Control Design and Loop Gain Analysis of DC-to-DC Converters Intended for General Load Subsystems

Figure 2

Current-sink loaded and current-mode controlled PWM DC-to-DC converter. (a) The diagram represents the buck converter with connections , the boost converter with , and the buck/boost converter with . The CSN represents the current sensing network and PWM is the pulsewidth modulation block. (b) Small-signal model: is the duty ratio and and with , for the buck converter, and for the boost and buck/boost converters. Consider for the buck converter, for the boost converter, and for the buck/boost converter with . represents the DC gain of CSN. is the sampling gain of CSN: with and , where is the switching period. is the modulator gain [7] of PWM block with : on-time slope of the sensed inductor current, , and : slope of the compensation ramp. represents the feedback/feedforward gain of current mode control [7]: for the buck converter, for the boost and buck/boost converters, for the boost converter, and for the buck and buck/boost converters. is the voltage feedback compensation.

(a)

(b)