Single phase inverter-current control loop

[hisham.i]

Hello

I am designing single phase inverter with TMS320LF2406 DSP.

I created sinusoidal output voltage, and now i want to make regulation.

While reading about regulation i found that it is recommended to use outer loop as voltage loop to generate Iref using PI controller, then this Iref is entered to inner loop ( current loop) where its output is entered to another PI controller to generate the PWM duty cycle.

What is the advantage of using the inner current loop? why we cannot only use the voltage control loop to determine the duty cycle?

Regards,

Hisham Issa

 

[anorlunda]

That recommendation applies only sometimes.

Since the load participates in the dynamics, then you can't design the controller without consideration of the load. If you don't know what the load wlll be, you could assume just a resistor R. In that case, Ohm's law locks you into V=IR, so you can't control V and I independently.