Charging overvoltage and undervoltage protection method and system for alternating current charging pile

The invention provides a charging overvoltage and undervoltage protection method and system for an alternating current charging pile in the technical field of charging and discharging control of the alternating current charging pile, and the method comprises the steps: S1, setting a voltage monitoring parameter group comprising a charging voltage upper limit, a charging voltage lower limit, an overvoltage return fork value and an undervoltage return fork value through an MCU, and setting a first time length and a second time length; s2, in the charging process, the MCU detects the input voltage of the power grid in real time through the power grid detection module, performs overvoltage and undervoltage monitoring on the input voltage based on the voltage monitoring parameter group, disconnects the connection with the power grid through the relay control module during overvoltage and undervoltage, controls the CP control module to stop outputting the PWM waveform, and controls the PWM control module to stop ou