Gotway ACM 1600 Autopsy and Mods

[Carlos E Rodriguez]

JUICY!

that makes me think that the current motors we have on 67 v batteries might just work also with 84v. 

Hack my controller:

-Replace MOSFET with 100Vgs and 300A rating one. 

- Bypass and inject fake 67vdc volts to the CPU.  Or build a scaling circuit to feed similar battery bolts scaled to 67 so CPU KNOW how to put warning. That would 

-Or buy a 84vdc controller. 

@electric_vehicle_lover

Do you know where to find the circuit diagram for the GOTWAY board?

Can someone jack the server and give us the schematic

what MOSFET they use for 84v

[Carlos E Rodriguez]

8 minutes ago, Rehab1 said:

So do they use a voltage regulator?

They use a board designed to handle the higher voltage. It looks like the motor can handle the higher voltage with no issues. 

[Chriull]

 

56 minutes ago, SuperSport said:

I know the MSuper uses the same motor on 67.2 and 84. 

 

54 minutes ago, Rehab1 said:

So do they use a voltage regulator?

 

45 minutes ago, Carlos E Rodriguez said:

They use a board designed to handle the higher voltage. It looks like the motor can handle the higher voltage with no issues. 

The motor should have no direct prob by a 25% higher voltage. The primary danger from higher voltage would be "breakdown voltage/disruptive discharge voltage" of the insulation of the motor coils. Insulations are designed with much higer safety factors.

By the higher voltage the motor could just be destroyed since by the higher possible currents it could be "overpowered" (overtemperature, demagnetizaton of the permanent magnets, magnetic saturation, etc) which still seems to be well within the possibilities of the motor. Its a quite solid metall part with nice cooling (air contact).

Additionally, as frequently reported, the motor wires, connectors, mosfets, etc are designed to act as fuses to protect the motor... ;(

Edit:

At low speeds the mainboard limits the possible max current anyway - so since with the same max current one gets the same max torque the battery voltage does not (really) matter.

For speeds this current limiting is not in effect anymore (torque resulting from this max current is outside of the max torque speed limit) the max torque speed limit curve is in favour of to the higher voltage EUC. -> higher speed and higher torque at the same speed possible (if the electronics and wires survive it;) ).

Edit2:

@Rehab1: Mentioning a voltage regulator is a nice way to describe how the EUC controller works - the controller chops the battery voltage into pulses of different duty factors. The inductance of the motor coils (by the mechanical ?inertia? (load) of the system) smoothes this pulses to the average of this chopped voltage. So there exists a voltage converter in every EUC.

i.e. no matter if looking at the 67,2V or 84V version of this wheel with the same motor - if they drive side by side with the same speed and acceleration and the same resistance forces (wind, incline, riders weight, balancing, etc) the controllers of both wheels generate the same averaged voltage for the motor.

[SuperSport]

25 minutes ago, Rehab1 said:

So do they use a voltage regulator?

No, the motor handles the higher voltage just fine. 

17 minutes ago, Carlos E Rodriguez said:

JUICY!

that makes me think that the current motors we have on 67 v batteries might just work also with 84v. 

Hack my controller:

-Replace MOSFET with 100Vgs and 300A rating one. 

- Bypass and inject fake 67vdc volts to the CPU.  Or build a scaling circuit to feed similar battery bolts scaled to 67 so CPU KNOW how to put warning. That would 

-Or buy a 84vdc controller. 

@electric_vehicle_lover

Do you know where to find the circuit diagram for the GOTWAY board?

Can someone jack the server and give us the schematic

what MOSFET they use for 84v

Wouldn't it be easier to just buy the new controller for $150 that's already set up?  Maybe up the Mossfets to higher Amps if wanted. 

[Slaughthammer]

1 minute ago, SuperSport said:

28 minutes ago, Rehab1 said:

So do they use a voltage regulator?

No, the motor handles the higher voltage just fine. 

Well, strictly speaking the controller of any EUC is a voltage regulator. It does quite some other things as well, but the voltage at the motor leads does not depend too much on the battery voltage. It won't get much, if any at all, higher than battery voltage though.

[meepmeepmayer]

Afaik all the motors in ACM and msuper V3, 67V or 84V, are the exact same. The 16 vs 18 inch is just different "rims" (not sure what the word is) for the tires.

[Chriull]

20 hours ago, esaj said:

It turns out that the difference between a "basic" BLDC and PMSM is in the windings (and of course the driving algorithm, which is much more complex for PMSM):

...

The main difference between BLDC and PMSM is the drive signal for which it is designed. A
PMSM is designed for a sinusoidal drive, while a BLDC is designed for a trapezoidal
drive. The advantage of a sinusoidal driven motor is the minimized torque ripple that
results in a much quieter motor, both electrically and mechanically.
 

Seems to be the explanation for the loud high pitched noise gotways and kingsongs produce compared to other wheels...

Either they use an BLDC instead of an PMSM motor or they just have a non optimal/?wrong? driving algorithm.

I came more or less to this assumption from browsing http://krex.k-state.edu/dspace/handle/2097/1507 - but i never could read this in detail  Thanks for citing this nice summary!

Sorry for the off topic input from my side

[Slaughthammer]

31 minutes ago, Chriull said:

Seems to be the explanation for the loud high pitched noise gotways and kingsongs produce compared to other wheels...

No. The high pitched noise is the PWM switching frequency at ~7kHz. If I understand @esaj correctly, an PMSM Motor would need an additional phase. Since all EUC motors that I have heard of until now have exactly three phases, they should all be BLDC motors.

[Rehab1]

@esaj @Carlos E Rodriguez I counted the slots, 3Xs to make sure, are there are 63....so 21 coils per leg. There are 14 individual wires that make up the copper jumpers. I have not ripped apart the coils yet to determine the number of copper strands but they definitely outnumber the jumpers.

[esaj]

2 hours ago, Chriull said:

Seems to be the explanation for the loud high pitched noise gotways and kingsongs produce compared to other wheels...

Either they use an BLDC instead of an PMSM motor or they just have a non optimal/?wrong? driving algorithm.

I came more or less to this assumption from browsing http://krex.k-state.edu/dspace/handle/2097/1507 - but i never could read this in detail  Thanks for citing this nice summary!

Sorry for the off topic input from my side

I certainly can't say for sure, but the winding would still suggest PMSM? For the noise, I don't know, it seems the more powerful motors are noisier, but even PMSM probably isn't totally silent, just less noisy than a BLDC?   Also, another source says that the space-vector commutation used in FOC has higher torque ripple, which might cause more noise too:

"Space-vector commutation is even more computationally intensive. And while it has more torque ripple than a sinusoidal drive, it makes higher utilization of the bus voltage and is therefore more efficient in terms of power."

https://robotics.stackexchange.com/questions/261/what-do-the-commutation-waveforms-look-like-for-a-brushless-motor  (The first answer also has nice images of the waveforms and comments)

 

1 hour ago, Slaughthammer said:

No. The high pitched noise is the PWM switching frequency at ~7kHz. If I understand @esaj correctly, an PMSM Motor would need an additional phase. Since all EUC motors that I have heard of until now have exactly three phases, they should all be BLDC motors.

It's still a 3-phase motor, but the phases are always connected either on the high or low-side, they're not left floating like with the BLDC trapezoidal control.   At least I'm fairly sure on that    

Trapezoidal:

Only two phases are connected at a time, the third one is floating (not connected to high- or low-side of its half-bridge).

FOC / Space-vector commutation:

All the phases are connected to either high or low side at all times (except during transitions, actually).

Both of the above images show just the whether they're connected to high- or low-side (or neither, in case of one phase for trapezoidal control), but of course PWM is also involved to control the voltage, the images just leave that out.

As the motor turns, the phases are ramped up and down at varying duty cycles. I get the rotational matrices (I'm a game programmer, remember? ), but where and how to get the reference frame angles and such is still a bit of a mystery to me (have to re-read some papers and more sources obviously)... Probably I should get some simple motor controller and a small PMSM to try it out in practice to gain better understanding.

I can't say I really understand it all, but I keep trying to learn

[Slaughthammer]

3 minutes ago, esaj said:

It's still a 3-phase motor, but the phases are always connected either on the high or low-side, they're not left floating like with the BLDC trapezoidal control ("").   At least I'm fairly sure on that  

Ok, now I see what was meant by "additional phase"...

But still, the high pitched noise is the PWM. If it was the torque ripple, the pitch would be speed dependend, which it obviously is not.

Additionally, I read in some ad for an EUC something abount sinusoidal motor drive, that would also point in the direction of PMSM instead of BLDC...

[esaj]

2 hours ago, Carlos E Rodriguez said:

what MOSFET they use for 84v

I think Rockwheel GT16 & Gotway MSuperV3, ACM and maybe Monster use IRFP4110 or IRFB4110. Might be used in other higher voltage wheels also?. The difference between the P- and B-models is that the P-model uses a more heavy-duty TO-247 -package, while the B-model has the TO-220, other than that they should be pretty much the same.

http://www.infineon.com/dgdl/irfp4110pbf.pdf?fileId=5546d462533600a4015356290ec51ffe

http://www.infineon.com/dgdl/irfb4110pbf.pdf?fileId=5546d462533600a401535615a9571e0b

 

[electric_vehicle_lover]

20 hours ago, Carlos E Rodriguez said:

 

@electric_vehicle_lover

 

Do you know where to find the circuit diagram for the GOTWAY board?

Can someone jack the server and give us the schematic

what MOSFET they use for 84v

I had to buy a few units of MicroWorks 30B4 boards to play with them draw the simplified schematic: https://github.com/EGG-electric-unicycle/documentation/wiki/MicroWorks-30B4-30kmh-controller-board-with-bluetooth

If now one will do that for other boards, there will be no schematic for no one :-)

[Carlos E Rodriguez]

15 minutes ago, electric_vehicle_lover said:

I had to buy a few units of MicroWorks 30B4 boards to play with them draw the simplified schematic: https://github.com/EGG-electric-unicycle/documentation/wiki/MicroWorks-30B4-30kmh-controller-board-with-bluetooth

If now one will do that for other boards, there will be no schematic for no one :-)

I am 100% certain that Microworks makes the controller for Gotway. The lower end 30B4 is almost identical. Also the microworks web site offers what looks like the MCM4 controller.  And it looks like the same one as in the Microworks Geek wheel. 

So my guess is Gotway only designed the shells since their app also is terrible and it looks like they don't care at all to make it work right for IOS. 

Also at one point they showed a 12 MOSFET board 40B but some how they did not release it in the open market. Only the 30B is available. 

@electric_vehicle_lover  Can you run the unmodified 30B board at 67 and 84 volts? Does the board care other than posibly changing the MOSFET to higher specs?

wonderinf if a 30B board can be updated with stronger MOSFET and the run it with higher battery bolts. Does the default software cares?

[electric_vehicle_lover]

24 minutes ago, Carlos E Rodriguez said:

I am 100% certain that Microworks makes the controller for Gotway. The lower end 30B4 is almost identical. Also the microworks web site offers what looks like the MCM4 controller.  And it looks like the same one as in the Microworks Geek wheel. 

So my guess is Gotway only designed the shells since their app also is terrible and it looks like they don't care at all to make it work right for IOS. 

Also at one point they showed a 12 MOSFET board 40B but some how they did not release it in the open market. Only the 30B is available. 

@electric_vehicle_lover  Can you run the unmodified 30B board at 67 and 84 volts? Does the board care other than posibly changing the MOSFET to higher specs?

wonderinf if a 30B board can be updated with stronger MOSFET and the run it with higher battery bolts. Does the default software cares?

I also think the same as you, about MicroWorks and Gotway controllers.

30B4 measures battery voltage/board input voltage on PA4 pin for STM32F103 and that is the only voltage it is able to measure. For Vin = 60V, PA4 pin = 2.35V. PA4 pin limit voltage should be about 3.2V, so, Vin max = 81.7V. BUT, we need to account the voltage produced when regen the battery/braking - which I don't know a safe margin that should be.

I don't know what the original firmwares does with PA4 voltage pin value, but for sure low voltage limit and I don't know about a possible high voltage limit (to protect the battery pack??).
Also Vin voltage value may be used on FOC motor control, but as a relative value (for sensorless algorithm at least) - I hope is not a a problem.

With an OpenSource firmware, we will be able to do things like change 1 resistor on the circuit so the board can measure much high values than 81.7V!!

[electric_vehicle_lover]

5 hours ago, electric_vehicle_lover said:

With an OpenSource firmware, we will be able to do things like change 1 resistor on the circuit so the board can measure much high values than 81.7V!!

Not just that part of the circuit... things like power supply ICs, etc. But 30B4 is a good board to hack!! very simple technology  and cheap!!

[Berus]

@electric_vehicle_lover @Carlos E Rodriguez

 ... I have some dubts about your hypotheses about GW MW controllers. This because when I asked a controller as replacement of one burned ( MCM4 V2 HS warranty) it comes from other company ( I thought like  you some times ago)

But of course  .. we can't know the truth !

[Hunka Hunka Burning Love]

It could be possible that MicroWorks bought some Gotway wheels and reverse engineered their boards to produce their own product to the market.  I always thought they produced boards and did customizations to them for other companies.  They were selling some Gotway wheels on their website a while ago.  With so many copycat companies in China it's difficult to tell the chicken from the egg.

[Rehab1]

Brief update on the mods. Now that all of the battery wires are repaired from the issue this past weekend  I moved onto installing the ventilation fan, dual air intake vents and the temperature data logger. I hope to have all of the mods completed before the new motor arrives. 

For those of you concerned about water entering the shell either through the air intakes or the ventilation fan, custom waterproof silicone boots will be fabricated to cover them in the event of rain.

 

[TremF]

2 minutes ago, Rehab1 said:

Brief update on the mods. Now that all of the battery wires are repaired from the issue this past weekend  I moved onto installing the ventilation fan, dual air intake vents and the temperature data logger. I hope to have all of the mods completed before the new motor arrives. 

For those of you concerned about water entering the shell either through the air intakes or the ventilation fan, custom waterproof silicone boots will be fabricated to cover them in the event of rain.

 

I'd also be worried about the dust that can get in. While riding along the canal, when it's dry, my ACM and Monster kick up a lot of dust which you'd be sucking right inside?

[Hunka Hunka Burning Love]

Maybe some thin pieces of 3M Filtrete, thin sponge material or mask filter paper could be used to help reduce the dust intake as yes things do get dusty while riding...

[Rehab1]

24 minutes ago, TremF said:

I'd also be worried about the dust that can get in. While riding along the canal, when it's dry, my ACM and Monster kick up a lot of dust which you'd be sucking right inside?

 

 

 

20 minutes ago, Hunka Hunka Burning Love said:

Maybe some thin pieces of 3M Filtrete or coffee filter paper could be used to help reduce the dust intake as yes things do get dusty while riding...

You both make a strong points so I may place air filters inside. The outside cover is easy to remove for routine filter maintenance. Thanks!

I am really interested to see how the temperature data logger performs while riding with both the fan on and off to see if it offers any cooling capacity.

[Rehab1]

I evaluated the air flow on the ventilation fan I installed and It appears to work fine. The real tests will be when the ACM is back on the road and I will then be able to measure the inside temperatures around the circuit board. I was not able to place the temperature data logger directly over the Mosfets but it is located on the heat sink. 

 

[Marty Backe]

53 minutes ago, Rehab1 said:

I evaluated the air flow on the ventilation fan I installed and It appears to work fine. The real tests will be when the ACM is back on the road and I will then be able to measure the inside temperatures around the circuit board. I was not able to place the temperature data logger directly over the Mosfets but it is located on the heat sink. 

 

When do you expect to receive your 2nd ACM? Without a 'reference standard' you really won't know how effective your cooling mods are 

In all seriousness (although I was being semi-serious above) your cooling mods are very, can I use the word cool?!

[Rehab1]

1 hour ago, Marty Backe said:

When do you expect to receive your 2nd ACM? Without a 'reference standard' you really won't know how effective your cooling mods are 

In all seriousness (although I was being semi-serious above) your cooling mods are very, can I use the word cool?!

Since I will be able to switch the fan on and off at my discretion this simple interaction should provide some degree of evidence based data on the efficacy of the fan and how it directly affects the ambient temperature inside the ACM. The data gathering will mostly be based of the output of temperature data logger. 

Now if you would like to donate your ACM to science I believe we can further the research in areas such as reducing pressure drop and eliminating flow induced vibrations that will aid in ensuring uniform flow parameters throughout the ACM shell.