Single-Source Multi-Battery Solar Charger: Analysis and Stability Issues

Energies

Alon Kuperman¹  Moshe Sitbon¹  Shlomo Gadelovits¹  Moshe Averbukh¹  Teuvo Suntio² 

[1] Department of Electrical Engineering and Electronics, Ariel University, Ariel 40700, Israel; E-Mails:;Department of Electrical Engineering, Tampere University of Technology, Tampere FI-33101, Finland; E-Mail:

关键词: battery charging;    photovoltaic converters;    small-signal modeling;    input voltage control;    stability assessment;   

DOI  :  10.3390/en8076427

来源: mdpi

【 摘 要 】

In this paper, dynamic analysis of a multi-battery dual mode charger, powered by a single solar array and suitable for lead-acid and lithium-ion cell-based batteries is presented. Each battery is interfaced to the solar array by means of a current-controlled buck power stage, operating either in constant power or constant voltage mode. Operation in former/latter charging mode implies regulating input/output voltage of the converter, which is a non-trivial situation since while feeding different batteries, all the converters share the same input terminals, connected to the solar array. It is revealed that when at least one of the batteries operates in constant power charging mode, open-loop instability occurs whenever converter input voltage is lower than maximum power point voltage of the solar array. Consequently, input voltage regulating controller must be designed to stabilize closed-loop dynamics for the worst case of instability, which is also derived. Moreover, it is shown that the dynamics of the converters operating under output voltage control are perceived as disturbances by input voltage control loop and must be properly rejected. Simple loop shaping design is proposed based on a PI controller, allowing stabilizing the system in case of worst case instability and rejecting output voltage control induced disturbances at the expense of non-constant, operating-point dependent closed-loop damping.

【 授权许可】

CC BY   
© 2015 by the authors; licensee MDPI, Basel, Switzerland.