Electronic Interface Circuitries for Kinetic Energy Harvesters

Transcription

1 Electronic Interface Circuitries for Kinetic Energy Harvesters Hannovermesse 2011 Philipp Becker Institut für Mikro- und Informationstechnik der Hahn-Schickard Gesellschaft e.v. HSG-IMIT Wilhelm-Schickard-Str. 10, D Villingen-Schwenningen, Germany phone: fax: Philipp Becker / / slide 1

2 Outline State of the art Interface circuitry Interface for electromagnetic energy harvesters Adaptive Switched Capacitors Interface for piezoelectric energy harvesters Parallel SSHI Direct SSHI: Basic idea of self triggered direct SSHI Generator design SSHI circuitry and control unit Measurement results Outlook Philipp Becker / / slide 2

3 State of the art Vibration Energy harvester DC/DC converter Sensor A Rectifier µcontroller Sensor B Energy storage RF Philipp Becker / / slide 3

4 State of the art A lot of the energy provided by the energy harvester remains unused. Interface circuitry Energy Harvester Rectifier Storage Capacitor Philipp Becker / / slide 4

5 Energy harvesters Electromagnetic energy harvester Characteristic values Relatively low output voltage Relatively high output current Piezoelectric energy harvester Characteristic values Relatively high output voltage Relatively low output current Philipp Becker / / slide 5

6 Interface for electromagnetic EH Basic concept of Adaptive Switched Capacitor Interface (Maurath et. al.) Voltage conversion by changing the arrangement of a capacitor array V buf C5 S t5 C6 S t6 V stack C3 S 24 C4 S 46 C buf C1 S 13 C2 S 24 S g2 charge state transfer state buffer Philipp Becker / / slide 6

7 Interface for piezoelectric EH Basic concept of parallel SSHI interface (Guyomar et. al.) Switch-on momentary a coil in parallel to the piezoelectric generator vibration source Energy Harvester Interface Rectifier Storage Capacitor control unit Philipp Becker / / slide 7

8 Parallel SSHI Exact trigger points Highly sensitive influencing parameter Switch-on at voltage maximum No exact trigger information due to rectifier and storage capacitor Default settings Not possible under varying excitation conditions Sensor to observe the piezo movement Increases the energy consumption of the entire system Philipp Becker / / slide 8

9 Direct SSHI vibration source Energy Harvester Interface Rectifier Storage Capacitor control unit etched zone trigger electrode main electrode Energy Harvester / trigger generator 2 electrode structures on the same substrate Interface SSHI (Guyomar et. al.) Philipp Becker / / slide 9

10 Energy Harvester First prototype of the piezoelectric generator Piezoelectric bimorph beam with 2 separated electrode structures Relatively big trigger electrode for the test structure Size may be reduced for the end device Philipp Becker / / slide 10

11 Energy Harvester Generator design Different electrode structures Philipp Becker / / slide 11

12 Energy Harvester Piezoelectric bimorph beam with 2 separated electrode structures FEM simulation for calculation of the resonance frequency Main generator & trigger generator Measurement results etched zone trigger electrode main electrode FEM simulation results Measurement results voltage / V 5,5 5 4,5 4 3,5 3 2,5 2 1,5 1 0,5 main trigger frequency / Hz Philipp Becker / / slide 12

13 Generator deformation FEM simulation Laser vibrometer measurements Philipp Becker / / slide 13

14 Generator Design Electrical Simulation Electro-mechanical analogues equivalent circuit input for spice based simulations Philipp Becker / / slide 14

15 Measurement results Voltage signals of: Main electrode Trigger electrode Main electrode + SSHI Interface Trigger electrode Interface control unit trigger point Philipp Becker / / slide 15

16 Charging a capacitor Measurement results: Charging an energy storage (Capacitor: 47µF) W = ½ CU² Standard Direct SSHI 2,6V ~159µJ 1,6V ~60µJ Philipp Becker / / slide 16

17 Outlook Conclusion Different types of energy harvesters need different types of interfaces Interface circuits can enhance the usable energy Future work: Integrated CMOS circuitry Optimization of the electrode structures Smaller trigger electrode Philipp Becker / / slide 17

18 Contact information Thank You for Your Attention! Philipp Becker Institut für Mikro- und Informationstechnik der Hahn-Schickard Gesellschaft e.v. HSG-IMIT Wilhelm-Schickard-Str. 10, D Villingen-Schwenningen, Germany phone: fax: Philipp Becker / / slide 18