**6. Simulation results**

In order to test the static and dynamic performance of the control, the DSIM is accelerated from standstill to reference speed 100 rad/s. The machine is applied

**Figure 5.** *Simulation results of real and estimated speed, torque, flux, and current of three-level DTC-ANN.*

*Improved Direct Torque Control Based on Neural Network of the Double-Star Induction… DOI: http://dx.doi.org/10.5772/intechopen.89877*

with a load torque of 11 Nm. Finally, the direction of rotation of the machine is reversed from 100 rad/s to 100 rad/s at time t = 2 s. **Figures 5** and **6** show the simulation results of the three- and five-level DTC control for DSIM.

Simulation results of speed, stator flux, torque, stator current, and stator voltage show the good performance of the three- and five-level DTC-ANN control of DSIM (speed, stability, and precision).

We note that the speed follows its reference value. The electromagnetic torque stabilizes at the value of the nominal torque after a transient regime with rapid response and without exceeding before stabilizing at the value of the applied load torque.

**Figure 6** shows that the five-level DTC-ANN control reduces the ripple of the electromagnetic torque, the stator flux, and the THD value compared to that of the three-level DTC-ANN. On the other hand, we note that the speed reaches its reference without exceeding for the two control types. Moreover, the couple follows the load torque. The dynamics of the stator flux are not affected by the application of these load instructions.

The use of multilevel inverter at five levels causes a decrease in the current ripple at the steady state that is to say low peaks than that of the three-level control. However, the results of the simulations shows a good dynamic characteristic of the stator flux in the transient regime for five-level DTC-ANN compared to the threelevel DTC-ANN with static errors that are virtually null in both cases of control DTC proposed.

**Figure 6.** *Simulation results of real and estimated speed, torque, flux, and current of five-level DTC-ANN.*

**6. Simulation results**

*Selection table based on neuron network.*

*Direct Torque Control Strategies of Electrical Machines*

**Figure 4.**

**Figure 5.**

**10**

In order to test the static and dynamic performance of the control, the DSIM is accelerated from standstill to reference speed 100 rad/s. The machine is applied

*Simulation results of real and estimated speed, torque, flux, and current of three-level DTC-ANN.*

**Figures 7** and **8** show the simulation results of the three-level and five-level DTC-ANN control for low-speed operation. DSIM is accelerated from standstill to a low reference speed of 10 rad/s, at time t = 0.5 s; the DSIM is accelerated again to a reference speed of 100 rad/s. The machine is loaded with a nominal load of 11 Nm. Finally, a reversal of the direction of rotation of the machine from 100 rad/s to 10 rad/s is performed at time t = 2 s.

The simulation results show that low-speed operation does not affect the performance of the proposed drive. Indeed, the good reference speed tracking is ensured, with advantages brought by the use of five-level DTC-ANN control, the minimization of torque ripple, and stator flux, which is confirmed by the simulation results.

In order to know the best type control of DSIM, a comparative study is essential

**THD (%) Ripples of torque Ripples of flux**

In this chapter, we presented two types of DTC control (three-level DTC-ANN and five-level DTC-ANN) of a DSIM fed by two NPC voltage inverters, and the technique of neural networks was applied to the DTC control. The main advantage of this control is to allow control of the flux and torque of the machine without the need to use a mechanical sensor. The direct torque control strategy is an effective and simple way to control an induction machine. In order to improve the performance of the DSIM (torque ripple reductions, flux, response time, and the THD value of the stator current), simulation tests of the control by variation and

inversely of the speed have been presented; the results obtained show that the fivelevel DTC-ANN control with speed control is very efficient. This shows the effec-

between the two types (three-level DTC-ANN and five-level DTC-ANN). The following table shows the comparison between the two types (**Table 3**).

*The comparison between three-level and five-level DTC-ANN.*

*DOI: http://dx.doi.org/10.5772/intechopen.89877*

Three-level DTC 18.73 Good Good Five-level DTC 12.82 Very good Very good

*Improved Direct Torque Control Based on Neural Network of the Double-Star Induction…*

**7. Conclusion**

**Table 3.**

**Appendix**

**13**

**DSIM parameters**

Pn = 4.5 Kw In =6A Rr = 2.12 Ω Lr = 0.006 H Rs1 = Rs2 = 1.86 Ω Ls1 = Ls2 = 0.011 H Lm = 0.3672 H J = 0.065 kg.m<sup>2</sup> kf = 0.001 Nm/rad.

tiveness of the proposed strategy.

**Figure 7.** *Simulation results of three-level DTC-ANN for low-speed operation.*

**Figure 8.** *Simulation results of five-level DTC-ANN for low-speed operation.*

*Improved Direct Torque Control Based on Neural Network of the Double-Star Induction… DOI: http://dx.doi.org/10.5772/intechopen.89877*


**Table 3.**

**Figures 7** and **8** show the simulation results of the three-level and five-level DTC-ANN control for low-speed operation. DSIM is accelerated from standstill to a low reference speed of 10 rad/s, at time t = 0.5 s; the DSIM is accelerated again to a reference speed of 100 rad/s. The machine is loaded with a nominal load of 11 Nm. Finally, a reversal of the direction of rotation of the machine from 100 rad/s to

The simulation results show that low-speed operation does not affect the performance of the proposed drive. Indeed, the good reference speed tracking is ensured, with advantages brought by the use of five-level DTC-ANN control, the minimization of torque ripple, and stator flux, which is confirmed by the simulation

10 rad/s is performed at time t = 2 s.

*Direct Torque Control Strategies of Electrical Machines*

*Simulation results of three-level DTC-ANN for low-speed operation.*

*Simulation results of five-level DTC-ANN for low-speed operation.*

results.

**Figure 7.**

**Figure 8.**

**12**

*The comparison between three-level and five-level DTC-ANN.*

In order to know the best type control of DSIM, a comparative study is essential between the two types (three-level DTC-ANN and five-level DTC-ANN). The following table shows the comparison between the two types (**Table 3**).
