Grid Forming Inverters (GFM) for Active Front End (AFE) Variable Frequency Drives (VFDs)

Active Front-End (AFE) based Variable Frequency Drives (VFDs) enable bidirectional power flow, near-unity power factor, and reduced line current harmonics compared to diode rectifier-fed drives. However, conventional AFE systems employ Grid-Following (GFL) control reliant on PhaseLocked Loop (PLL) synchronization and current regulation, resulting in degraded performance in weak or distorted grids, including synchronization instability and poor voltage regulation. This paper proposes the integration of Grid-Forming (GFM) control into AFE VFD architectures, allowing the converter to operate as a controlled voltage source independent of PLL synchronization. By incorporating droop control and virtual impedance, the proposed GFM-AFE enhances transient stability, voltage regulation, and fault ride-through capability.