Vicor DC-DC benchmarking queries

[biswaIITH]

Has anyone used Vicor DC-DC ?
How are they able to achieve such small dimension for power rating exceeding 600W to 1000W?
Like what kind of topologies ,devices & switching frequency etc.

Anyone has done any kind of benchmarking

 

[D.A.(Tony)Stewart]

No but this may interest you. Google's $1m contest 2014~2016

The Little Box Challenge

An open competition to build a smaller power inverter, with a $1,000,000 prize.

web.archive.org

the winning team exceeded the power density goal for the competition by a factor of 3, which is more than 10 times more compact than commercially available inverters

A key factor in the winning inverters was the use of wide bandgap semiconductors e.g GaN
The thermal design is impressive.

https://odnawialnezrodlaenergii.pl/energia-sloneczna-aktualnosci/item/download/203_61070c51fa7d3cd64e143082145c4b9a

This Technical Approach Document outlines the innovations and features of the Red Electrical Devils' project involving a 2 kVA inverter designed using Gallium Nitride (GaN) technology.

Key Points:

1. GaN Technology: The project leverages GaN technology, which allows for a high power density of approximately 145 W/in.³ for the 2 kVA inverter. GaN transistors offer several advantages, including low resistance, gate capacitance, and reverse recovery charge, leading to small size and low production costs.
2. Challenges with GaN: GaN transistors have fast switching characteristics, which can be challenging to drive and require effective electromagnetic noise management. Additionally, they can experience a high voltage drop when turned off.
3. Solution: Soft Switching: To overcome these challenges, the project employs a solution involving soft switching for all GaN transistors throughout their operational range.
4. Topology: The inverter design features a five-leg topology to combine a continuous current at the 450 V input stage with an alternating 240 V output voltage. It includes half bridges, active filters, inductors, capacitors, and other components to optimize energy transfer.
5. Control Algorithms: The inverter's efficiency is achieved through precise control algorithms that ensure soft switching operation of GaN devices and protection against overcurrents. The project involves a high-performance microcontroller, feedback systems, and optimization of switching frequency and phase shifts.
6. Miniaturization: The inverter components are miniaturized for DC-AC conversion, including MLC capacitors for energy storage, ferrite-based magnetic components, Litz wires for minimizing losses, and open-loop Hall sensors for compact current measurements.
7. Thermal Management: Effective thermal management is vital, with forced air cooling using an axial fan, copper components, and ceramic capacitors acting as an additional heatsink. The design minimizes hot spots and ensures GaN transistors operate within safe temperature limits.
8. Electromagnetic Compliance (EMC): To meet FCC part 15 class B compliance, the project focuses on the choice of topology and modulation based on noise source models. It includes internal and external shielding, small filters, and other strategies to reduce electromagnetic interference.
9. Conclusions: The combination of GaN transistors operated in Zero Voltage Switching (ZVS) mode, a specific active filtering topology, MLC capacitors, optimized thermal interfaces, and EMC strategies contribute to achieving high power density and compliance with electromagnetic standards.

--- Updated Oct 30, 2023 ---

https://www.vicorpower.com/documents/applications_manual/DesignGuideAppsManual_200J00.pdf

https://www.vicorpower.com/documents/design_guides/DG-DCM-Design-Guide-VICOR.pdf

Vicor White Paper https://file.elecfans.com/web1/M00/20/E7/oYYBAFmk3N6AH0sCAAVKiCbZa8s633.pdf

Hybrid bricks using the ZCS/ZVS (Zero Current Switching/Zero Voltage Switching) resonant technique were able to achieve power densities of 100 W/in3.

 

[cupoftea]

Yes Vicor is brill as Tony Stewart also implies i think...of course, you still need to dunk a heatsink on those little modules....and often fans over those heatsinks. Vicor do loads of app notes detailing all this.
They are always too pricey for my type of client, and not in stock enough.
But they keep it secret aswell.
The thermal potting os v good...and of course, its some special resonant topology.....sometimes you need two in cascade though, to get the regulation.

 

[D.A.(Tony)Stewart]

The Red Electrical Devils' design was the winner is even more impressive https://web.archive.org/web/2016080...boxchallenge.com/pdf/finalists/56568-Tech.pdf

 

[Easy peasy]

With Vicor - you may find heatsinking a challenge - the quiescent load is often quite high

you need to supply caps for input and output and emc filters - too much load C can upset them

there can be other quirks - you need to read all data sheets carefully

 

[Tahmid]

The Red Electrical Devils' design was the winner is even more impressive https://web.archive.org/web/2016080...boxchallenge.com/pdf/finalists/56568-Tech.pdf

From purely a power density point of view, also look at the Pilawa group's work at 216W/in³.

Little Box Challenge | Pilawa Research Group

--- Updated Nov 5, 2023 ---

Has anyone used Vicor DC-DC ?
How are they able to achieve such small dimension for power rating exceeding 600W to 1000W?
Like what kind of topologies ,devices & switching frequency etc.

Anyone has done any kind of benchmarking

In essence, it comes down to reducing the volume by targeting 2 aspects:

1. Typically your passives (especially magnetics) occupy the largest volumes. These can be reduced by using higher effective switching frequencies - and maybe even considering alternate topologies utilizing more energy-dense capacitors as the primary energy storage components.
2. By increasing efficiency, you can reduce the volume required for thermal mitigations. This can be done with a variety of soft-switching and resonant techniques, depending on the topology being used.

GaN transistors (and SiC at higher voltages too) further contribute to designing with higher switching frequencies and at higher efficiencies.

And then, of course, there is a lot of very good packaging design that commercial designers like Vicor are very good at.

 

[D.A.(Tony)Stewart]

The thermal design is critical. I was confused at first about who actually won the 2016 challenge as both appeared to be the winner. "our experimentally measured power density of 216 W/in^3 (the competition winner achieved 143 W/in^3, "

Then I saw the Red Electrical Devils rated density included the 1U high fan.