Variable Induction Research Articles

Gate Drive Circuit Implementation for Parallel Connection of Power Devices Considering Parasitic Inductance

SiC devices are potential future power devices because of their higher switching speed and lower ON resistance than those of Si devices. Research and development efforts to apply them in medium- and large-capacity power conversion circuits are underway. However, SiC power devices in TO packages, which are general-purpose packages, are difficult to apply in high-current applications owing to their low current ratings. Therefore, increasing the capacity of power devices by connecting them in parallel is being studied. However, the current imbalance during switching due to the differences in device characteristics and variations in parasitic inductance is problem. This study proposed a current-balancing procedure focused on the parasitic inductances around power devices and gate drive circuit implementation. The proposed method was verified by conducting double-pulse tests at 300V and 200A.

Staggered compensation of a multi-tube load curve with height difference and variable induced ring distribution

To solve the problem of high energy absorption conflicting with small load fluctuation, a multi-tube combined energy absorption structure with induced ring based on the load curve staggered compensation strategy was proposed. The effects of the number, height, and thickness of the induced rings on the load curve trend were investigated by experiment and simulation, and the initial structural parameters suitable for the design of load curve staggered compensation. were determined. Then, the influences of height difference and induced ring distribution on the load curve trend were revealed, and the control method that can make the appropriate difference in each tube load curve was summarized. Moreover, the diagram of the correlation between the key multi-tube combination parameters and the load curve control effect was plotted based on classical theory and the acquired temporal influence. Finally, a multi-tube structure with suitable height difference and variable induction ring distribution was proposed. Compared with the multi-tube structure with the same configuration parameters, the combined structure proposed in this study decreases the initial peak and load fluctuation by 49.45% and 58.93%, respectively, while maintaining a high energy absorption.

Novel filter approach for ripple-free input current boost converters based on variable inductors

Novel filter approach for ripple-free input current boost converters based on variable inductors

A 4.12 GHz, 3.3 mW VCO with 87.9% tuning range using a transformer-based variable inductance

A wide-band LC-tank CMOS voltage controlled oscillator (VCO) employing a transformer-based variable inductance structure is presented. The variable inductance is obtained through a switching scheme that controls the current path in a transformer and allows four different inductances to be delivered by the structure. Additionally, an electric model of the transformer obtained through the simulated data and equations based on its physical properties is proposed. The inductance and quality factor from the variable structure were extracted from the transformer’s electromagnetic simulations and model’s scattering parameters. The model showed and error lower than 4% in all modes of operation inside of the desired range (from 1 to 6 GHz). The proposed VCO is simulated and shows a percentual tuning range of 87.9% around a central frequency of 4.12 GHz, while consuming less than 3.3 mW of power and exhibiting a maximum phase noise of -108 dBc/GHz occupying an area of 0.45 mm2.

Mathematical Model and Simulation Based on ANSYS Maxwell of the Magnetic Fluid Differential Transformer Inclination Sensor

A mathematical model of a mutual inductance magnetic fluid inclination sensor is established. The sensing element of the sensor is magnetic fluid. The composite magnetic core suspended in the magnetic fluid increases the permeability of the medium in the winding. The total magnetic induction intensity B in the winding is composed of two parts: the excitation magnetic induction intensity Bl and the additional magnetic induction intensity Ba generated by the magnetization of pure iron. The sensitivity S of the sensor and its influencing factors are derived. The output characteristics of the sensor are analyzed using ANSYS Maxwell simulation software. The results show that the variable resistance of the measuring circuit can eliminate the residual voltage at zero point, and the output voltage carrier after filtering and rectification is positive half cycle; The addition of pure iron to the magnetic core greatly increases the mutual inductance variation between the primary and secondary windings, and the inclination angle in a small range is linear with the mutual inductance variation; The recovery force of the composite core is proportional to the displacement.

Robust Maximum Efficiency Tracking Control of Wirelessly Powered Directly Supplied Heart Pumps

In recent times, wireless power transfer systems have been identified as a reliable option to supply power to medical implants. Up to now, Wireless Power Transfer Systems (WPTS) have only been used to charge batteries of low-power medical implants. However, for medical implants requiring a relatively higher power, such as a ventricular assist device, which is an implanted blood pump in the patient’s abdominal cavity, an external power supply has been used. When WPTS is used for medical implants, it increases the number of required power converter stages and hardware complexity along with the volume, which tends to reduce the overall efficiency. In addition, the existence of uncertainties in WPTS-based medical implants, such as load and mutual inductance variations, can lead to system instability or poor performance. The focus of this paper is to design a WPTS to supply power to the pump motor directly through its inverter based on the requirements of the motor drive system (MDS) without resorting to an additional DC-to-DC converter stage. To this end, the constraints that the drive system imposes upon WPTS have been identified. In addition, to make a reliable closed-loop operation, a µ-synthesis robust controller is designed to make sure the system maintains its stability and performance with respect to the system’s existing uncertainties. A number of experimental results are provided to verify the effectiveness of the adopted WPTS design approach and the corresponding closed-loop controller for WPTS. Furthermore, the experimental findings for the maximum efficiency tracking (MET) approach (to minimize WPTS coil losses) and constant DC link voltage control approach are shown and compared. According to experimental results and system efficiency analysis, the former appears to perform better. The system dynamic performance analysis, on the other hand, demonstrates the latter’s advantage.

Metamodel of Parametric Geometric Magnetostatic Problem Based on PGD and RBF Approaches

In order to reduce the computational time induced by solving a finite element (FE) model for a magnetostatic problem with varying geometric parameters, a parametric geometric metamodel is defined using the proper generalized decomposition (PGD) approach. The mesh deformation associated with the geometric variation is implemented using the radial basis functions (RBFs) interpolation method. The proposed approach is applied to a variable inductance and then to a permanent magnet synchronous machine (PMSM). The results show that the PGD metamodel can accurately approximate the FE solution for the case of parametric geometric problems.

Floating Interleaved Boost Converter with Zero-Ripple Input Current Using Variable Inductor

A zero-ripple input current is known to improve the lifetime of battery sets and fuel cells and to assure maximum power point tracking in PV panels. To perform current ripple elimination in a floating interleaved boost converter (FIBC), one of the typical linear inductors is substituted by a variable inductor, and phases of the converter have complementary duty cycles. This variable inductor is controlled using a switched current-source converter, which adjusts the input current ripple. An equivalent model for the variable inductor is presented, including uncertainties in the component description. To achieve current stabilization, a variable inductor controller was designed using the sliding modes approach via fixed frequency. An experimental prototype is implemented and tested with an output voltage controller to compare with the conventional FIBC. The results demonstrate that the input current ripple of the proposed converter is eliminated without significantly decreasing the efficiency.

Variable inductive shape memory spring based multifunctional module for high sensitivity measurements

Shape memory elements as sensing units have promising potential; the prospect of using shape memory alloy coil as a multi-functional module using the inductive principle is assessed in this work. The self-sensing phenomenon in SMA is dominantly explored from the change in electrical resistance, however, the same can be realized from the variation in inductance in its coiled form. This article introduces a unique, variable inductive sensing system using an SMA spring for high sensitivity measurements, performance of which greatly relies on its coil geometry and permeability. The configuration enables the sensing operation at an isothermal condition for testing force, displacement, and as a proximity sensor. Experimental verification of the proof-of-concept for sensitivity enhancement reveals that adding an iron core results in a sensitivity of 0.1 μH/0.1 N and 0.16 μH/mm, for force and displacement sensing respectively which is a twofold increase over the system's sensitivity with an air core.

A Control Parameters Self-Adjusting Method for photovoltaic inverter considering the variation of inductance

The variation of inductance is the reason for the instability of photovoltaic (PV) inverter system. To this end, a control parameters self-adjusting method considering the variation of inductance is proposed to enhance the anti-interference ability. The basic control method is to use grid-connected current control and capacitor-current-feedback method to suppress resonance. Based on the Routh Criterion (RC), a simple Routh Array enumeration rule is proposed. Discrete Routh Criterion (RC) is selected as the stability analysis method to obtain the stability range of the control parameters. The control parameters self-adjusting method can enhance the anti-interference ability of system under variations of inductance, which is proved by comparative experiments.

Impact of the variation of capacitance, inductance, and resistive load on the behavior of buck converter

This paper deals with the structure of the buck converter circuit and the influence of the inappropriate values of its electrical components on the trend of its output voltage. In this perspective, a further study is established on the variation of the inductance, the capacity and the load. As a result, an observation of their impacts on the behavior of the converter is performed. Therefore, when the inductance value is low and the capacitance value is defined as large, the system tends to be more stable and faster. The optimal values of these two components have been considered within the converter circuit in order to closely observe the output response. Indeed, the obtained response has been the most stable and the faster. In this context, a comparison has been made between the calculated values and those obtained during the simulation on Matlab/Simulink. A small difference is observed between the both. On the other hand, the variation of the load resistance only influences the stability of the system, seen clearly for important values.

Geographic variation in induction of labor at 39-weeks in low-risk nulliparas across the United States

To investigate geographic variation in induction of labor (IOL) at 39-weeks gestation in low-risk nulliparas across the U.S. Data was collected from 2020 U.S. Vital Statistics birth certificates. Inductions and cesarean deliveries (CD) were examined in “low-risk” term (39-42 weeks of gestation) nulliparas, where “low-risk” was defined as patients without gestational or pre-gestational diabetes, chronic hypertension, or hypertensive disorders of pregnancy whose neonate was a vertex-presenting, non-anomalous singleton with birthweight 2500 to 5000 grams. We analyzed variation in 39-week induction rates in this population and whether this varied by various geographic regions, including the states, census divisions, and metro and urban characterization. We explored whether this variation was correlated to variation in cesarean delivery using Spearman Correlation testing. P-values < 0.05 were considered statistically significant. Rates of overall induction of labor at 39-42 weeks varied widely, from 14.2% to 59.1% across states (median 39.8%; IQR 37.0-49.0%). Similarly, rates of labor induction at 39 weeks specifically varied across states from 6.8% to 38.3% (median 17.9%; IQR 12.9-23.4%). Total induction rates and 39-week inductions rates were highly correlated across states (weighted Spearman correlation coefficient 0.90; p< 0.01) (Figure). Cesarean deliveries varied across states from 15.5% to 28.1%; however, this variation was not correlated with the variation in either total or 39-week inductions (p=0.61 and p=0.17, respectively). There was wide variation in 39-week induction rates at every geographic level (Table), varying up to 3-fold across census division from 9.7% in the Pacific to 30.2% in the East South Central. There is significant variation in rates of induction of labor at 39-weeks in low-risk nulliparous patients across the US. While this did not appear to correlate with variation in cesarean delivery, the reasons for this wide practice variation and implications on health and resource utilization should be further explored.View Large Image Figure ViewerDownload Hi-res image Download (PPT)

Three-Phase Four-Wire Inverter for Grid Emulator Under Wide Inductance Variation to Evaluate the Performance of Distributed Generator

This paper presents a three-phase four-wire inverter to generate voltage sources under wide filter inductance variation. The voltage sources with distortion and unbalance are to emulate grid voltages. The distortion includes voltage sags, voltage swells, and harmonic components, and the unbalance includes voltage and phase-angle differences. With a conventional PI control and direct digital control (DDC) only, the voltage distortion cannot fulfill precisely because of the improper controls. While with the proposed modified direct digital control (MDDC) and harmonic-angle adjustment algorithm, the soft core saturation can be taken into account and the harmonic voltage distortion can be accurately emulated, respectively. Moreover, the proposed control scheme can achieve fast transient response. The control law is derived and the inverter with the control to generate grid voltage is described in detail. Simulated and experimental results from 10 kW prototype have verified the analyses and discussions

Applied of Synthesis Furfural Based on Cassava Stems (Manihot utilissima) As Fuel Additive to Gasoline

Biofuel is an option to reduce CO2 generated by vehicles. In this study, synthetic crude furfural from cassava stems was blended as fuel additive to gasoline (Pertalite) and then induced by electromagnetic field. Analysis were carried out on engine performance and exhaust emissions produced by Kohler engines. Variations formed by samples crude furfural and commercial furfural (C5H4O2), then time variations of electromagnetic induction for 0 and 30 minutes. The blending composition of gasoline and furfural in a mixture of 1,500 ml fuel is 96% : 4%. The best results from increasing torque, cranking power and saving fuel consumption were obtained from variations in the use of crude furfural additives induced by electromagnetic fields (CFE). Exhaust emissions produced by pure Pertalite are still lower than fuels with furfural additives. The content of water and impurities in crude furfural causes the additive unmixed with Pertalite which is non-polar and hydrophobic.

Induction of genetic variability with gamma radiation and detection of DNA polymorphisms among radiomutants using sequence-related amplified polymorphism markers in Gaillardia pulchella Foug. plants

Induction of genetic variability with gamma radiation and detection of DNA polymorphisms among radiomutants using sequence-related amplified polymorphism markers in Gaillardia pulchella Foug. plants

A Low Gain Variation LC-VCO With Mutual Inductive Tuning for K VCO Linearity Compensation

A high-linearity LC-voltage-controlled oscillator (LC-VCO) with a mutual coupled inductive tuning technique is proposed to reduce VCO-gain ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$K_{\mathrm {vco}}$ </tex-math></inline-formula> ) variation induced by varactors in finite linear region. The oscillator is fabricated in a standard 180-nm CMOS process occupying 0.88 mm <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\times0.9$ </tex-math></inline-formula> mm and consuming 3.6 mW from mixed 0.9/1.8 V supply voltage. With the variable effective inductance of the resonant tank, the proposed topology achieves a low gain variation of less than 6.1%, possessing a linear-tuning control voltage range from 0.5 to 1.8 V and operating from 3.40 to 4.04 GHz. The phase noise is measured to be −108.59 dBc/Hz at 1 MHz offset with a carrier frequency of 4.04 GHz, and the figure of merit (FoM) is −173.8 dBc/Hz.

A simulation method for the electromagnetic railgun based on equivalent circuit

As a typical electromagnetic launcher, electromagnetic railguns have attracted widespread attention for their broad military application prospects. It is known that skin effects occur during electromagnetic railgun launch. How to quickly and accurately simulate these skin effects is of importance for the application of electromagnetic launch technology. This paper proposes a static two-dimensional finite element model in series with one variable equivalent inductance and three resistances for simulating the dynamic electromagnetic railgun launch. Two skin effects are presented by changing equivalent inductance and resistances. For an electromagnetic railgun including two rails of length of 2 m and width of 0.3 m and square armature of 0.3 m long, after 4.23 ms under a pulse current of a peak of 1 MA, the simulation results based on this proposed static 2D model show that the armature can leave the rails with a velocity and acceleration increasing to 1,464 m/s and 614,876 m/s2, respectively. For an equivalent circuit connected in series, the equivalent inductance, AC resistance, velocity skin effect resistance, and back EMF resistance are 0.49 μH, 2.5 mΩ, 7.1 mΩ, and 4.44 mΩ, respectively, whereas the breech voltage can increase to 1.36 kV. The proposed method simplifies the meshing in the finite element model, saves computational cost, and is conducive to study electromagnetic railgun design and projectile magnetic field shielding. Key words: Electromagnetic railgun, equivalent inductance, equivalent resistance. Tables 1, Figs 7, Refs 10.

Coupled Inductors With an Adaptive Coupling Coefficient for Multiphase Voltage Regulators

As modern microprocessors continuously advance, a high-efficiency, high-power-density voltage regulator design with fast transient response is a must. Compared with the non-coupled-inductor-based solution, a multiphase buck converter with an indirect-coupled inductor (ICL) can dramatically improve the circuit transient response without increasing the inductor current ripple and sacrificing efficiency. However, a design conflict between the steady-state performance and transient response exists for the conventional ICL structure with a given inductor size. This article first analyzes the benefits and limitations of the conventional ICL based on a detailed modeling process. Then, an adaptive-coupled inductor structure is proposed to solve the issue. This is realized by applying a variable inductor in the extra winding loop of an ICL. By self-adjusting the coupling coefficient, the proposed structure can further improve the circuit transient response without increasing the phase inductor current ripple. A four-phase buck converter with the proposed inductor structure is experimentally tested, and it shows that a 25.6% output voltage overshoot reduction or a 21.8% output capacitance reduction can be realized by the proposed coupled inductor structure.

Model Validation of Synchronous Motors With a New Standstill Measurement Technique

Permanent magnet synchronous machines (PMSM), synchronous reluctance machines (SynRM), and electrically excited synchronous machines (EESM) are widely used in the industry and transportation sectors. Their rotors are often equipped with conducting parts like permanent magnets, thick rotor laminations, damper windings, or a conducting sleeve, or they even have a solid rotor core. Such conducting elements do not allow applying standard AC supply techniques for inductance measurements because of the alternating flux induced by eddy currents. We propose a new technique for inductance measurement at a standstill with a quasi-static voltage supply, which mitigates the eddy current phenomenon. The inductance is measured at several rotor positions over a complete electrical cycle, which allows to proceed with a harmonic spectrum analysis of the inductance variation. With this information, it is possible to estimate motor performance characteristics, such as optimum torque, voltage control, power factor, and torque ripple. The new technique is experimentally validated on a 12 kW axially laminated anisotropic solid-rotor high-speed SynRM. In principle, the method also suits PMSMs, EESMs, and other synchronous machines (not verified in this paper). Experimental validation with a solid-rotor SynRM shows a good correspondence with the simulation. Furthermore, the torque computed using the measured inductance is very similar to the experimental one confirming the effectiveness of the method.

A Self-Tuning LCC/LCC System Based on Switch-Controlled Capacitors for Constant-Power Wireless Electric Vehicle Charging

In this article, a self-tuning <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">LCC/LCC</i> wireless power transfer system based on switch-controlled capacitors is proposed to maintain a high power factor on the primary inverter side and fixed output power on the secondary side against self or mutual inductance variation of the magnetic coupler. The PI control on the primary side and the method of gradient descent on the secondary side are proposed based on the proposed normalized mistuned <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">LCC/LCC</i> circuit model. Only two switch-controlled capacitors on each primary and secondary side are used to implement the control scheme without the Wi-Fi communication or parameter identification. A 3 kW experiment setup was built in the lab and two different magnetic shields, namely ferrite and nanocrystalline, were tested on the secondary pad. According to the experiment results, the proposed system is proven to be able to maintain a high power factor (>0.9) and the desired dc output power against 52% mutual inductance variation and 12% self-inductance variation of the secondary pad. The proposed system can be applied as a wireless charger for electric vehicles or a high-power wireless charger test bench.