32 IEEE Electrification Magazine / MARCH 2022 io = Vdc Cf vg Vdc Cf vg PWM Current Controller (Optional) io iref Voltage Controller vpcc vref Pref P Power-Based Synchronization Reference Generator ϑref Vref Lf ig vpcc Zg = PWM Current Controller PQ Calculator Q Qref iαβref Reactive Power Control Phase-Locked Loop ϑpll αβ dq PCC Pref eref Cv Qref (a) Qref (b) CP Z Pref iref Y io Pref io Lf ig vpcc Zg PQ Calculator PQ Qref Active and Reactive Power Controller Idref Iqref PCC Figure 1. Typical control diagrams of (a) a GFM inverter and its equivalent circuit and (b) a GFL inverter and its equivalent circuit. PWM: pulsewidth modulation; PCC: point of common coupling.