JP3966144B2 - Electric vehicle - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an electric vehicle equipped with a DC power supply.
[0002]
[Prior art]
Various electric vehicles that run by driving an electric motor with a DC power source have been proposed. For example, Patent Document 1 discloses a vehicle that travels using a high-voltage power source by coupling two electric motors having different output characteristics to a drive shaft. In recent years, fuel cells that generate electricity by an electrochemical reaction between hydrogen and oxygen have attracted attention as DC power sources.
[0003]
[Patent Document 1]
Japanese Patent Laid-Open No. 11-252993
[Problems to be solved by the invention]
However, in the conventional electric vehicle, there is a problem that when the supply of electric power from the DC power supply is interrupted, the vehicle cannot travel even if the electric motor is normal. An object of the present invention is to solve such a problem and to provide a vehicle that can continue running even if a power supply is disturbed.
[0005]
[Means for solving the problems and their functions and effects]
In order to solve at least a part of the above problems, in the present invention, an electric vehicle includes two power sources that output power to a drive shaft that outputs driving force. The power source has a DC power source and an electric motor driven by the DC power source for each system. By doing so, since a direct-current power supply is prepared for each system, even if an abnormality occurs in one system, it is possible to travel using the other system. Moreover, since the DC power supply and the electric motor are provided for each system, there is an advantage that the above-described redundancy can be secured while avoiding complicated control of each system.
[0006]
In the electric vehicle of the present invention, when a predetermined auxiliary machine driven by a DC power supply is connected for each system, the presence or absence of an abnormality in the DC power supply is detected, and when an abnormality is detected in one of the power supplies The following control may be applied. The motor of one system (hereinafter referred to as “abnormal system”) in which an abnormality exists in the DC power supply is driven by the motor of the other system (hereinafter referred to as “normal system”) in which no abnormality exists, You may make it generate electric power with an electric motor. By so doing, even when an abnormality occurs in the power supply, it is possible to secure power to the auxiliary machine. In order to realize this power generation, the electric motors of each system are preferably provided in a state in which power can be transmitted directly or indirectly to each other.
[0007]
In order to supply power to the abnormal system auxiliary machine, it is possible to adopt a method in which a connection mechanism for electrically connecting the normal system and the abnormal system is disposed between the two systems. Such a connection mechanism can be, for example, a relay device that closes the circuit when an abnormality occurs in one of the power supplies. However, when such a relay device is used, if the current supplied from the DC power supply is very large, there is a possibility of causing an adverse effect such as the occurrence of a spark in the vicinity of the contact at the moment of closing the circuit. On the other hand, the method of causing the abnormal system motor to generate electric power has an advantage that electric power can be supplied to the auxiliary machine without causing such an adverse effect.
[0008]
In the present invention, power generation by an abnormal system motor may be started immediately when an abnormality occurs in the power source. Further, in the case where each system has a power storage device that assists the DC power supply, the power storage device provided in the abnormal system may start when the power storage amount becomes a predetermined value or less. According to the latter mode, the power of the normal system can be effectively used for traveling at least during a period in which the auxiliary power is supplied from the power storage device of the abnormal system.
[0009]
The above-described control is particularly useful when an abnormal system auxiliary machine includes at least one of a steering system, a braking system, and a drive system of an electric vehicle, that is, an auxiliary machine essential for traveling of the electric vehicle. . As a steering system auxiliary machine, a so-called power steering compressor is included. The auxiliary brake system includes so-called brake oil, an air compressor, and a compressor for assisting the amount of brake depression. Examples of the drive system auxiliary equipment include an oil pump for transmission and a cooling pump.
[0010]
In the present invention, the operation of some of the auxiliary machines provided in the abnormal system may be suppressed. A stoppable accessory that is allowed to stop while the electric vehicle is running may be set in advance. Examples of auxiliary equipment that can be stopped include an air conditioning system, an in-vehicle illumination system, and an acoustic system.
[0011]
In the present invention, when the presence or absence of a decrease in the output of the DC power supply is detected, control may be applied in which the output distribution of the required power to be output from the drive shaft is different between the two systems. It is preferable to set the output distribution according to the output decrease so that the output of the system in which the output decrease is detected is lower than the output of the other system. By so doing, it is possible to ensure the required power by compensating the output decrease in one system with the output decrease in the other system. The decrease in output includes not only the case where power supply from the DC power supply becomes impossible, but also the case where a normal output cannot be obtained due to aging or other factors.
[0012]
In the present invention, various power sources such as a primary battery, a secondary battery, and a capacitor can be used as the DC power source, but a fuel cell is preferable from the viewpoint of energy efficiency. When a fuel cell is used, it is necessary to control the supply amount of a fuel gas such as hydrogen and an oxidizing gas such as oxygen in accordance with the required power generation amount. In the present invention, since the fuel cell is provided for each of the two systems, such control is facilitated, and there is an advantage that the operation of the fuel cell can be stabilized.
[0013]
The present invention may be configured as a power output device that outputs power from the drive shaft, or may be configured as a control method for the electric vehicle or the power output device, in addition to the above-described aspect of the electric vehicle.
[0014]
DETAILED DESCRIPTION OF THE INVENTION
The embodiment of the present invention will be described by dividing it into the following items.
A. Device configuration:
B. Operation control:
C. Target value setting:
D. Variation:
[0015]
A. Device configuration:
FIG. 1 is an explanatory diagram showing a schematic configuration of an electric vehicle as an embodiment. This electric vehicle is provided with two independent drive sources for outputting power on the right side and the left side. The left drive source includes a polymer electrolyte fuel cell 22 as a main power source and a battery 21 as an auxiliary power source. The electric power supplied from these power sources is converted into an alternating current by an inverter 24 as a drive circuit and supplied to an alternating current motor 25.
[0016]
The right drive source has the same configuration. As the right drive source, a fuel cell 32, a battery 31, an inverter 34, and an AC motor 35 are provided. In this embodiment, the right drive source and the left drive source have the same output characteristics and capacity. The fuel gas to the fuel cells 22 and 32 is supplied from a common hydrogen tank.
[0017]
The rotating shaft 26 of the motor 25 and the rotating shaft 36 of the motor 35 are connected to gears 42 and 43 in the gear box 40, respectively. The gears 42 and 43 are spur gears that mesh with the drive gear 41. The drive gear 41 is coupled to the drive shaft 12. The power of each motor 25, 35 is output to the drive shaft 12 via each gear of the gear box 40 and is transmitted to each wheel 14 </ b> L, 14 </ b> R via the differential gear 13.
[0018]
In the present embodiment, auxiliary driving circuits 23 and 33 for driving various auxiliary machines upon receiving electric power are connected to each driving source. Auxiliary drive circuits 23 and 33 include a pump for supplying fuel gas and cooling water to the fuel cells 22 and 32, an oil pump for power steering, an outlet for supplying power to electrical equipment of the vehicle, and a compressor for cooling the battery 21. , Air conditioning compressor, air conditioning electric heater, brake air compressor, etc.
[0019]
Among them, although pumps for supplying fuel gas and cooling water to the fuel cells 22 and 32, an oil pump for power steering, and an air compressor for brakes are prepared on both the left and right sides, in order to make the vehicle run stably Is positioned as an indispensable auxiliary machine that is desired to operate both. Air-conditioning compressors and air-conditioning electric heaters are not always essential for vehicle travel, so they are positioned as stoppable accessories that are allowed to automatically stop operation when an abnormality occurs during travel. It has been. The outlet for supplying power to the electrical equipment of the vehicle and the compressor for cooling the battery 21 can be positioned either. However, in this embodiment, in consideration of safety, they are positioned as essential auxiliary machines. These classifications for the auxiliary machines are stored in the control unit 10 in advance.
[0020]
Each part of the vehicle is controlled by the control unit 10. The control unit 10 is configured as a microcomputer having a CPU, a ROM, and a RAM therein, and controls the operation of each part of the vehicle according to a control program prepared in the ROM.
[0021]
In the drawing, various signal lines connected to the control unit 10 in order to realize this control are illustrated by broken lines. The sensor signal input to the control unit 10 includes: accelerator opening sensor 11; vehicle speed sensor 12s; motor rotation speed sensors 25s and 35s; abnormality detection sensors 22s and 32s for fuel cells 22 and 32; The remaining capacity sensors 21s and 31s for detecting the remaining capacity (SOC) are included. The abnormality detection sensors 22 s and 32 s are sensors for detecting various parameters that notify the abnormality of the fuel cells 22 and 23. Such parameters include, for example, the rotational speed of the compressor for supplying the fuel gas and the oxidizing gas to the fuel cells 22 and 32, the temperature of the fuel cells 22 and 32, the supply pressure of the fuel gas and the oxidizing gas, and the fuel cells 22 and 32. The voltage of each cell included in can be used.
[0022]
The output signals from the control unit 10 include output control signals for the fuel cells 22 and 32; control signals for the auxiliary machine drive circuits 23 and 33; control signals for the inverters 24 and 34, and the like.
[0023]
B. Operation control:
FIG. 2 is a flowchart of the operation control process. This is a process executed repeatedly by the control unit 10 while the electric vehicle is traveling. When this process is started, the control unit 10 first inputs an accelerator opening, a vehicle speed, and the like as parameters used for control (step S10). In various variables used in this control process, R means a value for the right side system, and L means a value for the left side system.
[0024]
Next, based on these parameters, various required powers shown below are set (step S12). The total required power Ptr is a required power for driving the vehicle, and is set by referring to a map that gives the total required power Ptr in advance in relation to the accelerator opening and the vehicle speed. The auxiliary machine powers PRa and PLa are required powers for driving the auxiliary machines, and vary depending on the operating state of each auxiliary machine. The charging powers PRb and PLb are powers for charging the batteries 21 and 31. In the present embodiment, when the remaining capacity of the batteries 21 and 31 falls below a preset lower limit value, charging is started. Therefore, the charging powers PRb and PLb are determined according to the remaining capacity at that time. When the remaining capacity of the battery 31 is equal to or greater than the lower limit value, charging is not required, and thus the charging powers PRb and PLb are zero.
[0025]
When the various powers are set in this way, the control unit 10 detects whether or not the operating state of the fuel cells 22 and 32 is normal (step S14). In this embodiment, the operation state of each of the fuel cells 22 and 32 is specified in three categories: normal, output reduction, and abnormality. The normal state is a state where the fuel cells 22 and 32 can output 90% or more of the power that can be originally output. The output reduction is a state in which the output of the fuel cells 22 and 32 is 80% or more and less than 90% due to aging and other causes, although there is no trouble in operation. The abnormality is a state where the operation of the fuel cells 22 and 32 cannot be continued, or a state where the output is below 80%. The classification of the operation state can be arbitrarily set, and it may be normal / abnormal only without providing the “output reduction” state. Moreover, the output range which prescribes | regulates each division can also be set arbitrarily.
[0026]
If it is determined that both of the fuel cells 22 and 32 are abnormal (step S16), the control unit 10 determines that the vehicle cannot continue traveling and stops the system (step S18). At the same time, the driver may be notified that the fuel cells 22 and 23 are abnormal. In the present embodiment, even when it is determined that both the fuel cells 22 and 32 are in output reduction, they are treated as being equivalent to the abnormality.
[0027]
In other cases, the control unit 10 sets a target value in accordance with the operating state of the fuel cells 22 and 32 (step S20). The power target values ER and EL are target values of power to be output from the fuel cells 22 and 32. The motor target powers MR and ML are target powers to be output from the motors 25 and 35. When the target power is positive, it means power running of the motors 25 and 35, and when it is negative, it means regeneration. A method for setting these target values will be described later.
[0028]
When each target value is set in this way, the control unit 10 uses the upper limit values ERmax and ELmax of the outputtable power and the rotational speed NR of the motor as parameters for controlling the operations of the fuel cells 22 and 32 and the motors 25 and 35. , NL are detected (step S22). Further, the upper limit guard of the motor target power MR, ML is applied by the calculation of the following equation (step S24).
MR = MIN (MR, ERmax);
ML = MIN (ML, ELmax);
Here, MIN is an operator that means to select the minimum value of two values.
[0029]
Due to the upper limit guard, the motors 25 and 35 are driven in a range of electric power that can be supplied from the fuel cells 22 and 32. The control unit 10 sets the target torques TR and TL of the motor by dividing the target powers MR and ML set in this way by the motor rotational speeds NR and NL (step S26). The torque and power target values ER and EL are used as command values to control the power source and the motor (step S28).
[0030]
C. Target value setting:
FIG. 3 is an explanatory diagram showing a target value setting method. In this embodiment, the operation states of the fuel cells 22 and 23 are classified into five combinations. The control unit 10 sets a target value using the following formula according to each classification.
[0031]
Case A: When both fuel cells are normal In this case, the total required power Ptr is output equally from each system. Auxiliary machine powers PRa and PLa and charging powers PRb and PLb are powers specific to each system, and are therefore output in each system. Accordingly, each target value is set as follows.
Electric power target value;
ER = Ptr / 2 + PRa + PRb;
EL = Ptr / 2 + PLa + PLb;
Motor target power;
MR = Ptr / 2;
ML = Ptr / 2;
[0032]
Case B: When the output of the right (R) fuel cell is reduced In this case, the total required power Ptr is output from each system in a different distribution. Since the output of the right system is decreasing, the distribution ratio on the right side is made lower than that on the left side. Auxiliary machine powers PRa and PLa and charging powers PRb and PLb are powers specific to each system, and are therefore output in each system. Accordingly, each target value is set as follows.
Electric power target value;
ER = Ptr / 2 × k + PRa + PRb;
EL = Ptr / 2 × (2-k) + PLa + PLb;
Motor target power;
MR = Ptr / 2 × k;
ML = Ptr / 2 × (2-k);
[0033]
k is a distribution ratio, and the set value in this embodiment is shown on the lower side of FIG. The output power range between p1 and p2 is a range in which the output is judged to be reduced. In this embodiment, “p1 = 80%, p2 = 90%” is set. The distribution rate k can be arbitrarily set, but in this embodiment, as shown in the figure, the distribution rate k is set to change linearly in the range of 0.8 to 1.0 in the above range. According to this setting, when the output of the right fuel cell is reduced to 80%, the power to be output from the right system is reduced to 0.8 times that in the normal state. On the other hand, the power to be output from the left system is increased to 1.2 times the normal value. By so doing, the output decrease of the right system can be compensated for by the left system, and the output of the total required power PTr can be ensured.
[0034]
Case C: When the output of the left (L) fuel cell is lowered In this case, the target values can be set as follows based on the same concept as in Case B.
Electric power target value;
ER = Ptr / 2 × (2-k) + PRa + PRb;
EL = Ptr / 2 × k + PLa + PLb;
Motor target power;
MR = Ptr / 2 × (2-k);
ML = Ptr / 2 × k;
The distribution rate k uses the same setting as in Case B.
[0035]
Case D: When the right (R) fuel cell is abnormal In this case, since the output from the right fuel cell cannot be obtained, the total required power is all output from the left system. In order for the vehicle to travel stably, it is necessary to supply power to the essential accessories connected to the right side system. In case D, this accessory power PRa is secured in two ways. . One is power from the right-side battery 31. The other is electric power obtained by regenerating a part of the power output from the left-side motor 25 operating normally by the right-side motor 35.
[0036]
In the present embodiment, the battery 31 is positioned as an auxiliary power source for the fuel cell 32 that outputs a shortage when the fuel cell 32 cannot output the requested power. In Case D, since the fuel cell 32 cannot output power, the power target value ER for the right system can be regarded as an output target to the battery 31 as it is.
[0037]
Based on the above concept, in case D, each target value is set as follows.
Electric power target value;
ER = PRa × FS;
EL = Ptr + PLa + PLb + PRa (1-FS);
Motor target power;
MR = −PRa × (1−FS);
ML = Ptr + PRa × (1−FS);
Since the target power MR of the right motor 35 is set to a negative value, the motor 35 regenerates electric power.
[0038]
FS is a distribution ratio of the power to be supplied from the battery 31, and the set value in the present embodiment is shown on the lower side of FIG. The distribution rate FS is set according to the remaining capacity SOC of the battery 31. The range in which the SOC is equal to or greater than s2 is a range in which the battery 31 can be regarded as being fully charged. In this state, all the auxiliary machine power PRa is supplied from the battery 31. The range in which the SOC is equal to or less than s1 is a range in which the battery 31 can be regarded as having insufficient remaining capacity. In this state, the battery 31 does not supply the auxiliary power PRa in order to avoid power consumption. In the range of s1 to s2, the battery 31 outputs a part of the auxiliary machine power PRa at a distribution rate according to the SOC value. Of the auxiliary machine power PRa, the shortage of the output from the battery 31 is compensated by regeneration. The setting of the allocation rate FS is not limited to this, and may be a discontinuous setting that takes either 0 or 1 with a predetermined SOC as a boundary. In case D, the distribution rate FS may be set to 0 constantly.
[0039]
The auxiliary machine power PRa may be a value equivalent to that at the normal time, or may be a value in a state in which the stopable auxiliary machine is stopped. In this embodiment, in order to suppress power consumption in the right side system, in case D, the stoppable auxiliary machine is stopped. Initially, all auxiliary machines may be operated, and the stopable auxiliary machine may be stopped when the remaining capacity of the battery 31 falls below a predetermined value.
[0040]
When the above-mentioned target power ER cannot be output by the left fuel cell 32, the upper limit guard is applied to the range in which the target power ER can be output, and the charging power PLb and the left motor target power ML are reduced. The motor target power MR on the right side holds the set value because power regeneration is essential for driving the auxiliary machine. By doing so, the power output from the drive shaft 12 is lower than the power requested by the driver, but the vehicle can continue to travel.
[0041]
Case E: When the left (L) fuel cell is abnormal In this case, each target value can be set as follows based on the same concept as in Case D.
Electric power target value;
ER = Ptr + PRa + PRb + PLa × (1−FS);
EL = PLa × FS;
Motor target power;
MR = Ptr + PLa × (1−FS);
ML = −PLa × (1−FS);
Since the target power ML of the left motor 25 is set to a negative value, the motor 25 regenerates electric power.
[0042]
FIG. 4 is an explanatory diagram showing a power transmission state in case E. This shows a state where there is an abnormality in the left fuel cell 22 and the remaining capacity of the battery 21 is s1 or less, that is, the distribution rate FS is zero.
[0043]
According to the target value setting in case E described above, a part of the power output from the right fuel cell 32 is supplied to the battery 31 as the charging power PRb (arrow A in the figure). A part is supplied to the left side auxiliary drive circuit 33 as the auxiliary power PLa (arrow B). The remainder is temporarily output as power of the motor 35 via the inverter 34 (arrow C). This power is distributed by the gear box 40, and an amount corresponding to the total required power Ptr is supplied to the drive shaft 12 (arrow D). The rest is regenerated by the motor 25 as auxiliary machine power PRa and supplied to the right side auxiliary machine drive circuit 23 (arrow F).
[0044]
According to the electric vehicle of the embodiment described above, even if the output is reduced or abnormal in one of the fuel cells 22, 32, the shortage is compensated with the electric power from the other system and the vehicle travels. be able to. In addition, the power supply system is provided independently on the left and right, but by regenerating power with the motor of the system in which an abnormality has occurred, it is possible to ensure the power supply to the auxiliary equipment even in the event of an abnormality. Can continue.
[0045]
D. Variation:
FIG. 5 is an explanatory diagram showing a schematic configuration of an electric vehicle as a modification. The difference from the embodiment is that a connector 15 for connecting the right and left systems is provided. The connector 15 is connected under the control of the control unit 10A when an abnormality occurs in one of the power supplies. The connector 15 may be a normal relay or a circuit that controls energization by a switching element.
[0046]
According to the modification, in addition to the control in the embodiment, it is possible to cope with a failure of the inverters 24 and 34 or the motors 25 and 35. When the control unit 10 </ b> A detects an abnormality in these systems, the control unit 10 </ b> A stops the inverter and motor of the abnormal system and connects the connector 15. By doing so, both the left and right power supplies are connected in parallel to the normal system inverter and motor. Therefore, traveling can be continued while avoiding an excessive load applied only to the normal fuel cell.
[0047]
As mentioned above, although the various Example of this invention was described, it cannot be overemphasized that this invention is not limited to these Examples, and can take a various structure in the range which does not deviate from the meaning. For example, the above control processing may be realized by hardware in addition to software.
[Brief description of the drawings]
FIG. 1 is an explanatory diagram showing a schematic configuration of an electric vehicle as an embodiment.
FIG. 2 is a flowchart of an operation control process.
FIG. 3 is an explanatory diagram showing a method for setting a target value.
4 is an explanatory diagram showing a power transmission state in case E. FIG.
FIG. 5 is an explanatory diagram showing a schematic configuration of an electric vehicle as a modified example.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 10, 10A ... Control unit 12 ... Drive shaft 13 ... Differential gear 14R, 14L ... Wheel 15 ... Connector 21, 31 ... Battery 21s, 31s ... Remaining capacity sensor 22, 32 ... Fuel cell 22s, 32s ... Sensor 23 for abnormality detection 33 ... Auxiliary machine drive circuits 24, 34 ... Inverters 25, 35 ... AC motors 25s, 35s ... Rotational speed sensors 26, 36 ... Rotating shaft 40 ... Gear box 41 ... Drive gear 42 ... Gear

Claims (7)

An electric vehicle,
A drive shaft that outputs drive force;
Two power sources for outputting power to the drive shaft,
The power source has a DC power source for each of the systems, and an electric motor driven by the DC power source ,
The electric vehicle further includes:
A predetermined auxiliary machine driven by the DC power supply for each of the systems;
A detection unit for detecting presence or absence of abnormality of the DC power supply;
When one of the systems is an abnormal system in which an abnormality exists in the DC power supply and the other system is detected as a normal system in which the abnormality does not exist, the motor of the abnormal system is driven by the motor of the normal system A power generation control unit that supplies power to the abnormal system auxiliary machine by generating power with the abnormal system motor;
An electric vehicle comprising: The electric vehicle according to claim 1 ,
Each system has a power storage device that assists the DC power supply,
The power generation control unit is an electric vehicle that operates when a storage amount of a power storage device provided in the abnormal system becomes a predetermined value or less. The electric vehicle according to claim 1 or 2 ,
The abnormal system auxiliary machine is an electric vehicle including at least one of a steering system, a braking system, and a drive system of the electric vehicle. An electric vehicle according to any one of claims 1 to 3 ,
A setting storage unit for preliminarily storing a setting content that sets a part of the auxiliary machine of the abnormal system as a stoppable auxiliary machine that is allowed to stop while the electric vehicle is running;
An electric vehicle comprising: an auxiliary machine control unit that suppresses operation of the stopable auxiliary machine for the abnormal system when the abnormality is detected. The electric vehicle according to any one of claims 1 to 4 ,
An input unit for inputting required power to be output from the drive shaft;
A detection unit for detecting the presence or absence of an output drop of the DC power supply;
Controls the operation of each motor so that when the output drop is detected in the DC power supply of one system, the output of the motor of this system becomes lower than the output of the motor of the other system according to the output drop An electric vehicle including an electric motor control unit. The DC power source, an electric vehicle according to any one of claims 1 to 5 is a fuel cell. An electric vehicle control method comprising:
The electric vehicle
A drive shaft that outputs drive force;
Two power sources for outputting power to the drive shaft,
The power source has a DC power source for each system, an electric motor driven by the DC power source, and a predetermined auxiliary machine driven by the DC power source,
Detecting the presence or absence of abnormality of the DC power supply;
When one of the systems is an abnormal system in which an abnormality exists in the DC power supply and the other system is detected as a normal system in which the abnormality does not exist, the motor of the abnormal system is driven by the motor of the normal system And a step of supplying electric power to the abnormal system auxiliary machine by generating power with the abnormal system motor.

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