High Frequency Modeling of Peak Current Mode Control of DC-DC Converters

The control of power converters can be difficult if high dynamic performance is required, especially against the variations in supply voltage and load. This difficulty can further increase in the presence of input filters, which are intentionally underdamped to decrease the converter losses. In such cases, the peak current mode control facilitates the design of control law. The usual approach for the modeling of this type of control assumes constant current ripples in smoothing inductance. However, this assumption is somewhat restrictive and limits the validity of the model at high frequency. This paper presents a modeling approach which avoids this assumption, consequently leading to a better representation of the converter at high frequencies. In order to improve its performance with respect to load and line disturbances, this kind of control implicitly integrates a feed forward compensation. The application of the developed analysis is carried out on a buck converter; however, it is equally applicable to any other type of converter.