DC Power Converter Research Articles

Features measurement and reliability considerations on a proposed main converter for LHC experiments

Equipment working in hostile environment are the aim of this paper. Devices operating in the hostile environment such as found in future experiments at LHC will be called to work with a level of background radiation able to cause accumulation of a Total Ionizing Dose (TID) up to 10kGy in Silicon, and fluences up to 2×1013protons/cm2 and 8×1013neutrons/cm2 but also a high level of magnetic field. This new scenario will be taken into account and it will be very important in future when the High Luminosity (HL) LHC will be operative. It is so important, at this aim, to consider the fact that also the electronic converters devoted to generate the supply for the electronic circuits can be often called to operate in hostile environment. Thus, the power supply is a key aspects in this scenario and new converters need to be ad-hoc re-designed in order to meet the future requirements that will be very stringent. In this paper a main DC–DC power converter, developed by authors in the framework of the APOLLO R&D project, has been proposed. The experimental activity devoted to its electrical and thermal characterization, which can be defined as mandatory in order to obtain an evaluation of the features, is presented and deeply discussed. It is also important to characterize the system in order to evaluate the dependability features such as the RAMS (Reliability, Availability, Maintainability Safety) requirements. In particular, reliability is a very important aspect in experiments as ATLAS at CERN where maintenance should be scheduled only during the shutdown time. Also these aspects have been considered and discussed in the paper.

Power Loss Prediction and Precise Modeling of Magnetic Powder Components in DC–DC Power Converter Application

In power electronics applications, magnetic components are often subjected to nonsinusoidal waveforms, variable frequencies, and dc bias conditions. These operating conditions generate different losses in the core compared to sinusoidal losses provided by manufacturers. In the conception and design stage, lack of precise losses diagnosis has unacceptable effects on sys-tem's efficiency, reliability, and power consumption. Since virtual prototyping is used to predict and improve system's behavior before realization, losses and behavior prediction of components is possible. Circuit simulators and their compatible components models are required. This paper is summarized by proposing nonlinear dynamic model of powdered material magnetic core for use in circuit simulators. It includes the material's nonlinear hysteresis behavior with accurate winding and core modeling. The magnetic component model is implemented in circuit simulation software Simplorer using VHDL–AMS modeling language. Waveforms and losses of a powder core inductor in a buck converter application are simulated and compared to measured ones. The model is validated for different ripple currents, different loads, and a wide frequency range. DC bias is taken into account in both continuous and discontinuous conduction modes.

Modelling Miniature Incandescent Light Bulbs for Thermal Infrared ‘THz Torch’ Applications

The ‘THz Torch’ concept is an emerging technology that was recently introduced by the authors for implementing secure wireless communications over short distances within the thermal infrared (20-100 THz, 15 μm to 3 μm). In order to predict the band-limited output radiated power from ‘THz Torch’ transmitters, for the first time, this paper reports on a detailed investigation into the radiation mechanisms associated with the basic thermal transducer. We demonstrate how both primary and secondary sources of radiation emitted from miniature incandescent light bulbs contribute to the total band-limited output power. The former is generated by the heated tungsten filament within the bulb, while the latter is due to the increased temperature of its glass envelope. Using analytical thermodynamic modelling, the band-limited output radiated power is calculated, showing good agreement with experimental results. Finally, the output radiated power to input DC power conversion efficiency for this transducer is determined, as a function of bias current and operation within different spectral ranges. This modelling approach can serve as an invaluable tool for engineering solutions that can achieve optimal performances with both single and multi-channel ‘THz Torch’ systems.

Technologies of Junction Box for Seafloor Observation Network

By using submarine cable and junction box to wire the science instruments deployed on the seafloor or in the water column into a network and combining with the terrestrial Internet and power gird to form the seafloor observation network that enables long-term, continual, real-time and in-situ ocean observing has become an important platform for ocean science research. The key technologies for designing junction box are studied and presented, including power transmission and conversion; high bandwidth communication and precise timing; power fault detection and isolation; and sealing and construction design. Based on the studied technologies, some prototypes of the junction box are built. Tests like water tank and high pressure simulative tests, shallow sea operation trial, and deep sea operation trial are carried out successfully and validated the relative technologies: Power distribution and management method based on DC power conversion can be applied on seafloor observation network; point to point communication on trunk cable via optical fibers and multi-stage tree communication structure could satisfy its requirement; detecting and isolating over-voltage, over-current and ground faults on individual port can enhance the reliability of the system; and modularized design and detachable structure could lower the cost and make it maintainable.

Low Frequency Conducted Emissions of Grid Connected Static Converters

Pulse-width modulated rectifiers are nowadays commonly used for AC to DC power conversion. PWM rectification technology is very effective and allows for bidirectional power flow with the possibility of power factor improvement and low-order harmonic emission limitation. Unfortunately, employed PWM boost topology results with generation of input current harmonic distortions in a frequency range tightly correlated to modulation frequency. PWM carrier frequency and its harmonic components in typical applications are usually located in frequency range from single kHz up to hundreds of kHz. Increase of harmonic emission in this particular frequency range can be disturbing for other sensitive systems, therefore can cause lack of electromagnetic compatibility. Interferences in low frequency range are increasingly frequent EMC issue because of extensive use of low power PWM rectifiers and significant increase of rated power of individual converters, which already reach several MW. Presented comparison of current harmonic emission spectra of PWM rectifiers with relation to classic diode rectifiers is focused on frequency range of 2 to 9 kHz, for which emission limitation rules are currently under development. New class of EMC problems arising in low frequency range in power system are underlined as a result of increased harmonic emission in frequency range of 2 to 9 kHz.

モジュラー・マルチレベル・カスケード変換器を用いたFTF（Front-To-Front）システムの実験検証

SUMMARY This paper presents an experimental discussion on modular multilevel cascade converters based on double-star chopper cells (MMCC-DSCC). Hereinafter, a single MMCC-DSCC is referred to simply as a “DSCC”. A couple of DSCCs are used to form a front-to-front (FTF) system capable of dc voltage matching and galvanic isolation between two dc grids. The FTF system can be considered as a dc–ac–dc power conversion system including an ac-link high-power transformer. The higher the ac-link frequency, the smaller and lighter are the ac-link transformer and dc capacitors. When the so-called “phase-shifted-carrier PWM” is applied to the DSCC, theoretical analysis and computer simulation have confirmed that a ratio of the carrier frequency with respect to the ac-link frequency can be reduced to 5/2. This paper designs, constructs, and tests a 400-Vdc 10-kW downscaled FTF system with a carrier frequency of 450 Hz and an ac-link frequency of 180 Hz, where their ratio is 5/2. Experimental waveforms obtained from the downscaled system are compared with simulated ones obtained from a software package, PSCAD/EMTDC, under the same operating and circuit conditions. They agree well each other not only under steady states but also under transient states.

SiC Based Single Chip Programmable AC to DC Power Converter

A single chip Programmable AC to DC Power Converter, consisting of wide band gap SiC MOSFET and SiC diodes, has been proposed which converts high frequency ac voltage to a conditioned dc output voltage at user defined given power level. The converter has high conversion efficiency because of negligible reverse recovery current in SiC diode and SiC MOSFET. High frequency operation reduces the need of bigger size inductor. Lead inductors are enough to maintain current continuity. A complete electrical analysis, die area estimation and thermal analysis of the converter has been presented. It has been found that settling time and peak overshoot voltage across the device has reduced significantly when SiC devices are used with respect to Si devices. Reduction in peak overshoot also increases the converter efficiency. The total package substrate dimension of the converter circuit is only 5 mm × 5 mm. Thermal analysis performed in the paper shows that these devices would be very useful for use as miniaturized power converters for load currents of up to 5-7 amp, keeping the package thermal conductivity limitation in mind. The converter is ideal for voltage requirements for sub-5 V level power supplies for high temperatures and space electronics systems.

Peak-Efficiency Detection and Peak-Efficiency Tracking Algorithm for Switched-Mode DC–DC Power Converters

In this paper, the system allowing to detect the peak-efficiency point of the periodically switching MOS power transistor is presented. The use of this system concerns namely the integrated dc-dc converters, charge pumps, class-E amplifiers, or isolated MOSFET power switches. Information about the peak-efficiency point position can be used to modify the power-switch operating conditions, which allows us to obtain the maximal available power-efficiency for a given operating point. The algorithm of the peak-efficiency tracking is developed here on the example of integrated 3.2 MHz step-down (buck) 5-A dc-dc converter. In this example, sizes of NMOS and PMOS power transistors are adjusted “on the fly,” in order to obtain the highest possible efficiency. In particular, power efficiency is optimized for the output current IOUT, battery and output voltages VBAT and VOUT, switching frequency fSW, temperature, and process variations. The principle of the method relies on the balancing of the Joule heat energy dissipated on the resistive elements, and energy dissipated during the charging process of the transistors' driving capacitances. As the result of the peak-efficiency tracking algorithm, the flat efficiency curve is obtained in a wide current range.

High efficient series resonant converter using direct power conversion

This study proposes a high efficient series resonant ac–dc converter. The proposed series resonant converter has a structure integrated with an ac chopper. The proposed converter provides turn-on with zero-voltage switching of all switches and performs direct power conversion without several power conversion processes. Therefore the proposed converter can achieve high efficiency by minimising losses during ac–dc power conversion. In addition, it achieves high power factor without an additional circuit. The concept and operation principle of the converter are analysed and verified. A 300 W prototype is implemented to show the performance of the proposed converter.

Small‐capacity grid‐connected solar power generation system

A small-capacity grid-connected solar power generation system, configured by a dual-output DC–DC power converter and a seven-level inverter, is proposed in this study. Voltage doubler based topology is used to configure the dual-output DC–DC power converter to convert the output voltage of a solar cell array into two dependent voltage sources with multiple relationships. The grid-connected seven-level inverter is configured by a dual-buck power converter and a full-bridge power converter. The dual-buck power converter is switched at high-frequency pulse-width modulation to generate a four-level DC voltage. The full-bridge power converter is switched synchronous with the utility voltage, to convert the four-level DC voltage into a seven-level AC voltage. The proposed solar power generation system generates a sinusoidal output current in phase with the utility voltage. The novelty of this proposed seven-level inverter is that two asymmetric DC voltage sources are used to increase the voltage levels and only two of the six power electronic switches in the seven-level inverter are switched at high frequency. A prototype is developed and tested to verify the performance of the proposed solar power generation system. The experimental results show that the proposed solar power generation system has the expected performance.

English

The quest for efficient power and energy sustainability has been of utmost importance to technological development. Power generation, transmission and distribution undeniably have been impeded by inherent harmonic distortions emanating from power lines and power devices. The attenuation of this harmonic is made possible using appropriate power semiconductor device. This paper therefore detailed a complete analysis of a grid connected hybrid pulse width modulated multi-level converter applied in a distributed power generation. The stage by stage dc power conversion from the photovoltaic supply in relation to the solar irradiance at different operating temperature of photovoltaic (PV) radiation is presented in this work. A mathematical modeling and Simulink block modeling of a d.c boost converter needed for increasing the PV output voltage to appreciable magnitude is incorporated. A follow up is a complete model of the hybrid five level a.c converter which is formed by a cascade of three level flying capacitor and H-bridge inverter modulated with the conventional multi-carrier sinusoidal method of pulse-width modulation at 0.8 modulation index. The synchronization of the multilevel a.c converter output voltage with the utility was actualized using the inductor current interface. A computer simulation of the proposed model was carried out in MATLAB/SIMULINK and the corresponding results were presented for analysis.

Design of a Miniaturized Vibrating Beam Power Converter

One of the largest components on miniaturized, multichip modules is the chip inductor associated with the onboard DC to DC power converter. It is an essential component for efficient conversion of the system voltage to the operating voltage of the module. In a previous paper, we described how vibrating capacitor structures could be used to perform inductor functions. In this paper, we focus on the specific application of an on-board power converter. Our vision is for a MEMS scale device that could be attached to the back of a chip as an appliqué or embedded in an interposer on which the chip was mounted. It would function as a DC to DC converter to extract power from the system buss and supply it to the chip at its required operating voltage. This device consists of a long, flat, rectangular, vibrating beam that is sandwiched between two fixed electrodes. It is clamped at its two ends and electrically connected to ground. On one of the fixed electrodes, which we refer to as the source electrode, a bias potential is applied through a resistor connected to a battery. The motion of the beam relative to the source electrode generates a sinusoidal like fluctuation in the potential between them. The amplitude of this alternating voltage is set by the amplitude of the beam vibration and the nominal gap between the beam and source electrode. It can be made insensitive to variations in battery voltage, by controlling the amplitude of the beam vibrations. The sinusoidal portion of the bias voltage can be extracted through a DC blocking capacitor connected to the source electrode. By passing it through a rectifier and filter capacitor, it can be used as a stable DC supply voltage. The beam vibration is initiated and sustained by voltage pulses applied to the other fixed electrode, which we refer to as the drive electrode. A logic circuit connected to the source electrode monitors its sinusoidal voltage and applies a pulse to the drive electrode when two criteria are met. First, the sinusoidal voltage must be rising, which occurs when the beam is moving away from the source electrode and towards the drive electrode. Second, the time average of the sinusoidal voltage must be below its desired set point, which means that more energy must be injected into the beam. When voltage is applied to the drive electrode, it exerts a force on the vibrating beam that pulls it towards the drive electrode. We have constructed a Mat Lab model of a vibrating beam power converter and have been using it to examine a number of design factors including, physical size, vibration frequency and amplitude, values for the DC blocking and output filter capacitors, as well as the logic used to apply pulses to the drive electrode. Our intent is to develop a sufficient understanding of the device operational and physical design requirements to enable us to build a prototype device.

Seven‐level active power conditioner for a renewable power generation system

A seven-level active power conditioner (SLAPC) used to inject the real power of the clean power source into the grid is proposed in this study. This SLAPC is composed of a four-level DC–DC power converter and a full-bridge inverter. The four-level DC–DC power converter converts the output voltage of the clean power source into a four-level pulse voltage. The full-bridge inverter is switched at low frequency and synchronised with the utility voltage and the output voltage of SLAPC is a seven-level AC voltage. Accordingly, the switching power loss, harmonic distortion and electromagnetic interference caused by the switching operation of power electronic switches are reduced because of the four-level in the DC side and the seven-level in the AC side of the full-bridge inverter. In addition, the proposed SLAPC acts as an active power filter that filters out the harmonic current of the load, so the utility current of the proposed SLAPC is a sinusoidal current and in phase with the utility voltage. A hardware prototype is developed to verify the performance of the proposed SLAPC. The experimental results show that the performance of the proposed SLAPC is as expected.

Designing fuzzy logic controllers for DC–DC converters using multi-objective particle swarm optimization

This paper proposes a new method for designing fuzzy logic controllers for voltage-regulated DC–DC power converters. Low sensitivity to input voltage variations, fast regulation during load transients and robustness against the aging process of the converter passive components are the main features achievable through the proposed approach. The multi-objective particle swarm optimization (MO-PSO) is used to find multiple Pareto-optimal solutions in a multi-objective optimization problem for the identification of the best possible membership functions and rules of the fuzzy controller. In order to evaluate the effectiveness of the proposed technique, different cases have been tested in laboratory on a buck converter prototype, considering deep input voltage deviations and big load transients, as well as variations in the nominal values of the passive components of the system. A comparison with a classical proportional-integral (PI) controller demonstrates the high performances of the proposed technique in terms of effective output voltage regulation under different operating conditions.

Design of Integrated Bipolar Symmetric Output DC–DC Power Converter for Digital Pulse Generators in Ultrasound Medical Imaging Systems

This paper presents a bipolar symmetric output switching dc–dc converter for digital pulse generators in ultrasound medical imaging systems. The proposed power stage architecture can generate symmetric bipolar supply voltages, while operating in a time-interleaving manner. Meanwhile, in order to power unipolar pulse generators with the same peak-to-peak pulse amplitude, the power stage can also be reconfigured to deliver a 2× unipolar output voltage. The power converter employs an adaptive <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex Notation="TeX">${\Delta}I$</tex></formula> charge balance control scheme to ensure that the outputs are symmetrically balanced and well regulated. At the circuit level, to utilize a single feedback controller for both power stage topologies, the assignment of a suitable chip ground is discussed. A prototype is fabricated using a 0.25-μm CMOS process and occupies a chip area of 6 mm <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex Notation="TeX">$^{2}$</tex></formula> . For an input supply voltage of 1.5 V, the dc–dc converter can regulate the bipolar outputs at a nominal voltage level of ±2.5 V and at 5 V for the unipolar output configuration and a maximum load current of 45 mA for both. The bipolar output power converter achieves a maximum efficiency of 83.4% at a load power of 187.5 mW, with the voltage balance error maintained within ± 2% over the entire load range.

Position control of an electro-pneumatic system based on PWM technique and FLC

In this paper, modeling and PWM based control of an electro-pneumatic system, including the four 2–2 valves and a double acting cylinder are studied. Dynamic nonlinear behavior of the system, containing fast switching solenoid valves and a pneumatic cylinder, as well as electrical, magnetic, mechanical, and fluid subsystems are modeled. A DC–DC power converter is employed to improve solenoid valve performance and suppress system delay. Among different position control methods, a proportional integrator derivative (PID) controller and fuzzy logic controller (FLC) are evaluated. An experimental setup, using an AVR microcontroller is implemented. Simulation and experimental results verify the effectiveness of the proposed control strategies.

Research & Implementation of AC—DC Converter with High Power Factor & High Efficiency

In this paper, we design and develop a high power factor, high efficiency two-stage AC—DC power converter. This paper proposes a two-stage AC—DC power converter. The first stage is boost active power factor correction circuit. The latter stage is near constant frequency LLC resonant converter. In addition to traditional LLC high efficiency advantages, light- load conversion efficiency of this power converter can be improved. And it possesses high power factor and near constant frequency operating characteristics, can significantly reduce the electromagnetic interference. This paper first discusses the main structure and control manner of power factor correction circuit. And then by the LLC resonant converter equivalent model proceed to circuit analysis to determine the important parameters of the converter circuit elements. Then design a variable frequency resonant tank. The resonant frequency can change automatically on the basis of the load to reach near constant frequency operation and a purpose of high efficiency. Finally, actually design and produce an AC—DC power converter with output of 190W to verify the characteristics and feasibility of this converter. The experimental results show that in a very light load (9.5 W) the efficiency is as high as 81%, the highest efficiency of 88% (90 W). Full load efficiency is 87%. At 19 W ~ 190 W power changes, the operating frequency change is only 0.4 kHz (AC 110 V) and 0.3 kHz (AC 220 V).

Recurrent wavelet neural network control of a PMSG system based on a PMSM wind turbine emulator

A recurrent wavelet neural network (NN)-controlled 3-phase permanent magnet synchronous generator system (PMSG), which is direct-driven by a permanent magnet synchronous motor (PMSM) based on a wind turbine emulator, is proposed to control the output values of a rectifier (or AC to DC power converter) and inverter (or DC to AC power converter) in this study. First, a closed-loop PMSM drive control based on a wind turbine emulator is designed to generate the maximum power for the PM synchronous generator (PMSG) system according to different wind speeds. Next, the rotor speed of the PMSG, the DC bus voltage, and the current of the power converter are detected simultaneously to yield a better power output of the converter through DC bus power control. Because the PMSG system is a nonlinear and time-varying dynamic system, one online-trained recurrent wavelet NN controller is developed for the tracking controller of the DC bus power to improve the control performance in the output end of the rectifier. Additionally, another online-trained recurrent wavelet NN controller is also developed for tracking the controller of the AC power to improve the control performance in the output end of the inverter. Finally, some experimental results are verified to show the effectiveness of the proposed recurrent wavelet NN-controlled PMSG system direct-driven by a PMSM based on a wind turbine emulator.

Analysis of EMI on control signal line of DC power converter of electric vehicle

Development of electric vehicles is promoted by the increasing problems about the severe shortage of oil resources and serious environment pollution at present. The interference produced by the new high–power electronic equipment in electric vehicles will have influence on the equipment that is attached to it, especially the effect it has on the control circuit cannot be ignored. In this paper, in the four typical working states of electric vehicles, research on the conducted interference current features on the control line of DC converter system is done, reasons for interference coupling to the control line are analysed, and the conclusion is drawn that the value of interference current on the control line in starting state and charging state is the maximum and that value decreases in high–speed state and idle–speed state.

Modeling and Control of a Grid Connected PAFC System

This paper presents a closed-loop control of a 440kW fuel cell system including power electronics and grid side filters. Simulation results show the dynamics of a phosphoric acid fuel cell (PAFC) and its associated power electronics including grid connection. The proposed model is based on empirical equations and Simulink blocks. The modeling and simulation is done in Matlab/Simulink software with its Power System Blockset (PSB). This model mathematically calculates cell output voltages and their consequent losses. Moreover, this model includes dc power conversion of fuel cell output into ac and grid interface. Presented model is simple and easy to understand.