Impedance Characteristic of Load in DC-DC Converters and Its Effect on Stability

As the core of the switching power supply,DC-DC converter may have load of inductive impedance in practical applications,and it will influence the system's stability. Based on the considerations of stable design,this paper studied the tolerance of converters to parasitic inductance in the impedance load,accordingly obtained the corresponding inductance threshold of stability and analyzed impedance effect of circuit load synthetically. Higher dimensional model including inductance component of load was introduced. By constructing discrete iterative map and calculating eigenvalue near equilibrium point,the evolution of system's operation regime and the circuit stability can be analyzed with the parasitic inductance component changing. Accurate simulations,theoretical analysis and circuit implementation prove that there exists a value range of parasitic inductance corresponding to the instable operation of converter,on which circuit parameters will have certain influence.