Hyper-efficient (98%) and super-compact (3.3kW/dm³) isolated AC/DC telecom power supply module based on multi-cell converter approach

Abstract

In this paper, a multi-cell converter approach for a telecom rectifier module breaking through the efficiency and power density barriers of traditional single-cell converter systems is shown. The potential of the multi-cell approach for high efficiency is derived from fundamental scaling laws of the system performances, such as the losses generated by the semiconductors and the harmonic spectrum, in dependence of the number of converter cells. Furthermore, a comprehensive optimization of the entire system with respect to efficiency and volume has been performed and the applied component loss models are described in detail. The achievable performance of the system is compared to a leading edge state-of-the-art single-cell converter system which currently sets the benchmark in terms of efficiency and power-density. In addition, the degrees of freedom of multi-cell converter systems in terms of converter operation are outlined and optimum control schemes are derived. I. INTRODUCTIONToday's single-phase telecom power supply modules usually comprise a PFC rectifier stage and an isolated DC-DC converter output stage, typically generating a nominal output voltage of 48 V. The rectifier stage in conventional power electronic systems is a boost-type PFC rectifier which consists of a full-bridge diode rectifier in connection with a boost converter. Since the forward voltage drops of the diodes in the rectifier account for high conduction losses, alternative topologies have gained significant interest over the past years [1], [2]. E.g. in [3] a triple-parallel-interleaved TCM PFC rectifier system is described in combination with a double-parallel-interleaved phase-shift full-bridge isolated DC-DC converter for telecom applications (rated power P out = 3.3 kW, output voltage V out = 48 V) featuring a power density of ρ = 3.3 kW/dm 3 and an efficiency of η = 97 % at half of the rated power. As shown in [4], this concept currently presents the leading edge technology for telecom power supplies and therefore serves as a benchmark system in this paper. A new approach towards a hyper-efficient and super-compact telecom rectifier design beyond the barriers of traditional converter concepts is presented in this paper. The approach is based on a multi-cell converter concept that leverages the advantages obtained by employing multiple series-parallel connected converter cells instead of a single converter, such as lower conduction and switching losses and reduction of harmonics by interleaving [5]. The performance targets that can be achieved with this approach are an output power of P out = 3.3 kW with a conversion efficiency of 98% at part

Multi-port multi-cell DC/DC converter topology for electric vehicle's power distribution networks

“…The same behavior can be found for PB,1,diff and PB,2,diff, as they are directly proportional to the voltage error VB,nom − VB,k according to (12). It can be seen, that the simulated output power values PB,k smoothly follow their reference values PB,k,set = PB,k,diff + PB,nom, yielding the desired voltage balancing of VB,1 and VB,2.…”

“…This also reduces the required DC link capacitance for a certain allowed voltage ripple and lowers the volume of these components. The proposed multi-cell approach for multi-port converter systems has already been investigated for two-port converter systems in telecom applications, where, due to the aforementioned benefits, a significant improvement in terms of efficiency and power density was achieved [12]. However, while for two-port converter systems, e.g.…”

“…with ISOP structure, a simple modulation scheme with common duty cycles and phase shifts for all individual converter cells can be applied [12]. The advantage of this control strategy is the minimization of the complexity and computation effort of the control, as a single controller can be used to calculate the common control parameter set DA, DB, DC, ϕAB and ϕAC for all converter cells.…”

Contactless DC Connector Based on GaN LLC Converter for Next-Generation Data Centers

“…Functions of the galvanic isolation and the voltage transformation are inherited to the ICCC. The high power density ac-dc converter without the distribution transformer is a part of the solid state transformer and their performances have been already reported [10], [11]. The contactless power supply technology for dc connectors has been also reported [12], [13].…”