Synchronized Switch Harvesting Technique Applied to Electromagnetic Vibrations Harvester

E. Arroyo, A. Badel, F. FormosaContact : earro@univ-savoie.fr

Objectives Model of an electromagnetic generator

Classical extraction circuit

Autonomous sensor node

Mechanical Energy ( Vibrations )

Non usable electrical energy

Usable electrical energy

Mechanical energy inside the gene.

Mech.-to-elec. conversion

Vibrations

Mech.-to-mech. conversion

Ener

gy h

arve

ster

Electrical extraction circuit

- Minimal losses

- Usable DC voltage levels

- Self-supply of the circuit - Large bandwidth

- Highest possible power

Application of non-linear techniques developed for piezoelectric generators to electromagnetic generators

Optimization of the electrical extraction circuit for electromagnetic generators

Comparison with classical extraction technique

Experimentation

PR strongly dependent on the load

Experiments

PSMFE constant from R = 1kΩ

AC voltage level < 0.2V

Usually increased by increasing the number of turns of the coil, at the detriment of the energy density

Usable DC voltage

+ RectifierLow voltage level

From 1 to 30 V

Simplified linear model

P overestimated

T

Charge of C2

Charge of C1

T/2

Commutation at each extremum of current

SMFE circuitModels

Simulations

Performed on a non optimized generator

k²= 0.03%ξe = 1

Resonance frequency : 153 Hz

Charge of C1 or C2

PR:

Harvested power with the classical technique, with matching impedance

PSMFE:

Harvested power with the SMFE technique

Generator parameters:

For low ξe :

Same or more power extracted with the SMFE technique

For high ξe :

Less power extracted with the SMFE technique

Worse case : 10% less

MIC

A 2

(Ber

kele

y)

Best case : 2.5 more power

Only 3 parameters are required to describe the behaviour of an

electromagnetic generator

My Mu Cu Ku I

0LV u r I L I

2m

C

KM

22

0

kKL

0 02L

e

r

L

0 02c

R

L