factor （PF） of the system input side. MPTC is used to select optimal voltage space vector to enable the system to have satisfactory torque and flux control effect. The resultant MPTC strategy not only makes the MC fed PMSM system operate reliably and have perfect control performance, but also makes the PF of the system input side be 1. Compared with direct torque control （DTC）, the proposed MPTC strategy guarantees that MC fed PMSM has better command following characteristics in the presence of variation of load torque and tracking reference speed. Simulation results verify the feasibility and effectiveness of the proposed strategy.

Model Predictive Control-Based Direct Torque Control for Matrix Converter-Fed Induction Motor with Reduced Torque Ripple

To reduce the torque ripple in motors resulting from the use of conventional direct torque control(DTC),a model predictive control(MPC)-based DTC strategy for a direct matrix converter-fed induction motor is proposed in this paper.Two new look-up tables are proposed,these are derived on the basis of the control of the electromagnetic torque and stator flux using all the feasible voltage vectors and their associated switching states.Finite control set model predictive control(FCS-MPC)has then been adopted to select the optimal switching state that minimizes the cost function related to the electromagnetic torque.Finally,the experimental results are shown to verify the reduced torque ripple performance of the proposed MPC-based DTC method.

AC/DC Matrix Converters for V2G Applications

由于当前V2G系统中普遍采用的电压型脉宽调制（pulse width modulation,PWM）整流方案中所存在的蓄电池电压匹配、功率体积比及系统效率问题,提出一种采用AC/DC矩阵变换器的解决方案。针对经典电流空间矢量调制策略中充电电流纹波较大的缺点,提出一种在全输出范围内减小充电电流纹波的分段优化调制策略,并深入对比分析这两种调制策略下充电电流纹波的大小。仿真和实验结果表明,所提分段优化调制策略的正确性和可行性。

High Performance Control of Matrix Converter Fed Induction Motor Drive System

Matrix converter fed motor drive is superior to pulse width modulation inverter drives since it not only provides bi-directional power flow,sinusoidal input/output currents,unity input power factor,but also allows a compact design due to the lack of DC-link capacitors for energy storage.In this paper,model and control of matrix converter fed induction motor drive system are analyzed.A combined control strategy is simplified and improved,which realizes space vector pulse width modulation of matrix converter and rotor flux oriented vector control technique for induction motor drive simultaneously.This control strategy combines the advantages of matrix converter with the good drive performance of vector control technique.Experimental results demonstrate the feasibility and effectiveness of the proposed control strategy.

Short-circuit fault analysis and isolation strategy for matrix converters

The behavior of matrix converter(MC) drive systems under the condition of MC short-circuit faults is comprehensively investigated. Two isolation strategies using semiconductors and high speed fuses(HSFs) for MC short-circuit faults are examined and their performances are compared. The behavior of MC drive systems during the fuse action time under different operating conditions is explored. The feasibility of fault-tolerant operation during the fuse action time is also studied. The basic selection laws for the HSFs and the requirements for the passive components of the MC drive system from the point view of short-circuit faults are also discussed. Simulation results are used to demonstrate the feasibility of the proposed isolation strategies.

PI and RST Control Design and Comparison for Matrix Converters Using Venturini Modulation Strategy

This paper presents a thorough design and comparative study of two popular control techniques, i.e., classical Proportional Integral (PI) and RST, for Matrix Converters (MCs) in terms of tracking the reference and robustness. The output signal of MCs is directly affected by unbalanced grid voltage. Some research works have attempted to overcome this problem with PI control. However, this technique is known to offer lower performance when it is used in complex and nonlinear systems. On the other hand, RST control offers better performance, even in case of highly nonlinear systems. Therefore, the RST can achieve better performance to overcome the limitation of PI control of nonlinear systems. In this paper, a RST control method is proposed as output current controller to improve the performance of the MC powered by unbalanced grid voltage. The overall operating principle, Venturini modulation strategy of MC, PI control and characteristics of RST are presented.

Research of matrix converter based on asymmetric regular sampling method SPWM control strategy

Based on the topological analysis of three-phase matrix AC to AC conversion circuit, an AC to AC nine-switch matrix isequivalent to rectification part and conversion part. The Matrix converter can be viewed as AC-DC-AC converter, the asymmetricregular sampling method SPWM(Sine Pulse Width Modulation) is studied and applied in the three-phase matrix AC to AC converter,Based on Matlab/simulink the simulation of the matrix converter with such strategy is carried out. Inductive load simulation is carriedout on the matrix converter prototype. The simulation results verify the workability of the asymmetric regular sampling method SPWMstrategy for matrix converter.

Control of Doubly Fed Induction Generator Supplied via Matrix Converter for Wind Energy Conversion System

The present paper deals with the modeling and control of Wind Energy Conversion System WECS based Doubly Fed Induction Generator DFIG using the slip energy recovery principle. The proposed drive system uses a Matrix Converter (MC) to transfer the slip energy of the rotor into the mains instead of using cascaded ac-dc-ac converter whilst the stator side is fixed to the grid. Operation at both sub-synchronous and super-synchronous regions is possible with the proposed drive system. The different level control strategies for maximum power point tracking and active-reactive power are discussed. Simulation results of the proposed doubly fed induction generator drive system show the good performance of the control system strategy for both transient and steadystate conditions.

Three Phase Dual Input Direct Matrix Converter for Integration of Two AC Sources from Wind Turbines

This project proposes a novel dual-input matrix converter (DIMC) which is used to integrate the output of the wind energy 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 followed by the current source inverter (CSI). Matrix electric power conversion topologies and their switch functions are flexible and are used for specific applications. With the additional three switches, the proposed DIMC can provide six input terminals, which make it possible to integrate two independent AC sources from two independent wind turbines into a single grid tied power electronics interface. Commanded currents can be extracted from the two input sources to the grid. The proposed PI control and modulation schemes guaranteed sinusoidal input and output waveforms as well as reduced THD. The simulation results are provided to validate the effectiveness of the proposed control and modulation schemes for the proposed converter.

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.

Model Predictive Control Circuit of the Current Source Matrix Converter

In this paper, a new predictive control strategy for current source matrix converter (CSMC) is presented. Proposed predictive control strategy allows for creating output voltages with boost type voltage transfer ratio and desired frequency. The description of predictive control circuit of the CSMC is presented. Furthermore the simulation test results to confirm functionality of the proposed control strategy and converter properties under this strategy are shown.

A Novel Approach to Practical Matrix Converter Motor Drive System With Reverse Blocking IGBT (To continue)

a Pole voltage waveforms (VA20 and VA40) for modulation index 0.4 (middle trace is A-phase voltage waveform) x-axis: 1 div.=10ms, y-axis: 1 div.= 100V b Normalized harmonic spectrum for pole voltage of Fig. 9a c A-phase current and phase voltage for modulation index 0.4 (reference space vector is in inner layer)

A Novel Approach to Practical Matrix Converter Motor Drive System With Reverse Blocking IGBT

a Pole voltage waveforms (VA20 and VA40) for modulation index 0.4 (middle trace is A-phase voltage waveform) x-axis: 1 div.=10ms, y-axis: 1 div.= 100V b Normalized harmonic spectrum for pole voltage of Fig. 9a c A-phase current and phase voltage for modulation index 0.4 (reference space vector is in inner layer)

Comparison of Properties of Tumor Necrosis Factor-α Converting Enzyme (TACE) and Some Matrix Metalloproteases (MMPs) in Catalytic Domains

The crystal structural data of TACE, MMP-1, MMP-2, MMP-3 and MMP-9 were obtained from PDB database, and then their catalytic domains＇ properties including conformation, molecular surface hydrophobicity and electrostatic potential were analyzed and compared by using Insight II molecular modeling software. It was found that the conformation and molecular surface hydrophobicity of catalytic domains of TACE and MMPs were not obviously different, but the molecular surface electrostatic potential of catalytic domain of TACE＇ and MMPs had obvious differences. The findings are helpful in the Rational Drug Design of TACE selective inhibitor.

Investigation of matrix effects in the MC-ICP-MS induced by Nb, W, and Cu: Isotopic case studies of iron and copper

Some elements normally occur at trace levels while the majority of natural geological materials may be exceedingly enriched in some special cases, such as the Bayan Obo ore deposit where REE and Nb are extremely enriched. These elements may not be removed completely during purification. Therefore, matrix effects will be caused during stable isotope ratio measurement in the MC-ICP-MS. Experiments have shown that the established methods of chromatographic separation of Cu, Fe, and Zn using AG MP-1 Anion Exchange Resin cannot make ef-fective separation of Nb, W, and Cu from Fe using 20 mL 6 M HCl. It is also observed that the elution curves of W and Cu overlap at working conditions and thus W is present in measurable amounts in some sample solutions. Matrix effects in the MC-ICP-MS induced by Nb, W, and Cu during Fe isotope ratio measurements and by W during Cu isotope ratio measurements were thus investigated by examining their changes in delta values between doped and undoped standards. The results show that the effects of the matrix elements Nb, W, or Cu on Fe isotope ratio measurements are minimal in the case of m(Nb)/m(Fe)<0.005, m(W)/m(Fe)<0.01, or m(Cu)/m(Fe)<0.6. This finding, combined with the extremely low levels of W and Cu, and the fact that nearly 90% of Nb can be removed during purification, demonstrates that the methods of chromatographic separation of Fe established before are suitable for Bayan Obo ore samples and that the methods can be simplified when Cu elution is unnecessary. The effects of the matrix element W on Cu isotope determinations are minimal in the case of m(W)/m(Cu)<0.7. Therefore, W exerts no significant effect on the measurements of Cu isotopes for the majority of natural geological materials.

Advance in Matrix Effect Study of LA-MC-ICPMS U-Pb Dating on U-Bearing Oxide Minerals

Objective With the development of analytic technologies, in-situ dating on U-bearing oxide minerals （e.g., cassiterite, rutile and baddeleyite） has been widely used in geological chronological researches and has attracted remarkable attention to explore evolution of the earth and obtain age information of various geological processes. Matrix effect related studies are especially important during in-situ U- Pb dating based on Laser Ablation Multiple Collector Inductively Coupled Plasma Mass Spectrometry （LA-MC- ICPMS）. However, to our knowledge, only few thorough and systematical matrix effect study of U-bearing oxide minerals has been reported. In this study, we systematically analyzed the matrix effect of U-bearing oxide minerals in order to take place the standards which are difficult to prepare with available standards.

Dynamical Analysis of Nonlinear Bifurcation in Current-Controlled Boost Converter

Based on the bifurcation theory in nonlinear dynamics, this paper analyzes quantitatively period solution dynamic characteristic. In particular, the ones of period-1 and period-2 solutions are deeply studied. From locus of Jacobian matrix eigenvalue, we conclude that the bifurcations between period-1 and period-2 solutions are pitchfork bifurcations while the bifurcations between period-2 and period-3 solutions are border collision bifurcations. The double period bifurcation condition is verified from complex plane locus of eigenvalues, furthermore, the necessary condition occurred pitchfork bifurcation is obtained from the cause of border collision bifurcation.

A General Approach for Direct Conversion of Single Phase AC to AC Converter for Induction Heating System

This paper signifies the study of modeling and simulation of a single phase matrix converter for induction heating system. The working principle and the control method, using PID are revealing in detail. The performance of the system is carried out in MATLAB/Simulink environment with pulse width modulation switching strategy by varying the duty cycle. PID control is employed to obtain the better performance for a specified input supply for various output frequencies. The proposed control strategy of AC to AC converter has been discussed with a wide range of operating frequencies and results in low Total Harmonic Distortion.