JP2016220305A - Hybrid automobile and charge control device therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To efficiently charge batteries with regenerative energy that an alternator generates, without using a DC/DC converter in a hybrid automobile in which a plurality of batteries with different rating voltages are mounted.SOLUTION: In a battery 2 of which the rating voltage is 12 V and a battery 3 of which the rating voltage is 48 V, battery controllers 2a and 3a are provided together and a battery state is detected in a predetermined sampling cycle. In a charge control part 6, an SOC calculation part 6a estimates an SOC of each of the batteries based on each of battery states. Based on the estimated SOC of each of the batteries, a battery selection part 6b selects a battery subjected to regenerative charge and notifies a charge path selector 7 of a selection result. A variable voltage setting part 6c sets an output voltage corresponding to the rating voltage of the selected battery to a variable voltage alternator 1. The charge path selector 7 sets up a path for regenerative charge between the variable voltage alternator 1 and the selected battery.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a hybrid vehicle and a charge control device thereof, and more particularly, to a hybrid vehicle and a charge control device thereof that efficiently charge regenerative energy during braking to a plurality of in-vehicle batteries having different rated voltages.

  As a hybrid vehicle combining an electric vehicle and an engine vehicle, there are known methods that use an electric motor for assisting the engine driving force and methods that do not use it. The latter uses an idling stop function that automatically stops the engine when the vehicle is stopped ( ISS) and a vehicle having a regenerative charging function for charging a battery with regenerative energy at the time of braking are particularly attracting attention as μHEV.

  As shown in Fig. 6 (a), μHEV is equipped with only a battery with a rated voltage of 12V (lead battery), and the regenerative energy output by the alternator during braking is used for charging the battery and consuming it in the low-voltage auxiliary machine. Although it is configured to be used, for example, as disclosed in Patent Documents 1 and 2, various methods have been proposed from the viewpoint of improving charging efficiency and extending the battery life.

  The μHEV in Fig. 2 (b) is equipped with a 12V main battery (lead battery) and sub battery (lead / lithium ion capacitor (LIC) / lithium ion battery (LIB)), and each battery's SOC (State Of Charge: Charge amount or remaining battery level) is constantly monitored, and regenerative energy output by the alternator during braking is charged to a battery with a lower SOC selected by the selector.

  The μHEV in Fig. 2 (c) is equipped with a 12V main battery (lead battery) and sub battery (LIB). Power is supplied from each battery to each auxiliary machine without generating power when the engine is running, and switch SW is used during braking. Is closed and regenerative energy is charged to each battery.

  The μHEV in the figure (d) is equipped with a 12V main battery (lead) for engine starting and auxiliary equipment and a 25V sub battery (capacitor) for regenerative charging. The alternator has a variable output voltage. The main battery is charged via a bypass relay with a charging voltage of 12 V, the output voltage of the alternator is switched to 25 V during braking, the sub battery is charged, and the main battery is charged via a DC / DC converter.

  The μHEV in Fig. 6 (e) reduces the main battery discharge load by connecting a 12V main battery (lead battery) and a sub battery (NiMh) in parallel and preferentially charging and discharging the sub battery. Thus, the battery life can be extended.

Japanese Patent No. 3703749 International Patent No. 2014/068953

  Conventionally, a 12V single power supply system has been generally used for passenger cars. However, in order to improve efficiency and improve redundancy, a 48V power supply system and a DC / DC converter are combined to provide a 12V supplement. Attention has been focused on a power supply system that can be used together with a 48V auxiliary machine.

  However, if a vehicle with such a power supply system is converted into a hybrid vehicle and a regenerative charging system is applied, the regenerative energy output by the alternator is directly applied to the capacitor-type sub-battery with a wide rated voltage range, and the rated voltage is reduced. The 12V main battery must be supplied after being stepped down by a DC / DC converter. Therefore, it was indispensable to use an expensive and large DC / DC converter capable of handling a large current during regenerative braking.

  An object of the present invention is to solve the above technical problem and efficiently charge each battery with regenerative energy generated by an alternator without using a DC / DC converter in a hybrid vehicle equipped with a plurality of batteries with different rated voltages. An object of the present invention is to provide a hybrid vehicle and a charging control device thereof.

  In order to achieve the above object, the present invention is characterized in that a hybrid vehicle that controls charging by regenerative energy output from a variable voltage alternator and a charging control device thereof have the following configurations.

(1) Means for detecting the state of charge of a plurality of batteries having different rated voltages, means for selecting a battery to be charged based on the state of charge of each battery, and the output voltage of the variable voltage alternator according to the selected battery And a means for establishing a path for charging the selected battery with the regenerative energy generated by the variable voltage alternator.
(2) The means for detecting the state of charge detects the SOC of each battery, and the means for selecting a battery selects a battery with a lower SOC.
(3) The battery selection means detects the remaining charge, rated voltage, power consumption and / or internal impedance of each battery, and selects a battery with higher charging efficiency based on these.

According to the present invention, the following effects are achieved.
(1) Regenerative energy can be efficiently charged to a plurality of batteries with different rated voltages without using an expensive and inefficient DC / DC converter.

  (2) Since the regenerative energy can be sufficiently consumed by efficient charging, a large regenerative braking force can be obtained by the alternator.

  (3) Compared the state of charge of each battery, select one battery that can charge regenerative energy more efficiently and preferentially charge it, so that more effective use of regenerative energy becomes possible, A larger regenerative braking force can be obtained.

  (4) Since the charging efficiency of each battery is quantitatively evaluated based on the remaining charge, rated voltage, power consumption and / or internal impedance, a battery with higher charging efficiency can be selected accurately. It becomes like this.

It is the block diagram which showed the structure of the charging system for vehicles to which this invention was applied, and its mounting vehicle. It is the figure which showed the method by which a charge control part selects any one of a main battery and a sub battery as charging object according to the SOC. It is the flowchart (the 1) which showed the selection procedure of the battery for charge. It is the flowchart (the 2) which showed the selection procedure of the battery for charge. It is the figure which showed the method by which a charge path | route selector establishes a charge path | route based on the selection result of a charge object battery. It is the figure which showed the regenerative charge system in the conventional μHEV.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is a block diagram illustrating a configuration of a main part of a hybrid vehicle to which the present invention is applied and a charge control device thereof.

  In the present embodiment, application to a hybrid vehicle having the configuration shown in FIG. 1 will be described as an example. However, the present invention is not limited to this, and a plurality of variable voltage alternators and terminal voltages (rated voltages) are different. This battery can be applied to any charging system as long as it is a system that charges each battery with regenerative energy during vehicle braking.

  The driving force generated by the engine E is transmitted to the driving wheel 33 via the driving shaft 31 and the differential gear 32 and is input to the rotating shaft of the variable voltage alternator 1 via the power distribution mechanism 34. The alternator 1 outputs regenerative energy during braking and can output charging energy as needed during normal travel.

  The main battery 2 is a low voltage battery. In this embodiment, a lead battery, NiMH battery, NiZn battery, LIB, or the like having a rated voltage of about 12V is assumed. The sub battery 3 is a high voltage battery. In this embodiment, a lead battery, LIC, LIB, NiZn battery, NiMH battery or EDLC having a rated voltage of about 48V is assumed.

  The low-voltage auxiliary machine 4 is an auxiliary machine such as a lighting device having a rated voltage of low voltage (12 V) and relatively low power consumption. The high-voltage auxiliary machine 5 is an auxiliary machine such as an electric device having a rated voltage of a high voltage (48V) and relatively large power consumption.

  Each battery 2 and 3 is provided with a battery controller 2a and 3a, respectively, and detects the battery status such as the rated voltage, temperature and charge / discharge current of each battery 2 and 3 at a predetermined sampling period (for example, at intervals of 10 ms) . The charge / discharge current can be detected by a current sensor 8 such as a Hall element or a shunt resistor.

  In the charge controller 6, the SOC calculator 6a estimates the SOC (State Of Charge) of each battery based on the battery state collected from each battery controller 2a, 3a. The battery selection unit 6b selects a target battery for regenerative charging based on the estimated SOC of each battery, and notifies the charging path selector 7 of the selection result. The variable voltage setting unit 6c sets an output voltage in the alternator 1 according to the rated voltage of the selected battery.

  The charging path selector 7 establishes a charging path between the alternator 1 and each of the batteries 2 and 3 and each of the auxiliary machines 4 and 5 so that the regenerative energy during braking is preferentially charged to the selected battery. To do.

  FIG. 2 is a diagram illustrating a method in which the charging control unit 6 selects one of the main battery 2 and the sub battery 3 as a target battery for regenerative charging according to the estimated SOC and the like. Is a flowchart showing the procedure.

  In step S1 of FIG. 3, for each of the main battery 2 and the sub battery 3, rated voltages Vm, Vs, integrated values of charge / discharge currents Im, Is, and temperatures detected by the battery controllers 2a, 3a at a predetermined sampling period. Based on T and the known battery capacities Cm, Cs and the like, the current estimated SOC (SOCm, SOCs) is estimated by the SOC calculation unit 6a. At this time, the terminal voltages Vm, Vs and the charge / discharge currents Im, Is are temperature compensated to values corresponding to the reference temperature.

  In step S2, the estimated SOCm and SOCs of each battery 2 and 3 are compared with a predetermined lower limit reference value SOCref2. In the present embodiment, the maximum SOC value that can promote the deterioration of the battery life due to overdischarge is set in advance to the lower limit reference value SOCref2. When the lower limit reference value SOCref2 is different for each battery, it may be compared with a specific lower limit reference value.

  Here, as shown in FIG. 2 (a), if the estimated SOCm of one battery (in this case, the main battery 2) is below the lower limit reference value SOCref2, the process proceeds to step S3 and forced charging is started. The one battery is charged with the power generation output of the alternator 1 during normal running without waiting for regenerative charging.

  That is, if the main battery 2 is forcibly charged, the charging controller 6 sets the output voltage of the alternator 1 to 12V. Further, the charging path selector 7 is instructed to establish a charging path so that the output of the alternator 1 is supplied to the main battery 2.

  On the other hand, if the sub-battery 3 is forcedly charged, the output voltage of the alternator 1 is set to 48V by the charging control unit 6. Further, the charging path selector 7 is instructed to establish a charging path so that the output of the alternator 1 is supplied to the sub-battery 3.

  On the other hand, if it is determined in step S2 that there is no battery whose estimated SOC is lower than the lower limit reference value SOCref2, the process proceeds to step S4, and it is determined whether the forced charging started in step S3 is continuing. The If forced charging is continuing, this will be complete | finished and it will progress to step S5. In step S5, regenerative charge control is performed to charge each battery with regenerative energy during braking.

  FIG. 4 is a flowchart showing the regenerative charging control method. In step S101, it is determined whether or not regenerative braking has been started. In step S112, it is determined whether or not regenerative braking has ended. The start or end of regenerative braking can be determined based on, for example, whether fuel supply to the engine is shut off.

  When the start of regenerative braking is detected, the process proceeds to step S102, and the estimated SOCm and SOCs of each battery 2 and 3 are compared with a predetermined upper limit reference value SOCref1. In the present embodiment, the minimum SOC value that can promote the deterioration of the battery life due to overcharging is set to the upper limit reference value SOCref1. When the upper limit reference value SOCref1 is different for each battery, it may be compared with a specific upper limit reference value.

  Here, as shown in FIG. 2B, if both of the estimated SOCm and SOCs exceed the upper limit reference value SOCref1, further charging leads to deterioration of the battery life due to overcharging, so the process proceeds to step S103. . In step S103, the battery selection unit 6b sets the target battery for regenerative charging to “none”.

  In step S106, as will be described in detail later, the charging path selector 7 does not perform regenerative charging on any of the batteries and supplies power from the corresponding batteries 2 and 3 to the auxiliary machines 4 and 5, respectively. The charging path is switched.

  On the other hand, as shown in FIGS. 2C and 2D, if only one of the estimated SOCm and SOCs exceeds the upper limit reference value SOCref1, and the other is lower than the upper limit reference value SOCref1, the process proceeds to step S104. The battery indicating the other estimated SOC is selected as the current charging target battery by the battery selection unit 6b.

  In step S105, the output voltage of the alternator 1 is set to 12V or 48V by the variable voltage setting unit 6c depending on the selected battery. In step S106, as will be described in detail later, the charging path selector 7 switches the charging path so that only the selected battery is charged by the output of the alternator 1.

  Further, as shown in FIGS. 2 (e) and 2 (f), if it is determined that both of the estimated SOCm and SOCs are below the upper limit reference value SOCref1, the process proceeds to step S107, and the difference ΔSOC between the estimated SOCm and SOCs. (= | SOCm−SOCs |) is compared with the reference difference Δref.

  As a result, as shown in FIG. 2 (e), if the difference ΔSOC is larger than the reference difference Δref, it is determined that there is a significant difference in the SOC of each battery, and the process proceeds to step S108, where the estimated SOC is lower. The battery is selected as the current charging target battery by the battery selection unit 6b.

  In step S109, the output voltage of the alternator 1 is set to 12V or 48V by the variable voltage setting unit 6c depending on the selected battery. In step S106, the charging path selector 7 switches the charging path so that only the selected battery is charged by the output of the alternator 1.

  On the other hand, as shown in FIG. 2 (f), if the difference ΔSOC is smaller than the reference difference Δref, it is determined that there is no significant difference in the SOC of each battery, and the process proceeds to step S110. In step S110, as the battery having high charging efficiency, for example, the sub-battery 3 is fixed or has a lower charge remaining amount obtained from the charge / discharge history, and the terminal voltage ratio (Vs / 12, Vm / 48) is lower. A battery or a battery having a smaller internal impedance is selected as the target battery for the current regenerative charge by the battery selection unit 6b. Or you may make it select the battery with more discharge total amount as this charge object with reference to the latest charging / discharging log | history.

  In step S111, the output voltage of the alternator 1 is set to 12V or 48V by the variable voltage setting unit 6c depending on the selected battery. In step S106, the charging path selector 7 switches the charging path so that only the selected battery is charged by the output of the alternator 1.

  Thereafter, when the end of regenerative braking is detected in step S112, the process proceeds to step S113, and the charge target is set to “none”. In step S106, the charging path is switched by the charging path selector 7 so that no battery is charged and power is supplied from the corresponding batteries 2 and 3 to the auxiliary machines 4 and 5, respectively.

  FIG. 5 is a diagram illustrating a method in which the charging path selector 7 establishes a charging path based on the selection result of the charging target battery by the charging control unit 6.

  As shown in FIG. 2 (b), if both estimated SOCm and SOCs exceed the upper limit reference value SOCref1, and the battery to be charged is “None”, as shown in FIG. 5 (a). Both the switch SW1 that connects the output of the alternator 1 to the 12V system and the switch SW2 that connects the 48V system are turned off.

  Further, a switch SW3 for connecting the main battery 2 to the 12V system, a switch SW4 for connecting the 12V auxiliary machine to the 12V system, a switch SW5 for connecting the sub battery 3 to the 48V system, and a switch SW6 for connecting the 48V auxiliary machine to the 48V system. Both are turned on. As a result, power is supplied from the batteries 2 and 3 corresponding to the auxiliary machines 4 and 5, respectively.

  On the other hand, as shown in FIG. 2 (c), or when the sub-battery 3 is selected for regenerative charging in each case of FIGS. 2 (e) and 2 (f), it is shown in FIG. As described above, the switch SW1 is turned off, and the other switches SW2 to SW6 are all turned on. As a result, the regenerative energy of the alternator 1 is used for charging the sub-battery 3 and for consumption by the 48V auxiliary machine.

  Further, as shown in FIG. 2 (d) or when the main battery 2 is selected for regenerative charging in each case of FIGS. 2 (e) and 2 (f), as shown in FIG. 5 (c). In addition, the switch SW2 is turned off, and the other switches SW1, SW3 to SW6 are all turned on. As a result, the regenerative energy of the alternator 1 is used for charging the main battery 2 and consuming the 12V auxiliary machine.

  Thus, according to the present embodiment, the regenerative energy of the alternator can be efficiently charged to a plurality of batteries having different rated voltages without using an expensive and inefficient DC / DC converter.

  Further, according to the present embodiment, the regenerative energy can be efficiently charged to the battery, and the regenerative energy can be sufficiently consumed, so that a sufficient regenerative braking force can be obtained.

  Furthermore, according to this embodiment, since one battery which can charge regenerative energy more efficiently is charged preferentially, the regenerative energy can be used more effectively.

DESCRIPTION OF SYMBOLS 1 ... Variable voltage alternator, 2 ... Main battery, 2a ... Battery controller, 3 ... Sub battery, 3a ... Battery controller, 4 ... Low voltage auxiliary machine, 5 ... High voltage auxiliary machine, 6 ... Charge control part, 7 ... Charging path Selector, 8 ... Current sensor, 31 ... Drive shaft, 32 ... Differential gear, 33 ... Drive wheel, 34 ... Power distribution mechanism

Claims (12)

In the vehicle charging control device for controlling charging of the regenerative energy output from the variable voltage alternator to the battery,
Means for detecting the state of charge of a plurality of batteries having different rated voltages;
Means for selecting a battery to be charged based on the state of charge of each battery;
Means for setting the output voltage of the variable voltage alternator based on the selection result;
A hybrid vehicle charging control device comprising: a variable voltage alternator and means for establishing a charging path between the selected battery.   The charging control apparatus for a hybrid vehicle according to claim 1, wherein the means for detecting the state of charge detects the SOC of each battery.   The charging control apparatus for a hybrid vehicle according to claim 2, wherein the means for selecting the battery selects a battery having a lower SOC.   The charging control device for a hybrid vehicle according to claim 2, wherein the means for selecting the battery selects a battery having a lower SOC within a range of a predetermined upper limit value or less.   The charging control device for a hybrid vehicle according to claim 2, wherein the means for selecting the battery selects a battery whose SOC is lower than a predetermined lower limit value. The means for detecting the state of charge detects at least one of a remaining charge, a terminal voltage ratio and an internal impedance obtained from a charge / discharge history of each battery,
The charging control device for a hybrid vehicle according to claim 1, wherein the battery selecting means selects a battery having the lower at least one detection result. In a hybrid vehicle that charges the battery with regenerative energy during braking,
A variable voltage alternator with variable output voltage;
A plurality of batteries with different rated voltages;
Means for detecting the state of charge of each battery;
Means for selecting a battery to be charged based on the state of charge of each battery;
Means for setting the output voltage of the variable voltage alternator based on the selection result;
A hybrid vehicle comprising: a variable voltage alternator and means for establishing a charging path between the selected battery.   The hybrid vehicle according to claim 7, wherein the means for detecting the state of charge detects the SOC of each battery.   The hybrid vehicle according to claim 8, wherein the battery selecting unit selects a battery having a lower SOC.   9. The hybrid vehicle according to claim 8, wherein the means for selecting the battery selects a battery having a lower SOC within a range of a predetermined upper limit value or less.   9. The hybrid vehicle according to claim 8, wherein the means for selecting the battery selects a battery whose SOC is lower than a predetermined lower limit value. The means for detecting the state of charge detects at least one of a remaining charge, a terminal voltage ratio and an internal impedance obtained from a charge / discharge history of each battery,
The hybrid vehicle according to claim 7, wherein the battery selecting unit selects a battery having the lower detection result of the at least one battery.