Integrated Magnetic-Based Isolated Three-Phase Inverter With Flux-Rate-Controlled Harmonic Filtering

This article proposes an integrated magnetic-based isolated three-phase inverter scheme. Here, the harmonic components are filtered using the flux-rate control technique. The system operates using a main and control inverter with a common dc link and a magnetic circuit. The main inverter performs a square wave mode of operation at the fundamental frequency throughout the operating range, causing lower switching losses and reduced voltage and current stresses. The control inverter performs pulse width modulation (PWM) operation and sets up the necessary flux rate in the magnetic interface, operating at a fraction of the total power rating. The integrated magnetic circuit comprises eight-limbed E-I-E lamination types. It interfaces the main inverter, control inverter, and loads, causing galvanic isolation and load side free from power electronic components to provide scaling flexibility. The bond graph modeling technique formulates the dynamic model of the system to conduct the simulation studies. A lab-built prototype validates the working of the proposed scheme. The experimental studies comprise the working of the inverter for different modulation, dynamic operations, and an induction machine’s open loop v/f operation. The study includes the proposed inverter’s power loss and size comparison with the conventional two-level and three-level neutral point clamp (NPC) inverters.