JP6210015B2 - Correction method of current sensor for detecting energization current related to charging or discharging of secondary battery - Google Patents

Description

  The present invention relates to a correction method for a current sensor that detects an energization current related to charging or discharging of a secondary battery.

  In a configuration using a secondary battery, a current value is detected in order to grasp the state (SOC, resistance, input / output, etc.) of the secondary battery. In particular, in order to accurately grasp the state of the secondary battery, highly accurate detection of the current value is required.

  Some current sensors have output varying with temperature. Since fluctuations in output cause an error in grasping the state of the secondary battery, it is necessary to correct the current sensor in accordance with the temperature. Patent Document 1 describes an example of such a technique.

JP 2013-240239 A

  However, the conventional technique has a problem in that the current sensor may not be appropriately corrected according to the temperature variation.

  For example, in the configuration of Patent Document 1, the braking mode is determined based on the magnitude of temperature fluctuation, but in the first braking mode with regenerative operation, the current sensor is not corrected from the start of charging to the end of charging. . For this reason, for example, even if the temperature rises due to heat generation of the secondary battery or circuit during charging and a temperature drift occurs in the output of the current sensor, this cannot be corrected until the regenerative operation is completed.

  The present invention has been made to solve such a problem, and in a current sensor for detecting a current for energization related to charging or discharging of a secondary battery, the current sensor is further corrected in accordance with a change in temperature. It aims to provide what can be implemented appropriately.

In order to solve the above-described problem, a method according to the present invention is a correction method for a current sensor that detects a current applied to charge or discharge a secondary battery. Acquiring a temperature as a reference temperature; acquiring a reference temperature; a reference temperature acquisition step; starting energization after the reference temperature acquisition step; current and temperature acquisition step, when the reference temperature and the current temperature satisfies a predetermined relationship during energization, executes a zero-point correction of the current sensor in a state where the conduction is stopped, and a correction execution step, a plurality of two Secondary batteries are connected in parallel, a current sensor is provided for each of the secondary batteries, energization relates to the discharge of the secondary battery, and the method is based on the reference temperature and current temperature during energization. Includes a current compensation step that is executed before the correction execution step, the current compensation step stops discharging the secondary battery according to the correction execution step, and another secondary battery. step der to increase the discharge current Ru.

  According to the present invention, when the temperature fluctuates greatly during energization, the energization is interrupted and the zero point correction of the current sensor is performed.

An energization restarting step of starting energization after the correction execution step may be further provided .

  The secondary battery system according to the present invention includes a secondary battery, a current sensor, a temperature sensor for acquiring a reference temperature and a current temperature, a switch mechanism for allowing or stopping energization, a current sensor, and a temperature sensor. And a control device connected to the switch mechanism, the control device performing the method described above.

  According to the present invention, when the temperature fluctuates greatly during energization, the energization is interrupted and the zero point correction of the current sensor is performed, so that the current sensor can be more appropriately corrected according to the temperature variation. .

It is a figure which shows the structure containing the battery pack which concerns on Embodiment 1 of this invention. 3 is a flowchart showing the operation of the battery ECU of FIG. It is a figure which shows the structure containing the battery pack which concerns on Embodiment 2 of this invention. It is a flowchart which shows operation | movement of battery ECU of FIG.

Embodiments of the present invention will be described below with reference to the accompanying drawings.
Embodiment 1 FIG.
FIG. 1 shows an example of a configuration including a battery pack 10 according to Embodiment 1 of the present invention. The battery pack 10 is mounted on a vehicle, for example. The battery pack 10 includes a battery module 20, a current sensor 30, and a main switch 40. The battery module 20, the current sensor 30, and the main switch 40 are connected in series, for example, to constitute the main circuit of the battery pack 10.

  The battery module 20 includes at least one battery cell 21. When a plurality of battery cells 21 are provided, the battery cells 21 are connected in series, for example. The battery cell 21 is a secondary battery that can be charged and discharged. Therefore, it can be said that the battery module 20 including the battery cell 21 is also a secondary battery that can be charged and discharged. Moreover, it can be said that the battery pack 10 provided with the battery cell 21 is a secondary battery pack (secondary battery system) which can be charged and discharged.

  The current sensor 30 is current detection means, and has a function of detecting the magnitude of current flowing between terminals. The current sensor 30 can be configured using, for example, a Hall element or a shunt resistor. The current sensor 30 has a non-zero temperature drift in the detected current value as its output. For example, if the current detection value at a certain temperature is accurate without error, the current detection value at a different temperature may include an error.

  The current sensor 30 has a function of correcting an error in the current detection value. For example, this correction is performed as a zero point correction. Zero point correction, for example, obtains the current value in a state where the current is zero (or a state considered to be zero), and offsets the detected current value output to this current value to zero It can be implemented as a process of determining.

  The main switch 40 functions as a switch mechanism that allows or stops energization between the terminals by connecting or disconnecting a circuit between the terminals. For example, in a state where the main switch 40 is opened and energization is stopped, the current flowing through the current sensor 30 is zero (or can be considered to be zero).

  In relation to the current sensor 30, a temperature sensor 50 for obtaining a temperature related to the current sensor 30 is provided. The temperature sensor 50 is disposed, for example, so that the temperature of the current sensor 30 can be measured (may be disposed in contact with the current sensor 30). Alternatively, the temperature sensor 50 is arranged so that the ambient temperature of the current sensor 30 can be measured. The temperature sensor 50 is arranged inside the battery pack 10 as shown in FIG.

  The battery pack 10 can exchange electric power with an external circuit via the connector 70. The external circuit may include a power source (such as a generator), may include a load (such as an auxiliary device), or may include both. In the example of FIG. 1, the external circuit includes an auxiliary machine 71 and an inverter 72. Further, the external circuit may include other components (such as a motor generator) connected to the inverter 72.

  The battery pack 10 includes a battery ECU 60. The battery ECU 60 is a control device that controls the operation of the battery pack 10. The battery ECU 60 is connected to the battery module 20, the current sensor 30, the main switch 40, the temperature sensor 50, and the connector 70, and controls these operations. The battery ECU 60 can communicate with an external computer (travel control ECU 73 in the example of FIG. 1) via the connector 70. The battery ECU 60 may be a single computer (such as a microprocessor) or may include a plurality of computers (for example, the monitoring device and the charging control device may be separate computers). When the battery module 20 is charged by connecting a charger to an external circuit, the battery ECU 60 can communicate with a charging control ECU (not shown).

  The traveling control ECU 73 is an external computer that controls the traveling operation of the vehicle, for example. The external computer may control an external circuit. In the example of FIG. 1, the travel control ECU 73 controls the power running operation and the regenerative operation of an external circuit (for example, a motor generator) by controlling the operation of the inverter 72.

  The battery ECU 60 monitors the state of the battery module 20 and the battery cell 21. In particular, the battery ECU 60 calculates the SOC of the battery module 20 based on the current detection value transmitted from the current sensor 30. For this reason, if an error is included in the current detection value, an error may also appear in the SOC. Therefore, it is preferable to reduce the error of the current detection value.

Hereinafter, the operation of the battery pack 10 will be described.
FIG. 2 is a flowchart showing the operation of the battery ECU 60. This flowchart relates to a correction method of the current sensor 30 that detects the charging current of the battery module 20 or the battery cell 21.

  The process shown in FIG. 2 is started in response to the battery ECU 60 receiving a charge start instruction from the outside (step S1). The charge start instruction is transmitted from the travel control ECU 73 via the connector 70, for example. If the battery ECU 60 has not received the charge start instruction, the process may be terminated, or the process may wait in step S1 until the charge start instruction is received. The charge start instruction may be received from an external computer (for example, a charge control ECU) (not shown), or the battery ECU 60 may determine the charge itself and start the charge without receiving the charge start instruction from the outside.

  When receiving the charging start instruction, the battery ECU 60 first stops energization (step S2). Here, “energization” includes both charging and discharging. That is, charging is stopped during charging, and discharging is stopped during discharging. The operation of stopping energization is realized by transmitting an opening command to the main switch 40, for example.

  Here, when energization is already stopped (that is, when neither charging nor discharging is performed), step S2 may not perform any operation, and energization is stopped. (For example, that the main switch 40 is opened) may be confirmed.

  Next, the battery ECU 60 performs zero point correction of the current sensor 30 (step S3, correction execution step). As a result, the current detection value of the current sensor 30 is zero-corrected in accordance with the temperature at the time of execution of step S3.

  Next, the battery ECU 60 acquires the temperature related to the current sensor 30 (step S4, reference temperature acquisition step). The temperature acquired here is set as a reference temperature Ta. Step S4 is executed, for example, by receiving information representing the temperature measured by the temperature sensor 50.

  Here, the “temperature related to the current sensor 30” may be the temperature of the current sensor 30 or a part thereof, or may be the ambient temperature of the current sensor 30. Further, it may be another temperature that can be a basis for calculating the temperature of the current sensor 30 or the ambient temperature of the current sensor 30. Since energization is stopped in step S2, step S4 is executed in a state where energization is stopped.

  Next, the battery ECU 60 starts charging the battery module 20 (step S5, energization start step). The operation for starting charging is realized by transmitting a closing command to the main switch 40, for example.

  Although not shown in FIG. 2, while the charging operation is in progress, the battery ECU 60 continuously receives the current detection value from the current sensor 30 and executes processing such as calculation of the SOC based on the current detection value. Here, since the zero point correction of the current sensor 30 is executed in the above step S3, the error of the current detection value remains at zero or a small value unless the temperature of the current sensor 30 fluctuates greatly. The accuracy of processing increases.

  Next, the battery ECU 60 acquires the temperature related to the current sensor 30 (step S6, current temperature acquisition step). This is executed, for example, by receiving information representing the temperature measured by the temperature sensor 50. Let the temperature acquired here be the present temperature Tb. The term “current temperature” does not necessarily mean the latest temperature value that changes from moment to moment, and may include those acquired after the reference temperature Ta. The current temperature Tb may be expressed as, for example, “temperature after change” or “temperature to be compared with the reference temperature”.

  Next, the battery ECU 60 determines whether or not the reference temperature Ta and the current temperature Tb satisfy a predetermined relationship during charging (step S7). The predetermined relationship is, for example, that the gap is relatively large, and the degree of the gap is determined based on the absolute value of the difference, for example. In the example of FIG. 2, the determination is made based on whether or not the absolute value of the difference between the reference temperature Ta and the current temperature Tb is greater than a predefined threshold Th.

  When the reference temperature Ta and the current temperature Tb satisfy a predetermined relationship (for example, when the temperature rises relatively greatly as the charging operation proceeds. In the example of FIG. 2, | Tb−Ta |> Th) The battery ECU 60 returns the process to step S2. That is, in this case, the charging operation that has been performed is temporarily interrupted, and the zero point correction of the current sensor 30 is performed again in a state where the charging is stopped. As a result, the current detection value of the current sensor 30 is zero-point corrected in accordance with a more accurate temperature. In this case, step S5 can be said to be a charge resuming step in which charging is started after step S3 (correction execution step).

  In this case, since the reference temperature Ta is reacquired together with the zero point correction, the new reference temperature Ta is used in the subsequent determination in step S7. As a modification, when step S4 is executed after the second time, measurement by the temperature sensor 50 may be omitted, and the current temperature Tb may be set as a new reference temperature Ta.

  In step S7, when the reference temperature Ta and the current temperature Tb do not satisfy the predetermined relationship (for example, when the temperature has not increased so much. In the example of FIG. 2, | Tb−Ta | ≦ Th). The battery ECU 60 determines whether or not the charging operation is finished (step S8). This determination is performed based on a known technique, and the determination criteria can be appropriately determined by those skilled in the art. For example, the determination may be made based on whether or not a charge end instruction has been received from the outside, or the determination may be made based on the SOC of the battery module 20.

  When the charging operation ends, the battery ECU 60 ends the process shown in FIG. On the other hand, when the charging operation has not ended, the battery ECU 60 returns the process to step S6. That is, in this case, the determination based on the temperature is repeated while continuing the charging.

  As described above, in the battery pack 10 according to the first embodiment, according to the method executed by the battery ECU 60, when the temperature related to the current sensor 30 greatly fluctuates, the charging is interrupted and the current sensor 30 becomes zero. Since the point correction is performed and then the charging is resumed, the current sensor 30 can be corrected more appropriately according to the temperature variation.

  In particular, the present invention has an exceptional effect in that it can cope with not only the environmental temperature change around the battery pack 10 but also a relatively rapid temperature change accompanying the charging operation of the battery module 20.

  Further, the present invention is generally applicable to a temperature sensor having a temperature drift that is not zero, but is particularly remarkable for a current sensor (for example, a vehicle-mounted simple current sensor) in which it is difficult to reduce the temperature drift. Has an effect.

In the first embodiment, the following modifications can be made.
The current sensor 30 may detect an energization current related to discharging instead of charging. That is, a discharge start instruction may be received in step S1, discharge may be started in step S5, and it may be determined whether or not the discharge has ended in step S8. In this case, since the discharge is temporarily interrupted from step S2 to step S3, there is a possibility that the power supply to the load may be affected. Is also applicable. Examples of configurations that can tolerate such influence include a case in which fluctuations in supply power to the load itself can be tolerated, and a case in which at least some power supply can be replaced by an external auxiliary power source.

  Steps S2 and S3 may be executed a plurality of times in a loop, but both may be omitted for the first execution. However, in that case, the zero point correction needs to be executed at a time before receiving the charging start instruction. For example, the zero point correction may be performed when the operation of the battery ECU 60 starts. Or, regardless of the charge start instruction, the zero point correction may be periodically performed in the energization stop state.

  The predetermined relationship serving as the determination criterion in step S7 is not limited to the absolute value of the difference, but can be variously defined. For example, a function or map of the reference temperature Ta and the current temperature Tb may be defined in advance, and the determination may be performed using the values. A person skilled in the art can appropriately define a relationship for suppressing a measurement error (temperature drift or the like) of the current sensor 30 within an allowable range.

Embodiment 2. FIG.
In the second embodiment, a plurality of battery modules 20 are provided in the first embodiment, and a cooperation process is performed between the battery modules 20. Hereinafter, differences from the first embodiment will be described.

  FIG. 3 shows an example of a configuration including battery pack 110 according to Embodiment 2 of the present invention. The battery pack 110 includes a plurality of battery modules 120, 121, and 122. The plurality of battery modules 120, 121, 122 are connected in parallel to each other. That is, it can be said that the method according to the present embodiment includes a step of connecting a plurality of battery modules 120, 121, and 122 in parallel with each other.

  The battery pack 110 includes a plurality of current sensors 130, 131, 132 and a plurality of main switches 140, 141, 142. The plurality of current sensors 130, 131, 132 are provided for the battery modules 120, 121, 122, respectively. Similarly, a plurality of main switches 140, 141, 142 are also provided for the battery modules 120, 121, 122, respectively. That is, it can be said that the method according to this embodiment includes a step of providing a plurality of current sensors 130, 131, 132 and a plurality of main switches 140, 141, 142 for the battery modules 120, 121, 122, respectively. .

  The battery modules 120, 121, 122, the corresponding current sensors 130, 131, 132 and the main switches 140, 141, 142, for example, are connected in series to constitute each battery module circuit. Each battery module circuit is connected in parallel to each other to constitute a main circuit of the battery pack 110.

  In association with each of the current sensors 130, 131, 132, temperature sensors 150, 151, 152 are provided for acquiring the temperature associated with each current sensor.

  Battery pack 110 also includes a battery ECU 160. The battery ECU 160 calculates the SOC of the battery modules 120, 121, and 122 based on the current detection values transmitted from the current sensors 130, 131, and 132, respectively. Battery ECU 160 can individually control main switches 140, 141, and 142. In FIG. 3, lines representing connections related to the battery ECU 160 are omitted.

Hereinafter, the operation of the battery pack 110 according to Embodiment 2 will be described.
FIG. 4 shows a flowchart showing the operation of battery ECU 160 according to the second embodiment. This flowchart is applicable to not only the charging operation but also the discharging operation in the operation of the battery ECU 60 shown in FIG. 2, and further, the step S2 for stopping energization is an operation for compensating the current according to the situation. Is replaced with step S2a (current compensation step).

  Battery ECU 160 can individually execute steps S1 and S3 to S8 for each of battery modules 120, 121, and 122. That is, the same control as in the first embodiment can be executed for each of battery modules 120, 121, and 122. However, any of the steps may be executed in common for a plurality of battery modules. For example, in step S1, after receiving a charge / discharge start instruction for the entire battery pack 110, the battery ECU 160 may determine a battery module to be charged / discharged, and the processes after step S2a may be executed only for that battery module. .

  In step S2a, the battery ECU 160 stops energization and compensates the current according to the situation. Here, “compensate for current” means that, when the charge / discharge current of the entire battery pack 110 is changed by stopping the charge / discharge of a battery module, the charge / discharge of another battery module is controlled and replaced. Thus, the charging / discharging current of the entire battery pack 110 is prevented from changing before and after step S2a (or the fluctuation amount before and after step S2a is made smaller).

  For example, it is assumed that the temperature of the battery module 120 changes while the battery module 120 is discharging, and | Tb−Ta |> Th is satisfied for the battery module 120. In this case, battery ECU 160 stops discharging battery module 120 and increases the discharging current of another battery module (for example, battery module 121) in step S2a.

  The control for increasing the discharge current includes the following control. For example, when the battery module 121 is not charging / discharging, discharging is started. For example, when the battery module 121 is already being discharged, the discharge current is increased. (When the battery module 121 is being charged, the charging current may be reduced.)

  Specific control when stopping the discharge of the battery module 120 to be subjected to zero point correction (such as the opening timing of the main switch 140), or specific control when increasing the discharge current of another battery module 121 ( A person skilled in the art can appropriately design the interlocking control between the main switch 140 and the main switch 141.

  When the other battery module 121 starts discharging, the discharging operation may be performed on the other battery module 121 itself in the same manner as the charging operation according to the flowchart of FIG. 2 or FIG. 4 (that is, , Discharge operation including zero point correction may be performed).

  The amount by which the discharge current is increased can be, for example, the value of the current that has been discharged by the battery module 120. In this case, the discharge current of the entire battery pack 110 does not change before and after step S2a. Even if the value is smaller than this, if the amount by which the discharge current is increased is not zero, the change in the discharge current of the entire battery pack 110 before and after step S2a can be kept relatively small.

  Moreover, the battery module which concerns on the increase in discharge current may be plural. That is, the discharge current may be increased for battery modules 121 and 122, respectively.

  As described above, in the battery pack 110 according to the second embodiment, according to the method executed by the battery ECU 160, as in the first embodiment, the temperature related to the current sensor greatly fluctuates for the battery module being charged / discharged. In such a case, charging / discharging is interrupted, the zero point correction of the corresponding current sensor is performed, and then charging / discharging is restarted. Therefore, the correction of the current sensor according to the temperature variation can be more appropriately performed.

  Furthermore, since a plurality of battery modules are provided and another battery module is charged / discharged to compensate for a charge / discharge stop associated with zero point correction of a certain battery module, the influence on external circuits can be avoided or reduced. .

  Note that the second embodiment can be modified in the same manner as in the first embodiment.

  10, 110 Battery pack (secondary battery system), 20, 120, 121, 122 Battery module (secondary battery), 21 Battery cell (secondary battery), 30, 130, 131, 132 Current sensor, 40, 140, 141, 142 main switch (switch mechanism), 50 temperature sensor, 60, 160 battery ECU (control device), S3 correction execution step, S4 reference temperature acquisition step, S5 energization start step or energization restart step, S6 current temperature acquisition step, S2a Current compensation step, Ta reference temperature, Tb current temperature.

Claims (3)

A method for correcting a current sensor for detecting an energization current related to charging or discharging of a secondary battery,
A reference temperature acquisition step of acquiring a temperature related to the current sensor as a reference temperature in a state where energization is stopped;
An energization start step for starting energization after the reference temperature acquisition step;
After the energization start step, a current temperature acquisition step of acquiring a temperature related to the current sensor as a current temperature;
A correction execution step for performing zero point correction of the current sensor in a state where the energization is stopped when the reference temperature and the current temperature satisfy a predetermined relationship during energization ,
A plurality of the secondary batteries are connected in parallel;
The current sensor is provided for each of the secondary batteries,
The energization relates to the discharge of the secondary battery,
The method includes a current compensation step executed before the correction execution step when the reference temperature and the current temperature satisfy the predetermined relationship during energization,
The current compensation step is a step of stopping discharge of the secondary battery according to the correction execution step and increasing a discharge current of another secondary battery.
Method.   The method according to claim 1, further comprising an energization restarting step of starting energization after the correction execution step. The secondary battery;
The current sensor;
A temperature sensor for obtaining the reference temperature and the current temperature;
A switch mechanism for allowing or stopping the energization;
A control device connected to the current sensor, the temperature sensor and the switch mechanism;
The said control apparatus is a secondary battery system which performs the method of Claim 1 or 2 .

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