EECS 192: Mechatronics Design Lab Discussion 4: Project Proposal - - PowerPoint PPT Presentation

▶
eecs 192 mechatronics design lab
SMART_READER_LITE
LIVE PREVIEW

EECS 192: Mechatronics Design Lab Discussion 4: Project Proposal - - PowerPoint PPT Presentation

Dec 31, 2022 32 likes •293 views

EECS 192: Mechatronics Design Lab Discussion 4: Project Proposal Feedback & Power Systems GSI: Varun Tolani 7 & 8 Feb 2017 (Week 4) 1 Project Proposal Feedback 2 SMPS Recap 3 Practical Application 4 Summary Ducky (UCB EECS) Mechatronics

slide-1
SLIDE 1

EECS 192: Mechatronics Design Lab

Discussion 4: Project Proposal Feedback & Power Systems GSI: Varun Tolani 7 & 8 Feb 2017 (Week 4)

1 Project Proposal Feedback 2 SMPS Recap 3 Practical Application 4 Summary

Ducky (UCB EECS) Mechatronics Design Lab 7 & 8 Feb 2017 (Week 4) 1 / 21

slide-2
SLIDE 2

Project Proposal Feedback

Project Proposal Feedback

Ducky (UCB EECS) Mechatronics Design Lab 7 & 8 Feb 2017 (Week 4) 2 / 21

slide-3
SLIDE 3

Project Proposal Feedback

Feedback

◮ IO ◮ Motor Drive ◮ Software

Ducky (UCB EECS) Mechatronics Design Lab 7 & 8 Feb 2017 (Week 4) 3 / 21

slide-4
SLIDE 4

Project Proposal Feedback

IO

◮ Sensors

◮ Line scan camera(s) ◮ encoder/ back emf sensor

◮ Other

◮ Bluetooth

◮ Links

◮ Line Scan Camera 1, Line Scan Camera 2 ◮ Optical Encoder ◮ Bluesmirf Chip

TSL1401CL Optical Encoder

Ducky (UCB EECS) Mechatronics Design Lab 7 & 8 Feb 2017 (Week 4) 4 / 21

slide-5
SLIDE 5

Project Proposal Feedback

Motor Drive

◮ G en

◮ Needs 5V!!!! ◮ Pull down resistor (6.8k good)

◮ Shoot through protection

◮ Logic protection circuit ◮ Inverted PWM via code

◮ General

◮ Heatsinks ◮ Layout

Complimentary PWM Mosfet Package

Ducky (UCB EECS) Mechatronics Design Lab 7 & 8 Feb 2017 (Week 4) 5 / 21

slide-6
SLIDE 6

Project Proposal Feedback

Software

◮ Timing

◮ Timers ◮ Main/threads

◮ Frequencies

◮

100s of hz

◮ General

◮ Keep it simple!!!

Software Timing

Ducky (UCB EECS) Mechatronics Design Lab 7 & 8 Feb 2017 (Week 4) 6 / 21

slide-7
SLIDE 7

SMPS Recap

Switching Power Supply

Ducky (UCB EECS) Mechatronics Design Lab 7 & 8 Feb 2017 (Week 4) 7 / 21

slide-8
SLIDE 8

SMPS Recap Buck Converter Theory

DC-DC Converter

◮ 3 Cell LiPo Battery provides 11-12V

◮ Good for motor, driver chip/ op amp

◮ We also need 5V?

◮ K64F, servo, optical encoder, camera, etc.

◮ How to consistently get 5V?

◮ DC-DC converter! ◮ Step Down ◮ Buck Converter, Linear Regulator ◮ Step Up ◮ Boost Converter

Buck Converter

Ducky (UCB EECS) Mechatronics Design Lab 7 & 8 Feb 2017 (Week 4) 8 / 21

slide-9
SLIDE 9

SMPS Recap Buck Converter Theory

Buck Converter Circuit

◮ DC-to-DC switching power supply

generating output voltage lower than input

◮ Uses inductor as storage element ◮ Efficient, no losses in ideal case

◮ Non-idealities: wire resistance, diode and

transistor losses

◮ Capacitive filter to smooth output voltage

Buck Converter

Ducky (UCB EECS) Mechatronics Design Lab 7 & 8 Feb 2017 (Week 4) 9 / 21

slide-10
SLIDE 10

SMPS Recap Buck Converter Theory

Buck Converter Operation

◮ Inductor charges when switch is closed

◮ Energy stored in inductor by magnetic

field, current through inductor increases

◮ Diode does nothing here

Switch Closed

Ducky (UCB EECS) Mechatronics Design Lab 7 & 8 Feb 2017 (Week 4) 10 / 21

slide-11
SLIDE 11

SMPS Recap Buck Converter Theory

Buck Converter Operation

◮ Inductor charges when switch is closed

◮ Energy stored in inductor by magnetic

field, current through inductor increases

◮ Diode does nothing here

◮ Inductor discharges when switch is open

◮ Magnetic field dissipates, current through

inductor decreases

◮ Inductor voltage polarity reversed,

generating voltage over input

◮ Current flows through diode, output

capacitor charged

Switch Open

Ducky (UCB EECS) Mechatronics Design Lab 7 & 8 Feb 2017 (Week 4) 10 / 21

slide-12
SLIDE 12

SMPS Recap Buck Converter Theory

Buck Converter Control

◮ If switch cycled fast enough, inductor does

not fully discharge

◮ Can do a lot of math, but output voltage is

function of duty cycle D

◮ Vout = DVin

Inductor charging Inductor discharging

Ducky (UCB EECS) Mechatronics Design Lab 7 & 8 Feb 2017 (Week 4) 11 / 21

slide-13
SLIDE 13

SMPS Recap Buck Converter Theory

Check your Understanding

◮ So I’ve got a buck converter set up... ◮ A magic chip (LM2678) regulates the

  • utput to 5v

◮ Duty cycle is adjusted to maintain voltage ◮ Remember: Vout = DVin

◮ What happens if I...

Buck Circuit

Ducky (UCB EECS) Mechatronics Design Lab 7 & 8 Feb 2017 (Week 4) 12 / 21

slide-14
SLIDE 14

SMPS Recap Buck Converter Theory

Check your Understanding

◮ So I’ve got a buck converter set up... ◮ A magic chip (LM2678) regulates the

  • utput to 5v

◮ Duty cycle is adjusted to maintain voltage ◮ Remember: Vout = DVin

◮ What happens if I...

◮ Increase the input voltage?

Buck Circuit

Ducky (UCB EECS) Mechatronics Design Lab 7 & 8 Feb 2017 (Week 4) 12 / 21

slide-15
SLIDE 15

SMPS Recap Buck Converter Theory

Check your Understanding

◮ So I’ve got a buck converter set up... ◮ A magic chip (LM2678) regulates the

  • utput to 5v

◮ Duty cycle is adjusted to maintain voltage ◮ Remember: Vout = DVin

◮ What happens if I...

◮ Increase the input voltage? ◮ Duty cycle decreases, current decreases

Buck Circuit

Ducky (UCB EECS) Mechatronics Design Lab 7 & 8 Feb 2017 (Week 4) 12 / 21

slide-16
SLIDE 16

SMPS Recap Buck Converter Theory

Check your Understanding

◮ So I’ve got a buck converter set up... ◮ A magic chip (LM2678) regulates the

  • utput to 5v

◮ Duty cycle is adjusted to maintain voltage ◮ Remember: Vout = DVin

◮ What happens if I...

◮ Increase the input voltage? ◮ Duty cycle decreases, current decreases ◮ Decrease the input voltage?

Buck Circuit

Ducky (UCB EECS) Mechatronics Design Lab 7 & 8 Feb 2017 (Week 4) 12 / 21

slide-17
SLIDE 17

SMPS Recap Buck Converter Theory

Check your Understanding

◮ So I’ve got a buck converter set up... ◮ A magic chip (LM2678) regulates the

  • utput to 5v

◮ Duty cycle is adjusted to maintain voltage ◮ Remember: Vout = DVin

◮ What happens if I...

◮ Increase the input voltage? ◮ Duty cycle decreases, current decreases ◮ Decrease the input voltage? ◮ Duty cycle increases, current increases

Buck Circuit

Ducky (UCB EECS) Mechatronics Design Lab 7 & 8 Feb 2017 (Week 4) 12 / 21

slide-18
SLIDE 18

SMPS Recap Related Topologies

Boost Converter Circuit (for your reference)

◮ DC-to-DC switching power supply

generating output voltage lower than input

◮ Similar principle to buck converter

◮ Vout =

1 1−DVin

◮ Also exists buck-boost converters, where

  • utput can be greater than, equal to, or

less than the input Boost Converter

Ducky (UCB EECS) Mechatronics Design Lab 7 & 8 Feb 2017 (Week 4) 13 / 21

slide-19
SLIDE 19

SMPS Recap Related Topologies

Questions?

got it?

power supply pros, right? Ducky (UCB EECS) Mechatronics Design Lab 7 & 8 Feb 2017 (Week 4) 14 / 21

slide-20
SLIDE 20

Practical Application

Practical Application

Ducky (UCB EECS) Mechatronics Design Lab 7 & 8 Feb 2017 (Week 4) 15 / 21

slide-21
SLIDE 21

Practical Application Basics

Automatic Feedback Control

◮ So, what is the switch-controlling magic? ◮ Feedback control: chip has logic to

regulate the voltage on the feedback pin to an internal VFB = 1.21V reference

◮ Vout = VFB(1 + R2 R1 ) ◮ R1 ≈ 1kΩ recommended

LM2678 Block Diagram Application circuit

Ducky (UCB EECS) Mechatronics Design Lab 7 & 8 Feb 2017 (Week 4) 16 / 21

slide-22
SLIDE 22

Practical Application Issues

Problematic?

◮ What happens if the switch get stucks in

the closed position? Boost Circuit

Ducky (UCB EECS) Mechatronics Design Lab 7 & 8 Feb 2017 (Week 4) 17 / 21

slide-23
SLIDE 23

Practical Application Issues

Layout is Important!!!

Boost Circuit

Ducky (UCB EECS) Mechatronics Design Lab 7 & 8 Feb 2017 (Week 4) 18 / 21

slide-24
SLIDE 24

Practical Application Issues

Layout Guidelines

◮ Switching power supplies are layout

sensitive

◮ Part placement and routing matters!

◮ Tips from the datasheet:

◮ Keep diode and filter capacitor

connections as short as possible

◮ Minimize high frequency current path

(switch, diode, capacitor)

◮ Read the datasheet!

Recommended layout

(uses surface-mount components) source: datasheet, Linear Technology Ducky (UCB EECS) Mechatronics Design Lab 7 & 8 Feb 2017 (Week 4) 19 / 21

slide-25
SLIDE 25

Practical Application Issues

Supporting Componenets

◮ Capacitors

◮ Ceramic, film, polarized (tantalum,

aluminum, etc.)...

◮ Diodes

◮ Shottky

◮ Inductor

◮ Toroid

Toroid Inductor

Ducky (UCB EECS) Mechatronics Design Lab 7 & 8 Feb 2017 (Week 4) 20 / 21

slide-26
SLIDE 26

Summary

Summary

Summary

◮ Buck converters step down a DC voltage to a lower DC voltage ◮ LM2678 uses feedback control to do voltage regulation ◮ Follow recommended layout guidelines during PCB design ◮ Very difficult to make work on perfboard- just design it on the pcb.

Parts Handout

◮ Get a Servo

Office hours for the rest of the section

◮ PCB deadline coming up in a week! Need help? Get it now!

Ducky (UCB EECS) Mechatronics Design Lab 7 & 8 Feb 2017 (Week 4) 21 / 21