PWM physical output

[CobryWZL]

Hi,

I have a SAMBA 43 J T20 and i want to controll a oilpump. In the hardware configuration I set the Output O PWM parameters and tried to start the output in a net (see image below). But this doesnt work. Do you have an example for me, that shows how it is done correctly?

Thanks!

[Ausman]

1 hour ago, CobryWZL said:

controll a oilpump.

What do you mean by this?  ON/OFF?  Variable speed?

With regards to one part of your program, do you know about Power Up values?  Please note the screenshot below showing MI6 being assigned at Power Up the value you are storing to it. 

Tick the "power plug" and type the value.  You can also do much the same in the Outputs view at the bottom of Visi.  Perhaps 3 is a varying part of what you are trying to achieve.....hence the store when the rung is running.

You are calling your output 0 as both a standard one and an "Immediate" type.  Not necessary.  Get rid of MB13 and the next rung.  However, the rest of your ladderwork which relates to O 0 needs an answer to the very first questions.

cheers, Aus

 

[CobryWZL]

I want to start the oilpump and controll its speed with the pwm signal.  At the beginning the oilpump doesnt get any power. at a certain point (e.g. when i press a start button) the pump should get power and start working with a certain speed.

I actually didnt know about that powerUp value. Good to now!

[kratmel]

Please explane oip pump setup:

Power sorce? Pump power (kW)? Driver for pump type? Model if driver is integrated to the pump? Connection Samba output to  the drive.

 

PWM on Samba can be configured via hardware setting and operated by changing Duty Cycle value 0-1000 in MI.

 

You only need to STORE Duty CYcle to the MI - in sample scren MI1, PWM  Frequency MI0  and   Run MB0=1 for PWM HSO activation.

You do not need  PWM block in ladder.  It used when PWM  Frequency is below 1Hz.

 

[AlexUT]

Hi CobryWZL,

There are two different PWM settings, and many peoples mix it by mistake.

1. Hardware PWM, which is configured in Hardware Configuration.

2. Slow PWM Scan in Ladder.

Two PWMs cannot be mixed.

In Ladder you use second one.

What is a PWM configuration in HW configuration?

 

[CobryWZL]

Obviously I really mixed the two types of PWM. The HW configuration is shown in the image below:

As you can see there we actually have two pumps, but i think if i understand how to controll one of them, i can do the same thing with the second one.
Each of the pumps is connected to its own solid state relay. These relays are connected to a power supply unit, that suits the pumps. Also the solid states relays are connected to Output0 and Output1 of the SAMBA. The wiring and choosing of the components was task of our electronics workshop and they told me that i now can trigger the solid states relays with a pwm signal from the SAMBA. So what i need to know is: How can i send a PWM signal via HW configuration from the SAMBA to the physical outputs. I thought, that i have to do something in ladder to activate the HW configuration or something like that...isnt that right?

 

BTW: I already tried to change the powerup state of MB100 and MB107 to 1 (SET) and the pumps still dont do anything

thanks!

SUDDENLY IT WORKS! I have no idea why but now the waterpumps start to work. Is it possible, that I need to download&burn to use HW configuration? during the last days i only downloaded.

the oilpump doesnt work currently, but i think i have to change the PWM paramters for it.

[Flex727]

5 hours ago, CobryWZL said:

Is it possible, that I need to download&burn to use HW configuration? during the last days i only downloaded.

No. I don't know what caused your pumps to start working, but this is not the reason.

[kratmel]

Please post to topic

solid state relay type and motor nameplate.

As i see you place 1Hz PWM Frequency to MI 103 and MI105   for the DC or AC type motor it is really slow.

Please note - this Frequency must be apropriate for solid state relay, and relay must be compatible to used motor type.

In PWM control you do not need change PWM Frequency  in program (It must be constant = powerup value). 

Only Duty Cycle MI104 or MI106 must be changed from 0 = 0 speed, 1000 = max speed.

If you post solid state relay nameplate   and motor nameplate  - i will try to recommend you Frequency for PWM.

[AlexUT]

Hi CobryWZL,,

Additional to what kratmel ask,

Please explain what frequency required to manage pump.

Is it fixed frequency and variable duty cycle?

B.R.

 

[Ausman]

14 hours ago, CobryWZL said:

Each of the pumps is connected to its own solid state relay. These relays are connected to a power supply unit, that suits the pumps

Are you SURE that it is variable speed?  Or the wiring layout has been done correctly?  It seems odd that it has an SSR connected to the supply unit, if it only needs a PWM signal to run that would normally come from the control system.   Perhaps the SSRs are the main power switching, and there is another input available for the PWM that has been missed.

This thought could possibly explain why the pumps suddenly ran, as the PWM may have crossed over the timing threshold so that the SSRs effectively stayed ON.  This is especially the case if they are actually fixed speed.

Perhaps you should post details of ALL the hardware in use.  There is information missing here that appears to be crucial.

cheers, Aus

[kratmel]

1 hour ago, Ausman said:

...SSR connected to the supply unit..

I think you're right, Aus!
That is why I tried to ask the author of the topic about the hardware present in the system from the beginning.

 

 

[CobryWZL]

Thanks guys, for all of your answers! I try to attach all HW Informations I have (The discriptions of the power supply units and the relays are in german):

 

Jabsco 32605-0394 Washdown Pump.pdf Pumpe Konzentrat UP2-OIL.pdf

[AlexUT]

1. You cannot power these motors by Ladder PWM SCAN FB. It is very slow for DC motors.

2. Right (MARCO) motor picture show remark "Do not use with PWM",  so you should use voltage regulator for this motor.

And this voltage regulator should be managed by 4-20 mA, 0-10V, or PWM signal.

3. Left picture motor may require the same regulators.

*Both motors are 12V. Do you power PLC by 12 V?

May be other Forum members has experience with such equipment?

B.R.

 

[CobryWZL]

The SAMBA is powered with the 24V power supply (its shown in the last picture) and both pumps are powered over the SSRs with the 12V power supply (also shown in the last picture). Our electronic workshop told me that i should trigger the SSR with PWM from the SAMBA to power the pumps.

13 hours ago, Ausman said:

  It seems odd that it has an SSR connected to the supply unit, if it only needs a PWM signal to run that would normally come from the control system. 

The old PLC, that was used for controlling the pumps, had analog outputs and could controll the pump power through this analog outputs without using SSR or PWM. Our SAMBA doesnt have analog outputs, so we needed an alternative to control the pump power.  I think with the SSR i now can use PWM to trigger the SSR and convert the digital output of the SAMBA to  a "analog" signal for the pumps.   At least i guess that was the idea of our electronic workshop.

[Ausman]

I actually think both those motors are not designed for variable speed.   As Alex notes from the picture...reading the actual manual says for UP2....   WARNING: DUE TO THE EMI FILTER THE PUMP IS NOT SUITABLE FOR SWITCHING APPLICATIONS (PWM DRIVER)  , which I interpret as "don't do this at all".

You can likely run them as Alex says using a voltage regulator, but they may not physically like it, particularly the Jabsco as it is appears to be a swash plate mechanism.  Also, getting something off the shelf made to work with 0-12V might be difficult.  Most of the DC motor controllers I work with are 0-180V at least.

How it was done beforehand I think needs to be exactly known.

cheers, Aus

[CobryWZL]

52 minutes ago, Ausman said:

I actually think both those motors are not designed for variable speed

I dont know how it was done exactly, but the speed of the pumps definitly was varied. We use these pumps to create a homogenious mixture of oil and water in a certain percentage, that changes for nearly every use.  I will ask our electronic workshop about this "Do not use PWM warning" on the oil pump, but i hope they already knew about it, when they bought the HW and made the wiring...

[kratmel]

Hi, in this document

http://www.crydom.com/en/products/catalog/1-dc-series-dc-panel-mount.pdf

present information about for D1D40 and D1D12 module with  MOSFET OUTPUT. 

Recomended max PWM Frequency D1D40<=950Hz,    D1D12<=4000Hz.

But in this manual present - max frequency supported on Resistive loads only. Please try to use aprox 800Hz and 3000Hz

Inductive loads must be diode suppresed (see in manual "Wiring manual"). Please ask your electronic workshop about this.

You can replace motor with 12V automotive LAMP and test you application - You will see LAMP with  PWM 0--1000 changes.

After that you can try to run motor.

I found

https://www.mate-usa.com/uploads/pdf/33-up2-oil-us.pdf

https://j109.org/docs/jabsco_parmax_shower_pump_31610-0092.pdf

manual for motor - in this manuals do not present any restriction about PWM control. Standard RF EMI filter present in all low voltage DC motors.

Please remember - you build open loop control system - speed of motor can be different in different load condition.

Sometimes pump cannot start in LOW PWM Duty rate - and some controller do short "start with high PWM"  and RUN with low rate PWM.

[Ausman]

With overnight pondering whilst asleep (thankyou brain),  I actually think you need to change methods. 

A direct lift from the Jabsco sheet Kratmel refers to:

 

I am all for doing unorthodox things, that is the way I have got around myriad problems over many years of designing lots of odd stuff.   You have obviously been implementing this setup OK before.  But I'd seriously consider changing the way you do it.   I'd run the pumps at full speed and institute a variable valve flow system with a pressure bypass back to the respective holding tank.  The pressure reliefs would be set equally so that the pumps don't get overworked.  Both the valves could be easily controlled by an analogue signal which would be available on a different samba model, which would be set before starting both motors concurrently.  Although this is still open loop, this method would likely give you much better flow control owing to consistency of mixing pressures.

cheers, Aus

 

[kratmel]

1 hour ago, Ausman said:

I'd run the pumps at full speed and institute a variable valve flow system with a pressure bypass back to the respective holding tank. 

Yes, it is maybe one of the best solution, Aus.

 

By the way, Up2-oil pump i offered by manufacturer in closed loop preprogrammed pressure variant.

https://www.clarksol.com/wp-content/uploads/2016/09/UP2.pdf

in another jabsco pump we see 15 max minutes working time limitation due to overheat!

 

We do not know that the developers of this design have an end goal.

What precision should be obtained,what costs of equipment are acceptable and what working time is predetermined?

However, I believe that the primary purpose of our communication is to help us understand what the Unitronics PLC

programmer can and cannot do to meet the above objectives.

SAMBA offer apropriate PWM condition for  MOSFET OUTPUT SSR. 

But i do not know about future result of motor performance with this control  setup.

Maybe this PWM must be used for proportional variable valve mentioned by Ausman.

[Joe Tauser]

A frequency of 1 Hz (as kratmel pointed out in your post from yesterday)  is way too slow for PWM of a motor, whether it's designed to handle it or not.

We still don't know exactly what you're doing.  Please post the latest version of your program.

Joe T.

 

[Ausman]

My brain was nagging me on this, saying I had something else.  After a few days of it running as a background process, I remembered what it was.

In case it might help, I've attached a copy of a very simple circuit I made ages ago (look at that T-Rex going past)  to run some 12v motors, that worked very well running just these types of motors at variable set speeds.  It was controlled by a simple relay switching matrix, but these days you could easily change it to speed control via a digital pot run by the Samba.  To run a number of digital pots you switch between serial lines using good quality mini relays with gold contacts.

I've labelled the main lines, but your electronics guys could consider the full ramifications and any mods needed.

cheers, Aus

[CobryWZL]

On 4/30/2020 at 5:49 PM, kratmel said:

 

Recomended max PWM Frequency D1D40<=950Hz,    D1D12<=4000Hz.

 

I am currently testing a little bit and the water pump reacts to the changing of the PWM parameters. If I set the parameter to frequency 500 and duty cycle 500 it works, but it doesn sound good. A lower frequency sounds much better, so i guess the above stated frequencies are way to high.

One thing that bothers me is: If i set the frequency to 0, the water pump still runs and for my ears it sounds quite good. So frequency = 0 is like a normal High or Low?

[kratmel]

Your control parameter is PWM Duty Cycle. 0=stop 1000=max.

You can run PWM on different frequency and  sound was different. The best solution is use HIGH PWM rate (above 2000Hz), but you SSR do not offer

above D1D40<=950Hz,    D1D12<=4000Hz.

Fequency (Hz)= 1/PWM cycle time (sec).   PWM cycle time (sec) = 1/Frequency(Hz).    If Freq=0,  PWM cycle time = infinite...

0 frequency = motor run on max voltage without PWM and  sound is quite good (you can connect motor direct to the power supply and result is the same).

 

As for me you must test motor in load condition.

 

[Ausman]

I've also remembered another option.  I converted a Honda trike to electric a while back and used parts from this supplier.  Some of their controllers might make all of this much easier.

cheers, Aus

https://www.motiondynamics.com.au/12v-48v-dc-speed-control-single-direction-25a-pcb-model.html#

[CobryWZL]

Hallo guys, just to bring this topic to and end:

We are currently using the above stated hardware to power both pumps. Both pumps can be controlled through PWM right now ( we found the freuqencies by testiing several) and it works quit good. The cable of the oil pump had a broken solder joint...so thats why it didnt work all the time.

When we'll change our wiring and give your suggestions a shot, I will return here and let you know!

 

Now we have another problem with flow counters that are installed behind the pumps ( see the attached files). The flow counters send a digital signal and every count is a 0. For each counter we have a signal cable and these signal cables are currently connected to I0 and I1.
Since the oil and the water are flowing now, I expected to get a signal from the flow counters. We are using the following code to count the pulses. But it counts nothing...

Any ideas? Thanks!

 

 

Duchflusszähler Konzentrat.pdf Zähler_Wasserkreislauf.pdf