12V to 24V Boost COTS Research
- Daniel Puratich
- Tim Gu
Who
@Daniel Puratich idea
@Tim Gu looking into it
What
Take in 12V and output 24V
For powering our 24V battery charger
would be massive help at comp and flight tests to be able to charge faster
Supply enough power for the charger
if the current is really high then this project is going to be waaay out of our skill range
Why
We have 12V server PSUs that are CSA approved
We get more power capability out of the charger at 24V
we could also just buy this? not sure if it maths out.
Initial Requirements:
12V - 24V @~40A Boost Converter PCB
Input 12V from PSUs, output 24V
Output Current
7A of current x 4 batteries was recommended - targeting 28A output current (672W output power)
Cost
Not sure if this is that much of a concern
The COTS option we identified was ~$100 off AliExpress, we can aim to do lower than that, but not a primary goal
Timeline?
Topology:
Due to the high power requirement, it may be best to design the board using the interleaved multiphase boost topology:
Essentially several boost convertors operating in parallel, out of phase with each other (their on/off switching alternates)
While one phase ramps up current, the other phase ramps it down.
Output current being split between multiple phases reduces power losses, which makes this more efficient than a single phase boost convertor. We may not need a heatsink
Example of a six-phase interleaved boost convertor: PMP31073 reference design | TI.com
Important components/features:
TODO: Research for component selection
Switching regulator/controller IC
to generate the PWM signals to control the MOSFETs
should find one that supports the multiphase boost topology
This will determine how we choose some of the other components
Inductor
Capacitor
MOSFET
Diode
Current sense (probably copying Hall effect sensor from other boards)
Overvoltage protection?
Research for COTS options:
Details
Battery charger: HotA F6 Quad Battery Charger (4 x 15 A)
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1000 W output power limit across the 4 channels, with max current 4 x 15 A.
PSU:
Supermicro PWS-741P-1R Datasheet
DC output: 740W, 12V/61.7A
What convertor to buy?
Suggestions from @Jerry Tian and @Ryan Scomazzon : Charger should be able to charge 5.5Ah batteries at 1C. 7A of current per battery was recommended.
If charging 4 batteries at once, charger must supply 4 x 7A at 24V = 672 W.
Ideally the convertor should be rated for well above 672 W (it should have some headroom)
COTS options:
The product from the following brand is the best I could find in terms of price and provided specifications. Most other products don’t have a datasheet
Though it is from AliExpress, is it sketchy to buy this from there?
Couldn’t really find anything good on Amazon or Facebook Marketplace
Product | Price | Ratings | Features | Datasheet | Notes |
|---|---|---|---|---|---|
Szwengao WG-12S2420M
| (AliExpress) | 24V 20A 0-480 W |
| https://proa2427b-pic7.websiteonline.cn/upload/WG-12S2420M.pdf |
|
Szwengao WG-12S2430M 
| 77.99 (AliExpress) | 24V 30A 0-720 W |
| https://proa2427b-pic7.websiteonline.cn/upload/WG-12S2430M.pdf |
|
Szwengao WG-12S2440M ✅  | 100.68 (AliExpress) | 24V 40A 0-960 W |
|
|
The WG-12S2440M should suit our needs
Usage
Uses screw terminal connections
Is there any designing that has to be done for wiring/harnessing? Diagrams?
On the output side: 672 W load at 24V - output current is 672/24 = 28 A
On the input side: Assuming 97% efficiency, input power is ~693 W at 12V - input current is 693/12 = 57.7 A
4 AWG wire?
Do we need a fuse for the wire carrying high current between the PSU and the boost convertor?