RLC analog circuit design

c1036783304

RLC analog circuit design [Copy link]

 

I am a newbie in analog electronics, and I need guidance from the experts. As shown in Figure 1 below, it is an RLC charge and discharge circuit. The switch S2 is turned on at a current of 5A, the on time is 5us, and it is in the off state for the rest of the time. (a) The oscillation frequency of the current flowing through the coil obtained based on Multisim simulation in Figure 1 is only about 500KHz, which is inconsistent with the theoretical calculation of 3.86MHz. I would like to ask the experts what is the reason? ? (b) The current amplitude flowing through the coil in Figure 1 is only about 3A. Is it possible to connect a certain circuit (such as a transformer, etc.) in series in the dotted box in Figure 2 without changing the circuit parameters to increase the current flowing through the coil to about 30A? ?

Figure 1

Figure 2

maychang

"(a) The oscillation frequency of the current flowing through the coil obtained based on Multisim simulation in Figure 1 is only about 500KHz, which is inconsistent with the theoretical calculation of 3.86MHz"

According to the inductance L = 30uH and the capacitance C = 2.2nF in the figure, 3.86MHz cannot be calculated. How did you calculate it?

maychang

"Is it possible to connect a certain circuit (such as a transformer) in series in the dotted box in Figure 2 to increase the current flowing through the coil to about 30A without changing the circuit parameters??"

It is impossible to increase the current flowing through the coil without changing the circuit parameters.

maychang

In your other post, PowerAnts has made it very clear to you: the current in the inductor reaches its peak value because the energy stored in the capacitor is completely converted into energy in the inductor. Therefore, the only way to increase the peak current in the inductor is to increase the energy stored in the capacitor. Given the capacitance, the only way to increase the energy stored in the capacitor is to increase VEE.

c1036783304

maychang published on 2019-10-18 08:26 "(a) The oscillation frequency of the current flowing through the coil obtained based on Multisim simulation in Figure 1 is only about 500KHz, which is inconsistent with the theoretical calculation of 3.86MHz" ...

I calculated the angular frequency of oscillation based on the formula

wd=1/sqrt(LC)*sqrt(1-R^2*C/(4L))

Calculated

I seem to have forgotten to divide by 2*pi, 3.889M is in radians

c1036783304

maychang posted on 2019-10-18 09:11 In your other post, PowerAnts has already made it very clear to you: the current in the inductor reaches its peak because the energy stored in the capacitor is completely converted...

Thank you very much for your detailed explanation.

c1036783304

maychang posted on 2019-10-18 08:28 "Is it possible to connect a certain circuit (such as a transformer, etc.) in series in the dotted box in Figure 2 without changing the circuit parameters so that the current flowing through the coil...

If I build a 1:10 transformer in the dotted box to increase the voltage across the energy storage capacitor and the coil by 10 times, can I increase the current through the coil?

maychang

c1036783304 Published on 2019-10-18 23:11 If I build a 1:10 transformer in the dotted box to increase the voltage across the energy storage capacitor and the coil by 10 times, can I increase the current through the coil?

"If I build a 1:10 transformer in the dotted box, the voltage across the energy storage capacitor and the coil will increase 10 times."

Connecting a 1:10 transformer will not increase the voltage across the energy storage capacitor by a factor of 10. If the capacitor charges long enough (your switch is off long enough), then the energy stored in the capacitor is the same as before the transformer was plugged in.

maychang

c1036783304 Published on 2019-10-18 23:11 If I build a 1:10 transformer in the dotted box to increase the voltage across the energy storage capacitor and the coil by 10 times, can I increase the current through the coil?

"If I build a 1:10 transformer in the dotted box, the voltage across the energy storage capacitor and the coil will increase 10 times."

Inserting a 1:10 transformer into the dotted box is equivalent to converting the 30uH inductance of the secondary connection into the 0.3uH inductance of the primary. The primary current of the transformer does increase, but the current in the inductor L1 will not increase. On the contrary, because the transformer efficiency cannot reach 100%, the current in L1 will decrease.

乐在其中1100

Come here to learn and recharge. Thanks for sharing.

c1036783304

maychang posted on 2019-10-19 07:50 "If I connect a 1:10 transformer in the dotted box, the voltage across the energy storage capacitor and the coil will increase 10 times" Insert the dotted box...

Hello, thank you very much for your explanation, but I still have a question. If we do not consider the loss of the transformer, since the current in the primary coil increases, then according to the relationship between the turns ratio, shouldn't the current in the secondary coil also increase? And if the current in the primary coil increases by several times, won't the current in the secondary coil also increase by several times?

maychang

c1036783304 posted on 2019-10-19 16:39 maychang posted on 2019-10-19 07:50 "If I build a 1:10 transformer in the dotted box, so that the energy storage capacitor and the ends of the coil...

For an ideal transformer (without loss), the voltage on both sides of the transformer is proportional to the number of turns of the two windings, and the current on both sides is inversely proportional to the number of turns of the two windings. Your transformer turns ratio is 1:10, that is, the secondary turns are 10 times the primary turns, and the secondary current must be 1/10 of the primary current.