External Inductor Research Articles

A Self-Powered and Area Efficient SSHI Rectifier for Piezoelectric Harvesters

This article presents an area efficient fully autonomous piezoelectric energy harvesting system to scavenge energy from periodic vibrations. Extraction rectifier utilized in the system is based on synchronized switch harvesting on inductor (SSHI) technique which enables system to outperform standard passive rectifiers. Compared to conventional SSHI circuits, enhanced SSHI (E-SSHI) system proposed in this paper uses a single low-profile external inductor in the range of $\mu \text{H}$ ’s to reduce overall system cost and volume, hence broadening application areas of such harvesting systems. Furthermore, E-SSHI does not include any negative voltage converter circuit and therefore, it offers area efficient AC/DC rectification. Detection of optimal voltage flipping times in E-SSHI technique is conducted autonomously without any external calibration. Energy transfer circuit provides control over how much energy is delivered from E-SSHI output to electronic load. The proposed system is fabricated in 180 nm CMOS process with 0.28 mm2 active area. It is tested using a commercial piezoelectric transducer MIDE V22BL with periodic excitation. Measured results reveal that E-SSHI circuit is capable of extracting up to 5.23 and 4.02 times more power compared with an ideal full-bridge rectifier at 0.87 V and 2.6 V piezoelectric open circuit voltage amplitudes (VOC, P), respectively. A maximum voltage flipping efficiency of 93% is observed at VOC,P = 3.6 V, owing to minimized losses on charge flipping path. Measured results are compared with state-of-the-art interface circuits. Comparison shows that E-SSHI design offers a huge step towards miniaturized harvesting systems thanks to its low-profile and fully autonomous design.

Overvoltage Estimation by Stray Inductances During Turn-off of a 500 kV/25 kA DC Circuit Breaker

Metal oxide varistors (MOVs) are usually applied to clamp the voltage across a dc circuit breaker (DCCB) after fault current elimination. This letter focuses on the transient process of a DCCB turn-off and has three contributions. First, it reveals that snubber circuit inductance, the internal and external stray inductances of an MOV could cause a significant overvoltage across a DCCB, which exceeds 47.5% of its nominal clamping voltage. The overvoltage mechanism is clearly analyzed based on the working principle of a DCCB, providing theoretical equations to estimate the overvoltage magnitude. Second, a nonlinear model of an MOV is proposed to simplify the calculation and provide an accurate estimation result. Third, a new arrangement of series submodules with discrete MOVs is proposed to suppress the overvoltage. A hybrid 500 kV/25 kA DCCB prototype with series insulated gate bipolar transistors (IGBTs) is implemented to validate the proposed analysis. The series-IGBT rating voltage is 1440 kV, and the MOV with a nominal clamping voltage of 800 kV is used to protect IGBTs. However, a 25 kA turn-off experiment clearly shows that the overvoltage increased to 1203 kV by an external stray inductance of 39.5 μH and di/dt of 1480 A/μs. The relative error between measurements and simulations is within 3%. Besides, simulations on the new arrangement show the overvoltage is decreased by 23.4% than before.

Dynamic Oscillation via Negative Differential Resistance in Type III Junction Organic/Two‐Dimensional and Oxide/Two‐Dimensional Transition Metal Dichalcogenide Diodes

AbstractAmong many of 2D semiconductor‐based devices, type III PN junction diodes are given special attentions due to their unique function, negative differential resistance (NDR). However, it has been found uneasy to achieve well‐matched type III PN junctions from 2D–2D van der Waals heterojunctions. Here, the authors present other alternatives of type III heterojunctions, using 2D p‐MoTe2/organic n‐type dipyrazino[2,3‐f:2′,3′‐h]quinoxaline‐2,3,6,7,10,11‐hexacarbonitrile (HAT‐CN) and 2D p‐WSe2/n‐MoOx systems. Those junction diodes appear to well‐demonstrate static and dynamic NDR behavior via resonant tunneling and electron–hole recombination. Extended to an inverter circuit, p‐MoTe2/n‐HAT‐CN diode enables multilevel inverter characteristics as monolithically integrated with p‐MoTe2 channel field effect transistor. The same NDR diode shows dynamic LC oscillation behavior under a constant DC voltage, connected to an external inductor. From p‐WSe2/n‐MoOx oxide diode, similar NDR behavior to those of p‐MoTe2/n‐HAT‐CN is again observed along with LC oscillations. The authors attribute these visible oscillation results to high peak‐to‐valley current ratios of their organic or oxide/2D heterojunction diodes.

Analysis and Simulation of Multi-Loop SQUID-Based Electric Circuits With Mesh-Current Method

Practical superconducting quantum interference devices (SQUIDs) have been developed into multiloop hybrid electric circuits with Josephson junctions and normal elements such as resistor, inductor and capacitor. To find a common circuit analysis and simulation method for different types of SQUID hybrid circuits consist of both superconducting and normal components, we introduce a mesh-current method, which can derive both the general system model and uniform circuit equations directly from the equivalent circuit. The mesh-current method is demonstrated in the simulation of a SQUID additional positive feedback circuit. The numerical simulation results are presented and verified with the measurements. Compared with the conventional nodal analysis method, the mesh-current method is excellent in dealing with the relations including external flux, self and mutual inductances in multiloop hybrid circuit analysis; its final circuit equations directly exhibit the physical theorems; its general system model reveals the quantum interference mechanism inside SQUID circuits, and is applicable for further dynamics studies.

LDO-Free Power Management System: A 10-bit Pipelined ADC Directly Powered by Inductor-Based Boost Converter With Ripple Calibration

This article presents a compact power management solution for a pipeline analog-to-digital converter (ADC), employing only a switching-mode power converter. By directly powering the ADC using a boost DC-DC converter, the power delivery network (PDN) exhibits an overall-high power efficiency. The proposed foreground ADC calibration calibrates the ripple error induced from the power converter, which obviates the need for well-regulated supply and reference voltage offered by low-efficiency linear low-dropout regulators (LDOs). A chip integrates the boost DC-DC converter and the pipelined ADC with an external power inductor. The prototype, implemented in 65-nm CMOS, occupies 2.34-mm2 of total active area (9.4% - ADC, 2.6% - power controller and switches, and 88% - output capacitance). In the measurement, the boost converter, switching at 31.25MHz, converts a 0.5V input to 1.2V and delivers 22.8mW of power to the pipeline ADC. The boost DC-DC converter supplies all voltage domains, including analog/digital power supply and reference. The resulting overall system power efficiency is 78.6%. Sampled at 500MS/s, the ADC achieves a signal-to-noise and distortion ratio (SNDR) of 34.7/39.9dB without/with the ripple calibration for an input frequency of 177MHz, respectively.

A 24-GHz Single-Transistor Oscillator on Paper

This letter describes a single-transistor oscillator implemented on a paper substrate at the operating frequency of 24 GHz, based on a design procedure that makes it possible to overcome the limitations caused by thin high-loss substrates and package parasitics of commercial components. The commercial transistor adopted in the oscillator is led to instability by exploiting its parasitic gate inductance. The drain network compensates for the parasitic inductance of the transistor package and connects the oscillator circuit to a 50- $\Omega $ load resistance. Finally, an external inductor at the source terminal is used to resonate out the capacitive contribution of the circuit at the oscillation frequency. Overall, the active device appears in a quasi-common-drain stage. Experimental results on prototype show that the oscillator exhibits an output power of +6.2 dBm at 24 GHz, with a dc power consumption of 72.5 mW.

Magneto-Impedance Biosensor Sensitivity: Effect and Enhancement.

Biosensors based on magneto-impedance (MI) effect are powerful tools for biomedical applications as they are highly sensitive, stable, exhibit fast response, small in size, and have low hysteresis and power consumption. However, the performance of these biosensors is influenced by a variety of factors, including the design, geometry, materials and fabrication procedures. Other less appreciated factors influencing the MI effect include measuring circuit implementation, the material used for construction, geometry of the thin film sensing element, and patterning shapes compatible with the interface microelectronic circuitry. The type magnetic (ferrofluid, Dynabeads, and nanoparticles) and size of the particles, the magnetic particle concentration, magnetic field strength and stray magnetic fields can also affect the sensor sensitivity. Based on these considerations it is proposed that ideal MI biosensor sensitivity could be achieved when the sensor is constructed in sandwich thick magnetic layers with large sensing area in a meander shape, measured with circuitry that provides the lowest possible external inductance at high frequencies, enclosed by a protective layer between magnetic particles and sensing element, and perpendicularly magnetized when detecting high-concentration of magnetic particles.

A wireless passive extra-arterial implantable blood pressure monitoring sensing system for rats

A novel, wireless, passive, extra-arterial implantable blood pressure monitoring system was designed, fabricated, and tested. The measurement system is composed of an implantable sensor in-vivo and a readout system in-vitro. It was designed to balance the measurement accuracy and arterial invasiveness in continuous blood pressure monitoring. The passive LC resonant circuit was formed by a variable parallel-plate capacitance and a planar spiral inductor. It was fabricated and implanted in the necks of the rats to detect blood pressure changes. The variation of blood pressure was transduced into a change of the capacitance value of the variable parallel-plate capacitor, which caused a variation of the resonant frequency of the LC circuit. A readout probe with inductor coil was then used to measure the change of the resonant frequency of the LC circuit, and therefore indirectly measure the variation of blood pressure wirelessly. By measuring the resonant frequency with electromagnetic coupling of the implanted LC resonant sensor and the external inductor coil, a sensitivity of 8.53 kHz/mmHg for blood pressure measurement had been successfully achieved. The sensing distance is longer than 22 mm, which is enough for implementation of the wireless measurement. The overall size of the implantable sensor is 5 mm × 1.1 mm. The wireless implantable blood pressure sensor may be used in biomedical research for continuous, accurate and arterial trauma free blood pressure monitoring.

Experimental Study of the Effect of External Inductance on Pinch Characteristics and Neon Soft X-Ray Yield in Filippov-Type Plasma Focus Device

So far, the detailed experimental effect of the inductance on the X-ray yield in the Filippov-type plasma focus devices has not been documented in literature. In this paper, a 90 kJ Filippov-type plasma focus device is used to investigate the effect of three different external inductances (20, 40, and 60 nH) on the pinch current and neon soft X-ray (SXR) yield experimentally. The obtained results for the three inductances show that the 60 nH inductance produces maximum pinch current for high voltages (12–13 kV). The results also show that with using 60 nH external inductance, a larger fraction of maximum current is transferred into the plasma column. Experimental results show that the ratio of pinch to maximum currents for 60 nH is larger than for the two other external inductances. The effect of external inductance on the neon soft X-ray emission at constant pressure (0.25 Torr) and different voltages (10–13 kV) is investigated with a five-channel diode X‑ray spectrometer. Of the three external inductances, the average neon SXR yield has a maximum value at 11 kV for 40 and 60 nH, and 12 kV for 20 nH. The maximum neon SXR yield energy is 24.87 ± 2.52 J for the external inductance 20 nH at 12 kV and it is 23.62 ± 3.10 J for the external inductance 40 nH at 11 kV and 5.23 ± 1.15 J for external inductance 60 nH at 11 kV. Experimental results show that with increasing of external inductance, the maximum neon SXR decreases.

Nonlinear dynamics in non-volatile locally-active memristor for periodic and chaotic oscillations* *Project supported by the National Natural Science Foundation of China (Grant No. 61771176).

Complexity and abundant dynamics may arise in locally-active systems only, in which locally-active elements are essential to amplify infinitesimal fluctuation signals and maintain oscillating. It has been recently found that some memristors may act as locally-active elements under suitable biasing. A number of important engineering applications would benefit from locally-active memristors. The aim of this paper is to show that locally-active memristor-based circuits can generate periodic and chaotic oscillations. To this end, we propose a non-volatile locally-active memristor, which has two asymptotically stable equilibrium points (or two non-volatile memristances) and globally-passive but locally-active characteristic. At an operating point in the locally-active region, a small-signal equivalent circuit is derived for describing the characteristics of the memristor near the operating point. By using the small-signal equivalent circuit, we show that the memristor possesses an edge of chaos in a voltage range, and that the memristor, when connected in series with an inductor, can oscillate about a locally-active operating point in the edge of chaos. And the oscillating frequency and the external inductance are determined by the small-signal admittance Y(iω). Furthermore, if the parasitic capacitor in parallel with the memristor is considered in the periodic oscillating circuit, the circuit generates chaotic oscillations.

Novel Permanent Magnet Synchronous Motor With Integrated Filter Inductor, Using Motor's Inherent Magnetics

A close functional and structural integration of passive elements is required to improve the power density of motor drives. Such power-dense motor drives are prerequisites in aerospace and automotive applications. This article presents a permanent magnet motor with an integrated filter inductor, which not only eliminates inductor losses but also removes its associated weight and volume. The motor with an integrated filter uses motor's inherent magnetics in order to use it as a filter inductance instead of adopting an external inductor option, which is traditionally placed outside the motor. A vector-controlled model, taking modulation and switching effect into account, has been developed by using MATLAB/Simulink tool. To experimentally validate the concept of the motor with an integrated filter inductor, the winding connections of an existing motor are modified. The comparative analysis, between the traditional and integrated motor drive systems, is carried out in terms of the magnitude of switching component, total system losses, weight, and volume. The total losses in the motor with integrated filter are reduced by 34.2% at 2100 r/min and 3-N·m load, when compared to the motor with traditional filter inductor, whereas, its weight and volume in the motor with integrated filter inductor are eliminated completely.

Impact on ZVS Operation by Splitting Inductance to Both Sides of Transformer for 1-MHz GaN Based DAB Converter

Zero-voltage-switching (ZVS) of dual active bridge (DAB) converter and its range extension have been studied intensively. However, this article proves that the external inductance location, i.e., placing on which side of the transformer, does affect the ZVS operation due to transformers’ parasitic capacitances, in particular, at a high switching frequency of higher than 1 MHz. Thus, this article, for the first time, gives the mathematical model of the resonant transition during the dead time and thereby analyzes partial hard switching under different modulation schemes with consideration of transformer's parasitic capacitances. From the analysis of ZVS operation, the solution of splitting the interfacing inductance and placing them on both sides of the transformer is proposed and its associated methodology of selecting these inductances is introduced. It extends the ZVS for all the switching devices and, therefore, enhances the efficiency or moves losses away from the critical semiconductor devices. Finally, the theoretical analysis is verified by the experimental results from a 1-MHz gallium nitride based DAB converter prototype.

Optimizing Josephson-ring-modulator-based Josephson parametric amplifiers via full Hamiltonian control

Josephson Parametric Amplifiers (JPA) are nonlinear devices that are used for quantum sensing and qubit readout in the microwave regime. While JPAs regularly operate in the quantum limit, their gain saturates for very small (few photons) input power. In a previous work, we showed that the saturation power of JPAs is not limited by pump depletion, but instead by the high-order nonlinearity of Josephson junctions, the nonlinear circuit elements that enable amplification in JPAs. Here, we present a systematic study of the nonlinearities in JPAs, we show which nonlinearities limit the saturation power, and present a strategy for optimizing the circuit parameters for achieving the best possible JPA. For concreteness, we focus on JPAs that are constructed around a Josephson Ring Modulator (JRM). We show that by tuning the external and shunt inductors, we should be able to take the best experimentally available JPAs and improve their saturation power by $\sim 15$ dB. Finally, we argue that our methods and qualitative results are applicable to a broad range of cavity based JPAs.

Understanding the reduction of the edge safety factor during hot VDEs and fast edge cooling events

In the present work, a simple analytical approach is presented in order to clarify the physics behind the edge current density behavior of a hot plasma entering in contact with a resistive conductor. As has been observed in recent simulations [C. R. Sovinec and K. J. Bunkers, Plasma Phys. Controlled Fusion 61(2), 024003 (2019)], when a plasma comes in contact with a highly resistive wall, large current densities appear at the edge of the plasma. The model shows that this edge current originates from the plasma response, which attempts to conserve the poloidal magnetic flux (Ψ) when the outer current is being lost. The loss of outer current is caused by the high resistance of the outer current path compared with the plasma core resistance. The resistance of the outer path may be given by plasma contact with a very resistive structure or by a sudden decrease in the outer plasma temperature (e.g., due to a partial thermal quench or due to a cold front penetration caused by massive gas injection). For general plasma geometries and current density profiles, the model shows that, given a small change in minor radius (δa), the plasma current is conserved to first order [δIp=0+O(δa2)]. This conservation comes from the fact that total inductance remains constant (δL=0) due to an exact compensation of the change in external inductance with the change in internal inductance (δLext+δLint=0). As the total current is conserved and the plasma volume is reduced, the edge safety factor drops according to qa∝a2/Ip. Finally, the consistency of the resulting analytical predictions is checked with the help of free-boundary MHD simulations.

A Neutron Source With 10¹³ Neutron Yield and Ion Properties With Respect to Gas Pressure in a Spherical Plasma Focus

The effect of gas pressure on the neutron yield and ion properties is investigated in this article by using the developed model. The gas pressure range is from 1 to 40 Torr with 1-Torr increment in the spherical plasma focus device using an equal amount deuterium–tritium gas mixture. The beam-target neutron yield, beam-ion speed, beam-ion energy, plasma column ion density, beam-ion density, and plasma temperature are calculated with respect to gas pressure variation. Increasing the gas pressure leads to an increase in the neutron yield until 26-Torr gas pressure. But, beyond 26 Torr, increasing gas pressure results in decreasing neutron yield. This result indicates that the optimum gas pressure for neutron yield in the spherical plasma focus device is 26 Torr with $1.42 \times 10^{13}$ neutrons for used operating parameters, which are 25-kV charging voltage, 36-nH external inductance, and 432- $\mu \text{F}$ capacitor bank. This device has an 8-cm inner electrode radius and a 14.5-cm outer electrode radius. While beam-ion and plasma-ion densities increase with the gas pressure, the beam-ion speed and energy decrease. It is also found that the plasma loses less energy for higher gas pressures through radiation emissions compared to lower gas pressures. Since there is not enough published experimental data about spherical plasma focus devices, this article is conducted with the simulation of the spherical plasma focus device.

A 100-V Battery Charger Voltage Extender IC With 97% Efficiency at 4-A and ±0.5% Voltage Accuracy

This paper presents an IC that extends the voltage capability of a low voltage battery charger to 100V for accurately and reliably charging lithium ion (Li-Ion) battery stacks of up to 18 cells. The IC interfaces with a buck converter battery charger that utilizes external nFET control and an external inductor current sensing resistor. The voltage extender IC provides voltage level translation for the nFET control signals and the current sensing function while supporting an input power supply voltage of up to 100V and output battery voltage of up to 80V. The inductor current sense voltage is translated with a ping-pong amplifier capable of driving a bi-directional input voltage to a fully differential output with a maximum load current of 10 mA at 20 MHz bandwidth and less than $500~\mu \text{V}$ offset. The combined system of the voltage extender IC and battery charger achieved 97% efficiency at a 4-A charging current. The battery charging voltage accuracy was better than ± 0.5% at 80V.

A Hybrid Low-Cost Bandpass Filter With SAW Resonators and External Lumped Inductors Using a Dual-Coupling Scheme

A class of hybrid low-cost bandpass filter (BPF) with only two kinds of circuit components, straightforward design procedure, and miniaturized circuit footprint is presented. The proposed BPF is based on a hybrid module composed of one type of surface-acoustic-wave (SAW) resonator and one external lumped inductor. Compared with traditional SAW-resonator-based BPF devices, the use of a single-SAW-resonator model for its design reduces the cost and complexity by avoiding the need for well-matched SAW-resonator pairs. The engineered filter topology consists of a dual-path coupling scheme, in which one coupling path is simply a series-type SAW resonator and another path is made up of two SAW resonators that are intercoupled by means of an external inductor in the middle. Such coupling architecture generates two additional transmission zeros (TZs) that allow to increase the out-of-band power-rejection levels and enlarge the stopband bandwidth. A circuit analysis based on the even-/odd-mode method is applied to derive its equivalent circuit that can be directly matched to a conventional transversal filter topology. The obtained equivalent circuit readily illustrates the operational mechanisms of the proposed filter principle in terms of reflection zeros and TZs. Subsequently, the quality factors of its even- and odd-mode-subnetwork resonators are analytically derived, and the obtained numerical results determine the tradeoff existing when choosing the external-inductor value among various performance metrics. For experimental validation purposes, two 418-MHz BPF prototypes formed by one and two in-series-cascade-connected second-order filtering units, respectively, are manufactured and tested. The circuit footprints of these filters are largely reduced by using a three-layer lamination technique for their physical implementations. The measured results show sharp-rejection filtering responses and are in close agreement with the theoretical predictions.

104 Optimization of handheld Wand to Activate a Shape Memory Penile Prosthesis

We previously described a novel shape memory alloy penile prosthesis that could be activated using an external wand via magnetic induction, thus obviating the need for internal hydraulics, pumps and reservoirs found with inflatable penile prostheses. Optimally, this wand would be portable, battery-powered, quick and easy to use. Herein, we characterize the parameters required to optimize the external wand for touchless activation of this novel shape memory penile prosthesis. Using a commercially purchased external inductor (Miniductor II) with 1000Watt of maximum power, we measured the time of activation of the SMA prosthesis. We compared the time of activation of the existing design (fig 1b) vs an alternate design with circumferential cross section (fig 1c). Activation is reached when the Nitinol component of the prosthesis reaches the full activation temperature of 42C. The time of activation and temperatures were measured with the use of thermocouples on the spine of the prosthesis. Additional parameters examined included distance, angle and shape of the coils (ring or flat).

A Corrosion Detection Method for Steel Strands Based on LC Electromagnetic Resonance

At present, prestress detection is a worldwide problem. Corrosion has an important impact on the accuracy of the stress detection results of prestressed tendons. Once the steel strands in service is corroded, stress corrosion will occur, which seriously affects the safe operation of the prestressed structure. Based on the LC electromagnetic resonance circuit to detect the prestressing force of steel strands, this research has been successfully applied to the detection of the corrosion rate of steel strands, which lays the foundation for the nondestructive detection of the healthy state of steel strands in the existing structure. In this study, the steel strands were regarded as an external inductor embedded in the LC resonance circuit. After the steel strands was corroded, its electromagnetic characteristics would change, and this change was manifested by the resonance frequency. In this paper, the regular change of the resonance frequency caused by the change of the inductance of the steel wire after corrosion was explained theoretically, and a theoretical model of the relationship between the electromagnetic resonance frequency and the corrosion rate was established. In this study, it was proved through experiments that the LC electromagnetic resonance method can accurately detect the overall corrosion degree of bare steel stranded wires, and a fitting formula for corrosion detection of steel stranded wires was established. Through the analysis and exploration of the test data and test phenomena, it has been found that the action mechanism of the stranded wire decreases with the increase of the corrosion rate and the inductance thereof, which leads to the increase of the resonance frequency. The discovery of these laws will provide an improved basis for the prestress detection of in‐service steel strands by LC resonant circuits and make the method to be further applied to practical engineering.

Design and Optimization of Three-Phase Dual-Active-Bridge Converters for Electric Vehicle Charging Stations

In this paper, design and optimization method of a three-phase dual-active-bridge DC/DC converter is discussed. Three single phase transformers connected in star-star configuration were designed with large leakage inductance aiming to eliminate the need for external inductors. Switching frequency, peak flux density, number of turns, number of layers, etc., were optimized using non-linear programming technique for minimizing the overall converter loss. Experimental results on a 10 kW prototype show that the optimized converter can operate efficiently an efficacy of up to 98.65% and a low-temperature rise of less than 70 degrees Celsius on both transformers and semiconductor devices.