Designing a Switched Mode Regulator for 48V 40A Battery ROV Applications

168 12

#1 21670162 20 Oct 2013 18:10

Amr Awny Amr Awny

Anonymous

Post #1
21670162 20 Oct 2013 18:10

I would like to design a switched mode regulator (48 volt 40 amp battery) for my rov but i don't know how to do it or how it look like if i purchase it
ADVERTISEMENT
#2 21670163 20 Oct 2013 20:01

Mark Harrington Mark Harrington

Anonymous

Post #2
21670163 20 Oct 2013 20:01

48 volts for a rov ?? What exactly is a Rov ?? do you mean Rover as in the vehicle ?
#3 21670164 21 Oct 2013 17:30

Amr Awny Amr Awny

Anonymous

Post #3
21670164 21 Oct 2013 17:30

remotely operated under water vehicle ,, the competition oblige us to use a 48 volt battery 40 amp , and I am using motors which use about 25 amp
ADVERTISEMENT
#4 21670165 21 Oct 2013 18:36

Cody Gass Cody Gass

Anonymous

Post #4
21670165 21 Oct 2013 18:36

If you're using a battery, why do you need a regulator? Are you trying to change the output voltage to something other than 48V?
#5 21670166 22 Oct 2013 16:23

Amr Awny Amr Awny

Anonymous

Post #5
21670166 22 Oct 2013 16:23

the bilge pump operates @ 10 volts and 2 of them are working @ the same time
ADVERTISEMENT
#6 21670167 22 Oct 2013 22:08

Mark Harrington Mark Harrington

Anonymous

Post #6
21670167 22 Oct 2013 22:08

So you looking at 50 amps combined total from the Battery if you have both motors going Thats a lot of current out of the battery Whats the amp hour on the Battery if you dont me asking
#7 21670168 23 Oct 2013 08:52

DAVID CUTHBERT DAVID CUTHBERT

Anonymous

Post #7
21670168 23 Oct 2013 08:52

Amr,

I recommend an off-the-shelf power supply. The reason is that a 2000 watt switching power supply is a major project and if you're like some of us you will go through a long and expensive learning process. And as reliability is probably paramount to your ROV, you don't want it failing.

If I understand, the input voltage is 48 volts. What voltage or voltages does the switching power supply need to deliver?
#8 21670169 23 Oct 2013 11:15

Cody Gass Cody Gass

Anonymous

Post #8
21670169 23 Oct 2013 11:15

So a 10 volt 50 amp SMPS? That's a pretty hefty project. I'd look into buying one. Building your first SMPS is tough and expensive. Building your first SMPS with it being capable of delivering 500+W and 10A is even tougher and more expensive.
ADVERTISEMENT
#9 21670170 23 Oct 2013 12:48

Mark Harrington Mark Harrington

Anonymous

Post #9
21670170 23 Oct 2013 12:48

Id use nucluer power ( Only In marine subs I didnt say use as an energy souce on land did I , justin case lol ) If i was you

I can see you batteries going flat at about 300 below see level after about half an hour either that or once you open the ballast tanks you wont have enough air to blow them out to get to the surface again with that sort of current drain
#10 21670171 20 Nov 2013 18:45

Amr Awny Amr Awny

Anonymous

Post #10
21670171 20 Nov 2013 18:45

I need to regulate the 48 input voltage to 12 output voltage plus , i want the motors will get 12 amp
#11 21670172 20 Nov 2013 20:12

DAVID CUTHBERT DAVID CUTHBERT

Anonymous

Post #11
21670172 20 Nov 2013 20:12

The Linear Technology LTM8027 uModule regulator operates to 60 volts and outputs 4 amps. These devices can be paralleled to supply the 12 amp motors.

To account for differences output voltage tolerance a series resistor of perhaps 0.1 ohms is placed in series with each regulator. This should be optimized using LTSpice at which time the number of devices can be determined to provide >12 amps under worse-case conditions.
#12 21670173 21 Nov 2013 07:17

DAVID CUTHBERT DAVID CUTHBERT

Anonymous

Post #12
21670173 21 Nov 2013 07:17

I think you would do best (save time and a steep learning curve) by going with an off-the-shelf solution. One solution I've used is the Vicor Maxi, Mini, Micro series of DC-DC converters.

For your 48-12 volt, 12 amp requirement the Vicor V48B12C250B will do the job. It will supply 12 volts at 21 amps and is $168 USD.

http://www.vicorpower.com/home/products.html?productType=cfg&productKey=V48B12C250B

To reduce EMI on the 48 volt bus a Vicor FIAM filter can be used.

http://www.vicorpower.com/documents/datasheets/ds_fiam.pdf
#13 21670174 06 Feb 2014 02:40

Garth Wilson Garth Wilson

Anonymous

Post #13
21670174 06 Feb 2014 02:40

I agree with the off-the-shelf path. SMPS design and construction is not for beginners. Even though the switching frequency may not seem that high, the di/dt's are astronomical, and good PCB layout and overall construction is imperative if you want decent behavior out of it.
Create an account, log in here. You will receive points by participating in discussions.
Join this discussion.

Install Elektroda application

Didn't find an answer? Ask Artificial Intelligence

*I agree to send the question to OpenAI, Anthropic PBC, Perplexity AI, Inc., Kagi Inc., Google LLC - owners of language models in order to prepare the best response. The companies may monitor and log information entered into the form.

*I agree to publicly display my question and answer. The question and answer will be publicly available to everyone. The process may take a few minutes. Upon completion, you will be redirected to the page with the answer.

Wait...(2min)

Topic summary

✨ The discussion focuses on designing a switched mode power supply (SMPS) to regulate a 48V battery source for a remotely operated underwater vehicle (ROV) application, specifically stepping down to 12V at 12A to power motors and bilge pumps. The original poster needs a regulator to convert 48V input to 12V output with sufficient current capacity. Several contributors recommend using off-the-shelf DC-DC converters due to the complexity, cost, and reliability challenges of designing a high-current (up to 40A) SMPS from scratch. Suggested solutions include paralleling multiple Linear Technology LTM8027 uModule regulators (each rated for 60V input and 4A output) with series resistors to share load current, and using Vicor Maxi, Mini, or Micro series DC-DC converters, specifically the Vicor V48B12C250B model, which provides 12V at 21A output and includes options for EMI filtering with Vicor FIAM filters. The importance of proper PCB layout and design to handle high di/dt and EMI in SMPS is emphasized. Battery capacity and current draw considerations for underwater operation are also noted.

Home page
/
Forum
/
Circuit Design
/
EEWeb Topics
/
Designing a Switched Mode Regulator for 48V 40A Battery ROV Applications

FAQ

TL;DR: For 48V ROV builds, step down to 10–12V using proven modules; a "2000 watt switching power supply is a major project" best bought off‑the‑shelf. This FAQ guides parts choices, sizing, and EMI control. [Elektroda, DAVID CUTHBERT, post #21670168]

Why it matters: Reliable power keeps thrusters and pumps running under pressure without burning time or budget.

Quick Facts

Target conversion: 48V input to regulated 12V output for motors. [Elektroda, Amr Awny, post #21670171]
Bilge pumps run at 10V; two operate simultaneously, so plan a 10V rail. [Elektroda, Amr Awny, post #21670166]
Off‑the‑shelf is advised; a 2 kW SMPS from scratch is a major project. [Elektroda, DAVID CUTHBERT, post #21670168]
Example pick: Vicor V48B12C250B → 12V at 21A; add FIAM filter for bus EMI. [Elektroda, DAVID CUTHBERT, post #21670173]
Modular path: LTM8027 handles up to 60V in, 4A out; parallel with small series resistors and validate in LTspice. [Elektroda, DAVID CUTHBERT, post #21670172]

What is an ROV and why are we using a 48V battery?

An ROV is a remotely operated underwater vehicle. The competition mandates a 48V battery, so your power system starts at 48V and must feed lower‑voltage loads. [Elektroda, Amr Awny, post #21670164]

Do I really need a regulator if my source is a 48V battery?

Yes. Your bilge pumps need 10V, and two run together. A regulator or dedicated DC‑DC stage is required to supply that rail safely. [Elektroda, Amr Awny, post #21670166]

What output spec do my motors need from the regulator?

You stated a 48V to 12V conversion, delivering about 12A to the motors. Size the converter and wiring for continuous 12A at 12V. [Elektroda, Amr Awny, post #21670171]

Can I build a 48V to 10–12V SMPS myself?

It’s possible but not recommended for your first design. As one expert noted, a 2000W SMPS is a major project; reliability matters underwater. [Elektroda, DAVID CUTHBERT, post #21670168]

What off‑the‑shelf 48V→12V module fits 12A or more?

Vicor’s V48B12C250B outputs 12V at 21A, covering your 12A requirement with headroom. Add a Vicor FIAM filter to tame bus EMI. [Elektroda, DAVID CUTHBERT, post #21670173]

How do I cut EMI on the 48V line feeding my converters?

Place an input EMI filter on the 48V bus. The suggested Vicor FIAM filter is designed for this and pairs with their DC‑DC modules. [Elektroda, DAVID CUTHBERT, post #21670173]

Can I parallel smaller regulators to reach 12A?

Yes. The LTM8027 handles up to 60V in and 4A out. Parallel several with small series resistors (≈0.1Ω) and verify sharing in LTspice. [Elektroda, DAVID CUTHBERT, post #21670172]

Why is SMPS layout such a big deal?

High di/dt currents make layout critical. "SMPS design and construction is not for beginners" because poor layout causes instability and noise. [Elektroda, Garth Wilson, post #21670174]

How much current could the system pull at full thrust?

If each motor draws about 25A, two motors together mean around 50A from the battery. Size conductors, fusing, and connectors accordingly. [Elektroda, Mark Harrington, post #21670167]

What should I do about the 10V bilge pumps?

Provide a dedicated 10V buck stage from 48V or from 12V, sized for both pumps’ combined current. Keep it isolated from motor spikes. [Elektroda, Amr Awny, post #21670166]

Quick how‑to: pick a 48V→12V converter for my ROV

Define outputs: 12V/≥12A for motors; 10V rail for pumps.
Select module: e.g., V48B12C250B for 12V/21A headroom.
Add input filter (FIAM), then validate under load on the bench before wet tests. [Elektroda, DAVID CUTHBERT, post #21670173]

What if I still want to design a custom multi‑module solution?

Model it first. Parallel LTM8027 uModules with small ballast resistors, tune values in LTspice, and confirm worst‑case current sharing margins. [Elektroda, DAVID CUTHBERT, post #21670172]

Is there a failure mode I should plan for early?

Watch for poor current sharing when paralleling modules. Mismatch can overload one regulator. Ballast resistors and simulation mitigate this risk. [Elektroda, DAVID CUTHBERT, post #21670172]

Why not overspec everything and be done?

Overspec costs and weight add up fast. A 21A, 12V module already provides margin over the requested 12A without unnecessary bulk. [Elektroda, DAVID CUTHBERT, post #21670173]

Who benefits most from off‑the‑shelf converters here?

Student or competition ROV teams gain reliability and speed. You avoid the steep SMPS learning curve and focus on mission tasks. [Elektroda, DAVID CUTHBERT, post #21670168]

Will layout still matter if I buy modules?

Yes. Keep short, wide high‑current paths and clean returns. Even with modules, layout discipline keeps noise and heat under control. [Elektroda, Garth Wilson, post #21670174]