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by pf26
16 Sep 2018, 07:35
Forum: Custom Applications
Topic: Diver propulsion vehicle (dpv) prototype
Replies: 1
Views: 64

Re: Diver propulsion vehicle (dpv) prototype

NTC: 10K (try to keep the same characteristics as the one used on the VESC PCB)
magnetic rotor (24p) : -> ERPM = 24/2 * RPM (assuming p is poles, not polepairs.) Quite easy to check anyways, for instance, there are free Strobe apps for Android phones, like Strobly...
by pf26
16 Sep 2018, 07:30
Forum: General
Topic: Braking in speed PID mode
Replies: 3
Views: 131

Re: Braking in speed PID mode

Running FOC or BLDC ?
Possibly, in the second example, the motor turns very slowly (smaller duty cycle), and braking is achieved by shorting the motor (no current IN) ?
by pf26
06 Sep 2018, 09:00
Forum: FOC
Topic: FOC settings configuration
Replies: 6
Views: 365

Re: FOC settings configuration

I think this motor is wound with many turns, so it requires relatively high voltage/low amp (someting like 30V-10Amps for 300W output near top speed). The original VESC works better in FOC mode for higher amps. I fear it is necessary to increase the Shunts (quadruple ?) and the firmware accordingly,...
by pf26
04 Sep 2018, 17:58
Forum: FOC
Topic: FOC settings configuration
Replies: 6
Views: 365

Re: FOC settings configuration

Your measured inductance seems surprinsingly low to me. Do you have more info on the motor ? When run in BLDC in full load, how many Volt/Amps do you use ? Possibly your Vesc has a faulty current measurement (which does not affect the BLDC mode too much). You could check the Current samples. Or try ...
by pf26
28 Aug 2018, 12:54
Forum: General
Topic: Stop always at same position?
Replies: 2
Views: 379

Re: Stop always at same position?

You can (nearly) do whatever you want wit ha customs app. There is a little bit of thinking precisely how you would want the speed ramp and slightly adjust the ramp to make sure the motor will stop where you want (I assume a dedicated position within one or more turns). An encoder will make it simpl...
by pf26
20 Aug 2018, 09:37
Forum: FOC
Topic: FOC RPM control keeps reversing direction
Replies: 7
Views: 3145

Re: FOC RPM control keeps reversing direction

I think the speed control based on motor current is very hard to achieve with a PID, especially when your motor has strong load variations and little inertia. The strong currents required for high loading will cause very high acceleration should the load cease. A voltage based speed regulation is mu...
by pf26
16 Aug 2018, 12:09
Forum: FOC
Topic: FOC settings configuration
Replies: 6
Views: 365

Re: FOC settings configuration

With a 1amp current, I fear you have too much noise in the measurements, so the results are unreliable.
You probably should try with the higher current that still gives a result for lambda.
What are the values found for R and L ? Do they seem to correspond to your motor specs ?
by pf26
23 Jul 2018, 08:48
Forum: FOC
Topic: Direct CAN velocity control
Replies: 3
Views: 398

Re: Direct CAN velocity control

Having CAN signals through sliprings seems a bit scary to me for long term reliability.. I would have used sliprings for power, and wireless (802.15.4) for control. If you use CAN through sliprings, maybe using some small capacitors (47pF ?) between 0V and both CANH and CANL, can help filter the pos...
by pf26
15 Jul 2018, 16:06
Forum: Related Hardware
Topic: Battery overvoltage protection - dump load
Replies: 14
Views: 1353

Re: Battery overvoltage protection - dumb load

Did you have a look at this one: http://vedder.se/forums/viewtopic.php?f=15&t=586 ? (dump, not dumb..)
by pf26
12 Jul 2018, 14:38
Forum: Related Hardware
Topic: Battery overvoltage protection - dump load
Replies: 14
Views: 1353

Re: Battery overvoltage protection - dumb load

I doubt you scheme will work. When the dump load is switched on, the internal resistance of the battery will cause the main voltage to drop, and depending upon the hysteresis of your comparator, will switch off the load or not. Anyway, you need some capacitance somewhere to have your dump load switc...

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