JPWO2016151697A1 - Vehicle power control device - Google Patents

Abstract

In the power control device 2 of the vehicle 1 that supplies power from the battery 6 and the fuel cell 8 mounted on the vehicle to the electric motor 3 for driving driving, the control unit 22 starts power generation of the fuel cell 8, Based on the deviation ΔSOC obtained by setting the target charging rate SOCt of the battery 6 so as to decrease as the remaining fuel amount Qf of the fuel cell 8 decreases and subtracting the current charging rate SOC from the target charging rate SOCt. Then, the power generation output Pf of the fuel cell 8 is controlled. When the power generation output Pf is controlled, the change rate of the power generation output Pf with respect to the deviation ΔSOC increases as the deviation ΔSOC increases with a positive value.

Description

  The present invention relates to a power generation control technique for a power generation unit mounted on a vehicle that is driven to travel by an electric motor.

In an electric vehicle that travels by driving an electric motor with electric power supplied from an in-vehicle battery, a vehicle equipped with a range extender that is a power generation unit has been developed. A range extender is composed of a small power generation engine and a generator, for example, and increases the cruising range of an electric vehicle by supplying the generated power to an electric motor or using it for charging an in-vehicle battery. be able to.
By the way, in recent years, development of fuel cells has progressed, and vehicles equipped with fuel cells have been proposed. Furthermore, vehicles that use fuel cells instead of engines have been proposed as range extenders for electric vehicles.
For example, in Patent Document 1, in a vehicle equipped with a fuel cell, the fuel cell and the battery are supplied to an electric motor as a power supply source to drive a drive wheel so that the vehicle can run. Further, Patent Document 1 discloses a technique for controlling the output of the fuel cell so that the battery charge rate (SOC) is maintained at a target charge rate set close to the lower limit after the battery power is used. Has been.

Japanese Patent No. 5101583

In the vehicle disclosed in Patent Document 1, electric power is supplied from the battery to the electric motor until the battery charging rate reaches the target charging rate, and when the battery charging rate falls below the target charging rate, The output from the fuel cell is controlled based on the deviation between the current charging rate of the battery and the target charging rate so as to cover the power used by the motor or the like and maintain the target charging rate.
However, if the power consumption of the vehicle changes due to, for example, an accelerator operation, and the battery charging rate fluctuates in the vicinity of the target charging rate, the generated power is also changed. The fluctuation of power reduces the efficiency of a power generation unit such as a fuel cell. And since the fuel of the electric power generation unit mounted in a vehicle is limited, the fall of the efficiency of an electric power generation unit will reduce the cruising range of a vehicle as a result. Further, when the charging rate of the battery fluctuates so as to increase or decrease the target charging rate, power generation is turned on / off, and there is a problem that the life of the fuel cell is reduced.

  The present invention has been made to solve such a problem, and an object of the present invention is to provide a power control device for a vehicle that controls a power generation unit such as a fuel cell to output efficiently and increases a cruising distance. It is to provide.

In order to achieve the above object, a power control device for a vehicle according to the present invention is a power control device for a vehicle that supplies power from a power generation unit that consumes fuel and a power generation to an electric motor for driving. A fuel remaining amount detection unit that detects a remaining fuel amount of the power generation unit, a charge rate detection unit that detects a current charging rate of the battery, and a power generation control unit that controls a power generation output of the power generation unit. The power generation control unit calculates the power generation output based on a deviation between a target charging rate calculated based on the fuel remaining amount and the current charging rate.
Preferably, the power generation control unit increases the power generation output as the deviation increases when the deviation obtained by subtracting the current charging rate from the target charging rate becomes a positive value. The power generation output may be calculated as described above.

Preferably, when the deviation obtained by subtracting the current charging rate from the target charging rate becomes a positive value, the power generation control unit changes the power generation output rate as the deviation increases. The power generation output may be calculated so that the value increases.
Preferably, the power generation control unit maintains the power generation output as a constant value without stopping power generation even when the deviation obtained by subtracting the current charging rate from the target charging rate is 0 or less.
Preferably, the power generation unit is a fuel cell.

  According to the vehicle power control device of the present invention, the power generation output of the power generation unit is calculated based on the deviation between the target charge rate calculated based on the remaining fuel amount and the current charge rate. Accordingly, the target charging rate is set to gradually decrease. Therefore, power can be generated before the battery drops to the final target charging rate, and even if the vehicle power consumption fluctuates and temporarily increases, the output from the battery increases and the power generation output of the power generation unit fluctuates. Can be suppressed. This can improve the efficiency of the power generation unit, increase the power generation amount of the power generation unit with limited fuel, increase the cruising range of the vehicle, and improve the life of the power generation unit Can do.

It is a schematic block diagram of the drive system of the electric vehicle which concerns on one Embodiment of this invention. It is an output gain calculation map. It is a graph which shows an example of transition of the charging rate of a battery at the time of vehicles running of this embodiment, fuel residual quantity, and power generation output.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 is a schematic configuration diagram of a drive system of a vehicle 1 according to an embodiment of the present invention.
A vehicle 1 that employs a power control device 2 according to an embodiment of the present invention is an electric vehicle that drives left and right traveling drive wheels 5 via a differential 4 by an electric motor 3.
The vehicle 1 is equipped with a battery 6 and a fuel cell 8 as a power supply device that supplies electric power to the electric motor 3 for driving.

The fuel cell 8 generates electricity using hydrogen stored in a fuel tank 9 mounted on the vehicle 1 as fuel. The electric power generated by the fuel cell 8 is supplied to the primary side of the DC-DC converter 10 to be boosted, and can be supplied from the secondary side of the DC-DC converter 10 to the electric motor 3 via the inverter 11. Yes. The battery 6 can supply power to the electric motor 3 via the inverter 11.
The fuel cell 8 and the battery 6 via the DC-DC converter 10 are connected in parallel, and surplus power output from the fuel cell 8 is supplied to the battery 6 to charge the battery 6. Further, when the power output from the power generation unit 7 is insufficient with respect to the power required for driving the electric motor 3, the power is supplied from the battery 6.

The vehicle 1 is equipped with a charger 12. The charger 12 is an AC-DC converter, which converts an AC voltage supplied from an external power supply through an outlet 13 into a direct current, and supplies the direct current to the battery 6 to charge the battery 6.
The fuel tank 9 is provided with a fuel remaining amount detector 20 (fuel remaining amount detecting unit) for detecting the remaining amount of fuel (remaining amount of hydrogen). Further, the battery 6 is provided with a battery monitoring unit 21 (charge rate detection unit) that monitors the charge rate of the battery 6.

  The control unit 22 (power generation control unit) includes a CPU (Central Processing Unit), a storage device (ROM, RAM), an input / output interface, and the like. The monitoring unit 21 inputs other vehicle operation information such as the charging rate of the battery 6, the amount of accelerator operation of the vehicle 1, and operation information of in-vehicle devices such as an air conditioner, and performs operation control of the electric motor 3 through the inverter 11. Then, output control of the fuel cell 8 is performed via the DC-DC converter 10.

  The control unit 22 performs power generation start determination for determining the high output / high speed travel state of the vehicle 1 during vehicle travel. The control unit 22 sequentially calculates the vehicle power consumption that is the sum of the power consumption of the electric motor 3 and the power consumption of other in-vehicle devices, and smoothes the vehicle power consumption using a filter or the like to obtain a vehicle speed change equivalent value. . Then, when this vehicle speed change equivalent value continues for a predetermined time Ta or more and exceeds a predetermined threshold value Va set in advance, it is determined that the vehicle 1 is in a high output / high speed running state (power generation start determination). )do. The predetermined threshold value Va and the predetermined time Ta may be appropriately set to values that can determine that the output state from the fuel cell 8 is in a high output / high speed running state. Even if the vehicle power consumption continues for a predetermined time Ta or more and does not exceed the threshold value Va, if the charging rate of the battery 6 reaches the ultimate target charging rate SOCb described later, the power generation start determination is also made at that time.

Further, after the power generation start determination is made, the control unit 22 calculates and controls the power generation output Pf of the fuel cell 8 every predetermined calculation cycle (for example, several milliseconds) (power generation control unit). The power generation output Pf is calculated by the following equation (1).
Pf = α × (SOCt−SOC) (1)
In Equation (1), SOC is the current charging rate of the battery 6 input from the battery monitoring unit 21. SOCt is a target charging rate, and is calculated for each predetermined calculation period together with equation (1) by the following equation (2). α is an output gain, and is calculated using a map shown in FIG. 2 as described later.
SOCt = SOCb + (SOCa−SOCb) × {(Qf−Qfb) / (Qfa−Qfb)} (2)

  In Equation (2), SOCa is a charging rate at the start, and is used by storing the charging rate of the battery 6 when the power generation start determination is made. The SOCb is an attainment target charging rate, which is a charging rate of the battery 6 that is required at least when the vehicle 1 finishes traveling, and is set to a positive value close to 0, for example. Qf is the current remaining fuel amount input from the remaining fuel amount detector 20, and Qfa is the starting fuel amount. The starting fuel remaining amount Qfa is used by storing the fuel remaining amount when the power generation start determination is made. Qfb is an attainment target fuel remaining amount, which is at least the remaining amount of fuel required when the vehicle 1 finishes traveling. The target fuel remaining amount Qfb is set to a positive value close to 0, for example.

FIG. 2 is a map for calculating the output gain α.
The control unit 22 calculates the output gain α from the deviation between the target charge rate SOCt and the current charge rate SOC using the calculation map shown in FIG.
The control unit 22 calculates a target charge rate deviation ΔSOC (= SOCt−SOC) by subtracting the current charge rate SOC from the target charge rate SOCt obtained by the equation (2). As shown in FIG. 2, when the target charging rate deviation ΔSOC is 0 or less, that is, when the current charging rate SOC is equal to or higher than the target charging rate SOCt, the output gain α is set to a predetermined value α1. The predetermined value α1 is a constant that is set so that the power generation output Pf calculated in the equation (1) is near the lower limit within the range in which the fuel cell 8 outputs efficiently.

When the target charging rate deviation ΔSOC is larger than 0, that is, when the current charging rate SOC is lower than the target charging rate SOCt, the output gain increases as the target charging rate deviation ΔSOC increases between the predetermined value α1 and the maximum value αmax. It is set so that α increases and the rate of change also increases. For example, the secondary degree of the target charging rate deviation ΔSOC may be set to be proportional to the output gain α between the predetermined value α1 and the maximum value αmax. The maximum value αmax may be set to a value such that the power generation output Pf does not exceed the maximum output of the fuel cell 8.
FIG. 3 is a graph showing an example of changes in the battery charge rate SOC, the remaining fuel amount Qf, and the power generation output Pf when the vehicle travels according to this embodiment.

In FIG. 3, from the state where the charging rate SOC of the battery 6 is 100% and the remaining amount of fuel is a value Qfa close to 100%, the vehicle 1 starts running and the maximum possible running is completed (A ) Shows the transition of the charging rate SOC of the battery 6, (B) the remaining fuel amount Qf, and (C) the power generation output Pf of the fuel cell 8. In FIG. 3, the solid line is the present embodiment in which the power generation output Pf is set using the above formulas (1) and (2), and the broken line indicates the transition in the comparative example. In addition, a two-dot chain line in FIG. 3A indicates a transition of the target charging rate SOCt set in the present embodiment.
In the comparative example described in FIG. 3, the electric motor 3 is driven only by the electric power from the battery 6 until the charging rate SOC of the battery 6 reaches the reaching target charging rate SOCb, and the reaching target is reached after reaching the reaching target charging rate SOCb. Electric power is supplied from the fuel cell 8 based on the deviation between the current charging rate SOC and the target reaching charging rate SOCb so as to maintain the charging rate SOCb.

On the other hand, in the present embodiment, as described above, even if the charging rate SOC of the battery 6 does not decrease to the target charging rate SOCb, the vehicle 1 is in a high output / high speed running state and the vehicle power consumption is equal to or longer than the predetermined time Ta. If the threshold value Va is continuously exceeded, power generation start determination is made and power generation of the fuel cell 8 is started. Therefore, power generation is started earlier than in the comparative example in a high output / high speed running state. By starting power generation early in this way, the output of the fuel cell 8 can be suppressed, and the shortage relative to the vehicle power consumption is compensated by the output from the battery 6.
After the power generation is started, the target charge rate SOCt is set to decrease as the fuel remaining amount Qf decreases, and the fuel remaining amount Qf reaches the target fuel remaining amount Qfb and the target charge rate SOCt is The target charging rate SOCt is set so that the reaching target charging rate SOCb is reached at the same time. Since the power generation output Pf is calculated based on the deviation between the target charge rate SOCt and the current charge rate SOC, the feedback control is accurately performed so that the charge rate SOC matches the target charge rate SOCt.

  Since the target charging rate SOCt is gradually lowered as the remaining fuel amount Qf decreases and is controlled so as to reach the reaching target charging rate SOCb at the same time as the remaining fuel amount Qf reaches the reaching target fuel remaining amount Qfb. The actual charging rate SOC of the battery 6 also reaches the target charging rate SOCb at substantially the same time as the target charging rate SOCt. Therefore, the distance that the vehicle 1 can travel from the state in which the charging rate of the battery 6 is 100% and the remaining fuel amount is the starting fuel remaining amount Qfa to the ultimate target charging rate SOCb and the remaining fuel amount Qfb can be traveled to the maximum. The cruising range. In this embodiment, the fuel cell 8 outputs until the fuel remaining amount Qf reaches the target fuel remaining amount Qfb, and the target charge rate SOCt is gradually decreased as the fuel remaining amount Qf decreases, thereby generating power. It is possible to secure a power generation time from the start to the end of travel and to suppress the output of the fuel cell 8.

In the comparative example, since the charging rate SOC of the battery 6 has already reached the attainment target charging rate SOCb after the start of power generation, it is difficult to increase the output from the battery 6, and thus when the vehicle power consumption greatly increases. The output from the fuel cell 8 must be greatly increased in accordance with the fluctuation. On the other hand, in this embodiment, since the charging rate SOC exceeds the ultimate target charging rate SOCb in the period from the start of power generation to the end of travel, even if the vehicle power consumption temporarily increases, The output can be increased and the fluctuation of the output of the fuel cell 8 can be suppressed.
As described above, in the present embodiment, in the high power / high speed running state, the target of charging is reduced as the fuel remaining amount Qf decreases until the charge start timing is advanced and the fuel remaining amount Qf reaches the target fuel remaining amount Qfb. By reducing the charging rate SOCt, the power generation time can be secured and the output of the fuel cell 8 can be kept constant. Since the efficiency of the fuel cell 8 generally decreases as the output increases, the efficiency of the fuel cell 8 is improved by suppressing the output of the fuel cell 8. Further, since the fluctuation of the output of the fuel cell 8 can be suppressed even with respect to the fluctuation of the vehicle power consumption, the efficiency of the fuel cell 8 can be improved also in this respect.

Thus, for example, in a situation where a high output / high speed driving state continues, such as when driving on a highway, the fuel cell 8 can be efficiently generated and fuel consumption can be suppressed. Therefore, the cruising distance of the vehicle 1 can be increased by increasing the power generation amount that the fuel cell 8 can use with the limited fuel (hydrogen) mounted on the vehicle 1. Further, the life of the fuel cell 8 can be improved by suppressing fluctuations in the output of the fuel cell 8.
When the low output / low speed running state continues, the power generation start is not determined at an early stage, and the power generation starts after the charge rate SOC of the battery 6 reaches the target target charge rate SOCb as in the comparative example. Since the electric motor 3 consumes less power because it is in a low-speed running state, it is not necessary to make the fuel cell 8 have a high output, and therefore a reduction in the efficiency of the fuel cell 8 is suppressed.

  Further, in the present embodiment, the power generation start determination is performed based on the vehicle speed equivalent value calculated by smoothing the vehicle power consumption. When the vehicle speed equivalent value exceeds the threshold value Va for a predetermined time Ta or more, the vehicle 1 outputs high power. It is determined that power generation is started, assuming that the vehicle is running at high speed. Therefore, it is difficult to be affected by uphill and downhill slopes, and the influence of output fluctuation due to acceleration / deceleration is suppressed, and the high output / high speed running state of the vehicle 1 can be determined stably and accurately.

  Further, in this embodiment, the output gain α is set to increase as the target charging rate deviation ΔSOC increases, and in particular, the rate of change of the output gain α increases as the target charging rate deviation ΔSOC increases. Therefore, in the positive region where the target charging rate deviation ΔSOC is close to 0, the output gain α is suppressed to around the predetermined value α1. Thereby, when the charging rate SOC of the battery 6 is slightly lower than the target charging rate SOCt, the output gain α is suppressed and the generated power Pf is suppressed, so that the charging rate SOC is changed to the target charging rate SOCt due to fluctuations in vehicle power consumption. Even if it fluctuates in the vicinity, fluctuations in the generated power Pf can be suppressed. On the other hand, when the target charging rate deviation ΔSOC is increased, that is, when the charging rate SOC of the battery 6 is significantly lower than the target charging rate SOCt, the output gain α is suddenly increased to increase the generated power Pf, and beyond that of the charging rate SOC. The battery 6 can be protected by reliably suppressing the decrease.

As described above, since the rate of change of the power generation output Pf with respect to the target charge rate deviation ΔSOC changes with the target charge rate deviation ΔSOC, it is possible to set a region for suppressing the fluctuation of the power generation output Pf with respect to the change of the target charge rate deviation ΔSOC. it can. Therefore, even if the charging rate SOC fluctuates due to fluctuations in power consumption of the electric motor 3 and the target charging rate deviation ΔSOC fluctuates, fluctuations in the power generation output Pf are suppressed in this region, and the efficiency of the fuel cell 8 is further improved. Can be made.
Further, when the target charging rate deviation ΔSOC is 0 or less, that is, when the charging rate SOC is equal to or higher than the target charging rate SOCt, the output gain α is set to the predetermined value α1, so that the fuel cell 8 can be efficiently used with a small amount of power generation. Generate electricity. Thereby, for example, even if the charging rate SOC changes so as to increase or decrease the target charging rate, the fuel cell 8 continues to generate power without being turned on and off, so that the efficiency and life of the fuel cell 8 can be improved.
This is the end of the description of the embodiment of the invention, but the invention is not limited to this embodiment.

  For example, in this embodiment, a fuel cell is used as a power generation unit, but a unit that combines an engine and a generator may be used instead of the fuel cell. In this case, the vehicle is a hybrid vehicle capable of the series mode, but even in such a vehicle, the generator and the engine are driven and controlled, and the output from the generator is controlled in the same manner as the output control of the fuel cell. By doing so, the engine can be operated efficiently and the cruising distance can be increased.

1 Vehicle 3 Electric Motor 6 Battery 8 Fuel Cell (Power Generation Unit)
20 Fuel level detector (fuel level detector)
21 Battery monitoring unit (charge rate detector)
22 Control unit (power generation control unit)

Claims (5)

A power control device for a vehicle that supplies power from a power generation unit that consumes fuel and generates electricity to an electric motor for driving from a battery,
A fuel remaining amount detecting unit for detecting the remaining amount of fuel in the power generation unit;
A charge rate detector for detecting a current charge rate of the battery;
A power generation control unit for controlling the power generation output of the power generation unit,
The power generation control unit for a vehicle, wherein the power generation control unit calculates the power generation output based on a deviation between a target charging rate calculated based on the fuel remaining amount and the current charging rate. The power generation control unit
When the deviation obtained by subtracting the current charging rate from the target charging rate becomes a positive value, the power generation output is calculated so that the power generation output increases as the deviation increases. The power control apparatus for a vehicle according to claim 1. The power generation control unit
When the deviation obtained by subtracting the current charging rate from the target charging rate becomes a positive value, the power generation output is calculated so that the rate of change of the power generation output increases as the deviation increases. The power control apparatus for a vehicle according to claim 1 or 2. The power generation control unit
4. The power generation output is maintained at a constant value without stopping power generation even when the deviation obtained by subtracting the current charge rate from the target charge rate is 0 or less. 5. The power control apparatus for a vehicle according to the item.   5. The vehicle power control apparatus according to claim 1, wherein the power generation unit is a fuel cell. 6.

Images