Design Of Buck Switch Mode Power Supply Based On ARM9

In recent years, with the economic development and more demands for powerproducts on computers and communications industry, the research of power-relatedtechnology has become an international hotspot in the field of power electronics.Therefore, the study of switch mode power supply，which is known as its advantages,such as the small size, light weight, stable and reliable, etc., not only has greattheoretical significance, but also has great economic and social benefits.The parameters, such as output voltage and current of a single DC stable powersupply are often out of requirements in practical application. With connecting themodular in series or parallel mode usually, people expansion the output voltage,output current and other functions. Parallel current sharing, which has beenspecifically designed to ensure the current and thermal stress’s evenly distributedbetween the parallel modular of power supply, is regarded as a key technology toachieve the object of high power, has a very important significance in improving thereliability of power system.At present, power supply is mainly controlled by the high-performance digitalprocessor chip directly. To improve the regulation accuracy, dynamic performance,integration, intelligence and other goals of the power supply, more and more powersupply manufacturers has begun to adopt ARM technology. With B/S Mode to designEmbedded Remote Supervisory Control has been the newest development trend.The main content of this thesis included three parts: designed the BUCK DC/DCmodules, realized the method of controlling the current’s distribution, which wasrealized by a digital PID regulator algorithms and closed-loop feedback of hardwarebased on ARM9, and designed the remote monitoring module of switch mode powersupply. In this paper, the system and circuits solutions were specific designed, got aexpected result through simulation and some tests. Tests showed that the systemsolutions can keep pace of the development of the industry; it also made the circuitssimpler, accuracy higher and more universal. In addition, this plan could also be usedin related fields. Firstly, this paper analyzed the development status of the switch mode powersupply at home and abroad and the necessary for parallel current sharing. Secondly,described the digital control technology and remote monitoring system of switchmode power supply. The design scheme of this paper was to design the main powermodule with DC/DC power convention chip, which converted the DC power supplythat commonly used in Human Machine Interface to the required voltage. Throughdigital PID regulator and closed-loop feedback of hardware, realized the control anddistribution of current. The current feedback signal came from the two DC/DCmodules’ current sampling, the voltage feedback signals came from the main circuit’svoltage sampling. Then the three signals were sent to S3C2440A’s ADC, aftertreatment, sent to the DAC, after converted the control signals to voltage signals, theywere sent to the regulator’s inverting input, at last, realized the closed-loop control. Atthe same time, it could ensure the stability of the system, completed the protection ofthe over-voltage and over-voltage and over-current, and showed the value of voltageand current. The given voltage and current signals were offered byARM9.Secondly, the paper made a carefully analysis and designing in various modulesform theoretical and practical, gave a specific circuit, and wrote some software flowcharts and design places in which should be paid attention to. The entire system wascomposed of TX2440A Development Board, the DC/DC power supply conversionmodules and the distribution of current control circuit module. Since the entire systemis a closed-loop control system, the sampling rate must be quite high. This systemused TX2440A’s ADC converter to complete the feedback current signal and thefeedback voltage signal’s sampling directly, and DC/DC power supply modules wereresponsible for the DC voltage’s conversion. Current distribution control circuitmodule can not only complete the two power supply modules’parallel current sharing,but only realize the current output by controlled proportion. The monitoring modulewas responsible for the remote monitoring of the system, in order to operate andmanage the data, improve the safety of monitoring system, used the embeddeddatabase SQLite.Finally, through some simulation and actual current output’s test, got theexpected conclusions. In conclusion, it pointed out some places which need toimprove. Under the current requirements of the small size, intelligence, high accuracyand stability, the digital switching power supply has a broad space for development.Basically, the system reached the design requirement. However, there were manyaspects would be helpful for improving the accuracy, such as improving the master, the accuracy of reference voltage and the accuracy of sampling devices, etc.This system involved electronics, communications and monitoring fields, itcombined the digital PID algorithm, the power of electronic technology andcommunications technology. The system design could be used not only in the powersupply controller, but also in the related field.