JP3708976B2 - Electric vehicle speed control device - Google Patents

Description

[0001]
[Industrial application fields]
The present invention relates to a speed control device for an electric vehicle that controls the output torque of a driving motor to perform speed control at a constant speed.
[0002]
[Prior art]
In recent years, a constant speed (auto-cruise) device that can store a speed desired by a driver and automatically drive the vehicle at a constant speed without operating an accelerator pedal or the like is provided. More vehicles are installed.
[0003]
For example, in a gasoline engine vehicle, the constant speed traveling device controls the opening of the throttle valve so as to maintain a set vehicle speed (a vehicle speed desired and set by a driving vehicle) based on a vehicle speed signal from a vehicle speed sensor or the like. There is one that can run at a constant speed. In such travel control of a gasoline engine vehicle, it is difficult to accurately control the output torque determined by the fuel injection amount, the in-cylinder intake flow rate, and the like.
[0004]
On the other hand, for example, as disclosed in Japanese Patent Application Laid-Open No. 57-142104, there is an electric vehicle that can be driven at a constant speed by changing the output torque of the traveling motor so as to keep the set vehicle speed constant. .
[0005]
[Problems to be solved by the invention]
However, in general, a constant speed traveling device on an automobile highway or the like is effective when the road is free, but there is a problem that it cannot be used when the road is crowded.
[0006]
This is because a vehicle that is not equipped with a constant speed traveling device becomes slower or faster due to the effect of increase or decrease in traveling resistance such as a slight road gradient or wind. In other words, a vehicle that is running at a constant speed with a constant speed traveling device performs speed control and tries to run at a constant speed, but a vehicle that is not equipped with a constant speed traveling device has a constant accelerator (output) This is because when the running resistance fluctuates, there is a relative speed difference between the vehicle equipped with the constant speed traveling device and the vehicle not equipped with the constant speed traveling device.
[0007]
Further, in an electric vehicle, running at a constant speed even when the load (running resistance) fluctuates causes a problem that the output fluctuates and the battery or the like does not last long.
[0008]
The present invention has been made in view of the above circumstances, and even in a constant speed control state, when fluctuations in running resistance occur due to road gradients, strong winds, etc., the speed is controlled according to the running resistance, and natural traffic It is an object of the present invention to provide a speed control device for an electric vehicle that can travel along the flow of the battery and can make a battery or the like economical and long lasting.
[0009]
[Means for Solving the Problems]
In order to achieve the above object, the invention according to claim 1 is an electric vehicle speed control apparatus for controlling the torque of a motor for traveling so that the vehicle speed coincides with a set speed when constant speed traveling is selected. Means for calculating a torque change amount of the travel motor under control of high speed travel, means for comparing the torque change amount of the travel motor with preset positive and negative set values, and the travel motor When the torque change amount is greater than or equal to the positive set value, the means for increasing the set torque of the traveling motor and decreasing the set speed for keeping the vehicle speed constant, When the amount of torque change is less than or equal to the negative set value, there is provided means for decreasing the set torque of the traveling motor and increasing the set speed by a set amount.
[0010]
According to a second aspect of the present invention, in the first aspect of the present invention, at least one of the set values and set amounts is set according to operating conditions.
[0012]
[Action]
The invention according to claim 1 calculates the torque change amount of the traveling motor in the constant speed traveling control in which the torque of the traveling motor is controlled so that the vehicle speed matches the set speed by selection of the constant speed traveling. Then, the torque change amount of the traveling motor is compared with the positive and negative set values set in advance. When the torque change amount of the traveling motor is equal to or larger than the positive set value, the torque of the traveling motor is set to the set value. As the vehicle speed increases, the set speed to keep the vehicle speed constant is reduced by a set amount. On the other hand, when the amount of torque change of the travel motor is less than the negative set value, the travel motor torque is decreased and the set speed is decreased. Increase the set amount.
[0013]
In addition, as in the invention described in claim 2, it is desirable that at least one of the set values and the set amount is set according to operating conditions.
[0015]
【Example】
Embodiments of the present invention will be described below with reference to the drawings. 1 to 4 show an embodiment of the present invention, FIG. 1 is a circuit block diagram of a motor control system, FIG. 2 is a flowchart of irregular auto-cruise control, and FIG. 3 is an example of control in a vehicle performance chart. FIG. 4 is a schematic explanatory diagram showing FIG. 3 in terms of the position of the vehicle.
[0016]
In FIG. 1, reference numeral 1 denotes a running motor mounted on an electric vehicle, which is an AC induction motor in the present embodiment. The motor 1 is connected to a transaxle (not shown), and the driving force from the transaxle is transmitted to both front wheels (both not shown) via, for example, left and right front wheel shafts. Yes.
[0017]
The motor 1 is connected to a controller 2 and is connected via an inverter 3 of the controller 2 to a main battery 4 that is a main power source for driving driving.
[0018]
The controller 2 includes a microcomputer 9 to which a CPU 5, a ROM 6, a RAM 7, and an I / O interface 8 are connected via a bus. An output port of the I / O interface 8 is connected to the above-described output circuit via a drive circuit 10. An inverter 3 is connected.
[0019]
Then, the torque control of the motor 1 is performed by replacing the target torque calculated by the CPU 5 of the microcomputer 9 with a current command corresponding to the number of revolutions in the drive circuit 10, and instructing the inverter 3. The direct current voltage from the main battery 4 is converted into a high frequency of a predetermined voltage by the inverter 3.
[0020]
A connection line between the motor 1 and the inverter 3 is provided with a current sensor 11 for detecting the drive current of the motor 1. The current sensor 11 is connected to the microcomputer 9 with the I / I. The O interface 8 is connected.
[0021]
Further, a sensor / switch such as a rotational speed sensor 12 for detecting the rotational speed of the motor rotor of the motor 1, a vehicle speed sensor 13, a normal / abnormal auto cruise switch 14, an accelerator pedal switch 15, a brake pedal switch 16, etc. 9 is connected through the I / O interface 8.
[0022]
The normal / irregular auto-cruise switch 14 includes a “normal auto-cruise mode” (constant speed travel control mode; a mode in which the speed is kept constant even when the travel resistance fluctuates), and an “abnormal auto cruise mode” (substantially constant output control). This is a switch for switching to three modes: mode: mode for controlling the speed according to the running resistance, and “OFF mode” (normal manual running mode).
[0023]
The accelerator pedal switch 15 is connected to an accelerator pedal provided on the floor of the driver's seat of the electric vehicle, and is a switch that is turned on with a small stroke at the beginning of the depression of the accelerator pedal.
[0024]
Similarly, the brake pedal switch 16 is a switch that is turned on with a minute stroke at the beginning of the depression of the brake pedal.
[0025]
The accelerator pedal switch 15 and the brake pedal switch 16 are auto-cruise cancel switches that turn the normal / anomalous auto-cruise switch 14 into the “OFF mode” when turned on. As other switches, although not particularly shown, a shift switch connected to the base of the shift lever to detect the shift position is connected to the microcomputer 9 via the I / O interface 8.
[0026]
Next, speed control performed by the controller 2 when the normal / abnormal auto-cruise switch 14 is set to the “abnormal auto-cruise mode” will be described with reference to the flowchart of FIG.
[0027]
When the program starts, first, in step S1, the vehicle speed V is measured by a signal from the vehicle speed sensor 13, and the process proceeds to step S2, where a fixed vehicle speed Vc for constant speed travel is commanded as a vehicle speed V (V = Vc; V is a set speed). Then, the process proceeds to step S3, and the torque of the motor 1 at that time is stored in the RAM 7 as the initial torque T0 (T = T0; T is a set torque). The torque of the motor 1 is obtained based on a value from the current sensor 11 by a current-torque characteristic map or calculation formula stored in the ROM 6 in advance. Further, the torque instruction value commanded to the drive circuit 10 by the microcomputer 9 may be used as it is.
[0028]
Next, when the routine proceeds to step S4, it is determined whether or not the auto-cruise is canceled by the normal / abnormal auto-cruise switch 14, the accelerator pedal switch 15, the brake pedal switch 16, and other shift switches. If it has not been canceled, the process proceeds to step S5. If auto-cruise has been canceled, the process proceeds to step S6, where the normal manual travel control, that is, the “regular auto-cruise mode” is canceled and the “OFF mode” is set.
[0029]
If it is determined in step S4 that auto-cruise has not been canceled and the process proceeds to step S5, the torque value Ti at that time is read, and the process proceeds to step S7.
[0030]
In this step S7, it is determined whether or not torque fluctuation (load and running resistance fluctuation) is large, that is, whether or not Ti−T ≧ ΔT or Ti−T ≦ −ΔT (| Ti−T | ≧ ΔT). A determination is made. Here, ΔT is a torque change amount previously set in the ROM 6 through experiments or the like, and is set to, for example, ΔT = 0.5 kgf · m (corresponding driving force ΔF = 12.5 kgf). Yes.
[0031]
In step S7, if the torque fluctuation is small and Ti−T <ΔT or Ti−T> −ΔT (| Ti−T | <ΔT), the process returns to step S4 again, and the torque fluctuation is large. When −T ≧ ΔT or Ti−T ≦ −ΔT (| Ti−T | ≧ ΔT), the process proceeds to step S8 to command to fix the torque of the motor 1 in the changing direction. That is, in step S7, if Ti−T ≧ ΔT, T = T + ΔT, and if Ti−T ≦ −ΔT, T = T−ΔT.
[0032]
Next, when proceeding to step S9, similarly to step S4 above, it is again determined whether or not auto-cruise has been cancelled.If auto-cruise has not been cancelled, the routine proceeds to step S10 and auto-cruise is performed. If it has been canceled, the routine proceeds to step S6 above, and normal manual travel control, that is, "anomalous auto cruise mode" is canceled and the "OFF mode" is entered.
[0033]
If it is determined in step S9 that auto-cruise has not been canceled and the process proceeds to step S10, the torque fixing command is canceled, and the process proceeds to step S11 to command to change the fixed vehicle speed.
[0034]
That is, when Ti−T ≧ ΔT is determined in step S7, and T = T + ΔT is set in step S8, a fixed vehicle speed change command is issued as V = V−ΔV, and Ti−T ≦ T in step S7. When it is determined that −ΔT and T = T−ΔT in step S8, a fixed vehicle speed change command is issued as V = V + ΔV. Here, ΔV is a speed change amount previously set in the ROM 6 by experiments or the like, and is set to, for example, ΔV = 5 km / h (the corresponding rotation speed ΔN = 333 rpm of the motor 1).
[0035]
Then, after executing step S11, the process returns to step S4 again to repeat the control.
[0036]
Next, an example of the control in the “abnormal auto cruise mode” will be described with reference to FIGS. In the running performance diagram of FIG. 3, the curve indicated by the solid line descending to the right is the maximum driving force curve of the electric vehicle of this embodiment, and the curve indicated by the broken line to the right is a certain constant of the electric vehicle of this embodiment. A driving force (output) curve and a curve indicated by a solid line rising to the right indicate a running resistance curve for each road gradient.
[0037]
In this embodiment, the relationship among the driving force P (kW), torque Tq (kgf · m), and motor rotational speed N (rpm) is given by, for example, the equation P = Tq · N / 974. It is assumed that the maximum driving force curve is a 60 kW curve, and the constant driving force curve is a 30 kW curve. It is assumed that there is no running resistance other than road gradient.
[0038]
As shown in FIG. 4, first, a vehicle traveling at a speed V0 at a 0% gradient (flat) position x1 is indicated by point P0 in the traveling performance diagram of FIG.
[0039]
In this state, the driver sets the normal / abnormal auto-cruise switch 14 to the “abnormal auto-cruise mode”, and when the vehicle travels on a 3% slope road, the vehicle tries to maintain the speed V0. Torque is increased.
[0040]
When this increase in torque becomes ΔT or more, the torque of the motor 1 is commanded to be fixed at a value increased by ΔT (point P1 in FIG. 3), and the speed is further reduced by ΔV to become V1 as indicated by position x2 ( In FIG. 3, point P10), the torque fixing command for the motor 1 is released, and the vehicle is controlled to run at a constant speed at a speed V1.
[0041]
At this time, as shown in FIG. 3, in order to perform constant speed traveling at the speed V1, the torque of the motor 1 is further increased. When this torque increase becomes ΔT or more, the torque of the motor 1 is A fixed command is given to the value increased by ΔT (point P2 in FIG. 3), and the speed is further reduced by ΔV to V2 as shown in position x3 (point P20 in FIG. 3), and the torque fixing command for the motor 1 is released. The vehicle is controlled to run at a constant speed at a speed V2.
[0042]
As shown in FIG. 3, the torque of the motor 1 is further increased in order to run at a constant speed at the speed V2, and when this torque increase becomes ΔT or more, the torque of the motor 1 is ΔT The fixed value is commanded to the increased value (point P3 in FIG. 3), and the speed is further decreased by ΔV to become V3 as indicated by position x4 (point P30 in FIG. 3), and the torque fixing command for the motor 1 is released, The vehicle is controlled to run at a constant speed at a speed V3.
[0043]
Similarly, as shown in FIG. 3, since the vehicle runs at a constant speed at the speed V3, the torque of the motor 1 is further increased, and when this torque increase becomes ΔT or more, the torque of the motor 1 becomes ΔT The fixed value is commanded to the increased value (point P4 in FIG. 3), and the speed is further decreased by ΔV to become V4 as indicated by position x5 (point P40 in FIG. 3), and the torque fixing command for the motor 1 is released, The vehicle is controlled to run at a constant speed at a speed V4.
[0044]
Here, since the driving force is substantially appropriate for traveling on a road having a 3% gradient, large fluctuations in torque are eliminated even if the vehicle is controlled to travel at a constant speed at the speed V4.
[0045]
From this state, when the vehicle travels again on a road having a 0% gradient (flat), the torque of the motor 1 is reduced because the vehicle tries to maintain the speed V4.
[0046]
When this torque decrease becomes ΔT or more, the torque of the motor 1 is commanded to be fixed at a value decreased by ΔT (point P5 in FIG. 3), and the speed is further increased by ΔV to become V3 as shown in the position x6 ( At point P30 in FIG. 3, the torque fixing command of the motor 1 is released, and the vehicle is controlled to run at a constant speed at a speed V3.
[0047]
At this time, as shown in FIG. 3, the torque of the motor 1 is further reduced in order to run at a constant speed at the speed V3, and when this torque reduction becomes ΔT or more, the torque of the motor 1 is A fixed command is given to a value reduced by ΔT (point P6 in FIG. 3), and the speed is further increased by ΔV to V2 as shown in position x7 (point P20 in FIG. 3), and the torque fixing command for the motor 1 is released. The vehicle is controlled to run at a constant speed at a speed V2.
[0048]
Then, as shown in FIG. 3, in order to run at a constant speed at a speed V2, the torque of the motor 1 is further reduced. When this torque reduction is equal to or greater than ΔT, the torque of the motor 1 is ΔT The fixed value is commanded to the decreased value (point P7 in FIG. 3), and the speed is further increased by ΔV to become V1 as indicated by position x8 (point P10 in FIG. 3), and the torque fixing command for the motor 1 is released, The vehicle is controlled to run at a constant speed at a speed V1.
[0049]
Similarly, as shown in FIG. 3, since the vehicle runs at a constant speed at a speed V1, the torque of the motor 1 is further reduced. When this torque reduction becomes equal to or greater than ΔT, the torque of the motor 1 becomes ΔT The fixed value is commanded to a decreased value (point P8 in FIG. 3), and the speed is further increased by ΔV to become V0 as indicated by position x9 (point P0 in FIG. 3), and the torque fixing command for the motor 1 is released, The vehicle is controlled to run at a constant speed at a speed V0.
[0050]
Here, since the driving force is substantially appropriate for traveling on a road having a 0% gradient, even if control is performed so that the vehicle travels at a constant speed at a speed V0, there is no significant fluctuation in torque.
[0051]
As a result of such control, as shown in FIG. 3, even when the running resistance for each road gradient fluctuates from 0% gradient → 3% gradient → 0% gradient, “anomalous auto cruise mode” It is possible to travel with a substantially constant driving force (a constant driving force indicated by a broken line) when set to.
[0052]
For this reason, for example, traveling at a speed close to the constant accelerator (constant output), which is slowed or increased due to the influence of increase or decrease in traveling resistance such as a slight road gradient or wind, in front of the driving vehicle. Even in the case where there is a vehicle, in the “anomalous auto-cruise mode”, the speed changes in the same manner, so that it is possible to travel along a natural traffic flow without causing a relative speed difference.
[0053]
Further, since the vehicle can travel with a substantially constant driving force (output), the battery current given by ΔW = i ² · R (ΔW: motor output, i: battery current, R: resistance) is made substantially constant. It is possible to prevent overload, and economical driving is possible, so that the cruising distance of the vehicle and the battery life can be extended.
[0054]
In the present embodiment, in the flowchart of FIG. 2, the reference value of torque fluctuation determined in step S7, that is, the torque fluctuation amount and the torque change amount changed in step S8 are set in advance as ΔT. The reference value for increasing torque fluctuation, the reference value for decreasing torque fluctuation, the amount of torque change to be increased, and the amount of torque change to be decreased may be set differently. The reference value and the reference value of the decreasing torque fluctuation may be set to the same value, and the torque change amount to be increased and the torque change amount to be decreased may be set differently.
[0055]
In addition, the reference value for increasing torque fluctuation, the reference value for decreasing torque fluctuation, the amount of torque change to be increased, and the amount of torque change to be reduced are not fixed values, for example, depending on driving conditions such as vehicle speed. It may be previously set with a map or the like so that it can be changed.
[0056]
Further, in this embodiment, ΔT is set to 0.5 kgf · m, for example, but it can be set to a value smaller than this value (for example, 0.1 kgf · m 2) so that finer smooth control can be performed. On the other hand, the convergence may be improved by setting the value larger than 0.5 kgf · m (for example, 1.0 kgf · m). Further, if the value of ΔT is made variable according to the driving state in this way (for example, ΔT is set to a large value in the transient driving state, and ΔT is set to a small value when relatively stable running continues). Can be used effectively.
[0057]
In the present embodiment, in the flowchart of FIG. 2, the speed change amount ΔV in step S11 is the same value when the speed is increased and when the speed is decreased, but may be set to different values. Further, for example, a map or the like may be set in advance so that it can be changed according to driving conditions such as vehicle speed.
[0058]
In this embodiment, ΔV is set to 5 km / h, for example, but is not limited to this value.
[0059]
Further, in the present embodiment, the vehicle speed is obtained from the vehicle speed sensor, but may be obtained by calculating from the motor rotation speed and the gear ratio.
[0060]
In the present embodiment, an example in which the traveling motor is an AC induction motor has been described. However, the present invention is not limited to this, and the motor may be an AC synchronous motor or a DC motor.
[0061]
【The invention's effect】
As described above, according to the first aspect of the present invention, when the running resistance varies due to road gradient or strong wind in the constant speed control state, the torque change amount of the running motor increases or decreases. The fluctuation of the running resistance is determined from the torque change amount of the running motor. Then, when the amount of torque change of the traveling motor is compared with preset positive and negative set values, and when the amount of torque change of the traveling motor is greater than the positive set value and it is determined that the traveling resistance is increased Increases the set value of the torque of the driving motor and decreases the set speed for keeping the vehicle speed constant . On the other hand, when the torque change amount of the traveling motor is equal to or less than the negative set value and it is determined that the traveling resistance is decreased, the torque of the traveling motor is decreased by the set value and the set speed is increased by the set amount. Even in a constant speed control state, when driving resistance fluctuates due to road gradients, strong winds, etc., it is possible to control the driving force and vehicle speed according to the driving resistance, and travel according to the natural traffic flow. It becomes.
Also, in the constant speed control state, when the running resistance is increased, the set speed is lowered to decrease the vehicle speed as the running motor torque is increased, and when the running resistance is reduced, the torque of the running motor is increased. Since the set speed is increased and the vehicle speed is increased as the speed is decreased, the change in the driving force is relatively suppressed. In other words, since the vehicle can run with a substantially constant driving force, the battery current is reduced. It is possible to maintain a constant value, and it is possible to prevent an overload and to run economically, so that a battery or the like can be made economical and long lasting.
[0062]
According to the invention described in claim 2 , since at least one of the set values and the set amount is set according to the operating condition, in addition to the effect of the invention according to claim 1, it is determined according to the operating state. Detailed control is possible, and it is possible to travel more naturally along the traffic flow and to perform more efficient travel.
[0063]
Furthermore, according to the third aspect of the invention, when the driver performs the constant speed traveling by the irregular constant speed traveling control means, in addition to the effect of the invention according to the second aspect, a preset torque fluctuation amount, Since at least one of the preset torque change amount, the preset speed change amount to be set to decrease, and the preset speed change amount to be set to increase is set variably according to the driving state, the driving state Therefore, the vehicle can travel more naturally along the traffic flow, and can travel more efficiently.
[Brief description of the drawings]
FIG. 1 is a circuit block diagram of a motor control system according to an embodiment of the present invention. FIG. 2 is a flowchart of an irregular auto cruise control according to an embodiment of the present invention. Explanatory diagram shown in vehicle performance diagram [FIG. 4] Schematic explanatory diagram showing FIG. 3 in terms of vehicle position
1 Driving Motor 2 Controller 14 Normal / Anomalous Auto Cruise Switch T Set Torque Ti Output Torque V Set Speed ΔT Preset torque fluctuation (torque change)
ΔV Preset speed change

Claims (2)

In a speed control device for an electric vehicle that controls the torque of a motor for traveling so that the vehicle speed matches a set speed when constant speed traveling is selected,
Means for calculating a torque change amount of the traveling motor under the control of the constant speed traveling;
Means for comparing the torque change amount of the traveling motor with a preset positive and negative set value;
When the torque variation of the traction motor is equal to or greater than the positive set value, means for lowering the set amount of the set speed to keep the vehicle speed constant with increasing setpoint torque of the traction motor,
When the torque variation of the traction motor is equal to or less than the negative of the set value, electric, characterized in that a means for increasing the set amount of the set speed while reducing torque setting value of the traction motor Automobile speed control device. 2. The speed control apparatus for an electric vehicle according to claim 1, wherein at least one of the set values and the set amounts is set according to driving conditions.

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