Author Topic: Controller running hot? What is considered normal temprature  (Read 1192 times)

Offline Pontus

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Controller running hot? What is considered normal temprature
« on: August 16, 2023, 08:19:06 AM »
I have the following setup.
  • Fin keeld sail boat @ 4 Tonnes
  • 10 kW water cooled BLDC motor @ 48 V mounted directly to propeller shaft (no reduction gears)
  • VEC500 cooled using 4 aluminum cooling blocks in parallel
  • Motor speed set to max 1500 rpm using the PI-800 software

I've deliberately designed my setup without reduction gears to reduce noise and mechanical losses but keeping it in mind that I might need to add a reduction pulley system later on.

When running the engine at about 3.5 - 4 kW for half an hour the base plate of the controller is about 75 °C, the phase connector studs and wires a bit more. The motor itself is only lukewarm; 30 - 35 °C.

It's a given that electrical components in general and motors in particular should be kept as cool as possible. Therefore the temp settings in the PI-800 seems rather hot to me (120, 130 and 150 °C) and I'm not even sure if that's for the motor or the controller even if it says motor temp in the program I don't know of any temp sensor in the motor connected to the controller.


What is considered TO hot?
Is there any temp throttling built in in the controller?

Follow along my electric conversion of a 4 ton Danish sail boat. Grinde 19

Offline Pontus

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Re: Controller running hot? What is considered normal temprature
« Reply #1 on: August 17, 2023, 08:31:37 PM »
I just got reply from the reseller who wrote the following, which might be of interest to others as well.

Quote
the controller temperature is a little high, control it below 65 degrees is better.
It's better to install a cooling system.
Follow along my electric conversion of a 4 ton Danish sail boat. Grinde 19

Offline Bikemad

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Re: Controller running hot? What is considered normal temprature
« Reply #2 on: August 18, 2023, 10:35:12 AM »
The temperature settings in the software relate to the motor's temperature, which the controller monitors using the internal thyristor that produces a variable resistance (measured between the Black and White leads on the Hall sensor connector) dependant upon the temperature of the stator windings.
I expect that the stator windings insulation and the motor's hall sensors are able to withstand the maximum temperature of 150?C, as the motor should cut out completely when this temperature is reached.

I would expect the controller (and the motor) to run much cooler with a 2:1 gear reduction, as the motor would then be outputting half the torque to provide the same speed and torque output at the propeller.
Reducing the torque should also reduce the current being drawn by the motor, which means a lot less strain on the controller and therefore less unwanted heat being generated.
A 2:1 gear reduction would also reduce the load on the battery, which should result in a noticeable increase in the motor run time and therefore range.
If you motor was only drawing half the Amps to maintain your current cruising speed, your boat should be able to go twice as far as it currently can.
A 2:1 toothed belt drive reduction is unlikely to make a huge difference to the noise output and the mechanical losses would be minimal compared to the increase in overall efficiency.

The VEC controllers should have internal thermal protection, as page 5 of the controller guide lists an 11 blink fault code for "Controller over-heat protection" which would be triggered "When controller operation temperature is higher than default value", but it doesn't say what the default value is.  ::)

Alan
 

Offline Pontus

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Re: Controller running hot? What is considered normal temprature
« Reply #3 on: August 20, 2023, 08:24:07 PM »
Thank you Bikemad for your comments.

During the design of my boat transmission this was a bit of a gamble, if it works it works. But I have made the design with a belt reduction in mind, saving space to accommodate that, if needed, at a later stage.

As for the cooling of the controller, I still have quite a bit of room for improvement, which I think will take me down below 65 °C. But this is most probably only a fix for this season. Since the controller is where almost all the heat is generated I'm not really sure of how to set up this the most effective way. Right now both the motor and the controller are cooled in parallel by the same water, which means that the motor acts as a cooler for the controller, since it's not nearly as warm. A second loop is an option but it feels a bit complex to have two separate loops, with pumps, pipes, radiator, coolant overflow tank etc. etc.

Regarding the reduction I've come to the same conclusion, although I will probably aim for an even more aggressive reduction of 1:3.
Follow along my electric conversion of a 4 ton Danish sail boat. Grinde 19

Offline Bikemad

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Re: Controller running hot? What is considered normal temprature
« Reply #4 on: August 21, 2023, 05:26:43 PM »
Regarding the reduction I've come to the same conclusion, although I will probably aim for an even more aggressive reduction of 1:3.

I think 3:1 reduction might be too much, as your motor would then only be able to produce ~2kW of power @ 4,500rpm (1,500 propeller speed).
according to the Dynamometer figures, the motor would need to be loaded below ~3,500 rpm to enable it to produce ~10kW of output power.

Alan
 

Offline Pontus

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Re: Controller running hot? What is considered normal temprature
« Reply #5 on: August 22, 2023, 07:53:15 AM »
Thank your for pointing that out Alan, that's much appreciated!

I'm currently using a 3-bladed 14" X 10" which gives a rpm about 1300 for our boat, so somewhere between 1:2,7 to 1:2,5 seems to be a good ratio.
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Offline Bikemad

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Re: Controller running hot? What is considered normal temprature
« Reply #6 on: August 22, 2023, 11:58:34 AM »
You might find this pulley/belt calculator useful but it looks like it may be more suitable for "V" belts than toothed belts.

This calculator seems better suited to toothed belts but I suspect your setup will require heavier duty pulleys than a robot uses.

A YouTube video showing most of the different toothed belt attributes can be found here.

Hopefully, some of this will be helpful.

Alan