Converting 3-phase to 6-phase by cutting coils at the star point

[mxlemming]

I spent ages looking at your pics. Far longer than I should have.

I am really sorry for that, but I wanted to say a sincere thanks for encouraging me to try the modification. I think I'd still be trying to wrap my head around it if it hadn't been for your help.

VESC has matured a lot, and we're doing what we can to move it even further along. There's an exciting future for VESC, I think it has cracked the code for a viable open-source high-power ESC.

I wouldn't have tried to help if it wasn't interesting to me. Please post all the results/video when you get it running with 2 VESCs.

I have a love hate relationship with VESC. Love the interfaces, the logging etc, hate the random screaming of motors, propensity for self destruction... I've burnt more hours trying to get VESC to work on a board I made than I spent coding my entire FOC. But it does work better than mine, when it works...

Keep up the good work. I've got 5x 12fet IMS boards in the post relying on the VESC code to run.

 

[kubark42]

Took way too long to solder but here it is:



I soldered a new set of rings above the first set. It's a little precarious right now because there's nothing supporting the new rings, but it'll do for testing.

Next step is to try with two ESCs simultaneously. I'm thinking to use a HobbyWing Platinum Pro 200 to pair with the VESC 100/250.

 

[kubark42]

The motor starts up fine. But I'm not sure what to think when both the HobbyWing (duty-cycle control, trapezoidal waveform) and the VESC 100/250 (current control, FOC) run simultaneously. Here's the video: https://vimeo.com/647759550

Description:

• First I run the ESCs individually

• Then I start the HobbyWing and bring the VESC online. Notice that the system barely speeds up, but the sound quality changes.

• Then I shut the HobbyWing off. Notice that the motor almost comes to a complete halt before the VESC kicks in and accelerates to a higher speed than before

• Finally, I run the VESC and then bring the HobbyWing online. The result is a brutal deceleration. It's hard to see in the video, but the sound is unmistakable!

Wiser minds than mine have pointed out that this behavior might be perfectly normal, since the duty cycle control of the HobbyWing imposes a speed, and the current control from the VESC provides more torque but in the no-load situation the additional torque doesn't lead to much more additional speed.

 

[mxlemming]

Won't let me watch your video, says unrated... I saw it on the other forum where it loads but just a heads up.

My guess is hobbywing controls duty cycle, so essentially hard clamps the speed, like you said below.

Sounds fairly smooth TBH.

 

[ray88]

The motor starts up fine. But I'm not sure what to think when both the HobbyWing (duty-cycle control, trapezoidal waveform) and the VESC 100/250 (current control, FOC) run simultaneously. Here's the video: https://vimeo.com/647759550

Description:

• First I run the ESCs individually

• Then I start the HobbyWing and bring the VESC online. Notice that the system barely speeds up, but the sound quality changes.

• Then I shut the HobbyWing off. Notice that the motor almost comes to a complete halt before the VESC kicks in and accelerates to a higher speed than before

• Finally, I run the VESC and then bring the HobbyWing online. The result is a brutal deceleration. It's hard to see in the video, but the sound is unmistakable!

Wiser minds than mine have pointed out that this behavior might be perfectly normal, since the duty cycle control of the HobbyWing imposes a speed, and the current control from the VESC provides more torque but in the no-load situation the additional torque doesn't lead to much more additional speed.

For it to work properly you need two identical controllers ! Vesc controller has a CAN interface through which it can send throttle info to the second Vesc . Even if you put it into reverse , the second Vesc will know what to do

 

[kubark42]

For it to work properly you need two identical controllers !

Can you explain some about why you think this is the case? Aside from mutual inductance, so long as at least one controller is in current-control mode I don't see where the two ESCs will be interacting.

 

[ray88]

For it to work properly you need two identical controllers !

Can you explain some about why you think this is the case? Aside from mutual inductance, so long as at least one controller is in current-control mode I don't see where the two ESCs will be interacting.

I watched your test video , it clearly showed how both controllers interact with each other . I don't know how it would work but if it works by putting one controller in current mode why not. Ive only seen tests with identical controllers and vesc can link together over CAN .
https://www.youtube.com/watch?v=LgRK4_4ElhU&ab_channel=mauimart

https://www.youtube.com/watch?v=3eL0EMFPnVw&t=9s&ab_channel=ArlinSansome

 

[kubark42]

As an update, I have now driven this to 14kW using the aforementioned VESC 100/250 and HobbyWing Platinum Pro 130A. I don't have a temperature sensor set up yet so I stopped the operation out of an abundance of caution, but it is quite clear that the concept is working. Whether it works as efficiently as if the windings were still tied together is an open question.

It is also an open question about whether the system is more or less fault-tolerant than before the modification.

I have an A200S on order, and once it arrives I'll be able to test to the full 18kW as well as use VESC's advanced features to map out fault tolerance.