For the loop bode plot, why does the phase shift start at -90 degrees at low frequencies instead of -270 degrees or +90 degrees. Shouldn't the negative in the Type-III Compensator transfer function (due to the inverting opamp) cause an additional -180 degree phase shift on top of the -90 degree phase shift from the pole at the origin?
Okay I saw in a comment you mentioned the calculations are different between MATLAB and Tina-TI. Do I need to account for the 180-degree phase shift in MATLAB, because having a phase shift starting at 90 degrees is confusing when calculating stability margins.
@@jadondewey1237 Thanks for your message. -90 degrees + -180 degrees is in totaal -270 degrees, but can be also written as +90 degrees by adding a 360 degrees.
@@CanBijles Thank you for your answer. Why does the phase bode plot for the loop at the end of the video start at -90 degrees instead of +90 degrees then?
@@jadondewey1237 MATLAB and TINA-TI Spice use a different phase polarity for the inverting error amplifier. MATLAB considers the phase reversal of the error amplifier as 180 degrees and not as -180 degrees, which is in effect the same. At DC, the phase of the compensation network is -90 degrees and with 180 degrees from the error amplifier make it -90 degrees.
Thank you very much. I made an adjustable power supply unit for TL494. 0-27 V; 0-12A.I calculated the phase compensation for the first voltage error amplifier according to your methodology. It works perfectly! The second error amplifier operates on current limitation and short circuit protection. The shunt is in the circuit on the underside, after the load resistance. A small voltage proportional to the flowing current goes from it to the input of the operational amplifier. Please tell me, can I calculate compensation for the second error amplifier using this technique? What should be taken into account, because in this case we take the feedback signal not from the capacitor, but from the lower side of the load resistance? I'm sorry, I have to work with a translator.
Thanks for your message. Great to know that the method works! I will need some time for this. Maybe you can send me some details via mail can.mehmet.tr@gmail.com so I can give a better answer. I will let you know coming week.
This question came up before, so I will copy paste the answer I have given then: 1. Compensation network (Type 3 network) is a third-order system, so it can provide 270 degrees. 2. MATLAB and TINA-TI Spice use a different phase polarity for the inverting error amplifier. MATLAB considers the phase reversal of the error amplifier as 180 degrees and not as -180 degrees, which is in effect the same. At DC, the phase of the compensation network is -90 degrees and with 180 degrees from the error amplifier make it -90 degrees. 3. Before we use the formula to calculate the K Factor, we add a phase of 180 degrees to get the phi_comp to compensate for the phase inversion in the error amplifier's inverting amplification. This is also described in this video when we discuss the calculations and simulations. More details are given in this video or a similar video via this link: ⚡ DC-DC Buck Converter Design Part 2 ⚡ - Controller Design - Calculations & MATLAB & TINA-TI: th-cam.com/video/p5q5jMvsjto/w-d-xo.html
That is correct. One note: before we use the formula to calculate the K Factor, we add a phase of 180 degrees to get the phi_comp to compensate for the phase inversion in the error amplifier's inverting amplification. This is also described in this video when we discuss the calculations and simulations.
@@patrickliew2756 In MATLAB, the phase contribution by the compensator G_comp is 24 degrees at 10 kHz, which is close to the actual crossover frequency (unity-gain frequency). The phase of the loop transfer function G_loop is -122 degrees, which means that the phase margin is 58 degrees. Remember that phase calculations in MATLAB and TINA-TI Spice are different; TINA-TI Spice will add an extra 180 degrees to compensate for the phase inversion of the inverting amplifier. The basic idea is the same.
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For the loop bode plot, why does the phase shift start at -90 degrees at low frequencies instead of -270 degrees or +90 degrees. Shouldn't the negative in the Type-III Compensator transfer function (due to the inverting opamp) cause an additional -180 degree phase shift on top of the -90 degree phase shift from the pole at the origin?
Okay I saw in a comment you mentioned the calculations are different between MATLAB and Tina-TI. Do I need to account for the 180-degree phase shift in MATLAB, because having a phase shift starting at 90 degrees is confusing when calculating stability margins.
@@jadondewey1237 Thanks for your message. -90 degrees + -180 degrees is in totaal -270 degrees, but can be also written as +90 degrees by adding a 360 degrees.
@@CanBijles Thank you for your answer. Why does the phase bode plot for the loop at the end of the video start at -90 degrees instead of +90 degrees then?
@@jadondewey1237 MATLAB and TINA-TI Spice use a different phase polarity for the inverting error amplifier. MATLAB considers the phase reversal of the error amplifier as 180 degrees and not as -180 degrees, which is in effect the same. At DC, the phase of the compensation network is -90 degrees and with 180 degrees from the error amplifier make it -90 degrees.
Thank you very much. I made an adjustable power supply unit for TL494. 0-27 V; 0-12A.I calculated the phase compensation for the first voltage error amplifier according to your methodology. It works perfectly!
The second error amplifier operates on current limitation and short circuit protection. The shunt is in the circuit on the underside, after the load resistance. A small voltage proportional to the flowing current goes from it to the input of the operational amplifier.
Please tell me, can I calculate compensation for the second error amplifier using this technique?
What should be taken into account, because in this case we take the feedback signal not from the capacitor, but from the lower side of the load resistance?
I'm sorry, I have to work with a translator.
Thanks for your message. Great to know that the method works! I will need some time for this. Maybe you can send me some details via mail can.mehmet.tr@gmail.com so I can give a better answer. I will let you know coming week.
@@CanBijles Well, I will definitely write to you
How come type 3 compensator can provide 201 deg phase ??
This question came up before, so I will copy paste the answer I have given then:
1. Compensation network (Type 3 network) is a third-order system, so it can provide 270 degrees.
2. MATLAB and TINA-TI Spice use a different phase polarity for the inverting error amplifier. MATLAB considers the phase reversal of the error amplifier as 180 degrees and not as -180 degrees, which is in effect the same. At DC, the phase of the compensation network is -90 degrees and with 180 degrees from the error amplifier make it -90 degrees.
3. Before we use the formula to calculate the K Factor, we add a phase of 180 degrees to get the phi_comp to compensate for the phase inversion in the error amplifier's inverting amplification. This is also described in this video when we discuss the calculations and simulations.
More details are given in this video or a similar video via this link:
⚡ DC-DC Buck Converter Design Part 2 ⚡ - Controller Design - Calculations & MATLAB & TINA-TI: th-cam.com/video/p5q5jMvsjto/w-d-xo.html
@@CanBijles Many Thanks 🙏
You are welcome.
How to make simulation with LTspice
I do not use LTSpice.
It is ok to apply this method to a boost converter design? Im designing now a two phase interleaved boost converter, and i need to compensate it...
Yes, you can use this method for other converter types also.
Hello, if i wanted to have a phase boost of 120 degree then based on 13:12 the G_comp should be 120 degree?
That is correct. One note: before we use the formula to calculate the K Factor, we add a phase of 180 degrees to get the phi_comp to compensate for the phase inversion in the error amplifier's inverting amplification. This is also described in this video when we discuss the calculations and simulations.
Sorry i mean at 30:40. Currently your designed compensator has a phase boost of 114 degree?
@@patrickliew2756 In MATLAB, the phase contribution by the compensator G_comp is 24 degrees at 10 kHz, which is close to the actual crossover frequency (unity-gain frequency). The phase of the loop transfer function G_loop is -122 degrees, which means that the phase margin is 58 degrees.
Remember that phase calculations in MATLAB and TINA-TI Spice are different; TINA-TI Spice will add an extra 180 degrees to compensate for the phase inversion of the inverting amplifier. The basic idea is the same.
@@CanBijles May I ask therefore the phase boost of the compensator design is 24 degree?