Showing papers on "Maximum power principle published in 1997"

Neural network based estimation of maximum power generation from PV module using environmental information

Abstract: This paper presents an application of an artificial neural network for the estimation of maximum power generation from PV module. The output power from a PV module depends on environmental factors such as irradiation and cell temperature. For the operation planning of power systems, the prediction of the power generation is inevitable for PV systems. For this purpose, irradiation, temperature and wind velocity are utilized as the input information to the proposed neural network. The output is the predicted maximum power generation under the condition given by those environmental factors. The efficiency of the proposed estimation scheme is evaluated by using actual data on daily, monthly and yearly bases. The proposed method gives highly accurate predictions compared with predictions using the conventional multiple regression model.

Lighting control with wireless remote control and programmability

Abstract: A remotely controllable and programmable power control unit for controlling and programming the state and power level, including special functions, of one or more electrical devices. The electrical device can be an electric lamp. The system includes a user-actuatable remote transmitter unit and a user-actuatable power control unit adapted to receive control signals from the remote transmitter unit. Both the remote transmitter unit and the power control unit include a power selection actuator for selecting a desired power level between a minimum power level and a maximum power level, and control switches for generating control signals representative of programmed power levels of one or more power scenes and special functions. In response to an input from a user, either directly or remotely, the one or more devices of the one or more power scenes can be controlled between an on or off state, to a desired programmed preset, or to a maximum power level.

Solar power generation apparatus and power control device therefor

Abstract: In order to extract maximum power from a solar cell, maximum power point tracking (MPPT) control is performed under ordinary circumstances. If the output current of the solar cell becomes too small, the operating point of the solar cell is caused to fluctuate over a range wider than that of MPPT control at a period longer than that of MPPT control and the output voltage and current of the solar cell is sampled. In a case where it is indicated by power values obtained from the sample voltage values and current values that a plurality of maximal points of power value exist, a voltage value corresponding to a power value indicative of the largest value is set as the operating point of the solar cell.

Solar cell power source device

Abstract: A solar cell power source device is disclosed which optimizes the power output of the solar cell by detecting a maximum power point of the solar cell and controlling the duty cycle of a switching transistor in a switching power converter such that the output current of the solar cell follows the maximum power point. Also shown is a pulse width modulation controller which multiplies the output voltage of the solar cell by the output current of the solar cell to obtain a power detecting signal, samples the power detecting signal during two different sample periods to determine if the power output is decreasing, and modulating the pulses output to the switching transistor of the switching power converter in order to maintain the power output of the solar cell at the maximum power point.

Control of transmission power in wireless packet data transfer

Abstract: In packet switched data transfer of the cellular radio system, the control of the transmission power comprises characteristics as well of the closed-loop control and the open-loop control. Before forming the connection and during long pauses between the packets, the terminal device measures the control signal transmitted by the base station and compares its signal power (R0) to the target level (t0), that is included by the base station in the control signal as a parameter. The base station informs in the control signal also the transmission power, whereby the terminal device sets the same power to be its transmission power, corrected by the difference between the target level and the measured quality of the link (t0-R0). In addition, also the measured quality of the link (RXQUAL) is transmitted in the acknowledgment messages of the packets, whereby the transmitting device changes its transmission power so that the quality will be controlled to the certain target level. The biggest step of the change is determined by the length of the packets. In the packet transfer downlink, the base station uses first the maximum power and corrects then its transmission power based on the measuring information included in the acknowledgment messages transmitted by the terminal device.

Optimum performance of a regenerative Brayton thermal cycle

Abstract: The optimum performance of a regenerative Brayton cycle was analyzed. The model includes external and internal irreversibilities coming from four main sources: coupling to external heat reservoirs, turbine and compressor nonisentropic processes, pressure losses in the heater and the cooler, and the regenerator. In terms of the parameters accounting for each type of irreversibility, explicit numerical results are presented for the maximum efficiency, maximum power output, efficiency at maximum power output, power output at maximum efficiency, as well as for the pressure ratios required for maximum efficiency and maximum power. This analysis could provide a general theoretical tool for the optimal design and operation of real regenerative gas turbine power plants.

A general property of endoreversible thermal engines

Abstract: In this work we propose that endoreversible Carnot–type heat engines have a general property independent of the heat transfer law used to describe heat exchanges between the working fluid and its thermal reservoirs. This property has to do with the so-called ecological function [F. Angulo–Brown, J. Appl. Phys. 69, 7465 (1991)]. According to this property, the efficiency at the maximum of the ecological function is the semisum of the Carnot and the maximum power efficiencies for any heat transfer law. This result is obtained by using the quasiparabolic behavior of power versus efficiency. From this property, we obtain a corollary over a general quantitative relation between the power (and also the entropy production) of both maximum power and maximum ecological regimes. We also discuss a criterion to find the best ecological function.

A new scheme for maximum photovoltaic power tracking control

Abstract: It is shown that the derivative (dp/sub s//de/sub s/) of output power (p/sub s/) with respect to output voltage (e/sub s/) of a photovoltaic array is equal to zero at the maximum power point. This kind of relationship is independent of insolation and temperature. This property may be utilized to perform maximum power tracking control, that is, at all insolation and temperature levels, the maximum power point can be obtained by regulating dp/sub s//de/sub s/ toward zero. Based on this concept, a new scheme of maximum power tracking control is proposed and applied to a utility-interactive photovoltaic power conditioning system, where the boost chopper is responsible for maximum power tracking control and the inverter responsible for unity power factor control and constant DC input voltage control. The related design method is described. The usefulness and validity of the proposed method are verified by simulation. Compared to conventional methods, this method show a considerably high tracking performance.

Estimation of maximum power and instantaneous current using a genetic algorithm

Abstract: We present a genetic-algorithm-based approach for estimating the maximum power dissipation and instantaneous current through supply lines for CMOS circuits. Our approach can handle large combinational and sequential circuits with arbitrary but known delays. To obtain accurate results we extract the timing and current information from transistor-level and general-delay gate-level simulation. Our experimental results show that the patterns generated by our approach produce on the average a lower bound on the maximum power which is 41% tighter than the one obtained by weighted random patterns for estimating the maximum power. Also, our lower bound for the maximum instantaneous current is 21% tighter as compared to the weighted random patterns.

Optical power generating system

Abstract: PROBLEM TO BE SOLVED: To provide an optical power generating system that can prevent decrease of power generating efficiency of the whole system. SOLUTION: An optical power generating system 100 comprises a plurality of solar battery modules 1a to 1n, and a plurality of power converters 2a to 2n respectively connected to the modules 1a to 1n and having maximum solar energy pursuing functions. The converters 2a to 2n are connected in series to one another. The modules 1a to 1n have their output current and output voltage controlled by the maximum solar energy pursuing functions of the converters 2a to 2n, so that the maximum power generating efficiency can be always obtained. Further, a common output current flows through the output terminals of the converters 2a to 2n, and the output voltages are automatically adjusted, so that the ratio of any two voltages becomes equal to the ratio of the maximum powers of the corresponding two of the modules 1a to 1n.

Transmission power control method

Abstract: A transmission power control method subdivides one or more transmission power steps as defined in a system specification into multiple sub-steps. A base station (290) instructs a mobile station (280) to use a defined power step, and the mobile station (280) initially selects a maximum power sub-step within the requested power step during an initial RACH (225) transmission. During the duration of the call, the mobile station (280) dynamically adjusts the power sub-step based on measured signal reception quality and channel conditions. The result is an improvement in call completion rates with only a minor reduction in battery life.

Piezoelectric Power Requirements for Active Vibration Control

Abstract: This paper presents a method for predicting the power consumption of piezoelectric actuators utilized for active vibration control. Analytical developments and experimental tests show that the maximum power required to control a structure using surface-bonded piezoelectric actuators is independent of the dynamics between the piezoelectric actuator and the host structure. The results demonstrate that for a perfectly-controlled system, the power consumption is a function of the quantity and type of piezoelectric actuators and the voltage and frequency of the control law output signal. Furthermore, as control effectiveness decreases, the power consumption of the piezoelectric actuators decreases. In addition, experimental results revealed a non-linear behavior in the material properties of piezoelectric actuators. The material non-linearity displayed a significant increase in capacitance with an increase in excitation voltage. Tests show that if the non-linearity of the capacitance was accounted for, a conservative estimate of the power can easily be determined.

System and method for solar cell generation

Abstract: (57) [Summary] [Problem] To provide a solar cell power generation system in which the maximum power amount of the entire power conversion system can be obtained by simply adding the maximum power generation amount of each unit solar cell module constituting a solar cell array. A maximum power tracking type power converter unit (20-1 to 20-n) is connected to each of the unit solar cell modules (101-1 to 101-n) constituting a solar cell array (100), and a control circuit unit (60) is connected. Is the switching power conversion circuit 3 At 0, the outputs of the respective maximum amounts of power obtained by controlling the output current are connected in series to obtain a high-efficiency output of the entire power conversion system.

Effects of scaling high frequency transformer parameters

Abstract: Design and optimization of high-frequency magnetic components usually involve a number of tradeoffs between performance functions This paper investigates the relationships between some of these factors by direct implementation of the thermal reference model previously presented by the authors This unique thermal model provided the foundation for a more flexible approach to design and optimization, forcing uninterrupted coherence between electromagnetic behavior and predefined thermal conditions Generic scaling of transformer parameters is performed herein, under simultaneous control of the temperature rise Relationships for performance functions, such as maximum power rating, power density, total losses, efficiency and leakage impedance are determined, tabulated and plotted as functions of several different scaling conditions

Modelling and optimal controllers design for a stand-alone photovoltaic-diesel generating unit

Abstract: This paper presents the dynamic modeling and optimal controllers design for a stand-alone photovoltaic-diesel generating unit. To limit the continual variation on load-bus voltage and frequency and to extract the maximum power from the photovoltaic generator, two optimal PI controllers are designed based on state and output feedback techniques. The dynamic behaviour of the closed-loop system following common disturbances such as load changes, insolation variation due to clouds and three phase short circuit is investigated. The simulation results show the capability of the closed-loop system for limiting the load-bus voltage and frequency variations within acceptable levels and extracting the maximum power from the PV generator under insolation variation can be realized.

Circuit configuration for supplying power to electronic tripping device

Abstract: A circuit configuration for supplying power to electronic tripping devices from a current-transforming device. A switched-mode power supply unit, in particular a choke/step-up transforming device having a pulse-width voltage control, is connected downstream of a charging capacitor. Once a set point of the output voltage at an output capacitor is reached, only a very high pulse duty factor is provided. Particularly, maximum power point control is provided during an initial charging phase. Circuit configurations of this kind serve the power supply of overvoltage tripping devices in low-voltage and medium-voltage systems.

Line powered modem

Abstract: A battery powered computer system includes an add-on device, such as a modem, with a power supply that uses power from a telephone line to provide power to the modem. In one embodiment the power supply is an adaptive power supply that uses power from both the telephone line and the battery of the computer system. The adaptive power supply determines the maximum power available from the telephone line and delivers that power to the modem. If the power from the telephone line is not sufficient for the modem, the adaptive power supply supplements the power with the power from the computer system. In one embodiment, the adaptive power supply uses power time division multiplexing to share the power from the telephone line and the computer system.

Maximum power point detecting circuit

Abstract: A maximum power point detecting circuit is disclosed including: a power detector for generating a power detecting signal responsive to an output voltage and an output current of a solar cell; a comparator for comparing a previous power average value with a current power average value according to the power detecting signal for a constant time; and a discriminator for latching an output signal of the comparing means immediately after a current constant time, setting an output immediately before a previous constant time, and judging that an output power of the solar cell decreases when the current power average value is smaller than the previous power average value to generate a discriminating signal.

Power consumption management system

Abstract: PROBLEM TO BE SOLVED: To obtain a power consumption management system which can rank the using states of various appliances by learning the states by issuing in order a stopping instruction to each appliance ranked by systems in accordance with the sum total value when the value exceeds an allowable maximum set value. SOLUTION: A power consumption management system compares the total sump value of the power consumption of each appliance with an allowable maximum power consumption value and when the total sum value exceeds the maximum power consumption value, displays it. Then the system compares the average information on the sum of each rank and each system held by means of a system-wise power consumption holding means 162 with the present total sum value of power consumption of each appliance from the appliance having the lowest priority in each rank and system and, when the present power consumption is higher than the average information, successively controls the power supply to the appliances by means of a control means 15 through a communicating means 102 so that the power supply may be reduced in accordance with the degree. When the total sum value of the power consumption exceeds the allowable maximum power consumption even when the power supply is controlled to all appliances from the appliance having the lowest priority to the appliance having the highest priority, the power consumption of the appliances is successively controlled by means of a power supply stopping means.

Rake receiver for direct diffusion cdma transmission system

Abstract: PROBLEM TO BE SOLVED: To provide a RAKE receiver which makes RAKE reception by selecting many signals having sufficient receiving power as much as possible by rejecting signals only containing noise, etc. SOLUTION: Diffusion-modulated signals in a base band are inputted to a matched filter 150 and reversely diffused by using the output of a diffused code replica generating section 151. The reversely diffused signals at L different timing are demodulated by means of a demodulating section 152. An average receiving power measuring section 153 measures the average receiving power at the L different timing. A minimum power detecting section 201 and a maximum power detecting section 203 detect the minimum signal power and maximum signal power at the L different timing. Two thresholds can be found by respectively multiplying the minimum and maximum signal power by constants GA and GB. A path selecting timing detecting section 205 detects the timing of a multipath having large signal power from the timing at which the average signal power is larger than the thresholds A and B. COPYRIGHT: (C)1998,JPO

Development of power assist system with individual compensation ratios for gravity and dynamic load

Abstract: This paper present the design concept of a power assist system. In such system, when the controller is designed without considering the maximum torque of the actuators, the actuators can sometimes become saturated, resulting in a loss of stability and manoeuvrability. We propose a method for dealing with this problem. The load force is divided into gravitational and dynamic component, and each component is attenuated by an individual ratio. These ratios are determined considering the maximum power of the operator and the actuators.

Some optimization criteria for biological systems in linear irreversible thermodynamics (

Abstract: Summary. — In the present work, some optimum working regimes for linear energy converters are analyzed from a thermodynamical point of view. The regimes studied are minimum entropy production, maximum power output and another one which represents a good compromise between high power output and low entropy production. The analysis is made within the domain of linear irreversible thermodynamics. Finally, the possibility that some biological systems satisfy these criteria is discussed. PACS 87.10 ‐ General, theoretical, and mathematical biophysics (including logic of biosystems, quantum biology, and relevant aspects of thermodyamics, information theory, cybernetics, and bionics).

COSMOS: a continuous optimization approach for maximum power estimation of CMOS circuits

Abstract: Maximum instantaneous power in VLSI circuits has a great impact on circuit's reliability and the design of power and ground lines. To synthesize highly reliable systems, accurate estimates of maximum power must be obtained in various design phases. Unfortunately, determining the input patterns to induce the maximum current (power) is essentially a combinatorial optimization problem. Even for circuits with small number of primary inputs (PI's), it is CPU time intensive to conduct exhaustive search in the input vector space. The only feasible way is to find good upper and lower bounds of the maximum power, and to make the gap between these two bounds as narrow as possible. In this paper, we present a continuous optimization approach to efficiently generate tight lower bounds of the maximum instantaneous power for CMOS circuits. In our approach, each primary input (PI) of the circuit is allowed to assume any real number between 0 and 1. Maximum power estimation for CMOS circuits is then transformed into a continuous optimization problem, in which a smooth function is maximized over a unit hypercube in the Euclidean space. The continuous problem can be solved efficiently to generate good lower bounds of the maximum power. Our experiments with ISCAS and MCNC benchmark circuits demonstrate the superiority of this approach. For all the circuits tested, the mean value of the ratio "CPU time of the continuous optimization approach divided by CPU time of the simulation-based technique" is equal to 0.41. For 60% of the circuits tested, our approach gives a better estimate (1.16 times larger, on an average) than the simulation-based technique does. Compared to the ATPG-based technique, the continuous optimization approach generates a tighter lower bound (1.19 times larger, on an average) of maximum power for 60% of all the circuits tested.

New bounds on the performance parameters of a thermoelectric generator

Abstract: The influence of three main irreversibilities existing in thermoelectric devices on the performance of a thermoelectric generator is investigated by means of nonequilibrium thermodynamics and finite-time thermodynamics. The efficiency and the power output of the thermoelectric generator are optimized. The maximum efficiency and the maximum power output are determined. The power output versus efficiency curves illustrate clearly that the two operating points corresponding to maximum efficiency and maximum power output approach one another as the thermal conductances between the thermoelectric device and its external heat reservoirs decrease. Finally, the optimal problem relative to the load matching involved in the design of a practical thermoelectric generator is discussed in detail.

Optimum Power Boosting of Gas Turbine Cycles With Compressor Inlet Air Refrigeration

Abstract: A conceptual gas turbine cycle with refrigerated air supplied to the compressor inlet is proposed to increase the cycle specific net power significantly and render it practically insensitive to seasonal temperature fluctuations. It is optimized for maximum power per m{sup 3}/s and maximum power per kg/s of induced air. These cycle performances are evaluated in a numerical example for two refrigeration cycle efficiencies, based on state-of-the-art isentropic efficiency coefficients of the compressor and turbine. The specific heats of air and products of combustion are treated as temperature-dependent parameters to be determined as integrated mean averages.