An adaptive current-sharing control technology for multi power module with hot swapping

This paper achieves an adaptive current-sharing control strategy for multi power modules to solve the output current imbalance problem even caused by hot swapping while some power modules are paralleled or removed to provide higher or lower power the load requires. The conventional hot swapping techniques used in multi power module are easy to perform flexibility and precision, but generally easy to result in both the output voltage and current imbalances of operating modules so that some paralleled modules will be overloaded to mistake the operation even damage. Therefore, one of the solutions to balance the each module voltage and current while hot swapping uses the current control IC in each modules, but it increases complexity, cost and volume of each power circuit as well as degrades the efficiency under tiny-load and no-load situations. This paper provides a simple and low-cost adaptive current-sharing control method using o®-the-shelf PWM control IC which only needs to be simply and easily modified. This paper discusses and illustrates the issues caused by hot swapping, the current-sharing control theory, and the proposed control scheme to easily implement the required control function. A multi power supply comprised of two power modules is implemented for verification of the proposed control in which one module has the design specification including 20V output voltage, 5A maximum output current, and 100W maximum output power, the other has 20V output voltage, 2.5A maximum output current, and 50W maximum power. The total multi power module has 7.5A maximum output current and 150W maximum output power. The experimental results verify the theoretic analysis and feasibility of the proposed control method, and show the required proportional current-sharing function with actually-measured waveforms.