Abstract:
Embodiments are directed to recovering energy associated with the operation of an elevator, by: determining, by a processing device, a battery charging current, estimating a state of charge (SoC) of at least one battery based on charging current acceptance capability, and causing, by the processing device, a charging of the at least one battery to within a threshold amount of 100% of SoC to recover energy associated with elevator operation.

Description:
BACKGROUND 
       [0001]    In a given elevator system or environment, one or more sources may be used to provide power. For example,  FIG. 1A  shows an architecture or circuit  100  for an elevator system. The architecture  100  may include a battery  102  serving as a source of power for a motor  104 , such as a permanent-magnet synchronous motor (PMSM). An inverter  106 , denoted by the boxed components in  FIG. 1A , may be used to generate currents for the motor  104 . 
         [0002]    The battery  102  may be a lead acid battery. The battery  102  may be charged by a charger  108 . In a typical environment or application, the battery  102  may be slightly overcharged to maintain it at 100% of state of charge (SoC), increasing the standby power demand and degrading the energy efficiency of the system  100  during standby 
         [0003]    As the elevator operates, regenerative energy may be generated. Due to the battery  102  having been charged to (nearly) 100% SoC, a dynamic braking resistor (DBR)  110  and/or a dynamic braking transistor (DBT)  112  may be used to consume the regenerative energy. In this manner, most of the elevator energy is wasted, degrading the running energy efficiency. Performance is adversely affected by this configuration. 
       BRIEF SUMMARY 
       [0004]    An embodiment is directed to a method for recovering energy associated with the operation of an elevator, comprising: determining, by a processing device, a battery charging current, estimating a state of charge (SoC) of at least one battery based on charging current acceptance capability, and causing, by the processing device, a charging of the at least one battery to within a threshold amount of 100% of SoC to recover energy associated with elevator operation. 
         [0005]    An embodiment is directed to an apparatus comprising: at least one processor, and memory having instructions stored thereon that, when executed, cause the apparatus to: determine that it has been greater than a first threshold amount of time since an elevator was last run, cause a charger to be turned on to charge a battery of the elevator, setting a charging voltage according to at least one of battery temperature and ambient temperature, determine that it has been greater than a second threshold amount of time since the elevator was last run and application of the charging voltage, determine that a current associated with the charger is greater than a first threshold current based on one or more battery characteristics, and cause the charger to be maintained turned on to charge the battery. 
         [0006]    An embodiment is directed to a method comprising: determining that an elevator has not been operated for an amount of time greater than a first threshold, determining a temperature associated with a battery of the elevator based on applying a testing charging voltage to the battery via a charger, wherein a value of the charging voltage is based on the temperature, determining that it has been greater than a second threshold amount of time since the elevator was last run and application of charging voltage, determining that a current associated with the charger is greater than a first threshold current and maintaining the testing voltage turned on as charging voltage, wherein a value of the charging voltage is based on the temperature, determining that the elevator has not been operated for an amount of time greater than the second threshold, determining that the current associated with the charger is less than a second threshold current, and removing the charging voltage from the battery. 
         [0007]    Additional embodiments are described below. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0008]    The present disclosure is illustrated by way of example and not limited in the accompanying figures in which like reference numerals indicate similar elements. 
           [0009]      FIG. 1A  illustrates a power architecture in accordance with the prior art; 
           [0010]      FIG. 1B  is a block diagram of components of an elevator system in an exemplary embodiment; 
           [0011]      FIG. 2  illustrates a flow chart of an exemplary algorithm; and 
           [0012]      FIG. 3  illustrates a flow chart of an exemplary method. 
       
    
    
     DETAILED DESCRIPTION 
       [0013]    It is noted that various connections are set forth between elements in the following description and in the drawings (the contents of which are included in this disclosure by way of reference). It is noted that these connections in general and, unless specified otherwise, may be direct or indirect and that this specification is not intended to be limiting in this respect. In this respect, a coupling between entities may refer to either a direct or an indirect connection. 
         [0014]    Exemplary embodiments of apparatuses, systems and methods are described for accepting or delivering power or energy rapidly. In some embodiments, devices used to accept/deliver power or energy may act in a so-called peak shaving mode, enabling the devices to be as small as possible. Accordingly, device cost may be minimized. In some other embodiments of apparatuses, the component (e.g. ultra-capacitors) able to accept or deliver energy rapidly is directly connected with drive DC-link, accordingly device cost may be minimized due to the electrical topology itself. 
         [0015]      FIG. 1B  is a block diagram of components of an elevator system  10  in an exemplary embodiment. The various entities shown in  FIG. 1B  may be arranged in any order or sequence, and the system  10  is merely one example of such an arrangement. For example, while the arrangement of  FIG. 1B  shows a battery charger  16  and battery  18  effectively in series with an AC power source  12 , in some embodiments the battery charger  16  and/or the battery  18  may lie in parallel with the AC power source  12 . 
         [0016]    Elevator system  10  includes the source of AC power  12 , such as an electrical main line. The AC power  12  is provided to a controller  14 , which may include circuit breakers, meters, controllers, etc. From the controller  14 , AC power is provided to the battery charger  16 , which may convert the AC power to DC power to charge the battery  18 . Battery  18  may be a lead-acid battery or other type of battery or combination of different types of batteries and ultra-capacitors. Battery  18  may power a drive unit  20 . Drive unit  20  may include a control circuit board and a power circuit board. The power circuit board may convert DC power from battery  18  to AC drive signals, which drive a machine  22 . The AC drive signals may be multiphase (e.g., three-phase) drive signals for a three-phase motor in machine  22 . 
         [0017]    The charger  16  may include one or more processors  34 , and memory  36  having instructions stored thereon that, when executed, cause the charger  16  or the system  10  to perform one or more methodological acts as described herein. In some embodiments, the processors  34  and/or memory  36  may be located in another entity, such as a controller (e.g., controller  14 ). 
         [0018]    In some embodiments, the charger  16  may provide for a buffer with respect to a state of charge (SoC) on the battery  18 , such that the battery can accept charge resulting from operation of the elevator (e.g., regenerative energy). In other words, and as described further below, the charger  16  may ensure that at various points in time the battery  18  is charged to a level or value that is less than 100% SoC, such that the battery  18  can subsequently accept additional charge based on the operation of the elevator. In some embodiments, SoC detection may be performed by one or more other entities, such as a logic board or drive. 
         [0019]    As part of one or more charging algorithms, potentially executed by the controller  14  or the charger  16 , SoC may be determined or measured during periods when the elevator is idle or not in use in order to avoid the impact from fluctuations that are characteristic of operating the elevator. In some instances, the battery  18  may stabilize before an accurate reading is obtained. 
         [0020]    In some embodiments, the controller  14  may cause the battery  18  to be charged to (approximately) 100% SoC periodically (e.g. monthly). Such charging may be used to help maintain battery state of health in terms of nominal capacity over long periods of time (e.g., years), avoiding a typical memory-effect of lead acid batteries. The battery  18  may be charged to approximately 100% SoC in order to prolong battery life 
         [0021]    Turning now to  FIG. 2 , a flow chart of an exemplary algorithm  200  is shown. The algorithm  200  may be used to provide for intelligent or smart charging of a battery (e.g., battery  18 ) with SoC detection. 
         [0022]    Blocks  202 - 208  may correspond to inputs to the algorithm  200 . For example, block  202  may correspond to a condition or confirmation that an elevator car is not running. Such a condition/confirmation may be used to ensure stable conditions during a SoC test, and may be used to achieve a reliable SoC estimation of a battery that is loaded by an intermittent load, typical of an elevator application. 
         [0023]    Block  204  may correspond to a determination of a temperature of a battery. Knowledge of the battery temperature may be used to adjust a testing and charging voltage while keeping or maintaining current thresholds insensitive to battery temperature and at the same time improving battery life and performance, both affected by battery cell temperature. 
         [0024]    Block  206  may correspond to a determination of a battery size (e.g., 24/38 Amp hours (Ah)). Knowledge of the battery size and characteristics may be used to select one or more appropriate current thresholds. 
         [0025]    Block  208  may correspond to a determination of the parasitic current that can affect the reliability of the SoC detection with a close circuit configuration. The parasitic current may supply the system  100  during standby. The parasitic current may be subtracted from a measured current during SoC testing to improve estimation accuracy. 
         [0026]    Based on the determination of the charging current in block  210 , the battery SoC may be estimated by comparing measured current and proper thresholds. Switching on or off the battery charge, SoC may be set at 70-80% as provided in block  212 . Operating at a SoC that is less than 100% may provide for greater charging efficiency relative to operating at 100% SoC. 
         [0027]    Turning now to  FIG. 3 , a flow chart of an exemplary method  300  is shown. The method  300  may be used to provide for intelligent or smart charging of a battery (e.g., battery  18 ) with SoC detection. In some embodiments, one or more aspects of the algorithm  200  of  FIG. 2  may be incorporated into the method  300  of  FIG. 3 , or vice versa. 
         [0028]    Block  302  may correspond to a starting point/operation for the method  300 . In block  302 , battery charge may be off. A low floating voltage of, e.g., 50.5 Volts (2.10V per cell) may be associated with a battery (e.g., battery  18 ) to maintain the SoC around 70-80% during standby phase. From block  302 , flow may proceed to block  304 . 
         [0029]    In block  304 , a determination may be made whether the time since the last elevator run is greater than a threshold (e.g., 60 minutes). If so (e.g., the “yes” path is taken out of block  304 ), flow may proceed from block  304  to block  306 . Otherwise (e.g., the “no” path is taken out of block  304 ), flow may proceed from block  304  to block  302 . The determination of block  304  may be used to ensure stability with respect to the SoC test that is performed as part of the method  300 . A sufficient relaxation time may be used to stabilize battery chemistry of the battery, like lead acid. 
         [0030]    In block  306 , a charging voltage may be applied by the charger (e.g., charger  16 ) to a battery (e.g., battery  18  of  FIG. 1B ). The charging voltage may be a function of temperature, which may correspond to ambient temperature and/or the temperature of the battery. For example, at 20° C., the charging voltage may be applied at 54.6 Volts. An adjustment of plus-or-minus 0.072 Volts/° C. may be made, where a higher temperature leads to a lower applied voltage. From block  306 , flow may proceed to block  308 . 
         [0031]    In block  308 , a determination may be made whether it has been less than some amount of time (e.g., approximately 720 hours or 30 days) from a so-called “complete charge cycle” where the battery is fully charged to (approximately) 100% SoC. If so (e.g., the “yes” path is taken out of block  308 ), flow may proceed from block  308  to block  310 . Otherwise (e.g., the “no” path is taken out of block  308 ), flow may proceed from block  308  to block  352 . 
         [0032]    In conjunction with the flow from block  308  to block  310 , system power may be turned on (block  312 ). In block  310 , a determination may be made whether it has been greater than some amount of time (e.g., 10 minutes) since the last run and application of charging voltage ( 306 ). If so (e.g., the “yes” path is taken out of block  310 ), flow may proceed from block  310  to block  314 . Otherwise (e.g., the “no” path is taken out of block  310 ), flow may remain at block  310 . 
         [0033]    In block  314 , a determination may be made whether the current output from the charger is greater than a threshold, where the threshold may correspond to, e.g., 70% SoC. If so (e.g., the “yes” path is taken out of block  314 ), flow may proceed from block  314  to block  316 . Otherwise (e.g., the “no” path is taken out of block  314 ), flow may proceed from block  314  to block  302 . 
         [0034]    In block  316 , the recharge remains switched on. As part of block  316 , a monitoring (e.g., continuous monitoring) of the charge current may be provided. From block  316 , flow may proceed to block  311 . 
         [0035]    In block  311 , a determination may be made whether it has been greater than some amount of time (e.g., 10 minutes) since the last run. If so (e.g., the “yes” path is taken out of block  311 ), flow may proceed from block  311  to block  362 . Otherwise (e.g., the “no” path is taken out of block  311 ), flow may remain at block  311 . The determination of block  311  may be performed in order to provide a sufficient relaxation time before reading charging current. 
         [0036]    In block  362  a determination may be made whether the charge current is less than a threshold, where the threshold may correspond to, e.g., 80% SoC. If so (e.g., the “yes” path is taken out of block  362 ), flow may proceed from block  362  to block  302 . Otherwise (e.g., the “no” path is taken out of block  362 ), flow may proceed from block  362  to block  364 . The determination of block  362  may used to verify that the battery is charged enough to trigger the charge off. 
         [0037]    In block  364 , a determination may be made whether the charger has been on for a period of time greater than a threshold (e.g., approximately 24 hours or 1 day). The threshold may be selected to satisfy one or more safety requirements or parameters. In some embodiments, the threshold may be specified as a current associated with a charge of approximately 95% or 100%. If the determination of block  364  is answered in the affirmative (e.g., the “yes” path is taken out of block  364 ), flow may proceed from block  364  to block  302 . Otherwise (e.g., the “no” path is taken out of block  364 ), flow may proceed from block  364  to block  316 . 
         [0038]    In block  352 , the charger voltage may be remain on. Flow may proceed from block  352  to block  354 . 
         [0039]    In block  354 , a determination may be made whether the charger has been on for a period of time greater than a threshold (e.g., 24 hours or 1 day). If so (e.g., the “yes” path is taken out of block  354 ), flow may proceed from block  354  to block  302 . Otherwise (e.g., the “no” path is taken out of block  354 ), flow may proceed from block  354  to block  352 . The determination of block  354  may be used to avoid any memory-effect as described above. 
         [0040]    The values described above in connection with  FIGS. 2 and 3  are merely illustrative. One skilled in the art would appreciate that the values used may be modified without departing from the scope and spirit of this disclosure. Moreover, the blocks or operations may execute in an order or sequence different from what is shown in  FIGS. 2 and 3 . In some embodiments, one or more of the blocks (or a portion thereof) may be optional. In some embodiments, additional blocks or operations not shown may be included. 
         [0041]    In some embodiments various functions or acts may take place at a given location and/or in connection with the operation of one or more apparatuses, systems, or devices. For example, in some embodiments, a portion of a given function or act may be performed at a first device or location, and the remainder of the function or act may be performed at one or more additional devices or locations. 
         [0042]    Embodiments may be implemented using one or more technologies. In some embodiments, an apparatus or system may include one or more processors, and memory having instructions stored thereon that, when executed by the one or more processors, cause the apparatus or system to perform one or more methodological acts as described herein. In some embodiments, one or more input/output (I/O) interfaces may be coupled to one or more processors and may be used to provide a user with an interface to an elevator system. Various mechanical components known to those of skill in the art may be used in some embodiments. 
         [0043]    Embodiments may be implemented as one or more apparatuses, systems, and/or methods. In some embodiments, instructions may be stored on one or more computer-readable media, such as a transitory and/or non-transitory computer-readable medium. The instructions, when executed, may cause an entity (e.g., an apparatus or system) to perform one or more methodological acts as described herein. 
         [0044]    Aspects of the disclosure have been described in terms of illustrative embodiments thereof. Numerous other embodiments, modifications and variations within the scope and spirit of the appended claims will occur to persons of ordinary skill in the art from a review of this disclosure. For example, one of ordinary skill in the art will appreciate that the steps described in conjunction with the illustrative figures may be performed in other than the recited order, and that one or more steps illustrated may be optional.