Abnormal Inverter Current Under Inductive Load

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Sze Sing Lee
Sze Sing Lee on 30 Sep 2014
Moved: Walter Roberson on 2 Oct 2025 at 17:00
Hello, I had constructed a three-phase inverter in Simulink by using simpowersystems. The model worked completely fine with resistive load. However, under inductive load the load current is unbalance where phase a current is shifted up (positive offset) while phase b and c currents are shifted down (negative offset). Then, I constructed another model with same load connected to three-phase source and compared the voltage and current across the load in both models. It is observed that the voltage across the load for both models (one using inverter and another using three-phase source) are exactly same. However, the load current in three-phase source is normal while in the inverter it is not.
I'm so curious why the load and voltage across the load for both models are exactly same but they have different current. One is normal/correct while the other it is not. Please run the attached model and I look forward for any comments and suggestions.
Kind regards, Lee
  1 Comment
Bahadir
Bahadir on 15 Jan 2025
Moved: Walter Roberson on 2 Oct 2025 at 17:00
I have similar problem.
When I add 450VAR inductive load to 450W resistive load at 0,02 second, phase a and b currents shift up and phase c current shift down. why?
All loads is balanced. Why does current behavior like that? How can ı solve it?

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Answers (1)

Sabin
Sabin on 23 Dec 2022
The unbalance operation is caused by the Inductive reactive Power QL (positive var) parameter in the Three-Phase Parallel RLC load. Best to revise the system parameters and loads.

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