A Design Of High-freqency Digital Switch Power For General Medical Equipment

As one of the latest international technological achievements, the single-chip switching power supply which is managed by the IC,has been widely used.This system is featured by high integration,high performance cost ratio,the most simple external circuit,the best performance indicator, an integral part of high-efficiency power supply, etc.This thesis aims at designing a digital medical high-frequency single-chip switching power supply, using the work pattern of PWM.This circuit can output steady voltage and electric current that can satisfy the need of normal middle and low-voltage armarium,functions of self-detection,protection and human-computer interaction.This thesis has designed the circuit system, including hardware and software. The results show that the circuit has finished feature design, and reached design targets; Leakage current has met the requirements for armarium.Firstly,this thesis gives a in-depth analysis on the basic principles of switching power. By considering aspects of functions and benefits, we decide to adopt the PWM digital mode, and give the preliminary requirements for parameters.Meanwhile,we design a conceptual system on basic principles so that the entire digital switching power supply is featured by openness and high security. Structure of the whole system is in line with embedded system structure standards, switching power supply structure standards and medical equipment safety standards, which are made by International Electrotechnical Commission.Secondly, the thesis elaborates design and production of the hardware circuit in depth.Particularly,combining with system design,we introduce modern software engineering design thought and use top-down approach to refine system gradually to design a circuit module with high cohesion and electric coupling, finally we design the whole schematic by model as a unit.Considering the safety demands required by medical supply, the thesis proposes the conception "FOUR GROUNDS",according to which we divide the circuit in large scale—high-voltage switching power supply control circuit, medium voltage switching power supply PWM control circuit and low-voltage SCM circuit.Finally,this thesis elaborates design and program of the software system. Software was designed according to the system design on the basic principles of switching power supply,combining with features of the hardware circuit and components.This thesis comprehensively analyzes the workflow of the universal power supply and designs modern digital control systems with the function of human-computer interaction.