JP2019068575A - Inverter control device - Google Patents

Abstract

To provide an inverter control device in which when a fail/safe control is performed by detecting overcurrent, the overcurrent occurrence factor is estimated in consideration of a possibility that one of switching elements of an inverter is in the off failure state.SOLUTION: If an operating point of a rotating electrical machine defined by a relationship between an absolute value of torque and rotational speed is within a range of a specific region and an overcurrent condition (OC) is detected in at least one of an inverter and the rotating electrical machine, retraction control (ZTQ) is executed to reduce at least one of the torque and rotational speed of the rotating electrical machine until the operating point is out of the range of the specific region. If the overcurrent condition (OC) is eliminated by the retraction control, it is determined that an off failure has occurred in one of switching elements constituting the inverter, and if the overcurrent condition (OC) is not eliminated by the retraction control, it is determined that another failure has occurred.SELECTED DRAWING: Figure 8

Description

  The present invention relates to an inverter control device that controls an inverter.

  When an abnormality occurs in the inverter or the rotating electric machine, various fail-safe control is performed. JP-A-2015-211533 exemplifies, for example, short-circuit control of the inverter in order to return current between the inverter and the rotating electric machine when an abnormality occurs in the inverter or the rotating electric machine. Short circuit control is also referred to as active short circuit control. For example, in the case of an inverter that converts power between three phase alternating current and direct current, the upper stage side switching elements of all three phases are turned on to lower stage side of all three phases. It is realized by turning off the switching elements or turning on the lower stage switching elements of all the three phases and turning off the upper stage switching elements of all the three phases.

  Here, when one of the switching elements controlled to be in the on state when active short circuit control is performed causes an off failure that is always fixed in the off state, the balance of the current flowing in each phase is lost. There is a possibility that an excessive current may flow to a healthy switching element which has not failed. Some switching elements are configured as a switching element module provided with an over current detection function and an overheat detection function. If such an excessive current flows, it may be detected as an overcurrent condition or an overheat condition. The detection result is transmitted to a control device that performs switching control of the inverter, and a drive circuit that relays a switching control signal generated by the control device. As a result, the switching element may be forcibly controlled to the off state by various fail-safe functions by the control device and the drive circuit.

  When all the switching elements constituting the inverter are turned off, a charging current flows by a voltage proportional to the rotation of the rotating electrical machine. When the inverter is connected to a DC power supply, an excessive current may flow in the DC power supply or the voltage of the DC power supply may be increased. In addition, when the inverter is not connected to the DC power supply, a capacitor connected between the positive electrode and the negative electrode of the inverter generally for stabilizing the DC voltage is charged, and the voltage between the terminals of the capacitor ( DC link voltage may increase. If the resistance of the DC power supply or the capacitor is increased in preparation for this, the size of the physique increases and the cost increases.

 For example, when occurrence of an overcurrent is detected and fail safe control is performed, if the cause is an off failure, it is not preferable to select active short circuit control as fail safe control as described above. However, it is not always the case that the off failure occurs in all cases where the overcurrent is detected. Therefore, it is preferable that the inverter control device appropriately estimate the cause of the abnormality and select a control method of failsafe control.

Unexamined-Japanese-Patent No. 2015-211533

  Therefore, when performing fail-safe control by detecting the overcurrent, it is desirable to estimate the cause of the overcurrent occurrence, taking into consideration the possibility that one of the switching elements of the inverter is in an off failure state.

The inverter control device in view of the above, as one aspect,
An inverter control apparatus connected to a DC power supply and connected to an AC rotating electric machine to control an inverter for converting power between DC and AC of multiple phases,
The operating point of the rotating electrical machine defined by the relationship between the absolute value of torque and the rotational speed is within the range of a specific region which is a region greater than or equal to the threshold value defined by the relationship; When an overcurrent condition is detected in at least one of
Executing retraction control to reduce at least one of the torque and the rotational speed of the rotating electrical machine until the operating point is out of the range of the specific region;
When the overcurrent state is eliminated by the retraction control, it is determined that an off failure which is always in an off state has occurred in one of the switching elements constituting the inverter,
If the overcurrent state is not eliminated even by the retraction control, it is determined that another failure has occurred.

  The specific region is a region equal to or higher than the threshold value defined by the relationship between the absolute value of torque and the rotational speed, and the value of alternating current increases even when normal control is normally performed. Here, if one switching element has an off failure, the symmetry of the three-phase alternating current is broken. In addition, due to the deviation of the amplitude center, the peak value of any single-phase alternating current may also be larger than when normal control is normally performed. Therefore, the occurrence of the off failure may detect an overcurrent condition. On the other hand, when the operating point is outside the target area, the symmetry of the alternating current is broken, and the amplitude itself of the alternating current is small even if the center of amplitude is shifted, and the value does not become large enough to be detected as an overcurrent. There are many. Therefore, by moving the operating point from the specific region, it can be determined whether the cause of the overcurrent is an off failure. If active short circuit control is executed while one of the switching elements controlled to be in the on state is in the off state, the path through which the return current flows decreases, and the healthy switching element that does not cause the fault is excessive. Current may flow. However, if the cause of the overcurrent is not an off failure, execution of active short circuit control is also possible. As described above, according to this configuration, it is possible to determine whether the cause of the overcurrent is an off failure or not. Therefore, when failsafe control is performed by the detection of the overcurrent, one of the switching elements of the inverter has an off failure. Factor of over current can be estimated in consideration of the possibility of

  Further features and advantages of the inverter control device are apparent from the following description of the embodiments described with reference to the drawings.

A schematic block diagram of a drive device for a vehicle and a drive control device for a vehicle Schematic circuit block diagram of control system of rotating electric machine Schematic circuit block diagram of drive circuit Speed-torque map of rotating electric machine Diagram showing the operating point of the rotating electrical machine in the current vector coordinate system A wave form diagram showing an example of current and torque at the time of normal control in the off failure state A waveform chart showing an example of current and torque at zero torque control in an off failure state Flowchart showing an example of failsafe control including evacuation control Timing chart showing an example of failsafe control including evacuation control Timing chart showing an example of failsafe control including evacuation control

  Hereinafter, an embodiment of an inverter control device will be described based on the drawings. Hereinafter, an example will be exemplified in which a rotating electrical machine is a driving force source of wheels in a vehicle. The schematic block diagram of FIG. 1 shows a vehicle drive control device 1 and a vehicle drive device 7 to be controlled by the vehicle drive control device 1. As shown in FIG. 1, the vehicle drive device 7 is a motive power connecting an input member IN, which is drivingly connected to an internal combustion engine (EG) 70 as a driving force source of the vehicle, and an output member OUT, which is drivingly connected to the wheel W The transmission path is provided with a drive power source engagement device (CL1) 75, a rotary electric machine (MG) 80, and a transmission (TM) 90 from the side of the input member IN.

  Here, “drive connection” refers to a state in which two rotating elements are connected to be able to transmit a driving force. Specifically, “drive connection” refers to a state in which the two rotating elements are connected to rotate integrally, or the two rotating elements are driven via one or more transmission members. It includes the state in which the force can be transmitted. Such a transmission member includes various members that transmit rotation at the same speed or by changing the speed, and includes, for example, a shaft, a gear mechanism, a belt, a chain, and the like. In addition, as such a transmission member, an engagement device that selectively transmits rotation and drive force, such as a friction engagement device or a meshing engagement device may be included.

  The vehicle drive control device 1 controls each part of the above-described vehicle drive device 7. In the present embodiment, the vehicle drive control device 1 includes an inverter control device (INV-CTRL) 20 as a core of control of the rotary electric machine 80 via an inverter (INV) 10 described later, and a core of control of the internal combustion engine 70. The internal combustion engine control unit (EG-CTRL) 30, the transmission control unit (TM-CTRL) 40 serving as the core of the control of the transmission 90, and a travel control unit (generally controlling these control units (20, 30, 40) And DRV-CTRL) 50. In addition, the vehicle is provided with a vehicle control device (VHL-CTRL) 100 that is an upper control device of the vehicle drive control device 1 and controls the entire vehicle.

  As shown in FIG. 1, the vehicle drive device 7 is a so-called parallel type hybrid drive device provided with an internal combustion engine 70 and a rotating electrical machine 80 as a driving force source of the vehicle. The internal combustion engine 70 is a heat engine driven by the combustion of fuel, and for example, a gasoline engine or a diesel engine can be used. The internal combustion engine 70 and the rotary electric machine 80 are drivably connected via the first engagement device 75, and the driving force is transmitted between the internal combustion engine 70 and the rotary electric machine 80 according to the state of the first engagement device 75. It is possible to switch between the state and the state in which the driving force is not transmitted.

  The internal combustion engine 70 can be started by the rotation of the rotary electric machine 80 when the first engagement device 75 is engaged. That is, the internal combustion engine 70 can be started following the rotating electrical machine 80. On the other hand, the internal combustion engine 70 can also be started independently of the rotary electric machine 80. When the first engagement device 75 is in the released state, the internal combustion engine 70 is started by the starter 71. In the present embodiment, a BAS (Belted Alternator Starter) suitable for so-called hot start such as restart from idling stop is illustrated as the starter 71.

  The transmission 90 is a stepped automatic transmission that has a plurality of shift speeds with different transmission ratios. For example, the transmission 90 includes a gear mechanism such as a planetary gear mechanism and a plurality of engagement devices (such as a clutch and a brake) in order to form a plurality of shift speeds. The input shaft of the transmission 90 is drivingly connected to the output shaft (for example, a rotor shaft) of the rotary electric machine 80. Here, a member in which the input shaft of the transmission 90 and the output shaft of the rotary electric machine 80 are drivingly connected is referred to as an intermediate member M. The rotational speed and torque of the internal combustion engine 70 and the rotary electric machine 80 are transmitted to the input shaft of the transmission 90.

  The transmission 90 shifts the rotational speed transmitted to the transmission 90 at the transmission gear ratio of each gear, converts the torque transmitted to the transmission 90, and transmits the converted torque to the output shaft of the transmission 90. The output shaft of the transmission 90 is distributed to two axles via, for example, a differential gear (output differential gear device) or the like, and is transmitted to the wheel W drivingly connected to each axle. Here, the gear ratio is the ratio of the rotational speed of the input shaft to the rotational speed of the output shaft when each gear is formed in the transmission 90 (= rotational speed of the input shaft / rotational speed of the output shaft) . Further, a torque obtained by multiplying the torque transmitted from the input shaft to the transmission 90 by the gear ratio corresponds to the torque transmitted to the output shaft.

  Here, although the form provided with the geared transmission mechanism as the transmission 90 was illustrated, the transmission 90 may be provided with a continuously variable transmission. For example, the transmission 90 may have a continuously variable transmission (CVT) that allows continuous shifting by passing a belt or a chain through two pulleys (pulleys) and changing the diameter of the pulleys. Good.

  Further, the transmission 90 has a function capable of interrupting the power transmission between the output member OUT and the rotary electric machine 80 (or the intermediate member M). In the present embodiment, in order to facilitate understanding, the second engagement device 95 that switches between a state in which the driving force is transmitted and a state in which the driving force is interrupted between the input shaft and the output shaft of the transmission 90 is the inside of the transmission 90 The form provided in FIG. For example, when the transmission 90 is an automatic transmission, the second engagement device 95 may be configured using a planetary gear mechanism. In the planetary gear mechanism, the second engagement device 95 can be configured using one or both of a clutch and a brake. Although the 2nd engagement apparatus 95 is illustrated as a clutch in FIG. 1, the 2nd engagement apparatus 95 may be comprised using not only a clutch but a brake.

  In FIG. 1, reference numeral 73 denotes a rotation sensor that detects the rotational speed of the internal combustion engine 70 or the input member IN, and reference numeral 93 denotes a rotation sensor that detects the rotational speed of the wheel W or the output member OUT. Further, although details will be described later, reference numeral 13 is a rotation sensor such as a resolver for detecting rotation (speed, direction, angular velocity, etc.) of the rotor of the rotating electrical machine 80, and reference numeral 12 is a current flowing through the rotating electrical machine 80 It is an alternating current sensor. In FIG. 1, various oil pumps (electric and mechanical) and the like are omitted.

  As described above, the rotary electric machine 80 is driven and controlled by the inverter control device 20 via the inverter 10. The block diagram of FIG. 2 schematically shows the rotating electrical machine drive device 2. Reference numeral 14 denotes a voltage sensor for detecting a voltage on the DC side of the inverter 10 (DC link voltage Vdc described later), and reference numeral 15 denotes a current (battery current) flowing to a high voltage battery 11 (DC power supply) described later. It is a battery current sensor.

  The inverter 10 is connected to the high voltage battery 11 via a contactor 9 to be described later, and is connected to an AC rotating electric machine 80 to perform power conversion between DC and multiple phases of AC (here, three-phase AC). . The rotating electrical machine 80 as a driving force source of the vehicle is a rotating electrical machine operating with a plurality of phases of alternating current (here, three-phase alternating current), and can function as a motor or a generator. That is, the rotary electric machine 80 converts the power from the high voltage battery 11 into motive power via the inverter 10 (powering). Alternatively, the rotating electrical machine 80 converts the rotational driving force transmitted from the internal combustion engine 70 or the wheel W into electric power, and charges the high voltage battery 11 via the inverter 10 (regeneration).

  The high voltage battery 11 as a power source for driving the rotating electrical machine 80 is configured of, for example, a secondary battery (battery) such as a nickel hydrogen battery or a lithium ion battery, an electric double layer capacitor, or the like. The high voltage battery 11 is a large voltage, large capacity DC power supply to supply power to the rotating electrical machine 80. The rated power supply voltage of the high voltage battery 11 is, for example, 200 to 400 [V].

  On the DC side of the inverter 10, a smoothing capacitor (DC link capacitor 4) for smoothing the voltage (DC link voltage Vdc) between the positive electrode and the negative electrode is provided. The DC link capacitor 4 stabilizes the DC link voltage Vdc which fluctuates according to the fluctuation of the power consumption of the rotary electric machine 80.

  As shown in FIG. 2, the contactor 9 is disposed between the high voltage battery 11 and the inverter 10, specifically, between the DC link capacitor 4 and the high voltage battery 11. The contactor 9 can disconnect the electrical connection between the rotating electrical machine drive device 2 and the high voltage battery 11. In the connected state (closed state) of the contactor 9, the high voltage battery 11 and the inverter 10 (and the rotating electrical machine 80) are electrically connected, and in the open state (opened state) of the contactor 9, the high voltage battery 11 and the inverter 10 (and the rotating electrical machine Electrical connection with 80) is cut off.

  In the present embodiment, as shown in FIG. 1, an air conditioner 61 for adjusting the temperature and humidity of the vehicle compartment, an electric oil pump (not shown), etc. are driven between the high voltage battery 11 and the inverter 10. The auxiliary device 60 such as a DC / DC converter (DC / DC) 62 that converts a DC voltage to V may be provided. The accessory 60 is preferably disposed between the contactor 9 and the DC link capacitor 4.

  In the present embodiment, the contactor 9 is a mechanical relay that opens and closes based on a command from the vehicle control device 100 as a vehicle electrical control unit (vehicle ECU (Electronic Control Unit)) which is one of the top control devices of the vehicle. For example, it is called a system main relay (SMR: System Main Relay) or a main contactor (MC: Main Contactor). When the ignition switch or main switch of the vehicle is in the on state (effective state), the contactor 9 is in the conductive state (connected state) by closing the contact, and when the ignition switch or the main switch is in the off state (ineffective state) Opens and becomes non-conductive (open).

  As described above, the inverter 10 converts DC power having the DC link voltage Vdc into AC power of multiple phases (n is a natural number, n phases, three phases here) and supplies the AC power to the rotating electrical machine 80. The AC power generated by 80 is converted to DC power and supplied to the DC power supply. The inverter 10 is configured to have a plurality of switching elements 3. The switching element 3 may be an IGBT (Insulated Gate Bipolar Transistor), a power MOSFET (Metal Oxide Semiconductor Field Effect Transistor), a SiC-MOSFET (Silicon Carbide-Metal Oxide Semiconductor FET), a SiC-SIT (SiC-Static Induction Transistor), or GaN. It is preferable to apply a power semiconductor device capable of operating at high frequency, such as MOSFET (Gallium Nitride). In FIG. 2, an embodiment in which an IGBT is used as the switching element 3 is illustrated.

  As shown in FIG. 2, the inverter 10 is configured by a bridge circuit having a number of arms 3A corresponding to each of a plurality of phases (here, three phases). That is, as shown in FIG. 1, two switching elements 3 (upper stage switching element 31 and lower stage switching element 32) are connected in series between the DC positive electrode side and the DC negative electrode side of the inverter 10 to form one arm 3A is configured. In the case of three-phase alternating current, this series circuit (one arm 3A) is connected in parallel in three circuits (three phases). That is, one series circuit (arm 3A) corresponds to each of stator coils 8 corresponding to the U-phase, V-phase, and W-phase of rotary electric machine 80. The respective switching elements 3 are provided with free wheel diodes 5 in parallel, with the direction from the negative electrode to the positive electrode (the direction from the lower side to the upper side) as a forward direction.

  In the present embodiment, as shown in FIG. 3, the power module 30 is configured by including at least one IGBT (switching element 3) and the free wheeling diode 5 connected in parallel to the IGBT. Such a power module 30 may have a function of detecting the current flowing through the switching element 3 and a function of detecting the temperature of the switching element 3. Such a function may output a detected value as a signal, or may output a notification signal when a predetermined threshold value is exceeded. In the present embodiment, as illustrated in FIG. 3, the temperature detection signal SC and the temperature detection signal TJ are output from the power module 30.

  As shown in FIGS. 1 and 2, the inverter 10 is controlled by an inverter control device 20. The inverter control device 20 is constructed using a logic circuit such as a microcomputer as a core member. For example, the inverter control device 20 performs current feedback control using a vector control method based on the target torque of the rotating electrical machine 80 provided by another control device or the like such as the vehicle control device 100 and the like. Control the rotary electric machine 80.

  The actual current (Iu, Iv, Iw: see FIG. 6 etc.) flowing through the stator coil 8 of each phase of the rotary electric machine 80 is detected by the alternating current sensor 12, and the inverter control device 20 acquires the detection result. In addition, the magnetic pole position at each point of time of the rotor of the rotating electrical machine 80 is detected by the rotation sensor 13 such as a resolver, and the inverter control device 20 acquires the detection result. The inverter control device 20 performs current feedback control using the detection results of the alternating current sensor 12 and the rotation sensor 13. The inverter controller 20 is configured to have various functional units for current feedback control, and each functional unit is realized by cooperation of hardware such as a microcomputer and software (program). .

  The power supply voltage of the vehicle control device 100, the inverter control device 20, etc. is, for example, 5 [V] or 3.3 [V]. In the vehicle, in addition to the high voltage battery 11, a low voltage battery (not shown) which is insulated from the high voltage battery 11 and which is a power supply having a voltage lower than that of the high voltage battery 11 is mounted. The power supply voltage of the low voltage battery is, for example, 12 to 24 [V]. The low voltage battery supplies power to the inverter control device 20 and the vehicle control device 100 via, for example, a regulator circuit that adjusts a voltage. The power supply voltage of the vehicle control device 100, the inverter control device 20, etc. is, for example, 5 [V] or 3.3 [V].

  As shown in FIG. 1, the control terminal (gate terminal in the case of IGBT or FET) of each switching element 3 constituting the inverter 10 is connected to the inverter control device 20 via the drive circuit 21 and individually individually. Switching control is performed. The high-voltage system circuit for driving the rotating electrical machine 80 and the low-voltage system circuit such as the inverter control device 20 having a microcomputer or the like as its core have greatly different operating voltages (power supply voltages of the circuits). For this reason, the drive circuit 21 (DRV-CCT) which relays the drive capability (switching control signal) to each switching element 3 by increasing the drive capability (for example, the capability to operate the circuit of the latter stage, such as voltage amplitude and output current) is relayed. It is equipped.

  FIG. 3 shows an example of the drive circuit 21. The drive circuit 21 is configured using, for example, a circuit using an insulating element such as a photocoupler, a magnetic coupler, or a transformer, or a driver IC incorporating such an element. In FIG. 3, a low voltage side drive circuit 23 connected to the so-called low voltage circuit side of the inverter control device 20 and a high voltage side drive circuit 24 connected to the so-called high voltage circuit side of the power module 30 are shown. And the driver IC 22 provided with The low voltage side drive circuit 23 and the high voltage side drive circuit 24 are isolated. For example, the low voltage side drive circuit 23 operates with a control circuit power supply V5 having a voltage of about 3.3 to 5 [V], and the high voltage side drive circuit 24 operates with a drive power supply V15 having a voltage of about 15 to 20 [V] Do.

  The inverter controller 20 also operates with the control circuit power supply V5. The switching control signal SW generated and output by the inverter control device 20 is input to the low voltage side drive circuit 23 through a buffer for enhancing output current, impedance conversion, etc., and through the high voltage side drive circuit 24. The gate signal GS is provided to each power module 30 (switching element 3). The drive circuit 21 also relays the temperature detection signal SC and the temperature detection signal TJ output from the power module 30 and provides the inverter control device 20 contrary to the switching control signal SW. The drive circuit 21 itself also has an abnormality detection function such as monitoring of the voltage of the drive power supply V15. In the present embodiment, an example is given in which the warning signal ALM is output to the inverter control device 20 when the temperature detection signal SC or the temperature detection signal TJ indicates an abnormality or when the drive circuit 21 detects an abnormality. ing.

  In the inverter controller 20, for example, when the voltage sensor 14 for detecting the DC link voltage Vdc detects an overvoltage, or when the battery current sensor 15 for detecting a current input to or output from the high voltage battery detects an overcurrent. It is preferable that the configuration is such that an abnormal signal is also input. FIG. 3 exemplifies a mode in which the over-voltage detection signal OV output when the voltage sensor 14 detects an over-voltage is provided to the inverter control device 20. In the present embodiment, the overvoltage detection signal OV is a negative logic signal, and the logic level in the normal state is high. The overvoltage detection signal OV is also connected to a control terminal of a tri-state buffer that relays the switching control signal SW to the low voltage side drive circuit 23. In the present embodiment, when an overvoltage occurs, the logic level of the overvoltage detection signal OV is in the low state, and the switching control signal SW can be interrupted to turn off all the switching elements 3 of the inverter 10 There is. In addition, illustration of pull-up resistance or pull-down resistance for determining the logic level of the signal input to the low voltage side drive circuit 23 at the time of cutoff is omitted.

  In addition, the drive circuit 21 has an enable terminal EN (negative logic), and switches off the switching control signal SW when the signal input to the enable terminal EN is not valid (when it is high level), A low level gate signal GS is output. In the present embodiment, the mode in which the enable terminal EN is fixed to the low level is exemplified, but in order to quickly invalidate the gate signal GS, a signal indicating a failure or abnormality may be connected. In addition, the drive circuit 21 outputs the warning signal ALM, or when the temperature detection signal SC or the temperature detection signal TJ is input in a state showing an abnormality, etc., regardless of the state of the switching control signal SW. Alternatively, the gate signal GS may be output at a low level.

  The inverter control device 20 uses, for example, pulse width modulation (PWM) control and rectangular wave control (one pulse control) as a form (a form of voltage waveform control) of a switching pattern of the switching element 3 constituting the inverter 10. There are two control forms of In addition, as a form of field control of the stator, the inverter control device 20 performs normal field control such as maximum torque control that outputs maximum torque with respect to motor current, maximum efficiency control that drives the motor with maximum efficiency with respect to motor current, And, field adjustment control such as field weakening control which weakens field magnetic flux by flowing field current (d axis current Id) which does not contribute to torque, and field adjustment control such as strong field control which strengthens field magnetic flux conversely. The pulse width modulation, the rectangular wave control (one pulse control), the normal field control, the field weakening control, the strong field control and the like are known and thus the detailed description is omitted.

As described above, in the present embodiment, the current feedback control using the current vector control method in the two-axis orthogonal vector space (orthogonal vector coordinate system) that rotates in synchronization with the rotation of the rotating electrical machine 80 is performed to Control 80 In the current vector control method, for example, the d-axis (field current axis, field axis) along the direction of the field magnetic flux by the permanent magnet and the q-axis (.pi. / 2 electrically advanced with respect to the d-axis) The current feedback control is performed in the orthogonal vector coordinate system (dq axis vector coordinate system) of two axes with the drive current axis and the drive axis. Inverter control device 20 determines torque command T ^* based on the target torque of rotary electric machine 80 to be controlled, and determines d-axis current command Id ^* and q-axis current command Iq ^* .

Inverter control device 20 calculates the deviation between the current command (Id ^* , Iq ^* ) and the actual current (Iu, Iv, Iw) flowing through the U-phase, V-phase, and W-phase coils of rotary electric machine 80. Then, proportional integral control calculation (PI control calculation) or proportional integral derivative control calculation (PID control calculation) is performed to finally determine three phase voltage commands. A switching control signal is generated based on this voltage command. Mutual coordinate conversion between the actual three-phase coordinate system of the rotary electric machine 80 and the orthogonal vector coordinate system of two axes is performed based on the magnetic pole position θ detected by the rotation sensor 13. Further, the rotation speed ω (angular velocity or rpm (Revolutions per Minute)) of the rotary electric machine 80 is derived from the detection result of the rotation sensor 13.

The field adjustment control will be briefly described below. Control based on basic current command values (d-axis current command Id ^* , q-axis current command Iq ^* ) set based on the target torque of the rotating electrical machine 80 for normal field control such as maximum torque control and maximum efficiency control It is a form. On the other hand, field weakening control is a control mode in which the d-axis current command Id ^* in the basic current command value is adjusted to weaken the field magnetic flux from the stator. The field strengthening control is a control mode in which the d-axis current command Id ^* in the basic current command value is adjusted in order to strengthen the field magnetic flux from the stator. While the d-axis current Id is adjusted in this manner during field weakening control or field strengthening control, etc., it is also possible to adjust the q-axis current Iq. For example, when the inverter 10 is stopped, the q-axis current Iq can be decreased to quickly reduce the torque of the rotating electrical machine 80. Similarly, when stopping the inverter 10, the d-axis current Id and the q-axis current Iq are adjusted to increase the torque in order to rapidly reduce the energy charged in the DC link capacitor 4. It is also possible to intentionally increase the loss by increasing the armature current (the current corresponding to the vector sum of the d-axis current Id and the q-axis current Iq) without (or reducing the torque).

  As described above, when various abnormalities such as the inverter 10 are detected, the vehicle drive control device 1 including the inverter control device 20 executes so-called failsafe control. The vehicle drive control device 1 changes the transmission state of the driving force by the first engagement device 75 or the second engagement device 95 as fail safe control, or changes the control method of the switching element 3 of the inverter 10 Do. Here, failsafe control in which the inverter control device 20 changes the control method of the switching element 3 of the inverter 10 will be described.

  For example, shutdown control (SDN) is known as fail-safe control in which the inverter 10 is controlled. The shutdown control is control for changing the switching control signals SW to all the switching elements 3 constituting the inverter 10 into the inactive state to turn the inverter 10 into the off state. At this time, when the rotor of the rotary electric machine 80 continues rotating at a relatively high speed due to inertia, a large counter electromotive force is generated. The power generated by the rotation of the rotor is rectified via the freewheeling diode 5 and charges the high voltage battery 11 when the contactor 9 is closed. If the absolute value of the current (battery current) charging the high voltage battery 11 largely increases and the battery current exceeds the rated current of the high voltage battery 11, the high voltage battery 11 may be consumed. Increasing the rated value of the high voltage battery 11 so as to withstand a large battery current may lead to an increase in scale and cost.

  On the other hand, when the contactor 9 is in the open state, the inflow of current to the high voltage battery 11 is cut off. The current cut off from flowing into the high voltage battery 11 charges the DC link capacitor 4 and raises the DC link voltage Vdc. It is not preferable that the DC link voltage Vdc exceeds the rated voltage (absolute maximum rating) of the inverter 10 (switching element 3) or the DC link capacitor 4. Increasing these ratings to allow higher voltages can result in increased size and cost. Further, as shown in FIG. 1, when the DC link voltage Vdc is also applied to the accessory 60 such as the air conditioner 61 and the DC / DC converter 62, the same applies to the accessory 60 as well. I can say that.

  In addition to shutdown control, active short circuit control (ASC) is also known as fail-safe control for controlling the inverter 10. With active short circuit control, either one of the upper side switching elements 31 of the arms 3A of multiple phases or the lower side switching elements 32 of all arms of the multiple phases is turned on and the other side is turned off. The control is to return the current between the inverter 80 and the inverter 10. The case where the upper stage switching elements 31 of all the multiple phase arms 3A are turned on and the lower stage switching elements 32 of all the multiple phase arms 3A are turned off is referred to as upper stage active short circuit control (HASC). Further, the case where the lower switching devices 32 of all the multiple phase arms 3A are turned on and the upper switching devices 31 of all the multiple arms 3A are turned off is referred to as lower active short circuit control (LASC).

  The active short circuit control does not involve a sharp rise of the DC link voltage Vdc or a sharp increase of the charging current of the high voltage battery 11. However, when the short circuit current of the rotary electric machine 80 is large, a large return current flows in the stator coil 8 and the inverter 10. If a large current continues to flow for a long time, the inverter 10 or the rotating electrical machine 80 may be consumed due to heat generation or the like due to a large current.

  Therefore, it is preferable that the fail-safe control is appropriately performed based on the conditions of the inverter 10 and the vehicle drive device 7 including the rotating electrical machine 80 when an abnormality occurs, the characteristics of the respective control methods, and the like. FIG. 4 shows a speed-torque map of the rotating electrical machine. For example, when the rotation speed ω of the rotary electric machine 80 is equal to or higher than a predetermined specified rotation speed ω1, the inverter control device 20 executes active short circuit control and is less than the specified rotation speed ω1 (first specified speed). In this case, the shutdown control is performed in which all the switching elements 3 of the inverter 10 are all turned off.

  Note that “A1”, “A2”, and “A3” in FIG. 4 respectively indicate operation regions to which a method of detecting an off failure described later is applied. The first operation area A1 in which the absolute value of the torque and the rotational speed ω are low is an area where the off failure detection is not performed. The second operation area A2 in which the absolute value of the torque and the rotational speed ω are high is an area in which the off failure is detected by the overcurrent detection (described later with reference to FIG. 6, FIG. 7 and the like). In the second operation area A2, the rotational speed ω is set in an area higher than the second specified speed ω2. The third operation area A3 is an area in which the off failure is detected by the alternating current (Iu, Iv, Iw) (due to the mutual relationship of the three phase currents). In the present embodiment, the maximum rotation speed in the first operation area A1 and the specified rotation speed ω1 are exemplified to be the same speed, but the maximum rotation speed and the specified rotation speed ω1 in the first operation area A1 are illustrated. And may have different rotational speeds.

  The shutdown control described above is also active as fail-safe control when the rotation state of the rotary electric machine 80 or the state of the inverter 10, for example, when the rotational speed ω of the rotary electric machine 80 is high and the switching element 3 of the inverter 10 is abnormal. In some cases, short circuit control can not be selected. In such a case, torque reduction control for reducing the torque of the rotary electric machine 80 is also one of failsafe control. The torque reduction control is control that reduces the torque of the rotating electrical machine 80 while continuing torque control that controls the rotating electrical machine 80 based on the target torque or rotational speed control that controls the rotating electrical machine 80 based on the target speed.

  Here, zero torque control as an example of such control will be described. FIG. 5 schematically shows the operating point (P1 etc.) of the rotary electric machine 80 in the current vector space (current vector coordinate system). In FIG. 5, reference numerals “200” (201 to 203) are equal torque lines each showing a vector locus of an armature current at which the rotary electric machine 80 outputs a certain torque. The second equal torque line 202 has a lower torque than the first equal torque line 201, and the third equal torque line 203 has a lower torque than the second equal torque line 202.

Curve "300" indicates a voltage velocity ellipse (voltage limited ellipse). When the back electromotive force of the rotating electrical machine 80 exceeds the DC link voltage Vdc, the rotating electrical machine 80 can not be controlled, and thus the settable current command range is the armature current (d-axis current Id and q-axis current Iq Is limited by the voltage velocity ellipse 300, which is a vector locus of In other words, the voltage-velocity ellipse can be set according to the value of the DC voltage (DC link voltage Vdc) of the inverter 10 and the rotation speed ω of the rotary electric machine 80 that affects the magnitude of the back electromotive voltage. It is a vector locus which shows a range. That is, the size of the voltage velocity ellipse 300 is determined based on the DC link voltage Vdc and the rotation speed ω of the rotating electrical machine 80. Specifically, the diameter of the voltage velocity ellipse 300 is proportional to the DC link voltage Vdc and inversely proportional to the rotational velocity ω of the rotary electric machine 80. The current command (Id ^* , Iq ^* ) is set as a value at an operating point on a line of equal torque line 200 present in voltage velocity ellipse 300 in such a current vector coordinate system.

  When the inverter control device 20 determines that the execution of fail safe control (zero torque control) is necessary, the inverter control device 20 performs, for example, the rotating electric machine 80 in a torque mode as a normal operation (for example, pulse width modulation control according to target torque) Control. The first operating point P1 shown in FIG. 5 indicates the operating point of the rotary electric machine 80 in the current vector coordinate system at this time. In other words, at the first operating point P1 on the third equal torque line 203, the rotary electric machine 80 performs the regenerative operation in the torque mode as a normal operation. Here, for convenience, the form in which the rotating electrical machine 80 performs the regenerative operation is illustrated, but, for example, the rotating electrical machine 80 performing the powering operation at the second operating point P2 indicated by the open white circle You may think that it moved to

When executing the zero torque control, inverter control device 20 sets torque command T ^* so that the torque of rotary electric machine 80 becomes zero, and reduces q-axis current Iq (drive current) to the zero state. At this time, the q-axis current Iq is decreased, and the d-axis current Id (field current) is increased so that the armature current increases while maintaining the torque (= zero) based on the torque command T ^*. It is also good. The inverter control device 20 controls the operating point to move to the origin (P 0) when the origin is included in the range of the voltage velocity ellipse 300 as in the first voltage velocity ellipse 301. Further, when the inverter controller 20 does not include the origin within the range of the voltage velocity ellipse 300 as in the second voltage velocity ellipse 302, the third voltage velocity ellipse 303, and the fourth voltage velocity ellipse 304, the voltage velocity ellipse Control is performed so that the operating point moves to the intersection point (P300) of 300 and the d axis.

  For example, when the contactor 9 is open, the DC link capacitor 4 can release the charge by flowing more armature current than the regenerative current. At this time, it is also preferable to increase the loss by continuing to flow more without reducing the amount of current, particularly for the d-axis current Id that does not contribute to torque. For example, the d-axis current Id may be increased while decreasing the q-axis current Iq from the first operating point P1 to make the torque approach zero. The locus of the operating point is preferably set based on the coordinates of the operating point, the decreasing speed of the q-axis current Iq, and the increasing speed of the d-axis current Id, with priority given to the decrease of the q-axis current Iq.

  In the above, although the form which performs zero torque control (torque reduction control) was illustrated, you may perform deceleration control which outputs the torque of the reverse direction to the rotation direction of the rotary electric machine 80. FIG. For example, the q-axis current Iq may be changed from the second operating point P2 to the first operating point P1 without changing the d-axis current Id within a range not exceeding the voltage velocity ellipse 300.

  As described above, when there is an abnormality such as an off failure in which the switching element 3 is always fixed in the off state, one of the switching elements 3 of the inverter 10 may not be able to execute active short circuit control. That is, when an off failure occurs in one of the switching elements 3 controlled to be in the on state when active short circuit control is executed, each phase will be described later with reference to FIG. 6, FIG. There is a possibility that the balance of the current flowing through the current flow is broken, and an excessive current may flow to the sound switching element 3 which has not failed. As described above, the switching element 3 may be configured as the power module 30 provided with the overcurrent detection function and the overheat detection function. When an excessive current flows, it is detected that an overcurrent condition or an overheat condition is present, and the switching element 3 is forced by various fail-safe functions by the inverter control device 20 and the drive circuit 21 as described above. May be controlled to the off state. As a result, even if active short circuit control is performed, if it becomes equivalent to the state where shutdown control is performed, there is a possibility of causing a rapid rise of the DC link voltage Vdc and a sharp increase of the battery current.

  Therefore, in the present embodiment, the inverter control device 20 also takes into consideration the possibility of an off failure (single phase off failure) in which one of the switching elements 3 constituting the inverter 10 is always in the off state. Execute failsafe control. When the operating point of rotating electric machine 80 is within the range of the second operation area A2 (specific area) and it is detected that at least one of inverter 10 and rotating electric machine 80 is in the overcurrent state In order to estimate the cause of the abnormality, retraction control is performed to reduce at least one of the torque and the rotational speed of the rotating electrical machine until the operating point is out of the range of the second operating area A2. Then, the inverter control device 20 executes fail-safe control with a different control method depending on whether the cause of the abnormality is an off failure.

  The second operation area A2 shown in FIG. 4 is a specific area equal to or greater than a threshold value defined by the relationship between the absolute value of torque and the rotational speed ω. In other words, threshold values of torque in both positive and negative directions are defined according to the rotational speed ω, and the second operation area A2 is an area where the torque is larger than the threshold value of positive torque at each rotational speed ω, It includes both the region where the torque is smaller (the absolute value is larger) than the negative torque threshold at each rotational speed ω. In the second operation area A2, the value of the alternating current increases even when the normal torque control is normally performed. In FIG. 4, the threshold value that defines the second operation area A2 is indicated by a broken line. Note that, as is clear from FIG. 4, in the present embodiment, the second operation area A2 is not set in the area where the rotational speed ω is equal to or less than the predetermined value (the second prescribed speed ω2). The waveform diagram of FIG. 6 shows the current and torque during a period in which normal torque control is normally executed on the left side relatively, and always off in one of the switching elements 3 constituting the inverter 10 on the right side. It shows the current and torque when there is an off-state failure. As shown in FIG. 6, when one switching element 3 has an off failure, the symmetry of the three-phase alternating current (Iu, Iv, Iw) is broken. In addition, due to deviation of the amplitude center or the like, the peak value of any single-phase alternating current may also be larger than when normal torque control is normally performed.

  As described above, in the second operation area A2, since the value of the alternating current is larger than that in the other operation areas, the peak value may exceed the predetermined current Ith defined in advance. When the off failure has occurred, it is not preferable to select the active short circuit control as the failsafe control as described above. However, the off failure does not necessarily occur in all cases where the overcurrent is detected. Therefore, when inverter control device 20 executes fail-safe control in response to detection of an overcurrent, a factor of the occurrence of overcurrent is taken into consideration, taking into consideration the possibility that one of switching elements 3 of inverter 10 is turned off. It is preferable to estimate Therefore, the inverter control device 20 executes retraction control to reduce at least one of the torque and the rotational speed ω of the rotating electrical machine 80 until the operating point is out of the range of the second operation area A2 which is the specific area.

  When the operating point of rotary electric machine 80 becomes an area other than the second operation area A2 due to the evacuation control and the overcurrent state is eliminated, the inverter control device 20 determines that the off failure has occurred, and the evacuation control is performed. If the overcurrent state is not eliminated even by the above, it is determined that another failure has occurred. Based on the determination result, inverter control device 20 executes appropriate fail-safe control according to each failure.

  Hereinafter, with reference to FIGS. 7 to 10, an embodiment of failsafe control including evacuation control will be described. The waveform diagram of FIG. 7 shows an example of current and torque when torque reduction control (zero torque control) is performed as retraction control in the off failure state. The flowchart of FIG. 8 illustrates an example of failsafe control including evacuation control. The timing charts of FIG. 9 and FIG. 10 show an example of failsafe control including evacuation control.

  As shown in FIG. 8, when it is determined that the inverter 10 or the rotating electrical machine 80 has some sort of abnormality, the inverter control device 20 first acquires an error flag (ERR_FLG) (# 1). Next, it is determined whether this error flag indicates an over current (OC: Over Current) (# 2). If the error flag does not indicate an overcurrent, the process ends. If the error flag indicates an overcurrent, the values of the rotational speed ω of the rotary electric machine 80 and the DC link voltage Vdc are acquired (# 3).

  Subsequently, inverter control device 20 calculates counter electromotive voltage Vbemf based on rotational speed ω (# 4). Specifically, the counter electromotive voltage Vbemf is calculated based on the electromagnetic specification (the number of turns of the stator coil 8, the magnetic flux of the permanent magnet of the rotor, the number of magnetic poles, etc.) of the rotary electric machine 80 and the rotational speed ω as a variable. . When shut-down control is executed when the back electromotive force Vbemf is larger than the DC link voltage Vdc, regenerative current flows to charge the DC link capacitor 4 to raise the DC link voltage Vdc, or the high voltage battery 11 is Large battery current may flow. At step # 5 following step # 4, it is determined whether or not the back electromotive voltage Vbemf is a voltage that can be shut down. The shutdown possibility determination threshold THsdn, which is the determination threshold, can be set, for example, by reference to a map based on the DC link voltage Vdc. For example, the value defining the first operation area A1 shown in FIG. 4 also corresponds to the shutdown availability determination threshold THsdn.

  If the back electromotive force Vbemf is less than the shutdown possibility determination threshold THsdn, shutdown control can be performed. For example, if the operating point of the rotating electrical machine 80 is in the range below the prescribed rotational speed ω1 shown in FIG. 4, it is possible to select the shutdown control as described above. Therefore, the inverter control device 20 sets the control mode (CTRL_MOD) to shutdown (SDN) and ends the process (# 6).

  On the other hand, when the back electromotive voltage Vbemf is equal to or higher than the shutdown possibility determination threshold THsdn, the control mode is set to torque reduction control (PDN) (# 7). Preferably, zero torque control (ZTQ) is performed as torque reduction control. For example, the inverter control device 20 executes the shutdown control when the rotational speed is less than the predetermined rotational speed ω1 shown in FIG. 4 and performs the torque reduction control (zero torque control) when the rotational speed is the predetermined rotational speed ω1 or more. Here, the torque reduction control is control for reducing the torque of the rotating electrical machine 80. In the present embodiment, when the operating point of the rotary electric machine 80 is within the range of the second operating area A2 (specific area), it is detected that the overcurrent state is present. 2 Move out of the range of the operation area A2. Although torque reduction control is illustrated here, deceleration control may be executed to output a torque in a direction opposite to the rotation direction of the rotary electric machine 80.

  The waveform diagram of FIG. 7 shows an example of the current and torque at the time of zero torque control in the off failure state, but the left side shows the normal torque control period Tt before starting the zero torque control as in the right side of FIG. The waveform is shown, and the center shows the waveform of the zero torque control period Tzt after the start of the zero torque control. As apparent from FIG. 7, the current and torque are greatly reduced. The waveform on the right side of FIG. 7 is an enlarged view of the waveform in the zero torque control period Tzt. As described above, in the present embodiment, the operating point when the overcurrent state is detected is included in the second operating area A2. However, for example, when the torque is reduced by the retraction control, the operating point moves to the outside of the second operation area A2, for example, to the third operation area A3.

  By the way, in the present embodiment, when the control mode is set to the torque reduction control at step # 7, the inverter control device 20 next requests the transmission control device 40 to put the second engagement device CL2 in the released state. Do it (# 8). For example, a release request (CL_OPEN_REQ) of the second engagement device CL2 is transmitted. When the wheel W is rotating in a state in which the rotary electric machine 80 is drivingly connected to the wheel W, the rotary electric machine 80 also continues to rotate, and the generation of the back electromotive force may not be reduced. Further, in the state where the switching element 3 is in the OFF failure state, as shown in FIG. 6 etc., pulsation may occur in the alternating current (Iu, Iv, Iw) and pulsation may also occur in the torque of the rotating electrical machine 80 is there. When the rotary electric machine 80 is drivingly connected to the wheel W, the pulsation may be transmitted to the wheel W to affect the ride quality of the vehicle. Therefore, when performing fail-safe control such as zero torque control or deceleration control, it is preferable that power transmission between the rotating electrical machine 80 and the wheel W be cut off.

  However, since the zero torque control (torque reduction control) is control for reducing the torque of the rotary electric machine 80, as shown in FIG. 7, the absolute value of the torque decreases. Therefore, even if pulsation occurs in the torque, its amplitude decreases. Therefore, for example, even if the rotary electric machine 80 is drivingly connected to the wheel W without executing step # 8, the pulsation of the rotary electric machine 80 transmitted to the wheel W is also small, and the influence is minor. Therefore, if the control mode is set to torque reduction control (zero torque control) in step # 7, step # 8 may not be performed.

  On the other hand, since the torque for decelerating the rotary electric machine 80 is output in the deceleration control, the torque is larger than that in the torque reduction control, and the pulsation tends to be larger accordingly. For this reason, when the rotary electric machine 80 is drivingly connected to the wheel W, the pulsation of the torque of the rotary electric machine 80 is easily transmitted to the wheel W as compared with the torque reduction control. Therefore, when the control mode is set to the deceleration control in step # 7, it is preferable to execute step # 8. In other words, the deceleration control is preferably selected in a situation where execution of step # 8 is possible (the second engagement device CL2 can be released). That is, inverter control device 20 performs zero torque control (torque reduction control) or deceleration control when second engagement device 95 is in the released state, and when second engagement device 95 is in the engaged state. It is preferable to execute torque reduction control.

  The torque in the deceleration control can be output in the range in which the current flowing through the switching elements 3 other than the switching element 3 having an off failure does not exceed the allowable current (for example, the specified current Ith) allowed for each switching element 3 Preferably it is torque. If a large torque is output, it is possible to quickly reduce the rotational speed ω of the rotary electric machine 80, but it is not preferable that a large current flows.

  As described above, the inverter control device 20 drives and controls the rotating electrical machine 80 by current feedback control based on the deviation between the command value of the alternating current and the actual current value. The actual current value is detected by the alternating current sensor 12. In order to perform feedback control with high precision, an appropriate dynamic range (detection range) corresponding to the resolution is set in the alternating current sensor 12. The alternating current in fail-safe control such as deceleration control has a larger amplitude than the alternating current at the time of feedback control of the normal rotating electrical machine 80. If the detection range of the alternating current sensor 12 is set according to the amplitude at the time of fail-safe control, the accuracy of the current feedback control is reduced. In deceleration control, in order to reduce torque quickly, it is possible to control so that an alternating current larger than normal flows, but when it exceeds the dynamic range of the alternating current sensor 12, controllability decreases Resulting in. Therefore, it is preferable that the inverter control device 20 execute the deceleration control with the torque that can be output in the range in which the value of the alternating current does not exceed the detectable range of the alternating current sensor 12.

  As described above, after executing the evacuation control centering on Step # 7 as described above, the inverter control device 20 acquires the error flag again (# 9), and determines whether the error flag indicates an overcurrent or not. (# 10). If the error flag does not indicate an overcurrent, it means that the overcurrent state has been eliminated by the evacuation control. That is, it is determined that the possibility of the occurrence of the off failure in one of the switching elements 3 constituting the inverter 10 is high because the overcurrent state is eliminated by the retraction from the second operation region A2. End the process. On the other hand, when the error flag still indicates the over current, the over current state is not eliminated even by the evacuation control, so that it is determined that the possibility that another failure has occurred is high. When an overcurrent state is generated due to an abnormality other than an off failure, there is little possibility that an excessive current flows in some of the switching elements 3 by performing the active short circuit control. Therefore, inverter control device 20 sets the control mode to active short circuit control (ASC) (# 11).

  The timing charts of FIG. 9 and FIG. 10 show the relationship between the detection of the overcurrent, the retraction control, and the failsafe control. "THoc" in the figure indicates a predetermined overcurrent threshold. The overcurrent threshold THoc can also be, for example, a specified current Ith. As shown in FIGS. 9 and 10, the inverter control device 20 generates an overcurrent when the alternating current of any phase is three times or more and the overcurrent threshold THoc or more in one control cycle. Determine that there is a possibility. However, since this may be due to an event that does not need to be detected as an overcurrent, such as a transient current jump, the inverter control device 20 uses a reset operation as a reset operation to eliminate such an event. , Shut down control (SDN) of the inverter 10 for a short time. "NML" indicates a normal control mode such as torque control. Even if such a reset operation is performed, the inverter control device 20 determines the determination that the overcurrent is occurring if the determination that the overcurrent may be generated continues three times. This corresponds to the process of step # 1 and step # 2 in FIG. Note that the number m of these determinations is an example, and may be a value other than three.

  When it is determined that the overcurrent is occurring, as described above, the inverter control device 20 executes the evacuation control. FIGS. 9 and 10 illustrate an embodiment in which zero torque control (ZTQ) is performed. This corresponds to the process of step # 7 in FIG. As shown in FIG. 9, when the alternating current reaches three times the overcurrent threshold THoc or more in one control cycle thereafter, the inverter control device 20 determines that the overcurrent is occurring. The control mode is set to active short circuit control (ASC). This process corresponds to steps # 9 to # 11 in FIG. The number (n) of the determinations is also an example, and may be a value other than one. However, it is preferable that the number of times m (in the above example, three times) or less of repeating the determination repeatedly if there is a possibility that an overcurrent is generated (n ≦ m).

  On the other hand, as shown in FIG. 10, the overcurrent state is not determined unless the alternating current reaches three times the overcurrent threshold THoc or more in one control cycle after the execution of the zero torque control. This process corresponds to Step # 9 to Step # 10 (No determination side) in FIG. FIG. 10 illustrates an example in which the zero torque control is continued. However, the control method is not limited to the continuation of the zero torque control, and another control method such as transition to shutdown control may be selected according to the rotation speed ω of the rotary electric machine 80 and the DC link voltage Vdc.

Outline of Embodiment
The outline of the inverter control device (20) described above will be briefly described below.

As one aspect, an inverter control apparatus connected to a DC power supply (11) and connected to an AC rotating electric machine (80) to control an inverter (10) for converting power between DC and a plurality of AC phases (20) is
A specific area (A2) in which the operating point of the electric rotating machine (80) defined by the relation between the absolute value of the torque (T) and the rotational speed (ω) is the area above the threshold defined by the relation If an overcurrent condition is detected in at least one of the inverter (10) and the rotating electric machine (80),
Execute retraction control to reduce at least one of the torque (T) and the rotational speed (ω) of the rotating electrical machine (80) until the operating point is out of the range of the specific area (A2),
When the overcurrent state is eliminated by the retraction control, it is determined that an off fault which is always in the off state has occurred in one of the switching elements (3) constituting the inverter (10). ,
If the overcurrent state is not eliminated even by the retraction control, it is determined that another failure has occurred.

  The specific area (A2) is an area equal to or greater than the threshold value defined by the relationship between the absolute value of the torque (T) and the rotational speed (ω), and alternating current even when normal control is normally performed. The value of (Iu, Iv, Iw) increases. Here, if one switching element (3) has an off failure, the symmetry of the three-phase alternating current (Iu, Iv, Iw) is broken. In addition, when the amplitude center is shifted, the peak value of any single-phase alternating current (Iu, Iv, Iw) may be larger than that when normal control is normally performed. Therefore, the occurrence of the off failure may detect an overcurrent condition. On the other hand, when the operating point is outside the target area, the symmetry of the alternating current is broken, and the amplitude itself of the alternating current is small even if the center of amplitude is shifted, and the value does not become large enough to be detected as an overcurrent. There are many. Therefore, by moving the operating point from the specific area (A2), it can be determined whether the cause of the overcurrent is an off failure. If active short circuit control is performed with an off failure in one of the switching elements (3) controlled to be in the on state, the path through which the return current flows is reduced, and healthy switching without failure occurs. There is a possibility that an excessive current may flow to the element (3). However, if the cause of the overcurrent is not an off failure, execution of active short circuit control is also possible. As described above, according to this configuration, it can be determined whether the cause of the overcurrent is an off failure or not. Therefore, when performing failsafe control by detecting the overcurrent, the switching element (3) of the inverter (10) The cause of the occurrence of the overcurrent can be estimated in consideration of the possibility that one of them is in the off state.

  As one aspect, in the retraction control, it is preferable to reduce at least the torque.

  In a situation where kinetic energy is supplied to the rotating electric machine (80), for example, when the rotating electric machine (80) is drivingly connected to the wheel (W) of the vehicle, the rotation of the rotating electric machine (80) It may be difficult to reduce the speed (ω). The alternating current can also be reduced by reducing the absolute value of the torque (T). Therefore, in the retraction control, it is preferable to reduce the alternating current by at least reducing the torque (T) even if the rotational speed (ω) of the rotating electrical machine (80) is maintained. Naturally, when the rotational speed (ω) of the rotating electrical machine (80) decreases, the alternating current can be reduced for both powering and regeneration, so the rotational speed (ω) is reduced along with the torque (T). It does not interfere with things.

  When the inverter control device (20) determines that the off failure has occurred, torque reduction control to reduce the torque of the rotating electric machine (80) or the rotation direction of the rotating electric machine (80) It is preferable to execute deceleration control that outputs torque in the reverse direction.

  When an off failure has occurred, it is not preferable to execute active short circuit control as failsafe control as described above. Preferably, the kinetic energy of the rotating electrical machine (80) is reduced by torque reduction control or deceleration control to reduce the current flowing to the inverter (80) and the rotating electrical machine (80).

  When the inverter control device (20) determines that another failure different from the off failure has occurred, the plurality of upper stage switching devices (31) connected to the positive electrode side of the DC power supply (11) And all of the plurality of switching elements (3) connected to one of the lower side switching elements (32) connected to the negative electrode side of the DC power supply (11) are turned off; It is preferable to execute active short circuit control in which current flows between the inverter (10) and the rotating electrical machine (80) with all of the plurality of switching elements (3) connected to the electrode side turned on. .

  When active short circuit control is executed in a state where one of the switching elements (3) controlled to be in the on state has an off failure, the balance of the current flowing in each phase is lost, and also the path through which the current flows Because of the limitation, an excessive current may flow to the sound switching element (3) which has not failed. However, if the cause of the overcurrent is not an off failure, execution of active short circuit control reduces the possibility of excessive current flow to some switching elements 3, so the inverter controller (20) performs failsafe control. It is also possible to implement active short circuit control.

ω: Rotational speed 3: Switching element 10: Inverter 11: High voltage battery (DC power supply)
20: inverter control device 31: upper stage side switching element 32: lower stage side switching element 80: rotating electric machine 95: second engagement device (engagement device)
A2: Second operation area (specific area)
Ith: Specified current (permissible current)
Iu: U phase current (AC current)
Iv: V-phase current (AC current)
Iw: W-phase current (AC current)
Vdc: DC link voltage

Claims (4)

An inverter control apparatus connected to a DC power supply and connected to an AC rotating electric machine to control an inverter for converting power between DC and AC of multiple phases,
The operating point of the rotating electrical machine defined by the relationship between the absolute value of torque and the rotational speed is within the range of a specific region which is a region greater than or equal to the threshold value defined by the relationship; When an overcurrent condition is detected in at least one of
Executing retraction control to reduce at least one of the torque and the rotational speed of the rotating electrical machine until the operating point is out of the range of the specific region;
When the overcurrent state is eliminated by the retraction control, it is determined that an off failure which is always in an off state has occurred in one of the switching elements constituting the inverter,
The inverter control apparatus which determines with the other failure having arisen when the said overcurrent state is not eliminated also by the said retraction | saving control.   The inverter control device according to claim 1, wherein at least the torque is reduced in the retraction control.   When it is determined that the off failure has occurred, torque reduction control for reducing the torque of the rotating electrical machine or deceleration control for outputting a torque in a direction opposite to the rotational direction of the rotating electrical machine is executed. The inverter control apparatus as described in 1 or 2. When it is determined that another failure different from the off failure has occurred, the plurality of upper stage side switching elements connected to the positive electrode side of the DC power supply and the plurality of lower stages connected to the negative electrode side of the DC power supply Among the side switching elements, the plurality of switching elements connected to one electrode side are all turned off, and the plurality of switching elements connected to the other electrode side are all turned on, the inverter and the rotating electric machine The inverter control device according to claim 1 or 2, wherein active short circuit control is performed to return current between them.

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