V²I<inf>C</inf> control: A novel control technique with very fast response under load and voltage steps

Abstract

Abstract-High switching frequencies (several MHz) allow the integration of low power DC/DC converters. Although, in theory, a high switching frequency would make possible to implement a conventional voltage mode control with very high bandwidth, in practice, parasitic effects and robustness make very complex to achieve bandwidths higher than 1MHz. This paper proposes a fast control technique to optimize the dynamic response of high switching frequency DC/DC converters. The proposed control is based on two loops. The fast internal loop has information of the output capacitor current and the error voltage, providing fast dynamic response under load and output voltage reference steps, while the slow external voltage loop provides accurate steady state regulation. Experimental results validate the fast dynamic response of the proposed control under load and output voltage reference steps and its suitability for high switching frequencies.

Improved transient response of controllers by synchronizing the modulator with the load step: application to v2ic

“…1), proposed in [1], is a ripple-based control that presents a very fast dynamic response under load perturbations and reference voltage steps [2], [3]. It is composed by a slow loop, where the output voltage is regulated with a linear controller, and a fast loop, composed by the error of the output voltage and the current through the output capacitor.…”

“…2). As the reference voltage step acts as a constant offset if it does not change, [1] and [4] with the same modulation have the same transient response under load perturbations.…”

Overview, equivalences and design guidelines of v¹ concept: A voltage mode control that behaves as a current-mode with near time-optimal response

“…Some ripple-based controls such as v 2 [1,2] and v 2 i c [6,11] only sense the output voltage but they are in nature current-mode controls. This is because the output voltage has inherently information of the capacitor current (from the ESR of the capacitor or by using a trans-impedance amplifier).…”

“…This control is named v 2 i c (or "current-mode control of the output capacitor current" in a previous version from 2010 [9]). Using the capacitor current to improve the dynamic response is not a new concept since it dates back at least to 1986 [10], but [6] improves the idea by using a simple lossless sensor of the capacitor that only measures the output voltage and that takes into account the ESL of the output capacitor. In 2013, [11] proposed the same concept with a different implementation of the sensor of the current.…”

“…In [4,5], the inductor current is added to the v 2 control to stabilize it. On the other hand, [6], proposed in 2011, instead, to add the capacitor current information using only the output voltage, which allows the control to behave almost optimally under load transients [7,8]. This control is named v 2 i c (or "current-mode control of the output capacitor current" in a previous version from 2010 [9]).…”