Elevator car power supply

A ropeless elevator system includes a vertically extending first lane, a vertically extending second lane, and a transfer station extending between and in communication with the first and second lanes. An elevator car is disposed in and is constructed and arranged to move through the transfer station and the first and second lanes. A propulsion system of the elevator system propels the elevator car through at least the first and second lanes and carries a supplemental DC energy storage device for providing supplemental energy to the elevator car during normal operation. A wireless power transfer system of the elevator system is configured to periodically charge the DC energy storage device.

BACKGROUND

The present disclosure relates to elevator systems, and more particularly to supplemental energy storage devices in an elevator car of the elevator system.

Self-propelled elevator systems, also referred to as ropeless elevator systems, are useful in certain applications (e.g., high rise buildings) where the mass of the ropes for a roped system is prohibitive and/or there is a need for multiple elevator cars in a single hoistway. Elevator cars typically need power for ventilation, lighting systems, control units, communication units and to recharge batteries installed, for example, on an elevator car controller. Moreover, elevator cars may require back-up systems in case of a power failure. Existing systems use moving cables or current collectors/sliders to connect a moving elevator car with power lines distributed along the elevator hoistway.

SUMMARY

A ropeless elevator system according to one, non-limiting, embodiment of the present disclosure includes a vertically extending first lane; a vertically extending second lane; a transfer station extending between and in communication with the first and second lanes; a first elevator car disposed in and arranged to move through the transfer station and the first and second lanes; a propulsion system for propelling the first elevator car through at least the first and second lanes; a first DC energy storage device carried by the first elevator car and configured to provide supplemental power to the elevator car during normal operation; and a wireless power transfer system configured to periodically charge the first DC energy storage device.

Additionally to the foregoing embodiment, the first DC energy storage device includes a plurality of batteries and a circuit for cell balancing.

In the alternative or additionally thereto, in the foregoing embodiment, the plurality of batteries are lithium batteries.

In the alternative or additionally thereto, in the foregoing embodiment, the ropeless elevator system includes a power source; and a conductor at least partially in the transfer station and extending from the power source and configured to releasably mate with the first DC energy storage device for charging when the first elevator car is in the transfer station.

In the alternative or additionally thereto, in the foregoing embodiment, the first DC energy storage device is a supercapacitor.

In the alternative or additionally thereto, in the foregoing embodiment, the ropeless elevator system includes a second DC energy storage device configured to provide power to the first elevator car during power failure.

In the alternative or additionally thereto, in the foregoing embodiment, the wireless power transfer system is configured to charge the first DC energy storage device only when needed to preserve the life of the first DC energy storage device.

In the alternative or additionally thereto, in the foregoing embodiment, the first DC energy storage device is configured to provide power to at least one of the second DC energy storage device, a ventilation unit, a lighting system, a control unit, a communication unit, and a braking system of the elevator car.

In the alternative or additionally thereto, in the foregoing embodiment, the first DC energy storage device is configured to provide power to at least one of a ventilation unit, a lighting system, a control unit, a communication unit, a door actuator, and a braking system of the first elevator car.

In the alternative or additionally thereto, in the foregoing embodiment, the ropeless elevator system includes a service zone in communication with at least one of the transfer station, the first lane and the second lane, and being constructed and arranged to house the first elevator car for service; a power source; and a conductor at least partially disposed in the service zone, extending from the power source, and configured to releasably mate with the first DC energy storage device for charging when the first elevator car is in the service zone.

In the alternative or additionally thereto, in the foregoing embodiment, the first DC energy storage device is constructed and arranged to be removable and replaced with a charged DC energy storage device when the first elevator car is in the transfer station.

In the alternative or additionally thereto, in the foregoing embodiment, the ropeless elevator system includes a second elevator car disposed in and constructed and arranged to move through the transfer station and the first and second lanes; and a second DC energy storage device carried by the second elevator car that varies in size from the first DC energy storage device.

A method of maintaining a DC energy storage device of an elevator car according to another, non-limiting, embodiment includes periodically charging the DC energy storage device via a wireless power transfer system when the elevator car is in normal use; and charging the DC energy storage device via a conductor and power source when the elevator car is not in normal use.

Additionally to the foregoing embodiment, the DC energy storage device is a supplemental storage device.

In the alternative or additionally thereto, in the foregoing embodiment, the elevator car is in the transfer station when charging the DC energy storage device via the conductor.

In the alternative or additionally thereto, in the foregoing embodiment, the method includes balancing cells of a plurality of batteries of the DC energy storage device via a circuit of the DC energy storage device.

DETAILED DESCRIPTION

The following patent applications assigned to the same assignee and filed on the same day as the present disclosure are herein incorporated by reference in their entirety Nos. 62/209,818, 62/209,814, 62/207,761, 62/209,775.

FIG. 1depicts a self-propelled or ropeless elevator system20in an exemplary embodiment that may be used in a structure or building22having multiple levels or floors24. Elevator system20includes a hoistway26having boundaries defined by the structure22and at least one car28adapted to travel in the hoistway26. The hoistway26may include, for example, three lanes30,32,34each extending along a respective central axis35with any number of cars28traveling in any one lane and in any number of travel directions (e.g., up and down). For example and as illustrated, the cars28in lanes30,34, may travel in an up direction and the cars28in lane32may travel in a down direction.

Above the top floor24may be an upper transfer station36that facilitates horizontal motion to elevator cars28for moving the cars between lanes30,32,34. Below the first floor24may be a lower transfer station38that facilitates horizontal motion to elevator cars28for moving the cars between lanes30,32,34. It is understood that the upper and lower transfer stations36,38may be respectively located at the top and first floors24rather than above and below the top and first floors, or may be located at any intermediate floor. Yet further, the elevator system20may include one or more intermediate transfer stations (not illustrated) located vertically between and similar to the upper and lower transfer stations36,38.

Referring toFIGS. 1 through 3, cars28are propelled using a linear propulsion system40having at least one, fixed, primary portion42(e.g., two illustrated inFIG. 2mounted on opposite sides of the car28), moving secondary portions44(e.g., two illustrated inFIG. 2mounted on opposite sides of the car28), and a control system46. The primary portion42includes a plurality of windings or coils48mounted at one or both sides of the lanes30,32,34in the hoistway26. Each secondary portion44includes two rows of opposing permanent magnets50A,50B mounted to the car28. Primary portion42is supplied with drive signals from the control system46to generate a magnetic flux that imparts a force on the secondary portions44to control movement of the cars28in their respective lanes30,32,34(e.g., moving up, down, or holding still). The plurality of coils48of the primary portion42are generally located between and spaced from the opposing rows of permanent magnets50A,50B. It is contemplated and understood that any number of secondary portions44may be mounted to the car28, and any number of primary portions42may be associated with the secondary portions44in any number of configurations.

Referring toFIG. 3, the control system46may include power sources52, drives54, buses56and a controller58. The power sources52are electrically coupled to the drives54via the buses56. In one non-limiting example, the power sources52may be direct current (DC) power sources. DC power sources52may be implemented using storage devices (e.g., batteries, capacitors), and may be active devices that condition power from another source (e.g., rectifiers). The drives54may receive DC power from the buses56and may provide drive signals to the primary portions42of the linear propulsion system40. Each drive54may be a converter that converts DC power from bus56to a multiphase (e.g., three phase) drive signal provided to a respective section of the primary portions42. The primary portion42is divided into a plurality of modules or sections, with each section associated with a respective drive54.

The controller58provides control signals to each of the drives54to control generation of the drive signals. Controller58may use pulse width modulation (PWM) control signals to control generation of the drive signals by drives54. Controller58may be implemented using a processor-based device programmed to generate the control signals. The controller58may also be part of an elevator control system or elevator management system. Elements of the control system46may be implemented in a single, integrated module, and/or be distributed along the hoistway26.

Referring toFIG. 4, a wireless power transfer system60of the elevator system20may be used to power loads61in or on the elevator car28. The power transfer system60may be an integral part of the control system46thereby sharing various components such as the controller58, buses56, power source52and portions of the linear propulsion system40such as the primary portion42and other components. Alternatively, the wireless power transfer system60may generally be independent of the control system46and/or linear propulsion system40. The power loads61may be alternating current (AC) loads utilizing a traditional power frequency such as, for example, about 60 Hz. Alternatively, or in addition thereto, the loads61may include direct current (DC) loads.

The wireless power transfer system60may include a power source62, a converter64that may be a high frequency converter, at least one conductor66for transferring power (e.g., high frequency power) from the converter64, a plurality of switches68, and a plurality of primary resonant coils70that may generally be the primary portion42. Each one of the primary resonant coils70are associated with a respective one of the plurality of switches68. The power transfer system60may further include a controller72that may be part of the controller58. The controller72may be configured to selectively and sequentially place and/or maintain the switches68in an off position (i.e., circuit open) and/or in an on position (i.e., circuit closed). The power source62may be the power source52and may further be of a DC or of an AC type with any frequency (i.e. low or high).

The converter64may be configured to convert the power outputted by the power source62to a high frequency power for the controlled and sequential energization of the primary resonant coils70by transmitting the high frequency power through the conductors66. More specifically, if the power source62is a DC power source, the converter64may convert the DC power to an AC power and at a prescribed high frequency. If the power source62is an AC power source with, for example, a low frequency such as 60 Hz, the converter64may increase the frequency to a desired high frequency value. For the present disclosure, a desired high frequency may fall within a range of about 1 kHz to 1 MHz, and preferably within a range of about 250 kHz to 300 kHz.

The wireless power transfer system60may further include components generally in or carried by the elevator car28. Such components may include a secondary resonant coil74configured to induce a current when an energized primary resonant coil70is proximate thereto, a resonant component76that may be active and/or passive, a power converter78, and an energy storage device80that may be utilized to power the DC loads61. The secondary resonant coil74may induce a current when the coil is proximate to an energized primary resonant coil74. The primary resonant coil70is energized when the respective switch68is closed based on the proximity of the elevator car28and secondary resonant coil74.

Each switch68may be controlled by the controller72over pathway81that may be hard-wired or wireless. Alternatively, or some combination thereof, the switches68may be smart switches each including a sensor83that senses a parameter indicative of the proximity of the secondary resonant coil74. For example, the sensor83may be an inductance sensor configured to sense a change of inductance across the associated primary resonant coil70indicative of a proximate location of the secondary resonant coil74. Alternatively, the sensor83may be a capacitance sensor configured to sense a change of capacitance across the associated primary resonant coil70indicative of a proximate location of the secondary resonant coil74. In another embodiment, the controller72may assume limited control and the switches68may still be smart switches. For example, the controller72may control the duration that a given switch remains closed; however, the switches are ‘smart’ in the sense that they may be configured to move to the closed position without the controller instruction to do so.

The AC voltage induced across the secondary resonant coil74is generally at the high frequency of the primary resonant coil70. The ability to energize the primary resonant coils70with the high frequency power (i.e., as oppose to low frequency) may optimize the efficiency of induced power transfer from the primary resonant coil70to the secondary resonant coil74. Moreover, the high frequency power generally facilitates the reduction in size of many system components such as the coils70,74, the resonant component76and the converter78amongst others. Reducing the size of components improves packaging of the system and may reduce elevator car28weight. The international patent application WO 2014/189492 published under the Patent Cooperation Treaty on Nov. 27, 2014, filed on May 21, 2013, and assigned to Otis Elevator Company of Farmington, Conn., is herein incorporated by reference in its entirety.

The resonant component76may be passive or active. As a passive resonant component76, the component is generally a capacitor and capable of storing AC power. As an active resonant component76, the component76is configured to mitigate the effects of a weak or variable coupling factor (i.e., varies when the secondary resonant coil74passes between primary resonant coils70). That is, the resonant component76may function to level-out the output current and voltage from the secondary resonant coil74.

The power converter78is configured to receive high frequency power from the resonant component76. The converter78may reduce the high frequency power to a low frequency power (e.g., 60 Hz or other) that is compatible with AC loads61in the elevator car28. The converter78may further function to convert the high frequency power to DC power, which is then stored in the energy storage device80. An example of an energy storage device may be a type of battery.

Referring toFIG. 5, the elevator system20further includes a second energy storage device82that may, as one non-limiting example, provide supplemental or secondary power to the loads61of the elevator car28when the charging circuits are not sufficient. Storage device82may include a plurality of batteries84and a circuit86for balancing energy between cells. The batteries84may be of a lithium type or other type characterized by high capacity, high energy density and a short charging time. Alternatively, the storage device82may include supercapacitors with a high energy capacity capable of supplementing any deficiency in energy during normal operation.

The loads61relative to the second energy storage device82may include the first energy storage device80, a ventilation unit, a lighting system, a control unit, a communication unit, door actuators, an elevator car braking system, and other loads. The loads61may require AC or DC power. During a power outage scenario, some loads61may obtain power from the storage device80that, in-turn, may receive limited supplemental power from the storage device82. Alternatively or in addition thereto, some loads61may receive DC power directly from the supplemental energy storage device82. For loads61requiring DC power, the storage device80and/or the supplemental energy storage device82may transmit DC power to an inverter88that outputs AC power at a desired frequency.

During normal elevator car28operation, the loads61may not draw power from the back-up energy storage device82, and instead, may draw power as previously described. The supplemental energy storage device82may maintain a minimal level of charge so as not to limit the life of the device via periodic charging by the wireless power transfer system60and/or as dictated by power management algorithm(s) conducted by, for example, the controller58. As best shown inFIG. 6, additional or full charging of the supplemental energy storage device82may be facilitated while the elevator car28is in the transfer station38(i.e., not normal operation). That is, when the elevator car28is in the transfer station38for a known duration, the time needed to fully charge the supplemental energy storage device82may be realized. Such charging may be accomplished by drawing power from a power source90, over a conductor or cable92, and to the device82. The cable92may be at least partially in the transfer station38and is capable of being connected and disconnected from the device82(e.g., a plug connection). It is further contemplated and understood, that re-charging of the energy storage device82may be conducted at any previously designated floor24setup with a cable92, and when the car28is stopped for the necessary period of time to perform the recharging operation.

The supplemental energy storage device82may also be charged utilizing the power source90and a cable92from a service zone94location having boundaries generally defined by the structure22and communicating with at least one of the transfer stations36,38and lanes30,32,34. It is further contemplated and understood that the storage device82or batteries84may simply be interchanged while the elevator car28resides in the transfer station38.

Although the present disclosure illustrates one example of a linear motor and one example of a wireless power transfer system60, the supplemental energy storage device82, and method of charging, may be applicable to any variety of ropeless elevator systems having any number of different means to wirelessly transfer power to the elevator car during normal operation. Furthermore, the energy storage devices82may be of different sizes from one elevator car28to the next of the same elevator system20. For example, elevator cars that are designated to perform specific and/or special tasks may require a different energy storage device size (i.e. amount of energy storage) than another car.

While the present disclosure is described with reference to exemplary embodiments, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted without departing from the spirit and scope of the present disclosure. In addition, various modifications may be applied to adapt the teachings of the present disclosure to particular situations, applications, and/or materials, without departing from the essential scope thereof. The present disclosure is thus not limited to the particular examples disclosed herein, but includes all embodiments falling within the scope of the appended claims.