Step-up Voltage Research Articles

High step‐up interleaved converter with soft‐switching using a single auxiliary switch for a fuel cell system

This study aims to develop a soft-switching interleaved converter with a high-voltage conversion ratio using a single auxiliary switch. As a step-up voltage converter, it performs zero voltage switching and zero current switching operations on main switches by means of the manipulation of the single auxiliary switch. In this manner, both the switching loss and switching stress of main switches can be reduced, giving rise to an improvement in the conversion efficiency. Placed in parallel with a converter available, merely a single resonant branch is employed in the proposed soft-switching mechanism, a simple and elegant way to reach the goal. This proposal is further applied to a fuel cell system as a high performance DC voltage booster so as to drive a high-voltage DC load. PSIM simulations are conducted and subsequent experimental validation is presented at the end of this work.

Generalised transformerless ultra step‐up DC–DC converter with reduced voltage stress on semiconductors

A non-isolated DC–DC converter with high-voltage gain and low-voltage stress across the semiconductors is proposed in this study. The proposed converter consists of n stages of diode–capacitor–inductor (D–C–L) units at the input side and m units of voltage multiplier cells (VMCs) at the output side. Increasing of D–C–L units and VMCs, lead to high-voltage gain at low duty cycle. Lower values of duty cycle will result in increasing of converter controllability and increasing of operation region. Also by increasing of VMCs, the voltage stress across the main switch and other semiconductors is reduced severely. Decreasing of voltage stress across the main switch leads to use a switch with lower R DS-ON that reduces on state losses of the proposed converter. Besides, by decreasing of voltage stress across the diode rectifiers, diodes with less forward voltage drop can be adopted. The circuit performance will be compared with other solutions that were previously proposed for voltage step-up in the terms of voltage gain, main switch voltage stress and number of components. Finally, a 357 V–65.5 W laboratory prototype with 92% conversion efficiency is built in order to prove the satisfying operation of the proposed converter and carried mathematical analysis.

High step-up converters based on quadratic boost converter for micro-inverter

This paper proposes two DC–DC converters namely semi-tapped and fully-tapped quadratic boost converter based on the quadratic boost converter topology for high step-up applications such as micro-inverter. The proposed converters integrate the step-up capabilities of the quadratic boost converter and the tapped-inductor based converter due to which high step-up voltage gain can be achieved at lower duty ratio. Further, the proposed converters also have feature of low voltage stress on active switch. This paper presents detailed steady state analysis of proposed converters which include voltage gain and efficiency analysis with the presence of parasitic components. The theoretical analysis of proposed converters is verified by simulation and experimental results.

English

Now-a-days due to the shortage of electric power and rising cost of non-renewable energy resources generating electric power from the renewable energy resources such as PV modules are increasing day to day. This paper presents non-isolated, high step-up dc-dc converter with hybrid transformer with for low voltage renewable energy resources applications. The proposed converter utilizes hybrid transformer to transfer the inductive and capacitive energy simultaneously, achieving high step-up voltage with smaller sized magnetic component, the turn-off loss of switch is minimized, increasing the efficiency of the converter under all load conditions. By changing the input voltage the voltage stresses on the active switch and diodes are maintained at low level and are independent as a result of the resonant capacitor transferring energy to the output of the converter. Due to high system efficiency as well as ability to operate with a wide variable input voltage, the proposed dc-dc converter is an attractive design for alternative low dc voltage energy sources, such as solar PV modules and fuel cells.

A Novel Transformer-less Adaptable Voltage Quadrupler DC Converter with Low Switch Voltage Stress

In this paper, a novel transformer-less adjustable voltage quadrupler dc-dc converter with high-voltage transfer gain and reduced semiconductor voltage stress is proposed. The proposed topology utilizes input-parallel output-series configuration for providing a much higher voltage gain without adopting an extreme large duty cycle. The proposed converter cannot only achieve high step-up voltage gain with reduced component count but also reduce the voltage stress of both active switches and diodes. This will allow one to choose lower voltage rating MOSFETs and diodes to reduce both switching and conduction losses. In addition, due to the charge balance of the blocking capacitor, the converter features automatic uniform current sharing characteristic of the two interleaved phases for voltage boosting mode without adding extra circuitry or complex control methods. The operation principle and steady analysis as well as a comparison with other recent existing high step-up topologies are presented. Finally, some simulation and experimental results are also presented to demonstrate the effectiveness of the proposed converter.

Comparison Criteria for Electric Traction System Using Z-Source/Quasi Z-Source Inverter and Conventional Architectures

This paper deals with objective criteria to compare conventional electric traction systems composed of a dc-dc boost converter, a voltage source inverter, and a permanent magnet synchronous machine with alternative topologies such as Z-source inverter (ZSI) or quasi Z-source inverter (QZSI). Rather focusing only on efficiencies issues, this paper deals with other relevant criteria. The stored energy in the systems is for instance linked with their passive elements weight, size, or cost. The currents rms values and the stepup voltage ratio are also considered. A complete losses evaluation is given and validated by both simulation and experimental results. The results show that the QZSI exhibits real advantages in terms of passive elements size since the stored energy during one operating cycle is lower than that for the conventional topologies.

RF Energy Harvesting and Charging Circuits for Low Power Mobile Devices

Low power RF devices, such as RFID and Zigbee, are important for ubiquitous sensing. These devices, however, are powered by portable energy sources, such as batteries, which limits their use. To mitigate this problem, this study developed RF energy harvesting with W-CDMA for a low power RF device. Diodes are required with a low turn on voltage because the diode threshold is larger than the received peak voltage of the rectifying antenna (rectenna). Therefore, a Schottky diode HSMS-286 was used. A prototype of RF energy harvesting device showed the maximum gain of 5.8dBi for the W-CDMA signal. The 16 patch antennas were manufactured with a 10 dielectric constant PTFT board. In low power RF devices, the transmitter requires a step-up voltage of 2.5~5V with up to 35 mA. To meet this requirement, the Texas Instruments TPS61220 was used as a low input voltage step-up converter. From the evaluated result, the achievable incident power of the rectenna at 926mV to operate Zigbee can be obtained within a distance of 12m.

English

Now-a-days the new family of dc-dc converters based on three state switching cell and voltage multiplier cells. It present a demonstrate of some advantages and limitations of a several topologies were typically use in voltage step-up applications. The operating principle of this family has chosen the boost converter and discussed in detail. The analysis of converter can applicable in uninterruptible power supplies, fuel cell systems and it is adequate in operating the high-gain boost stage with cascaded inverters in the renewable energy systems. Furthermore, It is applicable in dc voltage step-up is demanded, like electrical fork-lift, audio amplifiers, and some other applications.

Isolated Coupled-Inductor-Integrated DC–DC Converter With Nondissipative Snubber for Solar Energy Applications

This paper proposes an isolated coupled-inductor-integrated dc–dc converter with a nondissipative snubber for solar energy applications. The proposed converter realizes high step-up voltage gain without incurring a high coupled inductor turns ratio by adapting a dual-voltage doubler circuit. In addition, the energy in the coupled inductor leakage inductance can be recycled via a nondissipative snubber on the primary side. Thus, the system efficiency is improved. Finally, a laboratory prototype for demonstrating the performance of the proposed circuit is implemented with a 200-W solar array simulator, a 24-V solar voltage, and a 200-V output voltage. The experimental results show that the peak efficiency of the proposed converter is about 96%.

High step-up isolated efficient single switch DC-DC converter for renewable energy source

In this paper, an isolated high step-up single switch DC-DC converter for renewable energy source is proposed. In the proposed converter high step-up voltage is obtained by single power switching technique that operates low duty cycle with isolated transformer inductors and switched capacitors and power diodes. The disadvantage of conventional converters is that it has high duty ratio and high voltage stress on power devices with less efficiency. The proposed converter eliminates the switching losses and recycles the leakage energy which includes reverse recovery energy of the power diode by using passive clamp circuit. To achieve high output voltage gain, the isolated transformer primary terminal and secondary terminal are connected in series during switching operation. PSIM software has been used for simulation. Simulation circuit is analyzed at 40Vdc/400Vdc, 200W and this operation is validated by implementing in the hardware model at 12Vdc/120Vdc, 60W.

A Switched-Capacitor-Based Active-Network Converter With High Voltage Gain

The voltage gain of traditional boost converter is limited due to the high current ripple, high voltage stress across active switch and diode, and low efficiency associated with large duty ratio operation. High voltage gain is required in applications, such as the renewable energy power systems with low input voltage. A high step-up voltage gain active-network converter with switched-capacitor technique is proposed in this paper. The proposed converter can achieve high voltage gain without extremely high duty ratio. In addition, the voltage stress of the active switches and output diodes is low. Therefore, low voltage components can be adopted to reduce the conduction loss and cost. The operating principle and steady-state analysis are discussed in detail. A prototype with 20-40-V input voltage, 200-V output voltage, and 200-W output power has been established in the laboratory. Experimental results are given to verify the analysis and advantages of the proposed converter.

Analysis of voltage and current stresses of a generalised step‐up DC–DC converter

A non-isolated DC–DC converter with high-voltage gain and low-voltage stress on switches is proposed in this study. For absorption of energy n stages of diode–capacitor–inductor (D–C–L) units are used at the input that results in higher voltage gains. Actually, the proposed converter generalises the voltage lift circuit and combines it with a voltage multiplier cell. Therefore comparing to structures with one stage of D–C–L unit, it will be feasible to achieve supposed voltage gain at lower duty cycles. Lower values of duty cycle will result in increasing of converter controllability and increasing of operation region. The generalised analysis of the voltage and current stresses of the semiconductors and power components is carried out. The circuit performance will be compared with other solutions that were previously proposed for voltage step-up in the terms of voltage gain, switch and output diode voltage stress and number of components. The carried mathematical analysis and circuit performance are validated through both simulation and experimental results that match each other reasonably well.

High boost ratio DC–DC converter with ripple‐free input current

A high boost ratio non-isolated converter with a ripple-free input current is proposed, which combines a zero-ripple boost cell and a coupled inductor to achieve a high output voltage step-up. A passive snubber is utilised to suppress voltage spike of the switch caused by the resonance of the leakage inductance of the coupled inductor and the parasitic capacitance of the switch. Therefore, a low-voltage-rated metal oxide semiconductor field effect transistor (MOSFET) with low rDS(ON) can be used to improve the efficiency of the converter. In addition, a ripple-free input current can be achieved, making the electromagnetic interference (EMI) filter simple. Experimental results of a 100 W (40 V/200 V) prototype are presented to verify the analysis results of the proposed converter.

Digital Control of a Bidirectional DC/DC Switched Capacitor Converter for Hybrid Electric Vehicle Energy Storage System Applications

This paper presents the analysis and novel controller design for a hybrid switched-capacitor (SC) bidirectional DC/DC converter, applicable for electric and plug-in hybrid electric vehicles (HEV/PHEV) energy storage system (ESS) applications, based on power of traction motor and battery current gradient. Features of voltage step-down, voltage step-up, and bi-directional power flow are integrated into a single circuit. The developed novel control strategy enables simpler dynamics compared to a standard buck converter with input filter. Experimental results show, the proposed converter topology enables good regulation capability, low EMI, lower source current ripple, ease of control, and continuous input current waveform in both buck as well as boost modes of operation.

High-Conversion-Ratio Bidirectional DC–DC Converter With Coupled Inductor

In this paper, a high-conversion-ratio bidirectional dc-dc converter with coupled inductor is proposed. In the boost mode, two capacitors are parallel charged and series discharged by the coupled inductor. Thus, high step-up voltage gain can be achieved with an appropriate duty ratio. The voltage stress on the main switch is reduced by a passive clamp circuit. Therefore, the low resistance RDS(ON) of the main switch can be adopted to reduce conduction loss. In the buck mode, two capacitors are series charged and parallel discharged by the coupled inductor. The bidirectional converter can have high step-down gain. Aside from that, all of the switches achieve zero voltage-switching turn-on, and the switching loss can be improved. Due to two active clamp circuits, the energy of the leakage inductor of the coupled inductor is recycled. The efficiency can be further improved. The operating principle and the steady-state analyses of the voltage gain are discussed. Finally, a 24-V-input-voltage, 400-V-output-voltage, and 200-W-output-power prototype circuit is implemented in the laboratory to verify the performance.

Autonomous Wireless Sensor with a Low Cost TEG for Application in Automobile Vehicles

Abstract The present work consists in the development of an autonomous, low cost, reliable, energy scavenger sensor for automotive applications. Thermoelectric generators typically exhibit low efficiency but high reliability, making them suitable for autonomous, low average energy consumption, applications. A prototype sensor was developed for mounting in the engine exhaust pipe using a step-up voltage converter, a microcontroller, temperature and pressure sensing elements, conditioning electronics and a wireless transceiver, all powered by a low cost TEG (Peltier module TEC1-12706), through the scavenging of exhaust gases thermal energy. During the tests the prototype was able to sustain a regular signal transmission throughout the engine operation. The sensor was installed directly at the measuring point eliminating wired cables to hot and vibrating parts, thus, simplifying the installation of components and improving the reliability of the vehicle systems.

Development of Serial-Connected High Step-Up DC-DC Converter with Single Switch

In this paper, a novel high step-up DC-DC converter has been designed for fuel cell applications. The proposed high step-up converter can be used for various portable energy storage components such as fuel cells which are used for hybrid electric vehicles (HEV), and light electric vehicles (LEV).The proposed converter is integrated by boost circuit, voltage lift capacitor, and coupled-inductor techniques to achieve high step-up voltage and has several advantages. First, the circuit is controlled by one single pulse width modulation (PWM). Second, the converter consists of active clamp circuit to recycle the leakage inductance and send to output capacitor so that the voltage spike on active switch is suppressed and efficiency is also improved. Third, by using the winding of secondary boost circuit, and voltage lift capacitor techniques, the high voltage gain can be achieved without more than 50% duty ratio, and the slope compensation circuit can also be simplified.Finally, a 1k W prototype converter is implemented, to verify the performance of the proposed converter with input voltage 48V, output voltage 400V, and output power 1k W is also achieved. The highest efficiency is 92.96% at 400W, and the full-load efficiency is up to 90.48%.

A High Step-Up Three-Port DC–DC Converter for Stand-Alone PV/Battery Power Systems

A three-port dc-dc converter integrating photovoltaic (PV) and battery power for high step-up applications is proposed in this paper. The topology includes five power switches, two coupled inductors, and two active-clamp circuits. The coupled inductors are used to achieve high step-up voltage gain and to reduce the voltage stress of input side switches. Two sets of active-clamp circuits are used to recycle the energy stored in the leakage inductors and to improve the system efficiency. The operation mode does not need to be changed when a transition between charging and discharging occurs. Moreover, tracking maximum power point of the PV source and regulating the output voltage can be operated simultaneously during charging/discharging transitions. As long as the sun irradiation level is not too low, the maximum power point tracking (MPPT) algorithm will be disabled only when the battery charging voltage is too high. Therefore, the control scheme of the proposed converter provides maximum utilization of PV power most of the time. As a result, the proposed converter has merits of high boosting level, reduced number of devices, and simple control strategy. Experimental results of a 200-W laboratory prototype are presented to verify the performance of the proposed three-port converter.

A long-lasting wireless stimulator for small mammals

The chronic effects of electrical stimulation in unrestrained awake rodents are best studied with a wireless neural stimulator that can operate unsupervised for several weeks or more. A robust, inexpensive, easily built, cranially implantable stimulator was developed to explore the restorative effects of brainstem stimulation after neurotrauma. Its connectorless electrodes directly protrude from a cuboid epoxy capsule containing all circuitry and power sources. This physical arrangement prevents fluid leaks or wire breakage and also simplifies and speeds implantation. Constant-current pulses of high compliance (34 volts) are delivered from a step-up voltage regulator under microprocessor control. A slowly pulsed magnetic field controls activation state and stimulation parameters. Program status is signaled to a remote reader by interval-modulated infrared pulses. Capsule size is limited by the two batteries. Silver oxide batteries rated at 8 mA-h were used routinely in 8 mm wide, 15 mm long and 4 mm high capsules. Devices of smaller contact area (5 by 12 mm) but taller (6 mm) were created for mice. Microstimulation of the rat's raphe nuclei with intermittent 5-min (50% duty cycle) trains of 30 μA, 1 ms pulses at 8 or 24 Hz frequency during 12 daylight hours lasted 21.1 days ±0.8 (mean ± standard error, Kaplan-Meir censored estimate, n = 128). Extended lifetimes (>6 weeks, no failures, n = 16) were achieved with larger batteries (44 mA-h) in longer (18 mm), taller (6 mm) capsules. The circuit and electrode design are versatile; simple modifications allowed durable constant-voltage stimulation of the rat's sciatic nerve through a cylindrical cathode from a subcutaneous pelvic capsule. Devices with these general features can address in small mammals many of the biological and technical questions arising neurosurgically with prolonged peripheral or deep brain stimulation.

Switching regulator using a high step‐up voltage converter for fuel‐cell modules

A typical fuel-cell stack produces a low DC voltage with wide variations; therefore a DC–DC switching converter is required to step up and regulate the output voltage. In this work, a model based on electrical variables is developed for a fuel-cell stack. This model is later combined with the model of a high step-up voltage converter to obtain a combined model that incorporates the behaviour of fuel-cell stack. The resulting model is then used to design an average-current mode controller for a switching regulator. To test the proposed regulator, a power module with polymer electrolyte membrane fuel cells is used as an input source. This module delivers an output voltage between 26 and 42 V depending on the current being drawn. Experimental results exhibit the robustness of the switching regulator to step changes in the output load and the output voltage of the fuel-cell stack.