Intermittent chaotic operation in switching power converters

In the process of designing and constructing switching power converters, chaotic operations are often observed intermittently between long periods of regular operations. In practice, such intermittent chaotic operations can be eliminated by incorporating appropriate design measures to combat interference of spurious signals. In this paper, we explain the mechanism that causes "intermittent" chaos in a popular type of switching converters, namely, current-mode controlled switching converters. The circuit model used to study the phenomenon incorporates a coupling process through which a spurious signal is coupled to the current sensing and ramp compensation circuitry, resulting in a modulation of the compensation slope which causes the system to become unstable intermittently. We show that coupling of spurious signals into the compensation ramp can cause intermittent chaotic or subharmonic operations.