[PSUBS-MAILIST] PLC Choice

Sun Mar 11 22:11:33 EDT 2018

Hi Alan,
Thanks for all that.  I'm not oil filling, so that helps with most things,
although getting rid of heat is a headache.  The (ambient) housing of the
DPV is all plastic, so I'm going to have to implement a water cooling
system, at least for the prototype.  The motor isn't designed for water
cooling, so it will be a bit more annoying.  Might look at a proper water
cooled motor next.

Since I'm retrofitting the motor & controller to the DPV, it's rather nice
that I don't have to worry about other variables like modifying the motor.
The prop/shaft/seal assembly terminates on the inside with a large gear, so
I "just" had to make an adaptor bracket for the motor and a 3D printed
shaft coupler.

I imagine you're across it, but are you checking on efficiency in your prop
experiments?  (as in, mechanical power out, over electrical power in).
This can be calculated indirectly and it's really interesting to see how
badly a motor can be performing despite a high input power.  I thought I
was doing well with an undersized 70Kv motor apparently rated for 2.8kW
until I realised it was only operating at 30% efficiency (80-90% should be
quite achieveable).  The attached spreadsheet (warts and all) that I made
may be of interest.  Not sure how it translates to oil-filled - probably ok
if you use the figures from before it's filled with oil.

Cheers,
Steve

On Mon, Mar 12, 2018 at 12:48 PM, Alan via Personal_Submersibles <
personal_submersibles at psubs.org> wrote:

> Steve,
> some information in case it helps.
> you might have heard some of this from me before, but I have been oil
> filling
> the thrusters. I started with the Saite motors but a few things went wrong
> that were possibly my fault.
>    Firstly I didn't have an oil compensator to create an over-pressure &
> the
> oil was moving up the wiring tube when I started the motor. Possibly the
> motor design was creating force that was doing this, or centrifigal
> force inside the motor was throwing the oil out.
> The oil I was using was degrading the main wire insulations & I suspect
> dissolved the glue on the sensor board. They glue the sensor board at Saite
> with a glue that can be melted so you can adjust the timing of the motor.
>    I suspect the timing went out & it overheated, or it overheated first &
> caused the sensor board to come loose. It stopped running after
> 30 hrs.
>    I had replaced the propellor shaft with a 316 shaft that I turned down
> so that I had
> 12mm to fit the prop & 8mm through the motor. I didn't pay enough attention
> to getting the press fit right. The whole bell is attached at that one
> press fit
> point. I think I should have heated up the bell a bit & frozen the shaft &
> pressed it in a press, however would need to be weary of splitting the
> aluminium.
> The result of the not so tight fit was the bell moving off centre in time,
> this seemed
> ok when running at speed but would scrape at slow speeds. I had looked
> around
> for a suitable motor with a can bearings like the Turnigy 6374 but not
> sure if
> this is necessary.
>    Tested it out with a 2hp yamaha prop & was getting as good as or better
> thrust
> than the average thruster that I had information on was achieving. Have a
> number
> of props to try out.
>    Next step is to build another thruster housing for the Maytech motor,
> make a new
> test jig & order a plc to control the tests.
>    One reservation about the Maytech motor is I may have to drill angled
> holes
> in the end of the bell to cause an oil flow across the windings, or add a
> small
> impeller to do the same.
> Are you oil filling?
> Cheers Alan
>
>
> Sent from my iPad
>
> On 12/03/2018, at 1:36 PM, Stephen Fordyce via Personal_Submersibles <
> personal_submersibles at psubs.org> wrote:
>
> Hi Alan,
> Hah!  That's the same motor that I ordered - should have checked with you
> first (1 @ 60Kv and another at 70Kv).
>
> Yes I'm a big fan of the temperature sensing, and the sensors are nice for
> FOC control (quieter at slow speeds).
>
> Cheers,
> Steve
>
> On Sun, Mar 11, 2018 at 3:32 PM, Alan via Personal_Submersibles <
> personal_submersibles at psubs.org> wrote:
>
>> Thanks Steve,
>> any information on them is helpful.
>> Perhaps Maytech are putting out the Vesc with heatsink as a result of
>> problems!
>> Not sure if this instigram link works but it is a preview of the Vesc...
>> https://instagram.com/p/Bd2GOBLA1rU/
>> I bought 6 x 6374 sealed sensored outrunner motors off Maytech that I had
>> them wind to 60kv.
>> They have a temperature sensor on the hall sensor board that the Vesc
>> reads, which
>> will be handy for testing. Am running these in oil.
>> They are using these motors on electric surfboards. The wiring isn't as
>> stiff as the "Saite"
>> motors I tried.
>> Cheers Alan
>>
>>
>>
>> Sent from my iPad
>>
>> On 11/03/2018, at 12:48 PM, Stephen Fordyce via Personal_Submersibles <
>> personal_submersibles at psubs.org> wrote:
>>
>> Hi Alan,
>> Yes I looked at the Maytech VESC builds (and have also ordered a BLDC
>> motor sample from them), but the e-skaters do have a few negative things to
>> say about it.  I've been testing a "E-SK8" version I got from Hobbyking and
>> it's been completely fine, but the FOCBox has all round excellent reviews
>> and looks the part - I'd rather pay a bit more for something so critical
>> (and I want to be able to use FOC control too).  Since I'll be on-selling,
>> hopefully I can get much better than list pricing - I'll let you know if
>> I'm doing a bulk order.
>>
>> Cheers,
>> Steve
>>
>>
>>
>> On Sat, Mar 10, 2018 at 1:37 PM, Alan via Personal_Submersibles <
>> personal_submersibles at psubs.org> wrote:
>>
>>> Steve,
>>> thanks thats good to hear.
>>> I bought my Vesc from Maytech in China. They sell them along with a
>>> remote
>>> controller for skateboard use. They look like they have done a good job,
>>> &
>>> if they haven't you'll hear about it from the Skateboarding community.
>>> My Vesc cost about $100- & they are about to release a Vesc with heat
>>> sink
>>> in an aluminium housing.
>>> The Vesc Maytech sent me needed the firmware updating, & then I had to
>>> order
>>> an ST link from them to update the firmware. They sent the wrong wires
>>> with it.
>>> Apart from that, I have been buying bldc motors from them that are good
>>> quality.
>>> Will let you know when they release this & what the price is if you like.
>>> I was looking at the focbox, it looks like they have done a good job
>>> with it.
>>> Cheers Alan
>>>
>>>
>>> Sent from my iPad
>>>
>>> On 10/03/2018, at 10:04 AM, Stephen Fordyce via Personal_Submersibles <
>>> personal_submersibles at psubs.org> wrote:
>>>
>>> Hi Alan,
>>> I've also been using the VESC brushless motor controller (I use the
>>> FOCBOX type, which is sold in Australia) for diver propulsion vehicles and
>>> they are fantastic, with all their diagnostics and open source firmware.
>>> They also can have a Bluetooth module added so everything can be monitored
>>> on a smartphone app (Android).
>>>
>>> Cheers,
>>> Steve
>>>
>>> On 10 Mar 2018 6:23 am, "Alan via Personal_Submersibles" <
>>> personal_submersibles at psubs.org> wrote:
>>>
>>> Cliff, Steve, (mainly)
>>> just an update on where I am with the plc choice.
>>> Even though I had done a plc programming course I was getting totally
>>> bewildered with all the I/Os & what sort of information I could extract
>>> from my motor controller, BMS etc. Have bought a Vesc which is a small
>>> electronic
>>> brushless speed controller that can read rpm, amp draw & temperature
>>> from my
>>> motors. I have over 60 I/Os & most are analogue.
>>> I ended up contacting an electrician specialising in industrial
>>> automation
>>> who is also an electronics geek. He is young enough to be up on all the
>>> latest
>>> technology. He is coming up with all sorts of ways of reducing the I/Os
>>> using
>>> raspberry pi etc.
>>> So glad to leave it in his hands; will see what he comes up with.
>>> Alan
>>>
>>> Sent from my iPad
>>>
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