Conceptualization and Analysis of a Next-Generation Ultra-Compact 1.5-kW PCB-Integrated Wide-Input-Voltage-Range 12V-Output Industrial DC/DC Converter Module

Abstract

The next-generation industrial environment requires power supplies that are compact, efficient, low-cost, and ultra-reliable, even across mains failures, to power mission-critical electrified processes. Hold-up time requirements and the demand for ultra-high power density and minimum production costs, in particular, drive the need for power converters with (i) a wide input voltage range, to reduce the size of the hold-up capacitor, (ii) soft-switching over the full input voltage and load ranges, to achieve low losses that facilitate a compact realization, and (iii) complete PCB-integration for low-cost manufacturing. In this work, we conceptualize, design, model, fabricate, and characterize a 1.5kW, 12 V-output DC/DC converter for industrial power supplies that is required to operate across a wide 300 V–430 V input voltage range. This module utilizes an LLC-based control scheme for complete soft-switching and a snake-core transformer to divide the output current with a balanced flux among multiple secondary windings. Detailed loss models are derived for every component in the converter. The converter achieves close to 96 peak efficiency with a power density of 337 W/3 ( 20.6kW/d3m), excellent matching to the derived loss models, and zero-voltage switching even down to zero load. The loss models are used to identify improvements to further boost efficiency, the most important of which is the minimization of delay times in synchronous rectification, and a subsequent improved 1.5kW hardware module eliminates nearly 25% of converter losses for a peak efficiency of nearly 97% with a power density of 308 W/3 ( 18.8kW/d3m). Two 1.5kW modules are then paralleled to achieve 3 kW output power at 12 V and 345 W/3 ( 21.1kW/d3m) with ideal current sharing between the secondary outputs and no drop in efficiency from a single module, an important characteristic enabled by the novel snake-core transformer.

Three-Port Series-Resonant DC/DC Converter for Automotive Charging Applications

“…Since in this application, the requirements and specifications of the two DC voltage ports (HV and LV) differ greatly, as on the one hand, the high-voltage port mainly has to cover a wide voltage range and, on the other hand, the low-voltage port has to deliver a very high current (up to 200 A) at a low output voltage, the question is raised as to whether an asymmetric topology would be more suitable. The same can be observed in the literature for two-port systems with similarly different port specifications, where different topologies are commonly used in the two converter ports for most efficient power conversion [13]. Consequently, a three-port topology must be developed in which the topology of each port is tailored to the port-specific requirements given by the application.…”

“…Consequently, hardly any systems with similar specifications have been presented in the literature so far with which the proposed topology could be compared. Nevertheless, it is possible to get a good impression of the performance of the system presented by comparing the efficiency and power density with an isolated two-port DC/DC converter with similar specifications [13] (PCB-integrated magnetics, 3 kW, V in = 400 V, V out = 12 V), which could be used in EV applications as supply for the LV-bus. It is found, that both the power density (16.4 kW L −1 vs. 21.1 kW L −1 ) and the efficiency (95.6% vs. 96.6%) are only slightly lower in the three-port system, even though there is an additional isolated power path (3.7 kW) between the PFC and the HV port included.…”

“…Thus, with the proposed three-port DC/DC converter and an additional non-isolated PFC rectifier, a complete three-port EV charger could easily be built. In order to obtain the same functionality with the two-port converter of [13], not only an additional non-isolated PFC rectifier, but also an isolated 3.7 kW DC/DC converter between the PFC port and the HV port would be required. Taking into account the power densities mentioned above, this would mean that the additional DC/DC converter should have a maximum volume of V max = 3.7 kW /16.4 kW L −1 − 3.7 kW /21.1 kW L −1 = 50 cm 3 so that in the end both chargers would be the same size.…”