Inductive Compensation Research Articles

S/CLC Compensation Topology Analysis and Circular Coil Design for Wireless Power Transfer

Wireless power transfer (WPT) has drawn a lot of attention due to its inherent advantages and great potential in various applications. This paper proposes a novel compensation topology composed of one compensation inductor and three compensation capacitors. The newly proposed compensation topology, named as S/CLC, provides the advantages of constant voltage output and easy achievement of zero phase angle and zero voltage switching. It is also free from the constraints imposed by the loosely coupled transformer (LCT) parameters. All the above-mentioned merits are theoretically analyzed and verified by simulation and experiment. Compared to double-sided LCC compensation topology, S/CLC compensation topology needs less compensation components, meaning lower cost, smaller size, higher power density, and greater potential in practical applications. The optimization of a circular pad is conducted as well since the properties of the LCT have a significant impact on the performance of a WPT system. A circular pad is manufactured in terms of the conclusions obtained from the optimization. The coupling coefficient Circular pad design, constant voltage output (CVO), wireless power transfer (WPT), zero phase angle (ZPA), zero voltage switching (ZVS).of the circular pad is quite appealing, demonstrating the validity of the optimization.

Study on Quench Detection of the KSTAR PF Coils Using Numerical Compensation of Inductive Voltages With Genetic Algorithm

A quench detection system for Korea Superconducting Tokamak Advanced Research (KSTAR) Poloidal Field (PF) coils is indispensable against the occurrence of a normal zone due to frequently variable current operation and an enormous amount of stored energy. The co-wound conductive strips and Wheatstone bridges have been adopted in KSTAR to detect abnormal voltage signal caused from quench. Those voltage detection methods have sufficient capability to detect quench occurrence, but additional cancelling out of mutual induction by adjacent coils would improve stability and reliability of quench detection system. A new voltage detection concept, using central difference averaging (CDA) and mutual inductance compensation (MIK) simultaneously, as an advanced technique to compensate the mutual inductive voltage, has been suggested and studied for this study. The CDA and MIK methods were practically adapted to the KSTAR PF 1 coil for the feasibility study. Test results show that the inductance matrix calculated by the FEM tool should be revised because of a revealed discrepancy between measured CDA voltage and calculated MIK voltage. In this study, the inductance matrix was revised by using the “Genetic algorithm” optimization method to reduce the discrepancy between CDA and MIK effectively. The adoption of the MIK revised inductance matrix was consistent with CDA voltage; mutual inductive voltage was expected to be successfully eliminated.

Lamb-Wave Resonator Oscillator Powered by Inductive Compensation of Stray-Capacitance CMOS Inverter

Lamb-Wave Resonator Oscillator Powered by Inductive Compensation of Stray-Capacitance CMOS Inverter

高温超导带材和线圈的交流损耗测试方法研究

文中介绍了以采集卡为测量手段，由交流电流源、测量系统、电流源保护系统和补偿系统组成的高温超导带材/磁体交流损耗测试系统。测试系统将功率补偿技术、电感补偿技术应用于采集卡交流损耗测试方法中。通过单匝带材交流损耗测试、线圈交流损耗测试等测试结果，验证了高温超导带材/磁体交流损耗测试系统测试的准确性和稳定性。 In this paper, a new measuring system for the AC loss of High Temperature Superconducting (HTS) tapes and coils was designed, and tested. The system consists of AC current source, acquisition system, power protection system, compensation system, and the measurement is based on the high sensitivity data acquisition card. The power compensation technology and inductance com-pensation technology were applied in this system. The tests on the AC loss of types and coils prove the testing stability and accuracy of the new AC loss measuring system for HTS tapes and coils.

ELIMINATE CROSSTALK USING SYMMETRY IN MIMO ARRAYS OF INDUCTIVE ANTENNAS: AN INTRODUCTION TO PIE-CHART ANTENNAS

We present a topology of MIMO arrays of inductive antennas exhibiting inherent high crosstalk cancellation capabilities. A single layer PCB is etched into a 3-channels array of emitting/receiving antennas. Once coupled with another similar 3-channels emitter/receiver, we measured an Adjacent Channel Rejection Ratio (ACRR) as high as 70 dB from 150 Hz to 150 kHz. Another primitive device made out of copper wires wound around PVC tubes to form a 2-channels “non-contact slip-ring” exhibited 22 dB to 47 dB of ACRR up to 15MHz. In this paper we introduce the underlying theoretical model behind the crosstalk suppression capabilities of those so-called “Pie-Chart antennas”: an extension of the mutual inductance compensation method to higher number of channels using symmetries. We detail the simple iterative building process of those antennas, illustrate it with numerical analysis and evaluate there effectiveness via real experiments on the 3-channels PCB array and the 2-channels rotary array up to the limit of our test setup. The Pie Chart design is primarily intended as an alternative solution to costly electronic filters or cumbersome EM shields in wireless AND wired applications, but not exclusively.

A High-Precision CV/CC AC–DC Converter Based on Cable and Inductance Compensation Schemes

This paper proposes a high-precision primary-side regulation constant voltage (CV) and constant current (CC) ac–dc converter. CV output is achieved by adjusting the switching frequency and primary peak voltage simultaneously, for better dynamic adjustment ability. In order to improve CV precision, a cable compensation module is adopted to inject current to pull-down resistor of auxiliary winding divider, compensating the cable voltage loss caused by the output cable resistance. On the other hand, CC output is acquired by maintaining the ratio of switching frequency and output voltage constant. The inductance compensation module regulates further to keep the product of demagnetization time and switching frequency fixed, equalizing the inconsistent output current result from the big tolerance of the transformer primary-side inductance in the same batch. Moreover, an improved demagnetization time detector is proposed, which is beneficial to raise CC precision. The control chip is implemented based on TSMC 0.35-μm 5-V/40-V BCD process, and a 12 V/1 A prototype has been built to prove the proposed control method. In CV mode, the deviation of the output voltage is within ±1.5%, while that of output current is within ±3% in CC mode.

Inductance Compensation for the Quench Detection of the KSTAR CS Coil

Voltage-based QD is the primary way to guarantee that magnets can be protected against overheating because of its fastest response. However, central solenoid (CS) and poloidal field (PF) coils are operated in pulse currents, so resultant inductive voltages could be hundred times higher than quench detection voltage thresholds. For this reason, some inductive voltage compensation techniques have been adopted to discriminate the quench-induced resistive voltage from the voltage induced by self and mutual inductances between coils. Cowound voltage sensors and bridge circuits are used to eliminate inductive voltages, but achieving additional rejection of remaining inductive voltages is necessary. Simple comparison between bridge voltages or cowound voltages from upper and lower PF coils, which are symmetric to the equatorial plane, has been well operating for KSTAR. Another is mutual inductance compensation, where mutually induced voltages are estimated by using predefined inductances and temporal derivatives of PF coil currents and compared with measured voltages. Rogowski coils to measure the current derivatives of CS/PF coils, precompensated voltages with inductive voltages largely eliminated beforehand, and a data analysis system were prepared for the KSTAR PF 1 coil. Analysis of inductive voltage compensation was presented with the operational result in 2015 KSTAR campaign.

Design of a High-Precision Constant Current AC-DC Converter with Inductance Compensation

A primary-side regulation AC-DC converter operating in the PFM (Pulse Frequency Modulation) mode with a high precision output current is designed, which applies a novel inductance compensation technique to improve the precision of the output current, which reduces the bad impact of the large tolerance of the transformer primary side inductance in the same batch. In this paper, the output current is regulated by the OSC charging current, which is controlled by a CC (constant current) controller. Meanwhile, for different primary inductors, the inductance compensation module adjusts the OSC charging current finely to improve the accuracy of the output current. The operation principle and design of the CC controller and the inductance compensation module are analyzed and illustrated herein. The control chip is implemented based on a TSMC 0.35μm 5V/40V BCD process, and a 12V/1.1A prototype has been built to verify the proposed control method. The deviation of the output current is within ±3% and the variation of the output current is less than 1% when the inductances of the primary windings vary by 10%.

LCL Resonant Compensation of Movable ICPT Systems with a Multi-load

Compared to LC resonance, LCL resonance has distinct advantages such as a large resonant capability, low voltage and current stresses of the power device, constant voltage or current output characteristics, and fault-tolerance capability. Thus, LCL resonant compensation is employed for a movable Inductive Contactless Power Transfer (ICPT) system with a multi-load in this paper, which achieves constant current output characteristics. Peculiarly, the primary side adopts a much larger compensation inductor than the primary leakage inductor to lower the reactive power, reduce the input current ripple, generate a large current in the primary side, and realize soft-switching. Furthermore, this paper proposes an approximate resonant point for large inductor-ratio LCL resonant compensation through fundamental wave analysis. In addition, the PWM control strategy is used for this system to achieve constant current output characteristics. Finally, an experimental platform is built, whose secondary E-Type coils can ride and move on a primary rail. Simulations and experiments are conducted to verify the effectiveness and accuracy of both the theory and the design method.

Optimisation of reactive power compensation of HVAC cable in off‐shore wind power plant

High voltage AC (HVAC) transmission system is preferred to be used in off-shore wind power plant which is located within 40km from the seashore. Capacitance of HVAC cables is naturally higher than that of overhead lines, and it should be properly compensated. P model of three-core XLPE cable which is widely used in off-shore wind power plant was applied in the paper. Based on this model, impacts of reactive power compensation on HVAC transmission system, including capacity and location of compensation equipment, were analyzed and simulated then. Research showed that inductive compensation at off-shore side of the cable is more effective to decrease power loss along the cable and increase its transmission capacity than that at onshore side, while the latter is more appropriate to improve the power factor at onshore access point of the wind power plant to grid. Compensation capacity was optimized to realize the best economy with designated certain parameters of HVAC system by Sequential Quadratic Programming (SQP) method. Finally by SQP costs of 35kV and 220kV HVAC transmission system were compared, critical distance and transmission capacity of these two systems adoption were found. These results can be a reference of HVAC transmission system design of off-shore wind power plant.

Simulation Analysis of Improved Construction and Control Strategy for Programmable AC Power Source

Novel circuit topology and advanced control technique of inverter are research focus for programmable AC power source. An improved dual buck half bridge inverter topology is introduced and the central symmetrical pulse width modulation mode is proposed to double the output current ripple frequency. High output precision can be achieved by optimizing the output waveforms of inverter. Then, a hybrid digital control scheme combining PID control with repetitive control as well as inductance compensation deadbeat control is presented for the closed loop voltage regulation of the mentioned inverter. Besides, an inductance saturation characteristic mathematic model is established for accurate simulation. Simulation results show that the theoretical analysis of the special switching sequence and hybrid control scheme is true.

Loss Characteristics of the Polygonal YBCO Conductors with a NiW Magnetic Substrate

The single- and double-layer polygonal conductors were tested, to understand loss of the 154- and 22.9-kV YBCO-NiW cables in the power grid of Korea Electric Power Corporation (KEPCO). Especially in YBCO-NiW, there is also an iron loss of NiW besides AC loss of YBCO, and so the loss is very complex. For reliability of our loss data, we tried a statistical treatment for several losses measured after compensating an inductive voltage at the same current first. Then distribution of flux around YBCO caused by NiW’s reluctance was investigated for different arrangements of YBCO (Y) and NiW (N): the YN and NY ones. Finally, influence of perpendicular magnetic field on conductor loss was also examined through two polygonal conductors, whose wires’ numbers are ten and five, respectively. The results show that the loss in a single-layer YBCO-NiW conductor is constant regardless of inductive compensation, as might be expected. But a double-layer conductor has dispersive loss properties at the same current: this is due to external AC magnetic field applied to an outer layer. And loss flux distribution in the conductors strongly depends on NiW arrangement because of its reluctance. Then differently from BSCCO, the loss measured for a polygonal YBCO-NiW conductor does not depend on its wires’ number. Thus, difference between the experimental and numerically calculated losses gets gradually large with increasing the number of wires. It can also be seen from the measured losses that in the single-layer conductor, they are identical to the sum of self-field losses in its YBCO-NiW wires. However, the losses of the double-layer NYYN conductor are greater than the total self-field losses of the YBCO-NiW wires. Furthermore, losses measured from two voltage leads, which are contacted to the inner and outer layers, well fit with each other.

Novel Unity-Gain Frequency Tracking Control of Series–Series Resonant Converter to Improve Efficiency and Receiver Positioning Flexibility in Wireless Charging of Portable Electronics

Currently available wireless charging technology for portable electronics demonstrates several shortcomings. For the consumers, the two major shortcomings are limited receiver positioning flexibility and lower efficiency compared to hard-connected charging. For the industry, the major disadvantages are higher cost and complexity in design and control. To overcome these shortcomings and disadvantages, this paper presents a novel control method for unity-gain frequency tracking (UGFT) under coupling coefficient (k) variation in a resonant converter containing a symmetrically implemented series-series (SS) resonant tank. An SS resonant converter employing the UGFT control provides several desirable features: the need for digital communication between the transmitter and the receiver to achieve leakage inductance compensation is eliminated, the design is robust against coupling (k) and load (Q) variations, the SS resonant converter can operate most of the time at the frequency of highest efficiency (unity-gain frequency f <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">O</sub> ), and the downstream regulator commonly employed in a wireless charging system may be eliminated. Furthermore, in this paper, frequency-domain characteristics of SS resonant tank are explained in detail to illustrate various desirable characteristics. Detailed design criteria for SS resonant tanks are provided to achieve these characteristics. Throughout the analysis, various simulation results are provided to complement the discussion. The proposed UGFT control method is validated through experimental results.

Cost Optimal Design of a Power Inductor for VAR Compensation in EHV Line

The paper presents the procedure for finding out inductive compensation required for an EHV transmission line at its terminals. It also presents the design methodology for the power inductor. The 3-phase power inductor is similar in construction to a 3-phase core-type transformer with the exception that it has only one winding per phase and each limb is provided with an air-gap, the length of which is decided upon by the inductance required.

Performance of Facts Devices to Improve Power Quality and Application of Static Synchronous Compensator

This study presents the study of configuration, working, controller of the fundamentals of the STATCOM and significant function of each custom power devices. Flexible Ac Transmission Systems (FACTS) controller achieves fast control response time as well as providing better control than conventional control. However, Static Synchronous Compensator (STATCOM) could be seen as one of the key Flexible Ac Transmission Systems (FACTS) devices which are based on the Voltage Source Converter (VSC) technology. The capacitive and inductive compensation could be provided by the controller and could as well control output current over the rated maximum capacitive or inductive range without depending on the ac system voltage.

Design and characterization of an ultrasonic lamb-wave power delivery system.

In this paper, a novel design for an ultrasonic power transmission system designed for use in aircraft structural monitoring systems is described. The prototype system uses ultrasonic Lamb waves to carry energy along plates, such as those used in aircraft structures, and commercially available piezoelectric patch transducers as the transmitter and receiver. This sets it apart from other acoustic power transmission systems reported to date. The optimum configuration transmitted 12.7 mW of power across a distance of 54 cm in a 1.5-mm-thick aluminum plate, while being driven by a 20-Vpp, 35-kHz sinusoidal electric signal. This is in the same order of magnitude as the power required by the wireless sensors nodes of a structural health monitoring system currently being developed by Cardiff University and its partners. Thus, the power transmission system can be considered a viable component of the power source combination considered for the sensor nodes, which will also include vibration and thermal energy harvesting. The paper describes the design and optimization of the transmission and reception circuits with the use of inductive compensation. The use of laser vibrometry to characterize the transducers and to understand the signal propagation between them is also reported.

A 2.4GHz GaAs HBT stacked power amplifier with inductance compensation

A 2.4GHz GaAs HBT stacked power amplifier with inductance compensation

A New Fault Current Limiter and its Application in Micro-Grid

In this paper, a new type fault current limiter (FCL) topology is put forward for Micro-Grid (MG) system fault, which mainly consists of limiting inductance, bypass inductance and series compensation capacitors. The switching circuit is used to change circuit structure through the power diode bridge and FGCT, in the event of a fault the current limiting inductance is switched to limit short-circuit current. The topology has the advantages of switch quickly, simple control, and series compensation effect. Establishes a equivalent model of MG system with FCL, discusses the impact of FCL installation location to system short-circuit protection, and proposes the installation location program. Matlab is used for system modeling and simulation results show that the effect of the current limiter, which is installed on the outlet of the MG system power for three-phase short-circuit protection, is obvious, and has the function of inhibiting voltage sag.

Modeling and Electrical Measurement of Transport AC Loss in HTS-Based Superconducting Coils for Electric Machines

AC loss can be a significant problem for any applications that utilize or produce an AC current or magnetic field, such as an electric machine. The authors are currently investigating the electromagnetic properties of high temperature superconductors with a particular focus on the AC loss in coils made from YBCO superconductors. In this paper, a 2D finite element model based on the H formulation is introduced. The model is then used to calculate the trans port AC loss using both a bulk approximation and modeling the individual turns in a racetrack-shaped coil. The coil model is based on the superconducting stator coils used in the University of Cam bridge EPEC Superconductivity Group's superconducting permanent magnet synchronous motor design. The transport AC loss of a stator coil is measured using an electrical method based on inductive compensation using a variable mutual inductance. The simulated results are compared with the experimental results, verifying the validity of the model, and ways to improve the accuracy of the model are discussed.

Selection of a quench detection system for the ITER CS magnet

At variance with most of the existing superconducting systems operating in the world, the ITER central solenoid (CS) magnet is a fast pulsed system. This peculiarity creates a specific situation regarding the quench detection system, as a small resistive signal associated with a quench has to be discriminated from the high inductive signals imposed by the plasma scenario. The quench detection is based on an inductive compensation built from three adjacent double pancakes. The ITER protection rules for a superconducting magnet impose to respect the so-called maximum hot spot temperature criterion of 250 K in the quenched cable at the end of the fast discharge. A careful analysis of the residual inductive signals in the detection voltage shows that a blanking of the quench detection cannot be avoided during the early times of the plasma discharge (i.e. during 3.5 s). It is demonstrated that this blanking is, however, acceptable while fulfilling the hot spot criterion because the plasma initiation phase (PIP) is very similar to a fast safety discharge and corresponds to a fast decrease of the modules currents, which is favourable for the magnet protection.