Operation of the half-wave rectifier with resistive-capacitive load

Figure 1.7

The equations describing electric processes in the circuit are

Let's designate:

λ - a pulse thyristor current duration,

φ – a delay angle of the thyristor switching on is fixed concerning a point of natural switching on.

Let's consider intervals:

1)

The thyristor is on-state:

U_T=0;

Let's find I_T.

2) -

The thyristor is off-state:

.

According to second Kirchhoff’s law

Characteristic equation is

.

Root of this equation is

.

Then a voltage across the condenser is

.

Current through the load is

.

Current of the condenser is

.

Voltage across the thyristor is

.

Constant A we could be defound from the condition:

At

Then

.

Let's define

At

Figure 1.7

According to the diagram of changing the function tg(u)

limits by

.

For active load:

for the capacitive load: ,

From the condition of the no interrupted process, i.e. periodicity of electromagnetic processes in the circuit, we could find φ:

This transcendental equation can be solved graphically or by numerical methods by computer.

Fig. 1.8 – The diagram of electric processes in a single-phase half-wave circuit of the rectifier with resistive-capacitive load.

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