Constant resistance control of solar array regulator using average current mode control

Abstract

In this paper, a single current control loop to perform the MPPT and battery charging control as well as the current sharing control for the parallel connected SAR is presented. It transforms the effective load characteristic of the SAR seen by the SA from the constant power load into the constant resistance load. Thus, the system becomes large-signally stable for the entire operation region of the SA. The proposed method is simple and flexible since it is not affected by the characteristic of the SAR. Although it uses the nonlinear control to transform the effective load characteristic of SAR, it can be easily implemented using digital controller, which may be already available for the MPPT controller without additional circuits. For the design and the stability analysis of the proposed method, the small signal analysis is performed and the Z.O.H effect is analyzed. The experimental results from a 180W prototype hardware show that the proposed control scheme has a simple implementation structure and can stabilize the system in the entire region of SA.