Nowadays, there is an increasing demand for more efficient and better performing electric drive systems that can meet the requirements of today’s medium and high-power applications, such as electrified transport or renewable energies. In this regard, multiphase systems are becoming increasingly popular due to their superior characteristics compared to traditional three-phase systems. Their advantages include reduced torque ripple, reduced per phase current ratios, increased power density and, in particular, fault tolerance. In this sense, multiphase electrical machines are able to operate even under faulty conditions as long as at least three healthy phases remain, although they do so in a degraded form. However, in order to provide systems with true fault tolerance, the use of dedicated control and modulation techniques is essential. Similarly, it is desirable to avoid the occurrence of cascading failures that further degrade or permanently halt system operation. Therefore, the post-fault techniques that are employed must ensure the best possible performance in terms of torque ripple and loss minimization, while keeping both the converter and the motor at an appropriate operating point. However, multiphase systems are not immune to common mode voltage (CMV). This type of voltage, which is generated by the switching of the power converter, causes an electromagnetic interference that can affect the operation of the control electronics. Likewise, when discharged by the parasitic capacitors of the motor, the CMV derives circulating leakage currents that cause deterioration of the motor bearings and insulation. Furthermore, the effects caused by this voltage are highly dependent on the size of the motor and the grounding configuration. Therefore, the measures taken to reduce the CMV must be closely linked to the target application. In this context, this thesis aims to improve the performance of the converter motor assembly through the use of modulation techniques. For this purpose, this work is divided into three main sections. In the first one, a study of multiphase converters and the modulations used in them is carried out. After this first study, the five-phase converter is concluded to be the best option. Therefore, the contributions of this thesis are dedicated to it. Then, the next to sections are devoted to each of the problems identified at the beginning of this first one: fault tolerance and common mode voltage. In the second section, the one regarding fault tolerance, firstly the most frequently occurring faults in the converter-motor assembly are studied. Additionally, some of the modulation techniques proposed to date are discussed. After that, the first contribution is presented: discontinuous modulations for the single-phase loss scenario. Finally, these modulations are analysed experimentally and by means of a simulation model. The third section follows the same structure as the previous one but focusing on CMV. After first analysing the causes, effects and both active and passive solutions proposed in previous literature, the proposed modulation techniques for CMV reduction are presented. The target application of these techniques is an electromechanical actuator of a landing gear, which has been modelled using the Matlab/Simulink software. Finally, the proposed modulation is validated on this platform.