Resistance Emulation Research Articles

Design and validation of a dual-functional damper based on a stepper motor for energy harvesting and vibration control

Dampers are widely used to reduce undesired vibrations. In recent decades, they have been developed from the energy dissipation strategy to the energy harvesting strategy. Dual-functional dampers, which convert part of vibration energy into electrical energy, are intensively studied. DC motors are the most applied electromagnetic transducers in these studies. In this paper, two-phase stepper motors are applied as adjustable electrical dampers and energy harvesters. Dual-functional dampers using stepper motors inherently have higher damping density than those using DC motors, as stepper motors have more pole pairs than DC motors. The nonlinear theoretical electrical damping coefficient of two-phase stepper motors is derived and compared with that of DC motors. A dual two-stage Energy Harvesting Circuit (EHC) is proposed to realize the function of adjustable electrical damping through resistance emulation and the function of harvesting energy. A test bench is built to experimentally verify the adjustable electrical damping and energy harvesting performance of a selected two-phase hybrid stepper motor with the proposed dual two-stage energy harvesting circuit. The numerical solution from the identified model shows a high agreement with the experimental results. The energy harvesting efficiency in the electrical domain has reached about 85%. This tested dual-functional damper using a stepper motor has been successfully integrated into a full-scale demonstrator of the distributed-Multiple Tuned Facade Damping (d-MTFD) system.

A 51-ns Response-Time, Fully Integrated, High-Side Current Sensor for a 40-V 6-A dc–dc Converter

A 130-nm CMOS high-side current sensor for peak-current DC-DC converters, operating with an input voltage up to 40 V is presented. A loop pre-biasing technique is used to prevent the proposed sense-FET-based current sensor from losing its linear behavior, thus achieving fast response time and, hence, allowing operation of the DC-DC converter with short minimum on-time. The proposed circuit also exploits a feedback resistance emulation technique for preventing the feedback loop to open during the blanking time. The current sensor has been integrated within a complete 40-V peak-current DC-DC buck converter that achieves 1-mV/A load regulation and 0.1-mV/V line regulation performances, even with a minimum on-time of 51 ns, with a peak efficiency of 92.5%.

Low Temperature Sensitivity CMOS Transconductor Based on GZTC MOSFET Condition

Complementary Metal Oxide Semiconductor (CMOS) Transconductors, or Gm cells, are key building blocks to implement a large variety of analog circuits such as adjustable filters, multipliers, controlled oscillators and amplifiers. Usually temperature stability is a must in such applications, and herein we define all required conditions to design low thermal sensitivity Gm cells by biasing MOSFETs at Transconductance Zero Temperature Condition (GZTC). This special bias condition is analyzed using a MOSFET model which is continuous from weak to strong inversion, and it is proved that this condition always occurs from moderate to strong inversion operation in any CMOS fabrication process. Additionally, a few example circuits are designed using this technique: a single-ended resistor emulator, an impedance inverter, a first order and a second order filter. These circuits have been simulated in a 130 nm CMOS commercial process, resulting in improved thermal stability in the main performance parameters, in the range from 27 to 53 ppm/oC.

A novel sensorless current shaping control approach for SVPWM inverter with voltage disturbance rejection in a dc grid–based wind power generation system

AbstractA novel sensorless current shaping (CS) control strategy is proposed to avail better power quality (PQ) of a dc grid–based wind power generation system (WPGS) used on a poultry farm by generating an appropriate reference current for space vector pulse width modulation (SVPWM) inverter. The proposed CS strategy also offers adequate control for parallel operation of multiple generators and inverter applications, without requiring voltage and frequency synchronization. Further, to control the poultry farm–based WPGS, a two‐stage control loop is implemented such as energy flow control loop (EFCL) and harmonic control loop (HCL). The first loop is used to regulate the power flow, and the second loop is used to compensate harmonics. A mathematical current decomposition technique is suggested for an appropriate resistance emulation to realize a better power flow, higher harmonic rejection, and better inverter operation. In this planned approach for attaining constant wind speed, an electric ventilation fan in the poultry farm is used. A combined hybrid dc and ac grid approaches are suggested for facilitating variable load integration in a poultry farm–based microgrid system. Moreover, for achieving better power management during the islanded mode of operation, the battery energy storage (BES) device is integrated with the dc grid through a bidirectional converter. The proposed WPGS design and control approach has been simulated through MATLAB/Simulink software under various test conditions, to demonstrate the operational capability, to achieve better PQ, and to increase the flexibility and reliability in the microgrid operation.

Adaptive Distance Protection for Transmission Lines Incorporating SSSC With Energy Storage Device

A Static Synchronous Series Compensator incorporating energy storage device (SSSC-ES) at the DC bus enables the exchange of true power with the system in addition to line reactance compensation. This facilitates improved control of real and reactive power in a transmission system. However, the four-quadrant operation of SSSC presents additional problems for the accurate operation of conventional transmission line protection. In this paper, an in-depth analysis of the effect of emulated reactance and resistance by SSSC-ES installed at the center of a hybrid series compensated line on the performance of distance relay is carried out. An investigation is performed with all possible operating modes and control strategies of SSSC-ES, and the possibility of mal-operation of distance protection are explored. A novel adaptive setting based on constant reactance and constant resistance emulation control strategy of SSSC is proposed for quadrilateral distance relay to prevent the mal-operation. MATLAB / SIMULINK is used for the simulation study.

Electronic resistor emulators for ferroresonance damping in MV transformers

The occurrence of ferroresonances, due to the presence of voltage transformers in isolated-neutral in medium-voltage (MV) distribution grids, results in overvoltages and overcurrents that may damage the connected equipment. To prevent this phenomenon, the protection windings of the MV transformers have to be properly loaded for damping purposes. Mitigation equipment based on resistors, passive/active circuits and static converters have been proposed in the literature. This study proposes a new variety of mitigation equipment based on very simple power electronic converters operated as configurable resistor emulators. The proposed approach is evaluated theoretically and validated experimentally. A resistor emulator proof of concept is designed and applied for damping ferroresonances due to the occurrence of line-to-ground faults in isolated-neutral MV distribution power systems.

Power Quality Enhancement in Residential Smart Grids Through Power Factor Correction Stages

The proliferation of nonlinear loads and the increasing penetration of distributed energy resources in medium-voltage (MV) and low-voltage (LV) distribution grids make it more difficult to maintain the power quality levels in residential electrical grids, especially in the case of weak grids. Most household appliances contain a conventional power factor corrector (PFC) rectifier, which maximizes the load power factor ( $\text{PF}$ ) but does not contribute to the regulation of the voltage total harmonic distortion ( $\text{THD}_V$ ) in residential electrical grids. This paper proposes a modification for PFC controllers by adapting the operation mode depending on the measured $\text{THD}_V$ . As a result, the PFCs operate either in a low current total harmonic distortion ( $\text{THD}_I$ ) mode or in the conventional resistor emulator mode and contribute to the regulation of the $\text{THD}_V$ and the $\text{PF}$ at the distribution feeders. To prove the concept, the modification is applied to a current sensorless nonlinear controller applied to a single-phase boost rectifier. Experimental results show its performance in a PFC front-end stage operating in the continuous conduction mode connected to the grid with different $\text{THD}_V$ .

A Grid-Voltage-Sensorless Resistive-Active Power Filter With Series LC-Filter

Voltage-sensorless control has been investigated for voltage source inverters (VSIs) for many years due to the reduced system cost and potentially improved system reliability. The VSI-based resistive-active power filters (R-APFs) are now widely used to prevent the harmonic resonance in power distribution network, for which the voltage sensors are needed in order to obtain the current reference. In this paper, a grid-voltage-sensorless control strategy is proposed for the R-APF with series LC -filter. Unlike the traditional resistance emulation method, this proposed control method reshapes the output impedance of the R-APF at the harmonic frequencies, which is independent of the current reference. A fundamental grid-voltage estimation method is also proposed to control the dc-link voltage. The performance of the proposed control method is verified in both simulations and experiments. The results show good accuracy of the emulated resistance and functionality of the dc-link voltage control. With the proposed method, the cost of the R-APF can also be reduced with potentially improved system reliability.

High Efficiency Harmonic Harvester Rectenna for Energy Storage Application

This work presents harmonic harvester Rectenna integrated power management circuitry for improving RF-DC power conversion efficiency. The circuitry is developed for battery charging or energy storage application; resistance emulation method is used to realize a matching load resistance at output terminals. The proposed technique is useful for harvesting near maximum output power from the dual rectifiers (fundamental and harmonics) independently. Also, it delivers the combined maximal power to the energy storage cell. The power management module based on dual input buck-boost converter with simple open loop control is utilized.

Dual Comparison One Cycle Control for Single Phase AC to DC Converters

Resistance emulation using one cycle control (OCC) has been used extensively in single-phase full-bridge boost rectifiers. This paper proposes a new control strategy called dual comparison OCC (DC-OCC), which eliminates the limitations of OCC. The advantages of the proposed control strategy is that it ensures the average current is equal to grid voltage scaled by emulated resistance, in each switching cycle. This eliminates issues such as dc offset due to the peak current comparison in OCC. It also ensures that there is no distortion in current when the converter is lightly loaded. It is analytically shown that the proposed DC-OCC does not have the light load instability concerns of conventional OCC. The proposed method is also shown to achieve unipolar pulse-width modulation without sensing the grid voltage resulting in lower effective switching frequency. The proposed control requires only one additional comparator and additional logical elements for implementation. Detailed simulation and experimental studies are carried to validate the proposed control and the high performance that can be obtained.

A resistance emulation approach to optimize the wave energy harvesting for a direct drive point absorber

In general, a major challenge for the exploitation of renewable energies is to improve their efficiency. In electricity generation from the energy of ocean waves, not unlike other technologies, the converter must be optimized to make the energy harvesting economically feasible. This paper proposes a passive tuning control strategy of a point absorber in which the power captured is maximized by controlling the electromagnetic force of the generator with a resistance emulation approach. The proposed strategy consists of mapping the optimal values for regular waves and applying them to irregular waves. This strategy is tested in a wave energy converter in which the generator is connected to a boost rectifier converter whose controller is designed to emulate a resistance. The power electronics system implemented is validated by comparing its performance with the case in which the generator is directly connected to a resistive load. The simulation results show the effectiveness of the proposed strategy as the maximum captured power is concentrated around the optimal values previously calculated and with the same behavior for both excitations.

Convergence Parameter Analysis for Different Metaheuristic Methods Control Constant Estimation and it’s Tradeoff Inference

This paper is an extension of our previous work, which discussed the difficulty in implementing different methods of resistance emulation techniques on the hardware due to its control constant estimation delay. In order to get rid of the delay this paper attempts to include the meta-heuristic methods for the control constants of the controller. To achieve the minimum Total Harmonic Disturbance (THD) in the AC side of the converter modern meta-heuristic methods are compared with the traditional methods. The convergence parameters, which are primary for the earlier estimation of the control constants, are compared with the measured parameters, tabulated and tradeoff inference is done among the methods. This kind of implementation does not need the mathematical model of the system under study for finding the control constants. The parameters considered for estimation are population size, maximum number of epochs, and global best solution of the control constants, best THD value and execution time. MatlabTM /Simulink based simulation is optimized with the M-file based optimization techniques like Particle Swarm Optimization (PSO), Genetic Algorithm (GA), Cuckoo Search Algorithm, Gravity Search Algorithm, Harmony Search Algorithm and Bat Algorithm.

An electromagnetic inerter-based vibration suppression device

This paper describes how an inerter-based device for structural vibration suppression can be realized using an electromagnetic transducer such as a linear motor. When the motor shaft moves, a difference of voltage is generated across the transducer coil. The voltage difference is proportional to the relative velocity between its two terminals. The electromagnetic transducer will exert a force proportional to current following the Lorentz principle if the circuit is closed around the transducer coil. If an electronic circuit consisting of a capacitor, an inductance and a resistance with the appropriate configuration is connected, the resulting force reflected back into the mechanical domain is equivalent to that achieved by a mechanical inerter-based device. The proposed configuration is easy to implement and very versatile, provided a high quality conversion system with negligible losses. With the use of electromagnetic devices, a new generation of vibration absorbers can be realized, for example in the electrical domain it would be relatively uncomplicated to synthesize multi-frequency or real time tunable vibration absorbers by adding electrical components in parallel. In addition by using resistance emulators in the electrical circuits, part of the absorbed vibration energy can be converted into usable power. Here an electromagnetic tuned inerter damper (E-TID) is tested experimentally using real time dynamic substructuring. A voltage compensation unit was developed in order to compensate for coil losses. This voltage compensation unit requires power, which is acquired through harvesting from the vibration energy using a resistance emulator. A power balance analysis was developed in order to ensure the device can be self sufficient. Promising experimental results, using this approach, have been obtained and are presented in this paper. The ultimate goal of this research is the development of autonomous electromagnetic vibration absorbers, able to harvest energy, convert it into usable power, and use it for vibration control and health monitoring.

An electromagnetic vibration absorber with harvesting and tuning capabilities

This paper describes the development of an electromagnetic vibration absorber (EVA) with energy recovery and frequency tuning control capabilities. The essential component of the EVA is an electromagnetic transducer, interfacing between electrical and mechanical domains, connected to an external electrical circuit. So far, the use of electromagnetic devices in vibration-control applications has been driven by energy-harvesting applications. In these works, the electromagnetic transducer acts as a damper in the mechanical domain by connecting a resistance across the terminals of the device. By emulating the resistive components, some of the power that would have been dissipated in the resistor can be converted into usable power. The use of electromagnetic devices also opens the door (i) to the synthesis of more complex networks in the electrical domain, most of them impractical or too complicated to be synthesized mechanically and (ii) to the development of frequency tuning networks. We consider the possibility of using an EVA along with a resistance emulator to give a self-powered adaptive EVA. We explore the switching in of different elements across the terminals of the electromagnetic transducer in order to be able to derive new low-powered control schemes for better vibration absorption. With the underlying goal to develop high performance, energy-efficient vibration-control devices, a small scale EVA device was tested, coupled with a virtual host structure. The results presented here demonstrate the potential for self-tuning of such a device. Copyright © 2015 John Wiley & Sons, Ltd.

120% Harvesting Energy Improvement by Maximum Power Extracting Control for High Sustainability Magnetic Power Monitoring and Harvesting System

The magnetic energy harvesting (MEH) circuit and the power monitoring system are proposed in this paper to enlarge the system sustainability on wireless sensing or the monitoring system. The proposed MEH circuit harvests magnetic power on power wires through a power sensing current transformer (CT) and charges power monitoring system. The MEH circuit includes the direct ac-dc rectifier and the maximum power extracting (MPE) control circuit. The direct ac-dc rectifier can directly rectify ac input to the dc output current. The proposed MPE control fits the characteristic of magnetic energy source compared to the conventional resistor emulation maximum power point tracking method. Owing to continuous tracking the maximum power of the CT, 120% harvesting power improvement can be achieved under the same CT's sensing current. Peak efficiency of 82% can be achieved under the sensing current of 8 A. The test chip is fabricated in 0.25 μm CMOS process with an active area of 0.98 mm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> .

Three‐phase rectifiers with suboptimal current injection and improved efficiency

Three-phase diode bridge rectifiers that apply suboptimal current injection and active resistance emulation are analysed. Two types of current injection devices (CIDs) are in the focus, and rectifiers with each CID are analysed for two cases of active resistance emulation: one that applies low-frequency filtering of the emulator output, and another that does not. Models that cover both continuous and discontinuous conduction mode are developed. To minimise the input current total harmonic distortion (THD), optimisation is performed, showing that in each case the THD is about the same when the emulated resistance takes its optimal value. The results are experimentally verified on a 1.5 kW rectifier.

Switched-mode impedance synthesis for electrical tuning of a vibration energy harvester

Switched-mode power circuits are able to efficiently synthesise a variable complex load impedance that can tune a vibration energy harvester, whilst also providing rectification and feeding the harvested energy into a DC store. The electrical tuning system presented in this paper is based upon a boost rectifier configured as a variable power factor converter. Its performance is benchmarked against a more basic resistance emulator where it is demonstrated that electrical tuning provides an increase in power bandwidth of over three times. The paper describes the experimental results of electrical tuning in some detail and elucidates the design challenges for these systems.

열가소성 폴리우레탄과 벅-부스트 컨버터를 이용한 마이크로 에너지 포집시스템 설계

This paper proposes the design of micro energy harvesting system by using thermoplastic polyurethane(TPU), which harvests electric energy from the kinetic energy of pedestrian and drives the desired load, and applied it to the self-generating shoes. Also, we designed the buck-boost converter in discontinuous conduction mode(DCM) which functions as a resistor emulator(RE) such that converter`s average input current is proportional to input voltage, and it results in transfer of maximum power to buck-boost converter according to control behavior that converter`s input resistance is matched with TPU`s internal resistance. Therefore, this paper confirms the validity of proposed control scheme and possibility of application for self-generating shoes, from the obtained characteristic of designed micro energy harvesting system by using a TPU and buck-boost converter in DCM.

Optimized Wind Energy Harvesting System Using Resistance Emulator and Active Rectifier for Wireless Sensor Nodes

This paper presents an optimized wind energy harvesting (WEH) system that uses a specially designed ultra-low-power-management circuit for sustaining the operation of a wireless sensor node. The proposed power management circuit has two distinct features: 1) an active rectifier using MOSFETs for rectifying the low amplitude ac voltage generated by the wind turbine generator under low wind speed condition efficiently and 2) a dc-dc boost converter with resistor emulation algorithm to perform maximum power point tracking (MPPT) under varying wind-speed conditions. As compared to the conventional diode-bridge rectifier, it is shown that the efficiency of the active rectifier with a low input voltage of 1.2 V has been increased from 40% to 70% due to the significant reduction in the ON-state voltage drop (from 0.6 to 0.15 V) across each pair of MOSFETs used. The proposed robust low-power microcontroller-based resistance emulator is implemented with closed-loop resistance feedback control to ensure close impedance matching between the source and the load, resulting in an efficient power conversion. From the experimental test results obtained, an average electrical power of 7.86 mW is harvested by the optimized WEH system at an average wind speed of 3.62 m/s, which is almost four times higher than the conventional energy harvesting method without using the MPPT.

Resistor Emulation Approach to Low-Power RF Energy Harvesting

This paper presents an approach and associated circuitry for harvesting near maximum output power from electromagnetic waves in the RF/microwave region of the spectrum with variable incident power densities in the range of tens of muW/cm2. It is shown that open loop resistor emulation at the input port of a power converter is a suitable solution for tracking the peak power point of a low-power rectifying antenna source over a wide range of incident RF power densities. A boost converter with a simple low-power control approach for resistor emulation is presented. A hardware design example with detailed efficiency analysis is given using commercially available discrete circuitry. Experimental results are presented for a system harvesting 420 muW to 8 muW from a 6 cm times 6 cm rectifying antenna with incident RF power ranging from 70 muW/cm2 to 30 muW/cm2, respectively. The results demonstrate that resistor emulation is a simple and practical approach to energy harvesting with variable low-power radiative RF sources.