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VESC - Open source ESC
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Lizard
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VESC - Open source ESC - 04.23.2015, 10:01 AM

Just found this, thought I'd share this.

Haven't read the page myself yet, but it looks really cool, all the configuration options you can possibly imagine. The software even has a Tab that shows a Back-EMF plot.

There is also some nice info on sensorless motor startup there and generally a lot of interesting info about ESCs and how they work.

@Patrick: Maybe you can use that info to fix the cogging problem on your Mambas?

http://vedder.se/2015/01/vesc-open-source-esc/
   
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brainanator
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04.23.2015, 08:18 PM

Very cool! A little over my head, but I enjoyed browsing through it. The performance he is getting out of the those outrunners on his longboard is pretty impressive to me.


OFNA Jammin CRT.5e, Savage Flux HP, MBX5Te, SCX10, Multirotors, foam planes
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Lizard
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04.24.2015, 07:48 AM

Did some more reading, this thing is simply amazing. Basically, it has every feature I've been dreaming of and some more that I don't understand :)

The algorhythms used in this thing seem so advanced, that "normal" RC controllers look like junk compared to it. It seems to have real current/torque based control and not just based on duty-cycle like RC ESCs. It has a function where it measures the motors parameters to optimize commutation during startup. The creator is also planning to add field oriented commutation.

The hardware seems pretty advanced too, it has current sensing and voltage sensing on all phases and a lot more goodies.

It also has active freewheeling, which the author doesn't even mention in the specs, just in some posting, seems it's such a basic feature to him that it's not worth mentioning in the specs :)

Starting and braking is supposed to be smoother and more efficient than any RC ESC out there. He says he reaches 95% of torque during startup without sensors.
There is a video showing completely smooth starts from standstill with a skateboard plus driver on it with gearing for 70km/h. He says, in most cases it takes only one or two commutations to "lock-in" on rotor position and reach closed-loop operation. Amazing IMHO.

He's also doing something different with braking, there is no squaling sound and the regenerative efficiency is higher.

Electrical RPM limit is around 100k RPM.


Here's some threads related to it on endless-sphere forums:
http://endless-sphere.com/forums/vie...p?f=35&t=63540
http://endless-sphere.com/forums/vie...p?f=31&t=66958


Here is a link to a BETA Program where you can get the ESC for around 150$:
http://www.enertionboards.com/electr...ta-membership/


Video of it running in an 1/8th scale buggy:
https://www.youtube.com/watch?v=3puKPFVUfdc

Configuration tutorial:
https://www.youtube.com/watch?v=17CSl1iXYE8


Video showing smooth startup:
https://www.youtube.com/watch?v=MfNcHmt_avE




Here's the feature list from the page above:

The hardware and software is open source. Since there are plenty of CPU-resources left, the customization possibilities are almost endless.
STM32F4 microcontroller.
DRV8302 MOSFET driver / buck converter / current shunt amplifier.
IRFS3006 MOEFETs (other FETs in the same package also fit).
5V 1A output for external electronics from the buck converter integrated on the DRV8302.
Voltage: 8V 60V (Safe for 3S to 12S LiPo).
Current: Up to 240A for a couple of seconds or about 50A continuous depending on the temperature and air circulation around the PCB.
Firmware based on ChibiOS/RT.
PCB size: slightly less than 40mm x 60mm.
Current and voltage measurement on all phases.
Regenerative braking.
DC motors are also supported.
Sensored or sensorless operation.
A GUI with lots of configuration parameters
Adaptive PWM frequency to get as good ADC measurements as possible.
RPM-based phase advance (or timing/field weakening).
Good start-up torque in the sensorless mode (and obviously in the sensored mode as well).
The motor is used as a tachometer, which is good for odometry on modified RC cars.
Duty-cycle control, speed control or current control.
Seamless 4-quadrant operation.
Interface to control the motor: PPM signal (RC servo), analog, UART, I2C, USB or CAN-bus.
Wireless wii nunchuk (Nyko Kama) control through the I2C port. This is convenient for electric skateboards.
Consumed and regenerated amp-hour and watt-hour counting.
Optional PPM signal output. Useful when e.g. controlling an RC car from a raspberry pi or an android device.
The USB port uses the modem profile, so an Android device can be connected to the motor controller without rooting. Because of the servo output, the odometry and the extra ADC inputs (that can be used for sensors), this is perfect for modifying an RC car to be controlled from Android (or raspberry pi).
Adjustable protection against
Low input voltage
High input voltage
High motor current
High input current
High regenerative braking current (separate limits for the motor and the input)
Rapid duty cycle changes (ramping)
High RPM (separate limits for each direction).
When the current limits are hit, a soft back-off strategy is used while the motor keeps running. If the current becomes way too high, the motor is switched off completely.
The RPM limit also has a soft back-off strategy.
Commutation works perfectly even when the speed of the motor changes rapidly. This is due to the fact that the magnetic flux is integrated after the zero crossing instead of adding a delay based on the previous speed.
When the motor is rotating while the controller is off, the commutations and the direction are tracked. The duty-cycle to get the same speed is also calculated. This is to get a smooth start when the motor is already spinning.
All of the hardware is ready for sensorless field-oriented control (FOC). Writing the software is the remaining part. However, Im not sure if FOC will have many benefits for low inductance high-speed motors besides running a bit quieter.
   
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Lizard
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04.30.2015, 05:14 AM

Now there are some on sale.

From the developer in Sweden, only the assembled PCB, no cables/plugs and capacitors:
http://vedder.se/2015/01/vesc-open-source-esc/
115EUR plus 20EUR shipping worldwide.


Or here from Australia, complete with cables/plugs, capacitors and in shrinkwrap:
http://www.enertionboards.com/electr...ta-membership/
112EUR plus shipping



For people who only need 8S max, the 60V FETs on the ESC can be replaced by these 40V FETs with lower resistance:
http://www2.mouser.com/ProductDetail...ueC7iZnQ%3D%3D
   
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Pdelcast
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07.31.2015, 01:44 PM

Hi guys,

My $.02 -- it's pretty easy to do very nice things with an ESC, when you tune the ESC to a specific motor.

This ESC is very specific, and has to be tuned to a particular motor and load, and isn't plug-and-play.

There are a few hobby people who will know enough about how to tune the ESC to a particular motor to make it worth-while, but for mass market ESCs, they MUST be plug and play, and must work with everything right out of the box.

Even the stuff we sell to OEMs, with a motor, can't be tuned to a particular setup -- because who knows when someone will take that particular ESC and move it to a completely different setup.

That's a lot harder than you might think...


That said, this guy has done some pretty amazing things. :)

Thanks!

Patrick


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Dr_T
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07.31.2015, 06:17 PM

Coincidentally, I finally started playing a bit with mine today; indeed it's far from plug and play and not something for mass market, all the input variables make me feel like I'm new at the hobby again :). Should be fun to fiddle around a bit with though, if I can make it last.

Only tested it a bit on the bench so far. Cool to feel the difference between conventional "PWM control" ESCs vs. the "Current control" mode of the VESC. Was confusing in the beginning, as at no load, it spins up to max RPM at the slightest throttle input. Thought my Tx calibration was off, but it all made sense when I realized that's exactly how Current control works :). Curious to find out how it drives and how much power it can handle without cooling. To be continued... unless magic smoke :D.

   
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Pdelcast
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07.31.2015, 06:20 PM

Typically there are two loop levels when doing current control --

An outside loop doing RPM control and an inside loop doing current control.

Without the RPM control, yes, RPM will be uncontrolled under current control.

Patrick


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lincpimp
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08.10.2015, 01:58 PM

Lack of cooling fins or any cooling method looks suspect to me. My entire electric rc experience has revolved around how to manage heat, both the components and me, as I live in southern Louisiana.

Nice to see some homemade stuff, always like that!
   
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Lizard
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08.10.2015, 02:33 PM

Yeah, it's not really ready for consumer.

But look at this video (watch until the end), it can push heavy things from a standstill while geared for 150kph :)

http://youtube.com/watch?v=FMxd9J0o3G0
   
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Dr_T
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08.14.2015, 03:53 PM

Below's a test drive of the VESC in my ~5.75 kg Kyosho XXL on 7S with moderate gearing. Even without any cooling fins, the FETs (relative high resistance 60V ones and only 6 total, so no "brute-force" Current sharing) stay under 65C at ~20-25C ambient - cooler than the motor. Maybe normal hobby ESCs could run way more efficient and be less dependent on massive amounts of FETs and cooling, if they had (better) Current control loops.

Keep in mind, the VESC is more designed for HV use, up to 12S; so the relative high kv motors on relative low Voltage (6S :)) we typically use in 1/8 scales are not optimal because of excessive Currents, but the developer is a very devoted guy and determined to make it work well, and continuously improving the firmware. One of the cool features of VESC is that the throttle directly controls the Current (so Torque) instead of the duty cycle as with normal hobby ESCs. I feel that makes the power way more linear and predictable / "doseable" compared to normal ESCs. The commutation logic is also pretty cool.


Last edited by Dr_T; 08.14.2015 at 04:39 PM.
   
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