Fuzzy compensation of the load characteristics of a microcomputer based DC to DC converter

A study of the chopper load characteristics was conducted highlighting the problem of discontinuous conduction encountered with chopper fed DC drives and switch mode power supplies under light loads. The problem resides in the nonlinear increase of the output voltage as the load current drops below a critical value that depends on the chopper duty cycle K. An analytical study was undertaken to determine the amount of nonlinear compensation required to linearize the load characteristics. This paper develops a technique to linearize the load characteristics of a DC to DC characteristics using fuzzy compensation. A fuzzy rule base was constructed using two input universes of discourse: the armature current and the original duty cycle. The output universe of discourse is the negative offset of the duty cycle. The results are experimentally validated. A microcomputer provided with ADA card is used to perform the control of the chopper duty cycle and the online fuzzy compensation of its load characteristics.