VESC-based board(s) for sale....

If you plan to make a group order, if you have spare VESCs or parts for sale etc. you can post that here.
rew
Posts: 940
Joined: 25 Mar 2016, 12:29
Location: Delft, Netherlands.

Re: VESC-based board(s) for sale....

Postby rew » 30 Mar 2016, 11:55

Here is my dummyload for testing:
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This is the board... Ehh. boards!. Left CPU, middle driver/current amp, right is power board.
I had intended to put a heatsink on top, so I "hacked" the small capacitor to go to the other side. And the other capacitor is 4cm away to make room for the heatsink that I have. Since that plan, I've heard from IRF to cool the backside. I'm going to make a new board to test that.
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Closeup of the driver/current sense board. The "hacked" resistors are integrated onto the newer version of the board that we're assembling today or friday. I'm going to miss my scope-access-points..... :-)
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Last: My wattmeter. It claims to be able to measure up to 100A. It pretends to be able to measure in 10mA increments, but it is currently registering around 0.00A, which I think is about 100mA off.... (So after five days the Wh counter is off by about 120h * 24V * 0.1A = 288Wh.)... But then again, 100A at 75mV is 0.75mOhm of the current shunt. So at 0.1A we're talking 75 microvolts. Apparently it is unable to measure such a small voltage. Understandable.
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P.S. For the STM32 fans.... The AC version of this Wattmeter contains an STM32F030F4! (I haven't opened this one up yet, but I expect the same).


PPS: There is a maximum of two sets that go out for "the deal". One of the prospective buyers has indicated that the price was rather low, and he is right. I didn't account for any margin, and I missed a couple of not-negligible components.

hexakopter
Posts: 86
Joined: 24 Dec 2015, 15:24
Location: Germany

Re: VESC-based board(s) for sale....

Postby hexakopter » 30 Mar 2016, 21:56

Really cool build. Thank you for the pictures. Now I understand what you mean with reducing the size when the design is finished. This thing is huge. :)
Integrating the big switching step-downs on the board would be a important point I think. One is for 12V and one for 5V right? When I interpret that correctly the first step would be using the 12V with an LDO to got clean 5V. One big switching step-down less.

You haven't pinned out one SPI/UART more than on Vedders V4.XX design? When there are pins left for that it would be great to have them. I think your application maybe don't need that, but for feature interested skateboard users that would be important to have.

rew
Posts: 940
Joined: 25 Mar 2016, 12:29
Location: Delft, Netherlands.

Re: VESC-based board(s) for sale....

Postby rew » 31 Mar 2016, 08:45

After measuring the current on the 12V and 5V, I'm moving to a 25x25mm step-down board for the 12V. And simply a 7805 for the 5V. (I expect about max 50mA on the 5V, and similar on the 12V).

The above is my current debugging setup (I think I'll be moving it to my bike for reliability testing), the next version, being built today and tomorrow will have the new power-setup.

Oh, yeah. I have my own separate board with the step down. Again to be able to debug that separately from everything else. Of course it is going to be integrated as soon as it is shown to work.

rew
Posts: 940
Joined: 25 Mar 2016, 12:29
Location: Delft, Netherlands.

Re: VESC-based board(s) for sale....

Postby rew » 31 Mar 2016, 16:05

FYI: Current on 5V is more than I expected: about 70mA. Running the motor costs 2mA extra.... USB also costs something like that (but is included in the 70mA)

a 7805 from the 12V should be able to handle that. So I'm counting on 100mA, 700mW for the 7805, and also 100mA (rounded up from my measured 20mA) on the 12V. So I'm going to need 200mA on the 12V rail....

hexakopter
Posts: 86
Joined: 24 Dec 2015, 15:24
Location: Germany

Re: VESC-based board(s) for sale....

Postby hexakopter » 02 Apr 2016, 12:18

Maybe the best Idea when using LiPos would be to use the first three cells on the lets say 12s Lipo. When just 200mA are used this is a low number in comparison to the high amp current used for the motor. So debalance should be very low. When you are saying the LM5109 doesn't need "clear low-noise" 12V the voltage drop from 12.6V to 10.5V should not be a problem and the LM7805 don't have a problem with this either.
This would make it also easy to use 100V when the 12V are not down converted, but just steeled from the first three cells.

rew
Posts: 940
Joined: 25 Mar 2016, 12:29
Location: Delft, Netherlands.

Re: VESC-based board(s) for sale....

Postby rew » 03 Apr 2016, 10:49

I don't like the "stealing" of a partial voltage. Especially not with LIPOs. Running my test-motor at 3A (that's about the lowest it can go), the motor draws about the same amount of current from the 24V as the logic part.... And you might be leaving the controller on for a while.

I'm considering
* Keep the 3-pin "voltage converter" connector. You can put anything you like on there, for example my 60V step down. For now it's someone-elses-problem if you want more.
* Put the 60V stepdown that I have on the board, allow you to bypass it. if you want something else.
* That connector might double as an external "12V" input. Feel free to tap your 100V lipo at three cells.... :-)

rew
Posts: 940
Joined: 25 Mar 2016, 12:29
Location: Delft, Netherlands.

Re: VESC-based board(s) for sale....

Postby rew » 05 Apr 2016, 17:06

New batch of CPU boards are baking in the oven....
The driver and power boards are ready except for the through hole stuff like connectors.

rew
Posts: 940
Joined: 25 Mar 2016, 12:29
Location: Delft, Netherlands.

Re: VESC-based board(s) for sale....

Postby rew » 06 Apr 2016, 12:23

Tadaa!!!
Image
You might notice the missing capacitor on the driver board. I've decided that it is not necessary. I'd rather have the footprint and not need it than the other way around. Also there is a second capacitor on the small-power board. That is an attempt to be able to use this hardware for a "up to 50V, 30A software controlled power converter". That's a complicated way of saying: "lipo charger". :-) At those power-levels, actually being able to source all that power is the first concern... :-) (The 30A probably holds for both the input and the output, so the power is limited by the lower voltage. Have a big RC battery that needs charging in the field? Charge from a car battery and you can charge 12V, 30A -> 360W. Have a truck at 24V? 24V * 30A = 720W (assuming the battery is more than 24V). Have a 48V golf cart you can borrow some power from, but the battery that is going to be charged is only 36V? -> 36V*30A = 1080W.

When I have time I'll finish this project:
Imagethe heatsink on the power board. Soldering the "well heat-sinked" wires and fets is difficult.

Just tested my temperature sensor. Not the cleanest signal, but IMHO close enough. (the noise is 0.4 mV. IMHO not worth worrying about)
Image

I want to test the boards, and then they (two sets) are available for purchase. Those two that have already indicated interest are first in queue.

lizardmech
Posts: 171
Joined: 19 Jan 2016, 10:54
Location: Australia

Re: VESC-based board(s) for sale....

Postby lizardmech » 06 Apr 2016, 16:03

Do you have a list of the pins on the MCU board? I can make my power section to fit it if I know which pins do what and what connector are used.

rew
Posts: 940
Joined: 25 Mar 2016, 12:29
Location: Delft, Netherlands.

Re: VESC-based board(s) for sale....

Postby rew » 07 Apr 2016, 12:50

@lizardmech: yes. The footprint on the boards is just a 2x12 (24 pin) 0.1" header. I currently put males on top on the power and CPU module, and females on the bottom on the "driver" board.

(Driver board = fet drivers, current aplifiers and voltages. = used to be DRV82xx).

Oops... Seems the current limiting resistor was wrong.... [update: Was 1k for 22mA at 24V, now 100k. Visible enough!]
Image(A camera is built to have light from one source end up on a specific place on the sensor. Not "vaguely around it", that would lead to bad pictures. If you see that happening as in the picture above, the light source must be VERY VERY bright. The human eye is built to accept some bleeding of pixels to nearby places. The brain then interprets that as "very bright". It is a "bug" that evolution further developed into a feature.)

This is the pinout I'm using for the power section.
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Note that I now have the boards "upside down". pin 24 is the one nearest in the picture above. Where the "J1" is half-fallen-off-the-PCB is where pin 1 lives.

The "power going to the power board" can now be jumpered to be 3V3 or 5V.

In my powerboard the 5V powers the MCP9700 temperature sensor. In future boards, it might also provide the 3.3V for the ACS759 current sensors. That's why it can now be jumpered (thats a new feature on this second rev of the driver board).

[edit:]

Oh! I was just re-scanning if the signal names would be "enough" to deduce their function.... Let me make the full list...

The ISENSx signals are the positive side of the current shunts. (on rev 3 of the driver board: "Or the output of the ACS current sense chip") The ISENSxM are the negative side of the current sense resistor. Normally ground, but it's better to have a trace from the actual negative side of the current sense resistor.

GLx gate low X, gate driver resistor on the power board side. GHx: gate high signal.

Mx the raw phase wire (for the driver chip to help drive the top FET).

SENSx, SENSBUS: There are for measuring the phase and bus voltages. These have the top part of the resistor divider on the POWER board, and the lower end of the resistor divider on the CPU board. The reason is that this reduces noise (due to ground bounce). I use 39k // 2k2.

TEMP. Temperature. MCP9700 output on my board. As that's what I've designed the CPU board for, the full NTC resistor divider needs to be on the power board if you want to use an NTC...


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