JP2006180665A - Charger for hybrid vehicle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a controller capable of starting an engine quickly within a range not causing overcharge of a high voltage battery. <P>SOLUTION: When an engine cannot be started, internal resistance of a high voltage battery is estimated from discharge state thereof during cranking period (S304), an output and energy required for starting the engine are calculated (S305), a first voltage V1 for ensuring the required output energy thus calculated is determined (S306), a second voltage V2 satisfying the first voltage V1 in the open circuit voltage of the high voltage battery is calculated (S307), and charging is carried out from a low voltage power supply until the high voltage battery reaches the second voltage V2 only in the state of charge required for next time engine start. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a power supply device for a vehicle such as an electric vehicle or a hybrid vehicle, and more particularly to a charging device suitable for charging with an external power source.

  2. Description of the Related Art Conventionally, there is known a vehicle power supply device that includes a high voltage battery that supplies electric power to a vehicle drive motor and a low voltage battery that supplies electric power to vehicle accessories.

Then, when the engine cannot be started, a hybrid vehicle control device including means for generating charging power for the high voltage battery using a low voltage battery outside the host vehicle as a power source and charging the high voltage battery is proposed. (For example, refer to Patent Document 1).
JP 2001-339803 A

  In the conventional example, the charging is terminated when the set time has elapsed from the start of charging. In addition to the conventional example, there is a battery that sets a voltage during charging and terminates charging when charging is performed until a predetermined voltage is reached.

  However, in the former conventional example, when sufficient charging is not performed within the set time, and in the latter example, the terminal voltage is monitored to determine that the predetermined voltage has been reached. When the internal resistance has increased due to deterioration or the like, the high voltage battery cannot be charged to a level necessary for starting the engine, and restarting may not be possible.

  Therefore, in view of the above problems, the present invention enables a quick start of an engine in a hybrid vehicle in which a high voltage battery is charged with electric power of a low voltage power source outside the host vehicle without overcharging the high voltage battery. A control device is provided.

  The present invention has an electric motor that starts an engine with a high-voltage battery, and when the engine cannot be started due to discharge of the high-voltage battery, the high-voltage battery is A charging device for a hybrid vehicle to be charged, the internal resistance estimating means for estimating the internal resistance of the high voltage battery from the discharge state of the high voltage battery during the cranking period when the engine becomes unstartable, A required output / energy calculating means for calculating an output and energy required for starting, a first voltage calculating means for obtaining a first voltage V1 capable of securing the calculated required output / energy, and an open voltage of a high-voltage battery A second voltage calculating means for calculating a second voltage V2 that satisfies the first voltage V1, and until the high-voltage battery reaches the second voltage V2. And a charging means for charging from the voltage source to charge only the charge amount required for the next engine start.

  Therefore, according to the present invention, the internal resistance is estimated from the discharge state of the high-voltage battery during cranking when the engine cannot be started, and the output and energy necessary for starting the engine are calculated based on the estimated internal resistance. A second voltage V2 that can be supplied is calculated. And, when charging the high voltage battery from the low voltage power source outside the host vehicle, it is decided to charge up to the second voltage V2, so that the engine can be started quickly without overcharging the high voltage battery. Compared to the conventional example, the charging time can be shortened.

  Hereinafter, an embodiment of the present invention will be described with reference to the accompanying drawings.

  FIG. 1 is a system configuration diagram of a hybrid vehicle including a vehicle power supply device to which the present invention is applied, and FIG. 2 is a block diagram of the vehicle power supply device.

  In FIG. 1, the drive system of the hybrid vehicle includes an engine 22, a generator 23, a motor 24, a planetary gear 25, and the like, and the motor 24 becomes an output side and is connected to a drive wheel 28 via a differential gear 26 and an axle 27. Is done. An inverter 30 that drives the generator 23 and the motor 24 and a power supply device 1 that stores input / output power to the inverter 30 are provided. Here, the power supply device 1 includes a high voltage battery 1 and a constant voltage battery 3 as shown in FIG.

  The drive system of FIG. 1 connects the output shaft of the engine 22 to one of the three elements (sun, carrier, ring) of the planetary gear unit 5 and the engine drive generator, starter motor, A generator 3 operable as a regenerative braking generator is connected, and a torque assist motor 4 is connected to the remaining one element. Then, the output side of the planetary gear mechanism 5 is connected to the differential gear 26.

  The inverter 30 inputs DC power from the high voltage battery 1 and converts it into AC power and supplies it to the motor 4. Also, the inverter 30 inputs AC power from the generator 23 and converts it into DC power to be converted into the high voltage battery 1. An inverter circuit for charging is included, and the inverter circuit is controlled by the vehicle controller 32.

  Next, in the block diagram of the power supply apparatus in FIG. 2, the high voltage battery 1 is a power source that supplies power to the electric load 12 such as the motor 24 and supplies a voltage of, for example, 350 [V].

  The low voltage battery 3 is used as a power source for other control units such as the high voltage battery ECU 13 and accessories, and supplies a voltage of, for example, 12 [V].

  A high voltage battery ECU 13 that protects and manages the high voltage battery is connected to the high voltage battery 1.

  The high voltage battery 1 is connected to a charge control device 9 that supplies power from an external low voltage power source 2 to the high voltage battery 1. Between the charging device 9 and the high voltage battery 1, a relay 10 that selectively cuts off the power supply from the high voltage battery 13 is interposed.

  The charging control device 9 includes a high voltage system circuit unit 7, a charging control unit 8, a relay 6 for inputting a low voltage power source from the outside of the vehicle, and a connector 41 for connecting to an external low voltage power source 2. The

  The high voltage system circuit unit 7 converts the charging DC power supplied via the relay contact of the relay 6 into a high frequency AC voltage by a switching circuit, boosts the converted AC voltage, and then rectifies A high voltage necessary for the generation is generated, and a charging current is supplied to the high voltage battery 1 via the relay 10.

  The charging control unit 8 is connected to a charging power supply line 4 from a relay contact of the relay 6 and a start switch 5 for charging work. Further, the relay coil of the relay 6 and the relay coil of the relay 10 are connected to the charging control unit 8 via an interface, and are connected to the high voltage battery ECU 13 via a communication interface. The high voltage battery ECU 13 and the charge control unit 8 communicate with each other to control the charge state of the high voltage battery 1.

  The charging control unit 8 detects the switch ON of the start switch 5, controls the opening and closing of the relay 6 and the relay 10, and monitors the charging state of the high voltage battery 1, and quickly charges the battery when an abnormality is detected. finish.

  The high voltage battery ECU 13 manages the charge / discharge state of the high voltage battery 1, and determines whether or not charging is possible when charging from the external low voltage power source 2, and the determination result is a communication interface. Is transmitted to the charging control unit 8.

  Although not shown, the high voltage battery ECU 13 includes a voltage sensor that measures the voltage of the high voltage battery 1 and a current sensor that measures the current of the high voltage battery 1.

  Further, the high voltage battery ECU 13 receives the engine rotation speed Ne from the crank angle sensor 14 and the engine water temperature Tw from the water temperature sensor 15 in order to monitor the operating state of the engine 22.

  Except for charging the high-voltage battery 1 from the low-voltage power supply 2 from the outside, the relay contact of the relay 10 is opened, the high-voltage battery 1 and the charging device 9 are disconnected, and the motor 24 and the like from the high-voltage battery 1 Electric power is supplied to the electrical load 12. Further, the charge amount of the high voltage battery 1 is managed by the high voltage battery ECU 13 so that the charged amount is within a certain range.

  With the configuration described above, when the driving state of the vehicle reaches a predetermined state, the vehicle controller 32 drives the generator 23 to crank the engine 22 and start the engine 22.

  FIG. 3 is a flowchart showing an example of processing performed by the high voltage battery ECU 13 and is executed when the engine 22 is cranked.

  In S301, the discharge state of the high voltage battery 1 at the start of cranking is detected. As the discharge state, the current and voltage flowing in the high voltage battery 1 are detected by current sensors and voltage sensors provided in the high voltage battery ECU 13, respectively, and the storage state (SOC) is estimated, and within a predetermined time from the start of cranking. The current, voltage, and SOC data are stored in a storage device (such as a memory) (not shown) of the high voltage battery ECU 13.

  In S302, it is determined whether or not the engine 22 has been started after cranking. The engine 22 is started by determining whether the engine speed has exceeded a predetermined target idling speed after a predetermined time from the start of cranking, the duration of operation at an idling speed or higher, and powering the engine. In response to the fact that the motor that has cranked the engine absorbs the engine torque and regenerates, it is determined that the start of the engine 22 has been completed. If the start of the engine 22 is not completed, the process proceeds to S303, and if the start of the engine 22 is completed, the process is terminated without performing the charging process.

  If it is determined in S302 that the engine cannot be started, it is determined in S303 whether or not the start switch 5 of the charge control device 9 is ON.

  If it is determined in S303 that the start switch 5 of the charging control device 9 is ON, the internal resistance of the high voltage battery 1 is estimated in S304.

  For estimation of the internal resistance of the high-voltage battery 1, the current, voltage, and SOC data stored in S301 are used.

  FIG. 4 shows an example of transition of each data stored at the time of cranking of the engine 22, data acquisition is started after the processing of the high voltage battery ECU 13 is started, and cranking is started at time t1. Each data until it is determined that the engine cannot be started is stored. The SOC can be obtained by storing a value at the time of the previous vehicle stop and integrating the current as an initial value. As for the open circuit voltage, an open circuit voltage value corresponding to the SOC is obtained in advance by experiments, a table is prepared, and the open circuit voltage can be obtained from the initial value of the SOC by table search.

  The estimated value of the internal resistance R is calculated by the following equation.

ここで、Ｒ［Ω］は内部抵抗、Ｖｏ［Ｖ］は開放電圧、Ｖｔ［Ｖ］は端子電圧、Ｉ［Ａ］は電流を示す。なお、電流Ｉ［Ａ］は放電側を正としている。

Here, R [Ω] is an internal resistance, Vo [V] is an open circuit voltage, Vt [V] is a terminal voltage, and I [A] is a current. The current I [A] is positive on the discharge side.

  When the internal resistance R is estimated during the cranking period, an estimated value is obtained for each sampling period as shown in FIG. 4, but the internal resistance Re [Ω] used for the process is finally an estimated value during the cranking period. Use averaged values.

  In addition, when the current flowing through the high voltage battery 1 is small, the error detected by the current sensor greatly affects the estimation of the internal resistance. Therefore, when a current exceeding a predetermined threshold value (see FIG. 4) flows. By using the estimated average value of the internal resistance, a more accurate value can be obtained.

  In S305, the output and energy required for starting the engine are calculated. Since these values relate to the startability of the engine 22, the values are determined based on the engine startability represented by the water temperature of the engine 22. For each output and energy, obtain the engine water temperature and the maximum output and energy when the engine can be started in advance by experiment, create a table of engine water temperature Tw, maximum output and energy, and calculate the table from the detected engine water temperature Tw. The maximum output and energy can be obtained by searching. The output / energy required for starting the engine is set to a larger value as the engine water temperature Tw is lower.

  In S306, a first voltage V1 [V] that can supply the necessary output and energy obtained in S305 is obtained. What is necessary is just to obtain | require this voltage so that both said required output and energy may be satisfy | filled before reaching the lower limit of the usable voltage range of the high voltage battery 1.

  In S307, a second voltage V2 [V] that can satisfy the first voltage V1 obtained in S306 at the open circuit voltage Vo is obtained. Here, the charging current Ic [A] to the charging control device 9 can be set to an appropriate value and obtained by the following equation.

また、この第２の電圧はＶ２［Ｖ］は、高電圧バッテリ１の使用可能範囲の上限値とセレクトローすることとし、第１の電圧Ｖ１を開放電圧Ｖｏにおいて満たすことが可能な第２の電圧Ｖ２と高電圧バッテリ１の使用可能範囲の上限電圧のうち、低い方を第２の電圧とする。これにより、充電電圧が過大になるのを防いで高電圧バッテリ１の過充電を防止する。

The second voltage V2 [V] is selected to be low with the upper limit of the usable range of the high voltage battery 1, and the second voltage that can satisfy the first voltage V1 at the open voltage Vo. Of the upper limit voltage of the usable range of the voltage V2 and the high voltage battery 1, the lower one is set as the second voltage. As a result, the charging voltage is prevented from becoming excessive, and overcharging of the high voltage battery 1 is prevented.

  In S308, it is determined whether or not charging from the external low-voltage power supply 2 is possible. Here, it is only necessary to determine that charging is possible in response to the normal operation of the charging control device 9 and the fact that the high voltage battery ECU 13 that monitors the high voltage battery 1 has not failed. . In addition, it is assumed that the external low voltage power source 2 is connected to the charging control device 9 via the connector 41.

  If it is determined that charging is possible in S308, the charging control device 9 is operated in S309 to start charging the high-voltage battery 1 from the external low-voltage power source 2.

  On the other hand, if it is determined in S308 that charging is not possible, the charging process is terminated.

  In S310, it is determined whether or not the voltage of the high voltage battery 1 detected by the voltage sensor is equal to or higher than the second voltage V2. When it is determined that the detected voltage is equal to or higher than the second voltage V2, the charging control device 9 opens the relay 6 and the relay 10 and ends the charging process.

  When it is determined that the detected voltage is less than the second voltage V2, the process returns to S308 and the charging process is continued.

  With the above processing, the internal resistance R is estimated from the discharge state of the high-voltage battery 1 during cranking when the engine cannot be started, and the output / output required for starting the engine 22 based on the estimated internal resistance R. A second voltage V2 that can supply energy is calculated. When charging the high voltage battery 1 from the low voltage power supply 2 outside the host vehicle, the charging is performed up to the second voltage V2, so that the charging time is shortened compared to the conventional example, and the next engine It is possible to reliably start the engine.

  In addition, the internal resistance R of the high-voltage battery 1 during cranking can be estimated by using the detected value of the current and voltage flowing through the high-voltage battery 1 and the estimated SOC as the discharge state during cranking. .

  Moreover, since the estimation of the internal resistance R is performed when the value of the current flowing through the high voltage battery 1 is greater than or equal to a predetermined value, it is possible to suppress the deterioration of the estimation accuracy of the internal resistance caused by the detection error of the current sensor. Therefore, the second voltage V2, which is a voltage that enables the engine to be started, can be accurately calculated, and the next engine start can be completed with certainty.

  The output and energy required for starting the engine are calculated based on the engine water temperature. The lower the water temperature, the greater the output and energy required. For this reason, since the second voltage can be calculated in consideration of deterioration of startability when the engine is cold, the next engine start can be completed with certainty.

  Further, when the second voltage V2 exceeds the upper limit value of the usable voltage range in the high voltage battery 1, the second voltage V2 is set to the upper limit value of the usable voltage range. Charging can be prevented.

  In addition, when the second voltage V2 exceeds the upper limit value of the usable voltage range in the high voltage battery 1, a warning indicator 16 (see FIG. 2) for urging the driver to warn may be provided. With this operation, it is possible to indicate to the driver that the possibility that the engine can be started by charging the high voltage battery 1 is low. The warning is not limited to display, and the warning may be notified by voice or vibration.

  In the above embodiment, the control of FIG. 3 is performed by the high voltage battery ECU 13, but may be performed by the charge control unit device 9.

  As described above, in the charging device according to the present invention, the high-voltage battery can be charged quickly up to the charge amount that allows the engine to be started, and thus can be applied to a hybrid vehicle.

The block diagram of the drive system which shows embodiment of this invention. The block diagram of a power supply device similarly. The flowchart which shows an example of the process performed by high voltage battery ECU. The graph which shows the voltage of the high voltage battery during a cranking period, electric current, SOC, an internal resistance estimated value, and the relationship of time.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 High voltage battery 2 External low voltage power supply 9 Charge control apparatus 13 High voltage battery ECU

Claims (6)

It has an electric motor that starts the engine with a high-voltage battery, and can charge the high-voltage battery with electric power from a low-voltage power supply outside the host vehicle in case the engine cannot be started due to discharge of the high-voltage battery In a charging device for a hybrid vehicle,
An internal resistance estimating means for estimating the internal resistance of the high-voltage battery from the discharge state of the high-voltage battery at the time of cranking when the engine cannot be started;
Required output / energy calculating means for calculating output and energy required for starting the engine;
First voltage calculating means for obtaining a first voltage capable of securing the required output and energy;
Second voltage calculating means for calculating a second voltage that satisfies the first voltage in the open voltage of the high-voltage battery;
Charging means for charging from a low voltage power source until the high voltage battery is at a second voltage;
A charging device for a hybrid vehicle, comprising:   2. The hybrid vehicle charging device according to claim 1, wherein the internal resistance estimating unit estimates the internal resistance based on a current flowing through a high-voltage battery, a voltage, and a state of charge.   3. The hybrid vehicle charging device according to claim 1, wherein the internal resistance estimating unit estimates an internal resistance when a current flowing through the high-voltage battery is equal to or greater than a predetermined value. 4.   The charging of the hybrid vehicle according to claim 1, wherein the required output / energy calculating means includes an engine water temperature detecting means for detecting an engine water temperature, and the required output / energy is increased as the engine water temperature is lower. apparatus.   When the second voltage that satisfies the first voltage in the open voltage of the high-voltage battery exceeds a predetermined upper limit of the usable voltage range in the high-voltage battery, the second voltage calculation means 5. The hybrid vehicle charging device according to claim 1, wherein an upper limit value of the usable voltage range is a second voltage. 6.   The said 2nd voltage calculation means has a warning means which urges | urges a warning, when the said 2nd voltage exceeds the predetermined | prescribed upper limit of the usable voltage range in a high voltage battery, The warning means which urges | urges a warning is characterized by the above-mentioned. The charging device for a hybrid vehicle according to any one of claims 5 to 6.

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