JP2015224975A - Battery charge/discharge current detection device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a battery charge/discharge current detection device which, even when there is no electric load whose current consumption value is known, can appropriately correct the current value detected by a current sensor and detect the current value of a charge/discharge current with high accuracy.SOLUTION: The battery charge/discharge current detection device comprises: a first electric charge change amount calculation unit (121) for obtaining a first electric charge change amount on the basis of the value derived by integrating the current value detected by a current sensor (11) over a prescribed period, a second electric charge change amount calculation unit (122) for calculating a second electric charge change amount on the basis of the charge rate of a battery (2) in the prescribed period and the total capacity of the battery (2), a correction coefficient calculation unit (123) for calculating a gain error correction coefficient on the basis of the first and second electric charge change amounts, and a current value correction unit (124) for correcting the current value detected by the current sensor (11) on the basis of the gain error correction coefficient.

Description

  The present invention relates to a battery charge / discharge current detection device for a battery mounted on a vehicle or the like.

  Conventionally, a current value of a battery mounted on a vehicle is detected by a current sensor connected to the battery. In general, the detected value of the current sensor includes an offset error (b) and a gain error (a). Here, when the charge / discharge current is x and the current sensor output is y, the relationship y = ax + b is established (FIG. 4). The offset error is the value of the current sensor output when the charge / discharge current is zero. The gain error is a ratio between the change amount of the charge / discharge current and the change amount of the current sensor output. Regarding the conventional offset error, in the case of a battery mounted on a vehicle, the current value detected by the current sensor immediately after the ignition key switch is switched from on to off is calculated as the offset error. On the other hand, with respect to the gain error, the gain error is detected based on a current change when a predetermined electric load whose current consumption value is known changes from an on state to an off state or from an off state to an on state (for example, Patent Document 1).

JP-A-2005-37286

  However, the above-described conventional method is based on the assumption that a predetermined electric load whose current consumption value is known is used as an electric load of 12 V driven by a gasoline automobile battery. Here, for example, in the case of a battery for driving an electric vehicle, there is no appropriate electric load whose current consumption value is known. For this reason, the conventional technique cannot calculate a gain error and cannot appropriately correct the current value detected by the current sensor. Therefore, the conventional technology cannot accurately detect the charge / discharge current of the battery mounted on the electric vehicle.

  Therefore, an object of the present invention made in view of the above problems is to appropriately set the current value detected by the current sensor even when there is no electric load whose current consumption value is known. It is intended to provide a battery charge / discharge current detection device that corrects and can accurately detect the current value of the charge / discharge current.

In order to solve the above-described problem, a battery charge / discharge current detection device according to a first aspect of the present invention includes:
A battery charge / discharge current detecting device provided with a current sensor for detecting a charge / discharge current of a battery for supplying electric power to an electric load,
A first charge change amount calculation unit for obtaining a first charge change amount based on a value obtained by integrating the current value detected by the current sensor over a predetermined period;
A second charge change amount calculating unit for calculating a second charge change amount based on the charge rate change amount of the battery and the total capacity of the battery during the predetermined period;
A correction coefficient calculation unit that calculates a gain error correction coefficient based on the first charge change amount and the second charge change amount;
A current value correction unit that corrects a current value detected by the current sensor based on the gain error correction coefficient;
It is characterized by providing.

The battery charge / discharge current detecting device according to the second invention is
The second charge change amount calculation unit calculates a charge rate of the battery based on a terminal voltage after a predetermined time has elapsed after the battery current becomes zero.

Moreover, the battery charge / discharge current detecting device according to the third invention is
The second charge change amount calculation unit obtains the charge rate of the battery from battery state estimation by a sequential estimation method.

Moreover, the battery charge / discharge current detection device according to the fourth aspect of the invention comprises:
The battery charge / discharge current detection device corrects the current value by a gain error correction coefficient calculated from the second charge change amount when the charge rate change amount becomes a predetermined value or more. To do.

A battery charge / discharge current detection device according to a fifth aspect of the present invention includes:
The battery charge / discharge current detection device includes a storage unit that calculates the gain error correction coefficient immediately after vehicle shipment and stores the gain error correction coefficient, and the current value correction unit is stored in the storage unit. A current value detected by the current sensor is corrected based on a gain error correction coefficient.

A battery charge / discharge current detecting device according to the sixth invention is
The total capacity of the battery is corrected based on the health level of the battery.

  According to the battery charge / discharge current detection device of the first aspect of the present invention, even when there is no electrical load whose current consumption value is known, the current value detected by the current sensor is appropriately corrected and charged. The current value of the discharge current can be detected with high accuracy.

  In addition, according to the battery charge / discharge current detecting device of the second invention, since the terminal voltage when no current flows for a long time can be regarded as an open circuit voltage (OCV), the terminal voltage is used for accuracy. The SOC (State Of Charge) can be calculated well.

  Further, according to the battery charge / discharge current detection device of the third invention, the battery charge rate can be calculated by the successive estimation method even after a predetermined time has not elapsed since the current became zero.

  According to the battery charge / discharge current detecting device of the fourth invention, the gain error correction coefficient is accurately calculated by increasing the integrated value of the current value by setting the predetermined period for integrating the current value to be equal to or greater than the predetermined value. it can. Then, by appropriately correcting the current value detected by the current sensor using the gain error correction coefficient, the current value of the charge / discharge current can be detected with higher accuracy.

  According to the battery charge / discharge current detecting device of the fifth aspect of the invention, since the gain error correction coefficient is calculated when the battery 2 is new, the total battery capacity does not change due to deterioration of the battery 2, and more accurately. A gain error correction coefficient can be calculated. Further, even if the battery 2 is replaced, the current sensor 11 is not replaced. Therefore, the current value detected by the current sensor 11 can be corrected using the gain error correction coefficient stored in the storage unit 13.

  According to the battery charge / discharge current detection device of the sixth aspect of the invention, the second charge change amount is calculated more accurately in consideration of the deterioration of the battery 2 by correcting the total capacity of the battery 2 based on the soundness level. can do. Therefore, the accuracy of the gain error correction coefficient is improved, and the current value of the charge / discharge current can be detected with higher accuracy by appropriately correcting the current value detected by the current sensor using the gain error correction coefficient.

It is a block diagram of the battery charging / discharging current detection apparatus which concerns on one Embodiment of this invention. It is a conceptual diagram which shows the relationship between 1st charge variation | change_quantity and 2nd charge variation | change_quantity. It is a flowchart which shows operation | movement of the battery charging / discharging electric current detection apparatus which concerns on one Embodiment of this invention. It is a figure which shows the relationship between charging / discharging electric current and an electric current sensor output.

  Embodiments of the present invention will be described below.

(Embodiment)
FIG. 1 is a block diagram of a battery charge / discharge current detection device 1 according to an embodiment of the present invention. In the present embodiment, an example in which battery charge / discharge current detection device 1 is mounted on a vehicle is shown. The battery charge / discharge current detection device 1 according to an embodiment of the present invention includes a current sensor 11, a control unit 12, and a storage unit 13. As an outline, the battery charge / discharge current detection device 1 detects the current value of the charge / discharge current of the battery 2 and corrects the current value.

The current sensor 11 detects the current value (I ₀ ) of the charge / discharge current of the battery 2. The current value includes an offset error and a gain error. The control unit 12 performs various controls related to the battery charge / discharge current detection device 1. The storage unit 13 stores various information related to the battery charge / discharge current detection device 1.

  Hereinafter, the control unit 12 will be described in detail. The control unit 12 includes an offset error calculation unit 120, a first charge change amount calculation unit 121, a second charge change amount calculation unit 122, a correction coefficient calculation unit 123, and a current value correction unit 124.

  The offset error calculation unit 120 calculates an offset error. Specifically, the offset error calculation unit 120 detects whether or not the ignition switch 3 has been switched from the on state to the off state (or from the off state to the on state). When the ignition switch 3 is switched from the on state to the off state (or from the off state to the on state), the offset error calculation unit 120 calculates a current change before and after the switching as an offset error.

The first charge change amount calculation unit 121 calculates the amount of change in capacity (hereinafter also referred to as Q ₁ ) of the battery 2 from time t1 to t2 based on the following formula (1) by the Coulomb count method.

Here, I in Equation (1) is a current value obtained by subtracting the offset error (b) from the current value (I ₀ ) detected by the current sensor 11, and I = I ₀ -b. Thus, the first charge change amount calculation unit 121 integrates the current value I obtained by subtracting the offset error from the current value detected by the current sensor 11 over a predetermined period (T = t2-t1). A charge change amount (Q ₁ ) of ₁ is calculated. The first charge change amount calculation unit 121 integrates the current value I ₀ detected by the current sensor 11 over a predetermined period T, and subtracts the integrated offset error from the integrated value. The charge change amount (Q ₁ ) may be calculated. That is, the first charge change amount calculation unit 121 calculates the first charge change amount (Q ₁ ) based on a value obtained by integrating the current value detected by the current sensor 11 over a predetermined period T.

On the other hand, the second charge change amount calculation unit 122 obtains the change amount (ΔSOC) of the charging rate of the battery 2 from time t1 to time t2 based on the following formula (2). Then, the second charge change amount calculation unit 122 multiplies the total capacity (FCC: Full Charge Capacity) of the battery 2 and ΔSOC based on the following formula (3), so that the battery 2 at the time t1 to t2 A capacity change amount (hereinafter also referred to as Q ₂ ) is calculated.

Note that SOC _t1 and SOC _t2 in Equation (2) are SOC values at times t1 and t2, respectively. Regarding the calculation of SOC _t1 and SOC _t2 , the second charge change amount calculation unit 122 uses the open-circuit voltage (OCV) as the terminal voltage of the battery 2 after a lapse of a predetermined time after the charge / discharge current of the battery 2 becomes zero at each time. The SOC is calculated from the OCV-SOC characteristic.

As described above, the second charge change amount calculation unit 122 is based on the ΔSOC of the predetermined period (T) in which the first charge change amount calculation unit 121 integrates the current value and the total capacity (FCC) of the battery 2. 2 charge change amount (Q ₂ ) is calculated.

Here, the relationship between the first charge change amount Q ₁ and the second charge change amount Q ₂ will be described with reference to FIG. FIG. 2 is a conceptual diagram of a change curve of the battery capacity of the battery 2 in a discharged state. A line L1 is a change curve of the battery capacity when current values including offset error and gain error (that is, I ₀ ) are integrated. A line L2 is a change curve of the battery capacity when the current value including the gain error (that is, I) is integrated. A line L3 is a change curve of the battery capacity obtained from the SOC value at each time. The line L3 is not affected by the offset error and the gain error because the battery capacity is calculated without integrating the current value. Therefore, the battery capacity can be regarded as a true value. That is, in one embodiment of the present invention, a second charge change amount (Q ₂₎ regarded as a true value which does not include the offset error and gain error, based on Q _2, the Q ₁ including gain error The current value is corrected from the ratio. Hereinafter, correction of the current value will be described.

The correction coefficient calculation unit 123 calculates a gain error correction coefficient (α) shown in the following equation (4) based on the first charge change amount Q ₁ and the second charge change amount Q ₂ .

The current value correction unit 124 corrects the current value detected by the current sensor 11 based on the gain error correction coefficient. Specifically, the current value correction unit 124 calculates a corrected current value (I _c ) based on the following formula (5).

The current value (I _c ) is a current value from which an offset error and a gain error are removed.

  Next, the operation of the battery charge / discharge current detection device 1 according to one embodiment of the present invention will be described with reference to the flowchart shown in FIG. Note that the offset error is calculated in advance by the offset error calculation unit 120.

First, the first charge change amount calculation unit 121 calculates the capacity change amount (Q ₁ ) of the battery 2 from time t1 to t2 based on Equation (1) by the Coulomb count method. Further, the second charge change amount calculation unit 122 obtains the change rate (ΔSOC) of the battery 2 from time t1 to time t2 using Equation (2). Then, the second charge change amount calculation unit 122 multiplies the total capacity (FCC) of the battery 2 by ΔSOC based on the mathematical formula (3), thereby changing the capacity change amount (Q ₂₎ of the battery 2 from time t1 to t2. ) Is calculated (step S1).

Next, the correction coefficient calculation unit 123 calculates the gain error correction coefficient (α) using the formula (4) based on the first charge change amount Q ₁ and the second charge change amount Q ₂ (step S2). .

Subsequently, the current value correction unit 124 corrects the current value detected by the current sensor 11 based on the gain error correction coefficient (α). Specifically, the current value correction unit 124 calculates a corrected current value (I _c ) based on the mathematical formula (5) (step S3). Then, the process ends.

As described above, according to the battery charge / discharge current detection device 1 according to the embodiment of the present invention, the second charge change amount (Q ₂ ) is regarded as a true value including no offset error and gain error, and Q ₂ As a reference, the current value is corrected from the ratio to Q ₁ including the gain error. Therefore, even when there is no electrical load whose current consumption value is known, the current value detected by the current sensor 11 is appropriately corrected, and the current value not including the offset error and the gain error is accurately obtained. It can be detected. Further, the SOC and the parameters of the battery 2 are estimated by using the current value of the battery 2 corrected by the battery charge / discharge current detection device 1 according to the embodiment of the present invention, thereby estimating the SOC and the parameters with higher accuracy. be able to. As a result of experiments by the present inventor, the accuracy of the SOC is improved by about 1% by using the current value corrected by the battery charge / discharge current detecting device 1 according to the embodiment of the present invention.

In the present embodiment, regarding the calculation of SOC _t1 and SOC _t2 , the terminal voltage of battery 2 after a predetermined time has elapsed after the charge / discharge current of battery 2 becomes zero is regarded as the open circuit voltage (OCV), and OCV-SOC Although the SOC is calculated from the characteristics, the calculation method is not limited to this. For example, the second charge change amount calculation unit 122 may obtain the SOC of the battery 2 at each time from state estimation by the successive estimation method. In this way, the charging rate of the battery 2 can be calculated by the successive estimation method even after a predetermined time has not elapsed since the current became zero.

The predetermined time T is appropriately set so that the first charge change amount Q ₁ and the second charge change amount Q ₂ are each equal to or greater than a predetermined value. For example, when calculating Q ₂ , ΔSOC is set to be a predetermined value (for example, 20) or more. If the integral value is small, accurate detection cannot be performed. Therefore, by setting the predetermined period of integration to be greater than or equal to the predetermined value, the integral value is increased and the current value of the charge / discharge current is detected more accurately. Can do.

Preferably, the correction coefficient calculation unit 123 stores the calculated gain error correction coefficient in the storage unit 13. Then, the current value correction unit 124 corrects the current value detected by the current sensor 11 based on the gain error correction coefficient stored in the storage unit 13. More preferably, the battery charge / discharge current detection device 1 calculates a gain error correction coefficient immediately after the vehicle is shipped, and stores the gain error correction coefficient in the storage unit 13. That is, the first charge change amount calculation unit 121 and the second charge change amount calculation unit 122 respectively calculate Q ₁ and Q ₂ immediately after vehicle shipment, and the correction coefficient calculation unit 123 sets the Q ₁ and Q _2. Based on the above, a gain error correction coefficient is calculated, and the gain error correction coefficient is stored in the storage unit 13. The current value correction unit 124 corrects the current value detected by the current sensor 11 based on the gain error correction coefficient stored in the storage unit 13. By doing so, since the gain error correction coefficient is calculated when the battery 2 is new, the total battery capacity does not change due to deterioration of the battery 2, and the gain error correction coefficient can be calculated more accurately. . Since the current sensor 11 is not replaced even when the battery 2 is replaced, the current value detected by the current sensor 11 can be corrected using the gain error correction coefficient stored in the storage unit 13.

Note Preferably, the second charge variation calculation unit 122, the health of the battery 2 when the total capacity of the battery 2: corrected by (SOH State Of Health), and calculates the Q _2. That is, the second charge change amount calculation unit 122 calculates Q ₂ using the following formula (3) ′ instead of the formula (3).

Thus, by correcting the total capacity of the battery 2 based on the soundness level, Q ₂ can be calculated with higher accuracy in consideration of the deterioration of the battery 2. Therefore, the accuracy of the gain error correction coefficient is improved, and the current value of the charge / discharge current can be detected with higher accuracy by appropriately correcting the current value detected by the current sensor 11 with the gain error correction coefficient.

  In the present embodiment, the battery charge / discharge current detection device 1 is described as being mounted on a vehicle, but the present invention is not limited to this. For example, the battery charge / discharge current detection device 1 may be mounted on an electronic device such as a personal computer or a portable terminal.

  Although the present invention has been described based on the drawings and examples, it should be noted that those skilled in the art can easily make various modifications and corrections based on the present disclosure. Therefore, it should be noted that these variations and modifications are included in the scope of the present invention. For example, the functions included in each means, each step, etc. can be rearranged so that there is no logical contradiction, and a plurality of means, steps, etc. can be combined or divided into one. .

DESCRIPTION OF SYMBOLS 1 Battery charging / discharging electric current detection apparatus 2 Battery 11 Current sensor 12 Control part 13 Memory | storage part 120 Offset error calculation part 121 1st charge change amount calculation part 122 2nd charge change amount calculation part 123 Correction coefficient calculation part 124 Current value correction | amendment Part

Claims (6)

A battery charge / discharge current detecting device provided with a current sensor for detecting a charge / discharge current of a battery for supplying electric power to an electric load,
A first charge change amount calculation unit for obtaining a first charge change amount based on a value obtained by integrating the current value detected by the current sensor over a predetermined period;
A second charge change amount calculating unit for calculating a second charge change amount based on the charge rate change amount of the battery and the total capacity of the battery during the predetermined period;
A correction coefficient calculation unit that calculates a gain error correction coefficient based on the first charge change amount and the second charge change amount;
A current value correction unit that corrects a current value detected by the current sensor based on the gain error correction coefficient;
A battery charge / discharge current detection device comprising:   2. The charge rate of the battery according to claim 1, wherein the second charge change amount calculation unit calculates a charge rate of the battery based on a terminal voltage after a predetermined time has elapsed since the current of the battery becomes zero. Battery charge / discharge current detection device.   The battery charge / discharge current detection device according to claim 1, wherein the second charge change amount calculation unit obtains the charge rate of the battery from battery state estimation by a successive estimation method.   The battery charge / discharge current detection device corrects the current value by a gain error correction coefficient calculated from the second charge change amount when the charge rate change amount becomes a predetermined value or more. The battery charge / discharge current detection device according to any one of claims 1 to 3.   The battery charge / discharge current detection device includes a storage unit that calculates the gain error correction coefficient immediately after vehicle shipment and stores the gain error correction coefficient, and the current value correction unit is stored in the storage unit. 5. The battery charge / discharge current detection device according to claim 1, wherein the current value detected by the current sensor is corrected based on a gain error correction coefficient. 6.   5. The battery charge / discharge current detection device according to claim 1, wherein the total capacity of the battery is corrected based on a health level of the battery. 6.

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