Series Capacitor Research Articles

Tracking and Dynamic Tuning of a Wireless Powered Endoscopic Capsule

This work presents an inductive wireless power transfer system for powering an endoscopy capsule supplying energy to power electronic devices allocated inside a capsule of ≈26.1 mm × 9 mm. A receiver with three coils in quadrature with dimensions of ≈9 mm × 9 mm × 10 mm is located inside the capsule, moving freely inside a transmitter coil with 380 mm diameter through translations and revolutions. The proposed system tracks the variations of the equivalent magnetic coupling coefficient compensating misalignments between the transmitter and receiver coils. The power on the load is estimated and optimized from the transmitter, and the tracking control is performed by actuating on a capacitance in the matching network and on the voltage source frequency. The proposed system can prevent load overheating by limiting the power via adjusting of the magnitude of voltage source . Experimental results with uncertainties analysis reveal that, even at low magnetic coupling coefficients k ranging from (1.7 × 10, 3.5 × 10), the power on the load can be held within the range of 100–130 mW. These results are achieved with any position of the capsule in the space, limited by the diameter of the transmitter coil and height of 200 mm when adjusting the series capacitance of the transmitter in the range (17.4, 19.4) pF and the frequency of the power source in the range (802.1, 809.5) kHz.

Dual composite right/left‐handed unit with improved spurious performance and its application in wide‐stopband bandpass filter

AbstractA compact dual composite right/left‐handed (D‐CRLH) unit with improved spurious performance is presented in this study. The proposed D‐CRLH unit consists of an interdigital capacitance (IDC) and a microstrip section inductor (MSI). Compared with the traditional IDC, the proposed IDC is improved by connecting the ends of the alternate fingers through the metallic paths on the back of the substrate. Thus, the spurious resonance at low frequency is eliminated and the usable bandwidth of the IDC is extended. The meander slots are also exploited in each finger of the IDC to increase the series capacitance, which contributes to reducing the circuit size. Furthermore, the proposed D‐CRLH unit is applied in the wide stopband bandpass filter (BPF) design to demonstrate its practicability. The BPF is fabricated and measured for demonstration. The measured results are in good agreement with the simulated results.

Optimal Location for FACTS Devices: Hybrid Algorithm to Improve Power Flow and System Security

In this study, an efficient and reliable algorithm known as Jaya Algorithm-enabled Flower Pollination Algorithm (JA-FPA) is introduced for enhancing the Optimal Power Flow (OPF) and system security by a multi objective model. The multi-objective model is first derived based on entropy of individual objectives such as the Voltage Stability Index (VSI), Power Loss Index (PLI), Line Collapse Proximity Indexes (LCPI), severity and TCSC cost. Multi- objectives are achieved by optimizing the location as well as size of Flexible Alternating Current Transmission System (FACTS) devices in the test bus system. Consequently, the most popular and ubiquitous component of the FACTS equipment category, the Thyristor Controlled Series Capacitor (TCSC), is utilized in this study. The best solution with optimal sizing and allocation of TCSC devices for achieving the aforesaid objectives is chosen from the JA-FPA optimized outputs. The proposed model is performed on two benchmark test bus systems. The adopted model is distinguished with conventional models, and the results are obtained to analyze its effectiveness. In particular, the computational time of proposed model is is 1.74%, 2.52%, 1.13%, 0.63%, 50.15%, 2.36%, 3.83%, 6.00%, 2.79%, and 7.57% superior to existing GWO, WOA, DA, FPA, JA, PSO + GSA, PSO, Henry gas, GA, and TLBO approaches.

A FRACTAL MINKOWSKI DESIGN FOR MICROWAVE SENSING APPLICATIONS

This work describes a low-cost, extremely sensitive microwave sensor that may be used to distinguish between different liquid samples by measuring the variation in S21 magnitude. An interdigital capacitor (IDC) in series with a circular spiral inductor (CSI) and linked directly to a light dependent resistor (LDR) is used to do this and been installed minkowski farctal on end both stub. The suggested sensor operates at a frequency of 1.47 GHz. Using Computer Simulation Technology (CST) Microwave studio, the impacts of modifying the proposed LDR's value are evaluated parametrically. However, When the LDR value changes in relation to the light of incidence, a considerable change in the resonance band is observed. Many recent wireless technologies that use optical-based interface systems have found that such technology is an excellent candidate. The same model is developed for validation using a High-Frequency Simulator Structure (HFSS). The suggested sensor is built on an FR4 substrate with a 40×60 mm2 surface area. As a ground plane, a copper layer is applied to the rear panel. The results obtained by the two software systems are in perfect agreement.

Charging a Capacitor with Another Capacitor by Using Arduino

Resistor–capacitor (RC) circuit labs help students, but most courses don’t include them because of complications and cost. This work presents an easy and inexpensive Arduino-based lab on the charge and energy transfer between two capacitors with different values of the initial electric charge when they are connected through a resistor. Capacitors are electromagnetic devices widely described in calculus-based introductory physics courses. The concept of capacitance, the determination of the capacitance in planar and cylindrical geometries, the description of the series and parallel combinations of capacitors, or the evaluation of the electric energy stored in them are classic topics studied under electrostatic equilibrium conditions. Charge and discharge of a capacitor through a resistor is also studied in order to experimentally determine the capacitance of the capacitor or measure the electric charge stored in it. Energy balances in the charging and discharging processes of a capacitor are also widely discussed in textbooks. To get a better understanding of the basic concepts, other complex exercises are included in these courses. Among them, one can find the determination of the final charge and energy stored in each of the two capacitors, with different initial charge states, which are combined in parallel. In addition, the study of the charge through a resistor of a discharged capacitor by using a charged capacitor is also a classical exercise when one studies in depth the RC circuit. However, lab exercises covering these last topics are lacking in introductory physics courses. This is mainly due to the need to use complex experimental setups to simultaneously handle various power sources and various multimeters.

Development of a generator for percussive ultrasonic drills used in asteroid exploration based on impedance characteristics analysis

Percussive ultrasonic drills participate in asteroid exploration missions. Since space environments are complex and working loads vary dramatically, it is necessary to design a drive that better matches the percussive ultrasonic drill to make it achieve high-speed drilling with low power consumption. Impedance characteristics under different load conditions and the load varying in one drilling cycle are investigated based on analyzing the working principle of the percussive ultrasonic drill. An ultrasonic drill driver with automatic scanning resonant frequency and digital phase-locked loop frequency tracking control is designed according to the load characteristics. Series capacitance impedance matching ultrasonic drills is experimentally studied. Vibration amplitude and impedance characteristics of the ultrasonic drill driven by the designed driver are measured to evaluate the frequency tracking ability and the impedance matching. Finally, ultrasonic drilling experiments are conducted in room, low, and high temperature environments to investigate the driving performance. Under room temperature and 5 N drilling pressure, the speed of ultrasonic drilling into soft sandstone is 52 mm/min, and the power consumption is less than 70 W. The experimental results indicate that the designed driver can drive the percussive ultrasonic drill to achieve stable and high-speed drilling with low power consumption and low drilling pressure.

Optimal Power Flow Incorporating Thyristor-Controlled Series Capacitors Using the Gorilla Troops Algorithm

The optimal power flow issue (OPFI) can be solved in this work using the recently developed algorithm, gorilla troops algorithm (GTA). The goal of OPFI is to reduce numerous functions such as minimizing fuel costs, emissions, and power losses and improving the voltage stability related to electric power networks (EPNs). The GTA is inspired by gorillas’ social habits, which include migration to a strange region, migration toward a specified spot, traveling to other gorillas, competing for adult females, and escorting the silverback. The developed GTA is tested with and without the inclusion of the Thyristor-Controlled Series Capacitor (TCSC) devices in the system. The proposed GTA is applied on a practical Egyptian West Delta-EPN (WD-EPN) and the standard IEEE 57-bus EPN and with and without the inclusion of the TCSC devices to appraise the GTA algorithm’s performance in the OPFI. In addition, the proposed GTA is applied on a large-scale IEEE 118 bus system with higher outperformance compared to particle swarm optimization. The results illustrate that the fuel costs, emissions, voltage stability, and power losses are reduced for the standard IEEE 57-bus EPN with and without TCSC devices by a percentage of (18.847% and 18.818%), (59% and 58.97%), (13.405% and 11.507%), and (64.337% and 65.178%), respectively, while fuel costs, emissions, voltage stability, and power losses are reduced for WD-EPN with and without TCSC devices by a percentage of (8.547%, 8.565%), (13.641%, 13.6%), and (61.949%, 61.954%), respectively. A comparison study is conducted to demonstrate the GTA’s effectiveness when compared with other recently developed algorithms such as improved Salp Swarm Algorithm, quasi-reflection jellyfish search, Salp Swarm Algorithm, improved heap-based algorithm, bat search algorithm, social network search algorithm, electromagnetic field optimization, and other well-known algorithms as well. According to the comparison with these algorithms, the GTA demonstrates the best results among the attained results.

Interoperability study of wireless charging system with unipolar and bipolar coils based on capacitor–inductor–capacitor–capacitor–series​ topology

Wireless charging for electric vehicles (EVs) enjoys advantages such as automation, safety, and convenience. For the most popular magnetic induction wireless power transfer (WPT) technology, different coupled coils are utilized such as the unipolar coil, the bipolar coil, and the quadruple coil. Thus, the interoperability of different coil types should be solved. Particularly, the transmitter should be interoperable with different receiving coil types, able to charge different EVs This paper proposes an interoperable solution for the two most popular coil types: the unipolar coil and the bipolar coil. The unipolar and bipolar coils are adopted on the transmitter side. Based on the transmitter-side capacitor–inductor–capacitor–capacitor (CLCC) compensation and the alteration of the switching pattern, when the receiving coil is a unipolar coil, the transmitter-side unipolar coil can work as the power transmission coil and the bipolar coil can work as the compensating inductor; when the receiving coil is a bipolar coil, the transmitter-side bipolar coil can work as the power transmission coil and the unipolar coil can work as the compensating inductor. In this way, the transmitter can be interoperable with the unipolar or bipolar receiving coil. The mathematical mode is built. A simulation model and an experimental prototype is established to validate the effectiveness of the proposal. The experimental results show that the interoperability of the receiver-side unipolar or bipolar coil can be achieved.

Equivalent circuit model for reflective polarization converter based on anisotropic metasurfaces

A simple equivalent circuit model (ECM) for a reflective polarization converter (RPC) comprising anisotropic metasurfaces is presented in this paper. The impedance matrix of an anisotropic metasurface in x and y axis is derived by the impedance matrix in a diagonal axis multiply with a rotated matrix, while the diagonal impedance matrix can be calculated by a simple LC network, which contains a series of capacitors and inductors. The presence of the dielectric substrates is considered using the transmission line theory. Some typical RPCs with different metasurface shapes are used to verify the effectiveness of the ECM. The methodology provides a simple approach for the design and optimization of RPC. Finally, we designed a polarization converter based on the proposed method, and the measured results are in good agreement with the theoretical results.

Variable Turn-OFF Gate Voltage Drive for Voltage Balancing of High-Speed SiC MOSFETs in Series-Connection

Active gate drive with high accurate and self-adaptive closed-loop control is a promising approach to solving the imbalanced voltage problem of series-connected silicon carbide (SiC) <sc xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">mosfet</small> s. However, due to the inherent time propagation mismatching between Si- and SiC-based devices, behavior adjustment through Si-based ICs during the switching transient takes at least tens of nanoseconds, which limits the minimum allowable turn- <sc xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">off</small> time of each series unit. In this article, a novel active gate drive with a variable gate voltage regulator (GVR) is proposed. It uses a single P-channel <sc xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">mosfet</small> to determine the connection timing of a precharged capacitor in series with the input capacitance in which way the switching transient of each device in the stack is adjustable. It is more advantageous when applied to the low-power SiC <sc xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">mosfet</small> applications with relatively smaller external gate resistors. Two sampling and voltage balancing control circuits based on different processors are proposed for the GVR to adapt to different switching frequencies and costs. Its operational principle and design guidelines are specified and its performance on voltage balancing control is experimentally verified. Analytical assessment on switching losses and costs, compared with the previous work, is provided.

Investigation of Distribution System Stability with Incorporation of Capacitor Switching: A Case Study of Monatan 11 Kv Distribution System

Effectiveness of an electrical distribution system depends on the stability of its voltage profile. Several methods such as Static Compensator (SC), Thyristor Controlled Series Compensation (TCSC) and Series Capacitor have been applied for the stability of the system. However, these methods have been characterized by harmonic variation and low efficiency. Therefore, this research paper applied Shunt Switching Capacitor (SSC) on 11 kV distribution system located at Monatan, Ibadan, Oyo State in order to investigate the stability of the system during outages. Hourly data on bus voltage of the system were collected to determine the average bus voltage and voltage drop of the distribution system for stability evaluation using IEEE statutory limits method. Load Flow Model (LFM) of the distribution system was developed with incorporation of Capacitor Switching Compensation (CSC). This was solved using Kirchoff’s Current Law( KCL) analysis to improve the average bus voltage and voltage drop of the distribution system while simulation was done using MATLAB R2015a. The results of the average bus voltage and voltage drop of the distribution system were 10.5 and 4.2 , respectively. The CSC model improved the average bus voltage and voltage drop by 6 % and 33 % respectively. The research showed that incorporating capacitor switching as a compensation technique enhanced the stability of the distribution systems. The research is useful in the planning and optimization of electrical distribution systems. Keywords: Electrical Distribution System, Voltage, Capacitor Switching Compensation, Load Flow Models, Monatan 11 kV Distribution System, Voltage Drop, MATLAB. DOI: 10.7176/NCS/14-02 Publication date: August 31 st 2022

Analysis and Design of a Two-Phase Series Capacitor Dual-Path Hybrid DC-DC Converter

Inthis article, a two-phase series capacitor dual-path hybrid dc–dc converter with the step-down ratio of less than 1/6 is proposed for the first time. In this converter, the output current is divided into capacitance- and inductance-path, so the average value and ripple of inductance current are reduced. On the same time, the conduction loss caused by inductance equivalent series resistance (ESR) is also reduced. The addition of series capacitor leads to desirable characteristics, including lower switching stress, switching loss, parasitic output capacitance loss on <sc xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">mosfet</small> , automatic phase current balancing, duty ratio extension, etc. A 120 W prototype has been designed to demonstrate theoretical analysis. Obtained efficiency was up to 93.18% at full load. Experimental results show good agreement with theoretical analysis and high feasibility of proposed converters.

Condition Monitoring of DC-Link Electrolytic Capacitor in Back-to-Back Converters Based on Dissipation Factor

Condition-monitoring systems are used to determine the best timing for predictive maintenance of power electronics converters. These monitoring systems can significantly reduce the converter repair time and increase system availability. In this article, an investigation has been conducted on the possibility of using the dissipation factor as a lifetime indicator of electrolytic capacitors. A criterion is also proposed based on the dissipation factor to detect electrolytic capacitors’ end of useful life. A method has been presented for measuring the dc-link capacitor dissipation factor in a back-to-back converter. Using this technique, it is possible to estimate the switching component of the capacitor current by measuring the output currents of the converter without a need to measure the capacitor current directly. The proposed method is simulated, and the impact of various factors, such as switching frequency, capacitor series inductor, and the network filter on the accuracy of the dissipation factor measurement, is discussed. Experimental results are also provided to validate the acceptable accuracy of the proposed method.

Analysis and implementation of an isolated high step‐down converter with interleaved output for low voltage applications

AbstractThis paper proposes a new isolated high step‐down dc‐dc converter with a more extensive output range and high efficiency. The interleaved output and ZVS‐ZCS switching for all semiconductors have made the converter appropriate for high output current applications. An auxiliary inductor is used to achieve the ZVS (zero‐voltage switching) and ZVZCS (zero‐voltage zero‐current switching) condition, which charges and discharges the parallel snubber capacitors of the power switches at different modes of operation. Therefore, the switching losses of semiconductor components are reduced significantly, which results in enhanced efficiency. Moreover, the connection of an auxiliary capacitor in series with the transformer has prevented the probability of DC‐current saturation. The proposed converter could be controlled with duty‐cycle or switching frequency variations. However, the output voltage control with the switching frequency variations gives an extended range of output voltage compared with the other presented converters. Moreover, a coupled inductor is used to relate the output gain with the turn ratios, which causes a more extensive range for output voltage gain. Finally, the theoretical analysis is given and is compared with a 140 W experimental prototype, which converts a higher input voltage 300v to 7.5 V of the output voltage.

A Hybrid Inductive Power Transfer System with High Misalignment Tolerance Using Double-DD Quadrature Pads

Inductive power transfer (IPT) has been widely adopted as an efficient and convenient charging manner for both static and in-motion EVs. In this paper, a new hybrid topology is presented to improve the coupling tolerance under pad misalignment. The double inductor–capacitor–capacitor (LCC-LCC) network and series hybrid network combining the LCC-LCC topology and series-series (SS) topology are connected in parallel to provide better tolerance against self- and mutual inductance changes, particularly with a large Z-axis transmission distance. A double-DD quadrature pad (DD2Q) consists of a Q pad, and double orthogonal DD pads are analyzed in detail, which are employed to decouple the cross-mutual inductance. Moreover, a parametric design method based on the misalignment characteristics of the DD2Q pads is also proposed to maintain relatively constant power output. A 650-W hybrid topology with a fixed operating frequency of 85 kHz was built to verify the system’s feasibility. The size of the DD2Q pads was 280 mm × 280 mm, and the air gap was 100 mm. The results clearly show that the proposed hybrid topology can achieve a fluctuation within 5% in the output current with load varying from 100% full load to 25% light load conditions when the Z-axis transmission distance varies from 80 mm to 150 mm, and the maximum efficiency can reach 91% when the Z-axis transmission distance is 80 mm.

Circuit Implementation of Variable-Order Scaling Fractal-Ladder Fractor with High Resolution

Extensive research has been conducted on the scaling fractal fractor using various structures. The development of high-resolution emulator circuits to achieve a variable-order scaling fractal fractor with high resolution is a major area of interest. We present a scaling fractal-ladder circuit for achieving high-resolution variable-order fractor based on scaling expansion theory using a high-resolution multiplying digital-to-analog converter (HMDAC). Firstly, the circuit configuration of variable-order scaling fractal-ladder fractor (VSFF) is designed. A theoretical demonstration proves that VSFF exhibits the operational characteristics of variable-order fractional calculus. Secondly, a programmable resistor–capacitor series circuit and universal electronic component emulators are developed based on the HMDAC to adjust the resistance and capacitance in the circuit configuration. Lastly, the model, component parameters, approximation performance, and variable-order characteristics are analyzed, and the circuit is physically implemented. The experimental results demonstrate that the circuit exhibits variable-order characteristics, with an operational order ranging from −0.7 to −0.3 and an operational frequency ranging from 7.72Hz to 4.82kHz. The peak value of the input signal is 10V. This study also proposes a novel method for variable-order fractional calculus based on circuit theory. This study was the first attempt to implement feasible high-resolution continuous variable-order fractional calculus hardware based on VSFF.

Multiphase Interleaved IPT Based Current-Source Converter for High-Current Application

This article proposes a multiphase interleaved inductive power transfer (IPT) based dc–dc converter for high-current applications. There are three main contributions. First, the proposed converter is designed based on a loosely coupled IPT system with series compensation capacitors, which permits large leakage inductance and avoids magnetic saturation. Second, series capacitors are used to compensate the magnetic coupler, which achieves load-independent output current, namely a current-source converter. Third, a scalable multiphase converter is achieved with an input-parallel output-parallel structure for high current. Meantime, an interleaved control strategy is implemented to an <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">N</i> -phase system with an angle shift of 360°/(2× <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">N</i> ), reducing output current ripples. A 2-kW/100-A three-phase converter prototype is implemented with zero-voltage switching and harmonic loss suppression. Experimental results show a load-independent output current, which is linearly regulated by input dc voltage. With an input voltage of 480 V, the output current reaches 101.5 A with a small peak-peak ripple of 2.4 A. Output power reaches 2.07 kW with a 91.39% dc–dc efficiency. A steady-state test for a solid-state circuit breaker (SSCB) is conducted using the proposed high-current converter, showing its application in evaluating the steady-state efficiency and thermal performance of SSCB.

Modular DC‐DC converter with reduced current ripple and low voltage stress suitable for high voltage applications

AbstractIn this paper, a couple inductor‐based dc‐dc boost converter with extensible capability is presented. In the proposed converter, attaching extensions to input section alleviates input current ripple. Furthermore, the current sharing performance between different phases operates beneficially by expanding optimized boost converters, especially when a partial inequality exists among different switches' duty cycles and leakage inductances. The voltage conversion ratio of the proposed converter is also additionally optimized by a series of VMR's output capacitors. Meanwhile, not only the voltage stress upon the main switches is decreased but also the all switches are managed to be turned on with zero current switching technique. The voltage spikes across MOSFETs are eliminated by using the recycling energy of leakage inductances on the clamp capacitor. The topology of the proposed converter, steady‐state analysis, and design procedure is presented to indicate the merits of the suggested converter. A prototype circuit with a three‐phase interleaved boost converter, two number of diode‐capacitor in each VMR, and output power 660 W and 40–800 V conversion ratio is experimented to corroborate the validity of the presented structure.

Development of the Magnet Coil Power Supply for Fishtail Divertor on EAST

Fishtail divertor (FTD), a new divertor concept, is a significant research object of Experimental Advanced Superconducting Tokamak (EAST) tokamak divertor system. In order to meet the requirement of sinusoidal current precision and variable frequency, the combination of inductance and capacitance ( <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">LC</i> ) series resonance theory and high-frequency pulsewidth modulation (PWM) technology is put forward. A sine wave power supply with multifrequency points (1–3800 Hz) and current up to 8000 A is developed. The FTD power supply (PS) adopts dc switching power technology, sinusoidal PWM (SPWM) technology, and <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">LC</i> series resonance theory. The operating points of output current include 10–20 Hz at 8000 A, 30–110 Hz at 5000 A, and 1300–3800 Hz at 2400 A. The electromagnetic environment in the device is complex and arguable. The output current accuracy can reach 5% by the current feedback and frequency feedback control strategy. The test results demonstrate that the FTD PS can meet the system requirements, and it has strong reference significance, which can provide reference for the design of other divertor PS.

A Three-Coil Wireless Power Transfer System using Self-Resonant Open-Bifilar Coils

A common trend in the field of wireless power transfer consists in the use of more than two coils in order to extend the link distance in terms of efficiency, in which the 3-coil system is of great interest due to its high efficiency. In these circuits, usually, the preferred method of compensation is the series (capacitor and inductor in series), mainly due to its simplicity. Another promising topic is the use of coils tuned at their self-resonant frequency, mainly because it could avoid the use of external capacitors to achieve the resonant state in the involved circuits. However a multiple-coil self-resonant frequency with series compensation system was not yet presented in literature. In this paper, using open-bifilar coils, we present a self-resonant 3-coil wireless power transfer system that behaves as common series compensated circuit. Practical results confirm the validity of proposed solution, in a proof of concept methodology, that is, without any optimization strategy applied. For this sake, three different distances between transmitter and relay coil are adopted, while a 10 Ω resistor is used as load, allowing a maximum efficiency of 47% at a distance of 8 cm between relay and load coil (coils diameter are 15 cm).