Wide Input Voltage Range Research Articles

Full-Bridge Active-Clamp Forward-Flyback Converter with an Integrated Transformer for High-Performance and Low Cost Low-Voltage DC Converter of Vehicle Applications

This paper presents a full-bridge active-clamp forward-flyback (FBACFF) converter with an integrated transformer sharing a single primary winding. Compared to the conventional active-clamp-forward (ACF) converter, the proposed converter has low voltage stress on the primary switches due to its full-bridge active-clamp structure, which can leverage high performance Silicon- metal–oxide–semiconductor field-effect transistor (Si-MOSFET) of low voltage rating and low channel resistance. Integrating forward and flyback operations allows the proposed converter to have much lower primary root mean square (RMS) current than the conventional phase-shifted-full-bridge (PSFB) converter, while covering wide input/output voltage range with duty ratio over 0.5. The proposed integrated transformer reduces the transformer conduction loss and simplify the secondary structure of the proposed converter. As a result, the proposed converter has several advantages: (1) high heavy load efficiency, (2) wide input voltage range operation, (3) high power density with the integrated transformer, and (4) low cost. The proposed converter is a very promising candidate for applications with wide input voltage range and high power, such as the low-voltage DC (LDC) converter for eco-friendly vehicles.

Experimental investigation of PV based modified SEPIC converter fed hybrid electric vehicle (PV‐HEV)

SummaryThis paper presents a high gain modified three‐port dual boost single‐ended primary‐inductor converter (SEPIC) converter operated hybrid photovoltaic (PV)/battery electric vehicle to improve the power transfer capability and efficiency of the power conversion stage. The proposed three‐port dual boost high gain SEPIC converter accepts wide voltage range of input then the conventional single stage SEPIC converter. The three‐winding high frequency coupling transformer integrates the two input sources and step‐up the input voltage. The theoretical and experimental analyses are presented to validate the performance of the proposed modified SEPIC converter in boosting the wide range of input voltage. A 6 kW, 12 to 600 V of experimental model has been developed and tested. The efficiency obtained from the designed model is around 94.11%.

A Flexible Mode Electrolytic Capacitor-Free LED Driver With High Efficiency Over a Wide Range of Input Voltage

The conventional ac-dc LED drivers fail to achieve high efficiency and optimized bus voltage over a wide range of input voltage. In order to obtain the better performance in high-line and low-line conditions simultaneously, a flexible mode LED driver is proposed. The proposed driver can operate in half-voltage input mode at high-line input to achieve relatively low-bus voltage and high efficiency. Meanwhile, the proposed driver can operate in full-voltage input mode at low-line input to cut down the diode loss and switch loss; thus, high efficiency can be also achieved. Meanwhile, zero-voltage switching characteristic of the active switches can be fulfilled in both modes. In addition, the proposed LED driver can achieve electrolytic capacitor free. The detail structure, operational principle, and design considerations are examined in detail. Finally, the feasibility and the effectiveness of the proposed LED driver are verified by an experimental prototype with rated power of 100 W.

A Modular Multilevel Resonant DC–DC Converter

A modular multilevel resonant (MMR) dc-dc converter, its modulation, and control are proposed in this article. The MMR converter inherits the desirable features of both the modular multilevel converter and LLC resonant converter, such as high voltage capability, easy fault-tolerant operation, and soft switching. Besides, the MMR can regulate the output voltage over a wide input voltage range with much narrower frequency range compared to conventional resonant converters. By constantly inserting certain number of submodules into the arm according to the input voltage, the resonant tank voltage can be regulated with a relatively constant amplitude regardless of the wide input variation. This modulation technique is acted as a feedforward loop to roughly regulate the output according to the input voltage, and the feedback loop in the control system precisely regulates the output by varying the switching frequency. Simulations on a 200-kW MMR that converts 9-15 kV to 750 V are provided to verify the effectiveness of the proposed topology and control method. Experimental results on an MMR prototype are also given to demonstrate the feasibility.

Analysis and Design of a Resonant Power Converter With a Wide Input Voltage Range for AC/DC Applications

Resonant converter topologies have the ability to eliminate switching losses through zero-voltage switching (ZVS), making them well-suited for switching operation in the MHz frequency range. However, these types of converters are traditionally very sensitive to changes in input voltage and power level, making them unsuitable as power factor correcting ac–dc converters. This article presents a thorough analysis of the operation of a class DE converter in order to derive a set of conditions under which it can achieve a constant input impedance over a wide input-voltage range (60–325 Vdc) with a constant output voltage (450 Vdc) and, thus, be operated as a power factor correctional (PFC) converter, while maintaining ZVS across the full range. The operation is experimentally verified under dc–dc operation for different power levels at a series of input voltages within the specified range. The implemented prototype achieves conversion efficiencies of up to 94% and handles up to 105-W power at a switching frequency of 2 MHz and above, while achieving constant input impedance over the full input-voltage range, enabling its use as a power factor correcting converter.

Novel Transformerless Buck–Boost Inverters Without Leakage Current

This article presents novel transformerless single-stage buck-boost inverters with reactive power flow capability. The common-mode voltage of the proposed inverters is constant, which results in negligible leakage current. The output current of the proposed inverters is continuous that lowers the output harmonics and size of the output filtering capacitor. In the proposed inverters, only two switches receive high-frequency switching signals at a time, which reduces the power loss. The proposed topologies can achieve efficient power conversion with a wide input voltage range. A 120-Vrms/60-Hz output voltage, 74–200-V input voltage, and 500-W output power hardware prototype of the proposed inverter is built and tested with resistive, partially inductive, and partially capacitive loads. A peak efficiency of 97.3% is obtained.

A Modified Higher Operational Duty Phase Shifted Full Bridge Converter for Reduced Circulation Current

Besides many advantages, the reduction in the operational duty of a traditional phase shifted full converter limits its scope in applications where a wide range of input voltage is the main requirement. Operation with low duty cycle extends freewheeling interval, which results in degraded performance such as more circulating current, increased conduction loss in power devices, narrow range of zero voltage switching and increased EMI. To overcome these drawbacks, this work suggests a modified phase shifted full bridge converter that keeps the operational duty of the converter high for a wide range of input voltage. This cuts the freewheeling interval and improves performance. The proposed converter consists of four low profile transformers having a structure of reconfigurable interconnections. There are two distinct reconfigurable operational modes, a low-gain mode and a high-gain mode, which can be adopted following the variation in line voltage. The proposed work is validated in LTspice simulation and hardware characterization for a wide range of input voltage 100-400 Vdc/ 12 Vout and up to the load power of 1.2 kW.

A Reconfigurable Switched Capacitor DC–DC Converter With 1.9–6.3-V Input Voltage Range and 85% Peak Efficiency in 28-nm CMOS

A reconfigurable step-down switched capacitor dc–dc converter (SCC) capable of operating over a wide input voltage range from 1.9 to 6.3 V is presented in this letter. The converter can be reconfigured in five different topologies, obtaining five different voltage conversion ratios, with a minimum overhead in terms of extra switches and flying capacitors. Prototypes implemented in a 28-nm CMOS technology can deliver up to 0.45-W output power while regulating the output voltage to 0.9 V with a 85% peak efficiency.

Topology-Morphing Photovoltaic Microconverter With Wide MPPT Voltage Window and Post-Fault Operation Capability

In this paper the concept of wide input voltage range photovoltaic microconverter with post-fault operation capability is presented. This microconverter could remain operational in the case of short- or open-circuit failure of any switch of its front-end inverter. When the fault occurs, the control system automatically identifies the fault and applies the special post-fault modulation sequence thus keeping the functionality of the microconverter unchanged. The research findings are validated by the help of a 350 W experimental prototype specially developed for integration of silicon PV modules into the residential DC nanogrids with the nominal voltage of 350 V. Paper explains the multi-mode operation principle and fault identification routine. It presents the experimental efficiencies and evaluates the maximum power point tracking performance of the microconverter prior and after the short-circuit fault of an upper switch of the inverter. The daily energy yield test conducted for both cases has confirmed that the proposed approach can extend the service life of PV microconverters with a moderate impact on their performance.

Triple-Phase-Shift Modulation Strategy for Diode-Clamped Full-Bridge Three-Level Isolated DC/DC Converter

A triple-phase-shift (TPS) modulation strategy with reduced transformer's voltage stress is proposed in this paper for the diode-clamped full-bridge (FB) three-level isolated DC/DC converter. The proposed strategy can keep the transformer's maximum voltage changes (ΔV) at only half of the input voltage (V in /2) by employing three phase-shift delays. Consequently, comparing with the conventional strategies, the merits of the proposed strategy include: 1) reducing the voltage change rate (dv/dt) on the transformer and 2) improving the transformer's voltage harmonics due to the merit of the multi-level voltage. Additionally, the proposed strategy has two operating modes with zero-voltage switching (ZVS) for fulfilling the wide input voltage range. Finally, the proposed strategy is verified by both simulation and experimental results.

Analysis and Design of a Resonant Power Converter with Wide Input Voltage Range for AC/DC Applications

Analysis and Design of a Resonant Power Converter with Wide Input Voltage Range for AC/DC Applications

Design and Implementation of 150 W AC/DC LED Driver with Unity Power Factor, Low THD, and Dimming Capability

This paper presents the implementation of a two-stage light-emitting diode (LED) driver based on commercial integrated circuits (IC). The presented LED driver circuit topology, which is designed to drive a 150 W LED module, consists of two stages: AC-DC power factor correction (PFC) stage and DC/DC power converter stage. The implementation of the PFC stage uses IC NCP1608, which uses the critical conduction mode to guarantee a unity input power factor with a wide range of input voltages. The DC/DC power converter with soft-switching characteristics for the entire load range uses IC FLS2100XS. Furthermore, the design of an electromagnetic interference (EMI) filter for the LED driver and the dimming control circuit are discussed in detail. The hardware prototype, an LED lighting system, with a rated power of 150 W/32 V from a nominal 220 V/50 Hz AC voltage supply was tested to show the effectiveness of the design. The presented LED driver was tested for street lighting, and the experimental results show that the power factor (PF) was higher than 0.97, the total harmonics distortion (THD) was lower than 7%, and the efficiency was 91.7% at full load. The results prove that the performance of the presented LED driver complies with the standards: IEC61000-3-2 and CIRSP 15:2009.

Comparative efficiency analysis for silicon, silicon carbide MOSFETs and IGBT device for DC–DC boost converter

In present study, a comparative efficiency analysis for silicon (Si), silicon carbide (SiC) metal oxide semiconductor field effect transistors (MOSFETs) and insulated gate bipolar transistor (IGBT) device based DC–DC boost converter is performed. Due to different gate-drive characteristics of power semiconductor devices such as Si, SiC MOSFETs and IGBT device, different voltage levels are required to drive aforementioned devices. A 500 W boost converter for wide input voltage range (30–72 V) and 110 V output voltage is designed having a single gate driver circuit for Si, SiC MOSFETs and IGBT. A single gate driver provides the gate-source (or base-emitter in case of IGBT) signal for all the devices which eliminates the use of separate gate driver circuit. Si MOSFET and IGBT are driven by 12 V gate-source voltage whereas SiC MOSFET is operated by 18 V gate-source voltage using the gate driver circuit. An experimental study is performed for the comparative efficiency analysis for Si, SiC MOSFETs and IGBT device based converter for 20 and 50 kHz switching frequencies. It is found that SiC based converter provides highest efficiency ≈ 97.8%, whereas the lowest efficiency ≈ 94% is found for IGBT based converter at 20 kHz switching frequency. SiC based converter gives higher efficiency because lower conduction loss owning to lower on-state resistance as compared to Si MOSFET. Besides this, SiC application has another advantage such as low switching loss at higher frequency resulting compact size of converter. However, use of IGBT at higher switching frequency results in higher switching losses, hence lower efficiency of the converter.

SiC MOSFETs Gate Driver With Minimum Propagation Delay Time and Auxiliary Power Supply With Wide Input Voltage Range for High-Temperature Applications

Low propagation delay time is essential for SiC drivers at high frequency. The propagation delay time of the commercial parts is normally over 100 ns. A signal isolation circuit and a level shifting circuit are proposed and applied in SiC drivers with minimum propagation delay time. The narrow edge signals of the input pulsewidth modulation (PWM) signal are extracted by nondelay RC differential circuits in the control side and demodulated by an RS flip-flop in the drive side so that only two low-profile transformers are used for low-delay signal isolation. A two-stage isolated auxiliary power supply without linear optocouplers is proposed in order to realize wide input voltage range and wide operation temperature range. Wide input voltage range is achieved by forward- feedback control. The experimental results verify the proposed driver advantages. The propagation delay time at 400 kHz is 49.6 ns for the rising edge and 18.4 ns for the falling edge, which are reduced by over 50% compared with the commercial parts. The prototype is tested under the ambient temperature of 85 °C with the 9–18-V input auxiliary power supply. Considering the temperature rise of 28 °C, the operation temperature of the power supply is 113 °C.

System Model and Performance Evaluation of Single-Stage Buck–Boost-Type Manitoba Inverter for PV Applications

This article presents a control methodology for a recently proposed single-stage buck–boost-type inverter in photovoltaic (PV) applications. A wide range of input voltage is covered, and the dc power is effectively converted into the grid power within a single-stage system. However, from the topological characteristics, a ${ C\!L}$ filter is always formed at the system output, which results in a resonance pole in the control system. In the PV system, the panel output voltage keeps varying. Under the traditional control method, stability issues may occur, which poses a challenge to controller design. Thus, targeting PV applications, a comprehensive control methodology is presented in this article. Under such a control scheme, a high-quality ac grid power is guaranteed and the power conversion is maintained in a stable manner. Meanwhile, the maximum power point (MPP) of PV panels is always tracked and no additional current sensor is required in the MPP tracking (MPPT) design. In this article, a detailed system analysis is presented, which includes the system modeling and the stability evaluation. The performance of the presented control methodology is experimentally verified in a 750-W PV inverter platform. Both steady state and dynamic characteristics are in good agreement with theoretical knowledge.

Leakage Inductor Current Peak Optimization for Dual-Transformer Current-Fed Dual Active Bridge DC–DC Converter With Wide Input and Output Voltage Range

A current-fed dual active bridge dc-dc converter using dual transformers is proposed for the energy storage system and electric vehicles, which is suitable to be used in wide input and wide output voltage range bidirectional power flow applications. Optimized switching pattern and the coupling relationship among all the controlled variables have been explored in order to minimize the leakage inductor current peak and rms value in spite of the load and voltage conversion gain variation, which can reduce the current stress in switches and conduction loss. Furthermore, wide ZVS range can be achieved. The preferred optimized working modes and real-time closed-loop implementation by employing the proposed control strategy are given. The ZVS conditions for each switch are discussed in detail. The turns ratio design is also demonstrated. The effectiveness of the proposed method is verified by the experimental results of a 1-kW prototype.

An Output Capacitorless Low-Dropout Regulator With a Low-VDD Inverting Buffer for the Mobile Application

To provide power to the latest mobile applications that use functions with heavy loads, in this letter, we present a capacitorless low-dropout regulator (LDO) that supplies a large load current up to 600 mA. The proposed buffer and the feedforward paths are used to provide a stable operation and fast response along with a large load current. Owing to these schemes, the proposed LDO has a high unity gain frequency of 2.85 MHz at 100 mA with a total compensation capacitance of 5.1 pF. In addition, the LDO operates under a wide input voltage range of 1.5–5.0 V owing to the low-VDD structure. Also, a power supply rejection ratio was –52 dB at 100 kHz. The chip was implemented with a small size of 0.082 mm2 using the I/O devices of a 0.18 μ m CMOS process with a minimum length of 0.5 μ m.

Quadratic buck–boost converter with reduced input current ripple and wide conversion range

This study introduces an advanced DC-DC power converter with two main objectives, (i) to achieve a wide range of voltage gain, which means the converter may work over a wide range of input voltage for a fixed desired output voltage and (ii) to achieve a reduced input current ripple. Those features are highly desired in renewable energy applications, for example with photovoltaic panels and fuel cells. The proposed converter was designed in a structure in which the input voltage is composed by the difference of two inductor currents, the currents through inductors are driven with transistors that may have different duty cycle, this allows the current ripple cancellation. In addition, the structure of the converter provides a quadratic type voltage gain, which leads to a wide range of operation voltage. The converter achieves both the wire range of voltage gain and current ripple cancellation, nonetheless, the buck-boost capability is also provided. The input current ripple reduction helps preserve the renewable energy sources since they suffer deterioration when current with considerable ripple is drawn from them. Dynamic and steady-state analysis are performed along with the components sizing. Simulation and experimental results are provided to demonstrate the principle of the proposition.

Algebraic Series-Parallel-Based Switched-Capacitor DC–DC Boost Converter With Wide Input Voltage Range and Enhanced Power Density

This article presents an algebraic series–parallel (ASP) topology for fully integrated switched-capacitor (SC) dc–dc boost converters with flexible fractional voltage conversion ratios (VCRs). By elaborating the output voltage ( ${V} _{\textrm {OUT}}$ ) expression into a specific algebraic form, the proposed ASP can achieve improvements on both the charge sharing and bottom-plate-parasitic losses while maintaining the high topology and fractional VCR flexibility of conventional two-dimensional series–parallel (2DSP) converters. The proposed method consists of a generic ASP topology framework with systematic parameter determination for a precise converter implementation, and can theoretically surpass the power-conversion efficiency (PCE) of 2DSP converters. Fabricated in 65-nm bulk CMOS, we designed a fully integrated ASP-based SC rational boost converter by cascading with the Dickson topology, with a total of seven rational VCRs to boost an input voltage of 0.25–1 V to a 1-V output. Delivering a maximum loading power of 20.4 mW, the chip prototype achieves a peak efficiency of 80% at a power density of 22.7 mW/mm2.

Implementation of a Parallel-Series Resonant Converter with Wide Input Voltage Range

A new resonant converter is presented to have the advantages of soft switching operation on power devices, without reverse recovery current loss on power diodes and wide input voltage range operation. Resonant converter with frequency modulation is adopted in the proposed circuit to accomplish the low switching loss on power switches and possible zero current switching operation on fast recovery diodes. To improve the problem of limit voltage range operation in the conventional resonant converter, a new parallel-series structure resonant converter is studied to achieve wide input voltage operation capability, such as from Vin,min to 4Vin,min. A 1.8 kW laboratory circuit is implemented, and the measured results are provided to confirm the theoretical analysis and circuit performance.