It's not simulation, but real circuit. Do u mean to connect a resistor between the opamp output and GND? Thanks.eltonjohn said:question is a real ciruit or just a simulation ..I see no load on the Op amp output!
I know... but both ends of the bh-loop have small loop, which is not available in bh-loop published by manufacturer or in textbook. How to get rid of the small loops? Is it cost by the circuit?yjkwon57 said:The saturation appears when most of fine grains are aligned.
Good observation... I agree with you that Y-T and X-Y plots in Fig. 4 should be almost in phase. For your information, the slope of the b-h loop was 'negative' initially. Then, I 'invert' the signal at ch2 or Vo to get the b-h loop with 'positive' slope. Probably I forget to set the 'invert' on when measured the Y-T signal. Actually I should swap the terminals of the secondary winding. I will try it out next week. Thanks.yjkwon57 said:Hi, powersys.
One thing strange is that Vo and Ip should be almost in phase according to the circuit, I think. In Fig. 4, two signals shows 180 phase difference in Y-T plot, but, shows 0 phase difference in X-Y plot. In Fig. 5, they are almost in phase in both Y-T and X-Y plots. Anyway, in the experiment using a small current shows a small distortion in Vo compared to the distortion in Vo in the experiment using a small current. Thus, I think there are some interferences in the circuit, which caused the small loops at the end of the bh-loop.
Would u pls advise what are 'Pi' and 'Io' in your reply?yjkwon57 said:In Fig. 1.18 of the reference book, i_m should be much larger than i_c, if it can be used as an inductor/transformer. Thus, one thing to be noted is that, although some distortion is formed, the peak of Vo is (almost) in phase with the peak of i_pi, which will not introduce some small loops at both ends of the B-H curve. In Fig. 1.19 (c) of the reference book, if e is a sine-wave voltage signal, i_m as well as i_pi, representing Ip in your circuit, should be sinusoidal. But, i_m1, contributing to the effective magnetic flux and representing Vo in your circuit, will not be sinusoidal. In Fig. 1.19 (a) of the reference book, Pi is selected as a sine wave, but, in your circuit, Io is selected as a sine wave. Thus, both are correct. The difference is the different selection of the reference sine-wave signals, I think.
I have pasted the actual text (describing Figures 1.18 and 1.19) frm the reference book above. May be it could help for our discussion here. Thanks.yjkwon57 said:Pi in Fig. 1.18 of the reference book is the magnetic flux represented by the biggest solid line with a sequence number circles, and the i_pi in Fig. 1.18 (a) is equivalent to Ip in your circuit. You said Ip should be always sinusoidal. That is absolutely right in your experiment with your circuit. But, the magnetic flux is not proportional to Ip, which is not explained in the reference book. The magnetic flux is proportional to a current component depicted as i_pi1 in Fig. 1.18 (a) and i_m1 in my previous explanation. I used the symbol i_m1 just as i_pi1 in the reference book. The coupling magnetic flux will be distorted and the Vo also will be distorted in your experiment. Restating my previous description, in Fig. 1.19 (c) of the reference book, if e is a sine-wave voltage signal as in your experimental situation, i_m as well as i_pi represented as Ip in your circuit, should be sinusoidal. But, i_m1, contributing to the effective magnetic flux and represented as Vo in your circuit, will not be sinusoidal. If Pi in Fig. 1.18 and Fig. 19 of the reference book is to be sinusoidal, e in the same figure is not to be sinusoidal, i.e., to be distorted. Thus, I think e curve might be modified.
I think my comment (highlighted in red) is wrong. The correct one should be: Ip will be distorted when the core is saturated.powersys said:Would u pls advise what are 'Pi' and 'Io' in your reply?yjkwon57 said:In Fig. 1.18 of the reference book, i_m should be much larger than i_c, if it can be used as an inductor/transformer. Thus, one thing to be noted is that, although some distortion is formed, the peak of Vo is (almost) in phase with the peak of i_pi, which will not introduce some small loops at both ends of the B-H curve. In Fig. 1.19 (c) of the reference book, if e is a sine-wave voltage signal, i_m as well as i_pi, representing Ip in your circuit, should be sinusoidal. But, i_m1, contributing to the effective magnetic flux and representing Vo in your circuit, will not be sinusoidal. In Fig. 1.19 (a) of the reference book, Pi is selected as a sine wave, but, in your circuit, Io is selected as a sine wave. Thus, both are correct. The difference is the different selection of the reference sine-wave signals, I think.
I still feel that somethings wrong in Figure 1.18 and Figure 1.19. In my opinion, the Ip should be 'always' in sinusoidal, and the flux (which is represented by Vo in my circuit) will be distorted when the core is saturated due to high MMF, which is proportional to Ip. What's your opinion?
Thanks.
Hi yjkwon57,yjkwon57 said:Hi, powersys.
But, in your experimental circuit, Ip shold be sinusoidal. Analyzing the circuit based on the electronics, Ip should be sinusoidal to my knowledge.
But the Vin is an AC power supply, and jwL counts, right? Pls correct me if I'm wrong. Thanks.yjkwon57 said:Hi, powersys.
We are condidering a steady-state circuit solution rather than a step-input response. In your circuit, we are watching a steady-state response of your experimental circuit.
Added after 2 minutes:
In the reference book, the author also tries to solve the circuit to get a steady-state picture.
Did u mean Ip should be ALWAYS sinusoidal? Pls enlighten me how did u come to this conclusion... Thanks.yjkwon57 said:Hi, powersys.
But, in your experimental circuit, Ip shold be sinusoidal. Analyzing the circuit based on the electronics, Ip should be sinusoidal to my knowledge.
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