JP2017070052A - Charging control device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress deterioration in charging/discharging efficiency and breakage of a secondary battery by suppressing extreme deterioration in a charging rate of the secondary battery regardless of power generation capacity of a power generator.SOLUTION: A charging control device for performing charging control of a secondary battery mounted on a hybrid electric automobile includes: a power generation control part for starting charging when a charging rate of the secondary battery becomes a predetermined charging start value or less, and for stopping charging when the charging rate of the secondary battery becomes a predetermined charging stop value or more; an average charging rate calculation part for calculating an average charging rate of the secondary battery within a unit time; and a reference value adjustment part for increasing/decreasing a charging start value and a charging stop value on the basis of a comparison result between the average charging rate and the predetermined target charging rate.SELECTED DRAWING: Figure 11

Description

  The present invention relates to a charge control device that performs charge control of a secondary battery mounted on a vehicle.

  A hybrid electric vehicle includes a secondary battery that supplies electric power to a driving motor that generates driving force of the vehicle. Such a secondary battery can be charged with electric power generated by a generator mounted on a vehicle. For example, there is a vehicle in which a secondary battery can be charged with electric power generated using engine power (hereinafter also referred to as “power generation”). There is also a vehicle in which the secondary battery can be charged with electric power generated by using the kinetic energy of the vehicle during braking of the vehicle (hereinafter also referred to as “decelerated regenerative power generation”).

  The charge rate of the in-vehicle secondary battery is maintained with a predetermined amplitude. For example, charging starts when the charging rate of the secondary battery becomes equal to or lower than a preset charging start value, and then charging when the charging rate of the secondary battery becomes equal to or higher than a preset charging end value. Ends. When the charging rate of the secondary battery is too low, the internal resistance increases, the charge / discharge efficiency is deteriorated, and the secondary battery may be damaged in some cases. Therefore, when performing charging control of the secondary battery, control is performed so that the charging rate of the secondary battery is not significantly reduced.

  For example, in Patent Document 1, the vehicle controller records the power consumption of an electric motor or the like until the charging rate of the battery reaches the power generation start point, and the power generation start point based on the average power consumption calculated based on the recorded power consumption. A control device for calculating the value is disclosed. According to such a control device, the power generation start point is set high when the average power consumption is large, and the battery does not discharge deeply even in a situation where the power consumption of the motor is large, and the life of the battery is prolonged.

  Patent Document 2 also compares the amount of change in the battery charge rate per unit time with a reference value, and when the amount of change in the charge rate is large, the charge rate at which the engine and the motor shift to the travel mode. A control device is disclosed that increases the threshold correction coefficient and decreases the charge ratio threshold correction coefficient when the change rate of the charge rate is small. In such a control device, the power generation start time is advanced when the change amount of the charging rate is large, and the power generation start time is delayed when the change amount of the charge rate is small.

JP-A-6-197406 JP 2014-80163 A

  Here, the power generation capability (output) of the generator mounted on the vehicle may vary depending on the vehicle type, grade, and the like. In addition, the power generation capacity may change due to aging of the generator. When the output of the generator is different, the time from the start of power generation to the end of power generation of a predetermined amount of power is different. Specifically, when a low-output generator is controlled with the same algorithm as a high-output generator, the low-output generator has a small amount of generated power, and the charge rate of the secondary battery may be reduced.

  In the control devices disclosed in Patent Documents 1 and 2, the power generation start time is appropriately changed in accordance with the driving environment of the vehicle, the driver's handling habits, and the like, but it is assumed that the output of the generator is different. No. Therefore, when the control devices of Patent Documents 1 and 2 are applied to a hybrid electric vehicle equipped with a low-output generator, there is a possibility that the charge / discharge efficiency is lowered and the secondary battery is damaged.

  Also, when producing a vehicle, preparing a charge control device by adapting the algorithm for each generator output, which may vary depending on the vehicle type, grade, etc., leads to an increase in man-hours and, in turn, an increase in production cost. Can also be connected.

  This invention is made | formed in view of the said subject, The place made into the objective of this invention suppresses the remarkable fall of the charging rate of a secondary battery irrespective of the electric power generation capability of a generator, and charging / discharging efficiency. It is an object of the present invention to provide a new and improved charge control device that can suppress a decrease in battery life and damage to a secondary battery.

  In order to solve the above problems, according to one aspect of the present invention, in a charge control device that performs charge control of a secondary battery mounted on a hybrid electric vehicle, the charge rate of the secondary battery is equal to or less than a predetermined charge start value. The power generation control unit that starts charging when the charge reaches the value and stops charging when the charge rate of the secondary battery exceeds a predetermined charge stop value, and calculates the average charge rate of the secondary battery within a unit time And a reference value adjusting unit that increases or decreases the charge start value and the charge stop value based on a comparison result between the average charge rate and a predetermined target charge rate. The

  The reference value adjustment unit increases the charge start value and the charge stop value when the average charge rate is less than the predetermined target charge rate, and the charge start value and the charge stop value when the average charge rate exceeds the predetermined target charge rate. May be reduced.

  The reference value adjustment unit may set an increase range and a decrease range of the charge start value and the charge stop value based on the difference between the average charge rate and the target charge rate.

  The target charging rate may be a currently set charging start value.

  The reference value adjustment unit may change the charge start value and the charge stop value between a preset upper limit value and lower limit value.

  According to the charge control device of the present invention, it is possible to suppress a significant decrease in the charging rate of the secondary battery regardless of the power generation capability of the generator, and to suppress a decrease in charge / discharge efficiency and a damage to the secondary battery. it can.

It is a schematic diagram which shows the whole structure of the system provided with the charge control apparatus (GCU) concerning embodiment of this invention. It is a figure for demonstrating the relationship between the output of a secondary battery, and charging efficiency. It is a figure for demonstrating the relationship between the output of a secondary battery, and charging efficiency. It is a figure for demonstrating the relationship between the output of a secondary battery, and charging efficiency. It is a block diagram which shows the structural example of the charge control apparatus concerning the embodiment. It is a figure for demonstrating the average value of the charging rate per unit time. It is a figure which shows an example of the map for changing a threshold value. It is a flowchart which shows the process of the charge control apparatus concerning the embodiment. It is a flowchart which shows the process which calculates the average value of the charging rate per unit time. It is a time chart when not performing the process concerning the embodiment. It is a time chart at the time of performing the process concerning the embodiment.

  Exemplary embodiments of the present invention will be described below in detail with reference to the accompanying drawings. In addition, in this specification and drawing, about the component which has the substantially same function structure, duplication description is abbreviate | omitted by attaching | subjecting the same code | symbol.

<< 1. System outline >>
First, an example of a schematic configuration of a hybrid vehicle according to an embodiment of the present invention will be described. FIG. 1 is a schematic diagram showing a hybrid control system 10 according to the present embodiment. The hybrid control system 10 includes a drive system and an electronic control system.

<1-1. Structure of drive system>
The drive system of the hybrid control system 10 according to the present embodiment includes a secondary battery 80, an inverter 20, a motor / generator unit 30, an engine ENG, a planetary gear 60, and a differential gear 50.

(engine)
The engine ENG is an engine that generates driving force of a vehicle, typified by a gasoline engine or a diesel engine. The driving force generated by the engine ENG is transmitted to the drive wheels 40 via the planetary gear 60, the differential gear 50, the drive shaft 70, and the like. The driving force generated by the engine ENG is also used as power for power generation by the generator 31.

(Planetary gear)
Planetary gear 60 distributes the driving force generated by engine ENG to drive wheels 40 and generator 31. For example, the ring gear of the planetary gear 60 is connected to the drive shaft 70 connected to the drive wheels 40 via the differential gear 50, and the rotor of the generator 31 is connected to the sun gear.

(Motor / Generator unit)
The motor / generator unit 30 includes a generator 31 that generates power (power generation) using the driving force of the engine ENG and a motor / generator 32 that applies driving force to the drive shaft 70 via the differential gear 50. It is a unit that became. The generator 31 and the motor / generator 32 are electrically connected to the secondary battery 80 via the inverter 20.

  The generator 31 performs motive power generation using the driving force of the engine ENG. The generated power is charged in the secondary battery 80. The generator 31 is configured by, for example, a three-phase AC motor. When power is generated by the generator 31, the motor is rotated by the driving force of the engine ENG, thereby causing a change in the magnetic field in the motor, and a three-phase alternating current is output via the three-phase winding. The frequency of the generated alternating current is variable depending on the rotational speed of the motor. The generator 31 may be configured to function as a starter with the electric power from the secondary battery 80 when the engine ENG is started.

  The motor / generator 32 generates a driving force to be applied to the drive shaft 70 by an electromagnetic force generated by a current supplied via the inverter 20 and a magnetic force of a magnet provided in the motor / generator 32. The motor / generator 32 also has a regenerative function for generating power using the kinetic energy of the vehicle during deceleration. The motor / generator 32 is constituted by, for example, a three-phase AC motor. When a driving force is generated in the motor / generator 32, a rotating magnetic field is generated in the motor by supplying a three-phase alternating current to the three-phase winding of the stator coil, and the permanent magnet provided in the rotor is attracted to the rotating magnetic field. As a result, torque is generated. The magnitude of the torque generated at this time is proportional to the magnitude of the alternating current supplied to the motor. The frequency of the alternating current supplied to the motor is set according to the output torque and rotation speed of the motor.

(Secondary battery)
The secondary battery 80 is a chargeable / dischargeable storage battery. In the hybrid control system 10 of the present embodiment, a high voltage battery having a battery voltage of 200 V is used as the secondary battery 80. However, the rated voltage of the secondary battery 80 is not particularly limited. The secondary battery 80 supplies power to the motor / generator 32 that outputs the driving force of the vehicle. The secondary battery 80 is charged with the power generated by the generator 31 and the motor / generator 32. The secondary battery 80 includes a temperature sensor, a voltage sensor, a current sensor, and the like (not shown). The sensor values of these sensors are transmitted to the battery management system (BMS) 200.

(Inverter)
The inverter 20 controls the current supplied to the motor / generator unit 30 and controls the charging of the power generated by the motor / generator 32 to the secondary battery. When the inverter 20 outputs a driving force to the motor / generator 32, the inverter 20 converts the direct current supplied from the secondary battery 80 into an alternating current and supplies the alternating current to the three-phase winding of the motor / generator 32. The magnitude of the alternating current supplied to the motor / generator 32 and the frequency of the alternating current that can be adjusted by the inverter 20 are controlled by a generator control unit (ECU) 500. Since the motor / generator 32 generates a motor torque by flowing a current through the three-phase winding, it is possible to flow a larger current by increasing the applied voltage.

  Further, when the generator 20 and the motor / generator 32 generate electric power, the inverter 20 converts the alternating current generated by the motor into a direct current and charges the secondary battery 80. The voltage of the charging power at this time is controlled to be equal to or higher than the charging output voltage that changes according to the charging rate SOC of the secondary battery 80, the battery temperature Tb, and the degree of deterioration of the secondary battery.

<1-2. Configuration of electronic control system>
The electronic control system of the hybrid control system 10 according to the present embodiment includes a charge control device (hereinafter also referred to as “GCU”) 100, a battery management system (hereinafter also referred to as “BMS”) 200, and an electric drive system. A control device (hereinafter also referred to as “EV-CU”) 300, a vehicle control device (hereinafter also referred to as “VCU”) 400, and a generator control device (hereinafter also referred to as “ECU”) 500 are provided. ing. In the hybrid control system 10 according to the present embodiment, the electronic control system includes a plurality of independent control devices, but all or part of these control devices are integrated into one control device. It may be configured.

(Generator control unit: ECU)
ECU 500 includes a microcomputer, a storage element, and the like, and controls engine ENG and inverter 20. In the present embodiment, the ECU 500 functions as a generator control device, and performs motive power generation using the driving force of the engine ENG by the generator 31 and regenerative power generation by the motor / generator 32. For example, the ECU 500 causes the motor / generator 32 to generate electric power by using the kinetic energy of the vehicle while the driving force output from the motor / generator 32 to the driving wheel 40 is zero during traveling of the vehicle, Is supplied to the secondary battery 80. Further, ECU 500 causes generator 31 to generate power using the driving force of engine ENG in accordance with the power generation start command and power generation stop command transmitted from GCU 100, and supplies predetermined charging power to secondary battery 80.

(Battery management system: BMS)
The BMS 200 includes a microcomputer, a storage element, and the like, and functions as a device that manages the state of the secondary battery 80. For example, the BMS 200 receives the sensor values of the voltage sensor and the current sensor provided in the secondary battery 80 and calculates the charge rate SOC of the secondary battery 80. Further, the BMS 200 receives the sensor value of the temperature sensor provided in the secondary battery 80, and acquires information on the battery temperature Tb. The BMS 200 calculates the required power generation amount based on, for example, the charging rate SOC of the secondary battery 80 and the battery temperature Tb. The required power generation amount is an amount of power necessary for charging the secondary battery 80. The BMS 200 transmits the obtained information to the EV-CU 300.

(Vehicle control unit: VCU)
The VCU 400 includes a microcomputer, a storage element, and the like, and determines the state of the vehicle and controls each device provided in the vehicle in order to maintain the vehicle in an optimal state. For example, the VCU 400 acquires information related to the traveling load of the vehicle and determines whether regenerative power generation is on or off. The VCU 400 considers the influence on other devices rather than individually controlling each device that affects each other, such as the generator 31, the motor / generator 32, the inverter 20, the secondary battery 80, and the air conditioner (air conditioner). Then, overall control is performed.

(Electric drive system controller: EV-CU)
The EV-CU 300 includes a microcomputer, a storage element, and the like, acquires information from the BMS 200 and the VCU 400, and transmits necessary information to the GCU 100. For example, the EV-CU 300 acquires information on the current charging rate SOC of the secondary battery 80 and information on the required power generation amount from the BMS 200, and acquires information on the state of the vehicle from the VCU 400. The EV-CU 300 transmits information on the charging rate SOC, the required power generation amount, and the vehicle state to the GCU 100.

(Charge control unit: GCU)
The GCU 100 includes a microcomputer, a storage element, and the like, and executes charging control for the secondary battery 80 based on information transmitted from the EV-CU 300. Such a GCU 100 corresponds to a charge control device according to the present invention. Specifically, the GCU 100 performs a predetermined calculation based on the information transmitted from the EV-CU 300, and gives the ECU 500 an instruction to start and stop power generation, an instruction to turn on and off regenerative power generation, and information on the required power generation amount. Send. The ECU 500 controls the inverter 20 based on the transmitted information so that the charging power (kW) becomes the required power generation amount (kW). In addition, ECU 500 executes regenerative power generation by motor / generator 32 in accordance with the on / off of regenerative power generation. Further, ECU 500 executes motive power generation using the driving force of engine ENG by generator 31 from the reception of the power generation start instruction to the reception of the power generation stop instruction.

  Hereinafter, the start and stop of motive power generation will be described. The GCU 100 transmits a charge start instruction to the ECU 500 when the charge rate SOC of the secondary battery 80 becomes equal to or lower than the charge start value SOC_thre1, and when the charge rate SOC of the secondary battery 80 becomes equal to or higher than the charge stop value SOC_thre2. In addition, a charge stop instruction is transmitted to the ECU 500. At this time, the GCU 100 according to the present embodiment calculates the average charge rate SOC_ave of the secondary battery 80 within a unit time, and increases or decreases the charge start value SOC_thre1 and the charge stop value SOC_thre2 based on the average charge rate SOC_ave. Thereby, regardless of the power generation capability of the generator 31, it is possible to suppress a significant decrease in the charging rate of the secondary battery 80.

  Here, with reference to FIGS. 2 to 4, the difference in charging efficiency due to the difference in power generation capability of the generator 31 will be described. For example, as shown in FIG. 2, it is assumed that there are three generators A, B, and C having different power generation capacities (outputs). As shown in FIG. 3, when the secondary battery 80 is charged from a certain charging rate α (%) to a charging rate β (%), the required time T3 of the generator A having the lowest power generation capacity is determined by the other generators B and C. Is longer than the required time T2, T1. From a different viewpoint, as shown in FIG. 4, when the generator C having the highest power generation capacity performs charging at the time T <b> 1 required for charging from the charging rate α (%) to the charging rate β (%). The amount of charge of generators A and B with low power generation capacity is reduced.

  Then, even if charging of the secondary battery 80 is started at the same timing, a difference occurs in the charging rate SOC of the secondary battery 80 after a certain time has elapsed. Therefore, when the power generation capacity of the generator 31 is low, if the traveling load of the vehicle is large and the electric power supplied to the motor / generator 32 is large, the charging rate SOC of the secondary battery 80 may be significantly reduced. On the other hand, the GCU 100 according to the present embodiment increases or decreases the charging start value SOC_thre1 and the charging stop value SOC_thre2 based on the average charging rate SOC_ave per unit time, regardless of the power generation capacity of the generator 31. It is suppressed that the charging rate SOC of the secondary battery 80 is significantly reduced.

  FIG. 5 shows the configuration of the GCU 100 according to the present embodiment as functional blocks. The GCU 100 includes a load detection unit 110, a power generation control unit 120, an average charging rate calculation unit 130, and a reference value adjustment unit 140. Each of these units is a function realized by executing a program by a microcomputer.

  The load detection unit 110 detects the travel load of the vehicle based on the vehicle state transmitted from the EV-CU 300. For example, a high load is detected while the vehicle is traveling uphill, a low load is detected while the vehicle is traveling on a flat road, and a negative load is detected while the vehicle is traveling downhill.

  The power generation control unit 120 causes the motor / generator 32 to perform regenerative power generation while the traveling load of the vehicle detected by the load detection unit 110 is negative. During the period when the vehicle load is negative, no current is supplied to the motor / generator 32, and regenerative power generation is possible. Therefore, an execution instruction for regenerative power generation is transmitted to the ECU 500.

  Further, the power generation control unit 120 causes the generator 31 to execute motive power generation when the charging rate SOC of the secondary battery 80 becomes equal to or lower than the charging start value SOC_thre1. The motive power generation uses the driving force of the engine ENG, and the ECU 500 operates the engine ENG so that the load required for motive power generation is output together with the load used as the driving force of the vehicle. Perform power generation. Then, the power generation control unit 120 stops the power generation by the generator 31 when the charge rate SOC of the secondary battery 80 becomes equal to or higher than the charge stop value SOC_thre2 while executing the power generation.

  The charge start value SOC_thre1 and the charge stop value SOC_thre2 are determined as values obtained by adding or subtracting the adjustment value calculated by the reference value adjustment unit 140. The power generation control unit 120 reads the current charge start value SOC_thre1 and the charge stop value SOC_thre2 and compares them with the current value of the charge rate SOC. The power generation control unit 120 transmits an instruction to start or stop motive power generation to the ECU 500 based on the comparison result between the charge rate SOC and the charge start value SOC_thre1 or the charge stop value SOC_thre2.

  Average charging rate calculation unit 130 calculates average charging rate SOC_ave of secondary battery 80 per unit time. FIG. 6 is an explanatory diagram showing an example of how to obtain the average charging rate SOC_ave. The average charging rate calculation unit 130 calculates the average value of the charging rate SOC detected for each unit time W1 to W4 set in advance. The charging rate SOC of the secondary battery 80 may use all the values acquired for each processing cycle of the BMS 200 and the EV-CU 300, or use a value that can be detected at a predetermined time different from the processing cycle. Also good.

  The unit time for calculating the average charging rate SOC_ave can be set, for example, with a time to the extent that the charging rate SOC of the secondary battery 80 is reduced by 0.5%. If the unit time is too short, a difference in the average charging rate SOC_ave is unlikely to occur, and the charging start value SOC_thre1 and the charging stop value SOC_thre2 may not be appropriately increased or decreased. On the other hand, if the unit time is too long, the timing for increasing or decreasing the charge start value SOC_thre1 and the charge stop value SOC_thre2 may be delayed, and it may be difficult to prevent a significant decrease in the charge rate SOC. Such a unit time depends on the charge capacity of the secondary battery 80, but can be, for example, about 30 to 40 seconds.

  Based on the average charging rate SOC_ave, the reference value adjustment unit 140 obtains adjustment amounts of the charge start value SOC_thre1 and the charge stop value SOC_thre2, and reflects the adjustment amounts in the power generation control in the power generation control unit 120. Specifically, reference value adjustment unit 140 sets the adjustment amount of charge start value SOC_thre1 and charge stop value SOC_thre2 according to the difference obtained by subtracting average charge rate SOC_ave from target charge rate SOC_tgt. Reference value adjustment unit 140 adds the set adjustment amount to current charge start value SOC_thre1 and charge stop value SOC_thre2, and updates the values of charge start value SOC_thre1 and charge stop value SOC_thre2. The target charging rate SOC_tgt may be the current charging start value SOC_thre1. The initial value of the target charging rate SOC_tgt can be set to 10%, for example. In order to easily adjust the charge start value SOC_thre1 and the charge stop value SOC_thre2 to the increase side, the initial value of the target charge rate SOC_tgt may be set to a relatively large value.

  FIG. 7 shows an example of a map in which the adjustment amount is set according to the difference between the target charging rate SOC_tgt and the average charging rate SOC_ave. As shown in FIG. 7, as the difference obtained by subtracting the average charge rate SOC_ave from the target charge rate SOC_tgt increases toward the plus side, that is, as the average charge rate SOC_ave decreases, the charge start value SOC_thre1 and the charge stop value SOC_thre2 increase. Adjusted to Therefore, when the power generation capacity of the generator 31 is small and the average charging rate SOC_ave of the secondary battery 80 is small, the power generation start time is advanced, and a significant decrease in the charging rate SOC of the secondary battery 80 can be prevented.

  However, when increasing or decreasing the charge start value SOC_thre1 and the charge stop value SOC_thre2, an upper limit value and a lower limit value may be set, respectively. By setting the upper limit value and the lower limit value, it is possible to prevent the charge start value SOC_thre1 from being extremely small or the charge stop value SOC_thre2 from being extremely large.

<< 2. Power generation control method >>
Next, processing executed by the GCU (charge control device) 100 according to the present embodiment will be specifically described. FIG. 9 is a flowchart showing a process of adjusting the charge start value SOC_thre1 and the charge stop value SOC_thre2 executed by the GCU 100. For example, the processing shown in the flowchart is always executed while the hybrid control system 10 is activated.

  First, in step S100, the GCU 100 acquires an average charging rate SOC_ave of the secondary battery 80 per unit time. For example, the average charging rate calculation unit 130 of the GCU 100 reads the charging rate SOC of the secondary battery 80 calculated by the BMS 200 and transmitted via the EV-CU 300 every predetermined cycle, and sets a preset unit time W. For each, an average charging rate SOC_ave is calculated.

  FIG. 7 is a flowchart specifically illustrating an example of an acquisition process of the average charging rate SOC_ave. In step S110, the average charging rate calculation unit 130 reads the current charging rate SOC (n) of the secondary battery 80. Next, in step S120, the average charging rate calculation unit 130 adds the charging rate SOC (n) read in step S110 to the previous integrated value SOC_itg (n-1) to obtain a new integrated value SOC_itg (n). In step S130, the sampling count N is added (+1).

  Next, in step S140, the average charging rate calculation unit 130 determines whether or not a preset unit time W has elapsed. If the unit time W has not elapsed (S140: No), the process returns to step S110, and steps S110 to S140 are repeated until the unit time W has elapsed. On the other hand, when the unit time W has elapsed (S140: Yes), the average charging rate calculation unit 130 divides the integrated value SOC_itg (n) of the charging rate SOC by the number of samplings N in step S150, thereby averaging charging. The rate SOC_ave is calculated.

  After calculating the average charging rate SOC_ave, the average charging rate calculating unit 130 resets the number of times of sampling N (N = 0) in step S160, returns to the start (S110), and performs the average charging of the next unit time W. Calculation of the rate SOC_ave is started.

  Returning to FIG. 9, after acquiring the average charge rate SOC_ave in step S100, the GCU 100 determines in step S200 the charge start value SOC_thre1 and the charge stop value SOC_thre2 based on the value obtained by subtracting the average charge rate SOC_ave from the target charge rate SOC_tgt. Find the adjustment value. For example, the reference value adjustment unit 140 of the GCU 100 obtains an adjustment value corresponding to a value obtained by subtracting the average charging rate SOC_ave from the target charging rate SOC_tgt with reference to a map as shown in FIG. The target charging rate SOC_tgt may be the current charging start value SOC_thre1.

  Next, in step S300, the GCU 100 adds the obtained adjustment value to the current charge start value SOC_thre1 and charge stop value SOC_thre2, and updates the values of the charge start value SOC_thre1 and the charge stop value SOC_thre2. . Thereby, when the power generation capacity of the generator 31 is low, the charging start value SOC_thre1 is increased, and the time when the charging rate SOC of the secondary battery 80 becomes equal to or lower than the charging start value SOC_thre1 is advanced. As a result, the time when the power generation control unit 120 of the GCU 100 transmits an instruction to start power generation by the generator 31 to the ECU 500 is advanced.

  Since not only the charge start value SOC_thre1 but also the charge stop value SOC_thre2 is adjusted, the time when the charge rate SOC of the secondary battery 80 becomes equal to or higher than the charge stop value SOC_thre2 after the power generation by the generator 31 is started. Is delayed. As a result, the time when the power generation control unit 120 of the GCU 100 transmits an instruction to stop the power generation by the generator 31 to the ECU 500 is delayed. Therefore, as the power generation capacity of the generator 31 is lower, the charging rate SOC of the secondary battery 80 when stopping the power generation is larger. As described above, even when the power generation capacity of the generator 31 is low, it is possible to prevent the charging rate SOC of the secondary battery 80 from being significantly reduced.

<< 3. Time chart >>
Next, the difference in the charging rate SOC of the secondary battery 80 between when the GCU 100 according to this embodiment is not executed and when it is executed will be described based on a time chart. FIGS. 10 and 11 respectively show the gradient of the road surface on which the vehicle travels, the travel load of the vehicle, the power generation state, and the change in the SOC of the secondary battery 80 over time. FIG. 10 shows a case where the process of the GCU 100 according to this embodiment is not executed, and FIG. 11 shows a case where the process of the GCU 100 according to this embodiment is executed.

<3-1. Reference example not implementing the present invention>
In FIG. 10, the power generation state and the charging rate SOC of the low output generator with low power generation capability are indicated by a one-dot chain line, and the power generation state and the charge rate SOC of a high output generator with high power generation capability are indicated by a broken line. When the generator 31 has a high output (dashed line), when the vehicle starts traveling uphill from time t11, the traveling load of the vehicle increases and the driving force output from the motor / generator 32 increases. The charging rate SOC of the battery 80 decreases.

  When the charging rate SOC of the secondary battery 80 becomes equal to or lower than the charging start value SOC_thre1 at time t12, motive power generation by the generator 31 is started. When the generator 31 has a high output, the reduction in the charging rate SOC of the secondary battery 80 stops. However, until the time t13, the traveling load is large and the power supplied to the motor / generator 32 is large, so the charging rate SOC is recovered. can not see. After time t13 when the uphill is finished and the road surface is flat, the traveling load is reduced, so the charging rate SOC of the secondary battery 80 is increased. At time t14, the charging rate becomes SOC_thre2 or more. Power generation stops.

  After time t14 when the power generation by the generator 31 is stopped, the charging rate SOC of the secondary battery 80 gradually decreases according to the traveling load. Next, when the vehicle approaches a downhill at time t15, the traveling load becomes negative and regenerative power generation is started, so the charging rate SOC of the secondary battery 80 gradually increases. Next, after time t16 when the downhill is finished and the road surface is flat, the traveling load becomes positive although it is small, so the charging rate SOC of the secondary battery 80 gradually decreases. Next, when the vehicle approaches an uphill again at time t17, the traveling load increases, so the rate of decrease in the charging rate SOC of the secondary battery 80 also increases, and at time t18, the charging rate SOC becomes the charging start value. It becomes SOC_thre1 or less, and motive power generation by the generator 31 is started.

  Thus, when the generator 31 has a high output, the secondary battery 80 is repeatedly charged and discharged without the charge rate SOC of the secondary battery 80 being significantly lower than the charge start value SOC_thre1.

  On the other hand, when the generator 31 has a low output (broken line), when the vehicle starts to travel uphill from time t1, the charge rate SOC of the secondary battery 80 decreases as in the case where the generator 31 has a high output. When the charging rate SOC of the secondary battery 80 becomes equal to or lower than the charging start value SOC_thre1 at time t2, motive power generation by the generator 31 is started. When the generator 31 has a low output, the secondary battery 80 is charged, but when the power supplied to the motor / generator 32 is large, the charging rate SOC of the secondary battery 80 continues to decrease.

  Then, at time t3, when the uphill is finished and the road surface is flat, the traveling load is reduced, so the charging rate SOC of the secondary battery 80 starts to increase. The charging rate SOC at time t3 at which the charging rate SOC of the secondary battery 80 starts to rise is significantly lower than when the generator 31 has a high output. Next, when the vehicle approaches a downhill at time t4, regenerative power generation is started, so the rate of increase in the charging rate SOC of the secondary battery 80 increases. Next, when the charging rate SOC of the secondary battery 80 becomes equal to or higher than the charging stop value SOC_thre2 at time t5, the power generation by the generator 31 is stopped and only regenerative power generation is performed, so the rate of increase of the charging rate SOC is reduced.

  Next, after time t6 when the downhill is finished and the road surface is flat, the traveling load becomes positive although it is small, so the charging rate SOC of the secondary battery 80 gradually decreases. Next, when the vehicle approaches an uphill again at time t7, the traveling load increases, so the rate of decrease in the charging rate SOC of the secondary battery 80 also increases, and at time t8, the charging rate SOC becomes the charging start value. It becomes SOC_thre1 or less, and motive power generation by the generator 31 is started. However, when the traveling load of the vehicle is large, the power supplied to the motor / generator 32 is large, and the charging rate SOC of the secondary battery 80 continues to decrease.

  Thus, when the generator 31 has a low output, the charging rate SOC of the secondary battery 80 may greatly fall below the charging start value SOC_thre1.

<3-2. Example of carrying out the present invention>
In FIG. 11, the power generation state and the charging rate SOC when the present invention is implemented (Example) are shown by solid lines for a low output generator with low power generation capacity, and the present invention is not implemented (Comparative Example). The power generation state and the charging rate SOC are indicated by broken lines. That is, the power generation state and the charging rate SOC indicated by the broken line in FIG. 11 are the same as those of the low output generator shown in FIG. In the example shown in FIG. 11, the average value SOC_ave of the charging rate SOC of the secondary battery 80 is calculated every unit time W1, W2, and W3. A point (●) described on the graph of the change in the charging rate SOC indicated by the solid line is a detection point of the charging rate SOC. In the example shown in FIG. 11, four charging rate SOCs are detected for each unit time W1, and the average charging rate SOC_ave is obtained.

  From time t21 to t23, the power generation state and the charge rate SOC change as in the comparative example from time t1 to t3. At time t23, after the uphill finishes and starts running on a flat road surface, at time t24, the average charging rate SOC_ave of the unit time W1 is obtained. In this example, since the average charging rate SOC_ave of the unit time W1 is lower than the current charging start value SOC_thre1 used as the target charging rate SOC_tgt, the charging start value SOC_thre1 and the charge stop value SOC_thre2 are increased.

  Next, when the vehicle approaches a downhill at time t25, regenerative power generation is started and the rate of increase in the charge rate SOC of the secondary battery 80 increases. Thereafter, in the comparative example, at time t5, the charging rate SOC of the secondary battery 80 becomes equal to or higher than the charging stop value SOC_thre2, and the power generation is stopped. However, in the example, the charging stop value SOC_thre2 is increased. Power generation will continue.

  Next, at time t26 when the charging rate SOC of the secondary battery 80 becomes equal to or greater than the increased charge stop value SOC_thre2, the power generation is stopped. The timing at which the power generation is stopped is delayed as compared with the comparative example, and the charging rate SOC of the secondary battery 80 is restored to a relatively large value. Thereafter, the regenerative power generation continues until time t27 when the downhill ends, and the charging rate SOC of the secondary battery 80 gradually increases. Next, at the time t27, when the downhill is finished and the vehicle starts to travel on a flat road surface, the regenerative power generation is also stopped, and the charging rate SOC of the secondary battery 80 gradually decreases.

  Thereafter, at time t28, the average charging rate SOC_ave of the unit time W2 is obtained. In this example, since the average charging rate SOC_ave of the unit time W2 is equal to the charging start value SOC_thre1 used as the target charging rate SOC_tgt, the charging start value SOC_thre1 and the charge stop value SOC_thre2 are maintained as they are. The Next, when the vehicle approaches an uphill again at time t29, the rate of decrease in the charging rate SOC of the secondary battery 80 increases. Next, at time t30, the charging rate SOC of the secondary battery 80 becomes equal to or less than the increased charging start value SOC_thre, and motive power generation by the generator 31 is started. The charging rate SOC at the start of motive power generation is a value larger than that of the comparative example, and thereafter, the minimum value of the charging rate SOC is maintained larger than that of the comparative example.

  Thus, when the present invention is implemented, the charge rate SOC of the secondary battery 80 can be kept high even when the low-output generator 31 is used. Although not shown, when the high output generator 31 is used, the case where the average charge rate SOC_ave per unit time is larger than the target charge rate SOC_tgt and the case where they are equal are repeated. As a result, the charging rate SOC of the secondary battery 80 is maintained within a predetermined range without significantly decreasing.

  As described above, according to the charge control device (GCU) 100 according to the present embodiment, the charge start value SOC_thre1 and the charge based on the comparison result between the average charge rate SOC_ave per unit time W and the target charge rate SOC_tgt. The stop value SOC_thre2 is increased or decreased. Specifically, when the average charging rate SOC_ave is smaller than the target charging rate SOC_tgt, the charging start value SOC_thre1 and the charging stop value SOC_thre2 are increased, and when the average charging rate SOC_ave is larger than the target charging rate SOC_tgt, The charge start value SOC_thre1 and the charge stop value SOC_thre2 are decreased.

  Thereby, it is possible to prevent the charging rate SOC of the secondary battery 80 from significantly decreasing regardless of the power generation capacity of the generator 31. Therefore, it is possible to prevent the charge / discharge efficiency of the secondary battery 80 from being lowered or the secondary battery 80 from being damaged regardless of the type of the generator 31 and the degree of aging. Further, according to the charge control device 100 according to the present embodiment, the charging rate SOC of the secondary battery 80 can be controlled within a predetermined range regardless of the power generation capability of the generator 31, and the secondary battery 80 is protected. However, fuel efficiency can be suppressed and energy efficiency can be improved.

  The preferred embodiments of the present invention have been described in detail above with reference to the accompanying drawings, but the present invention is not limited to such examples. It is obvious that a person having ordinary knowledge in the technical field to which the present invention pertains can make various modifications or application examples within the scope of the technical idea described in the claims. Of course, it is understood that these also belong to the technical scope of the present invention.

  For example, in the above embodiment, when the preset unit time W elapses, the value SOC_itg (n) accumulated so far is divided by the number of times of sampling N to calculate the average charging rate SOC_ave. The present invention is not limited to such an example. For example, instead of determining whether or not the unit time W has elapsed, it may be determined whether or not the number of sampling times N has reached a specified number, and the integrated value so far may be divided by the specified number of samplings.

  The hybrid control system 10 according to the present embodiment is applied to a serial-parallel hybrid system, but the hybrid system may be applied to a serial or parallel hybrid system.

DESCRIPTION OF SYMBOLS 10 Hybrid control system 100 Charge control apparatus 110 Load detection part 120 Electric power generation control part 130 Average charging rate calculation part 140 Reference value adjustment part

Claims (5)

In a charging control device that performs charging control of a secondary battery mounted on a hybrid electric vehicle,
A power generation control unit that starts charging when the charging rate of the secondary battery becomes equal to or lower than a predetermined charging start value and stops charging when the charging rate of the secondary battery becomes equal to or higher than a predetermined charging stop value. When,
An average charge rate calculating unit for calculating an average charge rate of the secondary battery within a unit time;
Based on a comparison result between the average charge rate and a predetermined target charge rate, a reference value adjustment unit that increases or decreases the charge start value and the charge stop value;
A charge control device.   The reference value adjustment unit increases the charge start value and the charge stop value when the average charge rate is less than a predetermined target charge rate, and when the average charge rate exceeds the predetermined target charge rate, The charge control device according to claim 1, wherein a charge start value and the charge stop value are decreased.   3. The reference value adjusting unit according to claim 1, wherein the reference value adjustment unit sets an increase width and a decrease width of the charge start value and the charge stop value based on a difference between the average charge rate and the target charge rate. Charge control device.   The charge control device according to any one of claims 1 to 3, wherein the target charging rate is the currently set charging start value. The charge control device according to any one of claims 1 to 4, wherein the reference value adjustment unit changes the charge start value and the charge stop value between a preset upper limit value and a lower limit value.

Images