**6.1. Electrical model**

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

Simulations and experimental waveforms related to figure 15 are shown in figure 17. The

URMS = 230 V ; R = 58 ; Li =800 H ; Lo = 800 mH It can be seen that the simulated waveforms are very close to the experimental ones. The

overlap interval 1 is equivalent for simulation and experimental results (<sup>1</sup> 0.7 ms).

**Figure 17.** Comparison of Simulation and Experimental Waveforms in a six-pulse diode rectifier

a) Simulation b) Experimental result

Type : Variable-step Solver : ode15s (stiff/NDF) Max step size : 1e-4 Relative tolerance : 1e-5 Min step size : auto absolute tolerance : auto

Using a PC with an Intel core 2 duo CPU running at 2.19 GHz with 1 Go de RAM, the

This model has also been tested with a load constituted of an inverter and an induction machine. The results of this test have validated operations for discontinuous conduction

The Simulink model of the controlled rectifier is very close to the Simulink model of the diode rectifier. Only the condition to turn the thyristor on is different to the condition to turn the diode on. For an ideal thyristor, it is recalled that the thyristor turn-on if its voltage

Start time : 0 Stop time : 0.2s

mode. For the same configuration parameters, the simulation time was 5 s.

**6. Modeling and simulation of thyristor rectifiers** 

is positive and if a current pulse is sent to the gate.

The list of configuration parameters used for Matlab simulation is:

**5.3. Experimental validation** 

simulation time was 4 s.

simulation parameters are adjusted as follows:

Let us consider the electrical scheme presented on figure 18a. It represents a DC motor fed by a six-pulse rectifier. The electrical equivalent circuit of the DC motor is described by an inductance La in series with a resistance Ra in series with an induced voltage Va which characterizes the electromotive force, as illustrated in figure 18b.

a) Electrical circuit b) Simplified electrical circuit of a DC motor

**vo**

**Figure 18.** Controlled rectifier with inductive load

The thyristor are modelled by an ideal model which traduces the state of the switch:


Similar to the diode rectifier, there are 13 operating phases to describe:


All the thyristor are state-off


The different operating phases are illustrated in figure 15. The equations that governs an operating phase are the same whatever we work on a diode rectifier or a controlled rectifier.
