*A Guide to Small-Scale Energy Harvesting Techniques*

**45**

*Energy Harvester Based on Magnetomechanical Effect as a Power Source for Multi-node Wireless…*

Miniature — ϕ50 × 35 200 2000 Low power (A, D) ϕ50 × 50 300 5000 High power (Β) ϕ50 × 150 1000 10,000 "Tactical grade" (C) ϕ80 × 250 1500 10,000

**Dimensions [mm] Mass [g] Power in the** 

**impulse [mW]**

demagnetizing magnets, in which neodymium magnets subjected to strong mechanical stimulation, sometimes to its destruction, are used as the core. They differ in the amount of Terfenol-D used in the magnetic circuit and provide the possibility of screwing into the structure. The view of made harvesters is shown in **Figure 9** (**Table 1**).

*An overview of the prototypes of harvesters together with the most important parameters.*

**4. Harvesters based on mechanical impact and electronic converters for** 

Generators of special characteristics are the explosive-driven ferromagnetic generators (EDFMG) producing an electromagnetic wave that arises as a result of immediate demagnetization of the magnet by a stroke following an explosion or other strong force impulse. The magnet then loses its magnetic properties but generates a strong pulsed magnetic field around it. During the impact it is possible to even destroy the magnet, but the amount of energy that will be induced in the coil is large, and it is enough to charge high-voltage capacitors with a large capacity. This issue is the subject of intense research, especially in the last decade, and their

One of the proposed methods of generating electricity directly from the impact was the impact demagnetization of NdFeB permanent magnets [35, 36]. Just as a spring has its constant, which is a measure of energy accumulated in it, the magnet has similar storage properties. Large diameter springs have large solid, strong magnets and have a high energy density. Permanent magnets containing components of rare earth have the highest energy density (see **Table 2**). This applies to the generation of electricity for the instantaneous supply of microprocessor systems from the impact demagnetization of permanent magnet-type NdFeB. Currently, NdFeB magnets are the most powerful permanent magnets. The advantages of NdFeB

• The largest—of all permanent magnets—BH energy, up to 600 kJ/m3

• High hardness of the structure with simultaneous resistance to cracking

○ Poor resistance to thermal changes—high temperature has a destructive effect

○ Oxidation of the outer layer of the magnet makes it necessary to use chromium

**small power applications dedicated for them**

goal is applications, mainly military [43, 44].

permanent magnets in impact harvesting:

on the BH parameter.

as the outer layer.

• Strong magnetic flux at a surface of up to 2 T

The disadvantages of neodymium magnets include:

*DOI: http://dx.doi.org/10.5772/intechopen.85987*

**Figure 9**

**Harvester type View from** 

**Table 1.**

#### **Figure 9.**

*A view of prototypes developed in the Laboratory of Dynamics WRUT (a) and (d) low power harvesters, (b) high power harvester, (c) "Tactical grade" type harvester.*

The electric power obtained by harvesters depends on the type of material and dimensions of the core. A separate group consists of solutions based on the method of *Energy Harvester Based on Magnetomechanical Effect as a Power Source for Multi-node Wireless… DOI: http://dx.doi.org/10.5772/intechopen.85987*


**Table 1.**

*A Guide to Small-Scale Energy Harvesting Techniques*

*The classification of harvesters due to the nature of work, power, and the core material.*

**44**

**Figure 9.**

**Figure 8.**

The electric power obtained by harvesters depends on the type of material and dimensions of the core. A separate group consists of solutions based on the method of

*A view of prototypes developed in the Laboratory of Dynamics WRUT (a) and (d) low power harvesters,* 

*(b) high power harvester, (c) "Tactical grade" type harvester.*

*An overview of the prototypes of harvesters together with the most important parameters.*

demagnetizing magnets, in which neodymium magnets subjected to strong mechanical stimulation, sometimes to its destruction, are used as the core. They differ in the amount of Terfenol-D used in the magnetic circuit and provide the possibility of screwing into the structure. The view of made harvesters is shown in **Figure 9** (**Table 1**).
