ppt-dc to dc converter
TRANSCRIPT
CONTROL OF DC-DC CONVERTER USING MICROCONTROLLER
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 pulse-width modulation or frequency modulation.
• The basic types of Converters are BUCK,BOOST,BUCK-BOOST and CUK.
DC-DC CONVERTERS
BUCK CONVERTER
BOOST CONVERTER
BUCK-BOOST
CUK CONVERTER
BUCK CONVERTER
OPERATION
CONTINUOUS MODE
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.
PIC16F785 MICROCONTROLLER
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
CONTROL OF BUCK CONVERTER
BLOCK DIAGRAM
COMPARATOR
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.
TEST RESULTS
PWM OUTPUT- Case1
Vin= 20V Duty Cycle= Ton/T = 0.624
MOSFET GATE DRIVE- Case1
Vin= 20V Duty Cycle = Ton/T= 0.237
Vout= Vin * Duty Cycle = 4.75V
OUTPUT OF BUCK- Case 1
Vout = 4.8 V
PWM OUTPUT – Case 2
Vin= 23V Duty Cycle= Ton/T = 0.564
MOSFET GATE DRIVE- Case2
Vin= 23V Duty Cycle = Ton/T= 0.209
Vout= Vin * Duty Cycle = 4.8V
OUTPUT OF BUCK – Case 2
Vout = 4.8 V
PROS AND CONS
ADVANTAGES
• In-Circuit Programmability of parameters– Code can be altered at any
stage of design
• Other control functions and communication interfaces can also be performed using Microcontroller.
• Less power consumption.
DISADVANTAGES
• Level shifting is required to Drive the MOSFET.– Can be overcome by using
Logic Level MOSFETs
• External SYNC pulse required– Can be generated using PIC
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.
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
THANK YOU