JP6600974B2 - Battery control device - Google Patents

Description

  The present invention relates to a battery control device that controls a battery.

  Conventionally, high-voltage batteries that store electric power for driving a motor are mounted on electric vehicles such as hybrid vehicles and electric vehicles. The battery has a use upper limit charge rate and a use lower limit charge rate, and current is input / output (charge / discharge) so as to be used at the charge rate during this period. This is because when the usage upper limit charging rate is exceeded, the battery is overcharged, and when it falls below the usage lower limit charging rate, the battery is overdischarged.

The state of charge (SOC) of the battery is calculated based on the voltage value of the normal battery and the integrated value of the amount of current input to and output from the battery.
In general, it is known that there is a correlation between the voltage of the battery and the charging rate, and by accumulating the current input to and output from the battery, the amount of charge (that is, the charging rate) of the battery can be known. Therefore, it is possible to calculate the charging rate using only one of the voltage value and the current amount, but the detection value error (integration error, detection error, etc.) and individual battery characteristics (degradation level and temperature) Etc.) may cause a difference between the calculated charging rate and the actual charging rate. In particular, it is desired to calculate a more accurate charging rate when used near the upper limit charging rate and the lower limit charging rate.
For this reason, the charging rate is calculated using both the voltage value and the current amount of the battery.

By the way, if a failure occurs in either the voltage detection means for detecting the voltage of the battery or the current detection means for detecting the amount of current inputted to or outputted from the battery, it becomes difficult to calculate an accurate charging rate.
For this reason, in Patent Document 1 described below, when a failure of the voltage sensor is detected, the battery current is suppressed more than usual, thereby suppressing Joule heat generated during charging and discharging to protect the battery. .

Japanese Patent No. 3659068

If a failure occurs in either the voltage detection unit or the current detection unit and an accurate charging rate cannot be calculated, it may be considered that the use of the battery is prohibited to protect the battery. However, when the battery is a power source for driving an electric vehicle, it is predicted that the user's disadvantage will increase when the vehicle suddenly becomes unusable.
In addition, compared to the case where the battery is overdischarged, it is considered that the overcharged state has a greater effect on the battery and its surroundings. A method of allowing only the output to continue running the electric vehicle is also conceivable, however, for example, when a failure occurs with a low charging rate, the power in the battery runs out before reaching the vehicle repair company etc. There is a possibility.

  The present invention has been made in view of such circumstances, and an object thereof is to make it possible to use a battery in an appropriate range when a failure occurs in either the voltage detection means or the current detection means. is there.

In order to achieve the above object, a battery control device according to the invention of claim 1 includes a voltage detection unit that detects a voltage of the battery, a current detection unit that detects an amount of current input to and output from the battery, and the voltage. If a failure is detected in one of the charge rate calculation means for calculating the charge rate of the battery and the voltage detection means or the current detection means based on the detection values of the detection means and the current detection means , a failure detection is performed. A current control means for controlling the amount of current so that the subsequent charge rate is maintained below a charge rate at the time of failure, which is a charge rate at the time of failure detection, and a failure of at least one of the voltage detection means or the current detection means. comprising a failure detection means for detecting the said current control means sets the lower limit charging rate than the failure-time charging rate, when the charging ratio is less than the limit charging rate before The same amount of current as when no failure is detected is input to and output from the battery, and when the charge rate is greater than or equal to the limit charge rate and less than or equal to the charge rate during failure than when no failure is detected. Is also characterized in that the amount of current input to the battery is suppressed .
According to a second aspect of the present invention, the battery control device further includes temperature detection means for detecting the temperature of the battery, and the current control means lowers the limited charging rate as the temperature of the battery is higher. And
According to a third aspect of the present invention, in the battery control device according to the third aspect of the present invention, the charge rate calculation unit detects the failure after one of the voltage detection unit or the current detection unit and then detects the other failure. The charging rate is tentatively calculated based on the detected value.
In the battery control device according to the invention of claim 4, the failure detection unit detects a failure of the voltage detection unit, and the charge rate calculation unit detects the failure after the voltage detection unit detects the failure. The charging rate is calculated based on a detection value of a detection means.

According to the present invention, when a failure of the voltage detection unit or the current detection unit is detected, the charge rate of the battery after the failure detection is maintained below the charge rate at the time of failure that is the charge rate at the time of failure detection. Therefore, even after the failure of the detection means, it is advantageous in continuing the use of the battery while preventing the influence of the overcharge of the battery, for example, the failure of the battery or the damage of surrounding members due to heat generation.
In addition, since there is no restriction on the input / output to the battery other than maintaining the charging rate below the charging rate at the time of failure, it is advantageous in reducing the user's uncomfortable feeling when compared with that at the time of non-failure.
Further, in the present invention, charging to the battery (input of current) is permitted if it is in the range of the charging rate at the time of failure, so that the usable period of the battery is lengthened as compared with the case where charging to the battery is prohibited. This is advantageous in improving user convenience.
According to the present invention, after a failure is detected in one of the detection means, the charge rate is tentatively calculated based on the detection value of the other detection means in which no failure is detected. This is advantageous in continuing use while preventing overcharging of the battery.
According to the present invention, a limited charging rate lower than the failure charging rate is set, and when the charging rate is equal to or higher than the limiting charging rate and equal to or lower than the failure charging rate, an input is made to the battery than when no failure is detected. Since the amount of current is suppressed, the time until the charging rate reaches the charging rate at the time of failure can be lengthened, which is advantageous in extending the period in which the battery can be used.
According to the present invention, since the limited charging rate is set based on the battery temperature, control reflecting the state of the battery can be performed, which is advantageous in preventing overcharge more reliably.
According to the present invention, since the failure of the voltage detection means is detected and the charging rate is determined using the current detection means after the failure, the amount of current input to and output from the battery can be sequentially accumulated, and charging can be performed accurately. This is advantageous in calculating the rate.

It is explanatory drawing which shows the structure of the battery control apparatus 10 concerning embodiment. 4 is a flowchart showing processing of the battery control device 10. 5 is a graph showing an example of a change in charging rate with time when the voltage detecting means 30 is faulty.

  Exemplary embodiments of a battery control device according to the present invention will be explained below in detail with reference to the accompanying drawings. In the present embodiment, a case will be described in which the voltage detection unit of the voltage detection unit and the current detection unit fails.

(Embodiment)
FIG. 1 is an explanatory diagram illustrating a configuration of a battery control device 10 according to the embodiment.
The battery control device 10 controls the battery 12 that stores electric power for driving the electric vehicle.
In the present embodiment, it is assumed that the battery 12 is a power source for driving a hybrid vehicle equipped with the motor 14 and the engine 16.
The battery 12 is provided on an assembled battery 17 in which a plurality of battery cells 18 (18A to 18N) are connected in series, a positive-side main contactor 20 provided on the positive electrode side of the assembled battery 17, and a negative electrode side of the assembled battery 17. The negative side main contactor 22 and the precharge circuit 24 including the precharge contactor 24A and the precharge resistor 24B provided in parallel with the positive side main contactor 20 are configured as a battery pack accommodated in the housing 26. Yes.

The voltage detection unit 30 detects the voltage of the battery 12. More specifically, the voltage detection means 30 detects the cell voltage of each battery cell 18 and the battery voltage of the entire assembled battery 17.
The current detection means 32 (32A, 32B) detects the amount of current input / output to / from the battery 12. The input of current to the battery 12 corresponds to charging, and the output of current from the battery 12 corresponds to discharging.
In the present embodiment, two current detection means 32A and 32B are provided. As will be described later, in this embodiment, the charging rate is tentatively calculated only by the detection value of the current detection means 32 after the failure of the voltage detection means 30, so that the reliability of the current detection means 32 is improved. is there. If the difference between the detection values of the two current detection means 32A and 32B is within a predetermined error range, it can be determined that the current detection means 32 is operating normally, and the difference between the two detection values is an error. If it exceeds the range, it can be determined that a failure has occurred in the current detection means 32.
The temperature detection unit 34 detects the temperature of the battery 12 (battery temperature). The temperature detecting means 34 may be provided at a representative point of the assembled battery 17 or may be provided for each battery cell 18 or for each cell unit having a plurality of battery cells 18 as one unit.

The motor 14 operates using the electric power stored in the battery 12 and rotates the drive wheels of the electric vehicle. The motor 14 functions as a generator when the electric vehicle decelerates to generate a regenerative current.
An inverter (not shown) is provided between the motor 14 and the battery 12, and converts AC / DC of current input / output between the motor 14 and the battery 12.
The engine 16 rotates the drive wheels during high-speed running or the like, and rotates the motor 14 to generate a regenerative current when the charging rate of the battery 12 decreases. Thereby, even when the charging rate of the battery 12 decreases, the battery 12 can be charged at an arbitrary timing.
In the present embodiment, the motor 16 is rotated by the engine 16 to generate power. However, a generator may be provided separately from the motor 14 and the generator 16 may be driven by the engine 16 to generate power. Good.

The brake mechanism 15 reduces the rotation amount of the tire by friction when the electric vehicle is decelerated or stopped. The electric vehicle can be decelerated or stopped by using the brake mechanism 15 or by causing the motor 14 to regenerate and generating regenerative force. In general, deceleration by regenerative power is prioritized except when the battery 12 is close to full charge, and the brake mechanism 15 operates to compensate for this.
The display unit 19 is a monitor, an indicator lamp, or the like provided at a position that can be visually recognized by the driver. In the present embodiment, the display unit 19 functions as a notification unit that notifies the driver when a failure has occurred in the voltage detection unit 30 or the current detection unit 32 and prompts the operator to take measures such as repairs. To do.

The processing unit 40 includes a CPU, a ROM that stores and stores a control program, a RAM as an operation area of the control program, an EEPROM that stores various data in a rewritable manner, an interface unit that interfaces with peripheral circuits, and the like. Composed.
In FIG. 1, the processing unit 40 is illustrated outside the battery 12, but the processing unit 40 may be provided inside the battery 12.

The processing unit 40 functions as a charging rate calculation unit 42, a current control unit 44, and a failure detection unit 46 when the CPU executes the control program.
The charging rate calculation unit 42 calculates the charging rate of the battery 12 based on the detection values of the voltage detection unit 30 and the current detection unit 32. The charging rate calculation unit 42 calculates the charging rate of the battery 12 based on, for example, a map indicating a correlation between the voltage of the battery 12 and the charging rate, or an integrated value of currents input to and output from the battery 12.

The current control unit 44 controls the amount of current input to and output from the battery 12 based on the charging rate calculated by the charging rate calculation unit 42.
The current control unit 44 is configured such that the charge rate of the battery 12 does not exceed a predetermined use upper limit charge rate of the battery 12 during normal times (when the voltage detection unit 30 and the current detection unit 32 are not in failure) and the use lower limit charge. The amount of current input to and output from the battery 12 is controlled so as not to fall below the rate.
For example, when the charging rate of the battery 12 is in the vicinity of the upper limit charging rate, the current control unit 44 inhibits the regenerative operation of the motor 14 or suppresses the amount of regeneration to suppress the current input to the battery 12. The amount of deceleration corresponding to that amount is obtained by the operation of the brake mechanism 15. For example, when the charging rate of the battery 12 is close to the lower limit charging rate, the motor 14 is regenerated using the power of the engine 16 so that the battery 12 is charged.

The failure detection unit 46 detects a failure of at least one of the voltage detection unit 30 and the current detection unit 32. The failure detection unit 46 monitors, for example, the detection value of the voltage detection unit 30 or the current detection unit 32, and detects disconnection of these detection units, failure of the converter of the sensing unit, or the like.
In the present embodiment, the failure detection unit 46 detects a failure of the voltage detection unit 30.
When the failure detection unit 46 detects a failure in the voltage detection unit 30 or the current detection unit 32, the failure detection unit 46 displays a failure on the display unit 19 and notifies the driver of the failure.

Here, when a failure is detected by one of the voltage detection unit 30 or the current detection unit 32, the current control unit 44 determines the charge rate of the battery 12 after the failure is detected as the charge rate at the time of failure detection. The amount of current is controlled to maintain below. That is, after the failure is detected, control is performed so that the charging rate of the battery 12 does not increase more than when the failure is detected.
The charge rate at the time of failure detection (failure charge rate) is a charge rate calculated using a reliable detection value immediately before it is determined that the voltage detection means 30 or the current detection means 32 has failed. is there.

More specifically, after a failure is detected in one of the voltage detection unit 30 or the current detection unit 32, the charging rate calculation unit 42 tentatively determines based on the detection value of the other detection unit in which no failure is detected. Calculate the charge rate. This provisionally calculated charging rate is hereinafter referred to as “provisional charging rate”.
For example, when a failure of the voltage detection unit 30 is detected, the charging rate calculation unit 42 calculates a temporary charging rate based on the detection value of the current detection unit 32.
Then, the current control unit 44 controls the temporary charging rate to be equal to or less than the failure charging rate.
The provisional charging rate only needs to determine whether or not at least the current charging rate of the battery 12 is equal to or lower than the charging rate at the time of failure. For example, when the voltage detection unit 30 fails, it is only necessary to identify whether or not the amount of current input to the battery 12 after the failure exceeds the amount of current output from the battery 12 after the failure.
The provisional charge rate is less reliable than the charge rate calculated by the normal method, but if it is used for a relatively short time until the electric vehicle is moved to a vehicle repair shop, etc., the effect of error accumulation etc. It is thought that there are few.

Moreover, the current control means 44 sets a limited charging rate that is lower than the charging rate at the time of failure.
More specifically, the current control unit 44 inputs and outputs the same amount of current to and from the battery 12 when a failure is not detected when the temporary charging rate is less than the limited charging rate. In other words, the current supplied to the motor 14 is output from the battery 12 in conjunction with the driver's accelerator operation or the like, and the regenerative current generated by the motor 14 is input to the battery 12.
On the other hand, when the temporary charge rate is equal to or higher than the limit charge rate and equal to or lower than the charge rate at the time of failure, the amount of current input to the battery 12 is suppressed as compared to when no failure is detected. That is, the output of the current from the battery 12 is not limited, while the input of the regenerative current to the battery 12 is limited. In this case, for example, when the electric vehicle is decelerated, the amount of regeneration of the motor 14 is reduced as compared with the normal time, and the amount of deceleration using the brake mechanism 15 is increased correspondingly, thereby ensuring the same amount of deceleration as during normal time.
Further, when the temporary charging rate exceeds the charging rate at the time of failure, for example, the positive-side main contactor 20 and the negative-side main contactor 22 are turned off (opened) to forcibly disconnect the battery 12 from the high voltage load. Thus, overcharging of the battery 12 is prevented.
By setting the limited charging rate in this way, the time until the provisional charging rate reaches the failure charging rate can be extended.

The limited charging rate may depend on the temperature of the battery 12. More specifically, the limit charge rate may be lowered as the temperature of the battery 12 increases, and a margin up to the charge rate at the time of failure may be increased.
This is because the resistance value of the battery 12 is lower when the temperature is higher than when the temperature is lower, the current flows more easily, and it is predicted that the time until reaching the charging rate at the time of failure after exceeding the limited charging rate is predicted. It is.

FIG. 2 is a flowchart showing processing of the battery control device 10.
In the flowchart of FIG. 2, the battery control device 10 first detects the voltage value and current amount of the battery 12 by the voltage detection means 30 and the current detection means 32 (step S200).
Next, the failure detection means 46 determines whether or not a failure has occurred in the voltage detection means 30 based on the detection value in step S200 (step S202).
If no failure has occurred (step S202: No), the charging rate calculation means 42 calculates the charging rate of the battery 12 based on the detection value of step S200 (step S204), and the current control means 44 supplies the battery 12 to the battery 12. Current input / output is controlled (step S206). That is, the amount of current is controlled so that the charging rate of the battery 12 is in a range between the upper limit charging rate and the lower limit charging rate.
Thereafter, the process returns to step S200, and the subsequent processing is repeated.

On the other hand, when a failure has occurred (step S202: Yes), the failure detection unit 46 displays a failure on the display unit 19 (step S208), and notifies the driver of the failure of the voltage detection unit 30.
Further, the current control unit 44 stores the charging rate at the time of failure determination of the voltage detection unit 30 as a charging rate at the time of failure (step S210), and sets and stores a limited charging rate lower than the charging rate at the time of failure (step S210). Step S212).
Thereafter, the non-failed current detection means 32 detects the amount of current input / output to / from the battery 12 (step S214), and the charge rate calculation means 42 calculates a temporary charge rate based on the current amount (step S216). ).
The current control unit 44 controls the temporary charging rate so as to be maintained below the failure charging rate.
That is, when the temporary charging rate is less than the limited charging rate (temporary charging rate <restricted charging rate) (step S218: Yes), current is input to and output from the battery 12 in the same manner as when there is no failure (step S220). . That is, the same process as step S206 is performed. Thereafter, the process returns to step S214, and the subsequent processing is repeated.
Further, when the temporary charging rate is equal to or higher than the limited charging rate and equal to or lower than the failure charging rate (limited charging rate ≦ provisional charging rate ≦ failure charging rate) (step S222: Yes), the current input to the battery 12 is limited. (Step S224). That is, the amount of regeneration of the motor 14 is reduced as compared with the normal time, and the amount of deceleration using the brake mechanism 15 is increased accordingly. Thereafter, the process returns to step S214, and the subsequent processing is repeated.
When the temporary charging rate exceeds the failure charging rate (provisional charging rate> failing charging rate) (step S226), the positive-side main contactor 20 and the negative-side main contactor 22 are turned off (open). The connection between the battery 12 and the high voltage load is forcibly cut off. In this case, since the electric vehicle cannot travel, the processing according to this flowchart ends.

FIG. 3 is a graph showing an example of a change over time in the charging rate when the voltage detecting means 30 is faulty.
The vertical axis of the graph of FIG. 3 is the charging rate of the battery 12, the symbol _{Smax on the} vertical axis is the upper limit charging rate of use of the battery 12, and _Smin is the lower limit charging rate of use of the battery 12. The horizontal axis is time.
Assuming that the time at which the failure of the voltage detecting means 30 is detected is T1, from the time T0 to the time T1, current is input / output to / from the normal battery 12 according to the running state of the electric vehicle, and the charging rate is the upper limit of use. It fluctuates within the range of the charging rate S _max and the use lower limit charging rate S _min .
When a failure of the voltage detection means 30 is detected at time T1, the charging rate at that time is stored as the failure charging rate SA. Further, a limited charging rate SB (<failure charging rate) obtained by taking a predetermined margin amount M with respect to the failure charging rate SA is set and stored.

After time T1, the charging rate (provisional charging rate) is controlled to be equal to or lower than the failure charging rate SA. In other words, the current output is not particularly limited, and thus the electric vehicle can travel as usual.
On the other hand, the output of current is limited when the provisional charging rate becomes equal to or higher than the limited charging rate SB, for example, at time T2. That is, the amount of current input to the battery 12 is reduced by suppressing the amount of regeneration in the motor 14.
A line segment L1 indicates a case where the charging rate is reduced as a result of the input restriction as described above. In the line segment L1, the provisional charging rate is less than the limited charging rate SB at time T3, and thereafter the limitation on input is released.
When the provisional charging rate becomes close to the lower limit charging rate Smin, the motor 14 may be operated by the engine 16 to generate power, and the charging rate of the battery 12 may be maintained.
On the other hand, the line segment L2 indicates a case where the charging rate has increased despite the input restriction as described above. In the line segment L2, the charging rate continues to increase, and exceeds the failure charging rate SA at time T4. In this case, the current control unit 44 turns off the main contactors 20 and 22 of the battery 12 so that no more current is input to the battery 12. As a result, the electric vehicle cannot run, but the battery can be prevented from generating heat due to overcharging.

As described above, when the failure of the voltage detection means 30 or the current detection means 32 is detected, the battery control apparatus 10 according to the embodiment charges the charge rate of the battery 12 after the failure detection at the time of failure detection. The charge rate during failure, which is the rate, is maintained below.
Therefore, even after the failure of the detection means, it is advantageous in continuing to use the battery 12 while preventing the influence of the battery 12 from being overcharged, for example, the failure of the battery 12 or the damage of surrounding members due to heat generation.
Further, except that the charging rate is maintained below the charging rate at the time of failure, there is no restriction on the input / output to the battery 12, which is advantageous in reducing the user's uncomfortable feeling when compared with that at the time of non-failure.
Further, since the battery control device 10 permits charging (input of current) to the battery 12 within a range equal to or lower than the charging rate at the time of failure, the battery control device 10 uses the battery 12 as compared with the case where charging to the battery 12 is prohibited. The possible period can be extended, which is advantageous in improving user convenience.
In addition, since the battery control device 10 tentatively calculates the charging rate based on the detection value of the other detection means in which no failure is detected after the failure is detected in one of the detection means, An approximate value (provisional charging rate) can be obtained, which is advantageous in continuing use while preventing overcharging of the battery 12.
In addition, the battery control device 10 sets a limited charging rate lower than the charging rate at the time of failure, and when the charging rate is equal to or higher than the limiting charging rate and equal to or lower than the charging rate at the time of failure, the battery 12 is compared to when no failure is detected. Therefore, the time until the charging rate reaches the charging rate at the time of failure can be lengthened, which is advantageous in extending the period in which the battery 12 can be used.
In addition, if the limited charge rate is set based on the battery temperature in the battery control device 10, it is possible to perform control reflecting the state of the battery 12, which is advantageous in preventing overcharge more reliably. Become.
In addition, if the battery control device 10 detects a failure of the voltage detection means 30 and determines the charge rate using the current detection means 32 after the failure, the amount of current input to and output from the battery 12 is sequentially integrated. This is advantageous in accurately calculating the provisional charging rate.

DESCRIPTION OF SYMBOLS 10 ... Battery control apparatus, 12 ... Battery, 14 ... Motor, 16 ... Engine, 15 ... Brake mechanism, 17 ... Assembly battery, 18 (18A-18N) ... Battery cell, 19 ... Display part , 20... Positive side main contactor, 22... Negative side main contactor, 30... Voltage detection means, 32 (32 A, 32 B)... Current detection means, 34. …… Charge rate calculation means 44 …… Current control means 46 …… Failure detection means SA …… Charge rate at failure, SB …… Limited charge rate, S _max …… Upper limit charge rate, S _min …… Use Lower limit charging rate.

Claims (4)

Voltage detection means for detecting the voltage of the battery;
Current detection means for detecting the amount of current input to and output from the battery;
A charge rate calculation means for calculating a charge rate of the battery based on detection values of the voltage detection means and the current detection means;
When a failure is detected in the one of the voltage detection unit or the current detection unit, the current amount is set so that the charge rate after the failure detection is maintained below a charge rate at the time of failure, which is a charge rate at the time of failure detection. a current control means for controlling,
A failure detection means for detecting a failure of at least one of the voltage detection means or the current detection means,
The current control unit sets a limited charge rate lower than the charge rate at the time of failure, and when the charge rate is less than the limit charge rate, the current amount is the same as when the failure is not detected. Input / output to / from the battery, and when the charging rate is equal to or higher than the limit charging rate and equal to or lower than the charging rate at the time of failure, the amount of current input to the battery is suppressed more than when the failure is not detected.
A battery control device. A temperature detecting means for detecting the temperature of the battery;
The current control means lowers the limited charging rate as the temperature of the battery is higher.
The battery control device according to claim 1 . After the failure is detected by one of the voltage detection means or the current detection means, the charge rate calculation means tentatively determines the charge rate based on a detection value of the other detection means where the failure is not detected. To calculate,
The battery control apparatus according to claim 1 or 2, wherein The failure detection means detects a failure of the voltage detection means;
The charge rate calculation means calculates the charge rate based on a detection value of the current detection means after the failure is detected by the voltage detection means.
The battery control device according to claim 1 , wherein the battery control device is a battery control device.

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