Abstract:
The invention relates to a test apparatus for checking a battery control device or for checking a battery having at least one cell, comprising a battery simulator ( 18 ) for simulating a voltage of at least one cell of a simulated battery for specification on the battery control device, wherein the battery control device or the battery is connected to an evaluation module ( 14 ) via a rail designed as a central bus in order to process and check the voltage of a selected cell, wherein the selected cell of the battery simulator for the battery control device or the selected cell of the battery can be selected via a separation module ( 24 ). In this way, a test apparatus for checking a battery control device or for checking a battery can be provided, which has a simple construction and can check all of the cells of a simulated or actual battery in a simple manner.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    The invention relates to a test apparatus for checking a battery control device or a battery, and to a method for testing a battery control device or a battery. 
         [0002]    In the motor vehicle industry, electric drives, in particular in electric or hybrid vehicles, are becoming increasingly significant. These electric drives comprise a battery. The battery is monitored by a battery control device. Before installation in electric or hybrid vehicles, the battery and the battery control device must be tested. 
         [0003]    In practical application, automated test stands are utilized for generating test cases, configuring the test stand, carrying out the test, and evaluating the test. This includes the HIL standard, which is an acronym for the “hardware-in-the-loop” standard. In an HIL test system, at least one real component is connected to a simulator. 
         [0004]    However, the devices used in an HIL standard have a complex design and are heavy and voluminous, and are not sufficiently mobile for a battery-electronics test in the field. 
         [0005]    The problem addressed by the invention is therefore that of providing a test apparatus for checking a battery control device, which has a simple design and can check all the cells of a simulated or real battery in a simple manner. 
         [0006]    The problem is solved by a test apparatus according to the invention, and by a method according to the invention. Embodiments of the invention are described in the description which follows, and can depict one aspect of the invention either individually or in combination. 
       SUMMARY OF THE INVENTION 
       [0007]    According to the invention, a test apparatus for checking a battery control device or for checking a battery having at least one cell comprises a battery simulator for simulating a voltage of at least one cell of a simulated battery for specification to the battery control device, wherein the battery control device or the battery is connected to an evaluation module via a rail designed as a central bus in order to process and check the voltage, temperatures, and further quantities of a selected cell, wherein the selected cell of the battery simulator for the battery control device or the selected cell of the battery can be selected via an isolating module. 
         [0008]    Depending on the test mode of the test apparatus, a battery can be simulated in the test apparatus in order to test a battery control device or a real battery. 
         [0009]    By means of such a design, a simple, mobile test apparatus can be provided for checking a battery control device. The battery control device can be a battery control and supervision unit (BCSU). The battery control unit can comprise at least one monitoring device, in particular at least one CSC chip. The abbreviation CSC stands for “cell supervision unit”. A cell supervision unit (CSC) monitors the individual cells and ensures that they interact. The CSC balances the state of charge of all cells in the battery with respect to one another in order to ensure that the cells are not loaded to different extents for a long period of time. Due to the use of a battery simulator, the supply voltages can be made available for the monitoring device of the battery control device. In this case, the battery simulator can simulate individual cells of a battery and forward the corresponding measured quantities, such as supply voltages, to the monitoring device, so that the monitoring device can check and process the simulated cells. In addition, the supply voltage and supply currents of the monitoring device can be measured via the battery simulator and can be processed via the evaluation module. The battery simulator is not used, however, but rather is switched off when a battery is supposed to be tested in the test apparatus. 
         [0010]    The rail designed as a central bus is, in particular, a central voltage rail. The term “bus” describes a system for transferring voltage, temperature, data, and further quantities between multiple participants via a shared transmission path, wherein the participants are not involved in the transmission between other participants. The term “central voltage rail” describes a so-called rail comprising rail+ and rail−, to which the individual cells of the battery simulator or the battery can be connected and, in this way, can be connected to the evaluation module in order to be processed and checked by the evaluation module. In this case, the individual cells of the battery simulator or the battery can be selected via an isolating module having individual isolating stages, so that an operation can be carried out by the evaluation module. By means of the isolating module, the evaluation module can connect to a selected cell of the battery simulator or the battery, and therefore the cell voltage potential is identical to that of the voltage rail, in particular to that of the rail+ potential and the rail− potential. 
         [0011]    By means of the evaluation module, different variants of the adjustment, monitoring and processing any cell of a battery simulator or battery selected via the isolating module can be carried out. In terms of implementation, the evaluation module can operate according to a floating ground concept. In this case, all data from a selected cell are captured, controlled, and manipulated by the evaluation module. The decisive aspect of this concept is that the feedback can be compared via a setpoint-actual value comparison and the cell can be correctly controlled in accordance with the values. The reference point can be located at the negative pole of the selected cell. In this case, the evaluation module in a battery control device test can carry out a cell voltage specification with voltage feedback and can carry out a test of the balancing current for the selected cell with current, for example 100 mA, and a current measurement. In a battery test, the evaluation module can test a measurement of the cell voltages and can test the balancing current using current specifications. In addition, further quantities such as a temperature can be detected via the bus by means of a suitable expansion via switches. 
         [0012]    In this way, a test apparatus for checking a battery control device or for checking a battery can be provided, which has a simple design and can check all the cells of a simulated or real battery in a simple manner. 
         [0013]    In particular, the test apparatus can be supplied with a specifiable voltage via a voltage supply module. The voltage supply module can provide, in particular, a voltage for the battery control device, for example 48 V. In addition, the voltage supply module can provide a general voltage supply for the remaining digital modules of the test apparatus, for example, a voltage of 5 V. 
         [0014]    In one preferred embodiment, the processing and checking by the evaluation module can be coordinated via a control module. The control module can comprise a central computer, in particular a microcontroller. The central computer functions as a control and communication unit and can receive measured values from all modules of the test apparatus and can send commands for processing to the modules. In this way, a separate central processing unit for each individual module can be dispensed with. The communication by the evaluation module with the central computer can take place via optocouplers. The central computer can function as the coordinator and can establish the test sequence. For example, the actual value determined by the battery control unit can be transmitted to the central computer via CAN, i.e., a controller area network. CAN is a serial bus system and belongs to the field busses. 
         [0015]    It is preferred that a voltage of a selected cell of the battery simulator or the battery can be changed via a resistor network having at least one controllable optical field effect transistor. In particular, by means of the at least one controllable optical field effect transistor, a selective change of a simulated cell resistance can take place by utilizing a resistance characteristic curve of the optical field effect transistor. With the aid of the optical field effect transistor (optical-coupled MOS FET), the cell voltage of a selected cell can be adjusted in a simple way. By means of feedback via the central computer, a regulation to the desired resistance and, therefore, the voltage value can be carried out for any cell. The resistor network can be supplied with current with the aid of a constant-current module. A cell voltage of a selected cell can be individually changed by means of the resistor network. The current value and, therefore, the supply voltage for the battery control device can be specified by the central computer of the control module. The cell voltage can take place via a drop in resistance at resistors in conjunction with a current supply. During a battery test, the resistor network is decoupled from the constant-current module. The resistor network receives the voltage from the battery instead. 
         [0016]    It is preferred that a value for a balancing current in the charging direction of the cell or in the discharging direction of the cell can be specified via the evaluation module, wherein the evaluation module can control the balancing current for each cell of the battery simulator for the battery control device or for each cell of the battery, independently of an adjacent cell. The balancing current ensures, in a battery, in particular in a battery pack of a rechargeable battery, that the cells all have a uniform voltage. In order to increase the nominal voltage, batteries usually consist of multiple series-connected individual cells or cell blocks. For production-related reasons, there are fluctuations in the capacitance and the internal resistance of these cells. In the practical use of multi-cell, series-connected batteries, this situation results in the cells being discharged and charged differently and being capable of assuming critical states of charge. In this case, the different voltage levels of the individual cells within a series interconnection during discharge result in the danger of the total discharge of individual cells. Series-connected cells also do not reach the same final voltage of charging when they are jointly charged, which can result in individual cells being overcharged. Given that the evaluation module can control the balancing current for each cell of the battery simulator or the battery cell independently of an adjacent cell, different balancing methods can be implemented by the adjusting device by means of current specifications. For example, the adjusting device can forward the balancing current to the subsequent cell in accordance with the specification of the battery control device, and therefore the balancing current always flows through the entire battery or through the entire battery simulator. In addition, a selective balancing method can be applied, and therefore the current can be drawn from a predetermined cell and forwarded directly to other selected cells, without involving adjacent cells or other cells during the balancing process. 
         [0017]    In one preferred embodiment, the evaluation module comprises a capacitor for the intermediate storage of a voltage for the balancing current. In this way, the balancing function can be expanded. As a result, a balancing for each cell can be carried out selectively, independently of the adjacent cell. An additional charging or discharging can take place via a capacitor. For example, an additional charging to a higher voltage level can take place via a DC/DC converter, in order to achieve a higher storage capacity and a high voltage for balancing. 
         [0018]    Preferably, the evaluation module can be connected to a temperature module for detecting at least one temperature measured by the battery control device or a temperature of at least one cell of the battery. The cell temperature can take place, in this case, either via individual modules, in particular temperature sensors, each of which individually measures the temperatures of each cell and forward this to the evaluation module. In addition, a temperature simulation can correspond to a resistance change, which take place via optical field effect transistors in order to simulate the cell voltage. Feedback of the current value of the optical field effect transistors to the evaluation module always takes place in this case. 
         [0019]    It is preferred that the test apparatus comprises a matrix for assigning a supply voltage for the monitoring device. In this way, any cell distribution configuration can be implemented with the aid of the monitoring device. With the aid of a matrix, a decoupling of the current supply of the CSC chips in the battery control device can be made possible, whereby no reaction by a withdrawn current to the cell voltages can take place. The CSC supply voltages and the supply currents can be measured and transmitted to the central computer. 
         [0020]    Preferably, a specification of any temperatures for selected cells as voltage or resistance values with feedback is made possible by the evaluation module. In particular, the evaluation module can establish a selection connection to the temperature module via a relay. A selection with a temperature specification can take place in such a way that the evaluation unit assigns a temperature to a selected cell via changeable voltage or resistance values, while the non-selected cells are assigned a voltage via a fixed resistance. By means of the feedback of the values, the evaluation unit can adjust the temperature for the selected cell by changing a voltage or resistance. In this case, the evaluation unit can be controlled using an associated voltage level. 
         [0021]    In one preferred embodiment, the test apparatus comprises a communication unit for communication with an external operating element. The communication unit can be a Bluetooth interface, a wireless LAN network, or an external CAN. A wireless LAN network is a local radio network. The test apparatus can be globally controlled with the aid of the external operating element. In this way, the test system can be designed to be compact, because it is not necessary to fixedly connect external operating elements to the test apparatus. In addition, the test apparatus can be disposed at a distance from the external operating element, and therefore, for example, the operating element and the test apparatus can be disposed in two different rooms. The data from the test apparatus can also be evaluated with the aid of the external operating element. 
         [0022]    In addition, the invention relates to a method for testing a battery control device or for testing a battery in a test apparatus which is refined or designed as described above, including the following steps of:
       connecting a battery control device to the test apparatus or connecting a battery having at least one cell to the test apparatus; and   processing or checking the battery control device or the battery via an evaluation module of the test apparatus.       
 
         [0025]    In this way, a method comprising a test apparatus for checking a battery control device or for checking a battery can be provided, wherein the test apparatus has a simple design and can check all the cells of a simulated or real battery in a simple manner. 
         [0026]    In one preferred embodiment, the method includes the following step of:
       adjusting a balancing current for at least one selected cell of the battery simulator or the battery independently of an adjacent cell.       
 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0028]    The invention is explained in the following, by way of example, with reference to the attached figures and on the basis of preferred exemplary embodiments, wherein the features presented in the following can depict an aspect of the invention individually or in different combinations with one another. In the drawings: 
           [0029]      FIG. 1  shows a schematic drawing of a test apparatus. 
       
    
    
     DETAILED DESCRIPTION 
       [0030]      FIG. 1  shows a schematic drawing of a test apparatus  8 , to which a test module  30  is connected. The test apparatus  8  is depicted in  FIG. 1  as a schematic modular drawing. The individual modules of the test module are depicted as blocks. The test module  30  is intended to depict either a battery control device or a battery which is supposed to be tested by the test apparatus  8 . The test apparatus  8  comprises an evaluation module  14 , a resistor network  16 , a battery simulator  18 , a temperature module  20 , a relay module  22 , an isolating module  24 , and a control module  26 . In addition, the test module comprises a non-illustrated central voltage rail, a so-called rail comprising rail+ and rail−, to which the individual cells of the battery simulator or the battery can be connected and, in this way, are connected to the evaluation module  14 , in order to be processed and checked by the evaluation module  14 . 
         [0031]    The test apparatus  8  is supplied with current with the aid of a voltage supply  10  and a constant-current module  12 . The constant-current module  12  is supplied with a voltage and with current via the voltage supply module  10 . This is indicated by an arrow from the voltage supply module  10  to the constant-current module  12 . The module  12  likewise delivers the supply voltage for the battery control device  30 . 
         [0032]    The voltage supply module  10  is supplied with a voltage of 7 volts to 19 volts with the aid of an external power supply unit. This is indicated by an arrow. With the aid of the voltage supply module  10 , a battery control device having a basic voltage according to a battery simulator is supplied with a battery pack voltage specified by the control module  26 . In addition, the voltage supply module  10  supplies the remaining digital modules with a voltage of 5 V. The supply voltage  10  can also provide a voltage of 1.5 V for optocouplers for the through-switching of signals from the isolating module  24 . 
         [0033]    The constant-current module  12  generates a constant current for the resistor network  16 . In addition, the total current of a battery control device can be measured with the aid of the constant-current module  12 . The constant-current module  12  is controlled by means of a central computer of the control module  26 . The constant-current module  12  can comprise a switching module to enable different test modes to be carried out using the test apparatus  8 . The different test modes are a pure test mode for the battery control device by supplying constant current, or a test mode for the battery, wherein in this case, the resistor network  16  and the test module  30  are separated from the voltage supply by the constant-current module  12 . The relationships of the constant-current module  12  with the resistor network  16 , the adjusting device  26 , and the battery control device  30  are depicted as arrows. The dashed arrow between the constant-current module  12  and the test module  30  is supposed to illustrate that the constant-current module  12  provides a voltage to the resistor network  16  and the test module  30  only during a battery control device test. During a battery test, the individual cells of the battery provide the voltage. 
         [0034]    Both the battery control device and, simultaneously, the battery can be connected via separate connectors to a change-over via a relay for disconnection from the resistor network  16 . 
         [0035]    The evaluation module  14  has various different variants for adjusting and monitoring any cell of a battery simulator or battery selected via the isolating module  24 . Essential to the implementation is the floating ground concept for the detection, control, and manipulation of the selected cell. The evaluation module  14  can operate according to a floating ground concept. In this case, all data from a specified cell are captured, controlled, and manipulated by the evaluation module  14 . The decisive aspect of this concept is that the feedback can be compared via a setpoint-actual value comparison, and the cell can be correctly controlled in accordance with the values. The reference point can be located at the negative pole of the selected cell. The communication of the evaluation module  14  with the central computer of the control module  26  takes place via optocouplers. The central computer of the control module  26  functions as a coordinator and specifies the test sequence. The actual value ascertained by the test module  30  is transmitted to the central computer via CAN. This is depicted in  FIG. 1  as a dashed arrow between the control module  26  and the test module  30 . The evaluation module  14  makes it possible, during a battery control device test, to specify a cell voltage with voltage feedback and a test balancing of a cell with a current, for example, 100 mA, and to measure current. During a battery test, the evaluation module  14  makes it possible to measure the individual cells of the battery and to implement different balancing methods with current specification. Either the current is forwarded to the subsequent cell, and so the current flows through all the cells of the battery, or selective balancing takes place, and so the current is drawn from a predetermined cell and is supplied to a further specified cell. With the aid of the evaluation module  14 , the current of a cell is measured both during the withdrawal and during the supply. In one alternative embodiment, the evaluation module  14  comprises a microcontroller for carrying out the operations. The evaluation module  14  is connected to the control module  26  with the aid of a serial peripheral interface (SPI). In this way, the interfaces between the evaluation module  14  and the control module  26  are reduced, and an evaluation of the measured values takes place directly in the evaluation module  14 . In one further embodiment of the evaluation module  14 , the evaluation module  14  comprises a capacitor for the intermediate storage of a voltage. The balancing function can therefore be expanded, whereby the balancing can be carried out selectively for each cell, independently of the adjacent cell. In addition, a charging and discharging also takes place by way of the capacitor. The charging takes place by way of a DC/DC converter to a higher level, in order to achieve a higher storage capacity and a high voltage for balancing. The relationships between the evaluation module  14 , the control module  26 , and the isolating module  24  are depicted in  FIG. 1  as double arrows. 
         [0036]    The resistor network  16  is supplied with current via the constant-current module  12 . As a result, a voltage of a cell of a battery simulator or a battery can be changed without changing the voltages of the other cells. The current value itself can be specified and monitored by a central computer of the control module  26 . The voltage for the individual cells can be generated via a voltage drop at resistors in conjunction with a current supply in the resistor network  16 . The resistance control takes place between two adjacent connectors in the resistor network  16 , in order to reduce a cell voltage. The change takes place via optocouplers in this case. Voltage feedback takes place by means of the evaluation module  14  with selection of the cell to be considered via the isolating module  24 . The relationships of the resistor network  16  with the constant-current module  12 , the battery simulator  18 , and the isolating module  24  are depicted in  FIG. 1  as arrows. 
         [0037]    The battery simulator  18  makes it possible to select voltages of the resistor network  16  having downstream optocouplers for supplying the CSC chips in the battery control device. As a result, there is no reaction by the withdrawn current to the cell voltage. The CSC supply voltage and supply currents are measured and are transmitted to the central computer in the control module  26 . The voltage for the CSC chips is implemented in the battery simulator  18  via a matrix having a crosspoint structure. In this case, horizontal lines represent the cell voltages and the intersecting, vertical lines represent the supply of the CSC chips. In addition, the voltage selector  18  comprises an operational amplifier for supplying the CSC chips. The relationships of the battery simulator  18  with the resistor network  16 , the control module  26 , and the test module  30  are depicted in  FIG. 1  as arrows. 
         [0038]    The temperature module  20  is used for simulating the temperature of the test module  30 . In this case, two alternative embodiments are possible. In one first embodiment, the temperature detection is carried out by individual modules, each of which individually measures the temperatures of each cell and forwards these to the control module  26 . In one further embodiment, the temperature simulation takes place via a change in resistance, which takes place via optical field effect transistors for simulating the cell voltage. In this case, a feedback of the current value of an operational amplifier to the control module  26  always takes place. The relationships of the temperature module  20  with the test module  30  and the control module  26  are depicted in  FIG. 1  as double arrows. 
         [0039]    The starting of the engine of the motor vehicle and the charging of the battery of the motor vehicle are simulated with the aid of the relay module  22 . The signals for the simulation come either via a hardware switch, via a microcontroller having the signals “start” and “charge” or directly from a connected vehicle. In addition, the relay module  22  can comprise a relay which displays the simulation of starting and charging via an LED display and forwards a feedback to the control module  26 . The relationships of the relay module  22  with the test module  30  and the control module  26  are depicted in  FIG. 1  as double arrows. 
         [0040]    The isolating module  24  comprises individual isolating stages and is disposed between the evaluation module  14  and the resistor network  16 . Via the isolating module  24 , any cell of a battery simulator or a battery can be connected to the evaluation module  14 , and therefore the cell voltage potential is identical to the rail+ potential and the rail− potential. The remaining cell voltages are not influenced as a result. The relationships between the isolating module  24 , the evaluation module  14 , the resistor network  16 , and the control module  26  are depicted as double arrows. 
         [0041]    The control module  26  comprises a central computer. The central computer is a microcontroller. The control, monitoring, and communication of the test apparatus  8  with the other modules takes place with the aid of the control module  26 . The control module  26  functions as a control and communication unit of the test apparatus  8 . The control module  26  comprises a communication unit for communication with the external operating element  28  via WLAN or Bluetooth. The relationships between the control module  26 , the constant-current module  12 , the evaluation module  14 , the battery simulator  18 , the temperature module  20 , the relay module  22 , the isolating module  24 , the external operating module  28 , and the test module  30  are depicted in  FIG. 1  as arrows. 
         [0042]    The external operating element  28  can be a tablet PC, an external computer, a smartphone, or another operating element which can connect wirelessly to the control module  16  via WLAN or Bluetooth. 
         [0043]    The test module  30  is either the battery control device to be tested or the battery to be tested.