JP2018170847A - Electric-vehicular current monitor apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electric-vehicular current monitor apparatus provided with an excessive current monitor function, an SOC calculation function and a system abnormality detection function, at a low system cost.SOLUTION: Bus bars 16, 17 are inserted into a DC power line 7 that connects a motor-driving inverter 6 to a high-voltage battery 3, thus forming parallel first and second conduction paths 18, 19, and their resistance ratio is set at 1:1, thus applying the same current. A first current sensor 12 is disposed on the DC power line 7, with a second current sensor 13 disposed on the second conduction path 19, and the first current sensor is set at a wide detection zone capable of detecting an excessive current, with a detection zone of the second current sensor 13 narrow down to 1/2 of that of the first current sensor 12, thus improving detection accuracy. Based on a detection value of the first current sensor 12, an excessive current is determined; based on 2 times of a detection value of the second current sensor 13, an SOC of a high-voltage battery 3 is calculated; and based on a comparison between 2 times of the detection value and the detection value of the first current sensor 12, a sensor failure is determined.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a current monitoring device for an electric vehicle, and more specifically, a function for monitoring an overcurrent flowing through a power line, a function for calculating a charging rate of a traveling battery (hereinafter referred to as SOC), and a function for detecting a system abnormality. The present invention relates to a current monitoring device having both.

  As this type of electric vehicle current monitoring device, for example, a device disclosed in Patent Document 1 has been proposed. In the technique of Patent Document 1, an inverter is connected to a traveling motor that is a power source for traveling, and a high-voltage battery is connected to the inverter via a DC power line in which a main relay is interposed, thereby forming a drive circuit. Has been. The DC power supplied from the high voltage battery is converted into three-phase AC power by the inverter and supplied to the traveling motor, and the vehicle travels by the driving force of the traveling motor.

The current flowing through the DC power line is detected by a current sensor, and when the current value exceeds the upper limit value based on the design specifications of the drive circuit, an overcurrent occurrence determination is made and the main relay is opened. For this reason, electrical loads such as an inverter and a traveling motor are disconnected from the high voltage battery, and damage due to overcurrent is prevented.
By the way, for convenience of explanation, if the overcurrent monitoring function is called function 1), the following 2) and 3) may be required as functions using the detection information of the current sensor.
2) An SOC calculation function that calculates the SOC of the high-voltage battery by sequentially integrating the current flowing through the DC power line.
3) A system abnormality detection function that compares the detection values of two current sensors arranged in a DC power line and makes a current monitoring system abnormality determination based on the comparison result when any of the current sensors is considered a failure. .

The current sensor for function 1) can detect an overcurrent that is a large current that exceeds the current range by the normal charge / discharge control (in other words, detects the upper limit value based on the design specifications of the drive circuit as described above) It is necessary to have a wide detection area.
On the other hand, the current sensor for function 2) needs to have high detection accuracy capable of finely detecting a current region by normal charge / discharge control.

In order to realize function 3), it is necessary to provide at least two current sensors for comparison of detected values.
Therefore, when the above functions 1) to 3) are required, the following two current sensors can be set.
FIG. 6 is a control block diagram showing a conventional electric vehicle current monitoring apparatus.

The point that the electric load 101 such as a travel motor is connected to the high voltage battery 103 via the DC power line 102 is the same as the technique of the above-mentioned Patent Document 1. First to third current sensors 104 to 106 are disposed on the DC power line 102, and each current sensor 104 to 106 is connected to a battery ECU 107 that manages the state of the high voltage battery 103.
Although the detection accuracy is not high, the first current sensor 104 has a wide detection region in which overcurrent can be detected, and overcurrent generated in the drive circuit is monitored based on the detected value (function 1).

  The second current sensor 105 has a wide detection area like the first current sensor 104, and a system abnormality is detected based on a comparison of detection values with the first current sensor 104 (function 3). The battery ECU 107 includes a power source / detection circuit 107 a that is independent of the first current sensor 104 and the second current sensor 105, and the other current sensor 104, 105 is not affected by the failure of the other current sensor 104, 105. Current sensors 104 and 105 are operable.

Although the detection area is not wide, the third current sensor 106 has high detection accuracy capable of finely detecting current by charge / discharge control, and the SOC of the high-voltage battery 103 is calculated based on the detected value (function 2). ).
On the other hand, FIG. 7 is a control block diagram showing another conventional electric vehicle current monitoring apparatus.
First and second current sensors 201 and 202 are disposed on the DC power line 102. As in the case of FIG. 6, the power source / detection circuit 107a of the battery ECU 107 includes the first current sensor 201 and the second current sensor 202. And are independent.

The first current sensor 201 has a wide detection area like the first current sensor 104 in FIG. 6, and overcurrent generated in the drive circuit is monitored based on the detected value (function 1).
The second current sensor 202 has a wide detection area and high detection accuracy, and the SOC of the high-voltage battery 103 is calculated based on the detection value (function 2). A system abnormality is detected based on the comparison of the detected values (function 3).

JP-A-10-271603

However, since the conventional current monitoring apparatus shown in FIG. 6 requires three current sensors 104 to 106 corresponding to the functions 1) to 3), there is a problem that the system cost is high.
Further, in another conventional current monitoring apparatus shown in FIG. 7, the function 2) and the function 3) are realized by the second current sensor 202 that achieves both the detection region and the detection accuracy. However, in a general current sensor, since the detection area and the detection accuracy are in a trade-off relationship, it is impossible to satisfy both conditions with a single second current sensor 202. It must be said that the current monitoring device itself cannot be realized.

  The present invention has been made to solve such problems, and its object is to impose trade-off restrictions on the detection area and detection accuracy on the current sensor, and to reduce the cost due to the low system cost. An object of the present invention is to provide a current monitoring device for an electric vehicle that can have both a current monitoring function, an SOC calculation function, and a system abnormality detection function.

  In order to achieve the above object, a current monitoring device for an electric vehicle according to the present invention includes a first conduction path interposed in a power line connecting a traveling battery mounted on the vehicle and an electric load, and the first conductor. A second conduction path that is connected in parallel to the path and through which 1 / N (N is an arbitrary number) of the total current flowing through the power line flows by setting a resistance ratio with the first conduction path; A first current sensor having a detection region disposed in the power line and capable of detecting an overcurrent flowing in the power line; and a first current sensor disposed in the second conduction path and having a 1 / th of the detection region of the first current sensor. A second current sensor in which N is set as a detection region; overcurrent determination means for determining the presence or absence of an overcurrent based on a detection value of the first current sensor; and a multiplication value of N for the detection value of the second current sensor The charging rate for calculating the charging rate of the traveling battery based on And a sensor failure that determines whether or not the first and second current sensors are failed based on a comparison result between the output means and a value obtained by multiplying the detection value of the first current sensor and the detection value of the second current sensor by N. And determining means. (Claim 1)

  According to the current monitoring device for an electric vehicle configured as described above, the first current sensor that detects the total current flowing through the power line has a wide detection region in which overcurrent can be detected. It is possible to reliably determine whether or not there is any. The second current sensor that detects 1 / N of the total current has a detection area narrowed to 1 / N of the first current sensor, and instead has higher detection accuracy than the first current sensor. For this reason, the charging rate of the traveling battery can be calculated with high accuracy based on the multiplication value of N with respect to the detection value of the second current sensor. In addition, since the detection value of the second current sensor is multiplied by N, an equivalent comparison with the detection value of the first current sensor can be performed, so that it is possible to determine whether or not the first and second current sensors have failed.

Both the first and second current sensors can be sufficiently realized even when restrictions are imposed on the detection area and the detection accuracy that are in a trade-off relationship, and the current monitoring device can be realized by these two current sensors. To establish. Therefore, an overcurrent monitoring function, an SOC calculation function, and a sensor failure determination function can be realized at low system cost.
As another aspect, the resistance ratio between the second conduction path and the first conduction path is set by adjusting at least one of a path cross-sectional area and a path length with respect to the first conduction path. Preferred (claim 2).

According to this aspect, the resistance ratio with respect to the first conduction path is set by adjusting at least one of the path cross-sectional area and the path length of the second conduction path, whereby 1 of the total current flowing through the power line is set. / N can flow through the second conduction path.
As another aspect, a main bus bar is interposed in the power line, and both end portions of the sub bus bar are connected to a place at a predetermined interval in the longitudinal direction of the main bus bar. It is preferable that a region between the first conductive path and the second conductive path is one of the first and second conductive paths, and a region between the connection points on the sub bus bar is the other of the first and second conductive paths. Item 3).

According to this aspect, the first conductive path and the second conductive path are formed while suppressing an increase in cost by a simple configuration in which the sub bus bar is connected to the main bus bar.
As another aspect, the sensor failure determination means performs failure determination due to disconnection or short circuit of one of the current sensors when the output of either the first or second current sensor becomes 0 or maximum. And when the one current sensor for which the failure determination due to disconnection or short circuit is made by the sensor failure determination unit is the first current sensor, the overcurrent determination unit replaces the first current sensor with the first current sensor. Preferably, the presence or absence of the overcurrent is determined based on a multiplication value of N with respect to a detection value of the second current sensor.

According to this aspect, the failure determination is made when the output of either the first or second current sensor becomes 0 or the maximum, and when the failure determination is made for the first current sensor, the first current sensor Instead, based on the multiplication value of N with respect to the detection value of the second current sensor, the determination of the presence or absence of overcurrent by the overcurrent determination means is continued.
As another aspect, the sensor failure determination means performs failure determination due to disconnection or short circuit of one of the current sensors when the output of either the first or second current sensor becomes 0 or maximum. When the one current sensor for which the failure determination due to disconnection or short circuit is made by the sensor failure determination unit is the second current sensor, the charging rate calculation unit replaces the second current sensor with the second current sensor. It is preferable to calculate a charging rate of the traveling battery based on a detection value of the first current sensor.

  According to this aspect, the failure determination is made when the output of either the first or second current sensor becomes 0 or the maximum, and when the failure determination is made for the second current sensor, the second current sensor Instead, the calculation of the charging rate by the charging rate calculation means is continued based on the detection value of the first current sensor.

  According to the current monitoring apparatus for an electric vehicle of the present invention, an overcurrent monitoring function, an SOC calculation function, and a system abnormality are imposed at a low system cost after imposing trade-off restrictions on the detection area and detection accuracy on the current sensor. It is possible to have a detection function.

It is a control block diagram which shows the electric current monitoring apparatus of the electric vehicle of embodiment. It is a perspective view which shows the arrangement | positioning state of the 1st and 2nd current sensor on the bus-bar of a DC power line. It is a flowchart which shows the battery information acquisition routine which battery ECU performs. It is a flowchart which shows the 2nd sensor alternative control routine which battery ECU performs. It is a flowchart which shows the 1st sensor alternative control routine which battery ECU performs. It is a control block diagram which shows the current monitoring apparatus of the conventional electric vehicle. It is a control block diagram which shows the electric current monitoring apparatus of another conventional electric vehicle.

Hereinafter, an embodiment in which the present invention is embodied in an electric vehicle current monitoring device will be described.
FIG. 1 is a control block diagram showing a current monitoring device for an electric vehicle according to the present embodiment.
The electric vehicle of the present embodiment is an electric vehicle 1 (hereinafter sometimes simply referred to as a vehicle) provided with a travel motor 2 as a travel power source. Although not shown, the travel motor 2 is connected to the vehicle via a transmission. It is connected to one drive wheel. A high voltage battery 3 (travel battery) is mounted on the vehicle 1 as a power source for the travel motor 2, and a drive circuit 4 is formed between the travel motor 2 and the high voltage battery 3.

The drive circuit 4 will be described. An inverter 6 is connected to the traveling motor 2 via an AC power line 5, and the inverter 6 is connected to the high-voltage battery 3 via a DC power line 7 (output path). The high voltage battery 3 is configured by accommodating a large number of cells such as lithium ion batteries in a battery pack, and the voltage thereof is set to, for example, 288V.
A main relay 8 including a pair of relays 8 a and 8 b is interposed on the DC power line 7. The main relay 8 is switched between closing and opening according to ON / OFF of a power switch (not shown) of the vehicle 1. When the main relay 8 is closed, the high voltage battery 3 and the inverter 6 are electrically connected so that the traveling motor 2 can be operated. When the main relay 8 is opened, the high voltage battery 3 and the inverter 6 are electrically disconnected. Thus, the traveling motor 2 is stopped and held.

  When the traveling motor 2 is power-running while the main relay 8 is closed, the DC power of the high-voltage battery 3 is converted into three-phase AC power by the inverter 6 and supplied to the traveling motor 2 to drive the drive wheels. Run 1 The traveling motor 2 is regeneratively controlled while the vehicle 1 is decelerating or downhill, and the generated three-phase AC power is converted into DC power by the inverter 6 and charged to the high voltage battery 3.

  Although not shown in FIG. 1, various electric loads such as an air conditioner for cooling and heating are connected to the drive circuit 4 in addition to the traveling motor 2. In addition to the high voltage battery 3, a low voltage battery having a voltage of 12 V is mounted on the vehicle 1, and a part of the DC power from the high voltage battery 3 is stepped down by the DC-DC converter and charged to the low voltage battery. It is used for the operation of lighting and audio.

The state of the high voltage battery 3 is managed by the battery ECU 10 and is input as battery information from the battery ECU 10 to the vehicle ECU 11 which is an upper control unit. The battery ECU 10 and the vehicle ECU 11 each include an input / output device, a storage device (ROM, RAM, nonvolatile RAM, etc.), a central processing unit (CPU), and the like.
Although not shown, the high voltage battery 3 includes a voltage sensor and a temperature sensor, and the voltage of the high voltage battery 3 detected by the voltage sensor and the temperature of the high voltage battery 3 detected by the temperature sensor are input to the battery ECU 10. Further, between the high voltage battery 3 and one relay 8a of the main relay 8, a part of the DC power line 7 (indicated by A in FIG. 1) is configured as a bus bar. First and second current sensors 12 and 13 are disposed on the bus bar, and the current I flowing through the bus bar between the high voltage battery 3 and the traveling motor 2 is detected by the current sensors 12 and 13 respectively. Input to the ECU 10. Since the configuration of the bus bar and the setting of the current sensors 12 and 13 are characteristic portions of the present invention, details thereof will be described later.

The battery ECU 10 serves as a current monitoring device of the present invention, and has the following functions based on detection information from the first and second current sensors 12 and 13.
1) The current I flowing through the bus bar is constantly monitored, and when the current value exceeds the upper limit value corresponding to the design specification of the drive circuit 4, an overcurrent occurrence determination is made, and the occurrence of overcurrent as battery information is sent to the vehicle ECU 11 Output overcurrent monitoring function (overcurrent judgment means).
2) An SOC calculation function (charge rate calculation means) that sequentially accumulates the current I flowing through the bus bar to calculate the SOC (charge rate) of the high-voltage battery 3 and outputs the SOC to the vehicle ECU 11 as battery information.
3) The detection values of the first and second current sensors 12 and 13 are compared, and when any of the current sensors 12 and 13 is regarded as a failure based on the comparison result, an abnormality determination of the current monitoring system is made, and the battery A system abnormality detection function (sensor failure determination means) that outputs an abnormality of the current monitoring system to the vehicle ECU 11 as information. The battery ECU 10 includes power supply / detection circuits 12a and 13a that are independent from each other for the first current sensor 12 and the second current sensor 13, and is not affected by the failure of one of the current sensors 12 and 13. The other current sensors 12, 13 are operable for function 3).

In addition, the battery ECU 10 executes various processes related to the high voltage battery 3. For example, the battery ECU 10 displays a deterioration index (SOH: State of Health) indicating the degree of deterioration of the high voltage battery 3 based on detection information input from each sensor. The SOH is output to the vehicle ECU 11 as battery information.
The vehicle ECU 11 executes various controls such as operation control of the traveling motor 2 and display control of the combination meter 14 provided in the driver's seat based on various sensor information including battery information input from the battery ECU 10. For example, the target torque of the travel motor 2 is calculated based on the accelerator opening degree, the vehicle speed, and the like, and the inverter 6 is driven to achieve the target torque, and the travel motor 2 is subjected to power running control or regenerative control.

  When the occurrence of overcurrent is input from the battery ECU 10 by the function 1), the vehicle ECU 11 switches the main relay 8 from closing to opening and displays a message for prompting the vehicle inspection on the combination meter 14. As a result, all electric loads including the inverter 6 and the traveling motor 2 are disconnected from the high-voltage battery 3 to prevent damage due to overcurrent, and the vehicle 1 that has become unable to travel is brought into a sales company or the like by a carrier car. Inspected and repaired.

When the SOC is input from the battery ECU 10 by the function 2), the vehicle ECU 11 corrects the SOC by the SOH input in parallel, and sequentially calculates the cruising distance of the vehicle 1 based on the corrected SOC. Displayed on the combination meter 14. The displayed cruising range is used as a reference for charging the high-voltage battery 3 at a charging stand or the like.
When the abnormality of the current monitoring system based on the sensor failure is input from the battery ECU 10 by the function 3), the vehicle ECU 11 displays a message for prompting the vehicle inspection on the combination meter 14. Thereby, the vehicle 1 is brought into a sales company etc. by self-propelled and inspected and repaired.

  It should be noted that the battery ECU 10 when the current sensors 12 and 13 break down basically cannot perform the overcurrent detection function 1) or the SOC calculation function 2). However, only when the failure-side current sensors 12 and 13 can be specified, the functions 1) and 2) can be continued using the detection values of the normal-side current sensors 12 and 13 as an alternative. The processing of the battery ECU 10 at this time will be described later.

  By the way, as described in [Problems to be Solved by the Invention], the conventional current monitoring apparatus having the above functions 1) to 3) can be considered as shown in FIGS. However, the current monitoring device of FIG. 6 has a high system cost due to the required number of current sensors, and the current monitoring device of FIG. 7 has a detection area and a detection accuracy in a trade-off relationship. It was impossible to realize because I was not satisfied.

  In view of such a problem, the present inventor has found a measure for reducing the fluctuation range of the current I detected by one of the current sensors 12 and 13. That is, if the fluctuation range of the current I is reduced, the detection area of the current sensors 12 and 13 can be narrowed, and the detection accuracy can be improved instead. Therefore, the SOC calculation function 2) can be realized. By multiplying the detection values of the current sensors 12 and 13 by the reciprocal of the reduction ratio of the fluctuation range, an equivalent comparison with the detection values of the other current sensors 12 and 13 can be performed, and the system abnormality detection function 3) can be realized. .

In the present embodiment, the bus bar is configured based on the above knowledge and the characteristics of the current sensors 12 and 13 are set, and the details will be described.
FIG. 2 is a perspective view showing an arrangement state of the first and second current sensors 12 and 13 on the bus bar of the DC power line 7.
The bus bar includes a main bus bar 16 and a sub bus bar 17. The main bus bar 16 is linear, and although not shown, the right end is connected to the power cable of the DC power line 7 on the inverter 6 side, and the left end is connected to the power cable of the DC power line 7 on the high voltage battery 3 side. Yes. As a result, the main bus bar 16 is interposed in the middle of the DC power line 7, and a pair of bolt holes 16a are provided on the main bus bar 16 at predetermined intervals in the longitudinal direction.

  The sub bus bar 17 is substantially U-shaped, and bolt holes 17a penetrating at both ends thereof are overlapped with the bolt holes 16a of the main bus bar 16, and are connected to the main bus bar 16 by bolts and nuts (not shown). Hereinafter, the region between the bolt holes 17a (connection points) on the sub bus bar 17 (the region of the length L2 along the longitudinal direction of the sub bus bar 17) is referred to as a first conduction path 18, and the bolt hole on the main bus bar 16 is A region between 16a (connection points) (region of length L1 along the longitudinal direction of the main bus bar 16) is referred to as a second conduction path 19. The first and second conduction paths 18 and 19 are connected in parallel with each other. And the 1st conduction | electrical_connection path 18 and the 2nd conduction | electrical_connection path 19 can be formed after suppressing a cost increase with the simple structure which connected the sub bus bar 17 to the main bus bar 16 in this way.

In order to cause the same current to flow through the first and second conduction paths 18 and 19, the cross-sectional area and length thereof are set as described below.
First, since the main bus bar 16 and the sub bus bar 17 are made of the same material, for example, copper, the first and second conduction paths 18 and 19 have the same resistivity C. The first and second conduction paths 18, 19 both have the same cross-sectional shape in the entire longitudinal region, the cross-sectional area (path cross-sectional area) is A1, A2, and the length (path length) is L1. , L2.

The same voltage V is applied to the first and second conduction paths 18 and 19 via the DC power line 7, and the current I flowing in the first and second conduction paths 18 and 19 as shown in the following equation (1). Is proportional to the cross-sectional areas A1 and A2, and inversely proportional to the lengths L1 and L2.
I = V / C / ・ A1 / L1 = V / C / ・ A2 / L2 (1)
The following equation (2) can be derived from the equation (1).
A1 / L2 = A2 / L1 (2)
The cross-sectional areas A1 and A2 and the lengths L1 and L2 of the first and second conduction paths 18 and 19 are set so as to satisfy the condition of the expression (2), whereby the first and second conduction paths 18 and 19 The resistance ratio is 1: 1, and the same current I always flows. In other words, with respect to the DC power line 7 through which the entire current flows, a half current I flows through the first and second conduction paths 18 and 19.

  In the bus bar configured as described above, the first current sensor 12 is disposed in a region other than the second conduction path 19 of the main bus bar 16, that is, on the DC power line 7, and the second current sensor 13 is connected to the main bus bar 16. It is disposed on the second conduction path 19. As a result, the detection value of the second current sensor 13 is always 1/2 with respect to the detection value of the first current sensor 12. Since the same current I flows through the first and second conduction paths 18 and 19, the second current sensor 13 may be disposed on the first conduction path 18 instead of the second conduction path 19.

  Therefore, in the present embodiment, the reduction ratio of the fluctuation range of the current I detected by the second current sensor 13 is ½, and by multiplying by the reciprocal number 2, it can be regarded as the current I flowing through the DC power line 7. Thus, an equivalent comparison can be made with the detection value of the first current sensor 12. Since the first and second current sensors 12 and 13 have different detection values in this manner, the detection values are hereinafter distinguished as I1 and I2.

  The first current sensor 12 that detects the total current flowing through the DC power line 7 can detect an overcurrent that is a large current that exceeds the current range by the normal charge / discharge control in order to meet the demand of the function 1). The characteristics are set so as to have a large detection area. Further, the second current sensor 13 that detects 1/2 of the total current has its detection area narrowed to 1/2 of the first current sensor 12 in order to meet the demand of the function 2). The characteristics are set so that the detection accuracy is higher than that of the sensor 12.

When the main relay 8 is closed by turning on the power switch of the vehicle 1, the battery ECU 10 operates together with the vehicle ECU 11 and executes the battery information acquisition routine shown in FIG. 3 at a predetermined control interval.
First, in step S1, it is determined whether or not the detection value I1 of the first current sensor 12 is equal to or higher than the upper limit value Imax (corresponding to function 1). The upper limit value Imax is a threshold value set in advance based on the design specification of the drive circuit 4, and the current I equal to or higher than the upper limit value Imax can be regarded as an overcurrent to be avoided for the drive circuit 4. When the determination in step S1 is No (No), the process proceeds to step S2, which corresponds to the detection value I2 of the second current sensor 13 multiplied by 2 and added / updated to the SOC in the previous control interval (function 2). ).

  In the subsequent step S3, the absolute value (| I1−I2 × 2 |) of the difference between the detection value I1 of the first current sensor 12 and the detection value I2 of the second current sensor 13 multiplied by 2 is greater than or equal to the determination value ΔI. (Corresponding to function 3)). The determination value ΔI is a threshold value set in advance as a value exceeding the error included in the detection values I1 and I2 of the first and second current sensors 12 and 13, and when the absolute value of the difference is equal to or greater than the determination value ΔI. It can be considered that any of the current sensors 12 and 13 has failed. When the determination in step S3 is No, the routine is temporarily terminated.

As described above, when no overcurrent occurs in the drive circuit 4 (step S1) and no system abnormality occurs due to a sensor failure (step S3), functions 1) to 3) are performed by the processing of each step. Monitoring, SOC calculation, and system abnormality detection are repeatedly executed.
As described above, in the present embodiment, the first current sensor 12 has a characteristic that prioritizes a wider detection area than the detection accuracy, so that the presence or absence of overcurrent can be reliably determined, and the second current sensor 13 is higher than the detection area. Because of the characteristics giving priority to detection accuracy, the SOC of the high-voltage battery 3 can be calculated with high accuracy. Any of the current sensors 12 and 13 can be sufficiently realized even when restrictions are imposed on the detection area and the detection accuracy in a trade-off relationship.

As a result, the overcurrent monitoring function, the SOC calculation function, and the system abnormality detection function can be used without using the unrealizable second current sensor 202 having both the detection region and the detection accuracy as in the prior art shown in FIG. It is possible to establish a current monitoring device having both.
Further, since the functions 1) to 3) are realized by the first and second current sensors 12 and 13 as described above, the conventional technique shown in FIG. In comparison, the system cost can be surely reduced.

  Returning to the routine of FIG. 3, the description will be continued. When the determination of Yes (positive) is made in step S1 as an overcurrent occurrence, the process proceeds to step S4. In step S4, the generation of overcurrent is output to the vehicle ECU 11 as battery information. In this case, the main relay 8 is switched from the vehicle ECU 11 to the open state, and a message for prompting the vehicle inspection is displayed on the combination meter 14. Since the battery ECU 10 does not need to continue the functions 1) to 3) by opening the main relay 8, the routine of FIG. 3 ends.

  When the determination of Yes is made as a system abnormality in step S3, the process proceeds to step S5, and it is determined whether or not the faulty current sensors 12 and 13 can be specified. If it is determined in step S3 that the absolute value of the difference is greater than or equal to the determination value ΔI, but the detection values I1 and I2 of any of the current sensors 12 and 13 indicate intermediate values, it cannot be determined which is the normal value. Therefore, it is impossible to identify the current sensors 12 and 13 that are out of order. In this case, the determination of No is made in step S5, the process proceeds to step S6, and a system abnormality is output to the vehicle ECU 11 as battery information. Therefore, a message prompting vehicle inspection is displayed on the combination meter 14 by the vehicle ECU 11.

  When the first current sensor 12 fails, even if the actual current I flowing through the DC power line 7 does not reach the upper limit value Imax, it may be determined that an overcurrent has occurred based on the detected value I1 that is equal to or greater than the upper limit value Imax. obtain. As a result, the main relay 8 is opened, and the vehicle 1 becomes unable to travel. In addition, when the second current sensor 13 fails, the SOC far from the actual SOC of the high-voltage battery 3 is calculated, and as a result of trusting the apparent travelable distance based on the SOC, the charging timing may be missed. .

Since both are serious situations, when the system is abnormal and the failure sensor cannot be specified, the continuation of function 1) and function 2) is abandoned and the routine of FIG. 3 is terminated.
On the other hand, in step S5, when the output of any one of the current sensors 12 and 13 is 0 or the maximum, it can be determined that the failure is caused by disconnection or short circuit. Accordingly, in this case, the determination of Yes is made in step S5, and the process proceeds to step S7, where it is determined whether or not the current sensors 12, 13 that have made the failure determination are the first current sensors 12.

When the determination in step S7 is Yes, in step S8, substitution control using the detection value I2 of the second current sensor 13 instead of the first current sensor 12 (hereinafter referred to as second sensor substitution control) is started, and thereafter In step S6, the system abnormality is output to the vehicle ECU 11 as battery information.
When the determination in step S7 is No, substitution control using the detection value I1 of the first current sensor 12 instead of the second current sensor 13 (hereinafter referred to as first sensor substitution control) is started in step S9. Thereafter, the process proceeds to step S6.

When the second sensor substitution control is started in step S8, the battery ECU 10 executes a second sensor substitution control routine shown in FIG. 4 at a predetermined control interval.
First, in step S11, it is determined whether or not the value obtained by multiplying the detection value I2 of the second current sensor 13 by 2 is equal to or greater than the upper limit value Imax (corresponding to function 1). When the determination is Yes, the process proceeds to step S4 in FIG. 3, and the occurrence of overcurrent is output to the vehicle ECU 11 as battery information. Further, when the determination in step S11 is No, the process proceeds to step S12. Similarly to step S2 in FIG. 3, the detection value I2 of the second current sensor 13 is multiplied by 2, and the SOC is added and updated (function 2). The above routine is repeated.

  As described above, when the failure of the first current sensor 12 is specified by the function 3), the second sensor substitution control is executed, so that the excess of the function 1) is performed based on the detection value I2 of the second current sensor 13. Current monitoring continues. Therefore, for example, even if an overcurrent occurs in the drive circuit 4 when the traveling of the vehicle 1 is continued ignoring the display of the combination meter 14 or when the display 1 is prompted to self-travel to the sales company or the like, The main relay 8 is reliably opened by 1), and damage due to overcurrent can be prevented.

On the other hand, when the first sensor substitution control is started in step S9, the battery ECU 10 executes the first sensor substitution control routine shown in FIG. 5 at a predetermined control interval.
First, in step S21, as in step S1 of FIG. 3, it is determined whether or not the detected value I1 of the first current sensor 12 is equal to or higher than the upper limit value Imax (corresponding to function 1). The process proceeds to S4. If the determination in step S21 is No, the process proceeds to step S22, and the detection value I1 of the first current sensor 12 is added to and updated in the SOC (corresponding to function 2), and the above routine is repeated.

  Thus, when the failure of the second current sensor 13 is specified by the function 3), the SOC of the function 2) is performed based on the detection value I1 of the first current sensor 12 by executing the first sensor substitution control. The calculation of is continued. As a result, the calculation of the cruising distance of the vehicle 1 based on the SOC and the display of the cruising distance by the combination meter 14 are also continued. Due to the difference in detection accuracy between the current sensors 12 and 13, the reliability of the SOC and thus the reliability of the cruising range is reduced, but it is sufficiently useful for determining the charging timing, so the convenience is maintained. can do.

This is the end of the description of the embodiment, but the aspect of the present invention is not limited to this embodiment. For example, in the embodiment described above, the current monitoring device of the electric vehicle 1 is embodied. However, the target electric vehicle is not limited to the electric vehicle. For example, the present invention is applied to a hybrid vehicle including an engine and a traveling motor as a driving power source. You may apply.
In the above embodiment, the resistance ratio of the first and second conduction paths 18 and 19 is set to 1: 1, and the same current flows, and the detection area of the second current sensor 13 is narrowed to 1/2 of the first current sensor 12. However, this is not a limitation. 1 / N (N is an arbitrary number) of the total current flowing through the DC power line 7 is supplied to the first or second conduction paths 18 and 19, and the detection region of the second current sensor 13 is set to 1 / N of the first current sensor 12. Any change can be made as long as the condition narrowed to N is satisfied.

1 Electric vehicle (electric vehicle)
2 Traveling motor (electric load)
3 High voltage battery (running battery)
7 DC power line (power line)
10 Battery ECU (overcurrent determination means, charging rate calculation means, sensor failure determination means)
11 Vehicle ECU
12 First current sensor 13 Second current sensor 16 Main bus bar 17 Sub bus bar 18 First conduction path 19 Second conduction path

Claims (5)

A first conduction path interposed in a power line connecting a traveling battery mounted on a vehicle and an electric load;
The second current is connected in parallel to the first conduction path, and 1 / N (N is an arbitrary number) of the total current flowing through the power line is caused to flow by setting the resistance ratio with the first conduction path. A conduction path,
A first current sensor having a detection region disposed in the power line and capable of detecting an overcurrent flowing through the power line;
A second current sensor disposed in the second conduction path, wherein 1 / N of a detection region of the first current sensor is set as a detection region;
Overcurrent determination means for determining presence or absence of overcurrent based on a detection value of the first current sensor;
Charging rate calculation means for calculating a charging rate of the traveling battery based on a multiplication value of N with respect to a detection value of the second current sensor;
Sensor failure determination means for determining whether or not there is a failure in the first and second current sensors based on a comparison result between a detection value of the first current sensor and a multiplication value of N with respect to the detection value of the second current sensor; An electric vehicle current monitoring apparatus comprising: The resistance ratio between the second conduction path and the first conduction path is set by adjusting at least one of a path cross-sectional area and a path length with respect to the first conduction path. The electric vehicle current monitoring device according to claim 1. A main bus bar is interposed in the power line, and both end portions of the sub bus bar are connected to a portion at a predetermined interval in the longitudinal direction of the main bus bar, and a region between the connection points on the main bus bar is formed. The first or second conduction path is one of the first and second conduction paths, and the region between the connection points on the sub-bus bar is the other of the first and second conduction paths. The electric vehicle current monitoring device according to claim 1. The sensor failure determination means makes a failure determination due to disconnection or short circuit of one of the current sensors when the output of either the first or second current sensor becomes 0 or maximum,
The overcurrent determination unit is configured to replace the second current sensor in place of the first current sensor when the one current sensor for which the failure determination due to disconnection or short circuit is made by the sensor failure determination unit is the first current sensor. The current monitoring apparatus for an electric vehicle according to any one of claims 1 to 3, wherein the presence or absence of the overcurrent is determined based on a multiplication value of N with respect to a detection value of a current sensor. The sensor failure determination means makes a failure determination due to disconnection or short circuit of one of the current sensors when the output of either the first or second current sensor becomes 0 or maximum,
The charging rate calculating means replaces the second current sensor with the first current sensor when the one current sensor for which the failure judgment due to disconnection or short circuit is made by the sensor failure judging means is the second current sensor. The current monitoring device for an electric vehicle according to any one of claims 1 to 4, wherein a charge rate of the traveling battery is calculated based on a detection value of a current sensor.

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