Symmetric current balancing circuit for multiple DC loads

Abstract

One of the key challenges in driving multiple parallel loads using a single circuit is to ensure that each load share the same current. Current imbalance occurs because these loads have varying individual characteristics, which surface due to inevitable deviations in mass production. Lighting is one representative application where multiple lamps such as LED (light-emitting diode) arrays need some sort of current balancing mechanism. While resistive balancing technique can be highly inefficient, current balancing using dedicated control IC for each channel significantly increases the cost and circuit complexity. In this paper, a novel current balancing circuit for multiple DC loads is proposed. A smart combination of an inherent symmetry of circuit and capacitive balancing mechanism enables an efficient and cost-effective current balancing. The operating principle of the proposed balancing method is analyzed in detail and an appealing generalization is made. The feasibility of the proposed balancing scheme is verified by developing a hardware prototype to drive a 100 W system, having six LED arrays.