This project focuses on the topology of multilevel neutral point clamped (NPC)/H-bridge inverters and their modified modulation technique for high-power (megawatts) medium voltage (typically 6000 v) applications. A sinusodial pulse width in-phase disposition modulation is proposed for five-level NPC/H-bridge inverters. The inverter achieves good harmonic performance and low dv/dt in its output voltage waveforms in comparison to the conventional three-level NPC inverter. A seven-level NPC/H-bridge topology and its sinusodial pulse width in-phase disposition modulation are also proposed and investigated, which has better performance than the five-level inverters. Theoretical analysis and computer simulation are carried out for the proposed inverter topologies and algorithms. The output voltage waveforms and harmonic performance are verified by experiments on a five-level NPC/H-bridge inverters.