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by rew
02 Dec 2017, 19:26
Forum: General
Topic: 180 degree commutation with sensors vs standard 120
Replies: 13
Views: 823

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: 259

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?
by rew
20 Nov 2017, 09:15
Forum: General
Topic: Error: read version failed when trying to use OpenOCD 0.7.0 with STM32F407 Discovery Board As Programmer
Replies: 5
Views: 1598

Re: Error: read version failed when trying to use OpenOCD 0.7.0 with STM32F407 Discovery Board As Programmer

The discovery board is a reliable programmer. First try flashing the BLDC firmware into the CPU on the discovery board, then try removing the jumpers and making theconnection to the VESC. So this way you know for sure if it is software you're having trouble with or hardware.
by rew
11 Nov 2017, 09:43
Forum: FOC
Topic: FOC poor efficiency at high speed
Replies: 20
Views: 1906

Re: FOC poor efficiency at high speed

I messed with the switching speed. No real effect. Still craps out around 50% duty cycle. Is there any way to start in FOC and switch to BLDC at a certain RPM?? With the current firmware: Definitively no. Switching from one side to the other in the current setup means that the "other" str...
by rew
11 Nov 2017, 09:38
Forum: General
Topic: "Peak Efficiency" Control Mode?
Replies: 108
Views: 8716

Re: "Peak Efficiency" Control Mode?

[remember in the scenario the customer states his requirements include at least 30mph on flat ground, and greatest range while repeatedly accelerating full throttle in start and stop traffic.] So, your rider is allowed to press full-throttle, but the motor controller will, in the interest of effici...
by rew
03 Nov 2017, 08:03
Forum: General
Topic: Brushless motor stop at 58% of duty cylce
Replies: 4
Views: 435

Re: Brushless motor stop at 58% of duty cylce

No. RPM is linear with duty cycle. Especially at little or no load, or at a load that is proportional to the speed (RPM in this case).
by rew
03 Nov 2017, 08:02
Forum: General
Topic: "Peak Efficiency" Control Mode?
Replies: 108
Views: 8716

Re: "Peak Efficiency" Control Mode?

Devin, your calculations/simulations of a while back show your "max efficiency" method reducing the throttle value at certain points in the trip. Thus the guy riding "your algorithm" will be at work later than the guy riding "full trhottle". I propose adding a third vir...
by rew
29 Oct 2017, 07:21
Forum: Custom Applications
Topic: Long Term Regen
Replies: 4
Views: 428

Re: Long Term Regen

Indeed very interesting! Yes, you'd need some Maximum Power Point algorithm in there. The difficult part is how long you need to wait to get a valid measurement of the new situation. Otherwise, increasing the load will always seem advantageous because you are extracting kinetic energy from the movin...
by rew
28 Oct 2017, 17:34
Forum: Feature Requests
Topic: Reverse
Replies: 2
Views: 363

Re: Reverse

I always recommend that you put the controller closer to the battery when possible. The motor side is already expected to have some inductance (more = better (up to a point)) and resistance. To reduce stray inductance and EMI, I always braid the three wires. This does for three phases what "twi...
by rew
14 Oct 2017, 11:59
Forum: General
Topic: "Peak Efficiency" Control Mode?
Replies: 108
Views: 8716

Re: "Peak Efficiency" Control Mode?

devin wrote:PS How many kg thrust does your electric bicycle put out at 20a motor amps at 5kmh, just for curiosity?

At 20A motor amps, the thrust is (very closely) the same independent of the speed.

By my calculations I have about 80N of thrust with 20A motor current.

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