*6.2.2. Thyristor control*

The control device for thyristor T1 is presented in figure 21. The switch-on of T1 is delayed of r after urt has reached to zero (block "Delay 1"). The control thus carried out is a pulse train (the width of a pulse is computed by block "Delay 2").

The same principle is applied to the other thyristor.

b) Computing algorithm

**Figure 20.** Structure of the rectifier block

64 MATLAB – A Fundamental Tool for Scientific Computing and Engineering Applications – Volume 1


**Figure 19.** Simulink model of the controlled rectifier with inductive load

io

Controlled Rectifier


io vo

Load (Ra, Va)



urst vo teta\_r

*6.2.1. Internal structure of the rectifier block* 

the initial state for next computing phase.

(the width of a pulse is computed by block "Delay 2").

The same principle is applied to the other thyristor.

with the integrator function.

*6.2.2. Thyristor control* 

The simulink model of the controlled rectifier with inductive load is presented in figure 19.

The motor inductance La is regrouped with the output line inductance Lo to have a single

The structure of the rectifier block is presented on figure 20a. Four different blocks can be seen on this scheme: the first one called "Control T" is used for the control of the thyristor gate. The second one called MF1 is used to compute the inductances state and voltage. The third called Current computes inductances currents. Then, the Initial Phase block computes

a) Simulink model b) Load block

Subtract

1 vo

Va Constant


1 io

The computing algorithm has been created in accordance with figure 20b. For each computing step, the new operating phase is calculated. This phase is a function of the initial phase, the sign of the inductance currents and the diode voltages. For each operating phase, the value of each inductance di/dt is calculated and permits to know the diodes currents

The control device for thyristor T1 is presented in figure 21. The switch-on of T1 is delayed of r after urt has reached to zero (block "Delay 1"). The control thus carried out is a pulse train

The current block is strictly identical to the current block shown in figure 16.

**6.2. Simulink model** 

It consists of four blocks:

output inductor Loeq.

urst Input Voltage

teta\_r

#### **6.3. Experimental validation in continuous conduction mode**

Simulations and experimental waveforms related to the electrical circuit presented in figure 18 are shown in figure 22. The simulation parameters are adjusted as follows:

URMS = 230 V ; Ra = 4 ; Va = 145 V; Li = 800 H ; Loeq = 800 mH

The list of configuration parameters used for Matlab simulation is:


**Figure 21.** Control of thyristor T1

**Figure 22.** Comparison of Simulation and Experimental Waveforms

We can see that simulation results are in good agreement with experimental waveforms. The overlap delays are equivalent for simulation and experimental results.
