Showing papers on "Boost converter published in 2012"
TL;DR: A new topology for cascaded multilevel converter based on submultileVEL converter units and full-bridge converters is proposed, optimized for various objectives, such as the minimization of the number of switches, gate driver circuits and capacitors, and blocking voltage on switches.
Abstract: In this paper, a new topology for cascaded multilevel converter based on submultilevel converter units and full-bridge converters is proposed. The proposed topology significantly reduces the number of dc voltage sources, switches, IGBTs, and power diodes as the number of output voltage levels increases. Also, an algorithm to determine dc voltage sources magnitudes is proposed. To synthesize maximum levels at the output voltage, the proposed topology is optimized for various objectives, such as the minimization of the number of switches, gate driver circuits and capacitors, and blocking voltage on switches. The analytical analyses of the power losses of the proposed converter are also presented. The operation and performance of the proposed multilevel converter have been evaluated with the experimental results of a single-phase 125-level prototype converter.
471 citations
TL;DR: In this paper, the design and performance of a 6-kW, full-bridge, bidirectional isolated dc-dc converter using a 20-kHz transformer for a 53.2-V, 2-kWh Li-ion battery energy storage system was described.
Abstract: This paper describes the design and performance of a 6-kW, full-bridge, bidirectional isolated dc-dc converter using a 20-kHz transformer for a 53.2-V, 2-kWh lithium-ion (Li-ion) battery energy storage system. The dc voltage at the high-voltage side is controlled from 305 to 355 V, as the battery voltage at the low-voltage side (LVS) varies from 50 to 59 V. The maximal efficiency of the dc-dc converter is measured to be 96.0% during battery charging, and 96.9% during battery discharging. Moreover, this paper analyzes the effect of unavoidable dc-bias currents on the magnetic-flux saturation of the transformer. Finally, it provides the dc-dc converter loss breakdown with more focus on the LVS converter.
423 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: This paper introduces the methodology and the results of a comprehensive comparison of a direct matrix converter, an indirect MC, and a voltage dc-link back-to-back converter for a 15-kW permanent magnet synchronous motor drive.
Abstract: This paper introduces the methodology and the results of a comprehensive comparison of a direct matrix converter (MC), an indirect MC, and a voltage dc-link back-to-back converter for a 15-kW permanent magnet synchronous motor drive. The comparison involves the investigation of the passive components, including the EMI input filter, the required silicon chip area for a defined maximum admissible thermal loading of the power semiconductors, the total losses and/or achievable efficiency, a prediction of the resulting volume and weight of the passive components, and, finally, a tradeoff study between the efficiency, volume, and weight of the converters. Different performance indicators that ultimately allow a systematic determination of the application area of each converter topology are provided with this comparative evaluation.
342 citations
TL;DR: In this paper, a three-input dc-dc boost converter is proposed for hybridizing alternative energy sources such as photovoltaic (PV) source, fuel cell (FC) source and battery.
Abstract: A new three-input dc-dc boost converter is proposed in this paper. The proposed converter interfaces two unidirectional input power ports and a bidirectional port for a storage element in a unified structure. This converter is interesting for hybridizing alternative energy sources such as photovoltaic (PV) source, fuel cell (FC) source, and battery. Supplying the output load, charging or discharging the battery can be made by the PV and the FC power sources individually or simultaneously. The proposed structure utilizes only four power switches that are independently controlled with four different duty ratios. Utilizing these duty ratios, tracking the maximum power of the PV source, setting the FC power, controlling the battery power, and regulating the output voltage are provided. Depending on utilization state of the battery, three different power operation modes are defined for the converter. In order to design the converter control system, small-signal model is obtained in each operation mode. Due to interactions of converter control loops, decoupling network is used to design separate closed-loop controllers. The validity of the proposed converter and its control performance are verified by simulation and experimental results for different operation conditions.
330 citations
TL;DR: In this paper, a multidevice structure with interleaved control is proposed to reduce the input current ripples, the output voltage ripples and the size of passive components with high efficiency compared with the other topologies.
Abstract: Multiphase converter topologies for use in high-performance applications have received increasing interest in recent years. This paper proposes a novel multidevice interleaved boost converter (MDIBC) that interfaces the fuel cell with the powertrain of hybrid electric vehicles. In this research, a multidevice structure with interleaved control is proposed to reduce the input current ripples, the output voltage ripples, and the size of passive components with high efficiency compared with the other topologies. In addition, low EMI and low stress in the switches are expected. The proposed dc/dc converter is compared to other converter topologies such as conventional boost converter (BC), multidevice boost converter (MDBC), and two-phase interleaved boost converter (IBC) to verify its dynamic performance. Furthermore, a generalized small-signal model is derived for these dc/dc converters, which has not been previously discussed. A digital dual-loop control is designed to achieve the proper regulator for the converters with fast transient response. The dc/dc converter topologies and their controller are designed and investigated by using MATLAB/Simulink. Finally, the proposed converter (MDIBC) is experimentally validated with results obtained from a 30-kW prototype that has been built and tested in our laboratory based on TMS320F2808 DSP. The simulation and experimental results have demonstrated that the proposed converter is more efficient than other dc/dc converter topologies in achieving high performance and reliability for high-power dc/dc converters.
322 citations
TL;DR: A novel high step-up dc-dc converter with coupled-inductor and switched-capacitor techniques is proposed, which can achieve highstep-up voltage gain with appropriate duty ratio and reduce the conduction loss.
Abstract: A novel high step-up dc-dc converter with coupled-inductor and switched-capacitor techniques is proposed in this paper. The capacitors are charged in parallel and are discharged in series by the coupled inductor, stacking on the output capacitor. Thus, the proposed converter can achieve high step-up voltage gain with appropriate duty ratio. Besides, the voltage spike on the main switch can be clamped. Therefore, low on-state resistance RDS(ON) of the main switch can be adopted to reduce the conduction loss. The efficiency can be improved. The operating principle and steady-state analyses are discussed in detail. Finally, a prototype circuit with 24-V input voltage, 400-V output voltage, and 200-W output power is implemented in the laboratory. Experiment results confirm the analysis and advantages of the proposed converter.
291 citations
TL;DR: It is demonstrated that, with a careful design of the converter, the filter capacitances can be made small enough so that film capacitors may be used, and the converter mean time between failures can bemade as high as that of the solid-state lamp.
Abstract: In this paper, an integrated double buck-boost (IDBB) converter is proposed as a high-power-factor offline power supply for power-LED lamps. The IDBB converter features just one controlled switch and two inductors and is able to supply a solid-state lamp from the mains, providing high power factor and good efficiency. In this paper, the IDBB converter is analyzed, and a design methodology is proposed. It is demonstrated that, with a careful design of the converter, the filter capacitances can be made small enough so that film capacitors may be used. In this way, the converter mean time between failures can be made as high as that of the solid-state lamp. A design example for a 70-W converter supplied from a 230 V/50 Hz mains for street lighting applications is shown. Finally, experimental results from a laboratory prototype are also presented.
274 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
TL;DR: The results demonstrate that the phase shifted semi-bridgeless PFC boost converter is ideally suited for automotive level I residential charging applications in North America, where the typical supply is limited to 120 V and 1.44 kVA.
Abstract: As a key component of a plug-in hybrid electric vehicle (PHEV) charger system, the front-end ac-dc converter must achieve high efficiency and power density. This paper presents a topology survey evaluating topologies for use in front end ac-dc converters for PHEV battery chargers. The topology survey is focused on several boost power factor corrected converters, which offer high efficiency, high power factor, high density, and low cost. Experimental results are presented and interpreted for five prototype converters, converting universal ac input voltage to 400 V dc. The results demonstrate that the phase shifted semi-bridgeless PFC boost converter is ideally suited for automotive level I residential charging applications in North America, where the typical supply is limited to 120 V and 1.44 kVA or 1.92 kVA. For automotive level II residential charging applications in North America and Europe the bridgeless interleaved PFC boost converter is an ideal topology candidate for typical supplies of 240 V, with power levels of 3.3 kW, 5 kW, and 6.6 kW.
245 citations
TL;DR: A fully integrated 3-level DC-DC converter, a hybrid of buck and switched-capacitor converters, implemented in 130 nm CMOS technology is presented, which enables smaller inductors than a buck, while generating a wide range of output voltages compared to a 1/2 mode switched-Capacitor converter.
Abstract: On-chip DC-DC converters have the potential to offer fine-grain power management in modern chip-multiprocessors. This paper presents a fully integrated 3-level DC-DC converter, a hybrid of buck and switched-capacitor converters, implemented in 130 nm CMOS technology. The 3-level converter enables smaller inductors (1 nH) than a buck, while generating a wide range of output voltages compared to a 1/2 mode switched-capacitor converter. The test-chip prototype delivers up to 0.85 A load current while generating output voltages from 0.4 to 1.4 V from a 2.4 V input supply. It achieves 77% peak efficiency at power density of 0.1 W/mm2 and 63% efficiency at maximum power density of 0.3 W/mm2. The converter scales output voltage from 0.4 V to 1.4 V (or vice-versa) within 20 ns at a constant 450 mA load current. A shunt regulator reduces peak-to-peak voltage noise from 0.27 V to 0.19 V under pseudo-randomly fluctuating load currents. Using simulations across a wide range of design parameters, the paper compares conversion efficiencies of the 3-level, buck and switched-capacitor converters.
TL;DR: In this article, a design procedure is introduced for using LLC resonant converter as a wide output range voltage source, where the maximum value of the capacitor in parallel with the power MOSFETs drain-sources is derived to realize the zero voltage switching operation in the converter inductive region.
Abstract: LLC resonant converter is one of the most suitable circuit topologies that have been introduced for designing constant output voltage switched-mode power supplies. In this paper, a design procedure is introduced for using this converter as a wide output range voltage source. Unlike constant output voltage applications which need small converter inductance ratio and narrow switching frequency variations, for wide output range applications, large values of these parameters are needed simultaneously and should be optimized. Instead of minimizing the components stresses, leading to a great value of the inductance ratio, proper choice of the converter parameters resulting in a smaller inductance ratio has been done. Maximum value of the capacitor in parallel with the power MOSFETs drain-sources has been derived to realize the zero voltage switching operation in the converter inductive region. Soft switching is achieved for all power devices under all operating conditions. A prototype of the converter has been tested for different regulated output voltages (35-165 Vdc) under different loads (0-3 Adc) and input voltages (320-370 Vdc) for using an ion implanter arc power supply, with maximum efficiency value of 94.7%. Experimental results confirm the high performance of the wide output range LLC resonant converter even under the worst case conditions.
TL;DR: In this article, a ZVZCS full-bridge DC/DC converter is proposed to process and deliver power efficiently over very wide load variations, where the voltage across the output diode bridge is clamped to avoid any adverse voltage overshoots arising during turn-off of the output diodes as commonly found in regular full bridge converters.
Abstract: This paper presents a novel ZVZCS full-bridge DC/DC converter, which is able to process and deliver power efficiently over very wide load variations. The proposed DC/DC converter is part of a plug-in AC/DC converter used to charge the traction battery (high voltage battery) in an electric vehicle. The key challenge in this application is operation of the full-bridge converter from absolutely no-load to full-load conditions. In order to confirm reliable operation of the full-bridge converter under such wide load variations, the converter should not only operate with soft-switching from full load to no-load condition with satisfactory efficiency for the full range of operation, but also the voltage across the output diode bridge needs to be clamped to avoid any adverse voltage overshoots arising during turn-OFF of the output diodes as commonly found in regular full bridge converters. In order to achieve such stringent requirements and high reliability, the converter employs a symmetric passive near lossless auxiliary circuit to provide the reactive current for the full-bridge semiconductor switches, which guarantees zero voltage switching at turn-ON times for all load conditions. Moreover the proposed topology is based on a current driven rectifier in order to clamp the voltage of the output diode bridge and also satisfy ZVZCS operation of the converter resulting in superior efficiency for all load conditions. In this paper operation of the converter is presented in detail followed by analytical design procedure. Experimental results provided from a 3KW prototype validate the feasibility and superior performance of the proposed converter.
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
03 Apr 2012
TL;DR: A transformer-based self-starting boost converter architecture with low-power maximum power point tracking (MPPT) control for low-voltage thermoelectric generator applications and an improved MPPT sensing method is proposed to simplify the circuit.
Abstract: While the demand for micro-energy harvesters (μEHs) is increasing (for seamless energy source in applications such as wireless sensor node), two major problems still obstruct versatile use of them. The first problem is the self-startup capability. Because many wireless sensor nodes are likely to be located where human-maintenance is difficult, starting them up manually can be as difficult as replacing the battery. Its realization has been difficult because μEHs must be able to turn itself on without any stored energy. Some previous works have reported such a function: some needed high voltage [1] or vibration [2] and one used a transformer as a starter [3]. The other problem is the maximum power point tracking (MPPT) capability. Because it is known that MPPT algorithms usually require considerable power consumption [4], using them in μEHs is impractical. This paper suggests a new boost converter architecture and MPPT control method which can bring μEH into practical use.
Patent•
05 Jun 2012TL;DR: In this article, a triac-based dimmer is configured to phase modulate a supply voltage to the dimmer so that an output voltage has a substantially uninterrupted phase delay during each half-cycle of the supply voltage during the dimming period.
Abstract: In at least one embodiment, a controller allows triac-based dimmer to properly function and dim a load whose voltage is regulated by a switching power converter. In at least one embodiment, the switching power converter includes a switch to control voltage conversion of an input voltage to the switching power converter, wherein phase delays are introduced in the input voltage by a triac-based dimmer during a dimming period. In at least one embodiment, the controller is configured to control the switch of the switching power converter to establish an input resistance of the switching power converter during a dimming portion of the input voltage, wherein the input resistance allows the triac-based dimmer to phase modulate a supply voltage to the dimmer so that an output voltage of the dimmer has a substantially uninterrupted phase delay during each half-cycle of the supply voltage during the dimming period.
Patent•
23 Aug 2012TL;DR: In this paper, a wireless power transmission system includes a charging and path controller configured to supply, to a battery module, power generated by a solar cell module, or energy generated by an alternating current-to-direct current (AC/DC) converter, based on a control signal.
Abstract: A wireless power transmission system includes a charging and path controller configured to supply, to a battery module, power generated by a solar cell module, or power generated by an alternating current-to-direct current (AC/DC) converter, based on a control signal; a power converter configured to receive power from the battery module and generate a supply power to be supplied to a target device from power received from the battery module using a resonant frequency; a source resonator configured to receive the supply power from the power converter and transmit the supply power received from the power converter to the target device; and a control/communication unit configured to generate the control signal of the charging and path controller based on an amount of the power generated by the solar cell module and an amount of power that can be output from the battery module.
TL;DR: In this paper, the authors proposed a bidirectional switched-capacitor dc-dc converter for applications that require high voltage gain, which features low component (switching device and capacitor) power rating, small switching device count, and low output capacitance requirement.
Abstract: This paper proposes a bidirectional switched-capacitor dc-dc converter for applications that require high voltage gain. Some of conventional switched-capacitor dc-dc converters have diverse voltage or current stresses for the switching devices in the circuit, not suitable for modular configuration or for high efficiency demand; some suffer from relatively high power loss or large device count for high voltage gain, even if the device voltage stress could be low. By contrast, the proposed dc-dc converter features low component (switching device and capacitor) power rating, small switching device count, and low output capacitance requirement. In addition to its low current stress, the combination of two short symmetric paths of charge pumps further lowers power loss. Therefore, a small and light converter with high voltage gain and high efficiency can be achieved. Simulation and experimental results of a 450-W prototype with a voltage conversion ratio of six validate the principle and features of this topology.
TL;DR: A load adaptive control approach to optimally control the amount of reactive current required to guarantee zero-voltage switching (ZVS) of the converter switches, used as a battery charger for an electric vehicle (EV).
Abstract: This paper presents a load adaptive control approach to optimally control the amount of reactive current required to guarantee zero-voltage switching (ZVS) of the converter switches. The proposed dc/dc converter is used as a battery charger for an electric vehicle (EV). Since this application demands a wide range of load variations, the converter should be able to sustain ZVS from full-load to no-load condition. The converter employs an asymmetric auxiliary circuit to provide the reactive current for the full-bridge semiconductor switches, which guarantees ZVS at turn-on times. The proposed control scheme is able to determine the optimum value of the reactive current injected by the auxiliary circuit in order to minimize extra conduction losses in the power MOSFETs, as well as the losses in the auxiliary circuit. In the proposed approach, the peak value of the reactive current is controlled by controlling the switching frequency to make sure that there is enough current to charge and discharge the snubber capacitors during the deadtime. In addition, some practical issues of this application (battery charger for an EV) are discussed in this paper. Experimental results for a 2-kW dc/dc converter are presented. The results show an improvement in efficiency and better performance of the converter.
TL;DR: An ultra-large voltage conversion ratio converter is proposed by integrating a switched-capacitor circuit with a coupled inductor technology, which has the reason for the high efficiency performance.
Abstract: An ultra-large voltage conversion ratio converter is proposed by integrating a switched-capacitor circuit with a coupled inductor technology. The proposed converter can be seen as an equivalent parallel connection to the load of a basic boost converter and a number of forward converters, each one containing a switched-capacitor circuit. All the stages are activated by the boost switch. A single active switch is required, with no need of extreme duty-ratio values. The leakage energy of the coupled inductor is recycled to the load. The inrush current problem of switched capacitors is restrained by the leakage inductance of the coupled-inductor. The above features are the reason for the high efficiency performance. The operating principles and steady state analyses of continuous, discontinuous and boundary conduction modes are discussed in detail. To verify the performance of the proposed converter, a 200 W/20 V to 400 V prototype was implemented. The maximum measured efficiency is 96.4%. The full load efficiency is 95.1%.
TL;DR: In this paper, a modular interleaved boost converter is proposed by integrating a forward energy-delivering circuit with a voltage-doubler to achieve high step-up ratio and high efficiency for dc-microgrid applications.
Abstract: In this paper, a modular interleaved boost converter is first proposed by integrating a forward energy-delivering circuit with a voltage-doubler to achieve high step-up ratio and high efficiency for dc-microgrid applications. Then, steady-state analyses are made to show the merits of the proposed converter module. For closed-loop control design, the corresponding small-signal model is also derived. It is seen that, for higher power applications, more modules can be paralleled to increase the power rating and the dynamic performance. As an illustration, closed-loop control of a 450-W rating converter consisting of two paralleled modules with 24-V input and 200-V output is implemented for demonstration. Experimental results show that the modular high step-up boost converter can achieve an efficiency of 95.8% approximately.
TL;DR: In this paper, a power factor correction (PFC) topology is proposed by inserting the valley-fill circuit in the single-ended primary inductance converter (SEPIC)-derived converter, which can reduce the voltage stress of the storage capacitor and output diode under the same power factor condition.
Abstract: The high-brightness white-light-emitting diode (LED) has attracted a lot of attention for its high efficacy, simple to drive, environmentally friendly, long lifespan, and compact size. The power supply for LED also requires long life, while maintaining high efficiency, high power factor, and low cost. However, a typical power supply design employs an electrolytic capacitor as the storage capacitor, which is not only bulky, but also with a short lifespan, thus hampering performance improvement of the entire LED lighting system. In this paper, a novel power factor correction (PFC) topology is proposed by inserting the valley-fill circuit in the single-ended primary inductance converter (SEPIC)-derived converter, which can reduce the voltage stress of the storage capacitor and output diode under the same power factor condition. This valley-fill SEPIC-derived topology is, then, proposed for LED lighting applications. By allowing a relatively large voltage ripple in the PFC design and operating in the discontinuous conduction mode (DCM), the proposed PFC topology is able to eliminate the electrolytic capacitor, while maintaining high power factor and high efficiency. Under the electrolytic capacitor-less condition, the proposed PFC circuit can reduce the capacitance of the storage capacitor to half for the same power factor and output voltage ripple as comparing to its original circuit. To further increase the efficiency of LED driver proposal, a twin-bus buck converter is introduced and employed as the second-stage current regulator with the PWM dimming function. The basic operating principle and analysis will be described in detail. A 50-W prototype has been built and tested in the laboratory, and the experimental results under universal input-voltage operation are presented to verify the effectiveness and advantages of the proposal.
TL;DR: In this paper, a three-phase current-fed dual-active-bridge (DAB) bidirectional DC-DC converter is presented, which allows low RMS current and maintains zero voltage switching in the whole operating range by keeping the ratio between primary side and secondary side DC-link voltage constant, leading to high efficient energy conversion over a wide input voltage range.
Abstract: In this paper, a three-phase current-fed dual-active-bridge (DAB) bidirectional DC-DC converter is presented. Compared to the voltage source DAB converter, the proposed converter allows low RMS current and maintains zero voltage switching (ZVS) in the whole operating range by keeping the ratio between primary side and secondary side DC-link voltage constant, leading to high efficient energy conversion over a wide input voltage range. In addition, the ZVS conditions can be maintained using small DC inductors and the input current ripple still remains small because of high DC inductor current ripples being alleviated by three-phase interleaving structure. Furthermore, the proposed topology with Y-Y connected transformers is proven to have better current sharing capability compared with other three-phase topologies with different transformer connections. The operation mode analysis, soft switching conditions, and hardware design guidelines are derived in this paper. A 6-kW hardware prototype with input voltage range of 24~48 V and rated 288 V output voltage is developed and tested in the laboratory. The experimental results verified that the proposed converter could maintain high efficiency over a wide input voltage and power range.
TL;DR: Steady-state analysis of pulse-width modulated (PWM) Z-source dc-DC converter operating in continuous conduction mode (CCM) is presented and an expression for the overall efficiency of the PWM Z- source dc-dc has been derived.
Abstract: Steady-state analysis of pulse-width modulated (PWM) Z-source dc-dc converter operating in continuous conduction mode (CCM) is presented. Voltage and current waveforms, and their corresponding expressions describing the steady-state operation of the PWM Z-source dc-dc converter have been presented. The input-to-output dc voltage transfer functions, both for ideal and non-ideal PWM Z-source dc-dc converter have been derived. The minimum Z-network inductance required to ensure CCM operation is derived. The voltage ripple due to filter capacitor and its ESR, and their individual effects on the the overall output voltage ripple have been derived and analyzed. Expressions for power loss in each of the components of the PWM Z-source dc-dc converter has been determined. Using the expressions derived to determine the power losses, an expression for the overall efficiency of the PWM Z-source dc-dc has been derived. An example PWM Z-source dc-dc converter is considered. A laboratory prototype is built and the theoretical analysis is in good agreement with the experimental results.
TL;DR: In this article, the negative terminal of the solar cell array can be directly connected to the ground in the proposed grid-connected power converter to avoid the transparent conducting oxide corrosion that occurs in some types of thin-film solar cell arrays.
Abstract: This paper proposes a novel transformerless grid-connected power converter with negative grounding for a photovoltaic generation system. The negative terminal of the solar cell array can be directly connected to the ground in the proposed grid-connected power converter to avoid the transparent conducting oxide corrosion that occurs in some types of thin-film solar cell array. The proposed grid-connected power converter consists of a dc-dc power converter and a dc-ac inverter. The salient features of the proposed power converter are that some power electronic switches are simultaneously used in both the dc-dc power converter and dc-ac inverter, and only two power electronic switches operate at high switching frequency at the same time (one is in the dc-dc power converter and the other is in the dc-ac inverter). The leakage current of the photovoltaic generation system is reduced because the negative terminal of the solar cell array is connected directly to the ground. Finally, a prototype was developed to verify the performance of the proposed grid-connected power converter. The experimental results show that the performance of the proposed grid-connected power converter is as expected.
TL;DR: In this paper, a four-level flying-capacitor dc-dc converter is explored that can overcome the drawbacks of the traditional DC-DC converter by dramatically reducing the inductance requirement.
Abstract: This paper presents an alternative to the traditional dc-dc converter interfacing the battery with the inverter dc bus in plug-in hybrid electric vehicle (HEV) traction drives. The boost converter used in commercial HEVs meets with obstacles when it comes to upgrading the power rating and achieving high efficiency while downsizing the converter. A four-level flying-capacitor dc-dc converter is explored that can overcome these drawbacks by dramatically reducing the inductance requirement. A special case of the four-level converter, the 3X dc-dc converter, operates at three discrete output/input voltage ratios, thus further reducing the inductance requirement to a minimal value (almost zero). When further compared to its switched-capacitor dc-dc converter counterparts, the 3X dc-dc converter can be operated at variable output/input voltage ratios without sacrificing efficiency, and it lowers the capacitance requirement by utilizing the parasitic inductance. The operating principle, current ripple analysis, the transient control to limit the inrush current, and power loss analysis are introduced. Experimental results of a 55-kW prototype are provided to demonstrate the principle and analysis of this topology.
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 paper, the authors proposed a hybrid seven-level converter that is based on the upgrade of the five-level active neutral-point-clamped converter concept and is suitable for high-power applications.
Abstract: This paper introduces a novel hybrid seven-level converter that is based on the upgrade of the five-level active neutral-point-clamped converter concept and is suitable for high-power applications. The paper provides a comprehensive analysis for the operation of the converter. Based on the analysis, a space vector modulation (SVM)-based switching strategy that takes advantage of redundant switching vectors of the SVM strategy to counteract the voltage drift phenomenon of the proposed converter is proposed. The limit to the range of operation of the seven-level converter based on the proposed SVM strategy is also presented. It is shown that the ability to stabilize the dc-link capacitor voltages and the per-phase flying capacitors is a function of the converter operating indices, i.e., the load power factor and modulation index. The salient feature of the proposed SVM-based control strategy is that it enables proper operation of the converter with no requirements for additional controls or auxiliary power circuitry, within the specified range of operation. Performance of a converter under various operating conditions, based on the proposed SVM strategy, in the MATLAB/Simulink environment, is evaluated and experimentally demonstrated.
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.
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.