I understand that the pole voltage phase shift is 120degrees for 3 phase and the line to line voltage is equal to the difference in 2 pole voltages. However, how do I work out the phase shift between a pole voltage (say phase a) and the line to line voltage (vab)?

Thank you.

  • 1
    \$\begingroup\$ Curious: Why do you have inverter, modulation and PWM as tags? \$\endgroup\$ – KingDuken Apr 24 '17 at 1:01
  • \$\begingroup\$ Because the background/area of where my question originated from is for a 3 phase inverter with bipolar sinusoidal PWM modulation. \$\endgroup\$ – user3447255 Apr 24 '17 at 13:40

This site has a nice picture that explains why there is a 30 degrees phase shift between phase and line voltages: -

enter image description here

For instance, Vca is the addition of Voc and Voa and this produces a phase shift that is 30 degrees lagging to Voa.

If you are not familiar with phasor diagrams then I recommend that you become familiar. It will be time well-spent and it's just half an hour of your life and a few simple lessons in geometry.


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