JP2010206923A - Method of controlling motor for electric vehicle, and drive device for electric vehicle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To maintain a sense of comfortability of each occupant by suppressing the generation of a torque variation due to switching of the output characteristics of an electric motor for rotating and driving the driving wheels of a vehicle. <P>SOLUTION: A control method is provided for switching the output characteristics of the electric motor 5 for rotating and driving the driving wheels 16 of a vehicle 1 between a low-speed mode and a high-speed mode when a rotation speed N of the electric motor 5 passes through a switching line P. The method includes step (S2) of measuring the frequency of usage of the rotation speed N of the electric motor 5, step (S12) of determining whether usage frequency corresponding to the switching line P is not less than a predetermined threshold Fa based on the data of measured usage frequency, and steps (S14, S15) of shifting the switching line P to a side of lower usage frequency when it is determined that the usage frequency is not less than the threshold Fa. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  According to the present invention, when the rotational speed of the electric motor that rotationally drives the drive wheels of the vehicle passes through the switching line on the characteristic diagram, the output characteristics of the electric motor are set to a low-speed mode corresponding to a driving region near low rotation. Further, the present invention relates to 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.

  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 some cases, the torque transmitted to the driving wheels of the vehicle may fluctuate temporarily due to intermittent changes in the output of the electric motor.

  If such torque fluctuations occur frequently, passenger comfort may be impaired. Therefore, it is desirable that the frequency of switching the output characteristics is not so high. However, if the rotational speed at which the output characteristics are switched is set to a rotational speed that is frequently used during operation, the output characteristics are frequently switched, and the frequency of occurrence of torque fluctuation as described above is reduced. There is a problem that it increases and passenger comfort is impaired.

  The present invention has been made in view of the circumstances as described above, and suppresses the occurrence of torque fluctuation due to switching of the output characteristics of the electric motor that rotationally drives the driving wheels of the vehicle, thereby improving passenger comfort. The purpose is to maintain.

  In order to solve the above-described problems, the present invention provides an output characteristic of the electric motor with a low rotation speed when the rotation speed of the electric motor that rotates the drive wheels of the vehicle passes through the switching line on the characteristic diagram. A motor control method for an electric vehicle that switches between a low-speed mode corresponding to a driving region closer to a high-speed mode capable of corresponding to a driving region closer to higher rotation, wherein the frequency of use of the rotational speed of the electric motor is A use frequency measurement step for measuring the use frequency, a determination step for determining whether or not the use frequency corresponding to the switching line is greater than or equal to a predetermined threshold based on the measured use frequency data, and the use frequency is greater than or equal to the threshold And a correction step for shifting the switching line to a side with a low usage frequency.

  According to the present invention, when the motor rotation speed corresponding to the output characteristic switching line is high, the switching line is shifted to the low usage frequency side. It is possible to effectively prevent frequent switching of the output characteristics, and it is possible to reduce the frequency of torque fluctuation caused by the switching of the output characteristics and maintain the passenger comfort satisfactorily.

  In the present invention, preferably, in the use frequency measuring step, the use frequency of the rotational speed is measured for each destination of the vehicle (claim 2).

  If it does in this way, based on the data of the use frequency classified for every destination of vehicles, the above-mentioned change line can be set in a proper position, and generation of torque fluctuation by change of output characteristics can be controlled more effectively. There is an advantage.

  For the same reason, it is preferable to adopt the following method.

  In the use frequency measurement step, the use frequency of the rotational speed is measured for each degree of traffic jam during vehicle travel (claim 3).

  Alternatively, the frequency of use of the rotational speed is measured for each driver identified by a predetermined recognition means.

  Alternatively, the use frequency of the rotational speed is measured for each driving mode of the vehicle selected by the driver (claim 5).

  When measuring the use frequency of the rotational speed for each travel mode of the vehicle, particularly when the sport mode is selected as the travel mode, shifting of the switching line by the correction step may be prohibited ( Claim 6).

  In this way, there is an advantage that it is possible to effectively prevent the driving characteristics of the vehicle focusing on the sportiness according to the driver's preference from being damaged by the shift of the switching line.

  The present invention also provides an electric motor that rotates the drive wheels of a vehicle, and the output characteristics of the electric motor when the rotational speed of the electric motor passes through the switching line on the characteristic diagram. An electric vehicle drive device comprising a control means for switching between a low-speed mode corresponding to a region and a high-speed mode capable of dealing with a driving region closer to a higher rotation speed, wherein the control means includes the electric Storage means for storing a measurement result relating to the use frequency of the rotation speed of the motor, and determination means for determining whether the use frequency corresponding to the switching line is equal to or greater than a predetermined threshold based on the stored use frequency data And a correction unit that shifts the switching line to a lower usage frequency side when the usage frequency is determined to be equal to or higher than a threshold value (Claim 7).

  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 maintain the passenger comfort satisfactorily by suppressing the occurrence of torque fluctuation due to the switching of the output characteristics of the electric motor that rotationally drives the drive wheels of the vehicle.

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 the use frequency of the rotational speed of the said electric motor superimposed on an output characteristic figure. It is a figure which shows the data of the usage frequency of the rotational speed memorize | stored in a memory | storage means in a tabular form. It is a figure for demonstrating the condition which shifts a switching line according to the data of the said usage frequency. It is a figure which shows another example which shifts the said switching line. It is a flowchart which shows the control action at the time of measuring and memorize | storing the usage frequency of the said rotational speed. It is a flowchart which shows the control action regarding the setting of the said switching line and switching of the output characteristic of an electric motor. It is a circuit diagram for demonstrating the modification of this invention. It is a figure which shows the output characteristic of the electric motor in the said modification.

  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 a traveling speed (vehicle speed) of the vehicle 1, an accelerator opening sensor 31 that detects an opening degree of an accelerator pedal (not shown) that is depressed by a driver, and an engine. The engine rotation speed sensor 32 that detects the rotation speed of the crankshaft 2, the generator rotation speed sensor 33 that detects the shaft rotation speed of the generator 3, and the input current input from the battery 9 to the generator 3 or the generator 3 generates power. Generator current sensor 34 for detecting the output current output to battery 9, motor rotational speed sensor 35 for detecting shaft rotational speed N of electric motor 5, and motor current sensor 36 for detecting input / output current of electric motor 5. And a battery sensor 37 for detecting the remaining capacity of the battery 9 are connected to each other. These various control information detected by the sensors 30 to 37 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 30-37, and the said engine 2, the generator 3, the electric motor 5, and inverter 11,12 grade | etc., Based on the result 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.

  The controller 15 is electrically connected to a navigation unit 40, a travel mode selection switch 41, and driver recognition means 42 (corresponding to recognition means according to the present invention).

  The navigation unit 40 specifies the position on the map data stored in advance based on the radio wave from the GPS satellite and the optimum route for the destination set by the occupant. Is used to perform various types of information processing such as displaying on a display outside the figure.

  The travel mode selection switch 41 controls the drive of the electric motor 5 with an emphasis on the normal mode in which the drive of the electric motor 5 is prioritized for efficiency and the acceleration feeling obtained when the driver depresses the accelerator pedal. This is for switching the traveling mode of the host vehicle between the sports mode. The travel mode selection switch 41 is a button type switch that is turned on / off by a driver, for example, and an operation signal transmitted from the switch 41 in response to such an on / off operation is input to the controller 15. Thus, the traveling mode of the host vehicle can be switched between the normal mode and the sports mode.

  The driver recognition means 42 is for identifying a driver seated on a driver seat (not shown), and is constituted by, for example, a camera capable of imaging the driver's face. When the driver recognizing means 42 is constituted by the camera as described above, the controller 15 stores image data of the face of the driver who has driven the host vehicle in the past, and the stored image data By comparing the image data of the face appropriately captured by the image recognition means 42 at the start of traveling, the driver currently sitting on the driver's seat is identified.

  The navigation unit 40, the travel mode selection switch 41, and the driver recognition means 42 are provided, for example, on an instrument panel in the passenger compartment.

  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. For example, as indicated by an arrow D1 in the figure, the rotation speed N is lower than the switching line P when the electric motor 5 is driven in the low speed mode because the rotation speed N is lower than the switching line P. In the case of increasing to the high rotation side region, the output characteristics of the electric motor 5 are switched from the low speed mode to the 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.

  Here, the switching line P, which is a boundary line between the low speed mode and the high speed mode, is variably set by the controller 15 as shown in FIG. Specifically, the controller 15 measures the usage frequency of the motor rotation speed N shown by the diagram F in the figure while the vehicle 1 is traveling, and sets the switching line P to a predetermined value based on the distribution of the usage frequency. It is configured to variably set within the range of the rotation speed (within the range R in the figure). Hereinafter, the range R in which the switching line P can be changed is referred to as a shiftable range R.

  Returning to FIG. 2 again, the function of the controller 15 relating to the setting of the switching line P will be described in detail. As shown in the figure, the controller 15 includes a storage unit 15a, a determination unit 15b, and a correction unit 15c as functional elements.

  The said storage means 15a memorize | stores the measurement result regarding the usage frequency of the motor rotational speed N. FIG. FIG. 6 is a diagram showing, in a tabular form, data on the frequency of use of the motor rotational speed N stored in the storage means 15a. Aa1, Ab1,... In the figure are stored for each of various traveling conditions. It shows the data of the usage frequency. Each of these usage frequency data (Aa1, Ab1,...) Is data that defines the relationship between the motor rotation speed N and the usage frequency (the diagram F shown in FIG. 5), and more specifically. This is data obtained by collecting values of usage frequencies measured for each numerical section obtained by dividing the numerical axis of the motor rotation speed N (the horizontal axis in FIG. 5) into a number of regions. The frequency of use of each numerical section can be obtained, for example, by continuously monitoring the motor rotation speed N and calculating the relative time occupancy of each numerical section based on the monitoring data.

  The determination unit 15b determines whether the use frequency corresponding to the switching line P is equal to or greater than a predetermined threshold based on the use frequency data stored in the storage unit 15a. Specifically, as shown in FIG. 7, the rotation speed at a specific point on the switching line P is set as the representative switching rotation speed Ntr, and the representative switching rotation speed Ntr in the distribution graph F of the usage frequency is set. It is determined whether or not the value of the use frequency of the point Q corresponding to is greater than or equal to a preset threshold value Fa (two-dot chain line in the figure).

  The correction unit 15c shifts the switching line P to a side with a lower usage frequency when the determination unit 15b determines that the usage frequency corresponding to the representative switching rotation speed Ntr is equal to or greater than the threshold value Fa. It is. For example, in the example of FIG. 7, the usage frequency corresponding to the representative switching rotational speed Ntr (the value of the usage frequency of the point Q) is equal to or greater than the threshold value Fa, and thus the switching line P needs to be shifted from the current position. According to the usage frequency distribution diagram F in the figure, since the usage frequency is lower on the high rotation side than the representative switching rotation speed Ntr, the switching line P is shifted to the higher rotation side than the current position. The As a result, the first switching line P is changed to a new switching line P ′, and thereafter, the output characteristics of the electric motor 5 are switched based on the switching line P ′. However, the shift of the switching line P (change to the switching line P ′) is performed only within the shiftable range R described above.

  On the other hand, as shown in FIG. 8, when the frequency of use is lower on the low rotation side than the representative switching rotation speed Ntr, the switching line P is shifted to the low rotation side within the shiftable range R, and a new switching is performed. It will be changed to line P ′. In the following description, the switching line P initially set in FIGS. 7 and 8 (that is, the switching line P before the shift) may be particularly referred to as a “basic switching line P”.

  Next, the use frequency data of the motor rotation speed N stored in the storage unit 15a will be described in more detail. As shown in FIG. 6, the use frequency data (Aa1, Ab1...) Of the motor rotation speed N is measured for each travel condition such as destination, driver, travel mode, and the degree of traffic congestion, and is classified according to each condition. It is stored in the storage means 15a.

  FIG. 9 is a flowchart showing a control operation when the controller 15 measures the data of the usage frequency and stores it in the storage means 15a. When the flowchart of this figure starts, the controller 15 first executes control to read the currently set destination of the own vehicle, the driver seated on the driver's seat, the set travel mode, and the degree of traffic jam. (Step S1).

  Specifically, among the travel conditions read in step S1, the travel route can be specified by reading the destination set by the occupant using the navigation unit 40 from the navigation unit 40. It can be specified by reading the recognition result by the driver recognition means 43. The driving mode (normal mode or sports mode) can be specified based on the input signal from the driving mode selection switch 41, and the navigation unit 40 receives the degree of traffic jam (large, medium, or none). It can be specified based on traffic information such as VICS, the average speed of the host vehicle, and the like. If no operation for setting the destination is performed on the navigation unit 40, the destination is read as “none”.

  Next, the controller 15 executes control for measuring the use frequency of the motor rotation speed N based on the detection value of the motor rotation speed sensor 35 (step S3). Specifically, the detection value of the motor rotation speed sensor 35 is continuously read to monitor the motor rotation speed N over a predetermined period, and based on the relative time occupancy of each speed specified from the obtained monitoring data. Thus, the use frequency of the motor rotation speed N is obtained.

  When the usage frequency of the motor rotational speed N is measured in this way, the controller 15 executes control for storing the data on the usage frequency in the storage unit 15a in association with the travel condition read in step S1. (Step S3). That is, it is specified which condition column in the table data of FIG. 6 corresponds to the travel condition read in step S1, and the use frequency data is stored in the storage unit 15a in a state associated with the condition. At this time, if data on the frequency of use under the same conditions exists in the past, the new measurement data acquired in step S2 is added to the past data to sequentially accumulate the data. However, when the destination is “none” among the above driving conditions, the old data is sequentially deleted in order to use the data of the usage frequency as the data at the latest driving.

  Next, the control operation relating to the setting of the switching line P and the switching of the output characteristics of the electric motor 5 will be described with reference to the flowchart of FIG. When the flowchart of FIG. 10 starts, first, the controller 15 first sets the destination of the host vehicle, the driver seated on the driver's seat, and the set travel as in step S1 of FIG. Control for reading the mode and the degree of traffic jam is executed (step S10).

  Next, the controller 15 stores in the storage means 15a data on the frequency of use suitable for each driving condition (destination, driver, driving mode, degree of traffic jam) read in step S10 shown in FIG. Control to select and read from the data is executed (step S11).

  Next, the controller 15 is set on the usage frequency corresponding to the basic switching line P shown in FIGS. 7 and 8, that is, on the basic switching line P, based on the usage frequency data read in step S11. Control is performed to determine whether or not the value of the use frequency of the point Q corresponding to the representative switching rotational speed Ntr is equal to or greater than the threshold value Fa (step S12).

  When it is determined YES in step S12, that is, when it is confirmed that the use frequency corresponding to the basic switching line P is equal to or greater than the threshold value Fa, the controller 15 uses the use frequency within the shiftable range R. Control is performed to determine whether or not there is a rotational speed range that is lower than the threshold value Fa (step S13). For example, in the example of FIG. 7, the rotation speed range where the use frequency is smaller than the threshold value Fa exists in a part of the shiftable range R on the high rotation side. On the other hand, in the case of FIG. 8, a part of the shiftable range R on the low rotation side has a rotation speed region in which the use frequency is smaller than the threshold value Fa. For this reason, in any of these cases of FIG. 7 and FIG. 8, it is determined YES in step S13.

  If it is determined as YES in step S13 and it is confirmed that there is a rotation speed range in which the usage frequency is lower than the threshold value Fa, the controller 15 selects the basic switching among the switching line candidates corresponding to the rotation speed range. Control for setting a line closest to the line P as a new switching line P ′ is executed (step S14). On the other hand, when it is determined NO in step S13, control is performed to set a line that is least frequently used in the shiftable range R as a new switching line P '(step S15).

  If it is determined NO in step S12, that is, if it is confirmed that the usage frequency corresponding to the basic switching line P is lower than the threshold value Fa, the switching line is not shifted as described above. The switching line is maintained at the original position (basic switching line P).

  When the processing relating to the setting of the switching line is completed as described above, the controller 15 executes control for reading the rotational speed N of the electric motor 5 from the motor rotational speed sensor 35 (step S16).

  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 S1). S17). 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.

  If it is determined YES in step S17 and it is confirmed that the low speed mode is set, the controller 15 determines that the motor rotation speed N read in step S16 is higher than the switching line (P or P ′). Control for determining whether or not the engine is on the high rotation side is executed (step S18). Note that the switching line here refers to a new switching line P ′ after the shift when the switching line is shifted in steps S14 and S15, and the shift control as described above is performed. If not performed (NO in step S12), it indicates the basic switching line P.

  When it is determined YES in step S18 and it is confirmed that the motor rotation speed N is higher than the switching line (P or P ′), the controller 15 switches the switching element Sw of the second inverter 12 on. The output characteristic of the electric motor 5 is changed 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 of the first and second windings L1, L2 of the electric motor 5. Control to switch to is executed (step S19). On the other hand, when it is determined NO in step S18, the process returns without performing the switching operation as described above, and the output characteristics of the electric motor 5 are maintained in the low speed mode.

  Next, a description will be given of the control operation when it is determined NO in step S17, that is, when it is confirmed that the current output characteristics of the electric motor 5 are set to the high speed mode. In this case, the controller 15 determines whether or not the motor rotation speed N read in step S16 is on the lower rotation side than the switching line (P or P ′) (step S20). When it is determined that it is on the low rotation side, the switching element Sw is operated to switch the current path so that current flows through both the first and second windings L1 and L2. Control for switching the output characteristics of the motor 5 from the high speed mode to the low speed mode is executed (step S21). On the other hand, if it is determined NO in step S20, the process returns without performing the switching operation as described above, and the output characteristics of the electric motor 5 are maintained in the high speed mode.

  9 and 10 described above, step S2 is the use frequency measuring step according to the present invention, step S12 is the determining step according to the present invention, and steps S14 and S15 are the correcting steps according to the present invention. Equivalent to.

  As described above, in the electric vehicle drive device of the present embodiment, the electric motor 5 that rotationally drives the drive wheels 16 of the vehicle 1 and the rotational speed N of the electric motor 5 are determined in advance in the characteristic diagram of FIG. When passing through the set switching line P, the output characteristics of the electric motor 5 are a low speed mode corresponding to an operation region near low rotation, and a high speed mode capable of corresponding to an operation region near high rotation. And a controller 15 (control means) for switching between them. In the present embodiment, as the control operation for the electric motor 5, the step (S2) of measuring the use frequency of the rotational speed N of the electric motor 5 and the switching based on the measured use frequency data. A step (S12) of determining whether or not the usage frequency corresponding to the line P (the usage frequency of the point Q shown in FIGS. 7 and 8) is equal to or higher than a predetermined threshold Fa, and the usage frequency is determined to be higher than or equal to the threshold Fa. In this case, the controller 15 executes the steps (S14, S15) for shifting the switching line P to the less frequently used side. According to such a configuration, there is an advantage that the comfort of the occupant can be favorably maintained by suppressing the occurrence of torque fluctuation due to the switching of the output characteristics of the electric motor 5.

  That is, in the above embodiment, when the use frequency of the rotation speed N corresponding to the switching line P where the output characteristic of the electric motor 5 is switched is high, the switching line P is shifted to the low use frequency side. It is possible to effectively prevent frequent switching of the output characteristics across the line P, and to reduce the frequency of torque fluctuations caused by the switching of the output characteristics and to maintain good passenger comfort.

  In particular, in the above embodiment, the use frequency of the motor rotation speed N is measured and stored in the storage unit 15a for each driving condition such as the destination of the vehicle 1, the driver, the driving mode, and the degree of traffic jam. The switching line P can be set to an appropriate position on the basis of the usage frequency data classified into (2), and there is an advantage that occurrence of torque fluctuation due to switching of output characteristics can be more effectively suppressed.

  That is, if the driving conditions such as the destination, driver, driving mode, and the degree of traffic congestion are the same, it is expected that the same tendency will be seen in the value of the motor rotation speed N used. By using the data of the usage frequency of the rotational speed N classified for each condition, the magnitude of the usage frequency of the rotational speed N corresponding to the switching line P can be appropriately determined, and the switching line P can be used as necessary. Can be more effectively suppressed from occurring due to switching of output characteristics.

  In the above-described embodiment, when it is determined that the use frequency of the rotation speed N corresponding to the switching line P is equal to or greater than the threshold value Fa (that is, NO in step S12), the rotation frequency range where the use frequency is lower than the threshold value Fa. Is present in the shiftable range R (step S13), and if it exists, the switching line P is located at a position closest to the original line (basic switching line P) in the rotational speed range. Is shifted (step S14), and if it does not exist, the switching line P is shifted to a position where the frequency of use is lowest in the shiftable range R (step S15). Various other methods of shifting can be considered.

  For example, the switching line P may be shifted to a position where the frequency of use is lowest in the shiftable range R regardless of whether or not there is a rotation speed range where the frequency of use is lower than the threshold value Fa. In this way, the control flow can be simplified, and there is an advantage that when the switching line P is shifted, the switching line P can always be set at a position where the frequency of use is as low as possible.

  On the other hand, when the switching line P is shifted to a position closest to the original line as in the above-described embodiment, the shift width of the switching line P stays at a necessary minimum. Effectively preventing the efficiency of the electric motor 5 from deteriorating due to a relatively large deviation from the original position, etc., while reducing the frequency of torque fluctuations to the required level and improving passenger comfort There is an advantage that it can be maintained.

  In the above embodiment, the use frequency of the motor rotational speed N is measured by the travel mode selection switch 41, regardless of whether the normal mode or the sport mode is selected as the travel mode of the vehicle 1, and based on the data. The switching line P is shifted as necessary. However, when the sports mode is selected from the two travel modes, the switching line P is fixed at a fixed position and the switching line as described above is used. P shift may be prohibited.

  That is, in the situation where the sport mode is selected as the travel mode, the driver prefers that a sharp acceleration feeling is obtained and the like, and the torque fluctuation of the electric motor 5 due to the switching of the output characteristics occurs. Is not particularly concerned. Therefore, in such a situation, by prohibiting the shift of the switching line P, it is possible to effectively prevent the driving characteristics of the vehicle 1 that emphasizes the sportiness according to the driver's preference from being damaged by the shift of the switching line P. There are advantages.

  In the above embodiment, the output characteristic of the electric motor 5 is changed by switching the current path so that the current flows through all or part of the plurality of windings L1, L2. Instead, the output characteristic of the electric motor 5 is switched between the low speed mode and the high speed mode by changing the voltage Vdc on the inverter 12 side according to the operation of the boost converter 50 as shown in FIG. May be.

  That is, boost converter 50 shown in FIG. 11 has first and second switching elements Sw1 and Sw2. When electric motor 5 is in the low speed mode, both switching elements Sw1 and Sw2 are By being in the OFF state, the output characteristic of the electric motor 5 is set to a characteristic close to low rotation as indicated by a characteristic line A1 ′ in FIG. On the other hand, when the electric motor 5 shifts from the low speed mode to the high speed mode, the first switching element Sw1 is turned off and the second switching element Sw2 is subjected to switching control (ON / OFF is repeated). The voltage Vdc on the inverter 12 side is increased (boosted), and the output characteristic of the electric motor 5 changes to a characteristic close to high rotation as indicated by a characteristic line A2 ′ in FIG. At this time, depending on the switching control of the second switching element Sw2, the voltage Vdc at the time of boosting can be controlled in multiple stages, so that the output of the electric motor 5 can be freely increased in an appropriate width according to the driving state of the vehicle 1 and the like. It is possible to make it. When the electric motor 5 is in the high speed mode, for example, when the vehicle 1 is in a decelerating state and the electric motor 5 obtains a driving force from the drive shaft 8 to generate electric power (that is, when regenerative braking is performed). On the contrary, the first switching element Sw1 is subjected to switching control, and the second switching element Sw2 is turned off.

  A line Pa in FIG. 12 is a switching line in which the output characteristic of the electric motor 5 is switched from the low speed mode to the high speed mode. When the rotational speed N of the electric motor 5 passes through the line Pa, the second line of the boost converter 50 is shown. The switching element Sw2 is subjected to switching control so that the output characteristics of the electric motor 5 are switched between the low speed mode and the high speed mode. In such a configuration, as in the above embodiment, the use frequency of the rotation speed N corresponding to the switching line Pa (for example, the rotation speed corresponding to one representative point on the switching line Pa) is set as a predetermined threshold value. In comparison, if the switching line Pa is shifted to a less frequently used side when it is equal to or higher than the threshold value, the switching of the output characteristics from the switching line Pa is prevented, and passenger comfort is improved. There is an advantage that it can be maintained well.

  In FIG. 12, as can be seen by comparing the characteristic line A1 ′ corresponding to the low speed mode and the characteristic line A2 ′ corresponding to the high speed mode, the above configuration using the boost converter 50 is the case of the above-described embodiment ( Unlike FIG. 4), there is no difference between the maximum torque in the low speed mode and the maximum torque in the high speed mode. For this reason, even if the electric motor 5 is always driven in the high speed mode by always maintaining the boost converter 50 in the boosted state (a state in which the switching element Sw2 is switching-controlled), there is no particular problem in driving the vehicle 1. . However, when the boost converter 50 is in the boosted state, it is inevitable that some switching loss occurs due to the switching operation of the switching element Sw2 (operation that repeats ON / OFF), so the electric motor 5 is always in the high-speed mode. If it is driven, the energy loss due to the switching loss is increased, and the energy efficiency is deteriorated. Therefore, in order to prevent such deterioration of energy efficiency, the electric motor 5 is normally driven in the low speed mode, and the output characteristics of the electric motor 5 are switched to the high speed mode only when necessary (for example, during acceleration). This control is necessary.

  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 Storage means 15b Determination means 15c Correction means 16 Drive wheel 42 Driver recognition means (recognition means)
N Rotational speed P Switching line Fa Threshold

Claims (7)

When the rotational speed of the electric motor that drives the drive wheels of the vehicle passes through the switching line on the characteristic diagram, the output characteristics of the electric motor are set to the low speed mode corresponding to the driving region close to the low rotation, and A motor control method for an electric vehicle that switches between a high-speed mode that can support a driving region close to high rotation,
A use frequency measuring step for measuring the use frequency of the rotational speed of the electric motor;
A determination step of determining whether the use frequency corresponding to the switching line is equal to or greater than a predetermined threshold based on the measured use frequency data;
And a correction step of shifting the switching line to a lower frequency side of use when it is determined that the usage frequency is equal to or higher than a threshold value. In the motor control method of the electric vehicle according to claim 1,
In the use frequency measuring step, the use frequency of the rotational speed is measured for each destination of the vehicle. In the motor control method of the electric vehicle according to claim 1 or 2,
A motor control method for an electric vehicle characterized in that, in the use frequency measurement step, the use frequency of the rotational speed is measured for each degree of traffic jam during vehicle travel. In the motor control method of the electric vehicle according to any one of claims 1 to 3,
In the use frequency measuring step, the use frequency of the rotational speed is measured for each driver identified by a predetermined recognition means. In the motor control method of the electric vehicle according to any one of claims 1 to 4,
In the use frequency measuring step, the use frequency of the rotational speed is measured for each travel mode of the vehicle selected by the driver. In the motor control method of the electric vehicle according to claim 5,
A motor control method for an electric vehicle, wherein, when a sports mode is selected as the travel mode, shifting of a switching line by the correction step is prohibited. An electric motor that rotationally drives the drive wheels of the vehicle, and a low-speed mode that corresponds to the operating region near the low rotation speed when the rotational speed of the electric motor passes through the switching line on the characteristic diagram. And a drive means for an electric vehicle comprising a control means for switching between a high-speed mode capable of handling a driving region closer to a higher rotation than this,
The control means includes
Storage means for storing measurement results regarding the frequency of use of the rotational speed of the electric motor;
Determination means for determining whether the use frequency corresponding to the switching line is equal to or greater than a predetermined threshold based on the stored use frequency data;
An electric vehicle drive device comprising: a correction unit that shifts the switching line to a side with a low usage frequency when the usage frequency is determined to be equal to or greater than a threshold value.

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