Showing papers on "Electrical network published in 2003"

Lumped Element Modeling of Piezoelectric-Driven Synthetic Jet Actuators

Abstract: : This paper presents a lumped element model of a piezoelectric-driven synthetic jet actuator. A synthetic jet, also known as a zero net mass-flux device, uses a vibrating diaphragm to generate an oscillatory flow through a small orifice or slot. In lumped element modeling (LEM), the individual components of a synthetic jet are modeled as elements of an equivalent electrical circuit using conjugate power variables. The frequency response function of the circuit is derived to obtain an expression for Q(sub out)/V(sub AC), the volume flow rate per applied voltage. The circuit is analyzed to provide physical insight into the dependence of the device behavior on geometry and material properties. Methods to estimate the model parameters are discussed, and experimental verification is presented. In addition, the model is used to estimate the performance of two prototypical synthetic jets, and the results are compared with experiment.

Optimal location assignment and design of superconducting fault current limiters applied to loop power systems

Abstract: Short-circuit current is strongly related to the cost of apparatus and the efficient use of power transmissions. Therefore, the introduction of Superconducting Fault Current Limiters (SFCL's) becomes an effective way for suppressing such a high short-circuit current in loop power systems. Firstly, a method to obtain a smaller SFCL capacity by observing the SFCL behavior including sub-transient and transient effects during a short circuit is proposed. Secondly, we propose using a micro-genetic algorithm (micro-GA) combined with a hierarchical genetic algorithm (HGA) to simultaneously search for the optimal location and the smallest SFCL capacity. The efficiency of the proposed method is shown by numerical examples with a loop power system.

Control of a Civil Structure Using an Electric Machine with Semiactive Capability

Abstract: This paper concerns the implementation of a brushless DC machine as a force actuator, for use in suppressing vibrations in civil structures. The machine has the dual capability of operation as an active as well as semiactive device. It operates semiactively by using the machine as a generator to convert mechanical energy to electrical energy which is then dissipated. The electrical network uses electronic switching to control the power flow from the machine. With the machine shaft connected to a gear reducer and ballscrew mechanism, the result is a device that resembles a linear damper with a controllable damping coefficient. The only external electrical power required is that which is needed to support the control system intelligence and to control the transistors, enabling the device to be operated on battery power. As an example of an application of such an actuator, simulations are performed in which the semiactive device is used to control a three-story structural model, with acceleration feedback control. The structural control system design approach is the well-established “clipped-optimal” method. Results suggest that this actuator is effective in simultaneously suppressing the interstory drifts and the absolute accelerations of the structure. A comparison is made to a similar configuration using a magnetorheological damper as the semiactive force device.

Elliptic Partial Differential-Algebraic Multiphysics Models in Electrical Network Design

Abstract: In refined network analysis, a compact network model is combined with distributed models for semiconductor devices in a multiphysics approach. For linear RLC networks containing diodes as distributed devices, we construct a mathematical model that combines the differential-algebraic network equations of the circuit with elliptic boundary value problems modeling the diodes. For this mixed initial-boundary value problem of partial differential-algebraic equations a first existence result is given.

Electrical network protection system

Abstract: Protection systems for electrical systems are described, where the electrical systems may include spot networks and/or grid networks. The various protection systems may be designed and used to detect and clear faults that may occur within the electrical systems. For example, a pair of Rogowski coils may be used to detect current along a conductors at their respective locations on the conductors, and to output corresponding signals to a multi-function, differential relay having multiple voltage and current inputs. By comparing the signals from the Rogowski coils, the differential relay may determine whether a fault exists at some point along the conductors and between the pair of Rogowski coils. Further, the relay may then, in response to the fault, trip a circuit breaker or other network protection device to address the fault.

Modeling nonlinear dynamics in analog circuits via root localization

Abstract: An algorithm for determining when electrical circuit poles and zeros (i.e., roots) are topologically localized to a node or coupled-pair of nodes is described. Discovering this relationship provides insight to designers for circuit optimization, and is a basis upon which nonlinear dynamic behavioral models can be built. This root localization algorithm, the main contribution of this paper, facilitates the creation of models that more accurately reflect the distinctive behavior of a circuit. This is accomplished by identifying when poles and zeros can be modeled as localized effects whose values change with circuit operating conditions. The underlying modeling approach is described to provide a context for this research. The algorithm is illustrated through several examples.

Methods and apparatus for generating a data structure indicative of an alarm system circuit

Abstract: A user of a computer aided design (CAD) system graphically places fire alarm appliances, such as smoke detectors and sirens, in a drawing area. After elements are placed and physical paths are determined, a series of electrical circuit connections between alarm source elements and alarm appliance elements are determined. The electrical circuit connections define wire gauges and lengths passing through the physical paths. The wire types may be determined by predefined rules, and multiple wires may be placed in a single physical path. Subsequently, the CAD system performs electrical calculations associated with the alarm system. The electrical calculations may be based on a supervisory mode of operation as well as an alarm mode of operation. The resistance of wires in the alarm system may be based on a scaled wire length and/or a schematic (non-scaled) wire length. In one example, a backup battery capacity requirement is calculated.

Transient thermal response of a hot-wire anemometer

Abstract: The ability of a thermal anemometry system to accurately measure unsteady fluid velocity depends on the electrical control system as well as the thermal properties of the sensor. The present work is a numerical study of the thermal transient response of a hot-wire. A conventional constant temperature anemometer with an ideal feedback amplifier as well as a pulse width modulated system were used to model the electrical current supplied to the sensor to maintain a nominally constant sensor resistance. The agreement between these two electrical models confirmed that the response characteristics are only due to thermal effects. The thermal response was tested by providing a known input function for the cooling velocity, and comparing this with the output of the model. The first test used a step input function. It was found that the thermal transient effects along the length of the sensor caused the system to initially under predict the actual velocity increase; this was followed by an exponential increase to the steady state velocity. Secondly, the model was tested with sinusoidal inputs over a wide frequency range. The ratio: indicated-velocity/input-velocity, as a function of the input frequency was used to characterize the 'thermal frequency response'.

Electromagnetic/circuit co-simulation and co-optimization with parametric layout components

Abstract: Simulation of electromagnetic characteristics of an electrical circuit uses netlist data defining component instances, including layout component instances, and their topological interconnection in an electrical circuit. A circuit simulation is performed using the netlist data, involving use of a model for each layout component instance. An attempt is made to retrieve an existing simulation model of the layout component instance from a database of such layout component simulation models. If no suitable simulation model can be found in the database, an attempt is made to interpolate a new simulation model from among existing simulation models in the database. If interpolation is determined not to be feasible, then an electromagnetic simulation of the layout component instance is performed to develop a new electromagnetic simulation model. This new model is used in the circuit simulation, and added to the database for future use.

Load recognition and series arc detection using bandpass filter signatures

Abstract: A method and system for determining whether arcing is present in an electrical circuit includes sensing a change in an alternating current in the circuit and developing a corresponding input signal, analyzing the input signal to determine the presence of broadband noise in a predetermined range of frequencies, and producing a corresponding output signal, and processing the input signal and the output signal in a predetermined fashion to determine whether an arcing fault is present in the circuit The processing includes determining a type of load connected to the electrical circuit, based at least in part upon the input signal and the output signal, and monitoring high frequency noise in a 20 KHz band for each ⅛ cycle of the alternating current

Apparatus and method for location specific authentication using powerline networking

Abstract: A mechanism for ensuring the physical location of data processing devices as a security check is provided. With this mechanism, security data is transmitted to data processing devices via an electrical network and is used to perform a security check to determine if the data processing device may operate. The data processing devices may be limited such that they may only power-up, boot-up, or remain operational when they are coupled to the electrical network. Thus, they must be physically located such that they may gain access to the electrical network. In addition, a security check may be used to control which data processing devices may communicate data packets with one another over the data network. When a data packet is received by a data processing device, security data in the data packet is compared against a local history of security data received by the recipient of the data packet via the electrical network. If matching security data is found in the history for the same time represented by an associated timestamp, then the sending data processing device and the receiving data processing device are determined to be present on the same electrical network and may communicate with one another.

Coupled problem computation of 3-D multiply connected magnetic circuits and electrical circuits

Abstract: This paper presents the theory and the validation of a new finite-element formulation to realize the coupling between electrical circuits and multiply connected magnetic circuits, using a magnetic scalar potential as state variable. For this purpose, we used formulations in reduced magnetic scalar potential versus T/sub 0/ taking into account electrical circuits and a total magnetic scalar potential taking into account cuts.

On Factor Graphs and Electrical Networks

Abstract: Factor graphs are graphical models with origins in coding theory. The sum-product and the max-product algorithms, which operate by message passing in a factor graph, subsume a great variety of algorithms in coding, signal processing, and artificial intelligence. In this paper, factor graphs are used to express a one-to-one correspondence (based on results by Dennis) between a class of static electrical circuits and multi-variable probability distributions; these factor graphs may also be viewed as variational representations of the electrical networks. For the classical linear state space models, both the sum-product algorithm and the max-product algorithm coincide with Kalman filtering. By the mentioned correspondence, these algorithms have a circuit theory interpretation that was discovered by Carter.

A system and method for manufacturing printed circuit boards employing non-uniformly modified images

Abstract: A system and method for fabricating an electrical circuit in which a digital control image (46) is generated by non-uniformly modifying (44) a representation of an electrical circuit (40), such that an electrical circuit pattern (72) recorded on a substrate (12) using the digital control image (46) precisely fits an already formed electrical circuit portion (62).

Dynamic simulation of fuel cells and microturbines integrated with a multimachine network

Abstract: The paper discusses aspects of dynamic modelling and simulation of fuel cell and microturbine units as a part of a multi-machine electrical network. The focus is on the consideration of a large number of units connected to different low voltage nodes. In the study, the total power generated in decentralized units reaches up to 30% of the 110 kV network demands. Therefore, it is expected that decentralized sources impact the dynamic behaviour of the high voltage network and vice versa. Hence, the investigated power system comprises also the high voltage grid and the corresponding conventional power plants supplying into this network. To evaluate the performance of the network, various disturbances are applied and the results are discussed.

System and method to delay closure of a normally closed electrical circuit

Abstract: A system and method are provided to delay closure of an electrical circuit of a battery-powered electrical device, intended to operate remotely in an environment in which the pH value changes from one value to another. Two electrical contacts of an electrical circuit are separated by an insulator that holds the circuit open until the device is exposed to an environment having a predetermined pH value. Exposure of the insulator to an environment having that pH value causes the insulator to dissolve and the circuit to close, energizing the device. Alternatively, A Hall effect transistor or a reed switch may be used as the switch. It is held open by the presence of a magnetic field held in place by material that is dissolvable at a predetermined pH level. When a region having that pH level is reached, the material dissolves and the circuit closes.

Use of analog-valued floating-gate transistors to match the electrical characteristics of interleaved and pipelined

Abstract: Methods of and apparatuses for matching the signal delay, clock timing, frequency response, gain, offset, and/or transfer function of signal pathways in electrical circuits such as, for example, time-interleaved and pipelined circuits using analog-valued floating-gate MOSFETs are disclosed. The methods and apparatuses disclosed are applicable to a variety of circuits, including but not limited to, sample-and-hold or track-and-hold circuits, quadrature mixers, analog-to-digital converters (ADCs), digital-to-analog converters (DACs), analog or digital filters, and amplifiers.

Electric refrigeration compressor having a cooling system for an electrical circuit

Abstract: In an electrical compressor having a motor and an electrical circuit integrated with a compression portion, a part of electrical components of the electrical circuit is disposed in spaces between a cylindrical outer surface of a motor housing and an imaginary flat surface that imaginarily contacts the cylindrical outer surface. Therefore, the spaces can be used effectively, and the electrical compressor can be downsized. Further, the part of the electrical components can be effectively cooled by refrigerant in the motor housing. On the other hand, the outer surface of the motor housing is used as one surface defining an inner space of a casing for accommodating the electrical circuit. In this case, the electrical circuit can be effectively cooled by refrigerant in the motor housing.

Relaxation studies on power equipment

Abstract: This paper describes a method of studying and modeling the dielectric relaxation for stationary power apparatus in an interconnected network to get the necessary aging indicators. The polarization phenomenon was studied using Recovery Voltage (RVM) and Polarization Current (PCM) Measurements on individual power apparatus and on network with other connected apparatus. Because of dielectric absorption in composite insulation, all RVM responses showed a single peak response and the response was linear with charging voltage. PCM decreased monotonically with a sudden drop in the initial period and after 100 s, it decreased very slowly and the response was linear with charging voltage. The responses were analyzed by modeling the dielectric function as an exponential function and as two-time dependent fractional power law function to determine suitable aging parameters. Exponential function model was found to fit both responses to get an equivalent electrical circuit of the system. Interrelation of RVM and PCM was established in most of the cases. Predicted dielectric response function for generator was more linear with time than for transformers and cable. In the frequency plane, it was found to have distinct regions of relaxation spectrum. Studies indicated that the parameters of fit for RVM response with each charging period differed from all RVM responses.

Automobile onboard electrical network sensor device using shunt measuring resistance integrated in onboard electrical network

Abstract: The sensor device detects the current, voltage and/or temperature of an onboard electrical network via a rotationally symmetrical measuring resistance (6), connected between a pair of terminal blocks (4) coupled to current wires (2) of the onboard electrical network, so that it lies coaxial to the current wires. An Independent claim for a manufacturing method for an automobile onboard electrical network sensor device is also included.

Large time-scale electro-thermal simulation for loss and thermal management of power MOSFET

Abstract: In power electronics systems the management of power loss and temperature of switching devices is indispensable for the reliability of the whole system. In this paper, a simple electro-thermal simulation model is presented. This simulation model is capable of predicting the power loss and estimating the junction temperature of power device in various environmental conditions. The electro-thermal model is composed of electrical network model, semiconductor device model and thermal network model. These parts interact with each other to calculate the loss and temperature of device and parameters of each model. By focusing on the slow dynamics of heat sink temperature, the proposed model can be employed for the large time-scale simulations. A 200 W boost converter using a power MOSFET as an active switch and adopting a natural convection cooling aluminum heat sink as a cooling device was taken as an example system. The experimental results are compared with the predicted values of the simulation model.

Determining parameters of an equivalent circuit representing a transmission section of an electrical network

Abstract: A method for determining an equivalent impedance of a transmission section of an electrical network, includes representing the transmission section as having at least two interfaces with other sections of the network. For each interface, a voltage phasor and a current phasor flowing through the interface are determined from simultaneously made measurements at the interfaces. From the phasors, the equivalent impedance is calculated. The required simultaneousness of the phasor measurements is achieved by means of Phasor Measurement Units (PMUs) that are synchronized via the Global Positioning System (GPS).

Apparatus and method of monitoring insulation of a DC network that is electrically insulated with respect to the ground potential of a device

Abstract: Insulation monitoring of an electrical network such as a DC network which is electrically insulated with respect to the ground of a device, includes at least two insulation monitoring devices that monitor different network sections, which can be isolated by one or more switches. Non-contacting switches are used to alternatingly connect and isolate respective measuring resistors of the monitoring devices to, and from, ground, as a result of which the insulation monitoring devices can not negatively affect each other's measurements.

Household food warmer for keeping foods and beverages warm

Abstract: A household food warmer for keeping foods and beverages warm includes a housing, a drawer which can be inserted into the housing, an interior chamber which is bounded by the housing and the inserted drawer and which is used to accommodate foods placed on plates, a heating element, an electrical circuit in which is arranged a first electrical switch for switching on the heating element, and a temperature sensor for measuring the interior chamber temperature. A convection fan is provided. The convection fan can be switched on via a second electrical switch arranged in the electrical circuit and can be switched off via the second electrical switch upon the occurrence of a switching condition that is dependent on the temperature sensor.

Compact power supply

Abstract: The present invention discloses an electrical power supply for providing electrical power to a load, the power supply comprising a plurality of energy storage elements each having a different operating characteristic and connected in an electrical circuit to the load, and a circuit element interposed between at least one of the storage elements and the load and operable to segregate the energy storage elements therefrom, the circuit element being selected to match supply of energy to the load to the characteristics of the storage elements.