JP2010206924A - Method of controlling motor for electric vehicle, and drive device for electric vehicle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To maintain the sense of comfortability of each occupant in a good state by reducing a shock generated in switching the output characteristics of an electric motor for rotating and driving the driving wheels of a vehicle. <P>SOLUTION: A control method for controlling the electric motor 5 for driving the vehicle includes: a measuring step (S9) of measuring a shock generated on the vehicle 1 in switching the output characteristics of the electric motor 5 as a switching shock, and a changing step (S15) of changing a target current value Ima into an increase direction when the output characteristics are switched next time when it is determined that the measured switching shock is not less than a predetermine value. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an output characteristic of an electric motor that rotationally drives a driving wheel of a vehicle, a low-speed mode corresponding to a low-rotation operation region with a predetermined switching rotational speed as a boundary, and a high-rotation operation region. The present invention relates to a motor control method and the like of an electric vehicle that is switched between high-speed modes that can handle up to.

  Conventionally, in the field of automobiles, a so-called electric vehicle using an electric motor as a power source instead of a conventional vehicle using an internal combustion engine such as a gasoline engine or a diesel engine for the purpose of further improving emission performance and fuel efficiency performance. As is well known, so-called hybrid vehicles using an electric motor in combination with an internal combustion engine have been developed.

  As described above, in a vehicle using an electric motor as at least a part of a power source (hereinafter, such a vehicle is referred to as an electric vehicle) in order to make the output characteristics of the electric motor correspond to various traveling scenes of the vehicle. It is desirable to control the electric motor so as to cover a relatively wide range of rotation speeds.

  For example, in the following Patent Document 1, when a condition such that the rotational speed of the electric motor exceeds a predetermined threshold is satisfied, the electric motor is switched by switching the connection state of the winding of the electric motor or switching the field control method. The output characteristic is changed to a characteristic that can cope with a region closer to a higher rotation speed.

JP-A-6-225588

  By the way, according to the switching of the connection as described above, the output characteristic of the electric motor is switched between the output characteristic corresponding to the operation region near the low rotation and the output characteristic corresponding to the operation region near the high rotation. In this case, it is considered that the torque transmitted to the drive wheels of the vehicle temporarily varies because the actual output torque varies although the required torque is the same before and after switching. At this time, if the gear engagement between the motor side gear and the vehicle side gear in the gear train of the vehicle is momentarily disengaged, a large shock is generated in the vehicle when the gear meshes again, and passenger comfort is impaired. It is desirable to reduce as much as possible the shock generated in the vehicle by reducing the torque fluctuation as described above.

  The present invention has been made in view of the circumstances as described above, and reduces the shock that occurs when the output characteristics of the electric motor that rotationally drives the drive wheels of the vehicle is switched to maintain good passenger comfort. The purpose is to do.

  In order to solve the above-described problems, the present invention provides an output characteristic of an electric motor that rotationally drives a driving wheel of a vehicle, and a low-speed mode corresponding to a low-rotation driving region with a predetermined switching rotational speed as a boundary. A motor control method for an electric vehicle that switches between a high-speed mode that can cope with a driving region closer to a higher rotation than this, and a measurement step that measures a shock generated in the vehicle at the time of switching the output characteristics as a switching shock And a change step of changing the target current value of the electric motor in an increasing direction at the next switching of the output characteristics when the measured switching shock is determined to be equal to or greater than a predetermined value. (Claim 1).

  According to the present invention, the switching shock is measured when switching the output characteristics of the electric motor, and if the value is equal to or greater than the predetermined value, the target current value of the electric motor is changed in the increasing direction. There is an advantage that it can be suppressed to a small level, and the shock transmitted to the occupant when the output characteristics are switched can be reduced to maintain the occupant comfort satisfactorily.

  In addition, even if there is a variation in the output of each motor, the target current value is changed by learning based on the actual measurement value of the switching shock, so that the target current value is optimized for each individual and the switching shock is effectively performed. There is an advantage that it can be reduced.

  In the present invention, preferably, the method includes a comparison step for comparing the change shock before and after the change of the target current value in the change step, and as a result of the comparison in the comparison step, the change in the increase direction of the target current value When it is confirmed that the switching shock has become smaller than the previous time, the change in the target current value in the increasing direction is repeated until the switching shock falls below a predetermined value (Claim 2).

  In this way, for example, there is an advantage that the comfort of the occupant can be improved reliably by repeatedly changing the control parameter until the switching shock is reduced to a level at which the occupant does not feel discomfort.

  As a result of the comparison in the comparison step, when it is confirmed that the switching shock has become larger than the previous time due to the change in the target current value in the increasing direction, the target current value in the increasing direction thereafter is increased. It is preferable to prohibit the change (claim 3).

  In this way, even if the switching shock does not become less than the predetermined value, it can be suppressed to the minimum switching shock as much as possible, and the increase of the switching shock accompanying the change of the target current value can be suppressed. There are advantages.

  In this case, if it is confirmed as a result of the comparison in the comparison step that the switching shock has become larger than the previous time due to the change in the target current value in the increasing direction, the value of the switching rotational speed is set to It is preferable to change (Claim 4).

  In this way, even if the change effect of the target current does not provide a sufficient switching shock reduction effect, there is an advantage that the switching shock can be reliably suppressed below a predetermined value and passenger comfort can be sufficiently secured. .

  The present invention also relates to an electric motor that rotationally drives a drive wheel of a vehicle, and an output characteristic of the electric motor, and a low-speed mode corresponding to a low-rotation driving region with a predetermined switching rotational speed as a boundary. And a control means for switching between a high-speed mode capable of dealing with a driving region close to a high rotation speed, wherein the control means applies a shock generated to the vehicle when the output characteristics are switched. Measuring means for measuring as a switching shock, and changing means for changing the target current value of the electric motor in an increasing direction at the next switching of output characteristics when the measured switching shock is determined to be equal to or greater than a predetermined value. It is characterized by providing (Claim 5).

  Even in the case of the present invention, it is possible to obtain the same operational effects as in the case of the motor control method described above.

  As described above, according to the present invention, it is possible to reduce the shock that occurs when the output characteristics of the electric motor that rotationally drives the drive wheels of the vehicle are switched, and to maintain good passenger comfort.

1 is a schematic plan view showing an overall configuration of an electric vehicle drive device to which a motor control method according to an embodiment of the present invention is applied. It is a block diagram which shows the control system of the said drive device for electric vehicles. It is a circuit diagram which shows electric structures, such as an electric motor and an inverter, in the said drive device for electric vehicles. It is a figure for demonstrating the output characteristic of the said electric motor. It is a figure which shows an example of the relationship between the request torque at the time of switching from low speed mode to high speed mode, and actual output torque. It is a figure which shows the change of the actual output torque at the time of changing a request torque at the time of the said switching. It is a figure which shows the change of the target electric current value at the time of the said switching. It is a flowchart which shows the content of the control action performed during the drive of the said electric motor. It is a graph for demonstrating a mode that a switching shock changes with the change of the said target electric current value, (a) has shown the switching shock and (b) has shown the target electric current value.

  FIG. 1 is a schematic plan view showing an overall configuration of an electric vehicle drive device to which a motor control method according to an embodiment of the present invention is applied, and FIG. 2 is a block diagram showing a control system of the electric vehicle drive device. is there. The drive device for an electric vehicle shown in these drawings is configured as a drive device for driving an electric vehicle 1 (hereinafter simply referred to as a vehicle 1) composed of a hybrid vehicle. Specifically, the electric vehicle drive device includes an engine 2 that is a gasoline engine or a diesel engine provided as a power source for power generation, and starts the engine 2 when necessary, and obtains driving force from the engine 2. A generator 3 that generates electric power, a battery 9 as a power storage device that stores electric power generated by the generator 3, and an electric motor that is provided as a driving power source and drives the vehicle 1 by receiving electric power from the battery 9. A motor 5, a first inverter 11 and a second inverter 12 that drive the generator 3 and the electric motor 5 by converting the power supplied from the battery 9 to alternating current, and a controller 15 that controls these components in a centralized manner Equivalent to the control means according to the invention.

  The electric motor 5 is linked to a drive shaft 8 via a gear train 6 and a differential device 7, and passes through a power transmission path including the gear train 6, the differential device 7, and the drive shaft 8. Thus, the driving force of the electric motor 5 is transmitted to the pair of left and right drive wheels 16 connected to the drive shaft 8. In the vehicle 1 of the present embodiment, two of the four wheels provided on the front, rear, left and right are drive wheels 16 and the remaining wheels are driven wheels 17.

  The electric motor 5 is composed of, for example, a three-phase AC synchronous motor or the like, and receives power from the battery 9 via the second inverter 12 when necessary, so that the drive shaft 8 and the drive are driven via the gear train 6 and the like. While driving the wheel 16, the vehicle is configured to generate power by obtaining a driving force from the drive shaft 8 during deceleration or traveling downhill, and to store the generated power in the battery 9.

  The generator 3 receives a supply of electric power from the battery 9 via the first inverter 11 when the engine 2 is started, thereby forcibly rotating the crankshaft of the engine 2 to start the engine 2, and It has both functions as an alternator that generates driving power from the crankshaft of the engine 2.

  The controller 15 includes a well-known CPU, ROM, RAM, I / O (input / output interface), and the like, and various control programs necessary for driving the vehicle 1 are stored in the ROM in advance. The RAM stores various work memories necessary for executing the control program.

  As shown in FIG. 2, various sensors provided in each part of the vehicle 1 are electrically connected to the controller 15. Specifically, the controller 15 includes a vehicle speed sensor 30 that detects the traveling speed (vehicle speed) of the vehicle 1, an accelerator opening sensor 31 that detects an opening degree TVO of an accelerator pedal (not shown) that is depressed by a driver, An engine rotation speed sensor 32 that detects the rotation speed of the crankshaft of the engine 2, a generator rotation speed sensor 33 that detects the shaft rotation speed of the generator 3, and an input current input from the battery 9 to the generator 3 or power generation by the generator 3 Generator current sensor 34 that detects the output current that is output to the battery 9, the motor rotation speed sensor 35 that detects the shaft rotation speed N of the electric motor 5, and the motor current sensor that detects the input / output current of the electric motor 5. 36, a battery sensor 37 that detects the remaining capacity of the battery 9, and the vehicle 1. A G sensor 38 for detecting a deceleration α are respectively connected, various control information detected by the sensors 30 to 38 is adapted to be inputted as an electric signal to the controller 15.

  And the said controller 15 performs various calculations based on the input information from each said sensors 30-38, Based on the result, the said engine 2, the generator 3, the electric motor 5, and inverter 11,12 grade | etc., Are carried out. Control the overall operation. And by controlling each part by the controller 15 in this way, in the vehicle 1 of this embodiment, the electric motor 5 is driven and controlled based on the accelerator operation or the like of the driver, and the traveling speed of the vehicle 1 is adjusted. For example, when the remaining capacity of the battery 9 decreases, the engine 2 is started and the generator 3 generates power, and the generated power is replenished to the battery 9.

  FIG. 3 is a circuit diagram of the generator 3, the electric motor 5, and the inverters 11 and 12. As shown in this figure, each phase (U phase, V phase, W phase) of the electric motor 5 has two windings composed of a first winding L1 and a second winding L2 connected in series. The second inverter 12 is provided with a switching element Sw as means for switching the path of the current flowing through the windings L1 and L2 of the respective phases. Then, according to the switching operation by the switching element Sw, the current Im from the second inverter 12 flows through both the first and second windings L1 and L2, and only the first winding L1 among them. The current path is switched between the state where the current Im flows.

  FIG. 4 is a diagram illustrating output characteristics of the electric motor 5. In FIG. 4, a characteristic line A1 indicated by a thick line indicates an output characteristic when a current is passed through both the first and second windings L1 and L2, and a characteristic line A2 indicated by a thin line indicates the first winding. Output characteristics when current is supplied only to L1 are shown. As shown in the figure, when a current is passed through only the first winding L1 (in the case of the characteristic line A2), compared with a case where a current is passed through both the windings L1 and L2 (in the case of the characteristic line A1). Thus, although the shaft torque T of the electric motor 5 decreases, the electric motor 5 can be driven to a higher rotational speed. This is due to the following reason.

  That is, when current flows through the first and second windings L1 and L2 of the electric motor 5, the electric motor 5 has an induced voltage Va corresponding to the motor rotational speed N as shown in FIG. Although this occurs, while this induced voltage Va is smaller than the voltage Vdc on the inverter 12 side, a current Im flows from the inverter 12 side to the electric motor 5 due to the potential difference. However, when the motor rotation speed N further increases from this state and the induced voltage Va becomes substantially equal to the inverter-side voltage Vdc, the current Im does not flow to the electric motor 5, and the limit line AL of the characteristic line A1 in FIG. As shown, the torque T of the electric motor 5 rapidly decreases. Therefore, if the current path is switched by the switching element Sw before the current Im stops flowing so that the current Im bypasses the second winding L2 and flows only to the first winding L1, the motor is driven by that amount. Since the induced voltage Va of the motor 5 decreases, a potential difference can be generated between the inverter 12 and the electric motor 5 even in the region on the higher rotation side than the limit line AL. It becomes possible to drive.

  As described above, in this embodiment, a plurality of windings L1 and L2 connected in series are provided in each phase of the electric motor 5, and a current flows through all or part of the plurality of windings L1 and L2. By switching the path, the output characteristics of the electric motor 5 are characterized by a characteristic corresponding to the driving region near the low rotation (characteristic line A1 in FIG. 4) and a characteristic corresponding to the driving region near the high rotation (characteristic line A2). Is switched as appropriate. In the following description, the state in which the electric motor 5 is controlled so as to obtain output characteristics such as the characteristic line A1 by flowing current through both the first and second windings L1 and L2 is a low speed mode. A state in which the electric motor 5 is controlled so that an output characteristic such as the characteristic line A2 is obtained by passing a current only through the first winding L1 is referred to as a high-speed mode.

  As shown in FIG. 4, the switching between the low speed mode and the high speed mode is performed when the rotation speed N of the electric motor 5 passes through a switching line P set in advance in the overlapping portion between the low speed mode and the high speed mode. To be executed. Specifically, the switching line P has a large switching rotational speed Nt, which is a threshold for switching the output characteristics of the electric motor 5 between the low speed mode and the high speed mode, in relation to the torque value of the electric motor 5. It is defined in a dot shape, and is formed by continuously connecting the switching rotational speed Nt for each torque value. In FIG. 4, the switching line P is set to be inclined slightly upward to the right, but this is in consideration of electrical efficiency.

  An arrow D1 in FIG. 4 indicates that the rotation speed N is higher than that of the switching line P when the electric motor 5 is driven in the low speed mode because the rotation speed N is on the lower rotation side than the switching line P. When the rotation speed N changes from the low rotation side to the high rotation side across the switching line P as described above, the output characteristics of the electric motor 5 change from the low speed mode. Switch to high-speed mode. On the other hand, in contrast to the arrow D1, when the electric motor 5 is driven in the high speed mode and the rotation speed N decreases to a region on the lower rotation side than the switching line P, the electric motor 5 is switched from the high speed mode to the low speed mode.

  As described above, when the output characteristic of the electric motor 5 is switched between the low speed mode and the high speed mode with the switching line P (switching rotation speed Nt) as a boundary, a shock is generated in the vehicle 1 according to the switching. Sometimes. This is due to the following reason.

  FIG. 5 is a diagram showing an example of actual output torque when the low speed mode is switched to the high speed mode. At time t1 in the figure, in order to switch the output characteristics of the electric motor 5 from the low speed mode to the high speed mode, the switching element Sw shown in FIG. 3 is operated so that current flows only through the first winding L1. Represents the point in time of switching. The required torque value is the same in the low speed mode immediately before the switching time t1 and the high speed mode immediately after, but the actual output torque is not always the same in the low speed mode and the high speed mode, and varies. There is a possibility. For example, as shown in FIG. 5, the actual output torque T2 in the low speed mode varies to the high torque side with respect to the required torque (command torque from the controller 15) T1, and the actual output torque T3 in the high speed mode is low torque. If the difference is large, the gear engagement between the motor side gear and the vehicle side gear in the gear train of the vehicle 1 is momentarily separated at the time of switching. Then, when the disengaged gear meshes again, a relatively large shock is generated in the vehicle 1 and this is transmitted to the occupant. Therefore, it is possible to reduce the difference between the actual output torque in the low speed mode immediately before the switching and the actual output torque in the high speed mode immediately after the switching, and to prevent the gear meshing from being momentarily separated. It is important in reducing the shock that occurs.

  Therefore, in the present embodiment, as shown by a two-dot chain line in FIG. 6, the required torque T1b in the high speed mode immediately after the switching time t1 is set larger than the required torque T1a in the low speed mode immediately before the switching with a predetermined correction amount. Thus, the actual output torque T3 immediately after switching to the high speed mode at the switching time t1 is increased. Thereby, the difference from the actual output torque T2 in the low-speed mode before switching is reduced, and the shock generated in the vehicle 1 is reduced.

  The torque can be controlled by controlling the target current value Ima. FIG. 7 is a diagram showing control of the target current value corresponding to the required torque shown in FIG. When the low-speed mode target current immediately before the switching is Ima0 and the target current in the high-speed mode immediately after the switching is Ima1 with respect to the same required torque immediately before and immediately after the switching, there is no variation in the actual output torque between the two. There is no shock for the same amount of variation in the direction. On the other hand, as shown in FIG. 5, when the difference between the actual output torque in the low-speed mode immediately before switching and the actual output torque in the high-speed mode immediately after switching becomes large due to the variation, a shock occurs. By setting the mode target current to a target current value Ima2 that is a predetermined amount larger than Ima1, the actual output torque in the high-speed mode immediately after switching increases. As a result, the difference from the actual output torque in the low speed mode immediately before switching is reduced, and the shock generated in the vehicle 1 is reduced.

  In the above description, the movement of the target current value Ima set when the output characteristic of the electric motor 5 is switched from the low speed mode to the high speed mode has been described. However, the output characteristic of the electric motor 5 is switched from the high speed mode to the low speed mode. At the same time, the target current value Ima is corrected in the same manner as described above in order to reduce the shock at the time of switching. However, the shock occurs when switching from the high speed mode to the low speed mode when the output torque immediately after switching to the low speed mode is lower than the output torque in the high speed mode immediately before switching due to variations in the actual output torque. In this case, the target current value Ima0 in the low speed mode immediately after switching may be corrected in the increasing direction.

  Returning to FIG. 2 again, the function of the controller 15 relating to the setting of the target current value Ima of the electric motor 5 will be specifically described. As shown in the figure, the controller 15 includes measuring means 15a, changing means 15b, and comparing means 15c as functional elements.

  The measuring means 15a measures a shock generated in the vehicle 1 as a switching shock when the output characteristic of the electric motor 5 is switched between the low speed mode and the high speed mode. Specifically, the measuring means 15a measures the change in the acceleration / deceleration α that occurs when the output characteristic of the electric motor 5 is switched based on the detection value of the G sensor 38 (FIG. 2). Change is acquired as the switching shock. There is a method of detecting a shock by installing a torque sensor on the output shaft of the motor or attaching a magnetic shock sensor to the vehicle. In addition, the shock can be detected in conjunction with a sensor (for example, a current signal of a current detector that detects the inverter output current) that detects the amount of electricity whose signal changes due to the shock.

  When the switching shock measured by the measuring unit 15a is equal to or greater than a predetermined threshold, the changing unit 15b changes the target current value Ima as a control parameter that affects the switching shock at the next output characteristic switching. Is. That is, the changing unit 15b changes the target current value Ima temporarily set immediately after the current path switching time t1 in an increasing direction with respect to the original target current value Ima1, and sets the target current value Ima2 to the target current value Ima2. (See FIG. 7).

  The comparison means 15c compares the switching shock measured immediately before the target current value is changed by the changing means 15b with the switching shock measured after the change.

  Next, specific contents of the control operation performed by the controller 15 configured as described above will be described with reference to the flowchart of FIG. When this flowchart starts, the controller 15 first executes control for reading the rotational speed N of the electric motor 5 and the accelerator pedal opening TVO based on the detection values of the accelerator opening sensor 31 and the motor rotation speed sensor 35. (Step S1).

  Next, the controller 15 executes control for determining whether or not the current output characteristic of the electric motor 5 is set to the low speed mode based on the operating state of the switching element Sw of the second inverter 12 (step S2). ). That is, as described above, if the current path is set so that current flows through both of the two windings L1 and L2 of the electric motor 5 in accordance with the operating state of the switching element Sw, the electric motor Since the low speed mode is selected as the output characteristic of the motor 5, it is determined that the electric motor 5 is driven in the low speed mode when the switching element Sw is in the operating state as described above.

  When it is determined YES in step S2 and it is confirmed that the output characteristic of the electric motor 5 is set to the low speed mode, the controller 15 determines that the rotation speed N of the electric motor 5 read in step S1 is Control for determining whether or not the rotational speed Nt is equal to or higher than that shown in FIG. 4 is executed (step S3). That is, based on the rotational speed N of the electric motor 5 and the current required torque obtained from the accelerator opening TVO or the like, the current driving state of the electric motor 5 corresponds to which position in the characteristic diagram of FIG. It is determined whether or not the motor rotation speed N is equal to or higher than the switching rotation speed Nt by determining whether or not the position is on the higher rotation side than the switching line P.

  When it is determined YES in Step S3 and N ≧ Nt is confirmed, the controller 15 should be set at the time of switching as preparation for switching the output characteristics of the electric motor 5 from the low speed mode to the high speed mode. Control for reading the target current value Ima is executed (step S4). Specifically, the target current value Ima here is basically determined based on the current motor rotation speed N and the required torque. At this time, the target current that has been changed in steps S15 and S16, which will be described later. If a value (for example, Ima2 shown in FIG. 7) already exists, that value is read as the target current value Ima, whereas if it does not exist, it is determined beforehand in relation to the motor rotational speed N and the required torque. The set default value is read as the target current value Ima. Note that this default value is a target current value that is originally necessary after the high-speed mode switching, and is Ima1 in the example of FIG.

  When the target current value Ima at the time of switching the output characteristics is determined in this way, the controller 15 operates the switching element Sw of the second inverter 12, and the first and second windings L1, L2 of the electric motor 5 are operated. Of these, the control is performed to switch the output characteristic of the electric motor 5 from the low speed mode to the high speed mode by switching the current path so that the current flows only through the first winding L1 (step S5).

  On the other hand, if it is determined NO in step S3 and it is confirmed that the motor rotational speed N has not yet reached the switching rotational speed Nt or higher, the routine returns without performing the switching operation as described above, and the electric motor The output characteristic of 5 is maintained in the low speed mode.

  Next, a description will be given of the control operation when it is determined NO in step S2, that is, when the current output characteristic of the electric motor 5 is set to the high speed mode. In this case, the controller 15 executes control for determining whether or not the rotation speed N of the electric motor 5 read in step S1 is lower than the switching rotation speed Nt shown in FIG. 4 (step S6).

  When YES is determined in step S6 and it is confirmed that N <Nt, the controller 15 is set at the time of switching as preparation for switching the output characteristics of the electric motor 5 from the high speed mode to the low speed mode. Control for reading the target current value Ima to be executed is executed (step S7). When the target current value Ima at this time is the target current value that has already been changed (the target current value changed in steps S15 and S16), as in step S4, the target current value Ima does not exist. Is set to a default value (for example, Ima0 shown in FIG. 7).

  When the target current value Ima at the time of switching the output characteristics is determined in this way, the controller 15 operates the switching element Sw so that current flows through both the first and second windings L1 and L2. By switching the path, control is performed to switch the output characteristics of the electric motor 5 from the high speed mode to the low speed mode (step S8).

  On the other hand, if it is determined NO in step S6 and it is confirmed that the motor rotational speed N has not yet decreased below the switching rotational speed Nt, the process returns without performing the switching operation as described above, The output characteristics of the motor 5 are maintained in the high speed mode.

  Next, the control operation performed after the output characteristic of the electric motor 5 is switched from the low speed mode to the high speed mode or from the high speed mode to the low speed mode in step S5 or step S8 will be described. After switching the output characteristics in step S5 or step S8, the controller 15 calculates the change in the acceleration / deceleration α before and after the switching of the output characteristics based on the detection value of the G sensor 38. While acquiring as a switching shock (step 9), the control which determines whether the value is more than a predetermined threshold value is performed (step S10).

  When it is determined as YES in step S10 and it is confirmed that the switching shock is equal to or greater than the threshold, the controller 15 switches the output characteristics in step S5 or step S8 and the measurement in step S9. The control which memorize | stores the made switching shock is performed (step S11). Here, the switching condition is a condition to be considered in determining the change width of the target current value Ima at the time of switching. Specific examples of the switching condition include, for example, the switching direction of the output characteristics ( That is, whether the mode is switched from the low speed mode to the high speed mode or vice versa), the required torque at the time of switching, the motor rotation speed, and the like can be considered. Of these, at least the switching direction of the output characteristics is preferably considered as a switching condition.

  Next, the controller 15 executes control for determining whether or not the switching shock measured under the same switching condition is already stored (step S12). If the switch shock storage data under the same condition already exists, it is determined whether or not the target current value Ima is the value returned to the previous value in step S16 described later (step S13). Next, if the value is the value previously returned in step S16, the process returns. If not, the control is executed to determine whether or not the switching shock stored this time is smaller than the switching shock stored last time. (Step S14).

  When it is determined as YES in step S14 and it is confirmed that the current value is smaller than the previous switching shock, the controller 15 executes control to change the target current value Ima in the increasing direction (step S15). On the other hand, when it is determined NO in step S14, the target current value Ima is returned to the previous value. (Step S16).

  If NO is determined in step S12, that is, if there is no switching shock storage data under the same switching condition, the control proceeds to step S15 to change the target current value Ima in the increasing direction. Is executed.

  When the change process of the target current value Ima is completed as described above, the controller 15 executes control to store the changed target current value Ima (step S17), and returns. Note that the storage of the target current value Ima has a different value for each switching condition, and the target current value stored for each switching condition is read out in steps S4 and S7.

  As described in steps S14 to S17 above, in the control flow of this embodiment, when the switching shock occurs, the target current value Ima is changed in the increasing direction, and the switching shock newly measured after the change is the previous one. If the current switching shock is smaller than the previous switching shock as compared with the switching shock, the target current value Ima is changed until the switching shock falls below the threshold (until NO is determined in step S10). By repeating, an appropriate target current value Ima that can reduce the switching shock below the threshold value is learned. In addition, when the switching shock does not fall below the threshold and the shock increases due to the change of the target current value Ima, the target current value before the change is returned.

  FIGS. 9A and 9B are graphs illustrating how the switching shock changes in accordance with the process of changing the target current value Ima based on the flowchart of FIG. 8 described above. In these drawings, the number of times of switching on the horizontal axis represents the number of times of switching under the same switching condition.

  According to the examples of FIGS. 9A and 9B, the switching shock exceeds the threshold at the first switching when the target current value Ima is set to a predetermined default value, that is, the target current value that is originally required. In response to this, the target current value Ima has been changed since the next switching. Specifically, in the second switching, the target current value Ima is changed in the increasing direction. According to FIG. 9A, the switching shock is reduced as the target current value Ima increases. However, since the target current value Ima has been changed in the increasing direction at the third switching, and the switching shock has decreased below the threshold at the third switching, the switching shock is reduced thereafter. The same value as that set for the third time is maintained as the target current value Ima.

  As described above, the electric vehicle drive device of the present embodiment has the electric motor 5 that rotationally drives the drive wheels 16 of the vehicle 1 and the output characteristics of the electric motor 5 with a predetermined switching rotational speed Nt as a boundary. And a controller 15 (control means) that switches between a low-speed mode corresponding to an operation region closer to a low rotation and a high-speed mode compatible to an operation region closer to a higher rotation. And in this embodiment, as control with respect to the said electric motor 5, the step (S9) which measures the shock which generate | occur | produces in the vehicle 1 at the time of the switching of the said output characteristic as a switching shock, and the said measured switching shock are more than predetermined threshold value Is determined, the step (S15) of changing the target current value Ima in the increasing direction at the next switching of the output characteristics is executed. According to such a configuration, there is an advantage that the shock generated when the output characteristic of the electric motor 5 is switched can be reduced and the comfort of the passenger can be favorably maintained.

  That is, in the above embodiment, the switching shock is measured when the output characteristics of the electric motor 5 are switched, and the target current value Ima is changed in an increasing direction in which the switching shock is reduced when the value is equal to or greater than a predetermined threshold value. Therefore, there is an advantage that the switching shock can be suppressed to a smaller level, and the shock transmitted to the occupant at the time of switching the output characteristics can be reduced to maintain the occupant comfort satisfactorily.

  In particular, in the above embodiment, the switching shock measured after the target current value Ima is changed in the increasing direction is compared with the switching shock before the change (step S14), and the switching shock is reduced as a result of the comparison. Is confirmed (in the case of YES in S14), the change in the increasing direction of the target current value Ima is repeated until the switching shock falls below the threshold value. According to such a configuration, for example, by repeatedly changing the target current value Ima until the switching shock is reduced to a level at which the occupant does not feel discomfort, the occupant's comfort can be reliably improved. There is.

  Moreover, in the said embodiment, when it is confirmed as a result of the comparison by said step S14 that the switching shock became large by the change to the increase direction of the target electric current value Ima (in the case of NO at S14), By changing the target current value Ima back to the previous value, the target current value Ima is prohibited from changing in the increasing direction. According to such a configuration, even when the switching shock does not fall below a predetermined threshold, the switching shock can be suppressed to the minimum possible switching shock as much as possible, and the switching shock due to the target current value Ima being changed unnecessarily. There is an advantage that it is possible to effectively prevent the increase.

  In the above embodiment, if NO is determined in step S14, that is, changing the target current value Ima in the increasing direction, the switching shock increases, and the target current value Ima is further changed. However, if it is not possible to reduce the switching shock, the switching shock is reduced by changing, for example, the value of the switching rotational speed Nt shown in FIG. 4 as a control parameter other than the target current value Ima. May be.

  That is, since the switching shock generated in the vehicle 1 is considered to change depending on the value of the switching rotational speed Nt (position of the switching line P) serving as a threshold when the output characteristics of the electric motor 5 are switched, the target at the time of switching If the switching shock is not sufficiently reduced only by changing the current value Ima, the switching shock can be further reduced by appropriately changing the switching rotational speed Nt in addition to the change of the target current value Ima. It may be. Thereby, even when the change effect of the target current value Ima does not provide a sufficient effect of reducing the switching shock, there is an advantage that the switching shock can be surely kept below the threshold value and passenger comfort can be sufficiently secured.

  In addition, when it is determined that the switching shock is equal to or greater than the threshold value, it is conceivable that the switching rotational speed Nt is suddenly changed without changing the target current value Ima. However, since the value of the switching rotational speed Nt is determined in consideration of the efficiency of the electric motor 5, etc., suddenly changing the switching rotational speed Nt as described above is a significant change in the switching rotational speed Nt. This may lead to deterioration of motor efficiency and the like.

  For this reason, when the switching shock is equal to or greater than the threshold value, the target current value Ima is first changed while maintaining the switching rotational speed Nt at the original value, and only when the switching shock is not sufficiently reduced, It is preferable to change the switching rotational speed Nt. In other words, if at least the target current value Ima of the electric motor 5 is included in the control parameter that is changed when the switching shock is large, first, the efficiency of the electric motor 5 can be increased by changing the target current value Ima. It is possible to properly reduce the switching shock without damaging it.

  Moreover, although the said embodiment demonstrated the example which applied the control method of this invention with respect to the hybrid type vehicle which used the engine 2 and the electric motor 5 together as a motive power source, the control method of this invention is the electric motor 5. As long as the vehicle is an electric vehicle using at least a part of the power source, it is applicable regardless of the type.

1 Electric vehicle (vehicle)
5 Electric motor 15 Controller (control means)
15a Measuring means 15b Changing means 15c Comparison means 16 Driving wheel Nt Switching rotational speed Ima Target current value

Claims (5)

The output characteristics of the electric motor that drives the drive wheels of the vehicle can be handled from the low-speed mode that corresponds to the low-speed driving region and the driving region that is higher than this, at the predetermined switching rotational speed. An electric vehicle motor control method for switching between a high speed mode,
A measurement step of measuring a shock generated in the vehicle at the time of switching the output characteristic as a switching shock;
A step of changing the target current value of the electric motor in an increasing direction at the next switching of the output characteristics when it is determined that the measured switching shock is equal to or greater than a predetermined value. Motor control method. In the motor control method of the electric vehicle according to claim 1,
A comparison step of comparing the change shock before and after the change of the target current value by the change step,
As a result of the comparison in this comparison step, when it is confirmed that the switching shock has become smaller than the previous time due to the change in the target current value in the increasing direction, the change in the target current value in the increasing direction is performed. The motor control method for an electric vehicle is characterized by repeating until the switching shock falls below a predetermined value. In the motor control method of the electric vehicle according to claim 2,
As a result of the comparison in the comparison step, when it is confirmed that the switching shock has become larger than the previous time due to the change in the target current value in the increasing direction, the target current value in the increasing direction thereafter is increased. A motor control method for an electric vehicle characterized by prohibiting a change. In the motor control method of the electric vehicle according to claim 3,
As a result of the comparison in the comparison step, when it is confirmed that the switching shock has become larger than the previous time due to the change in the target current value in the increasing direction, the value of the switching rotational speed is changed. A motor control method for an electric vehicle, which is characterized. An electric motor that rotationally drives the driving wheels of the vehicle, and the output characteristics of this electric motor, with a predetermined switching rotational speed as a boundary, a low-speed mode corresponding to a low-speed driving region, and a driving closer to a higher speed than this A drive device for an electric vehicle comprising control means for switching between a high-speed mode capable of handling up to an area,
The control means is a measuring means for measuring a shock generated in the vehicle at the time of switching the output characteristics as a switching shock, and when the measured switching shock is determined to be a predetermined value or more, at the next switching of the output characteristics, An electric vehicle drive device comprising: a changing unit that changes a target current value of the electric motor in an increasing direction.

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