ВИЗНАЧЕННЯ УМОВ СТАБІЛЬНОЇ РОБОТИ ДВИГУНА ПОСТІЙНОГО СТРУМУ, ЩО ПІДКЛЮЧЕНИЙ БЕЗПОСЕРЕДНЬО ДО ФОТОЕЛЕКТРИЧНОГО МОДУЛЯ

Abstract

In this paper the operation of a parallel excitation DC motor, which operates on a load with a fan characteristic and is directly-coupled to a photovoltaic module is analyzed. The main goal of the study is to determine the parameters of the module, which ensure a stable operation of the motor under variable external conditions, in particular, the intensity of solar radiation. On the basis of a five-parameter model of a photovoltaic module, a stationary mathematical model of the module-motor-load system is built. This model describes the operating point of the motor, and takes into account the influence of external conditions: ambient temperature and intensity of solar radiation. Based on the constructed model, it is shown that the condition for stabilizing the operation of the motor is the presence of a power reserve of the photovoltaic module relative to the rated motor power, and this reserve should be obtained by increasing the module current. Accordingly, the priority is to increase the number of solar cells connected in parallel in the module. Increasing the power of the module by increasing the number of solar cells connected in series does not provide stabilization of the motor operation and leads to a variation in the operating point when external conditions change. The possibility of an abrupt change in the operating point is shown. Dimensionless criteria describing the operation of the engine have been determined. It is shown that the parameters of the photovoltaic module is strongly dependent on the ratio of the load torque at the rated motor speed to the rated starting torque. Criteria for determining the parameters of a photovoltaic module are proposed depending on the characteristics both of the load and of the motor, as well as the interval of external conditions, where stable operation of the system is expected. Keywords: photovoltaic module, DC motor, fan characteristic, parallel excitation, five-parameter model.