Designing a Double DC Input Hybrid Energy Converter/Charger Circuit

The following post describes a simple idea which enables the processing of two different sources of DC inputs derived from different renewable sources. This hybrid renewable energy processing circuit also includes a boost converter stage which effectively raises the voltage for the required output operations  such as a charging a battery. The idea was requested by one of the interested readers of this blog.


The Request 

hi, i am a final year engineering student, i need to implement a multi input chopper (integrated buck/buck boost converter) for combining two dc sources(hybrid).i have the basic circuit model, can you help me to design inductor,capacitor values and control circuit for the chopper.This is the link for multi input chopper.http://www.archives-ijaet.org/media/5I4ANALYSIS-AND-CONTROL-OF-DOUBLE-INPUT-INTEGRATED-BUCK-BUCK-BOOST-CONVERTER-FOR-HYBRID-ELECTRIC-VEHICLES-Copyright-IJAET.pdf
regards
Gayathri
(gayastce@gmail.com)

Circuit Description.

As shown in the figure the IC555 sections are two identical PWM circuits positioned for feeding the adjoining double input boost converter circuit.

Following functions take place when the shown configuration is switched ON:

DC1 may be assumed as the high DC source such as from a solar panel.

DC2 may be assumed as alow DC input source, such as from a wind turbine generator.

Assuming these sources to be switched ON, the respective mosfets start conducting these supply voltages across the following diode/inductor/capacitance circuit in response to the gate PWMs.

Now since the PWMs from the two stages might beset with different PWM rates, the switching response will also differ depending upon the above rates.

For the  instant when both the mosfets receive positive pulse, both the inputs are dumped across the inductor causing a high current boost to the connected load. The diodes effectively isolate the flow of the respective inputs towards the inductor.

For the instant when the upper mosfet is ON while the lower mosfet is OFF, the lower 6A4 becomes forward biased and allows the inductor a return path in response to the switching of the upper mosfet.

Similarly when the lower moset is ON, and the upper mosfet is OFF, the upper 6A4 provides the required return path for the L1 EMF.

So basically, the mosfets can be turned oN or OFF irrespective of any kind of synchronization making things pretty easy and safe. In any case the output load would receive the average (combined) intended power from the two inputs.

The introduction of the 1K resistor and the 1N4007 diode ensures that the two mosfets never receive separate logic high pulse edge, though the falling edge may be different depending upon the setting of the respective PWMs of the 555 ICs.


The inductor L1 will need to be experimented with in order to get the desired boost at the output. Different number of turns of 22 SWG super enameled copper wire may be used over a ferrite rod or slab, and the output measured for the required voltage.

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