Step-up Voltage Conversion Ratio Research Articles

Development of a Thermal Energy Harvesting Converter with Multiple Inputs and an Isolated Output

In this paper, an isolated multi-input single-output (MISO) converter is developed and applied to a thermoelectric energy conversion system to harvest thermal energy. The thermoelectric generators have individual maximum power point tracking functions. Furthermore, such a converter has a high step-up voltage conversion ratio. In addition, the presented converter is imposed on the thermoelectric energy conversion system with the three-point weighting strategy adopted to realize the maximum power point tracking (MPPT). In this paper, the basic principles of this converter are first described and analyzed, and finally some simulated and experimental results are offered to verify the feasibility and effectiveness of such a thermal energy harvesting system.

A Three-Switch-Based Single-Input Dual-Output Converter With Simultaneous Boost & Buck Voltage Conversion

With the increasing demand of applications that have two different output voltages, the single-input dual-output (SIDO) converter with fewer components is becoming the cost-effective option instead of employing two single-input single-output converters. However, the cross-regulation of different outputs is still a challenge in SIDO converters design. To save cost and obtain improved cross-regulation performance, a novel SIDO converter consisting of three active switches is proposed in this article. Owing to the use of a voltage multiplier circuit, a high step-up voltage conversion ratio is achieved with relatively low voltage stress of switches. Thanks to the independent power flow and two control variables, the cross-regulation performance is improved, and simultaneous buck as well as boost output voltages is realized. Additionally, all switches can achieve zero-voltage switching operation, which contributes to a significant switching loss reduction. The operation characteristics, design considerations, and control strategy of the proposed converter are analyzed. To verify the theoretical analysis and measure the power efficiency, a prototype circuit with 48 V input and 24 V/2 A, 200 V/1 A outputs is built.

A High-Efficiency DC/DC Converter for High-Voltage-Gain, High-Current Applications

A new class of high-voltage-gain dc–dc converters for high-efficiency and transformer-less dc–dc applications, where large voltage step-up ratios are required, is presented in this paper. The converter is derived from the hybrid integration of a switched-capacitor converter and a boost converter. It features high step-up voltage conversion ratio with a moderate duty cycle, nonpulsating input current, low-voltage stress on all of the switches, easy implementation of control and driving circuits, scalability for high-current high-power applications, and low cost due to reduced components via combination of a two-stage converter into a single-stage converter. Full soft-charging operation and minimal device voltage stresses are achieved under all operating conditions. Steady-state operations of the converter are comprehensively analyzed. A 300-W prototype of a 19-time converter achieving the peak efficiency of 96.1% is built. Both simulation and experimental results validating the theoretical analysis and operation of the converter are provided.

An Ultrahigh Step-Up Nonisolated Interleaved Converter With Low Input Current Ripple

In this paper, a new topology to achieve ultrahigh step-up voltage conversion ratio and very low input current ripple is introduced for nonisolated high-power applications by using interleaved structure combined with coupled inductors (CIs) and switched capacitors. Using voltage lift capacitors in this topology not only recycles the energy related to leakage inductance of CIs and alleviates the voltage spike across the power switches but also increases the voltage gain of the converter. Moreover, utilizing CI structure provides zero-current switching (ZCS) turn-on condition for power switches and reducing the diodes reverses recovery losses and also improves the voltage gain of the converter. Using the interleaved structure in the low-voltage side noticeably decreases the input current ripple and current stress through magnetic elements. In addition, utilizing the voltage multiplier cell structure in the high-voltage side provides a high-voltage gain. The voltage stress across the power switches is considerably lower than the output voltage. Hence, the low-voltage-rated switches can be employed. Based on the mentioned advantages, the efficiency of this implementation is improved significantly. Finally, to validate the performance of the proposed converter, a 600-W, 24-V/520-V prototype circuit is implemented.

A Novel High Step-up DC-DC Converter for Photovoltaic Applications

This paper proposes a new topology of a high step-up dc-dc converter for photovoltaic system applications. The proposed converter can boost up the low input voltage, about 20 V, generated from the PV array to the high output voltage level of approximately 400 V. The proposed converter employs only one power switch to achieve a high step-up voltage conversion ratio, approximately 20 times, without the extremely large duty cycle. The operating principles and steady-stage analyses of continuous conduction mode are described in detail. The relationship between the step-up voltage ratio and the duty cycle of the proposed converter is analyzed. The simulation and experimental results are shown to demonstrate the effectiveness of the proposed high step-up single-switch dc-dc converter for low-input and high-output voltage systems.

Multicell Switched-Inductor/Switched-Capacitor Combined Active-Network Converters

High step-up voltage gain dc/dc converters are widely used in renewable energy power generation, uninterruptible power system, etc. In order to avoid the influence of leakage inductor in coupled inductors based converters, switched-inductor boost converter (SL-boost), switched-capacitor boost converter (SC-boost) and active-network converter (ANC) have been developed. With the transition in series and parallel connection of the inductors and capacitors, high step-up voltage conversion ratio can be achieved. This paper discusses the characteristics of the switched inductor and switched-capacitor cell; makes some comparisons between the ANC and boost converter. Based on the aforementioned analysis, this paper proposed the multicell switched-inductor/ switched-capacitor combined active network converters (MSL/SC-ANC). The proposed converters combine the advantages of SL/SC unit and active-network structure. Compared with previous high step-up converters, the novel converter provides a higher voltage conversion ratio with a lower voltage/current stress on the power devices, moreover, the structure of proposed SL/SC-ANC is very flexible, which means the quantity of SL and SC cells can be adjusted according to required voltage gain. A 20 times gain prototype is designed as an example to show the design procedure. Theoretical analysis and experimental results are presented to demonstrate the feature of the proposed converter.

Analysis, Design, and Performance Evaluations of an Edge-Resonant Switched Capacitor Cell-Assisted Soft-Switching PWM Boost DC–DC Converter and Its Interleaved Topology

This paper presents a soft-switching pulsewidth modulation (PWM) nonisolated boost dc–dc converter embedding an edge-resonant switched capacitor (ER-SWC) cell and its interleaved circuit topology. The conceptual boost dc–dc converter treated herein can achieve high-frequency zero-current soft-switching turn-on and zero-voltage soft-switching turn-off operations in the active switches and minimization of a reverse recovering current in the freewheeling diode under discontinuous conduction mode partially including critical conduction mode in the input current. Those advantageous properties enable a wide range of soft-switching operations together with a high-voltage step-up conversion ratio with a reduced current stress. Circuit design guideline based on the soft-switching range is introduced; then, a theoretical analysis is carried out for investigating the step-up voltage conversion ratio. For demonstrating the effectiveness of the ER-SWC soft-switching PWM boost dc–dc converter and its newly developed interleaved topology, laboratory prototypes are evaluated in experiments; then, their performances are discussed from a practical point of view.

New zero-voltage switching DC–DC converter for renewable energy conversion systems

This study presents a novel DC–DC converter for renewable energy conversion systems with photovoltaic (PV) solar cell or fuel cell stack input. The proposed converter is based on a boost converter and a voltage-doubler configuration with a coupled inductor to achieve high step-up voltage conversion ratio. An active snubber is adopted to clamp the voltage stress of the active switch and to release the energy stored in leakage and magnetising inductances. Compared to a conventional boost converter, the adopted converter has a wide turn-off period such that a high output voltage can be achieved. Since an asymmetrical pulse-width modulation is adopted to control both active switches, the leakage inductance and output capacitance of the active switch are resonant in the transition interval. Therefore both active switches are turned on at zero-voltage switching to overcome the disadvantages of a conventional boost converter with low circuit efficiency and narrow turn-off period. Finally, experiments conducted on a laboratory prototype rated at 400 W are presented to verify the effectiveness of the adopted converter.

Photovoltaic panel integrated power conditioning system using a high efficiency step-up DC–DC converter

This paper presents a high efficiency photovoltaic (PV) panel integrated power conditioning system (PCS) by proposing a high efficiency step-up DC–DC converter. The suggested PCS consists of a high efficiency DC–DC converter and a single-phase DC–AC inverter. Each PV panel has its own DC–AC converter, performing the maximum power point tracking (MPPT) function and increasing its flexibility and expandability. Moreover, the proposed DC–DC converter converts the low PV panel voltage into a high DC-link voltage with a high step-up voltage conversion ratio. It can reduce the switching power losses, increasing the power conversion efficiency. The performance of the suggested PCS has been verified through a 180 W prototype of the PCS for a 60 Hz/120 V ac power grid. The proposed DC–DC converter achieves a high efficiency of 96.0%. The PCS including the DC–DC converter and DC–AC inverter achieves an efficiency of 93.1% with an almost unity power factor.

Polarity Inversion DC-DC Power Conversion Circuit with High Voltage Step-up Ratio

A novel polarity inversion dc-dc power conversion circuit that features the high input to output step-up voltage conversion ratio characteristics is presented for high voltage DC power supply applications. The proposed circuit features the reduced voltage stresses of the components compared to those of the conventional ones. The operational principles of the proposed circuit are analyzed and comparative features are presented. The simulation results and experimental results are presented to verify the validity of the proposed circuit.

Active-clamp ZVS converter with step-up voltage conversion ratio

This article presents the circuit implementation and design considerations of a zero voltage switching (ZVS) converter with voltage step-up for battery-based applications. An active-clamp circuit including one auxiliary switch and one clamp capacitor is connected in parallel with the main switch to allow resonant behaviour by the output capacitances of switches and transformer leakage inductance during the transition interval. Thus, the ZVS turn-on of switches can be achieved. The switching losses and thermal stresses of the semiconductors are reduced. The circuit configuration, operation principle and design considerations of the converter are discussed in detail. Finally, experiments conducted on a laboratory prototype rated at 200 W are provided to verify the theoretical analysis and the effectiveness of the proposed converter.