Showing papers on "Inductor published in 1996"

Electric surgical apparatus

Abstract: PURPOSE: To utilize an electrosurgical apparatus for electric surgical treatment, particularly for tissue cutting, by increasing an output voltage. CONSTITUTION: In an electrosurgical apparatus for drying and cutting a tissue, an electric surgical generator has a negative charge capacitance CL and output inductor L connected in series. The capacitance contains an electrode unit and a cable connected with a generator output 12A. The inductor forms a resonant circuit connected in series. Frequency of the resonant circuit connected in series is typically 1.5f, wherein f is operating frequency. The capacitor is included between conductors and bonded with them. By the conductors, a bipolar electrode 20E is connected with the generator in order to increase negative charge capacitance CL.

Planar magnetic element

Abstract: Disclosed herein is a planar magnetic element comprising a substrate, a first magnetic layer arranged over the substrate, a first insulation layer arranged over the first magnetic layer, a planer coil formed of a conductor, having a plurality of turns, arranged over the first insulation layer and having a gap aspect ratio of at least 1, the gap aspect ratio being the ratio of the thickness of the conductor to the gap between any adjacent two of the turns, a second insulation layer arranged over the planar coil, and a second magnetic layer arranged over the second insulation layer. When used as an inductor, the planar magnetic element has a great quality coefficient Q. When used as a transformer, it has a large gain and a high voltage ratio. Since the element is small and thin, it is suitable for use in an integrated circuit, and can greatly contribute to miniaturization of electronic devices.

Compact equivalent circuit model for the skin effect

Abstract: Rules for determining a compact circuit model consisting of four resistors and three inductors to accurately predict the skin effect have been developed. The circuit is easily constructed from the geometry, producing a response that matches exact results over a frequency range from dc to very high frequencies.

Control topology options for single-phase UPS inverters

Abstract: Several control topologies for single-phase UPS inverters are presented and compared, with the common objective of providing a dynamically stiff, low THD, sinusoidal output voltage. Full state feedback, full state command controllers are shown utilizing both filter inductor current and filter capacitor current feedback to augment output voltage control. All controllers presented include output voltage decoupling in a manner analogous to "back-EMF" decoupling in DC motor drives. Disturbance input decoupling of the load current and its derivative is presented. An observer-based controller is additionally considered, and is shown to be a technically viable, economically attractive option. The accuracy transfer function of the observer estimate is used to evaluate its measurement performance. Comparative disturbance rejection is evaluated by overlaying the dynamic stiffness (inverse of output impedance) frequency response of each controller on a single plot. Experimental results for one controller are presented.

Nonlinear-carrier control for high-power-factor boost rectifiers

Abstract: Novel nonlinear-carrier (NLC) controllers are proposed for high-power-factor boost rectifiers. In the NLC controllers, the switch duty ratio is determined by comparing a signal derived from the main switch current with a periodic, nonlinear carrier waveform. As a result, the average input current follows the input line voltage. The technique is suitable for boost converters operating in the continuous conduction mode. Input voltage sensing, the error amplifier in the current-shaping loop, and the multiplier/divider circuitry in the voltage feedback loop are eliminated. The current-shaping is based on switch (as opposed to inductor) current sensing. The NLC controllers offer comparable or improved performance over existing schemes, and are well suited for simple integrated-circuit implementation. Experimental verification on a 240 W rectifier is described.

Electrical Engineering: Principles and Applications

Abstract: (NOTE: Each chapter concludes with Summary and Problems.) I. CIRCUITS. 1. Introduction. Overview of Electrical Engineering. Circuits, Currents, and Voltages. Power and Energy. Kirchhoff's Current Law. Kirchhoff's Voltage Law. Introduction to Circuit Elements. Introduction to Circuits. 2. Resistive Circuits. Resistances in Series and Parallel. Network Analysis by Using Series and Parallel Equivalents. Voltage-Divider and Current-Divider Circuits. Node-Voltage Analysis. Mesh-Current Analysis. Thevenin and Norton Equivalent Circuits. Superposition Principle. Wheatstone Bridge. 3. Inductance and Capacitance. Capacitance. Capacitances in Series and Parallel. Physical Characteristics of Capacitors. Inductance. Inductances in Series and Parallel. Practical Inductors. Mutual Inductance. 4. Transients. First-Order RC Circuits. DC Steady State. RL Circuits. RC and RL Circuits with General Sources. Second-Order Circuits. 5. Steady-State Sinusoidal Analysis. Sinusoidal Currents and Voltages. Phasors. Complex Impedances. Circuit Analysis with Phasors and Complex Impedances. Power in AC Circuits. Thevenin and Norton Equivalent Circuits. Balanced Three-Phase Circuits. 6. Frequency Response, Bode Plots, and Resonance. Fourier Analysis, Filters, and Transfer Functions. First-Order Lowpass Filters. Decibels, the Cascade Connection, and Logarithmic Frequency Scales. Bode Plots. First-Order Highpass Filters. Series Resonance. Parallel Resonance. Ideal and Second-Order Filters. Digital Signal Processing. II. DIGITAL SYSTEMS. 7. Logic Circuits. Basic Logic Circuit Concepts. Representation of Numerical Data in Binary Form. Combinatorial Logic Circuits. Synthesis of Logic Circuits. Minimization of Logic Circuits. Sequential Logic Circuits. 8. Microcomputers. Computer Organization. Memory Types. Digital Process Control. The Motorola 68HC11/12. The Instruction Set and Addressing Modes for the 68HC11. Assembly-Language Programming. 9. Computer-Based Instrumentation Systems. Measurement Concepts and Sensors. Signal Conditioning. Analog-to-Digital Conversion. LabVIEWaA A . III. ELECTRONICS. 10. Diodes. Basic Diode Concepts. Load-Line Analysis of Diode Circuits. Zener-Diode Voltage-Regulator Circuits. Ideal-Diode Model. Piecewise-Linear Diode Models. Rectifier Circuits. Wave-Shaping Circuits. Linear Small-Signal Equivalent Circuits. 11. Amplifiers: Specifications and External Characteristics. Basic Amplifier Concepts. Cascaded Amplifiers. Power Supplies and Efficiency. Additional Amplifier Models. Importance of Amplifier Impedances in Various Applications. Ideal Amplifiers. Frequency Response. Linear Waveform Distortion. Pulse Response. Transfer Characteristic and Nonlinear Distortion. Differential Amplifiers. Offset Voltage, Bias Current, and Offset Current. 12. Field-Effect Transistors. NMOS and PMOS Transistors. Load-Line Analysis of a Simple NMOS Amplifier. Bias Circuits. Small-Signal Equivalent Circuits. Common-Source Amplifiers. Source Followers. CMOS Logic Gates. 13. Bipolar Junction Transistors. Current and Voltage Relationships. Common-Emitter Characteristics. Load-Line Analysis of a Common-Emitter Amplifier. pnp Bipolar Junction Transistor. Large-Signal DC Circuit Models. Large-Signal DC Analysis of BJT Circuits. Small-Signal Equivalent Circuits. Common-Emitter Amplifiers. Emitter-Followers. 14. Operational Amplifiers. Ideal Operational Amplifiers. Summing-Point Constraint. Inverting Amplifiers. Noninverting Amplifiers. Design of Simple Amplifiers. Op-Amp Imperfections in the Linear Range of Operation. Nonlinear Limitations. DC Imperfections. Differential and Instrumentation Amplifiers. Integrators and Differentiators. Active Filters. IV. ELECTROMECHANICS. 15. Magnetic Circuits and Transformers. Magnetic Fields. Magnetic Circuits. Inductance and Mutual Inductance. Magnetic Materials. Ideal Transformers. Real Transformers. 16. DC Machines. Overview of Motors. Principles of DC Machines. Rotating DC Machines. Shunt-Connected and Separately Excited DC Motors. Series-Connected DC Motors. Speed Control of DC Motors. 17. AC Machines. Three-Phase Induction Motors. Equivalent Circuit and Performance Calculations for Induction Motors. Synchronous Machines. Single-Phase Motors. Stepper Motors. Appendix A: Complex Numbers. Appendix B: Nominal Values and the Color Code for Resistors. Appendix C: Preparing for the Fundamentals of Engineering Exam. Appendix D: Computer-Aided Circuit Analysis. Index.

A soft-switched, full-bridge boost converter employing an active-clamp circuit

Abstract: A new full-bridge, active-clamp boost converter is proposed for single-phase high power PFC applications and applications requiring transformer isolation. The active-clamp network serves to limit bridge switch turn-off voltage overshoot and enable the energy stored in the transformer leakage inductance to be used for zero-voltage switching. PWM phase-shift control of the bridge switches is utilized to obtain zero-current switching for two of the four bridge switches. Simulation results are presented which verify the principle of operation.

Zero voltage and zero current switching full bridge PWM converter using secondary active clamp

Abstract: A new zero voltage and zero current switching (ZVZCS) full bridge (FB) PWM converter is proposed to improve the performance of the previously presented ZVZCS-FB-PWM converters. By adding a secondary active clamp and controlling the clamp switch moderately, ZVS (for leading leg switches) and ZCS (for lagging leg switches) are achieved without any lossy components, the reverse avalanche break down of leading-leg IGBTs or the saturable reactor in the primary. Many advantages including simple circuit topology, high efficiency, and low cost make the new converter attractive for high voltage and high power (>10 kW) applications. The principle of operation is explained and analyzed. The features and design considerations of the new converter are also illustrated and verified on a 1.8 kW, 100 kHz IGBT based experimental circuit.

VHF CMOS integrated active inductor

Abstract: The implementation of an RF CMOS active inductor is described. The circuit is based on a recently proposed CMOS GIC. The inductor loss is reduced by applying gain enhancement techniques based on cascoding. The proposed new inductors exhibit lower loss, high self-resonance frequency and wider inductive region. An RLC bandpass filter response is realised to verify the performance of the simulated inductor.

Applications of the current feedback operational amplifiers

Abstract: The current feedback operational amplifiers (CFOAs) are receiving increasing attention as basic building blocks in analog circuit design. This paper gives an overview of the applications of the CFOAs, in particular several new circuits employing the CFOA as the active element are given. These circuits include differential voltage amplifiers, differential integrators, nonideal and ideal inductors, frequency dependent negative resistors and filters. The advantages of using the CFOAs in realizing low sensitivity universal filters with grounded elements will be demonstrated by several new circuits suitable for VLSI implementation. PSPICE simulations using the AD844-CFOA which indicate the frequency limitations of some of the proposed circuits are included.

An improved soft switching PWM FB DC/DC converter for reducing conduction losses

Abstract: An improved soft-switching topology of a full-bridge (FB) pulsewidth-modulated (PWM) DC/DC converter is described. The new topology employs an energy-recovery snubber to minimize a circulating current flowing through the transformer and switching devices. By using an energy-recovery snubber instead of adding a tapped inductor and a saturable reactor to reduce RMS current stress, the converter achieves zero-current switching (ZCS) for the right leg due to the minimized circulating current and achieves zero-voltage switching (ZVS) for the left leg due to the reflected output current during the interval of left leg transition. Both analysis and experiments are performed to verify the proposed topology by implementing a 7 kW (120 VDC, 58 A) 30 kHz insulated gate bipolar transistor (IGBT) based experimental circuit.

Design of microfabricated transformers and inductors for high-frequency power conversion

Abstract: Transformers and inductors fabricated with micron-scale magnetic-alloy and copper thin films are designed for high-frequency power conversion applications. Fine patterning produced by photolithography reduces eddy current losses, thus enabling very high power densities. Calculated design graphs and design examples for 10 MHz transformers are presented.

Multilevel-spiral inductors using VLSI interconnect technology

Abstract: A multilevel-spiral (MLS) inductor structure for implementation in VLSI interconnect technology is presented. Inductances of 8.8 and 32 nH and maximum quality-factors (Q) of /spl sim/6.8 and 3.0, respectively, are achieved in a four-level metal BiCMOS technology, with four turns at each of the two or four stacked spiral coils and with an area of 226/spl times/226 /spl mu/m/sup 2/. The comparison of the MLS inductors to different single-level-spiral (SLS) control devices shows that a MLS inductor provides the same inductance at /spl sim/50% dc resistance, but the maximum Q is typically measured at a lower frequency and the self-resonance frequency is reduced due to a high inter-wire capacitance.

The Modeling and Simulation of a Proportional Solenoid Valve

Abstract: A nonlinear dynamic model of a high speed direct acting solenoid valve is presented. The valve consists of two subsystems ; a proportional solenoid and a spool assembly. These two subsystems are modeled separately. The solenoid is modeled as a nonlinear resistor/inductor combination, with inductance parameters that change with displacement and current. Empirical curve fitting techniques are used to model the magnetic characteristics of the solenoid, enabling both current and magnetic flux to be simulated. The spool assembly is modeled as a spring/mass/damper system. The inertia and damping effects of the armature are incorporated in the spool model. The solenoid model is used to estimate the spool force in order to obtain a suitable damping coefficient value. The model accurately predicts both the dynamic and steady-state response of the valve to voltage inputs. Simulated voltage, current, and displacement results are presented, which agree well with experimental results.

Methods and apparatus for measuring temperatures at high potential

Abstract: A thermocouple is provided which measures the temperatures of structures at high RF potential, such as an RF electrode within a plasma CVD or plasma etch reactor. The thermocouple includes an outer conductive sheath that connects to the RF electrode at a first location, and a wire pair, connected to a second location of the RF electrode, that is used to sense the RF electrode temperature. The sheath--or a conductive member connected in circuit with the sheath--is wound into a coil to form an inductor with an impedance much greater than the impedance of the RF electrode. A large capacitor grounds the coil so that the thermocouple wires, extending through the sheath, and through and out of the coil, are available for diagnostic purposes. While RF current flows through the sheath, the wires experience the same magnetic field generated by the inductive coil, substantially grounding the thermocouple. Preferably, signal conditioning electronics remove any remaining DC bias voltages. In the case of a reactor for plasma CVD or etch, the thermocouple can be enclosed within a vacuum-sealed RF feedthrough that conducts the RF energy to the electrode.

Linear peak current mode control: a simple active power factor correction control technique for continuous conduction mode

Abstract: A simplified power factor correction (PFC) technique for continuous conduction mode (CCM) operated power converters is presented which has the following advantages over conventional peak and average current mode PFC techniques: elimination of the controller multiplier and input voltage sensing circuits; unconditional stability of the current loop; and ease of implementation using low cost standard PWM control ICs (e.g. UC2843). Simulation and experimental results verify the viability of the new controller.

Technique for reducing rectifier reverse-recovery-related losses in high-voltage high power converters

Abstract: A circuit technique that substantially reduces the boost-converter losses caused by the reverse-recovery characteristics of the rectifier is described The losses are reduced by inserting an inductor in the series path of the boost switch and the rectifier to control the di/dt rate of the rectifier during its turn-off The energy from the inductor after the boost switch turn-off is returned to the input or delivered to the output via an active snubber The same technique can be extended to any member of the PWM-converter family

Modeling Litz-wire winding losses in high-frequency power inductors

Abstract: The parasitic effects in stranded, twisted, and Litz wire windings operating at high frequencies are studied. The skin and proximity effects that cause the winding parasitic resistance of an inductor to increase with the operating frequency are considered. An expression for the AC resistance as a function of the operating frequency is given. The measured and calculated values of the inductor AC resistance and quality factor are plotted versus frequency and compared. The theoretical results were in good agreement with those experimentally measured.

In-situ monitoring of the change in thickness of films

Abstract: The change in thickness of a film on an underlying body such as a semiconductor substrate is monitored in situ by inducing a current in the film, and as the thickness of the film changes (either increase or decrease), the changes in the current are detected. With a conductive film, eddy currents are induced in the film by a generating an alternating electromagnetic field with a sensor which includes a capacitor and an inductor.

Integrated circuit toroidal inductor

Abstract: High quality factor (Q) spiral and toroidal inductor and transformer are disclosed that are compatible with silicon very large scale integration (VLSI) processing, consume a small IC area, and operate at high frequencies. The spiral inductor has a spiral metal coil deposited in a trench formed in at dielectric layer over a substrate. The metal coil is enclosed in ferromagnetic liner and cap layers, and is connected to an underpass contact through a metal filled via in the dielectric layer. The spiral inductor also includes ferromagnetic cores lines surrounded by the metal spiral coil. A spiral transformer is formed by vertically stacking two spiral inductors, or placing them side-by-side over a ferromagnetic bridge formed below the metal coils and cores lines. The toroidal inductor includes a toroidal metal coil with a core having ferromagnetic strips. The toroidal metal coil is segmented into two coils each having a pair of ports to form a toroidal transformer.

Principle and characteristics of a fault current limiter with series compensation

Abstract: A power system fault current limiter with series compensation, which is composed of a compensation capacitor and a limiting reactor in series, is proposed. A solid-state switch connected in parallel with the capacitor controls either the ordinal series compensation or fault current limitation. A feasibility study of the current limiter by simulation analysis is presented and the effectiveness of the current limiter is evaluated from the viewpoints of transient stability improvement and device capacity. The current limiter is a useful protection device for large, high power transmission systems.

Resonant converter with controlled inductor

Abstract: An LC resonant circuit for a resonant converter includes a resonant capacitor and an inductor coupled to a fixed frequency AC supply. A controlled inductor in parallel with the resonant capacitor is controlled by a DC current to vary its inductance. The controlled inductor comprises a magnetic core having one or more power windings, and a control winding wound on the core. The DC current in the control winding produces core flux which effects core permeability. The controlled inductor has the effect of changing the capacitor impedance and thus influences the converter output. Multiple, independently controlled and regulated outputs may be driven by one power switching stage.

A new permeance meter based on both lumped elements/transmission line theories

Abstract: We have developed a new permeance meter in the 1 MHz-1.5 GHz range using either a microstrip pickup coil or a shielded loop pickup coil. Both pickup coils and the driving plates are free from LC resonance due to impedance matching. In the MHz range we must consider signal-to-noise ratio of the pickup coil. In the GHz range we must eliminate the voltage induced by the electric field, and an electromagnetic higher order mode in the driving plates.

Compact and efficient transformerless power conversion system

Abstract: The power conversion system (PCS) developed by the author is a new technology that efficiently transforms power between AC and DC. The conversion process permits the input voltage level to be stepped up or down without the use of magnetic core transformers. The transformation is accomplished using solid state switching devices, capacitors, air-core inductors and an intelligent control system. The technology is based on the property of resonance charging, thereby permitting the use of self commutating switches. The current through the switches, being sinusoidal in nature, has a low dI/dt. This permits the use of slower, less expensive thyristors, similar to those used in high voltage phase control applications. Using these components, a highly efficient inverter can be constructed for a variety of large utility applications.

Single magnetic low loss high frequency converter

Abstract: An improved magnetically integrated power converter which are provided specifically for use with power supplies with high density requirements. The converters comprise an integrated magnetic device integrating the functions of two transformers and three inductors. The integrated magnetic device is implemented on a three-leg core with two secondary windings and one primary winding, each winding on one of the core legs. The primary winding connects to the input dc voltage source by either a forward type arrangement or a half-bridge type circuit arrangement. Each secondary winding connects to the output through a rectifier. The turns number for two secondary windings can be different in order to achieve wider input range or reduced voltage stress.

Magnetic field detector

Abstract: In a magnetic field detector as well as in a combined telemetry and magnetic field detector unit in a medical implant, a magnetic field sensor with a coil and a diode are employed for determining the presence of a magnetic field. For making such a determination, the coil is charged by a source of voltage for a defined period of time, the time for the discharge of the coil through the diode depending on whether a magnetic field is present. A detection signal indicating the presence of a magnetic field is generated if the discharge time is less than a defined time threshold value.

Experimental evaluation of the influence of DC-premagnetization on the properties of power electronic ferrites

Abstract: In many power electronic applications, ferrite cores of magnetic components are biased with a DC or low-frequency premagnetization. Usually however, the influence of the bias on the losses and permeability is not considered in the component design. This paper describes a precise measurement setup to determine the power losses and the magnetization curve of premagnetized ferrites. The measurements on typical ferrites of two major manufacturers prove that the influence of a DC-bias on the material properties cannot be neglected.

Design of microfabricated inductors

Abstract: Possible configurations for microfabricated inductors are considered. Inductance can be set by adjusting permeability through control of anisotropy of a permalloy core, or via a patterned quasi-distributed gap. A design methodology based on a simple model is proposed. Analysis of secondary effects is also developed. A design example for a 5 MHz buck power converter application is presented. A power density of 12.8 W/cm/sup 2/ is possible for an efficiency of 94%.

A novel soft-switched PWM inverter for AC motor drives

Abstract: A novel soft-switched inverter topology is derived from the passively clamped quasi-resonant link (PCQRL) circuit. By introducing magnetic coupling between the two resonant inductors, the number of auxiliary switches can be reduced from two to one, and only a single magnetic core is required for the resonant DC link. An analysis of this novel PCQRL topology with coupled inductors is presented to reveal the various soft-switching characteristics. In comparison with the conventional passively clamped, continuously resonant DC link inverter, this soft-switched inverter can reduce voltage stresses from more than 2 per unit (pu) to 1.1-1.3 pu. It can also provide soft-switched pulse-width modulated (PWM) operation. Simulations and experiments are performed to backup the analysis.

A comparison of two micromachined inductors (bar- and meander-type) for fully integrated boost DC/DC power converters

Abstract: Two micromachined integrated inductors (bar- and meander-type) are realized on a silicon wafer by using modified, IC-compatible, multilevel metallization techniques. Efforts are made to minimize both the coil resistance and the magnetic reluctance by using thick electroplated conductors, cores, and vias. In the bar-type inductor, a 25-/spl mu/m thick nickel-iron permalloy magnetic core bar is wrapped with 30-/spl mu/m thick multilevel copper conductor lines. For an inductor size of 4 mm/spl times/1.0 mm/spl times/110 /spl mu/m thickness having 33 turns of multilevel coils, the achieved specific inductance is approximately 30 nH/mm/sup 2/ at 1 MHz. In the meander-type inductor, the roles of conductor wire and magnetic core are switched, i.e., a magnetic core is wrapped around a conductor wire. This inductor size is 4 mm/spl times/1.0 mm/spl times/130 /spl mu/m and consists of 30 turns of a 35-/spl mu/m thick nickel-iron permalloy magnetic core around a 10-/spl mu/m thick sputtered aluminum conductor lines. A specific inductance of 35 nH/mm/sup 2/ is achieved at a frequency of 1 MHz. Using these two inductors, switched DC/DC boost converters are demonstrated in a hybrid fashion. The obtained maximum output voltage is approximately double an input voltage of 3 V at switching frequencies of 300 kHz and a duty cycle of 50% for both inductors, demonstrating the usefulness of these integrated planar inductors.