The inputs of the PID module are an error signal e1 outputted by the error calculation module, the control signal PI_ctrl outputted by the mode control module and the V_PI0 assigned; in the dynamic mode, when the PID module is switched off, the dynamic mode is switched to the first switch period of the normal working mode, an initial value V_PI0 is assigned to the calculation of the PID module firstly, then PID calculation is conducted, the supplementary calculation result V_PI is outputted to the mode control module and the PWM module, then PID calculation is conducted to each period of the normal working mode, and the supplementary result V_PI is outputted to the mode control module and the PWM module.

The inputs of the PWM module are the PI_ctrl control signal outputted by the mode control module, the switch period T_{s_LTH} or T_{s_HTL} and the duty ratio D_LTH or D_HTL of the LTH and HTL modes, the control mode result mode_ctrl of the mode control module in the normal working mode, and the supplementary result V_PI of the PID module; the switch period and the duty ratio information in normal control are obtained by calculating through the supplementary result V_PI of the PID module and a control mode mode_ctrl signal of the normal working mode given by the mode control module, after the period and the duty ratio/peak current information are obtained, the duty ratio waveform is outputted through a driving circuit to realize the loop control on the grid of a power valve of the switch power; and then the output voltage of the switch power is sampled again, and the process above is repeated to conduct cycle control to switch on and off the power valve of the switch power, so as to make the system be more stable, thus obtaining higher dynamic response.