Alright everyone, here is my situation. I am playing around with a design I found on true sine wave inverters, found here: http://www.wpi.edu/Pubs/E-project/Available/E-project-042507-092653/unrestricted/MQP_D_1_2.pdf, to see how I can make a 3 phase inverter. At the time I found the above paper I was looking into inverters and PWM systems trying to learn more about them and ultimately SMPSs. I am looking at books to purchase in the relatively near future on SMPS and PWM systems to gain a deeper understanding of them.
This "project" is mostly just theory for now so I wanted to make sure I was understanding everything properly. I altered the design slightly to use a wein bridge oscillator versus a bubba oscillator. So with that basis, here is the meat.
Using an op-amp phase shift circuit I found here, http://www.tedpavlic.com/teaching/osu/ece209/lab1_intro/lab1_intro_phase_shifter.pdf, I began puting information regarding phase angle (e.g. 60, 120, 180, 240, and 300) into excel and using the equation \(\frac{tan(\frac{x \cdot \pi}{180})}{2 \cdot \omega \cdot y}\) (where y either = c in farads or r in ohms depending what you wish to solve for and x = phase shift in degrees). I noticed something intriguing. for a phase shift of 120° and 240°, the values I solve for are the same only one is negative. If I am understanding this right, this means that after I phase shift the signal by 120° I should use a unity gain inverting amplifier to get my 240° phase shift. I assume for sinusoidal signals and square waves, an inversion is equivalent to a phase shift of 180° (inversion not always being equivalent with certain signals).
Is my thinking correct with this? It has been some time since I worked with op-amps and signals so I want to make sure.
This "project" is mostly just theory for now so I wanted to make sure I was understanding everything properly. I altered the design slightly to use a wein bridge oscillator versus a bubba oscillator. So with that basis, here is the meat.
Using an op-amp phase shift circuit I found here, http://www.tedpavlic.com/teaching/osu/ece209/lab1_intro/lab1_intro_phase_shifter.pdf, I began puting information regarding phase angle (e.g. 60, 120, 180, 240, and 300) into excel and using the equation \(\frac{tan(\frac{x \cdot \pi}{180})}{2 \cdot \omega \cdot y}\) (where y either = c in farads or r in ohms depending what you wish to solve for and x = phase shift in degrees). I noticed something intriguing. for a phase shift of 120° and 240°, the values I solve for are the same only one is negative. If I am understanding this right, this means that after I phase shift the signal by 120° I should use a unity gain inverting amplifier to get my 240° phase shift. I assume for sinusoidal signals and square waves, an inversion is equivalent to a phase shift of 180° (inversion not always being equivalent with certain signals).
Is my thinking correct with this? It has been some time since I worked with op-amps and signals so I want to make sure.