JP6072466B2 - Vehicle power supply system - Google Patents

Description

  The present invention relates to a vehicular power supply system including a generator capable of regenerative power generation using regenerative energy of a vehicle, and a first storage battery and a second storage battery capable of charging power generated by the generator.

  For vehicles using an internal combustion engine as a travel drive source, a lead storage battery that supplies power to various electric loads such as a starter motor, an alternator (generator) capable of regenerative power generation by regenerative energy, and a voltage of power output from the alternator In general, a regulator (power generation control means) that variably controls the voltage to an adjustment voltage is mounted.

  Then, by adjusting the adjustment voltage by the regulator, the output voltage of the alternator is set to the first voltage (for example, 12V) at the normal time when the regenerative power generation is not performed, thereby reducing the drive load of the alternator for the internal combustion engine and improving the fuel consumption. Conventionally, variable voltage control is known in which the output voltage of the alternator is set to a second voltage (for example, 15 V) higher than the first voltage to increase the regenerative power. Here, regarding the headlight and the wiper of the electric load, if the voltage of the supplied power changes, the blinking of the headlight and the change in the operation speed of the wiper occur. Therefore, it is required to make the voltage of the supplied power constant. . Therefore, in switching between regenerative power generation and non-regenerative power generation, control is performed so that the rate of change of the output voltage of the alternator is not more than a predetermined speed. As a result, the change rate of the voltage of the supplied power is set to a predetermined speed or less for the electric load that is required to make the voltage of the supplied power constant.

  Moreover, as an in-vehicle power supply system mounted on a vehicle, two storage batteries such as a lead storage battery (first storage battery) and a lithium ion storage battery (second storage battery) are used, and electric power is supplied to various in-vehicle electric loads while using these storage batteries properly. Is known (see, for example, Patent Document 1). Specifically, the lithium ion storage battery is electrically connected to the alternator and the lead storage battery via a connection switch as an opening / closing means, and the lithium ion ion is connected from the alternator to the conduction state during regenerative power generation. Power supply to the storage battery is possible.

JP 2011-178384 A

  At the time of regenerative power generation by the alternator, to switch the connection switch from the state in which the connection switch is made conductive to charge both storage batteries to the disconnected state at the end of the regenerative power generation, lead at the time of the switching switching. It is desirable to reduce the output voltage of the storage battery to a predetermined cutoff permission voltage. As a result, it is possible to suppress problems such as unintended voltage fluctuations caused by surges in the connection lines connecting both storage batteries.

  In this case, after the end of regenerative power generation, the output voltage of the alternator is changed from the second voltage to the first voltage lower than that, but at that time, when the connection switch is cut off (the output voltage of the lead-acid battery) If the output voltage of the alternator is still high when the voltage drops to the cutoff permission voltage), the output voltage of the lead-acid battery suddenly rises due to the output voltage, and as a result, the supply voltage must be kept constant. There is a risk that the supply voltage to the electrical load will change suddenly and its operation will become unstable.

  In the vehicle power supply system in which the generator and the first storage battery and the second storage battery are connected via the connection switch, the present invention suppresses the unstable operation of the electric load when the connection switch is cut off. The main purpose is to do.

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

  The invention according to claim 1 electrically connects the generator (10), the first storage battery (20) and the second storage battery (30) connected in parallel to the generator, and both the storage batteries. A connection switch (50) provided on a connection line (15) to be connected, and for switching between conduction and interruption between the first storage battery and the generator and the second storage battery, It is a vehicle power supply system in which a storage battery is charged.

  Furthermore, the first storage battery is connected to an electric load (42) that is required to have a change in supply voltage with time that is not more than a predetermined change amount, and the output voltage (Vreg) of the generator during non-regenerative power generation. ) To a predetermined non-regenerative voltage, and at the time of regenerative power generation, the generator control means (80) for controlling the output voltage of the generator to a regenerative voltage higher than the non-regenerative voltage, and the first storage battery The voltage detection means (80) for detecting the output voltage and charging the both storage batteries by controlling the connection switch to the conductive state during regenerative power generation, and after the end of the regenerative power generation, the output of the first storage battery Switch control means (70) for controlling the connection switch to a cut-off state when the voltage drops to a predetermined cut-off permission voltage, and the power generation control means at the time of regenerative power generation, A target voltage of the storage battery is set so that the deviation between the target voltage and the detected voltage detected by the voltage detecting means is not more than a predetermined amount and not higher than a predetermined voltage width with respect to the target voltage. The output voltage of the generator is set, and the output voltage of the generator is controlled by the set voltage.

  According to the above configuration, at the time of regenerative power generation, the deviation between the target voltage of the first storage battery and the detected voltage (the detected value of the output voltage of the first storage battery) is less than or equal to a predetermined amount and is predetermined with respect to the target voltage. The output voltage of the generator is set so as not to become higher than the voltage width of the generator, and the output voltage of the generator is controlled by the set voltage. Thereby, the output voltage of the first storage battery can be controlled so as not to be excessively separated from the target voltage.

  In addition, while the output voltage of the first storage battery is controlled with respect to the target voltage in this way, the output voltage of the generator is controlled so as not to be higher than a predetermined voltage width with respect to the target voltage. It is possible to adjust the voltage difference (separation amount) of the output voltage of the generator with respect to the output voltage of the first storage battery. Thereby, the voltage difference between the output voltage of the first storage battery and the output voltage of the generator can be reduced when the connection switch is shut off (when the output voltage of the first storage battery drops to the shut-off permission voltage). The output voltage of the first storage battery can be prevented from rapidly increasing. That is, the inconvenience that the operation of the electric load becomes unstable can be suppressed. As a result, it is possible to eliminate the inconvenience when the connection switch provided between the first storage battery and the second storage battery is shut off, and to realize a stable operation of the electric load.

The block diagram which shows the outline of the power supply system in this embodiment. The flowchart showing the conventional adjustment voltage control processing. The timing chart showing the conventional adjustment voltage control processing. The functional block diagram showing the function which concerns on the adjustment voltage control process in this embodiment. The flowchart showing the adjustment voltage control process in this embodiment. The timing chart showing the adjustment voltage control process in this embodiment.

  Hereinafter, embodiments embodying the present invention will be described with reference to the drawings. 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 as a first storage battery, a lithium ion storage battery 30 as a second storage battery, various electric loads 41, 42, 43, and a connection switch. MOS switch 50 and SMR switch 60 as a storage battery switch. 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 higher charge / discharge energy efficiency, 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).

  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 (X 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 also an emergency opening / closing means, and is normally held in an ON state by an ON signal 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 adjustment voltage Vreg becomes abnormally high, there is a concern that the lithium ion storage battery 30 is 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 detects the output current, output voltage, and temperature of the lithium ion storage battery 30. The ECU 70 is connected to an ECU 80 (electronic control unit) outside the battery unit. That is, these ECUs 70 and 80 are connected by a communication network such as LIN and can communicate with each other, and various data stored in the ECUs 70 and 80 can be shared with each other.

  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.

  Moreover, the load shown by the code | symbol 41 among the electric loads 41-43 is a starter motor which starts an engine, and the load shown by the code | symbol 42 is general except the electric load 43 (constant voltage request | requirement electric load) and the starter 41. Electric 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 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 41 and the electric load 42.

  Here, of the general electric load 42, the headlight, the wiper, the blower fan, and the like, when the supply power voltage changes, the headlight blinks, the wiper operating speed changes, the blower fan rotational speed changes (fan noise change). ) Occurs, it is required to make the voltage of the supplied power constant. Hereinafter, among the general electric loads 42, such a load that is required to have a constant voltage is referred to as a “constant voltage request load”.

  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 excitation current flowing through the rotor coil, so that the voltage of the generated direct current is adjusted to the adjustment 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) in which overcharge / discharge does not occur. That is, as described above, the adjustment voltage Vreg is adjusted by the ECU 80 and the operation of the MOS switch 50 is controlled by the ECU 70 so as not to cause excessive charging / discharging.

  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 both the storage batteries 20 and 30 are connected in parallel, when charging is performed by the alternator 10, if the MOS switch 50 and the SMR switch 60 are turned on, the storage battery on the lower output voltage side is used. On the other hand, the electromotive current of the alternator 10 flows. On the other hand, when power is supplied (discharged) to the electric loads 42 and 43, if the MOS switch 50 and the SMR switch 60 are turned on during non-power generation, the discharge from the storage battery having the higher output voltage to the electric load is performed. Will be made.

  Incidentally, at the time of regenerative charging, the lithium ion storage battery 30 is charged in preference to the lead storage battery 20 so that the output voltage of the lithium ion storage battery 30 becomes lower than the output voltage of the lead storage battery 20. It has become. This setting can be realized by setting the open-circuit voltage and internal resistance value of both the storage batteries 20 and 30. The open-circuit voltage is set by selecting the positive electrode active material, the negative electrode active material, and the electrolytic solution of the lithium ion storage battery 30. This is possible.

  The vehicle according to this 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 with the engine being automatically stopped. The ECU 80 has a stop function, and the idling stop control is performed by the ECU 80. In the idling stop control, when the engine is automatically stopped, the ECU 70 operates the MOS switch 50 to be in an on (conductive) state in order to charge (regenerate) the lithium ion storage battery 30 in the process of decreasing the engine rotation 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.

  Further, when the vehicle travels other than during regenerative charging, the ECU 70 operates the MOS switch 50 to be in an off state and the SMR switch 60 to be in an on state. Since the connection between the alternator 10 and the lead storage battery 20 and the electric load 43 is cut off and the connection between the lithium ion storage battery 30 and the electric load 43 is brought into conduction, the lithium ion storage battery 30 alone has power for the electric load 43. Supply is made. Thereby, at the time of regenerative power generation, the generated power can be positively charged to the lithium ion storage battery 30. Since the lithium ion storage battery 30 has higher energy efficiency at the time of charging / discharging than the lead storage battery 20, it can improve the charging / discharging efficiency as the whole power supply system.

  Conventionally, the ECU 80 performs control to make the adjustment voltage Vreg during regenerative power generation higher than the adjustment voltage Vreg during non-regenerative power generation. With this control, it is possible to increase the amount of power generated by the alternator 10 during regenerative power generation and reduce the load on the output shaft of the engine accompanying power generation by the alternator 10 during non-regenerative power generation.

  FIG. 2 is a flowchart showing control of the conventional adjustment voltage Vreg. The adjustment voltage control process is performed in the ECU 80 at a predetermined time period.

  In step S01 of FIG. 2, it is determined whether regenerative power generation is being performed. When regenerative power generation is being performed (S01: YES), in step S02, the adjustment voltage Vreg is controlled to be a high voltage (for example, 15V). In step S03, the MOS switch 50 and the SMR switch 60 are controlled to be turned on, and the process is terminated. When regenerative power generation is not performed (S01: NO), the adjustment voltage Vreg is controlled to a low voltage (for example, 12V) in step S04. In step S05, the MOS switch 50 is turned off and the SMR switch 60 is turned on, and the process ends.

  FIG. 3 shows a timing chart showing the time variation of the adjustment voltage and V (Pb) when the adjustment voltage control shown in FIG. 2 is performed.

  At time T0 in FIG. 3, the fuel cut flag (F / C flag) is turned on, and the ECU 80 performs regenerative power generation in the alternator 10. By executing the regenerative power generation, the ECU 80 controls the adjustment voltage to a high value (15V). Further, the regenerative power generation is performed, whereby the ECU 70 controls the MOS switch 50 to be in an on state. When the MOS switch 50 is controlled to be in the ON state, the lead storage battery 20 and the lithium ion storage battery 30 are connected, and the output voltage V (Pb) of the lead storage battery 20 has a value of about 13V.

  At time T1, the F / C flag is turned off, and the ECU 80 stops regenerative power generation in the alternator 10. When the regenerative power generation is stopped, the ECU 80 adjusts the regulator of the alternator 10 and controls the adjustment voltage Vreg to decrease from 15V toward a lower voltage (12V). At this time, the adjustment voltage Vreg gradually decreases at a predetermined decrease rate.

  Further, when the regenerative power generation is stopped, the ECU 70 controls the MOS switch 50 to be turned off. The MOS switch 50 is controlled to be in the off state, whereby the alternator 10, the lead storage battery 20, and the lithium ion storage battery 30 are disconnected. As a result, the current flowing from the alternator 10 to the lithium ion storage battery 30 flows to the lead storage battery 20. As a result, the output voltage V (Pb) of the lead storage battery 20 approaches the adjustment voltage Vreg that is the output voltage of the alternator 10. Furthermore, when a transient current flows through the lead storage battery 20, V (Pb) temporarily becomes a voltage exceeding the adjustment voltage Vreg. For this reason, immediately after time T1, V (Pb) rapidly increases by 1.7V from 13.3V to 15V. When V (Pb) increases rapidly, the voltage supplied to the electric load 42 (constant voltage required load) increases rapidly, and the operation of the constant voltage required load becomes unstable.

  Therefore, the ECU 80 of the present embodiment controls the adjustment voltage Vreg to be close to the detected value of V (Pb) during regenerative power generation, and is accompanied by switching of the MOS switch 50 from the on state to the off state when regenerative power generation is stopped. The fluctuation of V (Pb) is suppressed. This stabilizes the operation of the electric load 42 (constant voltage required load).

  Further, the ECU 80 sets a target voltage that is a target value of V (Pb), and sets the target voltage during regenerative power generation higher than the target voltage during non-regenerative power generation. Then, when switching from non-regenerative power generation to regenerative power generation, the target voltage is gradually increased, and when switching from regenerative power generation to non-regenerative power generation, the target voltage is gradually decreased. The ECU 80 calculates the adjustment voltage Vreg based on the detected value of V (Pb) and the target voltage so as to reduce the difference between the target voltage and the detected value of V (Pb), and outputs the output voltage of the alternator 10. The regulator is controlled so as to become the calculated adjustment voltage Vreg. Thereby, the power generation amount of the alternator 10 at the time of regenerative power generation can be increased, and the engine load accompanying the power generation of the alternator 10 at the time of non-regenerative power generation can be reduced.

  FIG. 4 is a functional block diagram showing functions related to the adjustment voltage Vreg calculation process performed by the ECU 80 in the present embodiment. The target voltage upper limit value calculation unit B01, the target voltage calculation unit B02, and the target voltage gradual change unit B03 of the ECU 80 calculate the target voltage based on the detected value of V (Pb). Further, the separation voltage calculation unit B06, the separation voltage integration unit B08, the first integration upper limit value calculation unit B04, the second integration upper limit value calculation unit B05, the integration upper limit value calculation unit B07, the adjustment voltage request value calculation unit B09, the adjustment of the ECU 80 The voltage gradual change unit B10 and the adjustment voltage calculation unit B11 calculate the adjustment voltage Vreg based on the target voltage and the separation voltage that is the difference between the target voltage and the detected value of V (Pb).

  The output voltage V (Pb) of the lead storage battery 20 detected by the ECU 80 and the allowable separation voltage are input to the target voltage upper limit value calculation unit B01. The target voltage upper limit value calculation unit B01 adds V (Pb) and the separation allowable voltage to calculate a target voltage upper limit value that is an upper limit value of the target voltage.

  A target voltage upper limit value, a target voltage lower limit value, and a target voltage request value are input to the target voltage calculation unit B02. Here, as the target voltage request value, a high voltage (14 V) is input during regenerative power generation, and a low voltage (12.5 V) is input during non-regenerative power generation. The target voltage calculation unit B02 outputs the target voltage upper limit value as the target voltage when the target voltage request value is higher than the target voltage upper limit value. When the target voltage request value is equal to or lower than the target voltage upper limit value and equal to or higher than the target voltage lower limit value, the target voltage request value is output as the target voltage. When the target voltage request value is lower than the target voltage lower limit value, the target voltage lower limit value is output as the target voltage.

  The target voltage gradually changing unit B03 receives the target voltage output from the target voltage calculating unit B02 and the voltage change speed limit value. When the target voltage change rate is faster than the voltage change rate limit value, the target voltage gradual change unit B03 outputs the target voltage that is gradually changed so that the target voltage change rate is equal to or less than the voltage change rate limit value.

  The target voltage and V (Pb) output from the target voltage gradual change unit B03 are input to the separation voltage calculation unit B06. The separation voltage calculation unit B06 calculates a separation voltage between the target voltage and V (Pb) by subtracting V (Pb) from the target voltage.

  The separation voltage output from the separation voltage calculation unit B06 is input to the separation voltage integration unit B08. The separation voltage integration unit B08 calculates a time integration value of the separation voltage and outputs it as the separation voltage integration value. Further, when the integration upper limit value is input from the integration upper limit calculation unit B07 to the separation voltage integration unit B08, and the separation voltage integration value exceeds the integration upper limit value, the separation voltage integration unit B08 uses the integration upper limit value as the separation voltage integration. Output as a value.

  Here, the integration upper limit value calculation unit B07 includes a first integration upper limit value calculated by the first integration upper limit value calculation unit B04 and a second integration upper limit value calculated by the second integration upper limit value calculation unit B05. Entered. The integration upper limit value calculation unit B07 outputs a lower value of the first integration upper limit value and the second integration upper limit value as the integration upper limit value.

  The target voltage and the adjustment voltage upper limit value are input to the first integration upper limit value calculation unit B04. The first integration upper limit calculation unit B04 outputs a value obtained by subtracting the target voltage from the adjustment voltage upper limit value as the first integration upper limit value. The second integral upper limit calculation unit B05 receives the wiring resistance due to the wiring between the alternator 10 and the lead storage battery 20 and the alternator current output from the alternator 10 during regenerative power generation. The second integration upper limit value calculation unit B05 calculates the maximum value of the drop voltage in the wiring between the alternator 10 and the lead storage battery 20 by integrating the wiring resistance and the alternator current during regenerative power generation, and the second integration. Output as the upper limit.

  The target voltage and the separation voltage integrated value are input to the adjustment voltage request value calculation unit B09. The adjustment voltage request value calculation unit B09 adds the separation voltage integral value to the target voltage and outputs the result as the adjustment voltage request value. The adjustment voltage request value is gradually changed by the adjustment voltage gradual change unit B10 so that the change speed is equal to or less than the voltage change speed limit value.

  The adjustment voltage calculation unit B11 receives the adjustment voltage request value, the adjustment voltage upper limit value, and the adjustment voltage lower limit value. When the adjustment voltage request value exceeds the adjustment voltage upper limit value, the adjustment voltage calculation unit B11 calculates the adjustment voltage upper limit value as the adjustment voltage. In addition, when the adjustment voltage request value is equal to or less than the adjustment voltage upper limit value and equal to or more than the adjustment voltage lower limit value, the adjustment voltage calculation unit B11 calculates the adjustment voltage request value as the adjustment voltage. When the adjustment voltage request value is lower than the adjustment voltage lower limit value, the adjustment voltage calculation unit B11 calculates the adjustment voltage lower limit value as the adjustment voltage. The adjustment voltage calculation unit outputs the calculated voltage value of the adjustment voltage to the adjustment voltage command unit. The adjustment voltage command unit adjusts the regulator of the alternator 10 and controls the voltage output from the alternator 10 to be the adjustment voltage.

  FIG. 5 is a flowchart showing the control of the adjustment voltage Vreg performed by the ECU 80 in the present embodiment. The adjustment voltage control process is performed in the ECU 80 at a predetermined time period.

  In step S11, it is determined whether or not regenerative power generation is being performed. When regenerative power generation is being performed (S11: YES), in step S12, the MOS switch 50 is turned on and the SMR switch 60 is turned on, and the alternator 10 and the lithium ion storage battery 30 are connected. After the alternator 10 and the lithium ion storage battery 30 are connected, a process of increasing the target voltage to the target voltage (14 V) during regenerative power generation is performed in steps S13 and S16. In step S13, it is determined whether or not the target voltage has increased to a voltage value (14V) during regenerative power generation. When the target voltage ≧ 14V (S13: YES), in step S14 and in step S15, the adjustment voltage Vreg is used based on the detected value of V (Pb) and the target voltage using the adjustment voltage calculation process shown in FIG. Is calculated. In step S15, the regulator is controlled so that the output voltage of the alternator 10 becomes the adjustment voltage Vreg, and the process ends.

  In step S13, if the target voltage is less than 14V (S13: NO), a process of gradually increasing the target voltage is performed in step S16. And the process of step S14, S15 is performed and a process is complete | finished.

  If regenerative power generation is not performed in step S11 (S11: NO), in steps S17 and S20, processing is performed to reduce the target voltage to the target voltage (12.5 V) during non-regenerative power generation. In step S17, it is determined whether or not the target voltage has decreased to a voltage value (12.5 V) during non-regenerative power generation. When the target voltage ≦ 12.5 V (S17: YES), the adjustment voltage Vreg is calculated based on the detected value of V (Pb) and the target voltage using the adjustment voltage calculation process shown in FIG. 4 in step S18. In step S19, the regulator is controlled so that the output voltage of the alternator 10 becomes the adjustment voltage Vreg. Further, when the target voltage> 12.5 V (S17: NO), the process of steps S18 and S19 is performed after the process of gradually reducing the target voltage in step S20.

  After the process of step S19, in step S21, it is determined whether or not the detected value of V (Pb) has dropped below the MOS-OFF voltage (13V). If V (Pb) ≦ 13V (S21: YES), in step S22, the MOS switch 50 is turned off and the SMR switch 60 is turned on, and the process is terminated. If V (Pb)> 13V (S21: NO), the process is terminated as it is.

  FIG. 6 is a timing chart showing the time variation of the adjustment voltage, the target voltage, and V (Pb) in the present embodiment. The adjustment voltage is represented by a two-dot chain line, the target voltage is represented by a one-dot chain line, and V (Pb) is represented by a solid line.

  At time T10 in FIG. 6, the F / C flag is turned off, and regenerative power generation is not performed. For this reason, the ECU 80 sets the target voltage to a low value (12.5 V). The ECU 80 calculates the adjustment voltage Vreg so that the difference between the target voltage and the adjustment voltage Vreg becomes the maximum value of the drop voltage in the wiring between the alternator 10 and the lead storage battery 20. Then, the ECU 80 controls the regulator so that the output voltage of the alternator 10 becomes the calculated adjustment voltage Vreg. Further, since regenerative power generation is not performed, the ECU 70 controls the MOS switch 50 to be in an off state. As a result, V (Pb) is close to the adjustment voltage Vreg.

  At time T11, the F / C flag is switched from the off state to the on state, and regenerative power generation is performed. For this reason, ECU80 raises a target voltage toward the voltage (14V) at the time of regenerative power generation. The ECU 80 controls the rate of increase of the target voltage so as to become the voltage change rate limit value (1 V / second). Further, the ECU 80 performs control to increase the adjustment voltage Vreg as the target voltage increases.

  Further, by switching from the non-regenerative power generation state to the regenerative power generation state, the ECU 70 performs control to switch the MOS switch 50 from the off state to the on state. At this time, the lead storage battery 20 and the lithium ion storage battery 30 are connected, and V (Pb), which is the output voltage of the lead storage battery 20, temporarily decreases to a value close to the output voltage of the lithium ion storage battery 30. After time T11, V (Pb) increases as the adjustment voltage Vreg increases.

  At time T12, the separation voltage that is the difference between the target voltage and the detected value of V (Pb) reaches the separation allowable voltage. After time T12, the ECU 80 sets a target voltage with “V (Pb) + separation allowable voltage” as an upper limit value. Then, control is performed to increase the adjustment voltage Vreg so that the difference between the target voltage and V (Pb) decreases.

  At time T13, the target voltage reaches the voltage value (14V) during regenerative power generation. The ECU 80 subsequently performs control to increase the adjustment voltage Vreg based on the integration value of the separation voltage so that the difference between the target voltage and the detected value of V (Pb) decreases.

  At time T14, since the difference between the target voltage and the adjustment voltage Vreg reaches the maximum value of the drop voltage in the wiring between the alternator 10 and the lead storage battery 20, the ECU 80 determines that “Vreg = target voltage + drop voltage” after time T14. The adjustment voltage Vreg is controlled so as to be “the maximum value”. From time T14 to T15, the electric power generated in the alternator 10 is charged into the lead storage battery 20, whereby V (Pb) gradually increases.

  At time T15, the F / C flag is turned off and regenerative power generation is stopped. When the regenerative power generation is stopped, the ECU 80 reduces the target voltage toward the voltage (12.5 V) at the time of non-regenerative power generation. The ECU 80 controls the reduction rate of the target voltage so as to become the voltage change rate limit value (1 V / second). Furthermore, since the ECU 80 controls the adjustment voltage Vreg so that “Vreg = target voltage + maximum value of the drop voltage”, the adjustment voltage Vreg decreases at the same speed as the target voltage decrease speed. As the adjustment voltage Vreg decreases, the detected value of V (Pb) also decreases. At time T15, since the regenerative power generation in the alternator 10 is finished, the voltage drop in the wiring between the alternator 10 and the lead storage battery 20 decreases. For this reason, after time T15, the detected value of V (Pb) gradually approaches the adjustment voltage Vreg.

  At time T16, since the detected value of V (Pb) drops to the MOS-OFF voltage (13V), the ECU 80 instructs the ECU 70 to control the MOS switch 50 to be off and the SMR switch 60 to be on. Do. When the MOS switch 50 is switched from the on state to the off state, the current flowing from the alternator 10 to the lithium ion storage battery 30 flows into the lead storage battery 20. Here, as the regenerative power generation is stopped, the alternator current is 0 A, and the drop voltage in the wiring between the alternator 10 and the lead storage battery 20 is 0V. For this reason, before and after the MOS switch 50 is switched from the on state to the off state, the adjustment voltages Vreg and V (Pb) have substantially the same voltage value. Therefore, the voltage V (Pb) does not rapidly increase, and the electric load 42 operates stably.

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

  (1) According to the above configuration, during regenerative power generation, the deviation between the target voltage of the lead storage battery 20 and the detected value V (Pb) of the output voltage is less than a predetermined amount (separation allowable voltage) and the target voltage. Therefore, the adjustment voltage Vreg is set so as not to be higher than a predetermined voltage width (drop voltage due to wiring resistance), and the output voltage of the alternator 10 is controlled by the adjustment voltage Vreg. Thereby, the output voltage of the lead storage battery 20 can be controlled so as not to be excessively separated from the target voltage.

  Moreover, since the output voltage of the lead storage battery 20 is controlled with respect to the target voltage in this way, the output voltage of the alternator 10 is controlled so as not to be higher than a predetermined voltage width with respect to the target voltage. In addition, it is possible to adjust a voltage difference (an amount of separation) of the output voltage of the alternator 10 with respect to the output voltage of the lead storage battery 20. Thereby, when the MOS switch 50 is shut off (when the output voltage of the lead storage battery 20 is lowered to the shut-off permission voltage), the voltage difference between the output voltage of the lead storage battery 20 and the output voltage of the alternator 10 can be reduced. It is possible to suppress a sudden increase in the output voltage of the lead storage battery 20. That is, the inconvenience that the operation of the electric load 42 becomes unstable can be suppressed. As a result, the inconvenience at the time of interruption of the MOS switch 50 provided between the lead storage battery 20 and the lithium ion storage battery 30 can be solved, and the stable operation of the electric load 42 can be realized.

  (2) The ECU 80 sets the target voltage of the lead storage battery 20 during regenerative power generation to be higher than the target voltage during non-regenerative power generation. Then, the ECU 80 controls the adjustment voltage Vreg so that the target voltage and the detected value of V (Pb) do not deviate from the separation allowable voltage or more, so that V (Pb) during regenerative power generation becomes V (P Pb) can be higher. As a result, during regenerative power generation, the lead storage battery 20 can be charged efficiently, and the load caused by the alternator 10 during non-regeneration can be reduced to improve fuel efficiency.

  (3) The difference between the adjustment voltages Vreg and V (Pb), which are output voltages of the alternator 10, corresponds to a drop voltage due to the wiring resistance between the alternator 10 and the lead storage battery 20. Therefore, by setting the difference between the adjustment voltage Vreg and the target voltage to the drop voltage, and performing control to bring V (Pb) and the target voltage closer, the difference between the adjustment voltage Vreg and V (Pb) is obtained. Approach the drop voltage. As a result, the increase in V (Pb) when the MOS switch 50 is turned off can be brought close to 0V.

(Other embodiments)
You may change the said embodiment as follows, for example.

  In the above embodiment, the drop voltage is obtained as the product of the wiring resistance and the maximum value of the alternator current. However, a configuration may be adopted in which the drop voltage is calculated by detecting the current alternator current.

  -The separation voltage that is the difference between the detected value of V (Pb) and the target voltage is integrated, and the adjustment voltage is calculated based on the integration value. For example, the value obtained by adding the separation voltage to the target voltage is It is good also as a structure calculated as adjustment voltage Vreg.

  The detection value of V (Pb) and the target voltage are allowed to be separated up to the separation allowable voltage, but the adjustment voltage Vreg is calculated so that V (Pb) and the target voltage value are equal. It is good also as a structure.

  DESCRIPTION OF SYMBOLS 10 ... Alternator, 15 ... Feed line, 20 ... Lead storage battery, 30 ... Lithium ion storage battery, 42 ... Electric load, 50 ... MOS switch, 70, 80 ... ECU.

Claims (3)

A generator (10);
A first storage battery (20) and a second storage battery (30) respectively 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 disconnection between the first storage battery and the generator and the second storage battery; A vehicle power supply system in which the storage batteries are charged by regenerative power generation of a machine,
The first storage battery is connected to an electrical load (42) that is required to have a change in supply voltage with time over a predetermined amount of change,
Power generation for controlling the output voltage (Vreg) of the generator to a predetermined non-regenerative voltage during non-regenerative power generation and controlling the output voltage of the generator to a regenerative voltage higher than the non-regenerative voltage during regenerative power generation Control means (80);
Voltage detection means (80) for detecting the output voltage of the first storage battery;
The connection switch is controlled to be in a conductive state during regenerative power generation, so that the both storage batteries are charged, and the connection is performed when the output voltage of the first storage battery drops to a predetermined cutoff permission voltage after the end of regenerative power generation. Switch control means (70) for controlling the switch to a cut-off state;
With
The power generation control means sets a target voltage of the first storage battery during regenerative power generation so that a deviation between the target voltage and a detection voltage detected by the voltage detection means is not more than a predetermined amount, and A power supply system for a vehicle, wherein an output voltage of the generator is set so as not to be higher than a predetermined voltage width with respect to the voltage, and the output voltage of the generator is controlled by the set voltage. The power generation control means sets a first target value as a target voltage of the first storage battery during non-regenerative power generation, and sets a second target value of a voltage higher than the first target value during regenerative power generation. when changing the target voltage have accompanied the switching of the power generation state and the non-regenerative power generation state from the first target value to the second target value, or the first target value the target voltage from the second target value The vehicle power supply system according to claim 1 , wherein the target voltage is gradually changed when changing to the above.   The power generation control means calculates a voltage drop amount due to the wiring resistance based on a wiring resistance between the generator and the first storage battery and an output current of the generator as the predetermined voltage width, The vehicle power supply system according to claim 1 or 2, wherein an output voltage of the generator is set so as not to be higher than the voltage drop amount with respect to a target voltage.