[Jetlag]

Rev1.0b of the PCB

Just added some vias to the power ground planes in order to reduce EMI. Those vias were present on Rev1.0 but were lost on Rev1.0a PCB for unknown reason.

Is this file available? I only see version 1.0 in this thread.

[kreutz]

Is this file available? I only see version 1.0 in this thread.

I will post the complete schematics and B.O.M. as soon as the boards being assembled by Tenmetalman and Contactirfu are tested.

Thank you for your patience.

Kreutz.

[rokag3]

Hello Mr Kreutz

Taken from Rutex FAQs
what is the minimum armature resistant?
he give this formula max volts/continuous stall current of the mosfet /max volts
irf 264 200V 30A
in our case 200V/30A/200 =0.033 ohms per volts
so for 180V :180*.033=5.99ohms!!! minimum armature resistance
since the armature resistance of my motor is 1.3 ohms
5.99ohms-(.25ohms wiring+1.3ohms armature resistance)=4.45ohms of braking resistance
since i require 8A to get full torque
4.45ohms*(8A*8A)=248Watt
such braking resistor represent 8A*4.45ohms=35.6Voltage drop
minus 180V=144.4V so 80percent speed at full torque
am i correct ?

[kreutz]

Hello Mr Kreutz

Taken from Rutex FAQs
what is the minimum armature resistant?
he give this formula max volts/continuous stall current of the mosfet /max volts
irf 264 200V 30A
in our case 200V/30A/200 =0.033 ohms per volts
so for 180V :180*.033=5.99ohms!!! minimum armature resistance
since the armature resistance of my motor is 1.3 ohms
5.99ohms-(.25ohms wiring+1.3ohms armature resistance)=4.45ohms of braking resistance
since i require 8A to get full torque
4.45ohms*(8A*8A)=248Watt
such braking resistor represent 8A*4.45ohms=35.6Voltage drop
minus 180V=144.4V so 80percent speed at full torque
am i correct ?

Hello Rokag3;

Can you, please, send me a link to the calculation's original source? Any diagrams?

Thanks,

Kreutz.

[rokag3]

good morning,
http://www.rutex.com/pdf/Mystique2.pdf
this is the information i get on the subject
but the result of my calculation tell you why i am so interested by the gecko system but is it a solution or something else ?because if i can put the braking resistance only when i need it that's perfect

http://www.hv4all.com/cnc/Power%2520...%2520Bleed.pdf

[rokag3]

link

http://www.hv4all.com/cnc/Power%2520...%2520Bleed.pdf

[kreutz]

There is a difference between what they call "braking resistor" and the regenerative energy dump on the power supply.

Excess voltage develops as a regenerative effect of braking at high speeds by increasing the capacitor's voltage due to the energy returned to the power supply while decelerating, being the peak regenerative current limited/controlled or not. It is controlled by a regenerative energy dump circuit like the one posted by Mariss.

A "braking resistor" is added for another purpose, it limits the regenerative current peak value to the peak maximum allowed by the motor's armature and the controller's power stage. The peak current develops as the result of the BEMF voltage divided by the armature resistance, and requires to know the BEMF constant (given in volts per unit of rotational speed) of the motor (or externally rotating the motor at maximum speed and measuring the generated voltage) in order to calculate the required value.

That series resistor will also limit the maximum rpms, due to its voltage drop, unless it is switched In and Out of the circuit by hardware (which requires a fast contactor and a control circuit incorporated into the drive) or by active reverse current control on the drive itself, in this case there is no need for that resistor.

[contactirfu]

Anyone see the heatsink size!

[kreutz]

Any see the heatsink size!

Looks good, Your machine looks super too!!

Regards,

Kreutz.

[contactirfu]

Few updates on Heatsink, wanted to ask if I could let the heat sinks hang with support from the PCB.

The red tube is silicone (did not use that as heat sink paste, but the one in blue - it is also silicone based but with metal oxides. its called rohdia 340.

[kreutz]

Few updates on Heatsink, wanted to ask if I could let the heat sinks hang with support from the PCB.

The red tube is silicone (did not use that as heat sink paste, but the one in blue - it is also silicone based but with metal oxides. its called rohdia 340.

Hello;

I don't think it is going to be a problem for a short time, but over time it could stress the solder junction on the Mosfet leads' pads, or even the plastic encapsulate could crack at the Mosfet lead's junction. It would be better to support the board on the heat-sink and not the other way around.

Regards,

Kreutz.

[tenmetalman]

Contactirfu,
Boy O Boy, I quit watching you for just a minute and here you are thinking again ! The heatsinks look Great, You & I need to talk. I do agree with Kreutz. having spent 40 + years around industrial machinery, One of the most difficult things to keep from tearing things apart both mechanically & Electronically is vibration. When running the early CNC milling centers we kept a small plastic hammer handy & when the machine did anything strange. You stopped the cycle, opened the electronics cabinets & tapped each and every daughterboard on the edge to reseat the pins. Close cabinets, resume auto cycle and you were probably good for 8 hrs to three eight hour shifts. In the early milling centers there could be 200 or more daughtercards. Hence the hammer. Leaving the sixty's, You could make a couple of end pieces that support the weight of the heatsink & transfer it to the standoffs at the corners of the PCB using the same bolts that hold the PCB.
Paul

[contactirfu]

PAul and Kreutz,

I think I will route a few parts to sit under the heatsink- snug fit.

Today is testing day.

Hurrah!

Irfan

[H.O]

Today is testing day.

FINALLY!

Just kidding - This is going to be very interesting! I'm eager to get my hands on a set of suitable drives for my motors and want too see the results of these tests before I decide which way to go. Please keep up the nice work and keep us posted on the progress!

[koslaz]

Hi guys, can anyone tell me how hard/easy it is to tune a pair of identical spec motors with a pair uhu's for driving a long x axis with rack and pinions on both sides of it? (1 axis two motors).
I hope Mr Uli see this and reply as I think in the German site someone did it.

[contactirfu]

Progress today,

Powered up the boards and out flew the tantalum caps,I put 16v caps on a 15.7 supply....quickly got them changed to 35v ones.

All boards power up sweetly ...... tomorrow I am planning to connect the drives to the computer and run the UHU terminal program. configure them and then test the 26LS31 encoder driver. I built. Hope that works well as planned.

If that works fine I have to make another 3 of those driver for the 3 other motors I have but before that I am gonna finish testing all 3 UHU HP boards under low voltage. Once I have everything in place I plan to fit the drives in my router and run it full power at 110v 7 amps continuous. I have to still learn to configure the vref for the current setting.

Thats it for now.......meanwhile I am using a candcnc.com BOB.

Much more to come !

RGDS
Irfan

[luckym]

Hi all.
What is the max step frequency for the UHU controller. I've read, the max freq. for encoder is about 200kHz. Is the same for step input?
thanks for reply.
michal

[luckym]

Hi all.
What is the max step frequency for the UHU controller. I've read, the max freq. for encoder is about 200kHz. Is it the same for step input?
thanks for reply.
michal

[rokag3]

Hi guys, can anyone tell me how hard/easy it is to tune a pair of identical spec motors with a pair uhu's for driving a long x axis with rack and pinions on both sides of it? (1 axis two motors).
I hope Mr Uli see this and reply as I think in the German site someone did it.

2 motors 2 uhu 1 axe no problem just divide the step and dir signal for each card
even if the motors are a bit different the less performant will define the upper limit
2 motors 1 uhu 1 axe good luck but i am affraid there is no way
it will surprise me that you will always have the same balance torque compensation in every case
at least you must have only one encoder

[rokag3]

hello,
i know it's a bit early but any idea of the price for superUHU ???