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by rew
06 Jan 2018, 18:13
Forum: Hardware Problems
Topic: DRV fault code on FOC detection
Replies: 9
Views: 2602

Re: DRV fault code on FOC detection

That pulldown resistor is connected like that due to layout issues. Where it is connected now is connected to the "normal" place through one or two 0.001 ohm resistors. So the resistor still does its work, but at 0.002 ohms more resistance. With the DRV, you can DISABLE the FET outputs. In...
by rew
06 Jan 2018, 18:04
Forum: FOC
Topic: Technological choice alternatives
Replies: 1
Views: 460

Re: Technological choice alternatives

- As you don't use the built in current sense from the DRV8302, do you think it is a mistake to deal with regular mosfet driver ? Yes, my variant of the VESC uses just normal LM5109 or IR2xxx FET drivers. The VESC started out with "guidelines" from TI which said: you need only two current...
by rew
23 Dec 2017, 23:52
Forum: Custom Applications
Topic: VESC4X
Replies: 3
Views: 705

Re: VESC4X

The STM32F412 does not have the 3 ADC modules that the VESC uses.
by rew
23 Dec 2017, 23:48
Forum: Custom Applications
Topic: VESC for VR treadmill
Replies: 4
Views: 880

Re: VESC for VR treadmill

You do NOT want to tell both motors to do the same speed. Any minor error will cause the motors to fight each other. With PWM control, you get a slightly better situation. The effective resistance of the motors will allow them to adjust a bit to small errors. Still it is quite possible that one moto...
by rew
23 Dec 2017, 23:42
Forum: General
Topic: Improve cooling
Replies: 10
Views: 2648

Re: Improve cooling

Looks nice, but read my posting from 15 months ago: You are not effectively cooling the mosfets. any heat generated inside the mosfet has to travel through the 10x higher thermal resistance to the outside of the FET.
by rew
05 Dec 2017, 21:46
Forum: General
Topic: Failsafe shutdown of VESC
Replies: 4
Views: 896

Re: Failsafe shutdown of VESC

I asked TI about providing the PVDD externally. They answered! The response: DO NOT DO THAT! That might be (and probably is) just CYA policy, but that's the official word.... (I use a DCDC converter in an application. The datasheet says: "min load: 10% of max load". In my application the l...
by rew
02 Dec 2017, 20:30
Forum: VESC Projects
Topic: VESC in homemade lathe/drill press
Replies: 11
Views: 2222

Re: VESC in homemade lathe/drill press

Yes. The torque constant is actually the same as the motor constant Kv. Or depending on the units the inverse (*). 245Kv is 245 RPM / Volt = 245 (RPM/V) / 60(sec/min) * 2*pi (rad/rotation) = 25 rad/sec/V That means the torque constant is 1 over that, or 0.04 Nm/a. So for 40A you get: torque = 0.04 N...
by rew
02 Dec 2017, 19:49
Forum: General
Topic: Failsafe shutdown of VESC
Replies: 4
Views: 896

Re: Failsafe shutdown of VESC

I have had my lab powersupply backfed from braking the motor. Once with the powersupply at its max and a few times less agressive with some margin on the powersupply. But yes, the VESC will remain powered even if it cannot drive the fets as long as the motor turns....
by rew
02 Dec 2017, 19:26
Forum: General
Topic: 180 degree commutation with sensors vs standard 120
Replies: 13
Views: 2363

Re: 180 degree commutation with sensors vs standard 120

No, From what I read above, the "180 deg commutation" is simply BLDC but with an extra motor coil powered up. (Y or Delta does not matter). But if we think about what we want to achieve.... We have a permanent magnet in an electromagnetic field. We want to set up that magnetic field that h...
by rew
25 Nov 2017, 11:38
Forum: FOC
Topic: Formulas of Ki, Kp, observer gain
Replies: 3
Views: 813

Re: Formulas of Ki, Kp, observer gain

Nathan wrote:have very high inductivity - 12000mH.

That is VERY high. So if we apply 12V, after about a second the current will have risen to 1A. So more than about 20 - 30 RPM is imposible with this motor. Are you sure?

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