Improved Switching Converter Model Using Discrete and Averaging Techniques

Abstract

The nonlinear modeling and analysis of dc-dc converters has been done by averaging and discrete-sampling techniques. The averaging technique is simple, but inaccurate, as the modulation frequencies approach the theoretical limit of one-half the switching frequency. The discrete technique is accurate even at high frequencies, but is very complex and cumbersome. An improved model is developed by combining the aforementioned techniques. This new model is easy to implement in circuit and state variable forms and is accurate to the theoretical limit.

Frequency-Domain Analysis of Switching Closed-Loop Regulators

“…The notation d4)Idt [3] may be adopted, but in this notation 4) is the value at the beginning of the cycle (4)(0)), not the mean value, and the derivative is defined at discrete moments in time (t = kT). The same considerations are taken for (11), (21), and the variable V.…”

“…The variable X o 4.47 x 101; 4.38 x 103, therefore D2T 0.0447; 0.0438. If the output capacitor is large enough for good filtering, wD2T is always much smaller than unity; consequently, cos(wD2T) 1 The abovementioned approximations lead to maximum errors of 3 percent for the first numerical example and 4.5 percent for the second.…”

Reconsideration of loop gain measurement of DC/DC converters

“…As a result, the accuracy of the model is critical to guarantee the performance of the DC/DC converter as expected. There are several models of the DC/DC converter, such as the state space average model [1], the discrete model [2] and the discrete average model [3]. However, any model will have approximation [4], which leads to the difference between the model and the real characteristics of the DC/DC converter.…”

“…The MSPM is simple to be implemented and is easy to be understood. However, this method will yield erroneous measurement result if the perturbation signal at the point where the loop gain is measured contains a pulsating nature [3], [8]- [11]. To overcome this problem, the PSPM, which perturbs the duty cycle signal, is proposed [9].…”

Modeling and optimal-trajectory control of the series resonant converter pulsewidth-modulated or current-controlled for low switching loss

“…Especially, this approach could be extensively used in the resonant converters [3]. The combination of both averaging and discrete techniques has also been studied [4].…”