A Study on the Variable Inductor Design by Switching the Main Paths and the Coupling Coils

In a radio frequency (RF) system, it is possible to use variable inductors for providing tunable or selective frequency range. Variable inductors can be implemented by the microelectromechanical system (MEMS) process or by using transistors as switches to change the routing of coils or coupling quantities. In this paper, we investigated the design method of a variable inductor by using MOS transistors to switch the main coil paths and the secondary coupled coils. We observed the effects of different metal layers, turn numbers, and layout arrangements for secondary-coupled coils and compared their characteristics on the inductances and quality factors. We implemented two chips in the 0.18 m CMOS process technology for each kind of arrangement for verification. One inductor can achieve inductance values from about 300 pH to 550 pH, and the other is between 300 pH and 575 pH, corresponding to 59.3% and 62.5%, respectively, inductance variation range at 4 GHz frequency. Additionally, their fine step sizes of the switched inductances are from 0.5% to 6% for one design, and 1% to 12.5% for the other. We found that both designs achieved a large inductance tuning range and moderate inductance step sizes with a slight difference behavior on the inductance variation versus frequency.

A Novel Hybrid Active Power Filter with Multi-Coupled Coils

This paper proposes a hybrid active power filter (HAPF) with multi-coupled coils, applied to a medium- and high-voltage power grid. The passive filter of the proposed HAPF adopts the structure of multi-coupled coils to compress the traditional multiple LC branches into one branch which presents the same harmonic impedance characteristics as the former multiple LC branches. In the active power filter of the HAPF, a coupled inductor, instead of a transformer, is used to connect with the passive filter. The coupled inductor has mutual inductances with inductors of the passive filter. Through spatial magnetic coupling, the active power filter can inject compensation current into the power grid to eliminate the residual harmonics and absorb active power from the power grid to maintain the DC capacitor voltage. When the active power filter is open-circuited or short-circuited, the filtering effect of the passive filter can still be guaranteed, which improves the reliability of the filter. The benefits of the proposed HAPF with excellent harmonic filtering performance are that the inductors occupy only 1/3 space as compared with traditional three-tuned LC filter, and very small power of the active power filter. The feasibility of the proposed HAPF is verified through simulations and experiment.

Comparison of Effect Efficiency and Voltage Regulation Between Three-Phase Transformer Winding Connections

A transformer is an important device in electrical processes, as we know static electricity that involves magnetically coupled coils to increase or decrease the voltage. In three-phase transformer, there are various winding connections such as delta-delta (?, ?), wye-wye (Y, Y), wye-delta (Y, ?), delta-wye (?, Y), zig-zag (Z, Z), etc. And of the many often used connection are Yy0, Yd11, Dd0, and Dy5. From these various connections, each connection has different efficiency, losses, and voltage regulation. If they are connected with resistive, inductive, or capacitive loads. This paper method has discussed a transformer connection used are Yy0, Dd0, Yd11, and Dy5 in Laboratory Konversi Energi USU to see how the influence of load changes, on voltage regulation Where a state of balance load using are resistive, inductive, capacitive, and RLC combination. The result analysis of the experiment show, the best efficiency is at Dd0 connection, when loaded condition using capacitive is average 97.87%, and the best voltage regulation is obtained at Dy5, when loaded condition using resistive is average 28.35%

On Magnetically Coupled Coils Parameter Calculation

ANSYS Q3D Extractor tool (AQ3DE), using the quasi-static solvers (method of moments, integral equations and FEMs), is very efficient for computing and simulating two- and three-dimensional electromagnetic field. This simulation is used to extract parameters of interest, such as: resistance (R), conductance (G), self-inductance (L), mutual inductance (M) and capacitance (C). These parameters can be further used to optimize and to obtain automatically the design of a wireless power transfer systems (WPTS). The resulting matrices allow the generation of new matrices for any selected parameters. To complete the analysis, the model which is computed will be exported as an equivalent circuit. In this paper, starting from a given WPTS, using AQ3DE tool, the parameters of interest (R, G, L, M, C) were automatically calculated, and the SPICE equivalent circuit was obtained. The analysis was performed for two different distances between the emitter and the receiver. The electrical circuit theory was used for the system analysis of magnetically coupled coil (MCC) system. Starting from the parameters extracted by the AQ3DE tool, the performance of the WPTS has been analysed both in time and frequency domain.