JP2013255372A - Power system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To perform an appropriate monitoring process related to charging/discharging a first storage battery and a second storage battery by determining a correct current flowing through each storage battery or connection switch.SOLUTION: A power system includes an alternator 10, a lead-acid battery 20, a lithium ion storage battery 30, electrical loads 41-43, a MOS switch 50, and an SMR switch 60. In reference to a junction X1 on a feeder 15 with a battery current IPb, a switch current IMOS and a load current IR1, an ECU 70 regards the battery current IPb as a specific current and the others as nonspecific currents, and calculates a value of the battery current IPb in a plurality of states in which the battery current IPb takes different values. Specifically, the ECU 70 acquires values of the nonspecific currents and uses the values of the nonspecific currents for calculating the battery current IPb on the basis of equality between the sum of inflowing currents and the sum of outflowing currents at the junction X1. A gain of an output characteristic of a Pb current sensor 21 is calculated on the basis of the battery current IPb.

Description

  The present invention relates to a power supply system that includes a first storage battery, a second storage battery, and a generator that charges both the storage batteries, and is used as, for example, a vehicle power supply system.

  In a power supply system used for a vehicle or the like, in order to protect a control board or a storage battery, an operation such as immediately cutting off a current when a current value greater than an allowable current value flows is required. In addition, in the capacity integration function of the storage battery used in the fuel saving technology, it is necessary to always integrate the current value charged / discharged to the storage battery, and to permit and use the storage battery within a predetermined capacity range. In such a case, it is required that the current value be detected correctly. That is, if the storage battery is continuously used while the current value is erroneously detected, there is a possibility of causing early deterioration or the like, and it is required to grasp whether or not the detected current value is correct.

  In addition, for example, a plurality of storage batteries composed of a lead storage battery and a lithium ion storage battery, a generator for charging both storage batteries, and a connection switch for electrically connecting both storage batteries are connected according to the storage state of each storage battery. In the power supply system in which the on / off of the switch is controlled, by properly using these two storage batteries, the fuel saving effect in the vehicle, the protection effect of the storage battery, and the like can be obtained.

  In the above power supply system having a plurality of storage batteries, for example, if the current (Pb current) on the lead storage battery side is not correctly detected and the SOC of the lead storage battery is erroneously calculated as a high SOC value, there is a concern that the fuel consumption may be deteriorated. Is done. In addition, if the SOC of the lead-acid battery is erroneously calculated as a low SOC value, in a configuration in which the engine is restarted by the starter motor using the lead-acid battery as a power source, the system having an automatic engine stop / restart function automatically There is a disadvantage that the opportunity to automatically stop the engine after the stop is reduced. Furthermore, if the current (Li current) on the lithium ion storage battery side is not correctly detected, overcharge and overdischarge occur in the lithium ion storage battery, causing problems such as early deterioration of the storage battery.

  As a technique for improving the accuracy of current detection, a method for correcting the output of a current sensor for detecting a current flowing through a storage battery is known. For example, in the technique disclosed in Patent Document 1, when the output voltage of the generator connected to the storage battery is the open-circuit voltage of the storage battery, the detected current value of the current sensor is stored as an offset value, The detection current value of the current sensor is corrected based on the offset value.

JP 2007-57399 A

  However, in a configuration in which a plurality of storage batteries such as lead storage batteries and lithium ion storage batteries are provided and these storage batteries are properly used, the decrease in current detection accuracy is caused not only by the offset, but also for each storage battery. Depending on the mode of use and the like, it may occur due to different circumstances. Considering these points, it is considered that there is room for improvement in the technology for monitoring the power supply system.

  The present invention has been made to solve the above problems, and in a power supply system including a first storage battery, a second storage battery, and a connection switch for connecting and disconnecting both the storage batteries, a current flowing through each storage battery and the connection switch. It is an object of the present invention to correctly grasp the situation, and by extension, appropriately perform monitoring processing relating to charging and discharging of the first storage battery and the second storage battery.

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

  The power supply system according to claim 1 is an electrical connection between a generator (10), a first storage battery and a second storage battery (20, 30) connected in parallel to the generator, and both storage batteries. A connection switch (50) provided on the connection line (15) for switching between conduction and interruption between the first storage battery and the second storage battery, and an electrical load connected to both sides of the connection line across the connection switch (42, 43).

  And, based on the relationship in which the value of the supply current supplied from the generator and the storage batteries to the electrical load matches the value of the consumption current consumed by the electrical load, at least one of the storage batteries Current calculation processing for calculating at least one of the storage battery current and the switch current flowing through the connection switch in a plurality of states in which the storage battery current flowing through the current is different from each other, and the current calculated by the current calculation processing The power supply control means (70, 80) which implements the monitoring process regarding charging / discharging of at least any one of a said 1st storage battery and a said 2nd storage battery using a value is characterized by the above-mentioned.

  In the configuration in which the first storage battery and the second storage battery that are connected in parallel to the generator are provided, a connection switch is provided in the connection line that connects both storage batteries, and an electrical load is connected to the connection line. Electric power is supplied to the electric load using any one of the generator, the first storage battery, and the second storage battery as a power supply source. In this case, the value of the supply current supplied from the generator and both storage batteries to the electric load and the value of the consumption current consumed by the electric load (each load in the driving state) match, and such current The balance relationship (the relationship in which the current value on the supply side = the current value on the consumption side) is established regardless of the power generation state of the generator and the switching state of the connection switch. That is, the above current balance relationship is maintained even in a plurality of states in which the storage battery currents flowing through the first storage battery and the second storage battery have different values.

  In this case, using the fact that the current balance relationship is maintained even if the storage battery current values are different from each other, even if the usage form of each storage battery changes with the switching of the connection switch, a plurality of The actual state of the storage battery current and the switch current can be grasped by comparison in the above state. For example, it may be monitored whether or not other currents have been appropriately changed as the value of the storage battery current changes. Therefore, the monitoring process regarding charge / discharge of the first storage battery or the second storage battery can be appropriately performed by grasping such a current state.

The figure which shows schematic structure of the power supply system in embodiment of invention. The VI line figure which shows the output characteristic of a Pb current sensor. The figure which shows the flow of each electric current in the state which switched on / off of the MOS switch. The flowchart which shows a gain calculation process. The figure which shows the flow of each electric current in the state which switched on / off of the SMR switch. The figure which shows schematic structure of a power supply system in 2nd Embodiment. The flowchart which shows a gain calculation process. The figure which shows the flow of each electric current in the state which switched on / off of the MOS switch and the SMR switch in 3rd Embodiment. The flowchart which shows the abnormality determination process of an electric current detection system. The figure which shows the flow of each electric current in the state which switched on / off of the SMR switch in 4th Embodiment. The flowchart which shows a system abnormality determination process. The figure which shows schematic structure of the power supply system in 5th Embodiment. The flowchart which shows the abnormality determination process of a bypass relay. The flowchart which shows the abnormality determination process of a bypass relay. The flowchart which shows the abnormality determination process of a bypass relay.

  Hereinafter, embodiments embodying the present invention will be described with reference to the drawings. In the following embodiments, parts that are the same or equivalent to each other are denoted by the same reference numerals in the drawings, and the description of the same reference numerals is used.

(First embodiment)
The power supply system of the present embodiment is an on-vehicle power supply system mounted on a vehicle, and the vehicle travels using an engine (internal combustion engine) as a drive source. When the engine is started, initial rotation is applied to the engine by driving the starter motor.

  As shown in FIG. 1, this power supply system includes an alternator 10 (generator), a lead storage battery 20, a lithium ion storage battery 30, various electric loads 41, 42, 43, a MOS switch 50 as a connection switch, and a storage battery switch. An SMR switch 60 is provided. The lead storage battery 20 and the lithium ion storage battery 30 constitute a first storage battery and a second storage battery. The lead storage battery 20, the lithium ion storage battery 30, and the electrical loads 41 to 43 are electrically connected in parallel to the alternator 10 by a power supply line 15 as a connection line. The power supply line 15 forms a mutual power supply path for each of the electrical elements.

  The lead storage battery 20 is a well-known general-purpose storage battery. On the other hand, the lithium ion storage battery 30 is a high-density storage battery having a higher output density and energy density than the lead storage battery 20. The lithium ion storage battery 30 is constituted by an assembled battery formed by connecting a plurality of single cells in series. The storage capacity of the lead storage battery 20 is set larger than the storage capacity of the lithium ion storage battery 30.

  The MOS switch 50 is a semiconductor switch made of a MOSFET, and is provided between the alternator 10 and the lead storage battery 20 and the lithium ion storage battery 30. The MOS switch 50 functions as a switch that switches conduction (ON) and interruption (OFF) of the lithium ion storage battery 30 with respect to the alternator 10 and the lead storage battery 20.

  On / off of the MOS switch 50 is controlled by the ECU 70 (electronic control unit). That is, the ECU 70 switches the MOS switch 50 between the on operation (conduction operation) and the off operation (shut-off operation). It can be said that the MOS switch 50 made of MOSFET necessarily has a rectifying means due to its internal structure. That is, the internal circuit of the MOS switch 50 is equivalent to a circuit in which a semiconductor switch unit and a parasitic diode (rectifying means) are connected in parallel.

  Similarly to the MOS switch 50, the SMR switch 60 is configured by a semiconductor switch made of a MOSFET, and is provided between the connection point (X2 in the figure) of the MOS switch 50 and the electric load 43 and the lithium ion storage battery 30. It has been. The SMR switch 60 functions as a switch that switches between conduction and interruption of the lithium ion storage battery 30 with respect to the connection point of the MOS switch 50 and the electric load 43.

  Switching of the SMR switch 60 between the on operation (conduction operation) and the off operation (shut-off operation) is performed by the ECU 70. The SMR switch 60 is an emergency opening / closing means, and is normally kept in an on state by an on signal being constantly output from the ECU 70. In an emergency illustrated below, the output of the on signal is stopped and the SMR switch 60 is turned off. By turning off the SMR switch 60, overcharging and overdischarging of the lithium ion storage battery 30 are avoided.

  For example, when the regulator provided in the alternator 10 breaks down and the set voltage Vreg becomes abnormally high, there is a concern that the lithium ion storage battery 30 may be overcharged. In this case, the SMR switch 60 is turned off. Moreover, when the lithium ion storage battery 30 cannot be charged due to the failure of the alternator 10 or the failure of the MOS switch 50, there is a concern that the lithium ion storage battery 30 is overdischarged. Also in this case, the SMR switch 60 is turned off.

  The SMR switch 60 may be configured using a normally open electromagnetic relay. In this case, even if the ECU 70 breaks down and the operation of the SMR switch 60 cannot be controlled, the SMR switch 60 is automatically opened and the conduction is cut off.

  The lithium ion storage battery 30, the switches 50 and 60, and the ECU 70 are integrated by being accommodated in a casing (accommodating case) and configured as a battery unit U. The ECU 70 in the battery unit U is connected to an ECU 80 (electronic control device) outside the battery unit. That is, these ECUs 70 and 80 are connected by a communication network such as CAN and can communicate with each other, and various data stored in the ECUs 70 and 80 can be shared with each other.

  A Pb current sensor 21 having, for example, a Hall element is provided in a current path through which a current flowing through the lead storage battery 20 passes. The Pb current sensor 21 is a current detection unit that converts the detected current into a voltage and outputs the voltage. A voltage signal output from the Pb current sensor 21 is input to the ECU 80. The power supply line 15 is provided with a voltage detection unit 22 on the lead storage battery 20 side of the MOS switch 50. The voltage detection unit 22 detects the positive terminal voltage of the lead storage battery 20. The voltage detection unit 22 corresponds to a voltage detection unit that detects a voltage at a later-described branch point X1.

  The load indicated by reference numeral 43 among the electric loads 41 to 43 is a constant voltage required electric load in which the voltage of the supplied power is substantially constant or the voltage fluctuation is within a predetermined range and is required to be stable. The MOS switch 50 is electrically connected to the lithium ion storage battery 30 side. Thereby, the power supply to the electric load 43 which is a constant voltage required electric load is mainly shared by the lithium ion storage battery 30.

  Specific examples of the electric load 43 include a navigation device and an audio device. For example, when the voltage of the supplied power is not constant but fluctuates greatly, or fluctuates greatly beyond the predetermined range, the voltage instantaneously drops below the minimum operating voltage, and the navigation device etc. This causes a malfunction that resets the operation. Therefore, the electric power supplied to the electric load 43 is required to be stable at a constant value where the voltage does not drop below the minimum operating voltage.

  The load indicated by reference numeral 41 among the electric loads 41 to 43 is a starter motor for starting the engine, and the load indicated by reference numeral 42 is a general load other than the electric load 43 (constant voltage required electric load) and the starter motor 41. Is an electrical load. Specific examples of the electric load 42 include wipers such as a headlight and a front windshield, a blower fan for an air conditioner, and a defroster heater for a rear windshield. The starter motor 41 and the electric load 42 are electrically connected to the lead storage battery 20 side with respect to the MOS switch 50. As a result, the lead storage battery 20 mainly shares power supply to the starter motor 41 and the electric load 42.

  The electric loads 42 and 43 are connected to the ECU 80 via a communication network, and the on / off state and power usage information of the electric loads 42 and 43 are transmitted to the ECU 80 via the communication network. In addition, when another ECU for managing the driving of each of the electric loads 42 and 43 is provided, information regarding the driving of the electric loads 42 and 43 may be transmitted from the ECU to the ECU 80. The ECU 80 corresponds to information acquisition means.

  The alternator 10 generates electric power using rotational energy of an engine crankshaft (output shaft). Since the configuration and the like of the alternator 10 are well known, they are not illustrated here and will be described briefly. When the rotor of the alternator 10 is rotated by the crankshaft, an alternating current is induced in the stator coil according to the exciting current flowing in the rotor coil, and is converted into a direct current by a rectifier. Then, the regulator adjusts the exciting current flowing through the rotor coil so that the voltage of the generated direct current is adjusted to the set voltage Vreg. The ECU 80 controls the alternator 10 with respect to the regulator.

  The electric power generated by the alternator 10 is supplied to various electric loads 41 to 43 and also supplied to the lead storage battery 20 and the lithium ion storage battery 30. When the drive of the engine is stopped and the alternator 10 is not generating power, power is supplied from the lead storage battery 20 and the lithium ion storage battery 30 to the electric loads 41 to 43. The amount of discharge from the lead storage battery 20 and the lithium ion storage battery 30 to the electric loads 41 to 43 and the amount of charge from the alternator 10 to each storage battery 20, 30 are the SOC (State of charge) of each storage battery 20, 30. The ratio of the actual charge amount to the charge amount) is controlled to be in a range (appropriate range) where overcharge / discharge is not caused. That is, the set voltage Vreg is adjusted by the ECU 80 and the operation of the MOS switch 50 is controlled by the ECU 70 so that excessive charging / discharging does not occur as described above.

  Further, in the present embodiment, deceleration regeneration is performed in which the alternator 10 is generated by the regenerative energy of the vehicle and charged to both the storage batteries 20 and 30 (mainly the lithium ion storage battery 30). This deceleration regeneration is performed when conditions such as that the vehicle is in a decelerating state and that fuel injection to the engine is cut off are satisfied.

  Here, since the storage batteries 20 and 30 are connected in parallel, when charging is performed by the alternator 10, the alternator 10 can be used for the storage battery having a lower terminal voltage if the MOS switch 50 is turned on. The electromotive current flows in. On the other hand, when power is supplied (discharged) to the electric loads 42 and 43, if the MOS switch 50 is turned on at the time of non-power generation, the storage battery on the higher terminal voltage side is discharged to the electric load. .

  By the way, at the time of regenerative charging, the lithium ion storage battery 30 is charged with priority over the lead storage battery 20 so that the terminal voltage of the lithium ion storage battery 30 becomes lower than the terminal voltage of the lead storage battery 20. It has become. Further, at the time of discharging, the lithium ion storage battery 30 is discharged from the lithium ion storage battery 30 to the electric load 43 in preference to the lead storage battery 20 so that the terminal voltage of the lithium ion storage battery 30 becomes higher than the terminal voltage of the lead storage battery 20. It has become so. These settings can be realized by setting the open circuit voltage and internal resistance value of both storage batteries 20 and 30. The open circuit voltage can be set by selecting the positive electrode active material, the negative electrode active material and the electrolyte of the lithium ion storage battery 30. This is possible.

  The vehicle according to the present embodiment automatically stops the engine when a predetermined automatic stop condition is satisfied, and automatically restarts the engine when the predetermined restart condition is satisfied while the engine is automatically stopped. The ECU 80 has a stop function, and idle stop control is performed by the ECU 80. In the idling stop control, when the engine is automatically stopped, the MOS switch 50 is turned on (conducted) by the ECU 70 in order to charge (regenerate) the lithium ion storage battery 30 in the process of decreasing the engine speed. When the engine is restarted, the ECU 70 turns off (cuts off) the MOS switch 50 in order to drive the starter (electric load 41) by the lead storage battery 20 while the lead storage battery 20 and the lithium ion storage battery 30 are electrically disconnected. ) Is operated to the state.

In the electrical configuration shown in FIG. 1, X1 on the feeder line 15 is a branch point at which the feeder line 15 branches to the lead storage battery 20 side, the MOS switch 50 side, and the electrical load 42 side. In this case, in the current path including the branch point X1, assuming that the battery current flowing on the lead storage battery 20 side is IPb, the switch current flowing on the MOS switch 50 side is IMOS, and the load current flowing on the electric load 42 side is IR1, each of these currents Kirchhoff's current law holds. Therefore, if the battery current IPb and the load current IR1 are inflow currents with respect to the branch point X1, and the switch current IMOS is the outflow current with respect to the branch point X1, the following relational expression (1) of the current balance is established.
IR1 + IPb = IMOS (1)
According to the above equation (1), if two values of the currents IR1, IPb, and IMOS at the branch point X1 are known, the remaining one value can be calculated. The relational expression (1) always holds even if the value of each current changes, and the relational expression for each current included in the relational expression (1) even in a plurality of states in which the values of each current are different. Calculation based on (1) is possible.

  The actual value of each current included in the relational expression (1) can be acquired by sensing (detection) or estimation (calculation), and a method for acquiring the value of each current will be described.

  As described above, the Pb current sensor 21 is provided in the current path of the lead storage battery 20, and the ECU 80 calculates the battery current IPb based on the detection signal of the Pb current sensor 21. Further, the MOS switch 50 is provided with a current detection unit 51 that detects a current flowing through the switch 50, and the SMR switch 60 is provided with a current detection unit 61 that detects a current flowing through the switch 60. These current detectors 51 and 61 are provided integrally with each of the switches 50 and 60, convert the current into a voltage signal, and output the voltage signal to the ECU 70. In the ECU 70, the value of the switch current IMOS and the value of the battery current ILi are calculated based on the detection signals of the current detection units 51 and 61, respectively.

  The load current IR1 can be detected by a current sensor if a current sensor is added to the current path. However, in the present embodiment, the load current IR1 is calculated based on the current balance relationship at the branch point X1. That is, since the above relational expression (1) is established at the branch point X1, the battery current IPb and the switch current IMOS are calculated from the current detection signals, respectively, and are substituted into the relational expression (1) to obtain the load. The current IR1 is calculated.

  In this embodiment, among the currents included in the relational expression (1), the battery current IPb is set as a specific current, and the switch current IMOS and the load current IR1 other than the battery current IPb are set as non-specific currents. Then, the battery current IPb value and the voltage value at the branch point X1 are respectively calculated under a plurality of states where the battery current IPb values are different from each other, and the gain α of the output characteristic in the Pb current sensor 21 is calculated. It is said. At this time, in particular, the actual value of the battery current IPb is calculated by substituting the actual value of the non-specific current (IMOS, IR1) into the relational expression (1), and the gain α is calculated using the actual value. A reduction in accuracy of current value calculation due to a difference between an actual sensor output characteristic and a predetermined sensor output characteristic recognized on the ECU 80 side is suppressed.

  FIG. 2 is a V-I diagram showing the output characteristics of the Pb current sensor 21. In FIG. 2, a broken line indicates a predetermined sensor output characteristic recognized on the ECU 80 side, and a solid line indicates an actual sensor output characteristic (actual characteristic).

  The output characteristics of the Pb current sensor 21 are generally expressed by a linear line. In the Pb current sensor 21, the current is converted into a voltage and output, but the sensor output characteristics are shifted as shown in the figure. There may be. In this case, for example, if the battery current flowing through the lead storage battery 20 is A1, the sensor output voltage becomes V1 by current-voltage conversion. However, if the predetermined output characteristics are different from the actual characteristics as shown in the figure, The ECU 80 recognizes the battery current as A1 ′ (point P1 in the figure). Therefore, in this embodiment, an operating point (point P2 in the figure) indicating the relationship between the actual current and voltage in the Pb current sensor 21 is obtained, and the gain α is calculated using the operating point. Then, the inclination of the sensor output characteristic is corrected using the gain α.

  The switching of the state when the specific current (battery current IPb) is estimated will be described with reference to FIG. Here, a configuration in which the battery current IPb is made different by switching on / off of the MOS switch 50 will be described. FIG. 3 illustrates numerical values of the respective currents. In FIG. 3, the alternator 10 is not shown because it is in a non-power generation state. Moreover, since it is not at the time of the start by starter drive, illustration of the electric load 41 (starter motor) is also abbreviate | omitted.

  In FIG. 3A, the MOS switch 50 is turned off (cut off) and the SMR switch 60 is turned on (conducted), and current flows as shown in the figure. Here, since MOS switch 50 = off, IMOS = 0A, and further, from the relationship of current balance, IPb = −IR1 (= −4A) at branch point X1. In this state, the value of the battery current IPb is calculated from the detection signal of the Pb current sensor 21, and the value of the load current IR1 is calculated from the IPb value.

  In FIG. 3B, the MOS switch 50 is switched from OFF to ON while the SMR switch 60 is maintained in the ON state. As a result, the battery current IPb changes. At this time, since IR1 = 4A and IMOS = 7A at the branch point X1, IPb = 3A in view of the current balance. This IPb value is calculated by the above relational expression (1).

  In the state of FIG. 3B, compared with the state of FIG. 3B, the value of the switch current IMOS is changed from 0A to 7A while the value of the load current IR1 remains unchanged. The change amount ΔIMOS of the IMOS should match the IPb change amount from the IPb value with reference to the value of the battery current IPb calculated by the ECU in the state (a). In FIG. “+ ΔIMOS (= 7 A)” is the IPb value when the MOS switch 50 is turned on. The current value at the operating point P2 where IPb = A1 '+ ΔIMOS is A2'. Then, the gain is calculated from the difference between the current values (A2′−A1 ′ = A2−A1 = ΔIMOS (= 7A)) and the difference between the voltage values (B1−B2) at points P1 and P2 in FIG. 2 dash-dot line). Using this gain, the inclination of the predetermined characteristic of the Pb current sensor 21 is corrected.

  Note that the load current IR1 does not change under predetermined conditions such as the power generation state of the alternator 10 being constant. Therefore, even in a plurality of states in which the value of the battery current IPb is different from each other, the value of the load current IR1 is regarded as the same value.

On the other hand, X2 on the power supply line 15 in FIG. 1 is a branch point where the power supply line 15 branches to the lithium ion storage battery 30 side, the MOS switch 50 side, and the electric load 43 side. In this case, in the current path including the branch point X2, if the battery current flowing on the lithium ion storage battery 30 side is ILi, the switch current flowing on the MOS switch 50 side is IMOS, and the load current flowing on the electric load 43 side is IR2, each of these Kirchhoff's current law holds for current. Therefore, if the switch current IMOS is an inflow current with respect to the branch point X2, and the battery current ILi and the load current IR2 are outflow currents with respect to the branch point X2, the following current balance relational expression (2) is established.
IR2 + ILi = IMOS (2)
According to the above formula (2), if two values of the currents IR2, ILi, and IMOS at the branch point X2 are known, the remaining one value can be calculated. The relational expression (2) always holds even if the value of each current changes, and the relational expression for each current included in the relational expression (2) even in a plurality of states in which the values of each current are different from each other. Calculation based on (2) is possible.

  Even at the branch point X2, for example, the gain can be calculated for the output characteristics of the current detection unit 61 of the SMR switch 60. The calculation method is the same as the gain calculation in the Pb current sensor 21. Briefly, the battery current ILi is calculated from the currents included in the relational expression (2) in the current balance relationship at the branch point X2. The switch current IMOS other than the specific current, the battery current ILi, and the load current IR2 are set as non-specific currents. Then, under a plurality of states where the values of the battery currents ILi are different from each other, the value of the battery current ILi and the voltage value of the branch point X2 are calculated, respectively, and the gain α of the output characteristic in the Pb current sensor 21 is calculated. At this time, in particular, the actual value of the battery current ILi is calculated by substituting the actual value of the non-specific current (IMOS, IR2) into the relational expression (2), and the gain is calculated using the actual value. The accuracy of current value calculation due to the difference between the output characteristic and the predetermined output characteristic recognized on the ECU 70 side is suppressed.

  When calculating the gain of the output characteristic of the Pb current sensor 21 with respect to the branch point X1, the lead storage battery 20 corresponds to the “first storage battery”, and the gain of the output characteristic of the current detection unit 61 with respect to the branch point X2 is calculated. In this case, the lithium ion storage battery 30 corresponds to the “first storage battery”.

  FIG. 4 is a flowchart showing the gain calculation process. This process is repeatedly performed by the ECU 70 (or ECU 80) at a predetermined time period. This gain calculation process corresponds to the monitoring process for the lead storage battery 20. Here, the process of calculating the gain α related to the output characteristics of the Pb current sensor 21 will be described.

  In FIG. 4, in step S01, it is determined whether or not a predetermined execution condition regarding gain calculation is satisfied. This implementation condition is also a calculation condition for calculating the value of the battery current IPb as the specific current. The execution conditions of step S01 include time conditions and vehicle travel conditions. Specifically, it is determined as a timing condition whether or not the present time is an execution timing for calculating the gain α. For example, when the gain α is calculated every predetermined time (for example, every 30 minutes) under the ignition-on state, it is determined whether or not the predetermined time has elapsed since the previous calculation time. Alternatively, when the gain α is calculated only once after the ignition is turned on, it is determined whether or not the gain α has been calculated.

Further, as the vehicle traveling condition, it is calculated whether the traveling state of the vehicle is a predetermined traveling state in which the gain α can be calculated. For example,
(1) The power generation state of the alternator 10 is in a predetermined stable state,
(2) The vehicle speed is constant (the fluctuation range is below a predetermined value),
(3) The driving state of the electric loads 42 and 43 is constant,
(4) Not when starting the engine,
(5) The vehicle interior air conditioning temperature is stable at an appropriate value.
Determine. If any of the above execution conditions is satisfied, step S01 is affirmed and the process proceeds to subsequent step S02. Here, if the above (1) and (2) are established, the current value (total) on the power supply side is stable. Further, if the above (3) to (5) are established, the current value (total) on the power consumption side is stable.

  In addition, as a specific method for determining that the power generation state of the alternator 10 is in a predetermined stable state, it is determined that the fluctuation range of the power generation current flowing from the alternator 10 is equal to or less than a predetermined value, or a power source of the alternator 10 is used. It may be determined that the rotational state of a certain engine is stable (the fluctuation range of the rotational speed is equal to or less than a predetermined value). Further, as a specific method for determining that the driving state of the electric loads 42 and 43 is constant, based on the on / off state and power consumption information of each electric load 42 and 43 acquired via the communication network. It is determined that the on / off state of each electric load 42, 43 is unchanged, or it is determined that the power consumption of each electric load 42, 42 is constant (the differential value of the load current is not more than a predetermined value). It is good to do.

Other,
(6) The accelerator is being operated.
(7) The brake is being operated,
It may be configured to determine that either (6) or (7) is satisfied as an implementation condition. When the above (6) and (7) are established, it is difficult for the driver to perform a load operation (input operation on the instrument panel), and the current value (total) on the power consumption side is unlikely to fluctuate ( The same applies to (5) above).

  In step S02, it is determined whether or not the MOS switch 50 is currently turned off. Then, the process proceeds to step S03 on condition that the MOS switch 50 = off. In step S03, the switch current IMOS (off) when the MOS switch 50 is turned off is calculated based on the detection signal of the current detection unit 51. At this time, if the MOS switch 50 is OFF, IMOS = 0A should be obtained, so step S03 can be omitted.

  Thereafter, in step S04, the battery current IPb (off) in the MOS switch 50 = off state is calculated from the detection signal of the Pb current sensor 21. In calculating the battery current IPb (off), for example, the calculated value of the battery current IPb (off) is averaged a plurality of times to calculate the final battery current IPb (off), and the calculation accuracy is improved. It is desirable to do.

  In step S05, a load current IR1 flowing through the electric load 42 is calculated. At this time, the load current IR1 is calculated by substituting the battery current IPb and the switch current IMOS calculated in steps S03 and S04 into the relational expression (1). Since IMOS = 0A, IR1 = −IPb (off).

  Thereafter, in step S06, the terminal voltage VPb (off) of the lead storage battery 20 in the MOS switch 50 = off state is calculated. In a succeeding step S07, a command to turn on the MOS switch 50 is issued, and then this process is temporarily terminated.

  After the MOS switch 50 is turned on, step S02 becomes NO and the process proceeds to step S08. In step S08, it is determined whether or not both the load current IR1 and the battery current IPb (off) when the MOS switch 50 is turned off have been calculated. If both of these have been calculated, the process proceeds to step S09, and if not calculated, this process ends. For example, if the MOS switch 50 is turned on when the execution condition of step S01 is first established, the determination of step S08 is performed without calculating the load current IR1 and the battery current IPb (off). In this case, step S08 is NO and this process is terminated as it is.

  In step S09, the switch current IMOS (on) when the MOS switch 50 is turned on is calculated from the detection signal of the current detection unit 51. In the present embodiment, step S09 and step S05 described above correspond to the non-specific current acquisition unit, and the MOS switch 50 = ON state corresponds to the “predetermined state”.

  Thereafter, in step S10, the battery current IPb (on) when the MOS switch 50 is on is calculated. At this time, the battery current IPb (on) is calculated by substituting the load current IR1 calculated in step S05 and the switch current IMOS (on) calculated in step S09 into the relational expression (1). In step S09, the final switch current IMOS (on) is calculated from the average value of a plurality of calculated values, and the battery current IPb (on) is calculated using the value, thereby calculating the battery current IPb (on). It is recommended to increase the accuracy.

  Thereafter, in step S11, the terminal voltage VPb (on) of the lead storage battery 20 when the MOS switch 50 is turned on is calculated. In a succeeding step S12, a command to turn off the MOS switch 50 is issued.

  Thereafter, in step S13, the battery current IPb (off) calculated when the MOS switch 50 = OFF and the terminal voltage VPb (off) of the lead storage battery 20, and the battery current IPb (on) calculated when the MOS switch 50 = ON and the lead storage battery. The gain α is calculated from the 20 terminal voltage VPb (on). At this time, the gain α is calculated by dividing the amount of change in the battery current IPb and the amount of change in the terminal voltage VPb in each ON / OFF state of the MOS switch 50.

  In a succeeding step S14, it is determined whether or not the gain α is within an appropriate range. At this time, for example, when the calculation of the gain α is repeatedly performed, if the difference from the previous value of the gain α is equal to or less than a predetermined value, it is determined that the gain α is within the appropriate range. Alternatively, the gain (inclination) of the predetermined characteristic in the Pb current sensor 21 is compared with the gain α, and if the difference between the two (inclination difference) is equal to or less than a predetermined value, it is determined that the gain α is within an appropriate range. .

  If the gain α is within the appropriate range, the process proceeds to step S15. In step S15, the gain α is stored in a memory in the ECU (for example, a backup memory such as EEPROM (registered trademark)), and then this process is terminated. By calculating the gain α in this way, a series of gain calculation processes is completed.

  If the execution condition of step S01 is not satisfied during a series of gain calculation processes, the gain calculation is terminated when the condition is not satisfied. And a series of processing is good to be performed from the beginning. However, if the calculation of the battery current IPb (off) and the load current IR1 is completed in a state where the vehicle traveling condition is satisfied, the calculated value is stored even after the condition is not satisfied, and the gain thereafter You may use for calculation.

  The gain of the current detection unit 61 of the SMR switch 60 with respect to the branch point X2 can also be calculated by the same method as the gain of the Pb current sensor 21 described above.

  Briefly, when a predetermined execution condition is satisfied, the MOS switch 50 is turned off, the switch current IMOS (off), the battery current ILi (off), the load current IR2, and the terminals of the lithium ion storage battery 30 The voltage VLi (off) is calculated (see steps S03 to S06). At this time, the calculation of the battery current ILi (off) is performed using the detection signal of the current detection unit 61. The calculation of the load current IR2 is performed based on IR2 = IMOS (off). The calculation of the terminal voltage VLi (off) of the lithium ion storage battery 30 is performed using a detection signal of a voltage detection unit (not shown) provided on the power supply line 15 on the lithium ion storage battery 30 side of the MOS switch 50. .

  Further, the MOS switch 50 is switched to the ON state, and the switch current IMOS (on), the battery current ILi (on), and the terminal voltage VLi (on) of the lithium ion storage battery 30 are calculated (see steps S09 to S11). At this time, the above relational expression (2) is used to calculate the battery current ILi (on). Then, the battery current ILi (off) calculated when the MOS switch 50 = off and the terminal voltage VLi (off) of the lithium ion storage battery 30 and the battery current ILi (on) calculated when the MOS switch 50 = on and the lithium ion storage battery 30 The gain of the current detector 61 is calculated from the terminal voltage VLi (on).

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

  In the present power supply system, the current value on the power supply side and the current value on the consumption side match each other. In particular, the inflow current when viewed at the branch points X1 and X2 of the storage batteries 20 and 30, the MOS switch 50, and the electric loads 42 and 43. And that the current balance is always established regardless of the power generation state of the alternator 10 and the switching state of the switches 50 and 60. did. Thereby, for example, even if the usage pattern of each storage battery 20 and 30 changes with the switching of the MOS switch 50, the actual battery current and switch current can be easily grasped. Therefore, the monitoring process regarding charging / discharging of each storage battery 20 and 30 can be implemented appropriately.

  As the monitoring process, a gain calculation process for calculating the gain of the output characteristics of the Pb current sensor 21 and the like is performed. In the gain calculation process, the value of the specific current (battery current IPb) in each on / off state of the MOS switch 50 is determined. And the like, the voltage values of the branch points X1 and X2 (terminal voltages of the storage batteries 20 and 30) are calculated, and the gain of the output characteristics of the Pb current sensor 21 and the like is calculated based on the calculated values. Was calculated. In particular, the value of the battery current IPb is calculated based on the fact that the sum of the inflow current and the sum of the outflow current at the branch points X1 and X2 are equal when the MOS switch 50 is in the on state, and the IPb value is used to calculate the gain. I did it.

  In this case, the value of the specific current calculated based on the relationship of the current balance at the branch points X1 and X2 corresponds to the actual current value. According to this current value and the actual voltage value, the Pb current Even if the output characteristic of the sensor 21 or the current detection unit 61 (specific current detection means) is deviated between the actual characteristic and the predetermined characteristic, the gain can be calculated by bringing the predetermined characteristic closer to the actual characteristic. Then, by using the gain calculated as described above, it is possible to suppress the ECU 70 and 80 from calculating the current value as an incorrect value.

  In the gain calculation process, the battery currents IPb and ILi as specific currents are calculated when a predetermined stable condition is satisfied for the current consumed by the electric load (step S02). When the current consumed by the electric load is stable, the battery currents IPb and ILi and the switch current IMOS in a plurality of states can be easily grasped on the assumption that the values of the load currents IR1 and IR2 are constant. This is convenient for calculation. In this case, the same value can be used as each of the load currents IR1 and IR2 regardless of whether the MOS switch 50 is on or off.

  By switching on / off of the MOS switch 50, the values of the battery currents IPb and ILi are made different. In this case, when the MOS switch 50 is turned off, the switch current IMOS is 0 A regardless of the state of each of the storage batteries 20 and 30. Therefore, it is convenient for calculating the value of the load current IR1.

(Modification of the first embodiment)
In the above configuration, the battery currents IPb and ILi are changed by switching on / off of the MOS switch 50. However, by changing this, the battery currents IPb, ILi are switched by switching on / off of the SMR switch 60. It is good also as a structure which changes.

  FIG. 5 is a diagram showing the flow of each current in a state where the SMR switch 60 is switched on / off, and the values of each current are illustrated in the drawing. This is similar to FIG. In FIG. 5A, the MOS switch 50 is turned on (conducting) and the SMR switch 60 is turned on (conducting), and current flows as shown in the figure. At this time, IMOS = 7A and IPb = 3A are calculated from the current detection result at the branch point X1.

  In FIG. 5B, the SMR switch 60 is switched from on to off while the MOS switch 50 is maintained in the on state. As a result, the battery current IPb changes. At this time, since IR1 = 4A and IMOS = −8A at the branch point X1, IPb = −12A is calculated from the relational expression (1). Thus, since the battery current IPb when the SMR switch 60 is turned on and when it is turned off is calculated, the gain α can be calculated by the method described above.

(Other variations of the first embodiment)
In the above configuration, the load currents IR1 and IR2 are calculated from the relationship of the current balance at the branch points X1 and X2, but this may be changed. The load currents IR1 and IR2 are assumed to be known predetermined values if the vehicle traveling conditions match. Therefore, each value of IR1 and IR2 may be determined in association with the vehicle travel condition and registered in advance in a memory in the ECU. In this case, various monitoring processes may be performed under the implementation condition that the vehicle travel condition corresponds to the values of the load currents IR1 and IR2.

  The gain calculation process may be performed using on / off switching of the MOS switch 50 that accompanies automatic engine stop and restart by idle stop control. That is, when the engine is automatically stopped, the MOS switch 50 is held in the on state until the engine is restarted thereafter, and the MOS switch 50 is switched to the off state as the engine is restarted. In this case, as the monitoring process for the lithium ion storage battery 30, a gain calculation process for calculating the gain of the output characteristic for the current detection unit 61 of the SMR switch 60 is performed based on the relationship of the current balance at the branch point X2. Here, contrary to FIG. 4, the calculation of the battery current IPb (on) in the MOS switch 50 = on state is performed first, and the calculation of the battery current IPb (off) in the MOS switch 50 = off state is performed later. Done.

  Specifically, as the gain calculation processing, the ECU 70 determines the switch current IMOS from the result of each detection means under the condition that the MOS switch 50 is turned on with the automatic engine stop (particularly under the condition of the engine speed = 0). (On), battery current ILi (on), and terminal voltage VLi (on) of lithium ion storage battery 30 are calculated. Also, the load current IR2 is calculated by substituting the switch current IMOS (on) and the battery current ILi (on) into the relational expression (2).

  Thereafter, the battery current ILi (off) is calculated from the relationship of the current balance at the branch point X2 while the MOS switch 50 is turned off with the engine restart, and the terminal voltage VLi (off) of the lithium ion storage battery 30 is calculated. Is calculated. At this time, since the switch current IMOS (off) = 0A and ILi (off) = − IR2, the battery current ILi (off) is calculated. Then, the battery current ILi (on) calculated when the MOS switch 50 = on and the terminal voltage VLi (on) of the lithium ion storage battery 30 and the battery current ILi (off) calculated when the MOS switch 50 = off and the lithium ion storage battery 30 From the terminal voltage VLi (off), the gain of the output characteristic of the current detection unit 61 is calculated.

  By using the switching of the MOS switch 50 accompanying the execution of the idle stop control as described above, it is not necessary to forcibly switch the MOS switch 50 on / off. Therefore, the gain calculation process (monitoring process) can be performed without taking into account the influence associated with the on / off switching of the MOS switch 50.

(Second Embodiment)
In the configuration shown in FIG. 6, as a difference from the configuration in FIG. 1, electrical loads 43 </ b> A and 43 </ b> B are provided as the electrical load 43 on the lithium ion storage battery 30 side. In addition, load switches 44A and 44B are provided between the branch point X2 and the electric loads 43A and 43B, respectively. The load switches 44A and 44B are controlled to be turned on / off by the ECU 70. Each load switch 44A, 44B may be provided in the battery unit U.

  In this case, when the MOS switch 50 = on and the SMR switch 60 = off, the load switches 44A, 44B are switched on / off to make the battery current IPb different. Then, the value of the battery current IPb is calculated under each state where the battery current IPb is different, and the gain of the output characteristic is calculated for the Pb current sensor 21 based on the calculated value.

  FIG. 7 is a flowchart showing the gain calculation process, and this process is repeatedly performed by the ECU 70 (or the ECU 80) at a predetermined time period. This gain calculation process corresponds to the monitoring process for the lithium ion storage battery 30. Here, it is assumed that the MOS switch 50 = on and the SMR switch 60 = off.

  In FIG. 7, in step S21, it is determined whether or not a predetermined execution condition relating to gain calculation is satisfied. This implementation condition is substantially the same as that in step S01 of FIG. 4, except that switching of the driving state of the electric load 43 (43A, 43B) is allowed. However, the implementation condition may include that the driving state of the electric load 43 (43A, 43B) does not change unintentionally. If the execution condition is satisfied, the process proceeds to step S22.

  In step S22, it is determined whether or not the battery current IPb (1) in the “first load state” has not been calculated. Here, the first load state refers to a state after switching the driving state for the plurality of electric loads 43A and 43B in step S23 described later, and calculation of the battery current IPb (1) and the like in that state is completed. If not, step S22 is affirmed and the process proceeds to step S23.

  In step S23, the drive state is switched for any one of the plurality of electric loads 43A and 43B. At this time, the load drive state is switched by switching on / off one of the load switches 44A and 44B. For example, one of the load switches 44A (or 44B) is turned off while both of the load switches 44A and 44B are turned on. Alternatively, the load switch in the off state is turned on in a state where one of the load switches 44A and 44B is off. The state after this switching is performed is the first load state.

  Thereafter, in step S24, the switch current IMOS (1) in the first load state is calculated based on the detection signal of the current detection unit 51. In the subsequent step S25, the battery current IPb (1) in the first load state is calculated from the detection signal of the Pb current sensor 21. When calculating the switch current IMOS (1) and the battery current IPb (1), for example, the final switch current IMOS (1) and the battery current IPb (1) are calculated by averaging a plurality of calculated values. It is desirable to increase the calculation accuracy.

  Thereafter, in step S26, a load current IR2 flowing through the electric load 43 (43A, 43B) is calculated. At this time, the load current IR1 is calculated by substituting the switch current IMOS (1) and the battery current IPb (1) into the relational expression (1). In step S27, the terminal voltage VPb (1) of the lead storage battery 20 in the first load state is calculated, and then this process is temporarily terminated.

  After the battery current IPb (1) and the like are calculated in the first load state, step S22 becomes NO and the process proceeds to step S28. In step S28, the plurality of electric loads 43A and 43B are returned to the state before the switching of the driving state. At this time, the state of the load switches 44A and 44B is restored. This state is referred to as a “second load state”.

  Thereafter, in step S29, the switch current IMOS (2) in the second load state is calculated based on the detection signal of the current detection unit 51. In the present embodiment, step S29 and step S26 described above correspond to non-specific current acquisition means, and the second load state corresponds to a “predetermined state”.

  Thereafter, in step S30, the battery current IPb (2) in the second load state is calculated. At this time, the battery current IPb (2) is calculated by substituting the load current IR1 calculated in step S26 and the switch current IMOS (2) calculated in step S29 into the relational expression (1). In step S29, the final switch current IMOS (2) is calculated from the average value of a plurality of calculated values, and the battery current IPb (2) is calculated using the value, whereby the battery current IPb (2) is calculated. It is better to improve the calculation accuracy of.

  Thereafter, in step S31, the terminal voltage VPb (2) of the lead storage battery 20 in the second load state is calculated. In subsequent step S32, the battery current IPb (1) calculated in the first load state and the terminal voltage VPb (1) of the lead storage battery 20 and the battery current IPb (2) calculated in the second load state and the terminal of the lead storage battery 20 are displayed. The gain α is calculated from the voltage VPb (2). At this time, the gain α is calculated by dividing the change amount of the battery current IPb and the change amount of the terminal voltage VPb in the first and second load states.

  In a succeeding step S33, it is determined whether or not the gain α is within an appropriate range. If YES, the gain α is stored in a memory in the ECU in a step S34 (similar to steps S14 and S15 in FIG. 4).

  According to the second embodiment described in detail above, the gain of the Pb current sensor 21 is appropriately calculated by using the difference in the value of the battery current IPb by switching on / off of the load switches 44A and 44B. As a result, it is possible to suppress the ECU 70 and 80 from calculating the current value as an incorrect value.

(Modification 1 of 2nd Embodiment)
In the above configuration, the output characteristics of the Pb current sensor 21 that detects the battery current IPb at the branch point X1 by setting the battery current IPb as the specific current among the battery current IPb (first storage battery current), the switch current IMOS, and the load current IR1. However, it may be modified so that the switch current IMOS is a specific current and the gain of the output characteristic is calculated for the current detector 61 that detects the switch current IMOS. In this case, as described above, an actual IMOS value may be calculated using a current balance relationship at the branch point X1, and a gain may be calculated using the IMOS value.

  In the present embodiment, the value of the switch current IMOS can be made different while the MOS switch 50 is on and the SMR switch 60 is off. Therefore, the IMOS value can be calculated in each state where the switch current IMOS is different, and the gain can be calculated using the calculated value of the IMOS.

(Third embodiment)
In the third embodiment, at the branch point X2 where the MOS switch 50, the SMR switch 60, and the electric load 43 are connected, one of the MOS switch 50 and the SMR switch 60 is turned on (conductive) and the other is turned off (cut off). Thus, the abnormality detection of the MOS switch 50 and the SMR switch 60 is performed from the relationship of the current balance at the branch point X2 in both of these states. In the present embodiment, the lead storage battery 20 corresponds to a second storage battery, and the lithium ion storage battery 30 corresponds to a first storage battery.

  FIG. 8 is a diagram illustrating the flow of each current in a state where the MOS switch 50 and the SMR switch 60 are switched on / off, and the values of each current are illustrated in the drawing. Since the alternator 10 is in a non-power generation state, the illustration is omitted. Further, the electrical loads 41 and 42 are not shown because they are not directly related.

  In FIG. 8A, the MOS switch 50 is turned on (conducting) and the SMR switch 60 is turned off (cut off), and current flows as shown in the figure. In this state, since the SMR switch 60 is off, the battery current ILi = 0A. According to the current balance relationship at the branch point X2, the switch current IMOS and the load current IR2 have the same value (−12 A). In this case, if the driving state of the electric load 43 is constant, the load current IR2 is a constant value (−12A). If the current detection unit 51 of the MOS switch 50 is normal, the detection value is the same value as IR2. That's it. Therefore, whether or not the current detection unit 51 is abnormal can be detected by determining whether or not IMOS = −12A.

  On the other hand, in FIG. 8B, the MOS switch 50 is turned off (cut off) and the SMR switch 60 is turned on (conductive), and current flows as shown in the figure. In this state, since the MOS switch 50 is off, the switch current IMOS = 0A. Then, according to the current balance relationship at the branch point X2, the battery current ILi and the load current IR2 have the same value (12A, -12A). In this case, if the current detector 61 of the SMR switch 60 is normal, the detected value should be the same value as “−IR2”. Therefore, the presence or absence of abnormality of the current detection unit 61 can be detected by determining whether ILi = 12A.

  FIG. 9 is a flowchart showing an abnormality determination process of the current detection system, and this process is repeatedly performed by the ECU 70 (or ECU 80) at a predetermined time period. This abnormality determination process corresponds to the monitoring process for the lithium ion storage battery 30.

  In FIG. 9, in step S <b> 40, it is determined whether or not a predetermined execution condition regarding this abnormality determination is satisfied. This execution condition may be the same as that in step S01 in FIG. 4, and if the execution condition is satisfied, the process proceeds to step S41.

  In step S41, the value of the load current IR2 is acquired. The IR2 value is a value registered in advance in a memory in the ECU as a known value. In step S41, the IR2 value is read from the memory. This IR2 value is a value determined in association with the vehicle travel condition as the execution condition of step S40.

  In step S42, it is determined whether or not the MOS switch 50 is on and the SMR switch 60 is off. In step S43, it is determined whether or not the MOS switch 50 is off and the SMR switch 60 is on. When step S42 is YES, the process proceeds to step S44, and the value of the switch current IMOS is calculated from the detection signal from the current detection unit 51 of the MOS switch 50. In step S45, it is determined whether “IMOS ≠ IR2”. If IMOS ≠ IR2, it is determined in step S46 that the current detection unit 51 of the MOS switch 50 is abnormal.

  If step S43 is YES, the process proceeds to step S47, and the value of the battery current ILi is calculated from the detection signal from the current detection unit 61 of the SMR switch 60. In step S48, it is determined whether or not “ILi ≠ −IR2”. If ILi ≠ −IR2, it is determined in step S49 that there is an abnormality in the current detection unit 61 of the SMR switch 60.

  According to the third embodiment described in detail above, the battery current ILi between the MOS switch 50 = on and the SMR switch 60 = off and the MOS switch 50 = off and the SMR switch 60 = on. (The first storage battery current) and the switch current IMOS are different from each other, and in these two states, the switch current IMOS and the battery current ILi should be equal to the value of the load current IR2, respectively. The abnormality of each of the current detection units 51 and 61 can be suitably determined.

(Fourth embodiment)
In the fourth embodiment, the state in which power is supplied to the electrical loads 42 and 43 by the lead storage battery 20 and the state in which power is supplied to the electrical loads 42 and 43 by both the lead storage battery 20 and the lithium ion storage battery 30. Based on the value of the battery current in the two states of switching, each abnormality of the MOS switch 50 and the SMR switch 60 is determined. In the present embodiment, the lead storage battery 20 corresponds to a second storage battery, and the lithium ion storage battery 30 corresponds to a first storage battery. Here, when the electric loads 42 and 43 respectively connected to both sides of the MOS switch 50 are energized and driven, if the power generation amount of the alternator 10 is constant (for example, zero), the consumption of the electric loads 42 and 43 is performed. The power (full load current) should be the same regardless of whether the SMR switch 60 is on or off, and an abnormality determination is performed using this assumption.

  FIG. 10 is a diagram illustrating the flow of each current in a state where the SMR switch 60 is switched on / off, and the values of each current are illustrated in the drawing. This is similar to FIG.

  In FIG. 10A, the MOS switch 50 is turned on (conducting) and the SMR switch 60 is turned off (cut off), and current flows as shown in the figure. Here, the consumption current (load current IR1) of the electric load 42 is 4A, the consumption current (load current IR2) of the electric load 43 is -12A, and the total load current is -16A. In this case, since the SMR switch 60 is off (cut off), the consumption current of each of the electric loads 42 and 43 is all borne by the discharge of the lead storage battery 20, and the battery current calculated from the detection value of the Pb current sensor 21. IPb is the full load current (IPb = full load current).

  In FIG. 10B, the SMR switch 60 is switched from OFF to ON while the MOS switch 50 is maintained in the ON state. At this time, if the drive state of the electric loads 42 and 43 is unchanged, the total load current should be −16 A as in FIG. However, for example, if some abnormality occurs in the MOS switch 50 or the SMR switch 60, the full load current in the state of FIG. 10B does not match the full load current in the state of FIG. Become. Thereby, it can be determined that an abnormality has occurred.

In this case, in the state of FIG. 10B, the battery current IPb that is the Pb current can be obtained from the relationship of the current balance at the branch point X1,
IPb = IMOS-IR1
Can be calculated as Further, the battery current ILi that is the Li current can be calculated from the detection signal of the current detection unit 61. The sum of the battery currents IPb and ILi is the full load current (IPb + ILi = full load current).

  FIG. 11 is a flowchart showing the system abnormality determination process, and this process is repeatedly performed by the ECU 70 (or ECU 80) at a predetermined time period. This abnormality determination process corresponds to a monitoring process related to charging / discharging of both storage batteries 20 and 30. In the abnormality determination process, the battery currents IB1 and 1B2 are calculated as the sum of the current values flowing through the lead storage battery 20 and the lithium ion storage battery 30, and the abnormality determination is performed based on the battery currents IB1 and 1B2. The battery current IB1 is the sum of the current values flowing through the storage batteries 20 and 30 when the MOS switch 50 = ON and the SMR switch 60 = OFF. The battery current IB2 is the battery current IB2 when the MOS switch 50 = ON and the SMR switch 60 = ON. It is the sum of current values flowing through both storage batteries 20 and 30.

  In FIG. 11, in step S50, it is determined whether or not a predetermined execution condition regarding this abnormality determination is satisfied. This execution condition is substantially the same as that in step S01 of FIG. 4, except that the alternator 10 is in a power generation stop state. If the execution condition is satisfied, the process proceeds to step S51.

  In step S51, it is determined whether or not the battery current IB1 has been calculated. And it progresses to step S52 on condition that it has not calculated yet. In step S52, it is determined whether or not the MOS switch 50 is currently on and the SMR switch 60 is off. If step S52 is YES, the process proceeds to step S53.

  In step S53, the battery current IPb flowing through the lead storage battery 20 is calculated as the battery current IB1. At this time, since the consumption currents of the electric loads 42 and 43 are all borne by the discharge of the lead storage battery 20, the battery current IPb corresponds to the full load current. The battery current IPb is calculated from the detection signal of the Pb current sensor 21. Thereafter, in step S54, the load current IR1 of the electric load 42 is calculated. At this time, the load current IR1 is calculated by substituting the battery current IPb and the switch current IMOS each time into the relational expression (1).

  In step S55, a command to turn on the SMR switch 60 is issued, and then this process is temporarily terminated.

  After the battery current IB1 is calculated, step S51 is YES, and the process proceeds to step S56. In step S56, it is determined whether or not both the MOS switch 50 and the SMR switch 60 are currently on. If YES, the process proceeds to the subsequent step S57.

  In step S57, the sum of the battery currents IPb and ILi flowing through the storage batteries 20 and 30 is calculated as the battery current IB2. At this time, since the consumption current of each electric load 42 and 43 is borne by the discharge of the lead storage battery 20 and the lithium ion storage battery 30, IPb + ILi corresponds to the full load current. IB2 (total load current) = IPb + ILi = (IMOS−IR1) + ILi, and the battery current IB1 is calculated by adding the load current IR1 calculated in step S55, the switch current IMOS and the battery current ILi detected each time. The The battery current IPb may be calculated from a detection signal of the Pb current sensor 21.

  Thereafter, in step S58, it is determined whether or not the battery currents IB1 and IB2 match. If IB1 ≠ IB2, the process proceeds to step S59 to determine that an abnormality has occurred in either the MOS switch 50 or the SMR switch 60.

  According to the fourth embodiment described in detail above, each of the storage batteries 20, 30 in the state where the MOS switch 50 = on and the SMR switch 60 = off and the state where both the MOS switch 50 and the SMR switch 60 are on. Although the values of the currents flowing through are different, it is possible to appropriately determine each abnormality of the switches 50 and 60 based on the fact that the total load current should be unchanged.

  The abnormality determination process is performed in a state where the alternator 10 stops power generation. When the alternator 10 is in the power generation stop state, the sum of the current values flowing through the storage batteries 20 and 30 does not change, and when the system is normal, the MOS switch 50 = ON and the SMR switch 60 = OFF battery current IB1 and the MOS switch 50 = The battery current IB2 when ON and SMR switch 60 = ON coincides. In this case, a simple comparison of IB1 and IB2 is possible if the amount of power generated from the alternator 10 is zero. Further, since error factors are reduced, the accuracy of abnormality determination can be increased.

(Fifth embodiment)
In the fifth embodiment, a bypass relay is provided in a bypass path connecting both sides of the MOS switch 50, and abnormality determination of the bypass relay is performed. FIG. 12 shows the electrical configuration of the power supply system in the present embodiment. In the configuration of FIG. 12, as a difference from FIG. 1 described above, a bypass path that connects both sides of the MOS switch 50 is provided. This will be specifically described below.

  In FIG. 12, a bypass power supply line 91 is connected to the power supply line 15 so as to bypass the MOS switch 50. The bypass power supply line 91 has one end connected to the branch point X1 and the other end connected to the branch point X2. In addition, power can be supplied to the electrical load 43 from at least one of the alternator 10 and the lead storage battery 20 via the bypass power supply line 91. In the present embodiment, the lead storage battery 20 corresponds to a first storage battery, and the lithium ion storage battery 30 corresponds to a second storage battery.

  The bypass power supply line 91 is provided with a bypass relay 92 (bypass switching means) which is a normally closed electromagnetic relay. The operation of the bypass relay 92 is controlled by the ECU 70. The bypass relay 92 is an emergency energization means used when an abnormality (failure) occurs in the MOS switch 50 or the ECU 70. In normal operation (when no failure occurs), an excitation current is always output from the ECU 70. It is off. For example, when an abnormality occurs in the ECU 70 and the MOS switch 50 cannot be turned on, the normally closed bypass relay 92 is turned on, and the bypass power supply line 91 is turned on. As a result, power is supplied to the electrical load 43 from at least one of the alternator 10 and the lead storage battery 20 via the bypass power supply line 91.

  Here, in order to guarantee the power supply function (backup function) to the electric load 43 by the bypass power supply line 91, it is necessary to determine whether the bypass relay 92 is abnormal. Therefore, in the present embodiment, an abnormality determination process for the bypass relay 92 is performed.

  FIG. 13 is a flowchart showing an abnormality determination process of the bypass relay 92, and this process is repeatedly performed by the ECU 70 (or ECU 80) at a predetermined time period.

  In FIG. 13, in step S61, it is determined whether or not the MOS switch 50 is currently on. In step S62, the supply current supplied from the alternator 10 and the storage batteries 20 and 30 to the electric load 43 is determined. And the current consumption value consumed by the electric load 43 are determined to be unchanged. At this time, when the generated power of the alternator 10 is constant and the driving state of the electric load 43 is constant, step S62 is affirmed. And if both step S61 and S62 are YES, it will progress to subsequent step S63.

  In step S63, it is determined whether or not the switch current IMOS has changed. Specifically, when the bypass relay 92 is turned on unintentionally with the MOS switch 50 = on (when an on-failure occurs), the switch current IMOS is considered to be reduced by an amount corresponding to the energization resistance in the bypass relay 92. . In this case, step S63 is affirmed and the process proceeds to step S64. In step S64, it is determined that an ON abnormality has occurred in the bypass relay 92.

  According to the fifth embodiment described in detail above, the conduction abnormality of the bypass relay 92 can be suitably determined by utilizing the fact that the energization resistance value changes when the bypass relay 92 becomes conductive. Thereby, the operation of the backup function can be guaranteed in the power supply system.

(Modification 1 of 5th Embodiment)
In the process of FIG. 13 described above, the abnormality determination of the bypass relay 92 is performed based on whether or not the switch current IMOS is changed while the MOS switch 50 is turned on. However, this may be changed as shown in FIG.

  In FIG. 14, in step S71, it is determined whether both the MOS switch 50 and the SMR switch 60 are on. Note that the MOS switch 50 is turned off when the lithium ion storage battery 30 is not charged while the vehicle is traveling. Therefore, it is preferable to forcibly turn on the MOS switch 50 when the abnormality determination of the bypass relay 92 is performed. For example, when the MOS switch 50 = off and the SMR switch 60 = on, both switches 50, 60 may be turned on (overdischarge or overload in the lithium ion storage battery 30 when the MOS switch 50 is turned on). A state in which charging does not occur) is determined based on the storage state of both the storage batteries 20 and 30, and the switches 50 and 60 are both forcibly turned on according to the determination result. . If the MOS switch 50 is in the on state, the SMR switch 60 may be in the off state.

  If step S71 is YES, the bypass relay 92 is switched from the off state to the on state in step S72. Thereafter, in step S73, it is determined whether or not the amount of change in the switch current IMOS before and after switching of the bypass relay 92 is equal to or greater than a predetermined value.

  When the bypass relay 92 is switched from the off state to the on state, if the switching is normally performed, the value of the switch current IMOS changes (decreases) due to the change in the energization resistance value before and after the switching. On the other hand, if the switching of the bypass relay 92 is not performed normally, that is, if an ON abnormality that cannot turn off the bypass relay 92 occurs, the switch current IMOS does not change. Therefore, if step S73 is YES, the process is terminated as it is, and if step S73 is NO, the process proceeds to step S74, and it is determined that an ON abnormality has occurred in the bypass relay 92.

  It should be noted that the IMOS value when the bypass relay 92 is switched from ON to OFF is used instead of the configuration in which the abnormality of the bypass relay 92 is determined based on the amount of change in the IMOS value when the bypass relay 92 is switched from OFF to ON. An abnormality of the bypass relay 92 may be determined based on the amount of change.

(Modification 2 of 5th Embodiment)
It is also possible to carry out the abnormality determination process in FIG. In FIG. 15, in step S81, it is determined whether or not the MOS switch 50 = off and the SMR switch 60 = on. At this time, when the lithium ion storage battery 30 is not charged while the vehicle is traveling, the MOS switch 50 = OFF and the SMR switch 60 = ON, and step S81 is YES.

  If step S81 is YES, the bypass relay 92 is switched from the off state to the on state in step S82. Thereafter, in step S83, along with the switching of the bypass relay 92, whether the battery current IPb flowing through the lead storage battery 20 and the battery current ILi flowing through the lithium ion storage battery 30 have changed according to the potential difference between the storage batteries 20, 30. Determine whether or not.

  In the state where the MOS switch 50 is turned off, the potentials of both the storage batteries 20 and 30 are not the same, and a potential difference is generated between the storage batteries 20 and 30. Therefore, if the bypass relay 92 is normally switched from OFF to ON, immediately after the switching, a current change corresponding to the potential difference between the storage batteries 20 and 30 occurs as the battery current IPb or ILi. On the other hand, if switching of the bypass relay 92 is not performed normally, that is, if an ON abnormality that cannot turn off the bypass relay 92 occurs, the battery current IPb or ILi does not change. Therefore, if step S83 is YES, this process is terminated as it is, and if step S83 is NO, the process proceeds to step S84, and it is determined that an ON abnormality has occurred in the bypass relay 92.

  In step S83, if any change occurs in the battery current IPb or ILi, it may be determined that a current change according to the potential difference between the storage batteries 20 and 30 has occurred. Or, ascertaining which one of the storage batteries 20 and 30 is at a high potential, if the battery current IPb or ILi changes according to the level of the potential, the potential difference between the storage batteries 20 and 30 is determined. It may be determined that a current change has occurred. For example, when the potential of the lead storage battery 20 side <the potential of the lithium ion storage battery 30 side immediately before the bypass relay 92 is switched from OFF to ON, the discharge of the lithium ion storage battery 30 immediately after the bypass relay 92 is switched ON. Assuming that the discharge of the lead storage battery 20 is reduced, the change in the battery current IPb or ILi is determined.

  In any of the abnormality determination processes of FIGS. 14 and 15, it can be suitably determined whether or not the bypass relay 92 is abnormal, and the operation of the backup function can be guaranteed.

(Other embodiments)
Each of the above embodiments may be modified as follows, for example.

  In each of the above embodiments, the current detection unit 51 provided integrally with the MOS switch 50 is used as the switch current detection unit that detects the current flowing through the MOS switch 50 (connection switch), and the SMR switch 60 (storage battery switch) is used. As the storage battery current detection unit for detecting the flowing current, the current detection unit 61 provided integrally with the SMR switch 60 is used, but this may be changed. A configuration in which a current sensor is provided between the MOS switch 50 and the branch point X1 (or X2) as the switch current detection unit, or a current sensor is provided between the SMR switch 60 and the branch point X2 (or ground) as the storage battery current detection unit. You may employ | adopt the structure to provide.

  In each of the above embodiments, the lead storage battery 20 is used as the first storage battery and the lithium ion storage battery 30 is used as the second storage battery, but this may be changed. For example, another secondary battery such as a nickel-cadmium storage battery or a nickel hydride storage battery may be used as the second storage battery. Alternatively, both may be the lithium ion storage battery 30.

  -It is also possible to use the power supply system of this invention as power supply systems other than vehicle-mounted.

  DESCRIPTION OF SYMBOLS 10 ... Alternator (generator), 15 ... Feed line (connection line), 20 ... Lead storage battery, 30 ... Lithium ion storage battery, 42, 43 ... Electric load, 50 ... MOS switch (connection switch), 70, 80 ... ECU ( Power control means).

Claims (16)

A generator (10);
A first storage battery and a second storage battery (20, 30) connected in parallel to the generator;
A connection switch (50) provided on a connection line (15) for electrically connecting both the storage batteries, and for switching between conduction and interruption between the first storage battery and the second storage battery;
Electrical loads (42, 43) connected to both sides of the connection switch across the connection switch;
A power supply system comprising:
Based on the relationship between the value of the supply current supplied from the generator and the storage batteries to the electrical load and the value of the consumption current consumed by the electrical load, at least one of the storage batteries A current calculation process for calculating at least one of the storage battery current and a switch current flowing through the connection switch in a plurality of states in which the flowing storage battery currents have different values, and a current value calculated by the current calculation process A power supply system comprising: power supply control means (70, 80) for performing monitoring processing related to charging / discharging of at least one of the first storage battery and the second storage battery. At a branch point (X1, X2) between the first storage battery, the connection switch and the electrical load of the connection line, a first storage battery current flows on the first storage battery side, a switch current flows on the connection switch side, The load current flows on the electrical load side,
The power supply control unit calculates at least one of the first storage battery current and the switch current in the plurality of states based on the sum of the inflow current and the sum of the outflow current at the branch point being equal. The power supply system according to claim 1, wherein the current calculation process is performed and the monitoring process for the first storage battery is performed. Specific current detection means (21, 51) for setting either the first storage battery current or the switch current as a specific current, detecting the specific current and converting the current into a voltage and outputting the voltage,
Non-specific current acquisition means for acquiring a value of the non-specific current in a predetermined state included in the plurality of states by setting the first storage battery current, the switch current, and the load current other than the specific current as a non-specific current. When,
Voltage detection means (22) for detecting a voltage at the branch point;
With
The power control means includes
As the current calculation process, the value of the specific current is calculated in the plurality of states, and in the predetermined state, the value of the non-specific current acquired by the non-specific current acquisition unit is used, and the inflow at the branch point Current calculation means (70, 80) for calculating the value of the specific current based on the sum of the current and the sum of the outflow currents being equal;
As the monitoring process, the specific current is calculated based on the value of the specific current calculated by the current calculation unit in the plurality of states and the voltage value detected by the voltage detection unit in the plurality of states. Monitoring means for performing gain calculation processing for calculating the gain of the output characteristic of the detection means;
A power supply system according to claim 2.   The current calculation means sets the plurality of states to a state in which the storage batteries are turned on by the connection switch and a state in which the storage batteries are cut off, and calculates a value of the specific current in each of the states. Power supply system as described in. The generator is for generating power by rotating an output shaft of an internal combustion engine,
Automatic stop / restart that automatically stops the internal combustion engine when a predetermined automatic stop condition is satisfied, and restarts the internal combustion engine when a predetermined restart condition is satisfied when the internal combustion engine is automatically stopped Means (80);
A switch control means (70) for bringing the connection switch into a conductive state at the time of automatic stop of the internal combustion engine, and for closing the connection switch at a subsequent restart;
With
The current calculation means sets the state in which the connection switch is turned on by the switch control means and the state in which the connection switch is cut off by the switch control means as the plurality of states, and in each of the states, the current of the specific current The power supply system of Claim 3 which calculates a value.   The power supply system according to claim 4 or 5, wherein the non-specific current acquisition unit acquires the value of the load current as the non-specific current under a situation where the connection switch is cut off. Provided in a power supply path from the first storage battery to the electrical load, comprising a load switch (44A, 44B) for switching between conduction and interruption between the first storage battery and the electrical load,
The power source according to claim 3, wherein the current calculation means sets the plurality of states to a state where the load switch is conductive and a state where the load switch is cut off, and calculates the value of the specific current in each of the states. system. A storage battery switch (60) that is provided between the branch point (X2) and the first storage battery (30) and switches between conduction and disconnection between the branch point and the first storage battery;
A switch current detector (51) for detecting a switch current flowing through the connection switch;
A storage battery current detector (61) for detecting a first storage battery current flowing through the storage battery switch;
With
The state where the connection switch is conductive and the storage battery switch is cut off, and the state where the connection switch is cut off and the storage battery switch is conductive are the plurality of states,
The power control means includes
As the current calculation process, the value of the switch current is calculated from the detection result of the switch current detection unit in a state where the connection switch is conductive and the storage battery switch is disconnected, and the connection switch is disconnected and the storage battery Current calculation means for calculating a value of the first storage battery current from a detection result of the storage battery current detection unit in a state where the switch is conductive;
As the monitoring process, depending on whether the value of the switch current calculated by the current calculation means and the value of the first storage battery current respectively match the value of the load current at that time, the switch current An abnormality determination means for performing an abnormality determination process for determining presence or absence of abnormality in the detection unit and the storage battery current detection unit;
A power supply system according to claim 2. A storage battery switch (60) provided between the branch point (X2) to which the electrical load is connected in the connection line and the first storage battery (30) and switching between conduction and disconnection between the branch point and the first storage battery. )
A state where the connection switch is conductive and the storage battery switch is disconnected, and a state where both the connection switch and the storage battery switch are conductive are the plurality of states,
The power control means includes
As the current calculation process, the current flowing through the second storage battery (20) in a state where the connection switch is conductive and the storage battery switch is cut off is calculated as the storage battery current, and the connection switch and the storage battery switch are both Current calculating means for calculating a sum of currents flowing through the first storage battery and the second storage battery in the conductive state as the storage battery current;
As the monitoring process, an abnormality determination process is performed for determining whether or not there is an abnormality in the connection switch and the storage battery switch depending on whether or not the values of the storage battery current in the two states calculated by the current calculation unit match each other. An abnormality determination means to perform,
The power supply system according to claim 1.   The power supply system according to claim 9, wherein the current calculation unit calculates the storage battery current in a state where the generator stops power generation. Means for determining that the power generation state of the generator is in a predetermined stable state;
The power supply system according to any one of claims 1 to 10, wherein the power supply control unit performs the current calculation process when a power generation state of the generator is in a predetermined stable state. Comprising power control means for controlling the power generated by the generator;
The power supply system according to any one of claims 1 to 10, wherein the power control unit performs the current calculation process when the power generated by the generator is controlled to be constant by the power control unit. Comprising information acquisition means for acquiring information relating to the driving state of the electrical load;
The power supply control unit performs the current calculation process when it is determined that the driving state of the electric load is constant based on the acquisition information of the information acquisition unit. Power supply system as described in. The generator is connected to the first storage battery (20) side with respect to the connection switch in the connection line,
An electrical load connected to the connection line, bypassing the connection switch and connected to the second storage battery (30) side with respect to the connection switch from at least one of the generator and the first storage battery ( 43) a bypass line (91) for supplying electric power;
A bypass switching means (92) for switching the bypass line from a cut-off state to a conductive state when an abnormality occurs related to switching of the connection switch;
In the state where the connection switch is conductive, the value of the supply current supplied from the generator and both storage batteries to the electric load and the value of the consumption current consumed by the electric load are unchanged. Nonetheless, when the value of the switch current changes, an abnormality determining means (70, 80) for determining that a conduction abnormality has occurred in which the bypass switching means is unintentionally turned on,
The power supply system according to claim 1, further comprising: The generator is connected to the first storage battery (20) side with respect to the connection switch in the connection line,
An electrical load connected to the connection line, bypassing the connection switch and connected to the second storage battery (30) side with respect to the connection switch from at least one of the generator and the first storage battery ( 43) a bypass line (91) for supplying electric power;
A bypass switching means (92) for switching the bypass line from a cut-off state to a conductive state when an abnormality occurs related to switching of the connection switch;
Abnormality determination that switches the bypass switching means between the cut-off state and the conductive state when the connection switch is conductive, and determines whether the bypass switching means is abnormal based on a change in the switch current before and after the switching. Means (70, 80);
The power supply system according to claim 1, further comprising: The generator is connected to the first storage battery (20) side with respect to the connection switch in the connection line,
An electrical load connected to the connection line, bypassing the connection switch and connected to the second storage battery (30) side with respect to the connection switch from at least one of the generator and the first storage battery ( 43) a bypass line (91) for supplying electric power;
A bypass switching means (92) for switching the bypass line from a cut-off state to a conductive state when an abnormality occurs related to switching of the connection switch;
In the state where the connection switch is cut off, the bypass switching means is switched from a cut-off state to a conductive state, and in accordance with the switching, the first storage battery current flowing through the first storage battery and the second storage battery current flowing through the second storage battery are changed. An abnormality determining means (70, 80) for determining whether or not the bypass switching means is abnormal depending on whether or not a current change occurs according to the potential difference between the two storage batteries;
The power supply system according to claim 1, further comprising:

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