exponential increase in wave form in three phase grid connected svpwm

for the three phase grid connected system for the svpwm i have used the angle from pll, sector selection is also obtained using pll,vdc of 400v and Ts=1/10000. i have used current controller for obtaining vref. i'm experiencing exponentially increasing waveform in vref. what should i do to settle it down

Answer 1

[praguna manvi]

Hi @PARADESI,

Exponentially increasing "vref" waveform likely indicates instability in the control loop, here are the checks that can be performed to troubleshoot:

1. Control Loop Gain: Ensure that the gains in your current controller are not too high, which can cause instability. Try reducing the "Ki" (integral) and "Kp" (proportional) gains. For more information refer to this link on desigining a current controller: https://www.mathworks.com/help/mcb/ug/design-current-controller.html
2. PLL Stability: Verify that your Phase-Locked Loop (PLL) is correctly tuned and stable, providing an accurate phase angle. Refer to the a documentation on "PLL testbench": https://www.mathworks.com/help/msblks/gs/DesignAndEvaluateSimplePLLModel.html