High Power VESC

Discuss hardware related to the VESC such as the NRF nunchuk.
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TheFallen
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Re: High Power VESC

Postby TheFallen » 02 Feb 2017, 08:57

Okay, so rather than try and fix the PCB, which I'm convinced is haunted, I soldered up a new one.

Image

Despite screwing up the feedback resistors on the +5V_PSU and +3v3_PSU the +12V_PSU worked and I was able to check the gate drive chips. The pin voltages all matched the phase A & phase B pin voltages in the post above. Hopefully I should be able to fix the resistor problems and get it working.

*edit*

And with the resistors changed the power supplies are all nominal.

Image

rew
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Re: High Power VESC

Postby rew » 02 Feb 2017, 18:31

which reminds me: My board has leds for "vmot", 12V, 5V and 3.3V. (not for the 1.2V though, but I've never seen an STM fail to make 1.2V with a proper 3.3V).

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TheFallen
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Re: High Power VESC

Postby TheFallen » 03 Feb 2017, 09:05

This design is literally a VESC v4.12 but the DRV8302 is replaced with 3 UCC27211A and 3 switching power supplies, so I only have an LED on +3V3 as in v4.12 the +3V3 rail is derived from the DRV8302's internal +5V switching regulator. My next version mimics the DRV8302 power topology better.

So in my haste to try it out I loaded the original firmware onto my board, then immediately when to try and drive a motor. Forgetting that I'd made safety modifications to some custom firmware and I should have loaded that instead.

So it exploded.

Image (the hole in IC6 on the right)

Funny that.

It seems that the UCC27211A also took out the STM32F as it exploded so back to the soldering bench.

lizardmech
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Re: High Power VESC

Postby lizardmech » 03 Feb 2017, 15:22

What software changes did you make? My UCC27211 board is running with just a change in the conf file to adjust dividers and current amp. Put it in an electric scooter and rode it around using 80A currents today.

rew
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Re: High Power VESC

Postby rew » 03 Feb 2017, 15:22

You got cheated when you ordered the UCC27211A: These are the UCC27201A... :-)

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TheFallen
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Re: High Power VESC

Postby TheFallen » 04 Feb 2017, 10:51

lizardmech wrote:What software changes did you make? My UCC27211 board is running with just a change in the conf file to adjust dividers and current amp. Put it in an electric scooter and rode it around using 80A currents today.


I tripled the deadtime as a precaution, once I got MOSFETs switching under load I was planning to tune that in. I'm also using +5V ACSxxx current sensors, that are backwards so I need to invert the current reading as well as set a new mid point. The +5V output is divided down but not perfectly so 0A is at +1.25V and full range is at 0V and +2.5V.


rew wrote:You got cheated when you ordered the UCC27211A: These are the UCC27201A... :-)


Lol, turns out they're pretty much identical, difference is CMOS/TTL inputs and the UCC27210 comes in more packages. Oh hang on, the input levels may be a little high.

lizardmech
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Re: High Power VESC

Postby lizardmech » 04 Feb 2017, 12:18

Don't buy the UCC27210 I made that mistake, luckily it was a sample request. UCC27211 is the newest version and works with 3.3v logic.

rew
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Re: High Power VESC

Postby rew » 05 Feb 2017, 08:41

TheFallen wrote:Lol, turns out they're pretty much identical, difference is CMOS/TTL inputs and the UCC27210 comes in more packages. Oh hang on, the input levels may be a little high.
The difference that I saw was that the output current was 3A vs 4A.

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TheFallen
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Re: High Power VESC

Postby TheFallen » 17 Mar 2017, 10:11

Oh man, this board has been 'blessed' by Murphy. A constant battle to try and get it to work and only a single genuine problem.

The UCC27210s are not +3V3 logic compatible.

So with that fixed, get it all programmed, with the correct firmware, and then the USB cable bounces across the PCB shorting +3V3 and VCC. Yeh, +40V is not appreciated there. So after trying to figure out what's died, spoiler: everything, replacing it I've just got the STM32F405 to solder down, reprogram and I should be able to get a motor turning.

I'm also about halfway through designing the power stage using IPT020N10N3, copper bus bars and an Insulated Metal Substrate (IMS) PCB for improved heat-sinking.

rew
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Re: High Power VESC

Postby rew » 19 Mar 2017, 05:25

Again, you do not seem to have UCC27210s but UCC27201...... even when you're dyslectic try to work on getting the numbers right.... (electronics attracts dyslectic people or the other way around, i would not be surprised if about half the people here are more or less dyslectic....)


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