Smart transformer (ST)-based microgrids are preferred over conventional power transformer (CPT)-based microgrids because of their compact size, lighter weight, and ability to provide ancillary services. The low-voltage (LV) converter of ST operates as a grid-forming converter (GFC) unit, and distributed generator (DG) converters follow the voltages set by the ST LV converter. This paper introduces a new control technique called the instantaneous symmetrical component-based Andronov-Hopf virtual oscillator (S-AHVO), which addresses the limitations of existing virtual oscillator (VO) controls that only synchronize with positive-sequence voltages and fail under unbalanced conditions. The S-AHVO control enables continuous synchronization of positive, negative, and zero-sequence voltages, thereby enhancing microgrid operation during voltage imbalances and ensuring accurate load sharing. It maintains the dynamic performance of existing VO controls and can be implemented without additional sensors. The paper includes a systematic design procedure, mathematical analysis, and simulation studies to validate the proposed technique.