Design Of High Power And High Stability DC Switching Power Supply

As the application of micro electro mechanical,Micro-processing and Current cathode technology in the Electrical Vacuum Components,the microwave vacuum electronic devices frequencies are developing fast towards terahertz(THz)frequency fields and make an important step in the terahertz power source.High-voltage power supply is an essential component of terahertz sources for the system works stably and reliably,with high power output,wide adjustment range,low ripple coefficient and other features.Its performance directly affects output characteristics of the electric vacuum device,such as frequency,spectrum width,efficiency and so on.Therefore,It is an event of significance to develop the high power,small-scale and high stability power supply for THZ source.Based on the requirements of the 340GHz backward wave oscillator(BWO)and adequate understanding of the principles of switching power supply,the paper mainly includes the design of high voltage power supply system.High-voltage power supply system mainly includes filament module,auxiliary cathode voltage module,high-voltage acceleration module and interface control circuit.The main part of the high voltage is the core of the high-voltage power supply.This paper mainly introduces the main circuit control chip,power switch device and transformer core selection,and gives the detailed calculation process of transformer parameter design.The main circuit mainly introduce the selection of control chip,power switch device and core structure,the explicit calculation process of the parameters designation.The full-Bridge converte is used for major high-voltage power converter module,and the chopper circuit is realized by means of PWM control chip and drive chip in the circuit for alternating conduction of power switch.At the same time,in order to effectively protect the power module,over-voltage and over-current protection are provided in the circuit.Main control portion helps to achieve the voltage regulation with the combination of STM32 and traditional PWM chip UCC28086.The high output voltage can be set via the computer and the STM32 can be read the corresponding digital control commands form it and transform into analog variable.Then the PWM chip generates high voltage according to the analog quantity.Comparing the sampled voltage’s signal,which is regarded as the reference signal,with the Pre-set numeric value,then adjusting the duty cycle through the internal circuit of UCC28086 which leads to stabilizing the output voltage.Also a signal detection circuit are designed for STM32 to monitor the work condition of entire power.When the power input is over-voltaged or the output is over-current,the protection circuit will immediately activated to protect the power module.The output voltage of the high voltage switch power supply designed in this paper can be stable and adjustable in the range of-1kV～-6kV,the output current can reach up to 250mA,the power supply stability is below 5×10-4,and the ripple is below 0.2V.During the design process,the power supply was repeatedly debugged.The final test parameters all reached the design index,and hence it is of great value for engineering application.