Linear induction motor excitation modulation based communication

Patent metadata

Field	Value
Publication number	US-11979203-B2
Application number	US-202117375503-A
Country	US
Kind code	B2
Filing date	Jul 14, 2021
Priority date	May 12, 2021
Publication date	May 7, 2024
Grant date	May 7, 2024

Abstract

A set of stators of a linear induction motor are mounted on a track. A three-phase current is provided to each of the stators, such that a traveling magnetic field (TMF) is created by the stators along the length of the track. The traveling magnetic field includes a magnetic flux corresponding to a stator excitation modulated with a message signal. A rotor includes a series of conductor plates. As the traveling magnetic field passes through the conductor plates, a current is induced in the plates by induction. Such current then generates an opposing magnetic field causing the plates and the vehicle to be propelled. Each phase may first be modulated with a message signal, before being provided to the stator. The current at the rotor is then demodulated to realize the message signal. A doppler shift due to the speed of the rotor relative to the stator is corrected.

First claim

What is claimed:

1. A transportation system comprising:
a ground station configured to modulate an unmodulated message signal with a first-phase of a three-phase stator excitation to create a modulated stator excitation;
a stator coupled to the ground station, the stator including a coil assembly, wherein the coil assembly of the stator is configured to receive the modulated stator excitation from the ground station by the coupling, wherein the coil assembly generates a travelling magnetic field in response to receiving the modulated stator excitation;
a vehicle including a rotor, wherein an eddy current is induced by the rotor in response to the travelling magnetic field, wherein the eddy current corresponds to the modulated stator excitation, wherein the eddy current induces a secondary magnetic field opposing the traveling magnetic field, the secondary magnetic field causing the rotor and the vehicle to translate relative to the stator, wherein the vehicle is configured to determine a demodulated message signal corresponding to the unmodulated message signal based on the eddy current.

2. The transportation system of claim 1 , wherein at least one of the ground station or the vehicle is configured to correct for a doppler shift of the travelling magnetic field due to a speed of the vehicle relative to the stator.

3. The transportation system of claim 2 , wherein the vehicle is configured to transmit the demodulated message signal to the ground station, wherein the ground station is configured to compare the demodulated message signal with the unmodulated message signal, wherein the ground station is configured to modulate subsequent stator excitation to correct for the Doppler shift based on the comparison.

4. The transportation system of claim 2 , wherein the ground station is configured to receive a signal indicative of the speed of the vehicle relative to the stator, wherein the ground station is configured to modulate subsequent stator excitation to correct for the Doppler shift based on the signal indicative of the speed.

5. The transportation system of claim 2 , wherein the vehicle is configured to resample the demodulated message signal with an average frequency corresponding to a phase modulated frequency of the stator excitation to correct for the doppler shift of the travelling magnetic field.

6. The transportation system of claim 1 , wherein the ground station is configured to modulate the first-phase with the unmodulated message signal by at least one of an amplitude modulation, a frequency modulation, or a shift keying.

7. The transportation system of claim 1 , wherein the ground station is configured to modulate the first-phase with the message signal by a transformer or a semiconductor device.

8. The transportation system of claim 1 , wherein a frequency of the unmodulated message signal is between 750 Hz and 1000 Hz, wherein a frequency of the demodulated message signal is between 750 Hz and 1000 Hz.

9. The transportation system of claim 1 , wherein the vehicle is configured to determine the demodulated message signal corresponding to the unmodulated message signal based on the eddy current by at least one of an analog filter or a digital filter.

10. The transportation system of claim 1 , further comprising a secondary rotor disposed along the stator at a fixed distance from the ground station, wherein the secondary rotor is communicatively coupled with the ground station, wherein the travelling magnetic field is configured to induce an eddy current in the secondary rotor, wherein the secondary rotor is configured to communicate a signal indicative of the eddy current induced in the secondary rotor to the ground station.

11. The transportation system of claim 10 , wherein the ground station is configured to correct a power factor or a modulation depth of the modulated stator excitation in response to receiving the signal indicative of the eddy current induced in the secondary rotor.

12. The transportation system of claim 1 , wherein the ground station is further configured to modulate a second-phase of the three-phase stator excitation with a second message signal for increasing a communication bandwidth to the vehicle.

13. The transportation system of claim 1 , further comprising an additional stator, wherein the stator is adjacent to the additional stator, wherein the stator is electrically isolated from the additional stator, wherein the additional stator is configured to generate an additional travelling magnetic field for translating the vehicle and the rotor relative to the additional stator.

14. The transportation system of claim 13 , wherein the vehicle is configured to induce an eddy current in the additional stator to repeat the demodulated message signal.

15. The transportation system of claim 13 , further comprising an additional ground station, wherein the ground station is communicatively coupled with the additional ground station for inverse multiplexing a portion of the unmodulated message signal between the ground station and the additional ground station, wherein the additional ground station is configured to communicate the inverse multiplexed portion of the unmodulated message signal to the vehicle by the additional stator and the additional travelling wave.

16. A method of communicating from a ground station to a vehicle, the method comprising:
modulating a first-phase of a three-phase stator excitation with an unmodulated message signal to create a modulated stator excitation;
providing the modulated stator excitation to a coil assembly of a stator;
generating, by the coil assembly, a travelling magnetic field in response to receiving the modulated stator excitation;
inducing an eddy current in a rotor coupled to a vehicle in response to the travelling magnetic field, wherein the eddy current corresponds to the modulated stator excitation;
inducing a secondary magnetic field opposing the traveling magnetic field by the eddy current, the secondary magnetic field causing the rotor and the vehicle to translate relative to the stator; and
determining a demodulated message signal corresponding to the unmodulated message signal based on the eddy current by at least one of an analog filter or a digital filter.

17. The method of claim 16 , further comprising:
correcting for a doppler shift of the travelling magnetic field due to a speed of the vehicle relative to the stator.

18. The method of claim 17 , wherein correcting for the doppler shift comprises:
comparing the demodulated message signal with the unmodulated message signal; and
modulating subsequent stator excitation to correct for the doppler shift based on the comparison.

19. The method of claim 17 , wherein correcting for the doppler shift comprises:
receiving a signal indicative of the speed of the vehicle relative to the stator; and
modulating subsequent stator excitation to correct for the doppler shift based on the signal indicative of the speed.

20. The method of claim 17 , wherein correcting for the doppler shift comprises:
resampling the demodulated message signal with an average frequency corresponding to a phase modulated frequency of the stator excitation to correct for the doppler shift of the travelling magnetic field.

Assignees

• Rockwell Collins Inc

Inventors

• Sundararaj Laveen Vikram
• Kumar Sheetal

Classifications

• H04B7/01 Primary

  Reducing phase shift · CPC title

• B61L3/227

  using electromagnetic radiation · CPC title

• B61L3/24

  employing different frequencies or coded pulse groups {, e.g. in combination with track circuits} · CPC title

• B61L3/243

  using alternating current · CPC title

• B61L3/246

  using coded current · CPC title