Programmable Solar Array Simulator

This paper discusses the operational and circuit features of a laboratory device built to simulate the dynamic electrical output characteristics of a solar array in orbital flight. Operational controls provide for adjustment of the static electrical characteristics so that solar arrays of various configurations and capacities can be simulated with a reasonably high degree of accuracy. The programming feature of the system extends the capability to cover simulation of the predictable changes in characteristics exhibited by a solar array in response to changes in environment. This includes the exponential temperature changes resulting from the solar array\´s passing in and out of the earth\´s shadow as well as the changes in illumination seen by the solar array as the satellite rotates on any chosen axis. The basic system consists of a special purpose analog computer capable of generating a reference voltage in response to electrical inputs simulating the present yalue of load current, temperature and illumination and an output unit which is essentially a DC amplifier that applies a proportional voltage across the load. In the prototype system, the output unit was sized to produce approximately 300 watts. In the programmer portion of the system, the electrical signal simulating temperature is generated in an R-C circuit having a time constant which matches the "heat up" thermal time constant of the actual array. Simulation of the pattern of illumination accompanying satellite rotation is accomplished by an optical cam system.