JP2006109608A - Vehicle power supply device and its control method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To effectively use energy by connecting a charging transistor and a discharging transistor between and among an accumulating battery, an inputting capacitor, and an outputting capacitor that are connected in parallel. <P>SOLUTION: The accumulating battery 11, the inputting capacitor 12, and the outputting capacitor 13 are connected in parallel; an input rectification diode 17 is connected between an inverter 20 and the inputting capacitor 12; an output rectification diode 18 is connected between the inverter 20 and the outputting capacitor 13; the charging transistor 14 is connected between the accumulating battery 11 and the inputting capacitor 12; the discharging transistor 15 is connected between the accumulating battery 11 and the inputting capacitor 13; and a control unit 16 that controls a base current Tbi of the charging transistor 14 and a base current Tbo of the discharging transistor 15 is arranged. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a vehicle power supply device and a control method thereof.

  Hybrid vehicles that use an electric motor as an auxiliary drive source that assists the output of the engine have been commercialized, and secondary batteries are widely used as a power source for driving the electric motor. As shown in Patent Document 1, a vehicle power supply device in which a secondary battery and a capacitor are connected in parallel has been studied in improving the secondary battery. By connecting the secondary battery and the capacitor in parallel, the output of the capacitor at low temperatures can be compensated for by the action of the capacitor, which is superior in low temperature characteristics compared to the case of a single secondary battery, and the input / output characteristics at low temperatures can be improved. I can expect. Also, in the energy regeneration that occurs when the vehicle decelerates, the regenerative braking ability that takes out as electric energy by using the drive motor as a generator and converting it into heat and sound with a disc brake etc. as in the past Will improve. Furthermore, even when instantaneous high output such as engine start or rapid acceleration is required, the power running capability is improved, and the performance degradation due to the temperature rise that is concerned about the battery during electric energy discharge is eliminated, and the power running capability is also improved. improves.

Japanese Patent Laid-Open No. 2003-200249

  However, in such a vehicle power supply device in which a capacitor is connected in parallel to the secondary battery, the tendency for the regenerative input to be influenced by the state of charge (SOC) of the vehicle power supply device is when the secondary battery is alone. There is no particular advantage compared to the region where the state of charge is high, that is, the closer to the fully charged state as a power supply device for a vehicle, the more the voltage changes with respect to the amount of stored electric energy, which is a characteristic of the secondary battery The tendency to become impossible becomes strong. That is, even if capacitors are connected in parallel, this characteristic cannot be improved. As a result, improvement in regenerative input cannot be expected so much, and there is a problem that energy cannot be used efficiently.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a vehicle power supply device that can efficiently use energy and a control method thereof.

  To achieve the above object, in the present invention, a storage battery, an input capacitor and an output capacitor are connected in parallel, and a charging transistor is connected between the storage battery and the input capacitor, A discharge transistor is connected between the output capacitor and a control unit for controlling the base current of the charge transistor and the discharge transistor is provided.

  In the present invention, not only the storage battery, the input capacitor, and the output capacitor are connected in parallel, but also a charging transistor and a discharging transistor are connected between them, so that the input capacitor The voltage and the output capacitor voltage can be controlled by the base current of the charging transistor and the base current of the discharging transistor, and energy can be used efficiently.

  FIG. 1 is a diagram showing a basic configuration of a vehicle power supply device according to the present invention. The vehicle power supply device 10 includes a storage battery 11, an input capacitor 12, an output capacitor 13, a charging transistor 14 using a switching npn transistor, a discharging transistor 15 using a switching npn transistor, a control unit 16, It has an input rectifier diode 17 and an output rectifier diode 18, and supplies power to the drive motor 30 via an inverter (load) 20. The charging transistor 14, the discharging transistor 15, the input rectifier diode 17, and the output rectifier diode 18 are made of a semiconductor using a SiC compound.

  A storage battery 11, an input capacitor 12, and an output capacitor 13 are arranged in parallel. The emitter 14e of the charging transistor 14 is the positive electrode 11a of the storage battery 11, and the collector 14c is the positive electrode 12a of the input capacitor 12. And the cathode 17k of the input rectifier diode 17 and the output of the control unit 16 are connected to the base 14b. Similarly, the storage battery positive electrode 11a is connected to the collector 15c of the discharge transistor 15, the positive electrode 13a of the output capacitor 13 and the anode 18a of the output rectifier diode 18 are connected to the emitter 15e, and the output of the control unit 16 is connected to the base 15b. Each is connected. Further, the anode 17 a of the input rectifier diode 17 and the cathode 18 k of the output rectifier diode 18 are combined to form the positive electrode 10 a of the vehicle power supply device 10. Similarly, the negative electrode 11 b of the storage battery 11, the negative electrode 12 b of the input capacitor 12, and the negative electrode 13 b of the output capacitor 13 are combined to form the negative electrode 10 b of the entire vehicle power supply device 10, and these positive electrode 10 a and negative electrode 10 b are connected to the inverter 20. Is connected to.

  That is, the input rectifier diode 17 is connected between the inverter 20 and the input capacitor 12, the output rectifier diode 18 is connected between the inverter 20 and the output capacitor 13, and the storage battery 11 and the input capacitor 12 A charging transistor 14 is connected between them, and a discharging transistor 15 is connected between the storage battery 11 and the output capacitor 13.

  The control unit 16 has an external regeneration control command, a power running (torque) control command, a storage battery voltage Vb between the positive electrode 11a and the negative electrode 11b of the storage battery 11 detected by voltage detection means (not shown), and an input capacitor. The input capacitor voltage Vci between the positive electrode 12a and the negative electrode 12b of 12 and the output capacitor voltage Vco between the positive electrode 13a and the negative electrode 13b of the output capacitor 13 are input, and the base current Tbi of the charging transistor 14 and the discharging transistor 15 This is a control means for controlling the base current Tbo.

  The battery voltage Vb for storage, the capacitor voltage Vci for input, and the capacitor voltage Vco for output must be Vb = Vci = Vco in the case of normal parallel connection, but the vehicle power source of the present embodiment shown in FIG. In the apparatus, a charging transistor 14 is connected between the storage battery 11 and the input capacitor 12, and a discharging transistor 15 is connected between the storage battery 11 and the output capacitor 13. Yes. For this reason, if the base current Tbi of the charging transistor 14 is turned off, the storage battery 11 and the input capacitor 12 are electrically disconnected, and the base current Tbo of the discharging transistor 15 is turned off. By doing so, the state between the storage battery 11 and the output capacitor 13 is equivalent to the electrically disconnected state, and the input capacitor voltage Vci and the output capacitor voltage Vco can be controlled independently.

  Further, by providing the input rectifier diode 17 between the inverter 20 and the input capacitor 12, and providing the output rectifier diode 18 between the inverter 20 and the output capacitor 13, the regenerative current from the inverter 20 is always input capacitor. The power running current to the inverter 20 is always supplied from the output capacitor 13. Therefore, regardless of the storage battery voltage Vb, the input capacitor voltage Vci is always equivalent to 0% except when regenerative power is input, and at the same time, the output capacitor voltage Vco is always charged except when powering power is output. If the base current Tbi of the charging transistor 14 and the base current Tbo of the discharging transistor 15 are controlled by the control unit 16 so that the state ≈100%, the vehicle power supply device 10 can always perform regenerative control / maximum output. Power running control. Theoretically, the maximum efficiency electric energy management in the vehicle power supply device 10 is possible.

  Next, the operation of the vehicle power supply device shown in FIG. 1, that is, the control method of the vehicle power supply device will be described with reference to FIGS. These arithmetic processes are executed, for example, by a timer interrupt every predetermined control time ΔT. In these flowcharts, steps such as data storage and program reading are not particularly provided, but these steps are performed as needed.

  The overall control logic of the vehicle power supply device 10 is shown in FIG. First, in step S1, the control unit 16 reads the control command (specifically, “powering control / regenerative control” command) from the inverter 20, the storage battery voltage Vb, the input capacitor voltage Vci, and the output capacitor voltage Vco. If it is determined in step S2 that the command from the load 20 such as an inverter is “powering control”, the process proceeds to S20 to perform powering control processing (described later in FIG. 3). If not, the process proceeds to step S3. If the command is determined to be “regenerative control”, the process proceeds to S30 to perform a regenerative control process (described later in FIG. 4). If none of the “power running control / regenerative control” corresponds, that is, if no appropriate instruction is issued from the inverter 20, the process proceeds to step S4.

  Downstream from step S4, the base current Tbi of the charging transistor 14 and the base current Tbo of the discharging transistor 15 are controlled by the storage battery voltage Vb of the vehicle power supply device 10 according to the present invention. That is, in step S4, the power storage battery voltage Vb is compared with the output capacitor voltage Vco. If Vb ≧ Vco, it is necessary to supply electric energy to the output capacitor 13 in preparation for a power running control command from the inverter 20. Therefore, in steps S41 to S42, the base current Tbi of the charging transistor 14 is turned off in advance, the conductive relationship between the storage battery 11 and the input capacitor 12 is cut off, and the base of the discharging transistor 15 is cut in step S43. The current Tbo is turned on to connect the storage battery 11 and the output capacitor 13 in parallel. Thus, charging from the storage battery 11 to the output capacitor 13, that is, supply of electric energy is performed.

  If Vb <Vco in step S4, that is, if it is determined that it is not necessary to supply electrical energy to the output capacitor 13, the process proceeds to step S5. In step S5, the power storage battery voltage Vb is compared with the input capacitor voltage Vci. If Vb ≦ Vci, it can be determined that electrical energy sufficient to charge the storage battery 11 is stored in the input capacitor 12, and in preparation for a regeneration control command from the inverter 20, the input capacitor 12 Therefore, it is necessary to prepare a storage allowance for electric energy by reducing the voltage Vci as much as possible.

  Therefore, in steps S51 to S52, the base current Tbo of the discharge transistor 15 is turned off in advance to cut off the conductive relationship between the battery 11 for storage and the output capacitor 13, and in step S53, the charge transistor 14 The base current Tbi is turned on to connect the storage battery 11 and the input capacitor 12 in parallel. Thereby, charging from the input capacitor 12 to the battery 11 for storage, that is, supply of electric energy is performed.

  When it is determined in steps S4 and S5 that it is not necessary to transfer electrical energy between the storage battery 11, the input capacitor 12, and the output capacitor 13 (specifically, a voltage state of Vco> Vb> Vci). In step S6, the base currents Tbi and Tbo of the charging transistor 14 and the discharging transistor 15 are turned off, and the output capacitor voltage Vco is sufficiently increased in response to the power running control command from the inverter 20. For the regenerative control command, a storage allowance for electrical energy is prepared in a state where the input capacitor voltage Vci is sufficiently lowered, and the response is performed with good response.

  Next, FIG. 3 shows the power running control processing logic when it is determined as “power running control” in step S2. In step S21, the storage battery charge state (storage battery SOC) is calculated from the storage battery voltage Vb read in step S1 in FIG. Similarly, the output capacitor charge state (output capacitor SOC) is calculated from the output capacitor voltage Vco. Next, depending on whether or not the output capacitor charge state exceeds a preset threshold value Smin in step S22, the power running control command can be handled with the electric energy of only the output capacitor 13 or the electricity of the battery 11 for storage Judge whether to use energy.

  That is, if the output capacitor charge state exceeds the threshold value Smin, the process proceeds to step S221, and the base current Tbo of the discharge transistor 15 is turned off to cut off the conductive relationship between the output capacitor 13 and the storage battery 11. The output capacitor 13 alone corresponds to the power running control command.

  The merit when dealing with the output capacitor 13 alone is that a large amount of electric power can be taken out, so that a driving power with excellent acceleration can be obtained as a vehicle power supply device. However, since the amount of electrical energy stored in the output capacitor 13 is inferior to that of the storage battery 11, there is a demerit that the acceleration state (power running control) does not continue for a long time.

  When the charging state of the output capacitor 13 is lower than the threshold value Smin, it is determined that the electric energy necessary for the powering control command cannot be supplied by the output capacitor 13 alone, and the process proceeds to S23, and the charging state of the storage battery is not 0% In steps S231 to S232, the base current Tbi of the charging transistor 14 between the input-side capacitor 12 and the storage battery 11 is turned off to cut off the conductive relationship between them, and then the storage battery 11 and the output battery 11 The base current Tbi of the discharging transistor 15 between the capacitors 13 is turned on and connected in parallel (step S233), and the power storage battery 11 responds to the powering control command. By using the storage battery 11, a sufficient amount of electric energy can be secured compared to the case where the output capacitor 13 alone is used, but depending on the state of charge of the storage battery, it can cope with input / output of large power. Because there is no, there is a possibility that acceleration performance becomes dull. Therefore, when this control occurs, it is considered that it is necessary for the vehicle power supply device 10 to request the inverter 20 to limit the output. The specific value of the threshold value Smin largely depends on the design of the vehicular power supply apparatus 10, but it is appropriate to set it within a range of 0 to 50% as a guide.

  Incidentally, if it is determined in step S23 that the state of charge of the battery for storage is 0%, the process proceeds to step S24. That is, it means that the electric energy in the vehicle power supply device 10 is completely depleted, and therefore the power running operation is stopped.

  Next, FIG. 4 shows the regeneration control processing logic when it is determined that “regenerative control” in step S3. In step S31, the storage battery charge state is calculated from the storage battery voltage Vb read in step S1 in FIG. 2, and the input capacitor charge state (input capacitor SOC) is similarly calculated from the input capacitor voltage Vci. To do. Next, in step S32, it is compared whether or not the charging state of the input capacitor is 100%, and the regenerative control command corresponds to the electric energy storage cost of the input capacitor 12 alone, or the electric energy is stored in the battery 11 for storage. Judge whether to save.

  If the charging state of the input capacitor is not 100%, the base capacitor Tbi of the charging transistor 14 is turned off in step S321 to cut off the conductive relationship between the input capacitor 12 and the storage battery 11, and the input capacitor 12 Corresponds to the regenerative control command alone. The merit of dealing with the input capacitor 12 alone is that large regenerative power can be input, so that the energy generated during deceleration as a vehicle power supply device can be efficiently (minimum need to convert to heat and sound as in the past). Although it can be recovered as electric energy (in a limited state), the amount of electric energy stored in the input capacitor 12 is inferior to that of the storage battery 11, so that there is a demerit that it does not last long.

  Therefore, when the charging state of the input capacitor reaches 100%, it is determined that the electric energy obtained by regeneration cannot be taken by the input capacitor 12 alone, and the charging state of the storage battery 11 is 100% in S33. In Steps S331 to S332, the base current Tbo of the discharge transistor 15 between the output-side capacitor 13 and the storage battery 11 is turned off to cut off their conductive relationship, and then the storage battery 11 and the input are input. The base current Tbi of the charging transistor 14 between the capacitors for charging 12 is turned on and connected in parallel (step S333), and the regenerative control command is handled by the battery 11 for storage. By using the storage battery 11, it is possible to secure a sufficient storage amount of electric energy compared to the case where the above-described input capacitor 12 is handled alone, but the storage battery 11 supports high power input / output. Since it cannot be exhausted, the amount recoverable as electric energy out of the energy generated when the vehicle decelerates decreases, that is, the conversion efficiency into electric energy becomes dull. Therefore, when falling into this control, it is assumed that a brake that converts heat and sound as in the conventional case is also used.

  Incidentally, if it is determined in step S33 that the state of charge of the battery for storage is 100%, it means that the electric energy in the vehicle power supply device in the vehicle is in a fully charged state. Accordingly, the regenerative operation is stopped.

  In addition, the battery 11 for electrical storage in this invention means the energy type power supply device represented by the lithium ion secondary battery, for example. Therefore, devices that can be charged and discharged and can store a relatively large amount of electrical energy, such as nickel-hydrogen secondary batteries and lead-acid batteries, fall under this category.

  Furthermore, the “capacitor” in the present embodiment means a power type power supply device that is excellent in charge and discharge efficiency and durability, and that can input and output with high power, represented by an electric double layer capacitor, for example. Therefore, devices developed for the purpose of electrolytic capacitors and similar applications in the future shall fall under this category. In the present embodiment, the control unit 16 has been described on the assumption that it is composed of a microcomputer, but various arithmetic circuits may be combined.

  As described above, in the present embodiment, not only the storage battery 11, the input capacitor 12, and the output capacitor 13 are connected in parallel, but also a charging transistor that is a switching transistor between them. 14 and the discharging transistor 15 are connected, so that the input capacitor voltage Vci and the output capacitor voltage Vco are converted into the base current Tbi of the charging transistor 14 and the discharging transistor 15 while being in a parallel configuration in terms of wiring. By independently controlling with the base current Tbo, it is possible to transfer large input / large output electric energy to the drive motor 30 via the inverter 20, and the electric energy can be used efficiently. .

  The input capacitor 12 is set for electric energy input (specifically, receiving regenerative power from the drive motor), and the output capacitor 13 is set for electric energy output (specifically, powering power supply to the drive motor). Therefore, in addition to being able to simplify the voltage management from the storage battery 11 for the capacitors 12 and 13, for example, a congestion in which frequent regenerative control and power running control are expected to be repeated due to stop & go, for example. Even in a scene or the like, electric energy can be used efficiently.

  Further, the control unit 16 switches these transistors 14 and 15 by ON / OFF output to the base current Tbi of the charging transistor 14 and the base current Tbo of the discharging transistor 15. In this case, the control unit 16 switches from the inverter 20. By inputting the control state of regenerative control / power running control from the control signal and switching with a predetermined control logic, the input / output control of the vehicle power supply device 10 can be performed with good efficiency in accordance with the purpose. Further, by referring to the storage battery voltage Vb (stored electric energy) information, it is possible to grasp the margin of powering control / regenerative control in the input capacitor 12 and the output capacitor 13 in terms of electric energy. Therefore, the charging transistor 14 connected between the storage battery 11 and the input capacitor 12 and the discharging transistor 15 connected between the storage battery 11 and the output capacitor 13 provide a more precise voltage (electric energy). ) Management is possible.

  In addition, since the charging transistor 14, the discharging transistor 15, the input rectifier diode 17, and the output rectifier diode 18 are made of a SiC compound semiconductor, switching at a high voltage and high current as in the vehicle power supply device 10 is performed. (ON / OFF) and rectification can be supported.

It is a basic lineblock diagram of the power supply device for vehicles in the present invention. It is a flowchart which shows the whole control logic performed with a control unit. It is a flowchart which shows a power running control process. It is a flowchart which shows a regeneration control process.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Vehicle power supply device 11 ... Battery for electric storage 12 ... Input capacitor 13 ... Output capacitor 14 ... Charging transistor 15 ... Discharge transistor 16 ... Control unit 17 ... Input rectifier diode 18 ... Output rectifier diode 20 ... Inverter 30 ... Drive motor

Claims (13)

  A storage battery, an input capacitor and an output capacitor are connected in parallel, an input rectifier diode is connected between the load and the input capacitor, and an output rectifier diode is connected between the load and the output capacitor. A charging transistor is connected between the storage battery and the input capacitor, a discharge transistor is connected between the storage battery and the output capacitor, and the charging transistor and the discharging transistor are connected. A vehicle power supply apparatus comprising a control unit for controlling a base current of a transistor.   The collector of the charging transistor is connected to the cathode of the input rectifier diode and the positive electrode of the input capacitor, the emitter of the charging transistor is connected to the positive electrode of the storage battery, and the collector of the discharging transistor is connected to the storage battery. 2. The vehicle power supply device according to claim 1, wherein the vehicle power supply device is connected to a positive electrode of a battery, and an emitter of the discharge transistor is connected to an anode of the output rectifier diode and a positive electrode of the output capacitor.   The control unit sets the base current of the charging transistor and the discharging transistor according to the storage battery voltage of the storage battery, the input capacitor voltage of the input capacitor, and the output capacitor voltage of the output capacitor. The vehicle power supply device according to claim 1, wherein the vehicle power supply device is controlled.   When the control unit is not instructed for power running control and regenerative control from the load, when the storage battery voltage is equal to or lower than the input capacitor voltage, the control unit turns off the base current of the discharge transistor, and 4. The vehicle power supply device according to claim 3, wherein a base current of the charging transistor is turned on.   When the control unit is not instructed for power running control and regenerative control from the load, when the battery voltage for power storage is equal to or higher than the output capacitor voltage, the base current of the charging transistor is turned off, and 5. The vehicle power supply device according to claim 4, wherein a base current of the discharge transistor is turned on.   The control unit calculates an output capacitor charge state from the output capacitor voltage, and when the command from the load is power running control, the output capacitor charge state is set to a predetermined minimum output capacitor charge state. When exceeding, the base current of the discharging transistor is turned off, and when the output capacitor charging state is equal to or less than the minimum output capacitor charging state, the charging transistor base current is turned off, and the discharging transistor 4. The vehicle power supply device according to claim 3, wherein the base current is turned on.   The control unit calculates the charge state of the input capacitor from the input capacitor voltage, and when the command from the load is regenerative control and the charge state of the input capacitor is not 100%, the base of the charge transistor The current is turned off, and when the charge state of the input capacitor is 100%, the base current of the discharge transistor is turned off, and the base current of the charge transistor is turned on. The power supply device for vehicles as described.   2. The vehicle power supply device according to claim 1, wherein the charge transistor, the discharge transistor, the input rectifier diode, and the output rectifier diode are made of a SiC compound semiconductor.   2. The vehicle power supply device control method for controlling a vehicle power supply device according to claim 1, wherein the control unit causes the storage battery voltage of the storage battery, the input capacitor voltage of the input capacitor and the output capacitor to be controlled. A control method for a vehicle power supply apparatus, comprising: controlling base currents of the charging transistor and the discharging transistor according to a capacitor voltage for output of the capacitor.   When the control unit does not command power running control and regenerative control from the load, when the battery voltage for power storage is equal to or lower than the input capacitor voltage, the base current of the discharging transistor is turned off, and The method for controlling a vehicle power supply device according to claim 9, wherein a base current of the charging transistor is turned on.   When the control unit does not command power running control and regenerative control from the load, when the battery voltage for power storage is equal to or higher than the output capacitor voltage, the base current of the charging transistor is turned off, and The method for controlling a vehicle power supply device according to claim 10, wherein the base current of the discharging transistor is turned on.   The control unit calculates an output capacitor charge state from the output capacitor voltage, and when the command from the load is power running control, the output capacitor charge state is set to a predetermined minimum output capacitor charge state. When exceeding, the base current of the discharging transistor is turned off, and when the output capacitor charging state is equal to or less than the minimum output capacitor charging state, the charging transistor base current is turned off, and the discharging transistor The control method for a vehicle power supply device according to claim 9, wherein the base current is turned on.   The control unit calculates an input capacitor charge state from the input capacitor voltage. When the command from the load is regenerative control, and the input capacitor charge state is not 100%, the base of the charge transistor is calculated. 10. The method according to claim 9, wherein when the current is turned off and the charging state of the input capacitor is 100%, the base current of the discharging transistor is turned off and the base current of the charging transistor is turned on. The control method of the vehicle power supply device described.

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