Research On Some Key Technologies Of High Voltage Medical X-ray Power Based On SiC MOSFET

Medical X-ray machine plays an important role in the diagnosis and treatment of modern medicine.The quality of X-rays depends on the quality of the high-voltage medical power system.Medical high-voltage power system pursues smaller size,higher power,shorter rise times,smaller ripples,and higher efficiency.The paper first expounds the research status of high voltage medical power system,SiC MOSFET application and LCC resonance parameter design.The high voltage medical power system scheme is briefly introduced,and the main topology structure is analyzed and designed.The main circuit topology consists of rectification,full-bridge inverter,LCC resonant cavity and voltage doubler rectification.The LCC resonant cavity part analyzes the working principle of LCC resonant soft switch.The fundamental capacitive equivalent model of LCC resonant converter is established.Based on this,a design method for LCC resonance parameters suitable for a wide range of input and output voltages is proposed.And the simulation model is built by simulink to verify the effectiveness of the resonance parameters and design method.The inverter part analyzes the crosstalk of the SiC MOSFET H-bridge and the formation mechanism of the gate and drain oscillations,and the short-circuit protection.The drive circuit of the SiC device is optimized.At the same time,the SiC multi-tube parallel current sharing technology is researched and analyzed,and the PCB layout and routing of SiC devices and drivers are optimized.In addition,the circulation and current sharing mechanisms of multiple H-bridges are analyzed in parallel,and the circulation suppression and current sharing design of multiple H-bridges in parallel is realized.By constructing the LTSPICE model,the pre-simulation of the drive circuit parameter design was carried out to verify its rationality.The voltage doubler rectification part adopts positive and negative kV symmetrical voltage doubler rectifier circuit,which reduces the insulation voltage design requirements.At the same time,the parameter design of transformer and voltage doubler rectification topology is analyzed,and the design scheme is proposed to reduce the influence of distribution parameters on output voltage symmetry.Finally,the simulation and experimental verification of the system were carried out by constructing the simulink simulation model and experimental platform.The results show that the high-voltage medical power system based on SiC MOSFET designed in this paper basically achieves the expected results and meets the design requirements.