Research On Digital Controlled Phase-Shift Full Bridge ZVZCS DC/DC Converter

DC/DC converter is a main part of power electronic converter. Soft-Switching technique is a hotspot of power electronic research. It's the key technique in high frequency and high density converter. With the advent of microprocessor, there has been an increased interest in digital control of switch mode power supply, instead of analog control. The digital control scheme has many advantages in simplifying the control circuit, improving the anti-interference ability, control precision and flexibility, general and intelligent level. In order to research on soft-switching and digital control technology, this paper proposes a digital controlled phase-shift ZVZCS full bridge converter and analyses it's principle of operation.There are two soft-switch schemes of phase-shift full-bridge DC/DC converter: zero-voltage switching (ZVS) and zero-voltage zero-current switching (ZVZCS). This paper compares and analyses the two schemes. On the analyses of several typical ZVZCS circuit topologies, a ZVZCS full bridge PWM converter using coupled output inductor is introduced. The method of component parameter design and transformer design is presented in this paper and simulated by PSpice.On the state space analysis and small-signal model analysis of this topology, this paper introduced a digital control system based on digital signal processor IC (TMS320F240). This paper analyses the system control loop to satisfy the performance of the converter. The paper also presents the method of digital PI controller design and the implementation of the whole digital control scheme. The experiment results show: Main circuit's parameter is right, reasonable and achieve all design require; Zero-voltage zero-current switching is achieved correctly, and the converter has many advantages such as simple auxiliary circuit, low voltage stress of rectifier diode ,self-adjustment of circulating current and high efficiency; The control system's hardware structure is simple, highly integrated and easy to implement; The control system's software works properly and fulfill all functions, the correctness of the whole design is validated.