Controllability of DC-DC converters with constant power-load
DC-DC变换器在恒功率负载下的能控性

The DC-DC converter with a constant power-load is a switched nonlinear system. We study the Boost converter by building its switched-system-model in three operation modes. Mode I, II and III are the circuit topology in the switch-on mode, the switch-off mode, and the discontinuous current mode, respectively. Because the capacitor voltage can not be negative, we modify the latest results of the planar topology to obtain for the half-planar affine nonlinear systems the necessary and sufficient conditions of global controllability: criterion function changes its sign over any nonzero control curve. We thus find that Mode II is globally controllable. Since Mode II is an inevitable period in the operation, thus the switched system is controllable. This methodology can be extended to analyze the controllability of Buck converters, etc.