Control of Indirect Matrix Converter by Using Improved SVM Method

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

Modulation Strategies for Indirect Matrix Converter: Complexity, Quality and Performance

In general, there are two main classifications in matrix converters. The most common known type is conventional matrix converter (CMC) or direct matrix converter (DMC). The other type is indirect matrix converter (IMC). A brief review for modulation strategies are provided in this work for modulation strategies in IMC. There are several popular modulation methods for IMC such as carrier-based modulation and space vector modulation (SVM). A sinusoidal current waveform is produced on the input and output sides to implement the modulation method. In the conclusion the modulation methods will compared based on performance, theoretical complexity, and some other parameters

A modified modulation scheme for three-level diode-clamped matrix converter under unbalanced input conditions

The three-level diode-clamped matrix converter topology has outstanding performance under ideal operating conditions. However, input disturbance can influence the waveforms at the output side of the converter due to the direct coupling between the input and output. This paper proposes a modified modulation scheme for three-level diode-clamped matrix converter during operation with unbalanced input voltages and when different transformer turns ratios are used for an isolation transformer at the input. With this modulation technique, sinusoidal and balanced output voltages are guaranteed and the input current harmonics are minimized. Experimental results are presented to demonstrate the feasibility and effectiveness of the proposed modulation scheme

Reliability modeling and analysis for a novel design of modular converter system of wind turbines

Converters play a vital role in wind turbines. The concept of modularity is gaining in popularity in converter design for modern wind turbines in order to achieve high reliability as well as cost-effectiveness. In this study, we are concerned with a novel topology of modular converter invented by Hjort, Modular converter system with interchangeable converter modules. World Intellectual Property Organization, Pub. No. WO29027520 A2; 5 March 2009, in this architecture, the converter comprises a number of identical and interchangeable basic modules. Each module can operate in either AC/DC or DC/AC mode, depending on whether it functions on the generator or the grid side. Moreover, each module can be reconfigured from one side to the other, depending on the system\u27s operational requirements. This is a shining example of full-modular design. This paper aims to model and analyze the reliability of such a modular converter. A Markov modeling approach is applied to the system reliability analysis. In particular, six feasible converter system models based on Hjort\u27s architecture are investigated. Through numerical analyses and comparison, we provide insights and guidance for converter designers in their decision-making

Matrix Converter Based on Trapezoidal Current Injection

The Matrix Converter (MC) is a direct AC-AC power converter featuring high power density and high efficiency. However, the conventional MC (CMC) topologies require high control complexity and high transistor capacity, hindering the wide applications. An emerging MC topology (3CI-MC) based on the third-harmonic current injection (3CI) reduces the control complexity, but require more transistors and complex clamping circuit. This paper proposes the trapezoidal current injection (TCI) technique to form a novel MC topology (TCI-MC), which consists of a line-commutated converter (LCC), a TCI circuit and a voltage source converter (VSC). Compared with the 3CI-MC, the proposed TCI-MC not only maintains the advantages of simple modulation and independent voltage control, but also achieves lower current stress on the LCC part of the circuit. The total transistor capacity of the proposed TCI-MC is the lowest among all the considered MC topologies. The clamping circuit is also simplified and the bidirectional switches are eliminated, reducing the implementation cost. Simulation and experimental results have verified the validity of the proposed topology

Improved space vector modulation with reduced switching vectors for multi-phase matrix converter

Multi-phase converter inherits numerous advantages, namely superior fault tolerance, lower per-leg power rating and higher degree of freedom in control. With these advantages, this thesis proposes an improved space vector modulation (SVM) technique to enhance the ac-to-ac power conversion capability of the multi-phase matrix converter. The work is set to achieve two objectives. First is to improve the SVM of a three-to-seven phase single end matrix converter by reducing number of space vector combinations. Second is to use the active vector of the SVM to eliminate the common-mode voltage due to the heterogeneous switching combination of a dual three-to-five phase matrix converter. In the first part, the proposed technique utilizes only 129 out of 2,187 possible active space vectors. With the reduction, the SVM switching sequence is greatly simplified and the execution time is shortened. Despite this, no significant degradation in the output and the input waveform quality is observed from the MATLAB/Simulink simulation and the hardware prototype. The results show that the output voltage can reach up to 76.93% of the input voltage, which is the maximum physical limit of a three-to-seven phase matrix converter. In addition, the total harmonics distortion (THD) for the output voltage is measured to be below 5% over the operating frequency range of 0.1 Hz to 300 Hz. For the second part, the common-mode voltage elimination is based on the cancellation of the resultant vectors (that causes the common-mode to be formed), using a specially derived active vectors of the dual matrix converter. The elimination strategy is coupled with the ability to control the input power factor to unity. The proposed concept is verified by the MATLAB/Simulink simulation and is validated using a 5 kW three-to-five phase matrix converter prototype. The SVM switching algorithm itself is implemented on a dSPACE-1006 digital signal processor platform. The results prove that the common-mode voltage is successfully eliminated from the five-phase induction motor winding. Furthermore, the output phase voltage is boosted up to 150% of the input voltage in linear modulation range

A Review on Power Electronic Topologies and Control for Wave Energy Converters

Ocean energy systems (OESs) convert the kinetic, potential, and thermal energy from oceans and seas to electricity. These systems are broadly classified into tidal, wave, thermal, and current marine systems. If fully utilized, the OESs can supply the planet with the required electricity demand as they are capable of generating approximately 2 TW of energy. The wave energy converter (WEC) systems capture the kinetic and potential energy in the waves using suitable mechanical energy capturers such as turbines and paddles. The energy density in the ocean waves is in the range of tens of kilowatts per square meter, which makes them a very attractive energy source due to the high predictability and low variability when compared with other renewable sources. Because the final objective of any renewable energy source (RES), including the WECs, is to produce electricity, the energy capturer of the WEC systems is coupled with an electrical generator, which is controlled then by power electronic converters to generate the electrical power and inject the output current into the utility AC grid. The power electronic converters used in other RESs such as photovoltaics and wind systems have been progressing significantly in the last decade, which improved the energy harvesting process, which can benefit the WECs. In this context, this paper reviews the main power converter architectures used in the present WEC systems to aid in the development of these systems and provide a useful background for researchers in this area

Fault-tolerant Partial-resonant High-frequency AC-link Converters and Their Applications

Recently, the demand for high-power-density converters with high efficiency and enhanced reliability has increased considerably. To address this demand, this dissertation introduces several low, medium, and high power converter topologies with high-frequency ac links and soft-switching operation, both with and without galvanic isolation. These converters can be in ac-ac, dc-ac, ac-dc, or dc-dc configurations to transfer power from the utility, energy storage systems, or renewable/alternative energy sources (e.g., photovoltaics, wind, and fuel cells) to stand-alone loads or the utility. The advantages of these topologies include soft switching at turn-on and turn-off of all the semiconductor devices, exclusion of short-life electrolytic capacitors in the link, step-up/down capability, and the use of a smallsized high-frequency transformer for galvanic isolation. The proposed converters are also able to generate output waveforms with arbitrary amplitude and frequency as well as achieving a high input power factor in the ac-ac and ac-dc configurations. Moreover, some of the introduced topologies have fault-tolerance capability, which may allow the converter to run even with one or more faulty switches. In this case, a partial failure will not result in the converter shutdown, and thus system availability is improved. The high-frequency ac link of the introduced converters is composed of an ac inductor and small ac capacitor. The link inductor is responsible for transferring power, while the link capacitor realizes soft-switching operation. As the link components have low reactive ratings, the converters exhibit fast dynamic responses. The inductor can be replaced by an air-gapped high-frequency transformer to achieve galvanic isolation without the need for any snubber circuits. Due to operation at a high frequency, the link transformer is substantially smaller in size and lower in weight compared to conventional line-frequency isolation transformers. In this work, the proposed power topologies are explained in detail, and their comprehensive analyses are given to reveal their functioning behavior in various working conditions. Simulation and experimental results at different operating points are also presented to verify the effectiveness of the introduced power converters

Impact of silicon carbide device technologies on matrix converter design and performance

The development of high power density power converters has become an important topic in power electronics because of increasing demand in transportation applications including marine, aviation and vehicle system. The possibility for greater power densities due to absence of a DC link is made matrix converter topologies more attractive for these applications. Additionally, with the emerging SiC device technology, the operating switching frequency and temperature of the converter can be potentially increased. The extended switching frequency and temperature range provide opportunities to further improve the power density of the power converters. The aim of this thesis is to understand how SiC devices are different from the conventional Si devices and the effect these differences have on the design and performance of a matrix converter. Specific gate drive circuits are designed and implemented to fully utilize the high speed switching capabilities of these emerging semiconductor devices. A method to evaluate the conduction and switching losses and performance of Si and SiC power devices in the matrix converter circuit is developed. The developed method is used to compare power losses of matrix converters designed with different Si and SiC devices for a range of operating temperatures and switching frequencies. A design procedure for matrix converter input filters is proposed to fulfil power quality standard requirements and maximize the filter power density. The impact of the switching frequency on the input filter volume has also been considered in this work. The output waveform distortion due to commutation time in high switching frequency SiC matrix converters is also investigated and a three-step current commutation strategy is used to minimize the problem. Finally the influence of parasitic inductance on the behaviour of SiC power MOSFET matrix converters is investigated to highlight the challenges of high speed power devices