Showing papers on "Maximum power principle published in 1984"

A quantum mechanical open system as a model of a heat engine

Abstract: A quantum model of a heat engine is analyzed This engine is constructed from two coupled oscillators in interaction with a warm and cold reservoir Power is extracted by an external periodic driving force As a function of control parameters a maximum in power is obtained, and a decline of thermodynamic efficiency below the ideal Carnot value This irreversibility is a consequence of the mechanism devised to extract power in its perturbing the energy level structure of the engine In the limit of weak coupling to the driving force the efficiency at maximum power obtains the value of η=1−((Ta/Tb))1/2

Maximum-power points of solar cells with simultaneous series and shunt losses

Abstract: Maximum-power-point computation for solar cells when both series and shunt resistance losses are present simultaneously has been lacking in the past. This paper presents a new and simple method to achieve this task. Hence we become able to incorporate both series resistance R s and shunt resistance R sh, analytically in maximum-power analysis. The method is illustrated by a numerical example. The important solar cell parameters, i.e. open-circuit voltage V oc, short-circuit current I sc , maximum-power coordinates (I mp , V mp ) and maximum power P mp, fill factor FF and efficiency η have been obtained for the general lossy-cell case.

Method for controlling alternative energy sources for maximum power and an arrangement for carrying out the method

Abstract: The application deals with a method for automatically controlling the power emitted by an energy generating system to the highest possible value (MPP control). So that fluctuations in the power output, caused by changing environmental conditions, and thus effects on connected loads, are largely avoided, an adaptor between the generating system and the load is controlled in such a manner that the power in each case emitted at the highest and at the lowest voltage value is determined from current and voltage fluctuations and stored. From the stored values, a difference is continuously formed, the amount and polarity of which specifies the magnitude and the direction of the instantaneous operating point from the maximum power point. From this, a signal for the reference value for the adaptor is formed at the same time.

Maximum Power Spectroscopy for Photovoltaic Devices

Abstract: Maximum power spectroscopy for the study of photovoltaics is described. The technique is based on analyzing the modulated maximum power output of the photojunction cell for a controlled input spectrum in a dual beam (bias plus modulated monochromatic probe) arrangement. The differential power conversion efficiency is thus measured. The input spectrum is programmed by a computer and servo loop to be either neutral (wavelength independent) or solar in shape, from a stored reference table. The operation of the system, applicable to laboratory spectrum simulation, and the function of the bias beam are demonstrated. Spectra of a p-n Si diode with added series resistance simulate the differences between maximum power efficiency and the conventional short-circuit quantum efficiency. There are advantages to the power measurement in sensitivity to competitive kinetic processes governing cell conversion efficiency and to wavelength dependent effects on junction potential gradients.

Maximum power transfer in non‐linear source‐load systems

Abstract: This paper is concerned with the conceptual design and realization of matching networks for the continuous transfer of maximum power from a non-linear source with randomly varying characteristics to a load. Such sources are commonly encountered in the use of photovoltaic arrays or wind energy conversion systems for the production of electric power. Experimental studies as well as computer simulation results verify the validity of the design and point to methods for its practical implementation.

Power carrying capacity reduction in straight regular waveguide containing foreign conducting bodies

Abstract: The theoretical maximum power that can be transmitted through a waveguide dependsupon the maximum electric field strength of the propagating mode. Voltage gradients aremost likely to be higher if there are discontinuities such as ridge, post or foreign conductingboss. Therefore the maximum power that a waveguide will safely carry is usually a fractionof the theoretical maximum. We give the reduction factor in the power carrying capacity ofa waveguide containing continuities in the form of the ratio of (E_0/E_5)~2 for various cases ofdiscontinuities.

Maximum power control circuit for a solar converter

Abstract: Abstrac As one of the possible applications of Photovoltaic Solar Energy, the Electronic Engineering Department of the Industrial Engineering College of Madrid has developed an equipment which, in its prototype stage, has allowed a study to be made of the possibilities of connecting photovoltaic arrays to the electric power mains through a suitable high-power circuit. An additional objective was that the interfacing unit should have the fewest elements possible with a view to optimizing the overall efficiency of the installation.

Power source in magnetic levitation type vehicle

Abstract: PURPOSE:To obtain an efficient power source by controlling a power converter to gain the maximum power from an induction coil provided in a vehicle. CONSTITUTION:An indiction coil 1 of a power source for a vehicle is arranged in addition to a propulsion coil on the vehicle in response to the propulsion coil on the ground, and the output terminal of the coil 1 is connected through a power converter 20 to a storage battery 30. A control circuit 60 obtains a reference value to attain the maximum current from the first detection signal S1 relating to the speed, frequency or induced voltage from a transformer 40, and forms a control signal 100 for controlling the converter 20 so that the second detection signal S2 as to the current applied to the converter 20 from the current detection current transformer 50 reaches the above reference value. In this manner, the efficient power source can be obtained.

A new control method for ac drives with inverter-fed synchronous machines supplied from a battery

Abstract: A new control method for a.c. drives with synchronous machines is investigated. The machine is fed via a current-source machine-commutated inverter from a battery. Applying this control method, the drive is controlled by means of the inverter only. The battery-side converter, where usually a chopper is used, can be bridged or can be omitted. This control method can be used for operation in the constant power or field weakening range of the drive. The stationary performance of the drive is analyzed by means of the equations of a very simplified model. For an exact investigation measurements from a 20 kW drive, developed for a battery powered electric vehicle, and a detailed simulation are used. A good stationary performance can be recognized. The maximum power and the maximum applyable frequency are determined. The influence of several important drive and control parameters is shown. The advantage of this control method is an increased efficiency of the drive, as there are no losses of the battery-side converter.