Novel system for generating constant mechanical power from solar energy

Abstract

In order to make use of solar energy instead of oil and coal, the authors have proposed a new driving system which is composed of two coupled induction machines with a photovoltaic array. One induction machine is driven by electric power of the photovoltaic array through a general-purpose inverter, and the other induction machine is interconnected to the utility line. This system can generate the required mechanical power even in fluctuating insolation and supply the surplus electric power of the photovoltaic array to the utility line. In this paper, it is shown that the proposed method can be realized by using not only an induction–induction machine system but also an induction–synchronous one. The latter system can drive a mechanical load with a strictly constant speed and high efficiency. Such parallel running using two rotary machines has the advantage of decreasing the total loss compared to a single motor system when the no-load loss is less than a certain ratio of the load loss. Furthermore, this paper presents a practical method to measure the solar power, track the maximum power point, and control the connection–disconnection of the photovoltaic array to the general-purpose inverter. © 1999 Scripta Technica, Electr Eng Jpn, 130(2): 32–39, 2000