Thermal management for multi-phase current mode buck converters

Abstract

The main goal of this thesis is to develop an active thermal management control scheme for multi-phase current mode buck converters in order to improve the long term reliability of the converters. A thermal management unit (TMU) with independent linear compensators for the thermal loops is incorporated into the existing digital controller to regulate the current through each phase so that equal temperature distribution is achieved across all phases. A lumped parameter thermal model of the multi-phase converter is built as the basis of the TMU. iii

ℋ²-optimal thermal management for multi-phase current mode buck converters

“…The maximum difference in the average temperature between all phases is reduced from 12.4 • C to 1.8 • C, and the peak phase temperature is reduced from 58.8 • C to 53.7 • C within the power-stage area. The results are similar to those reported in [13], where the maximum difference in the average temperature between all phases was reduced from 8.9 • C to 1.4 • C, and the peak phase temperature was reduced from 64 • C to 60 • C within the power-stage area. This clearly shows the effectiveness of the TMU for achieving a uniform steady-state temperature distribution.…”

“…The system speciÀcations are listed in Table I. The parameters are identical as those in [13], with the exception that InÀneon OptiMOS devices were used for the power switches. This resulted in higher converter efÀciencies and generally lower temperatures.…”

“…Since the thermal loops in the phases operate in the same frequency range, they cannot be decoupled into independent SISO systems. As such, traditional PID-based single-input, single-output (SISO) design strategies, as proposed in [13], do not extend reliably to such cases, and the closed-loop system behaviour (such as stability) is difÀcult to predict. Second, the variability in the thermal system parameters imply that the PID-based designs must be tweaked experimentally to obtain satisfactory results.…”

“…The objective of this paper is to employ a multi-variable H 2 controller to quickly stabilize the phase temperatures under dynamic conditions. Previous work [13] relied on four completely independent thermal PI compensators. This approach implies that each temperature compensation loop operates independently without utilizing the readily available temperature feedback from the other phases.…”

A 12 to 1 V five phase interleaving GaN POL converter for high current low voltage applications

“…The multiphase converter also increases the effective output switching frequency which results in smaller size and higher power density [9]. Multiphase converters in previous efforts have demonstrated operating temperatures on the power devices of approximately 55 • C up to 60 • C at 40 A (10 A per-phase) output current with thermal management control techniques and forced air flow [10]. The presented design looks to lessen the need for advanced control techniques and minimize the need for forced air.…”