Hi priya,
I understand that you are using FOC with SVPWM and trying to implement two-zone overmodulation where you want to enable six-step operation when MI exceeds linear/overmodulation limits.
From the give information above, I can defer that following could be the issues with SVPWM not switching to six-step even at high MI:
- Reference voltage might be clamped or mis-scaled.
- PWM generator might not be configured for full six-step logic.
You can try the following measures to move into six-step at high MI:
1. You can try switching to six-step mode when MI>1.0-1.05, else stick to SVPWM. This detects the overmodulation region.
2. Implement six-step using 6 sectors (60* each) based on rotor angle with hard switching of phase voltages.
3. You can verify that your system ensures full 0-100% duty cycle and that dead time is active.
You can read more about "SVPWM" here: https://www.mathworks.com/help/sps/powersys/ref/svpwmgenerator2level.html
You can read more about Field-oriented Control ("FOC") here: https://www.mathworks.com/help/mcb/gs/implement-motor-speed-control-by-using-field-oriented-control-foc.html?searchHighlight=FOC&s_tid=srchtitle_support_results_1_FOC
Hope it helps!
