Research On Critical Technologies Of Telemetry Of Rotor Status

The acquisition of rotor status is a key part and a difficult problem in state monitor and improvement of rotary machines.Slip ring,the tradition method,is not the best way to acquire the status signals because of shorter life,less channels,louder noise compared with telemetry.The deployment of telemetry requires stable and continuous rotary power transfer,precious and low-noise sensor signal conditioning along with high-speed and accurate data transfer under high-speed rotating machines with rotor run out.Therefore,rotary power transfer,sensor signal conditioning and data transfer are key technologies of telemetry.This dissertation did a deep research on those technologies and the main works are as follows:The overall scheme is proposed targeting at requirements of the high-precision measurement,low power-consuming design of circuits on rotor parts and multi-channel signal transfer.With it,low EMI rotary power transfer based on rotary transformer and LLC resonant converter,low power-consuming sensor signal conditioning based on constant current source excitation of strain gauge along with fast parallel data transmission based on FSK modulation are all realized.A new optical feedback circuit is proposed targeting at the problem of inductance fluctuation caused by rotor run out.With it,a closed-loop control method can be implanted in the power transfer module for automatic resonant frequency tracking and soft-switching by transferring the cross-zero time of secondary current to the primary part.The requirements of low EMI of rotary power transfer,low power-consuming and miniaturization of circuits on rotor are also met with it.A wireless data transfer module based on FSK modulation is designed targeting at multi-channel parallel high-speed wireless transmission.The effective data transfer rate of the module is 5.14Mbps,which means it can deliver 4 channels strain signals and 10 channels temperature signals at the same time.By setting the different carrier frequencies,the telemetry system is able to support 20 modules at most to transfer data at the same time and without crosstalk.An antenna structure of combining a single frequency monopole transmitter antenna and a wide band receiver antenna which targets at the rotary structure of telemetry is designed,which solved the―shadow effect‖introduced by rotary power transfer.The design is beneficial to reduce the attenuation of wireless signal in transmission and expand the transmission channels.By deploying the antenna,a wireless data transmission with bit error rate better than 10^-6can be realized under11-30mm antenna gap and 0-3000rpm rotating speed.The prototype of telemetry was made and experiments were conducted to verify the correctness the proposals.A strain gauge was actually used to measure the strain signal via telemetry when the rotor is at rest.The rotating experiments were also conducted with rotating speed under 0-3000rpm.During the whole test,the rotary power transfer module was able to feed the system with stable power,while Effective data transmission rate and frequency spacing of the wireless data transfer module were also not affected by rotation,and the dynamic range of the sensing signal conditioning module is better than 62.99d B.