Vibration Energy Harvesing with PZT Cantilevers and Mxximum Power Point Tracking
1
Multifunctional Integrated Circuits and Systems Multifunctional Integrated Circuits and Systems Vibration Energy Harvesing with PZT Cantilevers and Mxximum Power Point Tracking Na Kong (MS or Ph.D.) and Dong S. Ha ECE Dept, Virginia Tech, Virginia Motivation: • Vibration energy is abundant in nature. • Example Sources and Applications Automobiles, bridges, industry machines, and human body. Wireless sensor nodes, Portable devices • PZT cantilevers offer high density and scale well. Impedance Matching: • The maximum power is transferred under the complex conjugate matching. However, the required inductance is impractical. • Resistive matching is adopted. Maximum Power Point Tracking: • It sets the input resistance of the DC/DC converter to the optimal value dynamically under varying operation condition. • A sophisticated algorithm can harvest more energy, but higher power dissipation. The goal is to maximize the net harvested energy. A “Perturb and Observation” algorithm is simple and effective. Proposed System: • A microcontroller unit (MCU) implements the MPPT – flexible. • Flyback Converter Z L PZT Low Power Controller Design: • Adopt constant on-time control for a lower clock frequency. • Duty cycle for the MPPT algorithm Execute the MPPT algorithm for 20 ms at 8-MHz clock, and go to the sleep mode for 2 sec at 1-MHz clock. Conclusion: • The MCU-based approach is flexible and achieves reasonably high efficiency. • Future improvements, use a synchronous rectifier. an ASIC for the controller. Experiment Set Up: 4 PZT Cantilevers Converter and Controller Efficiency: • 62 – 73 % under 0.5g base acceleration • Breakdown of losses Did power to battery increase? Decrease load resistance. Did power to battery increase? No No Yes Yes Increase load resistance. Average power 44 45 46 47 48 49 50 51 52 53 0 2 4 6 8 10 12 B ase V ibration Frequency (H z) O utputPower(m W ) O ursystem R esistorload 44 45 46 47 48 49 50 51 52 53 60 65 70 75 80 85 90 95 100 B ase V ibration Frequency (H z) E fficiency (% ) M PPT C onversion O verall 10 2 10 3 10 4 10 1 10 2 10 3 10 4 10 5 R in ( ) C lock frequency (kH z) C onstantFs,R in=50k C onstantFs,R in=10k C onstantTon 1 MHz 10 MHz 50 MHz Sleep 110 uA for 2 sec MPPT 2.6 mA for 20 ms s Lm m avg T i L P 2 2 max , Mechanical Model Equivalent Input Resistance MCU PZT Cantilever Constant Frequency Control Constant On-time Control in out conversion P P I AC R s L s C s C p d t T on T s T off d t T on T s T on R ectifier Energy Storage Device DC/DC C onverter C ontroller Load Energy Harvesting Sources max out overall P P max in MPPT P P
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Vibration Energy Harvesing with PZT Cantilevers and Mxximum Power Point Tracking. Na Kong (MS or Ph.D.) and Dong S. Ha ECE Dept , Virginia Tech , Virginia. PZT. Motivation: Vibration energy is abundant in nature. Example Sources and Applications - PowerPoint PPT Presentation
Transcript of Vibration Energy Harvesing with PZT Cantilevers and Mxximum Power Point Tracking
Multifunctional Integrated Circuits and SystemsMultifunctional Integrated Circuits and Systems
Vibration Energy Harvesing with PZT Cantilevers and Mxximum Power Point Tracking
Na Kong (MS or Ph.D.) and Dong S. HaECE Dept, Virginia Tech, VirginiaMotivation:
• Vibration energy is abundant in nature.• Example Sources and Applications
Automobiles, bridges, industry machines, and human body.
Wireless sensor nodes, Portable devices• PZT cantilevers offer high density and scale
well.
Impedance Matching:• The maximum power is transferred under the
complex conjugate matching. However, the required inductance is impractical.
• Resistive matching is adopted.
Maximum Power Point Tracking:• It sets the input resistance of the DC/DC
converter to the optimal value dynamically under varying operation condition.
• A sophisticated algorithm can harvest more energy, but higher power dissipation. The goal is to maximize the net harvested energy. A “Perturb and Observation” algorithm is
simple and effective.
Proposed System:• A microcontroller unit (MCU) implements the
MPPT – flexible.
• Flyback Converter
IAC
Rs
Ls
Cs
CpZL
PZT
Low Power Controller Design:• Adopt constant on-time control for a lower
clock frequency.
• Duty cycle for the MPPT algorithm Execute the MPPT algorithm for 20 ms at 8-MHz clock, and go to the sleep mode for 2 sec at 1-MHz clock.
Conclusion:• The MCU-based approach is flexible and
achieves reasonably high efficiency.• Future improvements, use
a synchronous rectifier. an ASIC for the controller.
Experiment Set Up: 4 PZT Cantilevers Converter and Controller
Efficiency:• 62 – 73 % under 0.5g base acceleration
• Breakdown of losses
Did power to battery
increase?
Decrease load resistance.
Did power to battery
increase?
NoNo
Yes Yes
Increase load resistance.
Average power
44 45 46 47 48 49 50 51 52 530
2
4
6
8
10
12
Base Vibration Frequency (Hz)
Out
put
Pow
er (
mW
)
Our system
Resistor load
44 45 46 47 48 49 50 51 52 5360
65
70
75
80
85
90
95
100
Base Vibration Frequency (Hz)
Eff
icie
ncy
(%)
MPPT
Conversion
Overall
d
tTon
Ts DToff
d
tTon
Ts
DTon
102
103
104
101
102
103
104
105
DRin ()
Clo
ck f
requ
ency
(kH
z)
Constant Fs, Rin=50k
Constant Fs, Rin=10kConstant Ton
1 MHz
10 MHz
50 MHz
Sleep110 uA for
2 sec
MPPT 2.6 mA for
20 ms
s
Lmmavg T
iLP
2
2max,
Mechanical Model
Equivalent Input Resistance
RectifierEnergy Storage Device
DC/DC Converter
Controller
LoadEnergy
Harvesting Sources
MCU
PZT Cantilever
Constant Frequency Control
Constant On-time Control
max
outoverall P
P
max
inMPPT P
P
in
outconversion P
P
