Patent Publication Number: US-9837860-B2

Title: Wireless power transmission systems for elevators

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims priority to U.S. Provisional Patent Application No. 61/988,874, filed on May 5, 2014, the entire contents of which are incorporated herein by reference. 
    
    
     TECHNICAL FIELD 
     This disclosure relates to wireless power transfer. 
     BACKGROUND 
     Energy or power may be transferred wirelessly using a variety of known radiative, or far-field, and non-radiative, or near-field, techniques as detailed, for example, in commonly owned U.S. patent application Ser. No. 12/613,686, published on May 6, 2010 as US 2010/010909445 and entitled “Wireless Energy Transfer Systems,” in U.S. patent application Ser. No. 12/860,375, published on Dec. 9, 2010 as US 2010/0308939 and entitled “Integrated Resonator-Shield Structures,” in U.S. patent application Ser. No. 13/283,854, published on Oct. 4, 2012 as US 2012/0248887 and entitled “Multi-Resonator Wireless Energy Transfer for Sensors,” and in U.S. patent application Ser. No. 13/534,966, published on Jan. 2, 2014 as US 2014/0002012 and entitled “Wireless Energy Transfer for Rechargeable Batteries.” The entire contents of each of the foregoing references are incorporated by reference herein. 
     SUMMARY 
     Highly resonant wireless power transfer systems can include high quality factor resonators that may be driven to generate oscillating electromagnetic fields and that can interact with oscillating magnetic fields to generate currents and/or voltages in electronic circuits. That is, energy may be transferred wirelessly using oscillating magnetic fields. Resonators and electronics can include magnetic material that can be used to increase efficiency and coupling between two or more resonators by guiding the magnetic field generated by an induced current in a resonator. In applications, one or more resonators can be shaped to further enhance efficiency, coupling, and the like. 
     In a first aspect, the disclosure features wireless power transmission systems for an elevator that include at least two wireless power sources disposed at intervals along a wall of an elevator shaft and coupled to a power supply, and at least one wireless power receiving device configured to be mounted to an exterior of an elevator cab and to be coupled to a load onboard the elevator cab, where during operation, the at least two wireless power sources are configured to generate an oscillating magnetic field to transfer wireless energy to the at least one wireless power receiving device. 
     Embodiments of the systems can include any one or more of the following features. Lengths of the intervals between the at least two sources can be determined by at least one of an amount of power delivered to the elevator cab, a length of the elevator shaft, positions along the elevator shaft at which the elevator cab stops, and a speed with which the elevator cab travels along the elevator shaft. The load can include a battery. Lengths of the intervals between the at least two sources can be determined by a power storage capacity of the battery. During operation, the battery can be used to power at least one of the elevator cab, a communication system, a lighting system, an air conditioning system, and a control system. 
     The load can include at least one of: direct power to a translation mechanism of the elevator cab, a communication system of the elevator cab, a lighting system of the elevator cab, an air conditioning system of the elevator cab, and a control system of the elevator cab. 
     During operation, the transferred wireless energy can supplement another form of power delivered to the elevator cab. One of the at least two wireless power sources can be positioned at a location in the shaft where the elevator cab spends more time than at other positions within the shaft. During operation, wireless energy transferred from another one of the at least two wireless power sources can be used to top-off a battery of the elevator cab. 
     The systems can include at least one repeater, where during operation, the at least one repeater receives wireless energy from one of the at least two wireless power sources and transfers wireless energy to the at least one wireless power receiving device. 
     The systems can include a shield configured to be disposed between a metallic surface of the elevator cab and the at least one wireless power receiving device. The systems can include a shield disposed between a metallic surface of the elevator shaft and one of the at least two wireless power sources. 
     The systems can include a communication and control system coupled to at least one of the at least two wireless power sources. The communication and control system can be configured to control an amount of energy transferred from the at least one of the at least two wireless power sources. The communication and control system can be configured to activate the at least one of the at least two wireless power sources. 
     The systems can include a sensor positioned in proximity to one of the at least two wireless power sources. The sensor can include at least one of a line-of-sight sensor, a photoelectric sensor, and an infrared sensor. 
     The systems can include a voltage monitor coupled to the battery. During operation, a communication and control system of the at least one wireless power receiving device can be configured to return the elevator cab to a position proximate to one of the at least two wireless power sources when the voltage monitor indicates a low battery level. During operation, a communication and control system of the one of the at least two wireless power sources can be configured to control an amount of power transferred from the one of the at least two wireless power sources. 
     Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure belongs. Although methods and materials similar or equivalent to those described herein can be used in the practice or testing of the subject matter herein, suitable methods and materials are described below. All publications, patent applications, patents, and other references mentioned herein are incorporated by reference in their entirety. In case of conflict, the present specification, including definitions, will control. In addition, the materials, methods, and examples are illustrative only and not intended to be limiting. 
     The details of one or more embodiments are set forth in the accompanying drawings and the description below. Other features and advantages will be apparent from the description, drawings, and claims. 
    
    
     
       DESCRIPTION OF DRAWINGS 
         FIG. 1  is a schematic diagram showing an exemplary embodiment of a wireless power transmission system for an elevator. 
         FIG. 2  is a schematic diagram showing an exemplary embodiment of a wireless power transmission system for an elevator with one or more resonators. 
         FIG. 3  is a schematic diagram showing an exemplary embodiment of a wireless power transmission system for an elevator that includes shielding. 
         FIG. 4  is a schematic diagram showing an exemplary embodiment of a wireless power transmission system for an elevator including communication and control systems. 
     
    
    
     Like reference symbols in the various drawings indicate like elements. 
     DETAILED DESCRIPTION 
     Conventional elevator systems typically include heavy, lengthy cables that connect an elevator cab to a power source for delivery of operating power to the cab and various electrical systems therein. The cable is a source of considerable additional weight and potential failure, particularly for elevator systems that traverse a long elevator shaft. In addition, retro-fitting conventional elevators to introduce new capabilities—such as delivering additional control signals—can involve connecting additional cables to the elevator cab which extend along the length of the elevator shaft, resulting in additional weight and increasing further the possibility of operating failures. 
     This disclosure features wireless power transfer systems for elevators that allow operating power to be delivered wirelessly to an elevator, an elevator cab, and/or an elevator shaft without using cables or other direct connections for power transfer. The wireless power transfer systems can also transfer power to one or more batteries of the elevator system. The batteries can in turn provide operating power to the various sub-systems of the elevator. 
     The wireless power transfer systems disclosed herein can be installed or retro-fitted to existing elevator systems, thereby ensuring that existing, conventional elevator systems can be upgraded to take advantage of wireless power transfer. The wireless power transfer systems can also be directly integrated into elevator systems during manufacturing. 
       FIG. 1  shows an example embodiment of a wireless power transfer system for an elevator system including elevator  104  in elevator shaft  102 . One or more wireless power sources  106   a ,  106   b ,  106   c  are installed at intervals along an elevator shaft. Intervals between the one or more wireless power sources  106   a/b/c  may be equal or may be different. For example, intervals may be defined by the distance between floors of a building. In another example, intervals may be different as elevator cabs may be designated to certain ranges of floors of a building. In another example, an elevator cab may be configured to skip certain floors of a building, such as floors that correspond to service levels of a building. In yet another example, the height of floors of a building may not be uniform, such as when single-floor, loft-style, and multiple-floor apartments are part of the same residence building. The frequency of the intervals may be determined by a number of factors, including the amount of power delivered to the elevator, the length of the elevator shaft, positions along the shaft at which the elevator cab spends the most time, the speed with which the elevator travels along the shaft, and the capacity of the battery onboard the elevator cab. In some embodiments, a wireless power sources  106   a/b/c  can include a source resonator coupled to source electronics. The source can be coupled to a power supply such as a battery, AC mains, and/or a solar power source. 
     In certain embodiments, a wireless power capture device  108  is installed or integrated into the elevator cab as shown in  FIG. 1 . Wireless power capture device  108  can include a device resonator coupled to device electronics. The device can provide power to a load such as a battery or directly power an electronic device or electronic systems of an elevator cab such as, for example, the translation mechanism of the elevator cab (i.e., the mechanism that moves the cab within the elevator shaft), the communication systems, control systems, lighting, heating, air conditioning, and/or fans. In some embodiments, the captured power can be used to charge a battery onboard the elevator cab. The battery can be used to power the elevator cab or electronics within the elevator cab, such as, for example, communication systems, control systems, lighting, heating, air conditioning, and/or fans. In certain embodiments, wireless power delivery can be supplementary to the traction or other conventional methods of power delivery to the elevator. 
     For example, a wireless power source may be installed at a floor that the elevator spends the most time idling at, such as a lobby or 1 st  floor. The battery of the elevator can be continually charged at that position and the additional power sources installed at other floors or locations may provide power to “top-off” the battery of the elevator cab. In some embodiments, more power may be delivered at the idling location of the elevator cab compared to the other source locations along the elevator shaft. In some embodiments, wireless power sources can be placed close to one another along the elevator shaft to provide continuous or near-continuous wireless delivery of power to the elevator as it moves within the shaft. 
     In certain embodiments, a battery of the elevator can be a wirelessly rechargeable battery. For example, the battery itself can include one or more resonators and electronics to capture energy from the oscillating magnetic field generated by a wireless power source, to charge the battery. In some embodiments, a wirelessly rechargeable battery and/or one or more repeater resonators can be used to provide wireless power to various parts of the elevator. Repeaters that can be used in the elevator systems disclosed herein include “passive” repeaters featuring one or more resonators, and “active” repeaters featuring one or more resonators and electronic components (e.g., electronic circuits, electronic processors). 
     For example, as shown in  FIG. 2 , elevator  104  can be equipped with one or more resonators  203 . Any of resonators  203  can be a device resonator, a resonator coupled to one or more batteries, and/or a repeater resonator, to power the interior  210  of the cab, the doors  206  of the cab, etc. The interior of the cab can include electrical systems such as, but not limited to, lighting, heating, fans, air conditioning, speakers, communication devices, and controls. Power can be delivered to any one or more of the electrical systems via resonators  203 . 
     In some embodiments, a wireless power source may draw power from a power supply such as a generator and provide a “back-up” to a conventional system for powering elevator  104 . This can be beneficial during a power outage and/or when elevator  104  is operated during an emergency condition. 
       FIG. 3  shows an example embodiment of a wirelessly powered elevator  104  that includes one or more shielding materials  302 ,  306 . In general, an elevator and/or elevator shaft can contain lossy materials such as metals. When wireless power source  106  generates a magnetic field, the magnetic field induces eddy currents in the lossy materials, thereby decreasing the magnitude of the field and reducing the efficiency with which power is transferred from the wireless power source to wireless power capture device  108 . 
     A variety of different shielding materials can be used in an elevator system. For example, the shielding materials that are used can include magnetic materials such as ferrite, and/or conductive materials such as copper and/or aluminum. In some embodiments, the shielding material is installed between a resonator and the lossy material. For example, the shielding material  302  can be positioned between source resonator  106  and wall  304  of elevator shaft  102  in  FIG. 3 . Additionally, shielding material  306  can be positioned between the device resonator  108  and the back of the elevator  104 . In some embodiments, shielding materials may cover a portion, or all, of elevator  104  and/or elevator shaft  102 . 
       FIG. 4  shows an example embodiment of a wireless power system for an elevator that includes communication and control schemes to increase efficiency of wireless power transfer to an elevator system. A wireless power system can include communication and controls systems, including a computer and/or processor, to measure and/or receive information such as, but not limited to, the amount of time an elevator spends at each of several locations and the amount of power drawn by the elevator at each location. The wireless power system can in turn calibrate itself to provide power when and where it is needed most by the elevator system. 
     In some embodiments, the controls of the wireless power system of an elevator may be coupled to the control system of the elevator itself. As such, the efficiency of wireless power transfer may be maintained or increased by turning on specific wireless power sources. For example, if a user of the elevator indicates a floor to travel to (i.e. by pushing a floor button in the elevator), the floor information can be communicated to the one or more wireless power sources  106   a/b/c  along the elevator shaft  102 . Certain of the wireless power sources  106   a/b/c  can then “drop out”, or cease transferring power, if the elevator will not stop at the floors corresponding to those sources. 
     In certain embodiments, communication and control related circuitry  402   a/b/c/d  can be part of one or more of the wireless power source(s)  106   a/b/c  and wireless power receiving device(s)  108 . In some embodiments, a wireless power source (e.g.,  106   a/b/c ) in elevator shaft  102  can be “triggered” to transfer power as elevator  104  travels towards the source. For example, sensors  404   a - 404   f  can be used to detect elevator  104  within shaft  102 , and to transmit signals to circuitry  402   a/b/c/d  to activate appropriate wireless power sources. Sensors  402   a/b/c/d  can include, but are not limited to, line-of-sight sensors, photoelectric sensors, and/or infrared sensors. In certain embodiments, one or more of sensors  404   a - 404   f  can be positioned near the one or more sources  402   a/b/c/d  so that appropriate sources are triggered as elevator  104  moves through elevator shaft  102 . 
     In some embodiments, the voltage of the battery  406  onboard the elevator  104  may be monitored by a voltage monitor (not shown in  FIG. 4 ). For example, the voltage monitor can be coupled to the communication and control system  402   d  of elevator  104  and/or wireless power receiving device  108 . During operation, if the voltage of battery  406  decreases to less a threshold value, communication and control system  402   d  can direct elevator  104  return to a wireless energy source along the elevator shaft  102 . The voltage threshold may be pre-determined and/or changed depending on expected usage of elevator  104 . The voltage of battery  406  can be communicated to the mechanical control of the elevator  104  via a wired or wireless communication system and protocol. In certain embodiments, the voltage of the battery  406  can be communicated to any one or more of wireless power sources  402   a/b/c . This information can be used to adjust the amount of power transferred from each of the wireless power sources to wireless power receiving device  108  on elevator  104 . 
     Other Embodiments 
     While a number of embodiments have been described, other embodiments will be understood by one of ordinary skill in the art and are intended to fall within the scope of this disclosure, which is to be interpreted in the broadest sense allowable by law. For example, designs, methods, configurations of components, etc. related to transmitting wireless power have been described above along with various specific applications and examples thereof. Those skilled in the art will appreciate where the designs, components, configurations or components described herein can be used in combination, or interchangeably, and that the above description does not limit such interchangeability or combination of components to only that which is described herein. Accordingly, embodiments other than those expressly described are within the scope of the following claims. 
     All documents referred to herein are hereby incorporated by reference.