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Implementation and Validation of a Two-Stage Energy Extraction Circuit for a Self Sustained Asset-Tracking System^{ †}

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## Abstract

**:**

## 1. Introduction

## 2. Concept of the Self-Sustained Asset-Tracking System

## 3. Design and Manufacturing Process of the Cantilever-Based Piezoelectric Energy Harvester

## 4. Characterization of the Excitation and the Piezoelectric Energy Harvester

## 5. The Two-Stage Energy Extraction Network

#### 5.1. Loss-Consideration of the HV-DC/DC

#### 5.2. Performance of the Proposed Network Excited with a Vibration Test System

#### 5.3. In Situ Evaluation for the Desired Usecase

## 6. Conclusions and Discussion

## Author Contributions

## Funding

## Acknowledgments

## Conflicts of Interest

## Abbreviations

PEH | Piezoelectric Energy Harvester |

RFID | Radio Frequency Identification |

VTS | Vibration Test System |

MPP | Maximum Power Point |

$\mathsf{\mu}$C | Micro Controller |

TX | Radio Transmitter |

OOK | On Off Keying |

BPSK | Binary Phase Shift Keying |

acc | Acceleration |

RMS | Root Mean Square value |

SSHI | Synchronized Switching Harvesting with Inductor |

SECE | Synchronized Electric Charge Exctraction |

OC | Open-Circuit |

Diff | Differentiator |

LV-DC/DC | Low Voltage—Distinct Current/Distinct Current Converter |

HV-DC/DC | High Voltage—Distinct Current/Distinct Current Converter |

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**Figure 1.**(

**Left**): Function principle of the autarchic asset tracking system. (

**Right**): Piezoelectric energy harvester and the two-stage energy extraction network are included in the object-to-be-tracked, which is placed on a pushcart.

**Figure 2.**(

**Top left**): Geometric dimensions of the piezoelectric energy harvester. (

**Top right**): Measurement setup of acceleration measurement. (

**Mid**): Measured transient acceleration ${a}_{z}\left(t\right)$ of a pushcart driven on different undergrounds. (

**Bottom**): Power spectrum ${\underline{a}}_{z}^{2}\left(f\right)/\left(2\pi f\right)$ of the measured transient accelerations.

**Figure 3.**(

**Top**): Measurement setup of the open-circuit voltage measurements. (

**Bottom**): Transient absolut value of the open-circuit voltages $|{\widehat{V}}_{\mathrm{PEH},\mathrm{OC}}|$ from the PEH for driving with the pushcart on different floortypes.

**Figure 4.**(

**Top**): Measurement setup for the power output of the PEH for sinusoidal excitation with a vibration test system. (

**Right**): Power output with respect to a directly connected load resistance ${R}_{\mathrm{L}}$. (

**Left**): Power output with respect to the frequency dependent open-circuit voltage ${V}_{\mathrm{PEH}}(f,{R}_{L}\to \infty )$. The arrow indicates the possible merit of the two-stage approach by providing better electrical load conditions to the PEH.

**Figure 5.**Schematic of the two-stage energy extraction network. (

**First row**): Power section with parallel SSHI unit, High Voltage DC/DC (HV-DC/DC) converter in flyback-topology, and Low Voltage DC/DC (LV-DC/DC) in buck-topology. (

**Second row**): Control-circuit section with SSHI Control, HV-DC/DC Control, and LV-DC/DC Control. Parts of the circuit can be disabled and enabled, which results in different energy extraction networks, refer to Table 1 for an explanation of the different network modes.

**Figure 6.**Comparison of the transmission rates for SSHI-, one-stage and two-stage energy extraction networks. (

**Left**): sinusoidal-excitation (

**Right**): noise-excitation; measured for different acceleration values, which correspond to different open-circuit voltages ${\widehat{V}}_{\mathrm{PEH},\mathrm{OC}}$. The results are obtained from the measurement setup in Figure 4, where the resistor network is supplemented with the proposed energy extraction network in Figure 5. To adjust the regulated value of ${V}_{\mathrm{C}1}$, the voltage devider ${R}_{2}/({R}_{1}+{R}_{2})$ is varied in order to evaluate the performance for different ${\widehat{V}}_{\mathrm{PEH},\mathrm{OC}}/{V}_{\mathrm{C}1}$.

Approach Name | SSHI + Control | HV-DC/DC + Control | LV-DC/DC + Control | Max. Transm./s ${\widehat{\mathit{V}}}_{\mathbf{PEH},\mathbf{OC}}=$ $60\phantom{\rule{0.166667em}{0ex}}\mathbf{V};\phantom{\rule{0.166667em}{0ex}}40\phantom{\rule{0.166667em}{0ex}}\mathbf{V};\phantom{\rule{0.166667em}{0ex}}25\phantom{\rule{0.166667em}{0ex}}\mathbf{V}$ Sinusoidal | Max. Transm./s ${\widehat{\mathit{V}}}_{\mathbf{PEH},\mathbf{OC}}=40\phantom{\rule{0.166667em}{0ex}}\mathbf{V}$ Noise with VTS | Median Transm./s ${\widehat{\mathit{V}}}_{\mathbf{PEH},\mathbf{OC}}\approx 90\phantom{\rule{0.166667em}{0ex}}\mathbf{V}$ In Situ: Asphalt |
---|---|---|---|---|---|---|

SSHI | enabled | disabled | enabled | 4; 2; 1 | 0.38 | - |

One-stage | disabled | disabled | enabled | 4; 2; 1 | 0.82 | 0.85 |

Two-stage | disabled | enabled | enabled | 6; 2.6; 0.8 | 1 | 1.65 |

**Table 2.**Losses of the HV-DC/DC depicted in Figure 5 for ${\overline{V}}_{\mathrm{C}1}=30\phantom{\rule{0.166667em}{0ex}}\mathrm{V}$, ${V}_{\mathrm{L}2}=6.2\phantom{\rule{0.166667em}{0ex}}\mathrm{V}$, ${V}_{\mathrm{D}2}=0.8\phantom{\rule{0.166667em}{0ex}}\mathrm{V}$, MOSFET BSS123 with ${R}_{\mathrm{DSon}}=6\phantom{\rule{0.166667em}{0ex}}\mathsf{\Omega}$.

Core | RM5 | ER11 with Airgap | ER11 without Airgap |
---|---|---|---|

Comparator | LTC1540 | TS881 | TS881 |

Volume | $1360\phantom{\rule{0.166667em}{0ex}}\mathrm{m}{\mathrm{m}}^{3}$ | $318\phantom{\rule{0.166667em}{0ex}}\mathrm{m}{\mathrm{m}}^{3}$ | $318\phantom{\rule{0.166667em}{0ex}}\mathrm{m}{\mathrm{m}}^{3}$ |

${t}_{\mathrm{on}}$ | $150\phantom{\rule{0.166667em}{0ex}}\mathsf{\mu}\mathrm{s}$ | $13.3\phantom{\rule{0.166667em}{0ex}}\mathsf{\mu}\mathrm{s}$ | $13.3\phantom{\rule{0.166667em}{0ex}}\mathsf{\mu}\mathrm{s}$ |

${t}_{\mathrm{Miller}}$ | $400\phantom{\rule{0.166667em}{0ex}}\mathrm{n}\mathrm{s}$ | $83\phantom{\rule{0.166667em}{0ex}}\mathrm{n}\mathrm{s}$ | $83\phantom{\rule{0.166667em}{0ex}}\mathrm{n}\mathrm{s}$ |

${L}_{1}$ | $315\phantom{\rule{0.166667em}{0ex}}\mathrm{m}\mathrm{H}$ | $5.35\phantom{\rule{0.166667em}{0ex}}\mathrm{m}\mathrm{H}$ | $46.1\phantom{\rule{0.166667em}{0ex}}\mathrm{m}\mathrm{H}$ |

${L}_{2}$ | $75\phantom{\rule{0.166667em}{0ex}}\mathrm{m}\mathrm{H}$ | $1.28\phantom{\rule{0.166667em}{0ex}}\mathrm{m}\mathrm{H}$ | $11.6\phantom{\rule{0.166667em}{0ex}}\mathrm{m}\mathrm{H}$ |

${R}_{\mathrm{L}1}$ | $5.1\phantom{\rule{0.166667em}{0ex}}\mathsf{\Omega}$ | $10.0\phantom{\rule{0.166667em}{0ex}}\mathsf{\Omega}$ | $9.9\phantom{\rule{0.166667em}{0ex}}\mathsf{\Omega}$ |

${R}_{\mathrm{L}2}$ | $3.15\phantom{\rule{0.166667em}{0ex}}\mathsf{\Omega}$ | $3.77\phantom{\rule{0.166667em}{0ex}}\mathsf{\Omega}$ | $3.77\phantom{\rule{0.166667em}{0ex}}\mathsf{\Omega}$ |

Results | |||

${E}_{\mathrm{in}}/\mathrm{Period}$ | $32.1\phantom{\rule{0.166667em}{0ex}}\mathsf{\mu}\mathrm{J}$ | $14.9\phantom{\rule{0.166667em}{0ex}}\mathsf{\mu}\mathrm{J}$ | $1.7\phantom{\rule{0.166667em}{0ex}}\mathsf{\mu}\mathrm{J}$ |

${E}_{\mathrm{Rdson}}$ | $133\phantom{\rule{0.166667em}{0ex}}\mathrm{n}\mathrm{J}$ | $133\phantom{\rule{0.166667em}{0ex}}\mathrm{n}\mathrm{J}$ | $1.8\phantom{\rule{0.166667em}{0ex}}\mathrm{n}\mathrm{J}$ |

${E}_{\mathrm{L}1}$ | $46.9\phantom{\rule{0.166667em}{0ex}}\mathrm{n}\mathrm{J}$ | $220\phantom{\rule{0.166667em}{0ex}}\mathrm{n}\mathrm{J}$ | $3.0\phantom{\rule{0.166667em}{0ex}}\mathrm{n}\mathrm{J}$ |

${E}_{\mathrm{L}2}$ | $225\phantom{\rule{0.166667em}{0ex}}\mathrm{n}\mathrm{J}$ | $670\phantom{\rule{0.166667em}{0ex}}\mathrm{n}\mathrm{J}$ | $8.7\phantom{\rule{0.166667em}{0ex}}\mathrm{n}\mathrm{J}$ |

${E}_{\mathrm{D}2}$ | $3297\phantom{\rule{0.166667em}{0ex}}\mathrm{n}\mathrm{J}$ | $1526\phantom{\rule{0.166667em}{0ex}}\mathrm{n}\mathrm{J}$ | $177\phantom{\rule{0.166667em}{0ex}}\mathrm{n}\mathrm{J}$ |

${E}_{\mathrm{swOff}}$ | $51\phantom{\rule{0.166667em}{0ex}}\mathrm{n}\mathrm{J}$ | $56\phantom{\rule{0.166667em}{0ex}}\mathrm{n}\mathrm{J}$ | $6.5\phantom{\rule{0.166667em}{0ex}}\mathrm{n}\mathrm{J}$ |

Efficiency | $89\%$ | $81\%$ | $89\%$ |

**Table 3.**Statistic results of the in situ measurement on asphalt displayed in Figure 7.

One-Stage | Two-Stage | |||||||||
---|---|---|---|---|---|---|---|---|---|---|

${\overline{V}}_{\mathrm{C}1}/\mathrm{V}$ | $6.7$ | $6.8$ | $8.8$ | $14.1$ | $22.2$ | $29.5$ | $35.7$ | $41.3$ | $48.2$ | $56.2$ |

$\mathrm{Transmissions}/\mathrm{s}$ | ||||||||||

Maximum | 1.44 | 1.24 | 1.63 | 2.49 | 3.94 | 5.27 | 7.48 | 6.17 | 7.05 | 10.2 |

75th Percentile | 1.00 | 0.87 | 0.97 | 1.37 | 2.05 | 2.31 | 2.22 | 2.64 | 2.37 | 1.91 |

Median | 0.85 | 0.73 | 0.81 | 1.17 | 1.59 | 1.51 | 1.65 | 1.51 | 1.23 | 1.07 |

25th Percentile | 0.70 | 0.65 | 0.70 | 1.03 | 1.21 | 1.17 | 1.26 | 1.29 | 0.84 | 0.65 |

Minimum | 0.55 | 0.51 | 0.53 | 0.67 | 0.74 | 0.29 | 0.57 | 0.36 | 0.30 | 0.22 |

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## Share and Cite

**MDPI and ACS Style**

Dorsch, P.; Bartsch, T.; Hubert, F.; Milosiu, H.; Rupitsch, S.J. Implementation and Validation of a Two-Stage Energy Extraction Circuit for a Self Sustained Asset-Tracking System. *Sensors* **2019**, *19*, 1330.
https://doi.org/10.3390/s19061330

**AMA Style**

Dorsch P, Bartsch T, Hubert F, Milosiu H, Rupitsch SJ. Implementation and Validation of a Two-Stage Energy Extraction Circuit for a Self Sustained Asset-Tracking System. *Sensors*. 2019; 19(6):1330.
https://doi.org/10.3390/s19061330

**Chicago/Turabian Style**

Dorsch, Philipp, Toni Bartsch, Florian Hubert, Heinrich Milosiu, and Stefan J. Rupitsch. 2019. "Implementation and Validation of a Two-Stage Energy Extraction Circuit for a Self Sustained Asset-Tracking System" *Sensors* 19, no. 6: 1330.
https://doi.org/10.3390/s19061330