The system consists of main power c

The system consists of main power conversion circuit, pulse width modulation and driving circuit, error compensation and amplification, etc. The system samples the output voltage V, and compares it with the reference voltage Vc to obtain the error voltage V, which is sent to PWM circuit after compensation and amplification. After comparison with triangular wave, it is modulated into a pulse signal with corresponding duty ratio d(t), and the pulse signal controls the on-off of IGBT through IGBT driver module, so as to achieve the purpose of adjusting the output voltage. In which the part enclosed in the dashed box is implemented in the digital controller DSP.In the principle of automatic control, the transfer function of the control object is needed to design the controller, so the dynamic model of the switching converter should be established first. The difference between switching converter and general physical model is that the switch action will change the circuit connection, so the modeling object is a time-varying nonlinear system.The main idea of modeling with small signal disturbance method is to linearize the converter by introducing low frequency small signal disturbance near the static working point of the converter. Compared with the switching frequency of the converter, the turning frequency of the general switching converter is far less than the switching frequency, that is, it is assumed that the high frequency components of the switching frequency and harmonic frequency contained in the state variables in the circuit are far less than other DC components, so that the switching frequency and frequency conversion band components can be ignored in the dynamic model