초록 ▼

A switching network for improving the conversion efficiency of a photovoltaic power supply comprises a variable coupling circuit for coupling an array of photovoltaic cells to a load resistance. The combined effective impedance of the network and load is varied to match the value required for maximu

A switching network for improving the conversion efficiency of a photovoltaic power supply comprises a variable coupling circuit for coupling an array of photovoltaic cells to a load resistance. The combined effective impedance of the network and load is varied to match the value required for maximum output power. A switching transistor (22) which connects the source module (20) to the load (30) is pulse-width modulated with a variable duty cycle determined by the control signal from the sensor circuit. A photovoltaic cell (32) similar to those comprising the photovoltaic power module (20) is used to track variations in the ambient light intensity. The open-circuit voltage of a sensor cell (32) is used to determine the proper value of duty cycle required for maximum power transfer. The output voltage of the module (20) is sampled and compared with the proper value to produce a control signal.

대표청구항 ▼

A control circuit for matching the electrical impedance of a photovoltaic power source and a load driven therefrom, comprising: voltage sensing means, comprising a photovoltaic cell, for providing a reference voltage indicative of a desired output voltage of said photovoltaic power source, circuit m

A control circuit for matching the electrical impedance of a photovoltaic power source and a load driven therefrom, comprising: voltage sensing means, comprising a photovoltaic cell, for providing a reference voltage indicative of a desired output voltage of said photovoltaic power source, circuit means for comparing the actual voltage of said photovoltaic power source and said reference voltage for producing a difference signal indicative of the difference, if any, between said reference voltage and said actual voltage of said photovoltaic power source, control means, connected to said circuit means, for producing a modulated control signal, the modulation of said control signal being indicative of said voltage difference, switching means for repetitively switching on and off the current flow from said photovoltaic power source to said load, said switching means being responsive to said control signal to vary the proportion of time that said current is switched on in relation to the proportion of time that said current is switched off so as to maintain the output voltage of said photovoltaic power source at a substantially constant level, whereby maximum power is transferred from said photovoltaic power source to said load, even when the solar radiation intensity received by, and ambient temperature of, said photovoltaic source vary.