Patent Publication Number: US-2016241057-A1

Title: Multiple parallel energy storage system and controlling method of the same

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     Korean Patent Application No. 10-2015-0021737, filed on Feb. 12, 2015, in the Korean Intellectual Property Office, and entitled: “Multiple Parallel Energy Storage System and Controlling Method Of The Same,” is incorporated by reference herein in its entirety. 
     BACKGROUND 
     1. Field 
     Embodiments relate to an energy storage system including an energy storage device and a plurality of battery trays connected in parallel, and a method of controlling the same. 
     2. Description of the Related Art 
     In the midst of destruction of the environment, resource depletion, and the like, interest in a system that may be able to store power and effectively utilize the stored power has increased. Also, interest in new and renewable energy not causing pollution in a power generation process has increased. In general, rechargeable batteries have been actively researched in line with the development of portable electronic devices, e.g., cellular phones, notebook computers, camcorders, personal digital assistants (PDAs), and the like. In particular, various types of rechargeable batteries including a nickel-cadmium battery, a lead storage battery, a nickel metal hybrid battery (NiMH), a lithium-ion battery, a lithium polymer battery, a metal lithium battery, and a zinc-air storage battery have been developed. A rechargeable battery is combined with a circuit to constitute a battery pack, and charging and discharging may be performed through an external terminal of the battery pack. 
     A peripheral circuit including a charging/discharging circuit may be a printed circuit board (PCB) and subsequently combined with the battery cell. When an external power source is connected through an external terminal of the battery pack, the battery cell is charged by the external power source supplied through the charging/discharging circuit and the external terminal. When a load is connected through the external terminal, power of the battery cell is supplied to the load through the charging/discharging circuit and the external terminal. The charging/discharging circuit controls charging and discharging of the battery cell between the external terminal and the battery cell. In general, a plurality of battery cells may be connected in series and/or parallel according to consumption capacity of a load. 
     When the energy storage system is in a normal status, both a charge switch and a discharge switch may be in an ON state during a discharging operation. Even in a rest status, both the charge switch and the discharge switch may be in the ON state, remaining unchanged. Also, when the energy storage system is turned to a charging state, both the charge switch and the discharge switch may be in the ON state. Thereafter, when charging is completed, the charge switch may be turned off, while the discharge switch may be maintained in the ON state. 
     When the energy storage system enters an under voltage protection (UVP) status, both the charge switch and the discharge switch may be turned off. When a charger voltage is supplied, that is, when charging starts, both the charge switch and the discharge switch are turned to the ON state, releasing the UVP status. 
     SUMMARY 
     A method for controlling an energy storage system of a battery tray in an under voltage protection (UVP) status according to an embodiment includes: performing precharging when a charge voltage is detected; transmitting information indicating that precharging is performed to at least one different tray connected to the battery tray in parallel; and when all of battery trays have performed precharging, simultaneously transmitting information instructing to start charging to the at least one different battery tray. 
     The information indicating that precharging is performed may be transmitted to the at least one different battery tray using a controller area network (CAN) communication. 
     Transmitting the information instructing to start charging may include simultaneously transmitting information instructing start charging to the at least one different battery tray in a state in which all of the battery trays have performed precharging and in a state in which the information indicating that all of the battery trays performed precharging has been transmitted. 
     Transmitting the information instructing to start charging may include determining whether the battery tray is a battery tray for transmitting the information instructing to start charging; and when the battery tray is a battery tray for transmitting information instructing to start charging, simultaneously transmitting the information instructing to start charging to the at least one different battery tray. 
     The method may further include, when the battery tray is not a battery tray for transmitting the information instructing to start charging, receiving information instructing to start charging. 
     Performing precharging may include: turning off a charge switch and a discharge switch and turning on a precharge switch. Performing precharging may be before, after, or simultaneous with transmitting information. 
     A battery tray according to another embodiment includes: at least one battery cell; a charge switch and discharge switch connected to the battery cell in series; a precharge switch connected to the charge switch and discharge switch in parallel; and a battery tray control unit connected to the battery cell in series, wherein the tray control unit performs precharging when a charge voltage is detected and transmits information indicating that precharging is performed to at least one different battery tray connected to the battery tray in parallel, and when all of battery trays have performed precharging, the tray control unit performs control to simultaneously transmit information instructing to start charging to the at least one different battery tray. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Features will become apparent to those of skill in the art by describing in detail exemplary embodiments with reference to the attached drawings in which: 
         FIG. 1  illustrates a view of an example of an energy storage system according to an embodiment. 
         FIG. 2  illustrates a view of an example of a configuration of a battery pack according to an embodiment. 
         FIG. 3  illustrates a view of an example of a configuration of a battery tray according to an embodiment. 
         FIG. 4  illustrates a flowchart of a procedure in which an energy storage system returns from an under voltage protection (UVP) status to a normal state according to an embodiment. 
     
    
    
     DETAILED DESCRIPTION 
     Example embodiments will now be described more fully hereinafter with reference to the accompanying drawings; however, they may be embodied in different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey exemplary implementations to those skilled in the art. 
     It is to be understood that when one element is referred to as being “connected to” or “coupled to” another element, it may be connected directly to or coupled directly to another element or be connected to or coupled to another element, having the other element intervening therebetween. In addition, in the following description, and the word ‘including’ does not preclude the presence of other components and means that an additional component may be included. 
     Terms such as ‘first’, ‘second’, etc., may be used to describe various components, but the components are not to be construed as being limited to the terms. The terms are used only to distinguish one component from another component. For example, the ‘first’ component may be named the ‘second’ component and the ‘second’ component may also be similarly named the ‘first’ component, without departing from the scope of the disclosure. 
     Also, elements of the embodiments are independently illustrated to show different characteristic functions, and it does not mean that each element is configured as separate hardware or a single software component. Namely, for the sake of explanation, respective elements are arranged to be included, and at least two of the respective elements may be incorporated into a single element or a single element may be divided into a plurality of elements to perform a function, and the integrated embodiment and divided embodiment of the respective elements are included in the scope of the disclosure unless contrary thereto. 
       FIG. 1  illustrates a view of an example of an energy storage system according to an embodiment. Referring to  FIG. 1 , a power storage system  110  according to an embodiment may supply power to a load  140 , in tandem with a power generation system  120  and a grid  130 . 
     The power generation system  120  is a system producing electric power using an energy source. The power generation system  120  may supply produced power to a power storage system  110 . For example, the power generation system  120  may be a photovoltaic power generation system, a wind power generation system, a tidal power generation system, or any power generation system producing electric power using renewable energy, e.g., solar heat, terrestrial heat, or the like. For example, a solar battery producing electric energy using solar heat, easy to install in homes or factories, may be applied to the power storage system  110 . The power generation system  120  may include a plurality of power generation modules in parallel and produces electric power by the power generation modules, thus constituting a large capacity power system. 
     The grid  130  may include a power plant, a substation, and a power line. When the grid  130  is in a normal status, the grid  130  supplies power to the power storage system  110  such that power may be supplied to the load  140  and/or the battery pack  160 , and receives power from the power storage system  110 . When the grid  130  is in an abnormal status, power supply from the grid  130  to the power storage system  110  is stopped from operation and power supply from the power storage system  110  to the grid  130  is also stopped. 
     The load  140  may consume power produced by the power generation system  120 , power stored in the battery pack  160 , or power supplied form the grid  130 . Homes or factories may be an example of the load  140 . 
     The power storage system  110  may store power produced by the power generation system  120  in the battery pack  160  and supply the produced power to the grid  130 , may supply power stored in the battery pack  160  to the grid  130 , or may store power supplied from the grid  130  in the battery pack  160 . When the grid  130  is in an abnormal status, e.g., when power failure occurs, the power storage system  110  may perform an uninterruptible power supply (UPS) operation to supply power to the load  140 . Even when the grid  130  is in a normal status, the power storage system  110  may supply power produced by the power generation system  120  or power stored in the battery pack  160  to the load  140 . 
     The power storage system  110  may include a power conversion system  150 , the battery pack  160 , a first switch  170 , and a second switch  180 . 
     The power conversion system  150  converts power of the power generation system  120 , the grid  130 , and the battery pack  160  into a requested specification and supplies the same to where the power is required. The power conversion system  150  may include a power conversion unit  151 , a DC link unit  152 , an inverter  153 , a converter  154 , and an integrated controller  155 . 
     The power conversion unit  151  is a power conversion device connected between the power generation system  120  and the DC link unit  152 . The power conversion unit  151  may transfer power produced by the power generation system  120  to the DC link unit  152  and, in this case, the power conversion unit  151  may convert an output voltage into a DC link voltage. 
     The power conversion unit  151  may be configured as a power conversion circuit, e.g., as a converter or a rectifying circuit, according to types of the power generation system  120 . For example, when the power generation system  120  produces DC, the power conversion unit  151  may be a DC/DC converter. Meanwhile, when the power generation system  120  produces AC, the power conversion unit  151  may be a rectifying circuit for converting AC into DC. In particular, when the power generation system  120  is a photovoltaic power generation system, the power conversion unit  151  may include a maximum power point tracking (MPPT) converter performing MPPT controlling to obtain power produced by the power generation system  120  to maximum according to a change in an amount of solar radiation or a temperature. When the power generation system  120  does not produce power, the power conversion unit  151  may be stopped to minimize power consumed by the power conversion circuit. 
     A DC link voltage may become unstable in magnitude due to a drop in an instantaneous voltage in the grid  130  or generation of a peak load in the load  140 . However, the DC link voltage needs to be stabilized for a normal operation of the converter  154  and the inverter  153 . Here, the DC link unit  152  may be connected between the power conversion unit  151  and the inverter  153  to uniformly maintain the DC link voltage. For example, a large capacitor may be used as the DC link unit. 
     The inverter  153  is a power conversion device connected between the DC link unit  152  and the first switch  170 . The inverter  153  may include an inverter converting a DC link voltage output from the power generation system  120  and/or the battery pack  160  into an AC voltage of the grid  130 , and outputting the same in a discharge mode. Also, in order to store power of the grid  130  in the battery pack  160  in a charge mode, the inverter  153  may include a rectifying circuit rectifying an AC voltage, converting the same into a DC link voltage, and outputting the converted DC link voltage. That is, the inverter  153  may be a bi-directional inverter in which input and output directions may be changed. According to embodiments, the inverter  153  may include a filter for removing harmonics from an AC voltage output to the grid  130 . Also, in order to suppress generation of invalid power, the inverter  153  may include a phase locked loop (PLL) for locking a phase of an AC voltage output from the inverter  153  of the grid  130  and a phase of the AC voltage of the grid  130 . The inverter  153  may perform additional functions, e.g., limiting a voltage fluctuation range, improving a power factor, removing a DC component, protecting transient phenomenon, and the like. Also, when not in use, operation of the inverter  153  may be stopped to minimize power consumption. 
     The converter  154  is a power conversion device connected between the DC link unit  152  and the battery pack  160 . The converter  154  may include a converter which DC-DC converts power stored in the battery pack  160  into a voltage level required by the inverter  153 , i.e., into a DC link voltage, and outputs the same in the discharge mode. Also, the converter  154  may include a converter which DC-DC converts a voltage of power output from the power conversion unit  151  or a voltage of power output from the inverter  153  into a voltage level required by the battery pack  160 , i.e., into a charge voltage in the charge mode. That is, the converter  154  may be a bi-directional converter in which input and output directions may be changed. When not required to charge or discharge the battery pack  160 , operation of the converter  154  may be stopped to minimize power consumption. 
     The integrated controller  155  may monitor states of the power generation system  120 , the grid  130 , the battery pack  160 , and the load  140 , and may control operations of the power conversion unit  151 , the inverter  153 , the converter  154 , the battery pack  160 , the first switch  170 , and the second switch  180 . For example, the integrated controller  155  may monitor whether a power failure has occurred in the grid  130 , whether power is produced by the power generation system  120 , and, when the power generation system  120  produces power, may output a charge state of the battery pack  160 , power consumption of the load  140 , and a time. Also, when power to be supplied to the load  140  is not sufficient because a power failure occurs in the grid  130 , or the like, the integrated controller  155  may determine priority levels of power usage devices included in the load  140  and control the load  140  such that power is supplied to the power usage devices, starting from one having the highest priority level. 
     The first switch  170  and the second switch  180  are connected in series between the inverter  153  and the grid  130 , and perform an ON/OFF operation under the control of the integrated controller  155  to control a current flow between the power generation system  120  and the grid  130 . ON/OFF of the first switch  170  and the second switch  180  may be determined according to states of the power generation system  120 , the grid  130 , and the battery pack  160 . 
     In detail, when power of the power generation system  120  and/or the battery pack  160  is supplied to the load  140  or when power of the grid  130  is supplied to the battery pack  160 , the first switch  170  is turned on. When power of the power generation system  120  and/or the battery pack  160  is supplied to the grid  130 , or when power of the grid  130  is supplied to the load  140  and/or the battery pack  160 , the second switch  180  is turned on. 
     When a power failure occurs in the grid  130 , the second switch  180  may be turned off and the first switch  170  may be turned on. That is, power from the power generation system  120  and/or the battery pack is supplied to the load  140 , while power supplied to the load  140  from flowing toward the grid  130  is prevented. Accordingly, a unilateral operation of the power storage system  110  is prevented, thus preventing occurrence of an accident in which a worker who works in a power line of the grid  130  from getting shocked by power from the power storage system  110 . 
     As the first switch  170  and the second switch  180 , a switching device that can tolerate a large current may be used, e.g., a relay. 
     The battery pack  160  may receive power from the power generation system  120  and/or the grid  130  and store the same, and supply stored power to the load  140  or the grid  130 . The battery pack  160  may include a part storing power and a part controlling the part storing power. 
       FIG. 2  illustrates a view of an example of a configuration of a battery pack according to an embodiment. Referring to  FIG. 2 , a battery pack according to an embodiment may include at least two battery trays  220 ,  230 , and  240 . Each of the battery trays  220 ,  230 , and  240  may include tray control units  225 ,  235 , and  245 , respectively. Here, the tray control units  225 ,  235 , and  246  may be battery management systems (BMS). The plurality of battery trays  220 ,  230 , and  240  connected in parallel may be connected to a charger  210  to be charged. When the plurality of battery trays  220 ,  230 , and  240  are charged, a charge voltage may be applied thereto. 
     The battery trays  220 ,  230 , and  240  may store power supplied from the outside, i.e., the power generation system  120  and/or the grid  130 , and may supply the stored power to the power generation system  120  and/or the grid  130 . 
     Here, the at least two battery trays  220 ,  230 , and  240  may be connected in parallel. Each of the battery trays  220 ,  230 , and  240  may include at least one battery cell. As the battery cell, various rechargeable batteries available to be charged may be used. For example, the rechargeable battery used in the battery cell may be a nickel-cadmium battery, a lead storage battery, a nickel metal hybrid battery (NiMH), a lithium-ion battery, or a lithium polymer battery, but embodiments are not limited thereto. 
       FIG. 3  illustrates a view of an example of a configuration of a battery tray according to an embodiment. Referring to  FIG. 3 , the battery tray according to an embodiment may include rechargeable battery cells  320  and  325 , and a protective circuit. The protective circuit may include a switch  310  and a tray control unit  390 , e.g., a battery management system (BMS). The switch  310  may include a charge switch and a discharge switch  313  and may include a precharge switch  315  connected in parallel thereto. The switch  310  may further include a resistor  317  connected to the precharge switch  315  in series. 
     The BMS  390  may include at least one analog front end (AFE)  330  and a MBS control unit  340 . The MBS control unit  340  may be a microcontroller (MCU). Also, the BMS  390  may further include a power software  370 , an identification (ID) software  371 , a transmitting (TR) software  373 , a controller area network (CAN) communication unit  375 , a light emitting diode (LED)  377 , and a joint test action group (JTAG) connector  379 . Of course, the BMS  390  may not include all of the foregoing components, or may further include a component other than the enumerated components. The CAN communication unit  375 , an internal communication protocol of a battery pack, may control communication among the battery trays  220 ,  230 , and  240 , and control the battery pack. 
     Also, the battery tray may further include components such as a Hall sensor  350  and a fuse  360  as illustrated in  FIG. 3 . 
     The battery tray may include at least one battery cells  320  and  326  connected in series, and may be realized using various rechargeable batteries. Also, the battery cells  320  and  325  may transmit various types of internal information, for example, cell-related information such as a temperature of a cell, a charge voltage of the cell, and a current amount flowing in the cell to the AFEs  330  and  335 . 
     The AFEs  330  and  335  are connected in parallel between the battery cells  320  and  325  and the switch  310 , and may be connected in series between the battery cells  320  and  325  and the MCU  340 . The AFEs  330  and  335  may monitor a voltage, a current, a temperature, a remaining power amount, a lifespan, a charge state, and the like. The AFEs  330  and  335  may analog-to-digital convert the measured data and transfer the same to the MCU  340 . According to embodiments, the AFEs  330  and  335  may be connected in series or may be a single integrated circuit (IC). 
     The MCU  340  may control a general operation of the battery tray. For example, the MCU  340  controls operations of the AFEs  330  and  335  and collect monitoring data from the AFEs  330  and  335 . The MCU  340  may control other component connected thereto. 
     The charge switch and discharge switch  313  may be in a high current path in series between the battery cells  320  and  326 , and an external terminal to control a flow of a charge current and a discharge current. The charge switch may cut off a charge current and the discharge switch may cut off a discharge current. Each of the charge switch and the discharge switch may be configured as a field effect transistor (FET) and may be controlled by the MCU  340 . The charge switch may be referred to as a charge FET (C-FET) and the discharge switch may be referred to as a discharge FET (D-FET). 
     In existing energy storage systems, in a normal status, both the charge switch and the discharge switch are in an ON state during a discharge operation, on standby, and during a charge operation, and when the charging operation is completed, the charge switch is turned off and the discharge switch is maintained in the ON state. When the energy storage system enters the under voltage protection (UVP) status, both the charge switch and the discharge switch are turned off, and when a charger voltage is input, that is, when charging starts, both the charge switch and the discharge switch are turned on, releasing the UVP status. Here, in the case where the energy storage system includes a plurality of battery trays connected in parallel, when any one first battery tray among the battery trays connected in parallel starts charging, both a charge switch and a discharge switch included in the first battery tray are turned on, and thus, a battery voltage may be a charger voltage. Accordingly, battery trays other than the first battery tray measure the charge voltage to be low, resulting in that the UVP status may not be released. Also, when a charge switch and a discharge switch of any one battery tray are turned on to start charging, multiple parallel reference charge current flows in to cause an overcurrent protecting operation or an inrush, leading to a possibility of generation of switch failure. 
     In contrast, in the case of the energy storage system according to an embodiment, since the battery tray further includes the precharge switch  315  as illustrated, such a problem may be resolved. The precharge switch  315  may be configured as an FET, and it may be referred to as a P-FET  315 . 
     That is, in the case of the energy storage system according to an embodiment, when the energy storage system enters the UVP status, if a charger voltage is applied, the precharge switch  315 , instead of the charge switch C-FET and the discharge switch D-FET  313 , may be first turned on to perform precharging. The battery tray, to which a charge voltage is applied to perform precharging, may transmit information indicating that the charge voltage has been applied to perform precharging, to other battery trays connected thereto in parallel. Here, the information indicating that precharging is performed or the information indicating that the charge voltage has been applied may be the same as a charger detection flag, for example. The information indicating that precharging is performed may be transmitted to other battery trays through CAN communication. 
     Thereafter, when all the battery trays in the UVP status have performed precharging, any one among the battery trays may simultaneously transmit information instructing to start charging to at least one different battery tray connected in parallel. According to embodiments, when all the batteries have performed precharging and the charger detection flag is set, the information instructing to start charging may be simultaneously transmit other battery trays. That is, when all the battery trays have transmitted the charger detection flag, the information instructing to start charging may be transmitted to other battery trays. 
     A battery tray which has received the information instructing to start charging and the battery tray which has transmitted the information instructing to start charging may turn on the charge switch C-FET and discharge switch D-FET  313  and turn off the precharge switch P-FET  315 , thus exiting the UVP status. Accordingly, the energy storage system may enter a normal status to perform a charging/discharging operation. The information instructing to start charging may be a charger start sync. signal, for example. Alternatively, the information instructing to start charging may be a normal operation signal, i.e., a signal indicating to start a normal charging operation. Also, the information instructing to start charging may be transmitted to other battery tray through CAN communication. According to embodiments, the battery tray transmitting the information instructing to start charging may be set with respect to the lowest one or the highest one of CAN ID numbers of the plurality of trays. 
     According to an embodiment, even when the energy storage system enters the UVP status, the precharge switch  315 , instead of the charge/discharge switch  313 , is turned on, whereby other battery trays are prevented from measuring a charger voltage to be low. That is, due to the resistor  317  connected in series to the precharge switch  315 , a battery voltage is prevented from being equal to the charger voltage, whereby other battery trays in the UVP status are prevented from measuring a charger voltage to be low. Also, since the information instructing to start charging is simultaneously transmitted (or received) in a state in which the battery trays in the UVP status have performed precharging, all the battery trays may exit the UVP status. 
       FIG. 4  illustrates a view of an example of a procedure in which an energy storage system returns from an under voltage protection (UVP) status to a normal status according to an embodiment. 
     Referring to  FIG. 4 , a battery tray may enter a UVP status in operation  410 . Accordingly, all the switches C-FET, D-FET, and P-FET of the battery tray may be turned off in operation  420 . 
     Thereafter, the battery tray determines whether a charge voltage is applied in operation  430 , and when a charge voltage is applied, the battery tray may perform precharging in operation  440 . Here, in the battery tray, the precharge switch P-FET  315  may be changed to be turned on, but the charge switch C-FET and the discharge switch D-FET  313  may be maintained in the OFF state. 
     Thereafter, the battery tray may transmit information indicating that precharging is performed to other battery trays connected thereto in parallel. Here, the battery tray which has performed precharging may transmit the foregoing information to other battery trays through CAN communication. Meanwhile, according to an embodiment, performing precharging in operation  440  and transmitting the information indicating that precharging is performed in operation  450  may be made in reverse order, and alternatively, performing precharging and transmitting the information indicating that precharging is performed may be made simultaneously. Also, as described above, the information indicating that precharging is performed or the information indicating that the charge voltage has been applied may be the same as a charger detection flag, for example. 
     Thereafter, it may be determined whether precharging of all the battery trays has been performed in operation  460 . Here, according to an embodiment, it may be determined whether the charger detection flag has been set, i.e., whether all the battery trays have transmitted the charger detection flag. 
     When precharging of all the battery trays has not been performed, the battery trays are on standby. When precharging of all the battery trays has been performed, it may be determined whether to transmit information indicating that charging starts to other battery trays in operation  470 . That is, the battery trays may determine whether they are a reference battery tray for transmitting information instructing to start charging to other battery trays connected thereto in parallel according to preset conditions. This may be determined according to a CAN ID number, for example, as described above. 
     When a battery tray is a battery tray for transmitting information instructing to start charging, the battery tray may simultaneously transmit a normal operation signal to other battery trays connected thereto in operation  475 . The normal operation signal may be transmitted through CAN communication. Also, a charging operation may be performed in operation  490 . That is, the battery tray may exit the UVP status by turning on the charge switch C-FET and discharge switch D-FET  313 , and turning off the precharge switch P-FET  315 . Accordingly, the energy storage system may enter the normal status allowing a charge/discharge operation to be performed. 
     When a battery tray is not a battery tray for transmitting information instructing to start charging, it may be determined whether information instructing to start charging has been received in operation  480 . When the information instructing to start charging is received, the battery tray may turn on the C-FET and the D-FET  313  and turn off the P-FET  315  to perform charge/discharge operation in operation S 490 . However, when the information instructing to start charging is not received, the battery tray may return to operation  460  to perform a process of determining whether all of the other battery trays in the UVP status have performed precharging. 
     As described above, when the battery module  200  including the battery cells  100  according to an embodiment, adjacent battery cells may be easily serially connected or may be easily connected in parallel. Therefore, it is possible to reduce the number of parts and working processes and thus, to reduce manufacturing cost. 
     By way of summation and review, an embodiment may prevent failure of a switch, for example, a field effect transistor (FET), when an energy storage system including a plurality of battery trays connected in parallel returns to charging from an under voltage protection (UVP) status. Another embodiment may reduce or prevent generation of tray imbalance by simultaneously starting charging of a plurality of battery trays connected in parallel. 
     The methods and processes described herein may be performed by code or instructions to be executed by a computer, processor, manager, or controller. Because the algorithms that form the basis of the methods (or operations of the computer, processor, or controller) are described in detail, the code or instructions for implementing the operations of the method embodiments may transform the computer, processor, or controller into a special-purpose processor for performing the methods described herein. 
     Also, another embodiment may include a computer-readable medium, e.g., a non-transitory computer-readable medium, for storing the code or instructions described above. The computer-readable medium may be a volatile or non-volatile memory or other storage device, which may be removably or fixedly coupled to the computer, processor, or controller which is to execute the code or instructions for performing the method embodiments described herein. 
     Example embodiments have been disclosed herein, and although specific terms are employed, they are used and are to be interpreted in a generic and descriptive sense only and not for purpose of limitation. In some instances, as would be apparent to one of ordinary skill in the art as of the filing of the present application, features, characteristics, and/or elements described in connection with a particular embodiment may be used singly or in combination with features, characteristics, and/or elements described in connection with other embodiments unless otherwise specifically indicated. Accordingly, it will be understood by those of skill in the art that various changes in form and details may be made without departing from the spirit and scope of the present invention as set forth in the following claims.