The invention relates to a dynamic stability performance evaluation method for a power device, which belongs to the technical field of power devices. Based on an
equivalent circuit of the power device, sample data of the power device under different working conditions are obtained, a state-space equation of the power device is established according to the sample data, so that a
system matrix is obtained, and the
system matrix is substituted into a
Lyapunov equation to solve a matrix used for judging stability; whether the matrix is positive definite or not is judged through the Sylvester criterion, so that whether the power device is stable or not under different working conditions is obtained, the
instability index of the power device can be obtained by counting the number of
instability points and the number of stability points, and therefore whether the power device is stable or not is judged. According to the method, the dynamic stability of the power device can be judged according to the parameters in real-time operation of the power device, the EMI
risk level of the power device can be effectively evaluated, the actual application of the power device can be guided, reference is provided for design optimization of the power device, and the method has the advantages of being simple, efficient, portable and the like.