New negative output wide voltage gain range boost DC–DC converter for fuel cell vehicles

This paper presents a new step up LLC resonant converter with re-structural feature that employs a novel pulse-width modulated (PWM) voltage multiplier. The proposed converter consists of a reconfigurable full-bridge to half-bridge inverter with fixed switching frequency at the input-side and a new PWM-controlled voltage multiplier rectifier at the output side. Wide voltage gain for different loading condition can be realized by adaptively changing the configuration at the input and controlling the duty ratio of the voltage multiplier in the output, with constant switching frequency. As a result, the circulating energy, and hence, the conduction losses of the LLC resonant tank are reduced. Zero voltage switching for all silicon carbide (SiC) switches and zero current switching for all the diodes are achieved for a wide range of voltage gain and loading conditions. Simulation and experimental results are provided on a laboratory scale 5kV, 4kW proof of concept prototype.

Bi-directional DC-DC converters (BDC) are required for power flow regulation between storage devices and DC buses in renewable energy based distributed generation systems. The fundamental requirements of the BDC are simple structure, reduced switching components, a wide range of voltage gain, low voltage stress, high efficiency, and reduced size. There are different BDC topologies for various applications based on their requirements in the literature. Various BDC are categorized according to their impedance networks. Isolated BDC converters are large due to high-frequency transformers and hence used for static energy storage applications whereas non-isolated BDC is lightweight and suitable for dynamic applications like electric vehicles. This paper reviews types of non-isolated BDC topologies. The performance of five non-isolated BDC converters under steady state condition is evaluated by using theoretical analysis. On this basis, suitability of BDC for different applications is discussed. Further advantages and limitations of converters are discussed by using comparative analysis. The optimization of BDC for distributed generation systems from the perspectives of wide voltage gain, low electromagnetic interference, low cost with higher efficiency is identified. Theoretical analysis of the converters is validated by simulating 200W converters in MATLAB Simulink.

LLC converters are attractive with their ability of enable to achieve soft switching, but there is a trade-off between voltage gain and efficiency in wide voltage regulation range applications. In this paper, a novel hybrid LLC and full-bridge (FB) converter is proposed for wide voltage gain applications. The converter consists of a half bridge (HB) LLC resonant converter and a switch-off current-clamp FB converter connected in parallel. The turn-off current of the LLC converter over the entire range is significantly reduced through the clamping operation of the FB converter. Consequently, all primary-side switches of LLC converter achieve zero-voltage switching-on (ZVS) and low-current switching-off (LCS), while secondary-side diodes achieve zero-current switching-off (ZCS), leading to a substantial reduction in switching losses. Furthermore, a smooth transition variable-frequency plus phase-shift control strategy is proposed to achieve wide-range of voltage regulation. The proposed control has three operation modes: variable-frequency with a shift angle <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\varphi $ </tex-math></inline-formula> is 0 mode, phase-shift mode, and variable-frequency with <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\varphi $ </tex-math></inline-formula> of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\pi $ </tex-math></inline-formula>. These modes cover the low, medium, and high voltage gain ranges, respectively. A 7.5 kW-rated experimental prototype is designed to convert a 400 V input to a 150-750 V wide output. The prototype demonstrates a peak efficiency of 98.04% and maintains an efficiency of over 93.8% from 30% load to full load across the 150-750 V output range.

This work has adopted the concept of asymmetric inductor magnetization to develop a new quadratic converter with the advantages like a wide range quadratic voltage gain and low source current ripple. In addition, the proposed high quadratic converter has achieved reduced voltage stress due to the presence of switched capacitor cell at the output side. Initially, the operation of the converter and steady-state analysis, including efficiency calculations, are explained. In addition, the design and selection of converter components are presented along with a small-signal analysis. Further, a comprehensive comparison with recent high quadratic gain converters is presented. The comparison is made with regard to the total component count, voltage conversion ratio, effectiveness index, electric stress, current ripple, switching device power (SDP) rating, and input current ripple factor. Furthermore, the 150 W laboratory prototype is used to verify the performance of the proposed converter in terms of operation, dynamic response, and efficiency, and the corresponding experimental findings are reported. The wide range voltage gain, low current ripple, and low electric stress features of the proposed converter highlight its superiority in fuel cell electric vehicle applications.

The LLC resonant converter, as an isolated DC-DC conversion topology, has been widely adopted in industrial applications. However, when operating under wide input/output voltage ranges, a broad switching frequency range is required to achieve the desired voltage gain. This wide frequency variation complicates the design of magnetic components, causes loss of soft-switching characteristics, and deteriorates electromagnetic interference (EMI) performance. To address these challenges, this paper presents a detailed analysis of the L-LCLC resonant converter. By controlling the connection/disconnection of additional inductors and capacitors through switching devices, the topology achieves structural reconfiguration to enhance the voltage gain range. Optimal mode transition points are selected to ensure stable operation during mode transitions, thereby reducing design complexity, minimizing transition losses, and suppressing voltage/current stress. The parameter design methodology for the additional reactive components is systematically developed. The converter’s performance is validated with Simulink, and the experimental prototype is established with 100 W. Both simulation and experimental results confirm that the L-LCLC resonant converter achieves a wide voltage gain range within a narrow frequency band while maintaining stable mode transitions.

Wide range operation dc/dc converters are required in renewable energy system applications. For example, for photovoltaic (PV) system, the output voltage of the PV ranges from 20 V to 60 V, which requires a dc/dc converter has a wide voltage gain range of 3. LLC resonant converters are popular due to their high efficiency characteristic. However, when traditional LLC converters are adopted in wide voltage range applications, the converter efficiency and power density performances are degraded due to the wide switching frequency operating range. In this article, a novel LLC topology, which has different operation modes, is proposed for renewable energy system applications, is proposed to satisfy the voltage gain requirement. By operating the proposed converter in three different operation modes, namely dual full-bridge, single full-bridge, and single half-bridge, the system normalized voltage gain can be varied from double to half. The operational principles, design considerations, and experimental validations are presented in this paper.

In this article, we propose a current-fed bidirectional resonant converter that has minimal switching loss over a wide voltage gain range. The proposed bidirectional resonant converter employs a double current-fed structure at the low-voltage side and an active voltage doubler with a bidirectional switch at the high-voltage side.The converter operates as a pulsewidth-modulation (PWM) double current-fed resonant converter in the forward mode and a PWM half-bridge resonant converter in the backward mode. By incorporating a bidirectional switch across center nodes of the active voltage doubler, the converter achieves almost zero-voltage switching at the turn-off instant, thereby, incurring little switching loss at all active switches. The proposed topology exhibits a high conversion ratio with low transformer turns-ratio and a low current ripple at the low-voltage side. The operating principles and theoretical derivations of the converter are discussed in detail. The performance of the proposed bidirectional converter are verified using a prototype that has 48-72-V low voltage, 380-V high voltage, and 1-kW output power.

Design options for implementing in standard CMOS drivers for MEMS body biasing

Full-bridge resonant converters have gained widespread adoption due to their excellent performance characteristics. However, these converters face limitations in terms of gain expansion. To address this issue, this paper proposes a switch-multiplexed resonant converter with wide voltage gain. By employing an auxiliary capacitor and inductor, the converter can achieve pseudo partial power processing and effectively expand its voltage gain. To regulate the voltage of the converter, the duty cycle of the switching devices is designed to be modulated, which is different from the conventional resonant converter. By optimizing the design parameters, the resonant current of converter can operate in discontinuous current mode (DCM), eliminating reverse recovery losses and/or minimizing reactive current. All switching devices achieve soft switching, thereby removing switching losses and further enhancing efficiency. Finally, a 1 kW prototype is built to validate the effectiveness of the proposed converter.

In order to match voltages between the fuel cell stacks and the DC link bus of fuel cell vehicles, a single-switch Boost dc–dc converter with diode-capacitor modules is proposed in this paper. The capacitors are charged in parallel and discharged in series. The wide voltage-gain range can be obtained by using a simple structure. In addition, the basic operating principles, the extended stages, the fault tolerant operation, and steady-state characteristics of the converter are analyzed and presented in this paper, and the small-signal model is also derived. A 400 V, 1.6 kW experimental prototype is developed, and the wide voltage-gain range (3.3 ∼ 8) is demonstrated with a maximum efficiency at 97.25%. The experimental results validate the effectiveness and feasibility of the proposed converter and its suitability as a power interface for fuel cell vehicles.

Designing ideal analogue circuits has become difficult due to extremely large-scale integration. The complementary metal oxide semiconductor (CMOS) analog integrated circuits (IC) could use an evolutionary method to figure out the size of each device. The CMOS operational transconductance amplifier (CMOS OTA) and the CMOS current conveyor second generation (CMOS CCII) are designed using advanced nanometer transistor technology (180 nm). Both CMOS OTA and CMOS CCII have high performance, such as a wide frequency, voltage gain, slew rate, and phase margin, to include very wide applications in signal processing, such as active filters and oscillators. The optimization approach is an iterative procedure that uses an optimization algorithm to change design variables until the optimal solution is identified. In this study, different sorts of algorithms the genetic algorithm (GA), particle swarm optimization (PSO), and cuckoo search (CS) are employed to boost and enhance the performance parameters. While decreasing the time required to develop a conventional operation amplifier's settling time. Some studies decrease the value of the power utilized at various frequencies. Others operate at extremely high frequencies, but their power consumption is greater than that of those operating at lower frequencies.

In order to break limited step-down ratio range and poor regulation capacity in the conventional resonant switched-capacitor converters for rectifier application, a single-stage ac/dc rectifier based on the dual-resonance switched-capacitor converter is proposed in this article. Through utilizing a dual-resonant structure and nonoverlapping strategy to realize wide continuous voltage gain of the proposed converter, high power factor (PF) and low total harmonic distortion (THD) based on the narrow dead zone are guaranteed by operating at high step-down conversion ratio in this converter topology. Moreover, the voltage gain is concentrated between resonant frequency and double resonant frequency to achieve a narrow switching frequency range for rectifier application. Furthermore, operating at flat voltage stress curves to obtain low voltage stress character. Comprehensive mode analysis, input PF and THD, and stress analysis are given, and analysis results indicate that the proposed power factor correction converter can work with soft 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> ; high efficiency is realized. Finally, an experimental prototype with 85–130 V <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">ac</sub> input and 47 V <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">dc</sub> /44 W output is built and tested for verifying the operation modes and PFC performance, and the comparison between different rectifiers and the proposed one is provided.

Series resonant converter can only operate efficiently within a narrow voltage gain range, which limits the use for battery charging applications. Thus, this article proposes a turn-off delay-controlled bidirectional series resonant (TFD-BSR) converter to extend the voltage gain range and enhance the efficiency. Instead of frequency modulation, the turn-off delay of the corresponding bottom switches is adopted to regulate the direction and amplitude of power flow. First, high peak and low valley voltage gain is obtained at fixed switching frequency. As a result, wide voltage range is extended. Second, the voltage gain is independent of auxiliary and magnetizing inductors, and hence, a large value for the two inductors, which depresses the circulating losses significantly, can be designed just considering zero-voltage switching (ZVS) conditions. In addition, all the active switches can operate with ZVS, which further enhances the efficiency. Operation principles, voltage gain characteristics, ZVS analysis, and design method of the proposed TFD-BSR converter are analyzed in detail. Finally, the feasibility and performance of the proposed converter are validated by simulations and experimental results from a 3.5-kW prototype.

To improve the efficiency of a dual-active-bridge resonant converter, a new control strategy based on three phase-shifts modulation is proposed in this paper. It is assumed that the converter is used for an application with a wide variation of voltage gain. The steady-state analysis of the DBSRC with three phase-shifts is performed by means of the fundamental harmonics approximation. With the help of fundamental phasor diagram, the new control strategy is presented to reduce the circulation current on the low-voltage side. It is shown that the dual-active-bridge resonant converter has nearly zero circulation current in a wide variation range of both voltage gain and load level. The feasibility of the control strategy is exemplified by a design of a lab prototype. Verifications of the analysis and design through both simulation and experimental test are included at last.

A soft-switching DC-DC converter with secondary-side phase-shift control strategy is proposed for applications requiring wide voltage range and isolated step-down power conversion such as battery charger. Two transformers and a three-leg hybrid rectifier (one MOSFET-leg and two diode-legs) are employed. The primary windings of the two transformers are in-series and the secondary windings are in parallel. Zero voltage switching is achieved for both the primary- and secondary-side power MOSFETs while zero current switching is achieved for the secondary-side diodes in a wide load range. Leakage inductance of the transformers is utilized for power transferring. The voltage stresses of all the devices are clamped automatically. Besides, the converter can operates in the buck, balance and boost modes to achieve a relatively wide input or output voltage range. The secondary-side rectifier can be extended to multiple transformers configuration for high step-down applications. The operation principles are analyzed and experimental results of a 1-kW 100-kHz prototype are provided to verify the effectiveness of the proposed converter.