Back-up Power Generating Door

1
Back-up Power Generating Door

• Group 21
• Kyle Rasmussen
• Michael Gan
• Allen Huang

2
Introduction

• This project converts mechanical energy from
  opening a door into electrical energy for a
  backup power supply. This green energy solution
  makes use of an everyday occurrence to protect
  against intermittent power loss.

3
Features

• Provides 120Vrms / 60Hz during intermittent power
  loss
• Easily deployable on any door fixture
• Senses power loss and automatically switches to
  backup power

4
Block Diagram Overview of Device
Regulation And Storage
Mechanical To Electrical
dc to ac Conversion
Recognition And Release
5
Overview

• Mechanical Transfers wide arc of door swing into
  spin on a mechanical shaft
• Generator Transforms rotation of shaft into
  electrical energy
• Charge/storage Stores energy created from the
  generator by charging it in a battery
• Converter Converts the DC power from the battery
  into AC power
• Transfer Switch Taps into the power from the
  battery to provide electrical control signals
  needed for the project to operate as well as
  controlling to flow of energy between each module
• Detection Detects power loss in the main power
  line and sends the appropriate signal to the
  transfer switch

6
Mechanical to Electrical Introduction

• This portion utilizes a series of gears to
  translate the swing of a door into rotational
  motion.
• The rotational motion is fed to a generator to
  convert mechanical energy into electricity.
• For our device to provide backup power for
  15min., each door use must generate 22.5J from
  the generator.

7
Mechanical Overview

• Capture motion from an opening and closing door
• Convert Kinetic Energy into Electrical Energy
• Provide enough energy to charge battery

8
Mechanical Components
9
Capture Design

• Mountable with screws
• Arms made from metal bars
• Rotates with door for 1.05 rad/sec

• Changed significantly from original design

10
Arm Kinematics
 
 
 
 
Denavit-Hartenberg Parameters
a a d ?
1 12 0 0
2 12 0 1
3 12 0 0
 
 
 
 
11
Gear Train and Generator

• Overall gear ratio of 1128
• Hand picked gears from local hobby store
• Placed on machined platforms

• Generator acquired from power lab

12
Construction

• Metal Grinder
• Fashioned arms
• Customized gears

13
Testing Generator Speed with Output
Trial Vm (V) Vtg (V) Vgavg (V) Vgpp (V) fg (Hz) RPM calc
1 4 0.636 2.837 0.438 67.6 212
2 8 1.713 6.923 0.875 168.9 571
3 12 2.656 10.624 1.68 260 885
4 12.5 2.826 11.238 2.00 270.3 942
5 16 3.699 14.879 2.50 359.3 1233
Verified rated speed of generator Determined
speed necessary for 14.88V into Buck Converter
14
Load Testing Generator
Trial Vm (V) Idc (A) Speed (RMS) Vgavg (V) Iload (A) Load ?
1 16 0.5 1200 14.48 0 0
2 16 0.6 1200 13.60 0.027g 500
3 16 0.6 1200 14.51 0.052 1000
4 16 0.6 1200 14.517 0.0837 1.5K
5 16 0.6 1200 14.03 0.111 2.0K
6 16 0.7 1133 14.03 0.138 2.5K
7 16 0.7 1133 14.04 0.164 3.0K
8 16 0.7 1200 13.7 0.189 3.5K
Motor-Generator Configuration Measuring power
output in response to different loads
15
Voltage Regulator

• Protects battery from surging generator
• Must handle voltage swings of /- 2.5V
• Limits charging current ripple to /- 2
• Maintains charging voltage at 12V /- 1

16
Voltage Regulator

• Buck Converter
• Steps down voltage from generator
• Hysteresis Controller
• Feedback control of Buck Converter
• MOSFET Driver
• Steps up switching signal from Hysteresis
  Controller

17
Voltage RegulatorBuck Converter

• Input voltage ranges from 13.63V to 16.13V.
• Per specification of the battery, the maximum
  allowable output current was chosen to be 3.33A.
• Assuming fswitch 100kHz, solving for VL L
  di/dt and Ic Cdv/dt yields
• L 229uH
• C 122.1uF

18
Voltage RegulatorHysteresis Controller

• Compares Buck Converter output (V-) to Vth
• Voltage comparator outputs high if V- lt Vth
• Outputs low if V- gt Vth

19
Voltage RegulatorHigh-Side Driver

• Converts output of Hysteresis controller to 18.5V
• Establishes Vgs gt Vth for Buck Converter MOSFET.

20
Voltage RegulatorTesting Buck Converter

• Vin sweep from 12.4V to 17.38V

Trial 1 2 3 4 5 6
Vin 12.4 13 14 14.88 16 17.38
Vout avg 11.58 11.93 11.99 12.03 12 12.08
Vout p-p 313 344 344 344 344 344
21
Voltage RegulatorTesting Buck Converter
Snapshot of output during testing

• Conclusions
• At the upper level of this sweep, the Buck
  Converter was still able to keep the output
  voltage within 1 of the nominal.
• It is clear that the regulator could handle the
  2.5V swing expected from the generator.
• While the ripple voltage was higher than
  expected, this is mostly due to the switching
  frequency it was tested at.

22
Voltage Regulator

• What went wrong?
• An unsuccessful transfer of the regulator to the
  PCB board
• On proto-board, Hysteresis not outputting
• This can be fixed with simple debugging

23
Transfer Switch and Driver Signals
24
Driver Signals

• 12V provided by main lead acid battery
• 15V provided by boost converter
• 6V and 18V provided by external small batteries

18 V
15 V
12 V
6V
25
Boost Converter

• Materials Used
• Power Inductor Self wound
• Schottky diode - MBR360
• Power MOSFET IRF540
• PWM Chip - UC2843, High performance PWM
  controller
• Capacitors frequency adjustment and charging
  output
• Resistors voltage divider for feedback

26
Boosting Operation

• On State
• Switch 1 is On, Switch 2 is Off
• Inductor charges / current increases
• Capacitor discharged across load
• Output voltage decreases
• Off State
• Switch 1 is Off, Switch 2 is On
• Inductor discharges / current decreases
• Capacitor gets charged
• Output voltage increases

S2
S1
S2
S1
www.coilgun.eclipse.co.uk/
27
Component Selection Calculations
http//focus.ti.com/docs/prod/folders/print/uc3843
.html

• Selection of R and C connected to the pins.
  Aiming for Freq 100K. Looking at the graph for
  Timing Resistance vs. Frequency, R 10K and C
  2nF.
• Need to select voltage divider to bring to the
  feedback pin. Output is selected at 15V and
  internal comparator voltage is 2.5V. This means a
  voltage division of 1/6 is needed. 120K and 20K
  resistor is chosen

28
Boost Converter Schematic
29
Boost Converter Output

• Average output voltage is 14.7V. Ripple occurs
  when MOSFET switches to discharge capacitor in
  order to lower output voltage.

30
Testing the boost converter

• Line Regulation
• Varied input voltage and fixed load
• Measure of how well the boost converter handles
  various input voltages
• Load Regulation
• Fixed input voltage and varied load
• Measure of how well the boost converter maintains
  15V

31
Line Regulation Tables
Load Input voltage (V) Output Voltage (V)
0 ? No Load 10.0 15.0
0 ? No Load 10.5 15.0
0 ? No Load 11.0 15.0
0 ? No Load 11.5 15.0
0 ? No Load 12.0 15.0
0 ? No Load 12.5 15.0
0 ? No Load 13.0 15.1
0 ? No Load 13.5 15.1
0 ? No Load 14.0 15.1
0 ? No Load 14.5 15.2
0 ? No Load 15.0 15.4
Load Input voltage (V) Output Voltage (V)
6.2 ? 10.0 9.782
6.2 ? 10.5 10.265
6.2 ? 11.0 10.769
6.2 ? 11.5 11.262
6.2 ? 12.0 11.731
6.2 ? 12.5 12.218
6.2 ? 13.0 12.717
6.2 ? 13.5 13.204
6.2 ? 14.0 13.696
6.2 ? 14.5 14.193
6.2 ? 15.0 14.697
Load Input voltage (V) Output Voltage (V)
16 ? 10.0 9.907
16 ? 10.5 10.406
16 ? 11.0 10.893
16 ? 11.5 11.414
16 ? 12.0 11.894
16 ? 12.5 12.385
16 ? 13.0 12.876
16 ? 13.5 13.378
16 ? 14.0 13.895
16 ? 14.5 14.388
16 ? 15.0 14.870
Load Input voltage (V) Output Voltage (V)
51 ? 10.0 9.977
51 ? 10.5 10.478
51 ? 11.0 10.977
51 ? 11.5 11.470
51 ? 12.0 11.974
51 ? 12.5 12.478
51 ? 13.0 12.972
51 ? 13.5 13.468
51 ? 14.0 13.973
51 ? 14.5 14.480
51 ? 15.0 14.970
2.67
32.77
33.09
33.29
32
Line Regulation vs. Input Voltage
33
Load Regulation Table
Load (?) Input Voltage (V) Output Voltage (V) Input Current (A) Output Current (A) Load Regulation () Output Power (W)
3.0 12 11.80 3.84 3.831 23.89 45.21
6.2 12 13.13 2.13 2.123 11.35 27.87
16 12 14.00 0.88 0.873 4.42 12.22
18 12 14.07 0.78 0.779 3.91 10.96
28 12 14.26 0.51 0.507 2.52 7.23
51 12 14.43 0.28 0.28 1.32 4.04
34
Load Regulation vs. Load

• Load Regulation is better for higher loads
• Ideally you want 0 load regulation
• Why almost 24 load regulation at 3??

35
Load Regulation vs. Output Power
36
Analysis of Load / Line Regulation

• Discrepancies

• Recommendations

• Line Regulation in 30s, Load Regulation in the
  10s to 20s
• Discontinuous mode operation - current in
  inductor to drop to 0A between switching cycles
• Inductor discharges into capacitor prematurely

• Increase duty cycle of the switch that drives the
  MOSFET
• Gives inductor more time to charge and less time
  to discharge

37
DC/AC ConverterObjectives

• Ideally,
• Transform 12Vdc from a battery into 12Vac
• Voltage waveform at 60Hz
• Smooth signal and eliminate harmonics with a
  filter

38
DC/AC ConverterGeneral Overview

• Voltage Sourced Inverter (VSI)
• Full Bridge Orientation
• Switches are Power MOSFETs with reverse-parallel
  diodes

39
DC/AC ConverterSwitching Overview

• Opposite switching signals to each leg
• Switching signals generated by astable
  multivibrator
• Voltages stepped up through MOSFET drivers

40
DC/AC ConverterSwitching Generation

• Astable Multivibrator
• Incorporates LM555 timer
• Thresholds established through voltage division
• Capacitor voltage triggers state changes

• Conceptual circuit
• Provide calculations in appendix to refer to

• Conceptual waveforms
• Or real if they are available

41
DC/AC ConverterSwitching Generation

• To realize a 60Hz square wave with 50 duty
• C 11.32 µF
• RA 120?
• RB 1K?

42
DC/AC ConverterSwitching Drivers

• 4V to 15V conversion
• Establish VGS VTH
• Two High-side
• LMD18400N (inv. non)
• Two Low-side
• MIC4427 (non)
• MIC4426 (inv.)

43
DC/AC ConverterSwitches Drivers
Signal to Switch 1,1
Signal to Switch 1,2
Signal to Switch 2,2
Signal to Switch 2,1
44
DC/AC ConverterInverter Output

• Leg one

• Signal across load

• Leg two

Signal 1 Inverter output voltage Signal 2 555
output voltage
45
DC/AC ConverterInverter Output

• Measured over 3? load
• Signal 1 Voltage out of Inverter
• Signal 2 Current out of Inverter

46
DC/AC ConverterInverter Output
As the power drawn from the battery increases, so
does the power loss over the inverter.
However, for the range of loads tested, the
losses turn out to be relatively proportional,
and the overall efficiency of the inverter
remains around 2/3.
47
DC/AC ConverterInverter Output

• Factors in Power Loss
• Pg 473 of Krein
• Need datasheet of MOS

48
DC/AC ConverterOutput Filtering

• Originally attempted to use LCR series resonant
  filter
• Balanced Q with L
• Given Q 3.4
• L 7.633mH
• C 921.8 µF

49
DC/AC ConverterOutput Filtration
1
2
3

1. 7.1ohm load (Vrms 7.87)
2. 3.55 ohm load (Vrms 4.96)
3. 1.1 ohm load (Vrms 2.56)

50
DC/AC ConverterOutput Filtration

• What went wrong?
• Not Core Saturation
• Inductors within volt-sec and amp-turn limits
• ESR
• Inductor had an ESR of 0.69?
• Increased power output meant greater voltage drop
• Additional Inductance
• Transformer introduced unaccounted for inductance
• Filter ceases to be resonant (XLgt XC)

51
TransformerOverview

• Step up voltage from inverter to 120Vrms
• From testing we know
• VPrimary 8.8Vrms
• Turns ratio is 8.8120

52
TransformerOutput
1
2

• For 1050 ohm load
• 1 Inverter output (Vrms 9.9, Arms 3.35)
• 2 Transformer output (Vrms 130, Arms 122mA)

53
TransformerOutput
High transformer efficiency implies Minimization
of Eddy current losses Minimization of Hysteresis
losses (i.e. small Hysteresis loop) This makes
sense, since we are operating at only 60Hz
54
Transfer Switch
Signal from Inverter ()(-)
Output ()(-)
Battery ()
Battery ()(-)
Inverter ()
Battery ()
Batter Charger ()
55
Switch Positions No Power Loss

• Main line power is fed through to output
• Inverter is disconnected from battery so it does
  not discharge it when it is not needed
• Battery charger linked to battery to charge it

56
Switch Positions Power Loss

• Main line power is disconnected from the output
• Inverter is allowed to draw power from the
  battery and feed it across the output
• Battery charger is disconnected from battery

57
Relay Switching Scheme
Power Loss Detection Relay
From Charger ()
12V control Signal
From Battery ()
High Power Switching Relay
High Power Switching Relay
To Inverter ()
To Battery ()
58
Transfer Switch Relaying Test
Switch 1
Switch 2
Switch 3
59
Relay Switch Efficiency
Test Number Voltage Probe Location Switch 1 Voltage Out (V) Switch 2 Voltage Out (V) Switch 3 Voltage Out (V)
1 From Wall NA 123.6 NA
1 Through Output NA 123.1 NA
2 18V Driver 18.948 18.948 18.948
2 Though Output 18.948 18.948 18.948
3 15V Driver 15.483 15.630 15.596
3 Through Output 15.479 15.625 15.595
4 12V Driver 12.540 12.540 12.498
4 Through Output 12.537 12.537 12.497
5 6V Driver 6.391 6.391 6.391
5 Through Output 6.391 6.391 6.391
Average Voltage Loss Average Voltage Loss lt 1 lt 1 lt 1
60
Conclusion

• Project derailed by unforeseen complications in
  both design and manufacturing
• End result was a backup power supply

61
Thank you!