Inductor

About: Inductor is a research topic. Over the lifetime, 52565 publications have been published within this topic receiving 484068 citations. The topic is also known as: passive two terminal.

Self-capacitance of inductors

Abstract: A new method for predicting the stray capacitance of inductors is presented. The method is based on an analytical approach and the physical structure of inductors. The inductor winding is partitioned into basic cells-many of which are identical. An expression for the equivalent capacitance of the basic cell is derived. Using this expression, the stray capacitance is found for both single- and multiple-layer coils, including the presence of the core. The method was tested with experimental measurements. The accuracy of the results is good. The derived expressions are useful for designing inductors and can be used for simulation purposes.

Calculation of losses in ferro- and ferrimagnetic materials based on the modified Steinmetz equation

Abstract: This paper discusses the influence of nonsinusoidal flux-waveforms on the remagnetization losses in ferro- and ferrimagnetic materials of inductors, transformers and electrical machines used in power electronic applications. The nonsinusoidal changes of flux originate from driving these devices by nonsinusoidal voltages and currents at different switching frequencies. A detailed examination of a dynamic hysteresis model shows that the physical origin of losses in magnetic material is the average remagnetization velocity rather than the remagnetization frequency. This principle leads to a modification of the most common calculation rule for magnetic core losses, i.e., to the "modified Steinmetz equation" (MSE). In the MSE the remagnetization frequency is replaced by an equivalent frequency which is calculated from the average remagnetization velocity. This approach allows, for the first time, to calculate the losses in the time domain for arbitrary waveforms of flux while using the available set of parameters of the classical Steinmetz equation, DC premagnetization of the material, having a substantial influence on the losses, can also be included. Extensive measurements verify the modified Steinmetz equation presented in this paper.

Exact analysis of class E tuned power amplifier at any Q and switch duty cycle

Abstract: Previous analytical descriptions of a Class E high-efficiency switching-mode tuned power amplifier have been based on the assumption of an infinite Q or the minimum possible value of Q . This paper presents an exact analysis of the Class E amplifier at any Q and any switch duty cycle D , along with experimental results. The basic equations governing the amplifier operation are derived analytically using Laplace-transform techniques and assuming a constant current through the dc-fed choke. The following performance parameters are determined for optimum operation: the current and voltage waveforms, the peak collector current and collector-emitter voltage, the output power, the power-output capability, the load-network component values, and the spectrum of the output voltage. It is shown that all parameters of the amplifier are functions of Q . Therefore, the high- Q assumption used in previous analyses leads to considerable errors. For example, for Q at D = 0.5 , some errors are up to 60 percent. The results can be used for designing Class E stages at any Q and switch duty cycle D . The measured performance shows excellent agreement with the design calculations. The collector efficiency was over 96 percent at 2 MHz for all tested values of Q from 0.1 to 10.

The Circuit Theory Behind Coupled-Mode Magnetic Resonance-Based Wireless Power Transmission

Abstract: Inductive coupling is a viable scheme to wirelessly energize devices with a wide range of power requirements from nanowatts in radio frequency identification tags to milliwatts in implantable microelectronic devices, watts in mobile electronics, and kilowatts in electric cars. Several analytical methods for estimating the power transfer efficiency (PTE) across inductive power transmission links have been devised based on circuit and electromagnetic theories by electrical engineers and physicists, respectively. However, a direct side-by-side comparison between these two approaches is lacking. Here, we have analyzed the PTE of a pair of capacitively loaded inductors via reflected load theory (RLT) and compared it with a method known as coupled-mode theory (CMT). We have also derived PTE equations for multiple capacitively loaded inductors based on both RLT and CMT. We have proven that both methods basically result in the same set of equations in steady state and either method can be applied for short- or midrange coupling conditions. We have verified the accuracy of both methods through measurements, and also analyzed the transient response of a pair of capacitively loaded inductors. Our analysis shows that the CMT is only applicable to coils with high quality factor (Q) and large coupling distance. It simplifies the analysis by reducing the order of the differential equations by half compared to the circuit theory.

Boost Converter With Coupled Inductors and Buck–Boost Type of Active Clamp

Abstract: This paper proposes a boost converter with coupled inductors and a buck-boost type of active clamp. In the converter, the active-clamp circuit is used to eliminate the voltage spike that is induced by the trapped energy in the leakage inductor of the coupled inductors. The active switch in the converter can still sustain a proper duty ratio even under high step-up applications, reducing voltage and current stresses significantly. Moreover, since both main and auxiliary switches can be turned on with zero-voltage switching, switching loss can be reduced, and conversion efficiency therefore can be improved significantly. A 200 W prototype of the proposed boost converter was built, from which experiment results have shown that efficiency can reach as high as 92% and surge can be suppressed effectively. It is relatively feasible for low-input-voltage applications, such as fuel cell and battery power conversion.