Solar car races

Post and discuss your VESC projects here.
lizardmech
Posts: 171
Joined: 19 Jan 2016, 10:54
Location: Australia
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Re: Solar car races

Postby lizardmech » 09 Feb 2017, 10:47

It should be fairly easy with GaN and film capacitors shouldn't it? I have 4 film capacitors on my controller, rated for about 8A each at 100khz.

Thor
Posts: 20
Joined: 22 Jan 2017, 11:32
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Re: Solar car races

Postby Thor » 24 Mar 2017, 16:18

Hey guys! I wanted to send sign of live. My 200V controller has now got a more professional make over. See for your self in the attachment. I bound myself strictly to Benjamins original design. Never the less I nedded to make some changes to achieve 200V:

1) The DRV8302 needed to go. I picked IR2110S as my predriver stage. Right next to the gates are a NPN/PNP postdriver pair to lower impedance and higher driver current capabillitys. With highest curents setting I can achieve 43ns from gatedriver input to phae output.

2) The voltage dividers were changed from 3k3/39k to 1k/64k9 to adopt to the higher input voltage range.

3) I use 500uOhm current shunts with INA240A1 with 20V/V amplifiers. The overall V/A constant is maintained as the original setup used 1mOhm 10V/V.

I got some motors turning now but there are still issues with the sensorless posission detection. Low speed tracing is quit good in sensorless mode but as the RPMs go up the motor starts to make klicking noises which eventualliy escalate into a sequence of accelleration and harsh brakeing where VESC obviously losses track of the rotor position.

Does anyone have an idea how to deal with this issue?
Thor
Attachments
HSWR V2.jpg
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tecnologic
Posts: 15
Joined: 26 Feb 2016, 08:23
Location: GER / Hamburg
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Re: Solar car races

Postby tecnologic » 24 Mar 2017, 16:49

seems u have more lag in the current measurement than the org. VESC.

regards Tec

Thor
Posts: 20
Joined: 22 Jan 2017, 11:32
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Re: Solar car races

Postby Thor » 24 Mar 2017, 20:05


pf26
Posts: 310
Joined: 28 Mar 2016, 14:37
Location: FR Valence
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Re: Solar car races

Postby pf26 » 25 Mar 2017, 11:47

Possibly you also have too much noise in your current measurements, due to high voltage switching nearby. You can have a look that using blcdtools. Filtering more is probably not an option since it would induce even more lag.

arvidb
Posts: 234
Joined: 26 Dec 2015, 14:38
Location: Sweden, Stockholm
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Re: Solar car races

Postby arvidb » 25 Mar 2017, 15:53


lizardmech
Posts: 171
Joined: 19 Jan 2016, 10:54
Location: Australia
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Re: Solar car races

Postby lizardmech » 26 Mar 2017, 08:32

What does the current graph look like in BLDC tool? My ina240a1 can easily run at 2A motor current even when using a 0.5mohm shunt. Also did you put the INA240 on the low side? I suppose it's missing the the window to sample current data at v0 above certain duty cycle. Ina240 looks like this on my board, no hardware or software filtering in this graph.
Attachments
ina240.png
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pf26
Posts: 310
Joined: 28 Mar 2016, 14:37
Location: FR Valence
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Re: Solar car races

Postby pf26 » 26 Mar 2017, 09:17

Position tracking ? there are 2 cases:
- Motor spins freely (current reference=0). The motor bemf is used to track its position, this is quite easy and more accurate at high speeds since bemf voltage increases with rpm.
- Motor is powered. You can't measure the bemf, since the VESC is now actively driving the 3 phases voltage outputs. You need to estimate this bemf from this output voltage, current measurements, and motor parameters (R and L). This is quite difficult.
The current measurements are used to track position using the observer as described here: .

Thor
Posts: 20
Joined: 22 Jan 2017, 11:32
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Re: Solar car races

Postby Thor » 26 Mar 2017, 12:56

Attachments
Screenshot from 2017-03-26 14-03-49.png
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lizardmech
Posts: 171
Joined: 19 Jan 2016, 10:54
Location: Australia
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Re: Solar car races

Postby lizardmech » 26 Mar 2017, 14:46

How is your board setup? Mine is 4 layers, the ina240s have the highest routing priority, the furthest one is 4cm from the MCU, traces are all on the top layer with a ground plane below them, the ground plane and ground for the high powered side are split with only a small connection away from electronics.

Can you take some screen shots of current graphs while it's running slowly?


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