It's inaccurate to say that cells operate at different switching frequency in LS-SPWM. all cells are switched at a fixed carrier frequency, but in a discontinues switching mode (part-time chopping and part time conducting or misconducting). The term "average switching frequency" is used only for variable frequency PWM, such as hysteresis control. Here, a more suitable term would be either average of pulses per period, or, average switching losses, in which case they are about 1/(N-1) lower than switching losses of PS-SPWM operating at same carrier frequency and load, and not 1/N, as you claim. Also, there are more than one option to distribute the carriers. You can use only two carriers with two source signals 180 degrees out of phase.
for 5 level CHB you said the level shifting is 1/4 = 0.25, but in the graph the levels are shifted by 0.5 from -1 to 1 . I think the term modulation index is not clear here how it is calculated or defined there ? Why in first example with third harmonic injection Vpeak=0.5 however in your second example Vpeak=1 ?
It's inaccurate to say that cells operate at different switching frequency in LS-SPWM. all cells are switched at a fixed carrier frequency, but in a discontinues switching mode (part-time chopping and part time conducting or misconducting).
The term "average switching frequency" is used only for variable frequency PWM, such as hysteresis control. Here, a more suitable term would be either average of pulses per period, or, average switching losses, in which case they are about 1/(N-1) lower than switching losses of PS-SPWM operating at same carrier frequency and load, and not 1/N, as you claim.
Also, there are more than one option to distribute the carriers. You can use only two carriers with two source signals 180 degrees out of phase.
well explained cover each and every topic thank you sir
Thanks .
for 5 level CHB you said the level shifting is 1/4 = 0.25, but in the graph the levels are shifted by 0.5 from -1 to 1 . I think the term modulation index is not clear here how it is calculated or defined there ? Why in first example with third harmonic injection Vpeak=0.5 however in your second example Vpeak=1 ?
Thanks sir... nicely explained
Nicely explained. Very helpful video.
Course book?