Constant Voltage Constant Current Power Supply Control .

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5th International Conference on Information Engineering for Mechanics and Materials (ICIMM 2015)Constant voltage constant current power supply control system forSingle-chip designQuan Zhou1,a, Yonghui Xie2,b1Electrical engineering, No. 243 Dongfeng East Street, Weifang City, Shandong Province, China2Electrical engineering, No. 243 Dongfeng East Street, Weifang City, Shandong Province, Chinaakyd1981cn@163.com, b xyhfdzh@tom.comKeywords: D / A conversion; Regulators Power; V / IAbstract. As electronic technology to the continued progress of the requirements of electronicdevices is also rising. Power circuit as a source of motive is playing an increasingly important role,Regulators sources in various laboratories or other places are indispensable. SCM technology withthe continuous development and D / A and A / D technology continues to mature NC Power makes itpossible, Digital control technology becomes more and more popular in the field of power supplies.NC current source is in control regardless of the accuracy or operability have the traditional powerunmatched advantages.ForewordRegulators sources in various laboratories or other places are indispensable, Traditional ACstabilized voltage supply is basically belong to dissipation ofenergy. It's theory is using nonlineardevice such as voltage regulator tube or ferroresonance steady voltage transformer assisted withnecessary circuit to realize the autoregulation of output voltage. It's ciruit is mature and theory isconsummate. But thiskind of supply has some idiopathic shortage.For example, supply usingmagnetismsaturation has the following shortage: size is big, weight is heavy; cost is high, efficiencyis low, self-consuming is high; high ripple coefficient of output voltage and low stabilization andefficiency.SCM technology with the continuous development and D / A and A / D technology continues tomature NC Power makes it possible. Compared with analog controllers, digital controllers have manyadvantages. The digital controller can realize some complicated control strategies and has higherreliability and stability, and the design of the digital controller is flexible. The digital controller canrealize the intelligent power and reduce the design cycle of new products.The subject in the current traditional reference sources, and ordinary NC current source, on thebasis of fully considering the cost performance while greatly enhancing the NC accuracy of thecurrent source, the power supply can be constant voltage and constant current output, Press throughits output voltage / flow control value stepper. Output voltage value using Digital Display 3.Some figures with 51 microcontroller as a core control. Through D / A converter module tocontrol the output voltage, while Sampling through sampling circuit output voltage / current andfeedback to the microcontroller. in order to enable voltage / current output more stable.The design of the main SCM control and display module, D/A conversion module, constantcurrent source module, output display module and feedback module. SCM control module usingSCM as the core, convert the input current signal into digital output; the constant current sourcemodule D/A conversion to analog voltage through a constant current source circuit into a constantcurrent; the display module to display the current or voltage; The feedback module is the outputvoltage and current sampling, through the A/D conversion after the feedback to the microcontrollerand compared to a predetermined, and adjust its output, the output is more stable. 2015. The authors - Published by Atlantis Press1316

Power Supply ModulePower modules make use of linear current source programs in the design, and add the active filtercircuit.Power transformer: A 150W dual 18V single 9V, 26V ring step-down transformer will change220V AC grid transform into about 25V AC power, the main and vice coil turns than about 9: 1. Afterthe rectification of AC voltage will be required DC voltage by electronic equipment.Rectifier circuit: the use of single-phase bridge rectifier circuit to change the direction and size ofthe 50Hz AC is transformed into the DC which is the same direction but still the pulse size. Theadvantage is the higher voltage, a smaller ripple voltage, rectifier diodes subjected to the maximumreverse AC current flow, the high utilization of the transformer.Filter circuit: the use of the nature of mutations of energy storage components - capacitor C atboth ends of the voltage, That RC filter circuit filte out most of the pulsation components of the outputof rectifier circuit , has been relatively smooth DC. Using 4700uF, 50V capacitor filter to achieve abetter filtering effect.Regulator circuit: After the 7815 7915 7805 7905 regulator rectifier filter circuit so that the DCvoltage does not communicate with the grid and load changes and changes in the disturbance. PowerSupply Module is shown in Fig. 1.Fig. 1 System Diagram powerThe System Display ModuleSystem display module using three semi-double integral ICL7107, analog voltage can be directlyconverted into BCD code, drive LED display, the display range is 0 19.99V , the minimumresolution is 10mv, to meet the circuit design requirements.74LS595 is the serial input and parallel output shift register, can be used as a static displayinterface, and then the serial port in the 89C52 used for digital display. Digital display module asshown in Fig. 2.99RCLKESRCLKSRCLR12131110J1 543214JFig. 2 Digital display module abacd f g bef e d acd f g beecfdgdpdp GND99R35R31R32R33R34R29R3012345678abacd f g beecfdgdpdpGND1412345678abacd f g bef e d cgdpdpGNDSER12345678U574LS595

D / A circuitAs a result of the coarse sub-harmonic control the accuracy of fine-tune system voltage / currentoutput greatly improves, to cost and component procurement consider, using DAC0832 circuit as a D/ A conversion circuit.DAC0832 is an 8-bit D / A converter chip, single power supply, from the 5 V 15 V may bethe normal work, the reference voltage range is 10V, time current set up is 1μs, CMOS technology,low power consumption 20mA. Its internal structure as shown, which is made of an 8-bit inputregisters, an 8-bit DAC registers and an 8-bit D / A converters, the pin ranges as shown in Fig. 3.Fig. 3 DAC0832 pin mapV / I conversion circuitThe using of output type D / A converter can achieves to current output, but its output current inμA the amplitude of the general order of magnitude, so the need for a number of times the currentamplification to achieve the required current value, the circuit is very difficult to achieve. So wechoose voltage output type DAC, then transform into a VI conversion circuit in proportion with thecurrent signal, the circuit is relatively easy to achieve in this program, V / I conversion circuit designis the key. Through the analysis we have chosen total load by way of V / I conversion circuit. V / Iconversion circuit as shown in Fig. 4.Fig. 4 Ways to load a total of V / I Conversion CircuitFilter moduleSimple RC filter circuit or π-type RC filter circuit can not meet the design requirements, so Ichoose to set up a new transistor devices in the π-type RC active filter circuit, and to the compositionof the active RC filter circuit. Filter module as shown in Fig. 5.1318

Fig. 5 Active filter circuitPower amplifier outputAccording to the design requirements we have chosen three LM337/LM317 client which isadjustable voltage regulator IC, and its output voltage range is 1.2V to 37V, load current is up to 1.5A.Its use is very simple, only two external resistors to set the output voltage. In addition, its the adjustrate of linear and the adjust rate of load are better than standard fixed regulators. LM337/LM317 havebuilt-in overload protection, security protection and other protection circuit.Sampling feedback moduleSampling feedback circuit has two input sample value, the output voltage signal sample taken atthe output of parallel resistors, by the method of partial pressure resistor voltage attenuation, theoutput current signal sample is in the main loop through the sampling resistor in series that will loadcurrent into a voltage signal sent to A / D conversion unit realized. Sampling feedback circuit diagramas shown in Fig. 6.After sampling the signal to the ADC0809 ADC, the analog signal is converted to digital signals,in comparison to the single-chip microcomputer, ADC0809 are with 8 A / D converter, 8-waymulti-way switch as well as micro-processing machine-compatible CMOS control logic components.Internal structure as shown, which is component of 8-channel analog switch, the address latch anddecoder, comparator, 8 switch tree D / A converters, successive approximation register and athree-state output latch. ADC 0809 internal structure map as shown in Fig.7.Fig. 6 Sampling feedback circuitFig. 7 ADC 0809 internal structure mapThe keyboard moduleKeyboard module for computer systems usually have two kinds of keyboard: one category iscoded keyboard, and the other non-coding keyboard ,here I would like to choose a non-codingkeyboard 3x3 structure, which can automatically eliminate the impact of key jitter, has protection tothe key on the button and pressed at the same time, can the keyboard into the stack information, canalso be issued to the CPU interrupt request, after the response, so that CPU access to key information,it is still acceptable CPU inter-team information inquiries.1319

AT89C52 single-chip microcomputer systems and peripheral circuitsIn circuit design I chose the most common ATMEL Corporation AT89C52 single-chipmicrocomputer. This single-chip microcomputer with the MCS-51 instruction set is fully compatiblewith products from 8K bytes Flash re-write flash memory, 256 8 bytes of internal RAM, 32programmable I / O port line, 2 16 timer / counter and 6 interrupt sources. And single-chipmicrocomputer is economical and practical, widely used, its main parts of the circuit as shown 810k10uD6VCCC2100UTXD 10RXD 11121314151617P10P11P12P13P14P15P16P17RESETRXD P3.0TXD P3.1INT0 P3.2INT1 P3.3T0 P3.4T1 P3.5WR P3.6RD ��控单片机Vss89C52EA/VPALE/PPSEN39 RCLK38373635343332212223242526272840VCC313029Fig. 8 The control circuit diagramThis design through the MCU as the core to control, plus a number of peripheral circuits bycontrolling the D / A converter input to change the final output, to achieve the purpose of NC. Asmentioned above, the NC power supply has many obvious advantages, such as output in a certainrange for, as a signal source to be able to output, through software changes to achieve many of thefeatures, without the need to change the number of hardware circuit wiring. Finally, by the test ofultimate system performance, design has proven that system output is with high accuracy, and canachieve the desired objective.References[1] J.Sun and H.Grotstollen.Symbolic analysis methods for averaged modeling of switching powerconverters[J].IEEE Transactions on Power Electronics,1997,12(3):537-546.[2] Lin Bor-Ren,@Hua Chihchiang,Hua Chihchiang.Uninterruptible Power Supply With FuzzyLogic Approach.Industrial Electronics,Control,and Instrumentation, 1993. Proceedings of theIECON ‘93.International Conference on.vol. 2:1123 1128.[3] Dixon.L.H.Average current Mode Control of Switching Power Supplies.Unitrode Power SupplyDesign Semi-nar Manual SEM700.1990.[4] C.Deisch.Simple switching control method changes power converter into a currentsource[C].Proc.IEEE Power Electronics Specialists Conf.1978,:300 306.[5] Daniel MMitchell.An Analytical Investigation of Current-Injected Control forConstant-Frequency Switching Regulators[J].IEEE Transactions on Power Electronics,1986,(7):167-174.[6] Robert Mammano.Switching Power Supply Topology Voltage Mode vs. Current Mode.Unitrode Product & Applications Handbook.1995-96.[7] Lloyd Dixon.Average Current Mode Control of Switching Power Supply. Unitrode Product &Applications Handbook.:1995-96.1320

The subject in the current traditional reference sources, and ordinary NC current source, on the basis of fully considering the cost performance while greatly enhancing the NC accuracy of the current source, the power supply can be constant voltage and constant current output, Press

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