Low-Frequency Characterization of Switched dc-dc Converters

Abstract

The objective is attained here by the development of continuous linearized models for the switched power stages in Fig. 2; thus, the power stage and controller can be treated as separate linear blocks. Averaged Power-Stage Models General ModelsConsider first the boost power stage. One can easily verify that Fig. 3 is an exact equivalent circuit' of the boost power stage shown in Fig. 2(B) T-The effect of averaging is approximately that of a low-pass filter with cut-off frequency ws = 2ir/T. The time-averaged model of the boost power stage is shown in Fig. 4(A)

Theoretical Assessment of DC/DC Power Converters’ Basic Topologies. A Common Static Model

“…where k1 and k2 are given by (18) and (25) respectively. Figure 10 shows a buck-boost converter that includes its main non-idealities (losses).…”

A mathematical steady-state design model for fully-integrated boost and buck DC–DC converters

“…The second initial condition depends on the circuit input variables U in , I max and the value of the voltage U C 0 ð Þ over C at the end of the charge phase, in steady-state. Both the initial conditions are given by (4).…”

“…Moreover, the Q-factor of on-chip passives is also much lower than their off-chip equivalents, resulting in increased parasitic series resistances of L and C. Therefore, steady-state models for DC-DC converters with external components, such as [1,2] and [3], are not suited for the accurate calculation of their fully-integrated equivalents. Also average models that provide information on the DC-DC converter's dynamics, such as [4,5] and [6], are insufficiently accurate for steady-state.…”

Output impedance considerations for switching regulators with current-injected control

“…State-space averaging and linearization [7], [8] are used to derive expressions for open-loop gain, audiosusceptibility and output impedance of a constant frequency CIC Manuscript received July 8, 1987; revised September 7, 1988 buck regulator with load-current feedforward. These expressions are then compared to those obtained for both CIC without load-current feedfonvard and lead-compensated voltage control at several different loop gains.…”