The switching loss of the secondary side rectifiers in LLC resonant converters can have a noticeable impact on the overall efficiency of the complete power supply and constrain the upper limit of the optimum switching frequencies of the converter. Two are the main contributions to the switching loss in the secondary side rectifiers: on the one hand, the reverse recovery loss (Qrr), most noticeably while operating above the series resonant frequency; and on the other hand, the output capacitance (Coss) hysteresis loss, not previously reported elsewhere, but present in all the operating modes of the converter (under and above the series resonant frequency). In this paper, a new technique is proposed for the measurement of the switching losses in the rectifiers of the LLC and other isolated converters. Moreover, two new circuits are introduced for the isolation and measurement of the Coss hysteresis loss, which can be applied to both high-voltage and low-voltage semiconductor devices. Finally, the analysis is experimentally demonstrated, characterizing the switching loss of the rectifiers in a 3 kW LLC converter (410 V input to 50 V output). Furthermore, the Coss hysteresis loss of several high-voltage and low-voltage devices is experimentally verified in the newly proposed measurement circuits.
The advent of the first TiO2-based memristor in 2008 revived the scientific interest both from academia and industry for this device technology and has so far led to several emerging applications including logic and in-memory computing. Several memristive logic families have been proposed in the current quest for energy-efficient future computing systems. However, the limited device endurance and variability (both cycleto-cycle and device-to-device) are important parameters to be considered in the assessment of logic operations. In this work we used an accurate physics-based model of a bipolar memristor (supporting parasitics of the device structure and variability of switching voltages and resistance states) and demonstrate that performance of memristor-based in-memory computations can de degraded owing to both variability and state drift impact, if such features are not properly considered in the design flow. Inspired on pseudo-NMOS ratioed logic and based upon a CMOS-like logic scheme, we propose a crossbar-compatible memristive ratioed logic style which is tolerant to device variability and does not affect device endurance as computations do not involve conditional switching of memristors. Using the Cadence Virtuoso suite, we compare this logic scheme with MAGIC and CNIMP approaches, focusing on the universal NOR gate and complex logic functions.
This paper proposes a novel modulation technique for the bidirectional operation of the Phase Shift Full Bridge (PSFB) DC/DC power converter. The forward or buck operation of this topology is well known and widely used in medium to high power DC to DC converter applications. In contrast, backward or boost operation is less typical since it exhibits large drain voltage overshoot in devices located at the secondary or current-fed side; a known problem in isolated boost converters. For that reason other topologies of symmetric configuration are preferred in bidirectional applications, like CLLC resonant converter or Dual Active Bridge (DAB). In this work, we propose a modulation technique overcoming the drain voltage overshoot of the isolated boost converter at the secondary or current-fed side, without additional components other than the ones in a standard PSFB and still achieving full or nearly full ZVS in the primary or voltage-fed side along all the load range of the converter. The proposed modulation has been tested in a bidirectional 3.3 kW PSFB with 400 V input and 54.5 V output, achieving a 98 % of peak efficiency in buck mode and 97.5 % in boost mode operation. This demonstrates that the PSFB converter may become a relatively simple and efficient topology for bidirectional DC to DC converter applications.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.