Programming a duty cycle in CFX

merper · October 2, 2013, 17:17

Ok, I'm guessing this is probably a simple thing to implement, but I've spent all morning searching and can only jury rig a solution so far. How do I use a loop or create and expression to turn a boundary condition on and off for 10, 20, 30...% of the time.

Right now, I'm using a simple if statement to create the cycle:

.6253 [V] - if(atstep >(DutyCyclePercentage*.8[s]/10)/TimestepSize, .6253 [V], 0 [V]) +if(atstep > 8[s]/TimestepSize,.6253[V],0[V])- if(atstep >(8[s]+DutyCyclePercentage*.8[s]/10)/TimestepSize, .6253 [V], 0 [V]) + if(atstep >16[s]/TimestepSize,.6253[V],0[V])-.....

but I basically have to repeat this over and over for the length of my simulation. How do I simplify this with a loop? I can't find the syntax.

ghorrocks · October 2, 2013, 18:10

Use the mod function to work out where in the current cycle you are. Then do a single if statement on that value to get a repeating duty cycle signal.

merper · October 2, 2013, 18:34

Ah, so simple. Yeah thanks.

if(mod(atstep,cyclelength),true,false)

October 2, 2013, 17:17	Programming a duty cycle in CFX	#1
merper New Member Anon Join Date: Oct 2013 Posts: 5 Rep Power: 12	Ok, I'm guessing this is probably a simple thing to implement, but I've spent all morning searching and can only jury rig a solution so far. How do I use a loop or create and expression to turn a boundary condition on and off for 10, 20, 30...% of the time. Right now, I'm using a simple if statement to create the cycle: .6253 [V] - if(atstep >(DutyCyclePercentage.8[s]/10)/TimestepSize, .6253 [V], 0 [V]) +if(atstep > 8[s]/TimestepSize,.6253[V],0[V])- if(atstep >(8[s]+DutyCyclePercentage.8[s]/10)/TimestepSize, .6253 [V], 0 [V]) + if(atstep >16[s]/TimestepSize,.6253[V],0[V])-..... but I basically have to repeat this over and over for the length of my simulation. How do I simplify this with a loop? I can't find the syntax.

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October 2, 2013, 18:10		#2
ghorrocks Super Moderator Glenn Horrocks Join Date: Mar 2009 Location: Sydney, Australia Posts: 17,703 Rep Power: 143	Use the mod function to work out where in the current cycle you are. Then do a single if statement on that value to get a repeating duty cycle signal.

October 2, 2013, 18:34		#3
merper New Member Anon Join Date: Oct 2013 Posts: 5 Rep Power: 12	Ah, so simple. Yeah thanks. if(mod(atstep,cyclelength),true,false)