JP6926547B2 - 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.

Therefore, in view of the above technical problems, at least one embodiment of the present invention sets the lower limit value and the lower limit value of power generation at the maximum efficiency output of the fuel cell in the power supply device of the electric vehicle including the fuel cell and the secondary battery. The purpose is to improve the fuel efficiency of the fuel cell by performing the operation between the target value and the value larger than the value.

(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, a charging state detecting means for detecting the charging state of the secondary battery, a fuel cell control unit for controlling the power generation of the fuel cell based on the charging state from the charging state detecting means, and the like. When the charging state falls below the lower limit charging rate, the fuel cell control unit generates power of the fuel cell at the maximum efficiency output, and when the charging state reaches a target charging rate higher than the lower limit charging rate, the fuel cell generates power. It is characterized by having a power generation control unit for stopping.

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.
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, 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 between them. Compared to controlling power generation with the highest efficiency output, the number of response to the start and stop of power generation is reduced, so deterioration of the fuel cell is suppressed.

(2) In some embodiments, the power generation control unit increases the target charge rate as the negative time change of the charge rate increases, and prolongs the power generation time of the fuel cell with the maximum efficiency output. It is characterized by that.

According to the above configuration (2), the power generation control unit increases the target charge rate as the negative time change of the charge rate increases, that is, as the decrease tendency of the charge rate increases, and the maximum efficiency output is obtained. Since the power generation time of the fuel cell is lengthened, the charge rate of the secondary battery can be maintained at the lower limit charge rate while improving the fuel efficiency of the fuel cell.

Further, the negative time change of the charge rate becomes large during high load operation and high speed operation. In this case, by increasing the target charge rate and maintaining the charge rate of the secondary battery high. It is possible to prevent the secondary battery from running out of electricity.
Further, by preventing the secondary battery from running out of power, the output of the fuel cell in the emergency mode in which the fuel cell is generated at the maximum output, that is, with low efficiency is prevented, and the deterioration of fuel consumption can be suppressed. Similarly, by preventing the fuel cell from falling below the lower limit SOC ( _{including SOC SAVE} and SOC _CHARGE ), the fuel cell is output by feeding back the SOC deviation, that is, low-efficiency power generation due to an output larger than the maximum efficiency output is prevented. It is possible to suppress the deterioration of fuel efficiency.

(3) In some embodiments, in some embodiments, the power generation control unit controls the power generation of the fuel cell so as to maintain the lower limit charge rate and increase the target charge rate. It is characterized in that the traveling mode of "" is provided.

According to the above configuration (3), in the "normal mode", the lower limit charge rate is maintained, the target charge rate is further increased, and the power generation time of the fuel cell by the maximum efficiency output is lengthened, so that the fuel efficiency of the fuel cell is improved. The charging rate of the secondary battery can be maintained at the lower limit charging rate.

(4) In some embodiments, the electric vehicle includes a mode selection means for selecting a traveling mode, and the mode selection means selects a "save mode" for maintaining the charge rate of the secondary battery at the time of selection. In this case, the power generation control unit sets the charge rate when the "save mode" is selected as the lower limit charge rate, and increases the increase coefficient of the target charge rate as compared with the case of the "normal mode". It is a feature.

According to the above configuration (4), when the "save mode" is selected by the driving mode selection means, the increase coefficient of the target charge rate is larger than that when the driving mode is the "normal mode", so that the "normal mode" is used. Since the target charge rate is larger than in the case of "" and the power generation time due to the maximum efficiency output of the fuel cell is longer, the lower limit charge rate of the "save mode" can be maintained while improving the fuel efficiency of the fuel cell.
Also, in the save mode, where the increase coefficient of the target charge rate is large, the SOC is kept higher by raising the target charge rate than in the normal mode, which prevents the secondary battery from running out of power during subsequent high-load operation. Will be done.

(5) In some embodiments, when the "charge mode" for maintaining the predetermined charge rate is selected by the mode selection means, the power generation control unit sets the predetermined charge rate of the "charge mode". The lower limit charge rate is set, and the increase coefficient of the target charge rate is made larger than in the case of the "save mode".

According to the above configuration (5), when the "charge mode" is selected by the driving mode selection means, the increase coefficient of the target charge rate is larger than that when the driving mode is the "save mode", so that the "save mode" is used. Since the target charge rate is larger than in the case of "" and the power generation time due to the maximum efficiency output of the fuel cell is longer, the lower limit charge rate of the "charge mode" can be maintained while improving the fuel efficiency of the fuel cell.
Further, as in the case of the save mode described above, in the charge mode, the increase coefficient of the target charge rate becomes large, so that the SOC is held higher, so that the secondary battery in the subsequent high load operation The power shortage is prevented.

(6) 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 (6), when the output obtained by subtracting the vehicle required output from the maximum efficiency output of the fuel cell exceeds the received power of 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.

(7) 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 increases the target charge rate with the predetermined charge rate in the "super charge mode" as the lower limit charge rate, and the fuel cell control unit subtracts the vehicle required output from the maximum efficiency output of the fuel cell. When the output exceeds the power received by the secondary battery, the output of the fuel cell is limited to the total value of the required output of the vehicle and the power received by the secondary battery, and the secondary battery is charged.

According to the above configuration (7), when the "super charge mode" is selected by the mode selection means, the fuel cell control unit uses the secondary battery as the output obtained by subtracting the vehicle required output from the maximum efficiency output of the fuel cell. 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 a power supply device for an electric vehicle including a fuel cell and a secondary battery, power generation at the maximum efficiency output of the fuel cell has a lower limit value and a target value larger than the lower limit value. By performing the operation in between, it is possible to improve the fuel efficiency as compared with the one that controls the operation of the maximum efficiency output with the charging rate of a predetermined constant value as a boundary.

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 of "normal mode control" in FIG. It is a control flowchart of "emergency mode control" in FIG. It is a control flowchart of "save mode control" in FIG. It is a control flowchart of "charge mode control" in FIG. It is a control flowchart of "super charge mode control" in FIG. It is a control flowchart in the fuel cell control part of the power supply device of the electric vehicle which concerns on another embodiment of this invention.

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.

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. The vehicle request output including the vehicle is calculated, and the vehicle request output is output to the motor control unit 25 and the fuel cell control unit 29 described later.
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 to 11.

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 increases the target 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. Is controlled to be long. In this way, since the target charge rate is increased and the power generation time of the fuel cell with the maximum efficiency output is lengthened, the charging time with 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.

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 ≦ 30% [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, and SOC ≧ (lower limit SOC + A) [target SOC. ], The power generation of the fuel cell 5 is stopped.

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 increase increases as the negative temporal change of SOC increases. For example, when SOC <30%, it is calculated based on the time change of the deviation between the current SOC and SOC 30%, that is, (SOC (current) -SOC (30%)) / dt.

After starting the power generation of the maximum efficiency output Ps, predetermined conditions (for example, when the elapsed power generation time of the maximum efficiency output Ps is a certain time or more and the vehicle required output such as the amount of depression of the accelerator pedal is a certain value or more) are satisfied. If it is established and the current SOC is less than the lower limit SOC, the deviation between the current SOC and the lower limit SOC is fed back to increase the output of the fuel cell 5 from the maximum efficiency output Ps and the maximum efficiency output Ps. Suspend the power generation of a certain value. When the lower limit SOC is reached, power generation at the maximum efficiency output Ps is restarted again.

Control table No. 4 indicates a "save mode". _{This "save mode" is a mode in which the SOC SAVE} is maintained 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 [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 + B%) [target SOC], or when (maximum efficiency output Ps of fuel cell 5-vehicle required output) ≥ secondary battery received power, the fuel cell 5 regardless of the target SOC. Stop the power generation.

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 increase increases as the negative temporal change of SOC increases. For example, when SOC <SOC _SAVE , it is calculated based on the time change of the deviation between the current SOC and SOC _SAVE , that is, (SOC (current) -SOC _{SAVE) / dt.} In the case of the "save mode", the feedback coefficient (increase coefficient) is set larger than that in the "normal mode".

In the "save mode" as well as the "charge mode", when the predetermined conditions are satisfied and the current SOC is _{less than the SOC SAVE} (lower limit SOC) after the power generation of the maximum efficiency output Ps is started. _{Feeds back} the deviation between the current SOC and SOC SAVE to increase the output of the fuel cell 5 from the maximum efficiency output Ps and interrupt the power generation of a constant value of the maximum efficiency output Ps. When the lower limit SOC is reached, power generation at the maximum efficiency output Ps is restarted again.

Control table No. 5 indicates a "charge mode". This "charge mode" is _{a mode for maintaining a predetermined SOC CHARGE} (for example, 80%). For example, when the “charge mode” is selected and SOC ≦ SOC _CHARGE [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 _CHARGE + C%) [target SOC], or when (maximum efficiency output Ps of fuel cell 5-vehicle required output) ≥ secondary battery received power, the fuel cell 5 regardless of the target SOC. Stop the power generation. The secondary battery received power is calculated based on the characteristics shown in FIG.

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

As in the "save mode", the "charge mode" is also the same as the "save mode" when the predetermined conditions are satisfied after the power generation of the maximum efficiency output Ps is started and the current SOC is _{less than the SOC CHARGE} (lower limit SOC). _{Feeds back} the deviation between the current SOC and SOC CHARGE, increases the output of the fuel cell 5 from the maximum efficiency output Ps, and interrupts power generation at a constant value of the maximum efficiency output Ps. When the lower limit SOC is reached, power generation at the maximum efficiency output Ps is restarted again.

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 the “supercharge mode” is selected and SOC ≦ SOC _CHARGE [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 _CHARGE + D%) [target SOC], the power generation of the fuel cell 5 is stopped.

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 increase increases as the negative temporal change of SOC increases. For example, when SOC <SOC _CHARGE , it is calculated based on the time change of the deviation between the current SOC and SOC _CHARGE , that is, (SOC (current) -SOC _{CHARGE) / dt.} 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 (increase 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.

In the "super charge mode" as well as the "charge mode", when the predetermined conditions are satisfied after the power generation of the maximum efficiency output Ps is started and the current SOC is _{less than the SOC CHARGE} (lower limit SOC). The output of the fuel cell 5 is increased from the maximum efficiency output Ps by feeding back the deviation between the current SOC and the SOC _{CHARGE, and the power generation of a constant value of the maximum efficiency output Ps is interrupted.} When the lower limit SOC is reached, power generation at the maximum efficiency output Ps is restarted again.

Next, the control flowchart in the fuel cell control unit 29 will be described with reference to the flowcharts of FIGS. 5 to 10.
FIG. 5 shows the entire control flowchart. In FIG. 5, first, in step S1, the SOC of the secondary battery 7 is read, and in step S2, 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 S3. In step S3, 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, 30% SOC. In step S3, in the case of Yes, the process proceeds to step S4, and in step S4, 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 S4 is No, the normal mode control is executed, and if the determination in step S4 is Yes, the emergency mode control is executed.
On the other hand, if the determination in step S3 is No, the process proceeds to step S7, and the power generation of the fuel cell 5 is stopped.

Here, returning to step S2, if the travel mode selection switch 21 is operated and a predetermined travel mode is selected in the determination of step S2, the process proceeds to step S9 and the selected travel mode is saved. Whether it is a mode or not is determined. In the case of Yes in step S9, the process proceeds to step S10 to execute the save mode control, and in the case of No in step S9, the process proceeds to step S11 to determine whether or not the charge mode is used.

If Yes in step S11, the charge mode control is executed in step S12, and if No in step S11, the process proceeds to step S13 to determine whether or not the supercharge mode is in effect.

If Yes in step S13, the process proceeds to step S14 to execute supercharge mode control, and if No in step S13, the process returns to step S9 and the determination of the traveling mode is repeated again.

Next, "normal mode control" in step S5, "emergency mode control" in step S6, "save mode control" in step S10, "charge mode control" in step S12, and "supercharge mode control" in step S14, 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 S21, the fuel cell 5 is generated with the maximum efficiency output Ps in step S22, and the negative time change of SOC is calculated in step S23.
For example, when SOC <30%, it is calculated based on the time change of the deviation between the current SOC and SOC 30%, that is, (SOC (current) -SOC (30%)) / dt.

Next, in step S24, the target SOC is increased according to the magnitude of the negative time change of the SOC, that is, as the negative time change becomes larger. The target SOC is calculated as the lower limit SOC + A%, and the increase amount A% is set based on the negative time change of the SOC calculated in step S23. For example, it is calculated as A = (SOC (current) -SOC (30%)) / dt × K (increase coefficient). By changing the increase 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 S25, it is determined whether or not the SOC has reached the target SOC increased in step S24, and if it reaches, it becomes Yes, FC power generation is stopped in step S26, and the process ends in step S27. If No in step S25, the process returns to step S22 and is repeated.

As described above, according to the normal mode control, power generation is started at the lower limit SOC (30%), and when the SOC is further decreasing, the target SOC is increased to obtain the fuel cell 5 having the highest efficiency output Ps. Since the power generation time is lengthened, the charge rate of the secondary battery 7 can be maintained without being lowered from the lower limit SOC (30%) while improving the fuel efficiency of the fuel cell.

FIG. 7 shows a flowchart of emergency mode control.
When the emergency mode control is started in step S31, the fuel cell 5 generates power at the maximum output Pmax in step S32, and in step S33, the SOC is larger than the second lower limit value (15%) and the first lower limit value (30). %) Is smaller than the third lower limit (20%). When it reaches, it becomes Yes and ends in step S34, 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 S4, 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 S41, it is determined in step S42 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 S43 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 S44. Similar to the case of the normal mode, for example, _{when SOC <SOC SAVE} , it is calculated based on the time change of the deviation between the current SOC and SOC _SAVE , that is, (SOC (current) -SOC _{SAVE) / dt.}

Next, in step S45, the target SOC is increased according to the magnitude of the negative time change of the SOC. The target SOC is _{calculated as SOC SAVE} + B%, and the increase amount B% is set based on the negative time change of SOC calculated in step S44. For example, it is calculated as B = (SOC (current) -SOC _SAVE ) / dt × K (increase coefficient). The increase coefficient K is set to be larger than in the normal mode.

Next, in step S46, it is determined whether or not the SOC has reached the increased target SOC in step S45, and if it reaches, it becomes Yes, FC power generation is stopped in step S47, and the process ends in step S50. If No in step S46, the process proceeds to step S48, and in step S48, 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 S47 to stop FC power generation and end in step S50. As a result, the secondary battery 7 is prevented from being overcharged, and power generation at the highest efficiency output Ps is stopped to improve fuel efficiency.

_{On the other hand, if the SOC is not equal to or less than the SOC SAVE} in step S42, the result is No, and the process proceeds to step S49 to stop FC power generation and end in step S50.

In this way, according to the save mode control, the increase coefficient of the target SOC is made larger than in the case of the "normal mode", so that the power generation time by the maximum efficiency output Ps is longer than in the case of 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 a flowchart of 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 _{lower limit SOC is SOC SAVE in the save mode control.} In mode control, the lower limit SOC is SOC _CHARGE .

When the charge mode control is started in step S61, it is determined in step S62 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 S63 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 S64. As in the case of the save mode, for example, _{when SOC <SOC CHARGE} , it is calculated based on the time change of the deviation between the current SOC and SOC _CHARGE , that is, (SOC (current) -SOC _{CHARGE) / dt.}

Next, in step S65, the target SOC is increased according to the magnitude of the negative time change of the SOC. The target SOC is _{calculated as SOC CHARGE} + C%, and the increase amount C% is set based on the negative time change of SOC calculated in step S64. For example, it is calculated as C = (SOC (current) -SOC _CHARGE ) / dt × K (increase coefficient). The increase coefficient K is set to be larger than in the save mode.

Next, in step S66, it is determined whether or not the SOC has reached the increased target SOC in step S65, and if it reaches, it becomes Yes, FC power generation is stopped in step S67, and the process ends in step S70. If No in step S66, the process proceeds to step S68, and in step S68, 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 S67 to stop FC power generation and end in step S50. As a result, the secondary battery 7 is prevented from being overcharged, and power generation at the maximum efficiency output is stopped to improve fuel efficiency.

_{On the other hand, if the SOC is not equal to or less than the SOC CHARGE} in step S62, the result is No, and the process proceeds to step S69 to stop FC power generation and end in step S70.

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

FIG. 10 shows a flowchart of 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 S82 to S88 of the supercharge mode of FIG. 10 are the same as steps S62 to S68 of the charge mode of FIG. Part A of step S89 in FIG. 10 is different.

That is, in the charge mode control of FIG. 9, FC power generation was stopped in the case of Yes in step S48, but in this supercharge mode control, the process proceeds to step S89 in the case of Yes in step S68, and FC power generation is not stopped. The output is limited to the above, and power generation is continued to secure the charge to the secondary battery 7.
Therefore, in the supercharge mode, although the fuel consumption of the fuel cell 5 is worse than that in the charge mode of FIG. 9, the secondary battery 7 is charged so as to achieve the target SOC while preventing overcharging. ..

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, since 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, the charging rate is a predetermined constant value. Since the operation response of the start and stop of power generation is reduced as compared with the control of power generation by the maximum efficiency output at the boundary of the above, the deterioration of the fuel cell 5 is suppressed.

In the present embodiment, the lower limit SOC corresponds to SOC 30% in normal mode control, SOC _{SAVE in save mode control, and SOC CHARGE} in charge mode control and supercharge mode control.
The target SOC corresponds to the lower limit SOC + A% in normal mode control, SOC _SAVE + B% _{in save mode control, SOC CHARGE} + C% in charge mode control, and SOC _CHARGE + D in supercharge mode control. % Equivalents.

Then, according to the present embodiment, as the negative time change of the SOC increases, the target charge rate is increased to prolong the power generation time of the fuel cell 5 by the maximum efficiency output Ps, so that the fuel cell 5 is improved in fuel efficiency. It is possible to maintain each SOC corresponding to the above lower limit SOC while trying to achieve the above.

The large negative time change of the charge rate occurs during high-load operation and high-speed operation. In this case, by increasing the target charge rate and maintaining the charge rate of the secondary battery high, 2 It is possible to prevent the power shortage of the next battery.
Further, by preventing the secondary battery from running out of power, the output of the fuel cell in the emergency mode in which the fuel cell is generated at the maximum output, that is, with low efficiency is prevented, and the deterioration of fuel consumption can be suppressed. Similarly, by preventing the fuel cell from falling below the lower limit SOC ( _{including SOC SAVE} and SOC _CHARGE ), the fuel cell is output by feeding back the SOC deviation, that is, low-efficiency power generation due to an output larger than the maximum efficiency output is prevented. It is possible to suppress the deterioration of fuel efficiency.

In addition, the increase coefficient of the save mode is larger than that of the normal mode, and the charge mode and the target charge rate are larger than those of the save mode, so that the SOC is held higher, and the secondary battery 7 in the subsequent high load operation Power shortage is prevented.

Next, another embodiment of the present invention is shown in FIG.
FIG. 11 calculates the vehicle request output in step S101 before the start of the control of one embodiment shown in FIG. For example, based on the signals from the vehicle speed sensor, the sensor that detects the depression amount (acceleration) of the accelerator pedal, and the like, the vehicle required output including the power consumption of the fuel cell 5 auxiliary machine and the vehicle auxiliary machine is calculated.
Next, in step S102, it is determined whether the vehicle required output is larger than (maximum output of the secondary battery 7 + current FC output). If the determination result is large and Yes, the process proceeds to step S103, and the FC output is set to (vehicle required output-maximum output of the secondary battery 7).

On the other hand, when the determination result in step S102 is No, the process proceeds to step S1 of the flowchart of one embodiment shown in FIG. 5, and the control of steps S1 to S14 in FIG. 5 is executed. In the case of the flowchart of FIG. 5, the final return destination is step S101.

In this embodiment, No. 1 in the control table shown in FIG. It corresponds to the assist mode control of 2. That is, when the vehicle required output> (maximum output of the secondary battery 7 + current FC output), the FC output is controlled in the range of Pmin to Pmax and the output of the secondary battery 7 in the case of sudden acceleration or the like. Can be supplemented.

According to at least one embodiment of the present invention, in a power supply device for an electric vehicle including a fuel cell and a secondary battery, power generation at the maximum efficiency output of the fuel cell has a lower limit value and a target value larger than the lower limit value. By performing this in between, it is possible to improve fuel efficiency as compared with the one that controls the operation of the maximum efficiency output with a predetermined constant value charging rate as a boundary, so that it is suitable for use in an electric vehicle.

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 27 Vehicle control unit 29 Fuel Battery control unit 31 Charging state detecting means 33 Power generation control unit

Claims (6)

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 charging state detecting means for detecting the charging state of the secondary battery, and
A fuel cell control unit that controls power generation of the fuel cell based on the charge state from the charge state detecting means 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. the power generation control unit possess,
The power generation control unit increases the target charge rate as the negative time change of the charge rate increases to prolong the power generation time of the fuel cell by the maximum efficiency output.
If the current charge rate is less than the lower limit charge rate after starting the power generation of the maximum efficiency output, the deviation between the current charge rate and the lower limit charge rate is fed back to output the output of the fuel cell to the maximum efficiency output. A power source for an electric vehicle , which comprises increasing power generation, interrupting power generation at the maximum efficiency output, and restarting power generation at the maximum efficiency output when the current charge rate reaches the lower limit charge rate. Device. The electric vehicle is provided with a "normal mode" driving mode in which the power generation of the fuel cell is controlled so as to maintain the lower limit charge rate and increase the target charge rate by the power generation control unit. The power supply device for an electric vehicle according to claim 1. The electric vehicle includes a mode selection means for selecting a traveling mode, and when the mode selection means selects a "save mode" for maintaining the charge rate of the secondary battery at the time of selection, the power generation control unit The electric motor according to claim 2 , wherein the charge rate when the "save mode" is selected is set as the lower limit charge rate, and the increase coefficient of the target charge rate is made larger than that in the case of the "normal mode". Vehicle power supply. When the "charge mode" for maintaining the predetermined charge rate is selected by the mode selection means, the power generation control unit sets the predetermined charge rate of the "charge mode" as the lower limit charge rate and sets the "save mode". The power supply device for an electric vehicle according to claim 3 , wherein the increase coefficient of the target charge rate is made larger than that in the case of. 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 any one of claims 1 to 4. 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". When the target charge rate is increased with the predetermined charge rate of "" as the lower limit charge rate, and 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 output of the fuel cell by limiting the sum of the vehicle request output and the secondary battery receiving power, the power supply device for an electric vehicle according to claim 1, characterized in that charging the secondary battery.

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