Range Of Load Resistance Research Articles

Influence of Power Losses in the Inductor Core on Characteristics of Selected DC–DC Converters

The paper presents the results of a computer simulation illustrating the influence of power losses in the core of an inductor based on the characteristics of buck and boost converters. In the computations, the authors’ model of power losses in the core is used. Correctness of this model is verified experimentally for three different magnetic materials. Computations are performed with the use of this model and the Excel software for inductors including cores made of ferrite, powdered iron, and nanocrystalline material in a wide range of load resistance, as well as input voltage of both the considered converters operating at different values of switching frequency. The obtained computation results show that power losses in the inductor core and watt-hour efficiency of converters strongly depend on the material used to make this core, in addition to the input voltage and parameters of the control signal and load resistance of the considered converters. The obtained results of watt-hour efficiency of the considered direct current (DC)–DC converters show that it changes up to 30 times in the considered ranges of the mentioned factors. In turn, in the same operating conditions, values of power losses in the considered cores change from a fraction of a watt to tens of watts. The paper also considers the issue of which material should be used to construct the inductor core in order to obtain the highest value of watt-hour efficiency at selected operation conditions of the considered converters.

Analog-Assisted Digital Capacitorless Low-Dropout Regulator Supporting Wide Load Range

Capacitorless (CL) low-dropout regulators (LDO) have gained significant research interest for point-of-load voltage regulation without off-chip capacitors. While analog CL-LDOs can deliver superior power supply rejection (PSR), digital CL-LDOs are more scalable and efficient. To achieve the advantages of both types, this paper presents a digital CL-LDO with an analog PSR enhancer, delivering strong PSR without compromising scalability and efficiency. Load regulation is performed by an asynchronous digital feedback controller for fast transient response and scalable load drivability. PSR is achieved by a load-insensitive wide-bandwidth analog controller. A prototype chip of the analog-assisted digital CL-LDO is fabricated in a 130-nm CMOS process with an active area of 0.0645 mm2 , supporting load current up to 50 mA at nominal 1-V input and 0.8-V output. The measured PSR is better than –20 dB for frequencies up to 10 MHz, and the measured current efficiency peaks at 99.3%, with average current efficiency of 96.7% across 50× load range. The measured transient response to a full load step, with two values of load capacitance (100 pF and 10 nF), demonstrates the LDO's stable operation over a wide range of load resistance and capacitance.

Zero-Voltage Switching Operation of Transformer Class-E Inverter at Any Coupling Coefficient

This paper presents a complete design methodology of a Class-E inverter with a loosely coupled transformer under zero-voltage switching conditions. At a selected maximum coupling coefficient, the inverter satisfies both zero-voltage switching (ZVS) and zero-derivative switching (ZDS) conditions to achieve a high efficiency. As the coupling coefficient is decreased from its maximum value to zero, the inverter satisfies the ZVS condition over a wide range of load resistance. The proposed method absorbs the magnetizing inductance and the leakage inductance into the inverter topology. The closed-form expressions for all the Class-E inverter parameters are derived in terms of the coupling coefficient, including: 1) input impedance of the transformer with a complex load impedance; 2) equivalent phase of the resonant circuit for both nominal and suboptimum operations; and 3) slope of the switch voltage waveform. The relationship between the voltage slope and the coupling coefficient is introduced, which indicates the proximity of the operating point from ZVS and ZDS conditions. A design example of the Class-E inverter is presented to achieve both ZVS and ZDS, at an optimum coupling coefficient of 0.77, and ZVS condition for any coupling coefficient lower than 0.77 and over a wide range of load resistance. Saber simulations and experimental results are given to validate the soft-switching capabilities over a wide range of the coupling coefficient and load resistance. The theoretical results were in good agreement with Saber simulations and experiments.

Analytical study of influence of boundary conditions on acoustic power transfer through an elastic barrier

In this paper, a fully coupled electromechanical model of wireless power transfer through an elastic barrier using piezoelectric transducers is established based on the theory of piezoelectricity. In this model, an elastic layer representing the elastic barrier is sandwiched by two piezoelectric layers attached by boundary mass and boundary constraint. The two piezoelectric layers act as input energy converter and output energy receiver, respectively. Using the electrical and mechanical boundary and continuous conditions, all the electrical and mechanical components of the system are derived. A simplification is performed and compared with a previous study and a preliminary experiment to valid the present study. Numerical studies are conducted to reveal the effects of circuit load resistance, barrier thickness, boundary mass and boundary constraint on the resonance frequency, output voltage, output power and transmission efficiency of the present model. With different circuit load resistance, the system resonance frequency is found between the short-circuit resonance frequency and open-circuit resonance frequency. With boundary mass applied to the piezoelectric transducers, the maximum resonance frequency response of both the output power and the transmission efficiency move toward the low-order resonance frequency. With boundary constraint applied to the boundary mass, a newly generated resonance frequency with high transmission efficiency at the low-frequency range is observed. A method to recognize the necessary input frequency range as well as the necessary circuit load resistance range respectively for large output power and large transmission efficiency is proposed.

Design and analysis of a collocated periodic vibration absorber-harvester

A collocated periodic vibration absorber-harvester (PVAH) is designed and the interaction between its absorption ability and harvesting capability is investigated. The PVAH consists of dual cantilever beams interconnected by a discrete spring. For energy harvesting purpose, both cantilever beams are partially covered with PZT layers. If the PVAH is properly designed, it could absorb vibrations in integer multiples of the base excitation frequency and harvest the vibration energy simultaneously. The PVAH can be designed based on its open or closed circuit state. To understand the performance of the PVAH, absorption and harvesting indicators are respectively defined and their dependencies on system parameter such as load resistance are examined. Numerical and experimental results show that PVAH outperforms a tonal dynamic vibration absorber when the excitation is periodic. In addition, experimental measurements reveal that there exists a best load resistance for maximum harvesting which depends on PZT coverage ratio. An illustrative PVAH case shows that the absorption performance diminishes 8.7% at maximum power harvesting when 15% of the beam length is covered with PZT layer. Experimental investigations conducted not only verify the theoretical calculations but also prove that collocated absorber and harvester design is feasible. Finally, a reasonable range of load resistance for the PVAH design is located and provided. This could be helpful to the vibration engineers for collocated absorber-harvester design.

Modeling and Experimental Validation of a Capacitive Link for Wireless Power Transfer to Biomedical Implants

This brief reports on the modeling and experimental validation of a capacitive link as an emerging strategy for wireless power transfer to biomedical implants. The capacitive link comprises two pairs of coated parallel plates that are placed at a distance of ${L}$ apart, with a tissue layer acting as the dielectric material. A series-resonant structure is then formed by placing two inductors in series with the capacitive link. A comprehensive circuit model is proposed that accounts for the ${L}$ -dependent, parasitic, cross-coupled, and longitudinal resistive elements contributed by the tissue between the two pairs. The series-resonant capacitive link is also realized with 400-mm $^{2}$ capacitive pads on printed-circuit boards that are coated with a 1- $\mu \text{m}$ -thick layer of Parylene- ${N}$ , aligned around a 5-mm-thick tissue layer, and placed in series with two 100- $\mu \text{H}$ inductors, resulting in resonance frequencies of ~115 and 127 kHz. At an operation frequency of 120 kHz and over a wide range of load resistance from $10~\Omega $ to 100 $\text{k}\Omega $ , the effect of ${L}$ on the power delivered to the load and power transfer efficiency parameters of the link is measured from 2 cm to $\infty $ and shown to be in very good agreement with simulation results from the related circuit model.

Tuning Electrode Properties and Surface Contacts for Uniform Deposits Produced by Atmospheric Plasma Dielectric Barrier Discharge Reactors

An investigation of the effect of experimental parameters on the temperature and uniformity of material deposition by atmospheric pressure dielectric barrier discharge (DBD) planar plasma reactors was conducted. The apparatus consisted of a pulsed AC high voltage power source with various electrode materials (aluminum, copper wire mesh, and aluminum/copper wire mesh) operating under a range of load resistances. Possible effects of non-ideal interfacial conditions for the contact surface between the electrode and the substrate were also studied with various modified surface thermal conditions. It was found that a hybrid electrode design with a fine copper (Cu) wire mesh attached to an aluminum plate of approximately 3 mm thickness produced the most visually uniform deposit, presumably as a result of both the superior conductivity provided by the Al metal plate and the stable plasma resulting from the relatively low breakdown voltage by using helium (He) as the dilution gas. Although the experimental conditions of plasma-enhanced chemical vapor deposition (PECVD) are often specific to particular systems and applications, this work provides insights on technical details which can be applied to various plasma DBD reactors.

Nulls-Free Wireless Power Transfer With Straightforward Control of Magnetoinductive Waves

We present a straightforward and yet, effective method to modulate the termination impedance of 1-D $LC$ resonating arrays for wireless power applications. The modulation method is based on activating/deactivating the last two cells of the array allowing to remove the power nulls caused by standing waves inside this type of arrays. The modulation of the terminating impedances is done at a distinct frequency than the resonance frequency of the cells. We explain why and how this distinct frequency was chosen. We further demonstrate how the same modulation is applicable for a wide range of load resistances on the receiver device. Modulation is achieved by wirelessly sensing the voltage delivered by the power supply according to where above the array a receiver device is located. A microcontroller records these voltages and determines which terminating impedance will provide the highest possible efficiency to the receiver device. Changes in the terminating impedances are set by digitally controlled solid state relays. The proposed modulation method permitted to power up a receiver device with a system efficiency of up to 60% anywhere over the 30 cm length of the resonating array.

Switched Control of Three-Phase Voltage Source Pulsewidth-Modulated Rectifier Under Dynamic Load: Output Feedback and Robustness

Three-phase voltage source pulsewidth-modulated (PWM) rectifiers (VSRs) have received great attentions in industrial applications. Recently, some attempt has been made to study the flexible direct current (DC)-bus voltage regulation problem under dynamic load of three-phase VSRs by switched control. Several proportional-integral (PI) controllers are designed for different load resistance range while only one PI controller is implemented for a given time instant by regarding the load resistance as the switching law. However, the existing approach is based on state feedback control, which requires the measurement of source current and DC-bus voltage. In this paper, we will adopt an output feedback control scheme, i.e., only DC-bus voltage should be measured. Compared with the existing result, our design requires less information and reduces the cost. Moreover, the robustness analysis of plant parameters is given when all the states are available. Simulation results demonstrate the effectiveness of our design.

Rheological properties of typical chernozems (Kursk oblast) under different land uses

Rheological parameters of humus horizons from typical chernozems under different land use—on a virgin land (unmown steppe) and under an oak forest, long-term black fallow, and agricultural use—have been studied by the amplitude sweep method with an MCR-302 modular rheometer at water contents corresponding to swelling limit and liquid limit. From the curves of elastic and viscous moduli, the ranges of elastic and viscoelastic (plastic) behavior of soil pastes—as well as that of transition from viscoelastic to viscous behavior—have been determined. It has been shown that the rheological behavior is largely determined by the content of organic matter, which can act as a binding agent structuring the interparticle bonds and as a lubricant in the viscous-flow (plastic) state of soil pastes. Soil samples enriched with organic matter (virgin land, oak forest, forest belt) have a more plastic behavior and a higher resistance to loads. Soil samples with the lower content of organic matter (long-term fallow, plowland) are characterized by a more rigid cohesion of particles and a narrower range of load resistance. Soil pastes at the water content of liquid limit have a stronger interparticle cohesion and a more brittle behavior than at the water content of swelling limit. Methodological aspects of testing soil pastes at the constant sample thickness and the controlled normal load have been considered. For swelling soil samples, tests under controlled normal load are preferred.

Design of Single-Switch Inverters for Variable Resistance/Load Modulation Operation

Single-Switch inverters such as the conventional Class-E inverter are often highly load sensitive, and maintain zero-voltage switching over only a narrow range of load resistances. This paper introduces a design methodology that enables rapid synthesis of Class E and related single-switch inverters that maintain ZVS operation over a wide range of resistive loads. We treat the design of Class-E inverters for variable resistance operation and show how the proposed methodology relates to circuit transformations on traditional Class-E designs. We also illustrate the use of this transformation approach to realize Φ <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> inverters for variable-resistance operation. The proposed methodology is demonstrated and experimentally validated at 27.12 MHz in a Class E and Φ <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> inverter designs that operate efficiently over 12:1 load resistance range for an 8:1 and 10:1 variation in output power, respectively, and a 25-W peak output power.

Manufacture and Characterisation of Piezoelectric Broadband Energy Harvesters Based on Asymmetric Bistable Cantilever Laminates

In this paper a bistable asymmetric laminate is manufactured and coupled to a ferroelectric material for potential energy harvesting applications. A cantilever configuration is explored and the harvester response as a function of vibration frequency, vibration level and electrical load resistance examined. The harvester is characterised at low and high vibration levels where the device exhibits either single well oscillations (at low vibration amplitude) or snap-through events (at high vibration amplitude). As the vibration levels increase and the device approaches snap-through it exhibits ‘softening’ where the peak power moves to lower frequencies with differences in power levels during up-sweep and down-sweep of frequencies. Examination of the frequency dependence of power for a range of load resistances indicates a broadening of the harvester performance at higher vibration levels and during snap-through.

A CMOS Controllable Constant-Power Source for Variable Resistive Loads Using Resistive Mirror With Large Load Resistance Dynamic Range

A CMOS controllable constant-power source for variable resistive loads is presented. Its operation is based on the resistive mirror which keeps the equality of the resistive original resistance and the resistive image resistance. Stability requirements are in accordance with the requirements of the basic approach itself enabling large load resistance dynamic range. Two designs are considered. Prototypes based on discrete components have been experimentally verified. Relative errors of the generated power with the discrete values in the range from 0.48 to 10.8 mW, for the load resistance range from 0.5 to 1.5 kQ, are smaller than 2.2%. Also, for the generated power of 6 mW, the load resistance range from 0.2 to 5.6 kQ with the relative error smaller than 0.7% has been achieved.

Methodology to obtain the linear range of a transistor as a control element in a DC current source

This paper presents a methodology to develop direct current sources using BJT transistors on the linear region (active region). This region depends on the saturation voltage, maximum power and polarization voltage of the element; from these parameters it is obtained the load resistance range that ensures a constant current. The methodology is used to develop a DC current source prototype of 2A and the range of the load resistance is defined by the transistor characteristics. The temperature and power constrains are taking into account.

A Junctionless Gate-All-Around Silicon Nanowire FET of High Linearity and Its Potential Applications

The linearity of a gate-all-around junctionless silicon nanowire (SiNW) FET has been analyzed. The SiNW FET shows a perfectly linear <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex Notation="TeX">$I_{D}$</tex></formula> – <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex Notation="TeX">$V_{G}$</tex></formula> relation and a nearly zero output conductance. The mechanism of its linear behaviors due to degenerate doping level has been also demonstrated. For RF applications, the proposed SiNW FET exhibits a much lower distortion for a whole range of load resistance, making it superior to modern short-channel MOSFET.

ZnO Nanostructured Diodes - Enhancing Energy Generation through Scavenging Vibration

ABSTRACTRecent developments on the use of the piezoelectric effect in ZnO nanorod-based p-n junctions for energy harvesting applications are presented. Two types of junctions are used. The first is a hybrid p-n device combining the semiconducting polymer poly(3,4-ethylene-dioxythiophene) poly(styrenesulfonate) (PEDOT:PSS) with ZnO nanorods. The second type of junction is an all-inorganic junction between n-type ZnO nanorods and p-type CuSCN. It is shown that both these diodes can be produced on flexible plastic substrates, which generate a voltage output when bent. The voltage output of the ZnO/PEDOT:PSS diodes are measured across a range of resistive loads while bending to find a maximum power point of 12 μWcm-2 at 4 kΩ. It is shown that a voltage output is also generated when this structure is vibrated acoustically. The ZnO/CuSCN diode is sensitized to sunlight with a Ru-based dye to form a photovoltaic device. It is shown that the device efficiency can be increased by application of acoustic vibrations. This is attributed to the electric field generated by the piezoelectric effect in ZnO affecting the charge-carrier recombination at the ZnO surface.

Piezoelectric vibration energy harvesting by optimized synchronous electric charge extraction

This article presents a novel nonlinear energy extraction technique for piezoelectric vibration energy harvesting. The proposed approach is an improvement of the previous technique, “synchronous electric charge extraction,” which is the first that optimizes the harvested power whatever the connected load. The new approach is then named as “optimized synchronous electric charge extraction.” Compared with synchronous electric charge extraction, the conversion effectiveness is enhanced while simplifying the electronic circuitry and the switch control strategy. The analytical expression of the harvested powers is derived for a classical electromechanical structure. Finally, theoretical predictions confirmed by experimental results show that optimized synchronous electric charge extraction increases the harvested power for a very large range of load resistance, which is a favorable characteristic for wideband vibration energy harvesting.

Simultaneous 6-Gb/s Data and 10-mW Power Transmission Using Nested Clover Coils for Noncontact Memory Card

An inductive power and data transmission link for a noncontact memory card interface is reported. Nested clover coils improve signal-to-interference ratio and enable simultaneous power and data transmission. This capability is then used in the design of a closed-loop feedback system for improving power transfer efficiency. Interference cancellation mechanism is analyzed with both 3-D EM simulations and a newly developed compact model of coupled inductors. Performance of the proposed solutions was confirmed experimentally using a scaled-down stacked-chip prototype fabricated in a 65-nm CMOS process. Maximum data transmission rate is 6 Gb/s and the total power transfer efficiency is 5.2%-10.2% over a load resistance range of 0.1-2 kΩ.

Double loop control of buck-boost converters for wide range of load resistance and reference voltage

A double-loop control mechanism is developed for an inverting buck-boost converter. The robust converter is capable of operating in a wide range of reference voltage and load resistance with unmodelled parameters. The cause of the non-minimum phase behaviour is analysed. The boundary layer width of the output voltage in sliding mode is found to be dependent on the circuit and control parameters. The speeds of the inner and outer loop are quantitatively determined and compared. The transient responses of the circuit are forecastable. The controller is validated on a simulation circuit.

Investigating Buck DC-DC Converter Operation in Different Operational Modes and Obtaining the Minimum Output Voltage Ripple Considering Filter Size

This paper investigates the operational modes of buck dc-dc converters and their energy transmission methods. The operational modes of such converters are classified in two types, discontinuous conduction mode (DCM) and continuous conduction mode (CCM). In this paper, the critical inductance relation of DCM and CCM is determined. The equations of the output voltage ripple (OVR) for each mode are obtained for a specific input voltage and load resistance range. The maximum output voltage ripple (MOVR) is also obtained for each mode. The filter size is decreased and the minimum required inductance value is calculated to guarantee the minimization of the MOVR. The experimental and simulation results in PSCAD/EMTDC prove the correctness of the presented theoretical concepts.