A Novel Power Conversion Approach for Single Phase Systems

A novel single phase rectification technique with a new architecture and control scheme is proposed. The new rectifier consists of switched capacitor branch in parallel with the diode bridge rectifier. The switched capacitor branch includes a capacitor and a bidirectional switch arranged in series so the switch can control the charging and discharging of the capacitor. The control strategy is carefully designed to ensure the output voltage of the rectifier is above a chosen threshold level and to maintain high input power factor with reduced line current harmonics. Circuit configuration, design parameters, principles of operation and the mathematical analysis are presented. The new architecture provides a reduction in the size of the DC side capacitor. This reduction can be as low as less than 10% of the size of the typical smoothing capacitor in the conventional single phase rectifier. The proposed concept is verified by the experimental results over a range of case studies. A novel buck-boost DC-DC converter architecture is also proposed. This converter utilises the close inversely-coupled inductors topology in both its conversion stages (buck and boost). The new converter aims to reduce the switching noise that usually accompanies the buck and boost circuits. This can be done by maintaining a continuous flow of current in both converter stages which results in a large reduction in the back e.m.f induced in the main inductor and thus reduces the switching noise. The new converter architecture also provides a unique design of the passive clamped circuit. This circuit is used to recycle the leakage energies of the coupled inductors which results in an efficiency improvement of the converter and to limit the voltage stress on the power switches. Circuit con figuration, principles of operation and the transfer function are presented. The proposed concept is verified by the experimental and the simulated results of a range of case studies. The highest achieved efficiency observed in the experiments was 97:7%.MOHES

Harmonic modelling and characterisation of modern power electronic devices in low voltage networks

Although the overall levels of harmonics in modern power supply systems are in most of the practical cases still below the prescribed tolerance limits and thresholds (e.g. these stipulated in [IEC 61000-3-2 and 61000-3-12]), the sources of harmonics are constantly increasing in numbers and are expected to increase even more in the future. Some of the examples of modern non-linear power electronic (PE) devices that are expected to be employed on a much wider scale in LV networks in the future include: light-emitting diode (LED) lamps, switched-mode power supplies (SMPS’), electric vehicle battery chargers (EVBCs) and photovoltaic inverters (PVIs), which are all analysed in this thesis. The thesis first reviews the conventional harmonic analysis methods, investigating their applicability to modern PE devices. After that, the two most widely used forms of harmonic models, i.e. component-based models (CBMs) and frequency-domain models (FDMs), are applied for modelling of the four abovementioned types of modern PE devices and their models are fully validated by measurements. The thesis next investigates the impact of supply voltage conditions and operating modes (e.g. low vs high operating powers) on the device characteristics and performance, using both measurements and developed CBMs and FDMs. The obtained results confirm that both supply conditions and operating modes have an impact on the characteristics of most of the considered PE devices, which is taken into account in the developed models and demonstrated on a number of case studies. As the next contribution, the thesis proposes new indices for the evaluation of current waveform distortions, allowing for a separate analysis of contributions of low and high frequency harmonics and interharmonics to the total waveform distortion of PE devices. As the modern PE devices are normally based on high-frequency switching converters or inverters, the impact of circuit topologies and control algorithms on their harmonic emission characteristics and performance is also investigated. Special attention is given to the operation of PE devices at low powers, when there is a significant increase of current waveform distortion, a substantial decrease of efficiency and power factors and when input ac current might lose its periodicity with the supply voltage frequency. This is analysed in detail for SMPS’, resulting in the proposal of a new methodology (“operating cycle based method”) for evaluating overall performance of PE devices across the entire range of operating powers. Finally, a novel and simple hybrid harmonic modelling technique, allowing for the use of both time-domain and frequency-domain models in the same simulation environment, is proposed and illustrated on the selected case studies. This is accompanied with a frequency-domain aggregation approach, which is applied in the thesis to investigate the impact of increasing numbers of different types of modern PE devices on the LV network. The implementation of the developed hybrid harmonic modelling approach and frequency-domain aggregation technique is demonstrated on the example of a typical (UK) urban generic LV distribution network and used for the analysis of different deployment levels of EVs and PVIs. The presented harmonic modelling framework for individual PE devices and, particularly, for their aggregate models, fills the gap in the existing literature on harmonic modelling and characterisation of modern PE devices, which is important for the correct evaluation of their harmonic interactions and analysis of the impact of their large-scale deployment on the overall network performance

Proceedings of the 6th International Conference EEDAL'11 Energy Efficiency in Domestic Appliances and Lighting

This book contains the papers presented at the sixth international conference on Energy Efficiency in Domestic Appliances and Lighting. EEDAL'11 was organised in Copenhagen, Denmark in May 2011. This major international conference, which was previously been staged in Florence 1997, Naples 2000, Turin 2003, London 2006, Berlin 200h9a s been very successful in attracting an international community of stakeholders dealing with residential appliances, equipment, metering liagnhdti ng (including manufacturers, retailers, consumers, governments, international organisations aangde ncies, academia and experts) to discuss the progress achieved in technologies, behavioural aspects and poliacineds , the strategies that need to be implemented to further progress this important work. Potential readers who may benefit from this book include researchers, engineers, policymakers, and all those who can influence the design, selection, application, and operation of electrical appliances and lighting.JRC.F.7-Renewable Energ

バレーフィルスナバの開発とパワーコンバータへの応用

近年、再生可能エネルギーなどの普及や電カエネルギーの高効率利用の社会的背景に基づいて、半導体電力変換装置の用途が拡大すると共に、更なる高効率化や高電力密度化が求められている。現在、電力変換装置に用いられる電力用パワーデバイスとしてはSiデバイスが広く利用されているが、次世代パワーデバイスとしてSicやGaNなどのデバイスの導入も進められている。Sicデバイスは、Siデバイスと比べて、低オン電圧と高速スイッチングが可能であることから半導体電力変換装置の高電力密度化が期待されている。しかし、スイッチング速度が高速であるためにスイッチング時に過大なサージ電圧が発生することに加えてEMIノイズの増加につながる。特に中・大容量の電力変換装置では、大形のパワーモジュールを使用する必要があるが、直流電源とパワーデバイスの間の配線インダクタンスが十分に低減できず、上記の問題の解決が困難になる。一方、Siデバイスは、SiCデバイスと比較して製造コストが低いため、多くの半導体電力変換装置において今後も使用されるものと考えられる。Siデバイスは、次世代パワーデバイスと比較してスイッチング速度が遅く、またターンオフ時にテール電流が発生するため、スイッチング損失の増加が課題となる。これらの問題に対して、従来は直流バスのコンデンサとパワーモジュール間の配線にラミネートバスバーを使用することやパワーモジュールのP-N端子間にRCDスナバ回路等を接続していた。しかしこれらの方法ではSiCデバイスの高速スイッチング動作への対応、あるいはSiデバイスのスイッチング損失の低減には限界がある。そこで本研究では、従来法のラミネートバスバーやRCDスナバ回路を用いる方法に代わる新しいスナバ回路の開発を行う。これは、従来デバイスのSiや次世代デバイスのSiCを用いた場合においても効果的となるように設計する。まず、既存の整流平滑回路に使用されてきたバレーフィル回路の充放電特性を応用した新しいスナバ回路(バレーフィルスナバ)が提案回路である。提案回路では、効率的にサージ電圧を抑制できることが可能であるか確認し、回路設計を行った。その後、SiC-MOSFETパワーモジュールおよびSi-IGBTパワーモジュールを使用し、出力電力4kVAの三相PWMインバータ回路で実機検証し、サージ電圧を抑制するハードスイッチング型バレーフィルスナバの開発とパワーコンバータへの応用を行った。この方式は、サージ電圧の抑制は可能であるがEMIノイズやスイッチング損失の低減が困難である。そこで低減ためにソフトスイッチング方式を採用し、ソフトスイッチング型バレーフィルスナバに拡張した。ソフトスイッチング方式は、サージ電圧の抑制に加えてEMIノイズとスイッチング損失の低減が可能であるが、大形のパワーモジュールの持つ寄生キャパシタの影響で低減効果が下がってしまうことからさらなる改良が必要である。これらを踏まえてソフトスイッチング改良型バレーフィルスナバを開発し、サージ電圧の抑制、EMIノイズとスイッチング損失の低減およびスナバ方式の違いによる電力変換効率を比較し、検証を行い、提案法の有用性を示した。首都大学東京, 2018-03-25, 修士（工学）首都大学東

Друга міжнародна конференція зі сталого майбутнього: екологічні, технологічні, соціальні та економічні питання (ICSF 2021). Кривий Ріг, Україна, 19-21 травня 2021 року

Second International Conference on Sustainable Futures: Environmental, Technological, Social and Economic Matters (ICSF 2021). Kryvyi Rih, Ukraine, May 19-21, 2021.Друга міжнародна конференція зі сталого майбутнього: екологічні, технологічні, соціальні та економічні питання (ICSF 2021). Кривий Ріг, Україна, 19-21 травня 2021 року