Multilevel Inverter with a Reduced Switch Count and DC-Link Capacitor

A multilevel inverter topology providing multilevel operation without a neutral point connection. With no split dc-link capacitors, the neutral point balancing issue in conventional multilevel operation is eliminated. The neutral points of the phase-legs are interconnected through a single bidirectional switch. The topology reduces the required number of switches for dual inverter operations, while providing all the critical benefits of multilevel operation (low current total harmonic distortion, low switching loss, low common-mode electromagnetic interference noise, and low motor iron loss).  The topology also offers a reduction in the dc-link capacitance up to 90%. Compared to a dual 2-level inverter, this invention with the same capacitance produces 50% less stress in the capacitor current and 50% less ripple in the capacitor voltage. It also enables the same level of ripple performance with only 46% of the capacitance required in the dual 2-level topology, leading significant cost and volume reductions.