RLC circuit

About: RLC circuit is a research topic. Over the lifetime, 14490 publications have been published within this topic receiving 142697 citations.

Detunable rf tags

Abstract: An RF tag suitable for use for electronic article surveillance comprises a tuned circuit formed by an inductive coil, which behaves as an antenna on a first side of a substrate electrically connected to a capacitor having plates on each side of an dielectric layer which may be the substrate. The capacitor and coil together form a resonant circuit. To permit deactivation of the tag the circuit also includes a discontinuity closed by a switch composition whose conducting properties can be changed from an insulating state to a conducting state when the tag is subjected to a strong electric field at or around its resonant frequency. The switch composition may, for example, be arranged to short out the capacitor plates or introduce additional capacitor plates or change the properties of the inductive coil. Alternatively the switch composition may introduce additional components (e.g. an IC) into the circuit. The tag may be arranged for sequential retuning to give a multifrequency tag. The switch composition may, for example, be an ink formulation containing 5 to 75 % by weight a metal, preferably in the form of flakes. The switch composition may further contain oxygen scavengers or ionic species to improve the response of the switch composition and/or prevent the switch composition reverting to the insulating state.

Method for driving an ultrasonic transducer

Abstract: An electronic control system for determining the resonant frequency of and driving ultrasonic transducers in a phacoemulsification probe used for ophthalmic surgery. The control system includes a voltage control led oscillator, power amplifier, power monitor, and automatic gain control circuit operating under the direction of command signals received from a microprocessor-based control console. The control system operates in a constant apparent power, direct drive mode with closed loop feedback maintaining the electrical power provided to the primary of a RLC transformer at the constant level requested by the command signals from the console. The frequency of the drive signal is held at the dominant resonant frequency of the ultrasonic transducer which is being driven by the control system. This resonant frequency is determined via a calibration procedure performed when the probe is first attached to the control system. During this procedure a constant voltage drive signal is swept through a range of frequencies and the electrical power consumed by the transducer is measured and stored at selected intervals such as 100 Hertz increments. The resonant frequency is also determined in part by looking for the frequency at which maximum power is consumed by the probe. The stored data is also subjected to other tests to cheok that the peak is indeed a resonant frequency and that the probe has selected output power characteristics about this resonant frequency thus helping to ensure that the probe is capable of operating satisfactorily when driven by the control system.

Parameterization of Three-Phase Electric Machine Models for EMI Simulation

Abstract: A systematic and practical method to parameterize three-phase electric machine models for electromagnetic interference (EMI) simulation is presented. The proposed behavioral model consists of multiple sections of linear RLC circuits and is intended for time-domain simulation with inverters and other power electronic circuits found in typical motor drive systems. The proposed parameterization method uses a differential-mode (DM) and a common-mode (CM) impedance measurement of the machine and takes advantage of the separation among different parallel and series resonant frequencies of each impedance to determine the parameters of each stage in a noniterative manner. The proposed method can also be applied to model three-phase cables and transformers.

A unified discrete-time state-space model for switching converters

Abstract: A unified nonlinear state-space model for arbitrary switching converters is presented, which uses discrete-time modeling of switches. Although its compact and powerful notation is valid for all types of switching circuits, perhaps its main application field is power electronics. The proposed model is valid for any electric circuit composed of ideal switches (externally or internally controlled), RLC elements and energy sources. Therefore, the model is general considering semiconductor devices as ideal switches, which are dealt with as discrete-time dynamic systems. Thus the developed model may be either a hybrid continuous-discrete-time one or a full discrete-time one. Moreover, this model is valid as a circuit simulator. >