Search found 286 matches

by pf26
27 Sep 2017, 09:21
Forum: FOC
Topic: FOC poor efficiency at high speed
Replies: 20
Views: 2965

Re: FOC poor efficiency at high speed

Playing with relatively low currents at high speed is difficult for the VESC. I fear you need to change the shunts to higher values like 5mOhms if you want reliable high speed FOC. If you have a look at the current samples using BLDC tools, you probably will see it isn't very clean. Higher loads wou...
by pf26
26 Sep 2017, 11:37
Forum: General
Topic: Strange behaviour on Regen mode
Replies: 10
Views: 1792

Re: Strange behaviour on Regen mode

You may want to have a look at the recorded faults in the VESC, causing it to halt. After a fault, use BLDC-tools and in the terminal window, type faults.
by pf26
22 Sep 2017, 18:29
Forum: General
Topic: SPI or ABI?
Replies: 2
Views: 842

Re: SPI or ABI?

Assuming your signals have the same strenght with regards to noise, SPI may give better results since a wrong transmission will be corrected by the next one, while the A/B interference will be cumulated until next I index position reference. But the SPI wrong transmission can be very wrong (if the m...
by pf26
21 Sep 2017, 08:37
Forum: General
Topic: [Solved] Wondering about quadrature encoder connection
Replies: 10
Views: 1081

Re: Wondering about quadrature encoder connection

Yes, FOC requires to know precisely the absolute position of the rotor, so it can create in the stator the magnetic field corresponding to the highest possible torque. Therefore the I signal is required for absolute reference. If you do not need absolute positions from the encoder, then the A/B sign...
by pf26
20 Sep 2017, 18:31
Forum: General
Topic: [Solved] Wondering about quadrature encoder connection
Replies: 10
Views: 1081

Re: Wondering about quadrature encoder connection

The index I signal gives the absolute 0 position of the encoder, there is just one such position where I is active on each turn. From there A/B simply count up/down depending on quadrature. Yes, the VESC needs the I signal, and will wait for it before it can actually use the encoder. Could you pleas...
by pf26
19 Sep 2017, 15:50
Forum: General
Topic: Watt Control Via Duty Cycle Control?
Replies: 14
Views: 1433

Re: Watt Control Via Duty Cycle Control?

I guess you won't stay long at 4.2 Volts, and not at 3.2 Volts either. I may even be cool to warn the user by decreasing the available power when the battery goes low. Anyway, if this is unacceptable for you.. With an open source code, and so much CPU ressources, nearly everything is possible.
by pf26
19 Sep 2017, 15:43
Forum: General
Topic: BLDC Tool Realtime Data to Excel File
Replies: 4
Views: 649

Re: BLDC Tool Realtime Data to Excel File

Writing to an SD Card requires a lot of RAM because you need a data buffer before you actually write pages of data into the SD-Card. Most likely it will be difficult to reduce this RAM usage. Depending upon the measurements you need, you might simply configure the VESC to output its status say at 10...
by pf26
19 Sep 2017, 12:25
Forum: General
Topic: Watt Control Via Duty Cycle Control?
Replies: 14
Views: 1433

Re: Watt Control Via Duty Cycle Control?

Watt control from the battery is already implemented, since you can configure a limitting max battery current, and the battery voltage should be very stable. If you give enough throttle, the duty cycle and motor current will be determined by the max battery current, ie watt-control. It might be inte...
by pf26
18 Sep 2017, 13:22
Forum: General
Topic: Watt Control Via Duty Cycle Control?
Replies: 14
Views: 1433

Re: Watt Control Via Duty Cycle Control?

With A= 10A = Battery Amps, B= 50A = Motor Amps, C= 20% = Duty Cycle, D= 5V = Present Back Emf V, E= 10V = Effective PWM Voltage F= 0.1ohm = Winding Resistance, G= 50V = Pack Voltage, H= 500W = Desired Wattage, I= 100kv = Motor KV, J= 500rpm = Present RPM It seems like half of your 500W is lost in t...
by pf26
17 Sep 2017, 09:33
Forum: VESC Projects
Topic: MiVESC - smaller version of VESC 6
Replies: 6
Views: 2003

Re: MiVESC - smaller version of VESC 6

Did you consider to monitor the Fets Vds instead of using shunts as done here: http://www.ti.com/tool/TIDA-00774?jktype=design
Maybe not linear enough for sensorless FOC though. But so much saved space..

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