Application Cases

Experiment Name: Energy Harvester Testing on an Exciter

Research Direction:
Piezoelectric energy harvesters are energy collection technologies based on the direct piezoelectric effect. They offer advantages such as simple structure, ease of use, high energy density, and resistance to electromagnetic interference. In recent years, they have attracted widespread attention from scholars both domestically and internationally, gradually becoming a research hotspot in the fields of vibration energy harvesting and self-powered wireless sensor nodes. Piezoelectric energy harvesters come in various structures, including cantilever structures, stack structures, multi-directional structures, and composite structures. Depending on the environmental vibration conditions, different structures can be selected for energy harvesting. In terms of materials, polyvinylidene fluoride (PVDF) is a flexible thin-film material suitable for manufacturing flexible sensors and energy harvesters, while lead zirconate titanate (PZT) piezoelectric ceramic materials offer high energy conversion efficiency, making them ideal for mechanical vibration energy harvesting.

Experiment Objective:
To investigate the influence of composite energy harvester parameters on the harvested voltage and power, and to introduce a method for identifying the structural parameters of composite energy harvesters. This serves as a reference for predicting the voltage and power of composite energy harvesters in practical vibration environments.

Testing Equipment:
Composite energy harvester, signal generator, ATA-4315 high-voltage power amplifier, charge amplifier, exciter, accelerometer, oscilloscope.

Experimental Procedure:
The schematic diagram of the experimental setup is shown below:
A signal generator produces a sinusoidal voltage signal, which is amplified by the power amplifier and then fed into an electromagnetic exciter. The exciter generates sinusoidal vibrations accordingly. An accelerometer and the energy harvester are mounted on the exciter and produce sinusoidal voltage signals in response to the vibrations. The accelerometer's voltage signal is amplified by a charge amplifier and displayed on an oscilloscope, while the energy harvester's voltage signal is directly sent to the oscilloscope for display. The vibration acceleration of the exciter and the open-circuit voltage of the energy harvester can be read from the oscilloscope.

Figure: Experimental Setup Diagram

The accelerometer is attached to the exciter platform using 502 adhesive, and the energy harvester is installed on the exciter platform. The experimental equipment used includes: exciter, piezoelectric accelerometer, oscilloscope, signal generator, ATA-4315 high-voltage power amplifier, charge amplifier, etc.

Experimental Results:
To study the role of the piezoelectric buzzer disc in the composite energy harvester, harvesters #2 and #5 with the same top mass were used as test subjects. The frequency characteristics of the stack voltage were measured for harvester #2 (with buzzer disc) and harvester #5 (without buzzer disc). As shown in Figure 4.6, harvesters #2 and #5 were installed on the exciter separately. The function signal generator output a sinusoidal voltage signal with an amplitude of 4V, and the amplification factor of the power amplifier remained unchanged (F constant). The two harvesters were subjected to vibration excitation at frequencies ranging from 15 Hz to 4000 Hz, and the open-circuit voltage frequency response curves of the stacks in the two harvesters were obtained, as shown in Figure 4.7.

Under the condition of the same top mass, harvester #5 (without buzzer disc) resonated at 3270 Hz, with the stack output voltage being only 1V. Such a high vibration frequency is difficult to achieve in practical environments. In low-frequency vibrations, harvester #2 (with buzzer disc) showed a distinct peak at 144 Hz, indicating resonance. At 144 Hz, the stack voltages of harvesters #2 and #5 were 3.86V and 0.3V, respectively. The stack voltage of harvester #2 was approximately 13 times that of harvester #5. According to the relevant formula, this indicates that the force on the stack in harvester #2 is 13 times that in harvester #5. The buzzer disc amplified the force on the stack. Since the stack capacitance remained unchanged, the energy collected per cycle by the stack in harvester #2 was 169 times that of harvester #5, achieving the goal of improving the power of the stack energy harvester.

Figure: ATA-4315 High-Voltage Power Amplifier Specifications

The experimental materials in this article were compiled and released by Xi’an Aigtek Electronics. For more experimental solutions, please continue to follow the Aigtek official website.