JP2007186038A - Controller of motor drive vehicle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve the fuel consumption while ensuring the power performance of a vehicle in a motor drive vehicle. <P>SOLUTION: A controller of a motor drive vehicle computes a first energy storage state and a second energy storage state smaller than the first storage state as values so as to discharge the power necessary for an acceleration request, respectively (S5, S6), when the acceleration request is not made and a power generation device is in operation, starts charging to an energy storage device if the energy storage state of an energy storage device is lower than the first storage state (S5, S7, S8), and when the acceleration request is not made and the generation device is stopped, starts the charging to the energy storage device if the energy storage state of the energy storage device is lower than the second storage state (S6, S7, S8). <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a control device for a motor-driven vehicle.

  In a hybrid vehicle including an air conditioner unit that air-conditions a passenger compartment, when the SOC of the battery becomes equal to or lower than the charge start SOC for determining the start of charging the battery, the generator is driven by the traveling engine to charge the battery. However, if the traveling engine is frequently operated only for charging, it is not possible to sufficiently achieve an object such as an improvement in fuel consumption.

Therefore, by setting the charging start SOC so that the driving engine is higher than when the driving engine is stopped, the driving engine is frequently operated only for charging regardless of whether the vehicle is stopped or traveling. Japanese Patent Application Laid-Open No. H10-228867 describes a technique for avoiding the occurrence of the problem as much as possible and further improving the fuel consumption.
JP 2002-262401 A

  However, with the above technology, there is a possibility that sufficient power performance of the vehicle cannot be ensured even if electric power necessary for the operation of the air conditioner unit can be ensured.

  SUMMARY OF THE INVENTION An object of the present invention is to improve fuel efficiency in a motor-driven vehicle such as a hybrid vehicle while ensuring the power performance of the vehicle.

  The motor-driven vehicle of the present invention includes power consumption calculation means for calculating the power consumption of the motor necessary to satisfy the driver's acceleration request, and when the acceleration request is generated, the generated power of the power generator is equal to the power consumption of the motor. A first power generation device control means for increasing at substantially the same increase rate as the increase rate; and a first power generation device that increases the generated power of the power generation device to the maximum generated power of the power generation device regardless of the power consumption of the motor when an acceleration request is generated. A first power storage state that is a power storage state of the power storage device necessary for discharging the amount of power predicted to be insufficient when performing control by the second power generation device control means, the first power generation device control means, Calculating a second power storage state smaller than the first power storage state, which is a power storage state of the power storage device necessary for discharging the amount of power predicted to be insufficient when performing control by the power generation device control means of Required storage state When the calculation unit and the acceleration request are not generated and the power generation device is in operation, when the power storage state of the power storage device falls below the first power storage state, charging of the power storage device is started and an acceleration request is generated. When the power generation device is not in operation and the power generation device is stopped, charge control means is provided to start charging the power storage device when the power storage state of the power storage device falls below the second power storage state. When the power storage state of the power storage device is greater than the first power storage state, control by the first power generation device control means is performed, and if the power storage state of the power storage device is smaller than the first power storage state and greater than the second power storage state, the first Control by the power generator control means 2 is performed.

  According to the present invention, when no acceleration request is generated and the power generation device is in operation, charging of the power storage device is started when the power storage state of the power storage device falls below the first power storage state, and the acceleration request When the power generation device is not operating and the power generation device is stopped, charging of the power storage device is started when the power storage state of the power storage device falls below the second power storage state. In comparison, the threshold value for determining the start of charging is increased, and the frequency of charging the power storage device is increased by the amount corresponding to the threshold value. As a result, the frequency of charging with high efficiency increases and the frequency of charging with low efficiency decreases, so that the fuel consumption can be reduced.

  Further, when an acceleration request is made, if the power storage state of the power storage device is larger than the first power storage state, the generated power of the power generation device is increased at a rate substantially the same as the motor power consumption increase rate. The acceleration request can be realized while the operation sound generated from the power generation apparatus is commensurate with the traveling load.

  Furthermore, when an acceleration request is generated, if the power storage state of the power storage device is smaller than the first power storage state and larger than the second power storage state, the power generation power of the power generation device is increased to the maximum power generation power of the power generation device regardless of the power consumption of the motor. Since the power is increased, the amount of power that is reserved in the power storage device in advance for the acceleration request, that is, the stored state can be suppressed as low as possible.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

(First embodiment)
FIG. 1 shows a configuration diagram of a series hybrid vehicle in the present embodiment. The power train is an engine 1, a generator 2 that is directly connected to the engine 1 and generates power by the output of the engine 1, cranking at start-up, power generated by the generator 2, and power stored in the power storage device 3 The motor 4 is driven by at least one electric power, and the torque of the motor 4 is transmitted to the drive wheels 6 via the final gear 5. Further, the electric power of the power storage device 3 is consumed by the auxiliary machinery 14 mounted on the vehicle.

  The engine controller 7 controls the throttle opening so as to realize the engine torque command value output from the integrated controller 11.

  The generator controller 8 performs vector control on the generator 2 so that the rotation speeds of the engine 1 and the generator 2 are equal to the rotation speed command value output from the integrated controller 11.

  The power storage device controller 9 detects the voltage and current of the power storage device 3, calculates the power that can be input to and output from the power storage device 3, and transmits it to the integrated controller 11. Here, a battery such as nickel metal hydride or lithium ion may be used for the power storage device 3, or a capacitor may be used.

  The motor controller 10 vector-controls the torque of the motor 4 based on the motor torque command value output from the integrated controller 11.

  The integrated controller 11 receives the vehicle speed detected by the vehicle speed sensor 12 and the accelerator opening calculated based on the output of the accelerator position sensor 13.

  Next, control performed by the integrated controller 11 will be described with reference to FIG. FIG. 2 is a flowchart showing the control of the control device for the motor-driven vehicle in the present invention. This control assumes the driver's acceleration request, and performs charge control so as to secure in advance the SOC of the power storage device necessary to realize the acceleration request. This control is repeatedly performed every minute time (for example, 10 ms).

  In step S1, the state of charge of power storage device 3 (hereinafter referred to as “SOC”) is calculated. The SOC detects a current flowing through the power storage device 3 using a current sensor, and calculates using the following equation (1).

  Here, I indicates a current flowing through the power storage device 3, and CAP indicates a capacity of the power storage device 3.

  Moreover, since an error occurs in the current value detected by the sensor, the accuracy of the calculated SOC is improved by appropriately correcting the SOC calculated by the equation (1) using the SOC calculated by a method other than the above. be able to.

  In step S2 (power consumption calculation means), the driver's acceleration request is assumed, and the power consumption of the motor 4 required to realize this acceleration request is calculated. The power consumption of the motor 4 is calculated according to the flowchart of FIG. In the following, the case where the vehicle is accelerated with the accelerator opening fully opened and reaches the predetermined vehicle speed within a desired time will be described. However, the present invention is not limited to this. It can be performed.

  In step S21, the current required driving force is calculated. The required driving force is calculated based on the vehicle speed and the accelerator opening with reference to the map of FIG. 4 showing the relationship between the vehicle speed, the accelerator opening, and the required driving force.

  In step S22, the acceleration α of the vehicle is calculated. The acceleration α is calculated based on the following equation (2).

Here, g is the gravitational acceleration, F is the required driving force, μ _r is the rolling resistance coefficient, W is the vehicle weight, μ _l is the air resistance coefficient, A is the front projected area, and V is the vehicle speed used in the previous calculation. , Φ is an apparent weight increase considering the rotating part. μ _r , W, μ _l , A, and φ are obtained in advance by experiments.

  In step S23, changes in vehicle speed and required driving force after execution of this step are estimated. The change in the vehicle speed and the required driving force is calculated by integrating the acceleration α calculated by the above equation (2) to calculate the vehicle speed after a minute time from the present, and based on this vehicle speed, the same processing as the above-described steps S21 and S22 To calculate the required driving force and acceleration after a short time. By repeating this process, as shown in FIG. 5, changes in the vehicle speed and the required driving force after the execution of this step are estimated.

  In step S24, a road surface transmittable torque upper limit value is calculated. The road surface transmittable torque upper limit value is calculated as follows.

  First, the road surface friction coefficient μ is estimated based on the wheel speed of each wheel. As an estimation method, for example, as described in Japanese Patent Application Laid-Open No. 11-78843, a technique for estimating a road surface friction coefficient gradient, which is a gradient of a friction coefficient between a tire and a road surface, or Japanese Patent Application Laid-Open No. 10-114263. As described above, as a physical quantity that can be handled equivalently to a road surface friction coefficient gradient, a technique that estimates based on a braking torque gradient or a driving torque gradient with respect to a slip speed is known.

  Next, by multiplying the load applied to the drive wheels 6 by the road surface friction coefficient μ, a road surface transmittable torque upper limit value that is the maximum value of the driving force that can be generated in each wheel without causing over-rotation slip is obtained. be able to.

  In step S25, the power consumption of the motor 4 is calculated. The power consumption of the motor 4 is calculated by dividing the output of the motor 4 calculated as the product of the rotation speed and the torque by the efficiency at the operating point.

  Here, the relationship between the rotational speed, torque and efficiency of the motor 4 is shown in the map of FIG. The thin solid line is the maximum torque line, the broken line is the iso-output line, the one-dot chain line is the iso-efficiency line, the two-dot chain line is the road surface transmittable torque upper limit value, and the point a indicates the point where the efficiency of the motor 4 is maximum. Further, based on the change in the required driving force estimated in step S23 and the road surface transmittable torque upper limit value calculated in step S24, the motor torque during acceleration has the road surface transmittable torque upper limit value set to the maximum value as shown in FIG. Follow the maximum torque line.

  Therefore, the power consumption of the motor 4 is calculated by referring to this map. The power consumption can also be obtained from measured data by simulating the driving situation assumed in the experiment using an actual vehicle.

  Returning to FIG. 2, in S3, it is determined whether the acceleration request assumed in step S2 is detected. If it is determined that an acceleration request is detected, the process proceeds to step S10. If it is determined that no acceleration request is detected, the process proceeds to step S4. In this embodiment, it is assumed that the acceleration request is made when the accelerator opening is fully opened from the vehicle stop state and reaches the predetermined vehicle speed within a desired time, so that the accelerator opening is 100% and the change rate of the opening. Is 0 to 100% within the calculation cycle, it is determined that the assumed acceleration request has been detected.

  In step S4, it is determined whether or not the power generator is operating. If it is determined that it is operating, the process proceeds to step S5, and if it is determined that it is not operating, the process proceeds to step S6. The power generation device is constituted by the engine 1 and the generator 2.

  In step S5 (necessary storage state calculating means), a first charge start SOC is set. Here, the first charging start SOC and the SOC for determining the start of charging while the power generator is in operation, the driver's request is given while emphasizing the feeling of acceleration felt by the driver when the acceleration request is actually generated. It is set as follows so that acceleration performance can be realized.

  Here, the driver feels acceleration by the loudness of the operating noise of the power generation device. In the series type hybrid vehicle, the output shaft of the power generation device and the drive shaft of the vehicle are not mechanically connected, so the output of the power generation device can be freely changed regardless of the output from the drive shaft. Therefore, when the acceleration feeling that the driver feels from elements such as vision does not match the acceleration feeling that the driver feels from the operating sound of the power generation device, the driver may feel uncomfortable.

  Therefore, as shown in FIG. 7, the power generated by the power generator when the driver requests acceleration is set so as to have a monotonically increasing relationship with the power consumption of the motor 4. At this time, as indicated by the hatched portion in FIG. 7, the shortage of the generated power relative to the power consumed by the motor 4 is the necessary power when the driver requests acceleration, and the first charge start SOC discharges this shortage. It is set to the SOC required to do.

  In addition, when the power generator is stopped later, the secured SOC may be lower than the first charging start SOC due to the power consumption of the auxiliary machinery 14, so the power consumed by the auxiliary machinery 14 is taken into consideration. The first charging start SOC may be set to a value larger by a predetermined value. Here, this predetermined value is set to a larger value as the auxiliary machine power consumption during traveling is larger.

  Furthermore, since the charge / discharge power characteristics of power storage device 3 vary depending on the temperature of power storage device 3 as shown in FIG. 8, the first charge start SOC may be set in consideration of this charge / discharge power characteristics. That is, as the temperature is lower, the charge / discharge power characteristics are lowered. Accordingly, the first charge start SOC is set higher as the temperature is lower.

  In addition, when there are a plurality of traveling situations in which an acceleration request is to be realized, the largest value among the first charging start SOCs set in the same manner may be set.

  On the other hand, when it is determined in step S4 that the power generator is not in operation, the process proceeds to step S6 (necessary storage state calculation means) to set the second charge start SOC. Here, the second charging start SOC is an SOC for determining the start of charging while the power generator is stopped, and is set as follows so as to realize the driver's acceleration request while avoiding charging as much as possible. .

  Here, the power generation efficiency when the engine is stopped and during operation will be described with reference to FIG. FIG. 9 shows the fuel consumption characteristics of the engine 1. The solid line is the equal fuel consumption rate line, the broken line is the equal output line, and the one-point difference line is the best fuel consumption line that minimizes the fuel consumption in realizing each output. .

  When power generation and charging are started while the engine is stopped, the operating point of the engine 1 shifts from point A to point A '. When charging is started during engine operation, the operating point of the engine 1 shifts from point B to point B ', for example. Therefore, the power generation efficiency is lower when the engine is stopped than during operation, and it is effective to avoid power generation while the engine is stopped as much as possible in order to improve fuel efficiency.

  Therefore, the second charging start SOC is set to the lowest value among the SOCs necessary for discharging the electric power necessary to realize the driver's acceleration request in order to avoid power generation and charging while the engine is stopped. . That is, as shown in FIG. 10, when an acceleration request is generated, the generated power of the power generator is increased to the maximum value, and charging is performed a little while the power consumption of the motor 4 exceeds the maximum generated power. The required power can be minimized, that is, the SOC secured in advance can be minimized.

  Further, similarly to the setting of the first SOC, the second charging start SOC may be set to a value larger by a predetermined value in consideration of the power consumed by the auxiliary machinery 14, and the temperature of the power storage device 3 may be set. The second charge start SOC may be set in consideration of the change in the charge / discharge power characteristics due to.

  In addition, when there are a plurality of travel situations in which an acceleration request is to be realized, the largest value among the second charge start SOCs set in the same manner may be set.

  Returning to FIG. 2, in step S7, it is determined whether or not the current SOC is smaller than the charge start SOC set in step S5 or S6. If the current SOC is smaller than the charging start SOC, the process proceeds to step S8 (charging control means) to start or continue charging. If the current SOC is equal to or higher than the charge start SOC, the process proceeds to step S9 (charge control means) to stop the charge.

  If the charging start SOC is set to the second SOC in step S8, charging of power storage device 3 is continued until the SOC exceeds the first SOC.

  On the other hand, if it is determined in step S3 that there is an acceleration request, the process proceeds to step S10 to determine whether or not the current SOC is greater than the first charge start SOC. If it is larger than the first charge start SOC, the process proceeds to step S11. If it is determined that it is equal to or less than the first charge start SOC, the process proceeds to step S12.

  In step S11 (first power generation device control means), the power generation device is controlled. In this step, since it is determined that the SOC is larger than the first charge start SOC, the target of the power generator is set so that the generated power monotonously increases with the power consumption of the motor 4 as shown in FIG. 7 described in step S5. Set the generated power.

  On the other hand, if it is determined in step S10 that the current SOC is equal to or lower than the first charge start SOC, the process proceeds to step S12, and it is determined whether or not the current SOC is greater than the second charge start SOC. If it is larger than the second charge start SOC, the process proceeds to step S13, and if it is equal to or less than the second charge start SOC, the process ends.

  In step S13 (second power generation device control means), the power generation device is controlled. In this step, since it is determined that the SOC is equal to or lower than the first charge start SOC and greater than the second charge start SOC, an acceleration request is generated as shown in FIG. The target generated power of the power generator is set so that the generated power increases to the maximum value.

  At this time, the target generated power may be set according to the magnitude of the SOC, that is, the increase rate of the target generated power may be reduced to the extent that the required power at the time of the acceleration request is not insufficient as the secured SOC is larger. As a result, the operating sound of the power generating device during acceleration can be brought close to that corresponding to the traveling load.

  As described above, in the present embodiment, when the acceleration request is not generated and the power generation device is operating, when the SOC falls below the first SOC, charging of the power storage device 3 is started, and the acceleration request is made. When it does not occur and the power generation device is stopped, charging of the power storage device 3 is started when the SOC falls below the second SOC. Therefore, charging is started when the power generation device is operating compared to when it is stopped. And the frequency of charging the power storage device 3 is higher than that at the time of stoppage. As a result, the frequency of charging with high efficiency increases and the frequency of charging with low efficiency decreases, so that the fuel consumption can be reduced.

  Further, when the acceleration request is made, if the SOC is larger than the first SOC, the generated power of the power generator is increased at substantially the same increase rate in synchronism with the increase rate of the power consumption of the motor 4, so that power generation during acceleration is performed. The driver's acceleration request can be realized while reducing a sense of incongruity given to the driver that the operation sound generated from the device is commensurate with the traveling load.

  Further, when the acceleration request is generated, if the SOC is smaller than the first SOC and larger than the second SOC, the generated power of the power generator is increased up to the maximum generated power of the power generator regardless of the power consumption of the motor 4. The amount of power that is reserved in advance in power storage device 3 in preparation for the acceleration request, that is, the second SOC can be suppressed as low as possible.

  Further, since the first charge start SOC is set to a value that is larger by a predetermined value, even if the SOC reserved for the acceleration request is reduced due to the power consumption by some load during the stoppage of the power generation device, The acceleration request can be realized while the operation sound generated by the operation of the power generation apparatus is commensurate with the traveling load.

  Further, the first charging start SOC is set to a value that is larger by the amount of power consumed by the auxiliary machinery 14, and is set to a larger value as the power consumption of the auxiliary machinery 14 is larger. Even if the SOC secured in preparation for the acceleration request decreases due to the power consumption due to the power consumption, the acceleration request can be realized while the operation sound generated by the operation of the power generation device at the time of the acceleration request is commensurate with the traveling load.

  Further, a road surface transmittable torque upper limit value is calculated based on the road surface μ between the tire and the road surface, and the maximum motor torque value during acceleration is used as the road surface transmittable torque upper limit value. It is possible to avoid a decrease in fuel efficiency improvement effect due to securing an extra electric power necessary for outputting torque exceeding the upper limit value.

  Further, when the charging start SOC is set to the second SOC and when the SOC falls below the second SOC and charging of the power storage device 3 is started, charging is performed until the SOC exceeds the first SOC. Therefore, it is possible to prevent the driver from feeling uncomfortable by repeating the operation and stop of the power generation device.

  Furthermore, since the first SOC and the second SOC are set in consideration of the change in the charge / discharge power characteristics based on the temperature change of the power storage device 3, it is possible to ensure the necessary SOC regardless of the temperature environment change. The driver's acceleration request can be realized.

(Second Embodiment)
In this embodiment, the control is the same as in the first embodiment, and the configuration of the vehicle is partially different. FIG. 11 is a block diagram of a series hybrid vehicle in the present embodiment.

  In the present embodiment, the power generator is a fuel cell 20 instead of the engine 1 and the generator 2 in the first embodiment. Various types of fuel cells 20 such as a solid polymer type, a phosphoric acid type, and a molten carbonate type can be applied to the fuel cell 20. The hydrogen gas as the fuel gas may be stored in a hydrogen cylinder, or may be generated by reforming a raw material such as alcohol using a reformer.

  The fuel cell controller 21 controls the generated power of the fuel cell 20 based on the target generated power command value output from the integrated controller 11.

  As described above, in the present embodiment, the power generation device is configured by the fuel cell 20 instead of the engine 1 and the generator 2, and the driver's acceleration request is reduced while reducing the uncomfortable feeling given to the driver as in the first embodiment. The fuel consumption can be further reduced.

  The present invention is not limited to the embodiment described above, and various modifications and changes can be made within the scope of the technical idea.

It is a whole block diagram which shows the control apparatus of the motor drive vehicle in 1st Embodiment. It is a flowchart which shows control of the control apparatus of the motor drive vehicle in 1st Embodiment. It is a flowchart which shows motor power consumption calculation control. It is a map which shows the relationship between a vehicle speed, an accelerator opening degree, and a request | requirement driving force. It is a time chart which shows the relationship between the required driving force at the time of acceleration, and a vehicle speed. It is a map which shows the relationship between the rotational speed of a motor, torque, an output, and the efficiency of an electric power generating apparatus. It is a time chart which shows the relationship between the power consumption of a motor, and generated electric power. It is a characteristic view which shows the charging / discharging electric power characteristic of a motor. It is a characteristic view which shows the fuel consumption characteristic of an engine. It is a time chart which shows the relationship between the power consumption of a motor, and generated electric power. It is a whole block diagram which shows the control apparatus of the motor drive vehicle in 2nd Embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Engine 2 Generator 3 Power storage device 4 Motor 5 Final gear 6 Drive wheel 7 Engine controller 8 Generator controller 9 Power storage device controller 10 Motor controller 11 Integrated controller 12 Vehicle speed sensor 13 Acceleration position sensor 14 Auxiliary machinery 20 Fuel cell 21 Fuel cell controller

Claims (8)

A power generator,
A power storage device that stores power generated by the power generation device; and
A motor driven by electric power supplied from at least one of the power generation device and the power storage device;
In a control device for a motor-driven vehicle comprising:
Power consumption calculating means for calculating the power consumption of the motor necessary to satisfy the driver's acceleration request;
First power generation device control means for increasing the generated power of the power generation device at an increase rate substantially the same as the increase rate of power consumption of the motor when the acceleration request occurs;
Second power generator control means for increasing the generated power of the power generator to the maximum generated power of the power generator regardless of the power consumption of the motor when the acceleration request occurs;
A first power storage state that is a power storage state of the power storage device required to discharge an amount of power that is predicted to be insufficient when performing control by the first power generation device control means; and the second power generation device control Necessary power storage for calculating a second power storage state smaller than the first power storage state, which is a power storage state of the power storage device necessary for discharging the amount of power predicted to be insufficient when performing control by means State calculating means;
When the acceleration request is not generated and the power generation device is in operation, when the power storage state of the power storage device falls below the first power storage state, charging of the power storage device is started, and the acceleration request Charging control means for starting charging the power storage device when the power storage state of the power storage device falls below the second power storage state when the power generation device is stopped when
With
When the acceleration request occurs, if the power storage state of the power storage device is greater than the first power storage state, control is performed by the first power generation device control means, and the power storage state of the power storage device is the first power storage state. A control device for a motor-driven vehicle, wherein control by the second power generation device control means is performed if it is smaller and larger than the second power storage state.   When the acceleration request is not generated and the power generation device is in operation, the charge control means is configured to reduce the storage state of the power storage device below a value larger than the first storage state by a predetermined value. 2. The motor-driven vehicle control device according to claim 1, wherein charging of the power storage device is started.   The motor-driven vehicle control device according to claim 2, wherein the predetermined value is set to a larger value as the power consumption of the auxiliary machinery is larger. A road surface transmittable driving force calculating means for estimating a friction coefficient between the tire of the vehicle and the road surface and calculating a driving force that can be transmitted to the road surface is further provided.
The power consumption calculating means calculates the power consumption of the motor so that the driving force of the motor does not exceed the driving force that can be transmitted to the road surface. The motor-driven vehicle control device described in 1.   The charge control unit is configured to cause the power storage state of the power storage device to exceed the first power storage state when the power storage state of the power storage device falls below the second power storage state and starts charging the power storage device. The control device for a motor-driven vehicle according to any one of claims 1 to 4, wherein the power storage device is continuously charged. Means for calculating charge / discharge power characteristics of the power storage device based on the temperature of the power storage device;
The said required electrical storage state calculating means calculates the said 1st electrical storage state and the said 2nd electrical storage state based on the said charging / discharging electric power characteristic, The any one of Claim 1-5 characterized by the above-mentioned. Motor drive vehicle control device.   The motor-driven vehicle control device according to claim 1, wherein the power generation device includes an engine and a generator.   The motor-driven vehicle control device according to any one of claims 1 to 6, wherein the power generation device includes a fuel cell.