Hjalli Sig Posted August 10, 2012 Report Share Posted August 10, 2012 Hello V 350-35-T2 Im configuring the highspeed output PWM. The Duty cycle i understand, from 0 to 1000 or 0-100% but i dont understand why i need to input the frequency ( is the frequency not constantly changing regarding the speed im trying to maintain! Quote Link to comment Share on other sites More sharing options...
Emil Posted August 11, 2012 Report Share Posted August 11, 2012 Sorry, it's not clear what you mean. Please explain. Who gives you the speed you need to mentain? Ho it's related to HSO? Quote Link to comment Share on other sites More sharing options...
guttih Posted August 16, 2012 Report Share Posted August 16, 2012 Hjalli Sig is talking about the output frequency (The HSO frequency). We are not sure how to configure it. After testing by changing HSO frequency and testing it with a different HSO Duty Cycles. It seems that if I give it the value 90 It behaves like i want, but I don't know why. Quote Link to comment Share on other sites More sharing options...
Damian Posted August 18, 2012 Report Share Posted August 18, 2012 Hello V 350-35-T2 Im configuring the highspeed output PWM. The Duty cycle i understand, from 0 to 1000 or 0-100% but i dont understand why i need to input the frequency ( is the frequency not constantly changing regarding the speed im trying to maintain! If you are using the PWM function block with an output then you should not be setting up that ouput in the hardware config as an HSO. The PWM block is meant to modulate a single ouput on and off at the selected cycle time and duty. If you want the hardware HSO to be cotnrolled by your PID output then all you need to do is link your PID output to your HSO "duty cycle" operand and just select an appropriate frequency. Quote Link to comment Share on other sites More sharing options...
Hjalli Sig Posted August 18, 2012 Author Report Share Posted August 18, 2012 If you are using the PWM function block with an output then you should not be setting up that ouput in the hardware config as an HSO. The PWM block is meant to modulate a single ouput on and off at the selected cycle time and duty. If you want the hardware HSO to be cotnrolled by your PID output then all you need to do is link your PID output to your HSO "duty cycle" operand and just select an appropriate frequency. The problem is to set the appropriate frequency! We are trying to control a hydro-turbine that runs on 50-60 Hz, we use a heater tube elements connected to the SSR and the OPLC PID-fb to controle the speed of the turbine to generate max power all the time. when we use the power for other things the PID controler loads the heater tube less to ceep up the speed that is set 55HZ . The question is! The frequency to the to the elements ( power side of the SSR ) changes from 50-60Hz will that affect the set frequency i seleted on the controler ? Quote Link to comment Share on other sites More sharing options...
Damian Posted August 21, 2012 Report Share Posted August 21, 2012 It won't affect the set frequency selected on the controller. Generally you will want your PWM frequency to be appreciably slower than the oscillating frequency of the power you are switching. I would not use the hardware HSO for this. I get the impression you are trying to sychronize your switching with the generators cycle, which Is probably beyond the capability of the control. I would recommend you use a Zero-Cross phase angle SCR style swtiching device controlled with an analog signal such as 4-20mA. Then just have the PID block source your analog output as opposed to PWM. You will get much more stable operation. Especially if you get an SCR with a linear input to power relationship. Quote Link to comment Share on other sites More sharing options...
guttih Posted August 21, 2012 Report Share Posted August 21, 2012 After reading the in the PID Tips in the Visilogic helpfile I think we need to set the The HSO frequency value to 4. In the helpfile is written: If you use an SSR, you can use a Unitronics PLC that supports a high-speed output. In Hardware Configuration, set the Frequency (F=1/CT) parameter's Power-up Value to 5 to 10Hz ( which is 0.2 -0.1s cycle time). Link the PWM Duty Cycle MI to the CV. Note that in order to activate the output pulses, you must SET the RUN MB linked to the HSO in Hardware Configuration. Quote Link to comment Share on other sites More sharing options...
Emil Posted August 21, 2012 Report Share Posted August 21, 2012 HSO Frequency below 5 is not legal value. HSO will not operate with such value. Quote Link to comment Share on other sites More sharing options...
guttih Posted August 21, 2012 Report Share Posted August 21, 2012 Then I will set it to 5. Thanks Quote Link to comment Share on other sites More sharing options...
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