JP2020108195A - Power supply device for vehicle - Google Patents

Abstract

To correct a value based on an error of a charging current which is detected by a current sensor, into a more proper value.SOLUTION: On the basis of a temperature difference detected by a temperature sensor for detecting a temperature inside of a junction box in which a current sensor is accommodated, in start and end of charging of a battery, a heat generation amount inside of the junction box is calculated and an estimate current in a case where the battery is charged is calculated on the basis of the heat generation amount. On the basis of the estimate current and a charging current of the battery detected by the current sensor, any one of the charging current, an integration value of the charging current and a full charge capacitance estimate value calculated using the integration value of the charging current is corrected.SELECTED DRAWING: Figure 2

Description

The present invention relates to a vehicle power supply device.

Conventionally, as a power supply device for a vehicle of this type, an estimated capacity that is an estimated value of a full charge capacity of a battery module is obtained by dividing an integrated amount of a current flowing through the battery module by a change amount of a storage ratio SOC of the battery module. A method for obtaining a value has been proposed (for example, see Patent Document 1). In this device, the reliability of estimation is obtained for each estimated capacity value using the amount of change in SOC, and the weighted average of the plurality of estimated capacity values is calculated using the plurality of reliability levels corresponding to the plurality of estimated capacity values. Thus, the output capacity value, which is the detection value of the full charge capacity, is obtained.

JP, 2013-250071, A

However, in the above-described power supply device, an error may occur in the charging current detected by the current sensor, and in this case, the accuracy of estimating the full charge capacity decreases. Since the full charge capacity is used when calculating and displaying the travelable distance of the vehicle, it becomes difficult to display the appropriate travelable distance when the estimation accuracy of the full charge capacity becomes low.

The vehicle power supply device of the present invention mainly aims to correct a value based on an error of the charging current detected by the current sensor to a more appropriate value.

The vehicle power supply device of the present invention employs the following means in order to achieve the above-mentioned main object.

The power supply device for a vehicle of the present invention is
A power supply device for a vehicle, comprising: a battery; and a current sensor for detecting a charging current of the battery,
A temperature sensor for detecting the temperature in the junction box accommodating the current sensor is provided,
The amount of heat generated in the junction box is calculated based on the temperature difference detected by the temperature sensor at the start and end of charging the battery, and the estimated current when the battery is charged is calculated based on the amount of heat generated. Then, based on the estimated current and the charging current, the charging current, the integrated value of the charging current, or one of the full charge capacity estimated value calculated using the integrated value of the charging current is corrected,
It is characterized by

In this vehicle power supply device of the present invention, the heat generation amount in the junction box is calculated based on the temperature difference detected by the temperature sensor at the start and end of battery charging, and the battery is charged based on this heat generation amount. Calculate the estimated current when doing. Then, based on the estimated current and the charging current detected by the current sensor, any one of the charging current, the integrated value of the charging current, and the estimated full charge capacity value calculated using the integrated value of the charging current is corrected. This makes it possible to obtain more appropriate charging current, integrated value of charging current, and estimated value of full charge capacity. That is, the value based on the error of the charging current detected by the current sensor (charging current, integrated value of charging current, estimated full charge capacity) can be corrected to a more appropriate value.

It is a block diagram which shows the outline of a structure of the electric vehicle 20 carrying the power supply device as one Example of this invention. 7 is a flowchart showing an example of full charge capacity estimation processing executed by an electronic control unit 70. It is explanatory drawing which shows an example of the map for correction value setting. It is a flowchart which shows an example of the full charge capacity estimation process of a modification. It is explanatory drawing which shows an example of the correction value setting map of a modification. It is a flowchart which shows an example of the full charge capacity estimation process of a modification. It is an explanatory view showing an example of a reflection rate setting map.

Next, modes for carrying out the present invention will be described using examples.

FIG. 1 is a configuration diagram showing an outline of a configuration of an electric vehicle 20 equipped with a full charge capacity estimation device as one embodiment of the present invention. As illustrated, the electric vehicle 20 of the embodiment includes a motor 32, an inverter 34, a battery 36 as a DC power source, and an electronic control unit 70.

The motor 32 is configured as, for example, a synchronous generator motor, and has a rotor connected to a drive shaft 26 that is connected to the drive wheels 22a and 22b via a differential gear 24. The inverter 34 is used to drive the motor 32 and is connected to the battery 36 via the power line 38 and the system main relay 35. The motor 32 is rotationally driven by the electronic control unit 70 controlling switching of a plurality of switching elements (not shown) of the inverter 34.

The battery 36 is configured as, for example, a lithium ion secondary battery or a nickel hydrogen secondary battery, and exchanges electric power with the motor 32 via the system main relay 35 and the inverter 34. That is, the power running control of the motor 32 is used to output the driving power from the motor 32 using the electric power from the battery 36, and the regenerative control of the motor 32 charges the battery 36 with the regenerative power from the motor 32.

The battery 36 is provided with a voltage sensor 36a for detecting a voltage between its terminals and a current sensor 36b for detecting a charging/discharging current b flowing in the battery 36. The voltage sensor 36a and the current sensor 36b are housed in the junction box 40 together with the system main relay 35.

The charging relay 50 is provided in the power line 52 that connects the vehicle-side connector 51 connected to the stand-side connector 91 of the charging stand 90 outside the vehicle and the power line 38. Although not shown, the charging relay 50 includes a positive electrode relay and a negative electrode relay.

Although not shown, the electronic control unit 70 is configured as a microprocessor centered on a CPU, and in addition to the CPU, a ROM for storing a processing program, a RAM for temporarily storing data, a flash memory, an input/output. It is equipped with ports, communication ports, etc.

Signals from various sensors are input to the electronic control unit 70 via input ports. The signals input to the electronic control unit 70 include, for example, the rotational position θm of the rotor of the motor 32 from a rotational position sensor (not shown) that detects the rotational position of the rotor of the motor 32, and the phase of each phase of the motor 32. The phase currents Iu, Iv, Iw of each phase of the motor 32 from a current sensor (not shown) that detects a current can be mentioned. Further, the voltage Vb of the battery 36 from the voltage sensor 36 a attached between the terminals of the battery 36, the charge/discharge current Ib of the battery 36 from the current sensor 36 b attached to the output terminal of the battery 36, the battery 36 attached to the battery 36. The temperature Tb of the battery 36 from the temperature sensor 36c and the temperature Tjb in the junction box 40 from the temperature sensor 42 attached to the junction box 40 can also be mentioned. A connection detection signal from a connection detection sensor 53 that detects whether the vehicle-side connector 51 is connected to the stand-side connector 91 or a voltage attached to the power line 52 between the vehicle-side connector 51 and the charging relay 50. The charging voltage Vchg from the sensor 52a can also be mentioned. Although not shown, an ignition signal from an ignition switch, a shift position SP from a shift position sensor that detects an operation position of a shift lever, an accelerator opening Acc from an accelerator pedal position sensor that detects a depression amount of an accelerator pedal, The brake pedal position BP from the brake pedal position sensor that detects the depression amount of the brake pedal, the vehicle speed V from the vehicle speed sensor, and the like can also be mentioned.

Various control signals are output from the electronic control unit 70 via the output port. Examples of the signal output from the electronic control unit 70 include a control signal to the inverter 34, a control signal to the system main relay 35, and a control signal to the charging relay 50. Further, information necessary for charging the charging stand 90 through the communication line of the vehicle side connector 51 and the stand side connector 91 when the vehicle side connector 51 is connected to the stand side connector 91 can also be mentioned. The electronic control unit 70 calculates the storage amount Sb and the storage ratio SOC of the battery 36 based on the integrated value of the input/output current Ib of the battery 36 from the current sensor 36b. Here, the charged amount Cb is the amount of electric power that can be discharged from the battery 36, and the charged ratio SOC is the ratio of the charged amount Cb to the total capacity Cap of the battery 36.

Here, in the electric vehicle 20 of the embodiment, the battery 36, the voltage sensor 36a, the current sensor 36b, the temperature sensor 36c, the system main relay 35, the junction box 40, the temperature sensor 42, and the electronic control unit 70 correspond to a power supply device. ..

Next, the operation of estimating the full charge capacity estimated value Mest of the battery 36 by the electric vehicle 20 of the implementation benefit will be described. FIG. 2 is a flowchart showing an example of full charge capacity estimation processing executed by the electronic control unit 70. This process is executed when learning the full charge capacity estimated value Mest when the battery 36 is charged by the electric power from the charging stand 90.

When the full charge capacity estimation process is executed, the electronic control unit 70 first calculates the temperature difference ΔT in the junk box 40 before and after the battery 36 is charged (step S100). The temperature difference ΔT is the difference (Tjb(2)) between the temperature Tjb(1) detected by the temperature sensor 42 at the start of charging the battery 36 and the temperature Tjb(2) detected by the temperature sensor 42 at the end of charging the battery 36. It can be calculated as −Tjb(1)).

Subsequently, the heat generation amount ΔQ in the junk box 40 during the charging of the battery 36 is calculated based on the temperature difference ΔT in the junk box 40 before and after the battery 36 is charged (step S110), and based on the heat generation amount ΔQ. The estimated current Iest when the battery 36 is charged is calculated (step S120). The heat generation amount ΔQ in the junk box 40 can be calculated by previously obtaining the heat capacity Cjb in the junk box and multiplying the heat capacity Cjb by the temperature difference ΔT. The estimated current Iest can be calculated from the relationship ΔQ=Iest ² ·R by previously obtaining the resistance Rjb in the junk box when charging the battery 36.

Next, the current difference ΔI (ΔI=Iest−Ib) is calculated by subtracting the current Ib detected by the current sensor 36b when the battery 36 is being charged from the calculated estimated current Iest (step S130). The correction value ki is set based on ΔI (step S140). As for the correction value ki, in the embodiment, the relationship between the current difference ΔI and the correction value ki is predetermined and stored as a correction value setting map, and when the current difference ΔI is given, the corresponding correction value ki is derived from the map. It is supposed to be set by this. FIG. 3 shows an example of the correction value setting map. In the embodiment, as shown in the correction value setting map of FIG. 3, the larger the current difference ΔI, the larger the correction value ki, and the larger the current difference ΔI, the larger the rate of change of the correction value ki. I decided to do it.

Then, the correction value ki is added to the current Ib detected by the current sensor 36b to calculate the corrected charging current Ib* (step S150), and the corrected charging current Ib* is used to calculate the full charge capacity estimated value Mest. The calculation is performed (step S160), and the full charge capacity estimation process ends. The full charge capacity estimated value Mest is calculated by using the corrected charging current Ib* to calculate the current integrated value ΣIb* during charging of the battery 36, and calculating the difference between the SOC of the battery 36 before and after charging (charging at the start of charging). It can be calculated by dividing the ratio SOC−the storage ratio SOC at the end of charging by the integrated current value ΣIb*.

In the electric vehicle 20 of the embodiment described above, the heat generation amount ΔQ in the junk box 40 is calculated based on the temperature difference ΔT before and after charging in the junction box 40 that houses the current sensor 36b that detects the charging current Ib of the battery 36. At the same time, the estimated current Iest when the battery 36 is charged is calculated based on the heat generation amount ΔT. Next, the correction value ki is set based on the current difference ΔI between the estimated current Iest and the charging current Ib detected by the current sensor 36b, and the corrected charging current Ib* obtained by adding the correction value ki to the charging current Ib is set. Ask. Then, the full charge capacity estimated value Mest is calculated using the corrected charge current Ib*. Since the charging current Ib is corrected by the correction value ki based on the temperature difference ΔT before and after charging in the junction box 40, a more appropriate corrected charging/discharging current Ib* can be obtained. Further, since the full charge capacity estimated value Mest is calculated using this more appropriate corrected charge current Ib*, the full charge capacity estimated value Mest can be made more appropriate.

In the electric vehicle 20 of the embodiment, the correction value ki is set on the basis of the current difference ΔI between the estimated current Iest and the charging current Ib detected by the current sensor 36b, and the corrected charging is performed by adding the correction value ki to the charging current Ib. The full charge capacity estimated value Mest is calculated using the current Ib*. However, the correction value ksi is set based on the current integrated value difference ΔΣI as the difference between the integrated value of the estimated current Iest and the integrated value of the charging current Ib detected by the current sensor 36b, and the integrated value ΣIb of the charging current Ib is set. The full charge capacity estimated value Mest may be calculated using the corrected charging current integrated value ΣIb* to which the correction value ksi has been added. In this case, the full charge capacity estimation process of the modification shown in FIG. 4 may be executed.

In the full charge capacity estimation process of the modified example of FIG. 4, the temperature difference ΔT in the junk box 40 before and after the battery 36 is charged is calculated (step S100), and is calculated as the temperature difference ΔT in the junk box 40 before and after the battery 36 is charged. Based on this, the heat generation amount ΔQ in the junk box 40 during the charging of the battery 36 is calculated (step S110), and the estimated current Iest when the battery 36 is charged is calculated based on this heat generation amount ΔQ (step S120). The process up to this point is the same as the full charge capacity estimation process of FIG.

Next, the integrated value (current integrated value difference) ΔΣI in the charging time of the current difference (Iest−Ib) obtained by subtracting the charging current Ib detected by the current sensor 36b from the calculated estimated current Iest is calculated (step S230). ). The integrated value of the current difference (Iest-Ib) in the charging time is synonymous with the difference between the integrated value of the estimated current Iest in the charging time and the integrated value of the charging current Ib in the charging time. Then, the correction value ksi is set based on the calculated current integrated value difference ΔΣI (step S240). As the correction value ki, the relationship between the current integrated value difference ΔΣI and the correction value ksi is predetermined and stored as a correction value setting map, and when the current integrated value difference ΔΣI is given, the corresponding correction value ksi is derived from the map. It was set by doing. FIG. 5 shows an example of the correction value setting map. In this modification, as shown in the correction value setting map of FIG. 5, the correction value ksi tends to increase as the current integrated value difference ΔΣI increases, and the change rate of the correction value ksi increases as the current integrated value difference ΔΣI increases. It was set to increase. Then, the correction value ksi is added to the integrated value ΣIb of the charging current Ib detected by the current sensor 36b to calculate the corrected charging current integrated value ΣIb* (step S250), and the corrected charging current integrated value ΣIb* is calculated. The full charge capacity estimated value Mest is calculated by using (step S260), and the full charge capacity estimation process is ended. The full-charge capacity estimated value Mest is obtained by dividing the difference between the storage ratios SOC before and after the battery 36 is charged (the storage ratio SOC at the start of charging-the storage ratio SOC at the end of charging) by the corrected charging current integrated value ΣIb*. Can be calculated by

In this modification, the correction value ksi is set based on the difference (current integrated value difference) ΔΣI between the integrated value of the estimated current Iest when the battery 36 is charged and the integrated value of the charging current Ib detected by the current sensor 36b. Then, the corrected charging current integrated value ΣIb* is obtained by adding the correction value ksi to the charging current integrated value ΣIb. Then, the full charge capacity estimated value Mest is calculated using the corrected charge current integrated value ΣIb*. In the modified example, as in the embodiment, the charging current integrated value ΣIb is corrected by the correction value ksi based on the temperature difference ΔT before and after charging in the junction box 40, so that a more appropriate corrected charge/discharge current integrated value ΣIb* is obtained. can do. Further, since the full-charge-capacity estimated value Mest is calculated using this more appropriate corrected charge current integrated value ΣIb*, the full-charge capacity estimated value Mest can be made more appropriate.

As another modification, the full charge capacity estimation process illustrated in FIG. 6 may be executed. In the full charge capacity estimation process of FIG. 6, the estimated current Iest when the battery 36 is charged is calculated similarly to the full charge capacity estimation process of FIGS. 2 and 4 (steps S100 to S120). Next, the current integrated value difference ΔΣI is calculated as in the full charge capacity estimation process of FIG. 4 (step S230).

Then, the reflection rate σ is set based on the calculated current integrated value difference ΔΣI (step S340). The reflection rate σ indicates the degree of reflection of the full charge capacity calculated using the charging current Ib in the currently calculated full charge capacity estimated value Mest to the previously calculated full charge estimated value Mest, and in this modified example. , The relationship between the integrated current value difference ΔΣI and the reflection rate σ is predetermined and stored as a reflection rate setting map, and when the integrated current value difference ΔΣI is given, the corresponding reflection rate σ is derived from the map to set. I decided to do it. FIG. 7 shows an example of the reflection rate setting map. In the reflection rate setting map of FIG. 7, the larger the absolute value of the current integrated value difference ΔΣI is, the smaller the tendency is, and the larger the absolute value of the current integrated value difference ΔΣI is, the larger the absolute value of the change rate is. σ is set.

Then, the full charge capacity estimation value M(Ib) is calculated based on the charging current Ib (step S350), and the reflection rate σ is added to the calculated full charge capacity estimation value M(Ib) as shown in the following equation (1). The full charge capacity estimated value Mest is calculated as the sum of the value obtained by multiplying by and the value obtained by multiplying the full charge capacity estimated value Mest previously calculated by this processing by the value 1 minus the reflection rate σ. (Step S360). The full-charge capacity estimated value M(Ib) is obtained by dividing the difference between the storage ratios SOC before and after the battery 36 is charged (storage ratio SOC at the start of charging-storage ratio SOC at the end of charging) by the integrated value ΣIb of the charging current Ib. It can be calculated by

Mest=M(Ib)·σ+previous Mest·(1-σ) (1)

In this modified example, the reflection rate σ is set based on the current integrated value difference ΔΣI, and the value obtained by multiplying the full charge capacity estimated value M(Ib) calculated based on the charging current Ib by the reflection rate σ and the previous value. The full charge capacity estimated value Mest is calculated as the sum of the value obtained by multiplying the full charge capacity estimated value Mest by the value 1 minus the reflection rate σ. As described above, the full charge capacity estimated value Mest is calculated using the reflection rate σ based on the temperature difference ΔT before and after charging in the junction box 40, so that the full charge capacity estimated value Mest can be made more appropriate. ..

Although the power supply device is mounted on the electric vehicle 20 in the embodiments and the modifications, the power supply device may be mounted on a hybrid vehicle or a fuel cell vehicle.

The embodiments for carrying out the present invention have been described above with reference to the embodiments. However, the present invention is not limited to these embodiments, and various embodiments are possible within the scope not departing from the gist of the present invention. Of course, it can be implemented.

INDUSTRIAL APPLICABILITY The present invention is applicable to the manufacturing industry of vehicle power supply devices and the like.

20 electric vehicle, 22a, 22b drive wheel, 24 differential gear, 26 drive shaft, 32 motor, 34 inverter, 35 system main relay, 36 battery, 36a voltage sensor, 36b current sensor, 36c temperature sensor, 38 power line, 50 charging Relay, 51 vehicle side connector, 52 electric power line, 52a voltage sensor, 53 connection detection sensor, 70 electronic control unit, 90 charging stand, 91 stand side connector.

Claims (1)

A power supply device for a vehicle, comprising: a battery; and a current sensor for detecting a charging current of the battery,
A temperature sensor for detecting the temperature in the junction box accommodating the current sensor is provided,
The amount of heat generated in the junction box is calculated based on the temperature difference detected by the temperature sensor at the start and end of charging the battery, and the estimated current when the battery is charged is calculated based on the amount of heat generated. Then, based on the estimated current and the charging current, the charging current, the integrated value of the charging current, or one of the full charge capacity estimated value calculated using the integrated value of the charging current is corrected,
A power supply device for a vehicle characterized by the above.

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