"In the field of power electronics, designers are constantly researching new methods to improve efficiency while optimizing dynamic performance. As communication technologies progress we are more often dealing with systems of increasing speed and complexity. For instance, from 1991 to 2013 we have observed the mobile broadband communication sector evolve from ~230 Kbits/s (2G) speeds to ~100 Mbits/s (4G LTE), a 430% increase in communication speed. In contrast, we have not observed the same evolutionary development in industrial power converters. Most switch-mode power supplies are still manufactured for 100 KHz to 800 KHz operating frequencies. The main reason for this is that most electrical devices only require steady-state DC power, so high speed conversion performance is largely unnecessary. But as size expectations for portable electronic devices continue to decrease, the only way to meet future demand is to realize power electronics that operate at much higher switching frequencies. Furthermore there is increasing demand to improve the transient response requirements in processor-based systems and achieve practical envelope tracking in RF communication systems. The most straightforward method of increasing the dynamic response for these systems is to increase the switching frequency of the power electronics in a sustainable and coherent manner."--Abstract.
This thesis proposes new power converter topologies suitable for aircraft systems. It also proposes both AC-DC and DC-DC types of converters for different electrical loads to improve the performance these systems. To increase fuel efficiency and reduce environmental impacts, less efficient non-electrical aircraft systems are being replaced by electrical systems. However, more electrical systems requires more electrical power to be generated in the aircraft. The increased consumption of electrical power in both civil and military aircrafts has necessitated the use of more efficient electrical power conversion technologies. This book presents acomprehensive mathematical analysis and the design and digital simulation of the power converters. Subsequently it discusses the construction of the hardware prototypes of each converter and the experimental tests carried out to verify the benefits of the proposed solutions in comparison to the existing solutions.
Compact and efficient high-frequency power converters and amplifiers are needed in a variety of applications, including base stations, mobile devices, and medical equipment. The ever-growing need for a smaller size, longer battery life, and lower cost introduces challenging design considerations for radio-frequency power converters. Today, these radio-frequency resonant converters use harmonic tuning to shape the voltage or current waveform of the switching device, with the primary goals of reducing device stress and increasing achievable efficiency. Although harmonic-tuned resonant converters can be very compact and efficient for a certain condition, significant challenges remain to widespread adoption, including limited high-efficiency range, complicated design procedures, and higher device stress compared with conventional approaches. This thesis presents circuit techniques that can extend the voltage, frequency, and efficiency ranges of radio-frequency power converters and provides more straightforward analysis and easy-to-implement design procedures. This thesis first presents a multi-resonant gate driver circuit developed using the harmonic wave-shaping technique that significantly reduces the high-frequency gate driving losses for Si and SiC MOSFETs. By controlling different harmonic components of an ideal square wave, we can resonantly shape a quasi-square voltage waveform at the gate. This gate driver is simple to control and has a low component count. Compared with a sine wave gate signal, this method reduces the transition time between the MOSFET is fully enhanced and turned-off, driving down the switching losses. Compared with similar multi-resonant drivers that are self-oscillating, this driver reduces the long start-up time required to reach steady-state. Intuitive design methodologies based on the frequency-domain plot are introduced. Using this technique, we are able to resonantly drive a Si MOSFET at 20 MHz and recycle 60% of the hard-switching gate-driving loss. We also demonstrate this driver on a SiC MOSFET switching at 30 MHz and save 80% of the hard-switching loss. Modern applications demand power converters to maintain a constant voltage output with high efficiency across significant load variation. This thesis presents a bidirectional dc-dc converter that enables efficient fixed-ratio voltage conversion at tens of megahertz. By selecting a proper matching network for the intermediate gain stage, we address multiple challenges simultaneously; a) replacing a lossy passive diode with a more efficient active transistor, b) maintaining efficient soft-switching operation, and c) a constant voltage conversion ratio over a wide load range. A 64 MHz, 12 W, 36 V-to-12 V prototype converter with 75% peak efficiency verifies the operation of the structure. An interleaved configuration is then proposed to improve the efficiency and transient performance of a single-phase structure. A 13.56 MHz, 210 V-to-30 V prototype converter with 90% peak efficiency at 200 W demonstrates the advantages of this proposed structure. RF power amplifiers underpin many systems that support our modern infrastructure. The Class EF and E/F family of harmonic-tuned switch-mode amplifiers have simple gate drives, reduced voltage stress, and higher output power capabilities than a conventional Class E circuit. To best utilize the performance potential of this family of circuits, this thesis presents a novel push-pull Phi2 (EF2) amplifier using interleaving and series-stacking techniques, denoted as a PPT Phi2 circuit. This series-stacked PPT Phi2 circuit combines all of the main advantages of different topologies, like the simplicity of gate driving, highest cut-off frequency, lowest voltage stress, and load-invariant operation. A compact 6.78 MHz, 100 V, 300 W prototype converter is demonstrated. Using lowcost Si devices, the prototype converter achieves 96% peak total efficiency and maintains above 94.5% drain efficiency across a wide range of voltage and power. This new series-stacked PPT F2 RF amplifier doubles the maximum operating frequency and voltage range of a Class EF or E/F amplifier with benefits in many modern applications that require high-frequency high-power RF signals, like wireless charging for electric vehicles, plasma RF drives, and nuclear magnetic resonance (NMR) spectroscopy.
A wideband hybrid envelope tracking modulator utilizing a hysteretic-controlled three-level switching converter and a slew-rate enhanced linear amplifierer is presented. In addition to smaller ripple and lower losses of three-level switching converters, employing the proposed hysteresis control loop results in a higher speed loop and wider bandwidth converter, enabling over 80MHz of switching frequency. A concurrent sensor circuit monitors and regulates the flying capacitor voltage VCF and eliminates conventional required calibration loop to control it. The hysteretic-controlled three-level switching converter provides a high percentage of power amplifier supply load current with lower ripple, reducing the linear amplifier high-frequency current and ripple cancellation current, improving the overall system efficiency. A slew-rate enhancement (SRE) circuit is employed in the linear amplifier resulting in slew-rate of
In this book, nine papers focusing on different fields of power electronics are gathered, all of which are in line with the present trends in research and industry. Given the generality of the Special Issue, the covered topics range from electrothermal models and losses models in semiconductors and magnetics to converters used in high-power applications. In this last case, the papers address specific problems such as the distortion due to zero-current detection or fault investigation using the fast Fourier transform, all being focused on analyzing the topologies of high-power high-density applications, such as the dual active bridge or the H-bridge multilevel inverter. All the papers provide enough insight in the analyzed issues to be used as the starting point of any research. Experimental or simulation results are presented to validate and help with the understanding of the proposed ideas. To summarize, this book will help the reader to solve specific problems in industrial equipment or to increase their knowledge in specific fields.
Envelope tracking technology is seen as the most promising efficiency enhancement technology for RF power amplifiers for 4G and beyond wireless communications. More and more organizations are investing and researching on this topic with huge potential in academic and commercial areas. This is the first book on the market to offer complete introduction, theory, and design considerations on envelope tracking for wireless communications. This resource presents you with a full introduction to the subject and covers underlying theory and practical design considerations.
An invaluable academic reference for the area of high-power converters, covering all the latest developments in the field High-power multilevel converters are well known in industry and academia as one of the preferred choices for efficient power conversion. Over the past decade, several power converters have been developed and commercialized in the form of standard and customized products that power a wide range of industrial applications. Currently, the modular multilevel converter is a fast-growing technology and has received wide acceptance from both industry and academia. Providing adequate technical background for graduate- and undergraduate-level teaching, this book includes a comprehensive analysis of the conventional and advanced modular multilevel converters employed in motor drives, HVDC systems, and power quality improvement. Modular Multilevel Converters: Analysis, Control, and Applications provides an overview of high-power converters, reference frame theory, classical control methods, pulse width modulation schemes, advanced model predictive control methods, modeling of ac drives, advanced drive control schemes, modeling and control of HVDC systems, active and reactive power control, power quality problems, reactive power, harmonics and unbalance compensation, modeling and control of static synchronous compensators (STATCOM) and unified power quality compensators. Furthermore, this book: Explores technical challenges, modeling, and control of various modular multilevel converters in a wide range of applications such as transformer and transformerless motor drives, high voltage direct current transmission systems, and power quality improvement Reflects the latest developments in high-power converters in medium-voltage motor drive systems Offers design guidance with tables, charts graphs, and MATLAB simulations Modular Multilevel Converters: Analysis, Control, and Applications is a valuable reference book for academic researchers, practicing engineers, and other professionals in the field of high power converters. It also serves well as a textbook for graduate-level students.
This book covers advancements of power electronic converters and their control techniques for grid integration of large-scale renewable energy sources and electrical vehicles. Major emphasis are on transformer-less direct grid integration, bidirectional power transfer, compensation of grid power quality issues, DC system protection and grounding, interaction in mixed AC/DC system, AC and DC system stability, magnetic design for high-frequency high power density systems with advanced soft magnetic materials, modelling and simulation of mixed AC/DC system, switching strategies for enhanced efficiency, and protection and reliability for sustainable grid integration. This book is an invaluable resource for professionals active in the field of renewable energy and power conversion.
Resonant power converters have many applications in the computer industry, telecommunications and in industrial electronics. Their advantage over traditional converters lies in their ability to transform power at very high frequencies. This book discusses resonant power converters.
