MPPT and DC-DC converter fixed output voltage

[goksinb]

Hi everybody, can someone say me that how can we achieve DC-DC converter fixed output voltage while we change duty cycle of DC-DC converter for MPPT. We know that for MPPT we must changes duty cycle of DC-DC converter but we also need some fixed voltage at the output of DC-DC converter to achieve a fixed voltage at the input of the DC-AC inverter. Thanks

Baris

 

[FvM]

Think!

Regulating a converter for constant output voltage means that the load commands the transferred power. But if the input power is restricted, the output voltage can be only maintained as long as the load power demand is below the available source power.

A MPPT algorithm is necessary though to guarantee that the available power is actually utilized. The solution could be a MPPT regulator with additional output voltage limiting.

 

[goksinb]

Think!

Regulating a converter for constant output voltage means that the load commands the transferred power. But if the input power is restricted, the output voltage can be only maintained as long as the load power demand is below the available source power.

A MPPT algorithm is necessary though to guarantee that the available power is actually utilized. The solution could be a MPPT regulator with additional output voltage limiting.

I mean that when we design a solar inverter; MPPT and DC-DC and DC-AC conversion are used. MPPT used for maximum power tracking. To achieve MPPT you changes duty cycle of DC-Dc converter. But you need a fixed voltage like 311V to achieve 220V output voltage at the output of DC-AC inverter. I couldnt understand how can inverter companies achieved this fixed output voltage while they change duty cycle for MPPT.

 

[rudr_p]

I think that is because maxim power point changes continuously which are always at different voltage and which also has changes the current. So if the panel voltage is more than nominal then I decrease the duty cycle to achieve the constant dc output and if voltage is less then nominal I increase the duty cycle to achieve the output voltage which is 311V in your case. You can find many paper about this topic and also you must read some TI or some companies app note about constant voltage dc/dc converter.