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Step-down transformer

Introduction

This example demonstrates the operation of a step-down single-phase transformer.

Description of the model

The example model uses blocks from the fundamental section of the Engee library for physical modeling. The transformer is designed for power , the operating frequency , input voltage and a day off. It is assumed that the efficiency is equal to , the no-load magnetization current is and leakage reactivity - . Core losses are not taken into account. It is assumed that the dependency the core material is linear.

electric_transformer.png

Initially, the transformer is idling. At a moment in time the rated load "load" is switched on. Due to the resistance of the winding and the inductance of the dissipation, the voltage of the secondary winding drops from before . A current is generated on the secondary winding of the transformer .

Simulation

Let's download and execute the developed model.

In [ ]: 
Путь_примера = @(__DIR__);
Имя_модели = "electrical_transformer";
Путь_модели = joinpath(Путь_примера, Имя_модели*".engee")

if Имя_модели ∉ getfield.(engee.get_all_models(), :name)
    engee.load(Путь_модели);
end

модель = engee.run(Имя_модели);

We will get the variables displayed in the model for further construction.

In [ ]: 
# Время
t = модель["V_1"].time;
# Напряжения
V_1 = модель["V_1"].value;
V_2 = модель["V_2"].value;
# Токи
I_1 = модель["I_1"].value;
I_2 = модель["I_2"].value;
# Магнитные потоки и мдс
Ф = модель["Ф"].value;
Ф2σ = модель["Фl_2"].value;
F = модель["МДС"].value;

Simulation results

We will plot graphs of electrical variables - voltages and currents of the primary and secondary windings.

In [ ]: 
# Подключаем библиотеку Plots и бэкэнд
using Plots
plotlyjs()

plot(t, [V_1 V_2]; layout = (2,1), subplot = 1, ylabel = "Напряжение, В", label = ["V_1" "V_2"], title="Напряжения и токи")
plot!(t, [I_1 I_2]; subplot = 2, ylabel = "Ток, А", label = ["I_1" "I_2"], xlabel = "Время, c")
Out[0]:

As can be seen from the voltage and current graphs, the transformer lowers the voltage and increases the current. After connecting the rated load secondary winding to the circuit, rated currents begin to flow through the windings.

Let's plot the magnetic variables - the main magnetic flux. , magnetic flux leakage through the secondary winding and magnetomotive force (mds).

In [ ]: 
plot(t, Ф.*1e3; layout = (3,1), subplot = 1, ylabel = "Поток, мВб", label = "Ф", title="Магнитные переменные")
plot!(t, Ф2σ.*1e6; subplot = 2, ylabel = "Поток, мкВб", label = "Ф2σ", color=:green)
plot!(t, F; subplot = 3, ylabel = "мдс, А⋅в", label = "мдс", color=:red, xlabel = "Время, c")
Out[0]:

As can be seen from the graphs, the main magnetic flux after connecting to the secondary load transformer decreases by the magnitude of the leakage magnetic fluxes, and a magnetomotive force is formed in the magnetic circuit.

Conclusion

In this example, a 220/12 V step-down transformer operating at rated load is considered. The dynamics of the electric and magnetic variables of the system was considered.

Blocks used in example