There are two main circuits within the system; the transmitter and the receiver.
The transmitter takes in the compression force and temperature data that is going to be monitored and modulates it into an encoded data signal. The signal is then carried from the transmitter to the receiver circuit using an antenna. The receiver circuit demodulates the signal converting it into a suitable form which can be processed accordingly. All this is done within microseconds, with the latency time delay being very small to allow us to monitor operation in real time. The transmitter module is also responsible to keep the power level of the wave to the regulated value in the country. 25 We have found a microcontroller chip manufactured by Microchip, which is ideal for operating at extreme environments, with an operating ambient temperature up to 150?.
It has a communication interface which has data rate of 15Mb/s and provides a high-resolution time measurement of 1ns, thus low latency. 26Power By Angel ReyesThe receiver module is outside the rotor and can be close to the generator controller, thus can be powered by the generator controller via cable. The microcontroller however, is mounted within the rotor therefore would be to be powered by a wireless powering system. 27 Energy HarvestingThere are induced currents from the changes in magnetic flux within the generator.
These readily available wireless signal power can be captured and transformed into an electrical power supply which can then power the microcontroller. Harvesting the power within the electromagnetic generator to power the microcontroller is an efficient and simple way. There can also be an added energy storage to continuously operate the microcontroller even when there is no ambient energy available.
To harvest the energy within the electromagnetic generator we need an inductive pickup coil which is dedicated to receiving the wireless signals. A rectifier would need to be in place to convert the induced current to a wireless DC electrical voltage supply. This DC electric voltage would need to be filtered and smoothed out using a low pass filter.
To ensure a constant value of DC voltage is supplied to the microcontroller a regulator is in place, preventing a too high voltage supply which can blow up the circuit, as it is a 100kW generator. 28We have found an energy harvesting kit from Cymbet Corporation however they are designed for small generators; therefore, it would be best to build a specific circuit to meet the needs. Figure 7 shows a simple example of the circuit which would need to be incorporated for energy harvesting.
A low pass filter is desired as the signal needs to be as flat as possible to achieve a 0Hz (DC) frequency with no ripples. 29 We can calculate the power used in the system by the transmitter components which are the; IR LEDs, the thermistor, the strain gauges and the microcontroller. These calculations can be seen in the equations below. We however cannot calculate the amount of power the voltage converter chip will use as we do not know the magnetic flux within the generator. The amount of power used by the system is 1.27W showing that we will not be using much power compared to the amount the generator generates, causing its efficiency to only change slightly or even remain the same.