| In order to improve the automation degree of travelling wave tube test system, overcome the manual test’s faults in flexibility and efficiency, people demand for traveling wave tube automatic test system is more and more intense. A small gain adjustable power amplifier need to be installed in front of TWT, the function of this device is amplify the signal source within a certain frequency band. This as the input signal of traveling wave tube, whether it works in good condition has a direct influence on the stability of the system. In order to protect the travelling wave tube and amplifier, this paper has design a digital flyback switching power supply based on TMS320F28035. The power supply has good reliability and circuit protection.This paper first introduces the research background about TWT automatic test system, introduce the occasions of power use and requirements, to do a detailed analysis about the present situation of the development of digital power supply. Combined with the requirements and newly mainstream solution, determine the design scheme of this paper. Secondly, through the introduction the basic theory of switching power supply, choosing the appropriate flyback work mode, digital control mode and control algorithm. According to the design scheme, the mode of power working and the parameters of the concrete, the power supply is designed. According to the requirement of the output power and voltage, input filter capacitor and switch tube device are choose. Designed the clamping circuit and flyback transformer, according to the characteristics of the parameters of the MOS tube, driving circuit was designed, using the optical coupler design output voltage sampling circuit. Software in system initialization, ADC sampling module, EPWM and comparator module are analyzed in detail, and introduce the module configuration and writing process. Introduces the main function works, complete the writing of the software. Finally, according to the above design, make a power output of 25 w amplifier power supply system. Through online debugging to verify this DSP program. Debug the DSP control part and power part, test the output wave and voltage waveform of MOS tube. Through the comparison with theoretical design, shows that power supply work in the normal state. Measure the output wave and efficiency. Ripple is 300 mV, Power supply working in more than 50% full load condition, the efficiency is above 75%. According to the measured results, analyze and summarize the proposed design scheme, and put forward the feasible improvement direction.According to the design and make the physical, complete the power supply system used in low power gain adjustable power amplifier, and explained the key points of technology for product design. Based on the design, manufacture and debugging the circuit, make the design meet the requirements of design index, to lay a solid foundation for further development of high performance power supply. |
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