Low-voltage Energy Sources Research Articles

Sliding Mode Control of Quadratic Boost Converters Based on Min-Type Control Strategy

The paper deals with the control of a quadratic boost converter supplied by low-voltage energy sources, such as photovoltaic panels, fuel cells, or batteries. The control scheme consists of two control loops. A min-type controller governs the inner loop to force the current state of the nominal model to converge in a neighborhood of the equilibrium state. The external loop processes the output tracking error using an integrator, and it allows reconfiguring the converter’s working point by changing the equilibrium state given in the input to the internal loop. This configuration assures both zero tracking error of the output voltage and robustness against load and input voltage variations and converter parameter uncertainties. The stability of the whole system is investigated using the hybrid system framework. The proposed control technique has been tested experimentally in a suitably developed (low-cost) setup, and the results show the effectiveness of the proposed approach.

Design of double-integral sliding-mode controller for fourth-order double input DC - DC boost converter with a voltage multiplier cell

ABSTRACT A voltage multiplier cell (VMC)-integrated dual-input boost converter (DIBC) with an inductor at the two inputs for dual boost, and working at a duty cycle greater than 0.5 is a requirement for achieving a high voltage gain from low-voltage energy sources. The main focus of this work is to design a suitable control to effectuate the voltage regulation during input voltage and load disturbances, as well as to reduce the start-up transient. The pulse-width-modulation-based double-integral sliding-mode controller was investigated for desirable voltage regulation. Two input inductor current references are incorporated in the controller design to facilitate the decoupling between the interacting loops, which render the design complex with two sliding surfaces for each input inductor current. Also, a comparative analysis with dual-loop proportional-integral control for DIBC with single VMC is presented to highlight the robustness of the proposed controller. A converter model of 200 W is developed, and the controller is carried out using a field-programmable gate array. Under various disturbance scenarios, MATLAB simulation and experimental results clearly showed the satisfactory transient and steady-state output voltage regulation with the proposed controller.

Control and cooling of electronic load based on FET-transistor

The introduction of electronic load for testing high-precision low-voltage sources (solar panels) requires careful review not only of the circuit design, but also thermal and mechanical design. Modern advances in the development of solar cells and other low-voltage energy sources have led to the need to create compact and express systems for testing them, which cannot be implemented on existing solutions. The article considers the principle of creating and calculating the optimal solution for the implementation of electronic load. To achieve this goal, methods of analysis of modern electronic database, calculations of basic physical and electrical parameters and their modeling are used. Based on the considered physical and circuit solutions for the implementation of the electronic load unit, a corresponding electrical circuit was developed. The transistors are controlled by four unipolar operational amplifiers integrated into the LM324 chip. Control of the electronic load unit is implemented by controlling the voltage at the positive feedback terminals, which is further stabilized by the TL431 chip. The device is powered by a source of DC stabilized current of 12 V (provides additional filtering from voltage fluctuations). On the basis of the previously considered physical and circuit solutions for the implementation of the electronic load unit, its cooling and control system was developed. The calculation of the heat balance allows you to choose the right cooling system for stable operation of the system. The control of the electronic load unit is implemented using INA219 and Xicor X9C microcircuits, and a method for their calibration is proposed. These solutions will make it possible to create a universal electronic load solution for researching semiconductor devices and solar cells. Adherence to the indications and principles set out in this article will provide the load with the ability to work at high power, while maintaining good performance and reliability.

Calculation of the electronic loading scheme for testing low voltage sources

Purpose. The introduction of electronic load for testing high-precision low-voltage sources (solar panels) requires careful review not only of the circuit design, but also thermal and mechanical design. The article considers the principle of creating and calculating the optimal solution for the implementation of electronic load. Methodology. To achieve this goal, methods of analysis of modern electronic database, calculations of basic physical and electrical parameters and their modeling are used. Findings. Based on the considered physical and circuit solutions for the implementation of the electronic load unit, a corresponding electrical circuit was developed. The transistors are controlled by four unipolar operational amplifiers integrated into the LM324 chip. Control of the electronic load unit is implemented by controlling the voltage at the positive feedback terminals, which is further stabilized by the TL431 chip. The device is powered by a source of DC stabilized current of 12 V (provides additional filtering from voltage fluctuations). Originality. Modern advances in the development of solar cells and other low-voltage energy sources have led to the need to create compact and express systems for testing them, which cannot be implemented on existing solutions. Practical value. Adherence to the indications and principles set out in this article will provide the load with the ability to work at high power, while maintaining good performance and reliability. The developed scheme allows to create a compass device for express testing of solar panels.

A non-toxic triboelectric nanogenerator for baby care applications

Herein, we report a non-toxic triboelectric nanogenerator for baby care applications.

Dual-source inverter for hybrid PV–FC application

Multi input–multi output Power electronic interface for hybrid energy resources has gathered much of interest. In this paper, a new configuration for cascade connection of two Z-Impedance networks is presented which is able to extract power from two separate low voltage energy sources such as photovoltaic panels and fuel cell stacks. The required load power can be shared between two sources which may have different low values. The power sharing is controlled by adjusting the shoot through duration and time shifting. The proposed converter includes the features of conventional Z-source converter such as voltage boost and shoot through immunity of the inverter. Steady state operation principles, switching methods and the main relations for power flow from two inputs to the output are derived. A prototype of the converter is built and tested for different operation modes. The results are compared with simulations and theoretical analysis which verify well performance of the system.

An Integrated Interleaved Ultrahigh Step-Up DC–DC Converter Using Dual Cross-Coupled Inductors With Built-In Input Current Balancing for Electric Vehicles

An integrated interleaved dc–dc converter with ultrahigh voltage gain and reduced voltage stress based on the coupled-inductors and switched-capacitor circuits is proposed in this article, which is suitable for interfacing the low-voltage energy sources, such as fuel-cell, with a high-voltage dc bus in electric vehicle applications. Input-parallel connection of the coupled-inductors offers a reduced input current ripple and the current rating of components, as well as automatic input current sharing without a dedicated current sharing controller. A promising power-density improvement technique is given, in which only one magnetic core is utilized to implement two coupled-inductors that can provide the filter functionality, as well as transformer behavior. For suppressing the voltage ringing resulting from the leakage inductors, the active-clamp configuration is employed that can facilitate the soft-switching performance for all switches in a wide range of output power. A voltage multiplier stage is adapted to not only boost the voltage gain but help alleviate the reverse-recovery problem of diodes. The steady-state performance, theoretical analysis, and a comparison with the state-of-the-art converters are given in this article. Finally, the experimental results of a 1-kW, 100-kHz prototype are provided to confirm the validity of the proposed concept.

Soft-Switched Interleaved DC/DC Converter as Front-End of Multi-Inverter Structure for Micro Grid Applications

An isolated four channel dc/dc converter with zero voltage switching is proposed as the front-end of multiple inverter structures to integrate renewable and other low voltage energy sources to micro grids. The interleaving technique is adopted to connect each module of proposed converter to a common dc source. This dc source can be a fuel cell stack, PV panels, battery, or any other low voltage dc source. All four channels are interleaved and a phase shift of 90° is provided between the gate signals of each channels, which reduces the input current ripple. The output port of the proposed converter provide four isolated and regulated dc voltages. These isolated dc sources can be connected in series or parallel or series-parallel manner to obtain required dc-link voltage of various inverter structure. Issues like capacitor voltage balancing of diode clamped multilevel inverters can overcome through the proposed converter. By incorporating a coupled inductor for isolation and energy storage along with voltage multiplier circuit, the proposed converter can achieve higher voltage step up with lower turns ratio and lower voltage stress at moderate duty ratio. Hence, mosfets of low voltage rating (low R <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">DS</sub> (ON)) can be utilized to reduce conduction loss. A 2 kW prototype of the proposed interleaved dc/dc converter is developed and tested with diode clamped three-level inverter, five-level inverter, and three-phase two-level inverter to verify the design.

A Family of Dual-Buck Inverters With an Extended Low-Voltage DC-Input Port for Efficiency Improvement Based on Dual-Input Pulsating Voltage-Source Cells

A systematic method to derive the topologies of dual-input (DI) dual-buck inverter (DBI) is proposed in this paper. A family of DI-DBIs is harvested by replacing the buck switching bridges in a traditional DBI with DI pulsating voltage-source cells. In comparison with the traditional DBIs, an additional dc-input port for a low voltage energy source interface is introduced into the inverters. With the extended low-voltage dc-input port, a low-voltage dc source, whose voltage is lower than the peak amplitude of the ac output voltage, is able to supply power to the ac output within single-stage power conversion stage. The conversion stages of the dc /ac power system, the power rating and power losses of the front-end Boost converter of the inverter are reduced. Besides, the voltage stresses and switching losses of the power switches are reduced due to the multi-level characteristics of the proposed DI-DBIs. As a result, the conversion efficiency of the inverter and the overall dc/ac converter is improved effectively. A DI-DBI proposed, named as DB6 inverter, is analyzed in-depth as an example and compared with the traditional DBI to verify the effectiveness and advantages of the proposed method.

A $200~\mu \text{m}$ by $100~\mu \text{m}$ Smart Submersible System With an Average Current Consumption of 1.3nA and a Compatible Voltage Converter

In this paper, we present a novel microscale “Smart Dust” type system designed to operate in aqueous solutions, with a volume of $200~\mu \text{m} \,\, \times 100~\mu \text{m} \,\, \times $ 35 $\mu \text{m}$ , called a lablet. The lablet contains a 20Hz low-power clock generator, a sensor, electric actuators, and a simple finite state machine to implement a predefined response to the sensor input. It is designed to be rechargeable and to communicate via local contacts through aqueous solution either between lablets or with a docking station chip. The system operates with supply voltages ranging from 0.3 to 1.8V and is thus suitable to be supplied from a capacitor with decreasing voltage. An input rectifier allows powering the lablet independent of polarity. The average current consumption of the system was measured to be 1.3nA when supplied from a capacitor with an initial voltage of 1.8V. The small system scale allows the investigation of “pourable electronics”, a concept where large quantities of microsystems are deployed within a chemical solution to perform a predefined task. Several lablets have been designed and fabricated in a standard 180nm CMOS process and the electrical functionality has been verified by contacting the lablet electrodes with multiple probe needles. In order to use low voltage energy sources to supply the lablet, a voltage up-converter has been designed which is small enough to fit on the lablet.

PEM single fuel cell as a dedicated power source for high-inductive superconducting coils

In practice, the voltage of a hydrogen–oxygen fuel cell is around 1 V at open circuit and from 0.6 V to 0.7 V at full rated load and it can be considered as a low-voltage energy source. Moreover, preliminary investigations undertaken on a single proton exchange membrane fuel cell (PEMFC) highlighted its behavior as a DC current source, that can be directly controlled by the H2 flow rate when the operating point is at very low voltage. In this paper, we present an innovative application of PEMFC that relies on taking advantage of both low voltage level and current source operating mode to feed a high inductive superconducting coil. Such a coil has no resistance and among others, is very sensitive to current ripples. Thus, specific power supplies are designed to feed them but they exhibit in most cases a huge volume and/or a low energy yield. Connecting a superconducting coil to a PEMFC implies to operate in short-circuit, which is an unusual use of PEMFC. To this end, requirements of such an application are defined, by making use of a PEMFC electrical model based on a 1D analog representation of mass transport phenomena. This model, that enables to take into account the influence of gas supply conditions, notably diffusion limit operation, is directly implemented in a standard simulation software used in electrical engineering. Then, simulation results and experimental results obtained by supplying a 10 H superconducting coil cooled by liquid helium by means of a single 100 cm2 PEMFC are compared and discussed.

Low switching stress DC-DC converter with capability of high voltage gain for low voltage energy sources

A soft-switched integrated boost-forward converter with switched capacitor voltage extension cell for low voltage energy sources is proposed. Extended switched capacitor voltage multiplier circuit is incorporated at the secondary side of the forward type coupled inductor. Switched capacitors of the voltage extension cell, charge in parallel through the coupled inductor when the main switch is OFF and discharge to the output in series when the main switch is ON. Thus high voltage step-up is achieved and the voltage stress on the MOSFETs and diodes are reduced. Here, the auxiliary MOSFETs switch helps to realize zero voltage switching turn ON of the MOSFET switches and clamp the voltage across the switches. Modeling and steady state analysis of the converter is provided. A 400 W experimental prototype is build and tested in laboratory. Measured full load efficiency of the converter is 94.29% and highest efficiency is 96.03%.

ZVS–ZCS High Voltage Gain Integrated Boost Converter for DC Microgrid

A nonisolated soft-switched-integrated boost converter having high voltage gain is proposed for the module-integrated PV systems, fuel cells, and other low voltage energy sources. Here, a bidirectional boost converter is integrated with a resonant voltage quadrupler cell to obtain higher voltage gain. The auxiliary switch of the converter, which is connected to the output port acts as an active clamp circuit. Hence, zero voltage switching turn-on of the MOSFET switches are achieved. Coupled inductor's leakage energy is recycled to the output port through this auxiliary switch. In the proposed converter, all the diodes of the quadrupler cell are turned off with zero-current switching (ZCS). This considerably reduces the high-frequency turn-off losses and reverse recovery losses of the diodes. ZCS turn-off of the diodes also remove the diode voltage ringing caused due to the interaction of the parasitic capacitance of the diodes and the leakage inductance of the coupled inductor. Hence, to protect the diodes from the voltage spikes, snubbers are not required. The voltage stress on all the MOSFETs and diodes are lower. This helps to choose switches of low voltage rating (low $R_{\text{DS}}(\text{ON})$ ) and, thus improve the efficiency. Design and mathematical analysis of the proposed converter are made. A 250-W prototype of the converter is built to verify the performance.

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.

High Boost Ratio Hybrid Transformer DC–DC Converter for Photovoltaic Module Applications

This paper presents a nonisolated, high boost ratio hybrid transformer dc–dc converter with applications for low-voltage renewable energy sources. The proposed converter utilizes a hybrid transformer to transfer the inductive and capacitive energy simultaneously, achieving a high boost ratio with a smaller sized magnetic component. As a result of incorporating the resonant operation mode into the traditional high boost ratio pulsewidth modulation converter, the turn-off loss of the switch is reduced, increasing the efficiency of the converter under all load conditions. The input current ripple and conduction losses are also reduced because of the hybrid linear-sinusoidal input current waveforms. The voltage stresses on the active switch and diodes are maintained at a low level and are independent of the changing input voltage over a wide range as a result of the resonant capacitor transferring energy to the output of the converter. The effectiveness of the proposed converter was experimentally verified using a 220-W prototype circuit. Utilizing an input voltage ranging from 20 to 45 V and a load range of 30–220 W, the experimental results show system of efficiencies greater than 96% with a peak efficiency of 97.4% at 35-V input, 160-W output. Due to the high system efficiency and the ability to operate with a wide variable input voltage, the proposed converter is an attractive design for alternative low dc voltage energy sources, such as solar photovoltaic modules and fuel cells.

Driving high voltage piezoelectric actuators in microrobotic applications

Piezoelectric actuators have been used successfully to enable locomotion in aerial and ambulatory microrobotic platforms. However, the use of piezoelectric actuators presents two major challenges for power electronic design: generating high-voltage drive signals in systems typically powered by low-voltage energy sources, and recovering unused energy from the actuators. Due to these challenges, conventional drive circuits become too bulky or inefficient in low mass applications. This work describes electrical characteristics and drive requirements of low mass piezoelectric actuators, the design and optimization of suitable drive circuit topologies, aspects of the physical instantiation of these topologies, including the fabrication of extremely lightweight magnetic components, and a custom, ultra low power integrated circuit that implements control functionality for the drive circuits. The principles and building blocks presented here enable efficient high-voltage drive circuits that can satisfy the stringent weight and power requirements of microrobotic applications.

A Novel Integrated Single-Phase Inverter With Auxiliary Step-Up Circuit for Low-Voltage Alternative Energy Source Applications

This paper presents a novel integrated single-phase inverter with both high step-up ratio and buck-boost capabilities for low-voltage alternative energy source applications. An auxiliary step-up circuit is integrated with an isolated Cuk-derived voltage-source inverter to achieve a much higher voltage-conversion ratio while avoiding using extreme duty ratios in both dc-side and ac-side switches. In addition, the proposed circuit possesses the automatic energy-transfer characteristic between parallel charging and series discharging of two capacitors to achieve a much higher voltage level. Moreover, the voltage stress of dc-side active switches can be reduced to below one half as compared with that of a traditional isolated Cuk converter. Finally, steady-state characteristics, performance analyses, and representative experimental results are also made to show the merits of the proposed inverter.

신재생에너지 연계용 고효율 승압형 DC-DC Converter 회로 토폴로지 개발

본 논문에서는 배터리전원 또는 태양광과 연료전지 등의 신재생 전원에서 발생되는 저전압 에너지원을 고전압으로 변환하기 위한 DC-DC 컨버터의 설계에 대해 연구하였다. 입력 DC24[V] 전압을 출력전압 400[V]로 변환하기 위한 H-브리지 컨버터의 회로 토폴로지에 있어 출력측 전력 및 전압을 제어하기 위해 위상천이제어를 적용하여 구현하였다. 제안된 컨버터 시스템의 장점으로는 전류 스트레스 감소 및 높은 효율성, 신뢰성 및 단순화된 관리뿐만 아니라 저렴한 비용 등을 들 수 있으며, 가정용 전력 생산을 위한 시스템으로 매우 유용하다는 것을 알 수 있었다.

Power conditioning circuit topologies

This article provides an overview of PCS architectures and circuit topologies for low-voltage energy source in single-phase grid-tie applications. The discussion was focused on those relatively new but practical system architectures and circuit topologies including dc-dc converters and dc-ac inverters.