Grid Voltage Phase Angle Detection Through di/dt Analysis and Curve Fitting for EV-Grid Synchronization

This paper presents an innovative curve fitting method to detect grid voltage phase angle in pulse width modulated (PWM) single-phase inverters using output current derivative analysis. The proposed approach detects the phase angle of the grid voltage in the switching cycle time frame (milliseconds) based on inverter current measurement, eliminating voltage sensors and traditional phase-locked loops (PLL). The approach provides an ultrafast response time and improved reliability, adaptable to any grid conditions (weak or stiff). Combining advanced data processing with linear and nonlinear curve fitting, this approach offers a robust, voltage-sensorless solution for vehicle-to-grid (V2G) synchronization, enabling rapid and seamless EV-Grid synchronization process without any grid interference regarding stability; therefore, a significant improvement in EV-Grid integration process can be achieved.