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This paper introduces a distributed energy management for islanded DC microgrids with electric vehicles (EVs) penetration. The energy management problem is divided into two stages. The first, named as filtering stage, is controlled through wavelet filter using the ultracapacitor. The second one is modeled as a noncooperative stackelberg game, where the battery energy storage system is designed as...
This paper studies an energy management problem for an isolated microgrid including photovoltaic panels, wind turbines, batteries and ultracapacitors. A normal form game is proposed for the energy management to maximize the energy utilization ratio of renewable energy sources, extend the battery life and keep the ultracapacitors able to compensate the dynamic variations. The solution of this game...
Wireless power transfer (WPT) working at megahertz (MHz) is widely considered a promising technology for the mid-range transfer of low power. In the biomedical implantable WPT systems, the receiving coil is small. Meanwhile, in real applications, the required transfer distance is large. Thus, the coupling coefficient k is low. For the applications of large load, the low coupling coefficient k and...
This paper presents a design procedure of a Class E2 DC-DC converter for megahertz wireless power transfer. The design formulas are analytically derived based on the input impedance of the Class E rectifier. A 6.78 MHz Class E2 DC-DC converter is designed and implemented by means of those formulas. The power-level of the converter is 15W. The experiments are provided to verify the proposed design...
To improve battery cell balancing speed, a novel switched capacitor (SC) circuit combining the conventional SC circuit and the optimized SC circuit is proposed in this paper. It has the advantage that the balancing speed is independent of number increase as well as initial voltage variation of battery cells. The equivalent model of the proposed circuit is developed and analyzed in this paper. Compared...
It is attractive to achieve multi-receiver wireless power transfer (WPT) through a megahertz operating frequency. However, the power distribution among receivers can be a difficult task due to the different load characteristics, i.e., power requirement, receiver size, and coupling coefficient. This paper proposes a general design methodology of efficiency optimization and power distribution of a MHz...
Class E rectifier is suitable for high-frequency rectification due to its soft-switching operation, which potentially improves the efficiency of wireless power transfer (WPT) systems working at MHz. In this paper, a robust optimization design is discussed for a 6.78-MHz WPT system using the Class E rectifier. In real WPT applications, the parameter variations are possible to be originated from the...
This paper discusses a decentralized energy management for an engine-generator/battery/ultracapacitor (UC) hybrid energy system with fault tolerance analysis. The energy management problem among the energy suppliers and the load is formed into a non-cooperative power distribution game where the engine-generator, the battery pack, the UC pack, and the load are modeled as independent and related players...
This paper provides a two-level energy management strategy for a fuel cell-battery-ultracapacitor (UC) hybrid system. In the proposed strategy, the battery and UC packs are seen as an energy storage system (ESS) at the first level and the equivalent consumption minimization strategy is used to distribute load power between this ESS and the fuel cell system. The penalty factor is tuned based on estimated...
High frequency wireless power transfer (WPT) such as working at megahertz (MHz) is widely considered to be a promising candidate for charging the lithium-ion batteries of mobile electronic devices. However, in a real battery charging application, the varying battery voltage and charging current will significantly affect the system efficiency and lead to the high power loss in the whole charging process,...
A decentralized charging control of a multiple-receiver wireless power transfer (WPT) system is proposed and discusses in this paper. Different from charging battery alone systems through WPT technology, using an additional ultracapacitor (UC) combined with the battery alone system could both achieve the power requirement and a high efficiency. Then the charging control problem is converted into a...
Wireless power transfer (WPT) has shown its potential over conventional charging systems in recent years. However, it is still challenging to determine the power distribution of a multiple-receiver WPT system for its high sensitivity, complex coupling and load relationships. This paper discusses a game theory based control approach for the power distribution of a multiple-receiver WPT system. The...
A wireless power transfer system can increase its system frequency to several Megahertz for large spatial freedom. A MHz system usually uses the same compensation as those kHz systems. Traditionally, the rectifier is modeled as a pure resistive load for the coupling coils when designing the compensation capacitors. However, the rectifier input reactance cannot be ignored for MHz systems. This reactance...
This paper provides an equivalent series resistance-based real-time control method for the battery-ultracapacitor hybrid system. The idea of this control method is that the dynamic load demand is distributed based on the equivalent series resistance ratio of batteries to ultracapacitors, whilst the estimated average load demand based on the past N seconds is supplied by the batteries. In addition,...
This report discusses using the new SiC-MOSFETs in a front-end DC-DC converter for distributed power systems. In such an application, high efficiency and high power density are the major driving factors that naturally require a high switching frequency. The SiC-MOSFET is widely considered a desirable switching device for the high-frequency power conversion/inversion circuits due to its high voltage,...
It is promising for consumer electronics to achieve the long wireless charging distance by increasing the system frequency to megahertz. For MHz systems, hard-switching-based rectifiers(e.g., the full-bridge rectifier) will have significant switching loss. Therefore, it is attractive to apply the soft-switching techniques for MHz rectifiers. The Class E rectifier is a proper candidate for MHz system...
It is attractive to achieve wireless power transfer with large spatial freedom by using a Megahertz system. For most systems, especially those working at kHz, the rectifiers are equivalently modelled as pure resistive loads when designing the compensated capacitors for coupling coils. However, the input reactance occurs when a rectifier works at high frequency, such as Megahertz. It can disturb the...
A high-efficiency power amplifier (PA) is important in a Megahertz wireless power transfer (WPT) system. It is attractive to apply the Class-E PA for its simple structure and high efficiency. However, the conventional design for Class-E PA can only ensure a high efficiency for a fixed load. It is necessary to develop a high-efficiency Class-E PA for a wide-range load in WPT systems. A novel design...
Dead-time produces distorted voltage and current, which degrades the performance of inverters. To compensate for the dead-time effect, its influence on converter voltage should be modeled precisely first. However, the state-of-the-art models of dead-time effect do not consider either the parasitic capacitance of power devices or the ripple current of inductors. These non-ideal factors prove to be...
The battery-ultracapacitor hybrid energy storage system (HESS) and its management have been widely investigated in recent years. Meanwhile, there is a lack of general and quantitative analysis on the energy loss of the battery-ultracapacitor HESS that does not depend on any specific control algorithm or physical limitations. In addition, the battery-ultracapacitor HESS is actually a simple example...
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