Patent Publication Number: US-2022231517-A1

Title: Method for operating an electrical energy store, electrical energy store and device

Description:
FIELD 
     The present invention relates to a method for operating an electrical energy store, to an electrical energy store and to a device, in particular a vehicle. 
     BACKGROUND INFORMATION 
     U.S. Patent Application Publication No. 2013/0169038 shows a device for the uninterrupted power supply of an electric vehicle from serially interconnected batteries, which includes a bridging switch. 
     China Patent Publication No. CN 203103992 U shows a control system for a battery charging management and battery discharging management. 
     SUMMARY 
     In accordance with an example embodiment of the present invention, in a method for operating an electrical energy store which includes at least two electrical energy store modules connected in parallel and a connection means (i.e., connector), it is initially queried which electrical energy store modules are operational, a first voltage of an operational electrical energy store module then being determined, which is greater than or equal to voltage U of all operational electrical energy store modules, those operational electrical energy store modules then being selected, whose voltage is within a voltage range below the first voltage, the selected electrical energy store modules then being electroconductively connected to the connection means. 
     With the aid of the method of the example embodiment of the present invention, it is possible to put into operation electrical energy store modules of an electrical energy store, which have various charge states and/or various voltages and/or various points in time of operational readiness. 
     The electrical energy store in this case is advantageously switched on with reduced power as compared to its maximum power and the power of the electrical energy store is gradually increased during the method by connecting further electrical energy store modules. The voltage range includes the voltage of the operational electrical energy store module having the maximum first voltage. As a result, the number of the connected electrical energy store modules may be maximized during the method, since the voltage of the electrical energy store modules decreases during discharge. 
     Further advantageous specific embodiments of the present invention are disclosed herein. 
     According to one advantageous embodiment of the present invention, if not all electrical energy store modules have been connected to the connection means of the electrical energy store, it is queried again at a later point in time during the operation of the electrical energy store which electrical energy store modules are operational and that electrical energy store module is selected, whose voltage is within the voltage range below a mean voltage of the electrical energy store module electrically connected to the connection means, and is electroconductively connected to the connection means. Thus, electrical energy store modules, which were not yet operable or whose voltage was too low at the start of the method, are connected at a later point in time and thus the available power of the electrical energy store is increased during the method. 
     In this case, it is advantageous if the aforementioned method steps are repeated until all electrical energy store modules are electroconductively connected to the connection means or the electrical energy store is switched off, the method steps being repeated, in particular, temporally recurrently, in particular, periodically. In this way, further electrical energy store modules may be connected in the course of the method during the operation of the electrical energy store. 
     It is further advantageous if the number of electrical energy store modules connected to the connection means remains constant if the voltage of a non-operable electrical energy store module is greater than the mean voltage and less than the sum of the mean voltage and of half the voltage range, until this electrical energy store module becomes operational, whereupon it is connected to the connection means, or until the voltage of this electrical energy store module is greater than the sum of the mean voltage and of half the voltage range. Thus, an electrical energy store module, which only later becomes operational and has a high voltage, may still also be put into operation. In this case, it is important that a voltage limiting value is not exceeded, in order to limit the compensating currents between the electrical energy store modules and to thereby protect the switching means (i.e., switch). 
     It is advantageous in this case if an electrical energy store module, whose voltage is greater than the mean voltage, in particular, greater than the sum of the mean voltage and of half the voltage range, is not electroconductively connected to the connection means, if it becomes operational during the method, in particular, during the entire method. This prevents the switching means from being overloaded during the connection of this electrical energy store module by excessively high compensating currents between the electrical energy store modules. 
     When switching off the electrical energy store, all electrical energy store modules are advantageously separated from the connection means. In this case, it is advantageous that the connection means of the electrical energy store is voltage-free after the electrical energy store is switched off. 
     It is further advantageous if the expansion of the voltage range is a function of the electrical energy store, in particular, of switching means of the electrical energy store and/or is constant during the method. 
     An electrical energy store module is advantageously operational if its temperature and/or its voltage is/are below a maximum limiting value and/or above a minimum limiting value. 
     In accordance with the present invention, in the electrical energy store including connection means and at least two electrical energy store modules, which are connected in parallel, the electrical energy store is configured to be operated with the aid of a method as described above or as further disclosed herein. 
     In accordance with the present invention, the electrical energy store modules may have various charge states and points in time of operational readiness. The electrical energy store may be put into operation with a subset of the electrical energy store modules, the available power of the electrical energy store being increasable. 
     According to one advantageous embodiment of the present invention, the electrical energy store includes a control unit, each electrical energy store module including at least one sensor, in particular, one voltage sensor and/or one temperature sensor, and a switching means for electroconductively connecting the respective electrical energy store module to the connection means of the electrical energy store, the control unit being configured to evaluate signals of the sensors and to activate the switching means. It is advantageous in this case that a central control unit is configured to control the method. 
     The electrical energy store modules are advantageously designed to be interchangeable. The electrical energy store may, for example, include electrical energy store modules that are variously aged. 
     In accordance with an example embodiment of the present invention, in the case of the device, in particular, the vehicle, the device includes an electrical energy store as described above and as disclosed hereinafter relating to the electrical energy store. 
     In accordance with an example embodiment of the present invention, the availability of the device may be improved by being able to connect individual electrical energy store modules in succession and/or in that electrical energy store modules are interchangeable. 
     The above embodiments and refinements may, if meaningful, be arbitrarily combined with one another. Further possible embodiments, refinements and implementations of the present invention also include not explicitly mentioned combinations of features of the present invention described previously or below with respect to the exemplary embodiments. Those skilled in the art will, in particular, also add individual aspects as improvements on or additions to the respective basic form of the present invention, in view of the disclosure herein. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Below, the present invention is explained with reference to exemplary embodiments, from which further inventive features may result which, however, do not limit the scope of the present invention. The exemplary embodiments are represented in the figures. 
         FIG. 1  shows a representation of voltage U and the operational readiness of various electrical energy store modules M 1 , M 2 , M 3 , M 4 , M 5 , M 6 , M 7 , M 8 , M 9 , M 10  of an electrical energy store according to an example embodiment of the present invention at a first point in time t 1 . 
         FIG. 2  shows a representation of voltage U and the operational readiness of electrical energy store modules M 1 , . . . M 10  of the electrical energy store at a second point in time t 2 . 
         FIG. 3  shows a representation of voltage U and of the operational readiness of various electrical energy store modules M 1 , . . . M 10  of the electrical energy store at a third point in time t 3 . 
         FIG. 4  schematically shows a flowchart of method  100  according to an example embodiment of the present invention for operating an electrical energy store. 
     
    
    
     DETAILED DESCRIPTION OF EXAMPLE EMBODIMENTS 
     The electrical energy store according to the present invention includes a plurality of electrical energy store modules M 1 , . . . M 10 , which are connected in parallel, two connection means (i.e., connectors) and a control unit. Each electrical energy store module M 1 , . . . M 10  includes at least one sensor, in particular, one voltage sensor and/or one temperature sensor, and switching means (i.e., switch) for electroconductively connecting respective energy store module M 1 , . . . M 10  to the connection means of the electrical energy store. The control unit is configured to evaluate signals of the sensor and to activate the switching means. 
     The voltages of various electrical energy store modules M 1 , . . . M 10 , in this exemplary embodiment ten electrical energy store modules M 1 , . . . M 10  at a first point in time t 1  are represented in  FIG. 1 . In this case, voltage U of an operational electrical energy store module M 1 , . . . M 10  is represented with the aid of a white bar and voltage U of a non-operational electrical energy store module M 1 , . . . M 10  is represented with the aid of a hatched bar. 
     First point in time t 1  is temporally prior to the start-up of the electrical energy store. 
     At first point in time t 1 , electrical energy store modules M 1 , . . . M 10  have different voltages. Seven electrical energy store modules M 1 , M 3 , M 4 , M 5 , M 7 , M 8 , M 10  are operational. Three further electrical energy store modules M 2 , M 6 , M 9  are not operational. 
     A first electrical energy store module M 1  has a first voltage U 1 , which is greater than the voltages of other electrical energy store modules M 2 , . . . M 10  of the electrical energy store. The electrical energy store has a voltage range ΔU, within which electrical energy store modules M 1 , . . . M 10  having various voltages U may be put into operation. Those electrical energy store modules M 1 , . . . M 10 , which are operational and which have the highest voltages, are preferably initially put into operation. These are operational electrical energy store modules M 1 , . . . M 10 , whose voltage is between first voltage U 1  and a second voltage U 2 . First voltage U 1  in this case limits voltage range ΔU upwardly and second voltage U 2  limits voltage range ΔU downwardly. Second voltage U 2  is therefore lower by ΔU than first voltage U 1 . 
     The expansion of voltage range ΔU in this case is a function of the electrical energy store, in particular, of the switching means of the electrical energy store, and unchangeable during the method. It is based on the maximally allowed current strength at the switching means under load, which includes compensating currents between the interconnected electrical energy store modules. Voltage range ΔU has an expansion, which is less than 5 V, in particular, less than 3 V, preferably approximately 1 V. As a result, the compensating currents between electrical energy store modules M 1 , . . . M 10  are limited to less than 25 A. These values correspond to a variance of the charge state of 5% between the electrical energy store modules. 
     In this exemplary embodiment, first electrical energy store module M 1 , fourth electrical energy store module M 4 , fifth electrical energy store module M 5  and eighth electrical energy store module M 8  each have a voltage U, which is within voltage range ΔU between first voltage U 1  and second voltage U 2 , and are operational. Voltage U of second electrical energy store module M 2  is in fact within voltage range ΔU, but second electrical energy store module M 2  is not operational. Voltages U of remaining electrical energy store modules M 3 , M 6 , M 7 , M 9 , M 10  are below second voltage U 2 . 
     The voltages of various electrical energy store modules M 1 , . . . M 10  at a second point in time t 2  are represented in  FIG. 2 . In this case, the voltage of one operational electrical energy store module M 1 , . . . M 10  is represented with the aid of a white bar and the voltage of a non-operational electrical energy store module M 1 , . . . M 10  is represented with the aid of a hatched bar. 
     Second point in time t 2  is temporally after first point in time t 1  and shortly after the start-up of the electrical energy store. 
     At second point in time t 2 , those electrical energy store modules M 1 , . . . M 10  are electroconductively connected to one another and to the connection means and/or to a device, which were operational at first point in time t 1  and whose voltage was between first voltage U 1  and second voltage U 2 . These are first electrical energy store module M 1 , fourth electrical energy store module M 4 , fifth electrical energy store module M 5  and eighth electrical energy store module M 8 . When connecting these electrical energy store modules M 1 , M 4 , M 5 , M 8 , the voltage of these electrical energy store modules is equalized so that these electrical energy store modules M 1 , M 4 , M 5 , M 8  each have a mean voltage Um. 
     The voltages of various electrical energy store modules M 1 , . . . M 10  at a third point in time t 3  are represented in  FIG. 3 . In this case, the voltage of an operational electrical energy store module M 1 , . . . M 10  is represented with the aid of a white bar and the voltage of a non-operational electrical energy store model M 1 , . . . M 10  is represented with the aid of a hatched bar. 
     Third point in time t 3  is temporally after first point in time t 1  and after second point in time t 2 . 
     At third point in time t 3 , those electrical energy store modules M 1 , M 4 , M 5 , M 8  are electroconductively connected to one another and to the connection means and/or to the device, which were electroconductively connected to one another and to the connection means and/or to the device at second point in time t 2 . These are first electrical energy store module M 1 , fourth electrical energy store module M 4 , fifth electrical energy store module M 5  and eighth electrical energy store module M 8 . 
     The electrical energy store module M 1 , . . . M 10  having the highest voltage U at third point in time t 3  is second energy store module M 2 , however, the second energy store module is also not operational at third point in time t 3 . 
     The operational electrical energy store module M 1 , . . . M 10  having the highest voltage are first, fourth, fifth and eighth electrical energy store module M 1 , M 4 , M 5 , M 8 , all of which have mean voltage Um. 
     Voltage range ΔU no longer extends from first voltage U 1  up to second voltage U 2  at third point in time t 3 , but from mean voltage Um to a third voltage U 3 , which is lower than second voltage U 2 . Third voltage U 3  in this case is lower by ΔU than mean voltage Um. 
     All operational electrical energy store modules M 1 , . . . M 10 , whose voltage U is between mean voltage Um and third voltage U 3 , may be put into operation at third point in time t 3 . That is, in addition to first electrical energy store module M 1 , fourth electrical energy store module M 4 , fifth electrical energy store module M 5  and eighth electrical energy store module M 8 , seventh electrical energy store module M 7 . 
     Voltages U of sixth electrical energy store module M 6  and of ninth electrical energy store module M 9  are also in voltage range ΔU between mean voltage Um and third voltage U 3 , however, sixth electrical energy store module M 6  and ninth electrical energy store module M 9  are not operational. 
     An electrical energy store module M 1 , . . . M 10 , whose voltage U is within voltage range ΔU may, once it becomes operational, also be switched on. Should an electrical energy store module M 1 , . . . M 10 , whose voltage is above mean voltage Um, in particular, above the sum of mean voltage Um and of half the voltage range ΔU, become operational, it may be switched on only after the next start of the electrical energy store. 
     A flowchart of method  100  according to the present invention for operating an electrical energy store is represented in  FIG. 4 . Method  100  for operating an electrical energy store includes the following steps: 
     In a first method step  101 , the electrical energy store is initialized. In the process, respective operating parameters, in particular, a respective voltage U and/or a respective temperature and/or the respective charge state and, if necessary, further parameters, of respective energy store modules M 1 , . . . M 10  are detected. 
     In a second method step  102  after first method step  101 , it is queried whether all electrical energy store modules M 1 , . . . M 10  of the electrical energy store are operational. 
     If not all electrical energy store modules M 1 , . . . M 10  are operational, operational electrical energy store modules M 1 , . . . M 10  are selected in a third method step  103  after second method step  102 . 
     In a fourth method step  104  after third method step  103 , that electrical energy store module M 1 , . . . M 10  is selected from operational electrical energy store modules M 1 , . . . M 10 , which has a maximum first voltage U 1 . In this case, maximum first voltage U 1  is greater than all other voltages U of operational electrical energy store modules M 1 , . . . M 10 . Those operational electric energy store modules M 1 , . . . M 10  are then selected, whose respective voltage U is within a voltage range ΔU below first voltage U 1 . 
     In a fifth method step  105  after fourth method step  104  or after eleventh method step  111 , electrical energy store modules M 1 , . . . M 10  selected in fourth method step  104  or in tenth method step  110  are electroconductively connected to one another and to the connection means and/or to a device. 
     In a sixth method step  106  after fifth method step  105 , the electrical energy store and/or the device is started with electrical energy store module M 1 , . . . M 10  selected in fourth method step  104  or in tenth method step  110 . The power of the electrical energy store in this case is reduced as compared to an operation including all electrical energy store modules M 1 , . . . M 10 . Voltages U of electrical energy store modules M 1 , . . . M 10  are then equalized and a mean voltage Um occurs in all electrical energy store modules M 1 , . . . M 10  electroconductively connected to one another. 
     In a seventh method step  107  after sixth method step  106 , it is queried whether further electrical energy store modules M 1 , . . . M 10  are operational and have a voltage U, which is within a voltage range ΔU below mean voltage Um of selected electrical energy store modules M 1 , . . . M 10  and, if necessary, this electrical energy store module M 1 , . . . M 10  is selected. 
     If in seventh method step  107  no electrical energy store module M 1 , . . . M 10  has been selected, seventh method step  107  is repeated temporally recurrently, in particular, periodically. 
     If in seventh method step  107  an electrical energy store module M 1 , . . . M 10  has been selected, in an eighth method step  108 , this electrical energy store module M 1 , . . . M 10  is electroconductively connected to electrical energy store modules M 1 , . . . M 10  already electroconductively connected to one another and to the connection means and/or to the device. 
     Seventh method step  107  and eighth method step  108  are repeated until all electrical energy store modules M 1 , . . . M 10  are electroconductively connected to one another and to the connection means and/or to the device, or method  100  is terminated in a ninth method step  109  and the electrical energy store and/or the device is/are switched off. 
     If in second method step  102  all electrical energy store modules M 1 , . . . M 10  are operational, that energy store module M 1 , . . . M 10  of electrical energy store modules M 1 , . . . M 10  having a maximum first voltage U 1  is selected in a tenth method step  110  after second method step  102 . In this case, maximum first voltage U 1  is greater than all other voltages U of electrical energy store modules M 1 , . . . M 10 . Those electrical energy store modules M 1 , . . . M 10  are thereafter selected, whose respective voltage U is within a voltage range ΔU below first voltage U 1 . 
     In an eleventh method step  111  after tenth method step  110 , it is queried whether all electrical energy store modules M 1 , . . . M 10  have been selected in tenth method step  110 . 
     If not all electrical energy store modules M 1 , . . . M 10  have been selected in tenth method step  110 , the method is continued after eleventh method step  111  with fifth method step  105 . 
     If in tenth method step  110  all electrical energy store modules M 1 , . . . M 10  of the electrical energy store have been selected, all electrical energy store modules M 1 , . . . M 10  are electroconductively connected to one another in a twelfth method step  112  and to the connection means and/or to the device. 
     In a thirteenth method step  113  after twelfth method step  112 , the electrical energy store and/or the device is started with all electrical energy store modules M 1 , . . . M 10 . 
     After thirteenth method step  113 , the method is terminated in ninth method step  109  and the electrical energy store and/or the device is/are switched off. 
     The respective electroconductive connection between respective electrical energy store modules M 1 , . . . M 10  and the connection means and/or the device is preferably separated after the ninth method step. 
     An electrical energy store in this case is understood to mean a rechargeable energy store, in particular, including an electrochemical energy store cell and/or an energy store module including at least one electrochemical energy store cell and/or one energy store pack including at least one energy store module. The energy store cell is implementable as a lithium-based battery cell, in particular, a lithium ion battery cell. Alternatively, the energy store cell is designed as a lithium polymer battery cell or a nickel metal hydride battery cell or a lead acid battery cell or a lithium air battery cell or a lithium sulfur battery cell.