JP2006254610A - Vehicle controller - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To shorten a time until a vehicle comes to be able to run by always making a voltage value of a capacitor not less than that of a fuel cell, and by enabling the fuel cell to be connected to the capacitor immediately after the start of a vehicle system when the vehicle system is started in a vehicle controller. <P>SOLUTION: A control means includes a voltage maintenance control unit that compares a capacitor voltage with a fuel cell one while the vehicle is in a stop state; and performs the control of enabling the capacitor voltage to be maintained at a level more than the fuel cell voltage while the fuel cell, the capacitor, and a motor can be controlled with the vehicle system started, in a state that the vehicle is stopped, and in a state that the electric power of the fuel cell cannot be supplied at least to the motor. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a vehicle control device, and can connect a fuel cell (fuel cell stack) and a capacitor (electric double layer capacitor) at the time of start-up of a vehicle system without mounting a new current control device. The present invention relates to a vehicle control device.

  Vehicles include fuel cell vehicles equipped with fuel cells (fuel cell stacks). This fuel cell vehicle is equipped with a power storage device such as a secondary battery or a capacitor (electric double layer capacitor) in order to improve the overall efficiency of the vehicle or to complement the load response characteristics of the fuel cell. A hybrid system is used. In particular, capacitors are not accompanied by chemical changes like secondary batteries in charge and discharge, so generally they have a long life and high output density, and also follow the output voltage of the fuel cell well. There are many advantages such as not requiring a voltage adjusting device such as a large DC / DC converter.

Conventionally, a vehicle control device equipped with a fuel cell and a capacitor detects a capacitor voltage, compares the detected capacitor voltage with a plurality of set reference voltages, and controls the operation of the auxiliary device. There is.
In addition, in a vehicle control device equipped with a fuel cell and a capacitor, when the vehicle is in an idle operation state, power generation of the fuel cell is stopped, or the fuel cell is operated in an operation region where the power generation efficiency is higher than the normal operation region. And there are things that generate electricity.
JP2004-14159 JP-A-2004-56868

  Conventionally, in a fuel cell vehicle equipped with a fuel cell and a capacitor, the fuel cell and the capacitor are generally electrically disconnected from the high voltage system by respective relays when the vehicle system is stopped. For this reason, when starting the vehicle system, if the capacitor voltage is significantly lower than the fuel cell voltage, an overcurrent is generated from the fuel cell to the capacitor at the moment when each relay is connected, and the components of the high voltage system As a result, the vehicle system was stopped or the fuel cell was deteriorated because the fuel cell voltage suddenly decreased.

  In order to avoid such problems, a switching regulator, a DC / DC chopper, a control resistor, etc. interposed between the fuel cell and the capacitor before connecting the fuel cell and the capacitor with a relay or the like have been conventionally used. The current control device charges the capacitor while limiting the current value from the fuel cell to the capacitor.

  However, in this case, it is generally necessary to provide a large and high-cost current control device, and therefore, the great merit of the capacitor, that is, unlike the case of the secondary battery, follows the value of the fuel cell voltage very well. Therefore, there is a disadvantage that the characteristic that a large voltage regulator is not required is offset.

  The present invention provides an auxiliary storage battery for driving an auxiliary machine for a vehicle in a vehicle control device including a motor for driving the vehicle, a fuel cell connected in parallel to the motor, and a capacitor. In a state in which the vehicle system is activated to control the fuel cell, the capacitor, and the motor, the vehicle is stopped, and at least the power of the fuel cell cannot be supplied to the motor. A control means provided with a voltage maintenance control unit that compares the capacitor voltage with the fuel cell voltage when the fuel cell is stopped and controls the capacitor voltage to maintain a value equal to or higher than the fuel cell voltage. Features.

  The vehicle control device according to the present invention is in a state where the vehicle system is activated to control the fuel cell, the capacitor, and the motor, and the vehicle is stopped, and at least the power of the fuel cell cannot be supplied to the motor. Then, the capacitor voltage is compared with the fuel cell voltage when the vehicle is stopped, and the capacitor voltage maintains a value that is equal to or higher than the fuel cell voltage. Since the fuel cell voltage does not fall below the value of the fuel cell voltage, the fuel cell and the capacitor can be connected immediately after the vehicle system is started, and the time until the vehicle can run can be shortened.

The present invention achieves the purpose of shortening the time until the vehicle can travel by allowing the capacitor voltage to maintain a value equal to or higher than the fuel cell voltage when the vehicle is stopped.
Hereinafter, embodiments of the present invention will be described in detail and specifically with reference to the drawings.

  1 to 3 show a first embodiment of the present invention.

  In FIG. 3, 2 is a control device for a vehicle of a fuel cell vehicle (hereinafter referred to as “vehicle”) (not shown), 4 is a fuel cell (fuel cell stack) mounted on the vehicle, 6 is an inverter, and 8 is a vehicle drive. Motor.

  The fuel cell 4 is configured to generate power upon receipt of fuel (gas) and oxidant. The inverter 6 converts the DC power generated by the fuel cell 4 into three-phase AC power and supplies the three-phase AC power to the motor 8. The motor 8 is driven by electric power supplied from the inverter 6.

  The fuel cell 4 and the inverter 6 are connected by the first and second main electric wires 10 and 12.

  The first and second main electric wires 10 and 12 are provided with a first relay (fuel cell relay) 14 on the fuel cell 4 side. The first relay 14 has a function of disconnecting the fuel cell 4 from the high voltage system by opening.

  In addition, a first voltmeter 16 is connected to the first and second main electric wires 10 and 12 between the fuel cell 4 and the first relay 14. The first voltmeter 16 has one end connected to the first one-side connecting portion 18 of the first main electric wire 10 and the other end connected to the first other-side connecting portion 20 of the second main electric wire 12, The voltage between the terminals of the battery 4 is measured.

  The first main electric wire 10 is provided with a backflow prevention diode 22 on the inverter 6 side of the first relay 14. This backflow prevention diode 22 prevents backflow of current to the fuel cell 4.

  In the middle of the first and second main electric wires 10 and 12, a capacitor (electric double layer capacitor) 28 is connected in parallel with the fuel cell 4 by the first and second sub electric wires 24 and 26. The first sub electric wire 24 is connected to the first main electric wire 10 at the first connecting portion 30 closer to the inverter 6 than the backflow prevention diode 22. The second sub electric wire 26 is connected to the second main electric wire 12 at the second connecting portion 32 closer to the inverter 6 than the first relay 14. Therefore, the fuel cell 4 and the capacitor 28 are provided in parallel to the motor 8.

  The capacitor 28 assists power supply to the inverter 6 and receives power generated by the fuel cell 4 and regenerative power from the inverter 6 when the vehicle is decelerated. Further, the capacitor 28 is generally superior in load responsiveness as compared with the fuel cell 4, and therefore responds very well to the load demand of the vehicle. Since this is accompanied by a change, it follows the change in the output voltage of the fuel cell 4 well.

  A second relay (capacitor relay) 34 is provided in the middle of the first and second sub wires 24 and 26. The second relay 34 has a function of disconnecting the capacitor 28 from the high voltage system by opening.

  The first and second sub wires 24 and 26 are provided with a second voltmeter 36 connected between the capacitor 28 and the second relay 34. The second voltmeter 36 has one end connected to the second one-side connecting portion 38 of the first sub-wire 24 and the other end connected to the second other-side connecting portion 40 of the second sub-wire 22, The voltage between 28 terminals is measured.

  Further, the first and second main electric wires 10 and 12 are connected to the fuel cell 4 and the capacitor 28 in parallel, and a high voltage composed of a plurality of high voltage auxiliary machines by the third and fourth sub electric wires 42 and 44 of the high voltage system. Auxiliary equipment 46 is connected and provided. The third sub electric wire 42 is connected to the first main electric wire 10 at the third connecting portion 48 closer to the inverter 6 than the first connecting portion 30. The fourth sub electric wire 44 is connected to the second main electric wire 12 at the fourth connecting portion 50 closer to the inverter 6 than the second connecting portion 32. The high voltage auxiliary machinery 46 is for operating a fuel cell system (not shown) including the fuel cell 4.

  Further, the first and second main electric wires 10 and 12 are connected to the fuel cell 4 and the capacitor 28 in parallel, and are used to drive auxiliary equipment, which is a storage battery for auxiliary equipment by the fifth and sixth sub electric wires 52 and 54 of the high voltage system. A battery (auxiliary battery) 56 is connected and provided. The fifth sub electric wire 52 is connected to the first main electric wire 10 at the fifth connecting portion 58 closer to the inverter 6 than the third connecting portion 48. The sixth sub electric wire 54 is connected to the second main electric wire 12 at the sixth connecting portion 60 closer to the inverter 6 than the fourth connecting portion 44.

  A bidirectional DC / DC converter 62 is provided in the middle of the fifth and sixth sub wires 52 and 54.

  Further, the fifth and sixth sub electric wires 52 and 54 are connected to the vehicle auxiliary machinery by the seventh and eighth sub electric wires 64 and 66 between the bidirectional DC / DC converter 62 and the auxiliary device driving battery 56. 68 is connected. The seventh sub electric wire 64 is connected to the fifth sub electric wire 52 at the seventh connecting portion 70. The eighth sub electric wire 66 is connected to the sixth sub electric wire 54 at the eighth connection portion 72.

  The auxiliary machine driving battery 56 supplies electric power for driving the vehicle auxiliary machines 68.

  Further, the bidirectional DC / DC converter 62 converts the power from the fuel cell 4 and the capacitor 28 or the voltage of the regenerative power from the inverter 6 into a voltage for driving the vehicle auxiliary equipment 68, On the contrary, the voltage for driving the vehicle auxiliary machinery 68 is converted into a voltage for driving the high voltage auxiliary machinery 46 or supplementing the capacitor 24. The bidirectional DC / DC converter 62 is not limited to the bidirectional type, and although not shown, it is possible to provide both a step-up DC / DC converter and a step-down DC / DC converter in parallel. It is.

  Further, the vehicle auxiliary devices 68 are connected to the low voltage side of the bidirectional DC / DC converter 62, and include various vehicle auxiliary devices such as a headlamp, a radio, and a water pump.

  Fuel cell 4, inverter 6, first relay 14, first voltmeter 16, capacitor 28, second relay 34, second voltmeter 36, high voltage auxiliary machine 46, auxiliary machine driving battery 56, and bidirectional DC The / DC converter 62 and the vehicle auxiliary devices 68 are connected to the control means 74.

  This control means 74 controls the vehicle system (not shown) based on the information collected from each sensor and the data stored in the internal memory 74A. When the capacitor 28 and the motor 8 are controllable and the vehicle is stopped, and the power of the fuel cell 4 cannot be supplied to at least the motor 8 (the first relay 14 is open), the vehicle is stopped. A voltage maintenance control unit 74B is provided for comparing the capacitor voltage Vcap (V) and the fuel cell voltage (V) in a running state and controlling the capacitor voltage to maintain a value equal to or higher than the fuel cell voltage.

  Further, the control means 74 controls charging of the capacitor 28 by an auxiliary machine driving battery 56 which is an auxiliary machine storage battery.

  Generally, in a fuel cell vehicle equipped with a fuel cell and a capacitor, a plurality of capacitor single cells having a maximum voltage of about 2.5V to 3.5V are connected in series, for example, a capacitor module having a maximum voltage of about 200V to 400V. Is configured. On the other hand, a general fuel cell used for a fuel cell vehicle has a single cell with an open circuit voltage of about 1.0 V, an idle voltage of about 0.9 V when the vehicle is idling, and a voltage of about 0.6 V at the maximum load. A fuel cell stack is configured by connecting a plurality of the above in series. That is, as an example, a 300-cell fuel cell has an open circuit voltage of about 300V, an idle voltage of about 270V, and a minimum voltage of about 180V.

  Therefore, the capacitor 28 in the first embodiment has a maximum voltage higher than the idle voltage of the fuel cell 4. In the above example, that is, when the 300-cell fuel cell 4 is employed, the maximum voltage of the capacitor 28 is set to 270 V or higher, which is higher than the idle voltage as the fuel cell voltage. This is effective to prevent an overcurrent from the fuel cell 4 to the capacitor 28 when the fuel cell 4 and the capacitor 28 that are electrically disconnected from each other are connected when the vehicle system is started. .

  That is, the fuel cell voltage when the vehicle system is activated is an idle voltage. When the capacitor voltage is lower than the idle voltage, a current is generated from the fuel cell toward the capacitor. Since this current value is basically determined by the voltage difference between the fuel cell and the capacitor and the internal resistance of the capacitor, when the voltage difference between the fuel cell and the capacitor is large, the current value also increases. If the value is excessive, there is a possibility that the components of the high-voltage system are burned or broken due to overcurrent, or the system is stopped or the fuel cell stack is deteriorated due to a rapid voltage drop of the fuel cell stack.

  Therefore, in the first embodiment, the maximum voltage of the capacitor 28 is higher than the idle voltage of the fuel cell 4, and when the fuel cell 4 and the capacitor 28 are connected, the capacitor voltage of the capacitor 28 is 4 or equal to or higher than the idle voltage, no current is generated from the fuel cell 4 toward the capacitor 28, and no malfunction occurs. Even in this case, no problem arises because no current is generated from the capacitor 28 to the fuel cell 4 by the backflow prevention diode 22.

  Further, the maximum voltage of the capacitor 28 is preferably higher within the range of the withstand voltage of the components of the high voltage system such as the inverter 6 and other auxiliary devices of the high voltage system for the following two reasons.

  The first reason is that by making the maximum voltage of the capacitor 28 higher, there is a margin with respect to the voltage value of the fuel cell 4 even when the capacitor voltage decreases due to self-discharge after the vehicle stops. This is because it becomes possible. By charging the capacitor voltage to a higher voltage than the idle voltage of the fuel cell 4 and then stopping the vehicle system, even if the capacitor voltage drops while the vehicle is parked due to self-discharge, the idle voltage is longer. It becomes possible to maintain a state higher than the voltage.

  The second reason is that the stored energy of the capacitor 28 can be used more effectively as the operating voltage range of the capacitor 28 is wider. The energy of the capacitor 28 is expressed by CV2 / 2, and is proportional to the square of the capacitance C and the voltage V of the capacitor 28. Therefore, the wider the usable voltage region of the capacitor 28, the larger the usable energy. .

  FIG. 2 schematically shows an example of the above-described example, that is, an example of a change in the voltage value of the 300-cell fuel cell 4 and the capacitor 28 during acceleration / deceleration of the vehicle.

  As shown in FIG. 2, the fuel cell voltage of the fuel cell 4 decreases as the required load of the vehicle increases, in other words, as the generated current of the fuel cell 4 increases, and conversely increases as the load decreases. Therefore, in this example, the fuel cell voltage Vfc varies in accordance with the load within a range from 180V at the maximum load to 270V at the idle time. On the other hand, the capacitor 28 follows the voltage change of the fuel cell 4 well due to the characteristic that charging and discharging accompanies the voltage change, and the regenerative power at the time of load and deceleration is within the range of 180 V at the maximum load to the maximum voltage of the capacitor 28. It changes according to.

  As an example, if the maximum voltage of the capacitor 28 is the idle voltage 270V of the fuel cell 4, the capacitor voltage follows the output voltage Vfc of the fuel cell 4 as shown by Vcap1 in FIG. Stays at ~ 270V. On the other hand, if the maximum voltage of the capacitor 28 is about 1.5 times 400V, the voltage rises due to regenerative energy during deceleration as shown by Vcap2 in FIG. 2, and the operating voltage range is 180V to 400V. It will spread significantly and the available energy will be about 3.2 times as shown in the equation in FIG.

  As a result, the actual energy density, which is the usable energy per unit weight or unit volume, is approximately 2.1 times, and the capacitor 28 can be reduced in size and weight.

  Therefore, in the first embodiment, in the fuel cell vehicle equipped with the fuel cell 4 and the capacitor 28, the fuel cell 4 which is likely to be generated when the fuel cell 4 and the capacitor 28 are connected at the time of starting the vehicle system. In order to prevent an overcurrent from to the capacitor 28, the capacitor 28 is charged in advance to a threshold value (idle voltage) or more in the vehicle stop routine. In addition, for charging the capacitor 28 at this time, power supplied from an auxiliary machine driving battery 56 such as a 12V battery provided in the vehicle is used, and this power is also provided in the vehicle. This is realized by boosting the voltage by the DC / DC converter 62. According to this method, the output voltage of the DC / DC converter 62 can be arbitrarily set, and therefore, the charging voltage of the capacitor 28 can be freely changed.

  Next, the operation of the first embodiment will be described based on the flowchart of FIG.

  As shown in FIG. 1, when the vehicle stop routine of the program of the control means 74 is started (step 102), the first relay 14 connecting the fuel cell 4 and the high voltage system is opened (step 104), and the fuel cell 4 Is disconnected from the high voltage system.

  Subsequently, the capacitor voltage Vcap is measured by the second voltmeter 36 for measuring the voltage across the terminals of the capacitor 28 (step 106), and this capacitor voltage Vcap is used as the fuel cell voltage stored in the control means 74. It is compared with the idle voltage Vfc-idle (step 108).

  In this step 108, if the capacitor voltage Vcap is equal to the idle voltage Vfc-idle, or if the capacitor voltage Vcap is larger than the idle voltage Vfc-idle and the answer is YES, the capacitor 28 is connected to the high voltage system. 2 The relay 34 is opened (step 110), the capacitor 28 is disconnected from the high voltage system, and the vehicle stop routine relating to the management of the capacitor voltage when the vehicle is stopped is terminated (step 112).

  On the other hand, when the capacitor voltage Vcap is smaller than the idle voltage Vfc-idle in step 108 and NO, the bidirectional DC / DC converter 62 is set to the boost mode and the output voltage is set to the idle voltage Vfc-idle. Then, the capacitor 28 is charged from the auxiliary device driving battery 56 via the bidirectional DC / DC converter 62 (step 114). By setting the charging current at this time to the maximum allowable current of the auxiliary device driving battery 56 and the capacitor 28, the charging time of the capacitor 28 in the vehicle stop routine can be shortened.

  While the capacitor 28 is being charged, the capacitor voltage Vcap is always measured (step 116), and the capacitor voltage Vcap is compared with the idle voltage Vfc-idle (step 118).

  In this step 118, if the capacitor voltage Vcap is equal to the idle voltage Vfc-idle or the capacitor voltage Vcap is larger than the idle voltage Vfc-idle, and YES, the capacitor 28 and the high voltage system are connected. The second relay 34 is opened (step 120), the bidirectional DC / DC converter 62 is stopped (step 122), and the charging of the capacitor 28 is ended (step 124).

  On the other hand, in step 118, when the capacitor voltage Vcap is smaller than the idle voltage Vfc-idle, in the case of NO, the process returns to step 114 and the capacitor 28 is continuously charged.

  Thereby, when the vehicle system is started next time, ideally, the capacitor voltage Vcap becomes equal to the idle voltage Vfc-idle. Therefore, after the fuel cell 4 is started, the fuel cell 4 and the high voltage system are connected. By closing the first relay 14 and subsequently closing the second relay 34 that connects the capacitor 28 and the high voltage system, an overcurrent from the fuel cell 4 to the capacitor 28 does not occur, and the fuel cell 4 and the capacitor 28 And can be connected.

  As a result, when the vehicle system is activated and the fuel cell 4, the capacitor 28, and the motor 8 can be controlled, the vehicle is stopped, and at least the power of the fuel cell 4 cannot be supplied to the motor 8. Since the capacitor voltage Vcap when the vehicle is stopped and the idle voltage Vfc-idle that is the fuel cell voltage are compared, the capacitor voltage Vcap can maintain a value that is equal to or higher than the idle voltage Vfc-idle. Since the value of the capacitor voltage Vcap does not always fall below the value of the idle voltage Vfc-idle at the time of starting the system, the fuel cell 4 and the capacitor 28 can be connected immediately after starting the vehicle system. It is possible to shorten the time until the vehicle can run.

  Further, since the control means 74 controls charging of the capacitor 28 by the auxiliary device driving battery 56, it is not necessary to provide a special charging device, and the fuel cell system is not complicated.

  That is, in the first embodiment, in the vehicle having the fuel cell 4 and the capacitor 28, the capacitor 28 is charged by the vehicle stop routine. And the capacitor 28 can be connected to each other, thereby shortening the time until the vehicle can run.

  In addition, since the capacitor 28 is charged using the auxiliary device driving battery 56 for driving the vehicle auxiliary devices 68 and the bidirectional DC / DC converter 62, the capacitor 28 is large and heavy. The time until the vehicle can travel can be reduced without providing an expensive voltage conversion device.

  Furthermore, since the maximum voltage of the capacitor 28 is higher than the idle voltage, which is the fuel cell voltage, and lower than the withstand voltage of the high voltage auxiliary machinery 46, the energy of the capacitor 28 can be used effectively. The capacitor 28 can be reduced in size and weight.

  Furthermore, since the charging voltage of the capacitor 28 in the vehicle stop routine is set equal to the idle voltage of the fuel cell 4, an overcurrent from the fuel cell 4 to the capacitor 28 at the time of starting the vehicle system can be prevented.

  FIG. 4 shows a second embodiment of the present invention.

  In the following embodiments, portions having the same functions as those in the first embodiment will be described with the same reference numerals.

  The features of the second embodiment are as follows. In general, a capacitor has a voltage that gradually decreases due to self-discharge even when there is no load after charging. The self-discharge rate of the capacitor is larger than that of the secondary battery in the present situation. Therefore, even if the capacitor is charged to the idle voltage of the fuel cell in the vehicle stop routine, the self-discharge rate until the next vehicle system start-up is performed. In the meantime, the capacitor voltage decreases depending on the parking time of the vehicle. For this reason, it is more preferable to charge the capacitor with a higher voltage value in advance in anticipation of the self-discharge of the capacitor.

  Therefore, in the second embodiment, as shown in FIG. 4, the threshold value of the capacitor voltage in the vehicle stop routine is changed. That is, the vehicle stop routine shown in FIG. 4 is substantially the same as the flowchart of the first embodiment shown in FIG. 1, but the capacitor voltage Vcap is set to a threshold value Vth1 (V) that is set to be higher than the idle voltage Vfc-idle. ) Has been changed.

  As shown in FIG. 4, when the vehicle stop routine of the program of the control means 74 is started (step 202), the first relay 14 connecting the fuel cell 4 and the high voltage system is opened (step 204), and the fuel cell 4 Is disconnected from the high voltage system.

  Subsequently, the capacitor voltage Vcap is measured by the second voltmeter 36 for measuring the voltage across the terminals of the capacitor 28 (step 206), and this capacitor voltage Vcap is compared with the threshold value Vth1 stored in the control means 74. (Step 208).

  In this step 208, when the capacitor voltage Vcap is equal to the threshold value Vth1 or the capacitor voltage Vcap is larger than the threshold value Vth1, in the case of YES, the second relay 34 connecting the capacitor 28 and the high voltage system is set. Open (step 210), disconnect the capacitor 28 from the high-voltage system, and end the vehicle stop routine related to the management of the capacitor voltage when the vehicle is stopped (step 212).

  On the other hand, when the capacitor voltage Vcap is smaller than the threshold value Vth1 in step 208 and NO, the bidirectional DC / DC converter 62 is set to the boost mode and the output voltage is set to the threshold value Vth1 (step 214). The capacitor 28 is charged from the driving battery 56 via the bidirectional DC / DC converter 62. By setting the charging current at this time to the maximum allowable current of the auxiliary device driving battery 56 and the capacitor 28, the capacitor charging time in the vehicle stop routine can be shortened.

  During the charging of the capacitor 28, the capacitor voltage Vcap is always measured (step 216), and the capacitor voltage Vcap is compared with the threshold value Vth1 (step 218).

  In this step 218, when the capacitor voltage Vcap is equal to the threshold value Vth1 or the capacitor voltage Vcap is larger than the threshold value Vth1, and YES, the second relay 34 that connects the capacitor 28 and the high voltage system is opened. (Step 220) Then, the bidirectional DC / DC converter 62 is stopped (Step 222), and the charging of the capacitor 28 is finished (Step 224).

  On the other hand, in step 218, when the capacitor voltage Vcap is smaller than the threshold value Vth1, in the case of NO, the process returns to step 214, and charging of the capacitor 28 is continued.

  That is, in the second embodiment, the capacitor voltage Vcap is changed to the threshold value Vth1 set higher than the idle voltage Vfc-idle in steps 208, 214, and 218 of FIG.

The threshold value Vth1 can be arbitrarily set between the idle voltage Vfc-idle and the maximum voltage of the capacitor 24, but a larger value can increase a margin for self-discharge. In general, the threshold value Vth1 is determined by the idle voltage Vfc-idle of the fuel cell 4, the self-discharge rate R (V / hr) expressed by the voltage drop per unit time of the capacitor 24, and the next vehicle system start-up. From the allowable vehicle parking time t (hr), it is possible to calculate the following equation (1).
Vth1 = Vfc-idle + Rt (1)

  Thus, by charging the capacitor voltage Vcap higher than the idle voltage Vfc-idle of the fuel cell 24 when the vehicle is stopped, the capacitor voltage has been reduced by self-discharge until the next start of the vehicle system. In preparation for the case, it is possible to reserve a margin, and if the vehicle parking time is between the allowable vehicle parking times, an overcurrent from the fuel cell 4 to the capacitor 28 is generated at the next start of the vehicle vehicle system. The fuel cell 4 and the capacitor 28 can be connected without any problem.

  Therefore, in the second embodiment, the charging voltage of the capacitor 28 in the vehicle stop routine is determined in consideration of the voltage drop due to the self-discharge of the capacitor 28, so that the capacitor voltage is reduced by the self-discharge while the vehicle is parked. Even in this case, it is possible to prevent an overcurrent from the fuel cell 4 to the capacitor 28 at the time of starting the vehicle system.

  FIG. 5 shows a third embodiment of the present invention.

  The features of the third embodiment are as follows. That is, when the vehicle system is started, if the fuel cell voltage of the fuel cell 4 is higher than the capacitor voltage of the capacitor 28, an overcurrent does not immediately occur. Therefore, step 108 of the flowchart of FIG. , 114, 118 and the threshold voltage Vth1 in steps 208, 214, 218 of the flowchart of FIG. 4 of the second embodiment are different from each other in consideration of the allowable voltage difference between the fuel cell 4 and the capacitor 28. It is also possible to change to the threshold value Vth2.

This threshold value Vth2 is the self-discharge rate R (V / hr) of the capacitor 28, the internal resistance r (Ω), the allowable current I (A) of the capacitor 28 and the fuel cell 4, and the allowable time until the next start of the vehicle system. It is a value that can be calculated from the vehicle parking time t (hr) according to the following equation (2). If the voltage value is equal to or greater than the threshold value Vth2, the current flowing from the fuel cell 4 to the capacitor 28 is excessive. Absent.
Vth2 = Vfc-idle + Rt-rI (2)

  That is, as shown in FIG. 5, when the vehicle stop routine of the program of the control means 74 starts (step 302), the first relay 14 that connects the fuel cell 4 and the high voltage system is opened (step 304). The fuel cell 4 is disconnected from the high voltage system.

  Subsequently, the capacitor voltage Vcap is measured by the second voltmeter 36 for measuring the voltage across the terminals of the capacitor 28 (step 306), and this capacitor voltage Vcap is compared with the threshold value Vth2 stored in the control means 74. (Step 308).

  In this step 308, if the capacitor voltage Vcap is equal to the threshold value Vth2 or the capacitor voltage Vcap is larger than the threshold value Vth2, in the case of YES, the second relay 34 that connects the capacitor 28 and the high voltage system is set. Open (step 310), the capacitor 28 is disconnected from the high voltage system, and the vehicle stop routine related to the management of the capacitor voltage when the vehicle is stopped is terminated (step 312).

  On the other hand, if the capacitor voltage Vcap is smaller than the threshold value Vth2 in step 308 and NO, the bidirectional DC / DC converter 62 is set to the boost mode and the output voltage is set to the threshold value Vth2 (step 314). The capacitor 28 is charged from the driving battery 56 via the bidirectional DC / DC converter 62. By setting the charging current at this time to the maximum allowable current of the auxiliary device driving battery 56 and the capacitor 28, the capacitor charging time in the vehicle stop routine can be shortened.

  During charging of the capacitor 28, the capacitor voltage Vcap is always measured (step 316), and the capacitor voltage Vcap is compared with the threshold value Vth2 (step 318).

  In this step 318, if the capacitor voltage Vcap is equal to the threshold value Vth2 or the capacitor voltage Vcap is greater than the threshold value Vth2, and YES, the second relay 34 connecting the capacitor 28 and the high voltage system is opened. (Step 320) Then, the bidirectional DC / DC converter 62 is stopped (Step 322), and the charging of the capacitor 28 is finished (Step 324).

  On the other hand, in step 318, when the capacitor voltage Vcap is smaller than the threshold value Vth2, in the case of NO, the process returns to step 314 and the capacitor 28 is continuously charged.

  Thus, by reducing the capacitor charging voltage in the vehicle stop routine by the allowable voltage difference when connecting the fuel cell 4 and the capacitor 28, the time required for charging the capacitor 28 can be shortened.

  Therefore, in the third embodiment, the charging voltage of the capacitor 28 in the vehicle stop routine is determined in consideration of the allowable current from the fuel cell 4 to the capacitor 28, so that the charging time of the capacitor 28 in the vehicle stop routine is shortened. However, it is possible to prevent an overcurrent from the fuel cell 4 to the capacitor 28 at the time of starting the vehicle system.

  FIG. 6 shows a fourth embodiment of the present invention.

  The features of the fourth embodiment are as follows. That is, a capacitor voltage monitor is proposed while the vehicle is parked.

  As described above, since the value of the capacitor voltage decreases with time due to self-discharge, the capacitor voltage becomes equal to or lower than the threshold value Vth2 of the third embodiment due to long-term vehicle parking exceeding the allowable vehicle parking time assumed as described above. In the case of a decrease, the overcurrent from the fuel cell 4 to the capacitor 28 occurs at the next start-up of the vehicle system, which may cause various problems.

  In order to prevent such a problem, in the fourth embodiment, when the capacitor voltage is measured during long-term parking of the vehicle exceeding the allowable vehicle parking time, and the capacitor voltage falls below a certain threshold, As in each of the embodiments, auxiliary charging of the capacitor 28 is performed using the auxiliary device driving battery 56 and the bidirectional DC / DC converter 62. The capacitor voltage monitor may be performed at all times during parking, but it is more preferable to perform the capacitor voltage monitor at a certain interval in order to minimize power consumption.

  As shown in FIG. 6, when the allowable vehicle parking time has elapsed since the vehicle stopped and the vehicle system has not been activated, the capacitor voltage monitoring routine starts (step 402). The capacitor voltage Vcap is measured every other time (step 404), and this capacitor voltage Vcap is compared with the threshold value Vth2 stored in the control means 74 (step 406).

  In this step 406, if the capacitor voltage Vcap is equal to the threshold value Vth2 or the capacitor voltage Vcap is larger than the threshold value Vth2, and YES, the capacitor voltage monitoring routine is terminated as it is (step 408).

  On the other hand, in this step 406, due to self-discharge, the capacitor voltage Vcap falls below the threshold value Vth2, and in the case of NO, the second relay 34 connecting the capacitor 28 and the high voltage system is closed (step 410). Then, the bidirectional DC / DC converter 62 is set to the boost mode (step 412), and the capacitor 28 is charged with the output voltage Vth2.

  During charging of the capacitor, the capacitor voltage Vcap is always measured (step 414), and the capacitor voltage Vcap is compared with the threshold value Vth2 (step 416).

  In this step 416, if the capacitor voltage Vcap is equal to the threshold value Vth2 or the capacitor voltage Vcap becomes larger than the threshold value Vth2 and YES, the second relay 34 connecting the capacitor 20 and the high voltage system is opened. (Step 418), the bidirectional DC / DC converter 62 is stopped (Step 420), and the charging of the capacitor 28 is finished (Step 422).

  On the other hand, in step 416, if the capacitor voltage Vcap is smaller than the threshold value Vth2, if NO, the process returns to step 412 to continue charging the capacitor 28.

  In the fourth embodiment, the threshold value of the capacitor voltage is set to Vth2, which is the threshold value of the third embodiment, but this threshold value can be changed as appropriate.

  As described above, the capacitor voltage is monitored at regular intervals, and if an unacceptable voltage drop is observed, the capacitor 28 is supplementally charged even when the vehicle is parked. 4 and the capacitor 28 can be easily connected.

  Therefore, in the fourth embodiment, since the capacitor 28 is supplementarily charged even when the capacitor voltage is lowered while the vehicle is parked, the vehicle parking time exceeds the assumed allowable vehicle parking time. In addition, it is possible to prevent an overcurrent from the fuel cell 4 to the capacitor 28 when the vehicle system is started.

  Of course, the present invention is not limited to the above-described embodiments, and various application modifications are possible.

  That is, three threshold values for the charging voltage of the capacitor have been described in each of the above embodiments. However, the threshold value is not limited to three, and can be changed to other different values.

  In addition, it is possible to suppress a decrease in the capacity of the auxiliary device driving battery by covering the capacitor with auxiliary power while the vehicle is parked by using generated power such as a solar battery.

  In addition, a switch is provided to detect that the driver has unlocked the vehicle door, and when this switch is turned on, the vehicle system is immediately activated to charge the capacitor early, so that the vehicle can run. This time can be further shortened. Further, the vehicle stop time is converted, and the vehicle stop routine of the present invention is executed only when necessary so that the vehicle stop time is long and the capacitor self-discharge occurs, thereby reducing the frequency of use of the vehicle stop routine. Is possible.

  Maintaining the capacitor voltage at a value equal to or higher than the fuel cell voltage when the vehicle is stopped can also be applied to control of other devices than the control of the hybrid vehicle.

It is a flowchart of control for vehicles in the 1st example. It is a figure explaining the change state of each voltage in 1st Example. It is a system configuration figure of the control device for vehicles in the 1st example. It is a flowchart of control for vehicles in the 2nd example. It is a flowchart of control for vehicles in the 3rd example. It is a flowchart of control for vehicles in the 4th example.

Explanation of symbols

2 Vehicle Control Device 4 Fuel Cell 6 Inverter 8 Motor 14 First Relay 16 First Voltmeter 28 Capacitor 34 Second Relay 36 Second Voltmeter 46 High Voltage Auxiliary Equipment 56 Auxiliary Drive Battery 68 Vehicle Auxiliary Equipment 74 Control means

Claims (2)

  In a vehicle control device including a motor for driving a vehicle, a fuel cell connected in parallel to the motor, and a capacitor, an auxiliary storage battery for driving the auxiliary device for the vehicle is provided, and the vehicle system is activated. When the fuel cell, the capacitor, and the motor are controllable and the vehicle is stopped, and the power of the fuel cell cannot be supplied to at least the motor, the vehicle is stopped. A vehicle is provided with a control means provided with a voltage maintenance control unit that compares the capacitor voltage with the fuel cell voltage in a state in which the capacitor voltage is maintained and controls the capacitor voltage so as to maintain a value equal to or higher than the fuel cell voltage. Control device.   The vehicle control device according to claim 1, wherein the control unit controls charging of the capacitor by the auxiliary storage battery.

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