A novel stability analysis method for the DC-AC inverter with nonlinear loads based on harmonic balance and Floquet theory

The nonlinear loads exist widely in practical engineering applications. Due to the nonlinear characteristic of the loads, the nonlinear loads firstly need to be linearized to a resistor with constant value using the traditional stability analysis method based on the Routh-Hurwitz stability criterion and the method based on the stroboscopic map. In this paper, a novel stability analysis method is proposed based on the harmonic balance and Floquet theory for the inverters with nonlinear loads, which can present all characteristics of the nonlinear loads. In detail, the model of the inverter with nonlinear loads is established. Following, the approximate analytical periodic expressions of the inverter with nonlinear loads are obtained by using the harmonic balance method; and then, the stability analysis of the above inverter versus PI parameters is carried out according to Floquet theory. Finally, simulation and experimental results are given to verify the accuracy of the stability analysis method proposed in this paper.