timestep too small and Input Power Factor cannot be got

[zhang24408]

Hi All

I've just started using multisim 2001 to simulate Electronic Ballast circuits and am having trouble.

About Double-Stage Electronic Ballast circuit,it works well before using EMI circuit,but I get a "timestep too small" error message after using EMI circuit.

About Single-Stage Electronic Ballast circuit,it also works well before using Wattmeter,so I cannot get input Power Factor.Besides, I try to add EMI circuit, but noting works.

I attached my circuit to this email, could someone please give me some assistant? I would be really appreciated

Thanks

[lacy]

I just finished solving the problem. It took a little time to isolate. What you need to do is replace all the virtual diodes with ones with models.This is what was causing the error.  I modified your circuit to use 1N4005 which is general purpose diode with a Breakdown Voltage of 660V. You can choose any diode with a model that suits your purpose.  This is for the double stage circuit. I am still working with the single stage. The circuit is below:

Message Edited by lacy on 08-26-2007 09:32 AM

[lacy]

I don't know if your going to be able to measure the wattage in the manner that your doing it. I checked the current draw off the source and it is not stable. If the current draw isn't consistent then you will not be able to get an accurate reading with the wattmeter. You can't even figure it with P=E/I without a fairly stable current. Both circuits exhibit this behaviour. 

I have tried everything I can think of.

If someone else has a suggestion to help please post it.

[lacy]

I mess up my formula it should have been P=E*I. Sorry for the error. Unless you can figure out a way to stabalize the current draw from the source, I can't see a way of measuring this. The current is just fluctuating to wildly.

[zhang24408]

Maybe we can change the topology.

[lacy]

I have tried something, but I am still not sure I am getting accurate readings. What I did was to remove the bridge rectifiers and the AC Voltage source and replace them by a DC power source at the same voltage value. It seems to stablize the reading, but I am not sure how reliable it is or if that is what it should be. What I will do is post the two circuit for you and let you look at them. It takes a little bit for the reading to stabalize so just be patient.

Here they are: