JP4992728B2 - Power supply device and discharge control method thereof - Google Patents

Description

  The present invention relates to a power supply device, and more particularly to a power supply device mounted on a hybrid vehicle using an internal combustion engine and an electric motor as a driving force source, and a discharge control method for the power supply device.

  Recently, as an environment-friendly vehicle, a hybrid vehicle incorporating a motor (motor) in a drive device has attracted a great deal of attention and has been partially put into practical use. This hybrid vehicle is equipped with a power source consisting of a secondary battery, an electric double layer capacitor, etc., to supply electric power to the motor, which is reduced in drive, or to convert kinetic energy into electric energy and store it during regenerative braking. ing. The discharge from the power source or the charging to the power source is performed in consideration of, for example, the remaining capacity of the power source (SOC: State of Charge 1). By maintaining the SOC within an appropriate range, overcharge and overdischarge of the power source can be suppressed.

  In a vehicle using such a motor as a driving force source, it is desirable to fully utilize the charging / discharging capability of the power source in order to improve the running performance such as acceleration performance and running distance. For example, in Japanese Patent Laid-Open No. 2003-153402 (Patent Document 1), a secondary battery input / output continuation at a certain power based on a current state quantity (SOC, temperature, etc.) using a secondary battery voltage model is disclosed. A secondary battery control device having a calculation means for calculating time is disclosed.

According to this, in a vehicle equipped with a secondary battery, when switching from motor drive to engine drive according to the state of the secondary battery, the secondary battery satisfies the power and duration required for engine cranking. By determining whether or not, the engine can be started when the output of the secondary battery falls to a limit state. Therefore, the secondary battery can be used to the limit.
JP 2003-153402 A JP 2007-74765 A

  However, in the secondary battery control device disclosed in Japanese Patent Laid-Open No. 2003-153402, the use efficiency of the secondary battery can be increased by using the secondary battery to the limit, while the secondary battery is low. When exposed to the SOC state, there is a problem that overdischarge occurs and the battery performance deteriorates.

  In addition, when high load driving is required, for example, when the driver fully opens the accelerator immediately after starting the engine, it is necessary to continuously supply power from the secondary battery to the motor for torque assist. However, since the SOC of the secondary battery has already decreased, it is determined that the possibility of overdischarge is further increased.

  In order to fully demonstrate the charge / discharge capability of the power supply, it is necessary to avoid using the power supply with overdischarge and overcharge. However, the above-mentioned Japanese Patent Application Laid-Open No. 2003-153402 does not disclose a solution to such a problem.

  Therefore, the present invention has been made to solve such a problem, and an object of the present invention is to provide a power supply device capable of reliably suppressing overdischarge of the power supply and a discharge control method thereof. .

  A power supply apparatus according to an aspect of the present invention has a first travel mode using a motor for driving an engine and a vehicle as a power source, and a second travel mode using only the motor as a power source with the engine stopped. Installed in the vehicle. The power supply device has a power supply, a motor drive control unit that receives power supply from the power supply and converts the power into drive power control according to a drive force command value, and a drive force based on a required drive force required for the drive shaft. And a control device that generates a driving force command value so as to be output to the driving shaft. When the control device receives a request for switching to the first travel mode during execution of the second travel mode, a travel mode setting unit that switches between the first travel mode and the second travel mode according to the required driving force, A start control unit that receives power from the power supply and starts the engine, and sets a first voltage as a lower limit voltage allowed for the power supply, and discharges the power supply so that the power supply voltage does not fall below the first voltage. A discharge allowable power calculation unit that derives the allowable power, and a drive control unit that adjusts the driving force command value so that the power consumption of the motor corresponding to the driving force command value does not exceed the discharge allowable power. When the required driving force reaches a predetermined reference value within a predetermined time after the request for switching to the first travel mode is given, the discharge allowable power calculation unit uses the first voltage as the lower limit voltage. A higher second voltage is set.

  Preferably, the travel mode setting unit switches between the first travel mode and the second travel mode according to the accelerator opening, and the discharge allowable power calculation unit is given a request to switch to the first travel mode. If the accelerator opening reaches a predetermined reference opening within a predetermined time later, the second voltage is set as the lower limit voltage.

  Preferably, the discharge allowable power calculation unit sets the predetermined reference opening so as to include the fully opened state of the accelerator opening.

  Preferably, the discharge allowable power calculation unit sets the predetermined period to a time shorter than the cranking time of the engine.

  A discharge control method according to another aspect of the present invention includes a first travel mode in which an engine and a motor for driving a vehicle are used as power sources, and a second travel mode in which the engine is stopped and only the motor is used as a power source. It is the discharge control method of the power supply device mounted in the vehicle which has this. The power supply device includes a power supply and a motor drive control unit that receives supply of power from the power supply and converts the power into power for driving and controlling the motor according to the drive force command value. The discharge control method includes a step of switching between the first travel mode and the second travel mode in accordance with a required driving force required for the drive shaft, and a request for switching to the first travel mode during execution of the second travel mode. Receiving the power from the power source, starting the engine, generating a driving force command value so that the driving force based on the required driving force is output to the driving shaft, and allowing the power source A first voltage is set as a lower limit voltage to be generated, and the step of deriving the discharge allowable power of the power supply so that the voltage of the power supply does not fall below the first voltage, and the power consumption of the motor corresponding to the driving force command value is Adjusting the driving force command value so as not to exceed the discharge allowable power. The step of deriving the discharge allowable power includes the first lower limit voltage as the lower limit voltage when the required driving force reaches a predetermined reference value within a predetermined time after the request for switching to the first traveling mode is given. A second voltage higher than the voltage is set.

  According to this invention, in the hybrid vehicle, the power supply can be reliably protected from overdischarge. As a result, the charging / discharging capability of the power source can be fully exhibited, and the running performance and fuel consumption performance of the vehicle can be improved.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In the drawings, the same reference numerals indicate the same or corresponding parts.

  FIG. 1 is a block diagram illustrating a configuration of a vehicle equipped with a power supply device according to an embodiment of the present invention.

  Referring to FIG. 1, a hybrid vehicle 100 according to the present invention includes a battery 10, an ECU (Electronic Control Unit) 15, a PCU (Power Control Unit) 20, a power output device 30, and a differential gear (Differential Gear) 40. And front wheels 50L and 50R, rear wheels 60L and 60R, front seats 70L and 70R, and a rear seat 80.

  The battery 10 is formed of a secondary battery such as nickel metal hydride or lithium ion, for example, and supplies a DC voltage to the PCU 20 and is charged by the DC voltage from the PCU 20. The battery 10 is disposed, for example, at the rear portion of the rear seat 80 and is electrically connected to the PCU 20. The PCU 20 collectively indicates power converters required in the hybrid vehicle 100.

  Various sensor outputs 17 from various sensors indicating the driving situation / vehicle situation are input to the ECU 15. The various sensor outputs 17 include an accelerator opening, a wheel speed sensor output, and the like corresponding to an accelerator depression amount detected by a position sensor disposed on the accelerator pedal 35. The ECU 15 comprehensively performs various controls relating to the hybrid vehicle 100 based on these input sensor outputs.

  Power output device 30 is provided as a wheel driving force source, and includes an engine and / or motor generators MG1 and MG2. These are mechanically connected via a power split mechanism (not shown). Then, according to the traveling state of the hybrid vehicle 100, the driving force is distributed and combined among the three parties via the power split mechanism, and as a result, the front wheels 50L and 50R are driven. The DG 40 transmits the power from the power output device 30 to the front wheels 50L and 50R, and transmits the rotational force of the front wheels 50L and 50R to the power output device 30.

  Thereby, motive power output device 30 transmits the power from engine and / or motor generators MG1, MG2 to front wheels 50L, 50R via DG 40 to drive front wheels 50L, 50R. In addition, power output device 30 generates power by the rotational force of motor generators MG1 and MG2 by front wheels 50L and 50R, and supplies the generated power to PCU 20.

  Motor generators MG1 and MG2 can function as both a generator and an electric motor, but motor generator MG1 mainly operates as a generator, and motor generator MG2 mainly operates as an electric motor.

  Specifically, motor generator MG1 is used as start-up air for starting the engine during acceleration. At this time, motor generator MG1 is supplied with electric power from battery 10 and is driven as an electric motor, and cranks and starts the engine.

  Further, after the engine is started, motor generator MG1 is rotated by the driving force of the engine transmitted through the power split mechanism to generate electric power.

  Motor generator MG2 is driven by at least one of the electric power stored in battery 10 and the electric power generated by motor generator MG1. The driving force of motor generator MG2 is transmitted to the driving shafts of front wheels 50L and 50R via DG40. Thereby, motor generator MG2 assists the engine to travel the vehicle, or travels the vehicle only by its own driving force.

  At the time of regenerative braking of the vehicle, motor generator MG2 is driven by front wheels 50L and 50R to operate as a generator. At this time, the regenerative power generated by motor generator MG2 is charged to battery 10 via PCU 20.

  PCU 20 boosts the DC voltage from battery 10 according to a control instruction from ECU 15 during powering operation of motor generators MG1 and MG2, and converts the boosted DC voltage into an AC voltage, and is included in power output device 30. The motor generators MG1 and MG2 to be driven are controlled.

  In addition, during regenerative braking of motor generators MG1 and MG2, PCU 20 charges battery 10 by converting the AC voltage generated by motor generators MG1 and MG2 into a DC voltage in accordance with a control instruction from ECU 15.

  Thus, in hybrid vehicle 100, “power supply device” that drives and controls motor generators MG <b> 1 and MG <b> 2 is configured by battery 10, PCU 20, and a portion of ECU 15 that controls PCU 20.

Next, the configuration of the power supply device according to the present invention will be described.
FIG. 2 is a block diagram showing the configuration of the power supply device according to the present invention.

  Referring to FIG. 2, a power supply device according to the present invention includes a battery 10 corresponding to “power supply”, a voltage sensor 12 that detects a DC voltage Vb from battery 10, and driving motor generators MG <b> 1 and MG <b> 2 of PCU 20. A part related to control (hereinafter, this part is also simply referred to as “PCU 20”) and a part of the ECU 15 that controls the PCU 20 (hereinafter referred to as “control device 15”) are provided.

  PCU 20 includes a converter 110, a smoothing capacitor 120, motor drive controllers 131 and 132 corresponding to motor generators MG1 and MG2, respectively, and a converter / inverter control unit 140. In this embodiment, since motor generators MG1 and MG2 which are AC motors are driven and controlled, motor drive controllers 131 and 132 are configured by inverters. Hereinafter, the motor drive controllers 131 and 132 are referred to as inverters 131 and 132.

  Based on various sensor outputs 17, control device 15 determines required torque Trq for motor generators MG1 and MG2 in consideration of output distribution with engine ENG and the like. Further, control device 15 calculates optimal motor operating voltage Vm # according to the operating state of motor generators MG1, MG2.

  Control device 15 further performs voltage command value Vmr and motor generator MG1 of motor operating voltage Vm by a method described later based on required torque Trq, optimal motor operating voltage Vm #, and DC voltage Vb from voltage sensor 12. , MG2 generates a torque command value Tref. Voltage command value Vmr and torque command value Tref are applied to converter / inverter control unit 140.

  Converter / inverter control unit 140 generates converter control signal Scnv for controlling the operation of converter 110 in accordance with voltage command value Vmr from control device 15. Further, converter / inverter control unit 140 generates inverter control signals Spwm1 and Spwm2 for controlling the operations of inverters 131 and 132, respectively, according to torque command value Tref from control device 15.

Next, the control structure of the control device 15 according to the present invention will be described with reference to FIG.
FIG. 3 is a block diagram showing a control structure in control device 15 according to the embodiment of the present invention. The control block shown in FIG. 3 is typically realized by the control device 15 executing a program stored in advance, but part or all of the configuration may be realized as dedicated hardware.

  Referring to FIG. 3, control device 15 includes an HV control unit 150, a battery lower limit voltage setting unit 152, and a discharge allowable power calculation unit 154.

  HV control unit 150 sets travel mode DM of hybrid vehicle 100 and outputs the set travel mode DM to battery lower limit voltage setting unit 152.

  Specifically, the HV control unit 150 travels by the output of only the motor generator MG2 in accordance with the accelerator opening and the wheel speed included in the various sensor outputs 17 (hereinafter also referred to as “EV travel mode”) and The mode (hereinafter also referred to as “HV travel mode”) is switched according to the output of engine ENG and motor generator MG2.

  For example, at the time of starting and running at a low speed, or at a light load such as when going down a gentle slope, in order to avoid a region where engine efficiency is low, the engine ENG output is not used, and the vehicle travels with the output of only the motor generator MG2. The EV travel mode is set. In other words, in a region where the accelerator opening is small, hybrid vehicle 100 travels using only the output of motor generator MG2. In this case, the operation of engine ENG is stopped except when an engine start request condition described later is satisfied.

  In addition, you may make it set to EV driving mode according to operation of the EV driving | running | working selection switch (not shown) by a driver | operator.

  On the other hand, during normal travel where the accelerator opening is larger than the predetermined value α%, the engine ENG is started and set to the HV travel mode. Thereby, the output from engine ENG is divided into the driving force of front wheels 50L and 50R and the driving force for power generation by motor generator MG1 by the power split mechanism. Electric power generated by motor generator MG2 is used to drive motor generator MG2. Therefore, during normal travel, the front wheels 50L and 50R are driven by assisting the output from the engine ENG with the output from the motor generator MG2. At this time, the control device 15 controls the power split ratio by the power split mechanism so that the overall efficiency is maximized.

  Further, at the time of high acceleration, the electric power supplied from battery 10 is further used for driving motor generator MG2, and the driving force of front wheels 50L and 50R further increases.

  During regenerative braking, motor generator MG2 is driven to rotate by front wheels 50L and 50R to generate electric power. The electric power recovered by the regenerative power generation of motor generator MG2 is converted into a DC voltage by PCU 20 and used for charging battery 10. Further, when the vehicle is stopped, the engine ENG is automatically stopped.

  Thus, in hybrid vehicle 100, the operation of engine ENG and motor generator MG2 is controlled by the combination of the output from engine ENG and the output from motor generator MG2 using electric energy as a source, that is, according to the vehicle situation. The vehicle is driven with improved fuel efficiency.

  At this time, in a region where the accelerator opening is small, engine ENG start control is performed when an engine start request condition that requires engine ENG start is satisfied. The engine start request condition includes a case where a driving force request such as high acceleration is given from the driver. As an example, it includes that the accelerator opening exceeds a predetermined value α%. Furthermore, a case may be included in which a request unrelated to the driving force request is given, such as when the battery output needs to be charged, or when the engine ENG is warming up.

  HV control unit 150 cranks and starts engine ENG by driving motor generator MG1 as an electric motor upon receiving power supplied from battery 10 as engine start control when the engine start request condition is satisfied. . Further, HV control unit 150 generates an H (logic high) level engine start request signal and outputs it to battery lower limit voltage setting unit 152.

  When battery lower limit voltage setting unit 152 receives travel mode DM, engine start request signal and various sensor outputs 17 from HV control unit 150, battery lower limit voltage setting unit 152 receives the minimum allowable voltage (lower limit) allowed for battery 10 in accordance with these input signals. Voltage) Vb_lim is variably set.

  Specifically, the battery lower limit voltage setting unit 152 normally sets the lower limit voltage Vb_lim to a predetermined voltage V1. The predetermined voltage V1 is set in advance based on the charge / discharge characteristics of the battery 10 and the like so that the SOC of the battery 10 is not within an appropriate range and overdischarge is not likely.

  On the other hand, when a predetermined traveling condition in which excessive power is expected to be taken out from the battery 10 is satisfied, the battery lower limit voltage setting unit 152 sets the lower limit voltage Vb_lim to a voltage V2 ( > V1).

  Specifically, as predetermined traveling conditions, during traveling in the EV traveling mode, the engine starting control is started when the above-described engine starting request condition is satisfied, and the engine starting control is started. It is set that the driver has performed a rapid acceleration operation within a predetermined period Δt1 from the time point. The rapid acceleration operation includes that the accelerator opening corresponding to the accelerator depression amount in the accelerator pedal 35 has reached a predetermined reference opening X%. Or you may make it include the case where the request | requirement driving force calculated based on the various sensor outputs 17 reaches a predetermined reference value.

  This predetermined reference opening value X% is set to, for example, a fully open point (100%) of the accelerator opening. Note that the predetermined reference opening X% may be in a region where the accelerator opening is large, and is not necessarily limited to the full open point.

  In the above running condition, predetermined period Δt1 is set to a time shorter than the drive time (cranking time) of motor generator MG1 for cranking engine ENG.

  As described above, the engine starting control and the rapid acceleration operation are continuously performed during traveling in the EV traveling mode under the predetermined traveling condition. The reason is that the EV traveling, the engine starting control, and the rapid acceleration are performed. In any case, since power is output from the battery 10 to the motor generator MG1 or the motor generator MG2, excessive power is taken out from the battery 10 when these three are performed continuously within a short period of time. This is because it is expected to occur. As a result, overdischarge occurs in the battery 10, and the battery performance may be deteriorated.

  Therefore, in the present embodiment, when such a predetermined traveling condition is satisfied, the battery lower limit voltage setting unit 152 sets the lower limit voltage Vb_lim of the battery 10 to a voltage V2 higher than the normal voltage V1 in advance. It is set as the structure which raises. Thereby, as described below, since the restriction on the power output from the battery 10 is strengthened, the battery 10 can be prevented from being overdischarged.

  Specifically, discharge allowable power calculation unit 154 receives lower limit voltage Vb_lim from battery lower limit voltage setting unit 152 and receives DC voltage Vb from voltage sensor 12, so that DC voltage Vb does not fall below lower limit voltage Vb_lim. The allowable power Wout is derived. The discharge allowable power Wout is a limit value of the discharge power at each time point defined by the chemical reaction limit.

  Specifically, discharge allowable power calculation unit 154 compares the magnitude relationship between DC voltage Vb from voltage sensor 12 and lower limit voltage Vb_lim, and when DC voltage Vb is higher than lower limit voltage Vb_lim, DC voltage Vb. Based on the above, discharge allowable power Wout is derived. At this time, discharge allowable power calculation unit 154 derives discharge allowable power Wout based on the SOC calculated from DC voltage Vb using a known technique.

  On the other hand, when DC voltage Vb becomes equal to or lower than lower limit voltage Vb_lim, discharge allowable power calculation unit 154 fixes discharge allowable power Wout to a predetermined minimum allowable power (lower limit power). In this way, power limitation of the battery 10 is performed so that the DC voltage Vb does not fall below the lower limit voltage Vb_lim.

  In such power limitation of the battery 10, when the predetermined traveling condition is satisfied, the lower limit voltage Vb_lim is raised more than usual, so that the power taken out from the battery 10 is more severely limited. It becomes. As a result, occurrence of overdischarge in the battery 10 is suppressed.

  Note that, by strengthening the power limit of the battery 10, it becomes difficult for the power supplied from the battery 10 to the PCU 20 to always satisfy the required output of the motor generator MG2, but the driving situation is the main output from the engine ENG. Therefore, it is determined that the driving characteristics of the vehicle (or the driving feeling of the driver) are not impaired.

  In actuality, discharge allowable power calculation unit 154 stores a discharge allowable power map defined in advance using DC voltage Vb as a parameter, and derives discharge allowable power Wout at each time point based on DC voltage Vb. Note that this discharge allowable power map includes two types of maps, a map that is used during normal times (that is, when a predetermined traveling condition is not satisfied) and a map that is used when a predetermined traveling condition is satisfied. Then, discharge allowable power calculation unit 154 outputs derived discharge allowable power Wout to HV control unit 150.

  As described above, the HV control unit 150 sets the travel mode DM of the hybrid vehicle 100 in accordance with the various sensor outputs 17, and based on the various sensor outputs 17, the motor generator MG <b> 1 takes into account output distribution with the engine and the like. MG2 required torque Trq is determined. Furthermore, the HV control unit 150 calculates an optimum motor operating voltage Vm # according to the determined required torque Trq and the motor rotational speed.

  Then, HV control unit 150 determines voltage command value Vmr for motor operating voltage Vm and torque command value Tref for motor generators MG1 and MG2 based on required torque Trq, optimum motor operating voltage Vm #, and discharge allowable power Wout. Is generated.

  Specifically, the HV control unit 150 calculates motor power consumption corresponding to the required torque Trq, and determines whether or not the calculated motor power consumption exceeds the discharge allowable power Wout. At this time, if the motor power consumption is equal to or less than the allowable discharge power Wout, the discharge allowable power Wout will not be exceeded even if power is consumed by the motor generators MG1, MG2 in accordance with the required torque Trq. 150 sets the torque command value Tref to be equal to the required torque Trq. Further, the HV control unit 150 sets the voltage command value Vmr to be equal to the optimum motor operating voltage Vm #.

  On the other hand, when the motor power consumption exceeds the discharge allowable power Wout, if the motor generators MG1 and MG2 consume power according to the required torque Trq, the motor power consumption exceeds the discharge allowable power Wout. Therefore, in this case, the motor power consumption is limited so as not to exceed the discharge allowable power Wout.

  Specifically, the motor power consumption at the limit where motor power consumption = discharge allowable power Wout is established, and the torque command value Tref is calculated in correspondence with the calculated motor power consumption. That is, the torque command value Tref is limited to be smaller than the initial required torque Trq. Similarly, voltage command value Vmr is limited to be smaller than the initial optimum motor operating voltage Vm # in accordance with the limited required torque Trq.

  Torque command value Tref and voltage command value Vmr generated in this way are applied to converter / inverter control unit 140. Converter / inverter control unit 140 determines the boost ratio in converter 110 (FIG. 2) based on voltage command value Vmr, and generates converter control signal Scnv so that this boost ratio is realized.

  Further, converter / inverter control unit 140 causes inverter control signals in accordance with output values from various sensors so that motor currents that generate torque according to torque command value Tref flow in motor generators MG1 and MG2. Spwm1 and Spwm2 are generated. For example, inverter control signals Spwm1 and Spwm2 are PWM signal waves generated according to a general control method. The output values from the various sensors include, for example, output values from the position sensors and speed sensors of the motor generators MG1 and MG2, output values from the current sensors that detect each phase current, and voltages that detect the motor operating voltage Vm. The output value from the sensor is included.

FIG. 4 is a diagram illustrating a temporal change in the DC voltage Vb of the battery 10.
Referring to FIG. 4, it is assumed that traveling of hybrid vehicle 100 is started at time t0. At this time t0, the accelerator opening included in the various sensor outputs 17 is smaller than the predetermined value α%. Therefore, hybrid vehicle 100 starts traveling in the EV traveling mode.

  If the accelerator opening exceeds the predetermined value α% during the travel in the EV travel mode (time t = t1), it is determined that the engine start request condition is satisfied, and the engine start control is performed. That is, after time t1, motor generator MG1 receives the supply of electric power from battery 10 and drives it as an electric motor, thereby cranking and starting engine ENG. Then, the torque (MG1 torque) output from motor generator MG1 increases after time t1. Then, the engine speed increases so as to follow this. Note that, when the engine speed reaches a predetermined speed, the engine start control is terminated, so the MG1 torque starts to decrease.

  Then, after the engine start control is started, a rapid acceleration operation is performed by the driver, and when the accelerator opening reaches a predetermined reference opening X% at time t2 when time Δt (≦ Δt1) has elapsed from time t1, The electric power supplied from battery 10 is further used to drive motor generator MG2. Thereby, the torque (MG2 torque) output from motor generator MG2 increases. Then, the engine speed further increases.

  In these series of operations, electric power stored in the battery 10 is used to drive the motor generators MG1 and MG2. Therefore, in the battery 10, the DC voltage Vb rapidly decreases after time t1, as indicated by the line LN1 or LN2 in the drawing. Therefore, in battery 10, output restriction is performed according to DC voltage Vb.

  In the output limitation of the battery 10, when the lower limit voltage Vb_lim is fixed to the voltage V1, the discharge allowable power Wout is reduced in response to the DC voltage Vb being lower than the voltage V1, as indicated by the line LN3 in the figure. Limited. As a result, the DC voltage Vb is maintained at substantially the voltage V1, as indicated by the line LN1 in the drawing. At this time, since the battery 10 is exposed to a low SOC state, overdischarge occurs and the battery performance may be deteriorated.

  On the other hand, in the present embodiment, since the accelerator opening has reached the predetermined reference opening X% at the time t2 within the predetermined period Δt1 from the time t1 when the engine start control is started, the lower limit voltage Vb_lim is reduced. The voltage is raised to a voltage V2 higher than the voltage V1. Thereby, after time t2, as indicated by line LN4 in the figure, discharge allowable power Wout is limited in response to DC voltage Vb being lower than voltage V2. As a result, the DC voltage Vb is maintained at substantially the voltage V2, as indicated by the line LN2 in the figure, so that the battery 10 is prevented from being overdischarged.

  Such an increase in the lower limit voltage Vb_lim is canceled in response to a decrease in power taken out from the battery 10. For example, as shown in FIG. 4, when the accelerator opening is below a predetermined reference value (time t = t3), the lower limit voltage Vb_lim is returned to the voltage V1.

  FIG. 5 is a flowchart for explaining drive control of the motor generator by the control device 15. In addition, the process of each step shown in FIG. 5 is implement | achieved when the control apparatus 15 (FIG. 2) functions as each control block shown in FIG.

  Referring to FIG. 5, battery lower limit voltage setting unit 152 determines whether or not hybrid vehicle 100 is traveling in EV based on travel mode DM given from HV control unit 150 (step S01). This determination is made according to whether or not the EV traveling mode has continued for a predetermined period. That is, when the EV travel mode has continued beyond the certain time, battery lower limit voltage setting unit 152 determines that hybrid vehicle 100 is traveling in EV.

  When hybrid vehicle 100 is traveling in EV (in the case of YES in step S01), battery lower limit voltage setting unit 152 further determines whether or not an engine start request is generated (step S02). Specifically, battery lower limit voltage setting unit 152 determines whether or not the engine start request signal from HV control unit 150 is at the H level.

  When the engine start request signal is at the H level, that is, when the engine start request is generated (YES in step S02), battery lower limit voltage setting unit 152 subsequently continues after the engine start request is generated. It is determined whether or not the accelerator opening has reached a predetermined reference opening X% within a predetermined period Δt1 (step S03).

  When the accelerator opening reaches a predetermined reference opening X% within the predetermined period Δt1 (YES in step S03), the battery lower limit voltage setting unit 152 sets the lower limit voltage Vb_lim of the battery 10 to the voltage. V2 (> V1) is set (step S04).

  In contrast, when hybrid vehicle 100 is not in EV travel (NO in step S01), an engine start request is not generated (NO in step S02), and a predetermined period Δt1 after the engine start request is generated. If the accelerator opening does not reach the predetermined reference opening X% (NO in step S03), battery lower limit voltage setting unit 152 sets lower limit voltage Vb_lim to voltage V1. (Step S05). The lower limit voltage Vb_lim set in step S04 or S05 is output to discharge allowable power calculation unit 154.

  Discharge allowable power calculation unit 154 receives lower limit voltage Vb_lim from battery lower limit voltage setting unit 152 and receives DC voltage Vb from voltage sensor 12 (FIG. 2), and determines whether or not DC voltage Vb is lower than lower limit voltage Vb_lim. (Step S06).

  When DC voltage Vb is equal to or higher than lower limit voltage Vb_lim (NO in step S06), discharge allowable power calculation unit 154 refers to the discharge allowable power map, and determines discharge allowable power Wout corresponding to DC voltage Vb. calculate.

  In contrast, when DC voltage Vb is lower than lower limit voltage Vb_lim (YES in step S06), discharge allowable power calculation unit 154 fixes discharge allowable power Wout to a preset lower limit power. Then, the output power from the battery 10 is limited (step S07).

  Based on the discharge allowable power Wout calculated and set in step S06 or S07 and the required torque Trq calculated according to various sensor outputs, the HV control unit 150 determines that the motor power consumption corresponding to the required torque Trq is the discharge allowable power. Torque command value Tref is calculated so as not to exceed Wout (step S09).

  Thus, switching control of inverters 131 and 132 is performed in accordance with torque command value Tref calculated in step S09, and torque (ie, motor current) of motor generators MG1 and MG2 is controlled (step S10).

  As described above, according to the embodiment of the present invention, when a driving condition in which excessive power is expected to be taken out from the battery is satisfied, the battery output is limited by raising the lower limit voltage of the battery in advance. Thus, it is possible to suppress the occurrence of overdischarge in the battery. As a result, deterioration of the battery performance can be suppressed and the charge / discharge capability of the battery can be sufficiently exerted, so that the running performance and fuel consumption performance of the vehicle can be improved.

  As for the correspondence relationship between the embodiment of the present invention and the present invention, the HV traveling mode corresponds to the “first traveling mode” and the EV traveling mode corresponds to the “second traveling mode”. In the control structure of the control device 15 shown in FIG. 3, the HV control unit 150 realizes a “running mode setting unit”, a “starting control unit”, and a “drive control unit”, and the battery lower limit voltage setting unit 152 and the discharge allowance. The power calculation unit 154 implements a “discharge allowable power calculation unit”. Each functional block constituting these means has been described as functioning as software realized by a CPU (Central Processing Unit) that is the control device 15 executing a program stored in the storage unit. It may be realized by hardware. Such a program is recorded on a recording medium and mounted on the vehicle.

  The embodiment disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

  The present invention can be applied to a power supply device mounted on a hybrid vehicle.

1 is a block diagram illustrating a configuration of a vehicle equipped with a power supply device according to an embodiment of the present invention. It is a block diagram which shows the structure of the power supply device by this invention. It is a block diagram which shows the control structure in the control apparatus according to embodiment of this invention. It is a figure which shows the time change of DC voltage Vb of a battery. It is a flowchart explaining the drive control of the motor generator by a control apparatus.

Explanation of symbols

  10 battery, 12 voltage sensor, 15 control device, 17 various sensor outputs, 30 power output device, 35 accelerator pedal, 50L, 50R front wheel, 60L, 60R rear wheel, 70L, 70R front seat, 80 rear seat, 100 hybrid vehicle, 110 Converter, 120 smoothing capacitor, 131, 132 motor drive controller, 140 converter / inverter control unit, 150 HV control unit, 152 battery lower limit voltage setting unit, 154 discharge allowable power calculation unit, ENG engine, MG1, MG2 motor generator.

Claims (5)

A power supply device mounted on a vehicle having a first travel mode using a motor for driving an engine and a vehicle as a power source, and a second travel mode using only the motor as a power source with the engine stopped. There,
Power supply,
A motor drive control unit that receives supply of electric power from the power source and converts the electric power to drive and control the motor according to a driving force command value;
A controller that generates the driving force command value so that a driving force based on a required driving force required for the driving shaft is output to the driving shaft;
The controller is
A travel mode setting unit that switches between the first travel mode and the second travel mode according to the required driving force;
When a request for switching to the first travel mode is received during execution of the second travel mode, a start control unit that receives power from the power source and starts the engine;
A discharge allowable power calculation unit that sets a first voltage as a lower limit voltage allowed for the power supply and derives a discharge allowable power of the power supply so that the voltage of the power supply does not fall below the first voltage;
A drive control unit that adjusts the driving force command value so that power consumption of the motor corresponding to the driving force command value does not exceed the discharge allowable power;
When the required driving force reaches a predetermined reference value within a predetermined time after the request for switching to the first travel mode is given, the discharge allowable power calculation unit is configured to use the lower limit voltage as the lower limit voltage. A power supply device that sets a second voltage higher than the first voltage. The travel mode setting unit switches between the first travel mode and the second travel mode according to the accelerator opening,
When the accelerator opening reaches a predetermined reference opening within a predetermined time after the request for switching to the first traveling mode is given, the discharge allowable power calculating unit sets the lower limit voltage as the lower limit voltage. The power supply device according to claim 1, wherein the second voltage is set.   The power supply apparatus according to claim 2, wherein the discharge allowable power calculation unit sets the predetermined reference opening so as to include a fully opened state of the accelerator opening.   The power supply apparatus according to claim 1, wherein the discharge allowable power calculation unit sets the predetermined period to a time shorter than a cranking time of the engine. A power supply device mounted on a vehicle having a first travel mode using a motor for driving an engine and a vehicle as a power source, and a second travel mode using only the motor as a power source with the engine stopped. A discharge control method comprising:
The power supply device
Power supply,
A motor drive control unit that receives supply of electric power from the power source and converts the electric power to drive and control the motor according to a driving force command value;
The discharge control method includes:
Switching between the first travel mode and the second travel mode according to the required driving force required for the drive shaft;
Receiving a request for switching to the first travel mode during execution of the second travel mode, receiving power from the power source and starting the engine;
Generating the driving force command value so that a driving force based on the required driving force is output to the driving shaft;
Setting a first voltage as a lower limit voltage allowed for the power supply, and deriving discharge allowable power of the power supply so that the voltage of the power supply does not fall below the first voltage;
Adjusting the driving force command value so that the power consumption of the motor corresponding to the driving force command value does not exceed the discharge allowable power,
The step of deriving the discharge allowable power includes the lower limit voltage when the required driving force reaches a predetermined reference value within a predetermined time after the request for switching to the first traveling mode is given. As a discharge control method, a second voltage higher than the first voltage is set.

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