Search found 301 matches

by peters
Jul 02 2020 4:06am
Forum: Motor Technology
Topic: low inductance output stage contruction
Replies: 161
Views: 23295

Re: low inductance output stage contruction

From the graph the ESL of this cap is probably between 10 and 15nH, that could be reduced with more parallel capacitors. Measure the DC bus voltage with the scope at the capacitor, there should be no or only a small ringing, then you'll see if more or bigger caps are needed. The loop inductance and ...
by peters
Jul 02 2020 12:01am
Forum: Motor Technology
Topic: low inductance output stage contruction
Replies: 161
Views: 23295

Re: low inductance output stage contruction

Hello. I had a lot problems with my earlier setup. So I tried setup with copper plates and here are results. Also I have huge ringing. Turn on and turn off resistance is same 12R. Power supply is battery 12V and 24V. Configuration half bridge, motor connected between ground and common node D-S. Fet...
by peters
Jun 21 2020 4:56am
Forum: Motor Technology
Topic: I designed a +200A powerstage with 200V MOSFETs
Replies: 22
Views: 1051

Re: I designed a +200A powerstage with 200V MOSFETs

Nice design, congrats! Great info on thermal tests, too, but I'm wondering something: In the datasheet the junction to case thermal resistance is 0.29 C/W. As in all test configs the case temp was 70C, then the junction temp would be different: first case: 70C + 92W*0.29C/W = 96.68C last case: 70C +...
by peters
May 28 2020 5:53am
Forum: Motor Technology
Topic: 5 Lines of Code to spin BLDC?!? On Youtube.
Replies: 5
Views: 250

Re: 5 Lines of Code to spin BLDC?!? On Youtube.

Looks like he just sets the pwm duty cycles (phase voltages) from lookup tables indexed by the position read from the encoder. It's normal that it spins the motor but it's not a fine method. There is no phase current control or current limit and the efficiency is not optimal. Some cheap and obsolete...
by peters
Apr 10 2020 1:49am
Forum: Motor Technology
Topic: Surron Motor tuning with datalogs! FOC experts needed
Replies: 5
Views: 347

Re: Surron Motor tuning with datalogs! FOC experts needed

I see what you mean but can't explain. You'd expect a flat horizontal section on the battery current (and power) curve after the peak, that would be a range where the peak batt current setting limits the acceleration, and the fall off would be only at higher RPM. The positive bump on the FOC Id grap...
by peters
Apr 01 2020 2:36am
Forum: Motor Technology
Topic: FEMM Simulation Help
Replies: 4
Views: 148

Re: FEMM Simulation Help

I don't know this software, but the flux lines should pass the coils vertically and return on the adjacent coil, as on figure 1 here:
https://www.mdpi.com/1996-1073/10/10/1492
You may just need to reverse the polarity of the magnets on one side.
by peters
Mar 25 2020 11:56am
Forum: Motor Technology
Topic: Ceramic Capacitor, adding some to controller DC rail
Replies: 44
Views: 4790

Re: Ceramic Capacitor, adding some to controller DC rail

10nF is more than what I guessed, but can still be normal as the voltage rise and fall times limit the power dissipated on the cap ESR.
About sevcon I don't know anything.
by peters
Mar 25 2020 6:13am
Forum: Motor Technology
Topic: Ceramic Capacitor, adding some to controller DC rail
Replies: 44
Views: 4790

Re: Ceramic Capacitor, adding some to controller DC rail

No, there are many different gate driver chips, this one is an IR2106S. It is not isolated so the first phase short may have damaged several other components also. But this chip is a low output current one, I'm not sure it drives the 10 parallel mosfets directly. Hard to give a good advice at this p...
by peters
Mar 24 2020 2:36am
Forum: Motor Technology
Topic: Ceramic Capacitor, adding some to controller DC rail
Replies: 44
Views: 4790

Re: Ceramic Capacitor, adding some to controller DC rail

These caps only reduce the EM emission, not protect the FETs, but should all be the same value, otherwise there is probably oscillation between the parallel FETs. But this oscillation shouldn't kill the FETs anyway. High voltage caps are needed, as madin said, not from a drone. There may also be gat...
by peters
Mar 22 2020 12:20am
Forum: Motor Technology
Topic: Ceramic Capacitor, adding some to controller DC rail
Replies: 44
Views: 4790

Re: Ceramic Capacitor, adding some to controller DC rail

Could hall sensor error cause mosfets to explode? Not really. Overcurrent or overvoltage (either Vgs or Vds) or overheating can kill the mosfets. Maybe there is a short-circuit somewhere on the board or on the cables. What happened exactly? Did you replace the 45 mosfets and they were all or some o...
by peters
Mar 11 2020 8:40am
Forum: Motor Technology
Topic: Ceramic Capacitor, adding some to controller DC rail
Replies: 44
Views: 4790

Re: Ceramic Capacitor, adding some to controller DC rail

Usually there is no capacitor in that position, but it mitigates the HF ringing amplitude and frequency that happens with low-Coss MOSFETs (that IPP120N20NFD is - if it's the part number). The value is definitely lower than a few nF, most likely 1nF, but may be even lower than that. Better to measur...
by peters
Mar 08 2020 1:50pm
Forum: Motor Technology
Topic: Does adding more cap to the DC bus on a controller help? Look in here for the answer.
Replies: 10
Views: 809

Re: Does adding more cap to the DC bus on a controller help? Look in here for the answer.

yeah, I also made tests with RCD snubbers and also can say the overshoots are minimal compared to the cap-only design, but I didn't fully work that out, stayed with caps only. For me the SMD ceramic caps work when they are placed just between the high and low side FETs, so they shunt a part of the D...
by peters
Mar 06 2020 1:32pm
Forum: EV Business World
Topic: Do you know this man ?
Replies: 25
Views: 2790

Re: Do you know this man ?

So... are you sceptical or what I said is obvious since the 1960's? :lol:
by peters
Mar 06 2020 3:48am
Forum: EV Business World
Topic: Do you know this man ?
Replies: 25
Views: 2790

Re: Do you know this man ?

Yes, that has been the expectation ever since the first commercial “microchip” in the 1960’s...!!! But it doesn't mean it won't happen. Some sci-fi topics are very unlikely, like time machines or even traveling to other stars, because there is no realistic idea to do them, but real intelligence and...
by peters
Mar 05 2020 5:16am
Forum: Motor Technology
Topic: What's so bad about low impedence?
Replies: 30
Views: 1587

Re: What's so bad about low impedence?

You can try to add serial inductors on the phase wires if the motor inductance is too low for the controller. Should be air-cored, because ferrite cores would be too heavy or go into saturation, probably at least 10uH, thick phase wires winded on plastic tubes, and avoid coupling between them. Here ...
by peters
Mar 05 2020 4:08am
Forum: EV Business World
Topic: Do you know this man ?
Replies: 25
Views: 2790

Re: Do you know this man ?

It's not that yet. :)
Will take a few decades at least, but machines will eventually outgrow us in all intellectual skills, and it seems inevitable.
by peters
Mar 04 2020 7:56am
Forum: EV Business World
Topic: Do you know this man ?
Replies: 25
Views: 2790

Re: Do you know this man ?

efMX Trials Electric Freeride wrote:
Feb 29 2020 11:06am
seems a good investment to throw their $$$ at the future.. kids and food are (in) the future right??
the world population is growing, but I'd bet more on conscious robots and electricity...
by peters
Mar 04 2020 12:31am
Forum: Motor Technology
Topic: Lebowski controller IC 2.B0 source code and (short) explanation
Replies: 36
Views: 2321

Re: Lebowski controller IC 2.A1 source code and (short) explanation

Very interesting, thanks for sharing.
On the loopfilter block diagram the two outputs of the multiplier (rotator) are the imaginary and the real parts? Imaginary is used to obtain omega/phi and real for Vr?
by peters
Feb 01 2020 11:29am
Forum: Motor Technology
Topic: Cheap FOCer 2 (Open-source, Low-cost, VESC 6 based ESC) (v0.9 release! Beta testing still ongoing)
Replies: 49
Views: 7660

Re: Cheap FOCer 2 (Open-source, Low-cost, VESC 6 based ESC) (Prototyped. Materials have arrived for a test batch)

Very nice waveforms, indeed! The overshoot (spike) at turn-off is absolutely normal, because the current changes from 50A to 0 during that time and the overshoot voltage above the DCbus is L*di/dt. L is the output loop inductance that is an inherent attribute of the circuit. In fact the area under t...
by peters
Jan 11 2020 2:34am
Forum: Motor Technology
Topic: Serious FOCer (84V VESC 6 based controller)
Replies: 266
Views: 37365

Re: Serious FOCer (84V VESC 6 based controller)

I'm pretty sure it's due to the long gate drive traces passing from the control board to the power stage thought the pin headers. That's very likely, I also measured that the gate and output waveforms depend on the connector position and orientation, because there is a coupled feedback from the out...
by peters
Jan 10 2020 10:12am
Forum: Motor Technology
Topic: Serious FOCer (84V VESC 6 based controller)
Replies: 266
Views: 37365

Re: Serious FOCer (84V VESC 6 based controller)

Can you describe the issue in details? Do you think it's the power PCB layout or coupling between the stacked boards? I made a few similar boards for testing in the past few years and I know there are issues with the stacked structure but those are mostly manageable, although basically better to pre...
by peters
Jan 08 2020 2:25am
Forum: Motor Technology
Topic: Why more KV = more power, the Maximum Power Transfer Theorem
Replies: 51
Views: 4106

Re: Why more KV = more power, the Maximum Power Transfer Theorem

Yes for sure we don't want to stall a powerful motor with the battery voltage connected to it, but you can do that with small RC motors. But the theory of operation for only the motors (without controller) is the same. If you add the controller, that will limit the current to the allowed maximum by ...
by peters
Jan 07 2020 5:48pm
Forum: Motor Technology
Topic: Why more KV = more power, the Maximum Power Transfer Theorem
Replies: 51
Views: 4106

Re: Why more KV = more power, the Maximum Power Transfer Theorem

Nope, that’s still not clear. BEMF is not performing shaft work, and it’s not doing electrical work as it’s not driving current. Noooo, BEMF produces the real power with the current component that is in phase with BEMF. In the motor model the BEMF is a voltage source in series with the phase induct...
by peters
Jan 06 2020 6:01am
Forum: Motor Technology
Topic: Winding Question: does STAR make more torque than DELTA, even with adjusted phase current?
Replies: 18
Views: 1774

Re: Winding Question: does STAR make more torque than DELTA, even with adjusted phase current?

No, it doesn’t as the torque per amps drop off on saturation. The calculated current to drive the delta motor is based on that neither of the cores saturate as that stops the (semi) linear relationship between current and torque. I agree that torque per amps drops off, but the torque itself is the ...
by peters
Jan 06 2020 3:39am
Forum: Motor Technology
Topic: Winding Question: does STAR make more torque than DELTA, even with adjusted phase current?
Replies: 18
Views: 1774

Re: Winding Question: does STAR make more torque than DELTA, even with adjusted phase current?

I think it's not a saturation issue because a saturated winding produces more magnetic field and so should produce more torque than the same winding not in saturation regardless of the winding config (wye-delta), if the hall sensor vs. phase current position is adjusted (I mean the 30 degrees differ...