JP6575308B2 - Internal resistance calculation device, computer program, and internal resistance calculation method - Google Patents

Description

  The present invention relates to an internal resistance calculation device that calculates an internal resistance of a secondary battery, a computer program for realizing the internal resistance calculation device, and an internal resistance calculation method.

  In recent years, vehicles such as HEV (Hybrid Electric Vehicle) and EV (Electric Vehicle) are becoming widespread. HEV and EV are equipped with secondary batteries. As the vehicle travels, charging and discharging of the secondary battery are repeated. When overdischarge or overcharge is performed, the secondary battery is deteriorated. Therefore, it is necessary to control charge / discharge while grasping the charge amount of the secondary battery. Moreover, in order to determine the deterioration of the secondary battery, it is necessary to accurately grasp the internal resistance of the secondary battery.

  Since the state of the secondary battery after the charge / discharge switching is unstable, an arithmetic device that calculates the internal resistance of the secondary battery based on the voltage and current detected after a lapse of a predetermined time from the charging / discharging switching time is disclosed. (See Patent Document 1).

JP 2011-257219 A

  However, in the device as disclosed in Patent Document 1, for example, 100 ms is used as the sampling period when detecting the voltage and current of the secondary battery. However, since the actual voltage and current fluctuate in a cycle shorter than the sampling cycle, it is unknown where the voltage value and current value obtained by sampling are in the fluctuation range of the voltage and current of the secondary battery. In some cases, the internal resistance value cannot be accurately calculated.

  The present invention has been made in view of such circumstances, and an internal resistance calculation device capable of accurately calculating the internal resistance of a secondary battery, a computer program for realizing the internal resistance calculation device, and an internal resistance An object is to provide a calculation method.

  An internal resistance calculation apparatus according to an embodiment of the present invention is an internal resistance calculation apparatus that calculates an internal resistance of a secondary battery, and acquires the voltage and current of the secondary battery at a predetermined first sampling period. A first sampling period when the acquisition unit acquires voltage and current when the estimation unit estimates that there is switching. A change unit for changing to a second sampling cycle shorter than the first sampling cycle, and switching of charging and discharging of the secondary battery based on the current acquired by the acquisition unit in the second sampling cycle changed by the change unit. A switching detection unit to detect, and when the switching detection unit detects charging / discharging switching, the voltage and current acquired by the acquisition unit before the charging / discharging switching time of the secondary battery, and charging / discharging of the secondary battery. Discharge switching point Based on Luo predetermined voltage the acquisition unit has acquired after the elapse of the waiting time and current, and a resistance calculation unit for calculating the internal resistance of the secondary battery.

  A computer program according to an embodiment of the present invention is a computer program for causing a computer to calculate an internal resistance of a secondary battery, and the computer is configured to perform voltage and current of the secondary battery at a predetermined first sampling period. The first sampling period when the acquisition unit acquires voltage and current when it is estimated that there is switching, an acquisition unit that acquires the acquisition unit that acquires the charge / discharge switching of the secondary battery A change detection unit that detects a change in charge / discharge of the secondary battery based on a current acquired by the acquisition unit in the changed second sampling cycle, and a change unit that changes to a second sampling cycle shorter than the first sampling cycle And the voltage and current acquired by the acquisition unit before the charging / discharging switching time of the secondary battery when the switching of charging / discharging is detected, and the secondary battery Based on the charging and discharging voltage the acquiring unit from the switching time point after a predetermined waiting time has acquired the and current, to function as a resistance calculation unit for calculating the internal resistance of the secondary battery.

  An internal resistance calculation method according to an embodiment of the present invention is an internal resistance calculation method for calculating an internal resistance of a secondary battery, wherein the acquisition unit obtains the voltage and current of the secondary battery at a predetermined first sampling period. The estimation unit estimates the presence / absence of switching of charge / discharge of the secondary battery, and when it is estimated that there is switching, the first sampling period when acquiring the voltage and current is shorter than the first sampling period The change unit changes to the second sampling cycle, and the switching detection unit detects the switching of the charge / discharge of the secondary battery based on the current acquired by the acquisition unit in the changed second sampling cycle, When switching is detected, the voltage and current acquired before the charging / discharging switching time of the secondary battery, and the voltage and current acquired after elapse of a predetermined standby time from the charging / discharging switching time of the secondary battery. On the basis of the Resistance calculating unit the internal resistance of the secondary battery is calculated.

  According to the present invention, the internal resistance of the secondary battery can be calculated with high accuracy.

It is a block diagram which shows an example of a structure of the principal part of the vehicle carrying the battery monitoring apparatus as an internal resistance calculation apparatus of this Embodiment. It is a block diagram which shows an example of a structure of the battery monitoring apparatus as a secondary battery calculation apparatus of this Embodiment. It is explanatory drawing which shows an example of the current waveform of a secondary battery unit. It is explanatory drawing which shows an example of the current waveform by the side of the discharge at the time of expanding the time axis of the current waveform of FIG. It is explanatory drawing which shows an example of the sampling value of the electric current by the battery monitoring apparatus of this Embodiment. It is explanatory drawing which shows the 1st example of the estimation method of the presence or absence of switching of charging / discharging based on the electric current by the battery monitoring apparatus of this Embodiment. It is explanatory drawing which shows the 2nd example of the estimation method of the presence or absence of the switching of charging / discharging based on the electric current by the battery monitoring apparatus of this Embodiment. It is explanatory drawing which shows an example of the estimation method of the presence or absence of switching of charging / discharging based on the residual amount by the battery monitoring apparatus of this Embodiment. It is explanatory drawing which shows an example of the estimation method of the presence or absence of switching of charging / discharging based on the information regarding the idling stop by the battery monitoring apparatus of this Embodiment. It is a flowchart which shows an example of the process sequence of the battery monitoring apparatus of this Embodiment. It is a flowchart which shows an example of the process sequence of the battery monitoring apparatus of this Embodiment.

[Description of Embodiment of Present Invention]
An internal resistance calculation apparatus according to an embodiment of the present invention is an internal resistance calculation apparatus that calculates an internal resistance of a secondary battery, and acquires the voltage and current of the secondary battery at a predetermined first sampling period. A first sampling period when the acquisition unit acquires voltage and current when the estimation unit estimates that there is switching. A change unit for changing to a second sampling cycle shorter than the first sampling cycle, and switching of charging and discharging of the secondary battery based on the current acquired by the acquisition unit in the second sampling cycle changed by the change unit. A switching detection unit to detect, and when the switching detection unit detects charging / discharging switching, the voltage and current acquired by the acquisition unit before the charging / discharging switching time of the secondary battery, and charging / discharging of the secondary battery. Discharge switching point Based on Luo predetermined voltage the acquisition unit has acquired after the elapse of the waiting time and current, and a resistance calculation unit for calculating the internal resistance of the secondary battery.

  A computer program according to an embodiment of the present invention is a computer program for causing a computer to calculate an internal resistance of a secondary battery, and the computer is configured to perform voltage and current of the secondary battery at a predetermined first sampling period. The first sampling period when the acquisition unit acquires voltage and current when it is estimated that there is switching, an acquisition unit that acquires the acquisition unit that acquires the charge / discharge switching of the secondary battery A change detection unit that detects a change in charge / discharge of the secondary battery based on a current acquired by the acquisition unit in the changed second sampling cycle, and a change unit that changes to a second sampling cycle shorter than the first sampling cycle And the voltage and current acquired by the acquisition unit before the charging / discharging switching time of the secondary battery when the switching of charging / discharging is detected, and the secondary battery Based on the charging and discharging voltage the acquiring unit from the switching time point after a predetermined waiting time has acquired the and current, to function as a resistance calculation unit for calculating the internal resistance of the secondary battery.

  An internal resistance calculation method according to an embodiment of the present invention is an internal resistance calculation method for calculating an internal resistance of a secondary battery, wherein the acquisition unit obtains the voltage and current of the secondary battery at a predetermined first sampling period. The estimation unit estimates the presence / absence of switching of charge / discharge of the secondary battery, and when it is estimated that there is switching, the first sampling period when acquiring the voltage and current is shorter than the first sampling period The change unit changes to the second sampling cycle, and the switching detection unit detects the switching of the charge / discharge of the secondary battery based on the current acquired by the acquisition unit in the changed second sampling cycle, When switching is detected, the voltage and current acquired before the charging / discharging switching time of the secondary battery, and the voltage and current acquired after elapse of a predetermined standby time from the charging / discharging switching time of the secondary battery. On the basis of the Resistance calculating unit the internal resistance of the secondary battery is calculated.

  The acquisition unit acquires the voltage and current of the secondary battery at a predetermined first sampling period. The first sampling period can be, for example, 10 ms, but is not limited thereto.

  An estimation part estimates the presence or absence of switching of charging / discharging of a secondary battery. That is, the estimation unit predicts switching between charge and discharge before the charge and discharge of the secondary battery is actually switched. The charge / discharge switching is estimated by, for example, monitoring the direction of increase / decrease in the charge / discharge current over time, and setting a predetermined condition based on the absolute value of the current and the degree of temporal change (for example, increase or decrease). The time when it is satisfied can be set as the estimated time.

  A change part changes the 1st sampling period when an acquisition part acquires a voltage and an electric current into the 2nd sampling period shorter than the said 1st sampling period, when the estimation part estimates the presence or absence of switching of charging / discharging. For example, when the first sampling period is 10 ms, the second sampling period can be 1 ms, but the present invention is not limited to this.

  The switching detection unit detects charging / discharging switching of the secondary battery based on the current acquired by the acquisition unit in the second sampling period changed by the changing unit. For example, when either charge or discharge is defined as positive and the current changes from positive to negative or 0, the current changes from 0 to positive or negative, or the current changes from negative to positive or 0 Switching between charge and discharge can be detected.

  The resistance calculation unit detects the voltage Vb and current Ib acquired by the acquisition unit before the charging / discharging switching time of the secondary battery and the charging / discharging switching time of the secondary battery when the switching detection unit detects the switching of charging / discharging. The internal resistance of the secondary battery is calculated based on the voltage Vc and the current Ic acquired by the acquisition unit after a predetermined standby time elapses.

  The secondary battery can be represented by an equivalent circuit including an electrolyte bulk resistance Rs, an interface charge transfer resistance Rc, an electric double layer capacitance C, and a diffusion impedance Zw. The internal resistance of the secondary battery is mainly composed of the electrolyte bulk resistance Rs and the interface charge transfer resistance Rc. On the other hand, when the frequency is changed from a high frequency to a low frequency in an impedance spectrum obtained by plotting values obtained by measuring the impedance of the secondary battery at a plurality of frequencies using the AC impedance method, the diffusion impedance Zw Increases, and the impedance of the secondary battery increases. The standby time T can be obtained based on the boundary frequency region where the diffusion impedance Zw increases. The waiting time T can be set to, for example, 100 ms, but is not limited thereto.

  The absolute value of the slope of the straight line obtained from the voltage and current between the two points before and after switching between charge and discharge indicates the internal resistance of the secondary battery. Therefore, the internal resistance R is calculated by, for example, R = (Vc−Vb) / (Ic−Ib).

  With the above configuration, when it is estimated that there is a charge / discharge switching of the secondary battery, the sampling period is shortened at a time before the actual charge / discharge switching time, and the voltage and current are acquired. Since switching of charging / discharging is detected based on this, even when the voltage and current of the secondary battery fluctuate in a short cycle, it is possible to accurately detect the switching point of charging / discharging. Since the charging / discharging switching time point can be detected with high accuracy, the standby time T elapsed time point can also be specified with high accuracy, so that the voltage Vb and current Ib before charging / discharging switching and the charging / discharging switching time point can The voltage Vc and current Ic after the elapse of the predetermined standby time T can be accurately obtained, and the internal resistance of the secondary battery can be calculated with high accuracy.

  In the internal resistance calculation device according to an embodiment of the present invention, when the change unit detects charge / discharge switching by the switching detection unit, the change unit detects the first to the charge / discharge switching time estimated by the estimation unit. Change to 2 sampling periods.

  A change part changes to a 2nd sampling period from the estimation time which estimated the presence or absence of the switching of charging / discharging to the switching time of charging / discharging, when the switching detection part detects the switching of charging / discharging. Since the second sampling period is changed from the estimated time point to the charge / discharge switching time point, the charge / discharge switching time point can be accurately determined even when the voltage and current of the secondary battery fluctuate in a short period. And since the switching time of charging / discharging can be determined accurately, the voltage Vb and current Ib before charging / discharging switching can be acquired correctly. In addition, the point in time when the standby time T has elapsed can be specified with high accuracy.

  In the internal resistance calculation device according to an embodiment of the present invention, the change unit detects the second sampling period from the charging / discharging switching time to the standby time lapse time when the switching detection unit detects the switching of charging / discharging. Change to

  When the switching detection unit detects charging / discharging switching, the changing unit changes the second sampling period from the charging / discharging switching time to the time when the standby time T has elapsed. Since the second sampling period is changed from the charging / discharging switching time to the standby time T, even when the voltage and current of the secondary battery fluctuate in a short cycle, after the predetermined standby time T elapses from the charging / discharging switching time. Voltage Vc and current Ic can be obtained accurately, and the internal resistance of the secondary battery can be calculated accurately.

  In the internal resistance calculation device according to the embodiment of the present invention, when the change detection unit detects charge / discharge switching by the change detection unit, the change unit changes to the first sampling period after the change point of charge / discharge, The second sampling period is changed between the switching time and the standby time.

  When the switching detection unit detects charging / discharging switching, the changing unit changes to the first sampling period after the switching point of charging / discharging, and changes to the second sampling period between the switching point and the standby time T. . For example, when the charge / discharge switching time point is 0 ms and the standby time T is 100 ms, the time point (predetermined time point) between the switching time point and the standby time T elapsed time point can be the time point when 90 ms has elapsed from the charge / discharge switching time point. However, the present invention is not limited to this. When the predetermined time is 90 ms and the standby time T is 100 ms, the predetermined time is 10 ms before the standby time T.

  In order to accurately calculate the internal resistance of the secondary battery, it is necessary to more accurately detect the voltage and current after the standby time T has elapsed. If the sampling period is shortened after the charging / discharging switching time, the voltage and current can be reliably acquired with a short sampling period when the standby time T has elapsed. On the other hand, shortening the sampling period increases the processing effort. Therefore, by shortening the sampling cycle from the first sampling cycle to the second sampling cycle at a predetermined time point sufficiently before the standby time T (time point 10 ms before the standby time T of 100 ms). The time width for sampling the voltage and current with a short sampling period can be reduced, and the increase in processing effort can be suppressed while improving the calculation accuracy of the internal resistance of the secondary battery.

  The internal resistance calculation device according to an embodiment of the present invention includes an increase / decrease amount calculation unit that repeatedly calculates an increase amount or a decrease amount of current based on the current acquired by the acquisition unit a plurality of times in the first sampling period, In the estimation unit, when the acquired current is positive and the decrease amount calculated by the increase / decrease amount calculation unit is equal to or greater than a predetermined threshold, or the acquired current is negative and the increase / decrease amount calculation unit When the calculated increase amount is equal to or greater than a predetermined threshold, it is estimated that charging / discharging is switched.

  The increase / decrease amount calculation unit repeatedly calculates an increase amount or a decrease amount of the current based on the current acquired by the acquisition unit a plurality of times in the first sampling period. For example, the sampling time points are (t-2), (t-1), and (t) in time series, and the currents acquired at the respective sampling time points are I (t-2), I (t-1), and I (t ). If I (t-2) <I (t-1) <I (t), the current increases. Further, if I (t−2)> I (t−1)> I (t), the current decreases.

  When the acquired current is positive and the amount of decrease calculated by the increase / decrease amount calculation unit is equal to or greater than a predetermined threshold, the estimation unit estimates that charging / discharging is switched. The charging current is positive and the discharging current is negative. For example, when I (t)> 0 and I (t−1) −I (t) ≧ Th1, the charging current decreases and approaches 0A, so that there is a switching from charging to discharging. Can be estimated. Note that the estimated time point can be the sampling time point t, but is not limited thereto.

  The estimation unit estimates that charging / discharging is switched when the acquired current is negative and the increase amount calculated by the increase / decrease amount calculation unit is equal to or greater than a predetermined threshold. For example, when I (t) <0 and I (t) −I (t−1) ≧ Th1, the discharge current increases and approaches 0 A, and therefore there is a switch from discharge to charge. Can be estimated. Note that the estimated time point can be the sampling time point t, but is not limited thereto.

  An internal resistance calculation apparatus according to an embodiment of the present invention includes a remaining amount calculation unit that repeatedly calculates a remaining amount of the secondary battery, and the estimation unit reduces a remaining amount calculated by the remaining amount calculation unit. And when the difference between the calculated remaining amount and the predetermined lower limit value is less than or equal to the predetermined lower limit threshold value, or the calculated remaining amount increases and the difference between the calculated remaining amount and the predetermined upper limit value is a predetermined value. When the upper limit threshold is not reached, it is estimated that charge / discharge switching has occurred.

  The remaining amount calculation unit repeatedly calculates the remaining amount of the secondary battery. The remaining amount (remaining amount) of the secondary battery is, for example, the remaining amount of the secondary battery calculated at time ta is C (ta), and the remaining amount of the secondary battery calculated at time tb after time ta is C. Assuming (tb), the remaining amount C (tb) can be calculated by C (ta) + (cumulative value of current between time points ta to tb).

  When the remaining amount calculated by the remaining amount calculating unit decreases and the difference between the calculated remaining amount and a predetermined lower limit value is equal to or less than a predetermined lower limit threshold, the estimating unit estimates that charging / discharging is switched. Since the discharge is stopped when the remaining amount decreases and falls below the lower limit value, it is estimated that switching from discharging to charging is performed when the difference between the remaining amount and the predetermined lower limit value falls below the predetermined lower limit threshold value. can do.

  In addition, the estimation unit estimates that charging / discharging is switched when the remaining amount calculated by the remaining amount calculation unit increases and the difference between the calculated remaining amount and a predetermined upper limit value is equal to or less than a predetermined upper limit threshold value. To do. When the remaining amount increases and exceeds the upper limit value, charging is stopped. Therefore, it is estimated that switching from charging to discharging is performed when the difference between the remaining amount and the predetermined upper limit value is less than or equal to the predetermined upper limit threshold value. can do.

  The internal resistance calculation device according to the embodiment of the present invention includes an idling information acquisition unit that acquires information regarding a start time or an end time of an idling stop, and the estimation unit includes a start time acquired by the idling information acquisition unit or Presence / absence of charge / discharge switching is estimated based on the end point.

  The idling information acquisition unit acquires information related to the start time or end time of the idling stop. The start time or end time of the idling stop is specified by, for example, the stop time and stop time at the intersection predicted based on the running state of the vehicle (vehicle speed, distance to the intersection), signal information of signal lights at the intersection, etc. And can be obtained.

  The estimation unit estimates the presence / absence of switching between charge and discharge based on the start time or end time acquired by the idling information acquisition unit. At the start of idling stop, it switches to discharge. In addition, there are the following two cases at the end of the idling stop. That is, when the remaining amount of the secondary battery becomes equal to or lower than the lower limit value during idling stop, the charging is switched to the state without charging / discharging at the end of the idling stop. Further, when the remaining amount of the secondary battery is larger than the lower limit value during idling stop, the state is switched from discharge to no charge / discharge at the end of idling stop. Thereby, the presence or absence of switching of charge / discharge can be estimated from the start time or end time of the idling stop.

  An internal resistance calculation device according to an embodiment of the present invention includes a command acquisition unit that acquires a command related to power generation to an alternator, and the estimation unit switches between charge and discharge based on the command acquired by the command acquisition unit. Presence or absence of is estimated.

  The command acquisition unit acquires a command related to power generation to the alternator. For example, since a predetermined ECU (electronic control unit) outputs a command related to power generation to the alternator to the alternator, a command output by the predetermined ECU may be acquired.

  An estimation part estimates the presence or absence of switching of charging / discharging based on the instruction | command acquired in the instruction | command acquisition part. For example, when a command to stop power generation is output from the ECU to the alternator, it can be estimated that switching from charging to discharging is performed. Further, when a command to start power generation is output from the ECU to the alternator, it can be estimated that switching to charging is performed.

[Details of the embodiment of the present invention]
Hereinafter, an internal resistance calculation apparatus according to an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a block diagram showing an example of a configuration of a main part of a vehicle equipped with a battery monitoring device 100 as an internal resistance calculation device of the present embodiment. As shown in FIG. 1, in addition to the battery monitoring device 100, the vehicle includes a secondary battery unit 50, relays 61, 62, 63, a generator (ALT) 71, a starter motor (ST) 72, a battery 73, an electric load. 74, 75 and the like.

  The secondary battery unit 50 is, for example, a lithium ion battery, and a plurality of cells 51 are connected in series or in series and parallel. The secondary battery unit 50 includes a voltage sensor 52, a current sensor 53, and a temperature sensor 54. The voltage sensor 52 detects the voltage across the secondary battery unit 50 and the voltage of each cell 51 and outputs the detected voltage to the battery monitoring device 100 via the voltage detection line 50a. The current sensor 53 is composed of, for example, a shunt resistor or a hall sensor, and detects a charging current and a discharging current of the secondary battery unit 50. The current sensor 53 outputs the current detected via the current detection line 50b to the battery monitoring device 100. The temperature sensor 54 is composed of, for example, a thermistor, and detects the temperature of the cell 51. The temperature sensor 54 outputs the temperature detected via the temperature detection line 50c to the battery monitoring device 100.

  The battery 73 is, for example, a lead battery, and supplies power to an electric load 74 (for example, a light, various motors, various controllers, etc.) of the vehicle, and drives the starter motor 72 when the relay 63 is turned on. To supply power. The generator 71 generates power by the rotation of the engine of the vehicle, and outputs direct current by a rectifier circuit provided inside to charge the battery 73. The generator 71 charges the battery 73 and the secondary battery unit 50 when the relays 61 and 62 are on. When the relay 61 is turned on, the secondary battery unit 50 supplies power to the electrical load 75 (for example, engine system electrical equipment, audio, etc.). Relays 61, 62, and 63 are turned on and off by a relay control unit (not shown) to distribute the power to be supplied according to the charge / discharge balance of the battery 73 and the secondary battery unit 50 and the degree of load.

  FIG. 2 is a block diagram showing an example of the configuration of the battery monitoring device 100 as the secondary battery calculation device of the present embodiment. The battery monitoring apparatus 100 includes a control unit 10 that controls the entire apparatus, a voltage acquisition unit 11, a current acquisition unit 12, a temperature acquisition unit 13, an estimation unit 14, a sampling period change unit 15, a communication unit 16, a switching detection unit 17, and a resistance. A calculation unit 18, an increase / decrease amount calculation unit 19, a remaining amount calculation unit 20, a command acquisition unit 21, a storage unit 22 that stores predetermined information, a timer 23 for timing, and the like are provided.

  The control unit 10 includes a CPU and the like.

  The voltage acquisition unit 11 has a function as an acquisition unit, and acquires the voltage of the secondary battery unit 50 (the voltage across the secondary battery unit 50 and the voltage of each cell 51). Moreover, the current acquisition unit 12 has a function as an acquisition unit, and acquires the current (charging current and discharging current) of the secondary battery unit 50.

  More specifically, the current acquisition unit 12 includes an AD converter, converts the acquired current into a digital value at the sampling period changed by the sampling period changing unit 15, and outputs the converted digital value to the control unit 10. To do. The sampling period can be, for example, a first sampling period (for example, 10 ms) and a second sampling period (for example, 1 ms) shorter than the first sampling period. The sampling periods of 10 ms and 1 ms are examples, and are not limited to such numerical values. Thereby, the control part 10 can read the electric current value of the secondary battery unit 50 by a 1st sampling period and a 2nd sampling period.

  The voltage acquisition unit 11 includes an AD converter, converts the acquired voltage into a digital value at the sampling period changed by the sampling period changing unit 15, and outputs the converted digital value to the control unit 10. The sampling period can be, for example, a first sampling period (for example, 10 ms) and a second sampling period (for example, 1 ms) shorter than the first sampling period. The sampling periods of 10 ms and 1 ms are examples, and are not limited to such numerical values. Thereby, the control part 10 can read the voltage value of the secondary battery unit 50 by a 1st sampling period and a 2nd sampling period.

  The temperature acquisition unit 13 acquires the temperature of the secondary battery unit 50.

  The estimation unit 14 estimates whether charging / discharging of the secondary battery unit 50 is switched. That is, the estimation unit 14 predicts switching between charge and discharge before the charge / discharge of the secondary battery unit 50 is actually switched. For example, the charge / discharge switching is estimated by monitoring the direction of increase / decrease in the charge / discharge current over time, based on the absolute value of the current and the degree of temporal change (for example, increase or decrease). The time when the condition is satisfied can be set as the estimated time. The details of the method for estimating the charging / discharging switching point will be described later.

  When the estimation unit 14 estimates that charging / discharging is switched, the sampling cycle changing unit 15 sets the first sampling cycle when the voltage acquisition unit 11 acquires a voltage and when the current acquisition unit 12 acquires a current. Change to a second sampling period shorter than one sampling period. That is, the sampling period changing unit 15 changes the sampling period to the second sampling period when the estimating unit 14 estimates that charging / discharging is switched. For example, when the first sampling period is 10 ms, the second sampling period can be 1 ms, but the present invention is not limited to this.

  The switching detection unit 17 detects charging / discharging switching of the secondary battery unit 50 based on the current acquired in the second sampling cycle changed by the sampling cycle changing unit 15. For example, if the current acquired by the current acquisition unit 12 in the case of charging is defined as positive, the direction of the current is opposite between charging and discharging, so when the current acquired by the current acquisition unit 12 is negative, It can be determined that this is a discharge. That is, when either charge or discharge is determined as positive and the current changes from positive to negative or 0, the current changes from 0 to positive or negative, or the current changes from negative to positive or 0 Switching between charge and discharge can be detected.

  When the switching detection unit 17 detects charging / discharging switching, the resistance calculation unit 18 acquires the voltage Vb and current Ib acquired before the charging / discharging switching time of the secondary battery unit 50 and the charging / discharging of the secondary battery unit 50. The internal resistance of the secondary battery unit 50 is calculated on the basis of the voltage Vc and the current Ic acquired after a predetermined waiting time T has elapsed from the time of switching.

  The secondary battery unit 50 can be represented by an equivalent circuit including an electrolyte bulk resistance Rs, an interface charge transfer resistance Rc, an electric double layer capacitance C, and a diffusion impedance Zw. The internal resistance of the secondary battery unit 50 is mainly composed of the electrolyte bulk resistance Rs and the interface charge transfer resistance Rc. On the other hand, when the frequency is changed from a high frequency to a low frequency in the impedance spectrum obtained by plotting the values obtained by measuring the impedance of the secondary battery unit 50 at a plurality of frequencies using the AC impedance method, the diffusion is performed in a certain boundary frequency range. The impedance Zw increases and the impedance of the secondary battery unit 50 increases. The standby time T can be obtained based on the boundary frequency region where the diffusion impedance Zw increases. The waiting time T can be set to, for example, 100 ms, but is not limited thereto.

  There is a relationship of T = 1 / (2 × f) between the frequency f in the alternating current impedance method and the waiting time T from when the direct current is applied until measurement is performed. That is, the standby time T can be specified from the relationship of the reciprocal of twice the frequency f, for example. For example, when the frequency f is 5 Hz, the standby time T is 0.1 second. Note that the standby time T is an inverse of twice the frequency f is an example. For example, the standby time T may be an inverse of four times the frequency f.

  The absolute value of the slope of the straight line obtained from the voltage and current between the two points before and after switching between charge and discharge indicates the internal resistance of the secondary battery unit 50. Therefore, the internal resistance R is calculated by, for example, R = (Vc−Vb) / (Ic−Ib).

  When it is estimated that the charging / discharging of the secondary battery unit 50 is switched by the above-described configuration, the sampling period is shortened before the actual charging / discharging switching time to acquire the voltage and current, and the acquired current Therefore, even when the voltage and current of the secondary battery unit 50 fluctuate in a short cycle, the charging / discharging switching time can be detected with high accuracy. Since the charging / discharging switching time can be detected with high accuracy, the time when the standby time T has elapsed can be specified with high accuracy. As a result, the voltage Vb and current Ib before the charge / discharge switching, and the voltage Vc and current Ic after the elapse of the predetermined standby time T from the charging / discharging switching time can be accurately obtained. Resistance can be calculated accurately.

  FIG. 3 is an explanatory diagram illustrating an example of a current waveform of the secondary battery unit 50. FIG. 4 is an explanatory diagram showing an example of a current waveform on the discharge side when the time axis of the current waveform in FIG. 3 is enlarged. 3 and 4, the horizontal axis represents time, and the vertical axis represents current. When the current is positive, it indicates a charging current, and when the current is negative, it indicates a discharging current. 3 and 4, in the current waveform on the discharge side, a discharge current pulse having a relatively large peak value appears at an interval of about 30 ms. The discharge current pulse is, for example, a pulse current that flows through an engine ignition system load, and includes, for example, a current that flows through an ignition coil, a load current of a fuel injection pump, and the like.

  Next, a method for sampling the current of the secondary battery unit 50 illustrated in FIGS. 3 and 4 will be described. FIG. 5 is an explanatory diagram showing an example of a current sampling value by the battery monitoring apparatus 100 of the present embodiment. In FIG. 5, the horizontal axis indicates time, and the vertical axis indicates current. When the current is positive, it indicates a charging current, and when the current is negative, it indicates a discharging current. A broken line indicated by a symbol A indicates a current value obtained by sampling the current shown in FIG. 4 at 10 ms as the first sampling period. A thin line indicated by a symbol B indicates a current value obtained by sampling the current shown in FIG. 4 at 1 ms as the second sampling period. A thick line indicated by a symbol C indicates a 5-moving average as a statistical value of a current value sampled at a sampling period of 1 ms indicated by a symbol B.

  In FIG. 5, the charge / discharge switching time is the time when the current changes from positive to negative, and is 201 ms. The waiting time T is set to 100 ms. Further, the estimated time point at which the charge / discharge switching is estimated is the 190 ms time point. According to the present embodiment, the sampling period is changed from 10 ms to 1 ms at 190 ms when the charge / discharge switching is estimated. Thereafter, the time point at which switching between charge and discharge is detected is a time point of 201 ms, and the time point when the standby time T elapses is a time point of 301 ms after 100 ms.

  Then, the current Ib and the voltage Vb before the charge / discharge switching are data at the time of 200 ms, which is 1 ms before the time 201 ms at which the charge / discharge switching is detected. Further, the current Ic and the voltage Vc after the elapse of the standby time T become data at a time point of 301 ms after the elapse of 100 ms from the time point 201 ms at which the charge / discharge switching is detected. Further, in the example of FIG. 5, the sampling period returns to 10 ms after 301 ms after the standby time T has elapsed.

  That is, the internal resistance R of the secondary battery unit 50 is calculated as R = (Vc−Vb) / (Ic−Ib) based on the current Ib and voltage Vb at 200 ms and the current Ic and voltage Vc at 301 ms. be able to.

  As shown in FIGS. 4 and 5, the current fluctuation period of the secondary battery unit 50 is shorter than the first sampling period of 10 ms. For this reason, if voltage and current are sampled at a sampling period of 10 ms, as shown in the chart of symbol A in FIG. 5, the time point at which switching of charging / discharging at the time point of 201 ms is detected is the time point of 210 ms. A time difference of 9 ms occurs from the switching time (201 ms). In addition, since the time point at which switching between charge and discharge is detected is 210 ms, the time point when the standby time T has elapsed is the time point 310 ms after 100 ms. As described above, when the voltage and current are sampled in the first sampling period, the time point at which the charge / discharge switching is detected deviates from the actual charge / discharge switching time point, and as a result, the standby time T has elapsed. Therefore, the acquisition time of the voltage and current for calculating the internal resistance shifts, and the internal resistance cannot be calculated with high accuracy.

  However, according to the present embodiment, even when the voltage and current of the secondary battery unit 50 fluctuate in a short cycle, the charging / discharging switching time can be accurately detected. Since the charging / discharging switching time can be detected with high accuracy, the time when the standby time T has elapsed can be specified with high accuracy. As a result, the voltage Vb and current Ib before the charge / discharge switching, and the voltage Vc and current Ic after the elapse of the predetermined standby time T from the charging / discharging switching time can be accurately obtained. Resistance can be calculated accurately.

  In addition, if at least one of the voltage or current acquired in the second sampling period (for example, 1 ms) fluctuates relatively greatly, the acquisition is performed in the second sampling period as shown in the chart indicated by symbol C in FIG. It is also possible to calculate a statistical value of the measured voltage and current (for example, five moving averages of the past five times), and calculate the internal resistance of the secondary battery unit 50 using the calculated voltage and current.

  That is, the resistance calculation unit 18 has acquired multiple times when the voltage acquisition unit 11 or the current acquisition unit 12 has acquired at least one variation width of the voltage or current acquired multiple times in the second sampling period is equal to or greater than a predetermined variation threshold. A statistical value of at least one of voltage and current is calculated.

  The fluctuation range can be, for example, the difference between the maximum value and the minimum value of the sampling values of the voltage or current acquired a plurality of times, but is not limited to this. The plurality of times can be, for example, five times, but is not limited thereto. The statistical value can be, for example, a five-moving average of the past five sampling values as indicated by a thick line indicated by a symbol C in FIG. 5, but is not limited thereto.

  The resistance calculation unit 18 calculates the internal resistance R of the secondary battery unit 50 based on the statistical value calculated after the standby time T has elapsed. For example, when the statistical value of voltage is Va and the statistical value of current is Ia, the internal resistance R can be calculated by R = (Va−Vb) / (Ia−Ib).

  When the fluctuation range of the values sampled over the past 5 times after the standby time T has passed is equal to or greater than the fluctuation threshold, the moving average of the past 5 sampling values is used, so the voltage or current fluctuates before and after the standby time T has passed. Even in this case, the voltage and current can be acquired by canceling the fluctuation of the sampling value, and the internal resistance of the secondary battery unit 50 can be calculated with high accuracy.

  In addition, when calculating 5 moving averages based on the past 5 sampling values, the last sampling time of current and voltage may be after the standby time T has elapsed. In other words, all of the past five sampling times may be after the waiting time T has elapsed. Further, the first one or several times of the past five sampling times may be before the waiting time T has elapsed.

  When the switching detection unit 17 detects charging / discharging switching, the sampling period changing unit 15 extends from the estimated time (190 ms in the example of FIG. 5) to the charging / discharging switching time (201 ms in the example of FIG. 5). Change to the second sampling period.

  Since the second sampling period is changed from the estimated time point to the charging / discharging switching time point, even when the voltage and current of the secondary battery unit 50 fluctuate in a short period, the charging / discharging switching time point can be accurately detected. And since the switching time of charging / discharging can be detected frequently, the voltage Vb and current Ib before charging / discharging switching can be acquired correctly. In addition, the point in time when the standby time T has elapsed can be specified with high accuracy.

  When the switching detection unit 17 detects the switching of charging / discharging, the sampling period changing unit 15 waits for the waiting time T (301 ms in the example of FIG. 5) from the switching point of charging / discharging (201 ms in the example of FIG. 5). Until the second sampling period.

  Since the second sampling period is changed from the charging / discharging switching time to the time when the standby time T elapses, the predetermined standby time T from the charging / discharging switching time even when the voltage and current of the secondary battery unit 50 fluctuate in a short period. The voltage Vc and the current Ic after the lapse can be accurately acquired, and the internal resistance of the secondary battery unit 50 can be calculated with high accuracy.

  Further, when the switching detection unit 17 detects the switching of charging / discharging, the sampling period changing unit 15 changes to the first sampling period after the switching point of charging / discharging, and changes between the switching point and the waiting time T. It can also be changed to two sampling periods.

  For example, in the example of FIG. 5, when charging / discharging switching is detected is 201 ms, and the standby time T is 100 ms, the standby time T elapsed time is 301 ms. Assuming that a time point (predetermined time point) between the switching time point and the waiting time T elapses is a time point when 90 ms has elapsed from the charging / discharging switching time point, the sampling period is returned to 10 ms after 201 ms when the charging / discharging switching is detected. The sampling period is changed to 1 ms at 291 ms, which is 10 ms before 301 ms, which is the time when T has elapsed.

  In order to accurately calculate the internal resistance of the secondary battery unit 50, it is necessary to more accurately detect the voltage and current after the standby time T has elapsed. If the sampling period is shortened after the charging / discharging switching time, the voltage and current can be reliably acquired with a short sampling period when the standby time T has elapsed. On the other hand, shortening the sampling period increases the processing effort. Therefore, by shortening the sampling cycle from the first sampling cycle to the second sampling cycle at a predetermined time point sufficiently before the standby time T (time point 10 ms before the standby time T of 100 ms). The time width for sampling the voltage and current with a short sampling period can be reduced, and the increase in processing effort can be suppressed while increasing the calculation accuracy of the internal resistance of the secondary battery unit 50.

  Next, a method for estimating the presence / absence of charge / discharge switching will be described. First, an estimation method based on the charge / discharge current will be described. FIG. 6 is an explanatory diagram showing a first example of a method for estimating the presence / absence of charge / discharge switching based on current by the battery monitoring apparatus 100 of the present embodiment. FIG. 6 shows the current of the secondary battery unit 50. In FIG. 6, the horizontal axis indicates time, and the vertical axis indicates current. The interval between the time point (t) and the time point (t−1) in FIG. 6 is 10 ms. When the current is positive, it indicates charging, and when the current is negative, it indicates discharging. That is, FIG. 6 shows an example of a state of switching from charging to discharging.

  The increase / decrease amount calculation unit 19 repeatedly calculates an increase amount or a decrease amount of the current based on the current acquired a plurality of times in the first sampling period. For example, the sampling time points are (t-2), (t-1), and (t) in time series, and the currents acquired at the respective sampling time points are I (t-2), I (t-1), and I (t ). If I (t-2) <I (t-1) <I (t), the current increases. Further, if I (t−2)> I (t−1)> I (t), the current decreases.

  When the acquired current is positive and the amount of decrease calculated by the increase / decrease amount calculation unit 19 is equal to or greater than a predetermined threshold, the estimation unit 14 estimates that charging / discharging is switched. As shown in FIG. 6, for example, when I (t)> 0 and I (t−1) −I (t) ≧ Th1, the charging current decreases and approaches 0A. It can be estimated that there is a switch to discharge. Note that, under the condition that the current is decreasing, the equation I (t−1) −I (t) ≧ Th1 is expressed as | I (t) −I (t−1) as shown in FIG. It can be replaced by the expression | ≧ Th1. The estimated time point can be set as the sampling time point t. Note that the estimated time can be shifted by a required time before and after the time t. The example of FIG. 6 can be used when the current of the secondary battery unit 50 changes relatively abruptly.

  FIG. 7 is an explanatory diagram showing a second example of a method for estimating the presence / absence of charge / discharge switching based on current by the battery monitoring apparatus 100 of the present embodiment. The interval between the time point (t), the time point (t-1), and the time point (t-2) in FIG. 7 is 10 ms. When the acquired current is positive and the amount of decrease calculated by the increase / decrease amount calculation unit 19 is equal to or greater than a predetermined threshold, the estimation unit 14 estimates that charging / discharging is switched. For example, as shown in FIG. 7, when I (t−2) −I (t−1) ≧ Th2, I (t−1) −I (t) ≧ Th2, and Th3> I (t)> 0 In some cases, since the charging current decreases and approaches 0 A, it can be estimated that there is a switching from charging to discharging. Note that, under the condition that the current is decreasing, the expression I (t−2) −I (t−1) ≧ Th2 is expressed as | I (t−1) −I ( t-2) It can be replaced by the expression | ≧ Th2. Further, the expression I (t−1) −I (t) ≧ Th2 can be replaced with the expression | I (t) −I (t−1) | ≧ Th2, as shown in FIG. Note that Th1> Th2> Th3. Further, the estimated time point can be set as the sampling time point t. The example of FIG. 7 can be used when the current of the secondary battery unit 50 changes relatively slowly.

  6 and 7, the case of switching from charging to discharging has been described, but the same applies to the case of switching from discharging to charging, that is, when the current increases. That is, when the acquired current is negative and the increase amount calculated by the increase / decrease amount calculation unit 19 is equal to or greater than a predetermined threshold, the estimation unit 14 estimates that charging / discharging is switched. For example, when I (t) <0 and I (t) −I (t−1) ≧ Th1, the discharge current increases and approaches 0 A, and therefore there is a switch from discharge to charge. Can be estimated. Note that the estimated time point can be the sampling time point t, but is not limited thereto.

  Next, a method for estimating the presence / absence of switching between charge and discharge based on the remaining amount (remaining amount) of the secondary battery unit 50, that is, SOC (State of Charge) will be described. FIG. 8 is an explanatory diagram showing an example of a method for estimating the presence / absence of charge / discharge switching based on the remaining amount by the battery monitoring apparatus 100 of the present embodiment. FIG. 8 shows an example of the change in the SOC of the secondary battery unit 50. In FIG. 8, the horizontal axis indicates time, and the vertical axis indicates SOC. In addition, in FIG. 8, SOC is shown typically.

  The remaining amount calculation unit 20 repeatedly calculates the remaining amount of the secondary battery unit 50. The remaining amount (remaining amount) of the secondary battery unit 50 is, for example, a secondary battery unit calculated at a time point tb after the time point ta with the remaining amount of the secondary battery unit 50 calculated at the time point ta as C (ta). When the remaining amount of 50 is C (tb), the remaining amount C (tb) can be calculated by C (ta) + (cumulative value of current between time points ta and tb).

  When the remaining amount calculated by the remaining amount calculating unit 20 decreases and the difference between the calculated remaining amount and a predetermined lower limit value is equal to or smaller than a predetermined lower limit threshold, the estimating unit 14 estimates that charging / discharging is switched. To do. Since the discharge is stopped when the remaining amount decreases and becomes lower than the lower limit value, it is estimated that switching from discharging to charging is performed when the difference between the remaining amount and the predetermined lower limit value becomes lower than the predetermined lower limit threshold value. be able to.

  For example, in the example of FIG. 8, at the time point t1, the state is switched from no charge / discharge to discharge (for example, the vehicle is stopped), and the SOC starts to decrease from the SOC (t1). At time t2, the SOC further decreases to SOC (t2). When the difference between the SOC (t3) and the lower limit value becomes equal to or lower than a predetermined lower limit threshold at time t3, it can be estimated that charging / discharging is switched at time t3.

  In the example of FIG. 8, when the difference between the SOC (t2) and the lower limit value at the time point t2 is equal to or less than the predetermined lower limit threshold value, it is estimated that charging / discharging is switched at the time point t2 before the time point t3. can do. Further, in the example of FIG. 8, charging is started when the SOC reaches the lower limit value, charging is performed until the charging end time t4, and thereafter, there is no charge / discharge state (for example, the vehicle is running). Yes. In the example of FIG. 8, the SOC is compared with the lower limit value, but the same is true when the SOC is compared with the upper limit value.

  That is, the estimation unit 14 switches between charge and discharge when the remaining amount calculated by the remaining amount calculation unit 19 increases and the difference between the calculated remaining amount and the predetermined upper limit value is equal to or less than the predetermined upper limit threshold value. Estimated. When the remaining amount increases and exceeds the upper limit value, charging is stopped. Therefore, it is estimated that switching from charging to discharging is performed when the difference between the remaining amount and the predetermined upper limit value is less than or equal to the predetermined upper limit threshold value. can do.

  Next, a method for estimating the charging / discharging switching time based on information related to idling stop will be described. FIG. 9 is an explanatory diagram showing an example of a method for estimating the presence / absence of charge / discharge switching based on information related to idling stop by the battery monitoring apparatus 100 according to the present embodiment. In FIG. 9, the horizontal axis indicates time, and the vertical axis indicates the current of the secondary battery unit 50. When the current is positive, it indicates a charging current, and when the current is negative, it indicates a discharging current. In FIG. 9, the vehicle stops at time t <b> 1 and discharge of the secondary battery unit 50 is started. At time t <b> 3, the SOC of the secondary battery unit 50 has dropped to the lower limit value, so charging of the secondary battery unit 50 is started. The vehicle starts to travel at time t4 and the charging of the secondary battery unit 50 is completed.

  The communication part 16 has a function as an idling information acquisition part, and acquires the information regarding the stop start time or end time from another system (not shown) in the vehicle or a roadside device (not shown) outside the vehicle. . The start time or end time of the idling stop is specified by, for example, the stop time and stop time at the intersection predicted based on the running state of the vehicle (vehicle speed, distance to the intersection), signal information of signal lights at the intersection, etc. And can be obtained.

  The estimation unit 14 estimates the presence / absence of charge / discharge switching based on the start time or end time acquired by the communication unit 16. At the start point of idling stop (time point t1 in FIG. 9), it switches to discharge. Further, there are the following two cases at the end of the idling stop (time t4 in FIG. 9). That is, as shown in FIG. 9, when the remaining amount of the secondary battery unit 50 becomes equal to or lower than the lower limit value during idling stop, the charging is switched to the state without charging / discharging at the end of the idling stop. Although not shown, when the remaining amount of the secondary battery is larger than the lower limit value during idling stop, the state is switched from discharge to no charge / discharge at the end of idling stop. Thereby, the presence or absence of switching of charge / discharge can be estimated from the start time or end time of the idling stop. The estimated time point can be a time point before a required time (for example, 10 ms) from the start point of the idling stop or a time point before the required time (for example, 10 ms) from the end point of the idling stop.

  Next, a method for estimating the presence / absence of charge / discharge switching based on a command relating to power generation to the alternator will be described. The command acquisition unit 21 acquires a command related to power generation to the alternator 71. For example, since a predetermined ECU (electronic control unit) (not shown) outputs a command related to power generation to the alternator 71 to the alternator 71, a command output by the predetermined ECU may be acquired.

  The estimation unit 14 estimates the presence / absence of charge / discharge switching based on the command acquired by the command acquisition unit 21. For example, when a command to stop power generation is output from the ECU to the alternator 71, it can be estimated that switching from charging to discharging is performed. In addition, when a command to start power generation is output from the ECU to the alternator 71, it can be estimated that switching to charging is performed. In this case, the estimated time point may be a time point before the required time (for example, 10 ms) from the time point when the power generation is started or a time point before the required time (for example, 10 ms) from the time point when the power generation is stopped.

  Next, the operation of the battery monitoring apparatus 100 of the present embodiment will be described. 10 and 11 are flowcharts showing an example of the processing procedure of the battery monitoring apparatus 100 of the present embodiment. Hereinafter, for the sake of convenience, the processing subject will be described as the control unit 10. The control unit 10 acquires the voltage and current of the secondary battery unit 50 in a first sampling period (for example, 10 ms) (S11), and determines whether or not charge / discharge switching can be estimated (S12). That is, the presence / absence of charge / discharge switching is estimated.

  When the charge / discharge switching cannot be estimated (NO in S12), that is, when it is estimated that there is no charge / discharge switching, the control unit 10 performs the process of step S11. When the charge / discharge switching can be estimated (YES in S12), that is, when it is estimated that the charge / discharge switching is performed, the control unit 10 changes the sampling period to the second sampling period (for example, 1 ms). (S13) The voltage and current of the secondary battery unit 50 are acquired in the second sampling period (S14).

  The controller 10 determines whether or not charging / discharging is switched (S15), and when there is no switching of charging / discharging (NO in S15), that is, when switching of charging / discharging cannot be detected, the process of step S15 is performed. to continue. When the charge / discharge switching is performed (YES in S15), that is, when the charge / discharge switching can be detected, the control unit 10 stores the voltage Vb and the current Ib immediately before the charge / discharge switching in the storage unit 22. (S16), it is determined whether or not a standby time T (for example, 100 ms) has elapsed since the switching point of charge / discharge (S17). When the standby time T has not elapsed (NO in S17), the control unit 10 continues the process of step S17.

  When the standby time T has elapsed (YES in S17), the control unit 10 determines whether or not the current acquired after the standby time T has elapsed is equal to or greater than a predetermined current threshold (S18). When the acquired current is equal to or greater than the current threshold (YES in S18), the control unit 10 determines whether or not the variation width of the voltage and current acquired a plurality of times is equal to or greater than a predetermined variation threshold (S19). Note that the fluctuation range of both voltage and current may be determined, or one of the fluctuation ranges may be determined.

  When the fluctuation range is not equal to or greater than the predetermined fluctuation threshold (NO in S19), the control unit 10 acquires the voltage Vc and the current Ic after the standby time T has elapsed (S20), and performs the process of step S22 described later. When the fluctuation range is equal to or larger than the predetermined fluctuation threshold value (YES in S19), the control unit 10 calculates the statistical value Va of voltage and the statistical value Ia of current (S21), and performs the process of step S22 described later.

  The control unit 10 calculates the internal resistance value R of the secondary battery unit 50 (S22). The internal resistance value R can be calculated by the equation R = (Vc−Vb) / (Ic−Ib) or the equation R = (Va−Vb) / (Ia−Ib).

  The control unit 10 changes the sampling period to the first sampling period (S23). If the acquired current is not equal to or greater than the current threshold (NO in S18), the control unit 10 performs the process of step S23 without performing the process of step S19.

  The control unit 10 determines whether or not to end the process (S24). If the process is not ended (NO in S24), the process after step S11 is continued and the process is ended (YES in S24). Exit.

  The internal resistance calculation device (battery monitoring device 100) of the present embodiment can also be realized by using a general-purpose computer including a CPU (processor), a RAM (memory), and the like. That is, as shown in FIGS. 10 and 11, a computer program that defines the procedure of each process is loaded into a RAM (memory) provided in the computer, and the computer program is executed by a CPU (processor). Thus, an internal resistance calculation device (battery monitoring device 100) can be realized.

  In the above-described embodiment, the secondary battery unit 50 has been described as a lithium ion battery. However, the secondary battery unit 50 is not limited to a lithium ion battery, and is provided, for example, to a nickel metal hydride battery or a nickel cadmium battery. can do.

  The disclosed embodiments are to be considered in all respects as illustrative and not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

DESCRIPTION OF SYMBOLS 10 Control part 11 Voltage acquisition part 12 Current acquisition part 13 Temperature acquisition part 14 Estimation part 15 Sampling period change part 16 Communication part 17 Switching determination part 18 Resistance calculation part 19 Increase / decrease amount calculation part 20 Residual amount calculation part 21 Command acquisition part 22 Storage Unit 23 Timer 50 Secondary battery unit 51 Cell 52 Voltage sensor 53 Current sensor 54 Temperature sensor 100 Battery monitoring device

Claims (10)

An internal resistance calculation device for calculating the internal resistance of a secondary battery,
An acquisition unit for acquiring the voltage and current of the secondary battery at a predetermined first sampling period;
An estimation unit for estimating presence / absence of charge / discharge switching of the secondary battery;
When the estimation unit estimates that there is switching, the changing unit changes the first sampling period when the acquisition unit acquires voltage and current to a second sampling period shorter than the first sampling period;
A switching detection unit that detects charging / discharging switching of the secondary battery based on the current acquired by the acquisition unit in the second sampling period changed by the changing unit;
When the switching detection unit detects charging / discharging switching, the voltage and current acquired by the acquiring unit before the charging / discharging switching time of the secondary battery, and the charging / discharging switching time of the secondary battery are predetermined. An internal resistance calculation device comprising: a resistance calculation unit that calculates an internal resistance of the secondary battery based on a voltage and a current acquired by the acquisition unit after the standby time has elapsed. The changing unit is
2. The internal resistance calculation device according to claim 1, wherein when the switching detection unit detects charging / discharging switching, the internal resistance calculation device changes to the second sampling period from the estimated time estimated by the estimating unit to the charging / discharging switching time. The changing unit is
The internal resistance calculation device according to claim 1 or 2, wherein when the switching detection unit detects charging / discharging switching, the second sampling period is changed from charging / discharging switching time to the standby time lapse time. The changing unit is
When the switching detection unit detects charging / discharging switching, the switching is changed to the first sampling period after the switching point of charging / discharging, and is changed to the second sampling period between the switching point and the standby time point. The internal resistance calculation device according to claim 1 or 2. An increase / decrease amount calculation unit that repeatedly calculates an increase amount or a decrease amount of current based on the current acquired by the acquisition unit a plurality of times in the first sampling period,
The estimation unit includes
When the acquired current is positive and the amount of decrease calculated by the increase / decrease amount calculation unit is equal to or greater than a predetermined threshold, or the acquired current is negative and the increase amount calculated by the increase / decrease amount calculation unit is The internal resistance calculation device according to any one of claims 1 to 4, wherein when the predetermined threshold value is exceeded, the charge / discharge switching is estimated to be performed. A remaining amount calculation unit that repeatedly calculates the remaining amount of the secondary battery;
The estimation unit includes
When the residual amount calculated by the residual amount calculation unit decreases and the difference between the calculated residual amount and the predetermined lower limit value is equal to or less than the predetermined lower limit threshold, or the calculated residual amount increases and is calculated The internal resistance calculation device according to any one of claims 1 to 4, wherein when the difference between the remaining amount and a predetermined upper limit value is equal to or less than a predetermined upper limit threshold, it is estimated that charging / discharging is switched. An idling information acquisition unit for acquiring information related to the start time or end time of the idling stop;
The estimation unit includes
The internal resistance calculation device according to any one of claims 1 to 4, wherein the presence / absence of charge / discharge switching is estimated based on a start time or an end time acquired by the idling information acquisition unit. A command acquisition unit that acquires a command related to power generation to the alternator,
The estimation unit includes
The internal resistance calculation apparatus according to any one of claims 1 to 4, wherein the presence / absence of switching between charge and discharge is estimated based on a command acquired by the command acquisition unit. A computer program for causing a computer to calculate the internal resistance of a secondary battery,
Computer
An acquisition unit for acquiring the voltage and current of the secondary battery at a predetermined first sampling period;
An estimation unit for estimating presence / absence of charge / discharge switching of the secondary battery;
A change unit that changes the first sampling period when the acquisition unit acquires the voltage and current to a second sampling period shorter than the first sampling period when it is estimated that there is switching;
A switching detection unit that detects charging / discharging switching of the secondary battery based on the current acquired by the acquisition unit in the changed second sampling period;
When switching of charging / discharging is detected, the voltage and current acquired by the acquisition unit before the switching time of charging / discharging of the secondary battery, and after the elapse of a predetermined standby time from the switching time of charging / discharging of the secondary battery, A computer program that functions as a resistance calculation unit that calculates the internal resistance of the secondary battery based on the voltage and current acquired by the acquisition unit. An internal resistance calculation method for calculating an internal resistance of a secondary battery,
The acquisition unit acquires the voltage and current of the secondary battery at a predetermined first sampling period,
The estimation unit estimates the presence / absence of switching between charge and discharge of the secondary battery,
When it is estimated that there is switching, the changing unit changes the first sampling period when acquiring the voltage and current to a second sampling period shorter than the first sampling period,
Based on the current acquired by the acquisition unit in the changed second sampling period, the switching detection unit detects the switching of charge and discharge of the secondary battery,
When charging / discharging switching is detected, the voltage and current acquired before the charging / discharging switching time of the secondary battery, and after the predetermined standby time has elapsed from the charging / discharging switching time of the secondary battery. An internal resistance calculation method in which a resistance calculation unit calculates an internal resistance of the secondary battery based on a voltage and a current.

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