Small-signal analysis of PWM boost converter in CCM with complex impedance load

This paper presents a small-signal analysis of the pulse-width modulated (PWM) boost dc-dc converters operating in continuous-conduction mode (CCM) and subject to complex impedance load. Using the existing knowledge on the small-signal model of the boost converter obtained through the circuit averaging approach, this paper presents an extended analysis of the small-signal transfer functions, under the influence of resistive and inductive load impedances. The expressions for the control-to-output, input-to-output voltage transfer functions, and the output impedance of the boost converter operating in CCM are derived. The characteristics of these transfer functions are analyzed and the effect of the added inductance on the location of poles and zeros is discussed. It is shown that the inherent right-half plane (RHP) zero shifts to the left-half of the s-plane, when the load inductance is increased beyond a specific value. The theoretical results are validated by simulations of a boost converter with suitable design specifications.