General Design Issues of Sliding-Mode Controllers in DC–DC Converters

Abstract

This paper examines the practical design issues of sliding-mode (SM) controllers as applied to the control of dc-dc converters. A comprehensive review of the relevant literature is first provided. Major problems that prevent the use of SM control in dc-dc converters for industrial and commercial applications are investigated. Possible solutions are derived, and practical design procedures are outlined. The performance of SM control is compared with that of conventional linear control in terms of transient characteristics. It has been shown that the use of SM control can lead to an improved robustness in providing consistent transient responses over a wide range of operating conditions.

Switching Frequency Regulation in Sliding Mode Control by a Hysteresis Band Controller

“…This method implements directly an ideal equivalent control calculated from a desired switching surface by a PWM at fixed frequency, while an algorithm to estimate the switching surface parameters was recently proposed in [23]. Results were summarized in [22], confirming an overall good performance. However, this solution can be derived without using sliding mode concepts, as the equivalent control is a continuous-time function that could be extracted imposing a desired dynamics to the system.…”

“…Thus, it follows from (55) that ρ ± * (t) are bounded, and so isρ * (t). Hence, it stems from Theorem 2 that the SFC with control law given in (22) yields a uniformly exponentially stable closed-loop system for 43383 < γ < 143170. Nevertheless, as it happened with the numerical example, the closed-loop system is still stable for positive values lower than 42142.…”

“…Finally, let the hysteresis band amplitude, ∆, be updated according to (22). If and the integral gain γ is selected as γ ∈ (γ m , γ M ), then the switching period, T k , converges asymptotically to its reference value, T * , in the steady state.…”

“…This is because the SFC control (22) includes the feedforward term Ω k introduced in (24), which requires knowledge of the current switching function derivatives, i.e. at period k. Of course the hysteresis band amplitude ∆ k should be calculated at the beginning of the period, when the available information is that of the k − 1 switching period.…”

An Effect of Output Capacitor ESL on Hysteretic PLL Controlled Multiphase Buck Converter

“…1, a small portion of inductor current ripple is fed into the comparator to improve noise immunity. When a robust control method like SMC (Sliding Mode Control) theory is used to design a hysteretic controller, then the output capacitor current instead of the inductor current is needed, since a variable and its first derivative, in this case, capacitor voltage and capacitor current are required for generating the switching function in agreement with SMC theory [8][9][10].…”