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Showing papers on "Inductor published in 2007"


Journal ArticleDOI
TL;DR: The closed-loop control methodology is utilized in the proposed scheme to overcome the voltage drift problem of the power source under the variation of loads and achieve the aim of high-efficiency power conversion.
Abstract: In this paper, a high-efficiency dc-dc converter with high voltage gain and reduced switch stress is proposed. Generally speaking, the utilization of a coupled inductor is useful for raising the step-up ratio of the conventional boost converter. However, the switch surge voltage may be caused by the leakage inductor so that it will result in the requirement of high-voltage-rated devices. In the proposed topology, a three-winding coupled inductor is used for providing a high voltage gain without extreme switch duty-cycle and enhancing the utility rate of magnetic core. Moreover, the energy in the leakage inductor is released directly to the output terminal for avoiding the phenomenon of circulating current and the production of switch surge voltage. In addition, the delay time formed with the cross of primary and secondary currents of the coupled inductor is manipulated to alleviate the reverse-recovery current of the output diode. It can achieve the aim of high-efficiency power conversion. Furthermore, the closed-loop control methodology is utilized in the proposed scheme to overcome the voltage drift problem of the power source under the variation of loads. Some experimental results via an example of a proton exchange membrane fuel cell power source with 250-W nominal rating are given to demonstrate the effectiveness of the proposed power conversion strategy

378 citations


Patent
16 Oct 2007
TL;DR: An inductive power pad (100) includes a plurality of transmitting inductors (120) and a respective plurality of detector circuits (140), each transmitting inductor is operable to provide inductive energy to a power receiver circuit (150) as discussed by the authors.
Abstract: An inductive power pad (100) includes a plurality of transmitting inductors (120) and a respective plurality of detector circuits (140). Each transmitting inductor (120) is operable to provide inductive energy to a power receiver circuit (150). Each detector circuit (140) corresponds to one of the plurality of transmitting inductors (120) and each detector circuit (140) is operable to electromagnetically sense a power receiver circuit (150) in proximity thereto. Each detector circuit upon electromagnetically sensing a power receiver circuit, is further operable to control switching of its corresponding transmitting inductor to a power supply (130), thereby providing a supply voltage to said corresponding transmitting inductor, said supply voltage operable to generating inductive energy (110) for transmission to said power receiver circuit.

361 citations


Journal ArticleDOI
TL;DR: In this article, a gate signal complimentary control scheme is proposed to turn on the nonactive switch and to divert the current into the antiparalleled diode of the active switch so that the main switch can be turned on under zero-voltage condition.
Abstract: A bidirectional dc-dc converter typically consists of a buck and a boost converters. In order to have high-power density, the converter can be designed to operate in discontinuous conducting mode (DCM) such that the passive inductor can be minimized. The DCM operation associated current ripple can be alleviated by interleaving multiphase currents. However, DCM operation tends to increase turnoff loss because of a high peak current and its associated parasitic ringing due to the oscillation between the inductor and the device output capacitance. Thus, the efficiency is suffered with the conventional DCM operation. Although to reduce the turnoff loss a lossless capacitor snubber can be added across the switch, the energy stored in the capacitor needs to be discharged before device is turned on. This paper adopts a gate signal complimentary control scheme to turn on the nonactive switch and to divert the current into the antiparalleled diode of the active switch so that the main switch can be turned on under zero-voltage condition. This diverted current also eliminates the parasitic ringing in inductor current. For capacitor value selection, there is a tradeoff between turnon and turnoff losses. This paper suggests the optimization of capacitance selection through a series of hardware experiments to ensure the overall power loss minimization under complimentary DCM operating condition. According to the suggested design optimization, a 100-kW hardware prototype is constructed and tested. The experimental results are provided to verify the proposed design approach.

355 citations


Journal ArticleDOI
TL;DR: In this article, a new class of single-chip multiple-frequency (up to 236 MHz) filters that are based on low motional resistance contour-mode aluminum nitride piezoelectric micromechanical resonators is presented.
Abstract: This paper reports experimental results on a new class of single-chip multiple-frequency (up to 236 MHz) filters that are based on low motional resistance contour-mode aluminum nitride piezoelectric micromechanical resonators. Rectangular plates and rings are made out of an aluminum nitride layer sandwiched between a bottom platinum electrode and a top aluminum electrode. For the first time, these devices have been electrically cascaded to yield high performance, low insertion loss (as low as 4 dB at 93MHz), and large rejection (27 dB at 236 MHz) micromechanical bandpass filters. This novel technology could revolutionize wireless communication systems by allowing cofabrication of multiple frequency filters on the same chip, potentially reducing form factors and manufacturing costs. In addition, these filters require terminations (1 kOmega termination is used at 236 MHz) that can be realized with on-chip inductors and capacitors, enabling their direct interface with standard 50-Omega systems

217 citations


Patent
06 Jun 2007
TL;DR: In this article, a plurality of bi-directional conducting and blocking semiconductor switches are used to connect an inductor and parallel capacitor between two or more portals, such that energy is transferred into the inductor from one or more input portals and/or phases.
Abstract: Methods and systems for transforming electric power between two or more portals. Any or all portals can be DC, single phase AC, or multi-phase AC. Conversion is accomplished by a plurality of bi-directional conducting and blocking semiconductor switches which alternately connect an inductor and parallel capacitor between said portals, such that energy is transferred into the inductor from one or more input portals and/or phases, then the energy is transferred out of the inductor to one or more output portals and/or phases, with said parallel capacitor facilitating “soft” turn-off, and with any excess inductor energy being returned back to the input. Soft turn-on and reverse recovery is also facilitated. Said bi-directional switches allow for two power transfers per inductor/capacitor cycle, thereby maximizing inductor/capacitor utilization as well as providing for optimum converter operation with high input/output voltage ratios. Control means coordinate the switches to accomplish the desired power transfers.

213 citations


Journal ArticleDOI
18 Jun 2007
TL;DR: An integrated 5-output single-inductor multiple-output DC-DC converter with ordered power-distributive control in a 0.5mum BiCMOS process is presented.
Abstract: An integrated five-output single-inductor multiple-output dc-dc converter with ordered power-distributive control (OPDC) in a 0.5 mum Bi-CMOS process is presented. The converter has four main positive boost outputs programmable from +5 V to +12 V and one dependent negative output ranged from -12 V to -5 V. A maximum efficiency of 80.8% is achieved at a total output power of 450 mW, with a switching frequency of 700 kHz. The performance of the converter as a commercial product is successfully verified with a new control method and proposed circuits, including a full-waveform inductor-current sensing circuit, a variation-free frequency generator, and an in-rush-current-free soft-start method. With simplicity, flexibility, and reliability, the design enables shorter time-to-market in future extensions with more outputs and different operation requirements.

211 citations


Journal ArticleDOI
TL;DR: A bridgeless boost rectifiers with low conduction losses and reduced diode reverse-recovery problems is proposed for power-factor correction and the linear peak current mode control is employed for the proposed boost rectifier.
Abstract: A bridgeless boost rectifier with low conduction losses and reduced diode reverse-recovery problems is proposed for power-factor correction. The proposed boost rectifier can reduce the conduction losses and alleviate the diode reverse-recovery problems by using a coupled inductor and two additional diodes. Zero-current turn-off of the output diodes is achieved, and the reverse-recovery currents of the additional diodes are slowed down to reduce the diode reverse-recovery losses. All inductive components are realized on a single magnetic core by utilizing the leakage inductance of the coupled inductor. Furthermore, for the use of this topology in the practical design, the linear peak current mode control is employed for the proposed boost rectifier. A detailed analysis and a control strategy are presented. Experimental results for a 300-W prototype are also discussed to show the performance of the proposed boost rectifier

203 citations


Journal ArticleDOI
TL;DR: In this article, the authors present a very practical, yet very general and accurate model, for core loss calculations in case of nonsinusoidal voltage waveforms, which can be used for the design of high frequency transformers and inductors for use in switched mode power supplies.
Abstract: Nonsinusoidal voltage waveforms are quite common in high frequency power conversion magnetics. Low frequency nonsinusoidal waveforms are also common in ac motor applications with waveforms such as pulsewidth modulation and six-step. Previous attempts to model these losses, based on the Steinmetz equation, can work only in a limited range of frequencies, flux density excitations, and waveforms. In this paper, we present a very practical, yet very general and accurate model, for core loss calculations in case of nonsinusoidal voltage waveforms. We show the model is equally applicable to low and high frequencies, metallic as well as nonmetallic (e.g., ferrites) core materials, by comparing the model prediction with measured data for various waveforms, frequencies, and flux densities. The model can be used for the design of high frequency transformers and inductors for use in switched mode power supplies. The model can also be used for ac motors where it is hard to estimate "derating factor" and to avoid uncontrolled temperature rise

198 citations


Journal ArticleDOI
TL;DR: An analytical express for the optimal frequency of a coil in terms of the design parameters is presented and it is shown to be useful in optimizing coil Index performance.
Abstract: This paper describes the ac power dissipation of coils as well as their self-capacitance, self-resonant frequency, and quality factor Q. In the past, self-resonant frequency was rarely calculated during design because of the lack of suitable closed-form design equations. However, coils are widely used in biomedical applications as inductive links for both power and data, and the power transfer capacity and the data rate of inductive links are determined by the operating frequency of the coils. The maximum operating frequency is limited by the self-resonant frequency of the coil. We present here an analytical express for the optimal frequency of a coil in terms of the design parameters. By varying the design parameters, we can move the optimal frequency close to the operating frequency, thereby boosting the efficiency of the inductive link. We have verified the derivation experimentally and shown it to be useful in optimizing coil Index performance.

182 citations


Journal ArticleDOI
TL;DR: In this paper, the authors identify a 1∕f component of the magnetic noise due to magnetization fluctuations and derive general relationships for the Johnson current noise and magnetization noise in cylindrical ferromagnetic shields in terms of their conductivity and complex magnetic permeability.
Abstract: Ferrite materials provide magnetic shielding performance similar to commonly used high permeability metals but have lower intrinsic magnetic noise generated by thermal Johnson currents due to their high electrical resistivity. Measurements inside a ferrite shield with a spin-exchange relaxation-free atomic magnetometer reveal a noise level of 0.75fTHz−1∕2, 25 times lower than what would be expected in a comparable μ-metal shield. The authors identify a 1∕f component of the magnetic noise due to magnetization fluctuations and derive general relationships for the Johnson current noise and magnetization noise in cylindrical ferromagnetic shields in terms of their conductivity and complex magnetic permeability.

170 citations


Patent
Yunfei Ding1
17 Apr 2007
TL;DR: In this paper, a method and system for providing and utilizing a magnetic memory is described, which includes driving a first current in proximity to but not through the magnetic element(s) of a portion of the magnetic storage cells.
Abstract: A method and system for providing and utilizing a magnetic memory are described. The magnetic memory includes a plurality of magnetic storage cells. Each magnetic storage cell includes magnetic element(s) programmable due to spin transfer when a write current is passed through the magnetic element(s) and selection device(s). The method and system include driving a first current in proximity to but not through the magnetic element(s) of a portion of the magnetic storage cells. The first current generates a magnetic field. The method and system also include driving a second current through the magnetic element(s) of the portion of the magnetic storage cells. The first and second currents are preferably both driven through bit line(s) coupled with the magnetic element(s). The first and second currents are turned on at a start time. The second current and the magnetic field are sufficient to program the magnetic element(s).

Journal ArticleDOI
TL;DR: This paper investigates the control of an uninterruptible power supply (UPS) using a combined measurement of capacitor and load currents in the same current sensor arrangement, and proposes a voltage controller based on resonant harmonic filters in order to compensate for unbalance and harmonic distortion on the load.
Abstract: This paper investigates the control of an uninterruptible power supply (UPS) using a combined measurement of capacitor and load currents in the same current sensor arrangement. The purpose of this combined measurement is, on one hand, to reach a similar performance as that obtained in the inductor current controller with load current feedforward and, on the other hand, to easily obtain an estimate of the inductor current for overcurrent protection capability. Based on this combined current measurement, a voltage controller based on resonant harmonic filters is investigated in order to compensate for unbalance and harmonic distortion on the load. Adaptation is included to cope with uncertainties in the system parameters. It is shown that after transformations the proposed controller gets a simple and practical form that includes a bank of resonant filters, which is in agreement with the internal model principle and corresponds to similar approaches proposed recently. The controller is based on a frequency-domain description of the periodic disturbances, which include both symmetric components, namely, the negative and positive sequence. Experimental results on the output stage of a three-phase three-wire UPS are presented to assess the performance of the proposed algorithm

Journal ArticleDOI
TL;DR: In this paper, an interleaved winding-coupled boost converter is proposed in order to realize ZCS turn-on condition and to achieve high step-up gain, where the voltage gain is extended easily and the voltage stress on the switches is reduced with different turns ratios of the coupled inductors.
Abstract: An interleaved winding-coupled boost converter is proposed in order to realize ZCS turn-on condition and to achieve high step-up gain. The voltage gain is extended easily and the voltage stress on the switches is reduced with different turns ratios of the coupled inductors. The output diode reverse-recovery problem is alleviated due to the inherent leakage inductor of the winding-coupled inductors. The simple but effective passive lossless clamp circuits are introduced to limit the voltage stress on the switches when they turn off so that the low-voltage, high-performance devices with low conduction resistor can be used in the proposed converter to reduce the relative losses. The leakage energy is ultimately recovered to the load. The high efficiency of 90.7% at full load and the maximum efficiency of 92.6% are achieved in a 1-kW 40-V-input-to-380-V-output prototype for front-end application. There is more than 10% efficiency improvement with the passive lossless clamp circuits compared to the case with RCD dissipated snubbers. The efficiency of 5% improvement at full load is achieved with the proposed converter with passive lossless circuits compared to the conventional interleaved boost converter.

Journal ArticleDOI
Wuhua Li1, X. He1
TL;DR: In this paper, an active-clamp circuit is introduced to clamp the switch turn-off voltage spikes effectively and to recycle the leakage energy, and a family of ZVT interleaved boost converters for high efficiency and high step-up DC-DC conversion is deduced.
Abstract: The narrow turn-off period of the conventional boost converters limits their applications in high step-up DC-DC conversion. The voltage gain is extended without an extreme duty-cycle by the winding-coupled inductor structure. However, the leakage inductance induces large voltage spikes when the switch turns off. An active-clamp circuit is introduced here to clamp the switch turn-off voltage spikes effectively and to recycle the leakage energy. Both the main switches and the auxiliary switches are ZVT during the whole switching transition. Meanwhile, the output diode reverse-recovery problem is alleviated because the leakage inductance of the coupled inductors is in series with the output diode. Furthermore, a family of ZVT interleaved boost converters for high efficiency and high step-up DC-DC conversion is deduced. The experimental results based on 40-380 V front-end applications verify the significant improvements in efficiency

Journal ArticleDOI
TL;DR: In this paper, the authors presented a fully integrated multistage interleaved synchronous buck dc-dc converter with on-chip filter inductor and capacitor, which achieved 64% efficiency while providing an output current of 200 mA.
Abstract: The design and analysis of a fully integrated multistage interleaved synchronous buck dc-dc converter with on-chip filter inductor and capacitor is presented. The dc-dc converter is designed and fabricated in 0.18 mum SiGe RF BiCMOS process technology and generates 1.5 V-2.0 V programmable output voltage supporting a maximum output current of 200 mA. High switching frequency of 45 MHz, multiphase interleaved operation, and fast hysteretic controller reduce the filter inductor and capacitor sizes by two orders of magnitude compared to state-of-the-art converters and enable a fully integrated converter. The fully integrated interleaved converter does not require off-chip decoupling and filtering and enables direct battery connection for integrated applications. This design is the first reported fully integrated multistage interleaved, zero voltage switching synchronous buck converter with monolithic output filters. The fully integrated buck regulator achieves 64% efficiency while providing an output current of 200 mA.

Journal ArticleDOI
TL;DR: In this article, a new family of Z-source ac-ac converters with buck-boost ability is proposed, including four switches single-phase structure and six switches threephase structure.
Abstract: A new family of Z-source ac-ac converters with buck-boost ability are proposed, including four switches single-phase structure and six switches three-phase structure. New commutation strategies for these converters are proposed and safe commutation can be achieved without snubber circuit. The commutation strategies are easily to realize by sampling only voltage signals, and two switches are always turned on, so switching loss can be reduced. Analysis based on state-space averaging reveals the relationship between Z-source inductor current and filter inductor current as well as voltage ratio. The design considerations of voltage-fed single-phase topology are given as an example. Simulation results on the voltage-fed topologies and experimental results on voltage-fed single-phase topology verified the unique features of Z-source ac-ac converters and the proposed commutation strategies. These converters have merits such as less conduction and switching loss, less devices, therefore high efficiency and reliability can be achieved.

Journal ArticleDOI
TL;DR: This paper describes a 30-kW (300 V/100 A) interleaved ZCT buck converter operating at 32-kHz effective switching frequency, which is very well suited for the realization of dc power supplies in plasma processes.
Abstract: This paper introduces interleaved zero-current-transition (ZCT) converters where two sets of switches are operating out-of-phase and share the load power equally. Turn-on transitions at zero current and a significant reduction of the losses associated with diode reverse recovery are accomplished through addition of two small inductors. This paper describes a 30-kW (300 V/100 A) interleaved ZCT buck converter operating at 32-kHz effective switching frequency. Losses and efficiency of the experimental prototype compare favorably against the standard and interleaved hard-switched buck converters. Constant frequency operation with low switching losses and low output current ripple is very well suited for the realization of dc power supplies in plasma processes.

Journal ArticleDOI
TL;DR: In this article, a photovoltaic module integrated converter is implemented with a current fed two-inductor boost converter cascaded with a line frequency unfolder, where passive lossless snubbers are employed to recover the energy trapped in the transformer leakage inductance and to minimize the switching losses.
Abstract: In this paper, a photovoltaic (PV) module integrated converter is implemented with a current fed two-inductor boost converter cascaded with a line frequency unfolder. The current source is a sinusoidally modulated two-phase buck converter with an interphase transformer. The boost cell operates at a fixed duty ratio and has an integrated magnetic structure. The two inductors and the transformer are integrated into one magnetic core. Passive lossless snubbers are employed to recover the energy trapped in the transformer leakage inductance and to minimize the switching losses. The two-inductor boost converter output interfaces with the mains via an unfolding stage, where the MOSFETs are driven by the PV gate drivers. Experimental results are provided for a 100-W converter developing a single phase 240-V 50-Hz output

Journal ArticleDOI
TL;DR: A transformer-based resonator is proposed to be used to build a dual-mode oscillator, e.g., a system capable of oscillating at two different frequencies without recurring to switched inductors, switched capacitors, or varactors.
Abstract: In this brief, we propose to use a transformer-based resonator to build a dual-mode oscillator, e.g., a system capable of oscillating at two different frequencies without recurring to switched inductors, switched capacitors, or varactors. The behavior of the resonator configured as a one-port and a two-port network is studied analytically, and the dependence of the quality factor on the design parameters is thoroughly explored. These results, combined with the use of traditional frequency tuning techniques, are applied to the design of a wide-band voltage-controlled oscillator (VCO) that covers the frequency range 3.6-7.8 GHz. The performance of the designed VCO, implemented in a digital 0.13-mum CMOS technology, has been studied by transistor-level and 2.5D electromagnetic simulation (Agilent Momentum). A typical phase noise performance at 1-MHz offset of -104 dBc/Hz has been predicted, while the power consumption ranges from 1 to 8 mW, depending on the VCO configuration

Patent
31 Oct 2007
TL;DR: In this paper, a TANK filter is provided for a lead wire of an active medical device (AMD), which includes a capacitor in parallel with an inductor, where values of capacitance and inductance are selected such that the filter is resonant at a selected frequency.
Abstract: A TANK filter is provided for a lead wire of an active medical device (AMD). The TANK filter includes a capacitor in parallel with an inductor. The parallel capacitor and inductor are placed in series with the lead wire of the AMD, wherein values of capacitance and inductance are selected such that the TANK filter is resonant at a selected frequency. In a preferred form, the TANK filter reduces or even eliminates the use of ferro-magnetic materials, and instead uses non-ferromagnetic materials so as to reduce or eliminate MRI image artifacts or the force or torque otherwise associated during an MRI image scan.

Proceedings ArticleDOI
Jee-Hoon Jung1, Joong-Gi Kwon1
01 Sep 2007
TL;DR: In this article, a LLC resonant topology is analyzed to derive efficiency and cost-optimal design for wide input ranges and load variations in the LLC converter, a wide range of output power is controlled with only a narrow variation in operating frequency since this converter is capable of both step-up and stepdown.
Abstract: A LLC resonant topology is analyzed to derive efficiency and cost optimal design for wide input ranges and load variations In the LLC converter, a wide range of output power is controlled with only a narrow variation in operating frequency since this converter is capable of both step-up and step-down In addition, ZVS turn-on and ZCS turn-off of MOSFETs and diode rectifiers can be achieved over the entire operating range Finally, the inductance of a resonant tank in the primary side can be merged in the main power transformer by resonant inductance and the absence of the secondary filter inductor makes low voltage stress on secondary rectifier and cost-effective property DC characteristics and input-output response in frequency domain are obtained with the equivalent circuit derived by first harmonic approximation (FHA) method In addition, operational principles are explained to show the ZVS and ZCS conditions of primary switches and output diode rectifiers, respectively Efficiency and cost optimal design rules of the LLC resonant converter are derived by a primary resonant network, operating frequency, and dead time duration Proposed analysis and designation are proved by experimental results with a 400 W LLC resonant converter

Journal ArticleDOI
TL;DR: Average current sharing is in-depth modeled and analyzed and reveals that the state-of-the-art current-sharing technique for multiphase buck converters cannot be directly applied to isolated current-doubler rectifier (CDR) dc-dc converters to achieve balanced inductor currents.
Abstract: Current sharing among inductors is an important issue in both isolated and nonisolated dc-dc converters. In this paper, average current sharing is in-depth modeled and analyzed for both interleaved multiphase buck converters and isolated current-doubler dc-dc converters. The features and comparison of various current-sharing techniques used in isolated and nonisolated dc-dc converters are presented, and the corresponding design guidelines are provided based on the theoretical analysis. The analysis reveals that the state-of-the-art current-sharing technique for multiphase buck converters cannot be directly applied to isolated current-doubler rectifier (CDR) dc-dc converters to achieve balanced inductor currents. Passive and active current-sharing methods are proposed for isolated current-doubler dc-dc converters to balance two inductor currents. Experimental results are presented to verify the modeling analysis and the proposed current-sharing techniques for CDRs in isolated dc-dc converters.

Journal ArticleDOI
TL;DR: A classification scheme is used to categorize tapped-inductor switched-mode power supplies and offers a way of ensuring that no tapped inductor converter circuit is neglected when a tapped-inductive circuit is to be chosen for any particular application.
Abstract: A classification scheme is used to categorize tapped-inductor switched-mode power supplies. This new scheme allows the many possible circuit variants to be displayed in a logical manner and analyzed for practicality and performance. The scheme offers a way of ensuring that no tapped inductor converter circuit is neglected when a tapped-inductor circuit is to be chosen for any particular application.

Journal ArticleDOI
TL;DR: In this article, a resonant gate drive circuit for synchronous buck converter was proposed, which charges and discharges the gate of MOSFET at a constant current during switching interval.
Abstract: This paper proposes a new resonant gate drive circuit for driving both the control metal oxide semiconductor field effect transistor (MOSFET) and synchronous MOSFET in a synchronous buck converter. The circuit can recover more than 70% of the conventional gate drive loss. More importantly, the driving circuit can also reduce the switching loss. It charges and discharges the gate of MOSFET at a constant current during switching interval. Other advantages of the proposed circuit include better noise immunity for dv/dt turn on, less sensitive to parasitic track inductance. The experimental prototype shows that the loss reduction is 10% of the output power for 12 V input, 1.5 V/15 A output with switching frequency of 1 MHz.

Journal ArticleDOI
07 May 2007
TL;DR: In this paper, a quasi-active power factor corrector (PFC) was proposed for driving a string of high brightness light emitting diodes (HB LEDs) for general lighting applications.
Abstract: High brightness light emitting diodes (HB LEDs) are likely to be used for general lighting applications due to their high efficiency and longer life. The paper presents a quasi-active power factor corrector (PFC) for driving a string of HB LEDs. The single-stage PFC circuit has a high efficiency, and it does not increase the voltage/current stress on the active switch used in the switching converter due to PFC. The circuit has two operating modes based on the input voltage level and its features, like power factor correction and power balance, are explained. The experimental results obtained on a prototype converter along with waveforms are presented.

Journal ArticleDOI
TL;DR: The proposed GM-C filter-based, fully integrated current-sensing CMOS scheme circumvents this accuracy limitation by introducing a self-learning sequence to start-up and power-on-reset, translating to a 2.6% power efficiency savings when compared to the more traditional but accurate series-sense resistor technique.
Abstract: Sensing current is a fundamental function in power supply circuits, especially as it generally applies to protection and feedback control. Emerging state-of-the-art switching supplies, in fact, are now exploring ways to use this sensed-current information to improve transient response, power efficiency, and compensation performance by appropriately self-adjusting, on the fly, frequency, inductor ripple current, switching configuration (e.g., synchronous to/from asynchronous), and other operating parameters. The discontinuous, non-integrated, and inaccurate nature of existing lossless current-sensing schemes, however, impedes their widespread adoption, and lossy solutions are not acceptable. Lossless, filter-based techniques are continuous, but inaccurate when integrated on-chip because of the inherent mismatches between the filter and the power inductor. The proposed GM-C filter-based, fully integrated current-sensing CMOS scheme circumvents this accuracy limitation by introducing a self-learning sequence to start-up and power-on-reset. During these seldom-occurring events, the gain and bandwidth of the internal filter are matched to the response of the power inductor and its equivalent series resistance (ESR), effectively measuring their values. A 0.5 mum CMOS realization of the proposed scheme was fabricated and applied to a current-mode buck switching supply, achieving overall DC and AC current-gain errors of 8% and 9%, respectively, at 0.8 A DC load and 0.2 A ripple currents for 3.5 muH-14 muH inductors with ESRs ranging from 48 mOmega to 384 mOmega (other lossless, state-of-the-art solutions achieve 20%-40% error, and only when the nominal specifications of the power MOSFET and/or inductor are known). Since the self-learning sequence is non-recurring, the power losses associated with the foregoing solution are minimal, translating to a 2.6% power efficiency savings when compared to the more traditional but accurate series-sense resistor (e.g., 50 mOmega) technique.

Journal ArticleDOI
TL;DR: In this paper, a simple treatment for the fringing fields of an air gap in the core of a magnetic component such as an inductor or a transformer is described, and the authors verify the derived analytical formulas for the fields by using numerical (finite-element) calculations.
Abstract: The paper describes a simple treatment for the fringing fields of an air gap in the core of a magnetic component such as an inductor or a transformer. It verifies the derived analytical formulas for the fields by using numerical (finite-element) calculations. It then applies these formulas to the calculation of high-frequency eddy-current losses for two types of winding arrangements, both of which employ thin rectangular conductors. The rectangular conductors are commonly used in flex circuit windings, printed circuit windings, and thin-film windings. The two types of winding configurations are flat and barrel wound. Each behaves in a different way as a function of the position of the conductor.

Journal ArticleDOI
TL;DR: It is shown that the minimization of the circulating current can be achieved if both the active current and reactive current of the equivalent load are evenly distributed among activated inverter modules.
Abstract: The control issue of multiple inverter modules operated in parallel is investigated for high-frequency alternative current (HFAC) power distribution architectures, where multiple high-frequency resonant inverters are connected in parallel to the high-frequency high-voltage low-current (HVLC) AC bus, to feed a number of point-of-use power supplies. The circulating current in the multiple inverter system is analyzed first. A novel control scheme is proposed based on the active and reactive current decomposition concept. In the proposed control, there are two loops: 1) the current sharing control loop and 2) the voltage feedback control loop. For the current sharing loop, the active current and reactive current are controlled separately. It is shown that the minimization of the circulating current can be achieved if both the active current and reactive current of the equivalent load are evenly distributed among activated inverter modules. This control method is superior to the scalar control where only the magnitudes of the currents are controlled. Performance is verified with both simulations and experiments on a prototype HFAC power distribution system where two two-stage resonant inverter modules of 500 kHz and 100 W are connected in parallel through small connection inductors to the 500-kHz 28-V rms HFAC bus.

Journal ArticleDOI
TL;DR: In this paper, a broadband and scalable lumped-element model for silicon on-chip transformers is presented, which is driven from layout and process technology specifications, and simple and accurate expressions for evaluating the self inductance and the mutual coupling coefficient are provided.
Abstract: A broadband and scalable lumped-element model for silicon on-chip transformers is presented. Model elements are driven from layout and process technology specifications. We provide simple and accurate expressions for evaluating the self inductance and the mutual coupling coefficient. The effects of various layout parameters, including transformer area, number of turns, and turns ratio, on transformer electrical response have been investigated. Model accuracy is demonstrated by comparing simulated and measured S-parameters, minimum insertion loss, quality factor, coils inductance, and magnetic coupling of several transformers with a wide range of configurations

Patent
13 Aug 2007
TL;DR: In this paper, a tank filter is provided for a lead wire of an active medical device (AMD), which includes a capacitor in parallel with an inductor, and a passageway through the tank filter permits selective slidable passage of a guide wire therethrough for locating the lead wire in an implantable position.
Abstract: A tank filter is provided for a lead wire of an active medical device (AMD). The tank filter includes a capacitor in parallel with an inductor. The parallel capacitor and inductor are placed in series with the lead wire of the AMD, wherein values of capacitance and inductance are selected such that the tank filter is resonant at a selected frequency. A passageway through the tank filter permits selective slidable passage of a guide wire therethrough for locating the lead wire in an implantable position. The Q of the inductor may be relatively maximized and the Q of the capacitor may be relatively minimized to reduce the overall Q of the tank filter to attenuate current flow through the lead wire along a range of selected frequencies. In a preferred form, the tank filter is integrated into a TIP and/or RING electrode for an active implantable medical device.