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This paper analyzes supercapacitor energy loss and investigates its impact on power management in environmentally powered wireless sensor nodes that use supercapacitor-based energy storage systems. While supercapacitor self-discharge is usually taken into account for system design and power management in wireless sensor nodes, supercapacitor charge redistribution and the associated energy loss have not been considered. In an environmentally powered wireless sensor node, supercapacitor charge redistribution may have more significant impact on power management than self-discharge. This paper analyzes supercapacitor energy loss during charge redistribution based on the variable leakage resistance (VLR) model. It is concluded that supercapacitor energy loss is dependent on charge redistribution time and supercapacitor initial state, which is defined as the initial voltages across the capacitors in the VLR model. The impact of supercapacitor energy loss on power management is studied by considering the task scheduling problem. A set of simulation cases that covers various supercapacitor initial state and energy harvesting capability is designed to investigate the impact of supercapacitor energy loss on task scheduling policy. It is demonstrated that greedy or lazy scheduling policy is preferred depending on supercapacitor initial state and energy harvesting capability in terms of two performance evaluation metrics. [ABSTRACT FROM AUTHOR]

A new three-level dc/dc converter is proposed in this paper. The outstanding features of this converter are that it operates with zero-voltage-switching (ZVS) from full-load to near no-load conditions with hardly any circulating freewheeling primary current due to its novel structure. Since the converter has little primary circulating current and its switches are exposed to only half of the input voltage, it has high efficiency even under light loads. In this paper, the new converter is introduced, its basic operating principles are explained, its modes of operation and its steady-state characteristics are discussed in detail as is its design, and experimental results obtained from a prototype converter that confirm its feasibility are presented. [ABSTRACT FROM AUTHOR]

An adaptive control method, to be called maximum efficiency point tracking (MEPT), is presented in this paper. This method tracks system efficiency, which is dc-dc converter efficiency in this paper, and adaptively optimizes system parameters to maximize efficiency. The MEPT method is used in this paper to optimize the primary-to-secondary switches' dead-time parameter in an isolated topology to reduce the switches' body diodes conduction during commutation periods and to reduce body diodes conduction and reverse-recovery related losses in order to improve efficiency. MEPT tracks converter efficiency while changing the dead-time and detects the optimized dead-time value at the maximum efficiency point at different load and line conditions. In this paper, the MEPT method is discussed and analyzed, and its digital control algorithm and experimental implementation are presented. [ABSTRACT FROM AUTHOR]

Transformer parasitics such as leakage inductance and self-capacitance are rarely calculated in advance during the design phase, because of the complexity and huge analytical error margins caused by practical winding implementation issues. Thus, choosing one transformer architecture over another for a given design is usually based on experience or a trial and error approach. This paper presents analytical expressions for calculating leakage inductance, self-capacitance, and ac resistance in transformer winding architectures (TWAs), ranging from the common noninterleaved primary/secondary winding architecture, to an interleaved, sectionalized, and bank winded architecture. The calculated results are evaluated experimentally, and through finite-element simulations, for an RM8 transformer with a turns ratio of 10. The four TWAs such as, noninterleaved and nonsectioned, noninterleaved and sectioned, interleaved and nonsectioned, and interleaved and sectioned, for an EF25 transformer with a turns ratio of 20, are investigated and practically implemented. The best TWA for an RM8 transformer in a high-voltage bidirectional flyback converter, used to drive an electro active polymer based incremental actuator, is identified based on the losses caused by the transformer parasitics. For an EF25 transformer, the best TWA is chosen according to whether electromagnetic interference due to the transformer interwinding capacitance, is a major problem or not. [ABSTRACT FROM AUTHOR]

New advanced power conversion systems play an essential role in the extension of range and life of batteries. This paper proposes a new modular multilevel converter with embedded electrochemical cells that achieves very low cell unbalancing without traditional balancing circuits and a negligible harmonic content of the output currents. In this new topology, the cells are connected in series by means of half-bridge converters, allowing high flexibility for the discharge and recharge of the battery. The converter features a cell balancing control that operates on each individual arm of the converter to equalize the state of charge of the cells. The paper shows that the proposed control does not affect the symmetry of the three-phase voltage output, even for significantly unbalanced cells. The viability of the proposed converter for battery electric vehicles and the effectiveness of the cell balancing control are confirmed by numerical simulations and experiments on a kilowatt-size prototype. [ABSTRACT FROM AUTHOR]

A new soft-switching pulse-width-modulated (PWM) full-bridge converter is proposed in this paper. The proposed converter has zero voltage switching (ZVS) in all its switches with fewer conduction losses than other ZVS-PWM full-bridge converters, due to a novel auxiliary circuit scheme. In this paper, the operation of the new converter is explained and analyzed, a design procedure is presented and demonstrated with an example, and experimental results that confirm the feasibility of the converter are also presented. [ABSTRACT FROM AUTHOR]

High-intensity-discharge (HID) lamps are widely utilized in a variety of lighting circumstances that need high luminance. This paper proposes a single-stage electronic ballast for HID lamps; the ballast offers power factor correction and is acoustic resonance free. The presented HID lamp ballast integrates a discontinuous-conduction-mode (DCM)-operated bridgeless power factor correction (PFC) converter for shaping the input utility-line current with a high-frequency (36 kHz)/low-frequency (60 Hz) square-wave-driven half-bridge inverter for supplying low-frequency (60 Hz) square-wave sources to the HID lamp. The features of the proposed ballast are high power factor, low total harmonic distortion (THD) of the input current, cost effectiveness, and that it avoids acoustic resonance. The operational modes, key design guidelines, and a design example are included. A 70 W prototype HID lamp ballast circuit operating with 110 V-rms input utility-line voltage has been implemented and testified. The functionalities of the presented ballast are demonstrated by satisfactorily experimental results with a maximum efficiency of 90.8%, a maximum power factor of 0.998, and a minimum current THD of 11.13%. [ABSTRACT FROM AUTHOR]

This paper presents an electric equivalent model applied to induction electrodeless fluorescent lamps. The model is based on passive components and takes into account the real and reactive lamp power. The presented model and its obtention methodology will be an important tool for ballast designers. One of the most important features of the proposed methodology is the concern regarding core losses and lamp reactive characteristics, because nowadays there are no electric models including these characteristics. In order to obtain and validate the electrodeless lamp model, a series–parallel resonant half-bridge inverter is used as ballast. Plasma and lamp windings are modeled as resistances and reactances depending on the lamp power. Simulations employing the proposed model are also presented, showing an excellent agreement with experimental results. [ABSTRACT FROM PUBLISHER]

In this paper, the use of input current shaper converters (ICSCs) working in discontinuous-conduction mode to stabilize the discharge arc in high intensity discharge lamps without close loop control is proposed. The analysis of how the ICSC stabilizes the lamp current, the description of the proposed topology and the design methodology are presented. Experimental results indicated the feasibility to stabilize the lamp with no close loop control and obtaining high efficiency with fewer components that conventional ballasts used for this application. Experimental results when dimming is applied are included too. [ABSTRACT FROM AUTHOR]

This paper presents the analysis and design method of a new configuration of resonant inverter suitable for high-intensity discharge (HID) lamp ballast applications. The proposed inverter results from the parallel connection of four class D LCp resonant inverters, sharing the total load current. In this way, the conduction losses are reduced and high frequency operation is achieved for high power lamps. The power control is implemented at constant frequency, modifying the phase displacement among the output voltages of each inverter section. Considering that the deviation of the operation point caused by the control action deteriorates the converter efficiency, this design guarantees minimum control action to correct the lamp power deviation caused by the lamp aging. A 600-W prototype has been built to validate the design proposal. [ABSTRACT FROM AUTHOR]

In this paper, a simple method to obtain the small-signal model of discharge lamps, and particularly metal halide (MH) lamps, is proposed. A dc voltage source with a series resistor is used to supply the lamp at the required power level. Then, the lamp response against an input voltage step transient is analyzed. From this analysis, the parameters of the equivalent lamp model can be calculated. The proposed method allows obtaining the lamp model in a straight manner from a single test. With this technique, a 35-W MH lamp is modeled at two different power levels. A validation circuit, which includes a resistive ballast and a capacitance, is analyzed to evaluate the possibilities of the proposed modeling technique. The obtained experimental results are in good agreement with the theoretical analysis. The derivation of a time domain lamp model for SPICE-based computer simulators is also introduced. Finally, an example of application in low-frequency square-waveform electronic ballasts is presented. [ABSTRACT FROM AUTHOR]

Take the case of parallel modules in battery discharging regulator of power conditioning unit, which is based on Weinberg topology, a conductance compensator used in average current mode control is proposed in this paper, which could ensure constant loop bandwidth and output impedance when the number of operating parallel modules changes. The design principle of conductance compensator is shown as that the total conductance coefficient keeps constant when the number of operating parallel modules changes. Besides, a circuit of the conductance compensator, and the timing between the regulation of conductance compensator and ON/OFF of parallel modules, as well as the frequency-domain constraints of each function part in outer voltage control loop, are also illustrated. Additionally, measurements of the loop characteristic and output impedance of regulated power bus with different numbers of operating parallel modules, as well as the voltage ripple and current waveforms at the ON/OFF moment of parallel modules (four parallel modules in total), have been carried out, validating the design purpose of the proposed conductance compensator. [ABSTRACT FROM AUTHOR]

An advanced technique of energy compression with the third harmonic circulating current generation is presented in this paper to improve the surface treatment performance in the dielectric barrier discharge (DBD) systems. First, the relationship between the energy compression degree and contact angle is explored, which shows that the polymer surface wettability can be improved by the high energy compression degree in DBD. And then, an additional inductor is inserted into the resonant tank in the current-fed parallel-series resonant converter to generate the third harmonic current component, which can reduce the discharge-time-ratio and compress the energy transferred to the DBD loads. Furthermore, the method of rectifier-compensated fundamental plus third harmonic approximation (RCFTHA) is introduced to describe the current-fed parallel-series resonant converter by superposing two equivalent linear circuits operating at the fundamental and third harmonic frequencies, respectively. Consequently, the discharge-time-ratio optimization with the parallel-series resonant tank design is realized. Finally, the experimental results from a 350-W prototype substantiate the effectiveness of the energy compression with the third harmonic circulating current and the accuracy of RCFTHA. [ABSTRACT FROM AUTHOR]

Hybrid multilevel converters combine features of conventional multilevel topologies to provide an acceptable tradeoff between the advantages and disadvantages of these converters. For many industrial applications, common dc link is a requirement that limits the choice of topologies to neutral point clamped (NPC) and flying capacitor multicell (FCM) hybrid types. This paper investigates the operation of a hybrid five-level topology and proposes a modulation method that takes the advantage of the combined features of NPC and FCM. The dual flying capacitor (FC) active-neutral-point-clamped (DFC-ANPC) converter provides certain advantages such as natural soft switching of line frequency switches, elimination of the transient voltage balancing snubbers, and a more even loss distribution. Simulation results and experimental verification of the five-level DFC-ANPC converter are presented to validate the performance of the converter as well as the applied modulation technique. [ABSTRACT FROM AUTHOR]

Electric vehicles make use of energy storage systems, such as batteries and/or ultracapacitors to power the electric power drive train, as well as auxiliary automotive system for control, safety, and comfort. This relatively complex power structure can be described as a distributed multiconverter system. The constant power behavior of tight-speed controllers in the vehicle's traction system and tightly regulated dc-dc converters connected to the HV-DC bus produces instability effects. This paper proposes a simple and practical geometric control, using circular switching surfaces, to address constant power load instability in electric vehicle's power systems. The proposed switching surfaces provide a solution in the geometrical domain to constant power loading conditions, while achieving outstanding dynamic response compared to state-of-the-art controllers. The controller is implemented in a bidirectional Buck + Boost cascade converter as a battery charge/discharge unit and ensures reliable system operation. The predictable and consistent behavior of the converter with constant power load is presented by analyzing the system curves in the normalized state plane with the switching surfaces employed. Simulation and experimental results on a scaled 1-kW Buck + Boost cascade converter validate the proposed switching surfaces and predictions regarding the converter's behavior under constant power loading conditions. [ABSTRACT FROM AUTHOR]

A novel primary-side controlled universal-input ac-dc LED driver based on the source-driving control scheme is proposed in this paper, which employs low-voltage control MOSFET M2 to drive high-voltage power MOSFETM1 without an auxiliary winding commonly used in the conventional primary-side controlled scheme. The proposed control IC adopts minimum voltage detection circuit to monitor the zero crossing information of secondary winding current. The demagnetization time signal is generated by demagnetization time detection circuit. In addition, the ratio between the secondary winding demagnetization time TDemag and switching period TS is maintained constant by adopting the intelligent charging and discharging circuit, finally achieving highprecision constant output current. A control IC for the proposed LED driver has been fabricated in TSMC 0.35 μm 5 V/600 V CMOS/LDMOS process. Experimental results of a 3-W circuit prototype show that the constant current precision is within ±1% in a wide range of universal-input ac voltage from 85 to 264 V, and that above 80% efficiency is obtained when driving three 1-W LEDs. The start-up time is only 46 ms under 90 Vac and 60 Hzinput, and the standby power is tested to be lower than 142 mW under 220 Vac and 50 Hz-input. [ABSTRACT FROM AUTHOR]

In this paper, the merits of a high-frequency resonant converter for supplying dielectric barrier discharges (DBD) devices are established. It is shown that, thanks to its high-frequency operating condition, such a converter allows to supply DBD devices with short discharge current pulses, a high repetition rate, and to control the injected power. In addition, such a topology eliminates the matter of connecting a high-voltage transformer directly across the DBD device and avoids the issues related to the parasitic capacitances of the latter which disturbs the control the power transfer to the plasma. The design issues of the converter, including the inverter and its switches, the resonant inductor, and the parameter drift compensation are studied. An experimental validation is performed: a mega Hertz resonant converter using GaN FET switches has been manufactured and tested with an excimer lamp. [ABSTRACT FROM AUTHOR]

This paper presents the analysis and optimal design of a current-source four-element CLCC resonant converter used in dielectric barrier discharge (DBD) field. Mathematically, by analyzing different operating modes, the expressions that accurately describe the behavior of the converter under any load conditions are derived. In addition, the characteristic parameters are expressed as functions of inherent circuit parameters and the control variables to make the analytical results readily employed. Also, an optimal design method is developed to facilitate a decrease of the primary winding current of the transformer and a reduction of the switching frequency variation of the inverter. An 8-kW DBD power supply for the surface treatment (one of the applications of DBD) is designed using the proposed method. The simulation and experimental results are given to verify the proposed analysis and design. [ABSTRACT FROM AUTHOR]

This paper proposes a practical capacity fading model for Li-ion cells based on real operating conditions in electric vehicles (EVs). Numerous LiFePO4 cells have been cycled with a current profile containing regenerative braking to determine the capacity fading rate. The cells have been cycled at different temperatures with different initial state of charges, depth of discharges, or C-rates. From the experiments, an empirical model is constructed, which is capable of modeling the capacity fading in EV battery cells under most operating conditions. The capacity fading model can be used to estimate the state of health of EV battery cells, and simple ways to optimize the battery lifetime are proposed. [ABSTRACT FROM AUTHOR]

A thermoelectric generator (TEG) is a low-voltage high-current dc power source with a linear V–I characteristic, and therefore, it is desirable to create a power converter with a topology and control method suited to these attributes. Due to the TEG’s low voltage, a topology that produces a high step-up gain for a moderate duty cycle is required to reduce voltage and current stresses within the converter. The linear V–I characteristic produces a P–I characteristic with a flatter peak relative to other sources. This can result in large operating point variations while performing maximum power point tracking (MPPT); thus, an algorithm with low steady-state error is desired. This paper presents a novel high step-up dc/dc converter topology operating with a fractional short-circuit MPPT algorithm for use with a 4.2-V, 3.4-A (for matched load at \Delta T = \270\,^\circ C) TEG module and a converter output of 180 V. Compared to existing high step-up dc/dc converters, the proposed converter achieves higher gain with similar component count. Experimental results are reported to confirm the converter analysis and better performance of the short-circuit MPPT algorithm over the perturb and observe algorithm. [ABSTRACT FROM PUBLISHER]

This paper explores sizing and topology reconfiguration strategies for charging and discharging multiple supercapacitors as energy storage in sub-Watt-scale energy harvesters. To maximize energy efficiency for storage (\etaEstorage), total leakage power is kept low by selecting the supercapacitors to charge sequentially, alternately, or in series based on their voltages. To maximize energy efficiency for driving load (\etaEdriving), residual energy is minimized by switching to series composition of the supercapacitors in order to raise the voltage above the minimum input voltage of the load-side dc–dc converter. Due to the nonlinear, stateful, load-dependent behavior of such harvesters, parameter sweeping is used for system-level optimization. A topology-reconfigurable structure consisting of two larger, symmetric “reservoir” supercapacitors and one voltage-raising “bootcap” proves to be efficient and practical when considering combinations of symmetric and asymmetric capacitance values. Experimental results on an actual implementation show that for charging, series topology is best when input power is high due to lower leakage, and individual topology is best when input power is low due to lower voltage; for discharging, series topology is effective in reducing residual energy while individual topology with alternating discharging effectively minimizes leakage. [ABSTRACT FROM AUTHOR]

The energy-efficiency issue of switched-capacitor converters is still a controversial topic that requires a more in-depth discussion. In this paper, we address the issue by dividing the analysis of the entire efficiency problem into two parts. In the first part, the efficiency of a capacitor-charging RC circuit under different aspects (partial charging, full charging, at zero capacitor voltage, at nonzero capacitor voltage, etc.) will be conducted. The efficiency analysis of a capacitor-discharging RC circuit with a resistor, capacitor, and paralleled resistor–capacitor loads will be covered. A complete evaluation of the overall efficiency is then performed in terms of both the charging and discharging efficiencies. Based on the analysis, some design rules useful for developing high-efficiency switched-capacitor converters is suggested. Additionally, it is shown that the belief that quasi-switched-capacitor converters are more lossy than switched-capacitor converters is a common misconception. [ABSTRACT FROM AUTHOR]

This paper describes the analysis and design of an LCL resonant power supply for ozone generation. The main advantage of the proposed topology is the absence of high-voltage transformer; the high voltage gain is achievable by means of double-resonance phenomena. Furthermore, the bandwidth is wider than the ordinary LC and its phase difference is constant over specific frequency range; as a result, an open-loop operation can be implemented. The complete analysis and design procedure of the power supply is presented. The design procedure is verified by implementing the power supply to drive a dielectric barrier discharge prototype ozone chamber. The hardware results are found to be in close agreement with simulation and thus justify the validity of the design procedures. The proposed circuit is suitable for portable ozone power supply fed by low-voltage source such as battery or photovoltaic module. [ABSTRACT FROM AUTHOR]

This paper presents a photovoltaic (PV) high-intensity-discharge (HID) street lighting system. A single-ended primary inductance converter (SEPIC) is studied for maximum power point tracking (MPPT) and battery charging. High conversion efficiency and high MPPT accuracy can be achieved under different atmospheric conditions. A pulse-current-charging scheme with an adaptive rest-period is also applied to avoid battery overcharging. An electronic ballast circuit is also designed to release the solar energy stored in battery for powering HID lamps. The studied PV HID street lighting system is connected to the ac-line utility with a SEPIC power factor correction converter. High input power factor can be achieved when energy is drawn from the ac-line utility to drive the HID lamp and to prevent the battery from over-discharging. The proposed PV HID street lighting system has the advantages of high power density, simple circuit, and long lifetime. The operating principle and design considerations were analyzed and discussed in detail. A laboratory prototype was implemented and tested. The experimental results were shown to verify the feasibility of the proposed scheme. [ABSTRACT FROM AUTHOR]

In this paper, dynamic simulation of the equivalent circuit model of the supercapacitor, taking into account the parameter variations and self-discharge, is discussed. Self-discharge is modeled with equivalent impedance including a constant phase element (CPE), and the parameter variations depending on the voltage are reflected. Since it is difficult to directly simulate the ZARC element (R-CPE parallel circuit) with a circuit simulation tool such as the professional simulation program with integrated circuit emphasis (PSPICE), equivalent transformation to three R-C parallel circuits is introduced in the simulation. The accuracy of simulation with the model is then verified through a comparison with results of an experiment. The comparison shows that the model using a CPE is effective in representing the dynamic characteristics and self-discharge of supercapacitors. Accordingly, it proves that the method proposed in this study can be useful in developing systems that include supercapacitors, and can be applied in an integrated simulation of a supercapacitor and a power electronic system. [ABSTRACT FROM AUTHOR]

This paper deals with partial discharge (PD) measurements on inverter-fed motors. They are performed by means of a broadband sensor-filter system that allows PD signal to be recorded, damping the noise generated by the commutation interference of electronic power supply. In this way, online or offline measurements can be carried out with the purpose of evaluating the presence of PDs in adjustable speed drives, which often constitute the main cause of winding insulation degradation and premature breakdown. An offline testing technique is also proposed to offer an insight into PD activity and a more precise location of PD sources. These techniques can allow improved quality control and diagnostics on power-electronic-controlled motors. [ABSTRACT FROM AUTHOR]

The paper presents the design guidelines of phase controlled resonant inverters to drive high intensity discharge lamps. Considering the variation of the lamp resistance over its lifetime, the resonant phase is determined and the condition of minimum phase lag is imposed to minimize the current through the circuit. The optimum input voltage is analyzed according to phase lag, frequency variation, and control complexity. A design procedure is presented and experimentally validated with results from two electronic ballast designs operating from 300-V and 400-V dc bus and driving a 150-W high pressure sodium lamp. [ABSTRACT FROM AUTHOR]

This paper presents a constant power control circuit for a three-stage high intensity discharge (HID) electronic ballast. The three-stage electronic ballast is composed of a boost pre-regulator to achieve high power factor, a dc-dc buck converter to regulate lamp current with constant lamp power, and a full-bridge inverter to drive the HID lamp with a low frequency ac square wave current. The buck converter operating in current mode utilizes current sense level-shift technique to achieve constant power output. The proposed constant power control circuit is easily designed and implemented for the three-stage HID electronic ballast. Finally, a laboratory prototype, of a 70-W HID electronic ballast is implemented. The measured results show that the proposed ballast can be applied for various HID lamps with low lamp power variation (less than 0.6%). [ABSTRACT FROM AUTHOR]

This paper proposes a bridgeless-type ac-side continuous-conduction-mode (CCM) current-source (CS) charge-pump (CP) power-factor-correction (PFC) electronic ballast. The draw-backs of conventional dc-side discontinuous-conduction-mode (DCM) electronic ballasts include high di/dt, high current stress, and high switching losses. As a result, conventional dc-side DCM CS-CP-PFC electronic ballasts have low efficiency, due to the DCM operation, and the ballasts require a large input electromagnetic interference filter. Conventional dc-side CCM CS-CP-PFC electronic ballasts are able to solve these problems, but still require a higher component count. To efficiently reduce the cost of electronic components, a bridgeless-type ac-side CCM CS-CP-PFC electronic ballast is proposed. A 32-W rated power electronic ballast prototype circuit is designed and implemented. Experimental results verify that the input-current harmonics meet the WC 61000-3-2 Class-C Standard, and the CP capacitor helps the PFC inductor current to achieve CCM and high power factor. [ABSTRACT FROM AUTHOR]

High intensity discharge lamps are typically operated at low frequency to avoid damage from acoustic resonance. Accordingly, an electronic ballast normally comprises a buck converter to control the lamp current magnitude and a full-bridge to commutate the lamp current at a low frequency. In such a system, the negative dynamic lamp characteristic may interact with the power electronic driver may give a poorly damped response, sometimes resulting in an oscillatory lamp current. Furthermore, lamp aging and reduced power mode operation both tend to increase re-ignition voltage overshoot, which in turn may lead to reduced lifetime, or prematurely extinguishing lamps. In the present paper, a procedure for obtaining the small-signal dynamic characteristics of metal halide lamps is proposed. Using this dynamic model, the lamp-ballast interaction is simulated and analyzed. A fuzzy-logic control method is `presented to cope with nonlinear behavior and improve the lamp-ballast performance. The simulation results are verified with practical measurements on a laboratory prototype. [ABSTRACT FROM AUTHOR]

Enhanced active resonant (EAR) dc circuit breakers (DCCBs) are a novel type of DCCB that use a discharge closing switch as interruption medium. A technical limitation of discharge closing switches is the minimum voltage across the main gap required for successful triggering. A novel commutation process creating the minimum voltage internally is proposed, which allows to simplify the EAR DCCB configuration and to reduce its component count. In the prototype, the discharge closing switch is implemented with a TVG. Experiments show that the TVG can be triggered reliably down to a voltage of 50  $\mathrm{V}$ and that the discharge in the TVG is highly oscillatory at low current. The originally proposed EAR DCCB configuration has to be tuned such that the commutation to the TVG succeeds at low current. Conversely, the novel commutation process decouples the minimum voltage from the current level by adjusting the triggering delay. This allows reliable commutation irrespective of the operating conditions. It is shown that the novel commutation process does not adversely affect dc interruption. Proactive commutation operation and auto-reclosing strategies are demonstrated. [ABSTRACT FROM AUTHOR]

With ever-increasing demand of feature-rich portable electronics, single-inductor multiple-output (SIMO) converters are becoming a cost-effective option to provide different supply voltages while maintaining a long battery life. A single-discharge (SDC) control scheme is proposed to simplify the SIMO design, to achieve low cross-regulation, and to support wide range of loads with reasonable power efficiency. A SDC SIMO buck converter with four outputs composed of comparators, phased-locked loop, finite state machine (FSM) controller, and an output stage, is prototyped using TSMC's 0.18-μm BCD process. In addition to the basic switching functions, the FSM controller provides a state skipping feature to allow no-load regulation. Its functionality is verified experimentally and can convert an input voltage from 2.7 to 3.7 V to 1, 1.2, 1.5, and 1.8 V outputs. The simulated peak power conversion efficiency is 86% with a combined output power ranging from 150 to 300 mW. The packaged SDC SIMO converter ICs exhibit a lower measured peak efficiency of 73%, with a cross-regulation of 0.24 mV/mA due to the parasitic bond-wire resistance. The converter prototype can support a wide range of loading conditions, from open circuit to a total output power of 1 W. [ABSTRACT FROM PUBLISHER]

The state-of-charge (SOC) estimation approaches based on the pack model can hardly provide precise estimation due to cell difference, while the approaches based on each cell cost high computation resource, which are not suitable for real-time application. The estimation error can be further enlarged without considering balancing current. The SOC estimation approach of the battery pack considering balancing current is proposed, which dynamically searches for the cell with maximum or minimum voltage, and it only needs to calculate the selected cell in every estimation cycle. Compared to the approaches based on the pack model or each single cell, this approach can achieve precise pack SOC and cost less calculation time and resource. It has been verified with ten series-connected 200 Ah Li(NiCoMn)O2 batteries. The SOC estimation error is limited to 0.3% during the charging process, and a reduction of 2.5% is achieved compared to an error of 2.8% based on the pack model. A reduction of 1% is achieved compared to an error of 1.5% based on the pack model during the discharging process. Compared to an error of 1.7% without considering balancing current, a reduction of 1.4% is achieved during the charging process. [ABSTRACT FROM PUBLISHER]

Hard-switching-induced switching loss can contribute significantly to the power loss of an isolated bidirectional dual-active-bridge (DAB) dc–dc converter operating at high frequency. An $LC$-type series resonant DAB converter based on a switch-controlled-inductor (SCI) is proposed to mitigate the loss arising from hard switching under wide-range variations in output voltage and current. Zero-voltage switching is achieved at the primary side (high voltage), while at the secondary side (low voltage), zero-current switching is preferred to reduce excessive ringing due to circulating current and switching loss. In order to achieve reduced conduction loss, a nominal operating point is chosen where the root-mean-square resonant tank current is the minimum. To validate the proposed topology and modulation scheme, an $LC$-type series resonant DAB converter based on SCI operating at 100 kHz is designed to interface a 400-V dc bus to a supercapacitor-based energy storage. Simulation and experimental results validate the effectiveness of the proposed topology for charging/discharging a supercapacitor with an output voltage variation of between 10 and 48 V and a maximum rated power of 480 W. A maximum efficiency of 94.6% is achieved using the proposed topology and modulation scheme. [ABSTRACT FROM PUBLISHER]

A resonant switched capacitor converter with high efficiency over a wide and continuous conversion ratio range is introduced. The efficiency of the topology depends primarily on the conduction losses and is decoupled, to a large extent, from the voltage conversion ratio. This is an advantage over classical switched capacitor converters, for which the efficiency is strongly related to the conversion ratio. The operation principle applies three zero current switching states to charge, discharge, and balance the remaining charge of the flying capacitor. This results in a gyrator, i.e., a voltage-dependent current source, with a wide range of voltage conversion ratios (smaller as well as greater than unity) as well as bidirectional power flow capabilities. The analytical expressions for the conversion ratio and expected efficiency are provided and validated through simulations and experiments. The experimental verifications of the converter demonstrate peak efficiency of 96% and above 90% efficiency over a wide range of voltage gains and loading conditions. In addition, the system was found to be highly efficient at the extreme cases of both light and heavy loads. [ABSTRACT FROM AUTHOR]

A generic modeling methodology that analyzes the losses in switched capacitor converters (SCC) operating in open loop was developed and verified by simulation and experiments. The proposed analytical approach is unified, covering both hard- and soft-SCC topologies that include active switches and/or diodes. An important feature of the proposed model is that it expresses the losses as a function of the average currents passing through each flying capacitor during each switching phase. Since these currents are linearly proportional to the output current, the model is also applicable to SCC with multiple capacitors if it can be assumed that each of the subcircuits of the modeled SCC can be described or approximated by a first-order system. The proposed model can be used to assess the effect of the operational conditions of the SCC, such as switching frequency and duty cycle, on the expected losses. As such, the model can help in the optimization of SCC systems and their control to achieve high efficiency and the desired regulations. [ABSTRACT FROM PUBLISHER]

A dynamically rapid method used for tracking the maximum power point of photovoltaic arrays, known as ripple cor- relation control, is presented and verified against experiment. The technique takes advantage of the signal ripple, which is automatically present in power converters. The ripple is interpreted as a perturbation from which a gradient ascent optimization can be realized. The technique converges asymptotically at maximum speed to the maximum power point without the benefit of any array parameters or measurements. The technique has simple circuit implementations. [ABSTRACT FROM AUTHOR]