New Modulation Technique for Three-level Interleaved Voltage Source Inverters for Switching Loss Reduction

This paper presents a new modulation strategy for three-level interleaved voltage source inverters for switching loss reduction. By using two in-phase level shifted triangular carrier signals, the simultaneous switching of the two interleaved inverter cells is avoided. Only one of the interleaved inverter cells is undergoing switching for half of the fundamental period; the other inverter cell is clamped to either the positive dc bus or the neutral point of the inverter. Therefore, the switching loss of the inverter is reduced by 50 percent compared to the conventional phase-shifted carrier modulation technique for interleaved inverters. The conduction loss of the inverter is slightly increased (by about 5 percent), but the overall loss is significantly reduced. The validity of the proposed modulation method is verified using a 1kW experimental prototype.