# Design of an Energy Harvester Based on a Rubber Bearing Floating Slab Track
## 4 Performance Comparison of Energy Harvesters
### Load Match
While the output power was low when the load resistance was very small or very large, it first increased and then decreased with the increase in the load resistance, and there was a maximum value. In addition, as can be seen from the shaded part under the curve, when the load resistance \(R_{L}\) was in a certain range (50-200 K\(\Omega\)), the output power of the disk energy harvester was about 1.7 \(\times\) 10\({}^{-3}\) mW, which was at a low level. And the output voltage was less than 0.5 V in this resistance range, making it difficult to achieve the minimum input requirements of the energy capture circuit, so the electrical output performance of the disk energy harvester was found to be relatively ordinary. In this range, the load resistance that made the output power optimal was the \"matching impedance\". Therefore, when \(R_{L}=90\) K\(\Omega\), the maximum output power was 2.03 \(\times\) 10\({}^{-3}\) mW, and the internal resistance of the piezoelectric energy harvester was calculated to be 90 K\(\Omega\). The load match model of the symbol energy harvester was established, and the effect of external load resistance on the output power of the symbol energy harvester was studied by frequency domain analysis. The results of voltage variation with resistance on the load  
Figure 10: Influence of load resistance on the electrical output characteristics of the disk energy harvester. resistor are shown in Figure 11a, and the results of power variation with resistance are shown in Figure 11b. According to the results, as the circuit load resistance increased, the voltage across the resistor increased monotonically and at a decreasing rate. When the load resistance increased to a near open circuit, the output voltage was 5.2 V, which approached the open circuit voltage of 6.5 V, and the curve tended to flatten out. While the output power was low when the load resistance was very small or very large, it first increased and then decreased with the increase in the load resistance, and there was a maximum value in the process. When the load resistance \(R_{L}\) was within a certain range (50-200 K\(\Omega\)), the output voltage of the cymbal energy harvester was able to reach the input requirement of the energy harvesting circuit, which was greater than 1.4 V. And the output power reached a high level, up to 0.13 mW. Meanwhile, when \(R_{L}=90\)K\(\Omega\), the maximum output power was 0.15 mW, and the internal resistance of the cymbal piezoelectric energy harvester was calculated to be 90 K\(\Omega\). Compared with the disk energy harvester, the cymbal energy harvester had the same matching impedance of 90 K\(\Omega\). But the output power of the cymbal energy harvester was two orders of magnitude higher than that of the disk type at a better load resistance, and it was up to the microwatt level. The load match model of the spherical energy harvester was established, and the effect of external load resistance on the output power of the energy harvester was studied through frequency domain analysis. The voltage on the load resistor varied with the resistance, as shown in Figure 12a, and the power varied with the resistance, as shown in Figure 12b. As can be seen from Figure 12, with the increase in circuit load resistance, the voltage across the resistor increased monotonously, and the growth rate decreased. When the load resistance increased to a near open circuit, the output voltage was 6.53 V, which approached the open circuit voltage of 6.7 V, and the curve tended to level off at this time. The output power was lower when the load resistance was very small or very large, and the law was consistent with other energy harvesters, that is, the power first increased and then decreased with the increase in load resistance, and there was a maximum value in the process.