JP2010206927A - Motor control method for electric vehicle and drive device for the electric vehicle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To maintain the 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: This control method for switching the output characteristics of the electric motor 5 between a low-speed mode and a high-speed mode includes a voltage detecting step (S5) for detecting a voltage value Vb of a power supply unit (9) for supplying power to the electric motor 5, a line setting step (S6) for setting a switching line P used as a reference in switching the output characteristics based on the voltage value Vb detected in the step (S5), a predicting step (S8) for predicting that the voltage value Vb of the power supply unit (9) decreases, and a shift step (S10) for shifting the switching line P set in the line setting step to a low rotation side based on the degree of estimated decrease prior to the actual decrease of the voltage value when the decrease in the voltage value Vb is predicted in the step (S8). <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an output characteristic of an electric motor that rotationally drives a drive wheel of a vehicle, a low-speed mode corresponding to a low-speed driving region with a switching line on a control map as a boundary, and driving higher than this. The present invention relates to a motor control method for an electric vehicle that is switched between a high-speed mode that can handle a region.

  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 Patent Document 1 below, when a condition such as the rotational speed of the electric motor exceeding a predetermined threshold (switching rotational speed) is established, the connection state of the winding of the electric motor is switched or the field control method is switched. As a result, the output characteristic of the electric motor is changed to a characteristic that can cope with a region closer to a higher rotation.

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 driving wheels of the vehicle temporarily fluctuates due to intermittent changes in the output of the electric motor. At this time, if the width of the torque fluctuation is too large, a large shock is generated in the vehicle and passenger comfort is impaired. Therefore, it is possible to reduce the torque fluctuation and reduce the shock generated in the vehicle as much as possible. desired.

  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-mentioned problems, the present invention relates to the output characteristics of the electric motor that rotationally drives the driving wheels of the vehicle, and the low-speed mode corresponding to the low-rotation driving region with the switching line on the control map as a boundary. And a motor control method for an electric vehicle that switches between a high-speed mode that can handle an operation region closer to a higher rotation speed than this, and a voltage detection that detects a voltage value of a power supply device that supplies electric power to the electric motor A step, a line setting step for setting the switching line based on the voltage value detected in this step, a prediction step for predicting that the voltage value of the power supply device decreases, and the voltage value decreases in this step If it is predicted that the switching line set in the line setting step is lowered based on the predicted decrease degree prior to the actual decrease in the voltage value. It is characterized in that comprises a shift step of shifting to the rotation side (claim 1).

  According to the present invention, the switching line on the control map serving as a reference when switching the output characteristics of the electric motor is shifted to the low rotation side based on the predicted degree of decrease prior to the decrease in the voltage value of the power supply device. Therefore, unlike when the switching line is reset according to the actual decrease in the power supply voltage, for example, the output characteristics of the electric motor can be prevented from switching from the low speed mode to the high speed mode at an unintended timing. There is an advantage that the comfort generated by the passenger can be maintained well by reducing the shock generated in the vehicle.

  In the present invention, preferably, in the shift step, the shift amount of the switching line is corrected to the lower rotation side as the load becomes higher (Claim 2).

  In this way, when a large load is applied to the electric motor and the voltage value of the power supply device drops, the motor current surge phenomenon can be achieved by relatively speeding up the switching timing to the high speed mode in the high load range. (Phenomenon in which a temporary high current flows through the electric motor) can be suppressed, and there is an advantage that loss / damage of the motor due to the surge phenomenon can be effectively prevented.

  In the present invention, preferably, even when a decrease in the voltage value is predicted by the prediction step, when the operating state of the electric motor is higher than the planned shift position of the switching line at the shift step. The shifting of the switching line by the shift step is prohibited (claim 3).

  In this way, it is possible to avoid switching the output characteristics to the high speed mode on the higher rotation side than the switching line after the shift, and to effectively prevent a large shock from being generated in the vehicle at that time. .

  In addition, the present invention provides an electric motor that rotationally drives the driving wheels of a vehicle, and the output characteristics of the electric motor, and a low-speed mode corresponding to a low-speed driving region with a switching line on the control map as a boundary. Drive for an electric vehicle comprising control means for switching between a high-speed mode capable of dealing with an operation region closer to a higher rotation speed, and voltage detection means for detecting a voltage value of a power supply device that supplies electric power to the electric motor A control unit, a line setting unit that sets the switching line based on a voltage value detected by the voltage detection unit, and a prediction unit that predicts that the voltage value of the power supply device is decreased. When it is predicted that the voltage value is lowered by the predicting unit, the switching line set by the line setting unit is set to the predicted degree of decrease before the actual decrease of the voltage value. Is characterized in that it has a shifting means for shifting to a low rotation side based on have (claim 4).

  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, there is an advantage that it is possible to reduce the shock that occurs when the output characteristics of the electric motor that rotationally drives the driving wheels of the vehicle are switched and to maintain the passenger comfort satisfactorily.

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 which shows the output characteristic of the said electric motor. It is a figure which shows the control map for the said electric motor set corresponding to the said output characteristic changing with battery voltages. It is a flowchart which shows the content of the control action performed with respect to the said electric motor. It is a figure for demonstrating a mode that a switching line is shifted to the low rotation side, before a battery voltage falls. It is a figure for demonstrating that a big switching shock may generate | occur | produce if the shift of the said switching line is not performed before a battery voltage falls.

  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 for generating electric power, an electric motor 5 provided as a driving power source, and a battery 9 (corresponding to the power supply device according to the present invention) for storing the electric power generated by the generator 3 and supplying the electric power to a necessary location. The first inverter 11 and the 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 the controller 15 that comprehensively controls these components (according to the present invention). Equivalent to control means).

  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 rotational speed sensor 32 that detects the rotational speed of the crankshaft of the engine 2, a generator rotational speed sensor 33 that detects the rotational speed of the generator 3, and an input current input from the battery 9 to the generator 3 or a battery from the generator 3 Generator current sensor 34 for detecting the output current output to 9, motor rotation speed sensor 35 for detecting the shaft rotation speed N of the electric motor 5, and motor current sensor 36 for detecting the input / output current of the electric motor 5. , A battery sensor 37 for detecting a voltage Vb between terminals of the battery 9 (electrical power according to the present invention). Detecting means corresponds) and are respectively connected, 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.

  A navigation unit 40 is electrically connected to the controller 15. 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 optimal 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.

  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, 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-carrying state is switched between the state in which 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. Specifically, the controller 15 variably changes the switching line P within a predetermined rotational speed range based on the value of the inter-terminal voltage Vb of the battery 9 detected by the battery sensor 37 while the vehicle 1 is traveling. It is configured to set (details will be described later).

  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 line setting means 15a, prediction means 15b, shift means 15c, and storage means 15d as functional elements.

  The line setting means 15a sets the switching line P at a predetermined position according to the voltage Vb between the terminals of the battery 9.

  The predicting means 15b predicts that the inter-terminal voltage Vb of the battery 9 decreases based on the planned travel route of the vehicle 1 specified from the navigation unit 40. That is, when a route that causes a large load on the electric motor 5 is included in the planned travel route nearest to the vehicle 1, it is predicted that the remaining capacity of the battery 9 decreases as the load increases. Therefore, it is predicted that the inter-terminal voltage Vb will decrease at such times.

  The shift means 15c is a switching line set by the line setting means prior to the actual decrease of the voltage value Vb when the predictor 15b predicts that the voltage Vb between the terminals of the battery 9 will decrease. P is shifted to the low rotation side based on the predicted decrease degree.

  The storage unit 15d stores a control map that is referred to when the line setting unit 15a sets the switching line P.

  FIG. 5 is a diagram for explaining a control map stored in the storage unit 15b. The control map M shown in the figure is composed of a bundle of a plurality of maps M1, M2,... Set according to conditions. Specifically, a plurality of maps M1, M2,... With different rotation speed ranges are prepared according to the voltage Vb between the terminals of the battery 9 detected by the battery sensor 37, and a bundle of these maps is the control map. M is stored in the storage means 15e.

  That is, when the remaining capacity of the battery 37 that supplies power to the electric motor 5 is reduced, and the inter-terminal voltage (battery voltage) Vb is reduced, the upper limit rotational speed of the electric motor 5 is reduced accordingly. The output characteristic 5 is reduced in the direction of the horizontal axis as shown in the figure. Therefore, a plurality of maps M1, M2,... Set corresponding to the value of the battery voltage Vb are prepared, and an appropriate map among them is appropriately selected based on the detection value of the battery sensor 37. ing. Note that a map M1 in FIG. 5 is a map when the battery voltage Vb is near the maximum value (voltage at full charge) so that the rotation speed range of the electric motor 5 can be secured most widely. Indicates the nth narrowest map from the map M1. As can be seen by comparing the map M1 and the map Mn, the position of the switching line P is also moved in the direction of the horizontal axis in accordance with the change in the rotation speed region due to the switching of the maps.

  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 inputs “0” as the default value to the line shift flag F indicating whether or not the control for shifting the switching line P has been executed based on the decrease prediction of the battery voltage Vb. The control which performs is performed (step S1). If the line shift flag F is “0”, the switching line P is not yet shifted, and if it is “1”, it is already shifted.

  Next, the controller 15 executes control for reading the rotational speed N of the electric motor 5 and the opening degree TVO of the accelerator pedal from the accelerator opening sensor 31 and the motor rotational speed sensor 35 (step S2), and is read here. Based on the accelerator opening TVO and the like, control for calculating the current required torque of the electric motor 5 is executed (step S3).

  Next, the controller 15 determines whether or not the line shift flag F = 1 (step S4). If it is determined NO and it is confirmed that the flag F = 0, that is, When it is confirmed that the switching line P has not yet been shifted, the control for reading the inter-terminal voltage (battery voltage) Vb of the battery 9 from the battery sensor 37 is executed (step S5).

  Next, the controller 15 executes control for setting the switching line P at a predetermined position corresponding to the battery voltage Vb (step S6). That is, the controller 15 selects an appropriate map corresponding to the battery voltage Vb read in step S5 from among a plurality of control maps M1, M2... (See FIG. 5) stored in the storage means 15c. Thus, the switching line P is set at a predetermined position corresponding to the battery voltage Vb. At this time, as described above, the higher the battery voltage Vb, the wider the rotation speed range of the electric motor 5 is secured. Therefore, the higher the battery voltage Vb, the higher the battery voltage Vb. The lower the voltage, the lower the rotation speed is set.

  When the setting of the switching line P is completed in this way, the controller 15 executes control for determining whether or not the output characteristic of the electric motor 5 is set to the low speed mode (step S7). 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 as YES in step S7 and it is confirmed that the low speed mode is set, the controller 15 executes control for predicting whether or not the battery voltage Vb will soon decrease (step S8). Specifically, the planned travel route of the vehicle 1 is read from the navigation unit 40, and based on the read planned route, it is predicted whether or not the load on the electric motor 5 will increase greatly in the near future. If the battery voltage Vb is predicted to increase, the battery voltage Vb is predicted to decrease. For example, on a relatively long uphill road or an entrance of an expressway that requires long-term acceleration, a considerably large load is applied to the electric motor 5 and the power consumption increases rapidly (that is, the remaining capacity of the battery 9 decreases). Therefore, it is predicted that the battery voltage Vb will suddenly decrease accordingly. Therefore, when it is predicted that the vehicle 1 will pass through the route as described above, the battery voltage Vb is predicted to decrease.

  When a decrease in the battery voltage Vb is predicted in step S8, the controller 15 determines the current operating state of the electric motor 5, that is, based on the motor rotation speed N and the required torque acquired in steps S2 and S3. It is determined whether or not the specified operating state is on the low rotation side with respect to the planned shift position of the switching line P that is shifted based on the predicted decrease in the battery voltage Vb (step S9). That is, in step S10 described later, control for shifting the switching line P to the low rotation side is executed based on the degree of decrease in the battery voltage Vb predicted in step S8 (see FIG. 7). In step S9, the position after the switching line P is shifted (the position indicated by the solid line in FIG. 7) is assumed, and it is determined whether or not the current driving state is on the lower rotation side than that position.

  When it is determined as YES in step S9 and it is confirmed that the speed is lower than the planned shift position, the controller 15 indicates the switching line P set in step S6 as indicated by an arrow X in FIG. Then, a control for shifting to a low rotation side by a predetermined amount is executed (step S10). The shift amount here is determined based on the degree of decrease in the battery voltage Vb predicted in step S8. That is, if the predicted decrease amount and decrease rate of the battery voltage Vb are large, the shift amount of the switching line P is also increased. If the predicted decrease amount and decrease rate of the battery voltage Vb is small, the switching line P The shift amount is also reduced. Thereby, before the battery voltage Vb actually decreases, the switching line P is shifted in advance to an appropriate position corresponding to the voltage value after the decrease.

  Thus, the switching line P is shifted prior to the actual decrease in the battery voltage Vb because the shock generated in the vehicle 1 when the output characteristic of the electric motor 5 is switched from the low speed mode to the high speed mode (switching shock). This is to reduce the above.

  That is, when the preceding shift of the switching line P as in step S10 is not performed, the switching line P is not shifted until the vehicle 1 actually starts traveling on a route where a considerable load is applied to the electric motor 5. When the battery voltage Vb is actually lowered due to such high load traveling, it is shifted to the low rotation side for the first time. Specifically, when the battery 1 drops on the vehicle 1 traveling on an uphill road or suddenly accelerating, the reduced voltage value is read in step S5, so that in the next step S6. The switching line P is reset to the low rotation side. At this time, for example, in the case where the battery voltage Vb decreases relatively suddenly, there is a certain difference between the previous read value and the current read value of the battery voltage Vb. Thus, it is considered that the position of the switching line P after resetting (the position of the solid line) is largely shifted to the low rotation side as compared with the position before resetting (the position of the broken line).

  When the switching line P after the resetting is greatly shifted to the low rotation side in this way, the output characteristics of the electric motor 5 are switched at a position different from the switching line P after the resetting, and the switching shock generated at that time is normally May increase. For example, when the position of the switching line P is moved from the broken line to the solid line with the resetting of the switching line P, the operation state of the electric motor 5 is the position indicated by the point Q in FIG. 8 (the position before the resetting and the position after the resetting). When the switching line P is reset, the point Q as the operation state of the electric motor 5 is suddenly positioned on the higher rotation side than the switching line P. Become. Then, where the output characteristic should be switched on the switching line P, the output characteristic is switched to the high speed mode at a position shifted to the higher rotation side than the switching line P, and the switching shock at that time increases. There is a fear.

  Therefore, in the present embodiment, when the battery voltage Vb is predicted to decrease, the switching line P is shifted to the low rotation side based on the predicted decrease degree prior to the actual decrease in the voltage value. (Step S10). In this way, by shifting the switching line P in advance to the low rotation side while the operating state of the electric motor 5 is in the low rotation region (lower rotation side than the shifted switching line P), When the battery voltage Vb actually decreases due to subsequent climbing or sudden acceleration, it is possible to avoid a situation in which the position of the switching line P is suddenly changed and the output characteristics are unexpectedly switched. An increase in switching shock due to switching can be prevented.

  Here, as shown in FIG. 7, the switching line P that is shifted to the low rotation side in step S <b> 10 is largely shifted to the low rotation side as the load is high (the positive side of the vertical axis). That is, when the switching line P is shifted so as to be substantially parallel to the original switching line P (line indicated by a broken line in FIG. 7) set in accordance with the current value of the battery voltage Vb. If the position is the one-dot chain line in FIG. 7, in step S10, the switching line P is shifted to the position where the high load portion is corrected to the low rotation side with respect to the one-dot chain line. This is to reduce the surge of the motor current that occurs when the output characteristic of the electric motor 5 is switched from the low speed mode to the high speed mode with the switching line P as a boundary.

  In general, the surge of the motor current that occurs when switching to the high-speed mode (a phenomenon in which the current temporarily becomes excessive) cannot be avoided at a certain level in the control of the motor, but if the surge amount is too large Further, the loss of the motor due to the flow of unnecessary high current increases, and the motor may be damaged. In particular, in the situation where the control for shifting the switching line P (step S10) is executed, that is, in the situation where the load of the electric motor 5 is expected to increase as the battery voltage Vb greatly decreases, the surge amount is reduced. There is concern about becoming oversized. Therefore, in order to suppress such an increase in surge amount, in step S10, as shown in FIG. 7, the shift amount of the switching line P is corrected to the lower rotation side in the higher load region.

  In other words, the surge amount of the motor current tends to increase in the high rotation / high load range where a higher target current value is set. However, it is advantageous in that the amount of surge can be reduced. In consideration of such points, in step S10, the switching line P is shifted to the lower rotation side in the higher load region, and thereby, the switching to the high speed mode in the high load region is earlier. The surge phenomenon as described above is suppressed.

  Returning to FIG. 6 again, the continuation of the flowchart will be described. When the shift of the switching line P is completed as described above, the controller 15 inputs “1” indicating that the switching line P has already been shifted to the line shift flag F (step S11), and then at the present time. Control is performed to determine whether the operating state of the electric motor 5 is on the higher rotation side than the shifted switching line P (the position of the solid line in FIG. 7) (step S12).

  As described above, since it has been confirmed in the previous step S9 that the operating state of the electric motor 5 is on the lower rotation side than the planned shift position of the switching line P, the determination in step S12 is initially NO. The Then, the controller 15 returns to step S2 to read the motor rotation speed N and the accelerator opening TVO, calculates the required torque in the next step S3, and further determines whether the line shift flag F = 1 in step S3. Determine whether or not.

  At this time, since “1” has already been input to the line shift flag F (step S11), the determination in step S3 is YES. Then, the controller 15 determines whether or not the result of predicting that the battery voltage Vb is reduced in step S8 is appropriate (step S14). For example, when the vehicle 1 deviates from the planned route set in the navigation unit 40, it is determined that the prediction result is not valid, and when the vehicle 1 is traveling according to the planned route, the prediction result is valid. It is determined that

  When it is determined YES in step S14 and it is confirmed that the prediction result is valid, the controller 15 proceeds to step S12, and the newly acquired values (motor rotational speed N and motor rotation speed N and S3) are transferred to steps S2 and S3. Control for determining whether or not the operating state of the electric motor 5 identified from the latest acquired value of the required torque is on the higher rotation side than the shifted switching line P (solid line in FIG. 7). Execute. If YES is determined here, the switching element Sw of the second inverter 12 is activated, and only the first winding L1 of the first and second windings L1 and L2 of the electric motor 5 has a current. By switching the current path so as to flow, control is performed to switch the output characteristics of the electric motor 5 from the low speed mode to the high speed mode (step S13). If NO is determined in step S14 and it is confirmed that the prediction result is not valid (that is, the battery voltage Vb does not decrease), the process returns and the control is repeated from the first step S1.

  Next, a description will be given of the control operation when it is determined NO in step S9, that is, when it is confirmed that the operating state of the electric motor 5 is on the higher rotation side than the planned shift position of the switching line P. . In this case, the controller 15 causes the operating state of the electric motor 5 to rotate at a higher speed than the normal switching line P set in step S6, that is, the switching line P set based on the current detected value of the battery voltage Vb. The control which determines whether it exists in the side is performed (step 15). And when it determines with YES here, while switching the output characteristic of the electric motor 5 to high speed mode (step S16), when it determines with NO, it returns.

  As a result, if the vehicle 1 is accelerating, the output characteristics of the electric motor 5 will soon be switched to the high speed mode with reference to the normal switching line P, and if the vehicle 1 is decelerating, the switching line P in step S10 will be changed. The shift of the switching line P is executed after waiting for the region to shift to the low rotation side from the planned shift position.

  Next, a description will be given of the control operation when it is determined NO in step S8, that is, when a decrease in the battery voltage Vb is not predicted. In this case, since it is not necessary to consider the influence due to the decrease in the battery voltage Vb, the controller 15 causes the output characteristics of the electric motor 5 to be higher than the normal switching line P (the line set in step S6). Is determined (step S15). If YES is determined here, control for switching the output characteristic of the electric motor 5 from the low speed mode to the high speed mode is executed (step S16).

  If NO is determined in step S7, that is, if the output characteristic of the electric motor 5 is set to the high speed mode, the process proceeds to step S17, where the output characteristic of the electric motor 5 is switched to normal. It is determined whether or not the rotation has shifted to the lower rotation side than the line P. And when it determines with YES by this step S17 and it has confirmed that it has shifted to the low rotation side rather than the switching line P, the switching element Sw of the said electric motor 5 is operated, and 1st, 2nd coil | winding L1 , L2 is performed so that the current path is switched so that the current flows through both of them, whereby the output characteristic of the electric motor 5 is controlled from the high speed mode to the low speed mode (step S18).

  As described above, the electric vehicle drive device of the present embodiment is configured so that the electric motor 5 that rotationally drives the drive wheels 16 of the vehicle 1 and the output characteristics of the electric motor 5 are represented by the switching line P on the control map M. The 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 power to the electric motor 5 And a battery sensor 37 (voltage detection means) for detecting a battery voltage Vb as a voltage value of a power source for supplying power. In this embodiment, as a control for the electric motor 5, a step (S5) of detecting the battery voltage Vb by the battery sensor 37, and the switching line P is set based on the voltage value Vb detected in this step. (S6), predicting that the battery voltage Vb will decrease (S8), and if it is predicted that the battery voltage Vb will decrease in this step, prior to the actual decrease of the voltage value The controller 15 executes a control operation including a step (S10) of shifting the switching line P to the low rotation side based on the predicted decrease degree. According to such a configuration, there is an advantage that the shock generated when the output characteristics of the electric motor 5 are switched can be reduced, and passenger comfort can be favorably maintained.

  For example, when the load of the electric motor 5 increases due to climbing or sudden acceleration, and the battery voltage Vb suddenly decreases accordingly, the switching line P is set to the low rotation side in accordance with the actual decrease of the battery voltage Vb. In such a case, as shown in FIG. 8, the position of the switching line P is suddenly changed, so that the output characteristic of the electric motor 5 is changed from the low speed mode to the high speed mode at an unintended timing. There is a possibility that a considerably large shock may occur in the vehicle 1 due to torque fluctuation at the time of switching. On the other hand, in the above embodiment, since the switching line P is shifted to the low rotation side based on the predicted degree of decrease prior to the decrease in the battery voltage Vb, the battery voltage Vb has already been reduced. The position of the switching line P is changed, and the unexpected switching of the output characteristics as described above is avoided. For this reason, according to the said embodiment, even if battery voltage Vb falls, an output characteristic can be switched at an appropriate timing, the shock which generate | occur | produces in that case can be reduced, and passenger comfort can be maintained favorably There are advantages.

  In the above embodiment, as shown in FIG. 7, when the switching line P is shifted prior to the decrease in the battery voltage Vb, the shift amount is corrected to the lower rotation side in the higher load region. . According to such a configuration, when a large load is applied to the electric motor 5 and the battery voltage Vb is lowered, the current surge phenomenon is caused by relatively increasing the switching timing to the high speed mode in the high load region. (A phenomenon in which a temporary high current flows through the electric motor 5 when switching to the high-speed mode) can be suppressed, and there is an advantage that loss / damage of the motor due to the surge phenomenon can be effectively prevented.

  In the above embodiment, even if a decrease in the battery voltage Vb is predicted in step S8, the operating state of the electric motor 5 is higher than the planned shift position of the switching line P in step S10. If there is (that is, NO in step S9), the shift to the low rotation side of the switching line P is prohibited by shifting to step S15 instead of step S10. According to such a configuration, it can be avoided that the output characteristics are switched to the high speed mode on the higher rotation side than the switching line P after the shift, and at that time, a large shock is effectively generated in the vehicle 1. There is an advantage that it can be prevented.

  Further, according to the above configuration, when the operation state shifts from the high rotation side to the low rotation side with respect to the normal switching line P before the shift, and the output characteristics are switched from the high speed mode to the low speed mode accordingly. Immediately after that, since the shift of the switching line P to the low speed side is prohibited, the switching line P is not switched again to the high speed mode immediately after the switching to the low speed mode, and before and after the shifting of the switching line P. Thus, there is an advantage that it is possible to effectively prevent the occupant from feeling uncomfortable due to frequent switching of the output characteristics.

  In the above embodiment, an example in which the control method of the present invention is applied to a hybrid vehicle that uses the engine 2 and the electric motor 5 as power sources has been described. However, the control method of the present invention is not limited to 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 vehicle 5 electric motor 9 battery (power supply device)
15 Controller (control means)
15a Line setting means 15b Prediction means 15c Shift means 16 Drive wheel 37 Battery sensor (voltage detection means)
M (M1, M2...) Control map P Switching line Vb Battery terminal voltage (voltage value of power supply device)

Claims (4)

The output characteristics of the electric motor that rotates the driving wheels of the vehicle can be handled from the low speed mode corresponding to the low rotation range to the low rotation range and the higher rotation range than the switching line on the control map. A motor control method for an electric vehicle that switches between different high-speed modes,
A voltage detection step of detecting a voltage value of a power supply device that supplies power to the electric motor;
A line setting step for setting the switching line based on the voltage value detected in this step;
A predicting step for predicting that the voltage value of the power supply device decreases;
When it is predicted that the voltage value will decrease in this step, prior to the actual decrease in the voltage value, the switching line set in the line setting step is shifted to the low rotation side based on the predicted decrease degree. A motor control method for an electric vehicle, comprising: a shift step for shifting. In the motor control method of the electric vehicle according to claim 1,
In the shift step, the motor control method for an electric vehicle is characterized in that the shift amount of the switching line is corrected to a lower rotation side as the load becomes higher. In the motor control method of the electric vehicle according to claim 1 or 2,
Even if a decrease in the voltage value is predicted by the prediction step, if the operation state of the electric motor is higher than the planned shift position of the switching line in the shift step, switching by the shift step is performed. A motor control method for an electric vehicle, wherein line shifting is prohibited. The electric motor that rotates the drive wheels of the vehicle, and the output characteristics of this electric motor, with the switching line on the control map as the boundary, the low-speed mode corresponding to the low-speed driving region, and the high-speed A drive device for an electric vehicle comprising: control means for switching between a high-speed mode capable of handling up to an operation region; and voltage detection means for detecting a voltage value of a power supply device that supplies electric power to the electric motor,
The control means includes
Line setting means for setting the switching line based on the voltage value detected by the voltage detection means;
Predicting means for predicting that the voltage value of the power supply device decreases;
When it is predicted that the voltage value is lowered by the predicting means, the switching line set by the line setting means is set on the low rotation side based on the predicted decrease degree before the actual voltage value is lowered. And an electric vehicle drive device characterized by having a shift means for shifting the motor to the electric vehicle.

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