5/21/2023 0 Comments Simple delay circuit pspice model![]() Linear Transformer Model and Equivalent CircuitĪ simple linear transformer model in PSpice is shown in the figure below. This might require using a 3D field solver, or you can determine the coupling coefficient using measurements from a real transformer. Calculating the coupling coefficient directly from the geometry of the transformer can be difficult, but it is nominally defined in terms of the mutual inductance (M) between the two coils, the inductance of each coil:Ĭoupling coefficient in a nonideal linear transformer modelĪs long as you can properly calculate the coupling coefficient based on the geometry of the coils in your transformer, you can get an accurate view of the behavior of a linear transformer model in your circuit. A value of k = 1 indicates perfect coupling (i.e., no flux loss), while k = 0 indicates perfect isolation (i.e., none of the flux reaches the secondary coil). This is included in a circuit model by defining a coupling coefficient k, which ranges from 0 to 1. As a result, the effective impedance of the secondary coil is slightly larger than the ideal case. A linear transformer model accounts for this flux reduction in the derivation for the voltage/current induced in the secondary coil. ![]() In addition, the conductors used to form each coil have some resistance, so the voltage dropped across the primary coil is slightly reduced from the supply voltage due to the resistance in the coil. Unfortunately, the magnetic field produced by the primary coil is not perfectly confined in the core, thus the magnetic flux that is seen at the secondary coil is slightly less than the magnetic flux produced by the primary coil. As a result, the impedance of the primary coil is equal to the impedance of the secondary coil, multiplied by the turns ratio. In other words, the flux produced by the primary coil is equal to flux seen at the secondary coil. In this model, There is no magnetizing inductance or resistance, and magnetic flux is perfectly confined between the two coils. In an ideal transformer, the voltage/current induced in the secondary coil only depends on the ratio of turns in the primary and secondary coils. Nonideal Linear Transformer Modelīefore getting into building a linear transformer model for a circuit simulation, we need to consider what happens in a real (i.e., nonideal) transformer, such as a flyback transformer. As much as we would like to ignore parasitics and nonideal effects in circuit models, accounting for these gives you a more accurate view of your system’s behavior and helps you make the right design choices. ![]() Real transformers are a perfect example of this. I think every engineer hopes their systems act just as was taught in their electronics classes, but this is not always the case. Transformer for 3-phase power distribution ![]()
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