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Showing papers on "Maximum power point tracking published in 1979"


Patent
23 Jul 1979
TL;DR: In this paper, a method for controlling a force-commutated inverter coupled between an electrochemical cell and a power grid for adjusting the magnitude and direction of the electrical energy flowing there between is presented.
Abstract: A method for controlling a force-commutated inverter coupled between an electrochemical cell and a power grid for adjusting the magnitude and direction of the electrical energy flowing therebetween. Both the real power component and the reactive power component of AC electrical energy flow can be independently varied through the switching waveform presented to the intermediately coupled inverter. A var error signal is derived from a comparison of a var command signal with a signal proportional to the actual reactive power circulating between the inverter and the power grid. This signal is presented to a voltage controller which essentially varies only the effective magnitude of the fundamental voltage waveform out of the inverter, thereby leaving the real power component substantially unaffected. In a similar manner, a power error signal is derived by a comparison of a power command signal with a signal proportional to the actual real power flowing between the electrochemical cell and the power grid. This signal is presented to a phase controller which varies only the phase of the fundamental component of the voltage waveform out of the inverter relative to that of the power grid and changes only the real power in proportion thereto, thus leaving the reactive power component substantially unaffected.

50 citations


Patent
26 Nov 1979
TL;DR: In this article, a series switch between the panel and inverter is activated into a conducting state in response to the panel voltage exceeding a predetermined value, provided by connecting a dummy power dissipating load in shunt with the panel while the series switch is cut off.
Abstract: Orderly control of power applied by a photovoltaic solar panel d.c. source to a load is attained despite varying long and short term solar conditions by coupling power from the panel to an inverter in response to the panel voltage exceeding a predetermined level and preventing coupling of power from the panel to the inverter in response to the panel voltage being less than a predetermined level. The switching frequency of the inverter is controlled in response to the panel voltage so that approximately maximum power which the panel is capable of generating is supplied to the inverter for the incident solar energy on the panel at a given temperature. Power is supplied to the inverter by a series switch between the panel and inverter. The switch is activated into a conducting state in response to the panel voltage exceeding a predetermined value. The panel voltage controls the turn-on and turn-off levels of the series switch by a hysteresis effect, provided by connecting a dummy power dissipating load in shunt with the panel while the series switch is cut off. The dummy load has a value causing the panel output voltage to be less than the voltage for maximum panel output power. A similar series switch and hysteresis control is provided for control circuitry for the inverter. The series switch for supplying power to the control circuitry can be activated in response to the same voltage which activates the series switch for the inverter, or in response to a different voltage level.

32 citations


Proceedings ArticleDOI
18 Jun 1979
TL;DR: In this paper, a new peak power tracking method for photovoltaic arrays is presented, which utilizes ripple inherent in the system to determine the correct operating point for maximum power from the array.
Abstract: A new method of peak power tracking for photovoltaic arrays is presented. The method utilizes ripple inherent in the system to determine the correct operating point for maximum power from tha array. Peak power tracking is important for efficient operation of photovoltaic power systems. Operation of a microprocessor controlled 50KVA power conditioning unit utilizing the new peak power tracking method is described. The unit features automatic start up and parallel operation with the utility grid.

16 citations



Patent
01 Feb 1979
TL;DR: Inverter power supply control circuitry that protects power supply components from relatively quick-changing overcurrent conditions and that provides regulation of the power supply's output current upon relatively slow-changing load conditions as mentioned in this paper.
Abstract: Inverter power supply control circuitry that protects power supply components from relatively quick-changing over-current conditions and that provides regulation of the power supply's output current upon relatively slow-changing load conditions.

7 citations


Journal ArticleDOI
A.S. Barker1, H.J. Power
TL;DR: In this paper, the performance of a silicon cell non-tracking photovoltaic array has been studied over a three year period, where the array provided power in parallel with commercial utility power in a shared mode which makes use of all the solar energy generated.

7 citations



ReportDOI
30 Apr 1979
TL;DR: In this article, a classification system for stand-alone and utility-interactive dc-to-ac inverters used in photovoltaic systems in the 1 to 100kVA power range is presented.
Abstract: A classification system is presented for stand-alone and utility-interactive dc-to-ac inverters used in photovoltaic systems in the 1-to-100-kVA power range. Additional inverter topologies, noted during the classification process, are introduced. To provide background, generally used dc-to-ac inversion technology is reviewed. Relative merits and liabilities of available power devices are discussed and device protective techniques are reviewed. Maximum power point tracking can enhance system value in utility-interactive no-battery photovoltaic power systems. This general theory is reviewed and an improved implementation is described.

2 citations


01 Aug 1979
TL;DR: In this article, an efficient power-conditioning circuit designed to utilize maximum power available from solar cell array, controls output of array so that excess energy not needed by load is diverted to charge batteries for reserve power when sufficient sunlight is not available.
Abstract: Efficient power-conditioning circuit designed to utilize maximum power available from solar cell array, controls output of array so that excess energy not needed by load is diverted to charge batteries for reserve power when sufficient sunlight is not available.

1 citations


01 Jan 1979
TL;DR: A photovoltaic solar energy system has been providing power for irrigation and crop drying at an agricultural field station of the University of Nebraska The system, developed and maintained jointly by MIT/Lincoln Laboratory and the University and under contract to the US Department of Energy, consists of a 25 kWp PV array, a battery subsystem, an inverter, a controller, and a data collection and management system Field data indicate that the PV array performs up to expectations if allowance is made for degradation.
Abstract: A photovoltaic solar energy system has been providing power for irrigation and crop drying at an agricultural field station of the University of Nebraska The system, developed and maintained jointly by MIT/Lincoln Laboratory and the University and under contract to the US Department of Energy, consists of a 25 kWp PV array, a battery subsystem, an inverter, a controller, and a data collection and management system Field data indicate that the PV array performs up to expectations if allowance is made for degradation The array operates at an efficiency (based on cell area) of between 7 and 8%; the battery subsystem at an in-out efficiency of 83%, and the inverter at 87% During the irrigation season the system delivers 70% of the energy provided by the PV array to the pump motor Approximately 10% of the array energy is wasted when the battery is in a fully charged state and the array power exceeds the load Performance of the system was compared with the results of a computer simulation This comparison showed agreement to within +- 5% on daily energy totals for array output, inverter input, battery input and output

1 citations


Proceedings ArticleDOI
01 Nov 1979
TL;DR: In this article, an uninterruptible power supply (UPS) system using a current source inverter is proposed, where the load commutation is achieved by selecting the output filter to maintain a net leading power factor at the inverter output over the operating load range.
Abstract: In this paper, an uninterruptible power supply (UPS) system using a current source inverter is proposed. A single phase and a three phase load commutated current source inverter suitable for this UPS system is presented. The load commutation is achieved by selecting the output filter to maintain a net leading power factor at the inverter output over the operating load range. A steady state analysis of the inverter power circuits is given. The analysis is based on using the harmonic series of the inverter output current to obtain the circuit voltages and currents. The theoretical results presented in this paper are verified on experimental models for both the single phase and the three phase inverters.