Analysis and comparison of diode rectifier units suitable for aerospace applications

The importance of power quality increases as more electric systems are introduced on aircraft. This paper compares the common mode and harmonic performance of four suitable multi-pulse diode rectifiers to give a better understanding of the performance tradeoffs of each system. This is achieved by simulating and assessing the effects of imbalance in the phase shifting transformers, voltage harmonics and negative sequence imbalance in the supply on CMV, line currents and Total Harmonic Current Distortion (THDI). This paper concludes that zero sequence harmonic distortion has the largest impact on the magnitude of CMV and a negligible effect on THDI. It is found that the DC link voltage is affected negligibly by harmonic distortion, negative sequence supply imbalance and inductive imbalance in the phase shifting transformers. Higher pulse number circuits tend to have a lower harmonic distortion and lower CMV providing the higher pulse number is not achieved by extending a lower pulse number converter using voltage injection techniques.