Ppt-dc to Dc Converter

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<p>CONTROL OF DC-DC CONVERTER USING MICROCONTROLLER</p> <p>INTRODUCTION Satellites are man-made machines, that send radio waves down to Earth, and are used for communication and remote sensing applications. Various voltage levels are required for different types of payloads in the satellite. The various voltage levels are generated using DC-DC converters. The DC-DC Converters can be controlled either by pulsewidth modulation or frequency modulation. The basic types of Converters are BUCK,BOOST,BUCKBOOST and CUK.</p> <p>DC-DC CONVERTERS</p> <p>BUCK CONVERTER</p> <p>BOOST CONVERTER</p> <p>BUCK-BOOST</p> <p>CUK CONVERTER</p> <p>BUCK CONVERTER</p> <p>OPERATION</p> <p>CONTINUOUS MODE</p> <p>MICROCONTROLLER A microcontroller is a small computer on a single integrated circuit . Microcontrollers are used in automatically controlled products and devices, such as remote controls, power tools, and toys.</p> <p>PIC16F785 MICROCONTROLLER</p> <p>FEATURES Operating Voltage Range : 2.0V-5.5V Frequency Range : 8 MHz to 32 MHz Uses HARVARD Architecture Two Operational Amplifiers Two Independent Analog Comparators Two-Phase PWM Module</p> <p>CONTROL OF BUCK CONVERTER</p> <p>BLOCK DIAGRAM</p> <p>COMPARATOR</p> <p>ALGORITHM PIC Microcontroller is configured to use built-in Internal Oscillator and code protect off, watchdog timer off, power up timer on and brown out detector off. Ports and module pins are configured as analog or digital input and output. Port C is cleared. Bit 6 and 7 of port C are configured as input using port C tristate register. Op-amp is enabled by setting bit 7 as 1. Bit 3 and 0 of port A are configured as input using portA tristate register. Comparator is on, non-inverted, normal speed, output present on pin 17, inputs from op- amp and external ramp signal. PWM auto-shutdown is disabled, SYNC pin acts as system slave, PH1 is driven by PWM signal. PWM outputs are configured active low, frequency of PWM set to 4MHz,time period set to 100ksec. PWM phase 1 is configured active low, PH1 resets when C1OUT goes high.</p> <p>TEST RESULTS</p> <p>PWM OUTPUT- Case1</p> <p>Vin= 20V Duty Cycle= Ton/T = 0.624</p> <p>MOSFET GATE DRIVE- Case1</p> <p>Vin= 20V Duty Cycle = Ton/T= 0.237 Vout= Vin * Duty Cycle = 4.75V</p> <p>OUTPUT OF BUCK- Case 1</p> <p>Vout = 4.8 V</p> <p>PWM OUTPUT Case 2</p> <p>Vin= 23V</p> <p>Duty Cycle= Ton/T = 0.564</p> <p>MOSFET GATE DRIVE- Case2</p> <p>Vin= 23V Duty Cycle = Ton/T= 0.209 Vout= Vin * Duty Cycle = 4.8V</p> <p>OUTPUT OF BUCK Case 2</p> <p>Vout = 4.8 V</p> <p>PROS AND CONSADVANTAGES In-Circuit Programmability of parameters Code can be altered at any stage of design</p> <p>DISADVANTAGES Level shifting is required to Drive the MOSFET. Can be overcome by using Logic Level MOSFETs</p> <p> Other control functions and communication interfaces can also be performed using Microcontroller. Less power consumption.</p> <p> External SYNC pulse required Can be generated using PIC</p> <p>APPLICATIONS Used to generate various voltage levels required for different subsystems of a satellite. Can be used for Regulation of Satellite Power Bus. Can be used to generate Auxiliary Power Buses from Satellite Primary Power Bus.</p> <p>CONCLUSION The successful control of a Buck Converter using PIC16F785 microcontroller was achieved. Future enhancements can be control of multiple DC-DC Converters with a single Microcontroller by using both the phases of PWM, control of Isolated Buck Converters, etc</p> <p>THANK YOU</p>