Author Topic: Royer/Mazzilli oscilator theoretical operation  (Read 1479 times)

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Offline drdmTopic starter

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Royer/Mazzilli oscilator theoretical operation
« on: January 11, 2020, 01:28:09 pm »
Hello everybody,
I have to build a power supply that needs to be powered by a battery and provide about 1500V with output current in the micro ampere range. It is for an university assignment, so I have to provide proper calculations and documentation with it. the PS is composed of a Buck converter that feeds Royer/Mazzilli oscillator which in turn powers a Cockroft-Walton multiplier. Output voltage is to be taken from the output and used to regulate the Buck (still no idea how to do that, but we'll get there :)). For weeks I've been browsing the internet and some books and I can not find a proper theoretical explanation on the Royer/Mazzili oscillator. How do you choose the right components? How do you calculate currents and voltages? How do you calculate the impact of the load? How do you regulate the output voltage?
I know the the difference between Royer and Mazzilli is the way the Switching components are driven, so I am using a Mazzilli oscillator, but I find that they are quite similar.
I have attached the schematic I am using. It's based on a simulation that I found in this forum. So here are my questions (there are a lot):
1. L1 is 2mH while transformer windings are 1uH each. L1 is supposed to keep the input current smooth, but why does the oscillator need constant input current? How do I calculate (or at least justify) that 2mH (why not 1mH or 3mH)? Also how do I calculate the peak current of L1?
2. How do I find the peak voltage in points A and B with respect to GND? In one source I found out that that it is the input voltage times 3.14(pie), but why?
3. How is the current trough Q1 and Q2 calculated? In the simulation it is constant during the ON period, I am guessing due to L1.
4. How does V_OUT depend on R_LOAD and V_IN?
5. Can I model the Load resistance to be in parallel with C1?
6. I red that the circuit oscillates with the resonant frequency of C1 and the transformer primary winding (FG). Is that true, because the simulation shows a different result?
7. Can I somehow calculate the peak currents trough the transformer?
I hope the topic is not too wide and is posted in the right section. Thank you n advance to anyone who is willing to help?
Best regards!
907274-0
 

Offline magic

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Re: Royer/Mazzilli oscilator theoretical operation
« Reply #1 on: January 11, 2020, 03:45:48 pm »
Seems rather complex for a job that a simple one stage flyback could do.

Getting or making the transformer would be the only tricky part as your voltage is above laptop CCFLs as far as I know but below automotive or CRT flybacks on the other hand.
 

Offline drdmTopic starter

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Re: Royer/Mazzilli oscilator theoretical operation
« Reply #2 on: January 11, 2020, 04:29:37 pm »
I agree that it is complex, but what can you do? It's an assignment :). The Cockroft-Walton is necessary due to the type of load, but that oscillator caught me off guard. |O 
 


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