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PeterH
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Hi, im having problems with the VESC tool. It tells me to update the firmware to version 3.58. Unfortunately I cant find it anywhere :-(.

 

Regards,

Peter

district9prawn
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Vesc tool itself contains firmware files. In vesc tool click on firmware on the left then hit the tab that says included files.

PeterH
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Hi, I cant find the right firmware there. Which VESC Tool Version do you have? I got Version 1.16 and it tells me to update the Firmware of the A200S to Version 3.58 and it only supports that version which kinda sucks.

Thanks, 

Peter

jlcortex
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Hello Euan,

What is the maximum voltage of A200S schematic? 

The 150V mosfet () has sense?

I see the driver has maximum voltage of 120V

 

 

 

TechAUmNu
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The limit is the 80v on the current shunt amplifiers INA240 

 

jlcortex
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Ok, because the shunt is at the phase output, is it?,  Do it have advantages over place shunts in the bottom side?

TechAUmNu
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@jlcortex Means FOC works much better with phase shunts. 

 

In other news I found a spectacular bug in the hardware that was probably causing all my issues at higher voltages! 

For some reason I added a 2.2uF capacitor on the voltage divider that measures the supply voltage. Which makes the frequency response of that voltage divider absolutely awful. This means that when you have hard regen braking, the bus voltage is actually significantly higher than what the ADC measures so it will keep braking too long and blow everything up.

Simple fix for this, remove C1. 

 

 

All the new boards have a TVS diode on each phase, from the supply side of the ceramic caps directly to the battery ground cable. Combined with the removal of this pesky cap it should be good for higher voltages. The TVS diode is this one https://uk.farnell.com/littelfuse/1-5ke75a/tvs-diode-1-5kw-64-1v-unidir-do/dp/2777092 which has a breakdown voltage between 71.30-78.80V, obviously adding the TVS means no 18S support, but I am going to be doing some testing at 18S again to see what difference removing the cap has. It might be that the TVS are not required depending on how fast the over voltage error turns off the fets.

 

Here you can see how detrimental the capacitor is. The main problem here is that the overvoltage warning will trigger FAR too late to do anything helpful. 2019-09-04 13_17_01-LTspice XVII - Draft1.asc_.png

 

Evolutiongts
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Do I need ST-link to update to the latest boot loader and firmware?

TechAUmNu
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Unless you have bricked the bootloader you should be able to update it over USB, the firmware has almost made it into VESC Tool which should make updating a bit easier.

e-biker
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Hi TechAUmNu,

In some cases over voltage protection is not fast enough. Have been playing with 100V setup with LAB power supply which has low output capacitance and accidently pressed regeneration button, consequences - two blown FETs, one on low side, one on high side. Over voltage protection was set on 105V, FETs used 150V so in total 45V difference was not enough to protect the FETs.

I'll to will try to do some testing with this protection.

Martin.

e-biker
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Done some measurements with over-voltage protection and it's reaction time varies from 1ms to 2ms.

TechAUmNu
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Hey e-biker,

Yeah it really isn't good enough to rely on for protecting the fets, we need reaction time in order of a few uS at most so hardware protection would be best. 

That's why I decided to add TVS diodes so there is at least something that tries to protect the fets.

I have 100v fets and set max voltage to 70v, with TVS kicking in at about 72v.

If fets do get blown, its normally only 1.

Euan

e-biker
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Hey, 

Yeah i fought about hardware protection too, but you have take some sacrifices then doing small factor ESC. 

If you have enough capacitance software protection should be fine, bad things could happen than you hit regeneration on fully charged battery pack, in this case electrolytic caps should help. It's not hard to calculate the capacitance needed.

I'm thinking adding a tvs diodes to, but doesn't decided is it necessary. Those ones that you chose is pretty fast, I like them.

Had done some crazy testing today, was trying to blow some FETS. All of that is just to decide if scope is showing noise or real voltage spikes then FETS are switching. Managed to get spikes over 30V of fet nominal voltage and fets didn't blown up (FLIR not showed any heating signs to), so I'm assuming that what scope shows is just a noise. Maybe adding those tvs diodes would clear out things further.

You are so lucky if you are blowing just one fet, usually I get 2 blown fets. Will try to use faster fuses to prevent that (want no plasma balls any more).

Martin.

TechAUmNu
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If you are getting lots of noise, make sure to use the little spring that goes on the end of the probe, or solder a coax directly to the board, get as close as possible to the supply and ground across the fet. When I measure I do it across the ceramic capacitors that are directly on top of the fets so the whole loop area is only a few mm including the fets.

I might add hardware protection at some point but for now doesn't seem necessary as long as you are reasonably sensible with settings.

At the moment I am working on an even smaller version for mass production, should be doing a batch of 100 in about a month. Main change is to take off a shunt per phase and the press fit terminals, so its now 2x 500uOhm. So max current measured will be 330A. Saves a lot of space removing the terminals and means the case can be better sealed with just holes for wires to pass through.

I also changed the input connections from 3x XT90 with 10AWG to 3x XT60 with 12 AWG. Which cuts down unnecessary weight quite a lot. The maximum battery input is set to 180A so the XT60 should be fine. 

2019-09-30 11_08_48-CircuitMaker (1.3) - A200S V2.CMPcbDoc - A200S V2 - Short.PrjPcb Euan Mutch is s.png

 

 

e-biker
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Wow, looks awesome, size and specs are too!! Gosh those 3D visualizations looks so great, maybe it's time to change old 2004 pcad to something newer! laugh

I'm fixing all my bugs in driver board and planing too add a hardware protection for over-voltage if it turns out that TVS diodes can't handle it. Probably will do some testing with 100V today after parts arrive for my damaged 5kW power supply.

Yeah I had considered out terminals just because they are so beefy and there is no real benefit for using them.

Those are a TVS diodes near electrolytic caps? You used 3kW or 5kW? Ordered a few 5kW ones.

Can you tell what are approximate costs for 3D printed case and aluminum heat sink? Still haven't decided which path to go - make a more complex heat sink and cover it with a PCB (like Vesc 6) or make a simple heat sink and more complex plastic cover with 3D printer (preliminary cost 45 Euros).

Martin.

TechAUmNu
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Yeah Altium 3D mode is the best :D

I have 3 of the cisco ws-cac-6000w, which do 42v @ 140A plus really good overcurrent protection.

The TVS I am using at the moment are 1.5kW through hole ones just tacked on the board as I didn't have any pads before. Those SMD ones are 3kW https://lcsc.com/product-detail/TVS_SOCAY-Elec-SMDJ64CA_C396542.html

Depends a lot on quantity, probably about 30-100usd for a machined heatsink at 1-5off. 3D printing case is pretty cheap if you get PLA or ABS about 10-15usd, mine are MJF Nylon12 which is quite pricey even at 100off. For a single part though MJF about 40usd.

 

grasshopper
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Hi TechAUmNu,

Is there a 3.62 firmware file for the A200s V1.3.2?

thanks

Carl_Dolk
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Hello!



I just received my A200S and was happy before I accidently ruined it… ☹



I connected with the VESC tool app and it told me that communication was limited due to old FW. I updated the FW trough the app but I probably chose the wrong board or something because it’s not booting up after this.



Could you please provide a compiled FW for me? I have a SWM programmer and I am able to connect, but I don’t know how to compile a FW from github.



I think that I can fix it if you give me the correct hex file.



Br Carl

TechAUmNu
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