In this chapter, we are first going to study the failures in a set of converter-synchronous machines that are used in a particular industrial application. The numerical data comes from [SCH 03] and [SCH 04]. We will see that the most important failures involve power transistors; other failures concern the stator coils of the synchronous machine. Hence, the main faults involve short-circuit or open-circuit problems. We will see that these problems cause perturbator torques, which are added to the cogging torque.

Second, we will study the supply strategies of healthy phases, aiming to compensate for both the perturbator torque and the cogging torque. We will show that in certain conditions it is possible to find optimal currents ensuring the desired torque while minimizing ohmic losses. We will give four main solutions and state six practical rules about these optimal currents.

Finally, we will see an adaptive control strategy in a closed loop based on neural learning to obtain optimal currents, whatever the type of fault. To illustrate the main situations that occur, we will give several examples of applications, which will be the object of simulations.

## 3.1.1. *Analysis of failures of the set converter-machine: converters with MOSFET transistors*

### 3.1.1.1. *Introduction*

The goal of this section is to study the operating safety of the permanent magnet three-phase synchronous actuator associated with the static ...