Margins of stability of inner-current loop of peak current-mode controlled PWM dc-dc converters

This paper presents expressions for the limiting value of the duty cycle and the minimum value of the slope compensation for marginally stable operation as well as for the normalized crossover frequency, the maximum duty cycle, and the value of the slope compensation at a required phase margin. These quantities describe the performance of the inner-current loop in peak current-mode controlled PWM dc-dc converters. The derivations are based on the Pade approximation of z = exp(sT_s). The results of this paper can be used for the design of the inner-current loop with a specified phase margin.