Research Of Design And Control Method Of Resonant Soft-switching Buck Converter

With the development of high frequency power electronics technology, the power converter is lighter in weight and smaller in size, and the performance price ratio of the product is improved. Switching losses will increase as the switching frequency increases in proportion by using conventional hard-switch technology, and the high frequency of the switch is limited. Aiming at the weakness of hard-switching for traditional power electronic converter is big loss and low efficiency, the soft-switching technology emerges. It uses the resonance as the main means of commutation, so the problem of switching noise and switching loss is effectively reduced. With the emergence of embedded and digital signal processing technology is becoming more and more mature and perfect. Performance price ratio of microprocessor, micro controller and digital signal processor continues to increase. Digital control is widely used in power converter. Compared with analog control, digital control has many advantages. Digital control can realize complex control strategy, which has higher stability, reliability and flexibility. And it’s easy to realize the power of intelligent, but also can shorten the development cycle of new products.The hardware circuit of the resonant soft-switching Buck converter which is studied in this paper is designed with STM32F407VGT6 as the core control device. The control strategy chooses Fuzzy PID control strategy. And finally the strategy is achieved through the software programming. The experimental results show that this control strategy has good control performance. Algorithm is relatively simple to achieve. At the same time control module designing is simple and high reliability.Key content and achievements made by this article is mainly reflected in the following aspects:To begin with, the basic working principle of the switching power supply and the working principle of the Buck topology is carried out a detailed analysis; At the same time, the control strategy of the DC-DC converter is studied. On the basis of this, the voltage regulator control of the resonant soft switching converter is explored.Secondly, the control strategy of resonant soft-switching Buck converter is studied. The combination of fuzzy control theory and PID algorithm is mainly studied. The conventional PID control theory, analog PID and digital PID control system are introduced, and the setting process and the rule of PID parameters are also given. The parameters of the conventional PID controller cannot adapt to the change of parameters, and the control system with a large number of interference. Obviously, it is difficult to obtain satisfactory control effect. Even when the parameter variation range is too large, the system performance will be significantly worse. Therefore, combined with the conventional PID control, a combined control algorithm based on fuzzy control and PID is studied. It can achieve better results. The control algorithm and the conventional PID control method are compared by simulation. By simulation, the feasibility of this strategy is verified, and the dynamic and steady state performance of the system are improved.Thirdly, the hardware design process of resonant soft-switching Buck converter is given. The schematic diagram of each module hardware circuit and calculating formula of key module parameters are given.Fourthly, software design of resonant soft-switching Buck converter is completed and developed. The software implementation process of the two-way complementary symmetrical PWM control signal, fuzzy PID regulation control and isolation sampling of output voltage are described in detail.Finally, the performance index of the resonant soft-switching Buck converter is tested. After the analysis of the input voltage mutation waveform and the output voltage waveform in the case of different load and input voltage, the reliability and stability of the designed converter are verified.