High Power VESC

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

Postby rew » 09 Dec 2016, 09:21


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TheFallen
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Re: High Power VESC

Postby TheFallen » 09 Dec 2016, 13:51

Right so if I alter 'CURRENT_AMP_GAIN' to be -10 or similar I'll get inverted current signals, excellent, that'll help the physical layout.

I wanted to avoid shunt resistors as they would be hard to build a dead-bug style power stage. In addition the hall-effect current sensors interfere with the current less and will be immune to much of the noise and temperature of the power stage. I will probably move back to current shunts when I move to 3 phase current sensors.

The wires should be pretty short and will be in twisted pairs and it's a style that has proved effective for similar controllers in large combat robots.

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TheFallen
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Re: High Power VESC

Postby TheFallen » 09 Dec 2016, 22:48

Tonight I got some more done:
Image
Image
I've programmed the board with the stock firmware and it's responding to BLDCtool and giving sensible values from the inputs. I've also got my crimper out and crimped the JST-PH headers together for the power, programming and the 3 half-bridges. As you can see the gate signals are in twisted pairs for noise immunity and to reduce EMI.

I also soldered up the power stage:
Image

The copper bus bars are further away from each other than I planned but it will do for a first test. I also made a mistake with the mounting holes for the high side MOSFETs. I'm planning a spreader bar to clamp them in place instead. This picture shows the placement of the ACSxxx current sensors quite well, I'll be soldering wires and heatshrinking them once I find my red, black and green wire. I also need to add the bulk capacitor and fast response capacitor between the bus bars. The final task will be the power wiring with 8 AWG silicon wire.

rew
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Re: High Power VESC

Postby rew » 10 Dec 2016, 12:17


pf26
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Re: High Power VESC

Postby pf26 » 11 Dec 2016, 18:19


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TheFallen
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Re: High Power VESC

Postby TheFallen » 12 Dec 2016, 07:51

I thought so pf26 but I've now soldered the ACSxxx's in backwards so I hope it will workout. :D

Made up the ACSxxx wiring last night so all I have to do now is mount the PCB and dig out heat-shrink for insulating/supporting the joints. Image

There is just enough room for everything in there, it's because the PCB is loose it looks like it's resting on the bus bars. But this gives a good view of the heatsink plate and how the the Hammond Manufacturing case (1455K1201) fits over everything as protection. The heatsink plate I'm planning to get made up by local CNC machine shops, best price I've been quoted was £25 each delivered. That seems pretty good.

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Re: High Power VESC

Postby pf26 » 12 Dec 2016, 09:14

I think there is a large distance between your - and + copper bars (busbar). This increases inductance and is not wanted.
In the original design, there was just space for the 3 motor wires to come through.

rew
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Re: High Power VESC

Postby rew » 12 Dec 2016, 22:44


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TheFallen
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Re: High Power VESC

Postby TheFallen » 13 Dec 2016, 00:32


rew
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Re: High Power VESC

Postby rew » 13 Dec 2016, 08:44

The gate resistance needs to be close to the fet. So I would recommend taking a few leaded resistors and solder them inline.


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