* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Download G050486-00 - DCC
Electric machine wikipedia , lookup
Power engineering wikipedia , lookup
Electrical ballast wikipedia , lookup
Mercury-arc valve wikipedia , lookup
Current source wikipedia , lookup
Transformer wikipedia , lookup
Induction motor wikipedia , lookup
Electrical substation wikipedia , lookup
Pulse-width modulation wikipedia , lookup
Spark-gap transmitter wikipedia , lookup
History of electric power transmission wikipedia , lookup
Three-phase electric power wikipedia , lookup
Power inverter wikipedia , lookup
Distribution management system wikipedia , lookup
Surge protector wikipedia , lookup
Power MOSFET wikipedia , lookup
Resistive opto-isolator wikipedia , lookup
Brushed DC electric motor wikipedia , lookup
Power electronics wikipedia , lookup
Voltage regulator wikipedia , lookup
Stray voltage wikipedia , lookup
Transformer types wikipedia , lookup
Buck converter wikipedia , lookup
Resonant inductive coupling wikipedia , lookup
Voltage optimisation wikipedia , lookup
Opto-isolator wikipedia , lookup
Switched-mode power supply wikipedia , lookup
Mains electricity wikipedia , lookup
Alternating current wikipedia , lookup
Wireless optical controls of LIGO static suspensions actuators Maria Paola Clarizia University of Sannio Mentor: Riccardo De Salvo Calum Torrie G050486-00-R LIGO R&D 1 The aim of this project A wireless control of a stepper motor to be used to balance the MIRROR suspension system of Advanced LIGO G050486-00-R LIGO R&D 2 Seismic noise At very low frequencies, seismic motions may dominate the detectors' noise, degrading their sensitivity The suspension system provides an isolation of the mirrors from the ground motion For Advanced LIGO a quadrupole pendulum mirror suspension is used G050486-00-R LIGO R&D 3 The suspension system ATTENUATED OPTICAL BENCH 22 Kg 22 Kg 40 Kg 40 Kg G050486-00-R LIGO R&D 4 The tuning mass THE TUNING MASS G050486-00-R LIGO R&D 5 PROBLEM: no tuning is possible once the vacuum chamber is close SOLUTION: remote control of the mass to adjust the pitch of the mirror METHOD: a stepping motor,which will move its own mass by means of a threaded shaft G050486-00-R LIGO R&D 6 The idea wireless circuit to control the motor, in order to eliminate mechanical A and electrical perturbations on the suspended masses, as well as an excessive load of outgas on vacuum. G050486-00-R LIGO R&D 7 What is a stepping motor? It’s an electric motor that rotates in small discrete steps (1.6O) An internal rotor containing permanent magnets is controlled by a set of stationary electromagnets that are switched electronically Stepping motors provide position holding torque while not in motion. G050486-00-R LIGO R&D 8 How to make steps A burst of current in the two coils is required to generate a step. Steps Coil 1 Coil 2 Coil 1 1 +i 2 3 +i -i 4 G050486-00-R Coil 2 -i LIGO R&D 9 How to test the motor • A charge is stored on a capacitor • G050486-00-R LIGO R&D A burst of current is injected in the coils by means of FET switches 10 The feeding circuit PULSE GENERATOR SW LASER PD TRANSFORMER RECTIFIER and CAPACITOR SW MOTOR SW SW The LASER signal used is a square wave with frequency 680 Hz G050486-00-R LIGO R&D In real life the laser would be coupled to the diode via a telescope through vacuum view port 11 Some specs The laser: Max control freq.: DC to 300 kHz Output power: 1 mW Wavelength: 635 nm The silicon detector: Responsitivity (at 635 nm) = 0.42 A/W The output current of the detector is about 0.42 mA G050486-00-R LIGO R&D 12 The transformer The main formula: V1 N1 I 2 V2 N 2 I1 ...but actually it’s not so simple!!! G050486-00-R LIGO R&D 13 Having fun… WINDING IT ALONG G050486-00-R LIGO R&D The wire used is very thin (AWG 35, that is a diameter of 0.203 mm) 14 Influences on the voltage The voltage that can be obtained on the secondary strongly depends on: The wire choice The section of the FERRITE core The excitation frequency Increasing the section of the FERRITE core, the frequency corresponding to the maximum voltage decreases G050486-00-R LIGO R&D 15 The voltage on the secondary 20 15 10 V 5 0 -5 -10 -15 -20 -5 G050486-00-R -4 -3 -2 -1 0 sec 1 LIGO R&D 2 3 4 5 -3 x 10 16 The rectifier 1 2 this kind of rectifier gives a DC voltage which is the peak peak voltage of the wave coming from the transformer (a SMALL voltage drop is due to the diodes). G050486-00-R LIGO R&D 17 Impedance matching The rectifier impedance changes while the capacitor charges up. 6 0 V V 2 6 4 4 2 2 0 0 V 4 6 -2 -2 -2 -4 -4 -4 -6 -5 -4 -3 -2 -1 0 sec 1 2 G050486-00-R 3 4 5 -3 x 10 -6 -5 -4 -3 -2 -1 0 sec 1 2 LIGO R&D 3 4 5 -3 x 10 -6 -5 -4 -3 -2 -1 0 sec 1 2 3 4 5 -3 x 10 18 Choice of the capacitor The generation of a MOTOR step requires a certain amount of charge. The bigger the capacitance, the slower the charging up TIME, but the smaller the capacitance, the higher the voltage required for A motor STEP. The capacitance has to be big enough to defeat stictions G050486-00-R LIGO R&D 19 The capacitor chosen Several charge up times have been measured for different values of the capacitance and different transformers. A capacitor of 100µF seems to be a good tradeoff! Voltage needed: 5 V Time of wait for one step: approximately one minute WITH 1 mW LASER POWER G050486-00-R LIGO R&D 20 The charging up curve G050486-00-R LIGO R&D 21 Further improvements The transformer used gives a good voltage, but it’s not optimized: a higher voltage could allow a smaller capacitor or a faster charge up time to be used. Impedance mismatching should be taken into account A laser with a larger power can be used to provide a stronger signal and to lower the waiting time for one step G050486-00-R LIGO R&D 22 Next steps Developing the FET SWITCH control circuit of the motor. The principle is to use frequency jumps to control gates of FET switches and four bandpass filters to route the current pulses. G050486-00-R LIGO R&D 23 acknoledgements My mentors Riccardo De Salvo and Calum Torrie My professor Innocenzo Pinto Dave Grimmett, Paul Russel and Peter King Marco Tarallo Ilaria Taurasi Yuri, Chiara, and all the italian people (including John HONORARY ITALIAN) United states for: •Wonderful places •Wonderful people G050486-00-R •Wonderful cookiesLIGO R&D 24 THAT’S IT ! G050486-00-R LIGO R&D 25