Digital Control of PWM Systems for LED Application Using One-Cycle Averaging

This paper proposes an approximate output tracking control for a class of PWM switched dc-dc converters driving LED lighting systems. The proposed model provides a discrete-time response of the one-cycle average (OCA) value of output signal of the system. Typically, the proposed model has unstable zero dynamics, as well as a nonlinear dependence on the duty ratio control input. Using scheduled (operating point dependent) output redefinition, an approximate design model providing stable zero dynamics is achieved. The digital control is studied on a dc-dc converter operating in CCM and DCM by using zero DC error tracking controller (ZDCETC) and zero magnitude error tracking controller (ZMETC). The effectiveness of output tracking control options is evaluated and verified to track a desired output. The numerical simulation results confirm bounded and non-oscillatory responses with reduced tracking errors.