JP5365263B2 - Battery management system - Google Patents

Description

  The present invention relates to a battery management system that manages a state of an assembled battery.

  As a power source mounted on an electric vehicle or a hybrid car, an assembled battery in which a plurality of single cells are electrically connected in series is used. In this type of battery pack, in order to monitor the state of the battery, a cell controller provided corresponding to each unit cell and connected in series from the upper level to the lower level, the uppermost cell controller and the lowermost cell controller And a battery controller connected to each other constitute a system for managing the assembled battery. In this system, the battery controller manages the state of each individual cell and the entire assembled battery based on the battery state (for example, voltage state) detected by each cell controller (see, for example, Patent Document 1). ).

JP 2003-59469 A

  However, each cell controller sequentially detects the state from the upper level to the lower level. However, when the detection timing and the noise generation timing are synchronized, there is a disadvantage that the state of the battery cannot be detected correctly.

  The present invention has been made in view of such circumstances, and an object thereof is to correctly detect the state of the battery by detecting the state of the battery while avoiding the influence of noise.

  In order to solve this problem, in the battery management system of the present invention, the state detection command is transmitted from the upper side to the lower side by transmitting a state detection command from the battery controller to the uppermost cell controller. The data is transmitted between the controllers using cascade communication. Here, each cell controller operates at a clock frequency shifted from 1 / N (N is a natural number) times the switching frequency of the power converter connected to the assembled battery.

  ADVANTAGE OF THE INVENTION According to this invention, the situation where the permutation detection timing by each cell controller and the timing of switching operation of a power converter device mutually synchronize can be suppressed. Thereby, since a state detection can be performed at the timing when the influence of noise was suppressed, the improvement of the detection accuracy regarding each single cell can be aimed at.

Configuration diagram schematically showing an electric vehicle to which a battery management system is applied The flowchart which shows the procedure of the voltage detection process of the assembled battery 1. Flow chart showing the detailed procedure of the sweep process Flow chart showing the procedure of voltage calculation processing Explanatory drawing which shows notionally the detection timing of the voltage value by cell controller CC1-CCn. Explanatory drawing which shows notionally the detection timing of the voltage value by cell controllers CC1-CCn at the time of the vehicle non-running Illustration of offset time T1 Explanatory drawing which shows notionally the detection timing of the voltage value by cell controller CC1-CCn at the time of driving | running | working of a vehicle. Configuration diagram schematically showing an electric vehicle to which a modification of the battery management system is applied

  FIG. 1 is a configuration diagram schematically showing an electric vehicle to which a battery management system according to an embodiment of the present invention is applied. The electric vehicle is driven by supplying electric power of the assembled battery 1 to a three-phase synchronous motor (vehicle driving motor) 6. Specifically, the inverter 2 that performs power conversion between the assembled battery 1 and the three-phase synchronous motor 6 is configured mainly with a plurality of switching elements (semiconductor switching elements), and receives DC power from the assembled battery 1. The AC power is converted into AC power, and the converted AC power is supplied to the three-phase synchronous motor 6. When the three-phase synchronous motor 6 is rotationally driven by the supplied AC power, the left and right drive wheels (not shown) are rotated via a speed reducer (not shown).

  The assembled battery 1 is configured by connecting a plurality of unit cells C1 to Cn in series. The assembled battery 1 is provided with cell controllers CC1 to CCn corresponding to the single cells C1 to Cn, respectively. When the unit cell C1 is the upper side and the unit cell Cn is the lower side, the individual cell controllers CC1 to CCn are connected in series from the upper side to the lower side. The cell controllers CC1 to CCn are activated when the activation signal from the battery controller 3 is turned on. When the activation signal is turned off, the cell controllers CC1 to CCn are also turned off. The individual cell controllers CC1 to CCn use the corresponding single cells C1 to Cn as power sources.

  Each cell controller CC1-CCn detects the battery state (in this embodiment, voltage value) of the unit cell 1 provided corresponding to itself. Specifically, each cell controller CC1 to CCn is connected between both terminals of the corresponding unit cells C1 to Cn, and when receiving a voltage detection command, the corresponding unit cells C1 to Cn. The voltage value of is detected.

  The voltage detection command is transmitted in a cascade manner between the adjacent cell controllers CC1 to CCn from the upper side to the lower side when the battery controller 3 described later transmits the voltage detection command to the uppermost cell controller CC1. The Specifically, when each cell controller CC1 to CCn receives a voltage detection command from the upper cell controllers CC1 to CCn, each cell controller CC1 to CCn detects a voltage value related to the corresponding single cells C1 to Cn. In addition, each cell controller CC1 to CCn transmits a voltage detection command to the adjacent lower cell controllers CC1 to CCn, and voltage data transmitted from the upper cell controllers CC1 to CCn (each higher side than itself). The voltage values detected by the cell controllers CC1 to CCn) and the voltage value detected by itself are transmitted as voltage data.

  As one of the features of this embodiment, each of the cell controllers CC1 to CCn operates at a clock frequency lower than the switching frequency of the inverter 2 controlled using the pulse width modulation method, and more specifically. Operates at a clock frequency shifted from 1 / N (N is a natural number) times the switching frequency of the inverter 2. Therefore, once the voltage detection command transmitted by cascade communication in the cell controllers CC1 to CCn from the upper level to the lower level is received by a certain cell controller CC1 to CCn, after a predetermined period corresponding to the clock frequency has elapsed, It is transmitted to the lower cell controllers CC1 to CCn. Therefore, the voltage detection operations executed by the individual cell controllers CC1 to CCn are also sequentially executed from the upper level to the lower level cell controllers CC1 to CCn while offsetting the timing by a predetermined period corresponding to the clock frequency.

  The battery controller (BC) 3 is mainly composed of a CPU, a ROM, a RAM, and an I / O interface. The battery controller 3 is connected to the highest cell controller CC1 and the lowest cell controller CCn. The battery controller 3 is detected by the cell controllers CC1 to CCn from the upper level to the lower level through cascade communication by the individual cell controllers CC1 to CCn by outputting a voltage detection command to the uppermost cell controller CC1. Each voltage value (voltage data) is received from the lowest cell controller CCn. Thereby, the battery controller 3 manages the assembled battery 1 whole based on the detection result of each cell controller CC1-CCn. The battery controller 3 uses an auxiliary battery (Ba) 7 as a power source.

  In the present embodiment, communication between the battery controller 3 and each of the cell controllers CC1 to CCn is performed by a serial transmission method. This is to obtain the latest data of the plurality of single cells C1 to Cn with the number of communication lines being minimized.

  The torque processing controller (TPC) 4 is mainly composed of a CPU, a ROM, a RAM, and an I / O interface. The torque processing controller 4 calculates the torque command value of the three-phase synchronous motor 6 based on the detection result of the sensor (AP) 8 that detects the amount of depression of the accelerator pedal (accelerator opening), vehicle speed information, and the like.

  The calculated torque command value is transmitted to the motor controller (MC) 5. The motor controller 5 supplies a current to be supplied from the inverter 2 to the three-phase synchronous motor 6 based on the torque command value sent from the torque processing controller 4, the rotational position information of the three-phase synchronous motor 6, brake information, and the like. Calculate the command value. And the motor controller 5 controls the switching element (semiconductor switching element) with which the inverter 2 is provided based on the calculated electric current command value using a pulse width modulation method.

  FIG. 2 is a flowchart showing a procedure of voltage detection processing of the assembled battery 1. In the voltage detection process of the assembled battery 1, the battery controller 3 functions as a battery management system that detects voltages related to the individual cells C1 to Cn by cooperating with the cell controllers CC1 to CCn.

  First, in step 10 (S10), the battery controller 3 performs a sweep process. FIG. 3 is a flowchart showing a detailed procedure of the sweep process. First, in step 20 (S20), standby processing according to the standby parameter n is performed. The waiting parameter n is a parameter for setting a predetermined waiting time, and the time obtained by the integrated value of a predetermined reference time (offset time T1 described later) and the waiting parameter n according to the waiting parameter n is a waiting time. Set as After waiting for the set waiting time, the battery controller 3 proceeds to step 21 (S21).

  In step 21, the battery controller 3 updates the standby parameter n with a value obtained by adding “1” to the current standby parameter n. In step 22 (S22), the battery controller 3 determines whether or not the standby parameter n has reached the determination value nth. If the standby parameter n has not reached the determination value nth, step 23 (S23) to be described later is skipped and the routine is exited. On the other hand, if the standby parameter n has reached the determination value nth, the process proceeds to step 23. In step 23, the battery controller 3 resets the standby parameter n to “0”.

  Referring to FIG. 2 again, in step 11 (S11), the battery controller 3 transmits a voltage detection command to the uppermost cell controller CC1. In step 12 (S12), the battery controller 3 determines whether or not voltage data has been received from the lowest cell controller CCn. When voltage data is received from the lowest cell controller CCn, an affirmative determination is made in this step, and thus the process proceeds to step 13 (S13).

  In step 13, the battery controller 3 is configured to associate the detected voltage values with respect to the detected single cells C <b> 1 to Cn with respect to the voltage values detected for the individual single cells C <b> 1 to Cn based on the received voltage data. The data are stored in an array in a storage means such as a ROM. Note that the battery controller 3 can store the voltage values (voltage data) of the single cells C1 to Cn corresponding to one voltage detection command in time series, and thus the previously detected voltage data can be stored. You can refer to it.

  In step 14 (S14), the battery controller 3 performs voltage calculation processing. FIG. 4 is a flowchart showing a procedure of voltage calculation processing. First, in step 30 (S30), the battery controller 3 determines whether or not the vehicle is traveling. If a negative determination is made in step 30, that is, if the vehicle is not traveling, the process proceeds to step 31 (S31). On the other hand, if an affirmative determination is made in step 14, that is, if the vehicle is traveling, the process proceeds to step 33 (S33).

  In step 31, when one battery cell C1 to Cn to be processed is specified from the single cells C1 to Cn, the battery controller 3 performs an averaging process on the specified single cells C1 to Cn. Specifically, the battery controller 3 extracts a plurality of voltage values detected previously as candidate data. Next, the battery controller 3 refers to the current value of the average value data calculated by the calculation described later, that is, the average value data calculated in the previous processing cycle, and the voltage value deviated from the average value data by a predetermined value or more. Are removed from the candidate data as non-standard data. In step 32 (S32), the battery controller 3 calculates an average value of the voltage values based on the candidate data from which the nonstandard data is excluded, and sets this as average value data. The battery controller 3 performs such an averaging process for all the unit cells C1 to Cn constituting the assembled battery 1.

  On the other hand, when the battery controller 3 specifies one single cell C1 to Cn to be processed from the single cells C1 to Cn in step 33, the battery controller 3 performs an averaging process on the specified single cells C1 to Cn. I do. Specifically, the battery controller 3 extracts a plurality of voltage values detected previously as candidate data. And the battery controller 3 calculates the average value of a voltage value based on candidate data, and sets this as average value data. The battery controller 3 performs such an averaging process for all the unit cells C1 to Cn constituting the assembled battery 1.

  In step 34 (S34), the battery controller 3 stores the average value data relating to the individual cells C1 to Cn in a storage means such as a ROM so as to associate each cell C1 to Cn with the average value data. To do.

  Referring to FIG. 2 again, the highest cell controller CC1 performs the following processing in parallel with the battery controller 3 according to its own control cycle. Specifically, in step 40 (S40), the cell controller CC1 determines whether or not a voltage detection command has been received. When the cell controller CC1 receives a voltage detection command from the battery controller 3, an affirmative determination is made in step 40, and thus the process proceeds to step 41 (S41). On the other hand, when the cell controller CC1 has not received a voltage detection command from the battery controller 3, the routine is exited.

  In step 42 (S42), the cell controller CC1 detects a voltage value related to the unit cell C1 provided corresponding to itself. In step 43 (S43), the cell controller CC1 transmits a voltage detection command to the adjacent lower cell controller CC2, and also transmits voltage data, that is, a voltage value related to the unit cell C1.

  Also, the other cell controllers CC2 to CCn perform the above-described processing according to their own control cycle, similarly to the highest cell controller CC1. However, the cell controllers CC2 to CCn combine the voltage value detected by the cell controllers CC2 to CCn in step 42 with the voltage data transmitted from the upper cell controllers CC1 to CCn, and then the lower level. Transmit to cell controllers CC1 to CCn.

  Further, the lowest cell controller CCn performs the process of step 43 (S43) instead of the process of step 42. Specifically, in step 43, the lowest cell controller CCn sends the voltage value detected by itself to the voltage data (voltage values related to the cells C1 to Cn-1) transmitted from the upper cell controller CCn-1. Are transmitted to the battery controller 3.

  Hereinafter, the concept of the voltage detection process according to the present embodiment will be described. FIG. 5 is an explanatory diagram conceptually showing voltage value detection timings by the cell controllers CC1 to CCn. As shown in the figure, the voltage values of the cells C <b> 1 to Cn may include noise in the voltage value corresponding to the switching operation of the inverter 2. For example, when the clock frequency of each cell controller CC1 to CCn is set to 1 / N times the switching frequency of the inverter 2, in this system using cascade communication, the timing of the switching operation of the inverter 2 and each cell The timing of voltage detection operation (open arrows) in the controllers CC1 to CCn is synchronized. In this case, the voltage value detected by each of the cell controllers CC1 to CCn includes noise accompanying the switching operation, and the voltage value cannot be detected with high accuracy.

  However, according to the present embodiment, each of the cell controllers CC <b> 1 to CCn operates at a clock frequency shifted from the 1 / N times the switching frequency of the inverter 2 connected to the assembled battery 1. Therefore, the situation where the detection timing of each cell controller CC1 and the timing of the switching operation of the inverter 2 are synchronized with each other can be suppressed. Thereby, the detection accuracy regarding the cell 1 can be improved.

  However, for the purpose of noise removal, a microcomputer or the like may be used for each of the cell controllers CC1 to CCn, and the clock frequency may be set higher than the switching frequency of the inverter 2 and shifted from the N-fold value. . However, in this case, the power consumption is large due to the high frequency, and there is a risk that the electric capacity of each unit cell 1 may vary. Therefore, each of the cell controllers CC <b> 1 to CCn is preferably a controller that operates at a clock frequency lower than the switching frequency of the inverter 2.

  In addition, there is also an averaging technique as a general idea for suppressing the influence of noise. However, as shown in the present embodiment, when cell controllers CC1 to CCn that perform cascade communication and operate at a clock frequency lower than the switching frequency of the inverter 2 as described above, switching is performed. Since the cell controller on which noise is superimposed is always affected, it is difficult to reduce the influence of noise even if averaging is performed.

  Furthermore, as a philosophy to suppress the influence of noise in general, there is a configuration through a filter. However, in the configuration having a plurality of cell controllers as in this embodiment, the number of filters increases, and the volume increases. This will increase the cost and cost.

  Therefore, in the present embodiment, it is an object to enable noise removal using cell controllers CC1 to CCn that operate at a clock frequency lower than the switching frequency of the inverter 2 and consume less power, and do not require a filter. And the above configuration.

  FIG. 6 is an explanatory diagram conceptually showing voltage value detection timings by the cell controllers CC1 to CCn. Here, (a) shows transition of the voltage value regarding the cell controllers CC1 to CC5 corresponding to the voltage detection command output from the battery controller 3 at a certain timing. (B) shows transition of the voltage value regarding the cell controllers CC1 to CC5 corresponding to the voltage detection command output from the battery controller 3 at a timing after one cycle (control cycle) from the timing of (a). (C) shows the transition of voltage values related to the cell controllers CC1 to CC4 corresponding to the voltage detection command output from the battery controller 3 at a timing one cycle after the timing of (b).

  In the present embodiment, the battery controller 3 periodically transmits a voltage detection command to the highest cell controller CC1. In this case, the battery controller 3 is delayed by the offset time T1 from the reference timing at which one period (control period) has elapsed from the transmission timing of the immediately preceding voltage detection command, as shown in FIG. The next voltage detection command is transmitted at the timing (sweep process). Therefore, as shown in FIG. 6C, for a voltage detection command after two cycles with respect to a certain voltage detection command, a time of two cycles (control cycle) has elapsed from the transmission timing of the initial voltage detection command. The voltage detection command is transmitted at a timing delayed by twice the offset time T1 (T2) from the reference timing.

  For example, when the voltage detection command transmitted from the battery controller 3 is transmitted at the reference timing according to the control cycle, the timing of the detection operation for a specific cell controller CC1 to CCn is the switching operation of the inverter 2. There is a risk of synchronization with the timing. In that respect, according to the present embodiment, by providing a delay time with respect to the reference timing, the timing of the detection operation for the specific cell controllers CC1 to CCn is synchronized with the timing of the switching operation of the inverter. The situation can be suppressed. Thereby, a voltage can be detected with high precision about all the unit cells C1 to Cn constituting the assembled battery 1.

  FIG. 7 is an explanatory diagram of the offset time T1. The offset time T1 can be set so that the time required for sampling a predetermined number of times for the cell controllers CC1 to CCn is longer than the duration of noise (see the following equation).

(Formula 1)
Noise duration <(1 / cell controller operating clock frequency × N) × sampling number M
In this equation, N is a natural number, and the offset time T1 may be set to a clock greater than N. For example, when the number of samplings is set to 2 and it is desired to make it larger than the elapsed time of noise, N is 5 or more if the noise duration is 10 μsec and the clock frequency of the cell controllers CC1 to CCn is 1 MHz. That is, the offset time T1 may be set to a time of 5 clocks or more.

  Further, in the present embodiment, the battery controller 3 extracts a plurality of previously detected voltage detection values as candidate data, and the average value of the extracted candidate data is the voltage value of each of the single cells C1 to Cn. Manage as. According to this configuration, since the influence of noise is suppressed by using the average value, it is possible to manage the states of the individual cells C1 to Cn in a state close to the actual voltage value.

  Further, according to the present embodiment, referring to FIG. 6 again, when the vehicle is in a non-running state, the current voltage values (average value data) of the cells C1 to Cn are extracted from the extracted candidate data. The detected voltage value deviating from the threshold value by more than the threshold value is deleted. And the battery controller 3 calculates average value data based on the candidate data after deletion. When the vehicle is not traveling, there is little change in voltage over time for each of the cells C1 to Cn. Therefore, it is possible to eliminate voltage detection values that deviate from the average value data, that is, voltage detection values that are affected by noise. Thereby, voltage detection can be performed with high accuracy.

  FIG. 8 is an explanatory diagram conceptually showing detection timings of voltage values by the cell controllers CC1 to CCn during vehicle travel, and the states (a) to (c) correspond to those in FIG. On the other hand, when the vehicle is in a running state, the battery controller 3 calculates average value data based on the extracted candidate data. As shown in the figure, in the scene where the vehicle is in the running state, the voltage change of the cells C1 to Cn is large. Therefore, in such a scene, the influence of noise can be suppressed by calculating average value data based on all candidate data.

  FIG. 9 is a configuration diagram schematically showing an electric vehicle to which a modification of the battery management system according to the embodiment of the present invention is applied. In embodiment mentioned above, if each cell controller CC1-CCn manages the single cell C1-Cn separately, this invention is not limited to this. For example, each of the cell controllers CC1 to CCn may be divided into a plurality of cell units M1 to Mn each composed of a plurality of single cells C1 to Cm, and the cell units M1 to Mn may be managed individually. Good. In this case, the cell controllers CC1 to CCn may detect individual voltage values of the single cells C1 to Cm in the cell units M1 to Mn, or may detect their sum. That is, in embodiment mentioned above, it becomes a system implement | achieved by comprising each cell unit M1-Mn by the single cell C1-Cm.

DESCRIPTION OF SYMBOLS 1 ... Assembly battery C1-Cn (Cm) ... Single cell M1-Mn ... Cell unit CC1-CCn ... Cell controller 2 ... Inverter 3 ... Battery controller 4 ... Torque processing controller 5 ... Motor controller 6 ... Three-phase synchronous motor

Claims (5)

In the battery management system for managing the state of the assembled battery in which a plurality of cell units each composed of one or more single cells are connected in series,
A plurality of cell controllers that are provided corresponding to each of the cell units and are connected in series from the upper level to the lower level, and when receiving a state detection command, each of which detects a battery state of the corresponding cell unit,
A battery that is connected to the highest cell controller and the lowest cell controller among the plurality of cell controllers, and manages each state of the cell unit based on a battery state detected by each of the cell controllers. A controller,
The state detection command is transmitted in cascade communication between adjacent cell controllers from the upper side to the lower side when the battery controller transmits the state detection command to the uppermost cell controller. And
Each of the cell controllers operates at a clock frequency shifted from 1 / N (N is a natural number) times a switching frequency of a power conversion device connected to the assembled battery.   The battery controller periodically transmits the state detection command to the uppermost cell controller, and the timing at which the next state detection command is transmitted is a reference in which one cycle has elapsed from the previous transmission timing. The battery management system according to claim 1, wherein the battery management system is set to a timing delayed from the timing. Each of the cell controllers detects a voltage value as a battery state of the cell unit,
The battery controller stores, for each cell unit, voltage values detected by the cell controller in time series, extracts a plurality of previously detected voltage values as candidate data, and the extracted candidates The battery management system according to claim 2, wherein an average value of data is managed as a voltage value of the cell unit. The power conversion device performs power conversion between the assembled battery and the drive motor for the vehicle,
When the vehicle is in a non-running state, the battery controller deletes, from the extracted candidate data, a voltage value that deviates more than a threshold value from the current voltage value of the cell unit, to the candidate data after deletion The battery management system according to claim 3, wherein an average value is calculated based on the battery.   The battery management system according to claim 3, wherein the battery controller calculates an average value based on the extracted candidate data when the vehicle is in a running state.

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