Hello,
This question pertains to Matlab simulation. I will be grateful in case anyone knows the answer.
Attached .docx file is a Simulink circuit of a inverter simulation. In order to implement close loop control of inverter, I first make it work as rectifier and trying to do its PLL and current control loop implementation. In this quest, I am applying a voltage through a grid and modify it to another level by transformer. I am not able to figure out that after putting any Kp and Ki values, why does the input current waveform shape is not symmetrical? Can any one help me to find the problem? In another file, I have attached Voltage (Upper) and current (Down) waveform taken from grid. The corresponding scope is marked in .docx file.
Regards
Aalok
you can manage to do PLL by help of a zero crossing detector circuit by using opamps. you can apply a voltage source from grid and pass through zero-crossing detector and compare your waveform with your PWM gate pulse and than the resultant will be provided to fire the inverter switches
Hello Jitendra,
Thank you for inputs. However, I have already implemented PLL via dq transformation. Now I am at the point to tune the current control loop. At that moment, I get distorted current itself from grid and therefore, dq transform is not able to convert properly. I am wondering how come the distortion from ideal grid comes?
Try using Yn instead Yg on the transformer and connect the source N and the transformer N together.
Hello Gopal,
Vielen Dank. Good Input. I did connect N of Trafo as well as Grid with and without grounding. However, no change in the waveform. The waveform is shifted from eachother as seen in the figure attached. I have limited the Grid power to 630kW which is my desired rating. Inspite of that, the current taken is enormous. I think I can work out large current value once the waveform distortion gets resolved.
Regards,
Aalok
A single line diagram of your problem is required for better analysis.
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