A Novel Three-Phase Dual-Output Neutral-Point-Clamped Three-Level Inverter

Abstract

A novel topology of a three-phase dual-output neutral-point-clamped three-level inverter (DO-NPC-TLI) is proposed. DO-NPC-TLI can achieve two groups of ac voltage outputs with adjustable frequency and amplitude. We describe the topology in detail. The proposed topology is based on a neutral-point-clamped three-level inverter (NPC-TLI). A total of eight switches and six clamping diodes are added to the NPC-TLI to form the new topology, and then analyze the working principle of the circuit. With the consideration of neutral point voltage balance, a modulation strategy combining the time-sharing modulation idea and virtual space vector pulsewidth modulation (VSVPWM) is proposed. In order to simplify the complicated calculation process of VSVPWM, a carrier-based PWM based on VSVPWM is proposed. All of the duty ratios are used to calculate the modulation waves of DO-NPC-TLI. The driving signals of switches are generated by comparing the modulation waves with a carrier. The modulation strategy mentioned above is verified by the experiment. The correctness of the experimental results illustrates the effectiveness of the modulation strategy and the feasibility of the proposed topology.