Wide Voltage Gain Range Research Articles

Review of Techniques for Resonant Converters With Wide Voltage Gain Range Applications

Review of Techniques for Resonant Converters With Wide Voltage Gain Range Applications

Integrated Quasi-Two-Stage Buck-LC Converter With Wide Voltage Gain Range

Integrated Quasi-Two-Stage Buck-<i>LC</i> Converter With Wide Voltage Gain Range

Phase-Shifting Adaptive LLC Resonant Converter with Reduced Turn-Off Loss in Wide Voltage Application

In this paper, a hybrid control method with adaptive phase-shifting modulation (PSM) and pulse-frequency modulation (PFM) is proposed to optimize the steady-state performance of an LLC resonant converter in wide voltage-gain range application. For the primary-side switches under the hybrid control method, zero-voltage switching (ZVS) performance is maintained over wide voltage-gain range and the turn-off loss is reduced; therefore, the converter reconciles wide voltage-gain range and high efficiency. Mode characteristics under different phase-shifting-angle-θ and switching-frequency-fs combinations is analyzed, and then the soft-switching characteristic is revealed. By introducing time domain analysis, the turn-on current of the primary-side switches is calculated, and thus the ZVS boundary of different θ and fs combinations is inferred. In addition, to acquire the optimum steady-state operation of the converter, the turn-off current is calculated; by making the converter work near to the minimum turn-off current operating point, the turn-off loss can be reduced greatly. With the principles of achieving ZVS performance and minimizing turn-off current, the phase-shifting angle θ of PSM is designed to be adaptive to the reference output voltage, no additional circuits are needed, and the two control degrees (θ and fs) are simplified to one (fs). The simulation and experiment are developed to verify the feasibility and effectiveness of the hybrid control method; the results show that ZVS performance is maintained at wide voltage-gain range and the turn-off current of the hybrid control method is reduced to that of the single PFM, and thus the turn-off loss is reduced. The efficiency comparison validates the fact that the hybrid control method has less power loss than single PSM and single PFM.

Dual LC parallel multi‐resonant DC‐DC converter with wide output‐voltage range

SummaryAlthough LLC converters have widespread applications due to their advantages of high efficiency, high power density, and soft switching, in wide voltage gain range applications, a large switching frequency range is inevitably required, which may bring difficulties in converter design and efficiency improvement. In this paper, a dual LC parallel multi‐resonant converter (MRC) is introduced. The converter contains two parallel LC resonant branches in the resonant tank, which exhibit the notch filter characteristic on the gain curve. It enables the converter to provide wide voltage gain regulation, soft startup, and overcurrent protection over a limited frequency range. Compared to other five‐element MRCs, since the converter provides different current loops for the fundamental wave and the third harmonic to transmit active power, the circulating reactive energy and stress on the resonant components are reduced. Finally, a detailed design procedure for a 3.3 kW converter prototype with an output voltage range of 250–450 V is provided.

Bidirectional Hybrid DC–DC Resonant Converter With Wide Voltage Gain Range

Bidirectional Hybrid DC–DC Resonant Converter With Wide Voltage Gain Range

Phase-Shift Modulated Hybrid LLC and Half-Bridge Converter With Fixed Frequency for Wide Voltage Gain Range Application

Phase-Shift Modulated Hybrid LLC and Half-Bridge Converter With Fixed Frequency for Wide Voltage Gain Range Application

Dual-Working-Modes-Based Common Grounded Nonisolated DC-DC Converter With a Wide Voltage-Gain Range for Photovoltaic Applications

Dual-Working-Modes-Based Common Grounded Nonisolated DC-DC Converter With a Wide Voltage-Gain Range for Photovoltaic Applications

Performance of a novel DC-DC low voltage stress boost converter for fuel-cell vehicle

Air pollution, global warming, depletion of fossil fuels and the lack of access to them due to potential political conflicts are some of the challenges that have forced governments to take necessary measures to promote and invest in the development of electric vehicles (EVs). One of the most important parts of EVs is dc-dc converter. A novel step-up single-switch unidirectional topology for a dc-dc converter is proposed in this paper. Some of the advantages of the proposed topology are the use of single-switch, ground switching, low input current ripple, wide range of voltage gain (VG), high level of VG, low stress level for semiconductor components, low input current ripple, small number of semiconductor and passive elements, high efficiency, and no need for high frequency transformer or coupled inductors. Topology analysis is done in continuous current mode (CCM) and calculations related to efficiency and appropriate design are performed to select the converter parameter values. Also, the proposed topology is compared with other similar topologies to show its high performance and superiority. To confirm the theoretical basis, laboratory prototype waveforms are evaluated and an efficiency of 93.2% is obtained.

A Variable-Mode Bidirectional Isolated Power Converter for Wide Voltage-Transfer Ratio Applications

Lithium battery charging require a wide voltage gain range. Due to the limited voltage gain range of LLC converter, it is limited in battery storage application scenarios. In this paper, A interleaved parallel LLC converter is proposed to realize the charging and discharging processes of bidirectional battery energy storage systems. The converter extended range of voltage gain required for battery recovery area by mode switching control. For the interleaved parallel mode power equalization problem, a gain compensation control strategy is proposed to solve the power equalization problem of the converter in this mode. This results in more uniform thermal and current stresses on the charger, as well as smaller input and output ripple. Moreover, with the proposed variable-mode control strategy, the efficiency of the charging process remains above 90%. A 1.5-kW experimental platform was developed to validate the performance of the proposed converter.

DC-DC Boost Converter with Reduced Switching Losses in Wide Range of Voltage Gain

This article presents the results of research on a new topology of a DC-DC converter in which switching losses are reduced by an auxiliary switching circuit (ASC). The proposed ASC can work as a passive or active circuit depending on the voltage gain of the converter. In both cases, this does not affect the operation of the main circuit and is analogous to a classic boost converter, which allows the use of the same control circuits and methods. The operation of the ASC is synchronized with the control of the main converter transistor. The reduction of transistor turn-off losses over a wide range of converter gain is a unique advantage of the proposed auxiliary circuit. This is evidenced by the comparison of the loss reduction with the classic boost converter and the reference converter with soft turn off. This article presents an in-depth analytical discussion related to the reduction of power losses, supported by simulation results, and verified experimentally.

Common Grounded Wide Voltage-Gain Range DC–DC Converter With Zero Input Current Ripple and Reduced Voltage Stresses for Fuel Cell Vehicles

A dc–dc converter used for fuel cell vehicles should be characterized by a wide voltage-gain range and low input current ripple. In order to meet the above requirements, a new nonisolated dc–dc converter consisting of an active switched-inductor cell, a zero current ripple cell, and a switched-capacitor (SC) cell was proposed in this article. The proposed converter integrates with the advantages of a wide voltage-gain range, zero input current ripple, low voltage stresses across power semiconductors, and common ground structure. Thanks to the use of a zero current ripple cell, not only the input current ripple is reduced but also the energy transfer path of the SC cell is changed, thereby reducing the instantaneous peak current of the SC structure. The operating principles, the characteristics analysis, and the parameter design of the proposed converter are given. In addition, to show the merits of the proposed converter, a comparison study is demonstrated. Finally, a prototype of 400 V, 1000 W/50 kHz is developed to validate the effectiveness of the proposed converter.

Non-Backflow-Power and Reduced-Switching-Loss Modulation for Bidirectional Series Resonant Converter With Wide Gain Range

In the achievement of high power efficiency over a wide gain range for a bidirectional series resonant converter (BSRC), conduction losses caused by backflow power and switching losses are two challenges. In this article, a novel modulation of the BSRC is proposed for a wide voltage gain range and high efficiency as well. With the proposed modulation, the BSRC can operate in both buck- and boost-like modes for a wide gain range. The resonant current is in phase with the terminal voltage on both primary and secondary sides, to eliminate the backflow power for the reduction of conduction losses. Hard turn-off problem is alleviated with a resonant current fully released before the completion of the switching cycle. Thus, the number of hard switching actions is significantly reduced compared with existing modulation schemes in the literature. A control scheme based on state-flowchart is also proposed to realize seamless transition among different working modes. To validate the proposed modulation, a 1 kVA prototype of BSRC is developed and interfaces a high-voltage bus ranging from 240 to 480 V and a low-voltage bus ranging from 24 to 56 V. Compared with conventional modulation schemes, efficiency enhancement can be observed over the whole operating range.

Investigation of ZVS Criteria and Optimization of Switching Loss in a Triple Active Bridge Converter Using Penta-Phase-Shift Modulation

Triple active bridge (TAB) as an isolated multiport dc–dc converter is a promising solution for integrated energy management systems to maintain an efficient power flow between the ports. This article presents the design, modeling, and switching loss optimized phase-duty-controlled PWM modulation scheme of a TAB converter composed of three full-bridge modules and a high-frequency planar transformer. The work aims at the derivation and analysis of the zero-voltage switching (ZVS) conditions for a TAB, where the turn-on switching loss is mitigated along with attaining an improved EMI performance, comprising of reduced noise peaks. Moreover, an optimized five-variable control-based TAB PWM modulation technique is proposed in this article in order to achieve minimized switching loss and the overall system loss for a wide voltage gain and load range. The instantaneous switching currents, responsible for the switching losses at the devices, are derived from the transformer winding current expressions, formulated employing the generalized harmonic approximation (GHA) technique. The various loss minimization techniques and the theoretically obtained criteria for ZVS are experimentally verified using a laboratory-developed prototype of an 800-W TAB converter. With the implementation of the proposed optimal phase-duty control, the experimental results show a nonunity gain light-load efficiency increment up to 10% compared to the conventional phase-shift modulation alone.

Advanced Modulation Scheme of a Dual-Active-Bridge Series Resonant Converter (DABSRC) for Enhanced Performance

This paper proposes a two-degree-of-freedom (2-DoF) modulation technique for the efficient optimization of an open-loop three-phase dual-active-bridge series resonant converter (3P-DABSRC). The efficiency and performance of an conventional dual-active-bridge (DAB) converter decrease when it is operated over a wide range of voltage gain. The efficiency and performance of a DAB converter depend upon the switching and conduction losses. Circulating current is the main cause of conduction loss, and hard switching of active switches adds a switching loss. To increase the performance of DAB converters, the first objective is to minimize the conduction loss, and the second objective is to reduce the switching loss. Still, unfortunately, it is not easy to achieve these two objectives simultaneously. Circulating current helps us to reduce the switching loss, but the unbridled amount of circulating current will increase the root-mean-square inductor tank current, and as a result, the conduction loss will be increased. This paper presents an advanced modulation scheme for a 3P-DABSRC that can be used not only in low-power applications, but also in high-power applications. The DABSRC consists of a series LC resonant tank, isolated high-frequency transformer, and dual active bridge connected with the primary and secondary sides of the transformer. The proposed 2-DoF modulation technique not only minimizes the circulating current, but also eliminates the switching loss. Keeping the minimum phase shift between the primary and secondary bridges reduces the circulating current, and thus, all switches can be operated with zero-voltage switching (ZVS) for the entire power range. The power is controlled by changing the switching frequency from 45 to 63 kHz. To confirm the proposed topology and modulation scheme, a 1500 W DABSRC, which interfaces a 300 V DC bus with a 75 V DC bus, is simulated. A loss model of the proposed topology is also made to verify the results. The simulation results are used to confirm the proper operation of the 3P-DABSRC.

A novel bi‐directional high‐gain DC‐DC converter with optimum number of components

AbstractMost emerging applications of battery energy storage systems, fuel cells, and unified power supply (UPS) applications require essential bi‐directional power capability with a high conversion ratio. It supports the integration of the high‐voltage DC‐bus with an energy storage unit or fuel cell. In order to meet this requirement, this paper proposes a novel nonisolated high‐gain DC‐DC converter with bi‐directional power flow capability. This converter is configured with a hybrid structure with a combination of the switched capacitor (SC) and switched inductor (SI) techniques. Moreover, this converter can attain extreme voltage gain with less number of semiconductors and passive components. As a result, the converter cost gets reduced and achieves a wide range of voltage gain at a lesser duty ratio. Furthermore, steady‐state analysis and performance of the proposed topology and its characteristics were presented in this paper. Additionally, a detailed comparative analysis was presented with the most recent literature. Finally, a 500‐W experimental prototype has been fabricated to authorize the performance, feasibility, and analytical waveforms with experimental results.

A Novel Nonisolated GaN-Based Bidirectional DC–DC Converter With High Voltage Gain

A nonisolated bidirectional dc–dc converter is proposed for energy storage systems in this article. The proposed converter is composed of three active switches, two synchronous rectifiers, two clamping capacitors, and two inductors. The proposed converter has advantages of being a simple structure, a fewer number of components, a common ground, lower voltage stress, and wide voltage gain range. Compared with the conventional buck converters, the novel converter triples the effective duty cycle and lowers voltage stresses across the active switches. A 300-W/500-kHz GaN-based experimental prototype is built and tested to verify the correctness and validity, demonstrating a peak efficiency of 94.54% in step-down mode and a peak efficiency of 94.88% in step-up mode.

A Constant-Frequency High-Voltage Gain Resonant Converter Module With Semiactive Phase-Shifted Voltage Multiplier for MVdc Distribution

A constant-frequency step-up LLC resonant converter module that employs a new phase-shifted semiactive voltage multiplier technique is proposed in this article for a medium-voltage dc distribution grid. In the proposed converter, a wide voltage gain for different loading conditions can be realized by adaptively controlling the phase shift of the auxiliary switch in a voltage quadrupler-based semiactive voltage multiplier. Zero-voltage switching turn-on is always achieved for all the primary side switches with a constant-frequency operation. In the proposed semiactive voltage multiplier, zero-current switching (ZCS) turn-on is achieved for the auxiliary switch with ZCS operations provided for all the output diodes over a wide range of voltage gain and loading conditions. The operating principles of the proposed circuit are discussed in this article. Simulation results on a 120-kW, 10-kV output and experimental results on a modular laboratory-scale silicon carbide (SiC)-based 5-kW (per-module), 240–440-V/5-kV prototype are provided to demonstrate the performance of the proposed converter.

A Hybrid Control Strategy for Half-bridge Three-level LLC Resonant Converter

The half-bridge three-level LLC resonant converter uses the resonant process of the inductance and the capacitance to transfer energy. It has the advantages of low voltage stress on the switch and high efficiency, but there are problems such as narrow voltage gain range. To widen the voltage gain range of the converter, a hybrid control strategy for a half-bridge three-level LLC resonant converter is proposed in this paper. The voltage gain of the converter is divided into three gain intervals: low, medium and high. Burst control is used in the low gain interval, phase shift control is adopted in the middle gain interval, and frequency modulation control is adopted in the high gain interval. The experiment results show that the proposed control strategy can realize a wide range of output voltage gain of the converter.

Bidirectional Resonant Converter With Minimized Switching Loss Over Wide Operating Voltage Range

In this article, we propose a bidirectional resonant converter having minimized switching loss in a wide operating voltage range. This converter serves as a pulse-width-modulation (PWM) full-bridge resonant-boost converter in the forward operation and a PWM half-bridge resonant-buck converter in the reverse operation. It can then achieve wide voltage gain range even in the reverse operation. By employing a T-type active voltage doubler, we can attain almost zero voltage switching at the turn-off instants, and so switching loss occurred at all active switches becomes negligible. Moreover, the circuit experiences very little instantaneous reactive current under wide voltage variations. Therefore, the proposed converter can accomplish a wide range of voltage gains in both power flow directions and high efficiency over a wide range of operating voltages. We present circuit operation and steady-state analysis in detail. We built a 3.3-kW/400-V prototype that copes with 250~415 V inputs and tested to demonstrate the superior quality of its circuit design.

An H5-Bridge-Based Laddered $CLLC$ DCX With Variable DC Link for PEV Charging Applications

Plug-in electric vehicles’ charger is preferred to cover an ultrawide battery voltage range with the vehicle-to-grid capability. Conventional bidirectional resonant dc–dc converters suffer from the contradiction among wide voltage gain range, squeezed dc-link voltage span, and narrow switching frequency band. To solve the issue, this article proposes a novel H5-bridge-based bidirectional <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$CLLC$</tex-math></inline-formula> converter. By configuring the switch pattern, the H5-bridge can form the modes of single half-bridge, dual half-bridge, half full-bridge, and dual full-bridge, respectively. Correspondingly, six gain curves can be derived. Combined with the variable dc-link framework, the converter constrains the switching frequency in the vicinity of the resonant frequency with optimal efficiency. The converter achieves an ultrawide battery voltage range with a squeezed dc-link span. A bidirectionally synchronous rectification method is proposed to improve the efficiency further. To verify the proposed concept, a 1-kW rated prototype with a 320–420 V dc link is built and tested. It validates the battery voltage 55–420 V for charging and 230–420 V for discharging. Zero-voltage turn- <sc xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">on</small> and zero-current turn- <sc xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">off</small> are achieved in the rectifying <sc xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">mosfet</small> s. The prototype exhibits 98.04% peak efficiency and good overall efficiency performance.