Showing papers on "Maximum power point tracking published in 1978"

Inverter circuit for energizing and dimming gas discharge lamps

Abstract: An illumination control system for gas discharge lamps which can be dimmed is provided in which a central inverter produces a sinusoidal output voltage at about 23 kHz. The amplitude of the inverter output is adjustable to dim the lamps. A transmission line consisting of spaced wires having respective thick insulation sheaths distributes the high frequency power to remotely located assemblies of ballasts and lamps. The ballasts consist of passive linear components. A high power factor rectifier network is disclosed for providing a d-c input to the inverter from the 50/60 Hz mains. The inverter circuit is provided with novel controls for gradual start-up and turn-off and is protected against load fault currents and internal fault currents. Automatic and manual resets are provided for internal fault current and load fault current, respectively. The basic inverter circuit consists of two alternately conducting controllably conductive power switching devices. Each is in parallel with a respective oppositely poled diode. The input d-c power line is connected in series with the series-connected power switching devices. A single series tuned circuit is connected in series with an output circuit element and is connected across one of the power switching devices. The amplitude of the inverter output is controlled by adjusting the phase at which the power switching devices turn on. In another embodiment, a single power switching device is used for the inverter circuit.

High efficiency wind power machine

Abstract: A high efficiency wind power machine is disclosed which is particularly well suited for large-scale, commercial conversion of wind power into electrical energy. The wind power machine of the present invention employs highly efficient wind-to-electric power conversion modules which may be interconnected to form a large-scale power converter. The individual modules employs flip-flop wind blades which travel in an oval path and are carried by traveling chains. The blades interact with the impinging wind stream at two points, thus increasing the overall efficiency of the conversion modules.

An inverter/controller subsystem optimized for photovoltaic applications

Abstract: Conversion of solar array dc power to ac power stimulated the specification, design, and simulation testing of an inverter/controller subsystem tailored to the photovoltaic power source characteristics. Optimization of the inverter/controller design is discussed as part of an overall photovoltaic power system designed for maximum energy extraction from the solar array. The special design requirements for the inverter/ controller include: a power system controller (PSC) to control continuously the solar array operating point at the maximum power level based on variable solar insolation and cell temperatures; and an inverter designed for high efficiency at rated load and low losses at light loadings to conserve energy.

Closed loop solar array-ion thruster system with power control circuitry

Abstract: A solar array-ion thruster system including a power control circuit which provides for use of the thruster itself in operating the solar array at the maximum power point. The power control circuit is connected between the solar array and the ion thruster and receives voltage and current signals from the former. The control circuit multiplies the voltage and current signals together to produce a power signal which is differentiated with respect to time. The differentiator output is detected by a zero crossing detector and, after suitable shaping, the detector output is phase compared with a clock in a phase demodulator. An integrator receives no output from the phase demodulator when the operating point is at the maximum power point but is driven toward the maximum power point for non-optimum operation. A ramp generator provides minor variations in the beam current reference signal produced by the integrator in order to obtain the first derivative of power.

Improvement of the Transient Stability by Optimal Switching Control of Parallel AC-DC Power Systems

Abstract: This paper is a contribution to the improvement of transient stability of parallel ac-dc power systems by use of the optimal switching control.

Advanced Photovoltaic Synchronous-Orbit Spacecraft Power Systems

Abstract: The state-of-the-art of photovoltaic power systems, for use in synchronous-orbit spacecraft, is characterized, including solar array, battery, and power control component performance. Advanced developments in each of these areas are reviewed, and performance improvement projections are made for the 1980-1990 time period. It is estimated that photovoltaic power system specific weight could improve from a present value of 126 kg/kW to approximately 43 kg/kW in 1985. These performance predictions are compared to nuclear system performance projections over the same period. The analysis indicates that advanced photovoltaic power systems will exhibit specific weights lower than isotope and nuclear reactor systems for power levels up to approximately 25 kW. At higher power levels, batteries with higher energy density would be required to compete with the projected performance of advanced nuclear systems. N this paper, we review state-of-the-art performance characteristics of synchronous-orbit power system components, discuss technology advancements, extrapolate overall system performance into the 1980-1990 time period, and finally, make alternative power system comparisons. Power subsystem performance improvement areas include solar array power density, battery energy density, and power control electronics power density. These components typically comprise 15-20% of total spacecraft weight. Increased spacecraft payload weight allocation and total system capability improvement will result from power system weight reduction.

High efficiency low cost solar cell power

Abstract: A concept for generating high-efficiency, low-cost, solar-cell power is outlined with reference to solar cell parameters, optical concentrators, and thermal control procedures A design for a 125-kw power module for space operation is discussed noting the optical system, spectrum splitter, light conversion system, cell cooling, power conditioner, and tracking mechanism It is found that for an unconcentrated array, efficiency approaches 60% when ten or more bandgaps are used For a 12-band system, a computer program distributed bandgaps for maximum efficiency and equal cell currents Rigid materials and thin films have been proposed for optical components and prisms, gratings, and dichroic mirrors have been recommended for spectrum splitting Various radiator concepts are noted including that of Weatherston and Smith (1960) and Hedgepeth and Knapp (1978) The concept may be suitable for the Solar Power Satellite

Photovoltaic power system tests on an 8-kilowatt single-phase line-commutated inverter

Abstract: Efficiency and power factor were measured as functions of solar array voltage and current. The effects of input shunt capacitance and series inductance were determined. Tests were conducted from 15 to 75 percent of the 8 kW rated inverter input power. Measured efficiencies ranged from 76 percent to 88 percent at about 50 percent of rated inverter input power. Power factor ranged from 36 percent to 72 percent.