JP2014117013A - Control device for motor and vehicle with motor mounted therein as drive source - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve the problem that it is excessive protection to restrict output of a motor when a magnet temperature exceeds a predetermined threshold, in order to avoid irreversible demagnetization occurrence in a permanent magnet provided in the motor, and unwanted output reduction of the motor results therefrom, such that it is necessary to consider not only the magnet temperature but also a demagnetized field strength when determining the presence/absence of the possibility of irreversible demagnetization occurrence.SOLUTION: A vehicle 10 includes a storage battery 20, a first motor 81, a second motor 82, an internal combustion engine 83 and a control device 100. The control device 100 determines the presence/absence of the possibility of irreversible demagnetization occurrence from a rotation speed and a combination of torque and a permanent magnet temperature. When the possibility of irreversible demagnetization occurrence is present, the control device 100 performs torque restriction control.

Description

  The present invention relates to an electric motor control device including a permanent magnet and a vehicle equipped with the electric motor as a drive source.

  In recent years, a hybrid vehicle and an electric vehicle equipped with an electric motor for driving a vehicle have become widespread against the background of increasing environmental awareness. Many of these vehicles employ a permanent magnet synchronous motor in which a permanent magnet is embedded in a rotor because it is efficient, can be reduced in size, and is easy to maintain.

  However, the permanent magnet has a property called “high temperature demagnetization” in which the magnetic flux decreases as the temperature of the permanent magnet (hereinafter simply referred to as “permanent magnet temperature”) increases. Furthermore, when the permanent magnet temperature exceeds a predetermined threshold, a phenomenon called “irreversible demagnetization” may occur in which the magnetic flux generated from the permanent magnet is not completely recovered even if the permanent magnet temperature is subsequently returned to room temperature. . If irreversible demagnetization occurs, the maximum torque that can be generated by the motor decreases, or the efficiency of the motor decreases. As a result, the running performance (power performance, power consumption, etc.) of the vehicle equipped with the electric motor is lowered.

  In order to avoid the occurrence of such irreversible demagnetization, one conventional motor control device limits the torque of the motor when the permanent magnet temperature rises (see, for example, Patent Document 1).

JP 2003-235286 A

  By the way, whether or not the above-described irreversible demagnetization occurs depends not only on the permanent magnet temperature but also on the strength (magnitude) of the demagnetizing field. Here, the demagnetizing field refers to a magnetic field in a direction opposite to the magnetic field generated by the permanent magnet of the electric motor and applied to the permanent magnet from the outside. More specifically, the permanent magnet temperature at which irreversible demagnetization occurs decreases as the strength of the demagnetizing field increases. A region where irreversible demagnetization of the permanent magnet occurs and is determined by the permanent magnet temperature and the demagnetizing field strength is also referred to as “irreversible demagnetization generation region” of the permanent magnet.

  Therefore, as in the above-described conventional apparatus, regardless of the demagnetizing field strength, it is determined that there is a possibility that irreversible demagnetization may occur when the permanent magnet temperature of the motor becomes high, and the permanent magnet temperature is lowered. When control (torque limit control) for temporarily reducing the torque generated by the electric motor is performed, the torque limit control may be performed in spite of the situation where irreversible demagnetization does not occur. Such torque limit control not only provides excessive protection for the electric motor, but also unnecessarily reduces the ability of the electric motor.

  Accordingly, one of the objects of the present invention is to provide a motor control device and a vehicle that avoids irreversible demagnetization of a permanent magnet and does not perform unnecessary torque limit control.

The motor control device of the present invention (hereinafter also referred to as “the device of the present invention”) for achieving the above object is applied to a motor including a permanent magnet.
The device of the present invention includes a target setting unit that sets a target torque that is a target value of the torque that should be generated by the electric motor, a determination unit, and a torque control unit.

The determination unit
Whether or not irreversible demagnetization of the permanent magnet occurs when the motor generates the target torque, a value correlated with the temperature of the permanent magnet, and the strength of the demagnetizing field applied to the permanent magnet from the outside The determination is made based on the value having a correlation with the magnitude of the demagnetizing field. As described above, the demagnetizing field is a magnetic field in a direction opposite to the magnetic field generated by the permanent magnet, and is a magnetic field applied to the permanent magnet from the outside when the electric motor generates the target torque.

The torque control unit
When it is determined that the irreversible demagnetization occurs, the motor is configured to control the motor so as to generate a torque lower than the target torque (that is, to execute torque limit control).

  According to the device of the present invention, the determination as to whether or not to perform torque limit control for avoiding irreversible demagnetization is performed based not only on the permanent magnet temperature but also on the demagnetizing field strength. Accordingly, when it is more certain that the state of the motor is in the irreversible demagnetization generation region, the torque limit control of the motor is executed. As a result, since the motor is not excessively protected, the motor control device can sufficiently exert the capability of the motor while avoiding irreversible demagnetization.

Furthermore, the torque control unit
When it is determined that the irreversible demagnetization does not occur, the motor may be configured to control the motor so as to generate a torque substantially equal to the target torque.

  According to the device of the present invention, when irreversible demagnetization has not occurred, the torque limit control is not executed, and the electric motor generates the target torque. As a result, since unnecessary protection of the electric motor is not performed, the motor control device can sufficiently exert the capability of the electric motor while reliably avoiding irreversible demagnetization.

  By the way, the demagnetizing field of the permanent magnet of the electric motor is actually a magnetic field generated by the coil of the electric motor. The intensity of the magnetic field generated by the coil has a correlation with the voltage applied to the motor. The voltage applied to the electric motor is often determined based on the rotational speed of the electric motor and the target torque of the electric motor. In particular, when the electric motor is mounted as a driving source of the vehicle, the voltage applied to the electric motor has a correlation with the rotational speed of the motor having a correlation with the traveling speed of the vehicle and the torque required for driving the vehicle. Is determined based on the target torque.

  Therefore, it is preferable that the control device for the electric motor is configured such that the determination unit acquires a value having a correlation with the intensity of the demagnetizing field based on the rotation speed of the electric motor and the target torque. . According to this, a value having a correlation with the intensity of the demagnetizing field can be acquired with relatively simple accuracy with a simple configuration.

  As an aspect of the torque limit control for avoiding irreversible demagnetization of the permanent magnet, the torque control unit may temporarily set the torque generated by the electric motor to “0”. However, even in the case where torque limit control is to be performed, it is desirable for the motor to generate torque that is as close as possible to the required torque in a range where irreversible demagnetization does not occur. In particular, when an electric motor is used as a drive source for a vehicle, even if torque limit control is performed, the motor is caused to generate a torque close to “torque required for driving the vehicle”. Is desirable.

  Therefore, the torque control unit is configured to control the electric motor so that the electric motor generates the largest torque within a range in which the irreversible demagnetization does not occur when it is determined that the irreversible demagnetization occurs. Is preferred.

  The present invention is applicable not only to the motor control device described above but also to a “vehicle equipped with an electric motor as a drive source” that performs the same operation as the motor control device. It extends to the control method of the motor.

1 is a schematic configuration diagram of a vehicle to which a motor control device according to an embodiment of the present invention is applied. It is a figure which shows each pulse waveform of sine wave PWM control, overmodulation PWM control, and rectangular wave control. It is mapping information for determining the control mode of a 1st motor from the rotational speed and generated torque of a 1st motor shown in FIG. It is mapping information for determining the control mode of a 2nd motor from the rotational speed and generated torque of a 2nd motor shown in FIG. It is the block diagram which showed each function performed when the control apparatus shown in FIG. 1 drives a 1st motor using PWM control. It is a figure which shows the map showing the irreversible demagnetization generation | occurrence | production area | region for every temperature of the permanent magnet with which the 1st electric motor shown in FIG. 1 is equipped. 2 is a flowchart illustrating a process for the vehicle control device shown in FIG. 1 to perform torque limit control of a first motor. It is the figure which showed the mode of the torque limitation control which the vehicle control apparatus shown in FIG. 1 performs in order to avoid the irreversible demagnetization of the permanent magnet of an electric motor. 2 is a graph showing a correlation between a demagnetization amount of the first electric motor shown in FIG. 1 and a permanent magnet temperature. It is the block diagram which showed each function performed when the control apparatus shown in FIG. 1 drives a 1st electric motor using rectangular wave control. It is a figure which shows the map showing the irreversible demagnetization generation | occurrence | production area | region for every temperature of the permanent magnet with which the 2nd electric motor shown in FIG. 1 is equipped.

Hereinafter, the “motor control device according to the embodiment of the present invention” will be described with reference to the drawings.
(Constitution)
This control device is applied to the vehicle 10 whose schematic configuration is shown in FIG. Vehicle 10 is a hybrid vehicle including storage battery 20, boost converter 30, first inverter 40, second inverter 60, first electric motor 81, second electric motor 82, internal combustion engine 83, power split mechanism 90, and control device 100. .

  The storage battery 20 is a secondary battery that can be charged and discharged, and is a lithium ion battery in this embodiment. The storage battery 20 outputs DC power to a pair of storage battery terminal portions (P1, N1). The storage battery 20 is charged by a voltage applied to the pair of storage battery terminal portions (P1, N1) from the outside.

  Boost converter 30 includes a boost chopper circuit. Boost converter 30 uses a boost chopper circuit to convert low-voltage side voltage VL substantially equal to the voltage (that is, storage battery voltage) between the pair of storage battery terminal portions (P1, N1) to high-voltage side voltage VH, and , And vice versa. Boost converter 30 includes a pair of low-voltage side terminal portions (P2, N2) and a pair of high-voltage side terminal portions (P3, N3). Boost converter 30 includes a capacitor 31, a reactor 32, a first IGBT 33, a diode 34, a second IGBT 35, a diode 36 and a capacitor 37.

  The capacitor 31 is inserted between a pair of power lines connected to the pair of low voltage side terminal portions (P2, N2). The capacitor 31 smoothes the low voltage side voltage VL. The reactor 32 is inserted in series with respect to the high-voltage terminal part (P3, N3) side from the capacitor 31.

  A diode 34 is connected in reverse parallel to the first IGBT 33, and a diode 36 is connected in reverse parallel to the second IGBT 35. The first IGBT 33 and the second IGBT 35 are connected in series so that the anode of the diode 34 and the cathode of the diode 36 are connected at the intermediate connection point Q, and are inserted between the pair of high-voltage side terminal portions (P3, N3). Yes. A reactor 32 is connected to the intermediate connection point Q. The capacitor 37 is inserted between the pair of high-voltage side terminal portions (P3, N3). The capacitor 37 smoothes the high voltage side voltage VH.

  Each switching element (the first IGBT 33 and the second IGBT 35) is switched based on a PWM (Pulse Width Modulation) signal from the control device 100, so that the boost converter 30 converts the above-described voltage conversion (that is, the low-voltage side voltage VL). A step-up operation for converting the high-voltage side voltage VH and a step-down operation for converting the high-voltage side voltage VH to the low-voltage side voltage VL are performed.

  The first inverter 40 converts the DC power output from the boost converter 30 into U-phase, V-phase, and W-phase three-phase AC power and outputs it to the first electric motor 81. The second inverter 60 converts the DC power output from the boost converter 30 into U-phase, V-phase, and W-phase three-phase AC power and outputs it to the second electric motor 82.

  When the first motor 81 operates as a generator, the first inverter 40 converts the AC power output from the first motor 81 into DC power and outputs the DC power to the boost converter 30. Similarly, when the second motor 82 operates as a generator, the second inverter 60 converts the AC power output from the second motor 82 into DC power and outputs the DC power to the boost converter 30. Boost converter 30 converts the converted DC power into a voltage (steps down) and outputs it between storage battery terminal portions (P1, N1) (that is, storage battery 20). As a result, the storage battery 20 is charged.

  The first inverter 40 includes a pair of input terminal portions (P4, N4). The pair of input terminal portions (P4, N4) are connected to the pair of high-voltage side terminal portions (P3, N3) of the boost converter 30, respectively. First inverter 40 includes a U-phase arm, a V-phase arm, and a W-phase arm. Each of these arms is inserted between a pair of input terminal portions (P4, N4) and connected in parallel to each other.

  The U-phase arm of the first inverter 40 includes an IGBT 41 and an IGBT 42. A diode 51 and a diode 52 are connected in reverse parallel to the IGBT 41 and the IGBT 42, respectively. The IGBT 41 and the IGBT 42 are connected in series so that the anode of the diode 51 and the cathode of the diode 52 are connected. A connection point between the IGBT 41 and the IGBT 42 is connected to a U-phase coil (not shown) of the first electric motor 81.

  The V-phase arm of the first inverter 40 includes an IGBT 43 and an IGBT 44. A diode 53 and a diode 54 are connected in reverse parallel to the IGBT 43 and IGBT 44, respectively. The IGBT 43 and the IGBT 44 are connected in series so that the anode of the diode 53 and the cathode of the diode 54 are connected. A connection point between the IGBT 43 and the IGBT 44 is connected to a V-phase coil (not shown) of the first electric motor 81.

  The W-phase arm of the first inverter 40 includes an IGBT 45 and an IGBT 46. A diode 55 and a diode 56 are connected in reverse parallel to the IGBT 45 and IGBT 46, respectively. The IGBT 45 and the IGBT 46 are connected in series so that the anode of the diode 55 and the cathode of the diode 56 are connected. A connection point between the IGBT 45 and the IGBT 46 is connected to a W-phase coil (not shown) of the first electric motor 81.

  The second inverter 60 includes a pair of input terminal portions (P5, N5). The pair of input terminal portions (P5, N5) are connected to the pair of high-voltage side terminal portions (P3, N3) of the boost converter 30, respectively. Second inverter 60 includes a U-phase arm, a V-phase arm, and a W-phase arm. Each of these arms is inserted between a pair of input terminal portions (P5, N5) and connected in parallel to each other.

  The U-phase arm of the second inverter 60 includes an IGBT 61 and an IGBT 62. A diode 71 and a diode 72 are connected in reverse parallel to the IGBT 61 and the IGBT 62, respectively. The IGBT 61 and the IGBT 62 are connected in series so that the anode of the diode 71 and the cathode of the diode 72 are connected. A connection point between the IGBT 61 and the IGBT 62 is connected to a U-phase coil (not shown) of the second electric motor 82.

  The V-phase arm of the second inverter 60 includes an IGBT 63 and an IGBT 64. A diode 73 and a diode 74 are connected in reverse parallel to the IGBT 63 and IGBT 64, respectively. The IGBT 63 and the IGBT 64 are connected in series so that the anode of the diode 73 and the cathode of the diode 74 are connected. A connection point between the IGBT 63 and the IGBT 64 is connected to a V-phase coil (not shown) of the second electric motor 82.

  The W-phase arm of second inverter 60 includes IGBT 65 and IGBT 66. A diode 75 and a diode 76 are connected in reverse parallel to the IGBT 65 and IGBT 66, respectively. The IGBT 65 and the IGBT 66 are connected in series so that the anode of the diode 75 and the cathode of the diode 76 are connected. A connection point between the IGBT 65 and the IGBT 66 is connected to a W-phase coil (not shown) of the second electric motor 82.

  The first inverter 40 and the second inverter 60 are controlled by switching their switching elements (IGBT) based on a signal from the control device 100. Specifically, the first inverter 40 converts the DC power between the input terminal portions (P4, N4) into three-phase AC power by switching the IGBTs 41-46 based on a signal from the control device 100. And it outputs to the 1st electric motor 81 from the connection point of two IGBT in each arm of U phase, V phase, and W phase.

  Similarly, the second inverter 60 converts the DC power between the input terminal portions (P5, N5) into three-phase AC power by switching the IGBTs 61-66 based on the signal from the control device 100. , U-phase, V-phase, and W-phase arms are output to the second motor 82 from the connection point of the two IGBTs.

  Each of the first electric motor 81 and the second electric motor 82 includes a stator including a three-phase winding (coil) that generates a rotating magnetic field, and a permanent magnet that generates torque by a magnetic force attracted or repelled by the rotating magnetic field. Including a rotor. Each of the first electric motor 81 and the second electric motor 82 operates as a motor and can also operate as a generator. The first electric motor 81 is mainly used as a generator, and can crank the internal combustion engine 83 when the internal combustion engine 83 is started. The second electric motor 82 is mainly used as an electric motor, and can generate driving force (torque for running the vehicle) of the vehicle 10.

  The internal combustion engine 83 is a gasoline fuel engine and can generate the driving force of the vehicle 10. The intake air amount and the fuel injection amount of the internal combustion engine 83 are controlled based on a signal from the control device 100.

  The power split mechanism 90 is a planetary gear mechanism. The power split mechanism 90 rotates a sun gear (not shown), a ring gear (not shown) concentrically arranged with the sun gear, a plurality of pinion gears (not shown) that mesh with the sun gear and mesh with the ring gear, and a plurality of pinion gears. A pinion carrier (not shown) that holds the sun gear in a state where it can revolve around the sun gear.

  The output shaft of the first electric motor 81 is connected to the sun gear so that torque can be transmitted. A crankshaft of the internal combustion engine 83 is connected to the pinion carrier so that torque can be transmitted. An output shaft of the second electric motor 82 is connected to the ring gear via a speed reduction mechanism 91 so that torque can be transmitted. Further, the output shaft of the second electric motor 82 is connected to the axle 92 through the speed reduction mechanism 91 so that torque can be transmitted. The axle 92 is connected to the drive wheel 94 via a differential gear 93 so that torque can be transmitted.

  The control device 100 includes a plurality of electronic control units (ECU: Electronic Control Units) for controlling the vehicle 10. That is, the control device 100 includes a power management ECU that performs overall control such as vehicle driving force and battery charging, an MG-ECU that controls the first motor 81 and the second motor 82, an engine ECU that controls the internal combustion engine 83, and The battery-ECU etc. which monitor the storage battery 20 etc. are included. Each electronic control unit is a microcomputer that includes a CPU, a memory, and the like and executes each program. Each electronic control unit exchanges information with each other through a communication line.

  Further, the vehicle 10 includes a voltmeter 21, a voltmeter 22, an ammeter 23, an ammeter 24, and a rotation angle sensor 25. The voltmeter 21 measures the low voltage VL and sends it to the control device 100. The voltmeter 22 measures the high-voltage side voltage VH and sends it to the control device 100. The ammeter 23 measures the current Iu flowing in the U phase of the first electric motor 81 and sends it to the control device 100. The ammeter 24 measures the current Iv flowing in the V phase of the first electric motor 81 and sends it to the control device 100. Since one end of the U phase, the V phase, and the W phase is connected to the neutral point C, the current Iw flowing through the W phase of the first electric motor 81 is expressed as Iw = − (Iu + Iv) based on Iu and Iv. Can be calculated. Therefore, an ammeter for measuring the current Iw is not provided in this embodiment. The rotation angle sensor 25 measures the rotation angle θ1 of the first electric motor 81 and sends the information to the control device 100. In the present embodiment, the rotation angle sensor 25 is realized by a resolver.

  The vehicle 10 includes an ammeter 26, an ammeter 27, and a rotation angle sensor 28. The ammeter 26 measures the current Iu <b> 2 flowing in the U phase of the second electric motor 82 and sends it to the control device 100. The ammeter 27 measures the current Iv <b> 2 flowing in the V phase of the second electric motor 82 and sends it to the control device 100. The current Iw2 flowing in the W phase of the second electric motor 82 can be calculated as Iw2 = − (Iu2 + Iv2) based on Iu2 and Iv2. Therefore, an ammeter for measuring the current Iw2 is not provided in this embodiment. The rotation angle sensor 28 measures the rotation angle θ <b> 2 of the second electric motor 82 and sends the information to the control device 100. In the present embodiment, the rotation angle sensor 28 is realized by a resolver.

(Operation)
Next, the operation of the control device 100 configured as described above (accordingly, the vehicle 10) will be described.
<Vehicle drive control>
The control device 100 determines the user request torque Tr and the user request output Pr required for the drive wheels 94 based on the depression amount of the accelerator pedal of the vehicle 10 and the traveling speed of the vehicle 10 at a predetermined timing. Note that the accelerator pedal depression amount and the traveling speed are detected based on signals from an accelerator pedal depression amount sensor and a vehicle speed sensor (not shown), respectively. Furthermore, the control device 100 determines the charge request output Pb based on the remaining capacity (SOC: State Of Charge) of the storage battery 20 estimated separately.

  Next, the control device 100 determines whether or not the engine request output Pe that is “the total value of the user request output Pr, the charge request output Pb and the assumed energy loss” is equal to or greater than a predetermined output threshold value PEth. If engine request output Pe is equal to or greater than output threshold value PEth, control device 100 operates internal combustion engine 83. Further, the control device 100 determines the internal combustion engine command torque Te and the internal combustion engine rotational speed Ne so that the internal combustion engine 83 is operated most efficiently while generating an output equal to the engine required output Pe. Further, the control device 100 determines a command torque T1 of the first motor 81 that operates as a generator and a command torque T2 of the second motor 82 that operates as a motor. The command torque T2 is equal to the shortage of the torque acting on the ring gear from the internal combustion engine 83 based on the internal combustion engine command torque Te with respect to the user request torque Tr.

  On the other hand, if engine request output Pe is smaller than output threshold value PEth, control device 100 stops internal combustion engine 83. In this case, since the control device 100 does not operate the first motor 81 as a generator, the command torque T1 of the first motor 81 is set to “0”, and the command torque T2 of the second motor 82 is set to the user request torque. Set to a value equal to Tr. These command torques are also called target torques. As will be described later, the command torque T1 may be reduced when there is a high possibility that irreversible demagnetization of the first motor 81 will occur. Similarly, the command torque T2 is reduced by irreversible demagnetization of the second motor 82. May be reduced when there is a high risk of occurrence. The reduced command torque is also referred to as “post-correction command torque”, and the command torque before being reduced is also referred to as “pre-correction command torque”.

  The control device 100 controls “AC power output from the first inverter 40 to the first motor 81” so that the first motor 81 generates a torque equal to the command torque T1. The control device 100 controls “AC power output from the second inverter 60 to the second motor 82” so that the second motor 82 generates a torque equal to the command torque T2. Further, when the internal combustion engine 83 is operated, the control device 100 causes the internal combustion engine 83 to generate a torque equal to the command torque Te and to be operated at a rotational speed equal to the internal combustion engine rotational speed Ne. The intake air amount and the fuel injection amount are controlled.

  Such drive control of the first electric motor 81, the second electric motor 82, and the internal combustion engine 83 is, for example, disclosed in Japanese Patent Application Laid-Open No. 2009-126450 (US Published Patent No. US 2010/0241297) and Japanese Patent Application Laid-Open No. 9-308012. (US Patent No. 6,131,680 filed on March 10, 1997) and the like. These are incorporated herein by reference.

<Outline of torque limit control>
Next, an outline of torque limit control executed by the control device 100 will be described. The torque limit control is control for avoiding irreversible demagnetization of the permanent magnet of the electric motor (the first electric motor 81 and the second electric motor 82). The torque limit control is similarly executed for each of the first electric motor 81 and the second electric motor 82. In the following, “motor” refers to one of the first motor 81 and the second motor 82. Furthermore, the point determined by the “rotational speed and torque” of the motor is also referred to as the operating point of the motor.

  The electric motor is controlled by one of the control modes of “sine wave PWM control, overmodulation PWM control and rectangular wave control” shown in FIG. These control modes will be described in detail later. For example, the first motor 81 is driven by sine wave PWM control when the operating point of the first motor 81 is in the region A11 of the map shown in FIG. 3, and is excessive when the operating point of the first motor 81 is in the region A12. Driven by modulation PWM control and driven by rectangular wave control when the operating point of the first electric motor 81 is in the region A13. Similarly, the second motor 82 is driven by sine wave PWM control when the operating point of the second motor 82 is in the area A21 of the map shown in FIG. 4, and when the operating point of the second motor 82 is in the area A22. Driven by overmodulation PWM control and driven by rectangular wave control when the operating point of the second motor 82 is in the region A23.

  By the way, one of the main causes of the temperature rise of the permanent magnet of the electric motor is eddy current loss. That is, when the magnetic field (flux lines) penetrating the permanent magnet varies with time, an eddy current is generated near the surface of the permanent magnet. As a result, Joule heat is generated by the eddy current, and the temperature of the permanent magnet rises. This eddy current loss is proportional to the square of the frequency of the magnetic field change.

  In a permanent magnet used for an electric motor, for example, the frequency of magnetic field change is relatively higher when the rotational speed of the electric motor is higher than when the rotational speed is low. Furthermore, the sine wave PWM signal includes relatively more harmonic components than the overmodulation PWM signal and the rectangular wave signal. For this reason, when the electric motor is rotating at a specific rotation speed, the frequency of the magnetic field change becomes relatively high when controlled by the sine wave PWM control.

  The inventor examined the operating point at which the eddy current loss increases for the first motor 81 and the second motor 82 (that is, the operating point at which the permanent magnet temperature is most likely to rise) based on this viewpoint. As a result, for the first motor 81, as shown by the region S1 in FIG. 3, the region where the output is maximum in the region A11 controlled by the sine wave PWM control is the region where the temperature of the permanent magnet is most likely to rise. The conclusion that it is. Regarding the second electric motor 82, as shown by the region S2 in FIG. 4, it was concluded that the region with the highest rotation speed is the region where the temperature of the permanent magnet is most likely to rise.

  On the other hand, the permanent magnet temperature at which irreversible demagnetization occurs decreases as the demagnetizing field strength increases. In other words, even when the intensity of the demagnetizing field is specific, there are cases where irreversible demagnetization occurs and does not occur depending on the permanent magnet temperature.

  Generally, the strength of the demagnetizing field applied to the permanent magnet of the electric motor increases as the rotational speed increases and the electric motor torque increases. Therefore, for the first motor 81, as shown in the region F1 in FIG. 3, the region with the largest output is the irreversible demagnetization generation region. Furthermore, the operating range in which irreversible demagnetization occurs increases as the permanent magnet temperature Th1 of the first electric motor 81 increases. Similarly, for the second electric motor 82, as shown in the region F2, the region where the output is the largest and the torque is the largest is the irreversible demagnetization generation region. Furthermore, the operating range in which irreversible demagnetization occurs increases as the permanent magnet temperature Th2 of the second electric motor 82 increases.

  From these, it is understood that when the first electric motor 81 is operated in the region F1 after being operated in the region S1 in FIG. 3, the possibility of occurrence of irreversible demagnetization is greatly increased. Similarly, when the second electric motor 82 is operated in the region F2 after being operated in the region S2, it is understood that the possibility of irreversible demagnetization is greatly increased.

  Therefore, the control device 100 estimates (or detects) the permanent magnet temperature of the electric motor by a method described later, and uses the operating point of the electric motor (the current electric motor rotational speed and the newly obtained command torque) under the permanent magnet temperature. It is determined whether or not the determined command operating point is within the operating region where irreversible demagnetization occurs. When the command operating point of the electric motor is within the operation region where irreversible demagnetization occurs, the control device 100 corrects the command torque to be reduced, thereby shifting the command operating point outside the irreversible demagnetizing region. In this case, the decrease-corrected command torque is the torque closest to the command torque before the decrease correction and outside the irreversible demagnetization region. As a result, the control device 100 can cause the electric motor to generate torque as close as possible to the torque before correction while avoiding occurrence of irreversible demagnetization. The above is the outline of the torque limit control.

<< Details of motor control >>
Next, details of the control of the first electric motor 81 and the second electric motor 82 by the control device 100 will be described. The control device 100 changes the ON / OFF timing of each switching element of the boost converter 30 and the first inverter 40 in order to cause the first electric motor 81 to generate a torque equal to the command torque T1. Control the output. Specifically, the control device 100 controls the output of the first inverter 40 by selectively executing sine wave PWM control, overmodulation PWM control, and rectangular wave control. Similarly, the control device 100 changes the ON / OFF timing of each switching element of the boost converter 30 and the second inverter 60 in order to cause the second electric motor 82 to generate a torque equal to the command torque T2. The output of the inverter 60 is controlled. Specifically, the control device 100 controls the output of the second inverter 60 by selectively executing sine wave PWM control, overmodulation PWM control, or rectangular wave control.

<<<< PWM control and rectangular wave control >>>>
The PWM control (sine wave PWM control and overmodulation PWM control) is realized by adjusting the on / off timing of each switching element of the inverter by pulse width modulation. More specifically, in the sine wave PWM control, as shown in FIG. 2A, a sine wave as a modulation wave signal and a triangular wave as a carrier signal are used, and a comparison result thereof. The on / off state (switching signal) of each switching element of the inverter is determined based on the above. In the sine wave PWM control, the amplitude of the sine wave is equal to or less than the amplitude of the triangular wave. That is, in the sine wave PWM control, each switching element of the inverter is maintained in the ON state in a period in which the modulation wave signal (sine wave) is larger than the carrier signal (triangular wave), and the modulation wave signal (sine wave) is transferred to the carrier signal (sine wave). Each switching element of the inverter is maintained in the OFF state in a period smaller than the triangular wave. 2A is, for example, a waveform for the U phase of the motor, and a waveform for the V phase is generated by delaying the phase of the sine wave shown in FIG. 2A by 120 degrees. The waveform for the W phase is generated by delaying the phase of the sine wave shown in FIG.

  Also in the overmodulation PWM control, as shown in FIG. 2B, a sine wave as a modulation wave signal and a triangular wave as a carrier signal are used, and each switching of the inverter is performed based on the comparison result. The on / off state (switching signal) of the element is determined. That is, also in overmodulation PWM control, each switching element of the inverter is maintained in an ON state during a period in which the modulation wave signal (sine wave) is larger than the carrier signal (triangular wave), and the modulation wave signal (sine wave) is transferred to the carrier signal (sine wave). Each switching element of the inverter is maintained in the OFF state in a period smaller than the triangular wave. However, in overmodulation PWM control, the amplitude of the sine wave is larger than the amplitude of the triangular wave. As a result, the ON time of each switching element of the inverter during overmodulation PWM control is longer than the ON time of each switching element of the inverter during sine wave PWM control, so that the output of the electric motor increases. The waveform shown in FIG. 2B is, for example, the waveform for the U phase of the motor, and the waveform for the V phase is generated by delaying the phase of the sine wave shown in FIG. 2B by 120 degrees. The waveform for the W phase is generated by delaying the phase of the sine wave shown in FIG. 2B by 240 degrees.

  Also in the rectangular wave control, as shown in FIG. 2C, a sine wave as a modulation wave signal and a triangular wave as a carrier signal are used, and each switching element of the inverter is based on the comparison result. The on / off state (switching signal) is determined. That is, also in the rectangular wave control, each switching element of the inverter is maintained in the ON state in a period in which the modulation wave signal (sine wave) is larger than the carrier signal (triangular wave), and the modulation wave signal (sine wave) The switching elements of the inverter are maintained in the off state in a period smaller than (). However, in the rectangular wave control, the amplitude of the modulation wave signal (sine wave) is set to infinity. Therefore, substantially, each switching element of the inverter is maintained in the on state when the modulation wave signal is positive, and each switching element of the inverter is maintained in the off state when the modulation wave signal is negative. As a result, the output of the inverter in the rectangular wave control is not a PWM waveform but a rectangle. Since the ON time of the switching element in the rectangular wave control becomes longer than the ON time of the switching element in the overmodulation PWM control, the output of the electric motor further increases. On the other hand, in the rectangular wave control, the number of pulses applied to the electric motor is reduced, so that it is difficult to precisely adjust the current flowing through the coil of the electric motor by adjusting the pulse width.

  Basically, in each control described above, the output voltage of the boost converter 30 (that is, the input voltage of the first inverter 40 and the second inverter 60) VH is changed to change the electric motor (that is, the first motor). 81 and the output torque of the second electric motor 82) are changed.

<<< Control mode selection >>>
The control device 100 determines which of the “sine wave PWM control, overmodulation PWM control, and rectangular wave control” is used to control the first electric motor 81 based on the rotational speed ω1 and the command torque T1 ( Actually, it is determined based on a post-correction command torque T1a) described later (that is, the control mode is selected). The control device 100 selects the sine wave PWM control when the output (= rotational speed × torque) of the first electric motor 81 is low, and the output of the first electric motor 81 rises and exceeds the controllable range by the sine wave PWM control. Overmodulation PWM control is selected, and when the output of the first motor 81 further increases and exceeds the controllable range by overmodulation PWM control, rectangular wave control is selected.

  More specifically, in the control device 100, the operating point of the first electric motor 81 determined by the combination of the rotational speed ω1 and the corrected command torque T1a is any of the areas A11 to A13 of the map shown in FIG. The control mode is determined based on whether or not When the operating point of first motor 81 is in region A11 of FIG. 3, control device 100 selects sine wave PWM control as the control mode of first motor 81. Furthermore, the control device 100 selects overmodulation PWM control when the operating point of the first motor 81 is in the region A12, and selects rectangular wave control when the operating point of the first motor 81 is in the region A13.

  The control device 100 determines (ie, selects) the control mode of the second electric motor 82 based on the rotational speed ω2 of the second electric motor 82 and the corrected command torque T2a. More specifically, the control device 100 determines whether the operating point of the second electric motor 82 determined by the combination of the rotational speed ω2 and the corrected command torque T2a is any of the areas A21 to A23 of the map shown in FIG. The control mode is determined based on whether the area is present. When the operating point of the second electric motor 82 is in the region A21 of FIG. 4, the control device 100 selects the sine wave PWM control as the control mode of the second electric motor 82. Further, control device 100 selects overmodulation PWM control when the operating point of the second motor is in region A22, and selects rectangular wave control when the operating point of second motor 82 is in region A23.

  In FIG. 4, there is a constant output region (that is, a region where the output of the motor is maximum) in which the torque and the rotational speed are in an inversely proportional relationship in the high rotation region where the second electric motor 82 is controlled by the rectangular wave control. Although it exists, the same area does not exist in FIG. This is different from the second electric motor 82 used as a driving force source of the vehicle 10 in order to prevent the first electric motor 81 mainly used as a generator from becoming an excessive load on the second electric motor 82 and the internal combustion engine 83. This is because it is determined not to generate high torque.

<<< Control for Boost Converter and First Inverter >>>
Next, in order to cause the first electric motor 81 to generate a torque equal to the command torque T1 (actually, the corrected command torque T1a), the “control for the boost converter 30 and the first inverter 40” is executed by the control device 100. Will be described. In order to cause the second motor 82 to generate a torque equal to the command torque T2 (actually, the corrected command torque T2a), the “control on the boost converter 30 and the second inverter 60” executed by the control device 100 is This is the same as the control related to the first electric motor 81.

A. Sine Wave PWM Control and Overmodulation PWM Control First, sine wave PWM control and overmodulation PWM control will be described. FIG. 5 shows a control block (functional block) executed when the control device 100 controls the first electric motor 81 by PWM control (sine wave PWM control and overmodulation PWM control). Each control block is realized by a control calculation process according to a predetermined program executed by the control device 100.

  The torque setting unit 110 sets the command torque T1 (pre-correction command torque T1b) based on the engine request output Pe and the like as described above. Torque setting unit 110 outputs pre-correction command torque T1b to operation adjustment unit 111.

  The operation adjustment unit 111 adjusts (corrects) the command torque for avoiding irreversible demagnetization of the permanent magnet of the first motor 81 and selection of the control mode of the first motor 81. Operation adjustment unit 111 receives pre-correction command torque T1b of first electric motor 81 from torque setting unit 110. The operation adjustment unit 111 further receives the rotational speed ω <b> 1 of the first electric motor 81 and the permanent magnet temperature Th <b> 1 of the first electric motor 81. The calculation process of the rotational speed ω1 and the permanent magnet temperature Th1 will be described later.

  The operation adjustment unit 111 holds the map shown in FIG. 6 in the ROM. The map shown in FIG. 6 shows the irreversible demagnetization generation region of the first motor 81 for each permanent magnet temperature of the first motor 81 as “the combination of rotational speed and torque (that is, the first motor 81 Operating point) ”. Data constituting this map is acquired in advance by experiments or the like.

  Further, the operation adjustment unit 111 performs the processing shown by the flowchart shown in FIG. That is, the CPU of the control device 100 (hereinafter referred to as CPU) starts processing from step 700 at a predetermined timing in order to realize the function of the operation adjustment unit 111 and proceeds to step 705. Whether the current operating point of the motor 81 (the current command torque T1 (pre-correction command torque T1b) and the operating point determined by the rotational speed ω1) is included in the “irreversible demagnetization generation region determined by the current permanent magnet temperature Th1”. Determine whether or not. Specifically, the CPU refers to the above-described map using the permanent magnet temperature Th1 and “rotational speed ω1 and pre-correction command torque T1b (operating point)”, and the operating point is in the irreversible demagnetization generation region. If it is included, “Yes” is determined in step 705 and the process proceeds to step 710.

  In step 710, the CPU crosses the boundary of the irreversible demagnetization generation region so that the operating point P1 of the first electric motor 81 goes out of the irreversible demagnetization generation region as shown in FIG. The pre-correction command torque T1b is reduced (so that the operating point of the electric motor 81 becomes P2), and the reduced value is set as the post-correction command torque T1a. Thereafter, the CPU proceeds to step 720.

  On the other hand, if the operating point is not included in the irreversible demagnetization generation region, the CPU makes a “No” determination at step 705 to proceed to step 715. In this case, since it is not necessary to correct the pre-correction command torque T1b, the CPU sets the post-correction command torque T1a equal to the pre-correction command torque T1b in step 715. Thereafter, the CPU proceeds to step 720.

  In step 720, the CPU determines the control mode of the first electric motor 81 with reference to the map shown in FIG. Thereafter, the CPU proceeds to step 795 to end the present routine tentatively.

  The operation adjustment unit 111 outputs the corrected command torque T1a to the DC control unit 112. When the control mode of the first motor 81 determined in step 720 is PWM control (sine wave PWM control or overmodulation PWM control), the operation adjusting unit 111 further controls the control mode (sine wave PWM control or overmodulation). Mod) is output to the PWM1 generator 125, and the corrected command torque T1a is output to the current command generator 120.

  The DC controller 112 receives the corrected command torque T1a of the first motor 81 and the rotation speed ω1 of the first motor, and calculates the output Pm1 (= T1a × ω1) of the first motor 81 based on these values. The DC controller 112 further receives the corrected command torque T2a of the second motor 82 and the rotational speed ω2 of the second motor 82, and calculates the output Pm2 (= T2a × ω2) of the second motor 82. In FIG. 5, the input of the corrected command torque T2a of the second motor 82 and the rotational speed ω2 of the second motor to the DC control unit 112 is omitted.

  The DC control unit 112 calculates a high-voltage side command voltage VH * that is necessary for the first motor 81 and the second motor 82 to output the output Pm1 and the output Pm2, respectively. The DC control unit 112 outputs the high voltage side command voltage VH * to the PWMc generation unit 113.

  The PWMc generator 113 receives the high voltage side command voltage VH * and the low voltage side voltage VL. The PWMc generator 113 generates a PWM signal PWMc for controlling each switching element of the boost converter 30 and outputs the PWM signal PWMc to the boost converter 30 so that the boost converter 30 outputs a voltage equal to the high-voltage command voltage VH *. Boost converter 30 performs switching (ie, voltage conversion) in accordance with PWM signal PWMc, and outputs a voltage equal to high-voltage command voltage VH * to first inverter 40 and second inverter 60.

  Three-phase / two-phase current converter 114 receives U-phase current Iu and V-phase current Iv from ammeter 23 and ammeter 24. As described above, the three-phase / two-phase current converter 114 calculates the W-phase current Iw based on the relationship of Iw = − (Iu + Iv). The three-phase / two-phase current converter 114 receives the rotation angle θ <b> 1 of the first electric motor 81 from the rotation angle sensor 25. The three-phase / two-phase current conversion unit 114 is based on the U-phase current Iu, the V-phase current Iv, and the W-phase current Iw of the first motor 81 by coordinate conversion from the three-phase to the two-phase using the rotation angle θ1. The d-axis current Id and the q-axis current Iq are calculated. The three-phase / two-phase current conversion unit 114 outputs the d-axis current Id to the subtractor 121 and outputs the q-axis current Iq to the subtractor 122.

  The rotation speed detector 115 receives the rotation angle θ1 of the first electric motor 81 from the rotation angle sensor 25, and calculates the rotation speed ω1 of the first electric motor 81 from the rotation angle θ1. The rotation speed detection unit 115 outputs the rotation speed ω1 to the operation adjustment unit 111, the DC control unit 112, the current command generation unit 120, the PWM reference value generation unit 130, and the demagnetization amount calculation unit 131.

  The current command generation unit 120 receives the corrected command torque T1a from the operation adjustment unit 111, receives the rotation speed ω1 of the first motor from the rotation speed detection unit 115, and receives the high-voltage side voltage VH from the voltmeter 22. The current command generator 120 generates a d-axis command current Id * and a q-axis command current Iq * necessary for causing the first electric motor 81 to generate the corrected command torque T1a. The current command generator 120 outputs the d-axis command current Id * to the subtractor 121 and the PWM reference value generator 130, and outputs the q-axis command current Iq * to the subtractor 122 and the PWM reference value generator 130.

  Subtractor 121 receives d-axis command current Id * from current command generation unit 120 and receives d-axis current Id from three-phase / 2-phase current conversion unit 114. The subtractor 121 calculates a d-axis current deviation ΔId (= Id * −Id) that is a deviation between the d-axis command current Id * and the d-axis current Id, and outputs the d-axis current deviation ΔId to the PI control unit 123. To do.

  Subtractor 122 receives q-axis command current Iq * from current command generation unit 120 and q-axis current Iq from three-phase / 2-phase current conversion unit 114. The subtractor 122 calculates a q-axis current deviation ΔIq (= Iq * −Iq) that is a deviation between the q-axis command current Iq * and the q-axis current Iq, and outputs the q-axis current deviation ΔIq to the PI control unit 123. To do.

  PI control unit 123 receives d-axis current deviation ΔId from subtractor 121 and q-axis current deviation ΔIq from subtractor 122. The PI control unit 123 performs PI calculation (proportional integration calculation) with a predetermined PI gain for each of the d-axis current deviation ΔId and the q-axis current deviation ΔIq, and obtains the d-axis command voltage Vd * and the q-axis command voltage Vq *. calculate. The PI control unit 123 outputs the d-axis command voltage Vd * and the q-axis command voltage Vq * to the 2-phase / 3-phase voltage conversion unit 124. The PI control unit 123 also outputs the q-axis command voltage Vq * to the demagnetization amount calculation unit 131.

  The two-phase / 3-phase voltage converter 124 receives the rotation angle θ1 of the first electric motor 81 from the rotation angle sensor 25, and receives the d-axis command voltage Vd * and the q-axis command voltage Vq * from the PI control unit 123. The two-phase / three-phase voltage converter 124 converts the U-phase command voltage Vu * based on the d-axis command voltage Vd * and the q-axis command voltage Vq * by coordinate conversion from the two-phase to the three-phase using the rotation angle θ1. The V-phase command voltage Vv * and the W-phase command voltage Vw * are calculated. The two-phase / three-phase voltage converter 124 outputs the U-phase command voltage Vu *, the V-phase command voltage Vv *, and the W-phase command voltage Vw * to the PWM1 generator 125.

  PWM1 generation unit 125 receives control mode mod of first electric motor 81 from operation adjustment unit 111. PWM1 generator 125 further receives U-phase command voltage Vu *, V-phase command voltage Vv *, W-phase command voltage Vw *, and high-voltage side voltage VH. The PWM1 generator 125 generates a PWM signal PWM1 that controls each switching element of the inverter 40 based on the received signal. The PWM1 generator 125 outputs the PWM signal PWM1 to the first inverter 40. The first inverter 40 performs switching (that is, conversion from DC power to AC power) in accordance with the PWM signal PWM1, thereby controlling the first electric motor 81 by sine wave PWM control or overmodulation PWM control and correcting the command. A torque equal to the torque T1a is generated.

B. Estimation of permanent magnet temperature in sine wave PWM control and overmodulation PWM control Next, a method of calculating the amount of demagnetization of the permanent magnet of the first electric motor 81 and a method of estimating the permanent magnet temperature will be described.

B-1. Method for calculating the amount of demagnetization of the permanent magnet When controlling the motor using coordinate conversion from the three-phase AC of the U phase, V phase and W phase to the dq axis (coordinate conversion from the three phases to the two phases) The q-axis voltage equation is as follows.
Vq = ωφ + ωLdId + RIq (1)
Here, Vq: q-axis voltage, ω: rotational speed, φ: permanent magnet magnetic flux, Ld: reactor, Id: d-axis current, R: armature resistance, and Iq: q-axis current, and ωφ The term represents the counter electromotive force generated in the coil. However, since the value of RIq has a minimum value and can be omitted, the q-axis voltage equation is substantially as follows.
Vq = ωφ + ωLdId (2)

Furthermore, the voltage equation of the q axis when the permanent magnet demagnetization (this is not irreversible demagnetization but reversible high temperature demagnetization) occurs as follows.
Vq ′ = ωφ ′ + ωLdId (3)
Here, Vq ′ is the q-axis voltage when demagnetization occurs, and φ ′ is the magnetic flux of the permanent magnet when demagnetization occurs.

The following equation is obtained by subtraction (3)-(2) of the equation.
φ−φ ′ = (Vq−Vq ′) / ω (4)
When demagnetization is occurring, the left side of Equation (4) represents the amount of demagnetization, and φ−φ ′> 0 when demagnetization occurs. In this case, Vq−Vq ′ on the right side represents a reduction amount of the back electromotive force generated in the coil of the electric motor.

  The control device 100 determines the q-axis voltage Vq when the first motor 81 is controlled by PWM control and no demagnetization of the permanent magnet of the first motor 81 occurs (that is, when the permanent magnet temperature is low). As a value having a correlation with the d-axis current Id, the q-axis current Iq, and the rotational speed ω1 of the first electric motor 81, it is held in the ROM in the form of a map. Data constituting this map is acquired in advance by experiments or the like. Then, the control device 100 determines that the d-axis command current Id * and the q-axis command current Iq * are the target values of the d-axis current Id and the q-axis current Iq of the first motor 81 during the operation of the first motor 81, respectively. In addition, the rotation speed ω1 is acquired, and the map is referred to based on these values, thereby acquiring the q-axis voltage Vq (assuming that no demagnetization has occurred at that time).

  The control device 100 further acquires the q-axis command voltage Vq * calculated by the PI control unit 123 as the q-axis voltage Vq ′ at the present time (that is, in a situation where demagnetization may occur). The control device 100 calculates the demagnetization amount (φ−φ ′) of the permanent magnet of the first electric motor 81 by substituting these values (that is, Vq, Vq ′, and ω1) into Expression (4).

B-2. Method for Estimating Permanent Magnet Temperature When demagnetization of a permanent magnet occurs as the permanent magnet temperature increases, the amount of demagnetization and the permanent magnet temperature are in a proportional relationship as shown in FIG. For this reason, the control device 100 holds the relationship between the demagnetization amount and the magnet temperature obtained beforehand through experiments or the like in the form of a map in the ROM. Then, the permanent magnet temperature is estimated by referring to the map based on the demagnetization amount (φ−φ ′) obtained by the above equation (4).

B-3. Specific Estimation Logic of Permanent Magnet Temperature Next, a control block relating to estimation of the permanent magnet temperature will be described. The PWM reference value generation unit 130 receives the d-axis command current Id * and the q-axis command current Iq * from the current command generation unit 120, and receives the rotation speed ω1 from the rotation speed detection unit 115. The PWM reference value generation unit 130 refers to the above-described map for obtaining the q-axis voltage Vq using these values, and calculates the q-axis reference value voltage Vqb that is the q-axis voltage when no demagnetization occurs. . The PWM reference value generation unit 130 outputs the q-axis reference value voltage Vqb to the demagnetization amount calculation unit 131.

  The demagnetization amount calculation unit 131 receives the q-axis reference value voltage Vqb from the PWM reference value generation unit 130, receives the q-axis command voltage Vq * from the PI control unit 123, and receives the rotation speed ω1 from the rotation speed detection unit 115. The demagnetization amount calculation unit 131 determines the demagnetization amount Δφ of the permanent magnet of the first electric motor 81 based on the deviation (Vq * −Vqb) of the q-axis command voltage Vq * and the q-axis reference value voltage Vqb and the rotational speed ω1 (that is, , A value corresponding to φ−φ ′ in equation (4). The demagnetization amount calculation unit 131 outputs the demagnetization amount Δφ to the temperature estimation unit 132.

  The temperature estimation unit 132 receives the demagnetization amount Δφ from the demagnetization amount calculation unit 131. The temperature estimation unit 132 holds the correlation between the permanent magnet demagnetization amount Δφ of the first electric motor 81 and the permanent magnet temperature Th1 as a map as shown in FIG. The demagnetization amount calculation unit 131 refers to this map and estimates the permanent magnet temperature Th1 from the demagnetization amount Δφ of the permanent magnet. The temperature estimation unit 132 outputs the permanent magnet temperature Th1 to the operation adjustment unit 111.

  By the processing described above, the control device 100 sets a value smaller than the pre-correction command torque T1b as the post-correction command torque T1a when irreversible demagnetization of the permanent magnet of the first electric motor 81 may occur. Furthermore, the control device 100 controls the boost converter 30 and the first inverter 40 so that the torque generated by the first electric motor 81 matches the corrected command torque T1a by sine wave PWM control or overmodulation PWM control.

C. Rectangular Wave Control Next, rectangular wave control will be described. FIG. 10 shows a control block (functional block) executed when the control device 100 controls the first electric motor 81 by the rectangular wave control. Each control block is realized by a control calculation process according to a predetermined program executed by the control device 100. However, the operations of the torque setting unit 110, the operation adjustment unit 111, the DC control unit 112, the PWMc generation unit 113, and the rotation speed detection unit 115 are the same as those in the case of the above-described PWM control, and thus description thereof is omitted.

The power calculation unit 140 receives the U-phase current Iu and the V-phase current Iv from the ammeter 23 and the ammeter 24. As described above, power calculation unit 140 calculates W-phase current Iw based on the relationship of Iw = − (Iu + Iv). Power calculation unit 140 receives U-phase command voltage Vu *, V-phase command voltage Vv *, and W-phase command voltage Vw * from rectangular wave generation unit 144. The power calculation unit 140 calculates supply power Po1 that the first inverter 40 supplies to the first motor 81 from the following equation.
Po1 = Iu · Vu * + Iv · Vv * + Iw · Vw * (5)
The power calculation unit 140 outputs the supplied power Po1 to the torque calculation unit 141.

  Torque calculation unit 141 receives supply power Po1 from power calculation unit 140 and receives rotation speed ω1 from rotation speed detection unit 115. The torque calculator 141 calculates the generated torque To1 (= Po1 / ω1) of the first electric motor 81. The torque calculation unit 141 outputs the generated torque To1 to the subtractor 142 and the rectangular wave reference value generation unit 146.

  The subtractor 142 receives the corrected command torque T1a from the operation adjustment unit 111 and the generated torque To1 from the torque calculation unit 141. The subtractor 142 calculates a torque deviation ΔTr (= T1a−To1) that is a deviation between the corrected command torque T1a and the generated torque To1, and outputs the torque deviation ΔTr to the PI control unit 143.

  PI control unit 143 receives torque deviation ΔTr from subtractor 142. The PI control unit 143 performs PI calculation (proportional integration calculation) with a predetermined PI gain on the torque deviation ΔTr, and calculates the phase Φv of the rectangular wave voltage output from the first inverter 40. Specifically, when the torque deviation ΔTr is positive, that is, when the torque is insufficient, the PI control unit 143 advances the phase Φv. On the other hand, when the torque deviation ΔTr is negative, that is, when the torque is excessive, the PI control unit 143 delays the phase Φv. The PI control unit 143 outputs the phase Φv to the rectangular wave generation unit 144.

  The rectangular wave generation unit 144 receives the phase Φv from the PI control unit 143 and receives the rotation angle θ1 of the first electric motor 81 from the rotation angle sensor 25. The rectangular wave generator 144 calculates the U-phase command voltage Vu *, the V-phase command voltage Vv *, and the W-phase command voltage Vw * according to the rotation angle θ1. The rectangular wave generator 144 outputs each phase command voltage to the power calculator 140, the signal generator 145, and the three-phase / two-phase voltage converter 147.

  The signal generator 145 receives the U-phase command voltage Vu *, the V-phase command voltage Vv * and the W-phase command voltage Vw * from the rectangular wave generator 144, and receives the high-voltage side voltage VH from the voltmeter 22. The signal generator 145 generates a signal for controlling each switching element of the first inverter 40. The signal generator 145 outputs the control signal to the first inverter 40.

D. Estimation of Permanent Magnet Temperature in Rectangular Wave Control Next, a process in which the control device 100 estimates the permanent magnet temperature of the first electric motor 81 when the first electric motor 81 is controlled by the rectangular wave control will be described.

D-1. Calculation Method of Demagnetization Amount of Permanent Magnet As in the case of PWM control, the control device 100 calculates the demagnetization amount (φ−φ ′) using Equation (4) and demagnetizes using the demagnetization amount. The permanent magnet temperature is estimated with reference to a map of the magnetic quantity and the permanent magnet temperature. However, the calculation method of the q-axis voltage Vq when the demagnetization of the permanent magnet of the first electric motor 81 does not occur (that is, when the permanent magnet temperature is low) is different from that in the PWM control.

  Specifically, the control device 100 controls the first electric motor 81 by the rectangular wave control and the permanent magnet of the first electric motor 81 is not demagnetized (that is, when the permanent magnet temperature is low). The q-axis voltage Vq is held in the ROM in the form of a map as a value having a correlation with the high-voltage side voltage VH, the rotational speed ω1 and the generated torque To1. Data constituting this map is acquired in advance by experiments or the like. Then, the control device 100 obtains the high-voltage side voltage VH, the rotational speed ω1 and the generated torque To1 of the first motor 81 during the operation of the first motor 81, and refers to this map (by decreasing at that time). The q-axis voltage Vq (assuming that no magnetism is generated) is acquired.

  The control device 100 further calculates a q-axis command voltage calculated by a three-phase / two-phase voltage conversion unit 147 described later as the current q-axis voltage Vq ′ (that is, in a situation where demagnetization may occur). Vq * is acquired. The control device 100 calculates the demagnetization amount (φ−φ ′) of the permanent magnet of the first electric motor 81 by substituting these values (that is, Vq, Vq ′, and ω1) into Expression (4).

  In order to implement the above-described processing, the rectangular wave reference value generation unit 146 receives the high-voltage side voltage VH, the rotation speed ω1, and the generated torque To1. The rectangular wave reference value generation unit 146 calculates a q-axis reference value voltage Vqb, which is a q-axis voltage in a state where no demagnetization occurs, with reference to the map regarding the q-axis voltage Vq using these values. The rectangular wave reference value generation unit 146 outputs the q-axis reference value voltage Vqb to the demagnetization amount calculation unit 131.

  The three-phase / two-phase voltage conversion unit 147 receives the U-phase command voltage Vu *, the V-phase command voltage Vv * and the W-phase command voltage Vw * of the first electric motor 81 and the rotation angle θ1 of the first electric motor 81. The three-phase / two-phase voltage conversion unit 147 is based on the U-phase command voltage Vu *, the V-phase command voltage Vv *, and the W-phase command voltage Vw * by coordinate conversion from three phases to two phases using the rotation angle θ1. q-axis command voltage Vq * is calculated. The three-phase / two-phase voltage conversion unit 147 outputs the q-axis command voltage Vq * to the demagnetization amount calculation unit 131.

  The demagnetization amount calculation unit 131 receives the q-axis reference value voltage Vqb from the rectangular wave reference value generation unit 146, receives the q-axis command voltage Vq * from the three-phase / two-phase voltage conversion unit 147, and receives the q-axis command voltage Vq * from the rotation speed detection unit 115. Receiving the rotational speed ω1. As in the case of PWM control, the demagnetization amount calculation unit 131 sets the first motor 81 permanently based on the deviation (Vq * −Vqb) between the q-axis command voltage Vq * and the q-axis reference value voltage Vqb and the rotational speed ω1. A demagnetization amount Δφ of the magnet (that is, a value corresponding to φ−φ ′ in the equation (4)) is calculated. The demagnetization amount calculation unit 131 outputs the demagnetization amount Δφ to the temperature estimation unit 132.

D-2. Permanent Magnet Temperature Estimation Method The temperature estimation unit 132 receives the demagnetization amount Δφ from the demagnetization amount calculation unit 131 and calculates the permanent magnet temperature Th1 of the first electric motor 81 as in the case of PWM control. . The temperature estimation unit 132 outputs the permanent magnet temperature Th1 to the operation adjustment unit 111.

  By the processing described above, the control device 100 sets a value smaller than the pre-correction command torque T1b as the post-correction command torque T1a when irreversible demagnetization of the permanent magnet of the first electric motor 81 may occur. Furthermore, the control device 100 controls the boost converter 30 and the first inverter 40 so that the torque generated by the first electric motor 81 coincides with the corrected command torque T1a by the rectangular wave control.

<<< Control for Boost Converter and Second Inverter >>>
Similarly to the first motor 81, the control device 100 sets a value smaller than the pre-correction command torque T2b as the post-correction command torque T2a when the irreversible demagnetization of the permanent magnet may occur in the second motor 82. Set. Furthermore, the control device 100 selectively executes the sine wave PWM control, the overmodulation PWM control, and the rectangular wave control so that the generated torque of the second electric motor 82 matches the corrected command torque T2a. 60 is controlled. The control device 100 holds the map shown in FIG. 11 in the ROM. The map shown in FIG. 11 shows the irreversible demagnetization generation region of the second motor 82 for each permanent magnet temperature of the second motor 82 “the combination of rotational speed and torque of the second motor 82 (that is, the second motor 82 Operating point) ”. Data constituting this map is acquired in advance by experiments or the like. Other processes performed by the control device 100 are the same as the processes related to the first electric motor 81, and thus the description thereof is omitted.

  As understood from FIGS. 3 and 4, the region where the temperature of the permanent magnet is most likely to rise is different from the region where the irreversible demagnetization occurs. In other words, the motor is operated so that the operating point of the motor is included in the region where the temperature of the permanent magnet is most likely to rise (as a result, the magnet temperature rises), and then the operating point of the motor is irreversibly demagnetized. Driving the electric motor so as to be included in the region is one of the operation patterns (sequence) in which irreversible demagnetization of the permanent magnet is most likely to occur. The vehicle 10 according to the present embodiment can avoid irreversible demagnetization of the permanent magnet of the electric motor by the torque limit control even when the electric motor is operated in this order.

As described above, the motor control device according to the present embodiment is
A target setting unit (torque setting unit 110) for setting a target torque (command torque T1) that is a target value of torque to be generated by the electric motor (first electric motor 81);
Whether or not irreversible demagnetization of the permanent magnet occurs when the motor generates the target torque, a value (permanent magnet temperature Th1) having a correlation with the temperature of the permanent magnet and the permanent magnet are generated. A value that has a correlation with the intensity of the demagnetizing field that is a magnetic field in the opposite direction to the magnetic field and that is externally applied to the permanent magnet when the motor generates the target torque (the rotational speed ω1 of the first motor and the correction) A pre-command torque T1b) and a determination unit (operation adjustment unit 111 and the like) for determination based on
When it is determined that the irreversible demagnetization occurs, the motor controls the motor to generate a torque lower than the target torque (step 710 in FIG. 7); a torque control unit (operation adjustment unit 111, etc.);
Is provided.

  Further, the torque control unit controls the motor so that the motor generates a torque substantially equal to the target torque when it is determined that the irreversible demagnetization does not occur (step 715 in FIG. 7). It is configured.

  Further, the determination unit determines a value having a correlation with the intensity of the demagnetizing field based on the rotation speed of the motor (rotation speed ω1 of the first motor 81) and the target torque (pre-correction command torque T1b of the first motor 81). Is configured to obtain based on

  Further, the torque control unit (such as the operation adjusting unit 111), when it is determined that the irreversible demagnetization occurs, causes the motor to generate the largest torque within a range where the irreversible demagnetization does not occur. It is configured to control (step 710 in FIG. 7, FIG. 8, etc.).

  Accordingly, the vehicle 10 determines whether or not to perform torque limit control for avoiding irreversible demagnetization of the permanent magnet of the motor in consideration of the permanent magnet temperature and the demagnetizing field strength of the motor. Thereby, the electric motor of vehicle 10 can avoid the situation where an output falls by unnecessary torque limit control.

  As mentioned above, although embodiment of the control apparatus of the electric motor which concerns on this invention was described, this invention is not limited to the said embodiment, A various change is possible unless it deviates from the objective of this invention. For example, the present invention extends to not only a hybrid vehicle including both an internal combustion engine and an electric motor for driving, but also a motor control device mounted on an electric vehicle including only the electric motor.

  In the present embodiment, an IGBT is used as the switching element. However, a MOFFET, a bipolar transistor, or the like may be used instead of the IGBT.

  In the present embodiment, the control device estimates (acquires) the permanent magnet temperature by referring to a map for converting the permanent magnet temperature from the demagnetization factor of the permanent magnet. However, a map for converting the permanent magnet temperature from a combination of the demagnetization factor, the motor control mode, and the motor rotation speed may be prepared, and the control device may estimate the magnet temperature by referring to the map. Furthermore, when a sensor capable of directly measuring the permanent magnet temperature of the electric motor is provided, the permanent magnet temperature may be acquired based on a signal from the sensor.

  In the present embodiment, each control block is realized by a control calculation process according to a predetermined program executed by the control device 100. However, part or all of the control arithmetic processing may be realized by logical arithmetic processing using hardware elements such as an electronic circuit.

  In the present embodiment, the maps for obtaining the permanent magnet temperature Th1 from the demagnetization amount Δφ referred to by the temperature estimation unit 132 are the same in any of the control modes of sine wave PWM control, overmodulation PWM control, and rectangular wave control. Met. However, the temperature estimation unit 132 may hold this map for each control mode. Further, the temperature estimation unit 132 may hold a map for obtaining the permanent magnet temperature Th1 from the demagnetization amount Δφ and the rotation speed ω1 obtained through experiments or the like. In addition, the electric motor may be driven in one or more control modes of sine wave PWM control, overmodulation PWM control, and rectangular wave control.

  DESCRIPTION OF SYMBOLS 10 ... Vehicle, 20 ... Storage battery, 21 ... Voltmeter, 22 ... Voltmeter, 23 ... Ammeter, 24 ... Ammeter, 25 ... Rotation angle sensor, 30 ... Boost converter, 40 ... Inverter, 60 ... Inverter, 81 ... Electric motor DESCRIPTION OF SYMBOLS 82 ... Electric motor 83 ... Internal combustion engine 90 ... Power split mechanism 91 ... Deceleration mechanism 92 ... Axle 93 ... Differential gear 94 ... Drive wheel 100 ... Control device.

Claims (5)

A control device for an electric motor including a permanent magnet,
A target setting unit for setting a target torque, which is a target value of torque to be generated by the electric motor;
Whether or not irreversible demagnetization of the permanent magnet occurs when the motor generates the target torque, a value correlated with the temperature of the permanent magnet, and a magnetic field in a direction opposite to the magnetic field generated by the permanent magnet And a determination unit for determining based on a value having a correlation with the intensity of a demagnetizing field that is a magnetic field applied from the outside to the permanent magnet when the electric motor generates the target torque,
A torque control unit that controls the motor so that the motor generates a torque lower than the target torque when it is determined that the irreversible demagnetization occurs;
An electric motor control device. The motor control device according to claim 1,
The motor control device configured to control the electric motor so that the electric motor generates a torque substantially equal to the target torque when it is determined that the irreversible demagnetization does not occur. In the motor control device according to claim 1 or 2,
The motor control device configured to acquire a value having a correlation with the intensity of the demagnetizing field based on a rotation speed of the motor and the target torque. In the motor control device according to any one of claims 1 to 3,
The torque control unit is configured to control the motor so that the motor generates the largest torque within a range in which the irreversible demagnetization does not occur when it is determined that the irreversible demagnetization occurs. Control device. A vehicle equipped with a motor having a permanent magnet as a drive source,
A target setting unit that sets a target torque, which is a target value of torque to be generated by the electric motor, according to the driving state of the vehicle;
Whether or not irreversible demagnetization of the permanent magnet occurs when the electric motor generates the target torque, a value correlated with the temperature of the permanent magnet, and a magnetic field in a direction opposite to the magnetic field generated by the permanent magnet And a determination unit for determining based on a value having a correlation with the intensity of a demagnetizing field that is a magnetic field applied from the outside to the permanent magnet when the electric motor generates the target torque,
A torque control unit that controls the motor so that the motor generates a torque lower than the target torque when it is determined that the irreversible demagnetization occurs;
A vehicle comprising:

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