IL292255A - System and method for active cancellation of magnetic fields - Google Patents

Description

SYSTEM AND METHOD FOR ACTIVE CANCELLATION OF MAGNETIC FIELDS TECHNOLOGICAL FIELD The present disclosure is in the field of radiation shielding systems and techniques and relates to techniques for active cancellation or reduction of time-varying magnetic fields.

BACKGROUND Electromagnetic radiation, and general electromagnetic fields surrounding human environment is increasing with the use of electrical tools. Electric vehicles utilize electricity operating motors for transmitting power to the wheels and additional electrical elements that operate the vehicle.

Various other scenarios and applications may require the ability for nullifying or significantly reducing electromagnetic fields (EMF) or electromagnetic radiation in certain regions. According to medical research, low frequency magnetic radiation is believed to cause long-term adverse health effects. In the example of electric automobiles/vehicle, reducing the EMF radiation in the area of the passengers’ seats may be desired.

GENERAL DESCRIPTION The present disclosure provides a system and technique for eliminating, or at least significantly reducing, electromagnetic fields in a selected region, and specifically time- varying electromagnetic fields. Such magnetic and electromagnetic fields may be generated on one or more magnetic field sources, generally external to the system of the present disclosure, where electrical current and/or one or more magnets are operated. For example, source of undesired electromagnetic field may be associated with operation of electric or hybrid electric vehicle.

The present technique is specifically directed at reducing magnetic fields in a selected region, by determining pattern of the magnetic field generated by one or more external sources that is to be canceled, and generating, using one or more magnetic field generators, magnetic fields having opposite direction and same or similar magnitude over time and space. Generally, the magnetic field within the selected region is not spatially uniform and may also vary in time. The present technique utilizes one or more magnetic field generators configured to be positioned around a selected region, one or more magnetic field sensors configured for sensing magnetic fields in at least a portion of said selected region, and a control system. The control system is operatively connectable to said one or more magnetic field generators and magnetic field sensors. The control system is further configured for receiving sensing data on sensed magnetic field from the one or more magnetic field sensors, processing the sensing data and determining one or more parameters of a cancellation magnetic field, and operating the one or more magnetic field generators for generating said cancellation magnetic field. The cancellation magnetic field is generally determined as a magnetic field pattern that is similar in magnitude and opposite in direction to magnetic field generated by one or more external sources. Such external sources may include various magnetic field sources. In the general frame of electric vehicles such external sources may include, for example: electric motor, electrical transmission lines, DC-AC current and/or voltage inverter, or other electrical elements in a vehicle. Typically, the control system according to the present disclosure may operate as a feedback control system for cancelling magnetic fields in the selected region. More specifically, the control system may operate to minimize magnetic field sensed by the one or more sensors, or certain relation between magnetic field data collected by two or more sensors. Generally, the sensing data collected by the one or more magnetic field sensors may be associated with residual magnetic field, formed of external magnetic field and cancellation magnetic field generated by the one or more magnetic field generators. Accordingly, operation of the control system provides for minimizing a selected function associated with the detected magnetic field. More specifically, the magnetic field generators, operated by the system of the present disclosure, generate magnetic fields, typically directed in opposite to external magnetic field. This magnetic field is included in the sensing data and thus needs to be considered in determining cancellation field. The magnetic field sensors are generally placed in vicinity or around the selected region, while oriented along selected direction to enable cancellation of vector magnetic field. Specifically, each sensor generally collects data on magnetic field flux through a respective surface/aperture defined by arrangement of the sensor. Thus, selected number of sensors are arranged along generally intersecting planes for providing sensing data on magnetic field along two or more, and preferably three axes. Further, the feedback control may also operate in accordance with effects of time-varying electromagnetic field on response function the magnetic field generators. More specifically, variation in electromagnetic flux through the magnetic field generators generally induce current therethrough. The feedback control according to the present disclosure utilizes data on magnetic field for estimating induced current and adjusting electrical current provided to the magnetic field generator to optimize field cancellation. As indicated above, the present technique may be operable in a vehicle, e.g., electric or hybrid electric vehicle, where electric motor, and other electrical systems generate magnetic fields within passenger’s cabin of the vehicle. The present technique utilizes a generally active field cancellation technique. This enables a generally broadband cancellation of time-varying magnetic field, typically up to tens of KHz, and generally spatially non-uniform. This is advantageous over magnetic shielding methods, which are generally costly, require complete, or almost complete enclosure, are limited and set during the enclosure design. Also, shielding arrangement cannot be altered using signal processing or any other "soft" methods. In addition, high permeability material is subject to saturation due to external magnetic fields, such as earth's magnetic field, which further degrades the shielding effectiveness. Additional techniques use faraday cages directed at shielding from high frequency electromagnetic radiation such as RF radiation. Thus, according to some embodiments, the present disclosure provides a system comprising: one or more magnetic field generators configured to be positioned around a selected region, one or more magnetic field sensors configured to provide sensing data indicative of a magnetic field in said selected region, and a control system; the control system being operatively connectable to said one or more magnetic field generators and magnetic field sensors, and configured for: receiving said sensing data on the magnetic field in said selected region, processing the sensing data and determining one or more parameters of a cancellation magnetic field for cancelling or at least significantly reducing a magnitude of the magnetic field in said selected region and operating said one or more magnetic field generators for generating said cancellation magnetic field. Generally, the one or more magnetic field sensors may be configured to provide sensing data on magnetic field in at least a portion of the selected region. According to some embodiments, the one or more magnetic field generators may comprise two or more magnetic field generators positioned to generate magnetic fields within said selected region with magnetic field vectors being along two or more intersecting axes within said selected region. According to some embodiments, the one or more magnetic field generators may comprise three or more magnetic field generators positioned and oriented to generate magnetic fields having magnetic field vectors being along three or more intersecting axes within said selected region, thereby enabling generation of magnetic field in three-dimensional span within said selected region. According to some embodiments, the system may comprise an arrangement of one or more magnetic field generators spatially overlapping with respective one or more magnetic field sensors, thereby providing magnetic field cancellation and minimizing magnetic field flux through said one or more magnetic field sensors. Further, in some embodiments the system may comprise additional one or more magnetic field generators, positioned at a selected distance from said arrangement of magnetic field generator spatially overlapping respective magnetic field sensor, and wherein said control system is configured to apply feedback control for determining cancellation magnetic field generated by said one or more magnetic field generators and said additional one or more magnetic field generator, having selected feedback gain parameters, to thereby selectively minimize magnetic field flux at a selected region between said one or more magnetic field generator and said additional one or more magnetic field generator.

The one or more magnetic field generators and said additional one or more magnetic field generators may be positioned at two sides of said selected region. Additionally, or alternatively, the one or more magnetic field generators and said additional one or more magnetic field generators may be positioned at two opposite sides of said selected region. According to some embodiments, the control system comprises at least one integrator module, configured and operable for integrating voltage signals provided from said one or more magnetic field sensors, to thereby determine said sensing data indicative of magnetic field flux through said one or more magnetic field sensors. In yet some embodiments, the control system is configured for processing said sensing data in accordance with one or more pre-stored parameters indicative of magnetic field induction between said one or more magnetic field generators and said one or more magnetic field sensors, to determine output current transmitted to said one or more magnetic field generators. In some further embodiments, the control system is configured and operable for determining output current transmitted to said one or more magnetic field generators, said determining output current comprises determining data in electrical current induced through said one or more magnetic field generators in response to magnetic field flux variation through said one or more magnetic field generators, said magnetic field flux variations is associated with variation in external magnetic field and variation in cancellation magnetic field generated by one or more other magnetic field generators. According to some embodiments, the one or more of said one or more magnetic field generators is operable as said one or more magnetic field sensors using time division duplex operation. In this connection the system may operate in operation cycles including sample/sensing period, processing period, and generating period in which the magnetic field generators are operated for generating cancelation magnetic field. According to some embodiments, the control system comprises: one or more processors and a memory unit, said memory unit is pre-stored with calibration data comprising calibration data indicative of a magnetic field pattern generated by said one or more magnetic field generators in response to respective operation electric currents transmitted therethrough, said one or more processors are configured to: receive sensing data on the magnetic field detected by said one or more magnetic field sensors, process the sensing data on said magnetic field and, determine said one or more parameters of the cancellation magnetic field utilizing said calibration data, said one or more parameters comprising output electric current pattern to be transmitted to said one or more magnetic field generators to thereby generate said cancellation magnetic field. According to some embodiments, the one or more processors are configured for utilizing output electric current data indicative of an electric current provided to said one or more magnetic field generators, said calibration data and sensing data from said one or more magnetic field sensors for determining an external magnetic field pattern corresponding with a portion of magnetic field generated by one or more sources external to said system. According to some embodiments, the system may be configured to be used in a range of one or more predetermined external magnetic field sources, wherein said memory unit comprises pre stored field data indicative of a time-varying pattern of a magnetic field generated by said one or more external sources and affecting said selected region, said one or more processors being configured for processing sensing data obtained from said one or more sensors at a sensing time period, and using said pre-stored field data, determine, generally by computing, an estimation of the magnetic field generated by the one or more external sources at a cancelling time period subsequent to the sensing time period, to thereby determine said one or more parameters for generating said cancellation magnetic field for cancelling or at least significantly reducing a magnitude of the magnetic field in said selected region at the cancelling time period. Generally, one or more magnetic field sources may generate varying magnetic field having a typical time profile, e.g., rotating magnetic field, estimation of magnetic field generation at a cancelation time period may comprise utilizing calibration data on typical variation of magnetic field generated by one or more sources in accordance with length of operation cycle and periods thereof. To this end, according to some embodiments, the pre stored field data may be indicative of the time varying pattern of magnetic field comprises data indicative of a generally rotating magnetic field portion. The control system may also be configured to determine in real time, a set of calibration coefficients for use, out of a selected pre-stored sets of coefficients. The decision is based on detecting a change in the spatial pattern of the magnetic field that indicated magnetic radiation emitted from one or more different sources. For example, one source may operate, emitting magnetic field, and at certain time another source may be kicking in or out of operation, varying the general pattern of the magnetic field. The calibration data may comprise of one or more sets of calibration coefficients associated with operation of one or more different magnetic field sources for which the calibration data is assigned. According to some embodiments, one or more of said one or more magnetic field generators may be operable as said one or more magnetic field sensors using time division duplex operation defining one or more combined sensor generator units, said control system being configured for operating said one or more combined sensor generator units for sensing magnetic field flux therethrough in a first period of operation cycle, processing sensing data on detected magnetic flux in a second period of operation cycle, and operating said one or more magnetic field generators for generating cancellation magnetic field in a third period of operation cycle. According to some embodiments, at least one of said one or more magnetic field generators is configured of a coil of effective diameter D and carrying N windings. In some embodiments, the magnetic field generators may be generally similarly wrapped coils. According to some embodiments, the one or more coils are covered by high permeability metal coating, thereby reducing magnetic field in close proximity to said coil, while maintaining far field effects on the magnetic field. According to some embodiments, the one or more magnetic field generators may be formed of a coil having generally circular shape. According to some embodiments, the one or more magnetic field generators may be formed of a coil having generally oval shape. According to some embodiments, the one or more magnetic field generators may be formed of a coil having generally polygonal shape. Design and shape of the one or more magnetic field generators may be selected in accordance with characteristic spatial radiation pattern for selected one or more magnetic field external sources and the characteristics and location of one or more target areas for magnetic fields cancelation or reduction.

According to some embodiments, the system may be configured to be placed in a vehicle, the system being operated for reducing effective magnetic field generated by components of said vehicle in a selected region comprising at least a portion of driver or passenger occupying region of said vehicle. The vehicle may be at least partially operated by one or more electric motors. According to some embodiments, the system may be configured to be mounted in a selected front and/or rear seat of a vehicle. According to some embodiments, the system may be configured as integral part of a vehicle. According to some embodiments, the system may be configured to be mounted in a child safety seat, or in a child or baby bed. According to one other broad aspect, the present disclosure provides an electric vehicle (EV or HEV) comprising a system for cancellation or at least significant reduction of magnetic fields; the system comprises: one or more magnetic field generators configured to be positioned around a selected region of the electric vehicle, one or more sensors configured to provide sensing data on magnetic fields in at least a portion of said selected region, and a control system; the control system being operatively connectable to said one or more magnetic field generators and magnetic field sensors, and configured for: receiving said sensing data on the magnetic field in said selected region, processing the sensing data and determining one or more parameters of a cancellation magnetic field for cancelling or at least significantly reducing a magnitude of the magnetic field in said selected region and operating said one or more magnetic field generators for generating said cancellation magnetic field. According to yet another broad aspect, the present disclosure provides a safety seat for use in a vehicle, comprising a system for cancellation or at least significant reduction of magnetic field s; the system comprises: one or more magnetic field generators configured to be positioned around a selected region of the safety seat, one or more sensors configured to provide sensing data on magnetic fields in at least a portion of said selected region, and a control system; the control system being operatively connectable to said one or more magnetic field generators and magnetic field sensors, and configured for: receiving said sensing data on the magnetic field in said selected region, processing the sensing data and determining one or more parameters of a cancellation magnetic field for cancelling or at least significantly reducing a magnitude of the magnetic field in said selected region and operating said one or more magnetic field generators for generating said cancellation magnetic field. According to a further broad aspect, the present disclosure provides a method for reducing magnitude of magnetic field within a selected region, the method comprising: installing one or more magnetic field sensors and one or more magnetic field generators in vicinity of said selected region, collecting sensing data processing sensing data on magnetic flux passing through said magnetic field sensors and processing said sensing data and determining a magnetic field pattern within said selected region generated by one of or more external sources, determining cancellation magnetic field pattern for cancelling or at least significantly reducing magnitude of magnetic field through said selected region and operating said one or more magnetic field generators for generating said magnetic field cancellation pattern. According to some embodiments at least one of said one or more magnetic field sensors and one or more magnetic field generators may be a common magnetic field sensing and generating unit, the method comprises operating said at least one common magnetic field sensing and generating unit in time division duplex for sensing magnetic field flux therethrough in a first period of operation cycle, processing data on detected magnetic flux in a second period of operation cycle, and operating said one or more magnetic field generators for generating cancellation magnetic field in a third period of operation cycle. According to some embodiments said collecting sensing data on magnetic flux from said one or more magnetic field sensors and operating said one or more magnetic field generators for generating cancellation magnetic field pattern may be performed simultaneously; said processing comprises determining pattern of sensed magnetic field, detected by said one or more magnetic field sensors, determining pattern of internally generated magnetic field generated by said one or more magnetic field generators, and subtracting said internally generated magnetic field from said sensed magnetic field, to thereby determine pattern of externally generated magnetic field. According to a further broad aspect, the present disclosure provides a method for reducing magnitude of magnetic field within a selected region, the method comprising: installing one or more magnetic field sensors and one or more magnetic field generator in vicinity of said selected region, collecting and processing sensing data on magnetic flux passing through said magnetic field sensors and operating said one or more magnetic field generators for generating cancellation magnetic field for cancelling or at least significantly reducing magnitude of magnetic field through said selected region and operating said one or more magnetic field generators for generating said magnetic field cancellation pattern. According to some embodiments, at least one of said one or more magnetic field sensors and one or more magnetic field generators are placed to be spatially overlapping each other forming a sensor-generator pair, thereby providing magnetic field cancellation that minimizes magnetic flux through said one or more magnetic field sensors. According to some embodiments, the method may further comprise installing at least one additional magnetic field generator, positioned at a selected distance to be spatially separated from a respective sensor-generator pair, thereby enabling minimizing magnetic field at a position between spatial location of said sensor-generator pair and said additional magnetic field generator. According to some embodiments, said processing sensing data comprises determining a magnetic field pattern within said selected region generated by one of or more external sources, determining a pattern of cancellation magnetic field, and operating said one or more magnetic field generators for generating said pattern of cancellation magnetic field. According to some embodiments, at least one of said one or more magnetic field sensors and one or more magnetic field generators may provide a common magnetic field sensing and generating unit, the method comprises operating said at least one common magnetic field sensing and generating unit in time division duplex for sensing magnetic field flux therethrough in a first period of operation cycle, processing data on detected magnetic flux in a second period of operation cycle, and operating said one or more magnetic field generators for generating cancellation magnetic field in a third period of operation cycle.

BRIEF DESCRIPTION OF THE DRAWINGS In order to better understand the subject matter that is disclosed herein and to exemplify how it may be carried out in practice, embodiments will now be described, by way of non-limiting example only, with reference to the accompanying drawings, in which: Fig. 1 schematically illustrates a system according to some embodiments of the present disclosure; Fig. 2 exemplifies configuration of the system according to some embodiments of the present disclosure installed in a vehicle; Figs. 3A to 3C exemplify spatial arrangements of magnetic field generators and sensors for using feedback control, illustrating overlapping magnetic field generators and sensors (Fig. 3A), separated generator and sensors (Fig. 3B), and combination of overlapping and separated generators and sensors (Fig. 3C) Fig. 4illustrates a control feedback operation for the system arrangement in Fig. 3C ; Fig. 5 exemplifies feedback control schematics for operation using two magnetic field sensors and two magnetic field generators; Fig. 6 exemplifies operation of the technique according to some embodiments of the present disclosure in a way of a block diagram; Fig. 7 exemplifies sequential operation of sensing and generating cancellation magnetic field according to some embodiments of the present disclosure; Figs. 8A and 8B exemplify processing configurations of the control system according to some embodiments of the present disclosure, Fig. 8A exemplifies direct digital processing configuration, and Fig. 8B exemplifies processing arrangement configured for varying processing topologies; Figs. 9A and 9B exemplify respectively configurations of exposed and shielded magnetic field generators according to some embodiments of the present disclosure; Fig. 10 illustrates a use of sensors for indirect measurement of magnetic field from external source according to some embodiments of the disclosure; Fig. 11 exemplifies a child safety seat carrying a system according to some embodiments of the present disclosure; and Fig. 12 illustrates a use of the present technique in an electric vehicle utilizing wireless charging.

Claims (35)

- 35 - CLAIMS:

1. A system comprising: one or more magnetic field generators configured to be positioned around a selected region, one or more magnetic field sensors configured to provide sensing data indicative of a magnetic field in said selected region, and a control system; the control system being operatively connectable to said one or more magnetic field generators and magnetic field sensors, and configured for: receiving said sensing data on the magnetic field in said selected region, processing the sensing data and determining one or more parameters of a cancellation magnetic field for cancelling or at least significantly reducing a magnitude of the magnetic field in said selected region and operating said one or more magnetic field generators for generating said cancellation magnetic field.

2. The system of claim 1, wherein said one or more magnetic field sensors are configured to provide sensing data on magnetic field in at least a portion of the selected region.

3. The system of claim 1 or 2, wherein said one or more magnetic field generators comprise two or more magnetic field generators positioned to generate magnetic field within said selected region with magnetic field vectors being along two or more intersecting axes within said selected region.

4. The system of any one of claims 1 to 3, wherein said one or more magnetic field generators comprise three or more magnetic field generators positioned and oriented to generate magnetic field having magnetic field vectors being along three or more intersecting axes within said selected region, thereby enabling generation of magnetic field in three-dimensional span within said selected region.

5. The system of any one of claims 1 to 4, comprising an arrangement of one or more magnetic field generators spatially overlapping with respective one or more magnetic field sensors, thereby providing magnetic field cancellation and minimizing magnetic field flux through said one or more magnetic field sensors.

6. The system of claim 5, further comprising additional one or more magnetic field generators, positioned at a selected distance from said arrangement of magnetic field - 36 - generator spatially overlapping respective magnetic field sensor, and wherein said control system is configured to apply feedback control for determining cancellation magnetic field generated by said one or more magnetic field generator and said additional one or more magnetic field generator, having selected feedback gain parameters, to thereby selectively minimize magnetic field flux at a selected region between said one or more magnetic field generator and said additional one or more magnetic field generator.

7. The system of claim 6, wherein said one or more magnetic field generators and said additional one or more magnetic field generators are positioned at two sides of said selected region.

8. The system of claim 6, wherein said one or more magnetic field generators and said additional one or more magnetic field generators are positioned at two opposite sides of said selected region.

9. The system of any one of claims 1 to 8, wherein said control system comprises at least one integrator module, configured and operable for integrating voltage signals provided from said one or more magnetic field sensors, to thereby determine said sensing data indicative of magnetic field flux through said one or more magnetic field sensors.

10. The system of any one of claims 1 to 9, wherein said control system is configured for processing said sensing data in accordance with one or more pre-stored parameters indicative of magnetic field induction between said one or more magnetic field generators and said one or more magnetic field sensors, to determine output current transmitted to said one or more magnetic field generators.

11. The system of any one of claims 1 to 10, wherein said control system is configured and operable for determining output current transmitted to said one or more magnetic field generators, said determining output current comprises determining data in electrical current induced through said one or more magnetic field generators in response to magnetic field flux variation through said one or more magnetic field generators, said magnetic field flux variations is associated with variation in external magnetic field and variation in cancellation magnetic field generated by one or more other magnetic field generators.

12. The system of any one of claims 1 to 4, wherein one or more of said one or more magnetic field generators is operable as said one or more magnetic field sensors using time division duplex operation.

13. The system of any one of claims 1 to 12, wherein said control system comprises: - 37 - one or more processors and a memory unit, said memory unit is pre-stored with calibration data comprising calibration data indicative of a magnetic field pattern generated by said one or more magnetic field generators in response to respective operation electric currents transmitted therethrough, said one or more processors are configured to: receive sensing data on the magnetic field detected by said one or more magnetic field sensors, process the sensing data on said magnetic field and, determine said one or more parameters of the cancellation magnetic field utilizing said calibration data, said one or more parameters comprising output electric current pattern to be transmitted to said one or more magnetic field generators to thereby generate said cancellation magnetic field.

14. The system of claim 13, wherein said one or more processors are configured for utilizing output electric current data indicative of an electric current provided to said one or more magnetic field generators, said calibration data and sensing data from said one or more magnetic field sensors for determining an external magnetic field pattern corresponding with a portion of magnetic field generated by one or more sources external to said system.

15. The system of claim 13 or 14, the system being configured to be used in a range of one or more predetermined external magnetic field sources, wherein said memory unit comprises pre stored field data indicative of a time-varying pattern of a magnetic field generated by said one or more external sources and affecting said selected region, said one or more processors being configured for processing sensing data obtained from said one or more sensors at a sensing time period, and using said pre-stored field data, determine an estimation of the magnetic field generated by the one or more external sources at a cancelling time period subsequent to the sensing time period, to thereby determine said one or more parameters for generating said cancellation magnetic field for cancelling or at least significantly reducing a magnitude of the magnetic field in said selected region at the cancelling time period.

16. The system of claim 15, wherein said pre stored field data indicative of the time varying pattern of magnetic field comprises data indicative of a generally rotating magnetic field portion. - 38 -

17. The system of any one of claims 13 to 16, wherein one or more of said one or more magnetic field generators are operable as said one or more magnetic field sensors using time division duplex operation defining one or more combined sensor generator units, said control system being configured for operating said one or more combined sensor generator units for sensing magnetic field flux therethrough in a first period of operation cycle, processing sensing data on detected magnetic flux in a second period of operation cycle, and operating said one or more magnetic field generators for generating cancellation magnetic field in a third period of operation cycle.

18. The system of any one of claim 1 to 17, wherein at least one of said one or more magnetic field generators is configured of a coil of effective diameter D and carrying N windings.

19. The system of claim 18, wherein said coil is covered by high permeability metal coating, thereby reducing magnetic field in close proximity to said coil, while maintaining far field effects on the magnetic field.

20. The system of any one of claims 1 to 19, wherein said one or more magnetic field generators are formed of a coil having generally circular shape.

21. The system of any one of claims 1 to 19, wherein said one or more magnetic field generators are formed of a coil having generally oval shape.

22. The system of any one of claims 1 to 19, wherein said one or more magnetic field generators are formed of a coil having generally polygonal shape.

23. The system of any one of claims 1 to 22, configured to be placed in a vehicle, the system being operated for reducing effective magnetic field generated by components of said vehicle in a selected region comprising at least a portion of passenger occupying region of said vehicle.

24. The system of claim 23, wherein said vehicle is at least partially operated by one or more electric motors.

25. The system of any one of claims 1 to 24, configured to be mounted in a rear seat of a vehicle.

26. The system of any one of claims 1 to 24, configured to be mounted in a child safety seat.

27. The system of any one of claims 1 to 24, configured as integral part of a vehicle.

28. An electric vehicle (EV or HEV) comprising a system for cancellation or at least significant reduction of magnetic fields; the system comprises: - 39 - one or more magnetic field generators configured to be positioned around a selected region of the electric vehicle, one or more sensors configured to provide sensing data on magnetic fields in at least a portion of said selected region, and a control system; the control system being operatively connectable to said one or more magnetic field generators and magnetic field sensors, and configured for: receiving said sensing data on the magnetic field in said selected region, processing the sensing data and determining one or more parameters of a cancellation magnetic field for cancelling or at least significantly reducing a magnitude of the magnetic field in said selected region and operating said one or more magnetic field generators for generating said cancellation magnetic field.

29. A safety seat for use in a vehicle, comprising a system for cancellation or at least significant reduction of magnetic fields; the system comprises: one or more magnetic field generators configured to be positioned around a selected region of the safety seat, one or more sensors configured to provide sensing data on magnetic fields in at least a portion of said selected region, and a control system; the control system being operatively connectable to said one or more magnetic field generators and magnetic field sensors, and configured for: receiving said sensing data on the magnetic field in said selected region, processing the sensing data and determining one or more parameters of a cancellation magnetic field for cancelling or at least significantly reducing a magnitude of the magnetic field in said selected region and operating said one or more magnetic field generators for generating said cancellation magnetic field.

30. A method for reducing magnitude of magnetic field within a selected region, the method comprising: installing one or more magnetic field sensors and one or more magnetic field generators in vicinity of said selected region, collecting and processing sensing data on magnetic flux passing through said magnetic field sensors and operating said one or more magnetic field generators for generating cancellation magnetic field for cancelling or at least significantly reducing magnitude of magnetic field through said - 40 - selected region and operating said one or more magnetic field generators for generating said magnetic field cancellation pattern.

31. The method of claim 30, wherein said collecting sensing data on magnetic flux from said one or more magnetic field sensors and operating said one or more magnetic field generators for generating cancellation magnetic field pattern are performed simultaneously; said processing comprises determining pattern of sensed magnetic field, detected by said one or more magnetic field sensors, determining pattern of internally generated magnetic field generated by said one or more magnetic field generators, and subtracting said internally generated magnetic field from said sensed magnetic field, to thereby determine pattern of externally generated magnetic field.

32. The method of claim 30 or 31, wherein at least one of said one or more magnetic field sensors and one or more magnetic field generators are placed to be spatially overlapping each other forming a sensor-generator pair, thereby providing magnetic field cancellation that minimizes magnetic flux through said one or more magnetic field sensors.

33. The method of any one of claims 30 to 32, further comprising, installing at least one additional magnetic field generator, positioned at a selected distance to be spatially separated from a respective sensor-generator pair, thereby enabling minimizing magnetic field at a position between spatial location of said sensor-generator pair and said additional magnetic field generator.

34. The method of claim 30, wherein processing sensing data comprises determining a magnetic field pattern within said selected region generated by one of or more external sources, determining a pattern of cancellation magnetic field, and operating said one or more magnetic field generators for generating said pattern of cancellation magnetic field.

35. The method of claim 34, wherein at least one of said one or more magnetic field sensors and one or more magnetic field generators is a common magnetic field sensing and generating unit, the method comprises operating said at least one common magnetic field sensing and generating unit in time division duplex for sensing magnetic field flux therethrough in a first period of operation cycle, processing data on detected magnetic flux in a second period of operation cycle, and operating said one or more magnetic field generators for generating cancellation magnetic field in a third period of operation cycle.