Power density

About: Power density is a research topic. Over the lifetime, 9534 publications have been published within this topic receiving 197264 citations. The topic is also known as: volumic power & volume power density.

Design of a 1-MHz High-Efficiency High-Power-Density Bidirectional GaN-Based CLLC Converter for Electric Vehicles

Abstract: In this paper, a bidirectional CLLC converter operating at MHz-level switching frequency is proposed to achieve high power density and high efficiency. An optimized stacked printed circuit board winding based planar transformer with adjustable leakage inductance is modeled and designed for the proposed converter. It is enabled using gallium nitride devices to achieve fast switching with low switching losses. A detailed power loss model is established for the efficient thermal design of the converter. A proof-of-concept hardware of 3.3 kW, 400–450 VDC input, 250–420 VDC output CLLC converter with 1 MHz operating frequency is built and tested over a wide range of loading conditions. The power density of the system is 9.22 W/cm3 (151.1 W/in3) and the peak efficiency achieves over 97%.

Series-Connected Partial-Power Converters Applied to PV Systems: A Design Approach Based on Step-Up/Down Voltage Regulation Range

Abstract: This paper proposes a novel approach to reduce the power processed by series-connected partial-power converters (S-PPC) applied to string/multistring level maximum power point tracking photovoltaic systems. A design procedure based on the definition of the voltage regulation range is presented. It introduces an additional degree of freedom that allows a proper design of the converter in order to reduce not only the active power but also the nonactive power, reducing losses and increasing power density. By means of the proposed approach, it is also demonstrated that by replacing the conventional step-up partial-power converter by a step-up/down partial-power converter, the active and nonactive power can be further reduced, allowing to better explore the benefits of the partial-power concept. In order to validate the proposed approach, two 750-W prototypes of full-bridge S-PPC and full-bridge/push–pull S-PPC were implemented and experimentally evaluated. The step-up/down prototype presented a reduction of 46.9% in nonactive power and 23.4% of its volume, resulting in a higher efficiency and power density in comparison to the voltage step-up prototype counterpart.

Tailoring a fluorophosphate as a novel 4 V cathode for lithium-ion batteries

Abstract: Lithium-ion batteries, which have been widely used to power portable electronic devices, are on the verge of being applied to new automobile applications. To expand this emerging market, however, an electrode that combines fast charging capability, long-term cycle stability, and high energy density is needed. Herein, we report a novel layered lithium vanadium fluorophosphate, Li1.1Na0.4VPO4.8F0.7, as a promising positive electrode contender. This new material has two-dimensional lithium pathways and is capable of reversibly releasing and reinserting ~1.1 Li+ ions at an ideal 4 V (versus Li+/Li) to give a capacity of ~156 mAh g−1 (energy density of 624 Wh kg−1). Moreover, outstanding capacity retentions of 98% and 96% after 100 cycles were achieved at 60°C and room temperature, respectively. Unexpectedly high rate capability was delivered for both charge and discharge despite the large particle size (a few microns), which promises further enhancement of power density with proper nano-engineering.

Structure-design strategy of 0–3 type (Bi0.32Sr0.42Na0.20)TiO3/MgO composite to boost energy storage density, efficiency and charge-discharge performance

Abstract: A novel 0–3 type (Bi0.32Sr0.42Na0.20)TiO3/MgO composite is investigated in this work, which possesses a high stored energy storage density ws˜2.50 J/cm3, recoverable energy storage density WR˜2.09 J/cm3 with high efficiency η˜84% under low electric field (20 kV/mm). The excellent performance is owning to the increase of breakdown strength (BDS) value and the intrinsic mechanism for enhanced BDS value by MgO incorporation is disclosed by numerical simulations (COMSOL). Moreover, the studied composite exhibits excellent charge-discharge performance, the current density (CD) and power density (PD) are 1671 A/cm2 and 150 MW/cm3, respectively, which are much superior to that of other ceramics. Besides, most of the stored energy is discharged within ˜0.15 μs via charge-discharge tests. This work not only provides a novel technique to designing bismuth-based ceramic capacitors with simultaneously high Wd, η and excellent charge-discharge performance, but also deepens the understandings of the role for the metallic oxide in the composite.

Design of segmented thermoelectric generator based on cost-effective and light-weight thermoelectric alloys

Abstract: A segmented thermoelectric (TE) generator was designed with higher temperature segments composed of n-type Mg 2 Si and p-type higher manganese silicide (HMS) and lower temperature segments composed of n- and p-type Bi–Te based compounds. Since magnesium and silicon based TE alloys have low densities, they produce a TE module with a high specific power density that is suitable for airborne applications. A two-pair segmented π-shaped TE generator was assembled with low contact resistance materials across bonding interfaces. The peak specific power density of this generator was measured at 42.9 W/kg under a 498 °C temperature difference, which has a good agreement with analytical predictions.