Research On Wide Range Input Constant Voltage Output DC-DC Converter

As the direct current interface of many electrical equipment,DC-DC converter is widely used in daily life.When the input voltage changes or is unstable,it may lead to unstable output of the system,breakdown of the power conversion device,or even damage the electrical equipment if there is no suitable power conversion device and control method.To solve this problem,a wide input constant output DC-DC converter is studied in this paper,which uses the circuit topology of two-switch Buck-Boost transformation and combines with a new adaptive hysteresis sliding-mode control method to effectively improve the static and dynamic state performance of the DC-DC converter.The working principle of two-switch Buck-Boost converter is analyzed,and the working characteristics and small-signal models of Buck and Boost circuits are studied respectively.In order to establish a complete sliding mode control system,the control rail function is constructed,and the arrival condition,existence condition and stability condition of sliding mode control are deduced.In order to eliminate the chattering phenomenon of sliding mode variable structure control,a hysteresis control method is used to change the sliding mode motion into controlled oscillation.In addition,an adaptive control method is introduced to further limit the switching frequency so that the two-switch Buck-Boost circuit can operate at a fixed frequency.According to the technical specifications of DC-DC power converter,the main circuit parameters are designed.In order to verify the correctness of theoretical analysis and design,circuit simulation experiments were carried out with MATLAB.The simulation results showed that the adaptive hysteresis sliding-mode control method greatly reduced the filter capacitance on the output side,and the two-switch Buck-Boost converter had strong robustness when the input voltage varied in a wide range and the load changed.In order to further verify the adaptive hysteresis sliding mode control method is effective and practical,a physical experiment was conducted on the Buck circuit,the experimental results showed that the adaptive hysteresis sliding mode control could provide excellent large signal processing ability,enabled the electric energy conversion device to work in a larger scope for better static performance and dynamic performance,enough to deal with the influence of outside working condition change on the DC-DC converter.