JP6638650B2 - Lead storage battery deterioration determination apparatus and lead storage battery deterioration determination method - Google Patents

Description

  The present disclosure relates to a lead storage battery deterioration determination device and a lead storage battery deterioration determination method for determining whether or not a lead storage battery is deteriorated, a charge control device for charging a lead storage battery and a secondary battery connected in parallel with each other, and a charging device. Control method.

  A vehicle having an engine as a main power source includes a battery as a power source of a starter motor for starting the engine. As this battery, a lead storage battery is generally used.

  Further, in recent years, a battery is charged with electric power generated by a generator using energy generated when a vehicle starts deceleration by a brake while traveling (energy regeneration). However, when energy is regenerated, quick charging is performed. However, it is difficult to effectively regenerate energy because a lead storage battery cannot perform sufficient rapid charging.

  Therefore, there is known a vehicle including a power supply unit in which a secondary battery other than a lead storage battery, such as a nickel-metal hydride secondary battery or a lithium ion secondary battery, capable of performing sufficient rapid charging is connected in parallel with the lead storage battery (Japanese Patent Application Laid-Open No. H10-157163). 1).

  However, in Patent Document 1, further improvement has been desired.

JP 2012-90404 A

  In order to solve the above-mentioned problem, a first aspect of the present invention provides a power supply unit including a lead storage battery and a secondary battery other than the lead storage battery connected in parallel to each other, and a voltage detection unit for detecting a voltage of the power supply unit. An acquisition unit that acquires an internal resistance of the secondary battery; a storage unit that previously stores an entire current value supplied from the power supply unit to the starting motor when the engine is started by the starting motor; A starting voltage, which is a voltage of the power supply unit at the time of starting the engine by the motor, is detected by the voltage detection unit, and the detected starting voltage and an internal resistance of the secondary battery acquired by the acquisition unit. A calculating unit that calculates the internal resistance of the lead-acid battery using the total current value stored in the storage unit; and an internal resistance of the lead-acid battery calculated by the calculating unit and a predetermined resistance threshold. And the ratio To, when the internal resistance of the lead-acid battery is higher than the threshold resistance value, the lead-acid battery in which and a determination unit to be deteriorated.

  According to this aspect, further improvement can be achieved.

FIG. 2 is a block diagram schematically illustrating a configuration of a vehicle including a battery control unit according to the first embodiment. It is a figure which shows transition of the voltage of a power supply part schematically. It is a figure showing an equivalent circuit of ISG, a lead storage battery, and a nickel hydrogen storage battery. 5 is a flowchart schematically showing an operation of a battery control unit. It is a figure which shows roughly transition of the internal resistance of the lead storage battery and the nickel-metal hydride storage battery used for a vehicle. It is a block diagram showing roughly composition of a vehicle containing a battery control part and ECU of a 2nd embodiment. FIG. 4 is a diagram schematically illustrating an example of a table representing a relationship between a threshold value of a lead storage battery 50 and an SOC value of a nickel-metal hydride storage battery at the start of charging. 7 is a timing chart schematically showing a charging current when the power supply unit of FIG. 6 is charged at a constant voltage of 13.7 V. It is a flowchart which shows the charging operation | movement of 2nd Embodiment schematically. FIG. 10 is a diagram schematically illustrating an example of SOCs of a lead storage battery and a nickel-metal hydride storage battery that are increased by the charging operation in FIG. 9. It is a flowchart which shows the charging operation | movement of 3rd Embodiment schematically. FIG. 12 is a diagram schematically illustrating an example of the SOC of a lead storage battery and a nickel-metal hydride storage battery that are increased by the charging operation in FIG. 11. 6 is a timing chart schematically showing an operation of the switch element. 4 is a timing chart schematically showing an output voltage of ISG. It is a block diagram showing roughly composition of a vehicle containing a battery control part and ECU of a 4th embodiment. It is a flowchart which shows the charging operation | movement of 4th Embodiment schematically. FIG. 17 is a diagram schematically illustrating an example of the SOC of a lead storage battery and a nickel-metal hydride storage battery that are increased by the charging operation in FIG. 16. 6 is a timing chart schematically showing an operation of the switch element. It is a flowchart which shows the charging operation | movement of 5th Embodiment schematically. It is a flowchart which shows the charging operation | movement of 5th Embodiment schematically. It is a block diagram showing roughly composition of a vehicle containing a battery control part and ECU of a 6th embodiment. 16 is a timing chart schematically showing a charging current when the power supply unit of FIG. 15 is charged at a constant voltage of 13.7 V. 4 is a timing chart schematically showing an output voltage of ISG. 4 is a timing chart schematically illustrating a charging current when a power supply unit configured by connecting a lead storage battery and a nickel hydride storage battery in parallel with each other is charged at a constant voltage.

(History leading to inventing the first aspect according to the present disclosure)
First, the viewpoint of the first embodiment according to the present disclosure will be described.

  A first aspect of the present disclosure relates to a lead storage battery deterioration determination device and a lead storage battery that can accurately determine deterioration of a lead storage battery in a configuration including a power supply unit in which a secondary battery other than the lead storage battery is connected in parallel with the lead storage battery. An object of the present invention is to provide a method for determining deterioration of a storage battery.

  2. Description of the Related Art In recent years, vehicles having an idle stop function have become widespread in order to reduce exhaust gas from vehicles whose main power source is an engine. In a vehicle having an energy regeneration function as described above and an idle stop function, the lead storage battery is frequently charged and discharged. For this reason, there is a concern about deterioration of the lead storage battery. However, Patent Document 1 does not sufficiently examine whether the lead storage battery is deteriorated or not.

  In view of this, the present inventor has proposed a power supply unit including a lead storage battery and a secondary battery other than the lead storage battery (a nickel-metal hydride storage battery in the present embodiment) connected in parallel with each other, similarly to the technique described in Patent Document 1. The deterioration of lead storage batteries when used in vehicles was studied. As the battery deteriorates, the internal resistance of the battery increases.

  FIG. 5 is a diagram schematically showing changes in internal resistance of a lead storage battery and a nickel hydride storage battery used in a vehicle. The upper diagram of FIG. 5 shows the transition of the internal resistance of each of the lead storage battery and the nickel hydride storage battery. The lower diagram of FIG. 5 shows the transition of the combined internal resistance obtained by combining the internal resistances of the lead storage battery and the nickel hydride storage battery.

  Lead-acid batteries used in vehicles are generally replaced every three years. Therefore, as shown in the upper diagram of FIG. 5, the internal resistance Rpb of the lead storage battery continues to increase for three years from the initial value Rpb0, but returns to the initial value Rpb0 every three years after replacement. On the other hand, nickel-metal hydride storage batteries are designed to have a life of 9 years or more, which is the same as that of vehicles. Therefore, as shown in the upper diagram of FIG. 5, the internal resistance Rni of the nickel-metal hydride storage battery continues to increase for nine years from the initial value Rni0.

  As a result, the combined internal resistance Rt of the lead storage battery and the nickel-metal hydride storage battery continues to increase for three years from the initial value R0, and then decreases when the lead storage battery is replaced three years later. However, since the internal resistance of the nickel-metal hydride storage battery has increased, the combined internal resistance Rt decreases only to a resistance value R3 higher than the initial value R0. Six years later, similarly, the combined internal resistance Rt decreases due to the replacement of the lead storage battery, but only decreases to a resistance value R6 higher than the resistance value R3.

  Therefore, when the deterioration determination of the lead storage battery is performed by comparing the predetermined resistance threshold Rd with the combined internal resistance Rt, it is possible to determine the deterioration at an appropriate timing three years after the start of use of the vehicle. However, after the replacement of the lead storage battery, the combined internal resistance Rt reaches the resistance threshold Rd in Td years (3 <Td <6) from the start of use of the vehicle. For this reason, it is determined that the lead storage battery has deteriorated within three years from the replacement of the lead storage battery, even though the lead storage battery has not deteriorated. Therefore, it is necessary to determine the deterioration of the lead storage battery based on the internal resistance Rpb of the lead storage battery alone instead of the combined internal resistance Rt.

  Therefore, it is conceivable to provide a current sensor for detecting the current flowing through the lead-acid battery and a voltage sensor for detecting the terminal voltage of the lead-acid battery, and calculate the internal resistance of the lead-acid battery from the detected current and the terminal voltage. However, since a large current flows when the engine is started, an expensive and large-sized current sensor is required to detect such a large current, which leads to an increase in cost and installation space.

  The present inventor has arrived at the invention of each aspect included in the first aspect according to the present disclosure as described below, based on the above examination.

  A first aspect according to the present disclosure is a power supply unit including a lead storage battery and a secondary battery other than the lead storage battery connected in parallel to each other, a voltage detection unit that detects a voltage of the power supply unit, and the secondary battery. An acquisition unit that acquires an internal resistance of the motor, a storage unit that stores in advance a total current value supplied from the power supply unit to the starting motor when the engine is started by the starting motor, and starting of the engine by the starting motor. The starting voltage which is the voltage of the power supply unit at the time is detected by the voltage detecting unit, and the detected starting voltage, the internal resistance of the secondary battery acquired by the acquiring unit, and stored in the storage unit. Using the calculated overall current value, an arithmetic unit for calculating the internal resistance of the lead storage battery, and comparing the internal resistance of the lead storage battery calculated by the arithmetic unit with a predetermined resistance threshold, Lead storage battery If the internal resistance is higher than the threshold resistance value, the lead-acid battery in which comprises a a determination unit has deteriorated, the.

  According to this aspect, the starting voltage, which is the voltage of the power supply unit when the engine is started by the starting motor, is detected by the voltage detecting unit. Using the detected starting voltage, the internal resistance of the secondary battery, and the overall current value supplied to the starting motor from the power supply unit when the engine is started by the starting motor, the internal resistance of the lead storage battery is calculated by the arithmetic unit. Is calculated. The total current value supplied from the power supply unit to the starting motor when the engine is started by the starting motor depends on the specifications of the starting motor and the engine. Therefore, when the starting motor and the engine are determined, the overall current value is also determined. Therefore, the entire current value can be stored in the storage unit in advance.

  First, using the total current value stored in the storage unit and the detected starting voltage, the combined internal resistance of the secondary battery and the lead storage battery connected in parallel to each other is calculated. Next, the internal resistance of the lead storage battery is calculated from the calculated combined internal resistance and the obtained internal resistance of the secondary battery. When the internal resistance of the lead storage battery is higher than the resistance threshold, the determination unit determines that the lead storage battery has deteriorated. Therefore, the deterioration of the lead storage battery can be accurately determined using the internal resistance of the lead storage battery alone.

  In the first aspect, for example, when the determination unit determines that the lead storage battery has deteriorated, the determination unit may prohibit automatic stop of the engine by idle stop control.

  According to this aspect, when the determination unit determines that the lead storage battery is deteriorated, the automatic stop of the engine by the idle stop control is prohibited by the determination unit. Therefore, it is possible to avoid a situation in which the automatically stopped engine cannot be started due to deterioration of the lead storage battery.

  In the first aspect, for example, the starting motor may be a motor that starts the engine automatically stopped by the idle stop control.

  In the first aspect, for example, the starting motor may be a motor that starts the engine by an operation of an ignition switch by a user.

  Another aspect according to the present disclosure is a lead storage battery deterioration determination method in a lead storage battery deterioration determination device including a power supply unit including a lead storage battery and a secondary battery other than the lead storage battery connected in parallel to each other, An obtaining step of obtaining an internal resistance of the secondary battery, a detecting step of detecting a starting voltage that is a voltage of the power supply unit when the engine is started by a starting motor, and the starting voltage detected in the detecting step; Using the internal resistance of the secondary battery acquired in the acquiring step and the total current value supplied to the starting motor from the power supply unit when the engine is started by the starting motor, Calculating the internal resistance, comparing the internal resistance of the lead-acid battery calculated in the calculation step with a predetermined resistance threshold, If the internal resistance of Kinamari battery is higher than the threshold resistance value, the lead-acid battery is intended to include, a determining step of determining to be deteriorated.

  According to this aspect, the starting voltage detected in the detecting step, the internal resistance of the secondary battery acquired in the acquiring step, and the total current supplied from the power supply unit to the starting motor when the engine is started by the starting motor. Using the value, the internal resistance of the lead storage battery is calculated in a calculation step. The total current value supplied from the power supply unit to the starting motor when the engine is started by the starting motor depends on the specifications of the starting motor and the engine. Therefore, when the starting motor and the engine are determined, the overall current value is also determined. Therefore, a predetermined total current value can be used.

  First, using the total current value and the detected starting voltage, the combined internal resistance of the secondary battery and the lead storage battery connected in parallel is calculated. Next, the internal resistance of the lead storage battery is calculated from the calculated combined internal resistance and the internal resistance of the secondary battery. In the determining step, when the internal resistance of the lead storage battery is higher than the resistance threshold, it is determined that the lead storage battery is deteriorated. Therefore, the deterioration of the lead storage battery can be accurately determined using the internal resistance of the lead storage battery alone.

(1st Embodiment)
Hereinafter, a first embodiment of the present invention will be described with reference to the drawings. The following embodiments are merely examples embodying the present invention, and do not limit the technical scope of the present invention. In each of the drawings, the same elements are denoted by the same reference numerals, and the description will be appropriately omitted.

  FIG. 1 is a block diagram schematically showing a configuration of a vehicle 1 including a battery control unit 80 according to the first embodiment.

  The vehicle 1 is a hybrid electric vehicle that uses an engine as a main power source and a motor as an auxiliary power source. The vehicle 1 includes an engine 10, a starter motor 20, an integrated starter generator (ISG) 30, an electric load 40, a power supply unit 45, an electronic control unit (ECU) 70, and a battery control unit 80 according to the first embodiment.

  Power supply unit 45 includes a lead storage battery 50 and a battery pack 60. Battery pack 60 includes a nickel-metal hydride storage battery 61 and a resistance detection unit 62. The lead storage battery 50 and the nickel hydride storage battery 61 are connected in parallel with each other. The starter motor 20 (an example of a starting motor) starts the engine 10 when an ignition switch is operated by a user.

  The ISG 30 (an example of a starting motor) has both a power generation function and an electric function. When a brake pedal (not shown) is operated to start deceleration while the vehicle 1 is traveling, torque is transmitted from the wheels to the ISG 30, and the ISG 30 generates power by a power generation function. When the generated electric power exceeds the electric load of the electrical load 40, the generated electric power charges the lead storage battery 50 and the nickel hydride storage battery 61 of the power supply unit 45. As a result, energy is regenerated. When the vehicle 1 stops, the engine 10 automatically stops by the idle stop control of the ECU 70. When the vehicle 1 starts, the vehicle 1 is driven by the electric function of the ISG 30 and the engine 10 is started.

  The electric load 40 includes loads of electric components and the like mounted on the vehicle 1 such as an air conditioner and a room light. The nominal voltage of the lead storage battery 50 and the nickel hydride storage battery 61 is, for example, 12 V in the first embodiment. The power output from the power supply unit 45 is used for driving the starter motor 20 and the ISG 30 for starting the engine 10 of the vehicle 1 and for powering the electrical load 40.

  The resistance detection unit 62 of the battery pack 60 detects the internal resistance Rni of the nickel-metal hydride storage battery 61. The resistance detection unit 62 includes, for example, a current detection unit including a shunt resistor and a voltage detection unit that detects a terminal voltage of the nickel-metal hydride storage battery 61. The resistance detector 62 is provided to determine whether the nickel-metal hydride storage battery 61 is abnormal and protect the battery pack 60. The resistance detection unit 62 is configured to output a warning signal to the ECU 70, for example, when detecting that the internal resistance Rni of the nickel-metal hydride storage battery 61 is equal to or greater than a predetermined value.

  The ECU 70 includes, for example, a CPU (Central Processing Unit) that executes predetermined arithmetic processing, a ROM (Read Only Memory) in which a predetermined control program is stored, and a RAM (Random Access Memory) in which data is temporarily stored. Peripheral circuits are provided. The ECU 70 is configured to be able to communicate with the battery control unit 80.

  The ECU 70 controls the entire operation of the vehicle 1 including the engine 10, the starter motor 20, the ISG 30, and the electrical load 40. The ECU 70 automatically stops the engine 10 when a predetermined stop condition such as stopping the vehicle 1 at an intersection or the like for a predetermined time, and again when a predetermined start condition such as operation release of a brake pedal (not shown) is satisfied. An idle stop control for starting the engine 10 is performed. When a prohibition signal (described later) is notified from the battery control unit 80, the ECU 70 does not automatically stop the engine 10 by the idle stop control.

  The battery control unit 80 includes, for example, a CPU that executes predetermined arithmetic processing, a ROM in which a predetermined control program is stored, a RAM in which data is temporarily stored, and peripheral circuits thereof. The battery control unit 80 includes a storage unit 81 configured by, for example, a flash memory or the like, and a voltage detection unit 82. The battery control unit 80 functions as a calculation unit 83 and a determination unit 84 by executing a control program stored in the ROM.

  The storage unit 81 stores in advance the total current value It supplied from the power supply unit 45 to the starter motor 20 or the ISG 30 when the starter motor 20 or the ISG 30 starts the engine 10. The overall current value It depends on the specifications of the engine 10, the starter motor 20, and the ISG 30. Therefore, when the engine 10, the starter motor 20, and the ISG 30 are determined, the overall current value It is also determined. In the first embodiment, when the starter motor 20 starts the engine 10, the total current value supplied to the starter motor 20 from the power supply unit 45 and when the ISG 30 starts the engine 10, Is substantially the same as the total current value supplied to the power supply. The overall current value It is, for example, 500A.

  The storage unit 81 stores in advance a resistance threshold value Rth for determining whether or not the lead storage battery 50 has deteriorated. The storage unit 81 stores in advance a voltage threshold Vth for determining whether the engine 10 has been started.

  Voltage detecting section 82 detects voltage Vt of power supply section 45. The voltage detector 82 outputs the detected voltage Vt to the calculator 83. The operation unit 83 compares the voltage Vt of the power supply unit 45 detected by the voltage detection unit 82 with the voltage threshold Vth stored in the storage unit 81, and determines whether the engine 10 has been started by the starter motor 20 or the ISG 30. Determine whether or not.

  FIG. 2 is a diagram schematically showing a transition of voltage Vt of power supply unit 45. When the engine 10 is started by the starter motor 20 or the ISG 30, a large current (for example, 500 A as described above) is supplied from the power supply unit 45 to the starter motor 20 or the ISG 30. For this reason, as shown in FIG. 2, when the engine 10 is started by the starter motor 20 or the ISG 30 at the time T0, the voltage Vt of the power supply unit 45 is suddenly reduced to the minimum voltage Vmin (an example of the starting voltage). And then gradually returns to the original voltage.

  When the voltage Vt of the power supply unit 45 drops below the voltage threshold Vth stored in the storage unit 81, the calculation unit 83 determines that the engine 10 has been started. The calculation unit 83 acquires the minimum voltage Vmin detected by the voltage detection unit 82 from the voltage detection unit 82. The voltage threshold Vth is set to an appropriate value of, for example, about 10 V in accordance with the specifications of the engine 10, the starter motor 20, the ISG 30, and the power supply unit 45, and is stored in the storage unit 81 in advance.

  Returning to FIG. 1, when determining that the engine 10 has been started by the starter motor 20 or the ISG 30, the computing unit 83 (an example of an acquiring unit) acquires the internal resistance Rni of the nickel-metal hydride storage battery 61 from the resistance detecting unit 62. The calculation unit 83 (an example of a calculation unit) includes the minimum voltage Vmin detected by the voltage detection unit 82, the overall current value It stored in the storage unit 81, and the nickel-metal hydride storage battery 61 obtained from the resistance detection unit 62. The internal resistance Rpb of the lead storage battery 50 is calculated using the internal resistance Rni.

FIG. 3 is a diagram showing an equivalent circuit of the ISG 30, the lead storage battery 50, and the nickel hydride storage battery 61. In the equivalent circuit of FIG. 3, the following equation (1) holds.
Rt = Vmin / It (1)
Here, Vmin is the minimum voltage detected by the voltage detection unit 82, It is the total current value stored in the storage unit 81, and Rt is the combined value of the lead storage battery 50 and nickel hydride storage battery 61 connected in parallel. Internal resistance. The combined internal resistance Rt of the lead storage battery 50 and the nickel-metal hydride storage battery 61 connected in parallel is calculated by equation (1).

Further, in the equivalent circuit of FIG. 3, the following equation (2) holds.
1 / Rt = 1 / Rpb + 1 / Rni (2)
Here, Rpb is the internal resistance of the lead storage battery 50, and Rni is the internal resistance of the nickel-metal hydride storage battery 61.

From the above equations (1) and (2), the following equation (3) is obtained.
1 / Rpb = It / Vmin-1 / Rni (3)
The internal resistance Rpb of the lead storage battery 50 is calculated by the above equation (3).

  Returning to FIG. 1, calculation unit 83 outputs calculated internal resistance Rpb of lead storage battery 50 to determination unit 84. The determination unit 84 compares the internal resistance Rpb of the lead storage battery 50 calculated by the calculation unit 83 with the resistance threshold Rth stored in the storage unit 81 to determine whether the lead storage battery 50 has deteriorated. I do. That is, when the calculated internal resistance Rpb of the lead storage battery 50 exceeds the resistance threshold Rth, the determination unit 84 determines that the lead storage battery 50 has deteriorated. The resistance threshold value Rth is set to an appropriate value according to the specification of the lead storage battery 50 and is stored in the storage unit 81 in advance.

  When determining that lead storage battery 50 is deteriorated, determination unit 84 outputs a prohibition signal to prohibit idle stop control to ECU 70. When the determination of deterioration of lead storage battery 50 is repeated a predetermined number of times, determination unit 84 outputs a replacement signal to ECU 70 to prompt the user to replace lead storage battery 50.

  FIG. 4 is a flowchart schematically showing the operation of the battery control unit 80. First, the voltage detection unit 82 detects the voltage Vt of the power supply unit 45 and outputs it to the calculation unit 83 (S1). The calculation unit 83 determines whether the detected voltage Vt is lower than the voltage threshold Vth (S2). If the detected voltage Vt is equal to or higher than the voltage threshold Vth (NO in S2), the process returns to S1. If the detected voltage Vt is less than the voltage threshold Vth (YES in S2), the voltage detection unit 82 detects the minimum voltage Vmin of the power supply unit 45, and the calculation unit 83 calculates the minimum voltage Vmin from the voltage detection unit 82. Acquisition (S3, an example of a detection step).

  The calculation unit 83 acquires the internal resistance Rni of the nickel-metal hydride storage battery 61 from the resistance detection unit 62 of the battery pack 60 (S4, an example of an acquisition step). The calculation unit 83 uses the total current value It stored in the storage unit 81, the detected minimum voltage Vmin, and the internal resistance Rni of the nickel-metal hydride storage battery 61 obtained from the resistance detection unit 62 to obtain the above equation ( According to 3), the internal resistance Rpb of the lead storage battery 50 is calculated, and the calculated internal resistance Rpb is output to the determination unit 84 (S5, an example of a calculation step).

  The determination unit 84 determines whether the calculated internal resistance Rpb of the lead storage battery 50 exceeds the resistance threshold Rth (S6, an example of a determination step). If the internal resistance Rpb of the lead storage battery 50 does not exceed the resistance threshold Rth (NO in S6), the process returns to S1. If the internal resistance Rpb of the lead storage battery 50 exceeds the resistance threshold Rth (YES in S6), the determination unit 84 notifies the ECU 70 of a prohibition signal for prohibiting the idle stop control (S7).

  The determination unit 84 increments the count value Cdg (S8). The determination unit 84 determines whether the count value Cdg has exceeded a predetermined threshold value Cth (S9). If the count value Cdg has not exceeded the threshold value Cth (NO in S9), the process returns to S1. If count value Cdg exceeds threshold value Cth (YES in S9), ECU 70 is notified of an exchange signal for urging the user to replace lead storage battery 50 (S10).

  The ECU 70 may prompt the user to replace the lead storage battery 50 by generating a sound, displaying characters, or turning on the replacement LED.

  As described above, the battery pack 60 of the first embodiment includes the resistance detection unit 62 that detects the internal resistance Rni of the nickel-metal hydride storage battery 61 to protect the nickel-metal hydride storage battery 61. Therefore, the battery control unit 80 of the first embodiment uses the internal resistance Rni of the nickel-metal hydride storage battery 61 detected by the existing resistance detection unit 62.

  Further, the total current value It supplied from the power supply unit 45 to the starter motor 20 or the ISG 30 when the engine 10 is started depends on the specifications of the engine 10, the starter motor 20, and the ISG 30. Therefore, when the engine 10, the starter motor 20, and the ISG 30 are determined, the overall current value It is also determined.

  Therefore, the battery control unit 80 of the first embodiment calculates the internal resistance Rpb of the lead storage battery 50 using these. Therefore, the internal resistance Rpb of the lead storage battery 50 can be obtained with a simple configuration without a large current sensor or the like that detects the current flowing only in the lead storage battery 50. As a result, according to the first embodiment, it is possible to accurately determine whether or not the lead storage battery 50 has deteriorated.

  Further, in the first embodiment, the internal resistance Rpb is calculated using the minimum voltage Vmin of the power supply unit 45 when the engine 10 is started (that is, when a large current of, for example, 500 A flows). For example, when the engine 10 is stopped by the idle stop control, a current of 10 to 20 A is supplied from the power supply unit 45 to the electric load 40. In this case, since the current is small, the difference between the normal voltage of the power supply unit 45 and the minimum voltage Vmin is small. Therefore, the difference between the minimum voltage Vmin when the lead storage battery 50 is normal and the minimum voltage Vmin when the lead storage battery 50 is deteriorated is reduced.

  On the other hand, when a large current is supplied from the power supply unit 45, the difference between the normal voltage of the power supply unit 45 and the minimum voltage Vmin is large. Therefore, the difference between the minimum voltage Vmin when the lead storage battery 50 is normal and the minimum voltage Vmin when the lead storage battery 50 is deteriorated increases. As a result, according to the first embodiment, it is possible to accurately determine whether or not the lead storage battery 50 has deteriorated.

(Modification of First Embodiment)
The present invention is not limited to the first embodiment. Hereinafter, modifications of the first embodiment of the present invention will be described.

  (1) In the first embodiment, the operation unit 83 of the battery control unit 80 starts the engine 10 by the starter motor 20 or the ISG 30 depending on whether the voltage Vt of the power supply unit 45 has dropped below the voltage threshold Vth. Is determined. Alternatively, ECU 70 may be configured to notify battery control unit 80 that engine 10 has been started. In this case, the arithmetic unit 83 may acquire the minimum voltage Vmin from the voltage detection unit 82 when receiving a notification from the ECU 70 that the engine 10 has been started.

  (2) In the first embodiment, the vehicle 1 includes the battery control unit 80 separately from the ECU 70. Alternatively, the ECU 70 may be configured to include each functional block of the battery control unit 80, and the battery control unit 80 may be eliminated. In this case, the ECU 70 may acquire the minimum voltage Vmin detected by the voltage detection unit 82 when controlling the start of the engine 10.

  (3) In the first embodiment, the battery pack 60 includes the nickel-metal hydride storage battery 61. Alternatively, the battery pack 60 may include other secondary batteries such as a lithium ion secondary battery, a lithium ion polymer secondary battery, and a nickel zinc storage battery.

  (4) In the first embodiment, the starter motor 20 that starts the engine 10 by the operation of the ignition switch by the user is provided. Alternatively, the starter motor 20 may be eliminated, and the ISG 30 may start the engine 10 by operating the ignition switch by the user.

  (5) In the first embodiment, when the engine 10 is started by the starter motor 20 or the ISG 30, the ECU 70 obtains the minimum voltage Vmin of the power supply unit 45 from the voltage detection unit 82, and determines the minimum voltage Vmin in advance. If it is less than the predetermined threshold, the automatic stop of the engine 10 by the idle stop control may be prohibited. In this case, the ECU 70 may set the threshold to be different between when the engine 10 is started by the starter motor 20 and when the engine 10 is started by the ISG 30.

(History leading to inventing the second aspect according to the present disclosure)
First, a viewpoint of the second aspect according to the present disclosure will be described.

  A second aspect of the present disclosure is a charge control device and a charge control device that have a simple configuration and that both a lead storage battery and a secondary battery do not become insufficiently charged when charging a lead storage battery and a secondary battery connected in parallel to each other. The aim is to provide a method.

  In the vehicle described in Patent Literature 1, a secondary battery other than a lead storage battery and a lead storage battery are charged by electric power output from a generator (alternator). In this case, since the secondary battery other than the lead storage battery and the lead storage battery are connected in parallel with each other, when charging by the generator, it is necessary to control so that both the lead storage battery and the secondary battery do not become insufficiently charged. There is. However, in Patent Literature 1, when charging a secondary battery and a lead storage battery other than a lead storage battery connected in parallel to each other, regarding preventing both the lead storage battery and the secondary battery from being insufficiently charged, Not considered enough.

  Thus, the inventor has configured a power supply unit by connecting a lead storage battery and a secondary battery other than the lead storage battery (a nickel-metal hydride storage battery in the present embodiment) in parallel with each other, as in the technique described in Patent Document 1. did. Then, the inventor examined changes in the charging current of each battery when the power supply unit thus configured was charged at a constant voltage.

  FIG. 24 is a timing chart schematically showing a charging current when a power supply unit configured by connecting a lead storage battery and a nickel hydride storage battery in parallel to each other is charged at a constant voltage. In FIG. 24, charging current Ipb indicates a charging current flowing through a lead storage battery, charging current Ini indicates a charging current flowing through a nickel-metal hydride storage battery, and charging current It indicates a sum of charging currents Ipb and Ini.

  The charging in FIG. 24 was performed under the following conditions. As the lead storage battery, a lead storage battery having a nominal voltage of 12 V in which six lead storage batteries were connected in series was used. As the nickel-metal hydride storage battery, a nickel-metal hydride storage battery with a nominal voltage of 12 V, which is the same as a lead storage battery, was used in which 10 nickel-metal hydride storage batteries were connected in series. Charging was performed at a constant voltage of 14.5 V, assuming a generator (alternator) used for the vehicle.

  As a result, as shown in FIG. 24, it was found that Ipb> Ini during the initial period T0 (about 5 seconds) at the start of charging, but Ini> Ipb after the initial period T0. . Although not shown, it has been found that the same charging characteristics are exhibited when a lead storage battery and a lithium ion secondary battery are connected in parallel with each other.

  The present inventor has speculated that the cause is caused by a difference in charging characteristics between a lead storage battery and a nickel hydride storage battery or a lithium ion secondary battery.

  First, the inventor inferred that the following phenomenon occurred in each battery immediately after the start of charging. In the lead-acid battery of the dissolution precipitation type, when the supply of the charging current is started, the chemical reaction of the charging is immediately started between the electrode and the electrolyte on the electrode surface.

  In contrast, in a nickel-metal hydride storage battery using a hydrogen storage alloy for the negative electrode, even when the supply of charging current is started, water is reduced and the hydrogen atoms generated on the surface of the hydrogen storage alloy are stored in the hydrogen storage alloy. The reaction to metal hydride does not start immediately. Further, also in the positive electrode, it takes time for the reaction in which nickel hydroxide is oxidized to generate nickel oxyhydroxide and water to start. For this reason, in the nickel-metal hydride battery, the chemical reaction of charging is not immediately started.

  In addition, in an intercalation type lithium ion secondary battery in which an electrode is formed of a crystal having a layered structure, even when the supply of charging current is started, initially, the layers of the crystal are widened and lithium ions can easily enter the electrode. It takes time to achieve such a state. For this reason, in the lithium ion secondary battery, the chemical reaction of charging is not immediately started. Therefore, during the initial period T0 (about 5 seconds) at the beginning of charging, the charging current of the lead storage battery is larger than the charging current of the nickel hydride storage battery or the lithium ion secondary battery.

  Next, the present inferred that after the initial period T0 at the beginning of charging, the chemical reaction proceeds in each battery as follows. In a lead-acid battery, when the chemical reaction between the electrode and the electrolyte on the electrode surface has been completed, the state becomes pseudo-fully charged, and it takes time for the chemical reaction to proceed from the electrode surface to the lower layer. .

  On the other hand, in the nickel-metal hydride storage battery in which the hydrogen storage alloy once starts storing hydrogen atoms and the generation reaction of nickel oxyhydroxide and water from nickel hydroxide has started, the chemical reaction of charging proceeds smoothly. In addition, in the lithium ion secondary battery once in a state where lithium ions can easily enter the electrode, the chemical reaction of charging proceeds smoothly. Therefore, after the initial period T0 at the beginning of charging, the charging current of the nickel-metal hydride storage battery or the lithium-ion secondary battery becomes larger than the charging current of the lead storage battery.

  Here, charging control for the nickel-metal hydride storage battery mounted on the vehicle will be described. If the state of charge (SOC) of the nickel-metal hydride storage battery is too high, the regenerative energy of the engine cannot be stored, so that the energy efficiency is rather lowered. On the other hand, when the SOC of the nickel-metal hydride storage battery is too low, supply of a large current required at the time of starting the engine or restarting the stopped engine under idle stop control is hindered.

  For this reason, in general, in a nickel-metal hydride storage battery mounted on a vehicle, an upper limit (for example, 80%) and a lower limit (for example, 20%) of the SOC are set. Charge and discharge of the nickel-metal hydride storage battery are controlled such that the SOC of the nickel-metal hydride storage battery is maintained within this range. Therefore, when the SOC of the nickel-metal hydride storage battery reaches the upper limit value during charging, charging is stopped. In this case, the nickel-metal hydride storage battery mounted on the vehicle is set to have a smaller capacity than the lead storage battery. For this reason, the SOC of the nickel-metal hydride storage battery greatly fluctuates as compared with the SOC of the lead storage battery even for the same amount of charged electricity. As a result, the SOC of the nickel-metal hydride storage battery reaches the upper limit relatively quickly.

  Therefore, if the normal constant-voltage charging is simply performed, the charging proceeds with the charging current as shown in FIG. 24. Therefore, before the lead storage battery is fully charged, the SOC of the nickel-metal hydride storage battery reaches the upper limit. Charging will be stopped. As a result, if the charge control is not devised, the lead storage battery will be in a state of insufficient charge, not being fully charged.

  On the other hand, it is conceivable to configure the charge control circuit of the power supply unit so that the lead storage battery and the nickel hydride storage battery can be charged separately. With this configuration, charging can be controlled so that both the lead storage battery and the nickel hydride storage battery do not become insufficiently charged. However, in the charge control circuit configured as described above, the circuit configuration becomes complicated and large, which causes an increase in cost and installation space.

  Therefore, the present inventor has arrived at the invention of each aspect included in the second aspect according to the present disclosure as described below based on the above examination.

  According to a second aspect of the present disclosure, a power supply unit including a lead storage battery and a secondary battery other than the lead storage battery connected in parallel to each other, and the power supply unit is connected to the power supply unit by constant voltage charging at a predetermined voltage value. A charge control unit that charges the lead storage battery and the secondary battery, wherein the predetermined voltage value is an initial period at the beginning of charging at the predetermined voltage value. The charging current increases and after the initial period, the charging current of the secondary battery is set to a value larger than the charging current of the lead storage battery.

  In this aspect, the lead storage battery and the secondary battery of the power supply unit including the lead storage battery and the secondary battery other than the lead storage battery connected in parallel with each other are charged by constant voltage charging at a predetermined voltage value. The predetermined voltage value is set in advance to a value in which the charging current of the lead storage battery is larger than the charging current of the secondary battery during the initial period at the beginning of charging at the predetermined voltage value. For this reason, insufficient charging of the lead storage battery is avoided. After the initial period, the charging current of the secondary battery is larger than the charging current of the lead storage battery. For this reason, insufficient charging of the secondary battery is avoided. As a result, according to this aspect, with a simple configuration, it is possible to prevent both the lead storage battery and the secondary battery from being insufficiently charged.

  In the second aspect, a first SOC acquisition unit for acquiring the SOC of the lead storage battery, a storage unit for storing an SOC threshold value of 100% or less which is predetermined as the SOC of the lead storage battery, A voltage adjustment unit that adjusts the voltage or a predetermined low voltage value lower than the predetermined voltage value, wherein the charging control unit controls the voltage adjustment unit to obtain the lead obtained by the first SOC obtaining unit. Until the SOC of the storage battery reaches the SOC threshold, the charging voltage is adjusted to the predetermined low voltage value. After the SOC of the lead storage battery reaches the SOC threshold, the charging voltage is adjusted to the predetermined voltage value. The two-stage constant voltage charging charges the lead storage battery and the secondary battery of the power supply unit, and the predetermined low voltage value is such that the charging current of the lead storage battery is larger than the charging current of the secondary battery. It may be determined in advance to become a value.

  In this aspect, until the SOC of the lead storage battery reaches the SOC threshold, the lead storage battery and the secondary battery are charged at a constant voltage at a predetermined low voltage value. The predetermined low voltage value is set in advance to a value at which the charging current of the lead storage battery is larger than the charging current of the secondary battery. For this reason, until the SOC of the lead storage battery reaches the SOC threshold, charging of the lead storage battery proceeds faster than that of the secondary battery. Therefore, according to this aspect, it is possible to avoid a shortage of charge such that the SOC of the lead storage battery becomes less than the SOC threshold.

  Further, in this aspect, after the SOC of the lead storage battery reaches the SOC threshold, the lead storage battery and the secondary battery are charged at a predetermined voltage at a constant voltage. The predetermined voltage value is such that during the initial period at the beginning of charging at the predetermined voltage value, the charging current of the lead storage battery becomes larger than the charging current of the secondary battery, and after the initial period, the charging current of the lead storage battery becomes smaller than the charging current of the lead storage battery. It is predetermined to a value at which the charging current of the battery increases. For this reason, after the SOC of the lead storage battery reaches the SOC threshold, charging of the secondary battery proceeds faster than that of the lead storage battery. Therefore, according to this aspect, it is possible to prevent the secondary battery from being insufficiently charged. As a result, according to this aspect, with a simple configuration, it is possible to prevent both the lead storage battery and the secondary battery from being insufficiently charged.

  In the second aspect, for example, the apparatus further includes a second SOC acquisition unit that acquires the SOC of the secondary battery, and the storage unit stores the first SOC upper limit of less than 100% that is predetermined as the SOC of the secondary battery. And the charging control unit may stop the two-step constant-voltage charging when the SOC of the secondary battery acquired by the second SOC acquiring unit reaches the first SOC upper limit value.

  According to this aspect, when the SOC of the secondary battery reaches the predetermined first SOC upper limit of less than 100%, the two-stage constant voltage charging is stopped. Therefore, it is possible to prevent the secondary battery from being overcharged.

  In the second aspect, for example, the charging control unit may set the SOC threshold to a larger value as the SOC of the secondary battery at the start of charging acquired by the second SOC acquiring unit is larger.

  In this aspect, charging is stopped when the SOC of the secondary battery reaches the first SOC upper limit of less than 100%. Therefore, the longer the SOC of the secondary battery at the start of charging, the shorter the time of constant voltage charging at the second voltage value. Therefore, as the SOC of the secondary battery at the start of charging is larger, the possibility that the lead storage battery will be insufficiently charged increases. On the other hand, according to the present aspect, the SOC threshold value is set to a larger value as the SOC of the secondary battery at the start of charging is larger. Therefore, the time of the constant voltage charging at the first voltage value becomes longer. As a result, the possibility that the lead storage battery becomes insufficiently charged can be reduced.

  In the second aspect, for example, the storage unit stores a second SOC upper limit value exceeding 100%, which is predetermined as the SOC of the lead storage battery, and the charge control unit determines that the SOC of the lead storage battery is the second SOC upper limit value. When the 2 SOC upper limit is reached, the two-stage constant voltage charging may be stopped.

  In this aspect, when the SOC of the lead storage battery reaches the second SOC upper limit exceeding 100%, the two-stage constant voltage charging is stopped. Therefore, when charging is continued until the SOC of the lead storage battery reaches the second SOC upper limit, it is possible to suppress excessive sulfation occurring in the lead storage battery due to insufficient charging.

  In the second aspect, for example, the storage unit stores an SOC lower limit value that is less than the SOC threshold value that is predetermined as an SOC of the lead storage battery, and the charging control unit determines that the SOC of the lead storage battery is equal to the SOC. When the number falls below the lower limit, the number of times of the decrease is counted, and the number of times counted is counted at a predetermined number of times, and the lead-acid battery and the secondary battery of the power supply unit are charged by the two-stage constant-voltage charging, and the counting is performed. If the number of times performed is less than the predetermined number of times, the charging voltage may be adjusted to the second voltage value, and the lead storage battery and the secondary battery of the power supply unit may be charged at a constant voltage.

  In this aspect, when the SOC of the lead storage battery falls below the SOC lower limit, the number of times the lead storage battery has fallen is counted. Each time the predetermined number of times is counted, each battery of the power supply unit is charged by two-stage constant voltage charging. Therefore, when charging is continued until the SOC of the lead storage battery reaches the second SOC upper limit, it is possible to suppress excessive sulfation occurring in the lead storage battery due to insufficient charging.

  On the other hand, when the counted number is less than the predetermined number, the charging voltage is adjusted to the second voltage value, and each battery of the power supply unit is charged by the constant voltage charging at the second voltage value. For this reason, overcharging such that the SOC of the lead storage battery reaches the second SOC upper limit value is performed every predetermined number of times, and is not performed when the number is less than the predetermined number of times. As a result, the lead storage battery can be prevented from being excessively deteriorated due to overcharging.

  In the second aspect, for example, in the two-stage constant-voltage charging, when the SOC of the lead storage battery reaches the SOC threshold and adjusts the charging voltage to the second voltage value, The lead storage battery and the secondary battery of the unit may be pulse-charged so that the ON period is shorter than the initial period.

  In this aspect, when the SOC of the lead storage battery reaches the SOC threshold and the charging voltage is adjusted to the second voltage value, each battery of the power supply unit is pulse-charged with the ON period of the initial period or less. Since the ON period is shorter than the initial period, the charge current of the lead storage battery is larger than the charge current of the secondary battery during the ON period. Therefore, although the charging voltage is adjusted to the second voltage value, the charging of the lead storage battery proceeds faster in the pulse charging than in the secondary battery. As a result, the lead storage battery can be prevented from being insufficiently charged.

  In the second aspect, a secondary battery SOC obtaining unit that obtains the SOC of the secondary battery, a storage unit that stores a first SOC upper limit of less than 100% that is predetermined as the SOC of the secondary battery, And wherein the charging control unit is configured to perform the constant voltage charging at the predetermined voltage value while the SOC of the secondary battery acquired by the secondary battery SOC acquiring unit is less than the first SOC upper limit value. When the SOC of the secondary battery obtained by the secondary battery SOC obtaining unit is equal to or more than the first SOC upper limit, the lead storage battery and the secondary battery of the unit are charged. The charging may be switched to pulse charging in which the ON period and the OFF period are alternately repeated.

  In this aspect, while the SOC of the secondary battery is less than the first SOC upper limit, the lead storage battery and the secondary battery are charged at a constant voltage at a predetermined voltage value. The predetermined voltage value is such that during the initial period at the beginning of charging at the predetermined voltage value, the charging current of the lead storage battery becomes larger than the charging current of the secondary battery, and after the initial period, the charging current of the lead storage battery becomes smaller than the charging current of the lead storage battery. It is set to a value at which the charging current of the battery increases. Therefore, in the constant voltage charging, the charging of the secondary battery proceeds faster than in the lead storage battery. Therefore, according to this aspect, it is possible to prevent the secondary battery from being insufficiently charged.

  Further, in this aspect, when the SOC of the secondary battery becomes equal to or higher than the first SOC upper limit value, the charging is switched to the pulse charging in which a predetermined ON period and OFF period are alternately repeated. In pulse charging, the charging current of the lead storage battery is larger than the charging current of the secondary battery. For this reason, the charging of the lead storage battery proceeds faster than the secondary battery. Therefore, according to this aspect, it is possible to prevent the lead storage battery from being insufficiently charged. As a result, according to this aspect, with a simple configuration, it is possible to prevent both the lead storage battery and the secondary battery from being insufficiently charged.

  In the second aspect, for example, the charge control unit may set the ON period in advance to a length equal to or less than the initial period.

  In this embodiment, the ON period is set to a length equal to or shorter than the initial period. Therefore, during the ON period, the charging current of the lead storage battery is larger than the charging current of the secondary battery. Therefore, in the pulse charging, the charging of the lead storage battery proceeds faster than that of the secondary battery. Therefore, according to this aspect, it is possible to prevent the lead storage battery from being insufficiently charged.

  In the second aspect, for example, the storage unit stores a predetermined SOC protection threshold value as a SOC of the secondary battery, which is less than 100% and exceeds the first SOC upper limit value, and The control unit may stop the pulse charging when the SOC of the secondary battery acquired by the secondary battery SOC acquisition unit becomes equal to or greater than the SOC protection threshold during the pulse charging.

  In pulse charging, charging of a lead storage battery proceeds faster than that of a secondary battery, but charging of the secondary battery also proceeds more slowly than that of a lead storage battery. However, according to the present aspect, when the SOC of the secondary battery is less than 100% and exceeds the first SOC upper limit value or more during the pulse charging, the pulse charging is stopped. You. Therefore, it is possible to prevent the SOC of the secondary battery from becoming excessive.

  In the second aspect, for example, the storage unit stores a first SOC lower limit value that is less than the first SOC upper limit value as an SOC of the secondary battery, and the charging control unit performs the pulse charging during the pulse charging. Alternatively, when the SOC of the secondary battery obtained by the secondary battery SOC obtaining unit becomes less than the first SOC lower limit, the pulse charging may be switched to the constant voltage charging.

  In the present aspect, when the SOC of the secondary battery becomes less than the first SOC lower limit predetermined below the first SOC upper limit during pulse charging, the pulse charging is switched to constant voltage charging. In the constant voltage charging, the charging of the secondary battery proceeds faster than that of the lead storage battery. Therefore, according to this aspect, it is possible to prevent the SOC of the secondary battery from being maintained below the first SOC lower limit.

  In the second aspect, for example, the apparatus further includes a lead storage battery SOC obtaining unit that obtains the SOC of the lead storage battery, wherein the storage unit sets a second SOC upper limit predetermined to 100% or more as the SOC of the lead storage battery. The charge control unit may save the pulse charging when the SOC of the lead storage battery obtained by the lead storage battery SOC obtaining unit becomes equal to or more than the second SOC upper limit value during the pulse charging.

  In this aspect, during the pulse charging, when the SOC of the lead storage battery becomes equal to or more than the second SOC upper limit value that is predetermined to be 100% or more, the pulse charging is stopped. Therefore, even if the SOC of the lead storage battery becomes equal to or more than the second SOC upper limit value, charging is continued, and it is possible to prevent the lead storage battery from being overcharged.

  In the second aspect, for example, the storage unit stores 100% and a value exceeding 100% as the second SOC upper limit value, and sets the SOC of the lead storage battery to a value less than 100% in advance. When the SOC of the lead storage battery falls below the second SOC lower limit, the charge controller starts counting the number of times the battery has dropped and starts the constant voltage charging. For each count, a value exceeding 100% may be used as the second SOC upper limit value, and if the counted number is less than the predetermined number, 100% may be used as the second SOC upper limit value.

  In this aspect, when the SOC of the lead storage battery drops below the SOC lower limit, the number of times the lead storage battery has dropped is counted and constant voltage charging is started. A value exceeding 100% is used as the second SOC upper limit every time the number of times of counting is increased a predetermined number of times. Therefore, when charging is continued until the SOC of the lead storage battery becomes equal to or more than the second SOC upper limit, it is possible to suppress excessive sulfation occurring in the lead storage battery due to insufficient charging.

  On the other hand, if the counted number is less than the predetermined number, 100% is used as the second SOC upper limit. For this reason, overcharging such that the SOC of the lead storage battery exceeds 100% is performed every predetermined number of times, and is not performed when the SOC is less than the predetermined number of times. As a result, the lead storage battery can be prevented from being excessively deteriorated due to overcharging.

  Another aspect according to the present disclosure includes a power supply unit including a lead storage battery and a secondary battery other than the lead storage battery connected in parallel to each other, and charging for controlling charging of the lead storage battery and the secondary battery of the power supply unit. A charging control method of the control device, comprising a predetermined voltage charging step of performing a constant voltage charging of the lead storage battery and the secondary battery of the power supply unit at a predetermined voltage value, wherein the predetermined voltage value is During the initial period at the beginning of charging at the predetermined voltage value, the charging current of the lead storage battery is larger than the charging current of the secondary battery, and after the initial period, the charging current of the lead storage battery is smaller than the charging current of the lead storage battery. It is set in advance to a value at which the charging current of the secondary battery increases.

  In the above other aspect, a lead storage battery SOC obtaining step of obtaining the SOC of the lead storage battery, and a predetermined low voltage lower than the predetermined voltage value until the SOC of the lead storage battery reaches a predetermined SOC threshold of 100% or less. A low-voltage charging step of charging the lead storage battery and the secondary battery of the power supply unit at a constant voltage at a voltage value, wherein the predetermined voltage charging step is such that the SOC of the lead storage battery has reached the SOC threshold. The predetermined low voltage value that is executed later may be set in advance to a value at which the charging current of the lead storage battery is larger than the charging current of the secondary battery.

  In the above other aspect, a secondary battery SOC obtaining step for obtaining the SOC of the secondary battery, and a secondary battery SOC of which the secondary battery SOC obtained in the secondary battery SOC obtaining step is less than a predetermined 100%. A pulse charging step of charging the lead storage battery and the secondary battery of the power supply unit by pulse charging that repeats a predetermined on-period and an off-period when the SOC is equal to or more than the upper limit of 1 SOC, and the predetermined voltage charging step May be executed while the SOC of the secondary battery acquired in the secondary battery SOC acquiring step is less than the first SOC upper limit value.

(2nd Embodiment)
FIG. 6 is a block diagram schematically illustrating a configuration of the vehicle 1 including the battery control unit 180 and the ECU 70 according to the second embodiment.

  The vehicle 1 is a hybrid electric vehicle that uses an engine as a main power source and a motor as an auxiliary power source. The vehicle 1 includes an engine 10, a starter motor 20, an integrated starter generator (ISG) 30, a voltage adjusting unit 31, a switch element 35, an electric load 40, a power supply unit 45, an electronic control unit (ECU) 70, and a battery control unit 180. .

  The power supply unit 45 includes a lead storage battery 50, current sensors 51 and 63, and a nickel hydride storage battery (Ni-MH) 61. The lead storage battery 50 and the nickel hydride storage battery 61 are connected in parallel with each other. The connection point K2 on the negative electrode side of the lead storage battery 50 and the nickel hydride storage battery 61 is grounded. The starter motor 20, the ISG 30, and the electrical load 40 are connected in parallel with the power supply unit 45. A power supply voltage Vcc is supplied from the power supply unit 45 to the battery control unit 180 and the ECU 70.

  Lead storage battery 50 includes a six-cell lead storage battery connected in series. With this configuration, the nominal voltage of the lead storage battery 50 is 12V. Nickel-metal hydride storage battery 61 includes a 10-cell nickel-metal hydride storage battery connected in series. With this configuration, the nominal voltage of the nickel-metal hydride storage battery 61 is 12V. The power output from the power supply unit 45 is used for driving the starter motor 20 and the ISG 30 for starting the engine 10 of the vehicle 1 and for powering the electrical load 40.

  Current sensor 51 detects a charging current or a discharging current flowing through lead storage battery 50. The current sensor 51 is mounted on a branch line L1 branched from a connection point K1 on the positive electrode side of the lead storage battery 50 and the nickel hydride storage battery 61. The current sensor 51 is provided to calculate the amount of charge and the amount of discharge of the lead storage battery 50.

  Current sensor 63 detects a charging current or a discharging current flowing through nickel-metal hydride storage battery 61. The current sensor 63 is attached on a branch line L2 branched from a connection point K1 on the positive electrode side of the lead storage battery 50 and the nickel hydride storage battery 61. The current sensor 63 is provided for calculating the amount of charge and the amount of discharge of the nickel-metal hydride storage battery 61.

  The current sensors 51 and 63 are, for example, Hall effect type current sensors including a Hall element. Alternatively, the current sensors 51 and 63 may include a shunt resistor and detect a current based on a voltage drop of the shunt resistor.

  The starter motor 20 starts the engine 10 when a user operates an ignition switch.

  The ISG 30 has both a power generation function and an electric function. When the engine 10 of the vehicle 1 is operating, the ISG 30 is driven by the engine 10 and generates power by a power generation function. When the generated electric power exceeds the electric load of the electrical load 40, the generated electric power charges the lead storage battery 50 and the nickel hydride storage battery 61 of the power supply unit 45. Further, when the brake pedal (not shown) is operated to start deceleration while the vehicle 1 is traveling, torque is transmitted from the wheels to the ISG 30, and the ISG 30 generates power by the power generation function. The generated electric power charges the lead storage battery 50 and the nickel hydride storage battery 61 of the power supply unit 45. As a result, energy is regenerated. When the vehicle 1 stops, the engine 10 automatically stops by the idle stop control of the ECU 70. When the vehicle 1 starts, the vehicle 1 is driven by the electric function of the ISG 30 and the engine 10 is started.

  The voltage adjuster 31 adjusts the output voltage of the ISG 30. The output voltage by the power generation function of the ISG 30 changes depending on the rotation speed of the engine 10, the current value of the load current, and the field current without being adjusted. The voltage adjuster 31 adjusts the output voltage of the ISG 30 to a constant value, for example, by increasing or decreasing the field current. The voltage adjustment unit 31 includes, for example, a semiconductor circuit in which a power transistor and a voltage detection circuit are integrated. In the second embodiment, the voltage adjusting unit 31 adjusts the output voltage of the ISG 30 in two stages, for example, DC 13.7 V (an example of a first voltage value) and DC 15.0 V (an example of a second voltage value). I do.

  The switch element 35 is provided between the ISG 30 and the power supply unit 45. The switch element 35 is turned on when the engine 10 is stopped. The switch element 35 is turned off when charging of the lead storage battery 50 and the nickel hydride storage battery 61 is stopped. ON / OFF of the switch element 35 is controlled by the battery control unit 180. The switch element 35 may be a mechanical relay. Alternatively, the switch element 35 may be a semiconductor switch such as a power MOSFET or an insulated gate bipolar transistor. The electric load 40 includes loads of electric components and the like mounted on the vehicle 1 such as an air conditioner and a room light.

  The ECU 70 includes, for example, a CPU (Central Processing Unit) that executes predetermined arithmetic processing, a ROM (Read Only Memory) in which a predetermined control program is stored, and a RAM (Random Access Memory) in which data is temporarily stored. Peripheral circuits are provided. The ECU 70 is configured to be able to communicate with the battery control unit 180.

  The ECU 70 controls the entire operation of the vehicle 1 including the engine 10, the starter motor 20, the ISG 30, the voltage adjustment unit 31, and the electric load 40. ECU 70 receives control signal SG output from battery control unit 180 and controls voltage adjustment unit 31.

  The battery control unit 180 includes, for example, a CPU that executes predetermined arithmetic processing, a ROM in which a predetermined control program is stored, a RAM in which data is temporarily stored, and peripheral circuits thereof. The battery control unit 180 includes a storage unit 181 configured by, for example, a flash memory. The battery control unit 180 functions as a first SOC calculation unit 182, a second SOC calculation unit 183, a voltage control unit 184, and a switch control unit 185 by executing a control program stored in the ROM.

  The storage unit 181 stores in advance a table 88 indicating the relationship between the SOC threshold Spb1 of 100% or less, which is predetermined as the SOC of the lead storage battery 50, and the SOC value Sni1 of the nickel-metal hydride storage battery 61 at the start of charging.

  FIG. 7 is a diagram schematically showing an example of the table 88. In the second embodiment, as shown in FIG. 7, when the SOC value Sn1 of the nickel-metal hydride storage battery 61 at the start of charging is Sn1 <30, the SOC threshold Spb1 is 97, and 30 ≦ Sni1 <40. In the case of, the SOC threshold Spb1 is set to 98, when 40 ≦ Sni1 <50, the SOC threshold Spb1 is set to 99, and when 50 ≦ Sni1, the SOC threshold Spb1 is set to 100. As shown in FIG. 7, as the SOC value Sni1 of the nickel-metal hydride storage battery 61 at the start of charging is larger, the SOC threshold Spb1 of the lead storage battery 50 is set to a larger value. The reason will be described later with reference to FIG.

  Returning to FIG. 6, storage unit 181 stores a predetermined SOC upper limit value Sni2 (an example of a first SOC upper limit value) as an upper limit value of the SOC of nickel-metal hydride storage battery 61 and a predetermined lower SOC limit value Sni3 of the SOC. Are stored in advance. In the second embodiment, for example, Sni2 = 80% and Sni3 = 20%.

  Storage unit 181 stores in advance an SOC upper limit Spb2 (an example of a second SOC upper limit) exceeding 100%, which is a predetermined upper limit of the SOC of lead storage battery 50. In the second embodiment, for example, Spb2 = 105%.

  Storage unit 181 stores in advance an SOC lower limit value Spb3 which is a predetermined lower limit value of the SOC of lead storage battery 50. SOC lower limit value Spb3 is set, for example, to less than SOC threshold value Spb1. In the second embodiment, for example, Spb3 = 80%.

  Battery control unit 180 controls charging and discharging of nickel-metal hydride storage battery 61 such that the SOC of nickel-metal hydride storage battery 61 is maintained within the range between SOC upper limit value Sni2 and SOC lower limit value Sni3. Battery control unit 180 controls charging and discharging of lead storage battery 50 such that the SOC of lead storage battery 50 is maintained at or above SOC lower limit Spb3.

  First SOC calculating section 182 calculates the amount of charge and the amount of discharge of lead storage battery 50 using the current value detected by current sensor 51. The first SOC calculation unit 182 calculates the SOC of the lead storage battery 50 using the calculated charge amount and discharge amount of the lead storage battery 50. The first SOC calculation unit 182 calculates the SOC, for example, every 100 msec. The first SOC calculation section 182 and the current sensor 51 correspond to an example of a first SOC acquisition section.

  The second SOC calculating unit 183 calculates the amount of charge and the amount of discharge of the nickel-metal hydride storage battery 61 using the current value detected by the current sensor 63. The second SOC calculation unit 183 calculates the SOC of the nickel-metal hydride storage battery 61 by using the calculated charge amount and discharge amount of the nickel-metal hydride storage battery 61. The second SOC calculation unit 183 calculates the SOC, for example, every 100 msec. The second SOC calculation unit 183 and the current sensor 63 correspond to an example of a second SOC acquisition unit.

  Voltage control section 184 outputs control signal SG to ECU 70 to control the charging voltage during charging of lead storage battery 50 and nickel-metal hydride storage battery 61. Voltage controller 184 obtains the SOC of lead storage battery 50 from first SOC calculator 182. Voltage control unit 184 outputs control signal SG to ECU 70 so as to control the charging voltage to 13.7 V until the acquired SOC of lead storage battery 50 reaches SOC threshold Spb1. When the control signal SG is input, the ECU 70 controls the voltage adjustment unit 31 to set the output voltage of the ISG 30 to 13.7V.

  Voltage control unit 184 outputs control signal SG to ECU 70 so that the charging voltage is controlled to 15.0 V after the SOC of lead storage battery 50 calculated by first SOC calculation unit 182 reaches SOC threshold value Spb1. . When the control signal SG is input, the ECU 70 controls the voltage adjusting unit 31 to set the output voltage of the ISG 30 to 15.0V. Thus, voltage control unit 184 and ECU 70 charge lead storage battery 50 and nickel-metal hydride storage battery 61 by two-stage constant voltage charging.

  FIG. 8 is a timing chart schematically showing a charging current when the power supply unit 45 of FIG. 6 is charged at a constant voltage of 13.7 V.

  In FIG. 8, unlike FIG. 24, the charging current Ini of the nickel-metal hydride storage battery 61 does not exceed the charging current Ipb of the lead storage battery 50. The cause is inferred as follows. In the lead-acid battery 50 of the dissolution precipitation type, the charging chemical reaction proceeds at a low speed even at a voltage of 13.7 V. However, in the nickel-metal hydride storage battery 61, since the voltage is too low at 13.7V, the hydrogen storage alloy does not enter a state in which hydrogen can be easily stored, so that the chemical reaction for charging hardly proceeds. Therefore, when the power supply unit 45 in FIG. 6 is charged at a constant voltage of 13.7 V, the charging current Ipb of the lead storage battery 50 becomes larger than the charging current Ini of the nickel hydride storage battery 61.

  As can be seen from a comparison between FIG. 8 and FIG. 24, the overall charging current It is about half that of FIG. 24 in FIG. Therefore, it takes time to charge the lead storage battery 50 and the nickel hydride storage battery 61. However, by adjusting the output voltage of the ISG 30 to 13.7 V, the charging of the lead storage battery 50 can proceed more quickly than the nickel-metal hydride storage battery 61.

  Returning to FIG. 6, voltage control unit 184 determines SOC threshold value Spb1 using SOC of nickel-metal hydride storage battery 61 at the time when supply of charging current from ISG 30 is started, and table 88 shown in FIG. .

  Voltage control section 184 counts the number of times that the SOC of lead storage battery 50 calculated by first SOC calculation section 182 has fallen below SOC lower limit value Spb3. The voltage control unit 184 performs the two-stage constant voltage control every time the count value becomes N (for example, N = 5 in the second embodiment). When the count value is 1 to (N-1) times, that is, when the count value is less than N times, the voltage control unit 184 does not perform the two-step constant voltage control, but changes the output voltage of the ISG 30 to 15. Normal constant voltage charging is performed by controlling the voltage to 0V.

  The switch control unit 185 controls on / off of the switch element 35. The switch control unit 185 turns on the switch element 35 when the engine 10 is stopped. When the SOC of nickel-metal hydride storage battery 61 calculated by second SOC calculating section 183 increases to or above SOC upper limit value Sni2 during charging, switch control section 185 turns off switch element 35 and stops charging.

  When the SOC of lead storage battery 50 calculated by first SOC calculating section 182 increases to or above SOC upper limit value Spb2 during charging, switch control section 185 turns off switch element 35 and stops charging.

  FIG. 9 is a flowchart schematically showing the charging operation of the second embodiment. FIG. 10 is a diagram schematically showing an example of the SOC of the lead storage battery 50 and the nickel-metal hydride storage battery 61 which are increased by the charging operation of FIG. The vertical axis in FIG. 10 represents the SOC of the lead storage battery 50, and the horizontal axis represents the SOC of the nickel-metal hydride storage battery 61. In FIG. 10, charging periods Tch1 and Tch11 represent periods during which constant-voltage charging at 13.7 V is performed, and charging periods Tch2 and Tch12 represent periods during which constant-voltage charging at 15.0 V is performed.

  In the second embodiment, the SOCs of the lead storage battery 50 and the nickel-metal hydride storage battery 61 change as represented by the charging periods Tch1 and Tch2. The SOCs of the lead storage battery 50 and the nickel-metal hydride storage battery 61 represented by the charging periods Tch11 and Tch12 represent comparative examples described later. In the normal state (that is, when the operation in FIG. 9 is started), the switch element 35 is turned on.

  In S101 of FIG. 9 (an example of a lead storage battery SOC obtaining step), first, the voltage control unit 184 obtains the SOC value of the lead storage battery 50 from the first SOC calculation unit 182. Voltage control unit 184 determines whether or not the acquired SOC value of lead storage battery 50 is less than SOC lower limit value Spb3. If the SOC value of lead storage battery 50 is less than SOC lower limit value Spb3 (YES in S101), in S102, voltage control unit 184 increases count value Ct by one.

  In S103, the voltage control unit 184 determines whether the count value Ct is smaller than N (N = 5 in the second embodiment). If the count value Ct is equal to or larger than N (NO in S103), in S104, the voltage control unit 184 resets the count value Ct to 0. In S105, voltage control unit 184 acquires SOC value Sni1 of nickel-metal hydride storage battery 61 from second SOC calculation unit 183. Voltage control unit 184 refers to table 88 to extract SOC threshold value Spb1 of lead storage battery 50 corresponding to acquired SOC value Sni1 of nickel-metal hydride storage battery 61.

  In S106 (an example of the low-voltage charging step), the voltage control unit 184 outputs a control signal SG requesting that the output voltage of the ISG 30 be adjusted to 13.7 V to the ECU 70. When receiving the control signal SG, the ECU 70 controls the voltage adjusting unit 31 to adjust the output voltage of the ISG 30 to 13.7V. Thus, the lead storage battery 50 and the nickel hydride storage battery 61 of the power supply unit 45 are charged at a constant voltage of 13.7V.

  In S107, voltage control unit 184 acquires the SOC value of lead storage battery 50 from first SOC calculation unit 182. Voltage control unit 184 determines whether or not the obtained SOC value of lead storage battery 50 is equal to or greater than SOC threshold value Spb1. If the SOC value of lead storage battery 50 is less than SOC threshold value Spb1 (NO in S107), the process returns to S107, and constant voltage charging at 13.7 V is continued.

  As described with reference to FIG. 8, when the voltage is 13.7 V, the charging current of the lead storage battery 50 is larger than the charging current of the nickel hydride storage battery 61. Therefore, as shown in FIG. 10, in the charging period Tch1, the SOC of the lead storage battery 50 increases faster than the SOC of the nickel-metal hydride storage battery 61. In FIG. 10, the SOC value Sni1 of the nickel-metal hydride storage battery 61 obtained in S5 of FIG. 9 satisfies 20 ≦ Sni1 <30. For this reason, the SOC threshold Spb1 extracted from the table 88 (FIG. 7) in S5 of FIG. 9 is 97 as shown in FIG.

  Returning to FIG. 9, if the SOC value of lead storage battery 50 is equal to or greater than SOC threshold Spb1 in S107 (an example of a lead storage battery SOC acquisition step) (YES in S107), voltage control unit 184 proceeds to S108 (predetermined voltage charging). In one example of the step), a control signal SG requesting that the output voltage of the ISG 30 be adjusted to 15.0 V is output to the ECU 70. When receiving the control signal SG, the ECU 70 controls the voltage adjusting unit 31 to adjust the output voltage of the ISG 30 to 15.0V. As a result, the lead storage battery 50 and the nickel hydride storage battery 61 of the power supply unit 45 are charged at a constant voltage of 15.0V.

  As described with reference to FIG. 24, when the voltage is 15.0 V, the charge current of the nickel-metal hydride storage battery 61 is larger than the charge current of the lead storage battery 50 except for the initial period T0 at the start of charging. Therefore, as shown in FIG. 10, in the charging period Tch2, the SOC of the nickel-metal hydride storage battery 61 increases faster than the SOC of the lead storage battery 50.

  Returning to FIG. 9, in S109, the switch control unit 185 acquires the SOC value of the nickel-metal hydride storage battery 61 from the second SOC calculation unit 183. Switch control unit 185 determines whether or not the obtained SOC value of nickel-metal hydride storage battery 61 is equal to or greater than SOC upper limit value Sni2. If the SOC value of nickel-metal hydride storage battery 61 is less than SOC upper limit value Sni2 (NO in S109), switch control unit 185 acquires the SOC value of lead storage battery 50 from first SOC calculation unit 182 in S110. Switch control unit 185 determines whether or not the SOC value of lead storage battery 50 is equal to or greater than SOC upper limit value Spb2. If the SOC value of lead storage battery 50 is less than SOC upper limit value Spb2 (NO in S110), the process returns to S109, and constant voltage charging at 15.0 V is continued.

  In S109, if the SOC value of the nickel-metal hydride storage battery 61 is equal to or more than the SOC upper limit value Sni2 (YES in S109), in S110, the switch control unit 185 turns off the switch element 35 to stop charging, and the charging in FIG. The process ends. In S110, if the SOC value of lead storage battery 50 is equal to or greater than SOC upper limit value Spb2 (YES in S110), the process proceeds to S111.

  In S101, if the SOC value of lead storage battery 50 is equal to or more than SOC lower limit value Spb3 (NO in S101), in S112, voltage control unit 184 acquires the SOC value of nickel-metal hydride storage battery 61 from second SOC calculation unit 183. . Voltage controller 184 determines whether or not the obtained SOC value of nickel-metal hydride storage battery 61 is less than SOC upper limit value Sni2. If the SOC value of nickel-metal hydride storage battery 61 is equal to or greater than SOC upper limit value Sni2 (NO in S112), the process proceeds to S11.

  In S112, if the SOC value of nickel-metal hydride storage battery 61 is less than SOC upper limit value Sni2 (YES in S112), the process proceeds to S108. If the count value Ct is smaller than N in S103 (YES in S103), the process proceeds to S108. As a result, in S108, normal constant voltage charging at 15.0 V is performed.

  As shown in S109 and S110 in FIG. 9, when either the SOC value of the nickel-metal hydride storage battery 61 or the SOC value of the lead-acid storage battery 50 increases beyond the SOC upper limit value, the switch element 35 is turned off, and charging is stopped. Is done. In the example of FIG. 10, the charging is stopped when the SOC value of the nickel-metal hydride storage battery 61 reaches the SOC upper limit value Sni2.

  In this manner, every time the SOC value of the lead storage battery 50 decreases N times or less to the SOC lower limit value Spb3 or less, the charge includes the constant voltage charge at the voltage of 13.7V and the constant voltage charge at the voltage of 15.0V2. Step constant voltage charging is performed. When the SOC value of the lead storage battery 50 exceeds the SOC lower limit value Spb3, and when the SOC value of the lead storage battery 50 decreases to the SOC lower limit value Spb3 or less up to (N-1) times, Is performed at 15.0 V for normal constant voltage charging.

  According to the second embodiment, as shown in FIG. 10, overcharging is performed when the SOC value of the lead storage battery 50 exceeds 100%. As a result, it is possible to suppress excessive sulfation occurring in the undercharged lead storage battery 50. Overcharging is not performed every time the SOC value of the lead storage battery 50 falls below the SOC lower limit Spb3, but rather, the SOC value of the lead storage battery 50 falls below the SOC lower limit Spb3 N (this In the second embodiment, the process is performed, for example, every N = 5) times. Therefore, the lead storage battery 50 is not excessively deteriorated due to overcharging.

  As shown in FIG. 7, as the SOC value Sni1 of the nickel-metal hydride storage battery 61 at the start of charging is larger, the SOC threshold value Spb1 of the lead storage battery 50 is set to a larger value. The reason will be described with reference to FIG.

  In FIG. 10, the SOC value Sni1 of the nickel-metal hydride storage battery 61 at the start of charging in the charging period Tch1 is Sni1 <30. Therefore, as described with reference to FIG. 7, SOC threshold Spb1 of lead storage battery 50 is set to 97%. As shown in FIG. 10, when the SOC value of lead storage battery 50 reaches SOC threshold Spb1 (97% in FIG. 10) (that is, at the end of charging period Tch1), the SOC value of nickel-metal hydride storage battery 61 becomes 50%. Has not reached.

  Therefore, since it takes time until the SOC value of the nickel-metal hydride storage battery 61 reaches 80%, the time for the constant voltage charging at 15.0 V (charging period Tch2) is sufficient. For this reason, as shown in FIG. 10, when the SOC value of the nickel-metal hydride storage battery 61 reaches 80%, the SOC value of the lead storage battery 50 exceeds 100%. Therefore, insufficient charging of the lead storage battery 50 can be eliminated.

  On the other hand, in the comparative example of FIG. 10, the SOC value Sni1 of the nickel-metal hydride storage battery 61 at the start of charging in the charging period Tch11 is 50%. In this case, when the SOC value of the lead storage battery 50 reaches 97%, the SOC value of the nickel-metal hydride storage battery 61 is close to 70%. Therefore, the SOC value of nickel-metal hydride storage battery 61 reaches 80% in a short time, and charging period Tch12 is shortened. Therefore, at the end of the charging period Tch12 when the SOC value of the nickel-metal hydride storage battery 61 has reached 80%, the SOC value of the lead storage battery 50 has not exceeded 100%.

  Therefore, in the second embodiment, as shown in FIG. 7, as the SOC value of the nickel-metal hydride storage battery 61 at the start of charging is larger, the SOC threshold Spb1 of the lead storage battery 50 is set to a larger value. Therefore, at the end of the constant voltage charging time at 13.7 V (charging period Tch1), the SOC value of the lead storage battery 50 is close to 100%. As a result, the SOC value of the lead storage battery 50 exceeds 100% even if the time for constant voltage charging at 15.0 V (charging period Tch2) is short. As a result, it is possible to suppress excessive sulfation occurring in the undercharged lead storage battery 50.

(Third embodiment)
FIG. 11 is a flowchart schematically showing the charging operation of the third embodiment. FIG. 12 is a diagram schematically showing an example of the SOC of the lead storage battery 50 and the nickel-metal hydride storage battery 61 increased by the charging operation of FIG. FIG. 13 is a timing chart schematically showing the operation of the switch element 35. The configuration of the third embodiment is the same as that of the second embodiment shown in FIG. Hereinafter, the third embodiment will be described focusing on the differences from the second embodiment.

  11, S101 to S107 are the same as S101 to S107 in FIG. 9 of the second embodiment. Due to the constant voltage charging at 13.7 V in S106 and S107, during the charging period Tch1 in FIG. 12, the SOC of the lead storage battery 50 is larger than the SOC of the nickel-metal hydride storage battery 61 as in the second embodiment (FIG. 10). But increase quickly.

  If the SOC value of lead storage battery 50 is equal to or greater than SOC threshold value Spb1 in S107 (YES in S107), in S115, voltage control section 184 requests a control to adjust the output voltage of ISG 30 to 15.0V. SG is output to ECU70. When receiving the control signal SG, the ECU 70 controls the voltage adjusting unit 31 to adjust the output voltage of the ISG 30 to 15.0V. Further, the switch control unit 185 controls the switch element 35 to alternately repeat the ON period Ton and the OFF period Toff of the switch element 35 (for example, Ton = Toff = 5 seconds in the third embodiment). Thus, the lead storage battery 50 and the nickel hydride storage battery 61 of the power supply unit 45 are pulse-charged at a voltage of 15.0 V. Steps S109 to S112 are the same as steps S109 to S112 in FIG. 9 of the second embodiment.

  As described with reference to FIG. 24, in the constant-voltage charging at a voltage of 15.0 V, in the initial period T0 at the beginning of charging, the charging current of the lead storage battery 50 is larger than the charging current of the nickel-metal hydride storage battery 61. . On the other hand, in the third embodiment, as shown in FIG. 13, the on-period Ton and the off-period Toff are alternately repeated, and the switch element 35 is turned on and off.

  In the off period Toff of the switch element 35, the voltage becomes zero. In both the lead storage battery 50 and the nickel hydride storage battery 61, the state near the electrodes returns to the initial state in about 5 seconds when the application of the voltage is stopped. For this reason, the state becomes the same as the initial period T0 at the beginning of charging in FIG. Therefore, in the ON period Ton of the switch element 35, the charging current Ipb of the lead storage battery 50 is larger than the charging current Ini of the nickel-metal hydride storage battery 61. Therefore, as shown in FIG. 12, in charging period Tch3, the SOC of nickel-metal hydride storage battery 61 hardly increases, and the SOC of lead storage battery 50 mainly increases. When the SOC value of the lead storage battery 50 reaches the SOC upper limit value Spb2 (for example, Spb2 = 105% in the third embodiment) (YES in S110 in FIG. 11), the switch element 35 is turned off (S111 in FIG. 11). ), Charging is stopped.

  Thus, also in the third embodiment, as shown in FIG. 12, overcharging is performed when the SOC value of the lead storage battery 50 exceeds 100%. Thus, in the third embodiment, similarly to the second embodiment, it is possible to suppress excessive sulfation occurring in the undercharged lead storage battery 50. Also in the third embodiment, as in the second embodiment, the lead storage battery 50 does not excessively deteriorate due to overcharging.

(Modification of Second and Third Embodiments)
The present invention is not limited to the second and third embodiments. Hereinafter, modifications of the second and third embodiments of the present invention will be described.

  (1) In the third embodiment, in S115 of FIG. 11, the switch control unit 185 of the battery control unit 180 turns on and off the switch element 35 to perform pulse charging. Alternatively, in S115 of FIG. 11, the switch control unit 185 may switch the output voltage of the ISG 30 into a pulse as shown in FIG.

  FIG. 14 is a timing chart schematically showing the output voltage of ISG 30. In the operation shown in FIG. 14, voltage control unit 184 sends control signal SG requesting ECU 70 to alternately repeat first period T1 of output voltage 15.0 V and second period T2 of output voltage 13.7 V alternately. Output. When receiving the control signal SG, the ECU 70 controls the voltage adjustment unit 31 to control the output voltage of the ISG 30 as shown in FIG.

  The second period T2 is, for example, 5 seconds. In the second period T2 in which the charging voltage is 13.7 V, as described with reference to FIG. 8, the charging current Ipb of the lead storage battery 50 is larger than the charging current Ini of the nickel-metal hydride storage battery 61. Therefore, in the second period T2, similarly to the charging period Tch1 in FIG. 10, the SOC of the lead storage battery 50 increases earlier than the SOC of the nickel-metal hydride storage battery 61. The second period T2 is not limited to 5 seconds and may be, for example, 10 seconds.

  The first period T1 is, for example, 4 seconds. Unlike the off-period Toff of the third embodiment (FIG. 13), in the second period T2, the charging voltage is not 0 but 13.7V. Therefore, it is considered that the period in which the charging current Ipb of the lead storage battery 50 is larger than the charging current Ini of the nickel-metal hydride storage battery 61 is shorter than the initial period T0 shown in FIG. Therefore, in the operation of FIG. 14, the first period T1 is set to, for example, 4 seconds, which is shorter than the initial period T0 of about 5 seconds.

  Therefore, even in the first period T1, the charging current Ipb of the lead storage battery 50 is larger than the charging current Ini of the nickel-metal hydride storage battery 61. Therefore, also in the first period T1, the SOC of the lead storage battery 50 increases faster than the SOC of the nickel-metal hydride storage battery 61. As a result, also in the operation of FIG. 14, the SOC of the lead storage battery 50 can be charged up to the SOC upper limit Spb2 (for example, Spb2 = 105%), similarly to the third embodiment (FIG. 12).

  In the charging of FIG. 14, the charging is continued at 13.7 V even in the second period T2, and the charging is not alternately turned on and off as shown in FIG. Therefore, the charging in FIG. 14 is not strictly a pulse charging. However, in this specification, charging as shown in FIG. 14 is also included in pulse charging.

  (2) In the second embodiment, in S6 of FIG. 9, the output voltage of the ISG 30 is adjusted to 13.7V. In the operation of FIG. 14, the output voltage of the ISG 30 in the second period T2 is adjusted to 13.7V. However, it is not limited to 13.7V. The output voltage of the ISG 30 is a voltage at which the hydrogen storage alloy of the negative electrode of the nickel-metal hydride storage battery 61 does not enter a state in which hydrogen can be easily stored, and may be adjusted to a voltage at which charging of the lead storage battery 50 proceeds. For example, the upper limit may be 1.38 to 1.39 V per cell of the nickel-metal hydride storage battery 61. In other words, in the second embodiment, since the nickel-metal hydride storage battery 61 includes a 10-cell nickel-metal hydride storage battery connected in series, the output voltage of the ISG 30 may be set to an upper limit of 13.8 to 13.9 V.

  (3) In the second embodiment, in S8 of FIG. 9, the output voltage of the ISG 30 is adjusted to 15.0V. In the operation of FIG. 14, the output voltage of the ISG 30 in the first period T1 is adjusted to 15.0V. However, it is not limited to 15.0V. The output voltage of the ISG 30 may be, for example, 14.5V. The output voltage of the ISG 30 may be a high voltage that allows the ISG 30 to output and does not damage or break the lead storage battery 50 and the nickel-metal hydride storage battery 61.

  (4) In the second and third embodiments, the vehicle 1 includes the battery control unit 180 separately from the ECU 70. Alternatively, the ECU 70 may be configured to include each functional block of the battery control unit 180, and the battery control unit 180 may be omitted.

  (5) In the second and third embodiments, the nickel-metal hydride storage battery 61 is connected in parallel with the lead storage battery 50. Alternatively, another secondary battery, such as a lithium ion secondary battery, a lithium ion polymer secondary battery, or a nickel zinc storage battery, may be connected in parallel with the lead storage battery 50.

  (6) In the second and third embodiments, the vehicle 1 includes the ISG 30. Alternatively, a normal alternator may be provided instead of the ISG 30. In this case, the voltage adjuster 31 adjusts the output voltage of the alternator.

(Fourth embodiment)
FIG. 15 is a block diagram schematically illustrating a configuration of a vehicle 1 including a battery control unit 280 and an ECU 70 according to the fourth embodiment.

  The vehicle 1 is a hybrid electric vehicle that uses an engine as a main power source and a motor as an auxiliary power source. The vehicle 1 includes an engine 10, a starter motor 20, an integrated starter generator (ISG) 30, a voltage adjustment unit 31, a switch element 35, an electric load 40, a power supply unit 45, an electronic control unit (ECU) 70, and a battery control unit 280. .

  The power supply unit 45 includes a lead storage battery 50, current sensors 51 and 63, and a nickel hydride storage battery (Ni-MH) 61. The lead storage battery 50 and the nickel hydride storage battery 61 are connected in parallel with each other. The connection point K2 on the negative electrode side of the lead storage battery 50 and the nickel hydride storage battery 61 is grounded. The starter motor 20, the ISG 30, and the electrical load 40 are connected in parallel with the power supply unit 45. A power supply voltage Vcc is supplied from the power supply unit 45 to the battery control unit 280 and the ECU 70.

  Lead storage battery 50 includes a six-cell lead storage battery connected in series. With this configuration, the nominal voltage of the lead storage battery 50 is 12V. Nickel-metal hydride storage battery 61 includes a 10-cell nickel-metal hydride storage battery connected in series. With this configuration, the nominal voltage of the nickel-metal hydride storage battery 61 is 12V. The power output from the power supply unit 45 is used for driving the starter motor 20 and the ISG 30 for starting the engine 10 of the vehicle 1 and for powering the electrical load 40.

  Current sensor 51 detects a charging current or a discharging current flowing through lead storage battery 50. The current sensor 51 is mounted on a branch line L1 branched from a connection point K1 on the positive electrode side of the lead storage battery 50 and the nickel hydride storage battery 61. The current sensor 51 is provided to calculate the amount of charge and the amount of discharge of the lead storage battery 50.

  Current sensor 63 detects a charging current or a discharging current flowing through nickel-metal hydride storage battery 61. The current sensor 63 is attached on a branch line L2 branched from a connection point K1 on the positive electrode side of the lead storage battery 50 and the nickel hydride storage battery 61. The current sensor 63 is provided for calculating the amount of charge and the amount of discharge of the nickel-metal hydride storage battery 61.

  The current sensors 51 and 63 are, for example, Hall effect type current sensors including a Hall element. Alternatively, the current sensors 51 and 63 may include a shunt resistor and detect a current based on a voltage drop of the shunt resistor.

  The starter motor 20 starts the engine 10 when a user operates an ignition switch.

  The ISG 30 has both a power generation function and an electric function. When the engine 10 of the vehicle 1 is operating, the ISG 30 is driven by the engine 10 and generates power by a power generation function. When the generated electric power exceeds the electric load of the electrical load 40, the generated electric power charges the lead storage battery 50 and the nickel hydride storage battery 61 of the power supply unit 45. Further, when the brake pedal (not shown) is operated to start deceleration while the vehicle 1 is traveling, torque is transmitted from the wheels to the ISG 30, and the ISG 30 generates power by the power generation function. The generated electric power charges the lead storage battery 50 and the nickel hydride storage battery 61 of the power supply unit 45. As a result, energy is regenerated. When the vehicle 1 stops, the engine 10 automatically stops by the idle stop control of the ECU 70. When the vehicle 1 starts, the vehicle 1 is driven by the electric function of the ISG 30 and the engine 10 is started.

  The voltage adjuster 31 adjusts the output voltage of the ISG 30. The output voltage by the power generation function of the ISG 30 changes depending on the rotation speed of the engine 10, the current value of the load current, and the field current without being adjusted. The voltage adjuster 31 adjusts the output voltage of the ISG 30 to a constant value, for example, by increasing or decreasing the field current. The voltage adjustment unit 31 includes, for example, a semiconductor circuit in which a power transistor and a voltage detection circuit are integrated. In the fourth embodiment, the voltage adjusting unit 31 adjusts the output voltage of the ISG 30 to, for example, 14.5 V DC (an example of a charging voltage value).

  The switch element 35 is provided between the ISG 30 and the power supply unit 45. The switch element 35 is turned on when the engine 10 is stopped. The switch element 35 is turned off when charging of the lead storage battery 50 and the nickel hydride storage battery 61 is stopped. ON / OFF of the switch element 35 is controlled by the battery control unit 280. The switch element 35 may be a mechanical relay. Alternatively, the switch element 35 may be a semiconductor switch such as a power MOSFET or an insulated gate bipolar transistor. The electric load 40 includes loads of electric components and the like mounted on the vehicle 1 such as an air conditioner and a room light.

  The ECU 70 includes, for example, a CPU (Central Processing Unit) that executes predetermined arithmetic processing, a ROM (Read Only Memory) in which a predetermined control program is stored, and a RAM (Random Access Memory) in which data is temporarily stored. Peripheral circuits are provided. The ECU 70 is configured to be able to communicate with the battery control unit 280.

  The ECU 70 controls the entire operation of the vehicle 1 including the engine 10, the starter motor 20, the ISG 30, the voltage adjustment unit 31, and the electric load 40.

  The battery control unit 280 includes, for example, a CPU that executes predetermined arithmetic processing, a ROM in which a predetermined control program is stored, a RAM in which data is temporarily stored, and peripheral circuits thereof. The battery control unit 280 includes a storage unit 281 configured by, for example, a flash memory. The battery control unit 280 functions as a first SOC calculation unit 282, a second SOC calculation unit 283, and a switch control unit 285 by executing a control program stored in the ROM.

  Storage unit 281 stores in advance an SOC upper limit value Sni2 (an example of a first SOC upper limit value) as the SOC upper limit value of nickel-metal hydride storage battery 61. In the fourth embodiment, for example, Sni2 = 80%. The SOC upper limit value Sni2 is not limited to 80%, and may be, for example, 75%. As described above, if the SOC upper limit value Sni2 is too high, the nickel-metal hydride storage battery 61 cannot store the regenerative energy of the engine 10. Therefore, SOC upper limit value Sni2 may be any SOC value enough to store the regenerative energy of engine 10.

  Storage unit 281 stores in advance an SOC lower limit value Sni3 (an example of a first SOC lower limit value) as a lower limit value of the SOC of nickel-metal hydride storage battery 61. In the fourth embodiment, for example, Sni3 = 20%. The SOC lower limit value Sni3 is not limited to 20%, and may be, for example, 25%. As described above, if the SOC lower limit value Sni3 is too low, supply of a large current required when starting the engine 10 or when restarting the engine 10 stopped by the idle stop control is hindered. Therefore, the SOC lower limit value Sni3 may be any SOC value that can supply a large current when starting or restarting the engine 10.

  The storage unit 281 stores in advance an SOC protection threshold value Sni4 set to a value exceeding the SOC upper limit value Sni2. In the fourth embodiment, for example, Sni4 = 90%. The SOC protection threshold value Sni4 is not limited to 90%, and may be, for example, 85%. The SOC protection threshold value Sni4 may be set so that the SOC value of the nickel-metal hydride storage battery 61 does not become excessive.

  Storage unit 281 stores in advance an SOC upper limit value Spb2 (an example of a second SOC upper limit value) that is predetermined to be 100% or more as the SOC upper limit value of lead storage battery 50. In the fourth embodiment, for example, Spb2 = 100%.

  Storage unit 281 stores in advance an SOC lower limit value Spb3 (an example of a second SOC lower limit value) determined as the lower limit value of the SOC of lead storage battery 50. In the fourth embodiment, for example, Spb3 = 80%. Note that SOC lower limit value Spb3 is not limited to 80%, and may be, for example, 75%. If the SOC value of the lead storage battery 50 becomes excessively low, the deterioration of the lead storage battery 50 is accelerated. Therefore, SOC lower limit value Spb3 may be determined so that lead storage battery 50 does not deteriorate quickly.

  Battery control unit 280 controls charging and discharging of nickel-metal hydride storage battery 61 such that the SOC of nickel-metal hydride storage battery 61 is maintained within a range between SOC upper limit value Sni2 and SOC lower limit value Sni3. Battery control unit 280 controls charging and discharging of lead storage battery 50 such that the SOC of lead storage battery 50 is maintained at or above SOC lower limit Spb3.

  First SOC calculating section 282 calculates the amount of charge and the amount of discharge of lead storage battery 50 using the current value detected by current sensor 51. The first SOC calculation unit 282 calculates the SOC of the lead storage battery 50 using the calculated charge amount and discharge amount of the lead storage battery 50. The first SOC calculation unit 282 calculates the SOC, for example, every 100 msec. First SOC calculating section 282 and current sensor 51 correspond to an example of a lead storage battery SOC obtaining section.

  The second SOC calculation unit 283 calculates the amount of charge and the amount of discharge of the nickel-metal hydride storage battery 61 using the current value detected by the current sensor 63. The second SOC calculation unit 283 calculates the SOC of the nickel-metal hydride storage battery 61 using the calculated charge amount and discharge amount of the nickel-metal hydride storage battery 61. The second SOC calculation unit 283 calculates the SOC, for example, every 100 msec. The second SOC calculation section 283 and the current sensor 63 correspond to an example of a secondary battery SOC acquisition section.

  The switch control unit 285 controls on / off of the switch element 35. The switch control unit 285 turns on the switch element 35 when the engine 10 is stopped. When the SOC of nickel-metal hydride storage battery 61 calculated by second SOC calculating section 283 increases to or above SOC upper limit value Sni2 during charging, switch control section 285 turns off switch element 35 and stops charging.

  When the SOC of lead storage battery 50 calculated by first SOC calculating section 282 increases to or above SOC upper limit value Spb2 during charging, switch control section 285 turns off switching element 35 and stops charging.

  The switch control unit 285 turns on the switch element 35 while the SOC of the nickel-metal hydride storage battery 61 calculated by the second SOC calculation unit 283 is less than the SOC upper limit Spb2. When the SOC of the nickel-metal hydride storage battery 61 calculated by the second SOC calculating unit 283 increases to the SOC upper limit Spb2 or more during charging, the switch control unit 285 turns on and off the switch element 35 to switch from constant voltage charging to pulse charging. Switch.

  FIG. 16 is a flowchart schematically illustrating a charging operation according to the fourth embodiment. FIG. 17 is a diagram schematically showing an example of the SOC of the lead storage battery 50 and the nickel-metal hydride storage battery 61 increased by the charging operation of FIG. FIG. 18 is a timing chart schematically showing the operation of the switch element 35.

  The vertical axis in FIG. 17 represents the SOC of the lead storage battery 50, and the horizontal axis represents the SOC of the nickel-metal hydride storage battery 61. In FIG. 17, a charging period Tch1 represents a period during which constant-voltage charging is performed, and a charging period Tch2 represents a period during which pulse charging is performed. Note that the charging period Tch3 represents a period during which pulse charging is performed in a fifth embodiment described later. In the normal state (ie, when the operation in FIG. 16 is started), the switch element 35 is turned on.

  In S201 of FIG. 16, first, the switch control unit 285 obtains the SOC value of the lead storage battery 50 from the first SOC calculation unit 282. Switch control unit 285 determines whether or not the obtained SOC value of lead storage battery 50 is less than SOC lower limit value Spb3. If the SOC value of the lead storage battery 50 is less than the SOC lower limit value Spb3 (YES in S201), in S202 (an example of the predetermined voltage charging step), the switch control unit 285 keeps the switch element 35 on. As a result, constant voltage charging is performed.

  As described with reference to FIG. 24, when the voltage is 14.5 V, the charge current of the nickel-metal hydride storage battery 61 is larger than the charge current of the lead storage battery 50 except for the initial period T0 at the start of charging. Therefore, as shown in FIG. 17, in the charging period Tch1, the SOC of the nickel-metal hydride storage battery 61 increases faster than the SOC of the lead storage battery 50.

  In S203 (an example of a secondary battery SOC obtaining step), the switch control unit 285 obtains the SOC value of the nickel-metal hydride storage battery 61 from the second SOC calculating unit 283. Switch control unit 285 determines whether or not the obtained SOC value of nickel-metal hydride storage battery 61 is equal to or greater than SOC upper limit value Sni2. If the SOC value of nickel-metal hydride battery 61 is less than SOC upper limit value Sni2 (NO in S203), the process returns to S202, and constant voltage charging is continued.

  In S203, if the SOC value of the nickel-metal hydride storage battery 61 is equal to or more than the SOC upper limit value Sni2 (YES in S203), the switch control unit 285 controls the switch element 35 in S204 (an example of the pulse charging step). The ON period Ton and the OFF period Toff of the switch element 35 are alternately repeated (for example, Ton = Toff = 5 seconds in the fourth embodiment). Thereby, the lead storage battery 50 and the nickel-metal hydride storage battery 61 of the power supply unit 45 are pulse-charged at a voltage of 14.5V.

  As described with reference to FIG. 24, in the constant voltage charging at a voltage of 14.5 V, in the initial period T0 at the beginning of charging, the charging current of the lead storage battery 50 is larger than the charging current of the nickel hydride storage battery 61. . On the other hand, in S4, as shown in FIG. 18, the ON period Ton and the OFF period Toff are alternately repeated, and the switch element 35 is turned on and off.

  In the off period Toff of the switch element 35, the voltage becomes zero. In both the lead storage battery 50 and the nickel hydride storage battery 61, the state near the electrodes returns to the initial state in about 5 seconds when the application of the voltage is stopped. For this reason, the state becomes the same as the initial period T0 at the beginning of charging in FIG. 24 for each ON period Ton of the switch element 35. Therefore, in the ON period Ton of the switch element 35, the charging current Ipb of the lead storage battery 50 is larger than the charging current Ini of the nickel-metal hydride storage battery 61. Therefore, as shown in FIG. 17, in the charging period Tch2, the SOC of the nickel-metal hydride storage battery 61 hardly increases, and the SOC of the lead storage battery 50 mainly increases.

  Returning to FIG. 16, in S205, the switch control unit 285 acquires the SOC value of the nickel-metal hydride storage battery 61 from the second SOC calculation unit 283. Switch control unit 285 determines whether or not the obtained SOC value of nickel-metal hydride storage battery 61 is less than SOC lower limit value Sni3. If the SOC value of nickel-metal hydride storage battery 61 is equal to or greater than SOC lower limit value Sni3 (NO in S205), in S206, switch control unit 285 determines whether or not the SOC value of nickel-metal hydride storage battery 61 is equal to or greater than SOC protection threshold value Sni4. Is determined.

  If the SOC value of nickel-metal hydride storage battery 61 is less than SOC protection threshold value Sni4 (NO in S206), switch control unit 285 acquires the SOC value of lead storage battery 50 from first SOC calculation unit 282 in S207. Switch control unit 285 determines whether or not the SOC value of lead storage battery 50 is equal to or greater than SOC upper limit value Spb2. If the SOC value of lead storage battery 50 is less than SOC upper limit value Spb2 (NO in S207), the process returns to S204, and pulse charging is continued.

  If the SOC value of nickel-metal hydride storage battery 61 is less than SOC lower limit value Sni3 in S205 (YES in S205), the process returns to S202. As a result, the switch control unit 285 turns on the switch element 35 to switch from pulse charging to constant voltage charging. As a result, the SOC value of the nickel-metal hydride storage battery 61 that has dropped below the SOC lower limit value Sni3 increases.

  If the SOC value of the nickel-metal hydride storage battery 61 is equal to or larger than the SOC protection threshold value Sni4 in S206 (YES in S206), in S208, the switch control unit 285 turns off the switch element 35 and stops the pulse charging.

  In S207, when the SOC value of lead storage battery 50 reaches SOC upper limit value Spb2 (for example, Spb2 = 100% in the fourth embodiment) (YES in S207), the process proceeds to S208.

  If the SOC value of the lead storage battery 50 is equal to or more than the SOC lower limit value Spb3 in S201 (NO in S201), the switch control unit 285 acquires the SOC value of the nickel-metal hydride storage battery 61 from the second SOC calculation unit 283 in S209. . Switch control unit 285 determines whether or not the obtained SOC value of nickel-metal hydride storage battery 61 is less than SOC upper limit value Sni2. If the SOC value of nickel-metal hydride storage battery 61 is equal to or greater than SOC upper limit value Sni2 (NO in S209), the process proceeds to S208.

  In S209, if the SOC value of nickel-metal hydride storage battery 61 is less than SOC upper limit value Sni2 (YES in S209), the process proceeds to S202.

  As shown in S206 and S207 of FIG. 16, when the SOC value of the nickel-metal hydride storage battery 61 increases to the SOC protection threshold value Sni4 or more or the SOC value of the lead storage battery 50 increases to the SOC upper limit value or more, the switch element 35 is turned off, The pulse charging is stopped. In the example of FIG. 17, the pulse charging is stopped when the SOC value of the lead storage battery 50 reaches the SOC upper limit Spb2 or more.

  As described above, in the fourth embodiment, as shown in FIG. 17, in the charging period Tch1, constant voltage charging is performed until the SOC value of the nickel-metal hydride storage battery 61 becomes 80%, and in the charging period Tch2, the lead storage battery 50 is charged. Are pulse-charged until the SOC value becomes 100%. Thus, according to the fourth embodiment, both the lead storage battery 50 and the nickel-metal hydride storage battery 61 can be prevented from being insufficiently charged.

(Fifth embodiment)
FIG. 19 and FIG. 20 are flowcharts schematically showing the charging operation of the fifth embodiment. The configuration of the fifth embodiment is the same as that of the fourth embodiment shown in FIG. Hereinafter, the fifth embodiment will be described focusing on the differences from the fourth embodiment.

  In the fifth embodiment, the storage unit 281 previously stores two values of 100% and a value exceeding 100% (for example, 105% in the fifth embodiment) as the SOC upper limit value Spb2.

  The switch control unit 285 counts the number of times that the SOC of the lead storage battery 50 calculated by the first SOC calculation unit 282 drops below the SOC lower limit value Spb3. Every time the count value is N (for example, N = 5 in the fifth embodiment), the switch control unit 285 uses a value exceeding 100% (for example, 105% in the fifth embodiment) as the SOC upper limit value Spb2. . When the count value is 1 to (N-1) times, that is, when the count value is less than N times, the switch control unit 285 uses 100% as the SOC upper limit value Spb2. The value exceeding 100% is not limited to 105%, but may be, for example, 110%, and may be set to an appropriate value according to the characteristics of the lead storage battery 50.

  In FIG. 19, S201 is the same as S201 of FIG. 16 of the fourth embodiment. If the SOC value of lead storage battery 50 is less than SOC lower limit value Spb3 (YES in S201), in S211, switch control unit 285 increases count value Ct by one.

  In S212, the switch control unit 285 determines whether the count value Ct is less than N (N = 5 in the fifth embodiment). If count value Ct is smaller than N (YES in S212), in S213, switch control unit 285 sets SOC upper limit value Spb2 to 100%. Subsequently, the process proceeds to S202.

  On the other hand, if the count value Ct is equal to or greater than N in S212 (NO in S212), the switch control unit 285 resets the count value Ct to 0 in S14. In S215, the switch control unit 285 sets the SOC upper limit value Spb2 to 105%. Subsequently, the process proceeds to S202. Steps S202 to S209 are the same as steps S202 to S209 in FIG. 16 of the fourth embodiment.

  In this way, every time the SOC value of the lead storage battery 50 drops below the SOC lower limit value Spb3, the SOC upper limit value Spb2 is set to 105%. Therefore, if NO in S5 in FIG. 20 and NO in S6, pulse charging is continued until YES in S7, and as shown in FIG. 17, the charge period Tch3 of the pulse charging causes It is charged until the SOC value becomes 105%.

  According to the fifth embodiment, as shown in the charging period Tch3 in FIG. 17, overcharging is performed when the SOC value of the lead storage battery 50 exceeds 100%. As a result, it is possible to suppress excessive sulfation occurring in the undercharged lead storage battery 50. Overcharging is not performed every time the SOC value of the lead storage battery 50 falls below the SOC lower limit value Spb3, but the SOC value of the lead storage battery 50 falls below the SOC lower limit value Spb3 at N (this In the fifth embodiment, for example, it is performed every N = 5) times. Therefore, the lead storage battery 50 is not excessively deteriorated due to overcharging.

(Sixth embodiment)
FIG. 21 is a block diagram schematically illustrating a configuration of a vehicle 1 including a battery control unit 280 and an ECU 70 according to the sixth embodiment. Hereinafter, the sixth embodiment will be described with a focus on differences from the fourth embodiment.

  In the sixth embodiment, the voltage adjuster 31 adjusts the output voltage of the ISG 30 in two stages, for example, DC 15.0V and DC 13.7V.

  In the sixth embodiment, the battery control unit 280 further includes a voltage control unit 284. Voltage control unit 284 outputs control signal SG to ECU 70 to control the charging voltage during charging of lead storage battery 50 and nickel-metal hydride storage battery 61. ECU 70 receives control signal SG output from battery control unit 280 and controls voltage adjustment unit 31.

  FIG. 22 is a timing chart schematically showing a charging current when the power supply unit 45 of FIG. 15 is charged at a constant voltage of 13.7 V.

  In FIG. 22, unlike FIG. 24 described above, the charging current Ini of the nickel-metal hydride storage battery 61 does not exceed the charging current Ipb of the lead storage battery 50. The cause is inferred as follows. In the lead-acid battery 50 of the dissolution precipitation type, the charging chemical reaction proceeds at a low speed even at a voltage of 13.7 V. However, in the nickel-metal hydride storage battery 61, since the voltage is too low at 13.7V, the hydrogen storage alloy does not enter a state in which hydrogen can be easily stored, so that the chemical reaction for charging hardly proceeds. Therefore, when the power supply unit 45 in FIG. 15 is charged at a constant voltage of 13.7 V, the charging current Ipb of the lead storage battery 50 becomes larger than the charging current Ini of the nickel hydride storage battery 61.

  As can be seen from a comparison between FIG. 22 and FIG. 24, the overall charging current It is about half that of FIG. 24 in FIG. Therefore, it takes time to charge the lead storage battery 50 and the nickel hydride storage battery 61. However, when the output voltage of the ISG 30 is adjusted to 13.7 V, the charging of the lead storage battery 50 can be advanced faster than that of the nickel-metal hydride storage battery 61.

  In the fourth embodiment, in S204 of FIG. 16, and in the fifth embodiment, in S204 of FIG. 20, the switch control unit 285 of the battery control unit 280 turns on and off the switch element 35 to perform pulse charging. Alternatively, in the sixth embodiment, the voltage control unit 284 switches the output voltage of the ISG 30 into a pulse as shown in FIG.

  FIG. 23 is a timing chart schematically showing the output voltage of ISG 30. In the operation shown in FIG. 23, voltage control unit 284 transmits to ECU 70 control signal SG requesting that ECU 70 alternately repeat first period T1 of output voltage 15.0 V and second period T2 of output voltage 13.7 V. Output. Upon receiving the control signal SG, the ECU 70 controls the voltage adjusting unit 31 to control the output voltage of the ISG 30 as shown in FIG.

  The second period T2 is, for example, 5 seconds. In the second period T2 in which the charging voltage is 13.7 V, as described with reference to FIG. 22, the charging current Ipb of the lead storage battery 50 is larger than the charging current Ini of the nickel-metal hydride storage battery 61. Therefore, in the second period T2, similarly to the charging period Tch2 in FIG. 17, the SOC of the lead storage battery 50 increases faster than the SOC of the nickel-metal hydride storage battery 61. The second period T2 is not limited to 5 seconds and may be, for example, 10 seconds.

  The first period T1 is, for example, 4 seconds. Unlike the off period Toff of the fourth embodiment (FIG. 18), in the second period T2, the charging voltage is not 0 but 13.7V. Therefore, it is considered that the period in which the charging current Ipb of the lead storage battery 50 is larger than the charging current Ini of the nickel-metal hydride storage battery 61 is shorter than the initial period T0 shown in FIG. Therefore, in the operation of FIG. 23, the first period T1 is set to, for example, 4 seconds, which is shorter than the initial period T0 of about 5 seconds.

  Therefore, even in the first period T1, the charging current Ipb of the lead storage battery 50 is larger than the charging current Ini of the nickel-metal hydride storage battery 61. Therefore, also in the first period T1, the SOC of the lead storage battery 50 increases faster than the SOC of the nickel-metal hydride storage battery 61. As a result, even in the operation of FIG. 23, similarly to the fourth and fifth embodiments, the SOC of the lead storage battery 50 is set to the SOC upper limit Spb2 (Spb2 = 100% in the fourth embodiment, Spb2 = 105 in the fifth embodiment). %).

  In the charging shown in FIG. 23, the charging is continued at 13.7 V even in the second period T2, and the charging is not alternately turned on and off as shown in FIG. Therefore, the charging in FIG. 23 is not strictly a pulse charging. However, in the present specification, charging as shown in FIG. 23 is also included in pulse charging.

(Modifications of Fourth to Sixth Embodiments)
The present invention is not limited to the fourth to sixth embodiments. Hereinafter, modifications of the fourth to sixth embodiments of the present invention will be described.

  (1) In the sixth embodiment, the output voltage of the ISG 30 in the second period T2 is adjusted to 13.7V. However, it is not limited to 13.7V. The output voltage of the ISG 30 is a voltage at which the hydrogen storage alloy of the negative electrode of the nickel-metal hydride storage battery 61 does not enter a state in which hydrogen can be easily stored, and may be adjusted to a voltage at which charging of the lead storage battery 50 proceeds. For example, the upper limit may be 1.38 to 1.39 V per cell of the nickel-metal hydride storage battery 61. In other words, in the fourth embodiment, since the nickel-metal hydride storage battery 61 includes a 10-cell nickel-metal hydride storage battery connected in series, the output voltage of the ISG 30 may be set to an upper limit of 13.8 to 13.9 V.

  (2) In the fourth embodiment, the output voltage of the ISG 30 is adjusted to 14.5V. In the sixth embodiment, the output voltage of the ISG 30 in the first period T1 is adjusted to 15.0V. However, it is not limited to these voltage values. The output voltage of the ISG 30 may be a high voltage that allows the ISG 30 to output and does not damage or break the lead storage battery 50 and the nickel-metal hydride storage battery 61.

  (3) In the fourth to sixth embodiments, the vehicle 1 includes the battery control unit 280 separately from the ECU 70. Alternatively, the ECU 70 may be configured to include each functional block of the battery control unit 280, and the battery control unit 280 may be eliminated.

  (4) In the fourth to sixth embodiments, the nickel-metal hydride storage battery 61 is connected in parallel with the lead storage battery 50. Alternatively, another secondary battery, such as a lithium ion secondary battery, a lithium ion polymer secondary battery, or a nickel zinc storage battery, may be connected in parallel with the lead storage battery 50.

  (5) In the fourth to sixth embodiments, the vehicle 1 includes the ISG 30. Alternatively, a normal alternator may be provided instead of the ISG 30. In this case, the voltage adjuster 31 adjusts the output voltage of the alternator.

INDUSTRIAL APPLICABILITY The lead storage battery deterioration determination device and the lead storage battery deterioration determination method according to the present disclosure are useful as a device and a method capable of suitably determining the deterioration of a lead storage battery. Further, the charge control device and the charge control method according to the present disclosure are useful as a device and a method that can suitably charge a lead storage battery and a secondary battery connected in parallel to each other.

Claims (2)

A power supply unit including a lead storage battery and a secondary battery other than the lead storage battery connected in parallel to each other,
A voltage detection unit that detects a voltage of the power supply unit;
An acquisition unit for acquiring an internal resistance of the secondary battery,
A storage unit that stores in advance a total current value supplied from the power supply unit to the starting motor when the engine is started by the starting motor;
A starting voltage, which is a voltage of the power supply unit when the engine is started by the starting motor, is detected by the voltage detection unit, and the detected starting voltage and the inside of the secondary battery acquired by the acquisition unit are detected. A calculating unit that calculates an internal resistance of the lead storage battery using the resistance and the total current value stored in the storage unit;
Comparing the internal resistance of the lead storage battery calculated by the arithmetic unit with a predetermined resistance threshold, and when the internal resistance of the lead storage battery is higher than the resistance threshold, the lead storage battery is degraded A determining unit for determining,
Comprising,
A device for determining the deterioration of a lead storage battery. A lead storage battery deterioration determination method in a lead storage battery deterioration determination device including a power supply unit including a lead storage battery and a secondary battery other than the lead storage battery connected in parallel to each other,
An obtaining step of obtaining an internal resistance of the secondary battery,
A detecting step of detecting a starting voltage that is a voltage of the power supply unit when the engine is started by the starting motor;
The starting voltage detected in the detecting step, the internal resistance of the secondary battery obtained in the obtaining step, and from the power supply unit when the engine is started by the starting motor stored in a storage unit in advance. A calculating step of calculating an internal resistance of the lead storage battery by using an entire current value supplied to the starting motor;
Comparing the internal resistance of the lead storage battery calculated in the calculation step with a predetermined resistance threshold, and when the internal resistance of the lead storage battery is higher than the resistance threshold, the lead storage battery is degraded A determining step of determining;
including,
A method for determining the deterioration of a lead storage battery.

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