JP6974060B2 - In-vehicle electrical system - Google Patents

Description

The present invention comprises a battery having a plurality of battery cells, a first electric device driven based on the output voltage of the battery, a second electric device driven at a lower voltage than the first electric device, and an output voltage of the battery. The present invention relates to the technical field of an in-vehicle electric system provided with a step-down unit that steps down the voltage and supplies the second electric device.

For example, in a hybrid vehicle equipped with a motor as well as an engine as a wheel drive source, in addition to a high-voltage electrical system for driving high-voltage electrical equipment such as a motor, various ECUs (Electronic Control Units) and accessories are used. Some have a low voltage electrical system to drive. A lead-acid battery is generally used as a power source for a low-voltage electric system.

However, since lead-acid batteries are heavy and large, it is conceivable that they will not be installed from the viewpoint of weight reduction and space saving of the vehicle.
As one of the methods of not installing a lead storage battery, it is conceivable to supply the electric power of the low voltage electric system from the high voltage electric system. For example, Patent Document 1 below discloses a configuration in which the output voltage of a high-voltage battery (111) is stepped down by a DC-DC converter (112) and supplied to a low-voltage load (103).

Japanese Unexamined Patent Publication No. 2012-55099

However, according to the above method, if the step-down portion of the DC-DC converter or the like fails, there is a risk that it will be impossible to drive a low-voltage device that operates at a low voltage.

Therefore, the present invention overcomes the above-mentioned problems and makes it possible to appropriately drive the low-voltage device even when the step-down section fails in the in-vehicle electric system in which the step-down section steps down the output voltage of the high-voltage battery and supplies it to the low-voltage device. The purpose is.

The vehicle-mounted electric system according to the present invention includes a battery having a plurality of battery cells, a first electric device driven based on the output voltage of the battery, and a second electric device driven at a lower voltage than the first electric device. The device, a step-down section that lowers the output voltage of the battery and supplies it to the second electric device, and a part of the battery cells in the battery that are connected in parallel to the step-down section with respect to the second electric device. A supply unit capable of supplying power to the second electric device by using a partial cell as a power source is provided, and the supply unit inhibits the inflow of current from the step-down unit to the partial cell side. The step-down section has one obstruction section, and the step-down section supplies a step-down voltage due to a voltage higher than the rated output voltage of the partial cell to the second electric device.

With the above supply unit, even when the output of the step-down unit cannot be obtained, it is possible to supply power to the second electric device by using a part of the cell as a power source.
Further, since the step-down voltage by the step-down part is set to be higher than the rated output voltage of some cells, power is supplied from some cells to the second electric device side in a state where the output of the step-down part is obtained. Further, by having the above-mentioned first inhibitory portion, it is possible to prevent only a part of the cells from being charged by the output of the step-down portion.

The in-vehicle electric system according to the present invention described above may be configured to include a second blocking section that inhibits the inflow of current from the supply section to the step-down section side.

As a result, even if the step-down section fails due to a ground fault, the inflow of current from the supply section to the step-down section side is hindered.

In the in-vehicle electric system according to the present invention described above, the battery is a cell portion in which the plurality of battery cells are connected in series and is composed of some other battery cells excluding the partial cell. The negative electrode side end has a positive electrode side cell portion connected to the positive electrode side end of the partial cell, the positive electrode side end of the positive electrode side cell portion, and a parallel connection circuit of the first electric device and the step-down portion. The negative electrode side inserted between the positive electrode side switch portion inserted in series between the two, the negative electrode side end of the positive electrode side cell portion, and the connection point between the positive electrode side end of the partial cell and the supply portion. It is possible to have a configuration including a switch unit.

The positive electrode side switch portion and the negative electrode side switch portion allow the connection between the positive electrode side cell portion and the electric load to be cut off freely. Then, by inserting the negative electrode side switch portion by the above connection form, even when the positive electrode side cell portion is cut off, that is, the power supply of the step-down portion is cut off, the second electric device is connected to the second electric device via the supply section. It is possible to supply power.

The in-vehicle electric system according to the present invention described above can be configured to include a bypass switch unit connected in parallel to the first obstruction unit.

This makes it possible to charge a part of the cell using the output of the step-down portion.

In the in-vehicle electric system according to the present invention described above, the remaining amount correlation information that correlates with the remaining battery level of the partial cell is acquired, and the on / off control of the bypass switch unit is performed based on at least the remaining amount correlation information. It is possible to have a configuration including a control unit for performing the operation.

This makes it possible to charge some cells according to the fact that the remaining battery level of some cells has actually decreased.

According to the present invention, in an in-vehicle electric system in which a step-down section steps down the output voltage of a high-voltage battery and supplies it to a low-voltage device, the low-voltage device can be appropriately driven even when the step-down section fails.
Further, it is possible to prevent power from not being supplied from some cells to the second electric device side in a state where the output of the step-down section is obtained, and to prevent only some cells from being charged by the output of the step-down section. From this point, it is possible to suppress the imbalance between cells related to the remaining battery level in the battery.

It is a circuit block diagram which showed the structural example of the in-vehicle electric system as the 1st Embodiment which concerns on this invention. It is a circuit block diagram which showed the structural example of the in-vehicle electric system as a 2nd Embodiment. It is a circuit block diagram which showed the structural example of the in-vehicle electric system as a 3rd Embodiment. It is a flowchart which showed the procedure of the process which should be executed in order to realize the charge control method as a third embodiment.

<1. First Embodiment>
FIG. 1 is a circuit block diagram showing a configuration example of an in-vehicle electric system 1 as a first embodiment according to the present invention.
The vehicle-mounted electric system 1 of the present embodiment is provided in a vehicle as an electric vehicle equipped with a motor as a drive source for wheels. Specifically, the vehicle of this example is a hybrid vehicle equipped with an engine together with a motor as a drive source for wheels.

As shown in the figure, the in-vehicle electric system 1 is lower than the battery 2 as an assembled battery having a plurality of battery cells 2a, the first electric device 3 driven based on the output voltage of the battery 2, and the first electric device 3. The connection (electrical) between the second electric device 4 driven by a voltage, the step-down section 5 that lowers the output voltage of the battery 2 and supplies it to the second electric device 4, and the electric load of the battery 2 and the battery 2. It is provided with a positive electrode side relay 7 and a negative negative side relay 8 by an electromagnetic relay for making the connection) freely cut off, and a battery control unit 10 for controlling the battery 2.

In the battery 2, four battery cells 2a made of, for example, a nickel-metal hydride battery or a lithium-ion battery are connected in series as a plurality of battery cells 2a, and some of the battery cells 2a connected in series in this way. The battery cell 2a is a part of the cell 21.
In this example, the partial cell 21 is composed of a partial battery cell 2a provided on the negative electrode end side of the battery 2, and the negative electrode side end is connected to the negative electrode side relay 8.
The partial cell 21 in this example is composed of one battery cell 2a, but the partial cell 21 may be composed of two or more battery cells 2a.
The rated output voltage of some cells 21 is, for example, about 12V.

Further, in the battery 2, the cell portion composed of some other battery cells 2a except for a part cell 21 is referred to as a positive electrode side cell portion 22. In the positive electrode side cell portion 22, the negative electrode side end is partially connected to the positive electrode side end of the cell 21, and the positive electrode side end is connected to the positive electrode side relay 7.
In this example, the total number of battery cells 2a of the battery 2 is 4 and the number of battery cells 2a of the positive electrode side cell portion 22 is 3. However, the total number of battery cells 2a of the battery 2 and the positive electrode side cell portion are set. The number of battery cells 2a included in 22 is not limited thereto.

An IC (Integrated Circuit) (not shown) is mounted on the battery 2, and the SOC (State Of Charge) of each battery cell 2a can be detected by the IC. The IC is communicably connected to the battery control unit 10, and the detected SOC information can be transmitted to the battery control unit 10.

The first electric device 3 is an electric device driven by a relatively high output voltage of the battery 2, and in this example, for example, the above-mentioned motor (traveling motor) is applicable.
Here, the number of the first electric devices 3 is one, but of course, a plurality of first electric devices 3 may be driven by the output voltage of the battery 2.

In this example, the motor is a motor generator that also functions as a generator, and although not shown, in the in-vehicle electric system 1, when the motor functions as a generator, it can be obtained by power generation. A charging circuit (not shown) can charge the battery 2 (both of a part of the cell 21 and the positive cell portion 22) by using the generated electric power.

The step-down unit 5 is composed of, for example, a DC-DC converter as a switching converter, and is connected to the battery 2 in parallel with the first electric device 3 to step down the output voltage of the battery 2.
In the present embodiment, the step-down unit 5 generates a step-down voltage higher than the rated output voltage of some cells 21 as a step-down voltage generated based on the output voltage of the battery 2, and supplies the voltage to the second electric device 4. Specifically, the step-down voltage in this example is about 13V to 15V.

In each of the first electric device 3 and the step-down portion 5, the input terminal on the positive electrode side is connected to the positive electrode side end of the battery 2 (the positive electrode side end of the positive electrode side cell portion 22) via the positive electrode side relay 7, and the input on the negative electrode side is input. The terminal is connected to the negative electrode side end of the battery 2 (the negative electrode side end of some cells 21) via the negative electrode side relay 8.

The second electric device 4 is an electric device driven at a lower voltage than the first electric device 3, such as computer devices such as various ECUs (Electronic Control Units) provided in the vehicle and auxiliary equipment. Here, for the sake of explanation, only one second electric device 4 is used, but in reality, a large number of parallel connection circuits of the second electric devices 4 are connected in series to the step-down section 5.

The battery control unit 10 includes, for example, a microcomputer equipped with a CPU (Central Processing Unit), a ROM (Read Only Memory), a RAM (Random Access Memory), and the like, and in this example, the positive electrode side relay 7 and the negative electrode side. It controls on / off of the relay 8 and controls related to charging of the battery 2.
Specifically, regarding the on / off control of the positive electrode side relay 7 and the negative electrode side relay 8, the battery control unit 10 has started the vehicle, such as on / off information of an ignition switch and a start switch (not shown) provided in the vehicle. / Acquires information indicating the non-start status. Then, when the vehicle is in the activated state, the positive side relay 7 and the negative side relay 8 are turned on to enable power supply from the battery 2 to the electric load of the battery 2 (in this example, the first electric device 3 and the step-down portion 5). In the non-started state, the positive side relay 7 and the negative side relay 8 are turned off to cut off the connection between the battery 2 and the electric load of the battery 2. The safety is improved by the shutoff function of the high voltage portion as the battery 2.

Further, the battery control unit 10 controls the charging circuit described above based on the SOC information of the battery cell 2a acquired from the battery 2 to execute charging of the battery 2.

Here, in the in-vehicle electric system 1 of the present embodiment, it is possible to supply electric power to the second electric device 4 as a low voltage load by using a part of the cells 21 in the battery 2 as a power source. As a configuration for that purpose, the vehicle-mounted electric system 1 is provided with a supply unit 6.
The supply unit 6 has at least a diode D1, is inserted in series between the second electric device 4 and a part of the cell 21, and is connected to the second electric device 4 in parallel with the step-down unit 5. It is said that the electric power partially charged in the cell 21 can be supplied to the second electric device 4 via the diode D1.
As shown in the figure, the diode D1 is inserted in a direction in which the anode is partially connected to the positive electrode side end of the cell 21. Such a diode D1 functions as an obstruction unit (first obstruction unit) that inhibits the inflow of current from the step-down portion 5 to a part of the cell 21 side.

As described above, since the step-down voltage by the step-down section 5 is higher than the rated output voltage of some cells 21, the step-down section 5 is in a non-failure state, that is, the output of the step-down section 5 is obtained. In the state, the step-down voltage is supplied to the second electric device 4 by the step-down unit 5, and the power is not supplied to the second electric device 4 via the supply unit 6.

At this time, if the diode D1 is not provided, the output voltage (voltage across) of some cells 21 is lower than the step-down voltage of the step-down section 5, so that some cells are passed from the step-down section 5 to the supply section 6. There is a risk that current will flow into the 21 side. That is, of the battery cells 2a in the battery 2, only the battery cells 2a constituting a part of the cells 21 may be charged unevenly.
By hindering the inflow of current from the step-down portion 5 to the part of the cell 21 side by the diode D1, it is possible to prevent the battery cell 2a of the part of the cell 21 from being unbalancedly charged. In the battery 2, it is possible to suppress the imbalance between cells related to the remaining battery level.

Here, when the step-down section 5 falls into an output stop state due to a failure, the path on the supply section 6 side becomes effective as the power supply path for the second electric device 4. That is, the second electric device 4 is driven by using a part of the cell 21 as a power source. Therefore, even if the step-down unit 5 fails, the second electric device 4 can be properly driven.
At this time, the switching of the power supply path to the second electric device 4 is automatically performed when the step-down section 5 fails, that is, the output of the step-down section 5 is stopped. That is, it is not necessary to provide a switching unit such as a configuration for detecting a switching trigger (for example, a failure or abnormality of the step-down unit 5) or a switch for route switching, and the number of circuit parts can be reduced.

Further, in the in-vehicle electric system 1 of the present embodiment, the diode D2 is inserted between the step-down portion 5 and the second electric device 4. As shown in the figure, the diode D2 is provided so that the anode is connected to the step-down section 5, and functions as an obstructing section (second blocking section) that inhibits the inflow of current from the supply section 6 to the step-down section 5. do.

The diode D2 exhibits its function when the step-down portion 5 causes a ground fault. That is, assuming that the step-down section 5 has a ground fault and the diode D2 is not provided, the discharge current of a part of the cell 21 flows into the step-down section 5 side via the supply section 6. There is a possibility that the power supply from the unit cell 21 to the second electric device 4 side cannot be performed. By inserting the diode D2, it is possible to prevent the current from flowing into the step-down section 5 side at the time of such a ground fault failure of the step-down section 5, and therefore, even if the step-down section 5 has a ground fault failure, the supply section. 6 can supply electric power to the second electric device 4.

<Second embodiment>
FIG. 2 is a circuit block diagram showing a configuration example of the in-vehicle electric system 1A as the second embodiment.
In the following description, the same parts as those already described will be designated by the same reference numerals and the description thereof will be omitted.

The in-vehicle electric system 1A shown in FIG. 2 is different from the case of the in-vehicle electric system 1 in that a negative electrode side relay 8A is provided instead of the negative electrode side relay 8.
As shown in the figure, the negative electrode side relay 8A is a connection point between the negative electrode side end of the positive electrode side cell portion 22, the positive electrode side end of a part of the cell 21, and the supply portion 6 (in this example, the connection point with the anode of the diode D1). It is inserted between and.

The on / off control of the negative electrode side relay 8A by the battery control unit 10 is performed as the same control as the control for the negative electrode side relay 8 described in the first embodiment.

In the case of the first embodiment, when the vehicle is in the non-starting state and the positive electrode side relay 7 and the negative electrode side relay 8 are turned off, the step-down portion 5 is stopped in operation, and some cells 21 are included. Since the entire battery 2 is cut off, it becomes impossible to supply power to the second electric device 4.

As the second electric device 4, there may be a device that is required to be operable even when the vehicle is not activated. For example, a device for realizing a keyless system that accepts remote control from outside the vehicle and unlocks / locks the door can be mentioned.
With respect to such a second electric device 4, if it is assumed that neither the step-down unit 5 nor the supply unit 6 can supply electric power when the vehicle is not activated, the keyless system cannot be operated properly.

On the other hand, in the in-vehicle electric system 1A in which the negative electrode side relay 8A is provided at the above-mentioned position, even if the positive electrode side relay 7 and the negative electrode side relay 8 are turned off when the vehicle is not started, the supply unit 6 is used. Power can be supplied to the second electric device 4.
Therefore, the second electronic device 4 that should be operated in a non-starting state, such as an electric device for a keyless system, can be properly operated.

<3. Third Embodiment>
FIG. 3 is a circuit block diagram showing a configuration example of the in-vehicle electric system 1B as the third embodiment.
The difference from the in-vehicle electric system 1A of the second embodiment is that the charging relay 9 is added and the battery control unit 10B is provided in place of the battery control unit 10.

The charging relay 9 is an electromagnetic relay connected in parallel to the diode D1 and functions as a bypass switch unit for switching the bypass path for the diode D1 between valid and invalid.
The charging relay 9 makes it possible to charge a part of the cell 21 by using the output of the step-down unit 5. For example, not only when the step-down unit 5 fails as in the second embodiment, but also when the power of some cells 21 is used in the non-starting state of the vehicle, the vehicle is in the starting state (relays 7 and 8A are turned on). It becomes possible to charge a part of the cell 21 according to the fact that the step-down unit 5 becomes operable.

By providing such a charging relay 9, even if a part of the cell 21 is used for driving the second electric device 4, the part of the cell 21 can be used repeatedly.
Further, the charging of the partial cell 21 at this time is performed by the step-down unit 5 using the electric power of the entire battery 2, that is, the electric power of the other battery cell 2a is used to charge the partial cell 21, so that the battery remains. It is possible to balance the balance between cells related to the quantity.

The battery control unit 10B performs on / off control of the charging relay 9 in addition to the control performed by the battery control unit 10.
Specifically, the battery control unit 10B acquires the remaining amount correlation information that correlates with the remaining battery level of some cells 21, and performs on / off control of the charging relay 9 based on at least the remaining amount correlation information. The battery control unit 10B of this example acquires the SOC of at least a part of the cells 21 detected by the battery 2 as the remaining amount correlation information, and charges the battery when the remaining amount of the battery of the part of the cells 21 is equal to or less than a predetermined threshold value THr. The relay 9 is turned on to charge a part of the cell 21.

A specific processing procedure performed by the battery control unit 10B will be described with reference to the flowchart of FIG. The process shown in FIG. 4 is executed by the CPU in the battery control unit 10B based on a program stored in a predetermined storage device such as a ROM.
The process shown in FIG. 4 is started by the battery control unit 10B when the positive electrode side relay 7 and the negative electrode side relay 8A are turned on in response to the above-mentioned ignition switch or the like being turned on. It starts when the step-down operation is possible. Further, at the start of the process shown in FIG. 4, the charging relay 9 is turned off.

First, the battery control unit 10B acquires the remaining amount correlation information of some cells 21 in step S101. That is, in this example, the SOC of some cells 21 detected in the battery 2 is acquired as the remaining amount correlation information.
In the following step S102, the battery control unit 10B determines whether or not the remaining battery level is equal to or less than the threshold value THr. That is, based on the acquired remaining amount correlation information, it is determined whether or not the remaining amount of the battery in some cells 21 corresponds to the threshold value THr or less. For example, it is determined whether or not the acquired SOC is equal to or less than a predetermined threshold value.
When it is determined that the remaining battery level is not equal to or less than the threshold value THr, the battery control unit 10B ends a series of processes shown in this figure. That is, some cells 21 are not charged.

On the other hand, when it is determined that the remaining battery level is equal to or less than the threshold value THr, the battery control unit 10B proceeds to step S103, turns on the charging relay 9, and starts charging a part of the cell 21.
Then, in the following step S104, the battery control unit 10B waits for the establishment of the charging end condition. Specifically, in this example, the process waits until the condition that the remaining battery level of some cells 21 becomes a predetermined value larger than the threshold value THr is satisfied. The charging end condition may be a condition that the remaining battery level of some cells 21 becomes a value larger than the threshold value THr.

In step S104, for example, when it is confirmed that the remaining battery level of some cells 21 is equal to or higher than the above-mentioned predetermined value and it is determined that the charging end condition is satisfied, the battery control unit 10B sets the charging relay 9 in step S105. Turn it off to finish the series of processes shown in this figure. As a result, charging of some cells 21 is completed.

By controlling the on / off of the charging relay 9 based on the remaining amount correlation information of some cells 21 as described above, some cells respond to the fact that the remaining battery level of some cells 21 actually decreases. It is possible to charge 21.
Therefore, it is possible to prevent the partial cell 21 from being charged indiscriminately, and it is possible to extend the life of the partial cell 21.

In the above, an example of acquiring SOC information as the remaining amount correlation information is given, but as the remaining amount correlation information of some cells, information on the amount of power taken out from the part of the cell 21 to the second electric device 4 side is given. Can also be obtained. For example, as the information on the amount to be taken out, it is conceivable to acquire information in Ah (amp-hour) or Wh (watt-hour) units.
When the carry-out amount is used, for example, the charging relay 9 may be turned on on condition that the carry-out amount is equal to or more than a predetermined amount.

Further, the on / off control of the charging relay 9 can also be performed by using information other than the remaining amount correlation information of some cells 21 in combination. For example, when the SOC of a part of the cell 21 (the SOC of the battery cell 2a constituting the part of the cell 21) and the SOC of the other battery cell 22 are acquired and the difference between the SOCs is equal to or more than a predetermined value, the charging relay 9 is obtained. Can also be turned on.
As a result, it is possible to balance the balance between cells related to the remaining battery level.

<4. Summary of Embodiments and Modifications>
As described above, the in-vehicle electric system (1 or 1A or 1B) of the embodiment is driven based on a battery (2) having a plurality of battery cells (2a) and the output voltage of the battery. An electric device (3), a second electric device (4) driven at a lower voltage than the first electric device, and a step-down section (5) that lowers the output voltage of the battery and supplies it to the second electric device. ) And a supply unit that is connected in parallel with the step-down unit to the second electric device and can supply power to the second electric device using a part of the cell (21), which is a part of the battery cell in the battery, as a power source. (Same as 6), the supply section has a first blocking section (diode D1) that inhibits the inflow of current from the step-down section to the cell side, and the step-down section has the rated output of some cells. It supplies a step-down voltage due to a voltage higher than the voltage to the second electric device.

With the above supply unit, even when the output of the step-down unit cannot be obtained, it is possible to supply power to the second electric device by using a part of the cell as a power source.
Further, since the step-down voltage by the step-down part is set to be higher than the rated output voltage of some cells, power is supplied from some cells to the second electric device side in a state where the output of the step-down part is obtained. Further, by having the above-mentioned first inhibitory portion, it is possible to prevent only a part of the cells from being charged by the output of the step-down portion.
As described above, according to the embodiment, in the in-vehicle electric system in which the step-down portion steps down the output voltage of the high-voltage battery and supplies it to the low-voltage device, the low-voltage device can be appropriately driven even when the step-down section fails.
Further, it is possible to prevent power from not being supplied from some cells to the second electric device side in a state where the output of the step-down section is obtained, and to prevent only some cells from being charged by the output of the step-down section. From this point, it is possible to suppress the imbalance between cells related to the remaining battery level in the battery.

Further, the in-vehicle electric system of the embodiment includes a second blocking section (diode D2) that blocks the inflow of current from the supply section to the step-down section side.

As a result, even if the step-down section fails due to a ground fault, the inflow of current from the supply section to the step-down section side is hindered.
Therefore, even if the step-down section fails due to a ground fault, the supply section can properly drive the second electric device.

Further, in the in-vehicle electric system (1A or 1B) of the embodiment, the battery is a cell unit in which a plurality of battery cells are connected in series and is composed of some other battery cells excluding some cells. As a result, the negative electrode side end has a positive electrode side cell portion (22) connected to the positive electrode side end of a part of the cell, and the positive electrode side end of the positive electrode side cell portion is connected in parallel with the first electric device and the step-down portion. It is inserted between the positive electrode side switch portion (7) inserted in series between the circuit, the negative electrode side end of the positive electrode side cell portion, and the connection point between the positive electrode side end of some cells and the supply portion. It also has a negative electrode side switch unit (8A).

The positive electrode side switch portion and the negative electrode side switch portion allow the connection between the positive electrode side cell portion and the electric load to be cut off freely. Then, by inserting the negative electrode side switch portion by the above connection form, even when the positive electrode side cell portion is cut off, that is, the power supply of the step-down portion is cut off, the second electric device is connected to the second electric device via the supply section. It is possible to supply power.
Therefore, it is possible to achieve both improvement in safety by allowing the cell portion on the positive electrode side to be cut off freely and enabling the second electric device to be appropriately driven.
In particular, when the positive electrode side switch section and the negative electrode side switch section are turned off when the vehicle is not activated, the second electronic device such as an electric device for a keyless system that should be operated while the vehicle is not activated is properly used. Can be operated.

Furthermore, the in-vehicle electric system (1B) of the embodiment includes a bypass switch unit (charging relay 9) connected in parallel to the first obstruction unit.

This makes it possible to charge a part of the cell using the output of the step-down portion.
Therefore, even if some cells are used to drive the second electric device, some cells can be used repeatedly.
Further, the charging of some cells at this time is performed by the step-down portion using the electric power of the entire battery, that is, the electric power of other battery cells is used to charge the partial cells, so that the inter-cells related to the remaining battery level are used. It is possible to balance the balance.

Further, in the in-vehicle electric system of the embodiment (1B), the remaining amount correlation information that correlates with the remaining battery level of some cells is acquired, and on / off control of the bypass switch unit is performed based on at least the remaining amount correlation information. It is provided with a control unit (battery control unit 10B) for performing the operation.

This makes it possible to charge some cells according to the fact that the remaining battery level of some cells has actually decreased.
Therefore, it is possible to prevent some cells from being charged indiscriminately, and it is possible to extend the life of some cells.

The present invention is not limited to the specific examples described above, and various modifications can be considered.
For example, in the above, the present invention has been applied to a vehicle having an engine, but the present invention can also be suitably applied to a vehicle having no engine.
When a motor is provided as the first electric device, the motor may be an ISG (Integrated Starter Generator). At this time, the ISG is connected to the crankshaft of the engine and used as a starter motor of the engine. Further, it may be used for torque assist of the engine.

1, 1A, 1B In-vehicle electric system, 2 battery, 2a battery cell, 21 partial cell, 22 positive electrode side cell part, 3 first electric device, 4 second electric device, 5 step-down part, 6 supply part, 7 positive electrode side Relay, 8, 8A negative electrode side relay, 9 charging relay, 10, 10B battery control unit, D1, D2 diode

Claims (4)

A battery with multiple battery cells and
The first electric device driven based on the output voltage of the battery,
The second electric device, which is driven at a lower voltage than the first electric device,
A step-down unit that steps down the output voltage of the battery and supplies it to the second electric device,
A supply unit connected in parallel with the step-down unit to the second electric device and capable of supplying electric power to the second electric device by using a part of the battery cells of the battery as a power source. Equipped with
The supply unit
It has a first inhibitory portion that inhibits the inflow of current from the step-down portion to the partial cell side.
The step-down portion
A step-down voltage due to a voltage higher than the rated output voltage of the partial cell is supplied to the second electric device.
The battery is
The plurality of battery cells are connected in series, and the negative electrode side end is connected to the positive electrode side end of the partial cell as a cell portion composed of some other battery cells excluding the partial cell. It has a positive electrode side cell part and has a positive electrode side cell part.
A positive electrode side switch portion inserted in series between the positive electrode side end of the positive electrode side cell portion and the parallel connection circuit between the first electric device and the step-down portion.
An in-vehicle electric system including a negative electrode side end of the positive electrode side cell portion and a negative electrode side switch portion inserted between a positive electrode side end of the partial cell and a connection point between the supply portion. The vehicle-mounted electric system according to claim 1, further comprising a second blocking section that inhibits the inflow of current from the supply section to the step-down section side. The vehicle-mounted electric system according to claim 1 or 2, further comprising a bypass switch unit connected in parallel to the first obstruction unit. The vehicle according to claim 3 , further comprising a control unit that acquires residual amount correlation information that correlates with the remaining battery level of some of the cells and controls on / off of the bypass switch unit based on at least the remaining amount correlation information. Electrical system.

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