Checking the static behaviour of the thyristor when it is switched on

In this example we will check that the steady-state behaviour of a switched-on thyristor corresponds to the parameters specified in the settings of its block:

V_GT = 0.6;     #В
I_GT = 3e-6;    #А
V_T = 1.2;      #В
I_T = 1.0;      #А
Rs = 87.0;      #кОм

Test 1: Checking the opening voltage

In the Thyristor_Static_Behavior_On_1.engee model, the thyristor starts when a pulse of 3 µA or more (Gate trigger current, I_GT) is applied to the gate.

Test conditions:

• Supply voltage $U_s = 12 В$. The supply voltage should not be applied abruptly, but gradually with the Linear Signal (Ramp) block to prevent dv/dt start-up;
• Load $R_L =120 Ом$;
• There is no external resistor on the gate in the circuit, so to switch on the device with a 3µA pulse, the value of the internal shunt resistor (Internal shunt resistor, Rs) must be set $R_s = 87.0$. If the resistance is low, the thyristor will not trigger at the input current $i_{GT}$, and if it is too high, the thyristor will trigger at a current lower than $i_{GT}$.

V_s1 = 12;         #В
R_load1 = 120;    #Ом
I_on1 = I_GT;      #A

In this test, we will check that the unlocking voltage at the control electrode is equal to the Corresponding gate voltage, V_GT, 0.6 V value specified in the settings when the current in the control electrode is equal to the thyristor trigger current, Gate trigger current, I_GT, 3 µA.

Starting the model

if "Thyristor_Static_Behavior_On_1" in [m.name for m in engee.get_all_models()]
    m = engee.open( "Thyristor_Static_Behavior_On_1" ) # загрузка модели
else
    m = engee.load( "Thyristor_Static_Behavior_On_1.engee" )
end
results_1 = engee.run(m, verbose=true)

Obtaining parameters

t_1 = results_1["i_GT_1"].time;         # Время
i_GT_1 = results_1["i_GT_1"].value;     # Ток затвора
v_GT_1 = results_1["v_GT_1"].value;     # Напряжение между затвором и катодом 
i_load_1 = results_1["i_load_1"].value; # Ток нагрузки 
v_AK_1 = results_1["v_AK_1"].value;     # Прямое напряжение  

Graphing

using Plots
plotlyjs();

plot(layout=@layout([a a; b b;]), legend=:outerbottomright)
plot!(t_1, i_GT_1, subplot=1, ylabel="Ток, А", w = 2, linecolor =:blue, label="Ток затвора")
plot!(t_1, v_AK_1, subplot=2, ylabel="Напряжение, В", w = 2, linecolor =:orange, label="Прямое напряжение")
plot!(t_1, i_load_1, subplot=3, xlabel="Время, c", ylabel="Ток, А", w = 2, linecolor =:green, label="Ток нагрузки")
plot!(t_1, v_GT_1, subplot=4, xlabel="Время, c", ylabel="Напряжение, В", w = 2, linecolor =:red, label="Напряжение между затвором и катодом")

From the graphs we can see that the thyristor starts when a 3 µA pulse is applied to the gate, and the voltage between the gate and the cathode is indeed close to 0.6 V.

Test 2. Checking the voltage drop of an open thyristor

The Thyristor_Static_Behavior_On_2.engee model uses a thyristor with the same settings. In this test we will verify that the voltage drop of the open thyristor $U_{AK}$, corresponds to the parameters specified in the thyristor settings (On-state voltage) $U_T = 1.2 В$ at the load current in the on-state (On-state current) $I_T=1 А$.

Test conditions:

• Supply voltage $U_s = 12 В$ (gradual supply);
• Load $R_L = \frac{U_s-U_T}{I_T}=\frac{12В-1.2В}{1А} = 10.8 Ом$;
• An external resistor $R_{GK} = 1000 Ом$ reduces the sensitivity of the thyristor's triggering. the triggering current increases to about $U_{GT}/R_{GK}=0.6 В/1000 Ом = 0.6 мА$. The critical current will be slightly less than $0.6 мА$ because of the increased anode-gate current that contributes to the gate current.

V_s2 = 12;          #В
R_load2 = 10.8;     #Ом
R_GK = 1000;        #Ом
I_on2 = 0.6*1e-3;   #А

Running the model

if "Thyristor_Static_Behavior_On_2" in [m.name for m in engee.get_all_models()]
    m = engee.open( "Thyristor_Static_Behavior_On_2" ) # загрузка модели
else
    m = engee.load( "Thyristor_Static_Behavior_On_2.engee" )
end
results_2 = engee.run(m, verbose=true)

Obtaining parameters

t_2 = results_2["i_GT_2"].time;         # Время
i_GT_2 = results_2["i_GT_2"].value;     # Ток затвора
v_GT_2 = results_2["v_GT_2"].value;     # Напряжение между затвором и катодом 
i_load_2 = results_2["i_load_2"].value; # Ток нагрузки 
v_AK_2 = results_2["v_AK_2"].value;     # Прямое напряжение    

Graphing

using Plots
plotlyjs();

plot(layout=@layout([a a; b b;]), legend=:outerbottomright)
plot!(t_2, i_GT_2, subplot=1, ylabel="Ток, А", w = 2, linecolor =:blue, label="Ток затвора")
plot!(t_2, v_AK_2, subplot=2, ylabel="Напряжение, В", w = 2, linecolor =:orange, label="Прямое напряжение")
plot!(t_2, i_load_2, subplot=3, xlabel="Время, c", ylabel="Ток, А", w = 2, linecolor =:green, label="Ток нагрузки")
plot!(t_2, v_GT_2, subplot=4, xlabel="Время, c", ylabel="Напряжение, В", w = 2, linecolor =:red, label="Напряжение между затвором и катодом")

From the graphs we can see that the load current in the switched on state is 1 A and at this current the voltage drop between anode and cathode is indeed close to 1.2 V.

Conclusion

Having performed two turn-on tests on the thyristor, we have verified that the static behaviour of the thyristor matches the parameters specified in its block settings.

Blocks used in example

• Controlled Voltage Source
• Pulse Generator
• Ramp
• Saturation
• Terminator