-----Original Message-----
From: Alex <spm2@nomad.ignorelist.com>
To: personal_submersibles <personal_submersibles@psubs.org>
Sent: Mon, Jun 25, 2012 11:10 pm
Subject: RE: [PSUBS-MAILIST] 12 or 24v ? - PWM controllers
If the motors are controlled by PWM make sure it's done correctly, especially
if it's regulating down from a voltage that is higher than the motor is
designed for. Sometimes people use low speed switching to regulate motor
speeds. This is like turning the motor fully on and full off over and over,
where the motor current is going to the maximum then zero over and over. This
is like controlling the motor with a resistor, where the motor coils are the
resistors. A proper PWM controller uses a high frequency and either has an
inductor built in or uses the inductance of the motor coils. This creates a
constant current through the motor which is what you want.
Alex
On 13-Jun-2012 Greg wrote:
> Hi James,
>
>
>
> As they say - "voltage is your friend". Always bump it up if you can. Try
> running the minn kotas with a PWM speed control that's being fed 36V.
>
> Install an amp gauge on the leads going to each thruster. Then, under load,
> increase speed until you reach the maximum amount of amps that the motors
> are rated for. This will be the top speed. As long as the amp rating is not
> exceeded the motors will run fine. This not only makes the whole system more
> efficient, but gives you more rpm on the minn kotas without burning them up.
> This works especially well with brush motors that are oil filled.
>
>
>
> Upper limit on DC systems in subs from a safety standpoint is about 50 V.
>
>
>
> Greg
>
>
>
>
>
> _____
>
> From: owner-personal_submersibles@psubs.org
> [mailto:owner-personal_submersibles@psubs.org] On Behalf Of James Frankland
> Sent: Wednesday, June 13, 2012 9:21 AM
> To: personal_submersibles@psubs.org
> Subject: [PSUBS-MAILIST] 12 or 24v ?
>
>
>
>
>
> Hi All,
>
>
>
> Does anyone have any thoughts on this?
>
>
>
> My motors are 24V minn kotas. Do you think i should pass 12v through the
> pods and link them up 24v inside? Or link them up 24v inside and bring that
> through?
>
>
>
> 12v seems easier and i can run 12v things inside, but less efficient and
> might produce more heat on the penetrators.
>
>
>
> 24v more efficient and easier on the penetrator but i'll need a transformer
> inside to run 12v equipment.
>
>
>
> Ive no idea what the penetrators run at.
>
>
>
> Any thoughts?
>
>
>
> Many thanks
>
> James
>
>
>
--
Mailed on 25-Jun-2012.
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