I am building a DC-DC push-pull converter which is sourced bu a PV panel. I am having really hard time on designing the transformer. I searched and read lots of articles and books but could not find a proper way to design.
The transformer will be center tapped only at primary side.
The switching frequency is 35 kHz(i can increase it to the 50 kHz )
The Voltage of panel will vary between 25-45 V.
According to panel and irradiation there is a MPPT algorithm that outputs a Duty Cycle which is for the extract most power from PV panel.
When i simulate it, when i used a panel that has 25 V at max power point the duty cycle is around 48% (50% is the max value you know) and when i used a panel that has 45 V at max power point the duty cycle is around %30.
The output of the converter will be 400V .
How do i start to calculate and so on?
I will be appreciate any advice and it is my graduation project from university and i need to graduate :)))
Did you try "Inductors and Transformers for Power Electronics- Van Den Bossche"? It's a really good reference.
Design of Transformer and Power stage of Push-Pull Inverter
http://electronics.etfbl.net/journal/Vol13No1/xPaper_04.pdf
Check the following reference Please.. it might's assist you in your question …
http://electronics.etfbl.net/journal/Vol13No1/xPaper_04.pdf
First of all, you have to make a good choice for the turns' number of the two coils, because that will determine the maximum output voltage when the duty cycle is max (0.5). So if you want an output voltage 400 Volt, calculate the coils (of the transformer) with 0.9 duty cycle and with lowest input voltage. Then I would suggest you to use a sawtooth wave (the peak of this wave you have to calculate from the duty cycle equation) to compare the input voltage and finally to generate pulses. If input voltage is getting smaller, duty cycle will grow.
If you use matlab, try to start the simulation with a simple dc source. Don't make big steps. Smaller are better.
Some of the major drawbacks of Voltage-fed converter can be resolved by its Current-fed counterpart with its certain practical advantages. The recent increase in interest and use of current-fed converters calls for establishing a systematic design methodology.
Voltage-fed isolated converter topologies have some serious drawbacks. They invariably consist of input capacitor to lower input voltage ripple & spikes and output low-pass filter to reduce output voltage ripple. This low-pass filter consists of an inductor in series with the secondary rectifier assembly, along with the shunt capacitor.
See book, Power Magnetics Design Optimization, D. Feucht, www.innovatia.com
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