I'm designing a push-pull amplifier where the center-tap on the primary is connected to +15V and each end of the primary will go through a low-side MOSFET to ground. On the secondary, I will have a 75ohm load. The goal is to get a +/-15V pulse across the load with a source voltage of 15V. Note I am not counting for losses here, just theoretical.
I have found a datasheet (T-51117) for a "2CT:1" transformer which claims to have an "OCL" value of 5mH. I'll assume this OCL value of 5mH is the inductance across the full primary.
Since the relationship between turns and inductance is given by the equation: Ns/Np = sqrt(Ls/Lp) and we know that Ns/Np = 1/2 and Lp = 5mH. This must mean that Ls = 1.25mH.
Now here is where things fall apart for me. If we assume that the center tap cuts the number of primary windings in half, then each half-primary to secondary should make a 1:1 transformer since they both have equal turns (the full primary has twice as many turns as the secondary). Since we just calculated the secondary to be 1.25mH, each half primary should also be 1.25mH to maintain the 1:1 ratio. However, since inductance in series adds linearly, that gives us a full primary inductance of 1.25mH + 1.25mH = 2.5mH, but we already know from the datasheet that the primary inductance is 5mH, not 2.5mH!
Obviously something I am doing is not right. What am I not considering and/or what assumptions do I have wrong?
Also, what should the values be for L1, L2 and L3 in the diagram below to model this 2CT:1 transformer with an OCL of 5mH?
Thanks!
I have found a datasheet (T-51117) for a "2CT:1" transformer which claims to have an "OCL" value of 5mH. I'll assume this OCL value of 5mH is the inductance across the full primary.
Since the relationship between turns and inductance is given by the equation: Ns/Np = sqrt(Ls/Lp) and we know that Ns/Np = 1/2 and Lp = 5mH. This must mean that Ls = 1.25mH.
Now here is where things fall apart for me. If we assume that the center tap cuts the number of primary windings in half, then each half-primary to secondary should make a 1:1 transformer since they both have equal turns (the full primary has twice as many turns as the secondary). Since we just calculated the secondary to be 1.25mH, each half primary should also be 1.25mH to maintain the 1:1 ratio. However, since inductance in series adds linearly, that gives us a full primary inductance of 1.25mH + 1.25mH = 2.5mH, but we already know from the datasheet that the primary inductance is 5mH, not 2.5mH!
Obviously something I am doing is not right. What am I not considering and/or what assumptions do I have wrong?
Also, what should the values be for L1, L2 and L3 in the diagram below to model this 2CT:1 transformer with an OCL of 5mH?
Thanks!
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