Abstract:
A method of operating an elevator system is presented. The method comprises controlling, using a controller, a plurality of components of the elevator system. The controlling comprises operating at least one of an internal power source, an elevator car, a drive unit, a power conversion device, and a brake. The method also comprises detecting, using the controller, when an external power source is unavailable; deactivating, using the controller, the power conversion device when an external power source is unavailable; and determining, using the controller, a mode of the elevator car. The mode includes at least one of a motoring mode and a near balance mode. The method further comprises connecting, using the controller, to an internal power source, when at least one of the motoring mode and the near balance mode is determined; and increasing, using the internal power source, voltage of the drive unit.

Description:
BACKGROUND 
       [0001]    The subject matter disclosed herein relates generally to the field of elevator systems, and specifically to a method and apparatus for bringing an elevator to a controlled stop when power from an external power source is unavailable. 
         [0002]    A typical elevator system includes a car and a counterweight disposed within a hoistway, a plurality of tension ropes that interconnect the car and counterweight, and a drive unit having a drive sheave engaged with the tension ropes to drive the car and the counterweight. The ropes, and thereby the car and counterweight, are driven by rotating the drive sheave. Traditionally, the drive unit and its associated equipment were housed in a separate machine room. 
         [0003]    Newer elevator systems have eliminated the need for a separate machine room by mounting the drive unit in the hoistway. These elevator systems are referred to as machine room-less systems. Traditionally, elevator systems have been dependent on an external power source for operation, which complicates operation in the event that the external power source is unavailable. 
       BRIEF SUMMARY 
       [0004]    According to one embodiment, a method of operating an elevator system is presented. The method comprises controlling, using a controller, a plurality of components of the elevator system. The controlling comprises operating at least one of an internal power source, an elevator car, a drive unit, a power conversion device, and a brake. The method also comprises detecting, using the controller, when an external power source is unavailable; deactivating, using the controller, the power conversion device when an external power source is unavailable; and determining, using the controller, a mode of the elevator car. The mode includes at least one of a motoring mode and a near balance mode. The method further comprises connecting, using the controller, to an internal power source, when at least one of the motoring mode and the near balance mode is determined; and increasing, using the internal power source, voltage of the drive unit. 
         [0005]    In addition to one or more of the features described above, or as an alternative, further embodiments of the method may include: determining, using the controller, a run profile of the elevator car; and operating, using the controller, the elevator car in response to the run profile determined. 
         [0006]    In addition to one or more of the features described above, or as an alternative, further embodiments of the method may include: determining, using the controller, a projected stop position and a projected stop velocity of the elevator car; and commanding, using the controller, the brake to stop the elevator car when the projected stop position is within a selected stop position range and the projected stop velocity is within a selected stop velocity range. 
         [0007]    In addition to one or more of the features described above, or as an alternative, further embodiments of the method may include: determining, using the controller, a projected stop position and a projected stop velocity of the elevator car; determining, using the controller, a run profile of the elevator car, when the projected stop position is not within a selected stop position range or the projected stop velocity is not within a selected stop velocity range; and operating, using the controller, the elevator car in response to the run profile determined. 
         [0008]    In addition to one or more of the features described above, or as an alternative, further embodiments of the method may include controlling, using a controller, a plurality of components of the elevator system. The controlling comprises operating at least one of an internal power source, an elevator car, a drive unit, a power conversion device, and a brake. The method may also include: detecting, using the controller, when an external power source is unavailable; deactivating, using the controller, the power conversion device when an external power source is unavailable; and determining, using the controller, a mode of the elevator car. The mode includes a regenerative mode. The method further includes determining, using the controller, a run profile of the elevator car when the regenerative mode is determined; and operating, using the controller, the elevator car in response to the run profile determined. 
         [0009]    In addition to one or more of the features described above, or as an alternative, further embodiments of the method may include: connecting, using the controller, to an internal power source, when the regenerative mode is detected; and charging, using the controller, the internal power source. 
         [0010]    In addition to one or more of the features described above, or as an alternative, further embodiments of the method may include: determining, using the controller, a projected stop position and a projected stop velocity of the elevator car; and commanding, using the controller, the brake to stop the elevator car when the projected stop position is within a selected stop position range and the projected stop velocity is within a selected stop velocity range. 
         [0011]    In addition to one or more of the features described above, or as an alternative, further embodiments of the method may include: determining, using the controller, a projected stop position and a projected stop velocity of the elevator car; and commanding, using the controller, the brake to stop the elevator car when the projected stop position is within a selected stop position range and the projected stop velocity is within a selected stop velocity range. 
         [0012]    In addition to one or more of the features described above, or as an alternative, further embodiments of the method may include: determining, using the controller, a projected stop position and a projected stop velocity of the elevator car; determining, using the controller, a run profile of the elevator car, when the projected stop position is not within a selected stop position range or the projected stop velocity is not within a selected stop velocity range; and operating, using the controller, the elevator car in response to the run profile determined. 
         [0013]    In addition to one or more of the features described above, or as an alternative, further embodiments of the method may include: determining, using the controller, a projected stop position and a projected stop velocity of the elevator car; determining, using the controller, a run profile of the elevator car, when the projected stop position is not within a selected stop position range or the projected stop velocity is not within a selected stop velocity range; and operating, using the controller, the elevator car in response to the run profile determined. 
         [0014]    According to another embodiment, an apparatus for operating an elevator system is presented. The apparatus comprising an internal power source; an elevator car; a drive unit; a power conversion device; a brake; and a controller to control a plurality of components of the elevator system. The controlling comprises operating at least one of the internal power source, the elevator car, the drive unit, the power conversion device, and the brake. The controller performs operations comprising: detecting when an external power source is unavailable, deactivating the power conversion device when an external power source is unavailable, and determining a mode of the elevator car. The mode includes at least one of a motoring mode, a near balance mode, and a regenerative mode. 
         [0015]    In addition to one or more of the features described above, or as an alternative, further embodiments of the apparatus may include: connecting to an internal power source, when at least one of the motoring mode and the near balance mode is determined; and increasing voltage of drive unit via the internal power source. 
         [0016]    In addition to one or more of the features described above, or as an alternative, further embodiments of the apparatus may include: determining a run profile of the elevator car; and operating the elevator car in response to the run profile determined. 
         [0017]    In addition to one or more of the features described above, or as an alternative, further embodiments of the apparatus may include: determining a run profile of the elevator car when the regenerative mode is determined; and operating the elevator car in response to the run profile determined. 
         [0018]    In addition to one or more of the features described above, or as an alternative, further embodiments of the apparatus may include: connecting to an internal power source, when the regenerative mode is detected; and charging the internal power source. 
         [0019]    In addition to one or more of the features described above, or as an alternative, further embodiments of the apparatus may include: determining a projected stop position and a projected stop velocity of the elevator car; and commanding the brake to stop the elevator car when the projected stop position is within a selected stop position range and the projected stop velocity is within a selected stop velocity range. 
         [0020]    In addition to one or more of the features described above, or as an alternative, further embodiments of the apparatus may include: determining a projected stop position and a projected stop velocity of the elevator car; and commanding the brake to stop the elevator car when the projected stop position is within a selected stop position range and the projected stop velocity is within a selected stop velocity range. 
         [0021]    In addition to one or more of the features described above, or as an alternative, further embodiments of the apparatus may include: determining a projected stop position and a projected stop velocity of the elevator car; and commanding the brake to stop the elevator car when the projected stop position is within a selected stop position range and the projected stop velocity is within a selected stop velocity range. 
         [0022]    In addition to one or more of the features described above, or as an alternative, further embodiments of the apparatus may include: determining a projected stop position and a projected stop velocity of the elevator car; determining a run profile of the elevator car, when the projected stop position is not within a selected stop position range or the projected stop velocity is not within a selected stop velocity range; and operating the elevator car in response to the run profile determined. 
         [0023]    In addition to one or more of the features described above, or as an alternative, further embodiments of the apparatus may include: determining a projected stop position and a projected stop velocity of the elevator car; determining a run profile of the elevator car, when the projected stop position is not within a selected stop position range or the projected stop velocity is not within a selected stop velocity range; and operating the elevator car in response to the run profile determined. 
         [0024]    Technical effects of embodiments of the present disclosure include an elevator system having a controller to bring an elevator car to a controlled stop when power from an external power source is unavailable. Further technical effects include that the controller detects the operating mode of the elevator car, switches to an internal power source as needed and adjusts the car velocity accordingly. 
         [0025]    The foregoing features and elements may be combined in various combinations without exclusivity, unless expressly indicated otherwise. These features and elements as well as the operation thereof will become more apparent in light of the following description and the accompanying drawings. It should be understood, however, that the following description and drawings are intended to be illustrative and explanatory in nature and non-limiting. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0026]    The foregoing and other features, and advantages of the disclosure are apparent from the following detailed description taken in conjunction with the accompanying drawings in which like elements are numbered alike in the several FIGURES: 
           [0027]      FIG. 1  illustrates a schematic view of an elevator system, in accordance with an embodiment of the disclosure; 
           [0028]      FIG. 2  is a block diagram of the elevator system of  FIG. 1 , in accordance with an embodiment of the disclosure; and 
           [0029]      FIG. 3  is a flow chart of an uninterrupted rescue operation of the elevator system of  FIG. 1 , in accordance with an embodiment of the disclosure. 
       
    
    
     DETAILED DESCRIPTION 
       [0030]    Referring now to  FIGS. 1 and 2 .  FIG. 1  shows a schematic view of an elevator system  10 , in accordance with an embodiment of the disclosure.  FIG. 2  shows a block diagram of the elevator system  10  of  FIG. 1 , in accordance with an embodiment of the disclosure. The elevator system  10  includes an elevator car  23  configured to move vertically upward and downward within a hoistway  50  along a plurality of car guide rails  60 . The elevator system  10  also includes a counterweight  28  operably connected to the elevator car  23  via a pulley system  26 . The counterweight  28  is configured to move vertically upward and downward within the hoistway  50 . The counterweight  28  moves in a direction generally opposite the movement of the elevator car  23 , as is known in conventional elevator systems. Movement of the counterweight  28  is guided by counterweight guide rails  70  mounted within the hoistway  50 . 
         [0031]    The elevator system  10  also includes an alternating current (AC) external power source  12 , such as an electrical main line (e.g., 230 volt, single phase). The AC power is provided from the AC external power source  12  to a switch panel  14 , which may include circuit breakers, meters, etc. From the switch panel  14 , the AC power may be provided directly to the drive unit  20  through the controller  30  or to an internal power source charger  16 , which converts the AC power to direct current (DC) power to charge an internal power source  18  that requires charging. For instance, an internal power source  18  that requires charging may be a battery, capacitor, or any other type of power storage device known to one of ordinary skill in the art. The battery may be a lead-acid, lithium ion or other type of battery. Alternatively, the internal power source  18  may not require charging from the AC external power source  12  and may be a device such as, for example a gas powered generator, solar cells, hydroelectric generator, wind turbine generator or similar power generation device. The internal power source  18  may power various components of the elevator system  10  when an external power source (e.g. AC external power source  12 ) is unavailable. If the internal power source  18  is generating an AC current, the AC power flows through the controller  30  to a drive unit  20 . The drive unit  20  contains a power conversion device  21  that includes an inverter and a converter. The power conversion device  21  may invert the DC power from the internal power source  18  to AC drive signals. The drive unit  20  drives a machine  22  to impart motion to the elevator car  23  via a traction sheave of the machine  22 . The AC drive signals may be multiphase (e.g., three-phase) drive signals for a three-phase motor in the machine  22 . The machine  22  also includes a brake  24  that can be activated to stop the machine  22  and elevator car  23 . 
         [0032]    The power conversion device  21  within the drive unit  20  converts DC power from internal power source  18  to AC power for powering various components of the elevator system  10  and may drive the machine  22  in motoring mode if necessary. Motoring mode refers to situations where the machine  22  is drawing current from the drive unit  20 . Motoring mode may occur when an empty elevator car is traveling downwards or a loaded elevator car is traveling upwards due to a weight imbalance between the elevator car  23  and the counterweight  28 . The power conversion device  21  of the drive unit  20  also converts AC power from machine  22  to DC power for optionally charging internal power source  18  when operating in regenerative mode. Regenerative mode refers to situations where the drive unit  20  receives current from the machine  22  (which acts as a generator) and supplies current back to the AC external power source  12  and/or the internal power source  18 . Regenerative mode may occur when an empty elevator car is traveling upwards or when a loaded elevator car is traveling downwards due to a weight imbalance between the elevator car  23  and the counterweight  28 . There is also a near balance mode when the weight of the elevator car  23  is about balanced with the weight of the counterweight  28 . Near balance mode operates similarly to motoring mode because the machine  22  is drawing current from the drive unit  20  to move the elevator car  23  out of the balance. As will be appreciated by those of skill in the art, motoring mode, regenerative mode, and near balance mode may occur in more than just the few examples described above and are within the scope of this disclosure. 
         [0033]    The controller  30  is responsible for controlling the operation of the elevator system  10 . The controller  30  may also determine a mode (motoring, regenerative, near balance) of the elevator car  23 . The controller  30  may determine the mode of the elevator car  23  using the car direction and the weight distribution between the elevator car  23  and the counterweight  28 . The modes may include at least one of a motoring mode, a near balance mode, and a regenerative mode, as previously described. The controller  30  may detect when the external power source  12  is unavailable. In the event the external power source  12  is unavailable, the controller  30  is responsible for determining a target floor and determining a run profile to meet that target floor. The controller  30  may adjust the velocity of the elevator car  23  to reach the target floor in response to the mode detected. The controller  30  may include a processor and an associated memory. The processor may be, but is not limited to, a single-processor or multi-processor system of any of a wide array of possible architectures, including field programmable gate array (FPGA), central processing unit (CPU), application specific integrated circuits (ASIC), digital signal processor (DSP) or graphics processing unit (GPU) hardware arranged homogenously or heterogeneously. The memory may be but is not limited to a random access memory (RAM), read only memory (ROM), or other electronic, optical, magnetic or any other computer readable medium. 
         [0034]    Referring now also to  FIG. 3 , which shows a block diagram of an uninterrupted rescue operation  300  of the elevator system  10  of  FIG. 1 , in accordance with an embodiment of the disclosure. The controller  30  may initiate the uninterrupted rescue operation  300  when the AC external power source  12  is unavailable at block  304 . Once the AC external power source  12  is unavailable, the controller  30  may deactivate the power conversion device  21  at block  306 . Next at block  308 , the controller  30  may determine the mode of the elevator car  23 . The mode may include at least one of a motoring mode, a near balance mode, and a regenerative mode, as described earlier. 
         [0035]    If at least one of the motoring mode and the near balance mode is determined, the controller may then connect to the internal power source  18  at block  310  and increase the voltage of the drive unit  20  via the internal power source  18  at block  312 . The internal power source  18  may be used to power a plurality of components of the elevator system  10 . Advantageously, depending on the size of the internal power source  18  this voltage increase may be strong enough to power the motoring of the elevator car  23  or may be just enough to supply power to various safety equipment such as for example brakes  24 , safety chain, and communication sensors. 
         [0036]    At block  308 , if regenerative mode is detected the controller may use the electrical power generated by the elevator system  10  in regenerative mode to power a plurality of components of the elevator system  10 . Additionally, if regenerative mode is detected, then the controller may also connect to the internal power source  18  to recharge the internal power source  18  at block  311 . 
         [0037]    Next, as shown in  FIG. 3 , the motoring and near balance path will converge with the regenerative path at block  314 , where the controller  30  dictates a run profile to a target floor. The process of dictating a run profile may include determining a run profile and operating the elevator car in response to the run profile determined. The run profile dictates a position, speed, and/or deceleration of the elevator car  23  to transition the elevator car  23  to a target floor. Then at block  316  the controller  30  will determine a projected stop position and a projected stop velocity of the elevator car  23  and drop the brake  24  at block  318  when the projected stop position is within a selected stop position range and the projected stop velocity is within a selected stop velocity range. If the projected stop position is not within a selected stop position range or the projected stop velocity is not within a selected stop velocity range the controller  30  will return back to block  314  to dictate a new run profile. The selected stop position range may refer to a safe location for rescue and/or egress from the elevator car  23  at a target floor. The selected stop velocity range may refer to a safe velocity of the elevator car  23  to approach the selected stop position location. 
         [0038]    Advantageously, in the event of the external power becomes unavailable at block  304 , the power is seamlessly transitioned from the AC external power source  12  to the internal power source  18  or in the case of regenerative mode, the power may be supplied by the elevator system  10  itself. This seamless transition allows the elevator car  23  to reach the target floor without interruption in all modes and also conserve internal power source  18  energy by only using it for certain modes. 
         [0039]    The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting. While the description has been presented for purposes of illustration and description, it is not intended to be exhaustive or limited to embodiments in the form disclosed. Many modifications, variations, alterations, substitutions or equivalent arrangement not hereto described will be apparent to those of ordinary skill in the art without departing from the scope of the disclosure. Additionally, while the various embodiments have been described, it is to be understood that aspects may include only some of the described embodiments. Accordingly, the disclosure is not to be seen as limited by the foregoing description, but is only limited by the scope of the appended claims.