JP7622608B2 - Vehicle battery unit control device - Google Patents

Description

The technology disclosed herein relates to a vehicle battery unit control device.

Battery units used in electric vehicles and hybrid vehicles are repeatedly charged and discharged. As a result of repeated charging and discharging, the battery unit may deteriorate to the over-discharging side or to the over-charging side. The battery control device described in Patent Document 1 reduces the allowable discharge power when the battery unit deteriorates to the over-discharging side, and reduces the allowable charge power when the battery unit deteriorates to the over-charging side. In this way, the battery control device described in Patent Document 1 suppresses the progression of deterioration of the battery unit.

JP 2017-50981 A

The technology described in Patent Document 1 can suppress the progression of deterioration of a battery unit that has deteriorated to the over-discharge or over-charge side. However, this technology cannot restore the deterioration of the battery unit.

The technology disclosed here recovers deterioration of a battery unit that has an imbalance in charge and discharge rates, such as from overcharging or overdischarging.

The inventor first focused on the fact that degradation can be restored by applying a reverse pulse to a battery unit with an unbalanced charge/discharge rate. In other words, when an over-discharged battery unit is charged at a high rate, degradation can be restored, and when an over-charged battery unit is discharged at a high rate, degradation can be restored.

However, in a vehicle battery unit that is mounted on a vehicle and supplies power to the vehicle's drive unit, the discharge or charge request for the battery unit is determined according to the vehicle's driving state, and the discharge or charge rate at that time is also determined. Therefore, the opportunities for the vehicle battery unit to perform high-rate charging or high-rate discharging are limited.

The technology disclosed herein aims to recover the deterioration of an over-discharged or over-charged battery unit by increasing the opportunities for performing high-rate charging or high-rate discharging of the vehicle battery unit.

Specifically, the technology disclosed herein relates to a vehicle battery unit control device.
A drive unit that is mounted on a vehicle and generates a driving force for running the vehicle;
a battery unit including a plurality of batteries connected in parallel to the drive unit, each of the batteries being capable of being charged and discharged;
a controller that controls charging and discharging of each of the plurality of batteries in response to a charging request or a discharging request corresponding to a running state of the vehicle during normal control;
The controller includes:
In the normal control, it is determined that the battery unit is overcharged, that is, a charge rate is higher than a discharge rate, or overdischarged, that is, a discharge rate is higher than a charge rate;
If the battery unit is overcharged, recovery control is performed in response to a request to discharge the battery unit, in which only some of the plurality of batteries are discharged at a high rate;
If the battery unit is over-discharged, recovery control is performed to charge only some of the plurality of batteries at a high rate when a charge request is made for the battery unit.

During normal control, the controller controls charging and discharging of the battery unit in response to a charging request or a discharging request corresponding to the vehicle's driving state. During normal control, the battery unit may become overcharged, in which the charging rate is higher than the discharging rate, or overdischarged, in which the discharging rate is higher than the charging rate. If the controller determines that the battery unit is overcharged or overdischarged, it performs recovery control.

When the battery unit is overcharged, recovery control is to discharge the battery unit at a high rate. In the vehicle battery unit control device configured as described above, the controller uses only a portion of the multiple batteries to discharge in response to the discharge request. Because only a portion of the batteries is used, the discharge rate of those batteries must be increased to satisfy the required discharge amount. As a result, some of the batteries are discharged at a high rate, and if they are overcharged and deteriorated, the deterioration is restored. At this time, those batteries discharge in a manner that satisfies the discharge request, and the drive unit can achieve driving in accordance with the driver's intentions.

On the other hand, recovery control when the battery unit is over-discharged is control to charge the battery unit at a high rate. In the vehicle battery unit control device configured as described above, the controller uses only some of the multiple batteries to charge in response to the charging request. Because only some of the batteries are used, the charging rate of those batteries must be increased to satisfy the requested charging amount. As a result, some of the batteries are charged at a high rate, so that if they are degraded due to over-discharge, the degradation is restored. At this time, those batteries are charged in a way that satisfies the charging request, and charging that corresponds to the vehicle's driving state is realized.

In this way, the battery unit can discharge and charge the battery at a high rate while charging and discharging according to the vehicle's driving state. The vehicle battery unit control device configured as described above can increase the opportunities to recover from the deterioration of an over-discharged or over-charged battery unit. Because the deterioration of the battery unit can be recovered, the deterioration of a battery unit that has been used for a long period of time is suppressed.

the vehicle battery unit control device includes a generator to which the plurality of batteries are connected in parallel and which supplies generated power to each of the plurality of batteries;
The controller may supply the generated power of the generator to only some of the plurality of batteries during recovery control when the battery unit is over-discharged.

With this configuration, the battery unit is charged using the power generated by the generator. The battery unit can be charged not only during regenerative power generation.

In addition, since multiple batteries are connected in parallel to the generator, as mentioned above, during recovery control, the generator can supply generated power to only some of the batteries. As a result, the batteries can be charged at a high rate.

Therefore, the vehicle battery unit control device configured as described above can increase the opportunities to recover from deterioration caused by excessive discharging of the battery unit.

The controller integrates high-rate discharge power or high-rate charge power of the battery unit during the normal control,
The controller may also perform charging at a high rate corresponding to the accumulated discharge power, or discharging at a high rate corresponding to the accumulated charge power, during the recovery control.

By matching the high-rate discharge power or high-rate charge power during normal control with the high-rate charge power or high-rate discharge power during recovery control, the deterioration of the battery unit can be effectively restored.

During recovery control, the controller may switch between multiple batteries to charge or discharge at a high rate.

This allows the controller to recover from degradation in all multiple batteries.

the vehicle battery unit control device includes a plurality of converters corresponding to the plurality of batteries, each converter being connected in parallel to the drive unit;
The controller may be configured to charge or discharge a plurality of batteries using the plurality of converters during the normal control, and to charge or discharge a portion of the batteries using some of the converters during the recovery control.

During normal control, the parallel converters can use their respective step-up/step-down functions to make the voltage supplied to the drive unit from each of the multiple batteries connected in parallel to the drive unit the same voltage.

In addition, during recovery control, the parallel converters can use their respective cutoff functions to charge or discharge only some of the batteries connected in parallel to the drive unit.

the vehicle battery unit control device is connected to the drive unit and includes a converter common to the plurality of batteries,
the battery unit includes a series line that connects the plurality of batteries in series and a switch that connects and disconnects the series line;
The controller may be configured to, during the normal control, charge or discharge the multiple batteries using the converter with the multiple batteries connected in series, and, during the recovery control, charge or discharge some of the batteries using the converter with the series connection of the multiple batteries disconnected.

Even with this configuration, during normal control, all of the multiple batteries connected in series can be charged or discharged, and during recovery control, some of the batteries that have been disconnected from the series connection can be charged or discharged. This configuration also has the advantage of reducing the number of converters, since a common converter is provided for the multiple batteries.

The vehicle battery unit control device can increase the opportunities to recover from deterioration of a battery unit that has an imbalance in charge and discharge rates, such as from overcharging or overdischarging.

FIG. 1 is a diagram showing the overall configuration of a hybrid vehicle equipped with a vehicle battery unit and its control device. The upper graph in FIG. 2 shows an example of a current change in the case of overcharging, and the lower graph shows an example of a current change in the case of overdischarging. FIG. 3 illustrates the relationship between the charge/discharge rate balance and deterioration. FIG. 4 shows that the deterioration of a battery unit in which the charge/discharge rate balance has been lost can be restored by applying a reverse pulse. The upper diagram in FIG. 5 shows a state in which only the first battery is discharging, and the lower diagram shows a state in which only the second battery is discharging. The upper diagram in FIG. 6 shows a state in which only the first battery is charging, and the lower diagram shows a state in which only the second battery is charging. FIG. 7 is a flow diagram of control when a discharge request is made to the battery unit. FIG. 8 is a flow diagram of control when a charge request is made to a battery unit. FIG. 9 is a flow diagram of control when a discharge request is made to a battery unit according to a modified example. FIG. 10 is a flow diagram of control when a charging request is made to a battery unit according to a modified example. FIG. 11 is a diagram showing the overall configuration of a hybrid vehicle according to a modified example. FIG. 12 is a diagram showing the overall configuration of a hybrid vehicle according to a modified example.

Embodiments of a vehicle battery unit control device will be described below with reference to the drawings. The vehicle battery unit control device described here is an example. FIG. 1 illustrates a hybrid vehicle (Hybrid Electric Vehicle or Plug-in Hybrid Electric Vehicle) equipped with a vehicle battery unit control device. Note that the vehicle battery unit control device is not limited to application to hybrid vehicles, but can also be applied to electric vehicles (Battery Electric Vehicles) that do not have an engine as a driving source.

<Overall configuration of hybrid vehicle>
1, the hybrid vehicle 100 includes wheels 10, axles 12, a motor 41, an engine 20, a generator 42, a first inverter 51, a second inverter 52, a first converter 71, a second converter 72, a battery unit 110, and an electronic control unit (ECU) 70. The motor 41 constitutes a drive unit of the hybrid vehicle 100. The ECU 70 is an example of a controller.

This hybrid vehicle 100 is a series type, and the motor 41 functions as a drive source that outputs driving force for the vehicle. The engine 20 functions as a drive source that drives the generator 42. The engine 20 is, for example, a gasoline engine.

The motor 41 is coupled to the axle 12 and connected to the battery unit 110 via a first inverter 51. The motor 41 receives power from the battery unit 110, which is converted to AC power by the first inverter 51 and then supplied with the power. The motor 41 receives the power supply and functions as an electric motor to rotate the axle 12. The motor 41 also functions as a generator by performing regenerative operation when the hybrid vehicle 100 decelerates, thereby charging the battery unit 110.

The generator 42 is connected to the first inverter 51 and the battery unit 110 via the second inverter 52. As described above, the generator 42 is driven by the engine 20 to supply power to the motor 41 and charge the battery unit 110. The second inverter 52 converts the power generated by the generator 42 into DC power and outputs it to the first inverter 51 or the first converter 71 and second converter 72 described below.

The battery unit 110 has multiple batteries. The battery unit 110 in the configuration example of FIG. 1 has a first battery 61 and a second battery 62. The first battery 61 and the second battery 62 are secondary batteries that can be charged and discharged. Specifically, the first battery 61 and the second battery 62 are lithium ion batteries. The number of batteries in the battery unit 110 is not limited to two. Also, the batteries in the battery unit 110 may have the same capacity and the same voltage, but are not limited to this.

The first battery 61 is connected to the first inverter 51 and the second inverter 52 via the first converter 71. The second battery 62 is connected to the first inverter 51 and the second inverter 52 via the second converter 72. The first battery 61 and the second battery 62 are connected in parallel to the motor 41 and the generator 42. The first converter 71 and the second converter 72 are also connected in parallel to the motor 41 and the generator 42.

The first converter 71 has a function of stepping up or stepping down the voltage between the first battery 61 and the first inverter 51 or the second inverter 52, and the second converter 72 has a function of stepping up or stepping down the voltage between the second battery 62 and the first inverter 51 or the second inverter 52. As described below, the first converter 71 also has a function of cutting off the connection between the first battery 61 and the first inverter 51 or the second inverter 52, and the second converter 72 also has a function of cutting off the connection between the second battery 62 and the first inverter 51 or the second inverter 52.

The ECU 70 controls the motor 41 and the engine 20 as well as charging and discharging the battery unit 110 so as to achieve the desired driving conditions in response to the driving operations of the driver of the hybrid vehicle 100 (i.e., normal control of the hybrid vehicle 100).

Specifically, when the ECU 70 drives the motor 41 to run the hybrid vehicle 100, it discharges the first battery 61 and the second battery 62 in response to a discharge request corresponding to the running state of the hybrid vehicle 100, and supplies the electric power to the first inverter 51 through the first converter 71 and the second converter 72. At this time, the first converter 71 and the second converter 72 adjust the discharge voltages of the first battery 61 and the second battery 62 so that the voltages supplied to the first inverter 51 match each other.

When the hybrid vehicle 100 is in regeneration mode, the ECU 70 supplies the regenerative power of the motor 41 to the first battery 61 and the second battery 62 through the first converter 71 and the second converter 72 in response to a charging request. The first battery 61 and the second battery 62 are charged by the regenerative power.

When the generator 42 is generating power, the ECU 70 supplies all or part of the power generated by the generator 42 to the motor 41 through the second inverter 52 and the first inverter 51. At this time, the ECU 70 may supply part of the power generated by the generator 42 to the first battery 61 and the second battery 62 through the first converter 71 and the second converter 72. In this case, the first battery 61 and the second battery 62 are charged by the power generated by the generator 42.

<Battery unit control device>
The battery unit 110 mounted on the hybrid vehicle 100 repeats charging and discharging as described above as the hybrid vehicle 100 travels. Depending on the traveling state of the hybrid vehicle 100, charging at a high rate or discharging at a high rate may be performed. Depending on the traveling state of the hybrid vehicle 100, the charging rate and the discharging rate may not be equal or approximately equal. For example, FIG. 2 illustrates the change in the charging current and the discharging current for the battery unit 110 over time. As shown in the upper diagram of FIG. 2, the battery unit 110 may become overcharged with the charging rate higher than the discharging rate by performing charging at a high rate, or may become overdischarged with the discharging rate higher than the charging rate by performing discharging at a high rate, as shown in the lower diagram of FIG. 2.

When the battery is overcharged as shown in the upper diagram of FIG. 2, or overdischarged as shown in the lower diagram of FIG. 2, the concentration distribution of Li ions becomes uneven inside the battery, causing deterioration in which the internal resistance rises. FIG. 3 illustrates the relationship between the charge/discharge rate balance and deterioration. In both cases of overcharging, where the charge rate is higher than the discharge rate, and overdischarging, where the discharge rate is higher than the charge rate, the internal resistance of the battery unit 110 increases, and deterioration of the battery unit 110 progresses.

This deterioration is reversible and can be restored. Specifically, in the case of overcharging, the battery unit 110 is discharged at a high rate, and in the case of overdischarging, the battery unit 110 is charged at a high rate. This improves the bias in the concentration distribution of Li ions and restores the deterioration. For example, FIG. 4 shows that the deterioration can be restored by applying a reverse pulse to a battery unit 110 whose charge/discharge rate balance has been lost. The horizontal axis of FIG. 4 is the number of cycles of the battery unit 110, and the vertical axis is the rate of increase in resistance of the battery unit 110. The number of cycles referred to here is the number counted as one cycle when the vehicle starts to operate and then ends after one or more large current charges and discharges.

The dashed line in the figure illustrates the change in the resistance rise rate when overcharging, in which the charge rate is higher than the discharge rate, continues. In this case, the resistance rise rate gradually increases, and deterioration progresses. In contrast, the solid line in the figure illustrates the change in the resistance rise rate when overcharging, in which the charge rate is higher than the discharge rate, and overdischarging, in which the discharge rate is higher than the charge rate, are alternately switched for each cycle. In this case, the increase in the resistance rise rate is suppressed, and the progression of deterioration is suppressed. In other words, in the case of overcharging, high-rate discharging is performed, and in the case of overdischarging, high-rate charging is performed, thereby allowing the deterioration to be restored. As can be seen from Figure 4, even if overcharging and overdischarging are alternately switched, it is difficult to completely restore the deterioration.

The control device of the vehicle battery unit executes recovery control to recover the deterioration of the battery unit 110 by discharging or charging at a high rate in the event of overcharging or overdischarging. However, the discharge or charge request for the battery unit 110 is determined according to the driving state of the hybrid vehicle 100. Depending on the driving state of the hybrid vehicle 100, there are cases where high-rate discharge or high-rate charging is not required. If high-rate charging or discharging is not required, the control device cannot recover the deterioration of the battery unit 110.

In order to increase the chances of recovering the battery unit 110 from deterioration, the control device of this vehicle battery unit discharges or charges only one of the first battery 61 and the second battery 62 connected in parallel to the drive unit 120 during recovery control. By limiting the number of batteries used to one, the discharge rate or charge rate must be increased to satisfy the required discharge or charge corresponding to the driving state of the hybrid vehicle 100. As a result, high-rate discharge or high-rate charging is performed. The control device of this vehicle battery unit can recover the deterioration of the battery unit 110 by charging and discharging at a high rate while driving the hybrid vehicle 100 in response to the driver's request.

(Control details)
5 and 6 show the flow of electricity during recovery control. FIG. 5 shows a high-rate discharge state. This recovers from deterioration due to overcharging. The upper diagram of FIG. 5 shows a state in which only the first battery 61 is discharged. In this case, the first converter 71 supplies the discharged power of the first battery 61 to the motor 41 through the first inverter 51. Meanwhile, the second converter 72 cuts off the current between the second battery 62 and the first inverter 51. The lower diagram of FIG. 5 shows a state in which only the second battery 62 is discharged. In this case, the second converter 72 supplies the discharged power of the second battery 62 to the motor 41 through the first inverter 51. Meanwhile, the first converter 71 cuts off the current between the first battery 61 and the first inverter 51.

Figure 6 shows the charging state at a high rate. This recovers the deterioration caused by excessive discharging. The upper diagram of Figure 6 shows the state where only the first battery 61 is charged. In this case, the first converter 71 supplies the generated power of the generator 42 to the first battery 61. Meanwhile, the second converter 72 cuts off the current between the second battery 62 and the second inverter 52. Note that a part of the generated power is supplied to the motor 41 through the first inverter 51. The lower diagram of Figure 6 shows the state where only the second battery 62 is charged. In this case, the second converter 72 supplies the generated power of the generator 42 to the second battery 62. Meanwhile, the first converter 71 cuts off the current between the first battery 61 and the second inverter 52. Note that even here, a part of the generated power is supplied to the motor 41 through the first inverter 51.

In the example of FIG. 6, the first battery 61 or the second battery 62 is charged at a high rate using the power generated by the generator 42, but the ECU 70 may also charge the first battery 61 or the second battery 62 at a high rate using the regenerative power of the motor 41 during recovery control.

The ECU 70 executes recovery control while switching between the first battery 61 and the second battery 62. In this way, recovery control can be performed for all batteries in the battery unit 110. As a result, all batteries are restored to their original state.

In addition, in the recovery control, the ECU 70 makes the amount of power for high-rate charging equal to the amount of power discharged during normal control. Similarly, the ECU 70 makes the amount of power for high-rate discharging equal to the amount of charging power during normal control. That is, as illustrated in the upper diagram of FIG. 2, in the case of overcharging, the amount of power for high-rate charging is accumulated in advance (see the shaded portion in the upper diagram of FIG. 2), and during recovery control, as illustrated in the lower diagram of FIG. 2, high-rate discharging is performed so as to be equal to the accumulated amount of power (see the shaded portion in the lower diagram of FIG. 2). In addition, as illustrated in the lower diagram of FIG. 2, in the case of overdischarging, the amount of power for high-rate discharging is accumulated in advance (see the shaded portion in the lower diagram of FIG. 2), and during recovery control, as illustrated in the upper diagram of FIG. 2, high-rate charging is performed so as to be equal to the accumulated amount of power (see the shaded portion in the upper diagram of FIG. 2). In this way, the deterioration of the battery unit 110 can be effectively restored.

In addition, during normal control, when charging and discharging at a large current and charging and discharging at a small current are repeated, the integrated value of the charging power amount and the integrated value of the discharging power amount can be calculated by integrating the power amount each time charging and discharging at a large current is performed.

(Flow of Control)
The control flows are shown in Figures 7 and 8. Figure 7 shows the control flow when there is a request to discharge the battery unit 110, and Figure 8 shows the control flow when there is a request to charge the battery unit 110. Note that the order of steps in Figures 7 and 8 and Figures 9 and 10 described below can be changed as appropriate. Also, some steps can be omitted, and new steps can be added.

In step S1 after the start of the flow in FIG. 7, the ECU 70 determines whether the overcharging flag F1 is 1. The overcharging flag F1 is a flag for determining whether the battery unit 110 is overcharged. As described below, the overcharging flag F1 is changed from 0 to 1 in step S19 of the flow in FIG. 8. If the determination in step S1 is YES, that is, if the battery unit 110 is overcharged, recovery control is required and the process proceeds to step S2, and if the determination in step S1 is NO, that is, if the battery unit 110 is not overcharged, recovery control is not required and the process proceeds to step S7.

In steps S7 to S10, the ECU 70 executes normal control. That is, in step S7, the ECU 70 discharges both the first battery 61 and the second battery 62 to supply power to the motor 41. In the following step S8, the ECU 70 judges whether or not a high-rate discharge request has been made. The ECU 70 judges YES when a discharge exceeding a predetermined high-rate threshold is requested, for example, as illustrated by the dashed line in the lower diagram of FIG. 2. If the judgment in step S8 is NO, the process returns. If the judgment in step S8 is YES, the process proceeds to step S9. In step S9, the ECU 70 changes the excessive discharge flag F2 from 0 to 1, and in the following step S10, the ECU 70 accumulates the high-rate discharge power. That is, it accumulates the power of the shaded portion illustrated in the lower diagram of FIG. 2. The high-rate discharge power amount accumulated in step S10 is used in the recovery control (steps S13 and S15) in the case of excessive discharge in the flow of FIG. 8 described below.

Meanwhile, in steps S2 to S6, the ECU 70 executes recovery control. First, in step S2, the ECU 70 discharges only the first battery 61 (see the upper diagram in FIG. 5). As a result, the first battery 61 discharges at a high rate. In the following step S3, the ECU 70 determines whether the deterioration of the first battery 61 has been resolved. If discharge has been performed corresponding to the integrated value of the high-rate charging power (see the shaded portion illustrated in the upper diagram in FIG. 2), which will be described later, the ECU 70 determines YES in step S3. If the determination in step S3 is NO, the process returns to step S2. If the determination in step S3 is YES, the process proceeds to step S4.

In step S4, the ECU 70 discharges only the second battery 62 (see the lower diagram in Figure 5). This causes the second battery 62 to discharge at a high rate. In the following step S5, the ECU 70 determines whether the deterioration of the second battery 62 has been resolved. As in the case of the first battery 61, if discharging corresponding to the integrated value of the high-rate charging power has been performed, the ECU 70 determines YES in step S5. If the determination in step S5 is NO, the process returns to step S4. If the determination in step S5 is YES, the process proceeds to step S6.

In step S6, the ECU 70 determines that the overcharging deterioration has been recovered from because the recovery control of the first battery 61 and the second battery 6 has been completed, and changes the overcharging flag F1 from 1 to 0.

In step S11 after the start of the flow in FIG. 8, the ECU 70 determines whether the over-discharge flag F2 is 1. The over-discharge flag F2 is a flag for determining whether the battery unit 110 is over-discharged. In step S9 of the flow in FIG. 7 described above, the over-discharge flag F2 changes from 0 to 1. If the determination in step S11 is YES, the battery unit 110 is over-discharged and recovery control is required, and the process proceeds to step S12. If the determination in step S11 is NO, the battery unit 110 is not over-discharged and recovery control is not required, and the process proceeds to step S17.

In steps S17 to S110, the ECU 70 executes normal control. That is, in step S17, the ECU 70 supplies the generated power of the motor 41 or the generator 42 to both the first battery 61 and the second battery 62 to charge the first battery 61 and the second battery 62. In the following step S18, the ECU 70 judges whether or not a high-rate charging request has been made. For example, as illustrated by the dashed line in the upper diagram of FIG. 2, the ECU 70 judges YES when charging exceeding a predetermined high-rate threshold is requested. If the judgment in step S18 is NO, the process returns. If the judgment in step S18 is YES, the process proceeds to step S19. In step S19, the ECU 70 changes the overcharging flag F1 from 0 to 1, and in the following step S110, the ECU 70 accumulates the high-rate charging power. That is, the power of the shaded portion shown in the upper diagram of FIG. 2 is accumulated. The high-rate charging power accumulated in step S110 is used in the recovery control (steps S3 and S5) in the case of overcharging in the flow of FIG. 7 described above.

Meanwhile, in steps S12 to S16, the ECU 70 executes recovery control. First, in step S12, the ECU 70 charges only the first battery 61 (see the upper diagram in FIG. 6). As a result, the first battery 61 is charged at a high rate. In the following step S13, the ECU 70 determines whether the deterioration of the first battery 61 has been resolved. If charging has been performed corresponding to the integrated value of the high-rate discharge power calculated in step S10 of FIG. 7, the ECU 70 determines YES in step S13. If the determination in step S13 is NO, the process returns to step S12. If the determination in step S13 is YES, the process proceeds to step S14.

In step S14, the ECU 70 charges only the second battery 62 (see the lower diagram in Figure 6). As a result, the second battery 62 is charged at a high rate. In the following step S15, the ECU 70 determines whether the deterioration of the second battery 62 has been resolved. If charging corresponding to the integrated value of the high-rate discharge power has been performed, the ECU 70 determines YES in step S15. If the determination in step S15 is NO, the process returns to step S14. If the determination in step S15 is YES, the process proceeds to step S16.

In step S16, the ECU 70 determines that the recovery control of the first battery 61 and the second battery 62 has been completed and that the deterioration caused by excessive discharge has been recovered from, and changes the excessive discharge flag F2 from 1 to 0.

Therefore, with this vehicle battery unit control device, the battery unit 110 can discharge or charge the first battery 61 or the second battery 62 at a high rate while charging and discharging according to the driving state of the hybrid vehicle 100. This increases the opportunities to recover the deterioration of the battery unit 110 that has been over-discharged or over-charged. Even if the battery unit 110 is used for a long period of time, the deterioration of the battery unit 110 is recovered, so the deterioration of the battery unit 110 is suppressed.

In addition, during recovery control, the ECU 70 switches between the first battery 61 and the second battery 62 and charges or discharges at a high rate, so that deterioration of both the first battery 61 and the second battery 62 can be recovered.

In addition, the ECU 70 matches the high-rate discharge power or charge power during normal control with the high-rate charge power or discharge power during recovery control, thereby effectively recovering from deterioration of the first battery 61 and the second battery 62.

The hybrid vehicle 100 is also equipped with a generator 42, and the generated power of the generator 42 is supplied to each of the first battery 61 and the second battery 62, so that the opportunity to charge the battery unit 110 is not limited to the time of regenerative power generation by the motor 41. The ECU 70 can increase the opportunities to restore the battery unit 110 to its original condition due to excessive discharge.

(Modification of Control)
7 and 8 , during recovery control, on the condition that the deterioration of the first battery 61 has been recovered from, the target of the recovery control is switched from the first battery 61 to the second battery 62. Alternatively, the recovery control of the first battery 61 or the second battery 62 may be switched based on the passage of time.

Figures 9 and 10 show the control flow for the modified example. Figure 9 shows the control flow when there is a request to discharge the battery unit 110, and Figure 10 shows the control flow when there is a request to charge the battery unit 110.

In step S21 after the start of the flow in FIG. 9, the ECU 70 determines whether the overcharging flag F1 is 1. If the determination in step S21 is YES, recovery control is deemed necessary, and the process proceeds to step S22. If the determination in step S21 is NO, recovery control is deemed unnecessary, and the process proceeds to step S29.

In steps S29 to S212, the ECU 70 executes normal control. That is, in step S29, the ECU 70 discharges both the first battery 61 and the second battery 62 to supply power to the motor 41. In the following step S210, the ECU 70 determines whether or not a high-rate discharge request has been made. If the determination in step S210 is NO, the process returns. If the determination in step S210 is YES, the process proceeds to step S211. In step S211, the ECU 70 changes the over-discharge flag F2 from 0 to 1. In the following step S212, the ECU 70 accumulates the high-rate discharge power.

Meanwhile, in steps S22 to S28, the ECU 70 executes recovery control. First, in step S22, the ECU 70 discharges only the first battery 61. The first battery 61 discharges at a high rate. In the following step S23, the ECU 70 judges whether the deterioration of the first battery 61 has been resolved. This judgment is the same as step S3 in FIG. 7 described above, and if a discharge corresponding to the integrated value of the high-rate charging power (see the shaded portion illustrated in the upper diagram of FIG. 2) has been performed, the ECU 70 judges YES in step S23. If the judgment in step S23 is NO, the process proceeds to step S24. If the judgment in step S23 is YES, the process proceeds to step S25.

In step S24, the ECU 70 determines whether a predetermined time has elapsed since the start of recovery control for the first battery 61. If the determination in step S24 is NO, the process returns to step S22 and continues recovery control for the first battery 61. If the determination in step S24 is YES, the process proceeds to step S25. Therefore, even if discharge corresponding to the integrated value of the high-rate charging power has not been performed, the target of recovery control will be switched from the first battery 61 to the second battery 62 after time has elapsed.

In step S25, the ECU 70 discharges only the second battery 62. The second battery 62 discharges at a high rate. In the following step S26, the ECU 70 determines whether the deterioration of the second battery 62 has been resolved. If the discharge corresponds to the integrated value of the high-rate charging power, the ECU 70 determines YES in step S26. If the determination in step S26 is NO, the process proceeds to step S27, and if the determination in step S26 is YES, the process proceeds to step S28.

In step S27, the ECU 70 determines whether a predetermined time has elapsed since the start of recovery control for the second battery 62. If the determination in step S27 is NO, the process returns to step S25, and the recovery control for the second battery 62 continues. If the determination in step S27 is YES, the process returns to step S22, and the control target is switched.

Therefore, recovery control is performed while switching the control target between the first battery 61 and the second battery 62 at predetermined time intervals. Then, when the deterioration of each of the first battery 61 and the second battery 62 is resolved, the process proceeds to step S28.

In step S28, the ECU 70 determines that the overcharging deterioration has been recovered from because the recovery control of the first battery 61 and the second battery 6 has been completed, and changes the overcharging flag F1 from 1 to 0.

In step S31 after the start of the flow in FIG. 10, the ECU 70 determines whether the excessive discharge flag F2 is 1. If the determination in step S31 is YES, recovery control is deemed necessary, and the process proceeds to step S32. If the determination in step S31 is NO, recovery control is deemed unnecessary, and the process proceeds to step S39.

In steps S39 to S312, the ECU 70 executes normal control. That is, in step S39, the ECU 70 supplies the generated power of the motor 41 or the generator 42 to both the first battery 61 and the second battery 62, thereby charging the first battery 61 and the second battery 62. In the following step S310, the ECU 70 determines whether or not a high-rate charging request has been made. If the determination in step S310 is NO, the process returns. If the determination in step S310 is YES, the process proceeds to step S311. In step S11, the ECU 70 changes the overcharging flag F1 from 0 to 1, and in the following step S312, the ECU 70 accumulates the high-rate charging power.

Meanwhile, in steps S32 to S38, the ECU 70 executes recovery control. First, in step S32, the ECU 70 charges only the first battery 61. The first battery 61 is charged at a high rate. In the following step S33, the ECU 70 determines whether the deterioration of the first battery 61 has been resolved. If the determination in step S33 is NO, the process proceeds to step S34. If the determination in step S33 is YES, the process proceeds to step S34.

In step S34, the ECU 70 determines whether a predetermined time has elapsed since the start of recovery control for the first battery 61. If the determination in step S34 is NO, the process returns to step S32 and continues recovery control for the first battery 61. If the determination in step S34 is YES, the process proceeds to step S35.

In step S35, the ECU 70 charges only the second battery 62. The second battery 62 is charged at a high rate. In the following step S36, the ECU 70 determines whether the deterioration of the second battery 62 has been resolved. If the determination in step S36 is NO, the process proceeds to step S37. If the determination in step S36 is YES, the process proceeds to step S38.

In step S37, the ECU 70 determines whether a predetermined time has elapsed since the start of recovery control for the second battery 62. If the determination in step S37 is NO, the process returns to step S35, and the recovery control for the second battery 62 continues. If the determination in step S37 is YES, the process returns to step S32, and the control target is switched.

If the deterioration of both the first battery 61 and the second battery 62 has been restored, in step S38, the ECU 70 changes the over-discharge flag F2 from 1 to 0 because the recovery control of the first battery 61 and the second battery 6 has been completed.

The charging and discharging requests for the battery unit 110 are determined according to the driving state of the hybrid vehicle 100. If the target of recovery control is switched after waiting for recovery of the first battery 61 or the second battery 62, even if one battery has recovered from its deterioration, there may be no opportunity to execute recovery control for the other battery. By switching the target of recovery control according to the elapsed time of control, it becomes possible to recover from the deterioration of each of the first battery 61 and the second battery 62.

(System Variations)
11 shows a first modified example of a hybrid vehicle 101. This hybrid vehicle 101 can reduce the number of converters. The hybrid vehicle 101 has one common converter 73 for two batteries, the first battery 61 and the second battery 62. This hybrid vehicle 101 can reduce the number of converters.

The battery unit 111 has a series line 63 that connects the first battery 61 and the second battery 62 in series. The positive electrode of the first battery 61 is connected to the converter 73 via the series line 63. The negative electrode of the first battery 61 is connected to the converter 73 and is connected to the first inverter 51 and the second inverter 52, bypassing the converter 73. The positive electrode of the second battery 62 is connected to the first inverter 51 and the second inverter 52, bypassing the converter 73. The negative electrode of the second battery 63 is connected to the converter 73 via the series line 63.

A first switch 31, a second switch 32, and a third switch 33 are provided between the first battery 61, the second battery 62, and the converter 73. The first switch 31 is provided on a line connected to the negative pole of the first battery 61. The second switch 32 is provided on a series line 63. The third switch 33 is provided on a line connected to the positive pole of the second battery 62. By switching on/off these switches 31 to 33, the battery unit 111 switches between a state in which the first battery 61 and the second battery 62 are connected in series and the first battery 61 and the second battery 62 are charged or discharged (during normal control) and a state in which the series connection of the first battery 61 and the second battery 62 is released and the first battery 61 is charged or discharged, or the second battery 62 is charged or discharged (during recovery control).

The control of the hybrid vehicle 101 according to the first modified example is performed in accordance with the flowcharts shown in Figures 7 to 10.

Figure 12 shows a second variant of the hybrid vehicle 102. This hybrid vehicle 102 has a total of four inverters. The hybrid vehicle 102 does not have a converter, and each inverter also has the function of a converter.

The battery unit 112 has a first battery 61 and a second battery 62. The first battery 61 is connected to a first inverter 51 and a second inverter 52, and the second battery 62 is connected to a third inverter 53 and a fourth inverter 54. The first inverter 51 and the third inverter 53 are connected in parallel to the motor 41, and the second inverter 52 and the fourth inverter 54 are connected in parallel to the generator 42.

The ECU 70 controls the operation of the first inverter 51, the second inverter 52, the third inverter 53, and the fourth inverter 54 to switch between a state in which both the first battery 61 and the second battery 62 are charged or discharged (during normal control) and a state in which the first battery 61 is charged or discharged or a state in which the second battery 62 is charged or discharged (during recovery control).

The control of the hybrid vehicle 102 in the second modified example is performed in accordance with the flowcharts of Figures 7 to 10 described above.

100 Hybrid car (vehicle)
101 Hybrid vehicle (vehicle)
102 Hybrid car (vehicle)
110 Battery unit 111 Battery unit 112 Battery unit 31 First switch 32 Second switch 33 Third switch 41 Motor (drive unit)
42 Generator
61 First battery 62 Second battery 63 Series line 70 ECU (controller)
71 First converter 72 Second converter 73 Converter

Claims (6)

A drive unit that is mounted on a vehicle and generates a driving force for running the vehicle;
a battery unit including a plurality of batteries connected in parallel to the drive unit, each of the batteries being capable of being charged and discharged;
a controller that controls charging and discharging of the battery unit in response to a charging request or a discharging request corresponding to a running state of the vehicle during normal control;
The controller includes:
In the normal control, it is determined that the battery unit is overcharged, that is, a charge rate is higher than a discharge rate, or overdischarged, that is, a discharge rate is higher than a charge rate;
If the battery unit is overcharged, recovery control is performed in response to a request to discharge the battery unit, in which only some of the plurality of batteries are discharged at a high rate;
If the battery unit is over-discharged, recovery control is performed to charge only some of the batteries among the plurality of batteries at a high rate when a charge request is made for the battery unit.
Vehicle battery unit control device. 2. The vehicle battery unit control device according to claim 1,
a generator connected in parallel to the plurality of batteries and supplying generated power to each of the plurality of batteries;
the controller supplies the generated power of the generator to only some of the batteries of the plurality of batteries during recovery control when the battery unit is over-discharged.
Vehicle battery unit control device. 3. The vehicle battery unit control device according to claim 1,
The controller integrates high-rate discharge power or high-rate charge power of the battery unit during the normal control,
The controller also performs charging at a high rate corresponding to the integrated discharge power or discharging at a high rate corresponding to the integrated charge power during the recovery control.
Vehicle battery unit control device. The vehicle battery unit control device according to any one of claims 1 to 3,
The controller switches among the plurality of batteries during recovery control to charge or discharge at a high rate.
Vehicle battery unit control device. The vehicle battery unit control device according to any one of claims 1 to 4,
a plurality of converters corresponding to the plurality of batteries and connected in parallel to the drive unit;
The controller charges or discharges the plurality of batteries using the plurality of converters during the normal control, and charges or discharges the portion of the batteries using the portion of the converters during the recovery control.
Vehicle battery unit control device. The vehicle battery unit control device according to any one of claims 1 to 4,
a converter connected to the drive unit and common to the plurality of batteries;
the battery unit includes a series line that connects the plurality of batteries in series and a switch that connects and disconnects the series line;
The controller charges or discharges the plurality of batteries using the converter while the plurality of batteries are connected in series during the normal control, and charges or discharges the portion of the batteries using the converter while the plurality of batteries are disconnected from the series connection during the recovery control.
Vehicle battery unit control device.