This paper presents harmonic mitigation techniques for hybrid electric vehicle traction motor drive systems. First, DC-bus harmonics are presented for a space vector modulated (SVM) dual traction drive system, compared against military standard MIL-STD-461. Next, dithered/random SVM techniques are explored and the respective harmonic performance is compared. The effect of the DC-bus capacitor size is also fully investigated, with the harmonic results again compared against MIL-STD-461. Based on the overall results and inherent DC-bus resonance conditions, it is proposed that the harmonic performance can be optimized through strategic frequency selection within the random switching frequency pool. Therefore, the paper concludes with analysis and implementation of "selective" switching frequency sweeps.