Analysis, design and implementation of a residential inductive contactless energy transfer system with multiple mobile clamps

This study presents the analysis, design and implementation of a simple and cost-effective residential inductive contactless energy transfer system with multiple mobile clamps. The topology is based on the cascaded connection of a buck converter and a high-frequency resonant inverter loaded by several output passive rectifiers. The proposed system includes a sliding transformer to supply the mobile loads, leading to a safe and flexible location of loads. The theoretical analysis and design of the proposed system is based on a mathematical model derived using the first harmonic approximation. Selected experimental results are included to verify the system features. In comparison with conventional topology, the proposed system significantly improves efficiency, complexity and cost.Peer ReviewedPostprint (author's final draft

Pregled stanja u području bezkontaktnog prijenosa električne energije: primjene, izazovi i trendovi

Methods of contactless electrical power transfer technologies have been surveyed and results are presented here. In this among, the inductive based contactless electrical power transfer systems are investigated in more detail. The principles, structures and operations of the systems as well as their methods presented in the literature are reviewed and their applications are explored. Also, current challenges and opportunities and future trends are noted. An effective index is proposed to compare different contactless power transfer systems describing their present statuses and the future trends. Finally, some remarks and recommendations regarding future studies are proposed.U radu je dan prikaz različitih tehnologija u području bezkontaktnog prijenosa električne energije. U radu je naglasak na indukcijom baziranim sustavima bezkontaktnog prijenosa električne energije. Pregledom literature utvrðeni su koncepti, strukture i način rada pojedinih sustava bezkonaktnog prijenosa kao i njihove primjene. Također, zabilježeni su trenutni izazovi, prilike i trendovi. Predložen je efektivni indeks za vrednovanje sustava bezkontaktnog prijenosa električne energije s ciljem komparativne analize različitih sustava opisanih trenutnim statusom i trendovima. Konačno, dan je kritički osvrt i predložene su preporuke za buduće studije

An Effective Experimental Optimization Method for Wireless Power Transfer System Design Using Frequency Domain Measurement

This paper proposes an experimental optimization method for a wireless power transfer (WPT) system. The power transfer characteristics of a WPT system with arbitrary loads and various types of coupling and compensation networks can be extracted by frequency domain measurements. The various performance parameters of the WPT system, such as input real/imaginary/apparent power, power factor, efficiency, output power and voltage gain, can be accurately extracted in a frequency domain by a single passive measurement. Subsequently, the design parameters can be efficiently tuned by separating the overall design steps into two parts. The extracted performance parameters of the WPT system were validated with time-domain experiments

Control method for wireless inductive energy transfer systems with relatively large air gap

Recent improvements in semiconductor technology make efficient switching possible at higher frequencies, which benefits the application of wireless inductive energy transfer. However, a higher frequency does not alter the magnetic coupling between energy transmitter and receiver. Due to the still weak magnetic coupling between transmitting and receiving sides that are separated by a substantial air gap, energy circulates in the primary transmitting side without being transferred to the secondary receiving side. This paper introduces an energy control method that reduces energy circulation in the primary to zero. Themethod makes use of the fact that energy can be stored in a magnetic field by the primary side and absorbed by the secondary side. Furthermore, the secondary side converter topology is modified in order to boost the damping as seen by the primary converter at required times. Essentially, the control method realizes an energetic coupling factor of one between the air coils of the wireless transformer. The working principle of the controlmethod has been verified with an experimental setup.Peer Reviewe

Design and Construction of a Dynamic Wireless Power Transfer System Applied to Battery Charging in Electric Vehicles

Cada día, los vehículos tienden a sustituir a los de combustión y se apoyan en la energía eléctrica, que tiene muchas ventajas desde el punto de vista medioambiental. Con el paso de los años, su eficiencia ha aumentado; sin embargo, existe un gran reto en el diseño de baterías de larga duración para los desplazamientos por carretera, además, el periodo de carga de las baterías aún está en investigación. En esta tesis se presenta el diseño de un sistema dinámico de transferencia de energía inalámbrica aplicado a los vehículos eléctricos. Se describe el análisis de la topología de compensación S-P, utilizando un acoplamiento inductivo resonante para WPT y un enfoque en la optimización de la geometría de la bobina para medir la eficiencia de la transferencia de potencia. Por lo tanto, se propone un sistema de transferencia de potencia dinámica de baja potencia para vehículos eléctricos que opera a una frecuencia de 85 kHz utilizando componentes semiconductores SiC de alta eficiencia y una bobina circular planar. El diseño se divide en dos circuitos; el primero consiste en un circuito transmisor que incluye una fuente de CC y mediante un inversor de medio puente convertir la potencia de CC en potencia de CA de alta frecuencia para transmitir la potencia que entra en la bobina Tx. Luego, está el segundo circuito, que es la parte receptora donde la bobina Rx recibe la energía que se transfiere a la resistencia de carga RL. Adicionalmente, se diseña un controlador PI para mantener una tensión constante bajo diferentes variaciones de distancia entre las bobinas y garantizar la transferencia de energía. Los resultados experimentales adquiridos muestran que el sistema alcanza una eficiencia del 65% para 55 mm y llega a 85 mm como distancia máxima de transferencia, lo que para un sistema de baja potencia es prometedor para implementar el DWPT para vehículos eléctricos, donde no requiere mayor intervención humana, y sin ocupar mucho espacio.Every day, vehicles are tending to replace combustion vehicles and rely on electric energy, which has many advantages from an environmental point of view. Over the years, their efficiency has increased; however, there is a great challenge on designing long-term batteries for long-road journeys, furthermore, the charging period of the batteries are still under research. In this thesis, the design of a dynamic wireless power transfer system applied to electric vehicles is presented. It describes the analysis of the S-P compensation topology, using a resonant inductive coupling for WPT and a focus on the optimization of the coil geometry to measure the efficiency of power transfer. Therefore, a low-power dynamic power transfer system for electric vehicles operating at a frequency of 85 kHz using high efficiency SiC semiconductor components and a planar circular coil is proposed. The design is divided into two circuits; the first one consists of a transmitter circuit that includes a dc source and by means of a half-bridge inverter to convert the dc power into high frequency ac power to transmit the power that enters the Tx coil. Then, there is the second circuit, which is the receiving part where the Rx coil receives the energy that is transferred to the load resistor RL. Additionally, a PI controller is designed to maintain a constant voltage under different distance variations between the coils and guarantee the energy transfer. The experimental results acquired show that the system achieves an efficiency of 65% for 55 mm and reaches 85 mm as maximum transfer distance, which for a low power system is promising to implement DWPT for electric vehicles, where it does not require major human intervention, and without occupying much space.MaestríaMagíster en Ingeniería EléctricaTABLE OF CONTENTS CHAPTER 1...........................................................................................................................8 INTRODUCTION..................................................................................................................8 1.1. Symbols and Abbreviations .................................................................................8 1.2. Abstract ................................................................................................................9 1.3. Problem Statement ...............................................................................................9 1.4. Justification ........................................................................................................10 1.5. Objectives...........................................................................................................11 1.5.1. General objective................................................................................................11 1.5.2. Specific objectives..............................................................................................11 CHAPTER 2.........................................................................................................................13 STATE OF THE ART IN WIRELESS POWER TRANSFER............................................13 2.1. Electric Vehicles.......................................................................................................13 2.1.1. Static Charge...........................................................................................................14 2.1.2. Dynamic Charge .....................................................................................................15 2.2 Principle of WPT ........................................................................................................15 2.2.1. Basic Structure and Connections............................................................................16 2.3. Operating Frequency..................................................................................................17 2.4. Quality Factor Q ........................................................................................................18 2.5. Z-source Inverter Single Phase ..................................................................................18 CHAPTER 3.........................................................................................................................21 MATHEMATICAL MODEL...............................................................................................21 3.1 Z-Source Inverter Mathematical Model .....................................................................21 3.1.1 Single Phase Z-Source Inverter ...............................................................................21 3.2 Serie-Parallel Compensated........................................................................................23 3.3. Mutual Inductance .....................................................................................................26 3.4. Skin Effect .................................................................................................................28 3.5. Circular Geometry .....................................................................................................29 3.6. Parallel Resonance .....................................................................................................30 CHAPTER 4.........................................................................................................................34 METHODOLOGY AND DESIGN OF CONTROL VERSUS PARAMETER VARIATION ..............................................................................................................................................34 4.1 Modeling Stace-Space of DWPT and Z-Source Inverter ...........................................34 4.2 Harmonic Approximation ...........................................................................................35 4.3. Derivation of Extended Describing Functions (EDF) ...............................................36 4.4. Control Scheme by State Feedback ...........................................................................38 4.5 PID Control.................................................................................................................40 CHAPTER 5.........................................................................................................................42 SIMULATION, DESIGN AND EXPERIMENTAL VALIDATION .................................42 5.1. Coil Design Considerations .......................................................................................42 6 5.1.1. Computational Analysis Coil Design .....................................................................43 5.1.2 Coil Design ..............................................................................................................44 5.1.3. Skin Effec ...............................................................................................................45 5.1.4 Analysis and Design for Control Strategies.............................................................46 5.2. Experimental Results.................................................................................................48 CHAPTER 6.........................................................................................................................52 CONCLUSIONS AND FUTURE WORK...........................................................................52 6.1 Conclusions.................................................................................................................52 6.2 Future Work................................................................................................................5

Control method for wireless inductive energy transfer systems with relatively large air gap

Recent improvements in semiconductor technology make efficient switching possible at higher frequencies, which benefits the application of wireless inductive energy transfer. However, a higher frequency does not alter the magnetic coupling between energy transmitter and receiver. Due to the still weak magnetic coupling between transmitting and receiving sides that are separated by a substantial air gap, energy circulates in the primary transmitting side without being transferred to the secondary receiving side. This paper introduces an energy control method that reduces energy circulation in the primary to zero. Themethod makes use of the fact that energy can be stored in a magnetic field by the primary side and absorbed by the secondary side. Furthermore, the secondary side converter topology is modified in order to boost the damping as seen by the primary converter at required times. Essentially, the control method realizes an energetic coupling factor of one between the air coils of the wireless transformer. The working principle of the controlmethod has been verified with an experimental setup.Peer Reviewe

Mapa de la recerca del Campus de Vilanova i la Geltrú

Postprint (author’s final draft

Inductive contactless energy transfer systems for residential areas

In recent years, contactless energy transfer systems have been developed and investigated widely. As evident, the transfer energy is performed without physical connection. This technology is classified according to power level and place of use. However, the most commonly used one is inductive contactless energy transfer system due to its higher efficiency. The inductive contactless system is responsible to deliver the electrical energy to the loads by means of a long winding loop and sliding transformers. In this system, the output converter and load are directly connected to the secondary side of transformer. Moreover, the secondary side transformer has the capability to move along the primary winding loop. According to this capability, and also possibility to construct long contactless system, it can be used as an electrical energy delivery system for mobile receivers. Also, the ICET technologies improve the safety of the final user by means of the elimination of electrical shocks. It is resulted from using a high-frequency resonant transformer which provides electrical isolation. This feature is particularly important in wet environments such as in swimming pools, gardens and bathrooms. Therefore, it is a good alternative system for implementing in the residential area instead of conventional systems. Implementation of the inductive contactless system in residential area presents several challenges. In this dissertation, several solutions are presented and discussed. In the first chapter, the concept of the contactless energy transfer system is explained. Also, the chapter classifies the contactless system according to the technology and the output power. In chapter two, a new adaptive control algorithm for the fully-controlled contactless energy transfer system is presented. The new adaptive algorithm operates dynamically with the load changes, resulting in maximum efficiency in all the load conditions. Moreover, the mathematical framework of the contactless system with new adaptive algorithm is presented. In chapter three, a partially-controlled inductive contactless system as an alternative to the fully-controlled topology is introduced. The features of the new topology are analyzed by considering several modulation techniques, including frequency modulation, phase modulation and quantum modulation. The performance of the new topology is evaluated and the best modulation technique is identified. The chapter is finished with the design of the new topology with the best modulation technique. In chapter four, the analysis, design and implementation of a simple and cost-effective technique to supply the residential contactless energy transfer system with multiple mobile loads is presents. The topology is based on the cascaded connection of a closed-loop buck converter and a high frequency resonant inverter operating in open loop which is loaded by several output passive rectifiers. The proposed system includes a sliding transformer to supply the mobile loads, leading to a safe and flexible location of loads. The theoretical analysis and design of the proposed system is based on a mathematical model derived using the first harmonic approximation. Selected experimental results are included to verify the system features. Finally, the dissertation concludes with remarks regarding the results.En los últimos años, los sistemas de transmisión de energía sin contacto han sido ampliamente investigados y desarrollados. Como es evidente, en estos la transmisión de energía se realiza sin conexión física. Esta tecnología se suele clasificar de acuerdo al nivel de potencia y el lugar de utilización. Sin embargo, los más usados son los sistemas inductivos de trasmisión de energía sin contacto (Inductive contactless energy transfer systems, ICET) debido a su alta eficiencia. Los sistemas ICET envían la energía eléctrica a las cargas a través de grandes bobinados y transformadores sliding. En estos sistemas, la salida del convertidor y las cargas están directamente conectadas al lado secundario del transformador. Este, tiene la capacidad de moverse a través del bobinado primario. Debido a esta capacidad y a la posibilidad de construir sistemas de gran tamaño, pueden ser usados como sistemas de suministro de energía para receptores móviles. Por otro lado, las tecnologías ICET mejoran la seguridad de los usuarios finales ya que eliminan el riesgo de electrocución, como resultado del uso de transformadores resonantes de alta frecuencia que proveen un aislamiento eléctrico. Esta característica es particularmente importante en ambientes húmedos como las piscinas, jardines y baños. Además, es una buena alternativa para la implementación residencial, en lugar de los sistemas convencionales. La implementación de sistemas ICET en áreas residenciales presenta ciertos retos. En esta tesis de doctorado, se presentan diversas soluciones a estos. En el primer capítulo, el concepto de sistemas de transmisión de energía sin contacto es explicado y se presenta una clasificación de acuerdo al nivel de potencia. En el segundo capítulo, se propone un algoritmo de control adaptativo para sistemas de transmisión de energía sin contacto totalmente controlados. Este algoritmo adaptativo opera dinámicamente con los cambios de carga, alcanzando la máxima eficiencia ante diferentes condiciones de carga. En el capítulo se describe el modelado matemático del algoritmo propuesto. En el tercer capítulo, se introduce un sistema sin contacto inductivo parcialmente controlado como alternativa a la topología totalmente controlada. Se analizan las características de esta nueva topología considerando diferentes técnicas de modulación, incluyendo la modulación de frecuencia, la modulación de fase y la modulación Quantum. Luego, se evalúa el desempeño de esta nueva topología y de identifica la técnica de modulación más adecuada. Finalmente, se presenta el diseño de la nueva topología con la técnica de modulación seleccionada. En el cuarto capítulo se presenta el análisis, diseño e implementación de una técnica simple y efectiva en términos de costo para el suministro energía inalámbrica residencial con múltiples cargas móviles. La topología se basa en una conexión en cascada de un convertidor buck de lazo cerrado y de un inversor resonante de alta frecuencia operando en lazo abierto, que es cargado con varios rectificadores pasivos. El sistema propuesto incluye un transformador sliding para abastecer las cargas móviles, lo que permite una ubicación flexible y segura de las mismas. El análisis teórico y el diseño del sistema propuesto se basan en modelos matemáticos derivados del uso de la aproximación del primer armónico. Se incluyen resultados experimentales para verificar las características del sistema. Finalmente, se presentan las conclusiones más importantes de los resultados obtenido

Inductive contactless energy transfer systems for residential areas

In recent years, contactless energy transfer systems have been developed and investigated widely. As evident, the transfer energy is performed without physical connection. This technology is classified according to power level and place of use. However, the most commonly used one is inductive contactless energy transfer system due to its higher efficiency. The inductive contactless system is responsible to deliver the electrical energy to the loads by means of a long winding loop and sliding transformers. In this system, the output converter and load are directly connected to the secondary side of transformer. Moreover, the secondary side transformer has the capability to move along the primary winding loop. According to this capability, and also possibility to construct long contactless system, it can be used as an electrical energy delivery system for mobile receivers. Also, the ICET technologies improve the safety of the final user by means of the elimination of electrical shocks. It is resulted from using a high-frequency resonant transformer which provides electrical isolation. This feature is particularly important in wet environments such as in swimming pools, gardens and bathrooms. Therefore, it is a good alternative system for implementing in the residential area instead of conventional systems. Implementation of the inductive contactless system in residential area presents several challenges. In this dissertation, several solutions are presented and discussed. In the first chapter, the concept of the contactless energy transfer system is explained. Also, the chapter classifies the contactless system according to the technology and the output power. In chapter two, a new adaptive control algorithm for the fully-controlled contactless energy transfer system is presented. The new adaptive algorithm operates dynamically with the load changes, resulting in maximum efficiency in all the load conditions. Moreover, the mathematical framework of the contactless system with new adaptive algorithm is presented. In chapter three, a partially-controlled inductive contactless system as an alternative to the fully-controlled topology is introduced. The features of the new topology are analyzed by considering several modulation techniques, including frequency modulation, phase modulation and quantum modulation. The performance of the new topology is evaluated and the best modulation technique is identified. The chapter is finished with the design of the new topology with the best modulation technique. In chapter four, the analysis, design and implementation of a simple and cost-effective technique to supply the residential contactless energy transfer system with multiple mobile loads is presents. The topology is based on the cascaded connection of a closed-loop buck converter and a high frequency resonant inverter operating in open loop which is loaded by several output passive rectifiers. The proposed system includes a sliding transformer to supply the mobile loads, leading to a safe and flexible location of loads. The theoretical analysis and design of the proposed system is based on a mathematical model derived using the first harmonic approximation. Selected experimental results are included to verify the system features. Finally, the dissertation concludes with remarks regarding the results.En los últimos años, los sistemas de transmisión de energía sin contacto han sido ampliamente investigados y desarrollados. Como es evidente, en estos la transmisión de energía se realiza sin conexión física. Esta tecnología se suele clasificar de acuerdo al nivel de potencia y el lugar de utilización. Sin embargo, los más usados son los sistemas inductivos de trasmisión de energía sin contacto (Inductive contactless energy transfer systems, ICET) debido a su alta eficiencia. Los sistemas ICET envían la energía eléctrica a las cargas a través de grandes bobinados y transformadores sliding. En estos sistemas, la salida del convertidor y las cargas están directamente conectadas al lado secundario del transformador. Este, tiene la capacidad de moverse a través del bobinado primario. Debido a esta capacidad y a la posibilidad de construir sistemas de gran tamaño, pueden ser usados como sistemas de suministro de energía para receptores móviles. Por otro lado, las tecnologías ICET mejoran la seguridad de los usuarios finales ya que eliminan el riesgo de electrocución, como resultado del uso de transformadores resonantes de alta frecuencia que proveen un aislamiento eléctrico. Esta característica es particularmente importante en ambientes húmedos como las piscinas, jardines y baños. Además, es una buena alternativa para la implementación residencial, en lugar de los sistemas convencionales. La implementación de sistemas ICET en áreas residenciales presenta ciertos retos. En esta tesis de doctorado, se presentan diversas soluciones a estos. En el primer capítulo, el concepto de sistemas de transmisión de energía sin contacto es explicado y se presenta una clasificación de acuerdo al nivel de potencia. En el segundo capítulo, se propone un algoritmo de control adaptativo para sistemas de transmisión de energía sin contacto totalmente controlados. Este algoritmo adaptativo opera dinámicamente con los cambios de carga, alcanzando la máxima eficiencia ante diferentes condiciones de carga. En el capítulo se describe el modelado matemático del algoritmo propuesto. En el tercer capítulo, se introduce un sistema sin contacto inductivo parcialmente controlado como alternativa a la topología totalmente controlada. Se analizan las características de esta nueva topología considerando diferentes técnicas de modulación, incluyendo la modulación de frecuencia, la modulación de fase y la modulación Quantum. Luego, se evalúa el desempeño de esta nueva topología y de identifica la técnica de modulación más adecuada. Finalmente, se presenta el diseño de la nueva topología con la técnica de modulación seleccionada. En el cuarto capítulo se presenta el análisis, diseño e implementación de una técnica simple y efectiva en términos de costo para el suministro energía inalámbrica residencial con múltiples cargas móviles. La topología se basa en una conexión en cascada de un convertidor buck de lazo cerrado y de un inversor resonante de alta frecuencia operando en lazo abierto, que es cargado con varios rectificadores pasivos. El sistema propuesto incluye un transformador sliding para abastecer las cargas móviles, lo que permite una ubicación flexible y segura de las mismas. El análisis teórico y el diseño del sistema propuesto se basan en modelos matemáticos derivados del uso de la aproximación del primer armónico. Se incluyen resultados experimentales para verificar las características del sistema. Finalmente, se presentan las conclusiones más importantes de los resultados obtenido

Multi-Frequency Modulation and Control for DC/AC and AC/DC Resonant Converters

Harmonic content is inherent in switched-mode power supplies. Since the undesired harmonics interfere with the operation of other sensitive electronics, the reduction of harmonic content is essential for power electronics design. Conventional approaches to attenuate the harmonic content include passive/active filter and wave-shaping in modulation. However, those approaches are not suitable for resonant converters due to bulky passive volumes and excessive switching losses. This dissertation focuses on eliminating the undesired harmonics from generation by intelligently manipulating the spectrum of switching waveforms, considering practical needs for functionality.To generate multiple ac outputs while eliminating the low-order harmonics from a single inverter, a multi-frequency programmed pulse width modulation is investigated. The proposed modulation schemes enable multi-frequency generation and independent output regulation. In this method, the fundamental and certain harmonics are independently controlled for each of the outputs, allowing individual power regulations. Also, undesired harmonics in between output frequencies are easily eliminated from generation, which prevents potential hazards caused by the harmonic content and bulky filters. Finally, the proposed modulation schemes are applicable to a variety of DC/AC topologies.Two applications of dc/ac resonant inverters, i.e. an electrosurgical generator and a dual-mode WPT transmitter, are demonstrated using the proposed MFPWM schemes. From the experimental results of two hardware prototypes, the MFPWM alleviates the challenges of designing a complicated passive filter for the low-order harmonics. In addition, the MFPWM facilitates combines functionalities using less hardware compared to the state-of-the-art. The prototypes demonstrate a comparable efficiency while achieving multiple ac outputs using a single inverter.To overcome the low-efficiency, low power-density problems in conventional wireless fast charging, a multi-level switched-capacitor ac/dc rectifier is investigated. This new WPT receiver takes advantage of a high power-density switched-capacitor circuit, the low harmonic content of the multilevel MFPWMs, and output regulation ability to improve the system efficiency. A detailed topology evaluation regarding the regulation scheme, system efficiency, current THD and volume estimation is demonstrated, and experimental results from a 20 W prototype prove that the multi-level switched-capacitor rectifier is an excellent candidate for high-efficiency, high power density design of wireless fast charging receiver