Circuit Design

[hy_scorpio]

Hello all,

I would like to seek help in circuit design as I'm currently working on my Final Year Project for my undergraduate studies.
Currently, I'm designing a circuit that produces a constant 5V output from the voltage produced by an AC generator.

This is how my project works:

AC Generator produces AC Voltage -> Bridge rectifier with capacitor filter (to produce a DC Voltage) -> Buck Boost Converter -> USB Output 

My input voltage varies from 3V - 5.7V while my input current is approximately 0.6A-0.7A.

I have a few doubts regarding this simulation.

1) With the input voltage and input current above, what component should I use as power source? If I use a function generator, the voltage can be fixed at 6V peak but the current cannot be varied. Will this affect my simulation results?

2) I am in the midst of building a bridge rectifier. However, the Schottky diode that I use CRS08(Q) from Toshiba is not available in Multisim. I have checked the manufacturer's website for SPICE model but I couldn't find any. Can anyone help me out here?

3) With the Schottky Diode problem, I'm also worried for the buck boost converter that I'm planning to use. I was thinking of using a Switching Regulator with automatic PWM to ensure I'll get a constant 5V. I have looked through a few manufacturers but most of them do not have SPICE model for it too. Please advise me.

[derekdb]

Hello,

It seems that you have a very interesting design topic. Here are just some comments on your questions:

1. There's currently no power supply that can be used to limit the current flowing through it. Your best bet is to calculate the equivalent impedance of your circuit and apply Ohm's law. 
2. I couldn't find the Toshiba Schottky diode either. You may contact the manufacturer for the resource. However, there are quite few models around on the Internet. Maybe you can check them out if some of them can be an alternative. The one I found is: http://forum.allaboutcircuits.com/newsgroups/viewtopic.php?t=974
3. There are quite a few switching regulators in MS version 12, but I didn't see any with PWM. Maybe you can try some other alternatives?

Hope your design project goes well.