To solve the problem of conventional phase locked loop technique under the condition of unbalanced power grid voltage, a grid inverter synchronous technology based on neural network under unbalanced power grid case is developed. At first, grid voltage state equation was derived in the two-phase stationary coordinates, and a neural network was built based on the state equation; the biases of output voltage vector and the actual voltage vector were used to adjust the neural network weight online, and thus to find out the amplitude, frequency and ...