Showing papers on "Maximum power point tracking published in 1984"

Power conversion device for solar cell

Abstract: A power conversion device of simple configuration for a solar cell which permits the solar cell to be connected to the commercial power source and enables the maximum electric power corresponding to the amount of incident sunlight to be drawn from the solar cell. A power conversion device for a solar cell of this invention comprises a voltage controlled oscillator capable of generating oscillation with a frequency which is the function of the dc output voltage of said solar cell, an inverter controlled based on the output frequency of said voltage controlled oscillator to receive the dc output current of said solar cell and convert said dc output current into an alternating current, and an inductor serving to connect the ac output from said inverter to a commercial power source.

New Solar Cell Power Supply System Using a Boost Type Bidirectinal DC-DC Converter

Abstract: A new solar cell power supply system is presented, in which the boost type bidirectional dc-dc converter and the simple control circuit with a small monitor solar cell are employed to track the maximum power point of the solar array. It is confirmed by the experiment that the new system has sufficiently precise tracking operation performance and satisfactorily high power efficiency. Also, a comparison of the power efficiencies is made theoretically, as well as experimentally, on the new and the conventional solar cell power supply systems. As a result, it is revealed that the new system is superior to the conventional one in the power efficiency.

Uninterruptible power supply and line conditioner

Abstract: Conventional uninterruptible power supplies require different power conversion stages and other systems, during normal "break even" operation, have minimum inverter currents under zero load conditions. An uninterruptable power supply and line conditioner uses a local battery (40) and the utility power lines (96, 98) as the sources of power for an AC load, and in which a pulse width modulation (PWM) inverter (46) is used to convert the battery DC to the load AC and to charge the battery from the power lines. The utility power lines (96, 98) are effectively connected to the load by way of a series inductance (78), and the phase angle between the inverter (46) output voltage and the effective input voltage to the inductance (78) from the power lines controls the proportioning of current to the load and to the battery (40) from the power lines, and from the inverter to the load. The necessary inverter current is reduced and the throughput efficiency improved by, in effect, providing a predetermined ratio R between the voltage applied to the input side of the inductor and the voltage at the inverter output; in a preferred embodiment the effective input voltage is about 1.1 times the inverter voltage, and is produced by use of magnetic shunts (114, 116) in a transformer (78) which couples the utility line to the load.

An Improved Three-Phase Multistepped-Voltage Inverter Combined with a Single-Phase Inverter Through Switching Devices

Abstract: A new multistepped-voltage waveform inverter with a total harmonic distortion (THD) of 6.25 percent is described. The proposed system consists of a three-phase inverter whose conduction intervgl is smaller than 180 °, a triple-frequency single-phase inverter, and power semiconductor switches that link the two inverters. The advantages of the proposed system over conventional stepped-voltage inverters are that it requires only a small number of switching devices, no three-phase output transformers, and an output filter of reduced size. The relation between THD and the number of steps of an output voltage waveform is discussed. Comparison with other stepped voltage inverters and experimental results using power transistors are also presented.

Controller of solar power generating system

Abstract: PURPOSE:To ensure the stable supply of electric power to a system by using a command device consisting of a mode selection switch, a memory circuit, etc. and carrying out the charge/discharge control and the night charging control of a storage battery based on the output of said command device. CONSTITUTION:A command device 21 consists of a mode selection switch for selection of modes of sunshine variation, a memory circuit which stores both upper and lower limit power commands for supply to a system as well as a command for final holding power amount, etc. A voltage setter 8 sets the voltage of an optimum working point, and a voltage control circuit 9 controls the ignition phase of an inverter 5 so that the output voltage of a solar battery 1 is equal to said voltage at an optimum working point and then controls the electric power to be supplied to a system 6. In this case, the output of the inverter 5 is controlled by the lower and upper power commands delivered from the device 21. This secures the stable supply of power. Furthermore the night charging is also controlled by a command for final holding power amount given from the device 21. In such a way, the stable supply of power is secured to the system 6 by means of the device 21.

On the Automatic Interconnection between Solar Cell and AC Power Source

Abstract: A novel method of interconnection between solar cell and ac commercial line is presented. A transistor core multivibrator and an inductor play a key role in this system. The principle is based on the output characteristics of the solar cell and the voltage-frequency characteristics of the multi-vibrator. The power is always transfered from the solar cell to the load and the ac line.

Inverter control system

Abstract: An inverter control system for selectively operating on one of an inverter and backup power source to supply a load current comprises a PLL circuit which includes an integrating amplifier and is operative to synchronize the inverter operation with the voltage of the backup power source. When the power supply to the load is switched from the backup power source to the inverter, a.c. switches for the switching operation are controlled so that both the backup power source and inverter are active simultaneously for a certain period, and during the parallel operation the integrating amplifier is supplied with a reference signal which operates on the inverter to increase its shared load current.

Current type converter utilizing self-extinguishing element

Abstract: PURPOSE: To continuously operate an inverter even when an AC power source is interrupted by providing power interruption time DC power supply means for supplying and circulating power from a battery to the inverter when the AC power source interruption is detected. CONSTITUTION: A battery 11 is connected through a contactor 11 in the intermediate between a converter 3 and an input terminal capacitor 2, and an AC power source 1 is connected through a contactor 9. An inverter 51 of a load 5 is connected through a DC reactor 4 with the output of the converter 3, which is controlled by a circuit 8 which has a power interruption detector 6 and a controller 7. The battery 11 is connected with the converter 3 at the power interruption time to control the converter 3, thereby continuously operating the inverter 51. COPYRIGHT: (C)1986,JPO&Japio

Tremiti Desalination Plant

Abstract: The Tremiti project will assure the drinkable water supply to the Island of S. Nicola in the Adriatic Sea. The system is a stand-alone plant for sea water desalination using the reverse osmosis process, energized by a photovoltaic power plant. A p.v. array will give a 65 kWp nominal peak power. MPPT/MBC converter will feed the main d.c. bus and the storage battery which assures the uninterrupted operation of the desalination plant during overcast periods. The total plant area is 4500 sq.m; 1800 of them covered by the p.v. field: the layout of the rows of modules has been designed to optimize the efficiency of the array subsystem, to minimize atmospheric overvoltage, and to assure easy operation and maintenance. Good fitting with the natural characteristics of land is obtained. The final solution of the supporting structure satisfies to the last Italian codes for seimic areas: pv modules are bolted to galvanized steel beams supported by walls of prefabricated vibrated concrete blocks. The electric appliance load will consist in a.c. induction motors driven by single inverters. The R.O. plant will produce about 5000 cu.m. of water with an average power requirement of 13 kWh/cu.m. A power flow supervisory system will optimize, in every possible operating condition and system status, the utilization of available energy. A data acquisition system will monitor continuously the system and record the relevant parameters.

The utility interface - Can state-of-the-art power conditioners alleviate our concerns

Abstract: A key issue in adding significant amounts of photovoltaic (PV) generated electricity to the US electric grid is the PV/utility interface This paper puts into perspective the four most commonly discussed interface issues: harmonic content of the PV system output, power factor at which the system operates, voltage flicker potential attributed to cloud movement over the PV arrays and automatic disconnection of the PV system during a utility outage For each of these topics, a brief discussion of the concerns will be followed by relevant results of recent research The role that power conditioning plays in the interface and the direction of on-going research will be delineated

An inexpensive ($34.69) photovoltaic pseudo maximum-power-point tracker

Abstract: Presentation de la mise en œuvre d'un convertisseur de tension continu-continu simple et peu couteux obligeant un panneau de cellules solaires a fonctionner a sa tension maximale. Presentation des conditions necessaires et suffisantes pour un fonctionnement stable de ce convertisseur

A Solar Photovoltaic Array Power Conditioner with New Instantaneous Current Control Strategy

Abstract: A sinusoidal PWM type inverter using Gate-Turn-Off Thyristors and featuring a new instantaneous current control strategy is described. Its utilization as an interface for a utility-grid connected photovoltaic generator with maximum power tracking capability is explained, and computer simulated along with experimental waveforms are discussed. Its simple hardware circuitry and excellent characteristics make it suitable for a wide variety of applications, including AC motor drives.