Optimized load sharing control by means of thermal reliability management

With new applications for high-current low-output voltage power systems emerging nearly every day the need for new and cost-efficient power system designs is a matter of course. As output voltage levels continue to decrease an approach that seems more and more attractive is the implementation of distributed power configurations with point-of-load power conversion. This technique distributes a high voltage to all parts of the system, thus minimizing the voltage drops throughout the distribution network. However, this configuration only solves the problem of power losses in the distribution network while the problems of high-current low-output voltage conversion at the point-of-load remain a challenge. A common solution to the latter problem is the parallel-connection of multiple converter units. This technique is attractive for a number of reasons. The first and most obvious reason is that it provides the designer with a simple technique for reliability improvements as redundancy quite easily can be implemented. Another advantage of this particular technique is that it allows the designer to implement large power systems by means of off-the-shelf units, thus minimizing parameters such as design time and system cost. However, due to non-ideal parts each converter unit deviates from the ideal case, which makes a power system comprised of parallel-connected converters a rather poor performing system. To account for the non-ideal parts some form of load sharing is needed, whereby it is ensured that each converter in the configuration delivers its share of the total output power. In other words parallel-operation of multiple converters is employed when specifications require a highly reliable system, designable within a very short time frame and at low costs. However, to make full use of the system’s potential load sharing control is a must.