<p>Dual three-phase permanent magnet synchronous motors (PMSMs) have excellent properties. However, an unavoidable power supply unbalance exists under dual DC power source configurations. To address this, an improved online space vector modulation (SVM) strategy incorporating harmonic current injection is proposed in this paper. First, to deduce the injected index of the harmonic currents, the relationship between the fundamental and harmonic currents is researched. Second, each subspace is tracked by four voltage vectors, and an improved online modulation method is proposed to eliminate offline tables, thereby simplifying calculation. Finally, experimental results verify the effectiveness of the proposed strategy under unbalance DC-link voltages, presenting superior characteristics in terms of a substantial reduction in both the current total harmonic distortion and action time compared to traditional methods.</p>