Improving the efficiency of a standard compliant wireless battery charger

In this paper, a wireless charger for portable electronics devices is presented. A power transmitter, also known as the magnetic pad, and a power receiver are magnetically coupled. A receiver architecture which improves the power conversion efficiency is proposed. All advantages brought by the proposed architecture are discussed and standard constraints are presented as well. The receiver is fully standard-compliant. A wireless station for mobile application is designed and tested. Simulation and experimental results are compared. As shown by experimental results, thanks to the proposed architecture the power conversion efficiency of the receiver section is really close to a unit value. Pow…

An innovative PWM loop control for VRMs

Architecture of a digital PFM controller for IC implementation

This paper presents a digital controller architecture oriented to IC implementation. The classical digital pulse width modulator (D-PWM), using digital analog converter (DAC), is replaced with a Sigma-Delta (/spl Sigma//spl Delta/) modulator based on pulse frequency modulator (PFM) technique. Results of an investigation from a prototype for DC-DC converter, in terms of simulated and experimental performances, are reported, together with harmonic frequency investigation. The control function design is implemented on a field programmable gate array (FPGA). As a consequence of good agreement between simulated and experimental results, the proposed architecture realizes a digital control loop w…

MATLAB-based simulator of a 5 kW fuel cell for power electronics design

Abstract In the last few years, renewable energies have been encouraged by worldwide governments to meet energy saving policies. Among renewable energy sources, fuel cells have attracted much interest for a wide variety of research areas. Since combined heat-power generation is allowed, household appliances are still the most promising applications. Fuel cell-based residential-scaled power supply systems take advantage by simultaneous generation of power and heat, reducing the overall fossil fuel consumption and utilities cost. Modelling is one of the most important topic concerning fuel cell use. In this paper, a measurement-based steady-state and dynamic fuel cell model is presented. The …

HEMT for low-noise microwaves: CAD-oriented performance evaluation

This paper shows how a graphic processing of low-noise HEMT's small signal parameters, allows evaluating and comparing the actual performance obtainable in front-end applications. HEMT's tradeoff charts which solve tradeoffs among the basic low-noise amplifier performance are reported. Figures of merit for microwave low-noise HEMT which represent a fast way of evaluating HEMT in actual working conditions and of selecting the proper transistor, are defined. As an example, the tradeoff charts and the figures of merit of two HEMT's (Fujitsu FHR02FH, Sony 2SK677) and a pseudomorphic-HEMT (Celeritek CFB001-03) are reported and compared with the data sheets. © 1995, IEEE. All rights reserved.

Fuel cells for household appliances: Experimental test of power management algorithms

In this paper, fuel cell - based hybrid power supplies for household appliances are addressed. The profile of residential power consumption is evaluated during working, non-working days in both summer and winter periods. The worst-case load power demand is therefore highlighted. A 5kW Nuvera PowerFlow proton exchange membrane fuel cell for household appliances is tested. On the basis of the characterization of the fuel cell stack under test, stand-alone and fuel cell - battery active hybrid power supply architectures are both considered. Experimental validation of three power management algorithms is proposed in terms of hydrogen consumption, cost and energy saving. Power management algorit…

A simple and accurate model of photovoltaic modules for power system design

A semi-empirical multipurpose steady-state model of a fuel cell for household appliances

In this paper, a multipurpose model of a proton exchange membrane fuel cell for household appliances is proposed. According to a conventional mathematical approach, the proposed model is derived from the physical and electro-chemical equations that rule the fuel cell behaviour. Differently from existing models, a parametric analysis is carried out and a few tunable parameters are accurately selected and identified. Furthermore, this paper proposes an innovative technique of unique model architecture which enables the designer to solve by himself the trade-off between complexity and accuracy on the basis of the specific applications. Three different choices could be performed by the designer…

A novel linear-non-linear digital control for DC/DC converters

In this paper, a digitally controlled multi-module DC-DC converter with fast transient response, based on a linear-non-linear control is presented. The proposed digital control improves the stability of the system, cuts off the effects of limit-cycle and reduces the recovery time, by making the "effective" bandwidth of the system independent of the bandwidth of the linear control loop and limits, at the same time, output voltage variations. The novel digital control is AVP-compatible and halves the recovery time. Preliminary hardware tests on a single phase step-down converter are reported. The experimental results match simulation ones, obtained by modelling system with Matlab/Aldec mixed …

Non-linear digital control improving transient response: Design and test on a multiphase VRM

Multiphase interleaved buck converters are widely used for point of load applications, especially for VRMs. Performance optimization issue often clashes with size and cost requirements thus leading the industrial and academic research to focus on advanced solutions. This paper presents a control technique for multiphase VRMs including two interacting sections: the linear loop implements a PWM peak current mode control and the nonlinear subsystem modifies few linear loop parameters under load transients only. Steady-state performances are affected by the linear control only while dynamic performance optimization is a non-linear algorithm issue. The proposed control system improves the dynami…

Dynamic performance evaluation of a non linear digital control technique for multiphase VRMs

Digital power conversion system based on a sigma-delta modulator linear model

This paper presents a new linear model for the sigma-delta (/spl Sigma//spl Delta/) modulator, based on modeling the nonlinear quantizer with a linear factor, and its input-to-output transfer function is given. The use of a 1-bit sigma-delta modulator in DC/DC power converter systems permits to implement a complete digital control. Results of an investigation from a prototype for a DC-DC converter are here reported. Using of a field programmable gate array allows implementing a simple variable control function. The modulator output produces a variable-frequency variable duty-ratio signal to control the switching power transistors.

A fuel cell-based hybrid power supply for portable electronics devices

A fuel cell - supercapacitor hybrid power supply for portable applications is designed. To ensure system level simulation, each component is accurately modeled and simulation results are reported. A Digital Still Camera is selected as specific load device, although the choice of a specific application does not influence the proposed control technique performances but only dictates the power supply specifications. The fuel cell and the power management system are modeled in PSIM. © 2008 IEEE.

Modeling and simulation of a digital control design approach for power supply systems

Electronic designers need to model and simulate system features as close as possible to its effective behaviour. Moreover, today, electronics systems are often composed of mixed analog and digital components. The increasing complexity has led to the use of different simulation softwares, each one specific for a particular level of abstraction: mathematical, circuital, behavioural, etc. In order to simulate the entire system these softwares should work together: co-simulation is necessary for digitally controlled power electronics systems. In this paper, the modeling of a digitally controlled switching power supply system using MATLAB/Simulink, ALDEC Active-HDL and Powersys PSIM is presented…

A demagnetization circuit for forward converters

This paper presents a demagnetization circuit able to operate the forward converter with an higher efficiency and with a wider input range. In particular, by the means of few added components, the magnetizing energy and the leakage one are continuously recovered, and the transformer reset and the primary mosfet OFF voltage clamp to the input, both under steady state and transient operations, are provided. The reduced voltage stress allows the converter to operate with a duty extended to unity over the typical 70% limit of the Active Clamp topology, with smaller output inductance, better converter dynamics and wider input range. Furthermore, thanks to this technique, by employing a duty appr…

Measurement-based load modelling for power supply system design

Load modelling is essential to simulate system features as closely as possible to the effective behaviour. In spite of model complexity, the need for accuracy often leads to a component-based approach, i.e. the analysis of load internal subsystems. It is a common belief that measurement-based load models lead to low accuracy. This paper presents a new, high-accuracy measurement-based load modelling approach to define a power consumption profile load model for power systems design. The load modeling technique is described by an application. Simulation and experimental results are compared. The efficiency and portability of the proposed modelling approach is discussed. ©2008 IEEE.

A New Model for Sigma-Delta Modulator Oriented to Digitally Controlled DC/DC Converter

Recent research activities have shown the feasibility and advantages of using digital controller ICs specifically developed for high-frequency switching converters, highlighting a challenging future trend in Switched-mode power supplies (SMPS) applications. Up to a few years ago, the application of digital control for SMPS was impractical due to the high cost and low performance of DSP and microcontroller systems, even if the advantages that digital controllers offer were well known, such as immunity to analog component variations and ability to implement sophisticated control schemes and system diagnostics. Digital controller ICs potentially offer other advantages from the integrated desig…

A digital control technique for high-performances DC-DC converters

An improved Flyback converter

This paper presents a modified Flyback converter able to operate with higher efficiency and smaller size, overcoming most of the conventional flyback converter drawbacks, and also keeping its low cost and simplicity. In particular, the proposed converter allows the mosfet off voltage to be reduced and clamped to the input, thus recovering the transformer leakage energy. As a consequence, the duty cycle can be extended to unity, thus reducing the voltage stress across the output rectifier, and lowering both the magnetizing inductance and the transformer bias current values. In addition, due to the auxiliary mosfet, the magnetizing current can become negative, eliminating the discontinuous co…

A lossless current sensing technique for flyback converters

Regardless of the feedback control, almost all converters require input or output current sense for overcurrent protection. If a current mode control is implemented, high accuracy is also required. The optimal current sensing method shows the highest accuracy and the lowest power dissipation. In this paper, a lossless and accurate current sensing technique for Flyback converters is proposed. An RC network is parallel connected with the primary MOSFET and the voltage signal across the sense capacitor accurately reproduces the magnetizing current waveform. The RC technique benefits from all the advantages of the most common current sensing techniques currently applied to Flyback converters, a…

FPGA implementation of a fuel cell emulator

Fuel cell based systems are usually tested with the aid of high-cost and complex auxiliary devices. A fuel cell emulator is an attractive solution for preliminary downward system test. The emulator replaces the effective power source saving cost, volume and hydrogen reserve still ensuring high-accuracy of test results. The use of a highperformance fuel cell model is essential for a successful conclusion of the overall design process. Although the proposed emulator is suitable for each fuel cell type and power level, a 10W Proton Exchange Membrane Fuel Cell emulator is designed and tested. An FPGA based controller models the fuel cell steady-state and dynamic behaviour, including temperature…

Dedicated anlog-to-digital converter for digital VRM

Non linear digital control improving transient response:design and test on a multiphase VRM

A steady-state and dynamic fuel cell model for power electronics design

A fuel cell model emulator, including temperature effects

Research on the model emulator and experiment checkout of the fuel cell

A review of fuel cell based hybrid power supply architectures and algorithms for household appliances

Abstract Nowadays, renewable power system solutions are widely investigated for residential applications. Grid-connected systems including energy storage elements are designed. Advanced research is actually focused on improving the reliability and energy density of renewable systems reducing the whole utility cost. Source and load modeling, power architectures and algorithms are only a few topics to be addressed. Designers have to carefully deal with each subtopic prior to design efficient renewable energy systems. In the literature, each topic is separately discussed and the lack of a unique reference guide is clear to power electronics designers. In this paper, each design step including …

Fuel cell analytical modeling: Solving the trade-off between accuracy and complexity

In this paper, a 5.5 kW Proton Exchange Membrane fuel cell is modeled. The proposed analytical model is described and the parameters identification procedure is further discussed. Simulation results of all three sub-models are compared to test the accuracy of each one. A comparison between simulation and experimental results is provided as well validating the modeling approach.

Experimental test on a Contactless Power Transfer system

Contactless Power Transfer (CPT) is an ever-growing technology in automotive market, due to the significant improvement brought by it to battery charging operation in terms of safety and comfort. CPT is based on inductive coupling between two coils, so that power cords can be avoided for vehicles battery charging and an important contribution towards a smarter mobility can arise. In this paper, a CPT prototype for E-bike is proposed. Magnetic design and power electronics system are described. Experimental results deriving from laboratory tests are presented and power efficiency of the system is addressed.

DESIGN METHODOLOGY AND SETUP TOOLS FOR INTEGRATED MAGNETICS IN A SEPIC TOPOLOGY

A wireless battery charger architecture for consumer electronics

In this paper, an innovative design of a wireless battery charger for portable electronic devices is proposed. The wireless power transfer is implemented through the magnetic coupling between a power transmitter, which is connected to the grid, and a power receiver, which is integrated inside the load device. An innovative receiver architecture which heavily improves the power conversion efficiency is presented. The proposed solution is standard compliant and suitable for IC implementation. A comparison between a conventional and the proposed receiver architectures is carried out by SPICE simulations. As shown by simulation results, a power efficiency increase by 40% is provided by the prop…

Measurement-based load modelling for power supply systems design

Wireless battery charging: E-bike application

Nowadays, Inductive Power Transfer (IPT) represents a widely investigated issue with respect to modern battery charging methods, by providing a wireless solution. IPT is applied across a large variety of applications, from Watt to kWatt power levels. Although IPT features great benefits in terms of safety and comfort, the most significant drawback consists of a relatively poor power conversion efficiency. In this paper, a 100W wireless charging equipment for E-bikes which improves efficiency is proposed. Complete magnetic structure design, as well as transmitter and receiver efficient architectures, are deeply exposed. The efficiency of the designed solution is shown by simulation results.

Inductive Power Transfer for 100W battery charging

Today, Inductive Power Transfer (IPT) is widely investigated to provide wireless battery charge. Potential applications range from a few Watts of handheld devices to kWatts of automotive applications. Despite of comfort and safety options, wireless charging features relatively poor power conversion efficiency. In the literature, several solutions are proposed addressing efficiency related issues. In this paper, a 100W wireless charging station for electric bikes which improves the power conversion efficiency is proposed. The magnetic structure design is analyzed thoroughly as well as the proposed power electronics system architectures of both the power transmitter and power receiver. The ef…

A steady state and dynamic fuel cell model including temperature effects

In the last few years fuel cells have attracted much interest from both academic and industrial researchers to replace current lithium-ion and similar rechargeable battery systems. A wide variety of research areas benefit from fuel cell use: electro-chemical, stationary, transportation and portable electronics can be cited as an example. Potential applications range from few watts to megawatts systems. Even concerning quite different scientific areas, fuel cell modelling is a common requirement. The complexity of such a topic relies not only on the modelling approach but also in the model structure and implementation. In this paper a steady state and dynamic fuel cell circuital model includ…

Fuel cell modelling for power supply systems design

Today academic and industrial research is addressed on fuel cell based power supply to replace current lithium-ion and similar rechargeable battery systems. For system simulation, fuel cell models are developed. Even if power electronics designers demand for a blackbox model to limit the knowledge of physical and chemical parameters, high performance in terms of model accuracy and portability is absolutely necessary. A steady state and dynamic fuel cell model oriented to power supply systems design is proposed and, as an example, the implementation on PSIM software is presented. Simulation and experimental results are compared and the model portability is discussed. ©2008 IEEE.

Gruppo ESDP PAlermo: Attività di Ricerca

Active Snubber Network Design and Implementationon on the Primary Side of an Isolated Cuk Converter Realizing Soft-switching for Efficiency Improvement

PWM DC/DC converter based on an innovative current sensing technique

A fuel cell-battery hybrid power supply for portable applications

Today, academic and industrial research is addressed to fuel cell based hybrid power supply in many fields of applications including stationary, automotive and portable electronics. Increasing source runtime, speeding up the transient response while minimizing weight, volume and cost of the power supply system are key requirements of all applications. According to the particular application, the power management system is optimized for a specific feature. In this paper, a fuel cell–battery hybrid power supply for a Digital Camera is proposed, although the control algorithm can be efficiently applied to any portable device. Thanks to an innovative control on the input power, any fuel cell pr…

High Accuracy Modelling of Hybrid Power Supplies

This chapter proposes a modelling approach based on the PSIM/Simulink co-simulation toolbox for hybrid power supplies, featuring high accuracy. Hybrid source performances are fully tested during behavioural simulations. The importance of high-accuracy modelling is investigated and modelling guidelines for both power sources and load are given for further applications. The Simulink model is analyzed and the efficiency of the proposed approach is verified by the comparison between simulation and experimental results. In the last few years, hybrid power supplies are investigated for a wide variety of application areas: two primary sources are coupled to take advantages of both, overcoming thei…

A circuit model of a 5kW fuel cell

In the last few years, industrial research has been focused on renewable energy sources. Owing to combined heat-power generation option, fuel cells have attracted much interest for a wide variety of research areas. Household appliances are still the most promising applications. Fuel cell modeling is still a critical topic to focus on, affecting each stage of power system design. This paper describes an empirical method to model a proton exchange membrane fuel cell. The modeling approach is applied to a 5kW Nuvera PowerFlow fuel cell. A circuit model is proposed for further applications. PSPICE implementation is described and the parameters tuning procedure is discussed. Simulation and exper…

A lossles current sensing technique for flyback converters

Experimental test on a fuel cell powered brushless synchronous motor for automotive applications

In this paper, a fuel cell powered motor emulator is proposed. The MATLAB/Simulink model including the fuel cell stack, the motor and drive models is described. The Urban Driving Cycle test is performed in MATLAB environment. Effective operating conditions of the whole fuel cell powered motor are accurately emulated according to actual regulations in force. The emulated current profile is used for experimental tests on a 5kW Nuvera PowerFlow stack. Thanks to the proposed approach, the motor and inverter drives are accurately emulated and the provided test-bench is used to evaluate performances of the stack under test for automotive applications. Simulation and experimental results are compa…

Control subsystem design for wireless power transfer

Recently, the wireless power transfer has been increasingly employed. Particularly for the electric vehicles, the wireless solution is attractive for contactless battery charging, based on the Inductive Power Transfer (IPT). In this paper, a 150W prototype for IPT-based battery charging is presented and design criteria are reported. In addition to the power stage analysis, a proper control strategy is proposed. Simulation and experimental results are shown. The proposed control method aims at regulating the load current against variations in the magnetic coupling, so that the required amount of power can be supplied despite of unexpected decreases in the coupling efficiency.

A novel fuel cell-based power system modeling approach

Nowadays, fuel cells are the most promising source of energy for stationary applications. Unfortunately, the power density of fuel cells is not adequate for modern applications. A fuel cell - based hybrid power supply is required. The fuel cell is coupled with a high-energy density power source to improve performances of the composite power source. A power management stage is introduced between the two basic sources to control the power flow path from the fuel cell to the auxiliary source and the load. In order to avoid effects of a limited power density of the fuel cell on the whole power supply, sophisticated power management algorithms are implemented. Accurate modeling is required to te…

Active snubber network design and implementation on the primary side of an isolated Ćuk converter realizing soft-switching for efficiency improvement

This paper describes the process of improving the efficiency of an existing isolated DC/DC converter based on CUK topology with secondary side synchronous rectification, by means of the introduction of an active snubber network on the primary side. The snubber circuit reduces to zero the switching losses during the off-time interval of secondary SR. In particular, the efficiency improvement is due to the elimination of the primary MOSFET Coss output capacitance losses, and mainly of the reverse recovery losses on the secondary SR MOSFET. However, the insertion of the active snubber creates itself additional losses in the circuit, and therefore to measure the really introduced benefit it is …

Design and control of a novel multi-source renewable energy system

In this paper, a novel multi-input, single-inductor architecture is proposed. An innovative hysteretic control strategy of both the output voltage and the sources operating point control is designed and tested. Benefits brought by the proposed architecture over existing solutions are widely investigated. As an example, the design of a 48 V dual input system which is fed by photovoltaic and thermo-electric generators is proposed. Design guidelines are given and simulation results are presented to test the efficiency of the proposed architecture.

A multi-input, single-inductor power system for multisource energy harvesting

Today, energy harvesting is drawing a great deal of attention due to modern trends in energy saving and sustainable development purposes. Among renewable energy sources fuel cells and photovoltaic arrays are the most promising for a wide variety of applications, ranging from few mWatts of wireless sensor networks to kWatts for household appliances. Coupling several harvesters and renewable sources is the winning strategy to ensure a proper supply overcoming the uncertainty and limited availability of common harvesters and renewable sources. Multisource energy harvesting is actually an open research topic involving several pressing and often conflicting requirements. System cost, complexity,…

A FUELL CELL-BASED HYBRID POWER SUPPLY FOR PORTABLE ELECTRONICS DEVICES

A fuel cell-supercapacitor power supply for portable applications

Due to the increasing number and complexity of the available functions, modern handheld devices require higher and higher current slew rates. Customers' requirements lead to a growing interest in longer-lasting power, fast transient response power supply systems and minimization of system weight, volume and cost. Fuel cell based hybrid systems are designed to meet all requirements. In this paper, a fuel cell-supercapacitor hybrid power supply for portable applications is proposed. The power management subsystem is designed and simulation results are shown to test the efficiency of the control algorithm. ©2008 IEEE.

SISTEMA E METODO PER LA GESTIONE DI SORGENTI DI ENERGIA RINNOVABILE

A new current-mode control for DC/DC converter

Current-sensing is used widely in smart power chips, especially in DC/DC converter for voltage regulator modules (VRM), implemented with interleaved synchronous rectifier buck converters. The interleaved technique main difficulty is due to its current-sharing control between the several modules. Besides, if the used control technique is current-mode type, it is necessary create a ramp signal proportional to current on the inductor. In this paper, a lossless current-sensing method, solving the major disadvantages of the current-mode control and implementing a current-sharing technique, is proposed. This innovative technique is tested in a two-module interleaved buck converter.

Implementazione di un MAC 802.11 su FPGA

Fuel cell modelling and test: Experimental validation of model accuracy

In the last few years, renewable energies have been encouraged by worldwide governments to meet energy saving policies. Among renewable energy sources, fuel cells have attracted much interest for a wide variety of research areas. Fuel cell-based residential-scaled power supply systems take advantage of simultaneous generation of power and heat, reducing the overall fossil fuel consumption and utilities cost. Modeling is one of the most important topics concerning fuel cell use. In this paper, a measurement-based steady-state and dynamic fuel cell model is presented. The proposed modelling approach is implemented on a 5kW Proton Exchange Membrane Fuel Cell. The parameters identification proc…

Experimental test of the performances of a photovoltaic modules model

In this paper, a measurement-based modeling technique for PV panels oriented to power electronics design is proposed. The proposed modelling approach aims at an accurate modeling of the whole PV curve and not only around a few remarkable points. The proposed approach is based on an experimental characterization of the module under test. In fact, the incompleteness of manufacturers' data and the knowledge of physical parameters are the main source of inaccuracy in existing modelling approaches. The proposed approach is applied to a four lumped parameters model of a Conergy E215P solar module. Tests are performed under natural light. The parameter identification procedure is described in deta…

A fuell cell-supercapacitor hybrid power supply for portable applications

Micro Fuel Cell for Powering Portable Electronic Market

Non-Linear Digital Control for DC-DC Power Converter

Experimental test on a fuel cell-supercapacitor hybrid power supply for a digital still camera

Wireless battery chargers for portable applications: Design and test of a high-efficiency power receiver

In this study, the authors present a 5 W wireless battery charger for handheld devices. Efficiency-related issues are addressed. A power receiver architecture which improves power conversion efficiency is proposed. Design hints are provided for further applications. Comparison with a conventional architecture is provided as well. Laboratory prototypes of both the proposed and the conventional architectures have been realised. Both prototypes are tested by using the same power transmitter to perform a valuable comparison. As shown by the experimental results, in the receiver side power conversion efficiency is increased up to 99% thanks to the proposed solution.

MATLAB Co-Simulation Tools for Power Supply Systems Design

ion level. Circuit simulation software as Powersim PSIM and Orcad Pspice are the most common choice for circuit modelling. In (Basso, 2008), the design and simulation of switchmode power supplies is deeply analyzed and simulation tips in several environments are proposed. ASIC simulation and verification tools as Xilinx ISE/Modelsim or Aldec ActiveHDL are available to implement the digital controller by the VHDL or VERILOG source code. Since the interaction between subsystems is the most common source of faults, testing separately analog and digital subsystems by the means of different verification tools is a severe mistake. Matlab is a powerful simulation environment for mixed-mode systems…

A High-Efficiency, Low-Cost Solution for On-Board Power Converters

Wide-input, low-voltage, and high-current applications are addressed. A single-ended isolated topology which improves the power efficiency, reduces both switching and conduction losses, and heavily lowers the system cost is presented. During each switching cycle, the transformer core reset is provided. The traditional tradeoff between the maximum allowable duty-cycle and the reset voltage is avoided and the off-voltage of active switches is clamped to the input voltage. Therefore, the system cost is heavily reduced and the converter is well suited for wide-input applications. Zero-voltage switching is achieved for active switches, and the power efficiency is greatly improved. In the output …