HYBRID ENERGY HARVESTING UNIT AND USE THEREOF

Abstract

Aspects of the present disclosure are directed to hybrid energy harvesting systems and methods related thereto. In one example embodiment of the present disclosure, a hybrid energy harvesting unit is disclosed including a guiding structure that provides a constrained trajectory, and one or more coils with a coil length arranged along the guiding structure. Each of the one or more coils encircle a part of the constrained trajectory. The hybrid energy harvesting unit further includes a cantilever structure with an anchoring end and a cantilever tip having a magnetic mass arranged thereon, a piezoelectric element arranged in the cantilever structure and outside the one or more coils, and a permanent magnet partially arranged in the guiding structure and which moves relative to the guiding structure. The anchoring end and the guiding structure is attached to and separated by a distance to the object in motion at a point of contact.

Claims

1. Hybrid energy harvesting unit configured to harvest energy from an object, the hybrid energy harvesting unit comprising: a guiding structure configured and arranged to provide a constrained trajectory, one or more coils with a coil length arranged along the guiding structure, each of the one or more coils encircling a part of the constrained trajectory, a cantilever structure with an anchoring end and a cantilever tip having a magnetic mass arranged thereon, a piezoelectric element arranged in the cantilever structure and outside the one or more coils, and a permanent magnet with a length arranged in the guiding structure and configured and arranged to move relative to the guiding structure, wherein the anchoring end and the guiding structure are configured and arranged to be attached to and separated by a distance to the object in motion at a point of contact, and within which distance the permanent magnet, when moved relative to a part of the guiding structure, interacts with the magnetic mass to deform the piezoelectric element.

2. The hybrid energy harvesting unit of claim 1, wherein the one or more coils are arranged along the guiding structure, and the one or more coils have coil lengths of the permanent magnet which are equal to the permanent magnet length.

3. The hybrid energy harvesting unit of claim 1, wherein the permanent magnet is configured and arranged with a magnetic field greater or equal to the magnetic field of the magnetic masse the permanent magnet interacts with.

4. The hybrid energy harvesting unit of claim 1, where the permanent magnet and/or the guiding structure includes a friction reducing suspension for the moveable permanent magnet.

5. The hybrid energy harvesting unit of claim 1, wherein the cantilever structure includes a substrate layer, a bottom electrode layer, a piezoelectric layer, and a top electrode layer, the layers being arranged in a sandwich structure reaching from the anchoring end to the cantilever tip and with the piezoelectric layer arranged between the top electrode layer and the bottom electrode layer.

6. The hybrid energy harvesting unit of claim 1, further including multiple piezoelectric elements in an array, with the anchoring end of each piezoelectric element configured and arranged to be attached to the object at a distance within which distance the permanent magnet, when moved relative to a part of the guiding structure, interacts with the magnetic mass to deform the piezoelectric element.

7. The hybrid energy harvesting unit of claim 1, wherein the guiding structure includes a first closed end, a second closed end and a stopper permanent magnet in one or both closed ends.

8. The hybrid energy harvesting unit of claim 7, further including a stopper permanent magnet a suspension arrangement in either the first or second closed end, the suspension arrangement including a fixed coil and a deformable suspension having a compressed length and an elongated length adapted to be arranged with an end of the deformable suspension fixed to the guiding structure and another end of the deformable suspension fixed to the object, and with the fixed coil fixed to the object in one end and encircling the stopper permanent magnet or a part of the permanent magnet at a length of the deformable suspension within a range between the compressed length and the elongated length.

9. The hybrid energy harvesting unit of claim 1, further including an interconnecting circuit and a rectifier circuit.

10. The hybrid energy harvesting unit of claim 1, further including a power management circuit and rechargeable energy storage.

11. Method for harvesting energy from an object in motion including the steps: displacing a permanent magnet through one or more coils along a guiding structure, and arranging a piezoelectric element including a cantilever structure, an anchoring end and a cantilever tip, the cantilever tip having a magnetic mass with a distance to the guiding structure (20), within the distance the permanent magnet, when moved relative to at least a part of the guiding structure, interacts with the magnetic mass to deform the piezoelectric element.

12. The method according to claim 11, wherein the permanent magnet is configured and arranged to be displaced along the guiding structure with a distance to the magnetic mass, and where the interacting magnetic forces between the permanent magnet and the magnetic mass are lower than a spring force of the cantilever structure.

13. The method of claim 11, wherein the deformation of the piezoelectric element is equal to or above the displacement causing the piezoelectric element to be operated in its resonance frequency.

14. The method of claim 11 wherein the motion of the object is a rotational motion, and wherein the permanent magnet and the guiding structure is configured and arranged such that the permanent magnet is moved by the Earths gravitational force at least once per rotation.

15. A system for harvesting energy comprising: a rotational movable part; a hybrid energy harvesting unit attached to the rotational movable part, the hybrid energy harvesting unit including a guiding structure configured and arranged to provide a constrained trajectory, one or more coils with a coil length arranged along the guiding structure, each of the one or more coils encircling a part of the constrained trajectory, a cantilever structure with an anchoring end and a cantilever tip having a magnetic mass arranged thereon, a piezoelectric element arranged in the cantilever structure and outside the one or more coils, and a permanent magnet with a length arranged in the guiding structure and configured and arranged to move relative to the guiding structure, wherein the anchoring end and the guiding structure are configured and arranged to be attached to and separated by a distance to an object in motion at a point of contact, and within which distance the permanent magnet, when moved relative to a part of the guiding structure, interacts with the magnetic mass to deform the piezoelectric element.

16. The system of claim 15, wherein the rotational moveable part includes a wind turbine.

17. The system of claim 15, wherein the hybrid energy harvesting unit is embedded in a power consuming unit.

18. The hybrid energy harvesting unit of claim 1, wherein the guiding structure has a length enabling the permanent magnet to reach a speed high enough to excite the cantilever, before the permanent magnet reach the cantilever.

Description

DESCRIPTION OF THE DRAWING

[0124] Embodiments of the invention will be described in the figures, whereon:

[0125] FIG. 1 illustrates one embodiment of the elements of the hybrid energy harvesting unit.

[0126] FIG. 2 illustrates one embodiment of the arrangement of the elements of the hybrid energy harvesting unit.

[0127] FIG. 3 illustrates one embodiment of the hybrid energy harvesting unit with an array of piezoelectric elements.

[0128] FIG. 4 illustrates two embodiments of the hybrid energy harvesting unit with a circular guiding structure.

[0129] FIG. 5 illustrates two embodiments of the hybrid energy harvesting unit.

[0130] FIG. 6 illustrates one embodiment of the hybrid energy harvesting unit in operation.

[0131] FIG. 7 illustrates another embodiment of the hybrid energy harvesting unit in operation.

[0132] FIG. 8 illustrates an embodiment of the hybrid energy harvesting unit with suspension arrangements.

[0133] FIG. 9 illustrates the use of the hybrid energy harvesting unit with a power consuming unit.

[0134] FIG. 10 illustrates the use of the hybrid energy harvesting unit attached to a wind turbine blade.

[0135] FIG. 11 illustrates an embodiment of the hybrid energy harvester unit and operation hereof used in COMSOL simulations.

[0136] FIG. 11C illustrates results of COMSOL simulations.

[0137] FIG. 12 illustrates results of COMSOL simulations.

DETAILED DESCRIPTION OF THE INVENTION

[0138]

TABLE-US-00001 Item No.  1 Hybrid energy harvesting unit  2 Object  4 Point of contact  10 Coil  11 Coil length  12 Fixed coil  20 Guiding structure  22 Circular structure  24 Linear structure  24A First closed end  24B Second closed end  30 Constrained trajectory  32 Circular trajectory  34 Linear trajectory  40 Piezoelectric element  42 Cantilever structure  44 Anchoring end  46 Cantilever tip  48 Magnetic mass  49 Array of piezoelectric elements  50 Permanent magnet  51 Permanent magnet length  52 Friction reducing suspension  60 Tube  70 Distance  80 Suspension arrangement  82 Deformable suspension  84 Stopper permanent magnet  86 Compressed length  88 Elongated length  90 Rectifier circuit  91 Interconnecting circuit  92 Power management circuit  94 Rechargeable energy storage 100 Use 110 Wind turbine 112 Rotational moveable part of a wind turbine 114 Power consuming unit 141 Top electrode layer 142 Bottom electrode layer 143 Piezoelectric layer 144 Substrate layer

[0139] FIG. 1 illustrates one embodiment of the elements of the hybrid energy harvesting unit. FIG. 1a illustrates a guiding structure 20 being a linear structure 24 providing a constrained trajectory 30 being a linear trajectory 34. Multiple coils 10 with a coil length 11 is arranged along the guiding structure 20. The three dots along the trajectory line indicate that additional coils 10 may be comprised. Each coil 10 encircles a part of the provided constrained trajectory 30.

[0140] In this embodiment, the guiding structure is a tube 60 with the coils being arranged on the exterior face of the tube 60.

[0141] A permanent magnet 50 with a permanent magnet length 51 is arranged in the guiding structure 20 and is adapted to move relative to the guiding structure 20 along the provided trajectory 30. A friction reducing suspension 52 for the moveable permanent magnet 50 is comprised in the permanent magnet 50 and/or in the guiding structure 30.

[0142] FIG. 1b illustrates a piezoelectric element 40 arranged in a cantilever structure 42. The piezoelectric element 40 has an anchoring end 44 and a cantilever tip 46 and comprises a magnetic mass 48 arranged at the cantilever tip 46, here arranged on top of the cantilever structure 42. The insert illustrates an embodiment of the cantilever structure (42) with a substrate layer (144), a bottom electrode layer (142), a piezoelectric layer (143), and a top electrode layer (141). The layers are arranged in a sandwich structure reaching from the anchoring end 44 to the cantilever tip 46.

[0143] FIG. 2 illustrates one embodiment of the arrangement of the elements of the hybrid energy harvesting unit. The elements illustrated in this figure are the same elements as illustrated in FIG. 1. The hybrid energy harvesting unit is here illustrated as being attached to an object at a point of contact 4. The anchoring end 44 and the guiding structure 20 are fixed relative to the point of contact. Furthermore, the anchoring end 44 and the guiding structure 20 are arranged with a distance 70 between them. This distance should be chosen such that within this distance 70 the permanent magnet 50, when moved relative to a part of the guiding structure 20, interacts with the magnetic mass 48 to deform the piezoelectric element 40.

[0144] The deformation of the piezoelectric element 40 may be caused by the permanent magnet 50 passing the magnetic mass 48 when moving along the confined trajectory 30. The deformation may be due to magnetic interaction and when the permanent magnet 50 increases its distance to the magnetic mass 48, the piezoelectric element 40, due to its cantilever structure, will begin to oscillate as indicated by the arched arrow. The hybrid energy harvesting unit 1 harvests energy when the piezoelectric element 40 deforms and when the permanent magnet 50 passes through the coils 10.

[0145] FIG. 3 illustrates one embodiment of the hybrid energy harvesting unit 1 with an array 49 of piezoelectric elements 40. The elements illustrated in this figure are the same elements as illustrated in FIG. 1, but with multiple piezoelectric elements 40.

[0146] The operation is similar to that described for the embodiment in FIG. 2. The anchoring ends 44 and the guiding structure 20 are arranged with a distance between them. This distance should be chosen such that the permanent magnet 50, when moved relative to a part of the guiding structure 20, interacts with the magnetic masses 48 to deform the piezoelectric element 40.

[0147] Deformation of the piezoelectric elements 40 may be caused by the permanent magnet 50 passing the magnetic mass 48 when moving along the confined trajectory 30. The deformation may be due to magnetic interaction and when the permanent magnet 50 increases its distance to the magnetic mass 48, each of the piezoelectric elements 40, due to their cantilever structure, will begin to oscillate as indicated by the arrows. The hybrid energy harvesting unit 1 harvests energy, when each of the piezoelectric elements 40 deforms and when the permanent magnet 50 passes through the coils 10.

[0148] FIG. 4 illustrates two embodiments of the hybrid energy harvesting unit 1 with a circular guiding structure 22. FIG. 4a illustrates an elongated circular guiding structure 20 comprised of a tube 60 providing a confined circular trajectory 30, 32. In the illustrated embodiment two piezoelectric elements 40 are arranged, one on either side of the guiding structure 20. When the permanent magnet 50 moves along the trajectory 30, it is moved through the coils 10 and past the piezoelectric elements 40.

[0149] FIG. 4b illustrates a circular guiding structure 20 comprised of a tube 60 providing a confined circular trajectory. In the illustrated embodiment one piezoelectric element 40 is arranged on the outer side of the guiding structure 20. When the permanent magnet 50 moves along the trajectory, it is moved through the coils and passes the piezoelectric element 40.

[0150] Hence, the operation as such of the two embodiments in FIG. 4 is similar to that described for the embodiments in FIG. 2 and FIG. 3. However, the hybrid energy harvesting unit 1 with a circular guiding structure 22 providing a trajectory without endpoints may be especially useful for rotational moving objects and for operation with the centre point of rotation arranged in the centre of the circular guiding structure, illustrated with an ‘x’ in FIGS. 4a and 4b. In such cases, the permanent magnet 50, as illustrated in FIG. 4b, will be held in an almost static position at the lowest point of the guiding structure due to the gravitational force acting hereon. The guiding structure 20 and the piezoelectric elements 40 will be rotated with the object to which they are attached, as indicated in FIG. 4b by the arrows.

[0151] As the magnetic mass of the piezoelectric elements 40 passes the permanent magnet, a deformation due to magnetic interaction and the cantilever structure may occur with a subsequent oscillation of the piezoelectric element 40, as indicated by the arrows. The hybrid energy harvesting unit 1 harvests energy, when each of the piezoelectric elements 40 deforms and when the coils pass the permanent magnet 50.

[0152] FIG. 5 illustrates two embodiments of the hybrid energy harvesting unit 1. FIGS. 5a and 5b illustrate a half-circular guiding structure 20,22 formed as a tube 60. Here, the confined trajectory for the permanent magnet 50 has two endpoints similar to the linear trajectory illustrated in the embodiments in FIG. 5c.

[0153] This hybrid energy harvesting unit 1 may be usefully operated attached to rotational moving objects and for operation with the centre point of rotation arranged in the centre of the circular guiding structure, illustrated with an ‘x’. In this case of operation, the closed end of the guiding structure will, as illustrated in the shift in position from FIG. 5a to FIG. 5b, move the permanent magnet 50 in a circular motion until the trajectory and the gravitational force is aligned such that the permanent magnet may fall along the trajectory to the other end of the guiding structure or, alternatively, to the lowest part of the guiding structure. There, in the lowest part of the guiding structure, the permanent magnet may be held in a static position while the guiding structure, the coils, and the piezoelectric element 40 pass until the closed end of the guiding structure reaches the permanent magnet 50 and again move the permanent magnet 50 in a circular motion.

[0154] An alternative operation of a half-circular guiding structure could be advantageous in regard to an object which has a rocking motion which may include tilting, rolling or similar movements. Operated as such, the guiding structure may be operated in a position opposite to that illustrated in FIG. 5b such that the permanent magnet 50 will be held in an almost static position at the lowest point of the guiding structure due to the gravitational force acting hereon. The position of the guiding structure 20 and the piezoelectric elements 40 will be shifted in a rocking motion rotated with the object to which they are attached such that the coils and piezoelectric element 40 will repeatedly pass the permanent magnet 50.

[0155] FIG. 5c illustrates an embodiment of a hybrid energy harvesting unit with a linear guiding structure 20 similar to the embodiment illustrated in FIG. 2. The hybrid energy harvesting unit 1 is here illustrated as being attached to an object at a point of contact 4. The anchoring end 44 and the guiding structure 20 are fixed relative to the point of contact. Furthermore, the anchoring end 44 and the guiding structure 20 are arranged with a distance 70 between them. This distance should be chosen such that, within this distance 70, the permanent magnet 50, when moved relative to a part of the guiding structure 20, interacts with the magnetic mass 48 to deform the piezoelectric element 40.

[0156] FIG. 6 illustrates one way of operating the hybrid energy harvesting unit 1 illustrated in FIG. 5c. The figures on the left hand side illustrate the interaction between the permanent magnet 50 and the piezoelectric element 40 as the position of the hybrid energy harvesting unit 1 is changed due to a rotational motion with a rotational centre ‘x’ as indicated in FIG. 5c. On the right hand side, the forces acting on the permanent magnet are illustrated by F_CF and F_G being the vector representation. When the gravitational force F_G exceeds the Y-component of the centrifugal forces F_CF the permanent magnet 50 begins to move along the confined trajectory to the lowest part of the guiding structure, here a closed end of the guiding structure. In this case any frictional resistance or other sources of interacting forces are neglected.

[0157] The permanent magnet 50 and the magnetic mass 48 of the piezoelectric element 40 in the illustrated embodiment are oppositely poled to attract each other. Hence, the piezoelectric element 40 is deformed towards the permanent magnet 50 as it passes, and when the distance increases and the magnetic interaction decreases below that of the ‘spring force’ of the piezoelectric element 40, the piezoelectric element 40 begins to oscillate.

[0158] FIG. 7 illustrates one way of operating the hybrid energy harvesting unit 1 illustrated in FIG. 4b as also illustrated in FIG. 7a. FIGS. 7b and 7c illustrate how the distance 70 between the anchoring end 44 of the piezoelectric element 40 and the permanent magnet 50 changes as the hybrid energy harvesting unit 1 is rotated with the object, to which it is attached, around the rotational centre indicated by the ‘x’ in FIGS. 7a and 7b. The dotted box in FIG. 7b illustrates the rotation of the hybrid energy harvesting unit 1 of FIG. 7a. The illustrated operation results in a trajectory of the permanent magnet 50 relative to the piezoelectric elements anchoring which may be perceived as a confined trajectory 32.

[0159] FIG. 8 illustrates an embodiment of the hybrid energy harvesting unit 1 with suspension arrangements 80. The hybrid energy harvesting unit 1 comprises a linear guiding structure 20 comprising a permanent magnet 50 and friction reducing suspension 52. The guiding structure comprises a first closed end 24A and a second closed end 24B. Furthermore, a stopper permanent magnet 84 is arranged in connection with either of the closed ends 24A, 24B.

[0160] The embodiment comprises a suspension arrangement 80 in either of the closed ends 24A, 24B. The suspension arrangements 80 each comprises a fixed coil 12 and a deformable suspension 82 having a compressed length 86 and an elongated length 88, as illustrated in the insert lower left corner of FIG. 8. The suspension arrangement 80 is arranged with one end of the deformable suspension 82 and one end of the fixed coil 12 fixed to the object 2 (illustrated with ‘ground’), and with the fixed coil 12 encircling the stopper permanent magnet 84 or a part hereof.

[0161] If the guiding structure is set in motion, it will oscillate between the fastening points, and the stopper permanent magnet 84 will move back and forth through the fixed coil 12.

[0162] In this embodiment the deformable suspension is illustrated as a spring.

[0163] FIG. 9 illustrates the use 100 of the hybrid energy harvesting unit with an array 49 of piezoelectric elements 40 with a power consuming unit 114. The elements of the hybrid energy harvesting unit, including the array 49 of piezoelectric elements 40, the coils 10, and possible the suspension arrangement 80, are connected to an interconnecting circuit 91 and a rectifier circuit 90. A power management circuit 92 distributes the electric power between the power consuming unit 114 and rechargeable energy storage 94.

[0164] FIG. 10 illustrates the use 100 of the hybrid energy harvesting unit 1 attached to an object in motion at a point of contact 4. Here, the object is a wind turbine blade being a rotationally moveable part (112) comprised in a wind turbine (110). The centre of rotation of the wind turbine and the attached hybrid energy harvesting unit 1 are illustrated by the ‘x’.

[0165] The hybrid energy harvesting unit 1 can be located inside or outside on the blade or built into the structure of the blade.

[0166] The illustrated wind turbine 110, including the rotor and the blade, is for illustrative purposes and is in a simple schematic outline. The dimension of the wind turbine 110 and the hybrid energy harvesting unit 1 is illustrated in non-comparable dimensions.

[0167] The hybrid energy harvesting unit 1 comprises a piezoelectric element and a linear guiding structure with a constrained linear trajectory 34. The permanent magnet in the guiding structure moves along the linear trajectory 34.

[0168] When the blade rotates both the gravitational force, f_G, and the centrifugal force, f_CF, act on the permanent magnet. The forces are illustrated by F_CF and F_G being the vector representation. When the gravitational force, F_G, exceeds the Y-component of the centrifugal forces, F_CF, the permanent magnet begins to move along the confined trajectory to the lowest part of the guiding structure, here a closed end of the guiding structure.

[0169] In this case, for illustrative purposes, any frictional resistance or other sources of interacting forces are neglected, just as the opposing force of the wall of the guiding structure is not illustrated.

[0170] A particular embodiment of the hybrid energy harvester unit 1 and simulations hereof is illustrated in FIGS. 11 and 12. The simulations are performed using COMSOL Multiphysics® Version 5.4.

[0171] FIG. 11A illustrates the hybrid energy harvesting unit 1 and FIG. 11 B illustrates the simulated operation of the hybrid energy harvesting unit of FIG. 11A.

[0172] The simulated hybrid energy harvesting unit 1 illustrated in FIG. 11A comprises a guiding structure 20 being a linear structure providing a constrained trajectory 30 being a linear trajectory. A coil 10 with a number of windings is arranged along the guiding structure 20. The coil 10 encircles a part of the provided constrained trajectory 30.

[0173] In this embodiment, the guiding structure 20 is a tube with the coil 10 being arranged on the exterior face of the tube.

[0174] The simulated hybrid energy harvesting unit 1 furthermore comprises a permanent magnet 50 arranged in the guiding structure 20 and is adapted to move relative to the guiding structure 20 along the provided trajectory 30.

[0175] The simulated hybrid energy harvesting unit 1 furthermore comprises a piezoelectric element 40 arranged in a cantilever structure. The piezoelectric element 40 has an anchoring end and a cantilever tip and comprises a magnetic mass 48 arranged at the cantilever tip. The cantilever structure comprises a substrate layer, a bottom electrode layer, a piezoelectric layer, and a top electrode layer. The layers are arranged in a layered sandwich structure reaching from the anchoring end to the cantilever tip.

[0176] The simulations of the hybrid energy harvesting unit 1 are performed for the hybrid energy harvesting unit 1 arranged attached to an object in motion at a point of contact.

[0177] The motion of the object is a rotational motion around a centre marked in FIG. 11B with an x. The hybrid energy harvesting unit 1 is arranged with the linear constrained trajectory 30 arranged tangential to the rotational circumference of the hybrid energy harvesting unit 1 and with the plane of the constrained trajectory being that of the gravitational force F_G. Hence, the simulation is performed with in the Earths gravitation force.

[0178] In the simulated embodiment the hybrid energy harvesting unit 1 comprises an EMHE and PEHE element with the following parameters:

[0179] EMHE

[0180] Permanent magnet, Size (L×W×H)=1 cm×1 cm×1 cm [0181] Material=NdFeB [0182] Magnetization=1.3 T

[0183] Constrained trajectory Linear, length 20 cm

[0184] Coil, windings, no=100 [0185] Load resistance 100 mOhm (milli-Ohm) [0186] Material=Copper

[0187] PEHE

[0188] Substrate layer Size (L×W×H)=40 mm×10 mm+0. 35 mm [0189] Material=Silicon

[0190] Piezoelectric layer Size (H)=2 micro meter [0191] Material=Aluminum nitride

[0192] Magnetic mass Size (L×W×H)=0.5 cm×1 cm×0.5 cm [0193] Material=NdFeB

[0194] Load resistance 90 kOhm (Kilo-Ohm)

[0195] FIG. 11C illustrates simulated forces, F_E between the magnets and displacement of the piezoelectric cantilever, ΔD. The simulated force, F_E and the displacement, ΔD are shown as Force, F versus Time, T and distance, D versus Time, T.

[0196] FIG. 12A illustrates the simulated energy and power output for the piezoelectric harvesting element (PEHE) for one oscillation cycle of the piezoelectric harvesting element (PEHE). The simulated energy output E_PEHE and the power output P_PEHE are shown as Energy, E versus Time, T and Power, P versus Time, T.

[0197] FIG. 12B illustrates the simulated energy and power output for the electromagnetic harvesting element (EMHE) for fall of the magnet through the coil along the constrained trajectory. The simulated energy output E_EMHE and the power output P_EMHE are shown as Energy, E versus Time, T and Power, P versus Time, T.

[0198] For the simulated embodiment, the simulated energy output per fall of the permanent magnet is for the EMHE, E_EMHE=8441 micro Joule (uJ) and for the PEHE,

[0199] E_PEHE 621 micro Joule (uJ). The simulated power output at a rotational speed of 20 rpm is for the EMHE, P_EMHE=5627 micro Watt (uW) and for the PEHE, P_PEHE=414 micro Watt (uW).