JP4175322B2 - vehicle - Google Patents

Description

  The present invention relates to an input / output control device and a vehicle, and particularly to a vehicle equipped with a secondary battery.

  In recent years, vehicles such as electric vehicles, hybrid vehicles, and fuel cell vehicles that employ a motor as a driving source for vehicle propulsion and have a large-capacity battery that stores electric power for driving the motor have appeared. .

  Japanese Patent Laid-Open No. 2000-2758 (Patent Document 1) discloses a battery maximum input / output for accurately estimating the maximum input / output power of the battery and expanding the use range of the battery without adversely affecting the battery life. A power estimation apparatus is disclosed.

This maximum input / output power estimation device does not simply estimate the maximum input / output power from the relationship between the regenerative current or discharge current and the voltage characteristics of the battery, but the open-circuit voltage obtained from the state of charge (SOC) of the battery and the battery's voltage characteristics. The battery voltage is estimated in consideration of the voltage fluctuation due to internal resistance and the dynamic voltage fluctuation based on the fluctuation of charge / discharge current, and this battery voltage reaches the maximum allowable voltage or the minimum allowable voltage within a predetermined time. The charging / discharging current value for estimating the maximum input / output power of the battery is estimated from this value. In other words, because it takes into account the dynamic fluctuation of the battery voltage that accompanies the fluctuation of the charging / discharging current, the maximum input / output power can be accurately estimated even in a usage environment where the charging / discharging current fluctuates drastically like a hybrid vehicle. be able to. Therefore, since the margin on the safe side can be reduced, the battery usage range can be expanded without adversely affecting the battery life.
JP 2000-2758 A JP 2001-327094 A JP-A-9-193675 JP-A-11-187777

  However, in Japanese Patent Laid-Open No. 2000-2758 (Patent Document 1), the battery voltage fluctuation range is considered as a dynamic fluctuation amount, but the rate of change of the battery voltage, that is, the slope of the time change of the voltage is not taken into consideration. When setting the target lower limit voltage of the feedback control, it is necessary to set it with a sufficient margin with respect to the use lower limit voltage that impairs the battery life. For this reason, the performance of a battery cannot fully be drawn out.

  For this reason, in order to achieve a predetermined performance, it is necessary to increase the capacity of the battery, which increases the weight of the vehicle and the price.

  An object of the present invention is to provide an input / output control device capable of more effectively extracting the performance of a battery and a vehicle with improved performance as a result.

  In summary, the present invention is an input / output control device that receives a battery voltage detected by a voltage detector and a voltage detector that detects a battery voltage of a secondary battery, and changes the battery voltage and the battery voltage. And a setting unit for setting an input / output limit value for the secondary battery.

  Preferably, the setting unit sets the input / output limit value when the battery voltages are equal at least within a predetermined battery voltage range as the absolute value of the change speed increases.

  Preferably, the secondary battery is an assembled battery including a plurality of battery units. The voltage detector detects a plurality of positive and negative voltages corresponding to the plurality of battery units, respectively. The setting unit selects the minimum value among the plurality of positive and negative voltages as the reference voltage, and sets the input / output limit value for the secondary battery based on the reference voltage and the change speed of the reference voltage.

  Preferably, the secondary battery is an assembled battery including a plurality of battery units. The voltage detector detects a plurality of positive and negative voltages corresponding to the plurality of battery units, respectively. The setting unit selects the maximum value among the plurality of positive and negative voltages as the reference voltage, and sets the input / output limit value for the secondary battery based on the reference voltage and the change speed of the reference voltage.

  Preferably, the input / output control device further includes a temperature detection unit that detects a battery temperature of the secondary battery. The setting unit further sets an input / output limit value for the secondary battery based on the battery temperature.

  According to another aspect of the present invention, the vehicle is a secondary battery, a voltage detection unit that detects a battery voltage of the secondary battery, a battery voltage detected by the voltage detection unit, a battery voltage and a battery voltage And a control device that sets an input / output limit value for the secondary battery based on the change rate of the secondary battery.

  Preferably, the control device sets the input / output limit value when the battery voltages are equal at least in a predetermined battery voltage range to be smaller as the absolute value of the change speed is larger.

  Preferably, the secondary battery is an assembled battery including a plurality of battery units. The voltage detector detects a plurality of positive and negative voltages corresponding to the plurality of battery units, respectively. The control device selects the minimum value among the plurality of positive and negative voltages as the reference voltage, and sets the input / output limit value for the secondary battery based on the reference voltage and the change speed of the reference voltage.

  Preferably, the secondary battery is an assembled battery including a plurality of battery units. The voltage detector detects a plurality of positive and negative voltages corresponding to the plurality of battery units, respectively. The control device selects a maximum value among a plurality of positive and negative voltages as a reference voltage, and sets an input / output limit value for the secondary battery based on the reference voltage and the change speed of the reference voltage.

  Preferably, the vehicle further includes a temperature detection unit that detects a battery temperature of the secondary battery. The control device further sets an input / output limit value for the secondary battery based on the battery temperature.

  Preferably, the vehicle further includes an inverter that exchanges power with the secondary battery, and a rotating electrical machine controlled by the inverter. The control device limits the operation of the inverter based on the input / output limit value.

  According to the present invention, the battery storage performance and discharge performance of the battery can be sufficiently obtained, the amount of the battery mounted can be optimized, and a vehicle with a balance between cost and performance can be realized.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In the drawings, the same or corresponding parts are denoted by the same reference numerals and description thereof will not be repeated.

  FIG. 1 is a schematic diagram showing a configuration of a hybrid vehicle 1 according to the first embodiment.

  Referring to FIG. 1, hybrid vehicle 1 includes front wheels 20R and 20L, rear wheels 22R and 22L, an engine 2, a planetary gear 16, a differential gear 18, and gears 4 and 6.

  The hybrid vehicle 1 further includes a battery 12 disposed behind the vehicle, a booster unit 32 that boosts the DC power output from the battery 12, an inverter 36 that transfers DC power between the booster unit 32, and the planetary gear 16. Includes a motor generator MG1 that receives power from the engine 2 to generate power and a motor generator MG2 whose rotating shaft is connected to the planetary gear 16. Inverter 36 is connected to motor generators MG1 and MG2, and converts AC power and DC power from the booster circuit.

  Planetary gear 16 has first to third rotation shafts. The first rotation shaft is connected to engine 2, the second rotation shaft is connected to motor generator MG1, and the third rotation shaft is connected to motor generator MG2.

  A gear 4 is attached to the third rotating shaft, and the gear 4 drives the gear 6 to transmit power to the differential gear 18. The differential gear 18 transmits the power received from the gear 6 to the front wheels 20R and 20L, and transmits the rotational force of the front wheels 20R and 20L to the third rotating shaft of the planetary gear via the gears 6 and 4.

  Planetary gear 16 serves to divide the power between engine 2 and motor generators MG1, MG2. That is, if the rotation of two of the three rotation shafts of the planetary gear 16 is determined, the rotation of the remaining one rotation shaft is naturally determined. Accordingly, the vehicle speed is controlled by controlling the power generation amount of the motor generator MG1 and driving the motor generator MG2 while operating the engine 2 in the most efficient region, thereby realizing an overall energy efficient vehicle. Yes.

  The battery 12 that is a DC power source is made of, for example, a secondary battery such as nickel metal hydride or lithium ion, and supplies DC power to the boost unit 32 and is charged by DC power from the boost unit 32.

  Boost unit 32 boosts the DC voltage received from battery 12 and supplies the boosted DC voltage to inverter 36. Inverter 36 converts the supplied DC voltage into AC voltage, and drives and controls motor generator MG1 when the engine is started. Further, after the engine is started, AC power generated by motor generator MG1 is converted to DC by inverter 36 and converted to a voltage suitable for charging battery 12 by boosting unit 32, and battery 12 is charged.

  Inverter 36 drives motor generator MG2. Motor generator MG2 assists engine 2 to drive front wheels 20R and 20L. During braking, the motor generator performs a regenerative operation and converts the rotational energy of the wheels into electric energy. The obtained electric energy is returned to the battery 12 via the inverter 36 and the booster unit 32.

  System main relays 28 and 30 are provided between the booster unit 32 and the battery 12, and the high voltage is cut off when the vehicle is not in operation.

  The battery 12 is an assembled battery and includes a plurality of battery units B0 to Bn connected in series.

  The hybrid vehicle 1 further includes a temperature sensor 24 and a voltage sensor 26 attached to the battery 12, and a control unit 14 that controls the engine 2, the inverter 36, and the booster unit 32 according to the outputs of the temperature sensor 24 and the voltage sensor 26. Including. The temperature sensor 24 detects the temperature of the battery and transmits it to the control unit 14. The voltage sensor 26 detects the terminal voltages V0 to Vn of the battery units B0 to Bn and transmits them to the control unit 14.

  The control unit 14 receives the battery voltage detected by the voltage sensor 26 and sets an input / output limit value for the battery 12 based on the battery voltage and the rate of change of the battery voltage.

  The control unit 14 sets the input / output limit value when the battery voltages are equal to each other at least in a predetermined battery voltage range as the absolute value of the change rate of the battery voltage increases. That is, when the discharge amount is large and the voltage drop occurs rapidly at the time of discharging, the output limit value of the battery 12 is reduced to prevent the voltage drop from occurring rapidly. Conversely, during charging, if the amount of charge is large and the voltage rises rapidly, the input limit value of the battery 12 is reduced to prevent the voltage from rising rapidly. As a result, the battery voltage can be managed well within the control target range voltage.

  FIG. 2 is a flowchart for explaining setting of limit values performed by control unit 14 in FIG. The processing routine of this flowchart from the main routine is executed every predetermined time or every time a predetermined condition is satisfied.

  1 and 2, when the limit value setting process is started, first, in step S1, control unit 14 reads the output of temperature sensor 24 and measures the battery temperature.

  Subsequently, in step S2, the control unit reads the output of the voltage sensor 26 and measures the inter-terminal voltages V0 to Vn of the battery units B0 to Bn.

  Thereafter, a minimum value Vmin among the voltages V0 to Vn measured in step S3 is calculated. In step S4, the minimum value Vmin of the voltages V0 to Vn obtained when the routine was executed last time and the minimum value Vmin of the voltages V0 to Vn obtained when the routine was executed this time are obtained. Using this, the slope of the voltage Vmin, that is, the amount of change per time is obtained. The d / dt (Vmin) may be obtained by further referring to not only the previous and current Vmin but also the Vmin history obtained so far.

  Subsequently, in step S5, a map corresponding to d / dt (Vmin) stored in advance in a memory built in the control unit 14 is referenced to obtain a limit value at that time corresponding to the battery voltage.

  FIG. 3 is a diagram showing an example of a map used for setting the output limit value used in step S5 of FIG.

  Referring to FIG. 3, when the battery voltage decrease rate during discharge is dV / dt = −20 (V / sec), the output limit value is limited to PO until the battery voltage decreases to VO1. However, when the battery voltage falls below VO1, the output limit value gradually decreases from PO as the battery voltage decreases as indicated by W1. As a result, the battery voltage is controlled so that the target lower limit voltage VL1 is the lower limit. As a result, the battery is protected so that the battery voltage does not fall below the use lower limit value VL0.

  On the other hand, when the battery voltage drop rate during discharge is dV / dt = -100 (V / sec), the output limit value is limited to PO up to a voltage value VO2 higher than VO1, but the battery voltage When the value exceeds this value, the output limit value gradually decreases from PO as the battery voltage decreases as indicated by W2. In order to control the battery voltage so that the target lower limit voltage VL1 becomes the lower limit, when the voltage drop speed of the battery is large, the output limit value is narrowed early to prevent the battery voltage from rapidly decreasing.

  The control unit 14 receives the battery voltage detected by the voltage sensor 26, and sets the output limit value for the battery 12 based on the battery voltage and the rate of decrease of the battery voltage based on the map shown in FIG. The control unit 14 sets the output limit value when the battery voltages are equal at least in the range of the predetermined battery voltage near the target lower limit voltage VL1 as the absolute value of the change rate of the battery voltage increases. As can be seen from FIG. 3, the output limit value is set smaller when the decrease rate is dV / dt = −100 (V / sec) than when the decrease rate is dV / dt = −20 (V / sec). .

  When the limit value of the output value is set to be smaller than PO, for example, the time for performing the so-called EV travel in which only the MG2 is used without using the engine 2 is shorter than when the output limit value is PO. Control is performed as follows. As another example, for example, control is performed such that the frequency of assist travel for assisting the engine 2 with MG2 to improve acceleration is less than when the output limit value is PO.

  FIG. 4 is a waveform diagram for explaining the effect when the setting of the output limit value of FIG. 3 is applied.

  Referring to FIG. 4, waveform W3 is a waveform showing a change in voltage when the control target lower limit value is set to VL1 and ON / OFF control is simply performed. In such control, when the voltage falls below the control target lower limit value VL1 at time t2, the output is rapidly limited and the voltage is recovered thereafter. However, an undershoot occurs in the waveform of the battery voltage with respect to the control target lower limit value VL1. In addition, the control target lower limit value VL1 must be determined with a margin in consideration of the margin with respect to the battery use lower limit voltage VL0 in consideration of this undershoot, and the battery performance cannot be sufficiently extracted.

  On the other hand, the waveform W4 is a waveform showing a change in the battery voltage when the setting of the output limit value described in FIG. 3 is applied. In this case, the output limit value gradually decreases as the battery voltage decreases from time t1. For this reason, it is possible to prevent the battery voltage waveform from causing an undershoot relative to the control target lower limit value VL1. Therefore, the control target lower limit value VL1 can be determined by reducing the margin with respect to the battery use lower limit voltage VL0, and the performance of the battery can be sufficiently obtained.

  FIG. 5 is a diagram showing an example of a map used for setting the input limit value used in step S5 of FIG.

  Referring to FIG. 5, when the battery voltage rise rate during charging is dV / dt = 20 (V / sec), the input limit value is limited to PI until the battery voltage rises to VI3. However, when the battery voltage exceeds VI3, the input limit value gradually decreases from PI as the battery voltage increases as indicated by W5. Thus, the battery voltage is controlled so that the target upper limit voltage VU1 is set as the upper limit. Thereby, the battery is protected so that the battery voltage does not exceed the use upper limit value VU0.

  On the other hand, when the battery voltage rise rate during charging is dV / dt = 200 (V / sec), the input limit value is limited to PI up to a voltage value VI4 lower than VI3, but the battery voltage is When the value exceeds this value, the input limit value gradually decreases from PI as the battery voltage increases as indicated by W6. In order to control the battery voltage so that the target upper limit voltage VU1 becomes the lower limit, when the battery voltage rise rate is large, the input limit value is narrowed early to prevent the battery voltage from rising rapidly.

  The control unit 14 receives the battery voltage detected by the voltage sensor 26, and sets the input limit value for the battery 12 based on the battery voltage and the rate of decrease of the battery voltage based on the map shown in FIG. In the vicinity of the target upper limit voltage VU1, the control unit 14 sets the input limit value when the battery voltages are equal at least within a predetermined battery voltage range to be smaller as the absolute value of the battery voltage change rate is larger. As can be seen from FIG. 5, the input limit value is set smaller when the rising speed is dV / dt = 200 (V / sec) than when the rising speed is dV / dt = 20 (V / sec).

  When the input limit value is set smaller than PI, for example, the electric power by the regenerative brake collected by MG2 in FIG. 1 during vehicle braking is controlled to a value smaller than usual. In this case, in order to obtain the same braking force, the ratio of the hydraulic brake to the braking force of a friction brake (not shown) is controlled to be larger than when the input limit value is PI. In this case, the fuel consumption is slightly reduced, but the battery is well protected and the battery life is further extended.

  FIG. 6 is a waveform diagram for explaining the effect when the input limit value setting of FIG. 5 is applied.

  Referring to FIG. 6, waveform W7 is a waveform showing a change in voltage when the control target upper limit value is VU1 and the on / off control is simply performed. In such control, when the voltage falls below the control target upper limit value VU1 at time t4, the input is rapidly limited, and the voltage is then restored. However, overshoot occurs in the waveform of the battery voltage with respect to the control target upper limit value VU1. In addition, the control target upper limit value VU1 must be determined with a margin in consideration of the margin for the use upper limit voltage VU0 of the battery in consideration of this overshoot.

  On the other hand, the waveform W8 is a waveform showing a change in the battery voltage when the input limit value setting described in FIG. 5 is applied. In this case, the input limit value gradually decreases as the battery voltage increases from time t3. For this reason, it is possible to prevent the battery voltage waveform from overshooting with respect to the control target upper limit value VU1. For this reason, the control target upper limit value VU1 can be determined by reducing the margin with respect to the upper limit voltage VU0 of the battery, and the battery storage performance can be sufficiently obtained.

[Other variations]
In the maps of FIGS. 3 and 5, the slope of the battery voltage change over time, that is, the battery voltage change speed is used as a parameter, but the slope of current or power may be used. When a large current is flowed from a battery or a large amount of power is consumed, the speed of voltage drop generally increases. Therefore, by starting control for the same reason, overshoot and undershoot of the voltage waveform are less likely to occur. If it does so, the electrical storage performance and discharge performance of a battery can fully be drawn out, the loading amount of a battery can also be optimized, and the motor vehicle with which cost and performance could be balanced can be implement | achieved.

The embodiment disclosed this time should be considered as illustrative in all points and not restrictive. The scope of the present invention is shown not by the above description of the embodiments but by the scope of claims for patent, and is intended to include meanings equivalent to the scope of claims for patent and all modifications within the scope.

1 is a schematic diagram showing a configuration of a hybrid vehicle 1 according to a first embodiment. It is a flowchart for demonstrating the setting of the limit value performed by the control part 14 in FIG. It is the figure which showed the example of the map used for the setting of the output limit value used by step S5 of FIG. It is a wave form diagram for demonstrating the effect at the time of the setting of the output limit value of FIG. It is the figure which showed the example of the map used for the setting of the input limiting value used by step S5 of FIG. FIG. 6 is a waveform diagram for explaining an effect when the input limit value setting of FIG. 5 is applied.

Explanation of symbols

  1 hybrid vehicle, 2 engine, 4, 6 gear, 12 battery, 14 control unit, 16 planetary gear, 18 differential gear, 20R, 20L front wheel, 22R, 22L rear wheel, 24 temperature sensor, 26 voltage sensor, 28, 30 system main Relay, 32 boost unit, 36 inverter, MG1, MG2 motor generator.

Claims (6)

A secondary battery,
A voltage detector for detecting a battery voltage of the secondary battery;
An inverter that exchanges power with the secondary battery;
A rotating electrical machine controlled by the inverter;
A controller that receives the battery voltage detected by the voltage detector and sets an input / output limit value for the secondary battery based on the battery voltage and a change rate of the battery voltage ;
The control device shows that when the secondary battery is discharged, the rate of decrease of the voltage of the secondary battery decreases more rapidly than the first value compared to a case where the rate of decrease of the voltage of the secondary battery is a first value. In the case of the second value, the output limit value for the secondary battery is set to be small, and when the secondary battery is charged, the voltage increase rate of the secondary battery is set to the third value. In the case where the rising speed is the fourth value indicating a faster rise than the third value, the input limit value for the secondary battery is set small,
The control device limits the operation of the inverter based on the input / output limit value . 2. The vehicle according to claim 1 , wherein the control device sets the input / output limit value when the battery voltages are equal at least within a predetermined range of the battery voltage to be smaller as the absolute value of the change speed is larger. The secondary battery is an assembled battery including a plurality of battery units,
The voltage detector detects a plurality of positive and negative voltages corresponding to the plurality of battery units,
The control device selects a minimum value among the plurality of positive and negative voltages as a reference voltage, and sets an input / output limit value for the secondary battery based on the reference voltage and a change rate of the reference voltage. The vehicle according to claim 1 or 2 . The secondary battery is an assembled battery including a plurality of battery units,
The voltage detector detects a plurality of positive and negative voltages corresponding to the plurality of battery units,
The control device selects a maximum value among the plurality of positive and negative voltages as a reference voltage, and sets an input / output limit value for the secondary battery based on the reference voltage and a change rate of the reference voltage. The vehicle according to claim 1 or 2 . A temperature detector for detecting a battery temperature of the secondary battery;
The vehicle according to any one of claims 1 to 4 , wherein the control device further sets an input / output limit value for the secondary battery based on the battery temperature. A secondary battery,
A voltage detector for detecting a battery voltage of the secondary battery;
A controller that receives the battery voltage detected by the voltage detector and sets an input / output limit value for the secondary battery based on the battery voltage and a change rate of the battery voltage;
The secondary battery is an assembled battery including a plurality of battery units,
The voltage detector detects a plurality of positive and negative voltages corresponding to the plurality of battery units,
The control device selects a maximum value among the plurality of positive and negative voltages as a reference voltage, and sets an input / output limit value for the secondary battery based on the reference voltage and a change rate of the reference voltage. vehicle.

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