JP2015150958A - Battery system for vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a battery system for a vehicle capable of suppressing progress of degradation of a second storage battery.SOLUTION: Power generation state of an alternator is controlled according to a voltage which is the higher between a first charge voltage required for charging a first storage battery and a second charge voltage required for charging a second storage battery. In a case where a charge rate of the second storage battery is detected to have become a first threshold value or higher and it is determined there is a power generation margin, the power generation state of the alternator is controlled to decrease power generation amount.

Description

  The present invention relates to a vehicle battery system including a first storage battery and a second storage battery mounted on a vehicle including an engine, and more particularly to charging of the first storage battery and the second storage battery by power generation by an alternator.

  For vehicles such as automobiles, lamps such as headlights, small lights, brake lamps, interior lights, drive motors such as power windows, wipers, air conditioners and radiator fans, starters at the start of engines, audio, navigation Various electric devices (electric loads) such as devices are mounted. And the electric power consumed by these electric loads is supplied by the storage battery which can be charged / discharged. Further, the vehicle is provided with an alternator (generator) driven by an engine, and the storage battery is appropriately charged with electric power generated by the alternator.

  In recent years, vehicles equipped with a plurality of storage batteries have been put into practical use in order to increase the electric load and improve the fuel efficiency of the vehicle. For example, a first storage battery that is a lead battery for supplying electric power to an electric load including a starter for starting the engine, and a second storage battery that is connected in parallel to the first storage battery. There is something that was made.

  In the vehicle battery system provided with such a first storage battery and a second storage battery, the first and second storage batteries may be charged simultaneously. Specifically, for example, an opening / closing means such as a relay is arranged in a connection wiring connecting the alternator and the lead storage battery (first storage battery) and the lithium ion storage battery (second storage battery), and the opening / closing means is opened and closed. Charging and discharging from the lithium ion storage battery are controlled (see Patent Document 1).

JP 2013-198318 A

  Thus, when charging a 1st storage battery and a 2nd storage battery simultaneously, there exists a possibility that the 2nd storage battery comprised with a lithium ion battery, a nickel-hydrogen battery, etc. may be in an overcharge state. For example, the amount of power generated by the alternator is determined according to the higher one of the first charging voltage required for charging the first storage battery and the second charging voltage required for charging the second storage battery. In this case, the first charging voltage may be higher than the second charging voltage depending on the driving state or environmental state of the vehicle, and the second storage battery may be overcharged.

  And the 2nd storage battery comprised with a nickel-metal hydride battery etc. has the problem that progress of deterioration accelerates in this overcharge state.

  This invention is made | formed in view of such a situation, and it aims at providing the vehicle battery system which can suppress progress of deterioration of a 2nd storage battery.

  A first aspect of the present invention that solves the above-described problem is a first storage battery that supplies power to a starter for starting an engine, and a second storage battery that is connected in parallel to the first storage battery and has an internal opening / closing means. A battery system for a vehicle comprising: a first storage battery; and an alternator connected to the first storage battery and the second storage battery and generating electric power by driving the engine, wherein the first storage battery and the second storage battery Charging state detecting means for detecting the charging state of the battery, and charging control means for controlling the power generation state of the alternator and the opening / closing state of the internal opening / closing means based on the detection result of the charging state detection means, and the charging The control means is configured to adjust the alternator according to a higher one of a first charging voltage required for charging the first storage battery and a second charging voltage required for charging the second storage battery. When the power generation state of the alternator is controlled in accordance with the first charging voltage, the charge rate of the second storage battery is set in advance by the charge state detecting means. In the vehicle battery system, the power generation state of the alternator is controlled to reduce the power generation amount when it is detected.

  In the first aspect, an excessive increase in the charging rate of the second storage battery can be suppressed, and deterioration of the second storage battery due to overcharging can be suppressed.

  According to a second aspect of the present invention, in the vehicle battery system according to the first aspect, the charging control means controls the power generation state of the alternator to reduce the power generation amount, so as to match the second charging voltage. In the vehicle battery system, the power generation amount is increased.

  In the second aspect, it is possible to more effectively suppress the progress of deterioration of the second storage battery due to overcharging.

  According to a third aspect of the present invention, in the vehicle battery system according to the first or second aspect, the vehicle battery system further includes temperature detection means for detecting a temperature of the first storage battery, and the charge control means further includes the temperature detection means. When the temperature of the first storage battery is detected to be equal to or lower than a predetermined temperature, the power generation state of the alternator is controlled to reduce the power generation amount.

  In the third aspect, an excessive increase in the charging rate of the second storage battery can be effectively suppressed while suppressing a decrease in the charging efficiency of the first storage battery.

  According to a fourth aspect of the present invention, in the vehicle battery system according to any one of the first to third aspects, the charge control unit controls the power generation state of the alternator to reduce the power generation amount, When the charging rate of the second storage battery is further increased by a predetermined value, the internal battery opening / closing means is controlled to be in an open state.

  In the fourth aspect, deterioration of the second storage battery due to overcharging can be suppressed more reliably. Further, the internal opening / closing means can be controlled to open at an appropriate timing, and the number of operations of the internal opening / closing means can be minimized.

  As described above, in the present invention, the progress of the deterioration of the second storage battery due to overcharging can be effectively suppressed.

It is a figure showing composition of a battery system for vehicles concerning one embodiment of the present invention. It is a figure showing composition of a battery system for vehicles concerning one embodiment of the present invention. It is a flowchart which shows an example of the charge control which concerns on one Embodiment of this invention.

  Hereinafter, a vehicle battery system according to an embodiment of the present invention will be described in detail with reference to the drawings.

  As shown in FIG. 1, a vehicle battery system 10 according to the present embodiment supplies power to various electric loads mounted on a vehicle, and includes a first storage battery 11 and a second storage battery 12. It has a storage battery. The first storage battery 11 is composed of a lead battery, and the second storage battery 12 is composed of a nickel metal hydride battery or a lithium ion battery. The second storage battery 12 according to this embodiment includes a battery cell unit 13, and although not shown, the battery cell unit 13 includes a plurality of, for example, about 10 battery cells (nickel metal hydride batteries) in series. Connected to and configured.

  The first storage battery 11 and the second storage battery 12 are connected in parallel. Specifically, the vehicle battery system 10 includes a first electric circuit 14 including a first storage battery 11 and a second electric circuit 15 including a second storage battery 12, and the first electric circuit 14 includes the first electric circuit 14 including the first storage battery 11. The electric circuit 14 and the second electric circuit 15 are connected via a connection wiring 16.

  The first electric circuit 14 includes, together with the first storage battery 11, an alternator (generator) 18 that is driven by the engine 17 to generate electric power, a starter 19 for starting the engine 17, and a first electric load 20. Are connected in parallel. Further, the first electric circuit 14 is provided with a battery sensor (first charge state detection means) 21 for detecting a charge state of the first storage battery 11, for example, a charge rate (SOC), a temperature and the like. The first electric load 20 is an electric load that may be restarted when the engine 17 is started, that is, an electric load that causes no problem if electric power is supplied while the vehicle is running. A headlamp, a heater, etc. are mentioned.

  On the other hand, the second electric circuit 15 is configured by connecting the second storage battery 12 and the second electric load 22 in parallel. In contrast to the first electrical load 20, the second electrical load 22 is preferably an electrical load that is not restarted when the engine 17 is started. For example, a car navigation device, audio, or the like can be given. It is done. Note that the separation of the first electric load 20 and the second electric load 22 of various electric loads is not limited to the above-described one, and may be appropriately set as necessary.

  The connection wiring 16 that connects the first electric circuit 14 and the second electric circuit 15 cuts off the flow of electricity from the second electric circuit 15 side to the first electric circuit 14 side. A possible external relay unit (external opening / closing means) 23 is provided. The external relay unit 23 includes a rectifying unit 23b formed of a diode together with the switch unit 23a.

  As shown in FIG. 1, when the switch unit 23a is in the closed state (connected state), the charging state of the first storage battery 11 and the second storage battery 12, the power generation state of the alternator 18, the first electric load 20 and Depending on the amount of power consumed by the second electrical load 22, etc., the flow of electricity from the first electrical circuit 14 side to the second electrical circuit 15 side is also the first from the second electrical circuit 15 side. The flow of electricity to the electric circuit 14 side can also occur. That is, electric power may be supplied from the first storage battery 11 or the alternator 18 to the second electric load 22, or electric power may be supplied from the second storage battery 12 to the first electric load 20.

  For example, when the engine 17 is in operation and the charge amounts of the first storage battery 11 and the second storage battery 12 are sufficient, the switch unit 23a is controlled to be closed. In this state, power is supplied to the first electrical load 20 not only from the first storage battery 11 but also from the second storage battery 12. Thereby, the electric power generation amount of the alternator 18 can be suppressed, and the fuel efficiency can be improved accordingly.

  On the other hand, as shown in FIG. 2, when the switch portion 23a is in the open state (disconnected state), only the flow of electricity from the second electric circuit 15 side to the first electric circuit 14 side is blocked. That is, the flow of electricity from the first electric circuit 14 side to the first electric circuit 14 side is maintained by the rectifying unit 23b provided in the external relay unit 23 as indicated by an arrow in the figure. Therefore, in this state, electric power may be supplied from the first storage battery 11 or the alternator 18 together with the second storage battery 12 to the second electrical load 22, but the first electrical load 20 is supplied to the first electrical load 20. On the other hand, electric power is supplied from the first storage battery 11 or the alternator 18, and no electric power is supplied from the second storage battery 12.

  Furthermore, the second storage battery 12 includes, for example, a mechanical internal relay (internal opening / closing means) 24, and is configured so that the connection state between the battery cell unit 13 and the connection wiring 16 can be appropriately switched by the internal relay 24. ing. The internal opening / closing means 24 may be constituted by a semiconductor relay or the like in addition to the mechanical relay.

  The external relay unit 23 and the internal relay 24 are appropriately controlled by a battery control unit (BMU) 26 based on a signal from the ECU 25. The BMU 26 includes a battery sensor that detects a charging state of the battery cell unit 13 that constitutes the second storage battery 12, a control unit (not shown) for controlling the external relay unit 23 and the internal relay 24, and the like. Consists of. The BMU 26 is provided in the second storage battery 12 in this embodiment, but may be provided separately from the second storage battery 12.

  The ECU (electronic control unit) 25 includes an input / output device, a storage device that stores a control program, a control map, and the like, a central processing unit, timers and counters, and based on information from various sensors, The overall control of the engine 17 including the starter 19 and the like is performed.

  The ECU 25 also serves as a part of the vehicle battery system 10 according to the present embodiment. For example, the ECU 25 controls the open / close state of the external relay unit 23 and the internal relay 24 via the BMU 26 as described above, and appropriately controls the power generation state (power generation amount) of the alternator 18. Thereby, the charging state (charging rate) of the 1st storage battery 11 and the 2nd storage battery 12 is controlled suitably, supplying desired electric power to various electric loads.

  Hereinafter, an example of control (charge control) of the state of charge of the storage battery in the vehicle battery system 10 will be described.

  The ECU 25 includes a charge control unit 27 as a unit for controlling the charging state (charging rate) of the first storage battery 11 and the second storage battery 12.

  The charging control means 27 controls the power generation amount of the alternator 18 according to the charging state (charging rate) of the first storage battery 11 and the second storage battery 12 to charge the first storage battery 11 and the second storage battery 12. Run. In the present embodiment, the battery sensor (first charge state detection means) 21 detects the charge state of the first storage battery 11, and the BMU (second charge state detection means) 26 detects the charge state of the second storage battery 12. Is detected. In the present embodiment, the battery sensor 21 also has a function as a temperature detection unit that detects the temperature of the first storage battery 11. Then, the charge control means 27 drives the engine 17 so that the power generation amount by the alternator 18 becomes a desired value based on the detection result by the battery sensor 21 and the BMU 26 as well as the driving state and environmental state of the vehicle. Control appropriately.

  The battery sensor 21 may directly detect the temperature of the first storage battery 11. For example, the battery sensor 21 may detect the outside air temperature and estimate the temperature of the first storage battery 11 based on the outside air temperature. Good.

  When the first storage battery 11 or the second storage battery 12 is discharged, that is, when the charge rate (SOC) of the first storage battery 11 or the second storage battery 12 is equal to or lower than the charging start threshold, The power generation of the alternator 18 is started and charging of the first storage battery 11 or the second storage battery 12 is started. Then, when the charging end threshold is reached, the power generation of the alternator 18 is ended.

  The charging start threshold and the charging end threshold are appropriately determined according to the characteristics of the storage batteries 11 and 12. In this embodiment, the charging start threshold of the first storage battery 11 is set to 90%, the charging end threshold is set to 95%, the charging start threshold of the second storage battery 12 is set to 30%, and the charging end threshold is set to 50%. ing.

  At normal time, the charging control means 27 places the internal relay 24 in a connected state when charging the first storage battery 11 and the second storage battery 12 (see FIG. 1). In this state, as indicated by an arrow in the figure, the electric power generated by the alternator 18 is supplied to the first storage battery 11 and the second storage battery 12, and the storage batteries 11 and 12 are charged simultaneously.

  Thereafter, when the charging rate (SOC) of the first storage battery 11 or the second storage battery 12 becomes equal to or higher than the charging end threshold, the power generation amount of the alternator 18 by the engine 17 is suppressed, and the charging of the storage batteries 11 and 12 is ended. In addition, the above-mentioned “normal time” means a state in which the first storage battery 11 or the second storage battery 12 is slightly discharged, that is, the charging rate of the first storage battery 11 or the second storage battery 12 is equal to or less than the charging start threshold value. This is a state in which the charging rates of the first storage battery 11 and the second storage battery 12 are lower than the charging end threshold.

  As described above, the charging control unit 27 normally controls the power generation amount of the alternator 18 so as to charge the first storage battery 11 and the second storage battery 12 at the normal time. Depending on the state of charge (charge rate) of the storage battery 12, the charging of the second storage battery 12 is interrupted.

  When charging the first storage battery 11 and the second storage battery 12, the amount of power generated by the alternator 18 is determined based on the first charging voltage (electric power) required for charging the first storage battery 11 and the second storage battery 12. It is determined according to the larger value of the second charging voltage (electric power) required for charging. Since this value is often higher in the second charging voltage than in the first charging voltage, the amount of power generated by the alternator 18 is determined according to the second charging voltage. For this reason, the second storage battery 12 is not overcharged. However, for example, when the temperature of the first storage battery 11 is lowered to an extremely low temperature (for example, about −20 ° C. or less), the charge acceptance of the first storage battery 11 is reduced, and the second charge voltage The first charging voltage may be higher than the first charging voltage. In such a case, since the power generation amount of the alternator 18 is determined according to the first charging voltage higher than the second charging voltage, the second storage battery 12 is in an overcharged state (for example, SOC is 80% or more). There is a risk of becoming. And the 2nd storage battery 12 has a possibility that progress of deterioration may be accelerated | stimulated because an overcharge state continues.

  Therefore, the charge control means 27 according to the present embodiment appropriately controls the power generation state of the alternator 18 and the open / close state of the internal relay 24 in order to eliminate the overcharge state of the second storage battery 12. Specifically, when the charge control means 27 controls the power generation state (power generation amount) of the alternator in accordance with the first charge voltage, the charging rate of the second storage battery 12 is set to a first threshold value (for example, by the BMU 26). When it is detected that the power generation amount is about 60% or more, first, the power generation state of the alternator 18 is controlled to reduce the power generation amount. The first threshold value may be set as a value equal to the charging end threshold value.

  Further, as described above, overcharge of the second storage battery 12 is likely to occur when the temperature of the first storage battery 11 is extremely low, for example. For this reason, the charging control means 27 satisfies the above conditions, and further, when the battery sensor 21 detects that the temperature of the first storage battery 11 is equal to or lower than a predetermined temperature (for example, −20 ° C.), the alternator 18 The power generation state may be controlled to reduce the power generation amount.

  Thus, by reducing the electric power generation amount of the alternator 18, it can suppress that the 2nd storage battery 12 will be in an overcharge state, and can advance the progress of deterioration of the 2nd storage battery 12. FIG.

  The amount of power generation to be reduced at this time may be appropriately determined according to the characteristics of the second storage battery 12 so that the second storage battery 12 is not overcharged. It is preferable that the power generation amount of the alternator 18 after being controlled becomes a value corresponding to the second charging voltage. Thereby, degradation of the 2nd storage battery 12 can be suppressed, suppressing the fall of the charge efficiency of the 1st storage battery 11. FIG.

  Furthermore, in this embodiment, after the charge control means 27 detects that the charging rate of the second storage battery 12 is equal to or higher than the first threshold value described above by the BMU 26, the charging rate of the second storage battery 12 further increases. When the predetermined value increases, the internal relay 24 is controlled to be in an open state. Although the power generation amount of the alternator 18 is reduced as described above, it is assumed that the charging rate of the second storage battery 12 increases due to, for example, a change in the driving state of the vehicle or a failure of the alternator 18. The In such a case, the charging control unit 27 controls the internal relay 24 to be in an open state when the charging rate of the second storage battery 12 increases by a predetermined value, for example, about 2%.

  Thereby, even when a failure or the like of the alternator 18 occurs, overcharge of the second storage battery 12 can be suppressed, and deterioration of the second storage battery 12 associated therewith can also be suppressed. Further, by controlling the internal relay 24 to the open state at such timing, it is possible to suppress the number of operations of the internal relay 24 as much as possible while suppressing the deterioration of the second storage battery 12.

  When the internal relay 24 is opened / closed, a relatively loud sound is generated. Therefore, if the opening / closing control of the internal relay 24 is frequently performed, there is a possibility that the passenger may feel uncomfortable. In particular, when the second storage battery 12 is disposed under the floor of the vehicle, it is easy to give the passenger discomfort. However, as described above, by suppressing the number of times of operation of the internal relay 24 as much as possible, occupant discomfort can be minimized.

  Hereinafter, an example of the charge control of the present embodiment will be further described with reference to the flowchart of FIG.

  First, in step S1, it is determined whether or not the state of charge of the first storage battery 11 and the second storage battery 12 is slightly discharged. Specifically, the charging rate (SOC) of the first storage battery 11 is equal to or lower than the charging start threshold (for example, 90%), and the charging rate of the second storage battery 12 is equal to or lower than the charging start threshold (for example, 30%). It is determined whether or not. Here, when the charging state of the first storage battery 11 and the second storage battery 12 is slightly discharged (step S1: Yes), for example, the rotational speed of the engine 17 in the idling state is controlled, and the alternator 18 By increasing the power generation amount, charging of the first storage battery 11 and the second storage battery 12 is started (step S2).

  Next, it is determined in step S3 whether or not the charging rates of the first and second storage batteries 11 and 12 are equal to or higher than a charging end threshold. Specifically, it is determined whether the charging rate of the first storage battery 11 is higher than 95% and the charging rate of the second storage battery 12 is higher than 50%. When the charging rates of both storage batteries 11 and 12 have not reached the charging end threshold value (step S3: No), the charging rate of the second storage battery 12 is equal to or higher than the first threshold value (for example, 60%) in step S4. It is determined whether or not there is. When the charging rate of the second storage battery 12 is equal to or higher than the first threshold value, that is, the charging rate of the first storage battery 11 is smaller than the charging end threshold value and the charging rate of the second storage battery 12 is equal to or higher than the first threshold value. If there is any (step S4: Yes), the power generation amount by the alternator 18 is appropriately adjusted in step S5. That is, the power generation amount of the alternator 18 is appropriately reduced as necessary so as to suppress an increase in the charging rate of the second storage battery 12. For example, as described above, when the first storage battery 11 is at a very low temperature and the power generation amount of the alternator 18 is controlled based on the first charging voltage, the power generation amount of the alternator 18 is appropriately reduced.

  When the charging rate of the second storage battery 12 is smaller than the first threshold value in step S4 (step S4: No), the process returns to step S3 and the charging of both storage batteries 11 and 12 is continued as it is.

  After adjusting the power generation amount of the alternator 18 in step S5, it is determined in step S6 whether the charging rate of the second storage battery 12 has further increased by a predetermined value (for example, 2%). When the charging rate of the second storage battery 12 has not increased by a predetermined value (step S6: No), the process returns to step S3. For example, when the charging rate of the second storage battery 12 increases by a predetermined value due to a change in the driving state of the vehicle (step S6: Yes), after controlling the internal relay 24 to the open state in step S7 Return to step S3. Thereafter, when it is detected that the charging rate of both storage batteries 11 and 12 is equal to or higher than the charging end threshold (step S3: Yes), the power generation amount of the alternator 18 is returned to the normal time in step S8, and the series of charging control is finished. . At this time, if the internal relay 24 is in the closed state, the internal relay 24 is controlled to be in the closed state, and the charging control is terminated.

  Thus, when charging the 1st storage battery 11 and the 2nd storage battery 12, the 2nd storage battery 12 will be in an overcharge state by controlling appropriately the power generation state of alternator 18, and the opening-and-closing state of internal relay 24. This can be suppressed, and the progress of deterioration of the second storage battery 12 can be delayed.

  As mentioned above, although one Embodiment of this invention was described, of course, this invention is not limited to the above-mentioned embodiment, In the range which does not deviate from the meaning, it can change suitably.

DESCRIPTION OF SYMBOLS 10 Vehicle battery system 11 1st storage battery 12 2nd storage battery 13 Battery cell unit 14 1st electric circuit 15 2nd electric circuit 16 Connection wiring 17 Engine 18 Alternator 19 Starter 20 1st electric load 21 Battery sensor 22 2nd electric load 23 External relay unit 23a Switch part 23b Rectification part 24 Internal relay 25 ECU
26 BMU
27 Charge control means

Claims (4)

A first storage battery for supplying power to a starter for starting the engine;
A second storage battery connected in parallel with the first storage battery and having internal opening and closing means;
An alternator connected to the first storage battery and the second storage battery and generating electric power by driving the engine;
A vehicle battery system comprising:
Charge state detection means for detecting a charge state of the first storage battery and the second storage battery;
Charge control means for controlling the power generation state of the alternator and the open / close state of the internal open / close means based on the detection result of the charge state detection means;
Have
The charge control means includes
The power generation state of the alternator is controlled according to the higher one of the first charging voltage required for charging the first storage battery and the second charging voltage required for charging the second storage battery. ,
When controlling the power generation state of the alternator in accordance with the first charging voltage, it is detected by the charging state detection means that the charging rate of the second storage battery is equal to or higher than a preset first threshold value. Then, the power generation state of the alternator is controlled to reduce the power generation amount. The vehicle battery system according to claim 1,
The charge control means includes
A vehicle battery system characterized in that when the power generation state of the alternator is controlled to reduce the power generation amount, the power generation amount matches the second charging voltage. The vehicle battery system according to claim 1 or 2,
Temperature detecting means for detecting the temperature of the first storage battery,
The charge control means includes
Furthermore, when the temperature detecting unit detects that the temperature of the first storage battery is equal to or lower than a predetermined temperature, the power generation state of the alternator is controlled to reduce the power generation amount. . The vehicle battery system according to any one of claims 1 to 3,
The charge control means includes
After the power generation state of the alternator is controlled to reduce the power generation amount, the internal opening / closing means is controlled to be opened when the charging rate of the second storage battery further increases by a predetermined value. Battery system.

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