JP6953737B2 - Control device - Google Patents

Description

The present invention relates to a control device applied to a power supply system having a plurality of storage batteries.

Conventionally, for example, as an in-vehicle power supply system mounted on a vehicle, a lead storage battery and a lithium ion storage battery are connected in parallel to a generator (for example, an alternator or an ISG), and the lead storage battery is connected to an electric load. There is a system in which the lithium ion storage battery is connected in parallel (for example, Patent Document 1). In this in-vehicle power supply system, two storage batteries are used properly to supply electric power to various electric loads, and the storage batteries are selected to charge the electric power from the generator. In such a power supply system, switches are provided in the first electric path between the generator and the lead storage battery and in the second electric path between the generator and the lithium ion storage battery, and by opening and closing each switch. Charging and discharging of each storage battery is controlled.

Japanese Unexamined Patent Publication No. 2011-176958

By the way, the switch provided in the second electric path between the generator and the lithium ion storage battery may be turned on (failure that does not turn off). In this case, even when the generator is charging the lead storage battery, the second electric path may be energized and the lithium ion storage battery may be charged. At this time, if the generated voltage is high, the lithium ion storage battery may be overcharged.

In particular, since the lithium ion storage battery is an assembled battery composed of a plurality of cells, the voltage of the cells may vary, and the voltage of the lithium ion storage battery and the voltage of each cell are used. May not be proportional. Therefore, based on the low voltage of some cells, the voltage of the lithium-ion storage battery may be lower than the generated voltage even though some cells are in the state immediately before being overcharged. .. In this case, since each cell is charged, there is a risk that some cell will be overcharged.

The present invention has been made in view of the above circumstances, and a main object of the present invention is to provide a control device capable of suppressing overcharging.

In order to solve the above problems, the first invention comprises a generator, a first storage battery, and a second storage battery which is an assembled battery having a plurality of cell cells (30a to 30e), and the generator is provided with a second storage battery. In a control device applied to a power supply system in which the first storage battery and the second storage battery are connected in parallel, a determination unit that determines the power generation voltage of the generator based on the storage state of the first storage battery, and each of the above. The acquisition unit that acquires the charge state of the cell, and when the second storage battery is charged, each unit at the time when the cell having the highest charge rate or voltage among the cell cells reaches the charge completion state. A determination unit that determines whether or not the total voltage of the batteries is higher than the power generation voltage based on the storage state of each unit acquired by the acquisition unit, and a power generation control unit that controls the power generation of the generator. When the determination unit determines that the total voltage is higher than the power generation voltage, the power generation control unit generates the generator with the power generation voltage, and the determination unit generates the total. When it is not determined that the voltage is higher than the generated voltage, the gist is to control the generator to be generated at a voltage equal to or lower than the total voltage or to regulate the generation of the generator.

When the determination unit determines that the total voltage is higher than the power generation voltage, even if the second storage battery is charged with the power generation voltage determined based on the power storage state of the first storage battery, the storage rate of each unit battery Alternatively, the cell with the highest voltage will not be charged until it is fully charged. On the other hand, if it is not determined that the total voltage is higher than the generated voltage, the generator is generated with a voltage equal to or less than the total voltage, or the power generation is regulated. The cell will not be charged until the voltage becomes higher than the fully charged state. Therefore, for example, even if a switch-on failure occurs and the electric path between the generator and the second storage battery becomes energized and the second storage battery is unintentionally supplied with the generated power, any one of them is used. It is possible to prevent the battery from being overcharged.

Further, when the total voltage is higher than the generated voltage, the power is generated at the generated voltage determined based on the stored state of the first storage battery, so that the charging can be appropriately performed according to the stored state of the first storage battery. ..

The second invention includes an equal control unit that controls the storage state of each of the cells to be uniform, and the voltage of the second storage battery when each of the cells is in the fully charged state is described as described above. If the total voltage is higher than the power generation voltage determined by the determination unit and the determination unit does not determine that the total voltage is higher than the power generation voltage, the equal control unit may perform the above-mentioned each during the power generation of the generator. The gist is to control the storage state of the cell so that it is even.

As a result, the storage state of each cell is equalized, and the total voltage can be made higher than the generated voltage. Therefore, the limitation of the generated voltage can be released, and the first storage battery can be charged efficiently.

The third invention includes a generator, a first storage battery, and a second storage battery which is an assembled battery having a plurality of cell batteries, and the first storage battery and the second storage battery are arranged in parallel with the generator. In the control device applied to the connected power supply system, a determination unit that determines the power generation voltage of the generator based on the storage state of the first storage battery, an acquisition unit that acquires the storage state of each unit battery, and a unit. When the second storage battery is charged, is the total voltage of each of the cells higher than the generated voltage at the time when the cell having the highest storage rate or voltage among the cells is in the fully charged state? A determination unit that determines whether or not the battery is stored based on the storage state of each unit acquired by the acquisition unit, a uniform control unit that controls the storage state of each unit to be equal, and the generated voltage. The power generation control unit that controls the generator to generate power is provided, and the voltage of the second storage battery when each of the unit batteries is in the fully charged state is determined by the determination unit. When the total voltage is higher than the voltage and the determination unit does not determine that the total voltage is higher than the power generation voltage, the equalization control unit determines that the storage state of each unit battery is equal during the power generation of the generator. The gist is to control it so that it becomes.

When the electricity storage state of each cell is equal, each cell is charged while maintaining the uniform state. Then, when each cell is in the fully charged state, the total voltage of each cell (that is, the voltage of the second storage battery) is higher than the generated voltage. As described above, when the electricity storage state of each cell is equal, each cell is not charged until the voltage becomes higher than that in the fully charged state. That is, it is possible to prevent any of the cells from being overcharged.

On the other hand, when it is not determined that the total voltage is higher than the generated voltage, the equal control unit controls so that the electricity storage state of each unit cell becomes equal during the power generation. Therefore, since the power storage state can be equalized, for example, when a switch-on failure occurs, the electric path between the generator and the second storage battery becomes energized, and the second storage battery unintentionally generates power. Is supplied, it is possible to prevent one of the batteries from being overcharged.

Further, since power is generated at a power generation voltage determined based on the storage state of the first storage battery, charging can be appropriately performed according to the storage state of the first storage battery.

A fourth invention includes a switch provided in an electric path between the generator and the second storage battery, and a switch control unit that controls opening and closing of the switch, and the determination unit controls the switch. The gist is to determine whether or not the total voltage of each of the cells is higher than the generated voltage even when the switch is opened by the unit.

As a result, even if a switch-on failure occurs, it is possible to prevent one of the cells from being overcharged. Further, it is possible to prevent one of the cells from being overcharged without detecting a switch-on failure.

In a fifth aspect of the invention, the determination unit determines that the unit having the highest storage rate or voltage among the units is based on the difference in the storage rate or the voltage difference of each unit acquired by the acquisition unit. The gist is to estimate the voltage of each of the cells at the time when the charging is completed, and determine whether or not the total voltage, which is the sum of the estimated voltages of the cells, is higher than the generated voltage. do.

The voltage of each cell is estimated based on the difference in the storage rate or the voltage difference of each cell, and the determination is made based on the total voltage of the estimated voltage. Therefore, it is possible to make an accurate determination as compared with the case where all the voltages are not estimated, overcharging is prevented, and the generated voltage is not excessively limited.

In the sixth invention, the number of the cell cells included in the second storage battery is three or more, and the determination unit has the cell battery having the highest storage rate or voltage among the cell cells and the storage rate or The gist is to determine whether or not the total voltage is higher than the generated voltage based on the difference in storage rate or the voltage difference from the cell having the lowest voltage.

In order to make a judgment based on the difference in storage rate or voltage difference between the cell with the highest storage rate or voltage and the cell with the lowest storage rate or voltage, it is based on the difference in storage rate or voltage difference of each cell. , The amount of calculation can be reduced as compared with the case of estimating the voltage of each cell.

In the seventh invention, the determination unit determines whether or not the total voltage is higher than the power generation voltage based on the difference in storage rate or the voltage difference and the average voltage of each unit cell. The gist is that.

Since the determination is made based on the difference in the storage rate or the voltage difference and the average voltage, an accurate determination can be made.

An electric circuit diagram showing an in-vehicle source system. An electric circuit diagram showing a part of a power supply unit. (A) to (e) are diagrams showing the relationship between SOC and voltage. A flowchart showing a power generation control process. An electric circuit diagram showing another example of an in-vehicle source system.

(First Embodiment)
Hereinafter, embodiments embodying the present invention will be described with reference to the drawings. In the present embodiment, in a vehicle traveling with an engine (internal combustion engine) as a drive source, an in-vehicle power supply system that supplies electric power to various devices of the vehicle is embodied.

As shown in FIG. 1, this power supply system is a dual power supply system having a lead storage battery 11 and a lithium ion storage battery 12, and each of the storage batteries 11 and 12 discharges to an electric load 13 and an electric load 15 ( Power supply) is possible. Further, each of the storage batteries 11 and 12 can be charged by the generator 14. In this system, the lead storage battery 11 and the lithium ion storage battery 12 are connected in parallel to the generator 14, and the lead storage battery 11 and the lithium ion storage battery 12 are connected in parallel to the electric load 15. In the present embodiment, the lead storage battery 11 corresponds to the "first storage battery", and the lithium ion storage battery 12 corresponds to the "second storage battery".

The lead storage battery 11 is a well-known general-purpose storage battery. On the other hand, the lithium ion storage battery 12 is a high-density storage battery having a smaller power loss during charging / discharging, a higher output density, and a higher energy density than the lead storage battery 11. The lithium ion storage battery 12 is preferably a storage battery having higher energy efficiency during charging / discharging than the lead storage battery 11. Further, the lithium ion storage battery 12 is configured as an assembled battery having a plurality of (five in this embodiment) single batteries 30a to 30e, respectively. The rated voltage of each of these storage batteries 11 and 12 is the same, for example, 12V.

Although a specific description by illustration is omitted, the lithium ion storage battery 12 is housed in a storage case and is configured as a battery unit U integrated with a substrate. In this embodiment, the battery unit U constitutes a "power supply device". In FIG. 1, the battery unit U is shown surrounded by a broken line. The battery unit U has external terminals P0 and P1, of which the lead-acid battery 11, the electric load 13, and the generator 14 are connected to the external terminal P0, and the electric load 15 is connected to the external terminal P1. There is.

An alternator can be considered as a specific example of the generator 14. The rotating shaft of the generator 14 is connected to an engine output shaft (not shown) via a belt or the like, and the rotating shaft of the generator 14 is configured to rotate with the rotation of the engine output shaft. The generator 14 generates power (regenerative power generation) by rotating the output shaft and axle of the engine. The generator 14 supplies the generated power to the storage batteries 11 and 12 and the electric load 15.

The electric load 15 includes a constant voltage load in which the voltage of the supplied power is required to be constant or fluctuate within a predetermined range, and a general electric load other than the constant voltage load.

Specific examples of the constant voltage load include various ECUs such as a navigation device, an audio device, a meter device, and an engine ECU. Specific examples of a general electric load include a starter, a seat heater, a heater for a defroster of a rear window, a headlight, a wiper of a front window, a blower fan of an air conditioner, and the like.

The electric load 13 is a general electric load other than the constant voltage required load. Specific examples of the electric load 13 include a starter, a seat heater, a heater for a defroster of a rear window, a headlight, a wiper of a front window, a blower fan of an air conditioner, and the like.

Next, the battery unit U will be described. The battery unit U is provided with an electric path L1 connecting the external terminals P0 and P1 and an electric path L2 connecting the connection point N1 on the electric path L1 and the lithium ion storage battery 12 as an electric path in the unit. .. Of these, the switch 21 is provided in the electric path L1 and the switch 22 is provided in the electric path L2. The generated power of the generator 14 is supplied to the lead storage battery 11 and the lithium ion storage battery 12 via the electric paths L1 and L2.

The switches 21 and 22 each include a set of two semiconductor switches 21a, 21b, 22a and 22b. The semiconductor switches 21a, 21b, 22a, and 22b are MOSFETs, and the parasitic diodes of the two sets of MOSFETs are connected in series so as to be opposite to each other.

For example, the switch 22 will be described in detail. The semiconductor switches 22a and 22b are connected in series. The semiconductor switches 22a and 22b inevitably have a rectifying means due to their internal structure. That is, the internal circuit of the semiconductor switch 22a is a circuit in which the switch unit S1 and the parasitic diode D1 are connected in parallel. Similarly, the semiconductor switch 22b is also a circuit in which the switch unit S2 and the parasitic diode D2 are connected in parallel. The semiconductor switches 22a and 22b are connected in series so that the parasitic diodes D1 and D2 are opposite to each other. Although the switch 22 has been described for convenience, the switch 21 is also configured in the same manner. Further, in FIG. 1, the parasitic diodes D1 and D2 are connected to each other by the anodes, but the cathodes of the parasitic diodes D1 and D2 may be connected to each other.

By configuring the switches 21 and 22 as described above, for example, when the switch 22 is turned off, that is, when the semiconductor switches 22a and 22b are turned off, a current flows through the parasitic diodes D1 and D2. Is completely blocked. That is, it is possible to prevent the lithium ion storage battery 12 from being unintentionally charged.

As the semiconductor switches 21a, 21b, 22a, 22b, it is also possible to use an IGBT, a bipolar transistor, or the like instead of the MOSFET. When an IGBT or a bipolar transistor is used as the switch unit, diodes alternative to the parasitic diodes D1 and D2 may be connected to the switch unit in parallel. Further, in the switches 21 and 22, a plurality of sets of MOSFETs may be provided to connect the plurality of sets of MOSFETs in parallel.

The battery unit U includes a control device 50 as a switch control unit that controls each of the switches 21 and 22. The control device 50 is composed of a microcomputer including a CPU, a ROM, a RAM, an input / output interface, and the like.

The control device 50 controls each of the switches 21 and 22 and the like based on the storage state of each of the storage batteries 11 and 12. For example, the control device 50 acquires the voltage of the lithium ion storage battery 12 from the voltage sensor, and calculates the SOC (state of charge) of the lithium ion storage battery 12 based on the acquired voltage. Then, the control device 50 controls the switches 21 and 22 so that the SOC is maintained within a predetermined range of use, and controls the charging and discharging of the lead storage battery 11 and the lithium ion storage battery 12. That is, the control device 50 selectively uses the lead storage battery 11 and the lithium ion storage battery 12 to charge and discharge. Therefore, the control device 50 functions as a switch control unit.

Since the electric load 15 is a constant voltage required load, either the switch 21 or the switch 22 is always closed, and electric power (dark current, etc.) is continuously supplied to the electric load 15. Become.

Further, the control device 50 determines an abnormality related to the battery unit U. Examples of the abnormality related to the battery unit U include an on failure of the semiconductor switches 21a, 21b, 22a, and 22b constituting the switches 21 and 22. The on failure refers to a state in which the switch unit S1 is stuck on due to the heat of the transient current generated when the connection state is switched. In this case, a situation may occur in which a current flows unintentionally.

Here, the detection of the on-failure of the switch 22 will be described. As shown in FIG. 1, a voltage sensor 60 for detecting (monitoring) the voltage at the intermediate point N10 is provided at the intermediate point N10 of the semiconductor switch 22a and the semiconductor switch 22b.

Here, for example, if either the semiconductor switch 22a or the semiconductor switch 22b is in the ON state, the voltage at the intermediate point N10 becomes equal to or higher than a predetermined value. On the other hand, if both the semiconductor switch 22a and the semiconductor switch 22b are in the off state, the value becomes less than the predetermined value. Therefore, the control device 50 can determine the on failure of the switch 22 based on the voltage detected by the voltage sensor 60. The control device 50 may determine that the on failure occurs when the voltage of the lithium ion storage battery 12 rises when the switch 22 is closed (off).

An ECU 100 including an engine ECU is connected to the control device 50, for example. The ECU 100 is composed of a microcomputer including a CPU, a ROM, a RAM, an input / output interface, and the like, and controls the operation of the engine based on the engine operating state and the vehicle running state each time. The control device 50 and the ECU 100 are connected by a communication network such as CAN so that they can communicate with each other, and various data stored in the control device 50 and the ECU 100 can be shared with each other.

As described above, since the lithium ion storage battery 12 is composed of a plurality of cell cells 30a to 30e, there is a possibility that the storage state (SOC or voltage) of each cell cell 30a to 30e varies. The variation in the storage state can occur, for example, due to the difference in the state of each of the cells 30a to 30e such as the internal resistance in self-discharge.

When the storage state varies, charging is restricted by a high SOC cell battery during charging, while discharging is restricted by a low SOC cell battery during discharging, and the usage area of each cell battery 30a to 30d is restricted. It cannot be fully utilized. Therefore, in order to equalize the SOC and voltage of the plurality of cells 30a to 30e, the control device 50 performs the SOC and voltage equalization processing of each of the cells 30a to 30e.

Specifically, as shown in FIG. 2, detection lines L11 to L16, which are electrical paths, are connected to both end sides (positive electrode side and negative electrode side) of the cells 30a to 30e, respectively. The voltage sensor 40 is connected to each of the detection lines L11 to L16, and from the voltage difference in the detection lines L11 to L16 on both ends (positive electrode side and negative electrode side) of each of the cell 30a to 30e, each cell 30a A voltage of ~ 30e is detected.

Further, the detection lines L11 to L16 on both end sides (positive electrode side and negative electrode side) of the cells 30a to 30e are connected by connection paths L21 to L25, which are electrical paths, respectively. The connection paths L21 to L25 are provided with switches SW1 to SW5 for energizing or shutting off the connection paths L21 to L25, respectively. Further, resistors R1 are provided in the connection paths L21 to L25, respectively, and when the switches SW1 to SW5 are closed, both ends (positive electrode side and negative electrode side) of the cells 30a to 30e are connected via the resistor R1. It will be connected. By controlling the opening and closing of the switches SW1 to SW5, the control device 50 can perform equalized discharge for each of the cells 30a to 30e until the voltages of the cells 30a to 30e become equal.

As a general rule, this equalization process is executed when the in-vehicle power supply system is in the stopped state, that is, when the ignition switch is in the off state. When the ignition switch is in the off state, the switch 22 is in the open state.

By the way, the switch 22 may be turned on (a failure that keeps the switch 22 closed and does not open). When the switch 22 is turned on and fails, the electric path L2 is energized. Then, when the generator 14 generates power and the generated power is supplied to the lead storage battery 11, that is, when the lead storage battery 11 is being charged and the switch 22 is on and failed, the lithium ion storage battery 12 May also be charged.

Specifically, when the switch 22 is open, the switch 21 is closed because it is necessary to supply electric power (dark current or the like) from the lead storage battery 11 or the generator 14 to the electric load 15. Therefore, when the switch 22 is turned on and the electric path L2 is energized, the generated power may be supplied to the lithium ion storage battery 12 via the switches 21 and 22.

The control device 50 can detect the on-failure of the switch 22 as described above, but cannot detect it unless the current of the electric path L2 flows. Therefore, it takes time to detect the on failure, and the lithium ion storage battery 12 may be charged.

Further, when the storage states of the cells 30a to 30e are equal, the generated voltage of the generator 14 is not a voltage that can be charged until the lithium ion storage battery 12 is overcharged. However, if the SOC (and voltage) of each of the cells 30a to 30e varies, some of the cells may be overcharged. The situation that can lead to overcharging will be described in detail.

First, a case where the storage states (SOC and voltage) of the cells 30a to 30e are equal will be described. As shown in FIG. 3A, when the lithium ion storage batteries 12 are charged when the storage states of the cells 30a to 30e are equal, the cells 30a to 30e are also charged evenly. That is, as shown in FIG. 3B, even after charging, the storage states of the cells 30a to 30e are maintained to be uniform.

In this way, when the electricity storage state is uniform, if all the cells 30a to 30e are charged until the charging is completed, the total voltage of each cell 30a to 30e (that is, the lithium ion storage battery 12) is charged. Voltage) is higher than the generated voltage of the generator 14.

An appropriate range (in the present embodiment, the SOC is in the range from the first predetermined value T10 to the second predetermined value T20) is defined for the storage state of the cells 30a to 30e, and the cells are used within this range. By (charging / discharging), it is possible to prevent overcharging and accelerated deterioration. The charging complete state refers to, for example, a power storage state having the highest SOC (or voltage) within an appropriate range (a power storage state in which the SOC is the second predetermined value T20). The charging complete state is not limited to an appropriate range and may be changed arbitrarily, but it is desirable that the charging completed state is the state of electricity storage immediately before overcharging.

For example, if the generated voltage is in the range of 10V to 13V, while the voltage of each cell 30a to 30e in the fully charged state is, for example, 3V, the total voltage of each cell 30a to 30e is It becomes 15V. Therefore, when the storage states of the cells 30a to 30e are uniform, the generated voltage is in the range of 10 to 13V, so that the batteries 30a to 30e are not charged until they are overcharged. ..

On the other hand, as shown in FIG. 3C, when the storage states of the cells 30a to 30e vary (when they are uneven), when the lithium ion storage battery 12 is charged, the cells maintain the variation. 30a to 30e are charged.

Therefore, as shown in FIG. 3D, even if the cell with the highest SOC or voltage (hereinafter, simply referred to as the maximum voltage cell) is in the fully charged state, the other cells 30b to 30e When the voltage is low, the total voltage of each of the cells 30a to 30e may be lower than the generated voltage. In FIGS. 3 (c) to 3 (e), the cell 30a is illustrated as the maximum voltage cell.

For example, even if the voltage of the maximum voltage cell 30a is 3V (charge completed state), if the voltages of the other cells 30b to 30e are 1.6V, 1.8V, 2V, and 2.5V, respectively, the single cell is used. The total voltage of the batteries 30a to 30e is 10.9V. In this case, assuming that the generated voltage is 12 V, as shown in FIG. 3 (e), the batteries will continue to be charged until the total voltage of the cells 30a to 30e reaches the generated voltage. As a result, at least the maximum voltage cell 30a becomes a voltage of 3 V or more, and there is a risk of overcharging.

Overcharging causes various inconveniences such as accelerated deterioration. Therefore, in order to regulate overcharging, the control device 50 is configured and processed as follows. explain in detail.

The control device 50 executes various functions by the determination unit 51 that determines the power generation voltage, the acquisition unit 52 that acquires the electricity storage state, the determination unit 53, the power generation control unit 54, and the equal control unit 55. Various functions are realized by executing the program stored in the storage device included in the control device 50. The various functions may be realized by electronic circuits that are hardware, or at least a part of them may be realized by software, that is, processing executed on a computer.

The determination unit 51 determines the power generation voltage of the generator 14 based on the storage state (SOC and voltage) of the lead storage battery 11. The generated voltage is determined within a predetermined range, for example, within the range of 10V to 13V.

The acquisition unit 52 acquires the voltage of each of the cells 30a to 30e detected by the voltage sensor 40. The SOC of each of the cells 30a to 30e may be calculated and the calculated SOC may be obtained.

When the lithium ion storage battery 12 is charged, the determination unit 53 determines that the total voltage of the cells 30a to 30e at the time when the maximum voltage cell of the cells 30a to 30e is fully charged is the total voltage of the cells 30a to 30e from the generated voltage. It is determined whether or not the voltage is high based on the storage state of each of the cells 30a to 30e acquired by the acquisition unit 52. In the following, the state at the time when the maximum voltage cell among the cells 30a to 30e is in the fully charged state is simply referred to as a specific state.

More specifically, the determination unit 53 first estimates the voltage of each of the cells 30a to 30e in a specific state based on the electricity storage state of each of the cells 30a to 30e acquired by the acquisition unit 52.

The estimation method will be specifically described. It is known that the voltage of each of the cells 30a to 30e and the SOC have a correlation as shown in FIG. That is, the SOC of each of the cells 30a to 30e and the voltage have a proportional relationship, and the proportional coefficient differs depending on the SOC and the voltage range.

For example, the proportional coefficient C1 when the SOC is lower than the first threshold T1 or higher than the second threshold T2 is larger than the proportional coefficient C2 when the SOC is within the range of the first threshold T1 to the second threshold T2. It's getting bigger. The SOC is smaller than the first predetermined value T10 (however, the first predetermined value T10 <first threshold value T1), or smaller than the second predetermined value T20 (however, the second threshold value T2 <second predetermined value T20). If it is large, the cells 30a to 30e are likely to deteriorate. In the present embodiment, when the SOC of the cells 30a to 30e is the second predetermined value T20, or when the voltage of the cells 30a to 30e is a voltage corresponding to the second predetermined value T20, the cells 30a to 30a 30e is in the fully charged state.

The storage device of the control device 50 stores the correlation between the voltage and the SOC in advance, and the determination unit 53 sets the storage state in the specific state based on the storage state of the cells 30a to 30e acquired by the acquisition unit 52. The voltage of each cell 30a to 30e is estimated.

Specifically, the determination unit 53 first calculates the SOC of each of the cells 30a to 30e at the present time based on the voltage of the cells 30a to 30e at the present time acquired by the acquisition unit 52. Then, the determination unit 53 identifies the maximum voltage cell among the calculated cells 30a to 30e.

Next, the determination unit 53 assumes that the SOC of the specified maximum voltage cell has reached the second predetermined value T20, and determines the SOC of each cell 30a to 30e based on the SOC difference of each cell 30a to 30e. presume. More specifically, the difference in SOC between the cells 30a to 30e is maintained even when charged. Therefore, the determination unit 53 calculates the SOC difference between the SOC of the specified maximum voltage cell and the SOC of the other cell, and subtracts the SOC difference calculated from the second predetermined value T20. The SOC of each cell 30a to 30e in a specific state is estimated.

For example, a case where the SOCs of the cells 30a to 30e at the present time are 50%, 45%, 40%, 35%, and 30%, respectively, will be described. Assuming that the SOC of the maximum voltage cell 30a is charged to 80%, which is the second predetermined value T20, the SOCs of the cells 30b to 30e are 75%, 70%, and 65%, respectively, based on the SOC difference. , Estimated to be 60%.

Then, the determination unit 53 specifies (estimates) the voltage of each of the cells 30a to 30e corresponding to the estimated SOC of each of the cells 30a to 30e based on the correlation between the voltage and the SOC.

Even if the batteries are charged, the voltage difference between the cells 30a to 30e is almost maintained. Therefore, the voltage difference of each of the cells 30a to 30e acquired by the acquisition unit 52 may be obtained, and the voltage of each of the cells 30a to 30e in a specific state may be estimated based on the voltage difference.

More specifically, the determination unit 53 identifies the maximum voltage cell among the cells 30a to 30e acquired by the acquisition unit 52. Then, the determination unit 53 calculates the voltage difference from the maximum voltage with the other cell. Then, the determination unit 53 estimates the voltage of each of the cells 30a to 30e in the specific state by subtracting each voltage difference calculated from the voltage V20 corresponding to the second predetermined value T20.

For example, a case where the voltages of the cells 30a to 30e at the present time are 1V, 1.2V, 1.5V, 1.8V, and 2V, respectively, will be described. Assuming that the maximum voltage cell 30e is charged until it reaches 3V corresponding to the second predetermined value T20, the voltages of the cell 30a to 30d are 2V and 2.2V, respectively, based on each voltage difference. , 2.5V, 2.8V.

Then, the determination unit 53 determines whether or not the total voltage obtained by summing the estimated voltages of the cells 30a to 30e in the specific state is higher than the generated voltage determined by the determination unit 51.

When it is determined that the total voltage is higher than the power generation voltage, the power generation control unit 54 controls the generator 14 to generate power at the power generation voltage. That is, the power generation control unit 54 notifies the ECU 100 of the determined power generation voltage. As a result, the ECU 100 controls the generator 14 so as to generate power at the generated voltage determined by the determination unit 51.

On the other hand, when it is not determined that the total voltage is higher than the power generation voltage, the power generation control unit 54 controls to generate power at a voltage equal to or lower than the estimated total voltage. That is, the control device 50 notifies the ECU 100 of a voltage equal to or less than the total voltage as a generated voltage. As a result, the ECU 100 controls the generator 14 so as to generate electricity at a voltage equal to or lower than the total voltage. If it is not determined that the total voltage is higher than the generated voltage, the power generation may be regulated.

When it is not determined that the total voltage is higher than the generated voltage, the equal control unit 55 controls so that the stored states of the cells 30a to 30e become equal during the power generation. That is, the equal control unit 55 controls the opening and closing of the switches SW1 to SW5 during power generation to perform equalization discharge for each of the cells 30a to 30e until the voltages of the cells 30a to 30e become equal. Let it be carried out.

Next, the power generation control process will be described with reference to FIG. The power generation control process is executed by the control device 50 at predetermined intervals while the IG is on.

First, the control device 50 determines whether or not the power generation condition for performing the regenerative power generation by the generator 14 is satisfied (step S101). The power generation condition is satisfied, for example, when the vehicle speed is decelerated. Whether or not the power generation condition is satisfied is determined based on, for example, a notification from the ECU 100. That is, when the ECU 100 notifies that the power generation condition is satisfied, the control device 50 determines that the power generation condition is satisfied. If the power generation condition is not satisfied (step S101: NO), the control device 50 ends the power generation control process.

When the power generation condition is satisfied (step S101: YES), the control device 50 determines the power generation voltage of the generator 14 based on the power storage state of the lead storage battery 11 (step S102).

Next, the control device 50 acquires the voltage of each of the cells 30a to 30e detected by the voltage sensor 40 (step S103). Then, the control device 50 estimates the total voltage of each of the cells 30a to 30e in the specific state based on the acquired voltage of each of the cells 30a to 30e (step S104).

Next, the control device 50 determines whether or not the total voltage of the cells 30a to 30e in the specific state is higher than the generated voltage (step S105). Specifically, the control device 50 determines whether or not the total voltage estimated in step S104 is higher than the generated voltage determined in step S102.

When it is determined that the total voltage is higher than the power generation voltage (step S105: YES), the control device 50 controls the generator 14 to generate power at the power generation voltage determined in step S103 (step S106). ..

On the other hand, when it is not determined that the total voltage is higher than the generated voltage (step S105: NO), the control device 50 causes the generator 14 to generate power at a voltage equal to or lower than the total voltage estimated in step S104. Control (step S107). That is, the generated voltage determined in step S103 is limited.

Further, the control device 50 controls the opening and closing of the switches SW1 to SW5 during power generation to carry out equalized discharge for each of the cells 30a to 30e until the voltages of the cells 30a to 30e become equal. (Step S108). Then, the control device 50 ends the power generation control process.

According to the present embodiment described in detail above, the following excellent effects can be obtained.

When it is determined that the total voltage of the cells 30a to 30e in the specific state is higher than the power generation voltage, the control device 50 generates power at the power generation voltage determined based on the power storage state of the lead storage battery 11. In this case, even if the lithium ion storage battery 12 is charged with the generated voltage, the lithium ion storage battery 12 is not charged until the maximum voltage cell among the cells 30a to 30e is in the fully charged state. On the other hand, if it is not determined that the total voltage is higher than the generated voltage, the control device 50 causes the generator 14 to generate power with a voltage equal to or lower than the total voltage, or regulates the power generation. Therefore, the maximum voltage cell among the cells 30a to 30e is not charged until the voltage becomes higher than that in the fully charged state. Therefore, for example, even if the switch 22 is turned on and the electric path L2 between the generator 14 and the lithium ion storage battery 12 is energized and the lithium ion storage battery 12 is unintentionally supplied with the generated power. , It is possible to prevent any of the cells 30a to 30e from being overcharged.

Further, when the total voltage is higher than the power generation voltage, the power is generated at the power generation voltage determined based on the power storage state of the lead storage battery 11, so that charging can be appropriately performed according to the power storage state of the lead storage battery 11. ..

When the storage states of the cells 30a to 30e are equal, the cells 30a to 30e are charged while maintaining the uniform state. When the lithium ion storage batteries 12 are charged until the charging of the cells 30a to 30e is completed, the total voltage of the cells 30a to 30e becomes higher than the generated voltage. As described above, when the storage states of the cells 30a to 30e are equal, the cells 30a to 30e are not charged until the voltage becomes higher than the state in which the charging is completed. That is, it is possible to prevent any of the cells 30a to 30e from being overcharged.

On the other hand, when it is not determined that the total voltage is higher than the generated voltage, the control device 50 controls so that the electricity storage state of each cell is equal. Since the power storage state can be equalized, for example, when the switch 22 is turned on, the electric path L2 between the generator 14 and the lithium ion storage battery 12 becomes energized, and the lithium ion storage battery 12 is unintentionally energized. Even if the generated power is supplied, it is possible to prevent any of the cells 30a to 30e from being overcharged.

Even when the switch 22 is open, the control device 50 determines whether or not the total voltage is higher than the generated voltage. Therefore, even if the switch 22 is turned on, it is possible to prevent one of the cells from being overcharged. Further, even if the on failure of the switch 22 is not detected, it is possible to prevent one of the cells from being overcharged.

The control device 50 estimates the voltage of each cell 30a to 30e in a specific state based on the SOC difference or voltage difference of each cell 30a to 30e, and the generated voltage is based on the total voltage obtained by summing the estimated voltages. Is high or not. Therefore, it is possible to make an accurate determination as compared with the case where all the voltages are not estimated, and the generated voltage is not excessively regulated.

The resistance value of the resistor R1 is larger than the internal resistance of the cells 30a to 30e. Therefore, the time required for the equalized discharge of each of the cells 30a to 30e may be longer than the time required for charging the cells 30a to 30e. Therefore, when it is not determined that the total voltage is higher than the generated voltage, the control device 50 can surely prevent overcharging by limiting the generated voltage.

The generated voltage will be limited until the storage states of the cells 30a to 30e are equalized. Therefore, even during power generation, the limitation on the power generation voltage can be released by controlling the storage states of the cells 30a to 30e to be even.

(Second Embodiment)
The second embodiment will be described in detail below. In the second embodiment, the determination method by the determination unit 53 is different. In the following, the same or equal parts as those in the first embodiment are designated by the same reference numerals, and the description thereof will be incorporated for the parts having the same reference numerals.

The determination unit 53 of the second embodiment has an SOC difference (or voltage) between the highest voltage cell among the cells 30a to 30e and the cell having the lowest SOC or voltage (hereinafter, simply referred to as the lowest voltage cell). Based on the difference), it is determined whether or not the total voltage of each of the cells 30a to 30e in the specific state is higher than the generated voltage.

More specifically, the determination unit 53 first determines the maximum voltage unit and the minimum voltage unit among the units 30a to 30e based on the storage state of the units 30a to 30e acquired by the acquisition unit 52. And identify. Next, the determination unit 53 calculates the SOC difference (or voltage difference) between the maximum voltage cell and the minimum voltage cell.

Then, the determination unit 53 estimates the voltages of the cells 30a to 30e in a specific state, assuming that the SOC (and voltage) of the cells other than the maximum voltage cell is the same as that of the minimum voltage cell.

The case of estimating based on the SOC difference will be specifically described. For example, a case where the SOCs of the cells 30a to 30e at the present time are 50%, 45%, 40%, 35%, and 30%, respectively, will be described. In this case, assuming that the SOC of the maximum voltage cell 30a is charged to 80%, which is the second predetermined value T20, the SOC of each cell 30b to 30e is based on the SOC difference from the minimum voltage cell 30e. , Estimated to be 60%. Then, the determination unit 53 specifies (estimates) the voltage of each of the cells 30a to 30e corresponding to the estimated SOC of each of the cells 30a to 30e based on the correlation between the voltage and the SOC.

Further, a case of estimating based on the voltage difference will be specifically described. For example, a case where the voltages of the cells 30a to 30e at the present time are 1V, 1.2V, 1.5V, 1.8V, and 2V, respectively, will be described. In this case, assuming that the maximum voltage cell 30e is charged to 3V corresponding to the second predetermined value T20, the voltages of the cell 30a to 30d are set based on the voltage difference from the minimum voltage cell 30a. Estimated to be 2V.

Then, the determination unit 53 determines whether or not the total voltage obtained by summing the estimated voltages of the cells 30a to 30e in the specific state is higher than the generated voltage determined by the determination unit 51. As a result, the total voltage of each of the cells 30a to 30e in the specific state can be easily estimated to be low, but the amount of calculation can be reduced as compared with the case of estimating the voltage of each of the cells 30a to 30e. ..

According to the present embodiment described in detail above, the following excellent effects can be obtained.

In the control device 50, the total voltage of each of the cells 30a to 30e in a specific state is calculated from the generated voltage based on the SOC difference or the voltage difference between the maximum voltage cell and the minimum voltage cell of the cells 30a to 30e. Is also high or not. If the control device 50 is not determined to be higher than the generated voltage, the controller 50 uses a voltage equal to or less than the total voltage estimated based on the SOC difference or the voltage difference between the maximum voltage cell and the minimum voltage cell. To generate electricity. Therefore, the amount of calculation is smaller than when the voltages of the cells 30a to 30e in a specific state are estimated.

(Other embodiments)
The present invention is not limited to the above embodiment, and may be implemented as follows, for example. In the following, the parts that are the same or equal to each other in each embodiment are designated by the same reference numerals, and the description thereof will be incorporated for the parts having the same reference numerals.

In the second embodiment, the total voltage of each of the cells 30a to 30e in a specific state is estimated based on the SOC difference or the voltage difference between the maximum voltage cell and the minimum voltage cell, and based on the estimated total voltage. Judged. As another example, when the SOC difference or voltage difference between the maximum voltage cell and the minimum voltage cell is equal to or less than a predetermined value (when the difference is small), the control device 50 is the total of the cells 30a to 30e in a specific state. It may be determined that the voltage is higher than the generated voltage. The predetermined value may be set according to the SOC difference or the voltage difference between the maximum voltage unit battery and the minimum voltage unit battery when the total voltage lower than the decidable power generation voltage is calculated.

In the second embodiment, the determination unit 53 sets the determination unit 53 in a specific state based on the SOC difference (or voltage difference) between the maximum voltage cell and the minimum voltage cell and the average voltage of each cell 30a to 30e. The total voltage of each cell 30a to 30e may be estimated. For example, the determination unit 53 adds a value corresponding to the average voltage to the total voltage calculated assuming that the SOC (or voltage) of the cell other than the maximum voltage cell is the same as that of the minimum voltage cell. It may be corrected. As a result, it is possible to prevent the total voltage from being estimated to be lower than the actual voltage.

-In the above embodiment, equalization discharge is performed in order to equalize the storage state of each of the cells 30a to 30e, but charging (equalization charging) may be performed in order to equalize. That is, the low-voltage cells 30a to 30e may be charged to equalize the storage state of the high-voltage cells.

-In the power generation control process of the above embodiment, if it is not determined that the total voltage in the specific state is higher than the power generation voltage, and if the power generation voltage is equal to or less than the total voltage, the cell 30a to It is not necessary to equalize the electricity storage state of 30e. That is, if the process of step S107 is executed, it is not necessary to execute the process of step S108.

-In the power generation control process of the above embodiment, when it is not determined that the total voltage in the specific state is higher than the power generation voltage, the power generation voltage is equal to or less than the total voltage if the storage states of the cells 30a to 30e are equalized. It does not have to be the voltage of. That is, if the process of step S108 is executed, it is not necessary to execute the process of step S107.

-In the above embodiment, the control device 50 is applied to the power supply system in which the lead storage battery 11 and the generator 14 are connected to the external terminal P0 and the electric load 15 is connected to the external terminal P1, but it is applied to other power supply systems. You may.

For example, it is applied to a power supply system in which the storage batteries 11 and 12 are connected in parallel to the ISG (Integrated Starter Generator) as a generator and the storage batteries 11 and 12 are connected in parallel to the electric load 15. You may.

Explaining this power supply system in detail, as shown in FIG. 5, a switch 21 is provided in the electric path L1 between the lead storage battery 11 and the ISG70, and a switch 22 is provided in the electric path L2 between the lithium ion storage battery 12 and the ISG70. Be done. Further, a switch 23 is provided in the electric path L3 between the lead-acid battery 11 and the electric load 15, and a switch 24 is provided in the electric path L4 between the lithium ion storage battery 12 and the electric load 15.

The ECU 100 may be provided with a part or all of various functions by the determination unit 51, the acquisition unit 52, the determination unit 53, the power generation control unit 54, and the equalization control unit 55.

11 ... Lead-acid battery, 12 ... Lithium-ion storage battery, 14 ... Generator, 30a-30e ... Cellular battery, 50 ... Control device, 51 ... Decision unit, 52 ... Acquisition unit, 53 ... Judgment unit, 54 ... Power generation control unit, 55 … Equal control unit.

Claims (6)

Electric load from the generator (14), the first storage battery (11), the second storage battery (12) which is an assembled battery having a plurality of single batteries (30a to 30e), and the generator and the first storage battery. The generator is provided with a first switch (21) provided on the electric path leading to the electric path and a second switch (22) provided between the electric path and the second storage battery. On the other hand, in the control device (50) applied to the power supply system in which the first storage battery and the second storage battery are connected in parallel,
The control device is
The opening and closing of the first switch and the second switch are opened and closed so that the first storage battery and the second storage battery are selectively used to charge and discharge based on the storage state of the first storage battery and the second storage battery. It has a function as a switch control unit to control,
A determination unit (51) that determines the generated voltage of the generator, and
The acquisition unit (52) that acquires the charge state of each of the cells,
A determination unit (53) for determining whether or not the total voltage of each of the cells is higher than the generated voltage.
A power generation control unit (54) that controls the power generation of the generator is provided.
The determination unit
When the power generation voltage is determined by the determination unit based on the electricity storage state of the first storage battery, the electricity storage rate or the electricity storage rate of each of the cells is based on the electricity storage state of each cell acquired by the acquisition unit. The total voltage of each of the cells when the second storage battery is charged until the cell having the highest voltage is fully charged is estimated.
It is configured to determine whether or not the estimated total voltage of each of the cells is higher than the generated voltage determined based on the storage state of the first storage battery.
The power generation control unit
When the determination unit determines that the total voltage is higher than the generated voltage, the generator is generated with the generated voltage determined based on the storage state of the first storage battery to generate the first. Charge the storage battery,
When the determination unit does not determine that the total voltage is higher than the generated voltage, the generator is generated with a voltage equal to or lower than the total voltage to charge the first storage battery, or the generator of the generator. A control device that controls power generation. A uniform control unit (55) for controlling the storage state of each of the cells so as to be uniform is provided.
When the determination unit does not determine that the total voltage is higher than the power generation voltage, the equal control unit controls the storage state of each unit cell to be equal during the power generation of the generator. ,
After that, the determination unit estimates the total voltage again, determines whether or not the total voltage is higher than the generated voltage, and determines whether or not the total voltage is higher than the generated voltage.
When the determination unit determines that the total voltage is higher than the power generation voltage, the power generation control unit uses the power generation voltage determined based on the storage state of the first storage battery to generate the generator. The control device according to claim 1, wherein power is generated to charge the first storage battery. When charging the first storage battery, the determination unit determines whether or not the total voltage of each unit battery is higher than the generated voltage even when the second switch is opened by the switch control unit. The control device according to claim 1 or 2. Based on the difference in the storage rate or the voltage difference of each of the cells acquired by the acquisition unit, the determination unit sets the unit having the highest storage rate or voltage among the cells in the fully charged state. The control device according to any one of claims 1 to 3, wherein the total voltage is estimated by estimating the voltage of each of the cells at a time point and summing the estimated voltages of the cells. The number of the cell cells included in the second storage battery is three or more, and the number of the cell cells is three or more.
The determination unit determines the voltage of each of the cells based on the difference in the storage rate or the voltage difference between the cell having the highest storage rate or voltage and the cell having the lowest storage rate or voltage. The control device according to any one of claims 1 to 3, wherein the total voltage is estimated by estimating and summing the estimated voltages of the respective cells. The determination unit estimates the voltage of each cell based on the difference in storage rate or the voltage difference and the average voltage of each cell, and totals the estimated voltage of each cell. The control device according to claim 5, wherein the total voltage is estimated accordingly.

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