Reply with QuoteOh, manjeet is alive and kicking, like every one else he has his other main business of packaging machinery and mostly busy with that. LAst time I called him he was busy getting stuff for a cnc lathe conversion.
RGDS
Irfan
Originally Posted by HJozsi
Hi John,
on the picture I can see the original UHU board (not the HP UHU)...
It is really more stable than Embedded, but I had reseting problems with big motors ( 136V 15 Amp 1kW)...
The real stable one is the HP UHU, I had never proc reset, despite I pushed the Reset button ...With 160V, 23 A ...
Regards,
Jozsef
Hi Jozsef,
Yes. That's the original UHU which I had ordered as a kit from Manjeet before I got the HP UHUs. I will be using the HP UHU's on my mill.
BTW, has anyone heard from Manjeet lately. Doesn't reply to emails.
John
Oh, manjeet is alive and kicking, like every one else he has his other main business of packaging machinery and mostly busy with that. LAst time I called him he was busy getting stuff for a cnc lathe conversion.
RGDS
Irfan
Hello,
my goal is to switch off the power of the servo and short circuit the motor with a shunt (5ohms)
i am going to use a relay with 3 contacts
2 wil be use to bring the power on sw1 et sw2 and one to disconect the shunt sw3
so when no energised (error state or no 15 V) the situation of the relay will be sw1+sw2 off sw3 on
if energised i will have sw1+sw2 on sw3 off
since they work on the same relay i will never meet the situation sw1+sw2 on sw3 on a 0.1microF will be put on sw3
my relay(24Vdc 390 ohms) (3*240v 10 A) will be driven with a darlington bd680
in order to take no risk with the pc i want to connect the base of the darlington through an optobridge
the power of the relay will be given by the 15 v of the logic and a diode of protection as been added
did anyone can make a little electronic shema do make the job?
efaristo poly
lucien
Hi Lucien,
Why do you want to put a shunt across the motor? is it to try and hold the motors in position?
It might be better to use a 4 pole relay and the 4th NC pole to place a small high wattage load resistor across the power supply to drain the capacitors as quickly as possible.
John
hello john
we have a system to discharge the capacitor
the problem is in case of errors the power stage is disconected then the dump circuit is also disconected so the motor work with the inertia (huge in my case) that's why i need another circuit to dump that the shunt will be placed between armature+ and armature-
Having a relay 24v energised with 15V i think that i will have 100 msec delay
sw1 and sw2 will swich only the +
maybe some one solve this problems in a better way
Some contactors have the possibility to make pairs of contacts make or break before the rest of the contacts, you can use that feature in order to make sure the load resistor contacts break a few ms before the other contacts make.
The brake resistor is better added on the power supply side, that way it will discharge the capacitors and brake the motor at the same time, just make the contacts of the relay short circuit the clamp circuit's Mosfet drain and source when it is not energized.
Hey Guys!!
I found out somebody has done just that, so the free code is already available for those interested into developing their own solution.
Here is the link.
Just because of professional respect to the author, I am not going to duplicate that work. I took a look to the code and it will be really easily ported to other dsPIC30, more drastic modifications will be necessary in order to make it work on a dsPIC33.
Converting from PWM-direction output into Locked Anti-phase require only to add an external logic chip (easy fix), but is also easily accomplished by modifying the code.
hello Mr kreutz
As i told before I have a dump system (the one of mariss from gecko) it work fine as you could see on the video (the flash light when decelerating)
The problem is when there is an error as you told me the power stage is shutoff and then there is nothing to brake the motor becaus the brake is on the side of the power supply so in case of error my motor run free wheel and on my case it's a huge amount of energy.
My problem is that i want to use on error in/out to drive an optocoupler i find out that if i put the optocoupler directly to the error i generate an error state so how can i drive an optocoupler with this signal without making it changing of state
after the phototransistor of the optocoupler will attack the base of the darlington and energised the relay
i make some test with the relay it never can be in conflict
thank you
Hello Lucien
If you make use of the error signal to shutdown the high voltage power supply (from the primary side of the transformer), and keep the clamping circuit ON, it will discharge the capacitors, and at the same time, will also brake the motor. Because the anti-parallel diodes on the Mosfets will act as a full bridge rectifier and the motor energy will be transferred into the power supply capacitors, even if the power supply is zero volts, so the resistor will be effectively across the motor terminals (with the equivalent of two diode forward voltage in series). Do a test, it should work.
Regards,
Kreutz.
yes i will test but back to my question how to use this error signal without disturbing it
Hi,
This weekend I'm laying out a small circuit board that does almost exactly that. It trips on the over voltage turning on a FET connected to the lightbulb or load resistor. Additionally, it has an optically coupled input connected to the power supply AC side before the bridge.
If power goes away (AC power drops out) the circuit also turns on the FET to drain the caps until the voltage drops out low enough to no longer turn on the FET.
Haven't tried it yet but I have some other proto circuit boards going to be made so I thought I'd just add this one.
Alternatively, just add that relay powered by the same AC that drives the power supply and use it to short the power supply with a dump resistor. Won't do over voltage protection but will dump the caps and load the motor.
John
Will it be driven by the error signal ?
The error signal will output a logic Low on the EMG-Stop In/Out terminal when the drive is in error state, you can use that signal externally to disable the power ON relay for the motor voltage power transformer. A TTL or CMOS gate input attached to that terminal will not disturb it.
Kreutz.
Last edited by kreutz; 06-14-2008 at 11:11 PM.
i will try
thank you
Must be a Software Engineer's lot in life to look at someone else's code and find fault. I'm sure it will happen with the Electronic Lead Screw once I release it.
Nice to see this DC Servo PID code is for a 3010 which is what I have on my dsPIC demo board and have ported a basic ELS to. So I've already got an application that does step/dir output.
A couple of things about the code though. Floating point code inside the interrupt routine; very slow even with a dsPIC. Variables that are initialized over and over again each time the function is called. It also uses a quadrature input rather than step and direction and the PWM code is specific to the hardware rather than 0% to +/-100% and then code to create specific drive for the hardware.
I think the code will need a bit of work. Still, it might be fun.
John
Actually the code was written for a dsPIC30F4012, reading the code is easy because it is relatively well commented . In order to be used on another circuit it will require a few modifications.
The quadrature input code (for EMC2) will work fine with Step-Dir too, but could be simplified.
The PID algorithm is based on the EMC2's, I don't like it in floating point either, but it seems to work on the author's prototype, even at less than 30 MIPS. The PWM output was designed for his OPamp based power stage, so that approach will have to be modified a little. I think that the author originally wanted to use it on a simple serial command based interface, instead of the step/dir or quadrature input, so the code uses parameters expressed in measuring units instead of normalized parameters.
As it is, it won't compile without a lot of warnings/errors, it seems that the original compiler was an early version, and strict compliant C code was not enforced, but that is also easy to solve.
I abandoned the floating point PID, for a Q15 fixed point, took a look at Microchip's DSP library PID function, and decided that it is a complete lost of time, it was made for (benchmarking) marketing purposes, and will never work on a serious circuit because of the lack of integral saturation. Too simplistic.
Now I am working on a protoboard mounted simple evaluation board. My dsPIC33 requires 3.3v power supply and the I/O current handling is limited to 4 ma maximum, so buffering/translation is required in order to drive the original LEDs and opto-couplers, specially the circuit connected to pin 17 of the Atmel chip on the original HP UHU . Some inputs are 5V compliant, some will require extra protection in order to be used on the current HP UHU board without modification. RS-232 interface will require a 3.3V driver, or input voltage conditioning on the Rx input...
Compiled C code with MPLAB C30 (student version 3.10b) is bloated, at least with no optimization, haven't tried to optimize yet.
Kreutz.
Oops. Yoiu're right. I was looking at the comments in main.c which specified the 3010.
That's the feeling I got from it too.
Not that bad with the optimizing compiler.
Total program memory used (bytes): 0x5d66 (23910) 48%
I think you'll finish way before I do since for me it's more of a back burner project. If you want to compile it with the full optimizing compiler for checking code size just send me a zip.
John
Thanks, I will send it when ready...
Kreutz.
hello ,
i have just started to test my first UHU HP board, the serial comms are fine i think !!
am able to soft reset ,and input data,
however the tantalum capacitors c19 and c23 have both blown, there is +14.9v
at both locations.
no motor power or motor is connected.
can you help please.
regards mick.
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