On the voltage pulse-width modulation control of L-C filters

Pulse-width modulation is broadly used to control electric and electronic devices. The operation of many of these devices is based on the control of the output voltage of a passive filter. Their controllers are designed from the approximate linearization of the dynamics of the joint system, filter-pulse width modulation strategy, which is strongly nonlinear. Common linearization techniques work fine when the modulation frequency is much larger than the natural frequencies of the filter, but fail when that frequency is of the same order of magnitude or smaller than these filter frequencies, as happens in power electronic circuits. This paper develops a new linearization technique that allows a very precise control of these devices when small modulation frequencies have to be used. Our method permits the design of power electronic circuits with very fast output dynamic responses. An experimental circuit is developed to test this and results are reported.