ELECTRICAL EQUIVALENCE PYRANOMETER WITH AMBIENT TEMPERATURE ANALOG COMPENSATION
Electrical Equivalence Pyranometer, Feedback Wheatstone Bridge, Constant Temperature Difference.
Pyranometers are devices used to measure incident radiation per unit area. This type of device is found in many applications in the field of solar energy, UV treatment, atmospheric research, etc. Some of these devices are based on the principle of electrical equivalence, in which radiant power is equated with electrical power in a thermoelectric balance. The balance of this balance usually occurs by compensating the radiant power by an electrical power to maintain a resistance thermometer at constant temperature. This configuration, however, has limitations when the ambient temperature varies, varying parameters such as sensitivity, useful output voltage, power consumption, among others. In this work, it is proposed to replace the configuration that keeps the sensor temperature constant for the configuration of constant temperature difference. The proposal is formulated by modifying the architecture of the feedback Wheatstone bridge so that it works with a constant temperature difference. The implemented
proposal is then validated through computer simulations in a SPICE environment and through field experiments. In this work, a prototype was developed that was tested in 3 different climatic conditions, namely: clear weather, partially cloudy weather and cloudy wheater. Results of this work point to an improvement in the useful voltage range by 5 times, a reduction in the influence of ambient temperature variation on the output voltage, a reduction in electrical consumption and an increase in the sensitivity to incident radiation.