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A high step-up dc–dc converter is proposed in this paper. The presented converter benefits from some advantages such as high voltage gain and continuous input current, which makes it suitable for the renewable energy applications. The presented converter is based on the SEPIC converter. However, the converter voltage gain is improved by employing a coupled inductor and two voltage multipliers. A passive clamp circuit is also added to the proposed converter that increases the voltage gain and reduces the voltage stress on the main switch. Thus, a switch with low $R_{{\text{DS(on)}}}$ will be needed that decreases the conduction loss. Besides, the voltage stress on the output diode in the proposed converter is reduced, which alleviates reverse recovery problem. The steady-state analysis of the proposed converter is discussed in this paper. The analysis is verified with experimental results under the output power of 245 W. [ABSTRACT FROM AUTHOR]

This paper presents the design and construction of a sample of Marx pulsed generator based on boost converter (BC) pulse-forming networks (BCPFNs). BCPFN is used instead of the conventional Marx floors for constructing this pulsed generator. BCPFN is carried out by connecting inductors and capacitors in series and parallel modes, respectively, by using solid-state switches, and during this procedure the pulsed generator converts to BC temporarily and increases the voltage of capacitors uniformly to a considerable value. This technique causes an increase in the discharging voltage level to the load that is many times more than its dc voltage source by charging the capacitors to a greater level. In order to take advantage of the benefits of Marx generator and PFN, this paper suggests a new circuit with the minimum number of switches. It means, to compose BCPFN and Marx, we have tried to design the circuit with fewer switches and instead of it we have achieved our desired performance with changing the operating mode in the states of BC, PFN, BCPFN, and BCPFN Marx. The results are simulated with MATLAB software. At the end, the experimental results of the construction of the above-mentioned system at low-power levels are presented, and the topology’s accuracy is proved by comparing them to the results of simulation. [ABSTRACT FROM AUTHOR]

In this paper, a new structure of nonisolated boost dc–dc converters based on voltage-lift technique is proposed. In comparison with conventional nonisolated boost dc–dc converters, the proposed converter generates higher voltage gain. In this paper, the relations between voltage and current of all elements in continuous conduction mode and discontinuous conduction mode are calculated as well as voltage gain in each mode. Then, the critical inductance and stress of switch current are extracted. Finally, the validity of given theories is examined by using the experimental results. [ABSTRACT FROM PUBLISHER]

In this paper, two structures are proposed for the switched-inductor quasi-Z-source inverter. In the proposed structures to extend the voltage gain of inverter, two new switched-inductor structures are used. In the proposed structures, voltage across the capacitors in the Z-source network and in the switched-inductor is symmetric and small. The other advantage of proposed inverters is known as achieving higher voltage gain per smaller duty cycle ratio (of shoot-through). Compared with a conventional continuous input current switched-inductor quasi-Z-source inverter at the same gain voltage, there is less of a ripple of input current in the proposed inverters. In this paper, at first the both the conventional and the proposed switched-inductor Z-source inventers are thoroughly investigated to find out their governing relations. Then, the proposed Z-source inverters are compared with the conventional ones by simulating them to assess their performance efficiency. Next, applying the simple boost pulse width modulation the simulation is carried out with PSCAD/EMTDC software. After that, to evaluate the obtained results, the prototypes of the proposed inverters with 48 Vdc input voltage are used. [ABSTRACT FROM PUBLISHER]

This paper proposes a wide-range zero-voltage-switching (ZVS) active-clamped current-fed push–pull converter for fuel cell application. The presented converter achieves ZVS for all of the primary switches and ZCS for secondary diodes from rated load to 10% full load over the wide input voltage variation, improving the overall efficiency. The ZVS of switches is realized by the energy stored in the transformer leakage inductance aided by the secondary parallel inductor. An additional active clamping circuit suppresses the voltage spike as well as assists in realizing ZVS of switches. Low-voltage-rated switches with low on-state resistance can be used. Moreover, the voltage-doubler rectifier is adopted to release the reverse-recovery problem of rectifier diodes and reduce turns ratio of the high-frequency transformer. Detailed steady-state operation, analysis, design, control, comparative study, and experimental results are discussed in depth in this paper. Finally, a 200-W prototype has been built in the laboratory to verify the effectiveness of the proposed converter. [ABSTRACT FROM PUBLISHER]

This paper proposes two coupled-inductors-based Z-source networks, called the modified series and tapped switched-coupled-inductors quasi-Z-source networks (mSSCL-qZSN and mTSCL-qZSN, respectively). These networks offer high voltage gains with less-than-unity winding turn ratios $(n < {\text{1)}}$ , resulting in a reduced inductive element size. Other advantages include a less number of active components and their lower ratings and a higher efficiency. In addition, a lower magnetic core size is required for the proposed ZSNs due to the lower peak magnetizing current. The performance principles and detailed comparative analysis are provided and confirmed through experiments on a 200-W dc–dc converter. [ABSTRACT FROM AUTHOR]

This paper presents an architecture for differential Colpitts voltage-controlled oscillators (VCOs) in complementary metal–oxide–semiconductor (CMOS) that utilizes three design techniques to extend the tuning range (TR) of the VCO, while maintaining a low phase noise (PN) and a low power consumption. First, a switched-capacitor bank based on a variable capacitive feedback technique is introduced to achieve a wide TR with a minimal PN degradation. Second, a $G_{m}$ -boosting technique using interstage inductors is employed to lower the power consumption and relax VCO startup issues. Third, a dynamic forward-body self-biased technique is used to further reduce the power consumption and PN of the proposed structure. As a proof of concept, a 26.3-GHz differential Colpitts VCO is designed and fabricated in a 65-nm CMOS process. Based on the measurement results, the VCO achieves a PN of −122.1 dBc/Hz at 10-MHz offset from the center frequency, and a TR of 20%. The circuit consumes 2.3 mW from a 1-V supply and excluding the pads occupies a 0.22 mm2 of silicon area. Compared to the recently published CMOS VCOs within the same frequency range, the proposed VCO simultaneously achieves a wide TR, low power dissipation, and low PN, resulting in a figure of merit (FOM) and FOM incorporating the TR (FOM $_{T}$) of −187 and −193 dBc/Hz at 10-MHz offset from the center frequency, respectively. [ABSTRACT FROM AUTHOR]

In this paper, a high-voltage unipolar pulse power generator is introduced for electroporation applications. Operating principle of the proposed structure is based on the buck–boost (BB) converter. The generator is comprised of parallel modules connected to the converter through an SCR and is supplied by a low-voltage dc source. Each module consists of an insulated gate bipolar transistor (IGBT), two diodes, and a capacitor. In fact, the proposed topology is a combination of the Marx generator and BB (MG-BB) converter. In comparison with other modular MG-BB structures, the proposed topology achieves interesting advantages including simpler structure, reduction of IGBTs voltage rating, and reducing number of components (inductors and switches). In order to clarify the features of the proposed structure, it has been compared with other unipolar MGs considering different aspects including the number of circuit components, number of required input supplies, amplitude of the output pulse, and the maximum voltage across switches and diodes. To validate the effectiveness of the structure, simulation and experimental results are presented. The results confirm that the proposed topology is capable of generating unipolar pulses with desirable amplitude and repetition frequency using a low-voltage dc supply. [ABSTRACT FROM AUTHOR]

The three-phase four-wire inverter with split dc-link capacitors can supply unbalanced loads. For the purpose of reducing the filter inductors, a neutral inductor could be introduced into the neutral line. This paper analyzes the operation principle of the three-phase four-wire inverter with split dc-link capacitors when a neutral inductor is introduced. It is illustrated that the neutral inductor can reduce the zero-sequence switching harmonics in the voltages between the phase-leg midpoints and the output neutral point, thus the filter inductors can be reduced. The optimized design of the neutral inductor and filter inductors is proposed with the considerations of the inductor current ripple, the ability of supplying unbalanced loads, and the total energy stored in the inductors. The equivalent circuits of the three-phase four-wire inverter with split dc-link capacitors and neutral inductor is derived in the α–β–0 frame, and the zero-axis voltage regulator is modified to suppress the third-order harmonic in the zero-sequence current caused by the deadtime of the drive signals for the power switches. Finally, the experimental results from a 9-kW prototype are provided to prove the effectiveness of the proposed optimized design of the neutral inductor and filter inductors and the control strategy of the inverter. [ABSTRACT FROM AUTHOR]

In this paper, a new nonisolated high step-up dc–dc converter is proposed. Active–passive inductor cells (APICs) are used to extend the topology. The ability to achieve high gains is the main merit of the proposed topology. The proposed converter operates based on parallel charging and series discharging of the inductors. The converter also achieves high step-up voltage gain with appropriate duty cycle and low voltage and current stress on the power switches and diodes. The proposed converter is analyzed in operation modes. The main parameters of the converter such as voltage gain, voltage stress of semiconductor devices are calculated to compare with other structures. Considering the output voltage ripple and filter size, the proposed converter is designed. Moreover, the losses and efficiency of the converter are calculated. The performance of the proposed converter is validated by experimental results. [ABSTRACT FROM AUTHOR]

This paper presents a novel dc–dc converter configuration, which successfully integrates two technologies, including a switched capacitor and a switched coupled inductor, into one converter. By adopting a coupled inductor to charge a switched capacitor, the voltage gain can be effectively increased, and the turns ratio of the coupled inductor can be also reduced. Not only lower conduction losses but also higher power conversion efficiency is benefited from a lower part count and lower turns ratios. The proposed converter is simply composed of six components, which can be further derived to varied converters for different purposes, such as a bidirectional converter. The operating principle and steady-state analysis are discussed in this paper. A 250-W laboratory hardware prototype is completed and verified. The voltage gain is up to 11. The highest efficiency is 97.2%, and the full-load efficiency is kept at 93.6%. [ABSTRACT FROM AUTHOR]

This paper extends the trans-Z-source concept to ac–ac power conversion and proposes a novel single-phase trans-Z-source ac–ac converter. The proposed converter retains the advantages of its existing Z-source/quasi-Z-source counterparts in which the output voltage can be boosted and in-phase with the input voltage or bucked/boosted and out-of-phase with the input voltage. Meanwhile, a coupled inductor is introduced into the proposed converter, and the turns ratio of the coupled inductor become another control variable beside the duty cycle to obtain extreme voltage gain. Importantly, the input voltage and output voltage share the same ground, and the input current could be continuous, which is a benefit for reducing input current harmonics. Most important of all, the safe-commutation strategy for the proposed converter is deep developed, and analytic expression between the switches state and loop circuit voltage/current condition is derived out. Hence, the current/voltage ripple can be avoided without a loss snubber circuit, which benefits a reduced cost and enhanced reliability. The performance analysis is discussed in consideration of parasitic resistance, and system parameter design is optimized based on theoretic calculation. A laboratory prototype is fabricated, and experiments are performed to verify the validation of the proposed converter. [ABSTRACT FROM PUBLISHER]

DC–DC converters with voltage boost capability are widely used in a large number of power conversion applications, from fraction-of-volt to tens of thousands of volts at power levels from milliwatts to megawatts. The literature has reported on various voltage-boosting techniques, in which fundamental energy storing elements (inductors and capacitors) and/or transformers in conjunction with switch(es) and diode(s) are utilized in the circuit. These techniques include switched capacitor (charge pump), voltage multiplier, switched inductor/voltage lift, magnetic coupling, and multistage/-level, and each has its own merits and demerits depending on application, in terms of cost, complexity, power density, reliability, and efficiency. To meet the growing demand for such applications, new power converter topologies that use the above voltage-boosting techniques, as well as some active and passive components, are continuously being proposed. The permutations and combinations of the various voltage-boosting techniques with additional components in a circuit allow for numerous new topologies and configurations, which are often confusing and difficult to follow. Therefore, to present a clear picture on the general law and framework of the development of next-generation step-up dc–dc converters, this paper aims to comprehensively review and classify various step-up dc–dc converters based on their characteristics and voltage-boosting techniques. In addition, the advantages and disadvantages of these voltage-boosting techniques and associated converters are discussed in detail. Finally, broad applications of dc–dc converters are presented and summarized with comparative study of different voltage-boosting techniques. [ABSTRACT FROM AUTHOR]

A novel circuit with the better performance for the inductive pulsed power supplies in the electromagnetic launch system is proposed in this paper, namely, the meat grinder with capacitive pulse forming unit (CPFU). Its working process is qualitatively analyzed stage by stage. Its practical feasibility is verified through a 7.5-kJ experiment. From the perspectives of circuit structure and working principle, this circuit can be regarded as the combination of a meat grinder and a CPFU. Compared with its preceding circuits, this circuit possesses following advantages: 1) the self-recovery of the capacitor precharged voltage can easily be achieved, which is conducive to continuous operations of the whole circuit and 2) the waveforms of the inductor currents contain no capacitive components, which can promote the energy storage density of the inductors. [ABSTRACT FROM PUBLISHER]

This paper proposes a zero-ripple input-current high-step-up boost–single ended primary inductor converter (SEPIC) dc–dc converter with reduced switch-voltage stress to overcome some drawbacks of the conventional cascaded boost–SEPIC dc–dc converter. In the proposed converter, the input current ripple is significantly removed by the auxiliary circuit at the boost stage and the voltage gain is more increased by using turn ratio of a coupled inductor at the SEPIC stage. Additional, the switch-voltage stress is reduced due to the clamping circuit, and the reverse-recovery problem of the output diode is alleviated by the leakage inductor. Hence, the low-voltage-rating MOSFET, which has low $R_{{{\rm ds(on)}}}$, can be utilized as a main switch device. Therefore, the total power efficiency is improved. The theoretical analysis of the proposed converter is verified on an output 200-V to 200-W prototype. [ABSTRACT FROM AUTHOR]

This paper proposes a soft-switched interleaved boost converter with minimal conduction loss increment and removed reverse-recovery problem. The soft-switching operation is enabled by a soft-switching cell composed of passive components in which an auxiliary coupled inductor and a dc-link capacitor are connected between the switch legs of the interleaved boost modules and output stage. Every MOSFET switch of the proposed boost converter operates with zero-voltage switching turn-on using the coupled inductor current. Consequently, the switching loss of the proposed interleaved boost converter is greatly reduced. In addition, the reduced circulating current in the auxiliary circuit minimizes the increment of the conduction loss. The proposed soft-switched interleaved boost converter operation is verified with 500-W experimental results. [ABSTRACT FROM AUTHOR]

This paper explores the feasibility of active clamping techniques in isolated time-sharing (TS) multiple-input converters (MICs). Additional losses caused by energy transfer from the leakage inductance in the isolating coupled-inductor into the input switches are addressed with a common active clamping leg for all input legs. An active clamping technique is applied to isolated TS-MIC to minimize the additional switching losses and voltage stresses on input legs. This paper also conducts an operational analysis of an isolated time-sharing dual-input single-ended primary-inductor converter (I-TS-DI-SEPIC) with the discussed active clamping technique. Zero-voltage switching can be achieved on the first-turned-on input leg and the active clamping leg with a proper driving strategy and well-chosen circuit parameter settings. Discussions on the effect of the active clamping technique to an MIC and the components stresses of the I-TS-DI-SEPIC with the active clamping technique have also been made to assist in the design of TS-MICs. Prototypes of the I-TS-DI-SEPIC with the active clamping technique have been built to demonstrate the performance in the application of split-phase dc distribution systems. Converter efficiency and voltage stresses are experimentally verified, showing that the active clamping technique achieves noticeable efficiency gains and component stress reduction. [ABSTRACT FROM AUTHOR]

This paper presents a new single-phase switched-coupled-inductor dc–ac inverter featuring higher voltage gain than the existing single-phase qZ-source and semi-Z-source inverters. Similar to the single-phase qZ-source and semi-Z-source inverters, the proposed inverter also has common grounds between the dc input and ac output voltages, which is beneficial especially for photovoltaic inverter systems. The inverter volume and maximum current flowing can be reduced significantly through the coupling of all inductors. A theoretical analysis of the proposed inverter is described and a 280-W experimental prototype is built to verify the performance of the inverter. [ABSTRACT FROM AUTHOR]

A novel transformerless buck–boost dc–dc converter is proposed in this paper. The presented converter voltage gain is higher than that of the conventional boost, buck–boost, CUK, SEPIC, and ZETA converters, and high voltage can be obtained with a suitable duty cycle. In this converter, only one power switch is utilized. The voltage stress across the power switch is low. Hence, the low on-state resistance of the power switch can be selected to decrease conduction loss of the switch and improve efficiency. The presented converter has simple structure, therefore, the control of the proposed converter will be easy. The principle of operation and the mathematical analyses of the proposed converter are explained. The validity of the presented converter is verified by the experimental results. [ABSTRACT FROM PUBLISHER]

This paper describes novel single-phase solutions with increased inverter voltage levels derived by means of a nonstandard inverter configuration and impedance source networks. Operation principles based on special modulation techniques are presented. Detailed component design guidelines along with simulation and experimental verification are also provided. Possible application fields are discussed, as well as advantages and disadvantages. Finally, future studies are addressed for the new solutions. [ABSTRACT FROM PUBLISHER]

This paper deals with a new family of high boost voltage inverters called switched-inductor quasi-Z-source inverters (SL-qZSIs). The proposed SL-qZSI is based on the well-known qZSI topology and adds only one inductor and three diodes. In comparison to the SL-ZSI, for the same input and output voltages, the proposed SL-qZSI provides continuous input current, a common ground with the dc source, reduced the passive component count, reduced voltage stress on capacitors, lower shoot-through current, and lower current stress on inductors and diodes. In addition, the proposed SL-qZSI can suppress inrush current at startup, which might destroy the devices. This paper presents the operating principles, analysis, and simulation results, and compares them with those of the SL-ZSI. To verify the performance of the proposed converter, a laboratory prototype was constructed with 48 Vdc input and an ac output line-to-line voltage of 120 Vrms. The simulation and experimental results verified that the converter has high step-up inversion ability. [ABSTRACT FROM AUTHOR]

A novel high step-up dc–dc converter with a quasi-active switched-inductor structure for a renewable energy system is presented in this paper. The proposed converter is composed of two coupled inductors which can be integrated into one magnetic core, two capacitors, two active switches, and three diodes. The primary sides of coupled inductors are charged in parallel by the input source, and the secondary sides of coupled inductors are discharged in series with the input source and two capacitors to achieve high step-up voltage gain with an appropriate duty ratio. The two sets of diode–capacitor circuits not only help to lift the voltage conversion gain but also alleviate voltage spike affected by the leakage inductance to limit the voltage stress across the power switch effectively. Therefore, the two low on-state resistance switches can be adopted to reduce conduction loss. Furthermore, the two diodes have no reverse-recovery problem due to turn off naturally, the reverse-recovery problem of the output diode is also alleviated by the leakage inductor and lower part count is needed; therefore, the power conversion efficiency can be further improved. The operating principles and steady-state analyses are discussed in detail; then, the performance of the proposed converter is compared with existing converters. Finally, a prototype is established in the laboratory, and the experimental results are given to verify the correctness of the analysis. [ABSTRACT FROM AUTHOR]

In this paper, a new topology for half-bridge switched boost inverter (HB-SBI) is proposed. The proposed half-bridge inverter uses more active elements rather than capacitors and inductors in comparison with the conventional half-bridge Z-source inverter with two Z-networks, which results in reduction of weight, size, and cost. Moreover, the proposed inverter has the capability of eliminating inverter leg short-circuit issues and is able to further increase the output voltage level in comparison with its conventional types. Generating zero-level output voltage is also another advantage of this topology. Based on theoretical calculations, the steady-state and small-signal analysis of the proposed topology in different operating modes are performed and the ripple of inductors’ current and capacitors’ voltage are also calculated. A comprehensive comparison is also made between the proposed inverter and the conventional types. Finally, the experimental results are provided to reconfirm the performance of the proposed inverter. [ABSTRACT FROM PUBLISHER]

Power electronics solutions based on multiple converter configurations offer cost-effective solutions by integrating a number of components at input or output power stages. This paper proposes a new multiinput isolated three-level converter for renewable and sustainable energy systems adopting high dc link voltage. Multiple dc sources are integrated to the three-level dc/dc converter before the isolation stage, resulting in reduced part-count, determining dc link voltage level and allowing flexibility in transformer design. The proposed architecture eliminates two boost switches which are present in the two-stage counterpart. The input inductors are operated in discontinuous conduction mode; thus, power can be shared between input sources through proper selection of input inductors. A low voltage prototype has been designed to serve as a proof of concept. [ABSTRACT FROM PUBLISHER]

This paper proposes a novel single-phase ac–ac Z-source converter based on the Γ-structure. The proposed converter uses a coupled transformer to produce the required gain. The obtained gain can be tuned by varying the turn ratio $\gamma _\Gamma$ of the transformer within the narrow range of $1 < \gamma _\Gamma < 2$. Also, the gain factor increases with decrease of the transformer turns ratio, $\gamma _\Gamma$ . Small transformer turn ratio results in more practical topology in some voltage gains. It makes the transformer design easier and reduces construction cost. Also, in the proposed topology, the input and output voltages share the same ground. In order to avoid voltage and current spikes on the switches, a commutation strategy is proposed and safe commutation is achieved without using a snubber circuit. The operating principles and steady-state analyses are presented to verify the operational concept of the proposed topology. Also, experimental results are given to verify the validation of the proposed converter. [ABSTRACT FROM AUTHOR]

In this paper, a family of three-phase direct pulse-width modulated (PWM) ac–ac converters consisting of buck, boost, and buck–boost converters is proposed. The proposed converters have no commutation problem even if all of the switches are turned on or off simultaneously. They do not use lossy snubbers and do not sense the voltage polarity for commutation, and produce high-quality output voltage waveforms. The proposed converters allow the use of power MOSFETs and fast recovery freewheeling diodes independently. The use of power MOSFETs as active switches and freewheeling diodes with extremely fast recovery features lower the switching losses and enable us to reduce the volume of passive components by increasing switching frequency. The input (or output) filter inductor experiences twice of the converter switching frequency and thus can be designed with minimum size. To increase power density of the proposed converters, a three-phase three-limb coupled inductor is proposed. Three-phase coupled inductor integrates three separate coupled inductors of the proposed converters in one three-limb core. In comparison with separate coupled inductors, the three-phase coupled inductor has a smaller size with large current-handling capability. Experimental results obtained for the boost-type converter show the robustness of the proposed three-phase ac–ac converters. [ABSTRACT FROM AUTHOR]

This paper proposes a new topology named the active-switched-capacitor/switched-inductor quasi-Z -source inverter (ASC/SL-qZSI), which is based on a traditional qZSI topology. Compared to other qZSI-based topologies under the same operating conditions, the proposed ASC/SL-qZSI provides higher boost ability, requires fewer passive components such as inductors and capacitors, and achieves lower voltage stress across the switching devices of the main inverter. Another advantage of the topology is its expandability. If a higher boosting rate is required, additional cells can easily be cascaded at the impedance network by adding one inductor and three diodes. Both the simulation studies and the experimental results obtained from a prototype built in the laboratory validate proper operation and performance of the proposed ASC/SL-qZSI. [ABSTRACT FROM AUTHOR]

High voltage gain dc-dc converters are required in many industrial applications such as photovoltaic and fuel cell energy systems, high-intensity discharge lamp (HID), dc back-up energy systems, and electric vehicles. This paper presents a novel input-parallel output-series boost converter with dual coupled inductors and a voltage multiplier module. On the one hand, the primary windings of two coupled inductors are connected in parallel to share the input current and reduce the current ripple at the input. On the other hand, the proposed converter inherits the merits of interleaved series-connected output capacitors for high voltage gain, low output voltage ripple, and low switch voltage stress. Moreover, the secondary sides of two coupled inductors are connected in series to a regenerative capacitor by a diode for extending the voltage gain and balancing the primary-parallel currents. In addition, the active switches are turned on at zero current and the reverse recovery problem of diodes is alleviated by reasonable leakage inductances of the coupled inductors. Besides, the energy of leakage inductances can be recycled. A prototype circuit rated 500-W output power is implemented in the laboratory, and the experimental results shows satisfactory agreement with the theoretical analysis. [ABSTRACT FROM AUTHOR]

This paper presents a high step-up converter for fuel cell energy source applications. The proposed high step-up dc-dc converter is devised for boosting the voltage generated from fuel cell to be a 400-V dc-bus voltage. Through the three-winding coupled inductor and voltage doubler circuit, the proposed converter achieve high step-up voltage gain without large duty cycle. The passive lossless clamped technology not only recycles leakage energy to improve efficiency but also alleviates large voltage spike to limit the voltage stress. Finally, the fuel cell as input voltage source 60-90 V integrated into a 2-kW prototype converter was implemented for performance verification. Under output voltage 400-V operation, the highest efficiency is up to 96.81%, and the full-load efficiency is 91.32%. [ABSTRACT FROM AUTHOR]

This paper presents a dc–dc boost converter with high voltage gain based on the three-state switching cell for split-capacitor neutral-point-clamped inverters. The proposed converter is analyzed considering the operation in continuous conduction mode and duty cycle higher than 0.5, which corresponds to overlapping mode. The main characteristics of the topology are operation at high switching frequency, whereas the input inductor is designed for twice such frequency; in order to minimize weight and volume, the voltage stress across the switches is lower than half of the output voltage and naturally clamped by one output capacitor, allowing the use of MOSFET transistors with reduced intrinsic on-resistance; the input current presents small ripple; the output voltage can be further stepped up by increasing the transformer turns ratio without compromising the voltage stress across the switches; and the output voltage is naturally balanced, thus making the converter suitable for supplying split-capacitor inverters. Several topologies where a high voltage step-up is possible are initially investigated in the literature. Then, the principle of operation and experimental results for a 1-kW prototype are presented to validate the theoretical analysis and demonstrate the converter performance. [ABSTRACT FROM PUBLISHER]

On the basis of the classical Z-source inverter (ZSI), this paper presents a novel ZSI which only contains inductors and diodes in Z-source network. The inverter uses a unique inductor and diode network for boosting its output voltage, provides a common ground for the dc source and inverter, and avoids the disadvantage causing by capacitor in the classical ZSI and SL-ZSI, especially in prohibiting the inrush current at startup and the resonance of Z-source capacitors and inductors. The inverter can increase the boost factor through adjusting shoot-through duty ratio and increasing the number of inductor. The working principle of the proposed ZSI and comparison with the classical ZSI and SL-ZSI are analyzed in detail. Simulation and experimental results are given to demonstrate the operation features of the inverter. [ABSTRACT FROM AUTHOR]

In this paper, a high-conversion-ratio bidirectional dc–dc converter with coupled inductor is proposed. In the boost mode, two capacitors are parallel charged and series discharged by the coupled inductor. Thus, high step-up voltage gain can be achieved with an appropriate duty ratio. The voltage stress on the main switch is reduced by a passive clamp circuit. Therefore, the low resistance R{DS(ON)} of the main switch can be adopted to reduce conduction loss. In the buck mode, two capacitors are series charged and parallel discharged by the coupled inductor. The bidirectional converter can have high step-down gain. Aside from that, all of the switches achieve zero voltage-switching turn-on, and the switching loss can be improved. Due to two active clamp circuits, the energy of the leakage inductor of the coupled inductor is recycled. The efficiency can be further improved. The operating principle and the steady-state analyses of the voltage gain are discussed. Finally, a 24-V-input-voltage, 400-V-output-voltage, and 200-W-output-power prototype circuit is implemented in the laboratory to verify the performance. [ABSTRACT FROM PUBLISHER]

The pulse-train (PT) control technique for switching dc–dc converters is simple to design and benefits from excellent control performance. Up to now, almost all of the works on PT control are focused on switching dc–dc converters operating in discontinuous conduction mode, with few works reported on PT control of switching dc–dc converters operating in continuous conduction mode (CCM). In this paper, a PT-controlled CCM buck converter is studied and a unique low-frequency oscillation phenomenon is revealed, which results in large undesired inductor-current and output-voltage variations. The effect of equivalent series resistance (ESR) output-capacitor on the low-frequency oscillation is examined. The results indicate that such oscillation occurs when the ESR output-capacitor is relatively small and disappears when it is relatively large. However, a larger ESR will result in a large output-voltage ripple. In order to avoid the low-frequency oscillation and, at the same time, to ensure a small output-voltage ripple, the ICRIF circuit is applied. In this way, a small ESR output-capacitor can be used to decrease the output-voltage ripple. Simulation and experimental results are provided to verify the theoretical analysis. [ABSTRACT FROM PUBLISHER]

The PowerChip research program is developing technologies to radically improve the size, integration, and performance of power electronics operating at up to grid-scale voltages (e.g., up to 200 V) and low-to-moderate power levels (e.g., up to 50 W) and demonstrating the technologies in a high-efficiency light-emitting diode driver, as an example application. This paper presents an overview of the program and of the progress toward meeting the program goals. Key program aspects and progress in advanced nitride power devices and device reliability, integrated high-frequency magnetics and magnetic materials, and high-frequency converter architectures are summarized. [ABSTRACT FROM AUTHOR]

This paper provides a perspective on progress toward realization of efficient, fully integrated dc–dc conversion and regulation functionality in CMOS platforms. In providing a comparative assessment between the inductor-based and switched-capacitor approaches, the presentation reviews the salient features in effectiveness in utilization of switch technology and in use and implementation of passives. The analytical conclusions point toward the strong advantages of the switched-capacitor (SC) approach with respect to both switch utilization and much higher energy densities of capacitors versus inductors. The analysis is substantiated with a review of recently developed and published integrated dc–dc converters of both the inductor-based and SC types. [ABSTRACT FROM AUTHOR]

This paper proposes a high step-up solar power optimizer (SPO) that efficiently harvests maximum energy from a photovoltaic (PV) panel then outputs energy to a dc-microgrid. Its structure integrates coupled inductor and switched capacitor technologies to realize high step-up voltage gain. The leakage inductance energy of the coupled inductor can be recycled to reduce voltage stress and power losses. A low voltage rating and low-conduction resistance switch improves system efficiency by employing the incremental conductance method for the maximum power point tracking (MPPT) algorithm. Because of its high tracking accuracy, the method is widely used in the energy harvesting of PV systems. laboratory prototypes of the proposed SPO that have an input voltage range of 20 to 40 V and a maximum PV output power of 400 V/300 W are applied. The highest PV power conversion efficiency is 96.7%. The maximum MPPT accuracy is 99.9%, and the full load average MPPT accuracy is 97.8%. [ABSTRACT FROM AUTHOR]

The LLC resonant converter has drawn much attention for high efficiency. However, its light-load efficiency still cannot meet the ever increasing requirements. This paper proposes a novel burst-mode control for the LLC resonant converter to improve the light-load efficiency. Based on the state-plane trajectory analysis, during the burst-on time, a three-pulse switching pattern is implemented. By optimizing the first pulse width, the state variables are settled to the steady state of the highest efficiency load in the minimal time, and then, the next two pulse operation follows this steady-state trajectory to achieve high burst efficiency. Moreover, when the load changes, the burst-on time with the optimal three-pulse switching pattern is maintained, but the burst-off time is modulated. As a result, the output-voltage low-frequency ripple minimally keeps constant, and no additional filter is needed. Experimental results validate the proposed techniques. [ABSTRACT FROM AUTHOR]

In this paper, a novel single-phase five-level inverter is proposed using coupled inductors. This inverter can output five-level voltage with only one dc source. No split of the dc voltage capacitor is needed, totally avoiding the voltage balancing problem in conventional multilevel inverters. The level of the output voltage is only half of the dc-link voltage in all conditions, leading to much reduced dv/dt . This inverter is based on the widely used three-arm power module and the voltage stresses on all the power switches are the same, making it very easy to construct. Operation mechanism of this inverter is analyzed and the possible switching patterns are investigated. Based on these analyses, a novel optimized modulation scheme is presented. With this modulation method, no dc components exist in the inductor currents, which is very helpful for minimization of the inductors. Simulation and experimental results show the validity of the proposed inverter together with the optimized modulation scheme. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

This paper proposes a generalized scheme of new soft-switching interleaved boost converters that is suitable for high step-up and high-power applications. The proposed converter is configured with proper numbers of series and parallel connected basic cells in order to fulfill the required output voltage and power levels, respectively. This leads to flexibility in device selection resulting in high component availability and easy thermal distribution. Design examples of determining the optimum circuit configuration for given output voltage and power level are presented. Experimental results from a 1.5-kW prototype are provided to validate the proposed concept. [ABSTRACT FROM AUTHOR]

In this paper, a novel high step-up dc–dc converter with coupled-inductor and voltage-doubler circuits is proposed. The converter achieves high step-up voltage gain with appropriate duty ratio and low voltage stress on the power switches. Also, the energy stored in the leakage inductor of the coupled inductor can be recycled to the output. The operating principles and the steady-state analyses of the proposed converter are discussed in detail. Finally, a prototype circuit of the proposed converter is implemented in the laboratory to verify the performance of the proposed converter. [ABSTRACT FROM AUTHOR]

This paper proposes an energy regeneration circuit for three-phase voltage-fed inverters using a modified Undeland snubber. The proposed system uses a quasi-square-wave zero voltage switching dc–dc auxiliary converter to regenerate the energy from snubber capacitor to the dc bus. The regenerative circuit uses a single active switch, and it operates independently of the three-phase inverter. Operation stages, theoretical waveforms, and a design methodology are presented. Experimental results based on a 4.5-kVA three-phase inverter prototype are included to validate the proposed topology. [ABSTRACT FROM PUBLISHER]

A high step-up conversion-ratio converter with soft switching is presented in this paper. By using both coupled inductors and isolated transformer, high voltage gain can be easily achieved without extremely high duty ratio. To deal with switching losses, the active clamping circuit is adopted to achieve the zero-voltage-switching turn-on feature for power switches and to absorb the energy stored in the leakage inductor. Moreover, the series-resonant tanks composed by leakage inductors of the transformer and resonant capacitors are used to achieve the zero-current-switching turn-off feature for rectifier diodes at the output side. Therefore, the turn-on switching loss of power switches and the reverse-recovery problem of rectifier diodes can be eliminated. The operational principles and design consideration are discussed in detail. Finally, experimental results taken from a 400-W prototype are presented to confirm the effectiveness of the proposed converter. [ABSTRACT FROM AUTHOR]

A dual resonant converter with two transformers is presented in this paper. Dual resonant tanks are composed of leakage inductors and resonant capacitors to achieve zero-current-switching turnoff for rectifier diodes at the secondary side of the transformer. Hence, the reverse-recovery problem of the rectifier diodes can be eliminated. Moreover, the active-clamp circuit does not only absorb the energy stored in the leakage inductor but also clamp the voltage stress of power switches. Compared to the conventional dual resonant converter, the zero-voltage switching operation of the proposed converter is easily achieved by using two transformers. The operation principles, design considerations, and realization are discussed in detail. Finally, experimental results from a 400-W laboratory prototype are presented to confirm the effectiveness of the proposed converter. [ABSTRACT FROM AUTHOR]

A novel high step-up dc–dc converter for a distributed generation system is proposed in this paper. The concept is composed of two capacitors, two diodes, and one coupled inductor. Two capacitors are charged in parallel, and are discharged in series by the coupled inductor. Thus, high step-up voltage gain can be achieved with an appropriate duty ratio. The voltage stresses on the main switch and output diode are reduced by a passive clamp circuit. Therefore, low resistance R DS(ON) for the main switch can be adopted to reduce conduction loss. In addition, the reverse-recovery problem of the diode is alleviated, and thus, the efficiency can be further improved. The operating principle and steady-state analyses of the voltage gain are also discussed in detail. Finally, a 24-V input voltage, 400-V output voltage, and 400-W output power prototype circuit of the proposed converter are implemented in the laboratory to verify the performance. [ABSTRACT FROM AUTHOR]

This paper proposes a new high step-up dc–dc converter designed especially for regulating the dc interface between various microsources and a dc–ac inverter to electricity grid. The figuration of the proposed converter is a quadratic boost converter with the coupled inductor in the second boost converter. The converter achieves high step-up voltage gain with appropriate duty ratio and low voltage stress on the power switch. Additionally, the energy stored in the leakage inductor of the coupled inductor can be recycled to the output capacitor. The operating principles and steady-state analyses of continuous-conduction mode and boundary-conduction mode are discussed in detail. To verify the performance of the proposed converter, a 280-W prototype sample is implemented with an input voltage range of 20–40 V and an output voltage of up to 400 V. The upmost efficiency of 93.3% is reached with high-line input; on the other hand, the full-load efficiency remains at 89.3% during low-line input. [ABSTRACT FROM AUTHOR]

A newly designed zero-voltage-switching (ZVS) multi-input converter is proposed in this paper. The converter can boost the different voltages of two power sources to a stable output voltage. An auxiliary circuit is employed for achieving turn-on ZVS of all switches in the proposed converter. According to various situations, the operational states of the proposed converter can be divided into two states, including a single-power-supply and a dual-power-supply state. In the dual-power-supply state, the input circuits connected in series together with the designed pulsewidth modulation can greatly reduce the conduction loss of the switches. In addition, the effectiveness of the designed circuit topology and the ZVS properties are verified by experimental results, and the goal of high-efficiency conversion can be obtained. [ABSTRACT FROM AUTHOR]

This paper proposes a zero-voltage-transition (ZVT) pulsewidth-modulated (PWM) synchronous buck converter, which is designed to operate at low voltage and high efficiency typically required for portable systems. A new passive auxiliary circuit that allows the main switch to operate with zero-voltage switching has been incorporated in the conventional PWM synchronous buck converter. The operation principles and detailed steady-state analysis of the ZVT PWM synchronous converter with a passive auxiliary circuit are presented. All of the semiconductor devices aside from the main switch operate under soft-switching conditions. Thus, the auxiliary circuit provides a larger overall efficiency. The feasibility of the auxiliary circuit is confirmed by the simulation and experimental results. [ABSTRACT FROM PUBLISHER]