Fabio Corti

Design of class-E ZVS inverter with loosely-coupled transformer at fixed coupling coefficient

The design of Class-E zero-voltage switching (ZVS) inverter with a loosely-coupled transformer is introduced in this paper. In the presented approach, the magnetizing and leakage inductances of the transformer are absorbed into the main circuit. The synthesis of the transformer-version of Class-E ZVS inverter into its equivalent π2a topology is presented. The π2a topology improves the range of the optimum load resistance required to achieve ZVS. An example of the Class-E inverter with dc supply voltage 10 V, output power 10 W, switching frequency 100 kHz and at a coupling coefficient of 0.77 is considered. The inverter is designed to achieve both zero-voltage switching (ZVS) and zero derivative switching (ZDS) conditions. The analytical expressions are validated through simulation results for an optimum coupling coefficient of 0.77. In view of potential misalignment between the primary and secondary coils, simulation results are provided for coupling coefficients, which are lower and higher than the optimum value. It is shown that both ZVS and ZDS can be achieved at a coupling coefficient lower than the optimum value and is not possible to achieve ZVS at a coupling coefficient higher than the optimum value. Overall efficiency of 94.3% is achieved at a coupling coefficient of 0.77, 93.4% at 0.85, and 92.12% at 0.7. The presented approach can be used for transformers with reactive load impedances also.

Inductive power transfer: Through a bondgraph analogy, an innovative modal approach

There is a wide research interest in the field of design and optimization of inductive power transfer systems due to increasing diffusion of sustainable electric powered transportation systems involving the development of both conventional and autonomous ground, air and marine vehicles. In this work authors, focused their attention on a consolidated toy benchmark (a cylindrical inductive pattern fed by a resonant converter), to introduce, test and validate an innovative approach based on the analogy between electromagnetic systems and mechanical ones. In this way, many key features of resonant inductive power transfer systems should be modelled and understood using methodologies previously developed for the study of mechanical vibrating systems and widely adopted for the optimization and control of suspension systems. In this work an example is validated both on a simplified experimental setup and on the corresponding Finite Element model, showing feasibility and advantages deriving from the proposed approach.

Fault detection in Class-E 2 resonant converters

DC-DC converter reliability is of primary interest due to their key role in electronic systems. This paper proposes a diagnostic algorithm, which can be easily implemented in digital programmable device for MOSFET fault detection and identification. An improvement over the existing technique is presented, and its rapid fault detection capability is demonstrated. The two basic faults, namely the short circuit (SCF) and the open circuit fault (OCF) are identified by analyzing the current through the choke inductance. Upon identification of the fault signature, techniques to mitigate the after-effects are discussed. To validate the algorithm, a simulation on a Class-E2 resonant converter is presented.

Class-E DC-AC resonant inverter design centering

Tolerance analysis is crucial in industrial production of power electronics converters. This paper presents an application of the design centering for resonant converters. Actually, this technique has been successfully utilized to increase the quality of analog and integrated circuits built on a large scale, but it has never been utilized for resonant converter circuits. The effect on the power mosfet switching of passive components constituting the resonant tank of a class-E DC-AC is considered. The paper also provides actions to increase the converter circuit reliability.

Distortion analysis and equivalent impedance estimation of a class-D full-wave rectifier

The substantial increasing of switching devices utilization such as switching power converters, inverters, electronic ballast, UPS, and computer equipment, introduce harmonic distortion in supply systems because of their non-linear characteristics. The waveform distortion produces harmonics that not only increases power losses but also introduces a distortion power, which sums to time-average real and reactive power usually considered in linear circuits. Therefore, effects on harmonics must be considered in the circuit design. In this paper, the current distortion introduced by a Class-D full wave resonant rectifier used in a series-series compensation circuit for wireless power transfer is considered and a general approach to derive a rectifier equivalent impedance that consider the effect of distortion on the output power is presented.

Wireless power recharge for underwater robotics

Development of Underwater Robotics is an important field of research and a promising industrial application since it represents a sustainable solution to exploit ocean resources with a reasonable environmental impact. To perform prolonged manipulation task, autonomous vehicles often suffer of insufficient autonomy while remotely operated vehicles despite to their performances are often limited by the complex management of umbilical link. For this reason, a new generation of hybrid underwater vehicles able to perform autonomously some tasks returning periodically to a docking station for recharge, vehicle and tooling reconfiguration is needed. In this work, a possible solution for a wireless recharging connection, able to drastically simplify recharge operations in underwater environment at abyssal depth (thousands of meter depth) is investigated. The paper presents some preliminary design and simulation proposal, along with a preliminary experimental validation of the adopted simulation tool on a toy test case.

Application of induction power recharge to garbage collection service

There is a wide variety of industrial vehicles that are customized to perform different public services in urban environments. Typical mission profiles, associated to these urban services are often ideal to the application of electric vehicles since low speed and frequent accelerations and decelerations are required. The cost of accumulators which are required to assure prescribed vehicle autonomy represents a serious issue for a fast diffusion of this technologies. However, some of the most commonly diffused public services such as collection of garbage involve the execution of fixed route with frequent and prolonged stoppages, a profile mission that suggests the possibility to adopt charging solutions to supply additional energy to the vehicle. In this work, the potential of an inductive recharge network is investigated as a mean to improve vehicle range or — from another point of view — to reduce the size of on board accumulators, making electric vehicles available to perform a prescribed mission profile without any limitation in comparison with conventional ones.