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SUMMARYDigital control in switching power converters has been proposed and researched in recent years. However, one of the problems which arise in these circuits is that of quantization-induced limit cycle oscillations, which are generally considered to be undesirable. In this work, we investigate the addition of new control terms in the feedback loop of the system, in order to actively prevent these limit cycles from occurring. Firstly, the addition of a sinusoidal signal is considered, and then a more complicated signal which focuses on interrupting how the system switches between duty cycle levels is presented. The methods are effective in removing the limit cycle oscillations which arise in the system.

Digital control of power converters has been an\ud area of considerable research interest in recent times. One of\ud the problems which arises in these systems is that of the limit\ud cycle oscillations that occur due to quantization in the feedback\ud loop. This paper investigates the limit cycle oscillations that occur\ud in the digitally controlled version of the buck converter with a\ud proportional-integral controller. The amplitude and frequency\ud of the oscillations that may occur on two duty cycle levels are\ud investigated and related to the controller gain parameters. The\ud analysis shows that it is not possible to guarantee that limit\ud cycle oscillations on two levels will not occur simply by adjusting\ud the gain parameters, and yields a condition which will prevent\ud oscillations on two levels from occurring.Postprint (published version

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