0000000000087932
AUTHOR
Filippo Marino
A Novel Linear-Non-Linear Digital Control for DC/DC Converter with Fast Transient Response
In this paper, a digitally controlled multimodule DC-DC converter with fast transient response, based on a linear-nonlinear 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 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 environm…
A novel digital control for DC/DC converters to improve steady-state performances
This paper describes an innovative digital PWM control implementation for low voltage, high current DC-DC converters. The proposed technique, based on the use of a low resolution DAC, improves steady-state performances, minimizing limit cycle effects. The novel technique is tested on a FPGA-based single phase buck converter operating at 250 kHz. A detailed description of the proposed architecture is given and test results, simulation and experimental ones, are shown
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…
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…
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.
Current-Sensing Technique for Current-Mode Controlled Voltage Regulator Modules
This paper introduces an innovative current-sense technique for voltage regulator modules (VRMs). The proposed method is applied to a multiphase buck converter although the converter topology does not affect the accuracy or effectiveness of the proposed technique. A RC network is parallel connected with the buck converter low-side MOSFET and the voltage signal across the sense capacitor reconstructs the inductor current waveform. The RC technique benefits from all the advantages of the most popular current-sensing technique, the inductor DC resistance current-sense method, cutting off its main disadvantage. The sense network design is oriented to obtain high immunity to noise and a great dy…
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…
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 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…
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.
Evaluation and management of hemorrhoids: Italian society of colorectal surgery (SICCR) consensus statement
Hemorrhoids are one of the most common medical and surgical diseases and the main reason for a visit to a coloproctologist. This consensus statement was drawn up by the Italian society of colorectal surgery in order to provide practice parameters for an accurate assessment of the disease and consequent appropriate treatment. The authors made a careful search in the main databases (MEDLINE, PubMed, Embase and Cochrane), and all results were classified on the basis of the grade of recommendation (A-C) of the American College of Chest Physicians.
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…
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.
Linear-non-linear digital control for dc/dc converters with fast transient response
A linear-non-linear digital control for multi-module DC/DC converters that improves system stability, solves the limit-cycle problem, reduces recovery time and limits over- and under-shoots in regulated output voltage, is presented. A simulation model in Matlab-Simulink/Active-HDL mixed environment is described. Preliminary hardware tests on a single-phase step-down converter are reported. Simulation and experimental results are shown.
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.