BS IEC 62830-6:2019 pdf free download – Semiconductor devices – Semiconductor devices for energy harvesting and generation
4.2 Limiting values and operating conditions
The characteristic parameters should be listed as shown in Table 1 . The manufacturer shall clearly announce the operating conditions and their limitation for energy harvesting. The limiting value is the maximum operating cycle to ensure the operation of the vertical contact mode energy harvester for power generation without any damage. Some mandatory input parameters, such as applied force, input frequency, number of cycles and internal impedance of the harvester shall be recorded. Some optional input parameters, such as surface roughness, material strain, capacitance, and dimension of the harvester shall also be recorded. Some mandatory output parameters are open-circuit voltage, short-circuit current, output voltage (for matching load), output current (for matching load), charge transfer between electrodes, and optimum load impedance. Some optional output parameters, such as rectified voltage and current, capacitor charging voltage, and reliability shall also be recorded.
5.2.1 Test procedure
Figure 5 shows a test setup for measuring the electrical characteristics of a device under test. To measure the electrical characteristics of the energy harvester, the device shall be mounted on a linear motor or force gauge. When a continuous excitation with specified acceleration and frequency is applied to the device, an output voltage or current across an external load is measured. Before the contact-separation operation happens, the initial surface potential of the interfacing material is zero. Therefore, the output performances (voltage, current and charge) of the harvester experience unsteady change at the initial cycles of operation and then reach a stable value. This unsteady change of output lasts between the first 1 to 5 cycles of operation, based on the inherent properties of the interfacing materials. To avoid this unavoidable unsteady change, it is recommended to take the output data after the first five cycles of operation. In case a custom-made testing setup other than a linear motor or force gauge is used, some input parameters, such as input frequency, applied force, and operating cycles shall be monitored using precision sensing equipment.
5.2.2 Open-circuit voltage
The objective of this test is to measure the instantaneous output voltage across the terminals of the energy harvester without external load. When measuring the open-circuit voltage, the input impedance of the voltage meter shall be recorded. Figure 6 shows the graphical shape of a measured instantaneous open-circuit output RMS voltage as a function of time. When measuring voltage, the input impedance of the meter shall be many decades higher than the impedance of the voltage source. For example, if the meter’s input impedance is only 1 GΩ (typical of DMMs), and the source of the voltage has 1 0 MΩ of impedance, then the meter will introduce a 1 % error due to its relatively low input impedance. In contrast, an electrometer with 1 0 1 4 Ω input impedance will cause only a 0,000 01 % error.