Modular Multilevel Converters (MMCs) have become a leading topology for medium- and high-voltage applications due to their modular structure, excellent scalability, and inherent fault-tolerant characteristics. The ability of MMCs to generate high-quality output waveforms with minimal filtering, combined with their flexible voltage and power scalability, makes them well suited for demanding applications such as High-Voltage Direct Current (HVDC) transmission, renewable energy grid integration, and industrial motor drives. This chapter investigates the implementation of Pulse Width Modulation (PWM) techniques across various Sub-Module (SM) configurations employed in MMCs, specifically Half-Bridge Sub-Modules (HBSMs), Full-Bridge Sub-Modules (FBSMs), and Flying Capacitor Sub-Modules (FCSMs). Each SM topology is examined in detail with respect to its switching methodology, operational characteristics, and capacitor voltage balancing requirements, offering a comprehensive analysis of their performance and challenges. Dedicated capacitor voltage balancing algorithms are designed for the HBSM, FBSM, and FCSM configurations, each tailored to address the unique operational constraints and control complexities associated with the respective SM structures. Comprehensive simulation studies are carried out in the MATLAB/Simulink environment to assess the performance and robustness of the proposed PWM schemes and balancing strategies. The simulation results demonstrate effective voltage regulation across a wide range of operating conditions, validating the reliability of each approach. Furthermore, the comparative analysis underscores the trade-offs and performance distinctions among the different SM topologies, offering critical insights for the optimal selection and control of sub-modules in practical MMC applications.