Input Voltage Range Applications Research Articles

A dual-mode buck converter with dynamic sawtooth voltage for wide input voltage range application

A dual-mode buck converter with dynamic sawtooth voltage for wide input voltage range application

An ISOP LLC Converter With Changeable Equivalent Magnetizing Inductance Utilizing Coupled Inductor for Ultrawide Input Voltage Range Application

An ISOP LLC Converter With Changeable Equivalent Magnetizing Inductance Utilizing Coupled Inductor for Ultrawide Input Voltage Range Application

Hybrid PFM and PWM Modulation Strategy for Stacked Structure LLC Resonant Converter With Wide Input Voltage Range Application

Hybrid PFM and PWM Modulation Strategy for Stacked Structure LLC Resonant Converter With Wide Input Voltage Range Application

Highly Efficient Nonisolated Constant Output Current LCC Resonant Converter With Wide Input Voltage Range

This paper proposes a simple structure highly efficient low-element-count non-isolated constant output current resonant converter for wide input voltage range and high-efficient applications. The converter is developed by combining a basic buck-boost converter with a half-bridge LCC resonant converter to improve the adjustable voltage conversion ratio. In the proposed structure, most of the output power is fed directly, which reduces the conduction power losses and increases efficiency by reduction of the processed power and the switches and rectifier diodes voltage stress is significantly decreased due to cascaded outputs structure. It operates at the resonant frequency to achieve a constant output current feature for applications such as LED drivers and battery chargers and the output current is regulated by the pulse-wide modulation (PWM). The proposed converter can achieve zero-voltage switching (ZVS) operation for all switches and zero-current switching (ZCS) operation for all diodes over a wide range of the input voltage and load conditions. The proposed structure is analyzed in detail. To verify the proposed converter performance, a 21 W laboratory prototype is realized and tested for the wide input voltage range of 12–40 V to provide 350 mA output current. The proposed converter achieves high peak efficiency of 98.15%.

Interleaved Boost-Integrated LC Series Resonant Converter With Frequency-Free Designed Transformer for Wide Voltage Range Applications

This paper presents a novel interleaved boost integrated LC series resonant converter with two output rectification modes, which are voltage-doubler rectifier mode and voltage-quadrupler rectifier mode with constant output voltage for wide input voltage range applications. Due to the symmetrical configuration of the rectifier, the voltage stress of switches and diodes on the secondary side are only half of the output voltage. With the proposed pulse frequency modulation, the maximum magnetic flux density <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">B_m</i> of high frequency transformer is only related with the resonant frequency rather than the switching frequency. Hence, the transformer can be frequency-free designed. The zero-voltage-switching of the primary switches and zero-current-switching of the secondary switches and diodes are achieved, respectively. Moreover, the design procedure for some key parameters is presented. Finally, a 470 W prototype with a switching frequency range from 50 kHz to 140 kHz is built to verify the operation principles of the proposed converter and modulation.

Two-Stage Hybrid Isolated DC–DC Boost Converter for High Power and Wide Input Voltage Range Applications

A two-stage hybrid isolated dc–dc boost converter for high power and wide input voltage range applications is proposed. It can be used as a front-end dc–dc converter that can boost variable low voltage from a power source [battery (home/industrial inverter/industrial UPS application), fuel-cell or solar-PV] and interface it to a high-voltage dc-ink, which typically feeds an inverter. A detailed comparison among the different family of converter topologies for isolated dc–dc boost application is carried out that can prove to be useful for power electronics engineers to choose the correct topology for a given input voltage range. The quantitative comparison takes into account the power device utilization, transformer utilization, capacitance utilization, and inductive energy requirement. Based on the comparison, it is shown that with input voltage variation greater than ±20%, two-stage hybrid isolated dc–dc boost converter is superior compared to other family of converters. Design details for the two-stage converter are provided. The converter is developed and tested for a 5 KW inverter application with an input dc voltage range of 90–170 V and output ac voltage of 230 V. Theoretical analysis for loss calculations is also provided which closely matches the experimental results.

Real Time Hardware-in-Loop Implementation of LLC Resonant Converter at Worst Operating Point Based on Time Domain Analysis

The inductor inductor capacitor (LLC) resonant topology has become more popular for deployment in high power density and high-efficiency power converter applications due to its ability to maintain zero voltage switching (ZVS) over a wider input voltage range. Due to their ease of operation and acceptable accuracy, frequency domain-related analytical methods using fundamental harmonic approximation (FHA) have been frequently utilized for resonant converters. However, when the switching frequency is far from the resonant frequency, the circuit currents contain a large number of harmonics, which cannot be ignored. Therefore, the FHA is incapable of guiding the design when the LLC converter is used to operate in a wide input voltage range applications due to its inaccuracy. As a result, a precise LLC converter model is needed. Time domain analysis is a precise analytical approach for obtaining converter attributes, which supports in the optimal sizing of LLC converters. This work strives to give a precise and an approximation-free time domain analysis for the exact modeling of high-frequency resonant converters. A complete mathematical analysis for an LLC resonant converter operating in discontinuous conduction mode (DCM)—i.e., the boost mode of operation below resonance—is presented in this paper. The proposed technique can confirm that the converter operates in PO mode throughout its working range; in addition, for primary MOSFET switches, it guarantees the ZVS and zero current switching (ZCS) for the secondary rectifier. As a function of frequency, load, and other circuit parameters, closed-form solutions are developed for the converter’s tank root mean square (RMS) current, peak stress, tank capacitor voltage, voltage gain, and zero voltage switching angle. Finally, an 8 KW LLC resonant converter is built in the hardware-in-loop (HIL) testing method on RT-LAB OP-5700 to endorse the theoretical study.

Isolated DC–DC Boost Converter for Wide Input Voltage Range and Wide Load Range Applications

A current-fed dual-inductor resonant full-bridge dc–dc isolated boost converter is proposed. The converter is most suitable for applications that demand wide input voltage and load ranges. It can be used as a front-end dc–dc converter that can boost variable low voltage from a power source [battery (home/industrial inverter/industrial UPS application), fuel-cell, or solar-PV] and interface it to a high-voltage dc-link, which typically feeds an inverter. It removes all major drawbacks of conventional current-fed isolated dc–dc converters, namely high-voltage spikes across the switches due to transformer leakage inductance, need for additional start-up circuit, and difficulty in converter tripping in case of faults. Soft-switching of rectifier didoes and clamping power switches is load independent leading to good efficiency over entire load range. Converter can be operated with <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">D</i> < 0.5, making it suitable for wide input voltage range applications. A detailed comparative analysis with state-of-the-art converters for wide input voltage range applications considering the major important factors, such as power device utilization, transformer utilization, inductive energy requirement, and dc capacitors utilization, confirms the superiority of the proposed converter. Experimental results for a 2.5 kVA inverter application with an input dc voltage range of 90–160 V and output ac voltage of 230 V are provided.

A Novel Polymorphic Topology with Hybrid Control Strategy Based LLC Resonant Converter for Ultra-Wide Input Voltage Range Applications

To realize effective utilization of renewable energy sources, a novel polymorphic topology with hybrid control strategy based LLC resonant converter was analyzed and designed in this paper. By combining the merits of a full bridge LLC resonant converter, three-level half bridge LLC resonant converter, and variable frequency control mode, the converter realizes an intelligent estimation of input voltage by automatically changing its internal circuit topology. Under this control strategy, different input voltages determine different operation modes. This is achieved in full bridge LLC mode when the input voltage is low. If the input voltage rises to a certain level, it operates in three-level half bridge LLC mode. These switches are digital and entirely carried out by the DSP (Digital Signal Processor), which means that an auxiliary circuit is unnecessary, where a simple strategy of software modification can be utilized. Experimental results of a 500W prototype with 100V~600V input voltage and full load efficiency of up to 92% are developed to verify feasibility and practicability. This type of converter is suitable for applications with an ultra-wide input voltage range, such as wind turbines, photovoltaic generators, bioenergy, and other renewable energy sources.

A ZVZCS Hybrid Dual Full-Bridge Converter Suitable for Wide Input Voltage Range

A phase-shift modulated converter with two full bridges at primary side and rectifier diodes in hybrid combination at secondary side is proposed in this article. Due to the proposed symmetrical modulation strategy, two full-bridges always equally share the total system power rating, and thus the VA rating of two transformers is minimized. The circulating currents decay to zero in the zero state, contributing to reduce the conduction loss and duty-cycle loss. Zero-voltage or zero-current switching is achieved for all switches over whole input voltage range with an auxiliary inductor. The rectifier output voltage is synthesized of two controlled transformer secondary voltages all the time, which achieves the same output current ripple suppression effect as the conventional input-parallel output-parallel full-bridge converters with interleaved control scheme, and reduces the voltage stress of rectifier diodes. These advantages make the converter suitable for wide input voltage range applications. In this article, the operation principle and steady-state analysis of the proposed converter are illustrated in detail. Experimental results with 220–460 V input voltage are demonstrated to verify the advantages.

Analysis of a Hybrid Variable-Frequency-Duty-Cycle-Modulated Low-$Q$ $LLC$ Resonant Converter for Improving the Light-Load Efficiency for a Wide Input Voltage Range

Light load efficiency and output voltage regulation of alow-Q LLC resonant converter is a critical problem for wide input voltage and load range applications. Parasitic capacitances such as rectifier diode junction capacitance (C3) degrade the soft switching performance. Compact size, high density, and high transformer turns-ratio requirements for microinverter applications add significant distributed capacitance (Cd) of the low-profile transformer, worsening the output regulation and zero-voltage-switching (ZVS) capability at light loads. Wide switching frequency requirement for regulation at light loads, which increases core losses and turnOFF switching losses in power MOSFETs, further degrades the power conversion efficiency. The conventional phase-shift modulation causes a high circulating current and loss of ZVS at light loads. Therefore, a hybrid adjustable switching-frequency-dutycycle modulation technique for improving the light load efficiency is proposed and analyzed for a full-bridge LLC resonant converter. Accurate loss analysis for the proposed modulation scheme, including the effect of parasitic capacitances, is performed using time-domain equations. The proposed methodology precalculates the optimal duty cycle at light load conditions for the required input voltage range such that minimum power losses are incurred. Variation in switching frequency at the preselected duty-cycle value regulates the output voltage. ZVS over a wide range of operating conditions is observed. An experimental prototype for a 20-40 V input, 380-V/300-W output LLC converter is tested for the validation of theoretical analysis.

A Novel LLC Converter With Topology Morphing Control for Wide Input Voltage Range Application

Wide voltage gain range applications are challenging for dc/dc converters, and the system efficiency would be degraded in order to satisfy the voltage gain requirement. Inductor–inductor–capacitor ( <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">LLC</i> ) resonant converters have gained popularity owning to its high efficiency feature. However, wide voltage gain range applications also challenge the <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">LLC</i> converters from the following three aspects: 1) large switching frequency operating range is required to meet the voltage gain requirement, which degrades the converter electromagnetic interference (EMI) performance and challenges the optimization of magnetic components; 2) small inductor ratio is required to boost the voltage gain, which increases the resonant tank root-mean-square (rms) current and conduction loss; and 3) control instability issues may occur at both maximum voltage gain and minimum voltage gain, which reduce the converter reliability. To address these issues, in this article, a novel <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">LLC</i> converter with topology morphing control is proposed for wide voltage gain range applications. Three operation modes, dual full-bridge (DFB), hybrid full-bridge and half-bridge (HFBHB), and dual half-bridge (DHB), can be achieved by adopting the topology morphing control, which can cover a wide voltage gain operation range. Operational principles, design considerations, and experimental validations of the proposed converter are presented.

Full-bridge resonant converter with hybrid control for wide input voltage range applications

This paper proposes a hybrid control strategy for a full-bridge resonant converter. In the applications with a wide input voltage, a resonant converter with variable frequency control (VFC) has to modulate the converter operating in a wide switching frequency range to satisfy gain requirements, which results in some problems such as difficulty in optimizing the design of magnetic components, increased power loss and deteriorated electromagnetic interference. By use of VFC, primary-side phase shift control and secondary-side phase shift control, the frequency variable range can be greatly reduced and the conversion efficiency can be increased, which make the converter appropriate for a wide input voltage range. With this hybrid control strategy, the converter can automatically convert to the corresponding control mode according to variations of the input voltage and load, which has a good transient performance. The working principle, gain characteristics and design considerations of a hybrid controlled CLL resonant converter are introduced in detail. Experimental results are shown to demonstrate its validity and feasibility.

Interleaved centre clamped forward converter (ICCFC) for wide input voltage range applications

A new interleaved centre clamped forward converter for high current applications is proposed. It is a series input and series output structure with common active clamp reset branch. In the proposed converter, both the high input voltage stress and output current stress are reduced. The converter comprises of two active clamp forward converters with one common centre clamp reset circuit and the series output comprises of a current double rectifier (CDR) with self-driven synchronous rectifier (SDSR). The capacitor divider at the input reduces the switching stress due to input voltage. The common centre clamp circuit enables the transformer core reset without any additional circuit and enables zero volt switching. The SDSR-based CDR reduces burden on the secondary side of the transformer by an additional current sharing. Extended duty cycle beyond 50% is achieved. Overall reduction in the size of magnetic components with reduced part count and high-power density is attained. Prototype for 50 W with input voltage in the range of 50—200 V, 5 V/10 A output at 100 kHz was developed. The experimental results match the theoretical investigations.

Multiphase Quasi-Z-Source DC–DC Converters for Residential Distributed Generation Systems

A multiphase quasi-Z-source (qZS) dc–dc converter was proposed for distributed energy generation applications. It contains single-switch qZS isolated dc–dc cells with a voltage doubler rectifier. These cells are connected in parallel at the input side and in series at the output side to increase the dc voltage gain. A dc voltage blocking capacitor in series with the isolation transformer results in resonance that could be utilized for soft-switching. Two design approaches were proposed: considering phase shedding dependent on the input voltage and without it. The former targets wide input voltage range applications, while the latter is better suited for high input current applications. An experimental prototype rated for 300 W was tested with two types of isolation transformers designed according to the two presented approaches. It could be used as a PV module integrated converter with wide input voltage regulation range. The experimental results prove efficiency improvement from the phase shedding. Resonance frequency variations caused by the utilization of the multilayer ceramic capacitors and their possible influence on switching losses are discussed.

Series-Input Interleaved Forward Converter With a Shared Switching Leg for Wide Input Voltage Range Applications

A method for extending the duty cycle range of series-input interleaved forward converter (SII-FC) is proposed in this paper. A family of novel SII-FC topologies is derived by integrating two switching legs, which belong to two forward cells, into one switching leg shared by both the two forward cells in the SII-FC. By employing the proposed method, the derived topologies have the advantages of extended duty cycle, reduced components, and conduction losses, which help to achieve high power density and high efficiency. These advantages make the SII-FC topologies suitable for such applications with wide input voltage range. A series-input interleaved two-switch forward converter (SII-TS-FC) is analyzed in detail, which is a typical SII-FC topology developed by the proposed method. It is composed of two low-voltage switching legs and a high-voltage switching leg. Detailed analysis indicates that the maximum duty cycle of the SII-TS-FC can reach 2/3, which is 1.33 times of that of the two-switch forward converter. The switches of the high-voltage leg can be soft-switched when duty cycle is less than 0.5, while the switches of the low-voltage legs can be soft-switched when duty cycle is larger than 0.5. As a result, high efficiency is achieved over a wide voltage range. In addition, the output filter can be reduced due to the interleaving operation of the two forward cells. The operational principles, characteristics, and design considerations for the proposed SII-FC are presented. Experimental results on the SII-TS-FC prototype with 200-400 V input 48 V/12 A output verify the proposed method and analysis.

Operation Mode Analysis and Peak Gain Approximation of the LLC Resonant Converter

With the advantage of achieving zero voltage switching for a wide input voltage range, the LLC resonant topology has become increasingly popular for use in high power density and high-efficiency power converter applications. However, when the LLC converter is applied to wide input voltage range applications, the widely used fundamental harmonic approximation is incapable of guiding the design due to its inaccuracy. Thus an accurate LLC converter model is desired. In this paper, a generalized mode analysis is presented that provides highly accurate prediction on resonant current and voltage behavior and dc gain characteristic. Also, because operation modes are affected by load, frequency, and gain conditions, the boundaries and distribution of modes are discussed and illustrated. Based on the mode analysis, an approximation method is developed to estimate the peak gain point, which is useful in LLC design. This approximation demonstrates high accuracy within the simulation results. An experimental prototype is built to verify the analysis.

A Low-Cost High Power Factor Battery Charger based on Standard Peak-Current Mode Integrated Controllers

In recent years, several low-cost Power Factor Corrector (PFC) control techniques operating in Continuous Conduction Mode (CCM) have been proposed to simplify traditional control strategies based on a multiplier. This simplification makes sense in the case of relatively low-power, low-cost and wide input voltage range applications. These techniques revolve above the Boost converter as a first stage of a.c.-d.c. power supplies, because their application in other topologies is more expensive and complex. In some applications, however, a PFC can be used as a one-stage power supply. This paper presents a new low-cost control strategy suitable for the Flyback family of PFCs (e.g., Buck-Boost, Flyback, SEPIC, Cuk and ZETA). Control is carried out by a standard Peak Current-Mode Integrated Controller (PCMIC) for d.c.-d.c. converters. Neither an analog multiplier nor an input voltage sensor is needed to achieve quasi-sinusoidal line waveforms, which makes this method very attractive for low-cost applications. In fact, this method is the simplification of One Cycle Control (OCC), also called Linear Peak Current Mode Control (LPCMC), applied to the Flyback family of PFCs. In this case, the use of a simple exponential compensation ramp instead of linear ramp is the proposed solution for reducing the Total Harmonic Distortion (THD). Moreover, the line current is cycle-by-cycle controlled and therefore the input current feedback loop is extremely fast, thus allowing the use of this type of control with high frequency lines. Finally, an experimental prototype of a battery charger was developed as a high Power Factor (PF) power supply to verify the viability of the new control strategy.

Zero-Voltage and Zero-Current-Switching PWM Combined Three-Level DC/DC Converter

This paper proposes a zero-voltage and zero-current-switching (ZVZCS) PWM combined three-level (TL) dc/dc converter, which is a combination of a ZVZCS PWM TL converter with a ZVZCS PWM full-bridge converter. The proposed converter has the following advantages: all power switches suffer only half of the input voltage; the voltage across the output filter is very close to the output voltage, which can reduce the output filter inductance significantly; and the voltage stress of the rectifier diodes is reduced too, so that the converter is very suitable for high input voltage and wide input voltage range applications. The converter also can achieve zero-voltage-switching for the leading switches and ZCS for the lagging switches in a wide load range to achieve higher efficiency. The design considerations and procedures are presented in this paper. The operation principle and characteristics of the proposed converter are analyzed and verified on a 400-800-V input and 54-V/20-A output prototype.

Analysis and implementation of a dual-output LLC resonant converter

This article analyses and presents an LLC resonant converter with a high power factor for LCD-TV applications. It integrates the advantages of power factor correction and the LLC resonant converter. It can improve not only power quality but also circuit efficiency. Since the power factor corrector is used in the first stage of the LLC resonant converter, it is suitable for wide input voltage range application. On the basis of the resonant behaviour, zero voltage switching is achieved for the power switches and ZCS is achieved for the rectifier diodes. An experimental prototype of 90–260V rms input and 12V/10A and −12V/10A outputs with 92.6% efficiency for 32″ LCD-TV application is built in the laboratory to verify the operation principle of the adopted converter.