JP5045572B2 - Control device for vehicle drive motor - Google Patents

Description

  The present invention relates to a vehicle drive motor control device, and more particularly, to a vehicle drive motor control device that executes control to reduce motor output torque when a motor is locked.

  Conventionally, a hybrid vehicle having both an engine and a motor as a power source for driving wheels is known. In this hybrid vehicle, a three-phase AC motor is generally used, and when a torque that is a wheel driving force is output to a motor, a DC voltage supplied from a battery is converted into an AC voltage by an inverter and applied to the motor.

  In the hybrid vehicle, for example, when a wheel is fitted into a depression or a side groove on the road and cannot be rotated, the wheel and the motor are connected via an axle, a gear train, etc. Even if the accelerator is depressed, the motor rotor cannot be rotated in the same manner. Such a state is referred to as a “motor lock state”.

  When the motor is locked and there is a large torque demand by the user's accelerator operation, a high current is applied to a specific phase coil among the U-phase, V-phase, and W-phase coils arranged in the stator of the three-phase AC motor. May flow in a single phase. If such a state continues, the coil of the specific phase and the switching element in the inverter corresponding thereto may be burned out due to overheating.

  In order to avoid the situation where the motor coil or the like is burned out in this way, it is preferable to execute control to reduce the motor torque by reducing the applied voltage to the motor when the motor lock state is detected. Since a sudden torque drop gives a driver a great sense of incongruity, for example, in the overload prevention device for an electric vehicle disclosed in Patent Document 1, it is described that the motor torque is gradually reduced in a substantially step shape.

JP-A-11-122703

  By the way, in a hybrid vehicle, a motor temperature is detected by a temperature sensor such as a thermistor installed in a motor stator, and when the detected temperature reaches a predetermined upper limit value, control for suppressing the motor output is executed to Prevents damage. In this case, a configuration in which three temperature sensors are installed corresponding to the U-phase, V-phase, and W-phase coils to detect the temperature of each phase coil leads to high costs and complicated control. It can be said that a simple and practical configuration is to arrange one temperature sensor corresponding to the coil and estimate the coil temperature of the other two phases from the coil temperature of the specific phase and use it for the motor output limitation. .

  However, if a temperature sensor is provided only in a specific phase coil, little or no current flows through the specific phase coil in the motor lock state as described above, and a high current flows intensively through the other phase coils. It is also assumed that thermal damage and burnout of the other phase coil cannot be prevented.

  An object of the present invention is to protect other phase coils other than the specific phase from thermal damage and burnout when the motor is locked in a three-phase AC motor provided with one temperature sensor corresponding to the specific phase coil. An object of the present invention is to provide a control device for a vehicle drive motor that can be used.

The vehicle drive motor control device according to the present invention includes a voltage conversion means for converting a DC voltage into an AC voltage and applying a wheel drive torque to a three-phase AC motor capable of outputting the wheel drive torque, and a three-phase stator of the three-phase AC motor. Current detection means for detecting AC current flowing in the coil, rotation speed detection means for detecting the rotation speed of the rotor of the three-phase AC motor, and coil temperature detection means for detecting the temperature of a specific phase coil among the three-phase coils And a control means for controlling the AC voltage output from the voltage conversion means according to the user request torque, the control means for the vehicle drive motor, the control means based on the user request torque and the rotation speed when it is determined that the motor lock state, the torque reduced to increase the torque of the three-phase AC motor, and thus reduce to a predetermined torque decrease target value until a predetermined torque increase target value Run the control, the average torque when running this torque reduction control, the based on the coil temperature of the particular phase coil to be less than the temperature capable of compensating torque threshold value for the other phase coil, the torque reduction target value The torque increase target value is set .

  In the vehicle drive motor control apparatus according to the present invention, the control means may repeatedly execute the torque reduction control until the motor lock state is eliminated.

Further, in the vehicle drive motor control device according to the present invention, the control means may set the torque reduction target value in the torque reduction control to a maximum continuous torque.

  Further, in the vehicle drive motor control apparatus according to the present invention, the control means may convert the torque to increase when the motor rotational speed becomes a predetermined value or more in the torque reduction control. In this case, the control means may change the predetermined value of the motor rotation speed in accordance with the accelerator opening of the vehicle.

According to the vehicle drive motor control device of the present invention, when the motor is locked, torque reduction control is executed. In this torque reduction control, the average torque of the motor is determined based on the coil temperature of the specific phase coil. The torque reduction target value and the torque increase target value in the torque reduction control are set so as to be equal to or lower than the temperature threshold value for which temperature compensation is possible. As a result, even if the motor is locked, temperature compensation control, that is, motor torque control for protecting the other phase coil from thermal damage or the like based on the temperature of the specific phase coil detected by the temperature detecting means is effective. It can be carried out.

  Embodiments according to the present invention will be described below in detail with reference to the accompanying drawings. In this description, specific shapes, materials, numerical values, directions, and the like are examples for facilitating the understanding of the present invention, and can be appropriately changed according to the application, purpose, specification, and the like. In the following, a hybrid vehicle will be described as an example, but the present invention is also applicable to an electric vehicle using only a motor as a power source.

  FIG. 1 is a diagram showing a schematic configuration of a hybrid vehicle 10 including a vehicle drive motor control device according to an embodiment of the present invention. In FIG. 1, the power transmission system is indicated by a solid line, the power line is indicated by a one-dot chain line, and the signal line is indicated by a dotted line. The hybrid vehicle 10 includes an engine 12 capable of outputting driving power, two three-phase AC synchronous motor generators (hereinafter simply referred to as “motors”) MG 1 and MG 2, and a power distribution and integration mechanism 14.

  The engine 12 is an internal combustion engine that uses gasoline, light oil, or the like as fuel. The engine 12 is electrically connected to an engine ECU (Electronic Control Unit) (hereinafter referred to as “engine ECU”) 16 and receives a control signal from the engine ECU 16 to inject fuel, ignite, intake air amount, and the like. The operation is controlled by adjusting. The rotational speed Ne of the engine 12 is calculated by the engine ECU 16 based on a detection value input from the rotational position sensor 11 provided in the vicinity of the output shaft 13 that outputs power from the engine 12.

  The power distribution and integration mechanism 14 includes a sun gear 18 disposed at the center, a ring gear 20 disposed concentrically with the sun gear 18 and having inner teeth at the inner periphery of the annular ring, and a plurality of meshing gears with both the sun gear 18 and the ring gear 20. And a planetary gear mechanism 22 including a planetary gear mechanism. The plurality of planetary gears 22 are rotatably attached to end portions of the carrier 26, respectively.

  In the power distribution and integration mechanism 14, the output shaft 13 of the engine 12 is connected to the carrier 26 via a damper 24 for reducing torque impact, and the rotary shaft 30 connected to the rotor 29 of the motor MG 1 is connected to the sun gear 18. The reduction gear 34 is connected to the ring gear 20 via the ring gear shaft 32. Thus, in the power distribution and integration mechanism 14, when the motor MG1 functions as a generator, the power from the engine 12 input from the carrier 26 is distributed to the sun gear 18 side and the ring gear 20 side according to the gear ratio. When the MG 1 functions as an electric motor, the power of the engine 12 input from the carrier 26 and the power from the MG 1 input from the sun gear 18 are integrated to reduce the speed including a gear train having a predetermined reduction ratio from the ring gear 20 via the ring gear shaft 32. It is input to the machine 34.

  A rotary shaft 38 connected to the rotor 36 of the motor MG2 is also connected to the speed reducer 34. When the motor MG2 functions as an electric motor, power from the motor MG2 is input to the speed reducer 34.

  The power input from at least one of the ring gear shaft 32 and the rotation shaft 38 of the MG 2 is transmitted to the axle 40 through the speed reducer 34, whereby the wheels 42 are rotationally driven. On the other hand, when power is input from the wheel 42 and the axle 40 to the rotary shaft 38 via the speed reducer 34 during regeneration, the MG 2 functions as a generator. Here, at the time of regeneration, not only when the driver decelerates the vehicle speed by performing a braking operation, but also when the driver releases the accelerator pedal and stops vehicle acceleration, or when the vehicle grabs downhill. Including the case of traveling by action.

  Motors MG 1 and MG 2 are electrically connected to corresponding inverters 44 and 46, respectively, and each of inverters 44 and 46 is electrically connected to battery 50 via a DC / DC converter (hereinafter simply referred to as “converter”) 48. Connected. The battery 50 is preferably a secondary battery such as a nickel metal hydride battery or a lithium ion battery.

  When motors MG1 and MG2 function as electric motors, DC voltage Vb supplied from battery 50 via smoothing capacitor 52 is boosted to output voltage Vc by converter 48, and then to smoothing capacitor 54 to inverters 44 and 46. (Converter output voltage Vc corresponds to inverter input voltage and system voltage VH. The same applies hereinafter), and is converted into an AC voltage by inverters 44 and 46 and input to motors MG1 and MG2.

  Conversely, when the motors MG1 and MG2 function as generators, the AC voltage output from the MG1 and MG2 is converted into DC by the inverters 44 and 46, and then the voltage is stepped down by the converter 48 to charge the battery 50. Since inverters 44 and 46 share power line 56 and ground line 58 connected to converter 48, the power generated by one of motors MG 1 and MG 2 is not transmitted through converter 48 but the other. It can also be driven to rotate by being supplied to this motor.

  Inverters 44 and 46 are electrically connected to a motor ECU (hereinafter referred to as “motor ECU”) 60, respectively, and are operated and controlled based on a control signal transmitted from motor ECU 60. The motors MG1 and MG2 are provided with rotation angle sensors 31 and 37 for detecting the rotation angles of the rotors 29 and 36, respectively. Detection values by the rotation angle sensors 31 and 37 are input to the motor ECU 60 and used to calculate the motor rotation speeds Nm1 and Nm2.

  The motor ECU 60 includes a CPU that executes a control program described later, a ROM that stores a control program, a control map, and the like, and a RAM that stores various detection values so that they can be read and rewritten as needed. The map stored in the ROM includes a coil temperature upper limit arrival time map. In this coil temperature upper limit arrival time map, the estimated coil temperature of the other phase (eg, U phase, V phase) rises to the upper limit value from the coil temperature of the specific phase (eg, W phase) detected by the temperature sensor. It is a map referred to in order to derive | lead-out the time which it takes in relation to a coil electric current value.

  The battery 50 is provided with an SOC sensor 62 for detecting the state of charge or the remaining capacity (SOC). The SOC sensor 62 can be configured by a current sensor that detects a charge / discharge current of the battery 50. The value detected by the SOC sensor 62 is input to a battery ECU (hereinafter referred to as “battery ECU”) 64. The battery ECU 62 is input with a battery voltage Vb detected by a voltage sensor, a battery temperature detected by a temperature sensor (not shown), and the like. The battery ECU 64 monitors the remaining battery capacity SOC based on the integrated value of the charge / discharge current detected by the SOC sensor 62 so that the battery remaining capacity SOC is maintained in an appropriate range. In the vicinity, output restriction and charge request signals are output to the hybrid ECU described later.

  As shown in FIG. 2, converter 48 is connected to battery 50 via system main relays SMR1, SMR2. System main relays SMR1 and SMR2 are turned on / off in response to switching signals S1 and S2 from motor ECU 60. Converter 48 includes a reactor L, power switching elements (hereinafter simply referred to as “switching elements”) E1 and E2, and diodes D1 and D2. Switching elements E 1 and E 2 are connected in series between power line 56 and ground line 58. As the switching elements E1 and E2, an IGBT (Insulated Gate Bipolar Transistor), a power MOS (Metal Oxide Semiconductor) transistor, a power bipolar transistor, or the like can be used. The diodes D1 and D2 are connected in parallel to the switching elements E1 and E2, respectively, so that a current flows from the emitter side to the collector side. Reactor L has one end connected to connection line 74 between switching elements E1 and E2, and the other end connected to the positive electrode of battery 50 via system main relay SMR1.

  The voltage across the smoothing capacitor 54 arranged between the converter 48 and the inverter 46, that is, the system voltage VH is detected by the voltage sensor 55 and input to the motor ECU 60.

  Inverter 46 includes a U-phase arm 78, a V-phase arm 80, and a W-phase arm 82 provided in parallel with each other between power line 56 and ground line 58. Each of the phase arms 78 to 82 includes two switching elements connected in series between the power line 56 and the ground line 58 and two diodes respectively connected in antiparallel to the switching elements. Specifically, U-phase arm 78 includes switching elements E3 and E4 and diodes D3 and D4, V-phase arm 80 includes switching elements E5 and E6 and diodes D5 and D6, and W-phase arm 82 includes switching elements E7 and E8. And diodes D7 and D8. For example, an IGBT or the like can be used for each of the switching elements E3 to E8. Switching elements E3 to E8 are on / off controlled by switching signals S3 to S8 from motor ECU 60.

  An intermediate point of each phase arm 78, 80, 82 is connected to one end of each phase coil of U phase, V phase and W phase (hereinafter simply referred to as “three phases”) of motor MG2. Each other end of each phase coil is commonly connected to a neutral point N in the motor MG2. Further, the current flowing through each phase coil is detected by the current sensor 84 and input to the motor ECU 60. Note that one current sensor may be omitted, and the omitted phase coil current may be calculated from the relationship that the sum of the other two-phase coil currents becomes zero.

  A temperature sensor 72 such as a thermistor for detecting the temperature of the W-phase coil is disposed on the outer peripheral portion of the stator of the motor MG2. The W phase coil temperature Tmw detected by the temperature sensor 72 is input to the motor ECU 60. Motor ECU 60 can estimate U-phase coil temperature Tmu and V-phase coil temperature Tmv based on W-phase coil temperature Tmw. This temperature estimation is performed using constants Ku and Kv that are optimally selected according to the characteristics of the motor MG2, the position of the temperature sensor 72, and the like.

  Engine ECU 16, motor ECU 60 and battery ECU 64 are electrically connected to a hybrid ECU (hereinafter referred to as “hybrid ECU”) 66. The hybrid ECU 66 has a function of comprehensively controlling the operation of the engine 12 and the motors MG1, MG2 and managing the battery 50.

  The hybrid ECU 66 transmits an engine control signal to and from the engine ECU 16 as necessary, and receives data relating to the engine operating state (for example, engine speed Ne) as necessary. Further, the hybrid ECU 66 transmits a required torque command Tr * to the motor ECU 60 as necessary, and receives data relating to the motor operating state (for example, motor rotation speeds Nm1, Nm2, motor current, etc.) as necessary. To do. Further, the hybrid ECU 66 receives data necessary for battery management such as the remaining battery capacity SOC, battery voltage, battery temperature, and input / output restriction signal from the battery ECU 64.

  Further, a vehicle speed sensor 68 and an accelerator opening sensor 70 are electrically connected to the hybrid ECU 66, and an accelerator opening corresponding to a vehicle speed Sv that is the traveling speed of the hybrid vehicle 10 and a depression amount of an accelerator pedal (not shown). Ac is input respectively.

  In hybrid vehicle 10 configured as described above, operation of engine 12 and motors MG1, MG2 is controlled by hybrid ECU 66 as follows.

  For example, when the hybrid vehicle 10 is started, the engine 12 is started using the motor MG1 as a so-called cell motor. When the engine is started, motor MG1 is driven by electric power supplied from battery 50 via converter 48 and inverter 44. However, when the vehicle starts with only the power output from the motor MG2 at the time of starting the vehicle, the engine is started only for warm-up operation.

  When the hybrid vehicle 10 starts from a stopped state, the vehicle 50 is normally driven by supplying power from the battery 50 to the motor MG2 via the converter 48 and the inverter 46, and the motor MG2 is started by outputting power only from the motor MG2. However, when the remaining capacity SOC of the battery 50 is reduced at this time and there is a charge request from the battery ECU 64, the power output from the engine 12 and distributed by the power distribution and integration mechanism 14 is input to the rotating shaft 30 of the motor MG1. The power is generated and the battery 50 is charged with the generated power.

  For example, when the hybrid vehicle 10 is traveling at a relatively light load, such as when the vehicle is traveling at a low speed or down a hill, fuel efficiency can be improved by outputting power from the engine 12 that is relatively inefficient in the low and medium rotation range. Since the engine 12 is stopped, the engine 12 is stopped while the remaining capacity SOC of the battery 50 is monitored, and the vehicle travels with power from only the motor MG2. At this time, when the remaining battery charge SOC decreases, the engine 12 is appropriately intermittently operated in response to a charge request from the battery ECU 64, and the battery 50 is charged by generating power with the motor MG1 with engine power.

  For example, during normal travel in which the hybrid vehicle 10 travels at a substantially constant and stable speed, the vehicle travels by outputting power from the engine 12 whose efficiency is relatively good in the middle and high speed rotation region. At this time, if necessary, for example, when the accelerator is temporarily stepped on and suddenly accelerates, power is supplied from the motor MG1 or the battery 50 in a power generation state by receiving the distribution of the engine power, and then the motor MG2 The power is also output to assist the power of the engine 12. Further, when the remaining battery capacity SOC is reduced, the output of the engine 12 is increased to increase the power distributed to the motor MG1, and a part of the electric power generated by the motor MG1 is charged in the battery 50.

  For example, during regeneration in which the hybrid vehicle 10 is decelerated by a brake operation, power is transmitted from the wheels 42 to the rotary shaft 38 via the axle 40 and the speed reducer 34, and the motor MG2 functions as a generator. The electric power generated by the motor MG2 during regeneration is converted into a DC voltage by the inverter 46, stepped down by the converter 48, and then charged to the battery 50.

  In the above, the inverter 46 corresponds to the voltage conversion means, the temperature sensor 72 corresponds to the temperature detection means, the rotation angle sensor 37 and a part of the motor ECU 60 correspond to the rotation speed detection means, and the current sensor 84 ( And, if necessary, a part of the motor ECU 60) corresponds to current detection means, and the motor ECU 60 corresponds to control means.

  Next, with reference to FIG. 3 to FIG. 5, a description will be given of torque control when the motor is locked during a so-called EV traveling that travels by outputting wheel driving force from only the motor MG2.

  In the hybrid vehicle 10 described above, for example, when the wheel 42 is fitted into a depression or a side groove on the road and cannot rotate, the wheel 42 and the rotor 36 of the motor MG2 include the axle 40, the speed reducer 34 including the gear train, and the rotation. Since it is connected via the shaft 38, the motor 36 is in a motor locked state in which the rotor 36 of the motor MG2 cannot rotate even when the driver as the user steps on the accelerator.

  Thus, when the motor is locked and there is still a large torque request by the user's accelerator operation, the U-phase, V-phase, and W-phase coils arranged in the stator of the motor MG2 are high in the specific phase coil. Current may flow in a single phase.

  In the motor ECU 60 of the hybrid vehicle 10, the W-phase coil temperature Tmw detected by the temperature sensor 72 normally (that is, other than when the motor is locked), and the U-phase estimated from the W-phase coil temperature Tmw using the constant K value, respectively. Temperature compensation control is performed to protect each phase coil from thermal damage and burnout by controlling the motor output, that is, the motor current, so that the coil temperature Tmu and the V-phase coil temperature Tmv do not exceed a predetermined upper limit value. . However, when the motor is locked, the temperature divergence between the W-phase coil temperature Tmw and the U-phase coil temperature Tmu and the V-phase coil temperature Tmv increases so rapidly that the above-described K value estimation cannot catch up. In the control, a situation occurs in which the U-phase coil and the V-phase coil cannot be effectively protected from thermal damage or the like. Therefore, in the vehicle drive motor control apparatus according to the present embodiment, the following torque reduction control is executed.

  FIG. 3 is a flowchart showing a processing procedure of torque reduction control executed by the motor ECU 60 when the motor is locked, and FIG. 4 is a diagram schematically showing changes in motor torque by the torque reduction control with the horizontal axis as a time axis. FIG. 5 is an enlarged view of the torque increase conversion portion in FIG.

  In FIG. 4, Tr <b> 1 indicates a point set as a target value when the torque is reduced in the torque reduction control, and is illustrated here as being consistent with the maximum continuous torque Trc. This “maximum continuable torque” is the output torque of the motor when a maximum current (DC current) allowed to continuously energize the coil of the specific phase of the motor MG2 in the motor locked state. In FIG. 4, Tr2 indicates a point set as a target value for increasing torque in torque reduction control. Here, upper limit torque Trth (hereinafter referred to as “ “Temperature-compensable upper limit torque”). Further, in FIG. 4, Trmean represents an average torque when the torque reduction control for decreasing the motor torque to Tr1 and increasing it to Tr2 is executed at least once.

  The motor ECU 60 determines whether or not the motor MG2 is in the motor lock state based on the user request torque Tr * by the user's accelerator operation and the motor rotation speed Nm2. As a specific example, when the user requested torque Tr * is the maximum torque Trmax that the motor MG2 can output with the accelerator opening fully open, and the motor rotation speed Nm2 is less than a predetermined value (for example, 100 rpm), the motor It is determined that the lock state is established. When it is determined that the motor is locked, the process shown in FIG. 3 is started.

  First, based on the W-phase coil temperature detected by the temperature sensor 72, the U-phase coil and the V-phase coil, which are other phases, are determined in advance by referring to the coil temperature upper limit arrival time map stored in the ROM. An arrival time estimated to reach the temperature upper limit value is acquired (step S10). At this time, when the estimated arrival times acquired for the U-phase coil and the V-phase coil are different, the shorter estimated arrival time is selected.

  Then, waiting for the set arrival time to elapse (step S12), the motor torque is reduced from the user request torque Trmax to the maximum continuous torque Tr1 at a predetermined down rate Rd (step S14). In this process, the switching elements E3 to E8 of the inverter 46 are controlled to reduce the motor input voltage, and the switching elements E1 and E2 of the converter 48 are controlled to reduce the system voltage VH as necessary. This is realized by reducing the current and the V-phase current. In addition, by reducing the motor torque, each phase current, especially the U-phase current and the V-phase current, is also reduced, so that the heat generation of the U-phase coil and the V-phase coil can be suppressed, and the temperature can be reduced by heat dissipation or active cooling by a refrigerant. As a result, a slight allowance to the temperature upper limit value is generated, and it becomes possible to obtain the coil temperature upper limit value arrival time again when the torque increases as will be described later.

  The reduction in motor torque due to step S14 is indicated by the falling portion 96 in FIG. At this time, if the torque is instantaneously reduced (for example, the torque is reduced downward from the maximum torque Trmax in FIG. 4), the driver who is the user is greatly discomfort due to sudden torque loss. The torque reduction is executed with a predetermined down rate Rd.

  Next, it is determined whether the accelerator opening degree Ac by a user operation is 70% or more (step S16). If the accelerator opening degree Ac is less than 70%, a predetermined threshold value of the motor rotational speed for determining the torque increase conversion is set to 100 rpm, and it is determined whether or not the rotational speed of the motor MG2 is 100 rpm or more (step) S18) On the other hand, if the accelerator opening degree Ac is 70% or more, the predetermined threshold value of the motor rotational speed Nm2 for determining the torque increase conversion is set to 50 rpm, and whether the rotational speed Nm2 of the motor MG2 is 50 rpm or more. Is determined (step S20).

  When the motor torque is reduced by the process in step S14, the force relationship that has been balanced with the maximum torque Trmax and in the motor lock state is lost, so that the gear of the speed reducer 34 is maintained even if the wheels 42 are fixed. The rotor 36 rotates slightly backward by an amount corresponding to the backlash of the row. Therefore, in step S18 or S20, the angular movement of the rotor 36 in the reverse rotation direction is detected by the rotation angle sensor 37, and the rotation speed Nm2 of the motor MG2 calculated based on the detected rotation angle becomes equal to or greater than a predetermined threshold value. (NO in step S18 or S20), the reduction of the motor torque in step S14 at the predetermined down rate Rd is continued. At this time, if the motor torque reaches the target value Tr1 before the motor rotation speed Nm2 becomes equal to or greater than the predetermined threshold value, the further torque reduction is stopped and the continuous maximum torque Tr1 is maintained.

  When the rotational speed Nm2 of the motor MG2 becomes equal to or greater than a predetermined threshold (YES in step S18 or S20), the motor torque once decreased is converted into an increase, and the motor torque is increased at a predetermined up rate Ru to a set target value Tr2. (Step S22). This increase in motor torque is indicated by a rising portion 98 in FIG. 4 and is realized by increasing the motor input voltage from the inverter 46.

  In FIG. 4, the predetermined up rate Ru that is the inclination of the rising portion 98 is set to be slightly smaller (that is, the inclination is gentle) than the predetermined down rate Rd that is the inclination of the falling portion 96 in absolute value comparison. However, as long as the condition that the average torque Trmean in the torque reduction control is equal to or lower than the temperature-compensable upper limit torque Trth is satisfied, the predetermined up-rate Ru may be equal to or higher than the predetermined down-rate in absolute value comparison. .

  FIG. 5 is an enlarged view of a portion where the motor torque is increased in the torque reduction control. A rising portion 98a indicated by a dotted line indicates an increase in torque when the motor rotation speed Nm2 becomes 100 rpm or more, and a rising portion 98b indicated by a solid line indicates an increase in torque when the motor rotation speed Nm2 becomes 50 rpm. As described above, when the accelerator opening degree Ac is large, the motor torque can be increased more quickly by setting the motor rotation speed threshold used for the torque increase determination to be small, and the response performance according to the user request can be improved. . In addition, assuming that the motor lock state occurs on an uphill slope, the longer the time for which the motor torque is greatly reduced, the longer the rearward distance of the vehicle, the earlier the timing. The conversion to torque increase also has the significance of ensuring the safety of the vehicle by reducing the rearward distance.

  Following the execution of the process of increasing the motor torque, it is determined whether or not the motor lock state has been eliminated (step S24). Here, after the motor torque is increased to the predetermined target value Tr2 by the process of step S22, it is determined whether or not the rotational speed Nm2 of the motor MG2 in the positive direction of the rotor 36 is 100 rpm or more. If the motor lock state is resolved (YES in step S24), the process is terminated as it is.

  On the other hand, if the motor lock state is not resolved (NO in step S24), it is determined whether or not there is a large torque request that exceeds the temperature compensable upper limit torque Trth by the accelerator operation by the user (step S26). If there is no torque request (NO in step S26), the process ends. On the other hand, if there is a torque request (YES in step S26), the process returns to step S10 and the torque reduction control described above is executed again. At this time, if the estimated temperatures of the U-phase coil and the V-phase coil are not less than or equal to the upper limit values, the upper limit value arrival time is set to zero (steps S10 and S12) and immediately after the torque reaches the target upper limit value Tr2. The process of step S14 is executed.

  Then, as long as the motor lock state is not eliminated, the torque reduction control including the processing of steps S10 to S26 is repeatedly executed, and the motor torque is between the target lower limit value Tr1 and the target upper limit value Tr2 as shown in FIG. It will be controlled to draw a zigzag shape. In this control, at least one of the predetermined down rate Rd and the predetermined up rate is adjusted so that the average torque Trmean of the motor torque that vibrates up and down does not exceed the temperature compensable upper limit torque Trth. Thereby, based on the temperature Tmw of the W constant-phase coil detected by the temperature sensor 72, temperature compensation can be performed for the U-phase coil and the V-phase coil, and it is possible to protect from thermal damage and burnout.

  In the torque reduction control, the target lower limit value Tr1 at the time of torque reduction is described as the maximum continuous torque Trc, and the target upper limit value Tr2 at the time of torque increase is described as the temperature compensateable upper limit torque Trth. However, the present invention is not limited to this. As long as at least one of the predetermined down rate Rd and the predetermined up rate is adjusted so that the average torque Trmean does not exceed the temperature-compensable upper limit torque Trth, the Tr1 and Tr2 can be appropriately set. .

1 is a schematic configuration diagram of a hybrid vehicle to which a vehicle drive motor control device according to an embodiment of the present invention is applied. It is a figure which shows the structure of the inverter and converter which comprise the control apparatus of the vehicle drive motor of FIG. It is a flowchart which shows the process sequence in the control apparatus of the vehicle drive motor of FIG. It is a figure which shows the state from which a motor torque changes according to control by the process sequence of FIG. It is an enlarged view of the torque increase conversion part in FIG.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 Hybrid vehicle, 11 Rotation position sensor, 12 Engine, 13 Output shaft, 14 Power distribution integration mechanism, 16 Engine ECU, 18 Sun gear, 20 Ring gear, 22 Planetary gear, 24 Damper, 26 Carrier, 29 Rotor, 30 Rotating shaft, 31, 37 rotation angle sensor, 32 ring gear shaft, 34 speed reducer, 36 rotor, 38 rotation shaft, 40 axle, 42 wheels, 44, 46 inverter, 48 converter, 50 battery, 52, 54 smoothing capacitor, 55 voltage sensor, 56 power line 58 ground line, 60 motor ECU, 62 SOC sensor, 64 battery ECU, 66 hybrid ECU, 68 vehicle speed sensor, 70 accelerator opening sensor, 72 temperature sensor, MG1, MG2 three-phase AC motor.

Claims (5)

A voltage conversion means for converting a DC voltage into an AC voltage and applying a wheel driving torque to a three-phase AC motor, a current detection means for detecting an AC current flowing in a three-phase coil of a stator of the three-phase AC motor, Output from the rotation speed detection means for detecting the rotation speed of the rotor of the three-phase AC motor, the coil temperature detection means for detecting the temperature of the coil of the specific phase among the three-phase coils, and the voltage conversion means according to the user requested torque A control means for controlling the AC voltage, and a vehicle drive motor control device comprising:
Control means, when it is determined that the motor lock state based on a user requested torque and rotational speed, three-phase AC motor torque prescribed torque increase target value or from lowering to a predetermined torque decrease the target value of The torque reduction control to be increased is executed, and the average torque when the torque reduction control is executed is set to be equal to or less than the torque threshold value that allows temperature compensation for the other phase coil based on the coil temperature of the specific phase coil. A control device for a motor for driving a vehicle, characterized in that a torque decrease target value and the torque increase target value are set . The vehicle drive motor control device according to claim 1,
The control means repeatedly performs the torque reduction control until the motor lock state is eliminated. The vehicle drive motor control device according to claim 1 or 2,
The control means sets the torque reduction target value in the torque reduction control to a maximum continuous torque , and a vehicle drive motor control device. In the control apparatus of the vehicle drive motor of any one of Claim 1 to 3,
The control means is a control device for a vehicle driving motor, wherein the torque reduction control switches to a torque increase when the motor rotation speed exceeds a predetermined value. The vehicle drive motor control device according to claim 4,
The control means changes the predetermined value of the motor rotation speed in accordance with the accelerator opening of the vehicle.

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