Digital Robust Control for DC-DC Converter with Second-Order Differential Characteristics

Robust DC-DC converter which can cover extensive load changes and also input voltage changes with one controller is needed. Then the demand to suppressing output voltage change becomes still severer. We proposed an aproximate 2DOF digital controller which realizes the startup response and dynamic load response independently. The controller makes the control bandwidth wider, and at the same time makes a variation of the output voltage small at sudden changes of loads and the input voltages. In this paper, a new approximate 2DOF digital control system with additional zeros is proposed. Using additional zeros a second- order differential transfer characteristics between equivalent disturbances and an output voltage is realized. So the new controller makes a variation of the output voltage more small at sudden changes of loads and the input voltages. This controller is actually implemented on a DSP and is connected to a DC-DC converter. Experimental studies demonstrate that this type of digital controller can satisfy given severe specifications.