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

In this example we will check that the dynamic behaviour of the thyristor when it is switched on corresponds to the parameters specified in the settings of its block:

In [ ]: 
T_on = 2.0;           #мкс
Rate_dvdt = 150.0;  #В/мкс

Test 1. Checking the switch-on delay

In the Thyristor_Dynamic_Behavior_On_1.engee model, a pulse is applied to the gate of the thyristor to start the thyristor. In this test, we will determine the turn-on time of the thyristor.

The time required for transition of the gate from off to on state (Gate-controlled turn-on time) is set in the Thyristor block parameters and is equal to 2 µs.

image.png

Running the model

In [ ]: 
if "Thyristor_Dynamic_Behavior_On_1" in [m.name for m in engee.get_all_models()]
    m = engee.open( "Thyristor_Dynamic_Behavior_On_1" ) # загрузка модели
else
    m = engee.load( "Thyristor_Dynamic_Behavior_On_1.engee" )
end
results_1 = engee.run(m, verbose=true)

Obtaining parameters

In [ ]: 
t_1 = results_1["i_GT_1"].time;
i_GT_1 = results_1["i_GT_1"].value; 
i_load_1 = results_1["i_load_1"].value;

Graphing

In [ ]: 
using Plots
plotlyjs();
In [ ]: 
plot(layout=@layout([a; b;]), legend=:outerbottomright)
plot!(t_1, i_GT_1, subplot=1, ylabel="Ток, А", w = 2, linecolor =:blue, label="Ток затвора")
plot!(t_1, i_load_1, subplot=2, xlabel="Время, c", ylabel="Ток, А", w = 2, linecolor =:green, label="Ток нагрузки")
Out[0]:

The graphs show that the load current lags behind the gate current pulse by about 1.3 µs. The exact time depends on the supply voltage and load resistance, but the influence of these parameters is not taken into account when initialising the block.

Test 2. Verification of dV/dt-start

The Thyristor_Dynamic_Behavior_On_2.engee model shows dv/dt starting, which is the spontaneous switching on of the thyristor due to a too fast change in forward voltage. The voltage creates a capacitive current in the gate-anode circuit.If this current is large enough, it will open the thyristor even without a control signal.

The value of the maximum permissible rate of rise of off-state voltage, dV/dt, is specified in the parameter of the thyristor block. The thyristor block uses this parameter to calculate the approximate value of the gate-anode junction capacitance that would cause the thyristor to trip at the specified rate. Because of the approximations used in estimating the capacitance value, in this example the thyristor will still trip if the rate of voltage change exceeds 95 V/µs.

In this test, let's apply a forward voltage $v_{AK}$, rising sharply from zero to 400 V at a rate of 150 V/µs.

image.png

Running the model

In [ ]: 
if "Thyristor_Dynamic_Behavior_On_2" in [m.name for m in engee.get_all_models()]
    m = engee.open( "Thyristor_Dynamic_Behavior_On_2" ) # загрузка модели
else
    m = engee.load( "Thyristor_Dynamic_Behavior_On_2.engee" )
end
results_2 = engee.run(m, verbose=true)

Obtaining parameters

In [ ]: 
t_2 = results_2["v_s_2"].time;   
v_s_2 = results_2["v_s_2"].value;   
v_AK_2 = results_2["v_AK_2"].value;
i_load_2 = results_2["i_load_2"].value;

Graphing

In [ ]: 
plot(layout=@layout([a; b; c]), legend=:outertopright)
plot!(t_2, v_s_2, subplot=1, ylabel="Напряжение, В", w = 2, linecolor =:blue, label="Напряжение питания")
plot!(t_2, v_AK_2, subplot=2, ylabel="Напряжение, В", w = 2, linecolor =:green, label="Прямое напряжение на тиристоре")
plot!(t_2, i_load_2, subplot=3, xlabel="Время, c", ylabel="Ток, А", w = 2, linecolor =:red, label="Ток нагрузки")
Out[0]:

The graphs show that when the forward voltage changes at a rate of 150 V/µs, the thyristor switches on.

Conclusion

By conducting two tests, we have studied the dynamic behaviour of the thyristor. In the first test the thyristor was switched on by applying control current to the gate and the second test shows dv/dt start-up.

Blocks used in example