JP2013210333A - Internal resistance detecting method and internal resistance detecting device for secondary battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an internal resistance detecting method and an internal resistance detecting device for a secondary battery, in which internal resistance of the secondary battery can be detected with high accuracy while reducing influences of resistance of a harness.SOLUTION: Resistance Rm is calculated from a current measurement and a voltage measurement inputted from a current measuring section 120 and a voltage measuring section 130, harness resistance Rh is subtracted therefrom, and internal resistance Rb of a secondary battery 10 is calculated. The harness resistance Rh is used after performing temperature correction to be a resistance value at a harness temperature detected by temperature detecting means 150 with respect to harness resistance Rhs at a predetermined reference temperature which is actually measured or calculated beforehand.

Description

  The present invention mainly relates to a secondary battery internal resistance detection method and an internal resistance detection device for detecting internal resistance of a secondary battery mounted on an automobile.

  As a method for detecting the internal resistance of a secondary battery mounted on an automobile, an active method and a passive method are known. In the internal resistance detection method using the active method, the secondary battery is actively (actively) discharged at an arbitrary timing, and the internal resistance of the secondary battery is detected from a change in voltage (current voltage response) at that time. In the internal resistance detection method using the passive method, the current-voltage response is measured when current flows through the secondary battery, such as when the engine is cranked or when a load is used, or when the generator is charged. Sense resistance. The internal resistance detection method by the passive method is called a passive method because it cannot know the timing of current flow in advance as in the active method.

  FIG. 5 shows an example in which an internal resistance detection device for measuring a current-voltage response is connected to a secondary battery mounted on a vehicle. The secondary battery 10 is first connected to an electrical connection box (also called a relay box, a junction box, or a fuse box) 20-1 through an electric wire 30, and here, another electrical connection is made via a bus bar 21 and a fuse 22. The connection boxes 20-2 and 20-3 are connected to the starter 40 and the like. The fuse 22 is provided to protect the vehicle electronic device (electric part). In the example shown in FIG. 5, the internal resistance detection device 50 is connected to an electrical connection box 20-2 that is one of the other electrical connection boxes connected to the electrical connection box 20-1.

  When the internal resistance detection device 50 is connected to the electrical junction box 20-2, the current and voltage measured by the internal resistance detection device 50 connect the battery terminal of the secondary battery 10 and the electrical junction box 20-1. The electric wire 30, the bus bar 21 and the fuse 22 inside the electric connection box 20-1, the electric wire 31 connecting the electric connection box 20-1 and the electric connection box 20-2, and the bus bar 23 inside the electric connection box 20-2. Affected by resistance. As a result, resistance components such as the electric wires 30 and 31, the bus bars 21 and 23, and the fuse 22 are added to the internal resistance of the secondary battery 10 obtained from the current and voltage measured by the internal resistance detection device 50. Therefore, the accurate internal resistance of the secondary battery 10 cannot be detected.

  In the conventional method of detecting internal resistance of a secondary battery, measurement is performed with an internal resistance detector without considering the influence of the resistance component of the current path such as electric wires, bus bars, fuses, etc. (hereinafter collectively referred to as harness). The resistance value was obtained from the measured current value and the measured voltage value, and this was used as the internal resistance of the secondary battery. As an example of a conventional method for detecting the internal resistance of a secondary battery, in Patent Document 1, a secondary battery is caused to perform a pulse discharge of a substantially rectangular wave with a predetermined current value. The internal resistance of the secondary battery is detected.

  In Patent Document 2, when starting an engine starter of a vehicle, the voltage and current of the secondary battery are sampled during the starter current increasing period, and the internal resistance of the secondary battery is detected from the amount of change in voltage and current per unit time. ing. Further, in Patent Document 3, for an assembled battery having a service plug box composed of a fuse and a service plug, the internal resistance value of the assembled battery is calculated and corrected using the resistance value of the service plug box. The resistance value of the service plug box is calculated by calculating the temperature of the service plug box based on the charge / discharge current, the battery temperature, and the ambient temperature.

JP 2006-284537 A JP 2002-168929 A JP 2010-160026 JP

  However, in the methods disclosed in Patent Document 1 and Patent Document 2, since the influence of the resistance of the harness is not considered, the detected internal resistance of the secondary battery includes the resistance of the harness, It is not possible to accurately know only the internal resistance of the secondary battery. Further, in the method of Patent Document 3, the resistance value of the service plug box is corrected to obtain the internal resistance value of the assembled battery. However, the resistance of the harness is not taken into consideration, and the corrected internal resistance is The resistance of the harness is included. Any of the conventional methods for detecting the internal resistance of a secondary battery has a problem that the internal resistance of the secondary battery cannot be accurately detected.

  The present invention has been made in order to solve the above-mentioned problem, and a method for detecting the internal resistance of a secondary battery capable of detecting the internal resistance of the secondary battery with high accuracy by reducing the influence of the resistance of the harness and An object is to provide an internal resistance detection device.

  In the first aspect of the method for detecting the internal resistance of the secondary battery of the present invention, the charge / discharge current and the response voltage when the secondary battery is charged / discharged are measured using current measuring means and voltage measuring means, respectively, A secondary battery internal resistance detection method for calculating an internal resistance of the secondary battery using a current measurement value and a voltage measurement value respectively input from a current measurement unit and the voltage measurement unit, the terminal of the secondary battery To the predetermined position of the current path through which the charging / discharging current flows is calculated, and the harness resistance Rh is subtracted from the resistance value Rm calculated from the current measurement value and the voltage measurement value. Is calculated.

According to another aspect of the method of detecting the internal resistance of the secondary battery of the present invention, the harness temperature of the current path is Th, the resistance temperature coefficient of the current path is α, and the harness resistance at the reference temperature Ts determined in advance is Rhs. When the harness resistance at the harness temperature Th is Rh, the harness resistance Rh is expressed by the following formula: Rh = Rhs × (1 + α × (Th−Ts))
The internal resistance is calculated by subtracting the calculated harness resistance Rh from the resistance value Rm.

According to another aspect of the method of detecting the internal resistance of the secondary battery of the present invention, when the current path from the terminal of the secondary battery to the predetermined position is composed of a fuse and a conductor, the resistance value RF of the fuse at a predetermined temperature. And the resistance value RC of the conductor is determined in advance, the resistance temperature coefficient of the conductor is α1, and the resistance temperature coefficient of the fuse is α2, the resistance temperature coefficient α of the current path is expressed by the following equation: α = α1 × RC / (RC + RF) + α2 × RF / (RC + RF)
It is characterized by calculating by.

  Another aspect of the method for detecting the internal resistance of the secondary battery according to the present invention has a discharge means for discharging a predetermined discharge current from the secondary battery, and the secondary battery is discharged from the secondary battery using the discharge means. The internal resistance is calculated by measuring the discharge current and the response voltage.

  In another aspect of the method for detecting the internal resistance of the secondary battery of the present invention, the internal resistance is calculated by measuring the discharge current and the response voltage when a large current of a predetermined value or more is discharged from the secondary battery. It is characterized by doing.

  The 1st aspect of the internal resistance detection apparatus of the secondary battery of this invention calculates the internal resistance of the said secondary battery by measuring the charging / discharging current and response voltage when charging / discharging a secondary battery. An internal resistance detection device for a battery, comprising: a current measurement unit that measures the charge / discharge current; a voltage measurement unit that measures the response voltage; and an arithmetic processing unit that calculates the internal resistance. The unit calculates a harness resistance Rh from a terminal of the secondary battery to a predetermined position of a current path through which the charge / discharge current flows, and inputs a current measurement value and a voltage measurement value from the current measurement unit and the voltage measurement unit. Then, a resistance value Rm is calculated from the current measurement value and the voltage measurement value, and the harness resistance Rh is subtracted from the resistance value Rm to calculate the internal resistance.

Another aspect of the internal resistance detection device for a secondary battery of the present invention further includes temperature detection means for detecting a harness temperature of a current path through which the charge / discharge current flows, and the harness temperature detected by the temperature detection means is detected. When the Th, the resistance temperature coefficient of the current path is α, the harness resistance at a predetermined reference temperature Ts is Rhs, and the harness resistance at the harness temperature Th is Rh, the arithmetic processing unit is the harness The resistance Rh is expressed by the following formula: Rh = Rhs × (1 + α × (Th−Ts))
The internal resistance is calculated by subtracting the calculated harness resistance Rh from the resistance value Rm.

  ADVANTAGE OF THE INVENTION According to this invention, the internal resistance detection method and internal resistance detection apparatus of a secondary battery which can reduce the influence of resistance of a harness and can detect the internal resistance of a secondary battery with high precision can be provided. .

It is the connection diagram which connected the internal resistance detection apparatus which concerns on 1st Embodiment of this invention to the secondary battery. It is a graph which shows an example of the temperature characteristic of internal resistance and harness resistance. It is a graph which shows the comparison with the temperature characteristic of an electric wire and a bus-bar, and the temperature characteristic of a fuse. It is the connection diagram which connected the internal resistance detection apparatus which concerns on 2nd Embodiment of this invention to the secondary battery. It is the connection diagram which connected the internal resistance detection apparatus for measuring a current voltage response to the secondary battery.

  A method for detecting the internal resistance of a secondary battery in a preferred embodiment of the present invention will be described in detail with reference to the drawings. In addition, about each structural part which has the same function, the same code | symbol is attached | subjected and shown for simplification of illustration and description.

(First embodiment)
A method for detecting the internal resistance of a secondary battery according to the first embodiment of the present invention will be described with reference to FIG. FIG. 1 is a connection diagram in which an internal resistance detection device 100 used in the secondary battery internal resistance detection method of the first embodiment is connected to a secondary battery 10. In the present embodiment, a method for detecting the internal resistance of a secondary battery by an active method is provided. In FIG. 1, the internal resistance detection device 100 of the present embodiment that detects the internal resistance of the secondary battery 10 is connected to the bus bar 23 of the electrical connection box 20-2 by electric wires 32 and 33. In addition, the electric connection box 20-2 is connected to the terminal of the bus bar 21 of the electric connection box 20-1 by the electric wire 31, and the electric connection box 20-1 is connected to the terminal (plus terminal) of the secondary battery 10 by the electric wire 30. ing.

  The internal resistance detection device 100 includes a discharge control unit 110 for causing the secondary battery 10 to discharge, a current measurement unit 120 for measuring the current of the secondary battery 10, and a voltage measurement for measuring the voltage of the secondary battery 10. Unit 130 and an arithmetic processing unit 140 that performs arithmetic processing on the internal resistance of the secondary battery 10. When the secondary battery 10 is discharged at a predetermined timing by the discharge control unit 110, the arithmetic processing unit 140 inputs the current and voltage of the secondary battery after the start of discharge from the current measurement unit 120 and the voltage measurement unit 130, respectively. Using this, the internal resistance of the secondary battery 10 is calculated.

  The discharge control unit 110 includes a current limiting resistor, a switching element, and the like (not shown), and can discharge the secondary battery 10 with an arbitrary current waveform (for example, a substantially rectangular wave or a sine wave). In addition, the internal resistance detection device 100 is connected to the connector terminal of the bus bar 23 of the electrical connection box 20-2 by the power supply wire 32 and supplied with power, and discharges the secondary battery 10 in an active manner. In addition, the discharge wire 33 is connected to another connector terminal of the bus bar 23. The voltage measurement in the internal resistance detection device 100 is performed on the line of the power supply wire 32.

  In FIG. 1, when the secondary battery 10 is discharged using the discharge control unit 110, the inside of the electric wire 30, the bus bar 21, the fuse 22, the electric wire 31, and the electric connection box 20-2 from the plus terminal of the secondary battery 10. Current flows through the discharge wire 33 via the bus bar 23 and the fuse 25. Further, in the voltage measurement after the start of discharge, the voltage appearing on the bus bar 23 in the electrical connection box 20-2 through which the discharge current flows is measured by the voltage measuring unit 130 via the power supply wire 32 and the fuse 24. Since the current flowing through the power supply wire 32 is smaller than the current flowing through the discharge wire 33, the voltage drop between the bus bar 23 and the voltage measuring unit 130 in the electrical connection box 20-2 is small and ignored. There is no problem.

  From the above, the voltage measured by the voltage measuring unit 130 is the voltage at the connection point with the fuse 24 to which the power supply wire 32 of the bus bar 23 in the electrical connection box 20-2 is connected. Therefore, in the following, the internal resistance of the secondary battery 10 is Rb, the resistance of the electric wire 30 is Rh1, the resistance of the electric wire 31 is Rh2, and the fuse connected between the bus bar 21 and the electric wire 31 in the electric junction box 20-1. The resistance of 22 is Rf. Further, the resistance from the connection point of the bus bar 21 to the electric wire 30 to the connection point to the fuse 22 is Rh3, and the resistance from the connection point of the bus bar 23 to the electric wire 31 to the connection point to the fuse 24 is Rh4. Furthermore, the total resistance of the harness from the plus terminal of the secondary battery 10 to the connection point with the fuse 24 of the bus bar 23 is Rh.

  From the above, the resistance Rh of the harness is the sum of the resistance Rh1 of the electric wire 30, the resistance Rh3 of the bus bar 21 in the electrical connection box 20-1, the resistance Rf of the fuse 22, the resistance Rh2 of the electric wire 31, and the resistance Rh4 of the bus bar 23. Rh = Rh1 + Rh2 + Rh3 + Rh4 + Rf.

  The internal resistance detection device 100 causes the discharge control unit 110 to discharge the secondary battery 10 with a predetermined discharge pattern at a predetermined timing, and measures the current and voltage at that time with the current measurement unit 120 and the voltage measurement unit 130, respectively. The arithmetic processing unit 140 inputs a current measurement value and a voltage measurement value for a predetermined period after the start of discharge from the current measurement unit 120 and the voltage measurement unit 130, respectively, and uses them to calculate the internal resistance of the secondary battery 10. .

When the resistance calculated from the current measurement value and the voltage measurement value is Rm in the arithmetic processing unit 140, the resistance Rm corresponds to the internal resistance Rb of the secondary battery 10 plus the harness resistance Rh. That is, the resistance Rm can be expressed as Rm = Rb + Rh. Thus, the internal resistance Rb of the secondary battery is Rb = Rm−Rh (1)
Given in.

  The harness resistance Rh is the resistance from the plus terminal of the secondary battery 10 to the connector terminal to which the fuse 24 of the bus bar 23 of the electrical connection box 20-2 is connected when the internal resistance detection device 100 is connected to the secondary battery 10. The value can be measured and stored in the arithmetic processing unit 140 for use. Or you may calculate and use resistance value based on the wire diameter, length, thickness, etc. of the electric wire and bus bar which can be read from a power supply wiring diagram, the electrical connection box design drawing, etc.

  The temperature of the harness changes due to heat generated by the current flowing through it, and the resistance value Rh also changes due to the influence. Therefore, it is necessary to use the resistance value at the harness temperature at that time as the harness resistance Rh used for calculating the internal resistance Rb of the secondary battery 10 of the formula (1). On the other hand, the harness resistance Rh that is measured in advance or calculated from the power supply wiring diagram or the like is a resistance value at a predetermined reference temperature. Therefore, in the internal resistance detection method of the present embodiment, the harness resistance at the reference temperature (hereinafter, this is referred to as Rhs) is used by correcting the resistance value at the actual harness temperature.

  An example of temperature characteristics (change in impedance with respect to temperature) of the internal resistance Rb and the harness resistance Rh of the secondary battery 10 is shown in FIG. In the figure, five cases with different deterioration states (SOH) of the secondary battery 10 are shown as temperature characteristics of the internal resistance Rb. Further, an actual measurement value is shown as the harness resistance Rh. As shown in the figure, the temperature characteristic of the internal resistance Rb and the temperature characteristic of the harness resistance Rh are different in change tendency with respect to temperature. Therefore, it is necessary to obtain the harness resistance Rh corresponding to the actual harness temperature and use this to calculate the internal resistance Rb of the secondary battery 10 from the equation (1).

  The internal resistance detection device 100 further includes temperature detection means 150 for detecting the harness temperature. The temperature detection means 150 may be a means for directly measuring the temperatures of the electric wires 30, 31, the bus bars 21, 23, and the fuse 22, or may measure any temperature or ambient temperature, and estimate the harness temperature therefrom. It may be a means.

When the harness temperature is detected by the temperature detecting means 150, the temperature correction is performed on the harness resistance Rhs at the reference temperature using the following equation.
Rh = Rhs × (1 + α × (Th−Ts)) (2)
here,
Rh: Harness resistance value after temperature correction α: Resistance temperature coefficient of harness Th: Harness temperature Ts: Reference temperature

  A room temperature of 25 ° C. is generally used as the reference temperature Ts. The resistance temperature coefficient α used in equation (2) corresponds to the rate of change of the harness resistance Rh with respect to the harness temperature Th, and is based on the resistance temperature coefficients of the electric wires 30, 31, bus bars 21, 23 and the fuse 22. It is to be decided. Generally, copper, aluminum, or stainless steel is used for the electric wires and bus bars, and the resistance temperature coefficient generally used is 0.00433 for copper, 0.0042 for aluminum, and 0 for stainless steel. .011.

  On the other hand, the fuse 22 is often formed of a metal compound made of tin or zinc. Therefore, the resistance temperature coefficients of the electric wires 30 and 31 and the bus bars 21 and 23 and the fuse 22 are different. FIG. 3 shows a comparison between the resistance change rate of the conductors (copper and aluminum) forming the electric wires and the bus bars and the resistance change rate of the fuse 22.

  In FIG. 3, each resistance change rate is shown normalized by a resistance change rate at 20 ° C. Further, three types of resistance change rates of the fuses are illustrated. As shown in the figure, the resistance change rate of copper and aluminum forming the electric wires and bus bars is almost the same, whereas the resistance change rate of the fuse greatly varies depending on the type. Thus, since the resistance change rate is greatly different between the conductors forming the electric wires 30 and 31 and the bus bars 21 and 23 and the fuse 22, the resistance temperature coefficient α of the harness reflects the difference in both resistance change rates. Need to be determined.

Therefore, in the internal resistance detection method of this embodiment, the resistance temperature coefficient α of the harness is calculated from the resistance temperature coefficient of the conductor forming the electric wire and the bus bar and the resistance temperature coefficient of the fuse using the following equation.
α = α1 × RC / (RC + RF) + α2 × RF / (RC + RF) (3)

  In Equation (3), RC is the sum of the resistance values at the predetermined positions of the electric wires 30 and 31 and the bus bars 21 and 23 at a predetermined temperature, and RF is the total resistance value of the fuse 22 at the predetermined temperature. Α1 and α2 are the resistance temperature coefficient of the conductors forming the electric wires 30 and 31 and the bus bars 21 and 23, respectively, and the resistance temperature coefficient of the fuse 22. In the equation (3), the resistance temperature coefficient α1 and α2 are weighted (linearly interpolated) with the resistance total value RC and RF as the resistance temperature coefficient α of the harness.

  In the internal resistance detection method of the present embodiment, the resistance temperature coefficient α of the harness is calculated from the equation (3) using the resistance temperature coefficient α1 of the conductor and the resistance temperature coefficient α2 of the fuse 22, and this is calculated by the equation (2). It is used for temperature correction of the harness resistance value Rh. In the internal resistance detection device 100, the resistance Rm is calculated by measuring the current and voltage when the secondary battery 10 is discharged by the active method. At the same time, the harness temperature Th is detected by the temperature detection means 150, and the harness resistance Rh whose temperature is corrected is calculated from the equation (2) using the detected temperature. Further, the internal resistance Rb is calculated from the equation (1) using the resistance Rm and the harness resistance Rh. Thereby, the influence of the resistance of the harness can be reduced and the internal resistance Rb of the secondary battery 10 can be accurately detected.

In the above description, it is assumed that the temperature correction of the harness resistance Rh is performed with high accuracy using the expression (2). However, the present invention is not limited to this. It may be created and used. Table 1 shows an example of a table in which the harness temperature Th is compared with the harness resistance Rh.

(Second Embodiment)
A method of detecting the internal resistance of the secondary battery according to the second embodiment of the present invention will be described with reference to FIG. FIG. 4 is a connection diagram in which the internal resistance detection device 200 used in the secondary battery internal resistance detection method according to the second embodiment is connected to the secondary battery 10. In the present embodiment, a method for detecting the internal resistance of a secondary battery by a passive method is provided. The internal resistance detection device 200 of the present embodiment that detects the internal resistance of the secondary battery 10 is connected to the electrical junction box 20-2 in the same manner as the internal resistance detection device 100 of the first embodiment.

  In this embodiment, since the internal resistance of the secondary battery 10 is detected by a passive method, the internal resistance detection device 200 is not provided with the discharge control unit 110. Instead, the internal resistance detection device 200 measures the current and voltage using the current measurement unit 120 and the voltage measurement unit 130 when the engine is cranked or when a large current load is operated. Inputs the current measurement value and the voltage measurement value to calculate the internal resistance of the secondary battery 10.

  Since the internal resistance detection device 200 does not have the discharge control unit 110, the internal resistance detection device 200 is connected to the electrical connection box 20-2 only by the power supply wire 32, and the discharge wire 33 is not connected. The timing for detecting the internal resistance of the secondary battery 10 can be set when an external signal associated with engine cranking or large current load operation is input or when a manual request is made. Alternatively, the current measured by the current measurement unit 120 may be monitored, and the time when the internal resistance of the secondary battery 10 is detected may be when a current of a predetermined value or more is detected. Here, an example will be described in which the internal resistance detection timing of the secondary battery 10 by the passive method is set at the time of engine cranking, that is, when a large current is discharged from the secondary battery 10 to the engine starter 40.

  In FIG. 4, when the secondary battery 10 discharges to the engine starter 40, a large current flows from the plus terminal of the secondary battery 10 to the engine starter 40 via the electric wire 30 and the bus bar 21. In the voltage measurement after the start of discharge, the voltage of the bus bar 21 through which the discharge current flows is measured by the voltage measuring unit 130 via the electric wire 31 and the power supply wire 32. The current flowing from the bus bar 21 to the power supply wire 32 via the fuse 22, the electric wire 31, the bus bar 23 in the electric connection box 20-2 and the fuse 24 is smaller than the current flowing from the bus bar 21 to the engine starter 40. The voltage drop between the bus bar 21 and the voltage measuring unit 130 is small and can be ignored.

  From the above, the voltage measured by the voltage measuring unit 130 is the voltage at the connection point with the fuse 22 to which the electric wire 31 of the bus bar 21 in the electrical connection box 20-1 is connected. From this, in the internal resistance detection method of the secondary battery of this embodiment, the resistance Rh of the harness is substantially equal to the sum of the resistance Rh1 of the electric wire 30 and the resistance Rh3 of the bus bar 21 in the electrical connection box 20-1. Rh = Rh1 + Rh3.

  When a large current is discharged from the secondary battery 10 to the engine starter 40, the internal resistance detection device 200 measures the current and voltage at that time by the current measurement unit 120 and the voltage measurement unit 130, respectively. The arithmetic processing unit 140 inputs a current measurement value and a voltage measurement value for a predetermined period after the start of discharge from the current measurement unit 120 and the voltage measurement unit 130, respectively, and calculates the resistance Rm using them. Since the resistance Rm is expressed as Rm = Rb + Rh, the internal resistance Rb of the secondary battery can be calculated using the formula (1).

  The harness resistance Rh is a resistance value from the plus terminal of the secondary battery 10 to the connection point with the fuse 22 of the bus bar 21 in the electrical connection box 20-1 when the internal resistance detection device 200 is connected to the secondary battery 10. Can be measured and stored in the arithmetic processing unit 140 for use. Or you may calculate and use resistance value based on the wire diameter, length, thickness, etc. of the electric wire and bus bar which can be read from a power supply wiring diagram, the electrical connection box design drawing, etc.

  As the harness resistance Rh, it is necessary to detect the harness temperature Th and correct the harness resistance Rhs at the reference temperature as in the first embodiment. Therefore, also in the present embodiment, the harness resistance Rh is calculated using Expression (2).

  By the way, in this embodiment, the resistance of the fuse is not included in the harness resistance Rh, and only the resistance of the electric wire 30 and the resistance of the bus bar 21 are included. Therefore, the resistance temperature coefficient of the conductor used to form the electric wire 30 and the bus bar 21 may be used as the resistance temperature coefficient α of the harness used in Expression (2). As an example, when the electric wire 30 and the bus bar 21 are made of copper, the resistance temperature coefficient of copper is 0.00433, and when the electric wire 30 and the bus bar are made of aluminum, the resistance temperature coefficient of aluminum is 0.0042 and is formed of stainless steel. If it is, stainless steel having a temperature coefficient of resistance of 0.011 may be used.

  In the internal resistance detection method of the present embodiment, when a large current is discharged to the engine starter 40, the internal resistance detection device 200 measures the current and voltage during discharge to calculate the resistance Rm. At the same time, the harness temperature Th is detected by the temperature detection means 150, and the harness resistance Rh whose temperature is corrected is calculated from the equation (2) using the detected temperature. Further, the internal resistance Rb is calculated from the equation (1) using the resistance Rm and the harness resistance Rh. Thereby, the influence of the resistance of the harness can be reduced and the internal resistance Rb of the secondary battery 10 can be accurately detected.

  Also in this embodiment, instead of performing the temperature correction of the harness resistance Rh using the formula (2), a table as shown in Table 1 in which the harness temperature Th and the harness resistance Rh are compared is previously provided. It may be created and used.

(Third embodiment)
A method for detecting the internal resistance of the secondary battery according to the third embodiment of the present invention will be described below. As 3rd Embodiment, the internal resistance of a secondary battery is detected by a passive system using the internal resistance detection apparatus 100 of 1st Embodiment. That is, when the secondary battery 10 is discharged to the engine starter 40, the current and voltage at that time are measured using the current measurement unit 120 and the voltage measurement unit 130, and the secondary battery 10 is measured in the same manner as in the second embodiment. Detect the internal resistance.

  Further, the secondary battery 10 is discharged using the discharge control unit 110 at a predetermined timing, and the internal resistance of the secondary battery 10 is detected in the same manner as in the first embodiment. The resistance temperature coefficient α of the harness at this time is calculated using the equation (3). The timing at which the internal resistance of the secondary battery 10 is detected by the active method using the discharge control unit 110 can be, for example, when a predetermined time has elapsed since the internal resistance was detected by the passive method.

  In the present embodiment, the internal resistance of the secondary battery 10 can be monitored at a suitable frequency by detecting the internal resistance by the active method.

  In addition, the description in this Embodiment shows an example of the internal resistance detection method and internal resistance detection apparatus of the secondary battery which concern on this invention, and is not limited to this. The detailed configuration and detailed operation of the internal resistance detection method and internal resistance detection device of the secondary battery in the present embodiment can be changed as appropriate without departing from the spirit of the present invention.

DESCRIPTION OF SYMBOLS 10 Secondary battery 20 Electric junction box 21, 23 Bus bar 22, 24, 25 Fuse 30, 31 Electric wire 32 Power supply electric wire 33 Discharge electric wire 40 Engine starter 50, 100, 200 Internal resistance detection apparatus 110 Discharge control part 120 Current measurement part 130 voltage measurement unit 140 arithmetic processing unit 150 temperature detection means

Claims (7)

Charge / discharge current and response voltage when charging / discharging the secondary battery are measured using current measuring means and voltage measuring means, respectively, and current measurement values and voltage measurements respectively input from the current measuring means and the voltage measuring means. A secondary battery internal resistance detection method for calculating an internal resistance of the secondary battery using a value,
Calculating a harness resistance Rh from a terminal of the secondary battery to a predetermined position of a current path through which the charge / discharge current flows;
An internal resistance detection method for a secondary battery, wherein the internal resistance is calculated by subtracting the harness resistance Rh from a resistance value Rm calculated from the current measurement value and the voltage measurement value. When the harness temperature of the current path is Th, the resistance temperature coefficient of the current path is α, the harness resistance at a predetermined reference temperature Ts is Rhs, and the harness resistance at the harness temperature Th is Rh, The harness resistance Rh is represented by the following formula: Rh = Rhs × (1 + α × (Th−Ts))
The internal resistance detection method according to claim 1, wherein the internal resistance is calculated by subtracting the calculated harness resistance Rh from the resistance value Rm. When the current path from the terminal of the secondary battery to the predetermined position is composed of a fuse and a conductor, the resistance value RF of the fuse and the resistance value RC of the conductor at a predetermined temperature are determined in advance,
When the resistance temperature coefficient of the conductor is α1 and the resistance temperature coefficient of the fuse is α2, the resistance temperature coefficient α of the current path is calculated by the following equation: α = α1 × RC / (RC + RF) + α2 × RF / ( RC + RF)
The method for detecting the internal resistance of the secondary battery according to claim 2. Having discharge means for discharging a predetermined discharge current from the secondary battery;
4. The internal resistance is calculated by measuring the discharge current and the response voltage when the secondary battery is discharged from the discharge unit using the discharge unit. 5. Method for detecting internal resistance of secondary battery. 4. The internal resistance is calculated by measuring the discharge current and the response voltage when a large current of a predetermined value or more is discharged from the secondary battery. 5. The internal resistance detection method of the secondary battery as described. An internal resistance detection device for a secondary battery that calculates the internal resistance of the secondary battery by measuring a charge / discharge current and a response voltage when charging and discharging the secondary battery,
A current measuring unit for measuring the charge / discharge current;
A voltage measuring unit for measuring the response voltage;
An arithmetic processing unit for calculating the internal resistance,
The arithmetic processing unit includes:
Calculating a harness resistance Rh from a terminal of the secondary battery to a predetermined position of a current path through which the charge / discharge current flows;
Input a current measurement value and a voltage measurement value from the current measurement unit and the voltage measurement unit,
A resistance value Rm is calculated from the current measurement value and the voltage measurement value, and the internal resistance is calculated by subtracting the harness resistance Rh from the resistance value Rm. A temperature detecting means for detecting a harness temperature of a current path through which the charge / discharge current flows;
The harness temperature detected by the temperature detection means is Th, the resistance temperature coefficient of the current path is α, the harness resistance at a predetermined reference temperature Ts is Rhs, and the harness resistance at the harness temperature Th is Rh, And when
The arithmetic processing unit uses the following equation for the harness resistance Rh: Rh = Rhs × (1 + α × (Th−Ts))
The internal resistance detection device of a secondary battery according to claim 6, wherein the internal resistance is calculated by subtracting the calculated harness resistance Rh from the resistance value Rm.

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