JP6926549B2 - Electric vehicle power supply - Google Patents

Description

The present disclosure relates to a power supply device for an electric vehicle, and more particularly to a power supply device for an electric vehicle including a fuel cell and a secondary battery.

In an electric vehicle equipped with a fuel cell as a power supply device, fuel efficiency is improved by operating the fuel cell in the most efficient range in the operation (power generation) control of the fuel cell.
For example, Patent Document 1 discloses a power supply device capable of responding to a high load requirement while taking into consideration the power generation efficiency of a fuel cell. Specifically, it is a power supply device including a fuel cell, a power storage device connected in parallel with the fuel cell with respect to an electric load, and a control device for controlling the output of the fuel cell and the charging of the power storage device. When the load requirement is smaller than the electric power at the high efficiency point of the fuel cell, the apparatus drives the fuel cell at the high efficiency point and charges the power storage device with surplus electric power. On the other hand, it is disclosed that when the load request is equal to or higher than the power at the high efficiency point, the power corresponding to the load request is controlled to be output from the fuel cell.

Japanese Unexamined Patent Publication No. 2006-210100

However, in the power supply device of Patent Document 1, it is shown that fuel efficiency is improved by operating the fuel cell at a high efficiency point, but as in step S7 in the flowchart of FIG. 2 of Patent Document 1, the power storage device ( This is a control in which operation is performed at a high efficiency point when the charge rate (SOC) of the secondary battery) is less than X% (for example, 60%).

Therefore, since Patent Document 1 controls the operation at the high efficiency point based on one point having a charge rate of X%, the operation at the high efficiency point is finely controlled based on the charge rate (SOC). It is not disclosed that the fuel efficiency of the fuel cell is further improved.
Further, in Patent Document 1, in order to reduce the charging cost by increasing the charging by electricity from the outside of the vehicle rather than the charging by hydrogen, which has a higher energy unit price than electricity, and to maintain the operation at a high efficiency point. It is not disclosed to limit the load requirement on the vehicle side.

Therefore, in view of the above technical problems, at least one embodiment of the present invention limits the required output on the vehicle side in the power supply device of the electric vehicle including the fuel cell and the secondary battery to obtain the maximum efficiency output of the fuel cell. The purpose is to improve the fuel cell fuel efficiency by increasing the power generation time of the fuel cell.

(1) The power supply device for an electric vehicle according to at least one embodiment of the present invention includes a fuel cell that generates power by being supplied with hydrogen and oxygen, and a secondary battery that charges the power generated by the fuel cell. In the power supply device of the electric vehicle provided, the fuel cell control unit for controlling the power generation of the fuel cell based on the information from the charge state detecting means for detecting the charge state of the secondary battery is provided, and the fuel cell control unit includes a fuel cell control unit. It has a power generation control unit that generates power at the maximum efficiency output of the fuel cell when the charging state falls below the lower limit charging rate and stops power generation of the fuel cell when the charging rate reaches a target charging rate higher than the lower limit charging rate. When the fuel cell is generating power at the maximum efficiency output by the power generation control unit, the fuel cell is provided with a vehicle output limiting unit that limits the vehicle required output indicating the required power on the vehicle side to the maximum efficiency output or less. do.

According to the above configuration (1), the lower limit value and the target value larger than the lower limit value are set for the filling rate of the secondary battery, and the fuel cell is generated with a constant value of the maximum efficiency output during that period. Compared to the one that controls the power generation by the maximum efficiency output with a constant charge rate as the boundary, the power generation time by the maximum efficiency output can be set longer, and the fuel cell fuel cell can be improved. In addition, since it is possible to reduce the response to the start and stop of power generation, the deterioration of the fuel cell is suppressed.
Improving the fuel efficiency of the fuel cell means reducing the amount of hydrogen gas and oxygen, and supplying auxiliary equipment required for generating the fuel cell, for example, air taken in from the outside air to the cathode of the fuel cell as oxygen gas. Operates auxiliary equipment such as an air blower, a circulation pump that recirculates unreacted hydrogen gas of the hydrogen gas of the fuel supplied to the fuel cell anode to the fuel cell anode, and a fuel cell cooling water or cooling air supply pump. Is to reduce the amount of power generated.

Further, according to the above configuration (1), when the fuel cell is generating power at the maximum efficiency output, the vehicle output limiting unit limits the vehicle required output on the vehicle side to the above maximum efficiency output or less, for example. Even if the accelerator pedal is depressed for a sudden acceleration request, the vehicle required output is limited to the maximum efficiency output of the fuel cell or less, so acceleration is sacrificed, but the power consumption of the secondary battery is suppressed and the fuel cell Even if the maximum efficiency operation is canceled and the power generation efficiency deteriorates, it is possible to suppress the generation of power and the charging of the secondary battery.
As a result, the fuel cell can maintain the operation in the maximum efficiency output state, so that the fuel efficiency of the fuel cell can be improved.

(2) In some embodiments, the vehicle output limiting unit limits the vehicle required output so as to match the maximum efficiency output of the fuel cell.

According to the above configuration (2), since the vehicle required output matches the maximum efficiency output of the fuel cell, even if the secondary battery output becomes the worst zero state, the vehicle uses only the maximum efficiency output of the fuel cell. It can respond to the vehicle request output on the side.
In addition, instead of charging the secondary battery by significantly increasing the fuel cell output even with the deterioration of the power generation efficiency of the fuel cell, the vehicle output limiting unit requires the vehicle to match the maximum efficiency output of the fuel cell. Since the output is limited, the power consumption of the secondary battery can be suppressed, and the fuel cell is maintained in the maximum efficiency output state, so that the fuel cell fuel efficiency can be improved.

( 3 ) In some embodiments, when the output obtained by subtracting the vehicle required output from the maximum efficiency output of the fuel cell exceeds the power received by the secondary battery, the fuel cell control unit may use the fuel cell control unit regardless of the target charge rate. It is characterized by stopping the power generation of the fuel cell.

According to the above configuration ( 3 ), when the output obtained by subtracting the vehicle required output from the maximum efficiency output of the fuel cell exceeds the power received by the secondary battery, the power generation of the fuel cell is stopped regardless of the target charge rate. It is possible to suppress overcharging of the battery and prevent deterioration of the secondary battery.

( 4 ) In some embodiments, the electric vehicle includes mode selection means for selecting a traveling mode, and when the "super charge mode" for maintaining a predetermined charge rate is selected by the mode selection means, the above. The power generation control unit sets the predetermined charge rate in the "super charge mode" as the target charge rate, and the fuel cell control unit uses the output obtained by subtracting the vehicle required output from the maximum efficiency output of the fuel cell as the secondary battery receiving power. When the amount exceeds, the output of the fuel cell is limited to the total value of the vehicle required output and the power received by the secondary battery, and the secondary battery is charged.

According to the above configuration ( 4 ), when the "super charge mode" is selected by the mode selection means, the fuel cell control unit determines that the output obtained by subtracting the vehicle required output from the maximum efficiency output of the fuel cell is the secondary battery. When the received power is exceeded, the output of the fuel cell is limited to the total value of the vehicle required output and the received power of the secondary battery to charge the secondary battery, so that the predetermined charge rate in the "super charge mode" is reached. You will be able to charge up to.

According to at least one embodiment of the present invention, in the power supply device of an electric vehicle including a fuel cell and a secondary battery, the required output on the vehicle side is limited to the maximum efficiency output of the fuel cell or less, so that the secondary battery Since power consumption is suppressed and the power generation output of the fuel cell is maintained in the maximum efficiency output state, the fuel cell fuel efficiency can be improved.

It is a block diagram of the power supply device of the electric vehicle which concerns on one Embodiment of this invention. It is a control table explaining the operation control of a fuel cell. It is a characteristic diagram which shows the relationship between a fuel cell output (FC output) and a vehicle efficiency. It is a characteristic diagram which shows the relationship between the rechargeable power which can accept a secondary battery, and the charge rate (SOC). It is a control flowchart in the fuel cell control part of the power supply device of the electric vehicle which concerns on one Embodiment of this invention. It is a control flowchart which shows the continuation of FIG. It is a control flowchart of "normal mode control" in FIG. 5-2. It is a control flowchart of "emergency mode control" in FIG. 5-2. It is a control flowchart of "save mode control" in FIG. 5-2. It is a control flowchart of "charge mode control" in FIG. 5-2. It is a control flowchart of "super charge mode control" in FIG. 5-2.

Hereinafter, some embodiments of the present invention will be described with reference to the accompanying drawings. However, the dimensions, materials, shapes, relative arrangements, etc. of the components described in these embodiments or shown in the drawings are not intended to limit the scope of the present invention to this, and are merely explanatory examples. It's just that. For example, expressions such as "same", "equal", and "homogeneous" that indicate that things are in the same state not only represent exactly the same state, but also have tolerances or differences to the extent that the same function can be obtained. It shall also represent the existing state. On the other hand, the expressions "equipped", "equipped", "equipped", "included", or "have" one component are not exclusive expressions that exclude the existence of other components.

The overall configuration of the power supply device 3 of the electric vehicle 1 according to the embodiment of the present invention will be described with reference to FIG.
As shown in FIG. 1, the electric vehicle 1 includes a fuel cell (FC) 5 that generates electricity by being supplied with hydrogen and oxygen, and a secondary battery 7 that charges the electric power generated by the fuel cell 5. It is provided with a traveling motor (motor) 9 that is mainly driven by receiving power supplied from the secondary battery 7. Although FIG. 1 shows an example in which the front wheel 11 side is driven by the traveling motor 9, the traveling motor 9 may be provided on the rear wheel side or on both sides of the front and rear wheels.

The fuel cell 5 is configured by sandwiching a power generation cell having a structure in which an air electrode (cathode) and a fuel electrode (anode) are opposed to each other with a solid polymer electrolyte membrane interposed therebetween, sandwiched between separators, and stacking a plurality of the power generation cells. ing.
In addition, air, which is oxygen, is supplied to the catalyst layer on each air electrode side of a plurality of power generation cells, and hydrogen gas as fuel gas is supplied to the catalyst layer on each fuel electrode side. There is.

In the fuel cell 5, when hydrogen gas is supplied to the fuel electrode (anode) and air containing oxygen is supplied to the air electrode (cathode), the following reaction occurs, so that an electromotive force occurs between the electrodes. It is possible to extract electrical energy as electric power.
A fuel electrode ^{_{(anode): H 2 → 2H + +}} 2e -
An air electrode ^{_{(cathode): 1 / 2O 2 + 2H}} + + 2e - → H 2 O

Further, an air blower (not shown) that supplies air containing oxygen to the air electrode (not shown) of the fuel cell 5 and a hydrogen tank (not shown) that supplies hydrogen gas to the fuel electrode (not shown) are connected. There is.
Further, a hydrogen gas circulation pump (not shown) for returning unreacted hydrogen gas of hydrogen gas supplied to the anode of the fuel cell 5 to the anode of the fuel cell, and a pump for supplying cooling water or cooling air of the fuel cell (not shown). ) Etc. are provided for fuel cells.

The power supply device 3 includes a fuel cell 5, a secondary battery 7, a DC-DC converter 13, an inverter 15, a control device 17, and the like.
The electric power generated by the power supply device 3 is a motor 9, an air blower which is an auxiliary machine of the fuel cell 5, a hydrogen gas circulation pump, a cooling water or cooling air supply pump of the fuel cell, and a vehicle auxiliary machine. It is designed to be supplied to passenger compartment air conditioners and lamps.

Further, the motor 9 of the electric vehicle 1 is configured to be mainly driven by the electric power of the secondary battery 7, and the electric power generated by the fuel cell 5 is adjusted to a predetermined voltage by the DC-DC converter 13. The secondary battery 7 is charged. That is, only when the output of the secondary battery 7 is insufficient, the electric power from the fuel cell 5 is supplied to the motor 9 so as to make up for the shortage.

As described above, the secondary battery 7 is responsible for supplying electric power when the load fluctuates due to acceleration / deceleration during vehicle traveling, and is also responsible for storing regenerative electric power during vehicle braking. The secondary battery 7 may be a lithium ion battery, a nickel-cadmium battery, a nickel-hydrogen battery, or the like, and is not particularly limited.

Next, the control device 17 will be described.
The control device 17 is provided with a signal input unit, a signal output unit, a storage unit, a calculation unit, and the like (not shown). A signal from the vehicle state sensor 19, for example, a signal from a sensor that detects the vehicle speed and the amount of depression (acceleration) of the accelerator pedal, and a travel mode signal from the travel mode selection switch 21 are input to the signal input unit.
Further, as shown in FIG. 1, the control device 17 mainly includes a secondary battery control unit 23, a motor control unit 25, a vehicle control unit 27, and a fuel cell control unit (FC control unit) 29.

The secondary battery control unit 23 detects the temperature, output voltage, discharge current of the secondary battery 7, and the charge state (SOC: State Of Charge) of the secondary battery by the charge state detecting means 31, and obtains this information. It is acquired and transmitted to the vehicle control unit 27 and further to the fuel cell control unit 29. Further, when the charging state of the secondary battery 7 reaches a predetermined charging rate (for example, SOC 20% or less), the secondary battery control unit 23 is likely to be in a power shortage state, so that the charging notification prompts charging. The means 32 is activated to notify the driver.

The motor control unit 25 detects and acquires torque information of the motor 9, and transmits the detection information to the vehicle control unit 27. Further, the inverter 15 is controlled in order to control the output torque of the motor 9 based on the instruction of the vehicle required output from the vehicle control unit 27.

The vehicle control unit 27 further reduces the power consumption of the fuel cell 5 auxiliary machine and the vehicle auxiliary machine based on the signals from the vehicle state sensor 19, for example, the vehicle speed sensor, the sensor that detects the depression amount (acceleration) of the accelerator pedal, and the like. Including, it has a vehicle request output calculation unit 26 that calculates a vehicle request output indicating the required power on the vehicle side, and outputs the calculated vehicle request output to the motor control unit 25 and the fuel cell control unit 29 described later.

Further, the vehicle control unit 27 has a vehicle output limiting unit 28 that limits the vehicle request output calculated by the vehicle request output calculation unit 26 and outputs the vehicle request output to the motor control unit 25 and the fuel cell control unit 29. The vehicle output limiting unit 28 limits the vehicle required output to the maximum efficiency output Ps (see FIG. 3) or less of the fuel cell 5. For example, the electric power of the motor 9, the in-vehicle air-conditioning air conditioner, the in-vehicle heater, etc. (not shown) is limited.

Further, the electric vehicle 1 is provided with a travel mode selection switch 21, and the vehicle control unit 27 uses a detection signal from the travel mode selection switch 21, that is, a travel mode signal selected by the driver, as a fuel cell control unit. 29, it is designed to output to the motor control unit 25.

The traveling mode selection switch 21 allows the driver to select the traveling mode and select the charging state of the secondary battery 7.
For example, the travel mode selection switch 21 can select "save mode", "charge mode", and "super charge mode", and the electric vehicle 1 is in "normal mode" during normal operation in which these travel modes are not selected. It is in a state.

Further, when the secondary battery 7 is in the power shortage state, the fuel cell 5 automatically switches to the "emergency mode" to prevent the power shortage, and the fuel cell 5 generates power at the maximum power generation output. Further, when the accelerator pedal is depressed more than a predetermined amount, the mode automatically switches to the "assist mode", and the output of the fuel cell 5 is controlled so as to compensate for the insufficient output of the secondary battery 7 to the secondary battery 7. It is designed to be charged and supplied to the motor 9.

Further, when the fuel cell 5 does not require power generation and is in a stopped state, it automatically switches to the "EV mode". In this case, the fuel cell 5 stops power generation, and the electric vehicle 1 is in a state of being driven only by the charging power of the secondary battery 7.
The power generation output of the fuel cell 5 and the charging state of the secondary battery 7 in each of these traveling modes will be described in detail in the control table of FIG. 2 and the flowcharts of FIGS. 5-1 to 10.

The fuel cell control unit 29 controls the power generation (power generation output, power generation timing) of the fuel cell 5 and generates power of the fuel cell 5 mainly based on the signal of the charge state of the secondary battery 7 from the charge state detection means 31 (power generation output, power generation timing). Power generation output, power generation timing) is controlled. Then, the fuel cell control unit 29 generates electricity at the maximum efficiency output when the charging state falls below the lower limit charging rate, and stops the power generation of the fuel cell 5 when the charging rate exceeds the lower limit charging rate and reaches the target charging rate or higher. It has a power generation control unit 33 to operate.

FIG. 3 shows the relationship between the fuel cell output (FC output) and the vehicle efficiency. The horizontal axis represents the output power (KW) of the fuel cell 5, and the vertical axis represents the vehicle efficiency (%). This vehicle efficiency is the efficiency (vehicle efficiency) of an electric vehicle equipped with a fuel cell system including a fuel cell 5 and an auxiliary machine of the fuel cell 5. Based on the characteristics shown in FIG. 3, the “maximum efficiency output” is the FC output Ps (KW) of the maximum efficiency point Xm (%) in FIG.

Further, the power generation control unit 33 reduces the lower limit charge rate as the negative time change of the charge rate increases, that is, when the charge rate tends to decrease, and the power generation time of the fuel cell with the maximum efficiency output. To lengthen. In this way, since the lower limit charge rate is reduced and the power generation time of the fuel cell by the maximum efficiency output is lengthened, the charging time by the maximum efficiency output can be secured, so that the fuel efficiency of the fuel cell can be improved.

Next, the power generation control of the fuel cell 5 by the fuel cell control unit 29 will be described with reference to the control table of FIG.
Control table No. 1 indicates "emergency mode". This "emergency mode" is a mode for preventing the secondary battery 7 from running out of electricity. For example, when the SOC of the secondary battery 7 becomes less than 15%, the fuel cell 5 is used until the SOC reaches 20%. Is generated with FC maximum output Pmax.

Control table No. 2 indicates an "assist mode". This "assist mode" is a mode for compensating for the insufficient output of the secondary battery 7, and when the accelerator pedal is depressed more than a predetermined amount during sudden acceleration, the fuel cell 5 is used to compensate for the insufficient output of the secondary battery 7. The power output is controlled. For example, when the vehicle required output> the secondary battery maximum output + the current FC output, the fuel cell output is controlled so that the vehicle required output-the secondary battery maximum output is obtained. The maximum output of this secondary battery is calculated from the current SOC. For example, it is calculated by preparing a map or the like having a relationship between the maximum output of the secondary battery and the SOC in advance.

Further, in the "assist mode", the output of the fuel cell 5 is controlled so as to compensate for the output shortage of the secondary battery 7 with respect to the vehicle required output, but the vehicle required output is obtained by the vehicle output limiting unit 28 of the fuel cell 5. It is limited to the maximum efficiency output Ps or less.

Control table No. 3 indicates "normal mode". This "normal mode" is a normal driving mode state.
The traveling mode selection switch 21 provided on the electric vehicle 1 enables the driver to select "save mode", "charge mode", and "super charge mode". During normal operation in which the travel mode selection switch 21 is not selected, the vehicle is in the “normal mode” state.
This "normal mode" is a mode in which power generation is started at the lower limit SOC and stopped at the target SOC during normal operation. For example, when SOC ≦ (power generation condition (example 25%) −A%) [lower limit SOC], the fuel cell 5 starts power generation at a constant value of the maximum efficiency output Ps and maintains the output state of the constant value. When SOC ≧ 30% [target SOC], the power generation of the fuel cell 5 is stopped. During the power generation period at a constant value of the maximum efficiency output Ps, the vehicle required output is limited to the maximum efficiency output Ps or less of the fuel cell 5 by the vehicle output limiting unit 28.

An initial value of A> 0 is set for this A%, and the negative temporal change of SOC is fed back and increased. The amount of decrease increases as the negative temporal change of SOC increases. For example, when SOC <(power generation condition (example 25%) -A%), the time change of the deviation between the current SOC and (power generation condition (example 25%) -A%), that is, (SOC (current)-( Calculated based on power generation conditions (eg 25%) -A%)) / dt.

Control table No. 4 indicates a "save mode". This "save mode" is a mode for maintaining _{the SOC SAVE} [target SOC] when the travel mode selection switch 21 selects the save mode by the driver. For example, when the save mode is selected and SOC ≦ (SOC _SAVE −B%) [lower limit SOC], the fuel cell 5 starts power generation at a constant value of the maximum efficiency output Ps and maintains the constant value state. Then, when SOC ≥ SOC _SAVE [target SOC], or when (maximum efficiency output Ps of fuel cell 5-vehicle required output) ≥ secondary battery received power, power generation of the fuel cell 5 is stopped regardless of the target SOC. do. During the power generation period at a constant value of the maximum efficiency output Ps, the vehicle required output is limited to the maximum efficiency output Ps or less of the fuel cell 5 by the vehicle output limiting unit 28.

Note that FIG. 4 shows the relationship between the charge rate (SOC) and the power received by the secondary battery. The horizontal axis represents the SOC (%) of the secondary battery 7, and the vertical axis represents the power received by the secondary battery (KW). The secondary battery received power is calculated based on the characteristics shown in FIG.

The initial value of B> 0 is set for B%, and the negative time change of SOC is fed back and increased. The amount of decrease increases as the negative temporal change of SOC increases. For example, when SOC <(SOC _SAVE- B%), the time change of the deviation between the current SOC and (SOC _SAVE- B%), that is, (SOC (current)-(SOC _SAVE- B%)) / dt Calculated based on. In the case of the "save mode", the feedback coefficient (decrease coefficient) is set larger than that in the "normal mode".

Control table No. 5 indicates a "charge mode". This "charge mode" is a mode for maintaining a predetermined SOCCHARGE (for example, 80%). For example, when the "charge mode" is selected and SOC ≦ (SOCCHARGE-C%) [lower limit SOC], the fuel cell 5 starts power generation at a constant value of the maximum efficiency output Ps and maintains the constant value state. .. Then, when SOC ≥ SOCCHARGE [target SOC], or when (maximum efficiency output Ps of fuel cell 5-vehicle required output) ≥ secondary battery received power, power generation of the fuel cell 5 is stopped regardless of the target SOC. .. The secondary battery received power is calculated based on the characteristics shown in FIG. Further, during the power generation period at a constant value of the maximum efficiency output Ps, the vehicle required output is limited to the maximum efficiency output Ps or less of the fuel cell 5 by the vehicle output limiting unit 28.

The initial value of C> 0 is set for C%, and the negative time change of SOC is fed back and increased. The amount of decrease increases as the negative temporal change of SOC increases. For example, when SOC <(SOC _CHARGE- C%), the time change of the deviation between the current SOC and (SOC _CHARGE- C%), that is, (SOC (current)-(SOC _CHARGE- C%)) / dt Calculated based on. In the case of the "charge mode", the feedback coefficient (decrease coefficient) is set larger than that in the "save mode".

Control table No. 6 indicates a "supercharge mode". This "super charge mode" is _{a mode for maintaining a predetermined SOC CHARGE} (for example, 80%) as in the "charge mode". For example, when "supercharge mode" is selected and SOC ≤ (SOC _CHARGE- D%) [lower limit SOC], the fuel cell 5 starts power generation at a constant value of the maximum efficiency output Ps and changes the constant value state. maintain. Then, when SOC ≧ SOC _CHARGE [target SOC], the power generation of the fuel cell 5 is stopped. During the power generation period at a constant value of the maximum efficiency output Ps, the vehicle required output is limited to the maximum efficiency output Ps or less of the fuel cell 5 by the vehicle output limiting unit 28.

An initial value of D> 0 is set for this D%, and the negative temporal change of SOC is fed back and increased. The amount of decrease increases as the negative temporal change of SOC increases. For example, when SOC <(SOC _CHARGE- D%), the time change of the deviation between the current SOC and (SOC _CHARGE- D%), that is, (SOC (current)-(SOC _CHARGE- C%)) / dt Calculated based on. In the case of the "super charge mode", the increase amount may be the same as the increase amount of the above "charge mode", or the feedback coefficient (decrease coefficient) may be set larger than that of the "charge mode". good.

In addition, the above No. In the "charge mode" of 5, when (maximum efficiency output Ps of fuel cell 5-vehicle required output) ≥ secondary battery received power, the control is to stop the power generation of the fuel cell 5 regardless of the target SOC. In the "super charge mode", when (maximum efficiency output Ps of fuel cell 5-vehicle required output) ≥ secondary battery received power, the output of the fuel cell 5 is not maintained in the maximum efficiency state, and the vehicle required output +2. By limiting the power received by the secondary battery, the fuel cell 5 to the secondary battery 7 are continuously charged to the target SOC.
Therefore, in the "super charge mode", it is difficult to obtain the fuel consumption reduction effect as compared with the "charge mode", but there is an effect that the target SOC is charged.
Even in the "supercharge mode", the vehicle required output is limited to the maximum efficiency output Ps or less of the fuel cell 5 by the vehicle output limiting unit 28.

Next, the control flowchart in the fuel cell control unit 29 will be described with reference to the flowcharts of FIGS. 5-1 to 10.
The entire control flowchart is shown in FIGS. 5-1 and 5-2. In FIG. 5-1 first, in step S1, the vehicle request output on the vehicle side calculated by the vehicle request output calculation unit 26 is calculated. In the next step S2, the FC maximum efficiency output Ps is read. In the next step S3, it is determined whether the vehicle request output is equal to or higher than the FC maximum efficiency output Ps. In the case of Yes, the process proceeds to step S4, and the vehicle request output is limited to the FC maximum efficiency output Ps or less. If step S3 is No, the process proceeds to FIG. 5-2 (A).

After limiting the vehicle required output to FC maximum efficiency output Ps or less in step S4, it is determined in step S5 whether the limited vehicle required output exceeds (secondary battery maximum output + current FC output). In the case of Yes, the process proceeds to step S6, and the FC output is controlled to (vehicle required output-second battery maximum output). That is, the output of the fuel cell 5 is controlled so as to compensate for the output shortage due to the secondary battery 7 with respect to the vehicle required output. If step S5 is No, the process proceeds to FIG. 5-2 (A). According to the above steps S4 to S6, No. 1 in the control table shown in FIG. 2 assist mode controls are configured.

Since the vehicle required output is limited to the maximum efficiency output Ps or less of the fuel cell 5 by the vehicle output limiting unit 28 as in steps S3 and S4, for example, depressing the accelerator pedal is a sudden acceleration request. Is also limited to the maximum efficiency output Ps or less. As a result, although the acceleration is sacrificed, the power consumption of the secondary battery 7 is suppressed, and the maximum efficiency operation of the fuel cell 5 is canceled to generate power even if the power generation efficiency deteriorates, and the secondary battery 7 is used. Charging is suppressed. As a result, the fuel cell 5 can maintain the operation in the maximum efficiency output state, so that the fuel efficiency of the fuel cell 5 can be improved.

Further, it may be limited by matching with the maximum efficiency output Ps of the fuel cell 5. In this case, even in the worst state where the output of the secondary battery 7 becomes zero, only the maximum efficiency output Ps of the fuel cell 5 is used. It can respond to the required output on the vehicle side.

Next, the overall flowchart of FIG. 5-2 will be described.
First, the SOC of the secondary battery 7 is read in step S11, and in step S12, the travel mode selection switch 21 is operated to determine whether or not a predetermined travel mode is selected. If the travel mode selection switch 21 has not been selected, the result is No, and the process proceeds to step S13.
In step S13, it is determined whether or not the SOC is equal to or less than the first lower limit value. The first lower limit is, for example, 25% SOC. In step S13, in the case of Yes, the process proceeds to step S14, and in step S14, it is determined whether or not the SOC is smaller than the first lower limit value and less than the second lower limit value. The second lower limit is, for example, 15% SOC.

Then, if the determination in step S14 is No, the normal mode control is executed, and if the determination in step S14 is Yes, the emergency mode control is executed.
On the other hand, if the determination in step S13 is No, the process proceeds to step S7, and the power generation of the fuel cell 5 is stopped.

Here, returning to step S12, if the travel mode selection switch 21 is operated and a predetermined travel mode is selected in the determination of step S12, the process proceeds to step S19 and the selected travel mode is saved. Whether it is a mode or not is determined. In the case of Yes in step S19, the process proceeds to step S20 to execute the save mode control, and in the case of No in step S19, the process proceeds to step S21 to determine whether or not the charge mode is used.

If Yes in step S21, the charge mode control is executed in step S22, and if No in step S21, the process proceeds to step S23 to determine whether or not the supercharge mode is in effect.

If Yes in step S23, the process proceeds to step S24 to execute the supercharge mode control, and if No in step S23, the process returns to step S19 and the determination of the traveling mode is repeated again.

Next, "normal mode control" in step S15, "emergency mode control" in step S16, "save mode control" in step S20, "charge mode control" in step S22, and "super charge mode control" in step S24, respectively. The sub-control flowchart of the above will be described.

FIG. 6 shows a flowchart of normal mode control.
When the normal mode control is started in step S31, the fuel cell 5 is generated with the maximum efficiency output Ps in step S32, and the negative time change of SOC is calculated in step S33.
For example, when SOC <25% (first lower limit SOC), the time change of the deviation between the current SOC and (SOC 25% -A%), that is, (SOC (current)-(SOC 25% -A%)) / dt Is calculated.

Next, in step S34, the first lower limit SOC is reduced according to the magnitude of the negative time change of SOC. That is, the first lower limit SOC is greatly reduced as the negative time change becomes larger. The amount of decrease A% is set based on the negative time change of SOC calculated in step S33. For example, the amount of decrease A% is calculated as (SOC (current) − (SOC25% − previous A%)) / dt × K (decrease coefficient). By changing the reduction coefficient K according to the traveling mode, the power generation time at the maximum efficiency output Ps of the fuel cell 5 can be adjusted.

Next, in step S35, it is determined whether or not the SOC has reached the target SOC (30%), and if it reaches the target SOC, it becomes Yes, FC power generation is stopped in step S36, and the process ends in step S37. If No in step S35, the process returns to step S32 and is repeated.

In this way, according to the normal mode control, when the target SOC (30%) is maintained and the SOC is on a downward trend, the first lower limit SOC is reduced to generate electricity for the fuel cell 5 with the highest efficiency output Ps. Since the time is lengthened, the target charge rate of the secondary battery 7 can be maintained while improving the fuel efficiency of the fuel cell.

Further, as the negative time change of the charging rate becomes larger, the first lower limit SOC is decreased to lengthen the power generation time of the fuel cell 5 by the maximum efficiency output Ps, so that the first lower limit at which the fuel cell 5 starts power generation is increased. The SOC is lowered, the chance of charging the secondary battery 7 from the fuel cell 5 is reduced, and the chance of charging from outside the vehicle, that is, charging by the external charger is increased. For example, the notification by the charging notification means 32 increases the chances of charging by electricity, which has a lower energy unit price than hydrogen, and can reduce the charging cost.

FIG. 7 shows a flowchart of emergency mode control.
When the emergency mode control is started in step S41, the fuel cell 5 generates power at the maximum output Pmax in step S42, and in step S43, the SOC is equal to or higher than the second lower limit value (15%) and the first lower limit value (25). %) Is smaller than the third lower limit (20%). When it reaches, it becomes Yes and ends in step S44, and when it does not reach the third lower limit value (20%), it returns to step S32 and repeats.
As described above, according to the emergency mode control, when the SOC of the secondary battery 7 is less than the second lower limit value (15%) in step S14, the fuel cell 5 generates power at the maximum output Pmax, resulting in a power shortage. Can be prevented.

FIG. 8 shows a flowchart of save mode control.
When the save mode control is started in step S51, it is determined in step S52 whether the SOC is equal to or less than the _{SOC SAVE.} When the SOC is SOC _SAVE or less, the process proceeds to step S53 to generate electricity in the fuel cell 5 with the highest efficiency output Ps, and the negative time change of the SOC is calculated in step S54. As in the case of the normal mode, for example, when SOC <SOC _SAVE- B%, _{the time change of the deviation between SOC and SOC SAVE-} B%, that is, (SOC (current)-(SOC _SAVE- B%)) / Calculate dt.

Next, in step S55, the lower limit SOC (SOC _SAVE −B%) is reduced according to the magnitude of the negative time change of SOC. That is, the lower limit SOC is greatly reduced as the negative time change becomes larger. The amount of decrease B% is set based on the negative time change of SOC calculated in step S54. For example, the amount of decrease B% is _{calculated as (SOC (current) − (SOC SAVE} − previous B%)) / dt × K (decrease coefficient). The reduction coefficient K is set larger than in the normal mode.

Next, in step S56, _{it is determined whether or not the SOC has reached the target SOC (SOC SAVE} ), and if it reaches the target SOC (SOC SAVE), it becomes Yes, FC power generation is stopped in step S57, and the process ends in step S60. If No in step S56, the process proceeds to step S58, and in step S58, it is determined whether the output obtained by subtracting the "vehicle required output" from the "maximum efficiency output Ps" is equal to or greater than the "secondary battery received power", and Yes. In the case of, the process proceeds to step S57 to stop FC power generation and end in step S60. As a result, the secondary battery 7 can be prevented from being overcharged, and power generation at the maximum efficiency output can be stopped to improve fuel efficiency.

_{On the other hand, if the SOC is not equal to or less than the SOC SAVE} in step S52, the result is No, and the process proceeds to step S59 to stop FC power generation and end in step S60.

In this way, according to the save mode control, the lower limit SOC reduction coefficient is made larger than in the "normal mode", so that the power generation time by the maximum efficiency output Ps is longer than in the "normal mode", and the fuel cell 5 The charge rate of the secondary battery 7 can be maintained _{at SOC SAVE while improving fuel efficiency.}

FIG. 9 shows charge mode control.
The basic flow of charge mode control is the same as that of the save mode control of FIG. 8, and the save mode control of FIG. 8 is the charge of FIG. 9 while the _{target SOC is SOC SAVE in the save mode control.} In mode control, the target SOC is SOC _CHARGE .

When the charge mode control is started in step S71, it is determined in step S72 whether the SOC is equal to or less than the _{SOC CHARGE.} When the SOC is _{equal to or less than the SOC CHARGE} , the process proceeds to step S73 to generate electricity in the fuel cell 5 with the maximum efficiency output Ps, and the negative time change of the SOC is calculated in step S74. As in the case of save mode, for example, when SOC <SOC _CHARGE- C%, _{the time change of the deviation between SOC and SOC CHARGE-} C%, that is, (SOC (current)-(SOC _CHARGE- C%)) / Calculate dt.

Next, in step S75, the lower limit SOC (SOC _CHARGE- C%) is reduced according to the magnitude of the negative time change of SOC. That is, the lower limit SOC is greatly reduced as the negative time change becomes larger. The amount of decrease C% is set based on the negative time change of SOC calculated in step S74. For example, the amount of decrease C% is _{calculated as (SOC (current) − (SOC CHARGE} − previous C%)) / dt × K (decrease coefficient). The reduction coefficient K is set to be larger than in the save mode.

Next, in step S76, _{it is determined whether or not the SOC has reached the target SOC (SOC CHARGE} ), and if it reaches the target SOC, it becomes Yes, FC power generation is stopped in step S77, and the process ends in step S80. If No in step S76, the process proceeds to step S78, and in step S78, it is determined whether the output obtained by subtracting the "vehicle required output" from the "maximum efficiency output Ps" is equal to or greater than the "secondary battery received power", and Yes. In the case of, the process proceeds to step S77 to stop FC power generation and end in step S80. As a result, the secondary battery 7 can be prevented from being overcharged, and power generation at the maximum efficiency output can be stopped to improve fuel efficiency.

_{On the other hand, if the SOC is not equal to or lower than the SOC CHARGE} in step S72, the result is No, and the process proceeds to step S79 to stop FC power generation and end in step S80.

In this way, according to the charge mode control, the lower limit SOC reduction coefficient is made larger than in the "save mode", so that the power generation time by the maximum efficiency output Ps is longer than in the "save mode", and the SOC _CHARGE is maintained. Can be achieved without deteriorating the fuel efficiency of the fuel cell 5.

FIG. 10 shows the supercharge mode control.
The basic flow of the supercharge mode control is the same as that of the charge mode control of FIG. 9, and steps S92 to S98 of the supercharge mode of FIG. 10 are the same as steps S72 to S78 of the charge mode of FIG. Part A of step S99 in FIG. 10 is different.

That is, in the charge mode control of FIG. 9, in the case of Yes in step S78, the process proceeds to step S77 to stop FC power generation, but in this supercharge mode control, in step S98, if Yes, the process proceeds to step S99 to generate FC power. Does not stop, limits the output, continues power generation, and secures the charge to the secondary battery 7.
Therefore, in the super charge mode, the fuel consumption of the fuel cell 5 is worse than that of the charge mode of FIG. 9 because the power generation is not performed by the maximum efficiency output Ps, but the target is to prevent the secondary battery 7 from being overcharged. It is charged to achieve charging to the SOC.

According to the present embodiment described above, the lower limit SOC and the target SOC larger than the lower limit SOC are set in the SOC of the secondary battery 7, and power is generated at a constant value of the maximum efficiency output Ps of the fuel cell 5 between them. It is possible to set the power generation time by the maximum efficiency output longer than that in which the power generation by the maximum efficiency output is controlled with the charging rate of a predetermined constant value as a boundary, and the fuel cell 5 can be improved in fuel efficiency.

Further, according to the present embodiment, as the negative time change of the SOC increases, the lower limit SOC is reduced to lengthen the power generation time of the fuel cell 5 by the maximum efficiency output Ps, so that the fuel cell 5 is used. The lower limit SOC for starting power generation is lowered, and the chance of charging the secondary battery 7 from the fuel cell 5 is reduced. That is, the chances of charging from outside the vehicle, that is, charging by the charger outside the vehicle will increase. For example, when the charging state of the secondary battery 7 reaches a predetermined charging rate (for example, SOC 20% or less), there is a high possibility that the secondary battery 7 will be in a power shortage state. Notify. As a result, the chances of charging with electricity, which has a lower energy unit price than hydrogen, can be increased, and the charging cost can be reduced.

Further, according to the present embodiment, when the fuel cell 5 is generating power at the maximum efficiency output Ps, the vehicle output limiting unit 28 limits the vehicle required output on the vehicle side to the above-mentioned maximum efficiency output Ps or less. For example, even if the accelerator pedal is depressed for a sudden acceleration request, the acceleration property is difficult to be satisfied, but the power consumption of the secondary battery 7 is suppressed, and the fuel cell 5 is maintained in the maximum efficiency output state. The fuel efficiency of 5 can be improved.

No. 2 in FIG. In the "assist mode" shown in 2, the output of the fuel cell 5 is controlled so as to compensate for the insufficient output of the secondary battery 7 with respect to the required output of the vehicle. As shown in steps S4 to S6 of FIG. Since the vehicle required output is limited to the maximum efficiency output Ps or less of the fuel cell 5 by the vehicle output limiting unit 28, it becomes difficult to satisfy the acceleration, but the fuel cell output is increased even with the deterioration of the power generation efficiency of the fuel cell 5. The fuel cell 5 can be improved in fuel efficiency by significantly increasing the amount and suppressing charging of the secondary battery.

In the present embodiment, the lower limit SOC corresponds to SOC 25% -A% in normal mode control, SOC _{SAVE- B% in save mode control, SOC CHARGE-} C% in charge mode control, and supercharge. In mode control, SOC _CHARGE- D% corresponds.
Further, as the target SOC, SOC 30% corresponds to the normal mode control, SOC _{SAVE corresponds to the save mode control, and SOC CHARGE} corresponds to the charge mode control and the super charge mode.

Then, according to the present embodiment, as the negative time change of the SOC increases, the lower limit SOC is reduced and the power generation time of the fuel cell 5 by the maximum efficiency output Ps is lengthened, so that the fuel consumption of the fuel cell 5 is deteriorated. The above target SOC can be maintained while improving fuel efficiency without causing the problem.

In addition, the large negative time change of the charge rate occurs during high-load operation and high-speed operation. In this case, there is a large deceleration regeneration, so the SOC is lowered in order to improve the acceptance of the secondary battery. It can be kept at, and the effect of deceleration regeneration can be obtained.
Further, since the reduction coefficient of the lower limit charge rate is larger than that of the normal mode and the charge mode is larger than that of the save mode, the acceptance of the secondary battery at the time of large deceleration regeneration from high load operation and high speed operation is improved. As shown in FIG. 4, the lower the SOC, the larger the deceleration regeneration can be accepted. Therefore, in the save mode in which the reduction coefficient of the lower limit charge rate becomes larger and the charge mode in which the lower limit charge rate becomes larger, it is possible to receive a larger deceleration regeneration by lowering the lower limit charge rate than in the normal mode, and it is possible to improve fuel efficiency. ..

According to at least one embodiment of the present invention, in the power supply device of an electric vehicle including a fuel cell and a secondary battery, the required output on the vehicle side is limited to the maximum efficiency output of the fuel cell or less, so that the secondary battery Since power consumption is suppressed and the power generation output of the fuel cell is maintained in the maximum efficiency output state, the fuel cell fuel efficiency can be improved, so that it is suitable for use in an electric vehicle equipped with a fuel cell and a secondary battery. ..

1 Electric vehicle 3 Power supply 5 Fuel cell 7 Secondary battery 9 Motor 13 DC-DC converter 15 Inverter 17 Control device 19 Vehicle status sensor 21 Driving mode selection switch 23 Secondary battery control unit 25 Motor control unit 26 Vehicle request output calculation unit 27 Vehicle control unit 28 Vehicle output limiting unit 29 Fuel cell control unit 31 Charging state detecting means 32 Charging notification means 33 Power generation control unit

Claims (4)

In a power supply device of an electric vehicle including a fuel cell that generates electricity by receiving the supply of hydrogen and oxygen and a secondary battery that charges the electric power generated by the fuel cell.
A fuel cell control unit that controls power generation of the fuel cell based on information from the charging state detecting means for detecting the charging state of the secondary battery is provided.
The fuel cell control unit generates electricity at the maximum efficiency output when the charging state falls below the lower limit charging rate, and stops power generation of the fuel cell when the charging rate reaches a target charging rate higher than the lower limit charging rate. Has a power generation control unit
When the fuel cell is generating power with the maximum efficiency output by the power generation control unit, the fuel cell is provided with a vehicle output limiting unit that limits the vehicle required output indicating the required power on the vehicle side to the maximum efficiency output or less. Power supply for electric vehicles. The power supply device for an electric vehicle according to claim 1, wherein the vehicle output limiting unit limits the vehicle required output so as to match the maximum efficiency output of the fuel cell. The fuel cell control unit is characterized in that when the output obtained by subtracting the vehicle required output from the maximum efficiency output of the fuel cell exceeds the power received by the secondary battery, the power generation of the fuel cell is stopped regardless of the target charge rate. The power supply device for an electric vehicle according to claim 1 or 2. The electric vehicle includes a mode selection means for selecting a traveling mode, and when the "super charge mode" for maintaining a predetermined charge rate is selected by the mode selection means, the power generation control unit performs the "super charge mode". The target charge rate is set as the target charge rate, and the fuel cell control unit determines the output of the fuel cell when the output obtained by subtracting the vehicle required output from the maximum efficiency output of the fuel cell exceeds the power received by the secondary battery. The power supply device for an electric vehicle according to claim 1, wherein the secondary battery is charged by limiting the total value of the vehicle required output and the power received by the secondary battery.

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