Common Inductor Research Articles

Depth comparison of common inductor and common capacitor passive current sharing methods for multiphase LLC converter

AbstractCommon inductor (CIM) and common capacitor (CCM) passive current‐sharing methods have the advantages of simple implementation and low cost. However, there is still a lack of detailed comparative research on the two methods, which makes researchers confused when choosing the two methods. To provide clear scheme guidance, this paper provides a detailed comparison of the performance of the two methods. Firstly, this paper reveals the difference between the current waveforms of the two methods, that is, the current waveform of the CIM method is distorted, while the CCM method is non‐distorted. Then, the mechanism of the above phenomenon is analysed in depth. Secondly, for comparing the current sharing performance of the two methods, the first harmonic approximation (FHA) equivalent circuit model considering parasitic parameters is established to obtain the system's current sharing error model, and the parameter sensitivity analysis is provided. Finally, the relationship between the current waveform, current sharing error, and load ripple of the two methods is discussed. Then, based on the two methods, a more attractive common resonate tanks (CRT) current‐sharing method is proposed. The correctness of the view in this paper has been verified by extensive simulations and experiment results.

Design and Assessment of a Planar Inductor for a 32-kW High Power Density DC–DC Converter

A uniform-flux inductor design strategy is described in this paper to improve the gravimetric power density of the common inductor of a 32 kW, 350 V dual-interleaved Buck-Boost DC-DC converter. The strategy consists of an unusual, enclosed winding arrangement that virtually distributes the core magnetic flux density outcoming in a more compact inductor. The resultant common inductor weight and volume are reduced by 41 % and 24 % respectively, the power density being increased to 7.9 kW/kg. A COMSOL numerical prediction confirms almost uniform flux density distribution along the magnetic core axes. Estimation of the inductance, power losses and thermal behaviour are also analysed. Construction assessment is described for a 7 μH, 150 kHz, 180 A inductor, which is experimentally verified in a 350 V, 32 kW prototype. The experiments reveal that the built uniform-flux inductor properly operates ensuring both electrical and thermal stability.

Long Life Power Factor Corrected LED Driver with Capacitive Energy Mechanism for Street Light Applications

Conventional switch-mode LED drivers have problems such as poor performance in harmonic distortion, flickering, power factor correction, stresses on the switches, high switching losses, large size, and high cost. To resolve these problems, we propose a long-life LED driver with the ability of power factor correction. The proposed system is based on the integration of a half-bridge LLC resonant converter and two boundary-conducted boost converters. Both boost converters share a common inductor designed in such a way that both boost converters work in boundary conduction mode to attain the natural power factor correction. Half-bridge LLC resonant converter has soft switching characteristics, which assure the zero-voltage switching (ZVS) of primary-side switches and zero-current switching (ZCS) of diodes on the secondary side. This significantly reduces switching losses and improves the overall efficiency of the system. Voltage divider capacitors are used on the input side, which minimizes the bus voltages. The proposed system has two identical secondary windings with a coupled inductor to eliminate the mismatch between them, which powers two independent LED strings. The simulation of a 100-watt 240 V AC converter yields the approximate sinusoidal shape of the input current. It shows that the switches on the primary side are operated in ZVS and the diodes in ZCS. At 240-volt AC input, the efficiency is 87.4%, the total harmonics distortion (THD) is 10.98%, and the power factor (PF) is 0.98.

A 10 GHz Compact Balun with Common Inductor on CMOS Process

This paper presents a compact balun with a common inductor design. The design used Wilkinson-type balun topology with modified lumped transmission lines and a common inductor to realize circuit size reduction on a lossy CMOS process. Measurements of the prototype chip had a reflection coefficient below 17.8 dB at all ports, an insertion loss of 1.98 dB, and an isolation of 16.8 dB. The chip size was only 0.025λ0 × 0.034λ0.

An 11–40-GHz High-Power Switch With Miniaturized High-Order Topology Using 100-nm GaN-on-Si HEMTs

This article proposes an ultrawideband switch with miniaturized high-order topology. A 100-nm gate-length GaN-on-Si process is used for high-power capability, and the modeling of the GaN high-electron-mobility transistors (HEMTs) is given to analyze its parasitic values. For wideband or high isolation, the high-order switch is one solution, whose die area is naturally large. To address this issue, a miniaturized coupled-resonator switch topology was proposed using inverter transformation, where two parallel LC tanks and four inverters are replaced by two series LC tanks. Furthermore, a miniaturized coupling structure is introduced using a common inductor to replace three individual ones, contributing to an 86% size reduction. For demonstration, one 11–40.5-GHz single-pole single-throw (SPST) switch with four transmission poles (TPs) has been designed and fabricated. A small chip size of 0.32 mm2, low ON-state minimum insertion loss (IL) of 0.55 dB, and a high-power capability of 1.3 W are achieved.

A Unified Common Inductor and Common Capacitor Current Sharing Method for Multiphase LLC Converter

The common inductor and common capacitor current sharing technologies with excellent current sharing capabilities and low-cost have attracted a lot of attention in recent years. However, these methods have certain limitations. To solve this problem, this paper proposes a unified common inductor common capacitor scheme. Firstly, the existing common inductor and common capacitor methods are reviewed. Based on the first harmonic approximation (FHA) analysis method, the limitations of these schemes are analyzed, and we find that the current sharing performance is not well when the multi-resonant parameters are mismatched, which will cause the one-phase to bear more power, even over-powered and damaged. To realize a better current sharing of multi-phase LLC modules, a unified common inductor common capacitor method is proposed in this article, where the series resonant inductors and resonant capacitors in each LLC converter are connected in parallel. The current sharing performance of the proposed method is analyzed by the FHA analysis method, and the proof-of-concept prototype with a 480W 24V two-phase LLC converter was built to verify the effectiveness of the proposed method. Simulation and experimental results show that the current sharing error of the proposed method is 2.1% under half load and 0.9% under full load.

A Passive Current Sharing Method for Two-Phase Common Inductor LLC Resonant Converters and Mathematical Analysis of Current Sharing Effect

A Passive Current Sharing Method for Two-Phase Common Inductor <i>LLC</i> Resonant Converters and Mathematical Analysis of Current Sharing Effect

A dual input single output non-isolated DC-DC converter for multiple sources electric vehicle applications

There is a need to design DC-DC converters capable of handling high voltages and that employ single-stage conversion to integrate renewable energy resources, such as solar photovoltaic cells and fuel cells, for electric vehicle applications. This paper elucidates the design and analysis of a dual input single output non-isolated Cuk-derived converter with a high step-up ratio. The proposed converter can effectively handle two different energy resources that have different electrical characteristics. It makes use of one common inductor between the dual input port, which reduces the passive components and the circuit volume required. The maximum efficiency that can be achieved by this converter is 95.72%, with two main switches and one diode in the circuit. This study involved a detailed analysis of the proposed converter in continuous current operation mode. A continuous current with reduced ripple in the output improves a fuel cell’s operating life-span. The efficacy of the proposed converter is verified through simulation and validated by constructing a 200 W, real-time, scaled-down prototype model.

Stabilization of the Rotor Speed of an Asynchronous Generator of a Wind Power Plant

Alternative energy sources play a significant part in the development of modern electric power, agriculture and forestry. In accordance with the decree of the Government of the Russian Federation of 08.01.2009 1-p “On the main directions of state policy in the field of improving the energy efficiency of the electric power industry based on the use of renewable energy sources for the period up to 2035”, currently, due to the high level of environmental pollution, the use of electricity obtained using alternative sources is relevant. Since alternative energy sources are renewable, there is no need for additional raw materials that are needed to generate energy. Alternative sources of electricity are widely used for consumers who are located in a remote area from power lines and have the need to obtain not only single-phase, but also three-phase electrical energy. For the implementation of power supply to these consumers, a wind turbine is considered, which allows for long-term uninterrupted three-phase power supply. The main difference of this wind turbine is a device for stabilizing the rotor speed of an asynchronous generator, which is a combined synchronous machine with a common inductor.

Compact Wilkinson Power Divider With Common Inductor on the IPD Process

Compact Wilkinson Power Divider With Common Inductor on the IPD Process

An emulation platform for mimicking unbalanced loads and sources

Abstract With the increasing penetration of power electronic equipment for various day to day applications, several testing methods are also gaining attention. Power level emulation is a popular technique which is typically employed for mimicking the behaviour of a source or load in real-time. Most of the available literature deals with the power level emulation of balanced loads and sources. This paper presents the details of control schemes and an emulator based on a four leg VSI, which is capable of mimicking unbalanced sources and loads. A flexible control scheme with a common inner inductor current loop is proposed for both the positive and negative sequence components, for the unbalanced load and source emulations. The proposed emulator is capable of emulating both types of unbalances — those in which only positive and negative sequence components exist (3 wire systems) and those in which the zero sequence components also exist in addition to the above mentioned components (4 wire systems). The modelling and control aspects are validated through simulations using Matlab Simulink and through experiments on the laboratory prototype emulator.

Dual-Band Compact Wilkinson Power Divider Using Common Inductor and Complex Load

A 1.8/2.4-GHz dual-band compact Wilkinson power divider was designed and implemented using an integrated passive device process. The design used a common inductor to match impedance in the even mode. The common inductor replaced two shunt inductors in the circuit so the circuit size was reduced. An additional complex load was then used for matching impedance in the odd mode. The circuit measurements showed reflection at all ports better than -11.9 dB, isolation at the output ports better than -14 dB and transmission coefficient better than -4.3 dB, at both operating frequencies. The circuit occupied only 0.036λ <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">o</sub> ×0.018λ <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">o</sub> at the higher operating frequency.

Dual input buck-boost converter for hybrid piezoelectric energy harvester – Supercapacitor sources

Integration of energy sources provides superior flexibility and reliability in low power electronic system. A dual input positive buck-boost converter is proposed for integrating piezoelectric energy harvester (PEH) and supercapacitor sources. The converter circuit consists of three active power switches, a common inductor, and an output filter capacitor. The active switch connected with the PEH is operated at the optimum duty cycle for maximum power extraction through impedance matching. The voltage at the output can be regulated by adjusting the duty ratio of the active switch connected with the supercapacitor. The charging mechanism of supercapacitor from a piezoelectric energy harvester is also presented. The operational performance of the proposed system is verified through simulation and validated by experimental investigation. The output power is measured for the range of load resistance, and a maximum power of 4.48 mW with the efficiency of 59% is obtained for the load resistance of 22 kΩ.

High-Efficiency and High-Density Single-Phase Dual-Mode Cascaded Buck–Boost Multilevel Transformerless PV Inverter With GaN AC Switches

This paper introduces a high-efficiency and high-density single-phase dual-mode cascaded buck–boost multilevel transformerless photovoltaic (PV) inverter for residential application. This inverter topology combines a regulated cascaded H-bridge multilevel inverter stage with an unregulated GaN-based ac boost converter. The cascaded H-bridge inverter and the ac boost share a common inductor. Compared with the traditional cascaded H-bridge PV inverter, this topology significantly enlarges the input voltage range due to the additional ac boost. And, a flexible number of PV panels can be used. To control the multiple dc-link PV voltages and to reduce the switching loss of the ac boost, this paper further introduces a dual-mode operation. The two modes are buck mode and buck–boost mode. To maximize the utilizations of the dc-link voltages, this paper presents a minimized ac boost duty-cycle generation strategy with feedforward. Then, a dual-mode modulation based on the boost feedforward duty-cycle generation is introduced. This paper also uses an indirect current control for this inverter, since the ac boost is an unregulated stage. The ac boost stage is implemented with two interleaved phases and the ac switches based on the 650-V E-mode GaN FETs. Finally, an 8-port 2-kW prototype based on this topology is developed and demonstrated. Compared with the state-of-the-art microinverter-based 2-kW PV inverter system, the developed inverter prototype achieves 40% reduction of the total power loss, 25% improvement of the power density, 37.5% reduction of the power connectors, 50% reduction of the device count, and 87.5% reduction of the main magnetic count. Operating with natural convection cooling, this PV inverter achieves 98.0% efficiency at 60% of load and 97.8% efficiency at full load. The power density of the packaged PV inverter is 5.8 W/in3.

Nonzero Discontinuous Inductor Current Mode in Certain Z-Source Converters

The continuous current mode (CCM) and discontinuous current mode (DCM) are common inductor current phenomenon seen in various Z-source converters. The CCM is characterized by nonzero rising or falling inductor current while inductor current acquires zero value during DCM. Primarily, DCM occurs in case of low inductor or light load condition. This results in difficult control of the converter due to aberrant voltage at dc terminal. However, in certain dc–ac Z-source converters, the inductor current acquires the profile of an ac load current or become constant in nature. This constant nature of inductor current occurs in case of low duty cycle condition. Constant nature in the current creates similar difficulty in control as DCM. Furthermore, it deteriorates the performance of the converter in terms of total harmonic distortion, high dc voltage ripple, increased dc voltage, and reduced peak ac voltage. This letter explains the nonzero discontinuous inductor current mode, in which constant current phenomenon appears, existence condition and case study along with performance parameters analysis.

A Passive Current Sharing Method With Common Inductor Multiphase LLC Resonant Converter

In this paper, a new common inductor current sharing method is proposed for a multiphase LLC resonant converter for high-power applications. Automatic current sharing is achieved by using a common resonant inductor connecting the resonant inductors in each LLC phase in parallel. The current sharing performance of the proposed method is evaluated under first harmonic approximation (FHA) assumption. The proposed method can automatically share the primary resonant current and the load current for all phases without any additional circuit and control strategy. A 600-W two-phase LLC converter prototype based on the proposed method is built to verify the feasibility. Excellent current sharing performance (less than 0.5% current sharing error at full load) has been achieved.

Crack Evaluation Based on Novel Circle-Ferrite Induction Thermography

Nondestructive inspection of rolling contact and stress corrosion cracks is a critical important research area in both science and technology industry to evaluate the properties of a product. This paper proposes a novel system of circle-ferrite pulsed inductive thermography for cracks inspection. The new sensing structure consists of several promising characteristics. It significantly enhances the detectability of omnidirectional micro cracks, and provides larger detection area with non-geometry influence. In addition, unlike common inductor, the proposed structure imposes uniform toroidal electromagnetic thermal fields, so that both sensitivities of detection rate and the detectable area can be simultaneously improved. This overcomes the problem of in-homogenous heating, and increases the thermal contrast between directional defective and non-defective region. The theoretical derivation based on magnetic circuit principles has been developed for analysis and interpretation of the results. In addition, both simulation experiments and tests on artificial and nature cracks sample have been conducted to show the reliability and efficiency of the proposed system.

Exact steady‐state analysis in multiple‐input converters applied with diverse time‐sharing switching schemes

Time-sharing switching (TSS) techniques are usually utilised in multiple-input converters (MICs) to manage power sharing among inputs as well as output-voltage regulation. The two most-commonly-used TSS schemes in practical MIC applications are trailing-edge modulation (TEM) and interleaved dual-edge modulation (IDEM), both of which containing abundant significant information on conduction sequence. Steady-state analysis and computation help understand MICs' behaviour, being of high significance in both principal and practical researches. This study exhibits a general and exact methodology for computing and synthesising analytical expressions in a steady state of any kind of MIC topology, based upon analysis of segmented waveforms of common inductor current and output capacitor voltage. The derivation results are of high accuracy and generality, applicable for scenarios with arbitrary number of inputs in either continuous conduction mode or discontinuous conduction mode, and applied by either TEM-based or IDEM-based TSS schemes. Analytical and derivation details are addressed to the issues of multiple-input buck converters, along with general procedures established for other MICs topologies, for example, multiple-input buck–boost converters and multiple-input single-ended primary-inductor converters. Case study on a dual-input buck converter prototype, considering power dissipations and voltage drops on its components, is put forward for theoretical verification.

Design and Implementation of a Power Converter to Process Renewable Energy for Step-down Voltage Applications

In this study a power converter to process renewable energy is proposed, which can not only process solar energy but deal with wind power. The proposed converter is derived from two series modified forwards to step down voltage for charger system or dc distribution application, so as called Modified-Forward Dual-Input Converter (MFDIC). The MFDIC mainly contains an upper Modified Forward (MF), a lower MF, a common output inductor and a DSP-based system controller. The upper and lower MFs can operate individually or simultaneously to accommodate the variation of atmospheric conditions. Since the MFDIC can process renewable power with interleaved operation, the ripple of output current is suppressed significantly and thus better performance is achieved. In the MFDIC only a common output inductor is needed, instead of two separated inductors, so that the volume of the converter is reduced significantly. To draw maximum power from PV panel and wind turbine, perturb-and-observe method is adopted to achieve the feature of Maximum Power Point Tracking (MPPT). The MFDIC is constructed, designed, analyzed, simulated and tested. Simulations and practical measurements have demonstrated the validity and the feasibility of the proposed dual-input converter.

Highly miniaturized RF bandpass filter based on thin-film bulk acoustic-wave resonator for 5-GHz-band application

Highly miniaturized RF bandpass filter using a thin-film bulk acoustic wave resonator (TFBAR) is designed and fabricated for 5-GHz-band application. The topology of the fabricated filter is based on a ladder-type configuration that has a common trimming inductor connected concurrently with two shunt TFBARs and the trimming inductor is directly connected to the ground. The role of unit the TFBAR's physical characteristics such as the size and thickness of the TFBAR determine the performance of the TFBAR filter, including the effect of the electrical impedance-matching characteristics of the TFBAR filter. The shape of the fabricated TFBARs are tetragons with unparallel sides and the sizes of resonator are smaller than 70/spl times/70 /spl mu/m/sup 2/ to ensure the ranges of impedance-matched filter performance. The insertion loss and bandwidth of fabricated TFBAR filters are less than 2.8 dB and 160 MHz at 3 dB. The out-of-band rejection is over 30 dB. The actual size of filter is smaller than 700/spl times/600 /spl mu/m/sup 2/, including signal and ground pad sizes.