Abstract
At the stage of designing switching converters, it is considerably important to optimize the dynamic characteristics, which impose the restriction on the choice of parameters such as the inductance of reactor, the capacitance of output capacitor and the feedback gain of control circuit, etc. For instance, the restriction for stability prevents the miniaturization of the converter because it increases the minimum capacitance of output capacitor, and also it reduces the range of available load current. From these reasons, the latitude of design is narrowly limited. To improve these problems there are some effective compensation methods available for dynamic characteristics such as proportional and differential control (PD control) and state feedback control composed of several control loops.
The purpose of this study is to compare PD cotrol which is popularly known as a compensation method and the state feedback control where not only the output voltage but also the reactor current are the feedback signals. The difference between them is made clear analytically and experimentally in terms of the compensation effect on the stability characteristics and the step response of output voltage. As a result, it is proved that by employing the state feedback control the capacitance of output capacitor is decreased half and the available load current is increased twice compared with those in case of the PD control. In addition the state feedback control is fairly insensitive to the ripple and noise and facile to design, whereas the PD control is not. Therefore the state feedback control is superior to the PD control as a whole.
