Two-phase interleaving configuration of the LLC resonant converter - Analysis and experimental evaluation

Abstract

The LLC resonant converter has become quite popular in recent years and is more and more used for DC-DC converters within cost effective as well as high performance power supplies. Since in case of high output power and low output voltage it is typically beneficial to use paralleled converters, this paper investigates the load sharing issue of two LLC converters connected in parallel and operated with interleaved driving signals. Value deviations of all the three passive components of the LLC resonant circuit are considered and the worst case scenarios are highlighted. Moreover a simple and practical solution to the load sharing issue applicable to a high power server PSU is presented, including measurements on a prototype to support the theoretical analysis.

Design considerations for charge‐compensated fast‐switching power MOSFET in the medium‐voltage range

“…Interleaving converters represent a technique of paralleling converters that avoids both the direct paralleling of high-voltage switches on the converter primary side and the high-ripple current in the output capacitors due to the cancellation of such ripple currents [22].…”

Unbalanced three-phase interleaved LLC resonant converter: current phase angle balancing technique

“…However, auxiliary power switches had to be added ( [12]- [14]) or increased loss due to soft switching loss by phase shift [15]. Another method is to add a power stage to regulate the output voltage, increasing the loss, increasing the cost and volume of the converter ( [16]- [18]). The interleaved LLC resonant converter presented in [12] adds variable inductors to compensate for gain characteristic mismatch.…”

“…Figge et al [15], proposed the output voltage is regulated by variable frequency control of the primary switch, while the time delay control used to control the secondary side switch is to correct load current imbalances between inverters. In [16] and [17], the output voltage of the power factor correction (PFC) stage is used to compensate the parameter mismatch between two resonant modules. The PFC must be placed before each module of the resonator.…”

An Interleaved PFM <italic>LLC</italic> Resonant Converter With Phase-Shift Compensation

“…Therefore, the wide input voltage cannot be achieved. In [9], [10], since the parameter mismatch among phases of resonant circuit is compensated by varying the output voltages of power factor correction (PFC) circuit as the front stage, the PFCs must be placed in front of each phase of the interleaved LLC resonant converters. The series-input and parallel-output connection is proposed and analyzed in [11], [12].…”