JP2017197117A - Power supply controller - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a power supply controller that is applied to a system comprising a first storage battery and a second storage battery, and can avoid flowing of an overcurrent from the first storage battery to the second storage battery.SOLUTION: A connection path LD which electrically connects the first storage battery 11 and second storage battery 12 to each other is provided with a first switch part SW1. To the connection path, an output part 10c of an electricity generator 10 is electrically connected more on a secondary battery side than the first switch part SW1. The connection path is provided with a second switch part SW2 is provided more on the secondary storage battery side than a connection point for the output part. A power supply controller determines whether the secondary storage battery is in an overdischarged state, and inhibits the first switch part SW1 and second switch part SW2 from being both closed on condition that it is determined that the second storage battery is in the overdischarged state.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a power supply control device mounted on a vehicle or the like.

  Conventionally, as can be seen in Patent Document 1 below, a power supply system including a first storage battery that is a lead storage battery, a second storage battery that is a lithium ion storage battery, and a semiconductor switch is known. The semiconductor switch is provided in a connection path that electrically connects these storage batteries. The power supply system further includes a generator that is electrically connected to the first storage battery side of the semiconductor switch in the connection path.

Japanese Patent No. 5234052

  In the power supply system described in Patent Document 1, when the second storage battery is not used for a long period of time, the second storage battery may be in an overdischarged state due to self-discharge of the second storage battery or the like. Conventionally, when such an overdischarge problem of a storage battery occurs in a vehicle, the lead storage battery can be removed from the vehicle, or can be charged by jumping a rescue vehicle or the like to start the engine. However, in the case of a lithium ion storage battery, since it is mounted as a battery pack that is an ASSY including the storage battery and peripheral circuits, there is no method for charging the storage battery from the outside, and the battery pack ASSY has to be replaced.

  Usually, when the amount of charge of a storage battery decreases, the terminal voltage decreases. For this reason, the 2nd storage battery used as the overdischarge state will be in the state in which the terminal voltage became a low state, and the terminal voltage of the 2nd storage battery fell greatly with respect to the terminal voltage of the 1st storage battery. In this state, when the semiconductor switch is switched from the open state to the closed state, an overcurrent may flow from the first storage battery to the second storage battery. In this case, the reliability of the part where overcurrent flows in the power supply system may be reduced.

  The present invention is applied to a system including a first storage battery and a second storage battery, and a main object thereof is to provide a power supply control device that can avoid an overcurrent from flowing from the first storage battery to the second storage battery.

  Hereinafter, means for solving the above-described problems and the operation and effects thereof will be described.

  The first invention is provided in a first storage battery (11), a second storage battery (12), and a connection path (LD) for electrically connecting the first storage battery and the second storage battery, and is in a closed state and an open state. A first switch unit (SW1) that switches between electrical continuity and cutoff by becoming one of the states, and an output unit that is electrically connected to the second storage battery side from the first switch unit in the connection path (10c), the generator (10) that outputs generated power from the output unit, and the connection path (N) between the output unit and the second storage battery side of the connection path, the closed state And a second switch unit (SW2) that switches between electrical conduction and interruption by being in any of the open states. According to a first aspect of the present invention, a determination unit (40) that determines whether or not the second storage battery is in an overdischarged state, and that the determination unit determines that the second storage battery is in an overdischarged state. As a condition, a prohibiting unit (40) for prohibiting both the first switch unit and the second switch unit from being closed is provided.

  In the above invention, the prohibiting unit prohibits both the first switch unit and the second switch unit from being closed on condition that the determination unit determines that the second storage battery is in an overdischarged state. The For this reason, it is prohibited that the second storage battery and the first storage battery are electrically connected, and an overcurrent can be avoided from flowing from the first storage battery to the second storage battery. As a result, a decrease in system reliability can be avoided.

  Furthermore, in the said invention, on the condition that it determines with the 2nd storage battery being an overdischarge state, a 1st switch part can also be made into a closed state and a 2nd switch part can also be made into an open state. Thereby, a 2nd storage battery can be electrically disconnected from the electrical system containing a 1st storage battery and a generator, and operation | movement and use of a normal electrical system can be continued among the electrical systems with which a system is equipped.

  According to a second aspect of the present invention, when the prohibition unit prohibits both the first switch unit and the second switch unit from being closed, the first switch unit is opened and the first switch unit is opened. The charging control part (40) which charges the said 2nd storage battery with the electric power generated by the said generator in the state which set the 2 switch part to the closed state is further provided.

  In the system to which the above invention is applied, in addition to the first switch unit, a second switch unit is provided on the second storage battery side of the connection path with the output unit of the generator in the connection path. For this reason, in the said invention, when prohibited by the prohibition part, a 2nd storage battery can be charged with the generated electric power of a generator in the state which made the 1st switch part the open state and made the 2nd switch part the closed state. Thereby, the charge amount of a 2nd storage battery can be increased and the 2nd storage battery can be used, without performing the operation | work which removes the 2nd storage battery determined to be an overdischarged state from a system.

  In the conventional system, which is the system described in Patent Document 1, the generator is electrically connected to the first storage battery side of the first switch unit in the connection path. For this reason, in the conventional system, when the second storage battery is charged with the generated power of the generator, it is necessary to close the first switch unit. However, when the first switch unit is switched to the closed state, an overcurrent may flow from the first storage battery to the overdischarged second storage battery. For this reason, in the conventional system, when the second storage battery is in an overdischarged state, it is necessary to remove the second storage battery from the system and replace it with a new second storage battery.

  In a third aspect, the system further includes an electrical load (14) electrically connected to the first storage battery side with respect to the first switch unit in the connection path.

  The system to which the invention is applied includes an electrical load that is electrically connected to the first storage battery side of the first switch unit in the connection path. For this reason, even if it is a case where the 1st switch part is made into an open state at the time of charge of the 2nd storage battery determined to be an overdischarge state, it replaces with a 2nd storage battery or a generator, and from the 1st storage battery. Power can be supplied to the electrical load. Therefore, it is possible to charge the second storage battery while securing the power supplied to the electric load.

  In a fourth aspect of the invention, the generator is configured such that the output voltage of the output unit can be adjusted, and the charging control unit gradually increases the output voltage of the output unit during charging of the second storage battery. It is something to be made.

  In the said invention, the output voltage of an output part is raised gradually at the time of charge of a 2nd storage battery. This is because when the second storage battery is in an overdischarged state, an overcurrent does not flow from the output of the generator to the second storage battery due to the difference between the terminal voltage of the second storage battery and the terminal voltage of the first storage battery. It is to do. Here, immediately after the start of charging of the second storage battery, the output voltage of the output unit of the generator is low, and the voltage of the electrical system including the generator and the second storage battery is low. For this reason, in the configuration in which the electrical load is electrically connected to the second storage battery side with respect to the first switch part in the connection path, immediately after the start of charging of the second storage battery, the electrical system including the generator and the second storage battery The voltage can be less than the lowest voltage that can guarantee the operation of the electrical load.

  In this regard, in the above-described invention, the electrical load is electrically connected to the first storage battery side of the first switch portion in the connection path. For this reason, immediately after charge of the 2nd storage battery, the 1st switch part is made into an open state, and electric power is supplied from the 1st storage battery to an electric load. Thereby, it can avoid that the voltage supplied to an electric load becomes less than the said minimum voltage. Therefore, the operation of the electric load can be guaranteed when the second storage battery is charged.

  In a fifth aspect of the invention, the generator is supplied with power, and a power generation control unit (10b) that adjusts the output voltage of the output unit based on an output voltage command value of the output unit instructed from the charge control unit. The power generation control unit is supplied with electric power from the first storage battery.

  In order to prevent an overcurrent from flowing from the output part of the generator to the second storage battery, the output voltage of the output part is gradually increased based on the output voltage command value when the second storage battery is charged. Here, in the configuration in which power is supplied from the second storage battery and the generator to the power generation control unit, immediately after the start of charging of the second storage battery, the voltage of the electrical system including the generator and the second storage battery causes the operation of the power generation control unit. It can be below the minimum voltage that can be guaranteed. In this case, there is a concern that the output voltage of the output unit cannot be adjusted. In order to cope with this problem, it is conceivable to increase the output voltage of the output unit. In this case, however, an overcurrent may flow from the output portion of the generator to the second storage battery.

  In this regard, in the above-described invention, power is supplied from the first storage battery to the power generation control unit. For this reason, it can avoid that the voltage supplied to a power generation control part becomes less than the said minimum voltage. Thereby, operation | movement of a power generation control part can be guaranteed and the output voltage of the output part of a generator can be adjusted appropriately.

  In a sixth aspect of the invention, the system includes an engine (20), the generator generates power when power is supplied from the engine, and the generator is supplied with power. Thus, the power generation control unit (10b) for adjusting the output voltage of the output unit based on the output voltage command value of the output unit instructed from the charge control unit, Electric power is supplied from the generator while the engine is driven.

  In the above-described invention, the power of the power generation control unit can be covered by the power generated by the generator while the engine is driven.

  In a seventh aspect, when the charge control unit determines that the charge amount of the first storage battery is below a lower limit value of an appropriate range, the first switch unit is closed prior to charging of the second storage battery. The first storage battery is charged with the generated power of the generator in a state where the second switch unit is in an open state.

  When the second storage battery is charged, if the charge amount of the first storage battery is insufficient, the power supplied from the first storage battery to the electric load may be insufficient. In this regard, in the above-described invention, when it is determined that the charge amount of the first storage battery is below the lower limit value of the appropriate range, the first switch portion is closed and the second switch is set prior to charging the second storage battery. The first storage battery is charged by the power generated by the generator with the switch portion in the open state. Then, the second storage battery is charged. For this reason, it is possible to avoid a shortage of power supplied from the first storage battery to the electric load during charging of the second storage battery.

  In an eighth aspect of the invention, when the charge control unit determines that the charge amount of the first storage battery falls below a lower limit value of an appropriate range during charging of the second storage battery, the first switch unit is switched to a closed state. In addition, the first storage battery is charged with the generated power of the generator while the second switch unit is switched to the open state.

  When the power supplied from the first storage battery to the electric load is large or the charging period of the second storage battery becomes long, the charge amount of the first storage battery becomes insufficient during charging of the second storage battery, The power supplied to the electrical load may be insufficient. In this regard, in the above invention, when it is determined that the charge amount of the first storage battery is below the lower limit value of the appropriate range during the charging of the second storage battery, the first switch unit is switched to the closed state and the second switch unit Is switched to the open state. In this state, the first storage battery is charged with the power generated by the generator. For this reason, it is possible to avoid a shortage of power supplied from the first storage battery to the electric load during charging of the second storage battery.

The whole block diagram of a vehicle-mounted power supply system. The flowchart which shows the procedure of a charging process. The time chart which shows the charge process in case the charge amount of lead acid battery is enough. The time chart which shows the charge process when the charge amount of a lead storage battery is insufficient.

  DESCRIPTION OF EXEMPLARY EMBODIMENTS Embodiments of the invention will be described below with reference to the drawings. A vehicle on which the power supply control device of this embodiment is mounted travels using an engine as a drive source and has a so-called idling stop function.

  As shown in FIG. 1, the in-vehicle power supply system includes a rotating electrical machine 10, a lead storage battery 11 as a first storage battery, a lithium ion storage battery 12 as a second storage battery, a starter 13, and various electric loads 14. The lead storage battery 11 is a well-known general-purpose storage battery. On the other hand, the lithium ion storage battery 12 is a high-performance storage battery that has higher output density and energy density than the lead storage battery 11 and has high resistance to frequent charging and discharging. In the present embodiment, the lead storage battery 11 has a storage capacity larger than that of the lithium ion storage battery 12. Moreover, in this embodiment, the rated voltage of the lead storage battery 11 is the same as or substantially the same as the rated voltage of the lithium ion storage battery 12.

  The positive electrode of the lithium ion storage battery 12 is connected to the positive electrode of the lead storage battery 11 via the connection path LD. The negative electrodes of the lead storage battery 11 and the lithium ion storage battery 12 are grounded.

  The rotating electrical machine 10 includes a power generation unit 10a, a power generation control unit 10b, and an output unit 10c that outputs the generated power of the power generation unit 10a. The power generation unit 10a includes a stator, a stator coil wound around the stator, a rotor, and a rotor coil wound around the rotor. The rotation shaft of the rotor is connected to the output shaft 20a of the engine 20 by a belt or the like. In the present embodiment, the rotating electrical machine 10 functions as a generator that generates power by rotating the output shaft 20a or the axle.

  The rotor is rotated by the power supplied from the output shaft 20a. In the power generation unit 10a, an alternating current is induced in the stator coil in accordance with the exciting current flowing in the rotor coil under a situation where the rotor rotates, and is converted into a direct current by a rectifier (not shown). The excitation current flowing through the rotor coil is adjusted by the power generation control unit 10b, so that the generated DC voltage is adjusted to the output voltage command value Vref. That is, the power generation control unit 10b controls the generated power output from the output unit 10c to the output voltage command value Vref. Power is supplied from the lead storage battery 11 to the power generation control unit 10b.

  The power supply system includes a first switch unit SW1 and a second switch unit SW2. In the present embodiment, the first switch unit SW1 is a semiconductor switch that is provided in the connection path LD and switches between electrical continuity and disconnection when in either the closed state or the open state. In the present embodiment, the first switch unit SW1 is configured by a pair of N-channel MOSFETs whose sources are connected to each other.

  In the connection path LD, the output unit 10c is electrically connected to the lithium ion storage battery 12 side of the first switch unit SW1. In the connection path LD, a second switch unit SW2 that is a semiconductor switch is provided closer to the lithium ion storage battery 12 than the connection point N with the output unit 10c. In the present embodiment, the second switch unit SW2 is configured by a pair of N-channel MOSFETs whose sources are connected to each other.

  A starter 13 is connected in parallel to the lead storage battery 11. The starter 13 performs cranking for applying an initial rotation to the output shaft 20 a of the engine 20 when electric power is supplied from the lead storage battery 11.

  An electric load 14 is connected in parallel to the lead storage battery 11. The electric load 14 includes a constant voltage required load that is required to be stable so that the voltage of the supplied power is substantially constant or varies at least within a predetermined range. Specific examples of the constant voltage required load include a navigation device, a headlight, and a blower fan of an air conditioner.

  The power supply system includes a first voltage detection unit 30 that detects a terminal voltage of the lead storage battery 11 and a first current detection unit 31 that detects a charge / discharge current flowing in the lead storage battery 11. The power supply system includes a second voltage detection unit 32 that detects a terminal voltage of the lithium ion storage battery 12 and a second current detection unit 33 that detects a charge / discharge current flowing through the lithium ion storage battery 12.

  The detection value of each detection part is input into the control apparatus 40 with which a power supply system is equipped. The control device 40 does not overcharge / discharge the start control of the engine 20, the power generation control for outputting the output voltage command value Vref to the power generation control unit 10b, and the charge rate (SOC) of the lead storage battery 11 and the lithium ion storage battery 12. Charge / discharge control is performed so as to adjust to an appropriate range. The appropriate range of the lead storage battery 11 is set to a predetermined range from the central value, specifically, for example, set to 90% ± 2%. Moreover, the appropriate range of the lithium ion storage battery 12 is specifically set to 30 to 80%, for example.

  The start control of the engine 20 includes the restart control of the engine 20 by the idling stop control in addition to the initial start control of the engine 20 in which the vehicle user's ignition switch ON operation is input. As is well known, the idling stop control is to automatically stop the engine 20 when a predetermined automatic stop condition is satisfied, and to restart the engine 20 when the predetermined restart condition is satisfied under the automatic stop state.

  Incidentally, in practice, a control device is provided individually corresponding to each component of the in-vehicle system such as the engine 20. In the present embodiment, the point that the control devices are individually provided is not a main part, and for convenience, these control devices are illustrated as a single control device 40.

  Next, a charging process at the time of starting the engine 20 executed by the control device 40 will be described.

  In the power supply system, the vehicle may be left for a long time, and the lithium ion storage battery 12 may not be used for a long time. In this case, the charge rate of the lithium ion storage battery 12 becomes close to the lower limit value of the appropriate range due to self-discharge of the lithium ion storage battery 12 or supply of dark current to a device electrically connected to the lithium ion storage battery 12. There may be an overdischarge state that is lower than the lower limit. The lithium ion storage battery 12 in an overdischarged state is in a state where the terminal voltage is low, and the degree of decrease in the terminal voltage of the lithium ion storage battery 12 relative to the terminal voltage of the lead storage battery 11 can be large. In this state, if the first switch unit SW <b> 1 is switched from the open state to the closed state, an overcurrent may flow from the lead storage battery 11 to the lithium ion storage battery 12. In this case, the reliability of the connection path LD, the lead storage battery 11 and the lithium ion storage battery 12 may be reduced.

  In order to solve this problem, it is conceivable to replace the lithium ion storage battery 12 in an overdischarged state with a new lithium ion storage battery or a used lithium ion storage battery with a sufficient charge amount. It is also conceivable that the lithium ion storage battery 12 in an overdischarged state is removed from the vehicle, and the removed lithium ion storage battery 12 is charged with a charging facility and mounted on the vehicle again. However, in this case, there are inconveniences such as time-consuming man-hours for replacement and an increase in replacement costs borne by the vehicle user.

  Therefore, in this embodiment, even when the lithium ion storage battery 12 is in an overdischarged state, a charging process is performed to make the lithium ion storage battery 12 usable again without removing the lithium ion storage battery 12 from the vehicle. Is called.

  FIG. 2 shows the procedure of the charging process. This process is repeatedly executed by the control device 40 at a predetermined cycle, for example.

  In this series of processing, first, in step S10, it is determined whether or not the ignition switch is turned on. If it is determined in step S10 that it is turned on, the process proceeds to step S12 to determine whether or not the value of the determination flag F is zero. The initial value of the determination flag F is set to 0.

  If it is determined in step S12 that the value of the determination flag F is 0, the process proceeds to step S14, where the first switch unit SW1 is closed and the second switch unit SW2 is opened.

  In a succeeding step S16, it is determined whether or not the engine 20 has been started. As a method for determining completion of starting of the engine 20, for example, a method of determining that the starting is completed when it is determined that the rotation speed of the output shaft 20a is equal to or higher than a predetermined rotation speed may be employed. When the start of the engine 20 is completed, the rotating electrical machine 10 can generate power with the power supplied from the output shaft 20a of the engine 20. In the present embodiment, the power generated by the rotating electrical machine 10 is directly supplied to the power generation control unit 10b while the engine 20 is being driven. Thereby, the electric power which should be supplied to the electric power generation control part 10b can be covered with the electric power generated of the rotary electric machine 10. FIG.

  If it is determined in step S16 that the engine 20 has been started, or if it is determined in step S12 that the value of the determination flag F is 1, the process proceeds to step S18. In step S18, it is determined whether or not the lithium ion storage battery 12 is in an overdischarged state. In this embodiment, when it determines with the terminal voltage VLi of the lithium ion storage battery 12 detected by the 2nd voltage detection part 32 being less than 1st determination value Vth1, it determines with the lithium ion storage battery 12 being an overdischarge state. . In the present embodiment, the first determination value Vth1 is set to the lower limit value of the appropriate range of the terminal voltage of the lithium ion storage battery 12. In the present embodiment, the process of step S18 corresponds to a determination unit.

  When the process of step S18 is first performed after the process shown in FIG. 2 is started, the second switch unit SW2 is opened and the lithium ion storage battery 12 is disconnected from the connection point N. At this time, when it is determined that the open-circuit voltage of the lithium ion storage battery 12 is equal to or lower than a predetermined value (for example, 10 V), the lithium ion storage battery 12 may be determined to be in an overdischarged state.

  If it is determined in step S18 that the overdischarge state is not established, the process proceeds to step S20, where the first switch unit SW1 and the second switch unit SW2 are allowed to be closed simultaneously. When the first switch unit SW1 and the second switch unit SW2 are in the closed state, when the rotating electrical machine 10 generates power, the generated power is supplied to the lead storage battery 11, the lithium ion storage battery 12, and the electrical load 14. . After the process of step S20 is completed, the process proceeds to step S22, and the value of the determination flag F is set to 1.

  On the other hand, if it is determined in step S18 that the battery is in an overdischarged state, the process proceeds to step S24, and the first switch unit SW1 and the second switch unit SW2 are prohibited from being closed simultaneously. In the present embodiment, the process in step S24 corresponds to a prohibition unit.

  In continuing step S26, it is determined whether the lead acid battery 11 has deteriorated. If it is determined in step S26 that the battery has deteriorated, it is desirable to perform a process of notifying the user of the deterioration by turning on a failure warning lamp or the like.

  When it determines with having not deteriorated in step S26, it progresses to step S28 and it is determined whether the charge amount of the lead storage battery 11 is enough. In this embodiment, when it determines with the terminal voltage VPb of the lead storage battery 11 detected by the 1st voltage detection part 30 being less than 2nd determination value Vth2, it determines with the charge amount of the lead storage battery 11 not being enough. In the present embodiment, the second determination value Vth2 is set to the lower limit value of the appropriate range of the terminal voltage of the lead storage battery 11. In addition, the said lower limit of the lead storage battery 11 is 12.5V, for example.

  Incidentally, as a method for determining that the charge amount of the lead storage battery 11 is sufficient, there is a method described below. Specifically, for example, it is determined that the terminal voltage when the lead storage battery 11 is charged with a predetermined current (for example, 5 A) is equal to or higher than the third determination value Vth3 (for example, 14 V) that is larger than the second determination value Vth2. In this case, there is a method for determining that the charge amount of the lead storage battery 11 is sufficient. Further, for example, when it is determined that the charging current to the lead storage battery 11 when charging at a predetermined voltage (for example, 14 V) is a predetermined value (for example, 5 A) or less, the charge amount of the lead storage battery 11 is determined to be sufficient. There is also a way to do it.

  When it determines with the charge amount of the lead storage battery 11 being sufficient in step S28, it progresses to step S30, makes 1st switch part SW1 an open state, and makes 2nd switch part SW2 a closed state.

  In continuing step S32, the lithium ion storage battery 12 is charged with the generated electric power output from the output part 10c of the rotary electric machine 10. FIG. In the present embodiment, when the lithium ion storage battery 12 is charged, a process of gradually increasing the output voltage command value Vref is performed until the output voltage command value Vref reaches a specified value. This is a process for avoiding an overcurrent flowing from the output unit 10 c to the lithium ion storage battery 12. In addition, the said prescribed value is set to the value higher than the rated voltage of the lithium ion storage battery 12 and the lead storage battery 11, for example. After the completion of the process of step S32, the value of the determination flag F is set to 1 in the subsequent step S34.

  On the other hand, when it determines with the charge amount of the lead storage battery 11 not being enough in step S28, it progresses to step S36, makes 1st switch part SW1 a closed state, and makes 2nd switch part SW2 an open state. In continuing step S38, the lead storage battery 11 is charged with the generated electric power output from the output part 10c of the rotary electric machine 10. FIG. In step S40, it is determined whether or not the terminal voltage VPb of the lead storage battery 11 is equal to or higher than the third determination value Vth3. If an affirmative determination is made in step S40, the process proceeds to step S42, and the value of the determination flag F is set to zero.

  Subsequently, the charging process when the engine 20 is started will be further described with reference to FIGS. 3 and 4.

  First, the charging process when the charge amount of the lead storage battery 11 at the completion of the start of the engine 20 is sufficient will be described using FIG. Here, FIG. 3 (a) shows the transition of the operation state of the ignition switch, FIG. 3 (b) shows the transition of the operating state of the starter 13, and FIG. 3 (c) shows the transition of the operating state of the engine 20. . FIGS. 3D and 3E show the transition of the operation state of the first and second switch units SW1 and SW2, and FIG. 3F shows the terminals of the lithium ion storage battery 12 detected by the second voltage detection unit 32. The transition of the voltage VLi is shown.

  In the illustrated example, when the ignition switch is turned on at time t1, the first switch unit SW1 is switched from the open state to the closed state. Thereafter, initial rotation is applied to the output shaft 20a of the engine 20 by the starter 13, and combustion control of the engine 20 is started, so that it is determined that the start of the engine 20 is completed at time t2. In the present embodiment, it is assumed that the lead storage battery 11 has a storage amount necessary for driving the starter 13 when the engine 20 is started.

  Thereafter, when the lithium ion storage battery 12 is determined to be in an overdischarged state, after the start of the engine 20 is completed, the first switch unit SW1 and the second switch unit SW2 are both closed before the first switch unit SW1 is closed. It is prohibited that both the switch unit SW1 and the second switch unit SW2 are closed.

  Thereafter, at time t3, the first switch unit SW1 is switched from the closed state to the open state, and the second switch unit SW2 is switched from the open state to the closed state. Then, charging of the lithium ion storage battery 12 is started by the electric power generated by the rotating electrical machine 10. By charging the lithium ion storage battery 12, it is determined that the terminal voltage VLi of the lithium ion storage battery 12 has reached the first determination value Vth1 at time t4. For this reason, it is determined that the overdischarge state of the lithium ion storage battery 12 has been eliminated, and it is permitted that both the first switch unit SW1 and the second switch unit SW2 are closed. Thereby, 1st switch part SW1 is switched to a closed state.

  Next, the charging process when the charge amount of the lead storage battery 11 at the completion of the start of the engine 20 is insufficient will be described using FIG. 4A to 4E correspond to FIGS. 3A to 3F, and FIG. 4F shows the lead detected by the first voltage detector 30. FIG. The transition of the terminal voltage VPb of the storage battery 11 is shown. In FIG. 4F, illustration of a decrease in the terminal voltage VPb due to driving of the starter 13 is omitted.

  In the illustrated example, it is determined that the lithium ion storage battery 12 is in an overdischarged state after time t2. Thereafter, prior to charging of the lithium ion storage battery 12, charging of the lead storage battery 11 is started by power generated by the rotating electrical machine 10 at time t3. It is determined by charging of the lead storage battery 11 that the terminal voltage VPb of the lead storage battery 11 has reached the third determination value Vth3 at time t4. Thereafter, it is determined that the charge amount of the lead storage battery 11 is sufficient. Then, charging of the lithium ion storage battery 12 is started by the generated power of the rotating electrical machine 10 in a state where the first switch unit SW1 is switched to the open state and the second switch unit SW2 is switched to the closed state. Then, at time t5, it is determined that the overdischarge state of the lithium ion storage battery 12 has been eliminated, and both the first switch unit SW1 and the second switch unit SW2 are permitted to be closed. Thereby, 1st switch part SW1 is switched to a closed state.

  In addition, when the power supplied from the lead storage battery 11 to the electric load 14 is large or the charging period of the lithium ion storage battery 12 becomes long, the terminal voltage of the lead storage battery 11 is being charged during the charging of the lithium ion storage battery 12 by the charging process. VPb can be less than the second determination value Vth2. Here, according to the charging process shown in FIG. 2, when it is determined in step S <b> 28 that the terminal voltage VPb of the lead storage battery 11 has become less than the second determination value Vth <b> 2 during the charging of the lithium ion storage battery 12, step S <b> 36. As a result, the first switch unit SW1 is switched to the closed state and the second switch unit SW2 is switched to the open state. In this state, the lead storage battery 11 is charged with the power generated by the rotating electrical machine 10, and then the charging of the lithium ion storage battery 12 is started again. For this reason, it is possible to avoid a shortage of power supplied from the lead storage battery 11 to the electric load 14 during charging of the lithium ion storage battery 12.

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

  When it was determined that the lithium ion storage battery 12 is in an overdischarged state, the first switch unit SW1 and the second switch unit SW2 are both prohibited from being closed. For this reason, it can avoid that an overcurrent flows from the lead storage battery 11 to the lithium ion storage battery 12 determined to be in an overdischarged state. Thereby, the fall of the reliability of a power supply system can be avoided.

  When it is determined that the lithium ion storage battery 12 is in an overdischarged state, the lithium ion storage battery 12 is generated by the electric power generated by the rotating electrical machine 10 with the first switch unit SW1 in the open state and the second switch unit SW2 in the closed state. Charged. For this reason, without performing the operation | work which removes the lithium ion storage battery 12 determined to be an overdischarge state from a vehicle, the charge amount of the lithium ion storage battery 12 is increased in the state with which the vehicle was equipped, and the lithium ion storage battery 12 is used. It can be restored to a possible state.

  In the connection path LD, the electrical load 14 was connected to the lead storage battery 11 side from the first switch unit SW1. For this reason, even when the first switch unit SW1 is in an open state during charging of the lithium ion storage battery 12 determined to be in an overdischarged state, power is supplied from the lead storage battery 11 to the electrical load 14. it can. Therefore, the charging process of the lithium ion storage battery 12 can be performed while avoiding that the voltage supplied to the electric load 14 becomes less than the minimum voltage at which the operation of the electric load 14 can be guaranteed.

  Further, in the configuration in which the output voltage command value Vref is gradually increased during charging of the lithium ion storage battery 12, the power generation control unit 10b is connected to the lead storage battery 11 side of the first switch unit SW1 in the connection path LD. Thereby, it can avoid that the voltage supplied to the electric power generation control part 10b becomes less than the minimum voltage which can guarantee the operation | movement of the electric power generation control part 10b.

(Other embodiments)
The above embodiment may be modified as follows.

  The method for determining whether or not the lithium ion storage battery 12 is in an overdischarged state is not limited to that described in the above embodiment. For example, when it is determined that the charging rate of the lithium ion storage battery 12 is less than the lower limit of the appropriate range, the lithium ion storage battery 12 may be determined to be in an overdischarged state. The charging rate of the lithium ion storage battery 12 may be calculated based on, for example, the integrated value of the charge / discharge current of the lithium ion storage battery 12 detected by the second current detection unit 33.

  Further, as a method for determining whether or not the lithium ion storage battery 12 is in an overdischarged state, for example, a determination method based on the difference between the terminal voltage VPb of the lead storage battery 11 and the terminal voltage VLi of the lithium ion storage battery 12 may be used. Specifically, when it is determined that the value obtained by subtracting the terminal voltage VLi of the lithium ion storage battery 12 from the terminal voltage VPb of the lead storage battery 11 is less than a predetermined value (> 0), the lithium ion storage battery 12 is in an overdischarged state. Can be determined.

  Furthermore, a method for determining whether or not the lithium ion storage battery 12 is in an overdischarged state is not limited to using a detected value such as a terminal voltage. For example, a method may be used in which it is determined that the lithium ion storage battery 12 is in an overdischarged state when it is determined that the elapsed time since the power supply system was last used has become a predetermined time or more.

  -In step S28 of FIG. 2, as a determination method of whether the charge amount of the lead storage battery 11 is enough, it is not restricted to what was demonstrated by the said embodiment. For example, when it is determined that the charge rate (SOC) of the lead storage battery 11 is less than the lower limit value of the appropriate range, it may be determined that the charge amount of the lead storage battery 11 is not sufficient. The lower limit value of the appropriate range is set to 88% (= 90% -2%), for example. Moreover, the charge rate of the lead storage battery 11 should just be calculated based on the integrated value of the charging / discharging current of the lead storage battery 11 detected by the 1st electric current detection part 31, for example.

  In step S28 executed during the period when the lithium ion storage battery 12 is charged by the process of step S32 in FIG. 2, the threshold value for determining that the charge amount of the lead storage battery 11 is sufficient is the second determination. The value Vth2 may be switched to another value. Specifically, for example, the second determination value Vth2 may be switched to a value that is larger than the second determination value Vth2 and smaller than the third determination value Vth3.

  In the above embodiment, the first storage battery is the lead storage battery 11 and the second storage battery is the lithium ion storage battery 12. However, the present invention is not limited to this. Both the first storage battery and the second storage battery may be the same type of storage battery. In addition, as a kind of storage battery, storage batteries of types other than a lead storage battery and a lithium ion storage battery may be sufficient.

  -In the connection path | route LD, the structure by which the electrical load is connected to the connection point N side rather than 1st switch part SW1 may be sufficient. Here, as an electrical load connected to the connection point N side, for example, an electrical load that does not require a sufficient supply of power during charging of the lithium ion storage battery 12 in an overdischarged state, or an effect on vehicle travel And an electric load that does not need to operate during charging of the lithium ion storage battery 12 in an overdischarged state.

  -When charging the lithium ion storage battery 12 in an overdischarged state, the output voltage command value Vref may be gradually increased so that the charging current of the lithium ion storage battery 12 becomes a predetermined current or less.

  The first switch unit SW1 and the second switch unit SW2 are not limited to semiconductor switches configured by MOSFETs, and for example, semiconductor switches configured by thyristors or solid state relays may be used.

  DESCRIPTION OF SYMBOLS 10 ... Rotary electric machine, 11 ... Lead storage battery, 12 ... Lithium ion storage battery, 40 ... Control apparatus, LD ... Connection path, SW1 ... 1st switch part, SW2 ... 2nd switch part.

Claims (8)

A first storage battery (11);
A second storage battery (12);
A first switch unit (SW1) that is provided in a connection path (LD) that electrically connects the first storage battery and the second storage battery and switches between electrical continuity and disconnection by being in a closed state or an open state. )When,
A generator (10) having an output part (10c) electrically connected to the second storage battery side from the first switch part in the connection path, and outputting generated power from the output part;
A second switch portion (on the connection path) that is provided closer to the second storage battery than the connection point (N) with the output portion, and switches between electrical continuity and disconnection by being in a closed state or an open state ( SW2), and a system comprising:
A determination unit (40) for determining whether or not the second storage battery is in an overdischarged state;
A prohibition unit that prohibits both the first switch unit and the second switch unit from being closed on the condition that the determination unit determines that the second storage battery is in an overdischarged state ( 40).   When the prohibition unit prohibits both the first switch unit and the second switch unit from being closed, the first switch unit is opened and the second switch unit is closed. The power supply control device according to claim 1, further comprising a charge control unit (40) that charges the second storage battery with the generated power of the generator in the state described above.   The power supply control device according to claim 2, wherein the system further includes an electric load (14) electrically connected to the first storage battery side with respect to the first switch unit in the connection path. The generator is capable of adjusting the output voltage of the output unit,
The power supply control device according to claim 3, wherein the charging control unit gradually increases an output voltage of the output unit during charging of the second storage battery. The generator has a power generation control unit (10b) that adjusts the output voltage of the output unit based on an output voltage command value of the output unit that is instructed by the charge control unit by being supplied with power. ,
The power supply control device according to claim 4, wherein electric power is supplied from the first storage battery to the power generation control unit. The system includes an engine (20),
The generator generates power when power is supplied from the engine,
The generator has a power generation control unit (10b) that adjusts the output voltage of the output unit based on an output voltage command value of the output unit that is instructed by the charge control unit by being supplied with power. ,
The power supply control device according to claim 4 or 5, wherein the power generation control unit is supplied with electric power from the generator in a state where the engine is driven.   When it is determined that the charge amount of the first storage battery is below the lower limit value of the appropriate range, the charge control unit closes the first switch unit and charges the second switch prior to charging the second storage battery. The power supply control device according to any one of claims 3 to 6, wherein the first storage battery is charged with the generated power of the generator in a state where the switch unit is in an open state.   When the charge control unit determines that the charge amount of the first storage battery falls below a lower limit value of an appropriate range during the charging of the second storage battery, the charge control unit switches the first switch unit to a closed state and the second switch The power supply control device according to any one of claims 3 to 7, wherein the first storage battery is charged with the generated power of the generator in a state where the unit is switched to an open state.

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