Power losses in PWM-VSI inverter using NPT or PT IGBT devices

This paper investigates the power losses for two different IGBT technologies (nonpunch through and punch through) for use in PWM-VSI inverters in order to choose the right device technology for a given application. A loss model of the inverter is developed based on experimental determination of the power losses. The loss model is used on two different modulation strategies which are a sine wave with a third harmonic added and a 60°-PWM modulation where only two inverter legs are active at the same time. The two IGBT technologies are characterized on an advanced measurement system which is described. The total power losses in the inverter are estimated by simulation at different conditions and it is concluded that the nonpunch through (NPT) technology is most useful for higher switching frequencies, while the punch through (PT) technology is especially useful at lower switching frequencies and high load currents. It is also concluded that the 60°-PWM modulation has the lowest power losses and the power losses are almost independent of phase angle cos(φ) for normal motor operation