Endless Sphere

Hm I don't know, 120kHz bandwitdth for the ACS parts seem good enough to me. 100k-erpm translates to 1.6 kHz, a pole at 120kHz would give a phase rotation of less than 1 degree. Cycle time of the algorithm is in the order of 30usec, so 4 usec delay in the current sensor doesn't seem relevant.

I would do 70% of max controller phase current. If it is a good controller it will probably not hit that level but back off earlier for other reasons...

But no reason not to start low and try anfew runs upping the field weakening, just dont expect impressive results before hitting the 70% mark.

I prefer proper current (magnetic field based) over resistive ones for the simple reason that if you want to keep the power dissipation the same, the higher the current rating of the resistor the lower the effective voltage you'll get. A 1W sense resistor for 1A can deliver 1V signal, a 1W for 1000A...

If you can set fieldweakening current, set it to 70% of max phase current.

Phase inductance should be different depending on rotor position. If that's enough info, and "easily" measurable, to know the exact rotor position, it's another story. Maybe it's also possible to use a phase to induce current into another phase and from that get position information. I imagine the ...

My goal is to have something which can sense the correct phase even when the motor is (mechanically) locked, so that the motor can provide torque in the correct direction against the mechanical lock. So no cheating by having a necessary small bit of movement to try and figure out which way we're goi...

lizardmech wrote: ↑

May 14, 2018 5:11 am

are you keep it secret in the hope of commercializing it or something?

yes

basically the circuit is a lowpass filter. With the VESC it allows you to filter out the PWM and see the sinusoidal content of the output.... though it should look more trapezoidal than sinusoidal. You need the motor parameters to calculate the correct timing advance for FOC. But mine does not need ...

Filtering and amplification... basically compensating for the ADC being only 10 bits

Tja, I don't really know what TI does with Instaspin. If you have a schematic somewhere I'd be interested to have a look... What I have seen somewhere (but this is not FOC or rotor position detection at standstill) is that they integrate the phase voltages to get motor flux (as voltage is the deriva...

would your sensorless start improvments help with "regular" sensored start in some way as well? even though the controller/software now (since last autumn's update with hall data integration in sensorless mode) works better than ever, there is still some improvment possible in the (sensored) start ...

Sensorless torque at standstill, unfortunately direction is still random and can change when switching on/off, so that will be the next thing to work on

nice thing of a bigger chip is larger RAM (8kB, wow :shock: ) so I can sample real-time data and have a look at signal spectra: (this is a complex spectrum with two notch filters implemented, one at DC and one at a negative frequency) real time datalogging-800x800.jpg It was a real #$%@ though to ge...

Making the controller parameters motor independent is no big deal, and it (well, mine) doesnt need to know motor inertia.... Ah sorry I should have clarified, not motor inertia but the overall total vehicle inertia. At least the way that ASI has written their sensorless self start firmware it runs ...

It is actually possible to get absolute phase information (so including north/south) and without pulsing etc... but this signal almost disappears the moment you apply phase current so cannot be counted on as a reliable and ever present source of info... Still trying to find a workaround, will just t...

Since whereswally606 asked in a PM about the sensorless start with full torque Iam working on, might as well post the status here: I am at a point where I have a one-shot algoritm to get the double phase out. So the controller IC takes just one look (it does not need multiple, but filtering multiple...

Making the controller parameters motor independent is no big deal, and it (well, mine) doesnt need to know motor inertia....

Yep, R18-23 for 4468's should be 4.7 Ohm, R12-17 should be 15 Ohm. R1, I dont know the value of this one yet, it is a filter resistor for the processor board supply. Ive been using 100 Ohm so far, but shorting it out should be ok too. Plan is to drop around 5V across this resistor, assuming the powe...

Busy with some extremely interesting stuff. DSC02111-800x800.jpg I've started programming on a different chip, one of the 33EV types. Goal is to have sensorless start with full torque at standstill. Relative (sensorless) position at standstill is quite easy, but to get absolute phase information req...

Did you just solder them ? You should be getting the correct values... did you add the pull up resistor ?

Did the chip correctly find two temp sensors ? Does it display the two identification codes ?

P.s. and its recommended to update the firmware to 2.A1

Just be meticulous and building the board should pose no problems. I would however add copper wire to the high current traces. Solder basically has about 10 times the resistance of the equivalent area of copper. So you need 10mm^2 of solder (a 2 mm thick layer on 5 mm wide traces) to get the equival...

Make sure you get the correct gate resistors for the Fet you are using.

Also, leave some room between Fets and PCB, this make it easier to replace a broken FET and for fattening uo the traces.

Something that will help reduce the noise in drive_3 is to reduce this coefficient: n) immediate motor phase step: 48 in the control loop coefficients menu. You can set this coefficient all the way down to 0, but it may (or not) cause instability. I am not 100% sure this coefficient is absolutely ne...