This paper presents a comprehensive study on the state-of-the-art and emerging wind energy technologies from the electrical engineering perspective. In an attempt to decrease cost of energy, increase the wind energy conversion efficiency, reliability, power density, and comply with the stringent grid codes, the electric generators and power electronic converters have emerged in a rigorous manner. From the market based survey, the most successful generator-converter configurations are addressed along with few promising topologies available in the literature. The back-to-back connected converters, passive generator-side converters, converters for multiphase generators, and converters without intermediate dc-link are investigated for high-power wind energy conversion systems (WECS), and presented in low and medium voltage category. The onshore and offshore wind farm configurations are analyzed with respect to the series/parallel connection of wind turbine ac/dc output terminals, and high voltage ac/dc transmission. The fault-ride through compliance methods used in the induction and synchronous generator based WECS are also discussed. The past, present and future trends in megawatt WECS are reviewed in terms of mechanical and electrical technologies, integration to power systems, and control theory. The important survey results, and technical merits and demerits of various WECS electrical systems are summarized by tables. The list of current and future wind turbines are also provided along with technical details.

High-Power Wind Energy Conversion Systems: State-of-the-Art and Emerging Technologies

This paper presents a review of the most popular control and modulation strategies studied for matrix converters (MCs) in the last decade. The purpose of most of these methods is to generate sinusoidal current on the input and output sides. These methods are compared considering theoretical complexity and performance. This paper concludes that the control strategy has a significant impact on the resonance of the MC input filter.

A Review of Control and Modulation Methods for Matrix Converters

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.

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

A novel three-phase AC-DC-AC sparse matrix converter (SMC) having no energy storage elements in the DC link and employing only 15 IGBTs as opposed to 18 IGBTs of a functionally equivalent conventional AC-AC matrix converter (CMC) is proposed. It is shown that the realization effort could be further reduced to only 9 IGBTs (ultra sparse matrix converter, USMC) in case the phase displacement of the fundamentals of voltage and current at the input and at the output is limited to /spl plusmn//spl pi//6. The dependency of the voltage and current transfer ratios of the systems on the operating parameters is analyzed and a space vector modulation scheme is described in combination with a zero current commutation procedure. Furthermore, a safe multi-step current commutation concept is treated briefly. Conduction and switching losses of the SMC and USMC are calculated in analytically closed form. Finally, the theoretical results are verified in Part II of the paper by digital simulations and results of a first experimental investigation of a 10 kW/400 V SMC prototype are given.

Novel three-phase AC-DC-AC sparse matrix converter

An uninterruptible power supply (UPS) system includes an AC power input configured to receive AC power from a single-phase AC power source or a multi-phase AC power source, a DC power source, an output circuit including a power output, a controllable switch configured to selectively couple at least one of the AC power input and the DC power source to the output circuit, and a processor coupled and configured to affect operation of the output circuit depending upon which of single-phase and multi-phase operation of the UPS is indicated.

Uninterruptible power supply

An alternating-current/direct-current converter includes a rectifier, a reactor, a capacitor, and a switching rectifier. The rectifier is configured to rectify alternating-current voltage output from an alternating-current power source, thereby converting the alternating-current voltage into direct-current voltage, and to output the direct-current voltage. The capacitor includes terminals. The switching rectifier is coupled to the AC power source and switchable to output the direct-current voltage to the capacitor.

Alternating-current/direct-current converter

The matrix converter is an AC-to-AC direct power conversion system that can generate variable voltage variable frequency output. There is a topology of Matrix converter having sinusoidal waveforms using output LC filter. It enabled that to provide lower EMI, lower common-mode current, and lower shaft voltage. However, there are some problems that filter size become bulky because of the restriction of switching speed using conventional power module, Silicon IGBT. Downsizing of input-output filter can be realized by employing SiC power devices since they are associated with low losses and can be operated at high frequency. In this paper, the use of SiC power devices in matrix converters is studied and its effect in reducing the size of the input and output filter is verified. A prototype was built for evaluations and the results are presented.

Matrix converter with sinusoidal input-output filter and filter downsizing using SiC devices

PROBLEM TO BE SOLVED: To avoid generation of large vibrations in an input current, even if the output voltage is multiplexed, regardless of the synchronization or asynchronization of switching carrier frequency with the frequency of power supply voltage. SOLUTION: A control device for three-phase/single-phase PWM cycloconverter has a power supply voltage information detecting section 22, an input current distribution factor generating section 24 outputting the ratio of the minimum value to intermediate value as an input current distribution factor among the absolute values of input current commands in the phase of input current command, an input information generating section 25, a switching pattern creating section 26, a switch signal generating section 29 generating and outputting on/off signals of carrier period of six bidirectional switches 11 to 16, and a bidirectional switch drive section 30.

Controller for three-phase/single-phase pwm cycloconverter

PROBLEM TO BE SOLVED: To provide a power semiconductor module capable of absorbing a surge voltage generated in a module, and to provide a bidirectional power supply unit using the same. SOLUTION: In the power semiconductor module where semiconductor devices provided with a pair of diodes and having self arc-extinguishing capability are inversely parallel-connected with each other to bidirectionally transmit power, an anode terminal of the diode and an output terminal of the semiconductor device are connected with a first terminal and a second terminal of the power semiconductor module, and all of the cathode terminals of the diode and the input side terminals of the semiconductor device are connected with a third terminal. COPYRIGHT: (C)2004,JPO

Power semiconductor module and bidirectional power supply unit using the same

PROBLEM TO BE SOLVED: To provide an apparatus for detecting a voltage/current polarity, by which the voltage/current polarity of both terminals of a bidirectional switch can always be detected, even when a voltage is high or low. SOLUTION: In this detection apparatus, the polarity of a voltage applied across both ends x, y of a semiconductor switch 11, by which a current can flow in both directions, is detected. At least one terminal of both specific terminals a, b of a voltage-limiting circuit 12 which limits a voltage across both terminals a, b is connected in series with a resistance 5 and is connected in parallel with both ends x, y of the semiconductor switch. Both ends of a voltage-polarity discrimination circuit 13, by which the polarity of the voltage applied across both the ends x, y of the semiconductor switch 11 is discriminated on the basis of the polarity of the voltage across both the terminals a, b are connected to both the terminals a, b of the voltage limiting circuit 12.

Apparatus for detecting voltage/current polarity

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