Showing papers on "Inductor published in 2012"
TL;DR: In this article, a dual-path architecture for energy harvesting is employed that has a peak efficiency improvement of 11-13% over the traditional two-stage approach, which is achieved by combining energy from solar, thermal, and vibration sources.
Abstract: A platform architecture combining energy from solar, thermal, and vibration sources is presented. A dual-path architecture for energy harvesting is employed that has a peak efficiency improvement of 11%-13% over the traditional two-stage approach. The system implemented consists of a reconfigurable multi-input, multi-output switch matrix that combines energy from three distinct energy-harvesting sources-photovoltaic, thermoelectric, and piezoelectric. The system can handle input voltages from 20 mV to 5 V and is capable of extracting maximum power from individual harvesters all at the same time utilizing a single inductor. A proposed time-based power monitor is used for achieving maximum power point tracking for the photovoltaic harvester. This has a peak tracking efficiency of 96%. The peak efficiencies achieved with inductor sharing are 83%, 58%, and 79% for photovoltaic boost, thermoelectric boost, and piezoelectric buck-boost converters, respectively. The switch matrix and the control circuits are implemented on a 0.35-μm CMOS process.
446 citations
TL;DR: This work has analyzed the PTE of a pair of capacitively loaded inductors via reflected load theory (RLT) and compared it with a method known as coupled-mode theory (CMT) and proven that both methods basically result in the same set of equations in steady state and either method can be applied for short- or midrange coupling conditions.
Abstract: Inductive coupling is a viable scheme to wirelessly energize devices with a wide range of power requirements from nanowatts in radio frequency identification tags to milliwatts in implantable microelectronic devices, watts in mobile electronics, and kilowatts in electric cars. Several analytical methods for estimating the power transfer efficiency (PTE) across inductive power transmission links have been devised based on circuit and electromagnetic theories by electrical engineers and physicists, respectively. However, a direct side-by-side comparison between these two approaches is lacking. Here, we have analyzed the PTE of a pair of capacitively loaded inductors via reflected load theory (RLT) and compared it with a method known as coupled-mode theory (CMT). We have also derived PTE equations for multiple capacitively loaded inductors based on both RLT and CMT. We have proven that both methods basically result in the same set of equations in steady state and either method can be applied for short- or midrange coupling conditions. We have verified the accuracy of both methods through measurements, and also analyzed the transient response of a pair of capacitively loaded inductors. Our analysis shows that the CMT is only applicable to coils with high quality factor (Q) and large coupling distance. It simplifies the analysis by reducing the order of the differential equations by half compared to the circuit theory.
387 citations
TL;DR: A novel switched-capacitor inverter, which does not need any inductors, can be smaller than a conventional two-stage unit which consists of a boost converter and an inverter bridge and its output harmonics are reduced compared to a conventional voltage source single phase full bridge inverter.
Abstract: A novel switched-capacitor inverter is proposed. The proposed inverter outputs larger voltage than the input voltage by switching the capacitors in series and in parallel. The maximum output voltage is determined by the number of the capacitors. The proposed inverter, which does not need any inductors, can be smaller than a conventional two-stage unit which consists of a boost converter and an inverter bridge. Its output harmonics are reduced compared to a conventional voltage source single phase full bridge inverter. In this paper, the circuit configuration, the theoretical operation, the simulation results with MATLAB/SIMULINK, and the experimental results are shown. The experimental results accorded with the theoretical calculation and the simulation results.
370 citations
TL;DR: The LLCL filter as mentioned in this paper inserts a small inductor in the branch loop of the capacitor in the traditional LCL filter to compose a series resonant circuit at the switching frequency, which attenuates the switching-frequency current ripple components much better than an LCL filtering.
Abstract: This paper presents a new topology of higher order power filter for grid-tied voltage-source inverters, named the LLCL filter, which inserts a small inductor in the branch loop of the capacitor in the traditional LCL filter to compose a series resonant circuit at the switching frequency. Particularly, it can attenuate the switching-frequency current ripple components much better than an LCL filter, leading to a decrease in the total inductance and volume. Furthermore, by decreasing the inductance of a grid-side inductor, it raises the characteristic resonance frequency, which is beneficial to the inverter system control. The parameter design criteria of the proposed LLCL filter is also introduced. The comparative analysis and discussions regarding the traditional LCL filter and the proposed LLCL filter have been presented and evaluated through experiment on a 1.8-kW-single-phase grid-tied inverter prototype.
350 citations
TL;DR: An improved interleaving structure with optimal behaviors is proposed, which constructs the top layer paralleling with the bottom layer and then in series with the other turns of the primary, so that a lower magnetomotive force ratio m can be obtained, as well as minimized ac resistance, leakage inductance, and even stray capacitance.
Abstract: The trend toward high power density, high operating frequency, and low profile in power converters has exposed a number of limitations in the use of conventional wire-wound magnetic component structures. A planar magnetic is a low-profile transformer or inductor utilizing planar windings, instead of the traditional windings made of Cu wires. In this paper, the most important factors for planar transformer (PT) design including winding loss, core loss, leakage inductance, and stray capacitance have individually been investigated. The tradeoffs among these factors have to be analyzed in order to achieve optimal parameters. Combined with an application, four typical winding arrangements have been compared to illustrate their advantages and disadvantages. An improved interleaving structure with optimal behaviors is proposed, which constructs the top layer paralleling with the bottom layer and then in series with the other turns of the primary, so that a lower magnetomotive force ratio m can be obtained, as well as minimized ac resistance, leakage inductance, and even stray capacitance. A 1.2-kW full-bridge dc-dc converter prototype employing the improved PT structure has been constructed, over 96% efficiency is achieved, and a 2.7% improvement, compared with the noninterleaving structure, is obtained.
295 citations
TL;DR: In this article, a steady-state analysis of the bidirectional dual active bridge (DAB) dc-dc converter is presented, which produces equations for RMS and average device currents, and rms and peak inductor/transformer currents.
Abstract: This paper contributes to the steady-state analysis of the bidirectional dual active bridge (DAB) dc-dc converter by proposing a new model that produces equations for rms and average device currents, and rms and peak inductor/transformer currents. These equations are useful in predicting losses that occur in the devices and passive components and aid in the converter design. An analysis of zero-voltage switching (ZVS) boundaries for buck and boost modes while considering the effect of snubber capacitors on the DAB converter is also presented. The proposed model can be used to predict the converter efficiency at any desired operating point. The new model can serve as an important teaching-cum-research tool for DAB hardware design (devices and passive components selection), soft-switching-operating range estimation, and performance prediction at the design stage. The operation of the DAB dc-dc converter has been verified through extensive simulations. A DAB converter prototype was designed on the basis of the proposed model and was built for an aerospace energy storage application. Experimental results are presented to validate the new model for a 7 kW, 390/180 V, 20 kHz converter operation and the ZVS boundary operation.
273 citations
12 Nov 2012
TL;DR: In this article, the authors proposed a close-loop method for suppression of the inner current in MMC, which can be applied to single-phase or three-phase MMCs.
Abstract: Ideally, the inner (the upper or lower arm) current of a modular multilevel converter (MMC) is assumed to be the sum of a dc component and an ac component of the fundamental frequency. However, this current is usually distorted and the peak/RMS value of it is increased compared with the theoretical result. This is because ac current flows through the submodule (SM) capacitors and the capacitor voltages fluctuate with time. The increased currents will increase power losses and may threaten the safe operation of the power devices and capacitors. This paper proposes a novel close-loop method for suppression of the inner current in MMC. This method is very simple and is implemented in stationary frame, and no harmonic extraction algorithm is needed. Hence, it can be applied to single-phase or three-phase MMC. What is more important, this method does not influence the balancing of the SM capacitor voltages. Simulation and experimental results show that the proposed method can suppress the peak and RMS values of the inner currents dramatically. Meanwhile, the harmonic contents in the output current can also be suppressed satisfactorily even when the SM capacitor voltage ripple factor is as large as about ±19%. Therefore, the proposed method can also be adopted to reduce the SM capacitance requirement.
254 citations
TL;DR: A novel bidirectional dc-dc converter that employs a coupled inductor with same winding turns in the primary and secondary sides has higher step-up and step-down voltage gains than the conventional bidirectionals dc-DC boost/buck converter.
Abstract: A novel bidirectional dc-dc converter is presented in this paper The circuit configuration of the proposed converter is very simple The proposed converter employs a coupled inductor with same winding turns in the primary and secondary sides In step-up mode, the primary and secondary windings of the coupled inductor are operated in parallel charge and series discharge to achieve high step-up voltage gain In step-down mode, the primary and secondary windings of the coupled inductor are operated in series charge and parallel discharge to achieve high step-down voltage gain Thus, the proposed converter has higher step-up and step-down voltage gains than the conventional bidirectional dc-dc boost/buck converter Under same electric specifications for the proposed converter and the conventional bidirectional boost/buck converter, the average value of the switch current in the proposed converter is less than the conventional bidirectional boost/buck converter The operating principle and steady-state analysis are discussed in detail Finally, a 14/42-V prototype circuit is implemented to verify the performance for the automobile dual-battery system
225 citations
TL;DR: In this article, a single-phase grid-connected transformerless photovoltaic inverter for residential application is presented, which is derived from a boost cascaded with a buck converter along with a line frequency unfolding circuit.
Abstract: In this paper, a single-phase grid-connected transformerless photovoltaic inverter for residential application is presented. The inverter is derived from a boost cascaded with a buck converter along with a line frequency unfolding circuit. Due to its novel operating modes, high efficiency can be achieved because there is only one switch operating at high frequency at a time, and the converter allows the use of power MOSFET and ultrafast reverse recovery diode. It also features a robust structure because the phase leg does not have a shoot-through issue. This paper begins with theoretical analysis and modeling of this boost-buck converter-based inverter. And the model indicates that small boost inductance will lead to an increase in the resonant pole frequency and a decrease in the peak of Q, which results in easier control and greater stability. Thus, interleaved multiple phases structure is proposed to have small equivalent inductance; meanwhile, the ripple can be decreased, and the inductor size can be reduced as well. A two-phase interleaved inverter is then designed accordingly. Finally, the simulation and experiment results are shown to verify the concept and the tested efficiency under 1-kW power condition is up to 98.5%.
205 citations
TL;DR: In this paper, the authors present a systematic analysis and comparison of all the principal types of power extraction circuit that allow this damping force to be increased, under both ideal and realistic constraints.
Abstract: When a piezoelectric energy harvester is connected to a simple load circuit, the damping force which the piezoelectric element is able to generate is often below the optimal value to maximize electrical power generation Circuits that aim to increase the power output of a piezoelectric energy harvester do so by modifying the voltage onto which the piezoelectric current source drives its charge This paper presents a systematic analysis and comparison of all the principal types of power extraction circuit that allow this damping force to be increased, under both ideal and realistic constraints Particular emphasis is placed on low-amplitude operation A circuit called single-supply prebiasing is shown to harvest more power than previous approaches Most of the analyzed circuits able to increase the power output do so by synchronously inverting or charging the piezoelectric capacitance through an inductor For inductor Q factors greater than around only 2, the single-supply prebiasing circuit has the highest power density of the analyzed circuits The absence of diodes in conduction paths, achievable with a minimum number of synchronous rectifiers, means that the input excitation amplitude is not required to overcome a minimum value before power can be extracted, making it particularly suitable for microscale applications or those with a wide variation in amplitude
203 citations
TL;DR: In this article, a single-stage flyback power factor correction (PFC) circuit with a variable boost inductance was proposed for high-brightness LED applications for the universal input voltage (90-270 Vrms).
Abstract: This paper presents a single-stage flyback power-factor-correction (PFC) circuit with a variable boost inductance for high-brightness LED applications for the universal input voltage (90-270 Vrms). The proposed circuit overcomes the limitations of the conventional single-stage PFC flyback with a constant boost inductance that cannot be designed to achieve a practical maximum bulk-capacitor voltage level (i.e., less than 450 V) at high line while meeting required line-current harmonic specifications at low line. According to the proposed method for achieving variable boost inductance, the boost inductance has a constant high value at high line, while at low line it is reduced proportionally to the load current, so that the IEC 61000-3-2 class C and corresponding Japanese JIS C 61000-3-2 class C line-current harmonic limits are satisfied. The proposed single-stage PFC flyback LED driver with the variable boost inductor is experimentally verified on a 24-V/91-W prototype circuit.
TL;DR: A wide range zero-voltage switching (ZVS) active-clamped L-L type current-fed isolated dc-dc converter is proposed for fuel cells to utility interface application and maintains ZVS of all switches from full load down to very light load condition for wide input voltage variation.
Abstract: A wide range zero-voltage switching (ZVS) active-clamped L-L type current-fed isolated dc-dc converter is proposed for fuel cells to utility interface application. The proposed converter maintains ZVS of all switches from full load down to very light load condition for wide input voltage variation. Detailed operation, analysis, design, simulation and experimental results for the proposed converter are presented. The auxiliary active clamping circuit absorbs the turn-off voltage spike and also assists in achieving ZVS of main switches. The ZVS of auxiliary switches and main switches is achieved by the energy stored in the boost inductors and series inductor (aided by parallel inductor), respectively. Rectifier diodes operate with zero-current switching. An experimental converter rated at 200 W has been designed, built and tested in the laboratory to verify the analysis, design and performance of the proposed converter for wide variations in input voltage and load.
TL;DR: In this article, an inductor current ripple-based modeling approach has been proposed to accurately model and analyze the converter and the control, cross-coupling, and cross-regulation transfer functions, generated through the model, accurately represent the performance of the converter.
Abstract: Portable applications require multiple supplies with different output levels and some applications also require negative outputs. Single-inductor multiple-output (SIMO) switchers are a good for existing parallel output configurations. This study presents an SIMO dc-dc converter capable of generating buck, boost, and inverted outputs simultaneously. The operation of this class of converter being driven by the ripple in the inductor current the conventional averaging method does not work well. An inductor current ripple-based modeling approach has been proposed to accurately model and analyze the converter. The control, cross-coupling, and cross-regulation transfer functions, generated through the model, accurately represent the performance of the converter. The proof of concept has been carried out with discrete components on an in-house built PCB and the experimental results validating the steady state and ac responses of the converter are presented.
Patent•
23 Mar 2012
TL;DR: In this article, a wireless power receiving system for a mobile electronic device that includes a high-Q repeater resonator comprising at least an inductor and a capacitor and having a Q-factor Q1.
Abstract: A wireless power receiving system for a mobile electronic device that includes a high-Q repeater resonator comprising at least an inductor and a capacitor and having a Q-factor Q1. The inductor of the repeater resonator is enclosed in a removable sleeve of the mobile electronic. The system also includes a high-Q device resonator comprising at least an inductor and a capacitor and having a Q-factor Q2. The device resonator is integrated in the mobile device and electrically connected to the mobile electronic device, and the square root of the product Q1 and Q2 is greater than 100.
TL;DR: In this paper, a single-phase improved active clamp coupled-inductor-based converter with extended voltage doubler cell is proposed for large-voltage conversion ratio applications, where the secondary winding of the coupled inductor is inserted into the half-wave VDC to extend the voltage gain dramatically and decrease the switch voltage stress effectively.
Abstract: In this paper, A single-phase improved active clamp coupled-inductor-based converter with extended voltage doubler cell is proposed for large-voltage conversion ratio applications. The secondary winding of the coupled inductor is inserted into the half-wave voltage doubler cell to extend the voltage gain dramatically and decrease the switch voltage stress effectively. By combining the coupled inductor and voltage doubler cell structure, the disadvantage of the potential resonance between the leakage inductance and the diode stray capacitor is cancelled, and the unexpected high pulsed current in the voltage doubler cell is decreased due to the inherent leakage inductance of the coupled inductor. Meanwhile, the active clamp scheme is employed to recycle the leakage energy, suppress the switch turn-off voltage spikes, and implement zero-voltage-switching turn-on operation. In addition, there is only one magnetic component in the proposed converter and the coupled inductor operates not only as a filter inductor, but also as a transformer when the main switch is in the ON state, which reduces the volume of the magnetic core and improves the power density of the converter. A 500 W prototype operating at 100 kHz with 48 V input and 380 V output is built to verify the analysis. The maximum efficiency of the prototype is nearly 97% and the efficiency is higher than 96% over a wide load range.
TL;DR: In this article, a floating active switch is employed to isolate energy from the PV panel when the ac module is off; this particular design protects installers and users from electrical hazards.
Abstract: Within the photovoltaic (PV) power-generation market, the ac PV module has shown obvious growth. However, a high voltage gain converter is essential for the module's grid connection through a dc-ac inverter. This paper proposes a converter that employs a floating active switch to isolate energy from the PV panel when the ac module is off; this particular design protects installers and users from electrical hazards. Without extreme duty ratios and the numerous turns-ratios of a coupled inductor, this converter achieves a high step-up voltage-conversion ratio; the leakage inductor energy of the coupled inductor is efficiently recycled to the load. These features explain the module's high-efficiency performance. The detailed operating principles and steady-state analyses of continuous, discontinuous, and boundary conduction modes are described. A 15 V input voltage, 200 V output voltage, and 100 W output power prototype circuit of the proposed converter has been implemented; its maximum efficiency is up to 95.3% and full-load efficiency is 92.3%.
TL;DR: A novel, yet simple zero-voltage switching (ZVS) interleaved boost power factor correction (PFC) ac/dc converter used to charge the traction battery of an electric vehicle from the utility mains shows a considerable increase in efficiency and superior performance compared to the conventional hard-switched interleaves boost PFC converter.
Abstract: This paper presents a novel, yet simple zero-voltage switching (ZVS) interleaved boost power factor correction (PFC) ac/dc converter used to charge the traction battery of an electric vehicle from the utility mains. The proposed opology consists of a passive auxiliary circuit, placed between two phases of the interleaved front-end boost PFC converter, which provides enough current to charge and discharge the MOSFETs' output capacitors during turn-ON times. Therefore, the MOSFETs are turned ON at zero voltage. The proposed converter maintains ZVS for the universal input voltage (85 to 265 Vrms), which includes a very wide range of duty ratios (0.07-1). In addition, the control system optimizes the amount of reactive current required to guarantee ZVS during the line cycle for different load conditions. This optimization is crucial in this application since the converter may work at very light loads for a long period of time. Experimental results from a 3 kW ac/dc converter are presented in the paper to evaluate the performance of the proposed converter. The results show a considerable increase in efficiency and superior performance of the proposed converter compared to the conventional hard-switched interleaved boost PFC converter.
TL;DR: In this paper, a superconducting fault-current limiter-magnetic energy storage system is presented to solve weak lowvoltage ride-through capability and fluctuating output power in doubly fed induction generators.
Abstract: Two major problems that are faced by doubly fed induction generators are: weak low-voltage ride-through capability and fluctuating output power. To solve these problems, a superconducting fault-current limiter-magnetic energy storage system is presented. The superconducting coil (SC) is utilized as the energy storage device for output power smoothing control during normal operation and as a fault-current limiting inductor to limit the surge current in the stator or rotor during the grid fault. The SC can also weaken the rotor back electromotive force voltage, and thus enhance the controllability of the rotor-side converter (RSC), which helps to protect both the RSC and the gearbox. Simulation results verify the efficacy of the proposed approaches.
TL;DR: In this paper, two topologies are presented for switched-inductor quasi-Z-source inverters, namely a ripple input current switched-independant quasi-source (rSL-qZSI) and a continuous input current SWZSI (cSL-QZSI).
Abstract: In this study, two topologies are presented for switched-inductor quasi-Z-source inverters, namely a ripple input current switched-inductor quasi-Z-source inverter (rSL-qZSI) and a continuous input current switched-inductor quasi-Z-source inverter (cSL-qZSI). The proposed inverters possess high boost voltage inversion ability and a lower voltage stress across the active switching devices. Compared with a conventional switched-inductor ZSI, the proposed SL-qZSIs for the same input and output voltage provide a continuous input current and a reduced voltage stress on the capacitors. Moreover, the proposed inverters can overcome the startup inrush current problem but a conventional SL-qZSI cannot overcome this. This study presents the operating principles and analysis, and compares them with the conventional ZSIs. In order, to verify the performance of the proposed converters, a 60 W scaled-down laboratory prototype was constructed and, to test both the configurations it employed a 36 V dc input and an ac output line-to-line voltage of 83 V rms . The peak-to-peak input current ripple of the rSL-qZSI and cSL-ZSI is 126.3 and 59.8%, respectively. The experiment results verified that the proposed inverters have high step-up inversion ability, lower voltage stress on the capacitors and lower input current ripple.
TL;DR: In this article, the feasibility of inkjet-printed passive components such as resistor, capacitor, and inductor were demonstrated on a polyimide (PI) substrate with various functional inks.
TL;DR: In this article, a measurement method is proposed that provides a direct measurement of an inductor quality factor QL as a function of inductor current at RF frequencies, and enables indirect calculation of core loss as the function of flux density.
Abstract: This paper investigates the loss characteristics of RF magnetic materials for power conversion applications in the 10 to 100 MHz range. A measurement method is proposed that provides a direct measurement of an inductor quality factor QL as a function of inductor current at RF frequencies, and enables indirect calculation of core loss as a function of flux density. Possible sources of error in measurement and calculation are evaluated and addressed. The proposed method is used to identify loss characteristics of several commercial RF magnetic-core materials. The loss characteristics of these materials, which have not previously been available, are illustrated and compared in tables and figures. The use of the method and data is demonstrated in the design of a magnetic-core inductor, which is applied in a 30-MHz inverter. The results of this paper are thus useful for the design of magnetic components for very high frequency applications.
TL;DR: This paper presents a fully autonomous, adaptive pulsed synchronous charge extractor (PSCE) circuit optimized for piezoelectric harvesters (PEHs) which have a wide output voltage range 1.3-20 V.
Abstract: This paper presents a fully autonomous, adaptive pulsed synchronous charge extractor (PSCE) circuit optimized for piezoelectric harvesters (PEHs) which have a wide output voltage range 1.3-20 V. The PSCE chip fabricated in a 0.35 μm CMOS process is supplied exclusively by the buffer capacitor where the harvested energy is stored in. Due to the low power consumption, the chip can handle a minimum PEH output power of 5.7 μW. The system performs a startup from an uncharged buffer capacitor and operates in the adaptive mode at storage buffer voltages from 1.4 V to 5 V. By reducing the series resistance losses, the implementation of an improved switching technique increases the extracted power by up to 20% compared to the formerly presented Synchronous Electric Charge Extraction (SECE) technique and enables the chip efficiency to reach values of up to 85%. Compared to a low-voltage-drop passive full-wave rectifier, the PSCE chip increases the extracted power to 123% when the PEH is driven at resonance and to 206% at off-resonance.
TL;DR: A new 16-phase interleaved bidirectional dc/dc converter is developed featuring smaller input/output filters, faster dynamic response and lower device stress than conventional designs, for hybrid vehicle applications.
Abstract: A new 16-phase interleaved bidirectional dc/dc converter is developed featuring smaller input/output filters, faster dynamic response and lower device stress than conventional designs, for hybrid vehicle applications. The converter is connected between the ultracapacitor (UC) pack and the battery pack in a multisource energy storage system of a hybrid vehicle. Typically, multiphase interleaved converters require a current control loop in each phase to avoid imbalanced current between phases. This increases system cost and control complexity. In this paper, in order to minimize imbalance currents and remove the current control loop in each phase, the converter is designed to operate in discontinuous conduction mode (DCM). The high current ripple associated with DCM operation is then alleviated by interleaving. The design, construction, and testing of an experimental hardware prototype is presented, with the test results included. Finally, a novel soft switch topology for DCM operation is proposed for future research, to achieve zero-voltage switching (ZVS), or zero-current switching (ZCS) in all transitions.
TL;DR: An electrostatically tunable magnetoelectric inductor with a tunable inductance range of >5:1 while consuming less than 0.5 mJ of power in the process of tuning was presented in this paper.
Abstract: An electrostatically tunable magnetoelectric inductor including: a substrate; a piezoelectric layer; and a magnetoelectric structure comprising a first electrically conductive layer, a magnetic film layer, a second electrically conductive layer, and recesses formed so as to create at least one electrically conductive coil around the magnetic film layer; with a portion of the substrate removed so as to enhance deformation of the piezoelectric layer. Also disclosed is a method of making the same. This inductor displays a tunable inductance range of >5:1 while consuming less than 0.5 mJ of power in the process of tuning, does not require continual current to maintain tuning, and does not require complex mechanical components such as actuators or switches.
TL;DR: To ensure that the bus capacitor voltage can be kept in a tolerable region, the characteristics of a PFC converter and an LLC tank are investigated, and then, a design procedure is proposed correspondingly.
Abstract: Analysis and design of a single-stage LLC resonant converter are proposed. A single-stage converter uses only one control signal to drive two power converters, a power factor corrector (PFC) converter and a dc/dc converter, for reducing the cost of the system. However, this simplicity induces power imbalance between two converters, and then, the bus voltage between two converters drifts and becomes unpredictable. To ensure that the bus capacitor voltage can be kept in a tolerable region, the characteristics of a PFC converter and an LLC tank are investigated, and then, a design procedure is proposed correspondingly. Finally, a single-stage LLC resonant converter is implemented to verify the analysis.
09 Mar 2012
TL;DR: In this article, an integrated 3D point of load (POL) converter operating at a switching frequency of 2MHz for a 12V to 1.2V buck converter with a full load current of 20A.
Abstract: The introduction of Gallium Nitride (GaN) based power devices offers the potential to achieve higher efficiency and higher switching frequencies than possible with Silicon MOSFET's. This paper will discuss the GaN device characteristics, packaging impact on performance, gate driving methods, and the integration possibilities using GaN technology. The final demonstration being an integrated 3D point of load (POL) converter operating at a switching frequency of 2MHz for a 12V to 1.2V buck converter with a full load current of 20A. This 3D converter employs a low profile low temperature co-fired ceramic (LTCC) inductor and can achieve a full load efficiency of 83% and a power density of 750W/in3 which doubles the power density of current integrated POL converters on the market today.
TL;DR: In this paper, the inverse Watkins-Johnson (IWJ) topology is proposed to achieve robust electromagnetic interference noise immunity, which is achieved by allowing shoot through of the inverter leg switches.
Abstract: A Z-source inverter (ZSI) uses an L-C impedance network between the source and the voltage source inverter (VSI). It has the property of stepping down or stepping up the input voltage, as a result, the output can be either higher or lower than the input voltage as per requirement. This topology also possesses robust electromagnetic interference noise immunity, which is achieved by allowing shoot through of the inverter leg switches. This letter proposes an inverter circuit based on the inverse Watkins-Johnson (IWJ) topology that can achieve similar advantages as that of a ZSI. The proposed circuit requires two switches and one pair of an LC filter apart from the VSI. The systematic development of this inverter topology is described starting from the basic IWJ circuit. Steady-state analysis and implementation of the proposed topology are also described. The pulse width modulation control strategy of the inverter is explained. An experimental prototype is used to validate the proposed circuit.
TL;DR: In this paper, the analysis and design of a three-level LLC series resonant converter (TL LLC SRC) for high and wide-input-voltage applications is presented.
Abstract: In this paper, the analysis and design of a three-level LLC series resonant converter (TL LLC SRC) for high- and wide-input-voltage applications is presented. The TL LLC SRC discussed in this paper consists of two half-bridge LLC SRCs in series, sharing a resonant inductor and a transformer. Its main advantages are that the voltage across each switch is clamped at half of the input voltage and that voltage balance is achieved. Thus, it is suitable for high-input-voltage applications. Moreover, due to its simple driving signals, the additional circulating current of the conventional TL LLC SRCs does not appear in the converter, and a simpler driving circuitry is allowed to be designed. With this converter, the operation principles, the gain of the LLC resonant tank, and the zero-voltage-switching condition under wide input voltage variation are analyzed. Both the current and voltage stresses over different design factors of the resonant tank are discussed as well. Based on the results of these analyses, a design example is provided and its validity is confirmed by an experiment involving a prototype converter with an input of 400-600 V and an output of 48 V/20 A. In addition, a family of TL LLC SRCs with double-resonant tanks for high-input-voltage applications is introduced. While this paper deals with a TL LLC SRC, the analysis results can be applied to other TL LLC SRCs for wide-input-voltage applications.
TL;DR: This paper presents a capacitor-isolated light-emitting diode (LED) driver with inherent current-balancing capability based on a series resonant converter that can be used both for safety isolation and the current balancing with the proposed two-output rectifier structure.
Abstract: This paper presents a capacitor-isolated light-emitting diode (LED) driver with inherent current-balancing capability. Based on a series resonant converter, the resonant capacitor can be used both for safety isolation and the current balancing with the proposed two-output rectifier structure. Compared to the conventional current-sharing technique, the proposed LED driver circuit is simple and has low cost and high performance. Also, the capacitor-isolated structure is more efficient and compact compared to the conventional transformer isolation. The detailed theoretical analysis and design considerations of the proposed circuit are presented. The performance of the proposed circuit is validated by the experimental results from a 60-W prototype with two balanced outputs.
TL;DR: Since the voltage clamping, synchronous rectification and soft-switching techniques are utilised in the proposed circuit topology and the corresponding device specifications are adequately fulfilled, the proposed converter can provide highly efficient bidirectional power conversion in a wide range on the low-voltage side.
Abstract: This study presents a novel soft-switching bidirectional dc-dc converter with a coupled inductor. Transformer-based circuit topologies are commonly employed in conventional bidirectional converters and soft-switching techniques, including zero-voltage switching (ZVS) or zero-current switching (ZCS), are frequently applied to mitigate switching losses. Unfortunately, the use of more than four switches and several diodes in these transformer-based schemes increase production costs and reduce conversion efficiency. This work presents a coupled-inductor bidirectional converter scheme that utilises four power switches to achieve the goal of bidirectional current control. The high step-up and step-down ratios enable a battery module current with a low-voltage level to be injected into a high-voltage dc bus for subsequent utilisation. Experimental results based on a 24 V/200 V 800 W prototype are provided to verify the effectiveness of the proposed bidirectional converter. Since the voltage clamping, synchronous rectification and soft-switching techniques are utilised in the proposed circuit topology and the corresponding device specifications are adequately fulfilled, the proposed converter can provide highly efficient bidirectional power conversion in a wide range on the low-voltage side.