Efficiency enhancement of high-power interleaved DC-DC converter by using an improved phase shedding control with phase equivalent resistance.

DC-DC converters generally maintain poor efficiency when operating at light to medium loads. This is primarily due to the fact that switching losses outweigh conduction losses significantly, while core losses remain constant regardless of the load conditions. In the case of the interleaved boost converter (IBC), this efficiency deterioration increases more than the conventional boost converter (CBC), when the number of phases increases. Therefore, an efficiency improvement is necessary for IBC under light load to medium load conditions. This paper proposed an enhanced phase-shedding control algorithm using phase equivalent resistance estimation for a 3-ϕ IBC, aiming to improve efficiency across all load conditions by incorporating automatic phase selection. Also, in the case of phase number selection, the required unknown parameter value i.e. phase equivalent resistance has been measured online in order to improve phase shedding performance. In addition, this algorithm is implemented by including the auto change inner loop-average current mode control (ACIL-ACMC) to maintain equal current sharing among the phases and voltage regulation during load variation as well as phase switching. The overall phase shedding control has been developed in the DSP (TMS320F28335) for the designed 7.5kW IBC.

Fixed structure compensator design using a constrained hybrid evolutionary optimization approach.

This paper presents an efficient technique for designing a fixed order compensator for compensating current mode control architecture of DC-DC converters. The compensator design is formulated as an optimization problem, which seeks to attain a set of frequency domain specifications. The highly nonlinear nature of the optimization problem demands the use of an initial parameterization independent global search technique. In this regard, the optimization problem is solved using a hybrid evolutionary optimization approach, because of its simple structure, faster execution time and greater probability in achieving the global solution. The proposed algorithm involves the combination of a population search based optimization approach i.e. Particle Swarm Optimization (PSO) and local search based method. The op-amp dynamics have been incorporated during the design process. Considering the limitations of fixed structure compensator in achieving loop bandwidth higher than a certain threshold, the proposed approach also determines the op-amp bandwidth, which would be able to achieve the same. The effectiveness of the proposed approach in meeting the desired frequency domain specifications is experimentally tested on a peak current mode control dc-dc buck converter.