The Available Matching of Solar Arrays to DC Motors Having Both Constant and Series-Excited Field Components

This paper presents a procedure for increasing the daily output mechanical energy supplied by dc motors directly connected to solar cell arrays (SCA). The technique is based on the use of dc motors with two components of magnetic field: a constant component that can be provided by a permanent magnet (or a separately excited winding) and a second one produced by a series field winding. Through properly selecting the parameters of the motor's magnetic circuit (i.e., the value of the constant field and the mutual inductance as well as their relative directions), an improved matching between the photovoltaic (PV) array and the dc motor can be achieved. Based on assessing and minimizing an expression used to quantify the power mismatch between the SCA and the dc motor, the optimal parameters are identified. A comparison is then made between this suggested motor design and both the separately excited and series motors.