Inverter N line detection control circuit and method thereof

The embodiment of the invention discloses an inverter N line detection control circuit and a method thereof. The circuit comprises a sampling module used for collecting three-phase voltage; the filtering module is connected among the L1 line, the L2 line, the L3 line and the N line of the three-phase inverter; the controlled module is connected between any one of the L1 line, the L2 line and the L3 line and the N line, and when the controlled module is conducted, the X capacitance capacity of the line connected with the controlled module to the N line is larger than the X capacitance capacities of the other two lines to the N line respectively; and the control module is configured to control the controlled module to be switched on or switched off according to the output mode, and judges whether the N line is connected to the power grid or not by comparing the phase angle difference value of the three-phase voltage with a preset angle range. According to the invention, the capacitance capacity of any one line