JP2020018157A - Abnormality determination system - Google Patents

Abstract

To provide an abnormality determination system capable of detecting abnormality of cutoff function, even at the time of substantially 0 fastening failure of a current sensor.SOLUTION: The gate command section 44 of a control arrangement 40 generates driving signals for driving the gates of multiple switching elements 61-66 of a bridge circuit 60. An AND circuit 48 as a signal changeover section outputs the driving signals to a bridge circuit 60, when the driving signals are inputted, but an interruption signal for stopping gate drive of the multiple switching elements 61-66 are not inputted. When the interruption signal is inputted, the AND circuit 48 stops output of the driving signals, and actuates the interruption function of an inverter 30. When a power supply relay 15 operates to open, the control arrangement 40 starts discharge processing for discharging a smoothing capacitor 50, and actuates the interruption function during execution of discharge processing. When a determination is made that the capacitor voltage Vc is low during operation of the interruption function, an abnormality determination part 45 determines that the interruption function is abnormal.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an abnormality determination system that determines an abnormality of a shutoff function of an inverter.

  2. Description of the Related Art Conventionally, in an inverter that drives a rotating electric machine, a device that determines an abnormality of a shutoff function that stops gate driving of a switching element is known. For example, a vehicle drive device disclosed in Patent Literature 1 determines an abnormality of a shutoff function for shutting off a power converter after the vehicle has finished traveling.

  The control device of the drive device outputs a drive command for flowing a drive current and a cutoff command for shutting down the power converter with priority over the drive command. When the drive current is determined while both the drive command and the shutoff command for shutting off the power converter are being output, the control device determines that the shutoff function for shutting off the power converter is abnormal. It is determined that there is.

Japanese Patent No. 5287705

  Hereinafter, “approximately 0” with respect to the current means “substantially 0 [A]”, and indicates a current in a range substantially regarded as “0 [A]” in consideration of the resolution and detection error of the device. . In general, a command for flowing a drive current is determined so as to control a drive state while referring to output values of a two-phase current sensor. Further, according to the device of Patent Document 1, if the output value of the current sensor is approximately 0, the cutoff function is normal. If the output value of the current sensor is larger than approximately 0 or smaller than approximately 0, the drive current flows out. It is determined that the cutoff function is abnormal.

  For example, it is assumed that a “substantially 0 stuck failure” occurs in the V-phase current sensor among the current sensors provided in the two phases of the V-phase and the W-phase. In this case, even if the drive current flows in the current path from the U-phase to the V-phase, the output of the V-phase current sensor is substantially 0, so that the cutoff function is determined to be normal. Further, when a “substantially zero fixing failure” occurs in both the V-phase and W-phase current sensors, it is determined that the cutoff function is normal regardless of which phase the drive current flows. Therefore, it is not possible to correctly detect an abnormality in the shutoff function.

  In the second embodiment of Patent Document 1, when a voltage drop of the smoothing capacitor occurs and the outflow of the drive current is detected, it is determined that the cutoff function is abnormal. That is, even if a voltage drop of the smoothing capacitor has occurred, the failure of the shut-off function cannot be correctly detected if the "substantially zero fixation failure" has occurred in the current sensor of one or more phases. This is the same as when not used for diagnosis.

  The present invention has been made in view of such a point, and an object of the present invention is to provide an abnormality determination system that can detect an abnormality of a shut-off function even when a current sensor has a substantially zero stick failure.

  The abnormality determination system according to the present invention includes an inverter (30) and a power relay (15). The inverter includes a bridge circuit (60) in which a plurality of switching elements (61-66) are bridge-connected, a smoothing capacitor (50) provided at an input portion of the bridge circuit, and a control device (40) for controlling driving of the bridge circuit. )including. The inverter converts the DC power input from the DC power supply (10) to the bridge circuit into AC power and supplies the AC power to the rotating electric machine (80). The power supply relay is provided between the DC power supply and the smoothing capacitor, and can cut off the power supply from the DC power supply to the bridge circuit.

  The control device includes a gate command unit (44), a signal switching unit (48), and an abnormality determination unit (45). The gate command unit generates a drive signal for driving gates of a plurality of switching elements of the bridge circuit. The signal switching unit outputs the drive signal to the bridge circuit when the drive signal is input and the cutoff signal for stopping the gate driving of the plurality of switching elements of the bridge circuit is not input. Further, when the cutoff signal is input, the signal switching unit stops outputting the drive signal and operates the cutoff function of the inverter. The abnormality determination unit determines an abnormality of the shutoff function.

  When the power supply relay is opened, the control device starts the discharge process for driving the bridge circuit to discharge the electric charge of the smoothing capacitor, and operates the cutoff function during the execution of the discharge process. When it is determined that the voltage (Vc) of the smoothing capacitor detected directly or indirectly has decreased during the operation of the cutoff function, the abnormality determination unit determines that the cutoff function is abnormal. "Indirect detection" refers to detecting the voltage of the smoothing capacitor, for example, by detecting the current flowing out of the high potential side electrode of the smoothing capacitor to the bridge circuit.

  In the abnormality determination system of the present invention, instead of using the current value of the current sensor as in the related art of Patent Document 1, the abnormality of the cutoff function is determined based only on the voltage drop of the smoothing capacitor. Even in the case where the current sensor is almost stuck at zero, the abnormality diagnosis of the shutoff function can be appropriately performed.

  Further, in the related art of Patent Literature 1, it is not specified which of the plurality of shutdown commands is abnormal. Further, in a system configuration in which a common system main relay is provided immediately after the power storage device for a plurality of inverters, the motor current of each inverter is input to the current detection unit without distinguishing the timing. That is, no consideration is given to interference in abnormality detection with respect to a plurality of shutoff commands or interference with abnormality detection among a plurality of inverters. On the other hand, in the present invention, when diagnosing abnormalities of a plurality of cutoff signals or diagnosing abnormalities of a plurality of inverters, it is desirable to avoid the interference of abnormality detection by shifting the timing of the diagnosis.

FIG. 1 is an overall configuration diagram of an abnormality determination system according to a first embodiment. FIG. 2 is a configuration diagram in which the system configuration of FIG. 1 is simplified. FIG. 3 is a diagram illustrating a configuration regarding a drive signal and a cutoff signal according to the first embodiment. 5 is a flowchart of a diagnosis process according to the first embodiment. 5 is a time chart of a diagnosis process according to the first embodiment. 9 is a flowchart of a diagnosis execution determination based on a diagnosis start voltage. FIG. 2 is a diagram of a system in which another device is connected in parallel with a smoothing capacitor. FIG. 5 is a configuration diagram of an abnormality determination system according to a second embodiment. FIG. 10 is a diagram illustrating a configuration regarding a drive signal and a cutoff signal according to a third embodiment. 9 is a flowchart of a diagnosis process according to the third embodiment. 9 is a time chart of a diagnosis process according to the third embodiment. FIG. 9 is a configuration diagram of an abnormality determination system according to a fourth embodiment. FIG. 14 is a diagram illustrating a configuration regarding a drive signal and a cutoff signal according to a fourth embodiment. 9 is a flowchart of a diagnosis process according to a fourth embodiment. 15 is a flowchart of a diagnosis process according to a fifth embodiment. FIG. 13 is a configuration diagram of an abnormality determination system according to a sixth embodiment. FIG. 14 is a configuration diagram of an abnormality determination system according to a seventh embodiment. The block diagram of the abnormality determination system of 8th Embodiment. FIG. 18 is a diagram illustrating a case where the inverters to be diagnosed are limited in the abnormality determination system according to the eighth embodiment.

  Hereinafter, a plurality of embodiments of an abnormality determination system will be described with reference to the drawings. In a plurality of embodiments, substantially the same configuration or substantially the same step in the flowchart is denoted by the same reference numeral or the same step number, and the description is omitted. Further, the first to eighth embodiments are collectively referred to as “the present embodiment”. The abnormality determination system according to the present embodiment is mounted on a hybrid vehicle or an electric vehicle including a motor as a “rotary electric machine” as a power source.

  During normal running of the vehicle, the abnormality determination system converts DC power of a battery as a “DC power supply source” into AC power by an inverter and supplies the AC power to the AC motor. Then, when the vehicle is ready-off after stopping and the power relay provided between the battery and the inverter is opened (that is, turned off), the abnormality determination system cooperates with the vehicle control device to diagnose abnormality of the shutoff function. “Abnormality of the shutoff function” means an abnormality of the shutoff signal for stopping the gate of the switching element forming the bridge circuit of the inverter.

(1st Embodiment)
An abnormality determination system according to the first embodiment will be described with reference to FIGS. FIG. 1 shows an overall configuration of an abnormality determination system 901 for supplying power from one inverter 30 to one three-phase AC motor 80. The abnormality determination system 901 mainly includes the inverter 30 and the power relay 15.

  The inverter 30 includes a bridge circuit 60 in which a plurality of switching elements 61 to 66 are bridge-connected, a smoothing capacitor 50 provided at an input portion of the bridge circuit, and a control device 40 for controlling driving of the bridge circuit. As described above, in the present specification, the bridge circuit 60 alone is not defined as an “inverter”, but is defined as an “inverter” including the smoothing capacitor 50 and the control device 40. The inverter 30 converts DC power input from the battery 10 as a “DC power supply source” to the bridge circuit 60 into AC power, and supplies the AC power to a motor 80 as a “rotary electric machine”. The power relay 15 is provided between the battery 10 and the smoothing capacitor 50, and can cut off the power supply from the battery 10 to the bridge circuit 60.

  Next, each component will be described in detail. The battery 10 is a chargeable / dischargeable secondary battery such as a lithium ion battery, and is a so-called high voltage battery capable of storing a high voltage of several hundred volts. However, in the present specification, the high-voltage battery is simply referred to as “battery 10” because an auxiliary battery, which is a so-called low-voltage battery, is not referred to. The positive electrode of battery 10 is connected to the high potential electrode of smoothing capacitor 50 via DC bus Lp, and the negative electrode of battery 10 is connected to the low potential electrode of smoothing capacitor 50 via ground line Ln. The charge amount and temperature of the battery 10 are monitored by the battery monitoring device 12.

  The power relay 15 is provided on the DC bus Lp between the positive electrode of the battery 10 and the high potential electrode of the smoothing capacitor 50, for example, as shown in FIG. The power supply relay may be provided across the DC bus Lp and the ground line Ln like the system main relay of Patent Document 1, or may be combined with a precharge relay for preventing an inrush current at the time of closing operation. The opening and closing of the power supply relay 15 is operated by the vehicle control device 20 or the battery monitoring device 12 that controls the behavior of the entire vehicle. When the battery monitoring device 12 operates the power supply relay 15, the information is notified to the vehicle control device 20.

  In the present embodiment applied to a vehicle, typically, when a power switch of the vehicle is ready-on, a power supply relay is turned on, that is, closed. During traveling of the vehicle including a temporary stop, electric charges are accumulated in the smoothing capacitor 50. When the vehicle stops and the power switch is ready-off, the power supply relay 15 is turned off, that is, opened. Thereafter, a discharge process (so-called discharge process) for discharging the remaining charge of the smoothing capacitor 50 is generally performed to secure electrical safety during parking.

  In the bridge circuit 60 of the inverter 30, the six switching elements 61-66 of the upper and lower arms are bridge-connected. The switching elements 61, 62, and 63 are upper-arm switching elements of U-phase, V-phase, and W-phase, respectively, and the switching elements 64, 65, and 66 are lower-arm switching elements of U-phase, V-phase, and W-phase, respectively. Element. Each of the switching elements 61 to 66 is formed of, for example, an IGBT, and is connected in parallel with a return diode that allows a current flowing from a low potential side to a high potential side.

  Hereinafter, motor control during normal running of the vehicle is referred to as “normal control”. During normal control, the bridge circuit 60 converts DC power into three-phase AC power by operating the switching elements 61-66 in accordance with the gate signal output from the control device 40. Then, a phase voltage according to the voltage command calculated by the control device 40 is applied to each phase winding 81, 82, 83 of the motor 80.

  The smoothing capacitor 50 smoothes the DC voltage input to the bridge circuit 60. Hereinafter, the voltage between the electrodes of the smoothing capacitor 50, in other words, the voltage of the DC bus Lp based on the potential of the ground line Ln is referred to as “capacitor voltage Vc”. In the first embodiment, a voltage sensor 51 for directly detecting the capacitor voltage Vc is provided.

  A current path for detecting a phase current is provided in a current path connected to two-phase or three-phase or more of the three-phase windings 81, 82, and 83 of the motor 80. In the example of FIG. 1, current sensors 72 and 73 for detecting phase currents Iv and Iw are provided in current paths connected to the V-phase winding 82 and the W-phase winding 83, respectively. Iu is estimated based on Kirchhoff's law. In other embodiments, any two-phase current may be detected and three-phase current may be detected.

  The detected phase current is coordinate-converted into, for example, a dq-axis current and is fed back to the current command, so that the voltage command is PI-calculated. As described later, in the present embodiment, a current sensor is not necessary in the first place, and therefore, for example, the bridge circuit 60 may always be driven by feedforward control without using a current detection value even during normal control.

  The motor 80 is, for example, a permanent magnet type synchronous three-phase AC motor. The motor 80 according to the present embodiment has both a function as an electric motor that generates torque for driving the drive wheels of the hybrid vehicle and a function as a generator that recovers the torque transmitted from the engine and the drive wheels by generating electricity. It is a motor generator. In general, a motor control is provided with a rotation angle sensor for detecting a rotation angle used for coordinate conversion calculation or the like, but illustration in FIG. 1 and reference in the specification are omitted.

  The control device 40 includes a microcomputer 41 including a gate command unit 44 and an abnormality determination unit 45, and an AND circuit 48 as a “signal switching unit”. The microcomputer 41 internally includes a CPU, a ROM, an I / O (not shown), a bus line for connecting these components, and the like. The microcomputer 41 executes control by software processing by executing a program stored in advance by the CPU or hardware processing by a dedicated electronic circuit. Further, the vehicle control device 20 and the control device 40 can communicate with each other via a network such as CAN communication.

  At the time of normal control, the microcomputer 41 performs general motor control such as vector control. That is, the microcomputer 41 performs three-phase conversion on the dq-axis voltage command calculated by the controller to calculate a three-phase voltage command, and further performs PWM modulation by the modulator to output a gate command. In the current feedback control, the controller calculates a dq-axis voltage command by performing PI control so that the detected current value follows the current command. In the voltage feedforward control, the controller calculates, for example, a dq-axis voltage command calculated from a current command by a voltage equation. Since such a general motor control configuration is a well-known technique, detailed description and illustration of signal input / output are omitted.

  In particular, in the present embodiment, the gate command unit 44 of the microcomputer 41 generates a drive signal DR for driving the gates of the plurality of switching elements 61-66 of the bridge circuit 60. The abnormality determination unit 45 determines an abnormality of a later-described interruption function based on a change in the capacitor voltage Vc at the time of gate interruption. Further, as described later, the abnormality determination unit 45 determines an abnormality in the discharge function of the inverter 30 based on a change in the capacitor voltage Vc during the discharging process.

  When the power supply relay 15 is opened by the operation of the vehicle control device 20 or the battery monitoring device 12, the vehicle control device 20 transmits a discharge command to the gate command unit 44 of the microcomputer 41 by CAN communication. Therefore, the drive signal DR is input from the gate command unit 44 to one input terminal of the AND circuit 48. The other input terminal of the AND circuit 48 receives a negative input of the shut-off signal SO generated by the microcomputer 41 of the AND circuit 48 or the vehicle control device 20. The cutoff signal SO is a signal for stopping gate driving of the plurality of switching elements 61-66 of the bridge circuit 60.

  That is, the AND circuit 48 outputs the drive signal DR to the bridge circuit 60 when the drive signal DR is input and the cutoff signal SO is not input. At this time, the control device 40 can operate the switching elements 61 to 66 of the bridge circuit 60 to perform the discharging process.

  The AND circuit 48 does not output when the drive signal DR is not input or when the cutoff signal SO is input. Therefore, the AND circuit 48 stops outputting the drive signal DR when the cutoff signal SO is input from the microcomputer 41 or the vehicle control device 20. In this manner, the operation of stopping the gate drive of the bridge circuit 60, that is, fixing the OFF state irrespective of the gate command, is expressed as "operating the cutoff function of the inverter 30". The control device 40 can interrupt the discharge of the smoothing capacitor 50 by operating the cutoff function of the inverter 30 during the execution of the discharge process.

  FIG. 2 is a simplified diagram of the system configuration of FIG. FIG. 3 is a diagram illustrating a communication configuration regarding the drive signal DR and the cutoff signal SO in the vehicle control device 20 and the control device 40. FIGS. 2 and 3 are basic views showing the configuration of the first embodiment. In the second and subsequent embodiments, the difference between the first embodiment and the second embodiment is shown in a diagram similar to FIGS. Is shown. Configurations omitted in the drawings of the following embodiments are to be interpreted according to FIG.

  By the way, if an abnormality occurs in the cutoff signal SO, there is a disadvantage that the drive cannot be stopped when the gate drive of the bridge circuit 60 needs to be stopped urgently. Therefore, there is a need to diagnose the abnormality of the cutoff signal SO. In the technique disclosed in Patent Literature 1 as a conventional technique, an abnormality of the cutoff function is determined based on an output value of a two-phase current sensor that detects a drive current. However, this conventional technique has a problem that when a “substantially zero fixation failure” occurs in the current sensor, it is not possible to correctly detect an abnormality in the cutoff function.

  In the method of detecting an abnormality of the shutoff function using a two-phase current sensor according to the related art, the above-described problem occurs because there is a leak in a cover range for checking the shutoff function. When the cutoff function is abnormal and current flows out of the smoothing capacitor 50, energy is supplied to the inverter 30 from the DC bus Lp even if a part of the cutoff function has failed as described above.

  An aspect of solving the problem is that if the energy supply is inspected, leakage of the coverage area can be prevented. In the present embodiment, attention is paid to the point that the energy supply can be inspected by a change in the energy stored in the smoothing capacitor 50 when the smoothing capacitor 50 is discharged. Further, since the energy stored in the smoothing capacitor 50 is proportional to the square value of the capacitor voltage Vc, it is possible to inspect the energy supply by changing the capacitor voltage Vc.

  Therefore, in the present embodiment, a means for solving the problem is adopted in which the interruption function is confirmed using the capacitor voltage Vc during the discharge of the charge of the smoothing capacitor 50. That is, the abnormality determination unit 45 determines that there is an abnormality in the cutoff function if the capacitor voltage Vc decreases while the discharge process is performed and the cutoff signal SO is output. That is, in the present embodiment, the output values of the current sensors 72 and 73 are not used for abnormality diagnosis, and the abnormality of the cutoff function is determined only by a change in the energy stored in the smoothing capacitor 50. In this way, it is possible to ensure an abnormality detection property when the current sensors 72 and 73 have a substantially zero stick failure.

  Next, a diagnosis process according to the first embodiment is shown in a flowchart of FIG. In the following flowcharts, the symbol S represents “step”. Of the steps in FIG. 4, step S10 of the discharge function diagnosis includes S13 and S14, and step S20 of the shutdown function diagnosis includes S22 to S24. In the description of FIG. 4, “abnormality of the cutoff function” is specifically described as “abnormality of the cutoff signal SO”.

  When the power relay is opened in S01, the control device 40 starts driving the inverter 30 in S02 and starts discharging the smoothing capacitor. When the inverter 30 is driven and a current flows through the motor 80, if the driving of the inverter 30 is normal, the charge of the smoothing capacitor 50 is discharged and the capacitor voltage Vc decreases. However, when the driving of the inverter 30 is abnormal, the capacitor voltage Vc does not decrease.

  Therefore, in S13, the abnormality determination unit 45 determines whether or not the capacitor voltage Vc has dropped during the period before the shut-off function operates. The abnormality determination unit 45 determines that the discharge function of the inverter 30 is normal when there is a voltage drop, and determines that the discharge function of the inverter 30 is abnormal when there is no voltage drop and the capacitor voltage Vc is maintained. Specifically, when the capacitor voltage Vc is equal to or greater than the discharge threshold value α, or when the capacitor voltage decrease amount ΔVc is equal to or less than the discharge decrease amount threshold value α, NO is determined in S13 and the process proceeds to S14. In S14, the abnormality determination unit 45 determines that the discharge function of the inverter 30 is abnormal.

  If YES in S13, that is, if it is determined that the discharge function is normal, the cutoff function diagnosis in S20 is performed. After the cutoff signal SO is turned on in S22, the abnormality determination unit 45 determines in S23 whether or not the capacitor voltage Vc has dropped. The abnormality determination unit 45 determines that the cutoff signal SO is normal when there is no voltage drop, and determines that the cutoff signal SO is abnormal when there is a voltage drop. Specifically, when the capacitor voltage Vc is equal to or less than the cut-off threshold value β, or when the capacitor voltage decrease amount ΔVc is equal to or greater than the cut-off amount threshold value Δβ, YES is determined in S23 and the process proceeds to S24. In S24, the abnormality determination unit 45 determines that the cutoff signal SO is abnormal.

Here, the method of determining the presence or absence of a voltage drop will be supplemented. The presence or absence of the voltage drop may be determined by sampling the voltage at least at two timings and evaluating the voltage drop amount ΔVc, or may be determined by the fact that the voltage equal to or lower than the cutoff threshold has continued for a predetermined time. When a discharge resistor is provided in the DC bus Lp, the voltage drop ΔVc is evaluated in consideration of the voltage drop due to the discharge of the discharge resistor. More specifically, the rate of change of the capacitor energy with time due to the discharge of the discharge resistor is “voltage ² / resistance value”, which may be taken into account.

  When NO is determined in S23, that is, when the cutoff signal SO is determined to be normal, the abnormality determination unit 45 completes the abnormality diagnosis in S30. In the process of FIG. 4, by performing the shutdown function diagnosis after confirming that the discharge function is normal, it is possible to avoid erroneous determination that the shutdown signal SO is normal despite the occurrence of an abnormality in the shutdown signal SO. be able to. However, for example, when it is already confirmed that the drive of the inverter 30 is normal by another diagnosis processing, the discharge function diagnosis in S10 may be omitted. In this case, following S02, the step of turning off the cutoff signal in S22 may be performed.

  The relationship between the operation timing of the gate and the change in the capacitor voltage Vc in the diagnostic processing of the first embodiment is shown in the time chart of FIG. The period indicated by the bar indicates a period during which the discharge processing of the smoothing capacitor 50 is performed and a period during which the gate cutoff signal SO is output to the bridge circuit 60. “S02”, “S22, S23” and “S30” correspond to the step numbers in FIG. In FIG. 5, communication delay is not considered.

  When the discharge process is started at time t1, the capacitor voltage Vc decreases from the voltage Vci at the start of diagnosis with a gradient corresponding to the discharge speed. When the cutoff signal SO is output from time t2 to time t3, when the cutoff signal SO is normal, the capacitor voltage Vc is maintained at a constant value Vcs as shown by a solid line. At time t3, the abnormality determination unit 45 determines normality, and the abnormality diagnosis is completed. When the output of the cutoff signal SO stops, the capacitor voltage Vc decreases again, and the discharge process ends at time t4 when the convergence value Vcf decreases to 0 (ideally, 0).

  On the other hand, when the cutoff signal SO is abnormal, as indicated by the broken line, the capacitor voltage Vc continues to decrease after time t2 and thereafter reaches the convergence value Vcf. At time t3, the abnormality determination unit 45 makes an abnormality determination based on, for example, that the voltage drop amount ΔVc is equal to or larger than the threshold, and the abnormality diagnosis is completed.

Hereinafter, other considerations in the abnormality diagnosis will be described.
<Current vector when driving the inverter>
The current vector at the time of driving the inverter for discharging is desirably in the d-axis direction so that torque due to the current is not generated. This makes it possible to avoid a driver's discomfort when the discharge is performed immediately after the vehicle stops. Even if the current sensors 72 and 73 are out of order, the current can flow if the inverter 30 is driven, so that the discharge can be realized.

<Drive command output method>
As a control method for driving the inverter 30 at the time of discharging, if the current sensors 72 and 73 are normal, a current feedback control method of generating a voltage command from a deviation between the current command and the detected current value may be adopted. Alternatively, a voltage feedforward control method of generating a voltage command without using a current detection value may be employed.

<Switch of discharge speed>
It is desirable that the discharge rate be switched according to the capacitor voltage Vc. In particular, the discharge speed is increased in a voltage range higher than the voltage range used for diagnosis, and is decreased in a voltage range lower than the voltage range used for diagnosis. Slowing the discharge rate facilitates setting of diagnostic conditions. Further, by increasing the discharge speed, the completion of the discharge can be accelerated, and the safety is improved. Note that the discharge rate may be switched stepwise or continuously according to the capacitor voltage Vc.

<Voltage range at the start of diagnosis>
Preferably, the presence or absence of the diagnosis is determined according to the capacitor voltage Vc at the start of the diagnosis. This is because if the voltage Vc at the start of the diagnosis is lower than the lower limit value, the voltage drops sharply due to the discharge and normal diagnosis cannot be performed. If the voltage Vc at the start of the diagnosis is higher than the upper limit value, the time until the completion of the diagnosis becomes longer and safety is impaired. In the flowchart of FIG. 6, in S04, the control device 40 determines whether the voltage at the start of diagnosis is in the range from the lower limit to the upper limit. If YES in S04, the diagnosis is performed in S05, and if NO in S04, the diagnosis is not performed in S06.

<Handling of systems in which other devices are connected to the DC bus>
As shown in FIG. 7, it is assumed that another device 19 is connected in parallel with the smoothing capacitor 50 between the DC bus Lp and the ground line Ln closer to the inverter 30 than the power relay 15. The other device 19 is, for example, a DCDC converter or an air conditioner compressor. In such a system, when the other device 19 operates after the opening operation of the power supply relay 15, the electric charge of the smoothing capacitor 50 is consumed, so that it is impossible to make a correct determination in the abnormality diagnosis. Therefore, it is necessary to stop the operation of the other devices 19 before opening the power relay 15. In particular, the configuration to which the boost converter is connected will be described later as seventh and eighth embodiments.

  As described above, in the abnormality determination system 901 of this embodiment, after the power relay 15 is opened, when it is determined that the voltage Vc of the smoothing capacitor detected during the operation of the cutoff function has decreased, the abnormality determination is performed. The unit 45 determines that the shutoff function is abnormal. Instead of using the current values of the current sensors 72 and 73 as in the related art of Patent Document 1, the abnormality of the cutoff function is determined based only on the capacitor voltage Vc. Even in the case of a 0-stick failure, it is possible to appropriately perform the abnormality diagnosis of the shutoff function.

  In the abnormality determination system 901, when it is determined that the capacitor voltage Vc is maintained during a period after the start of the discharge process and before the shut-off function operates, the abnormality determination unit 45 sets the discharge function of the inverter 30. Is determined to be abnormal. By performing the shutoff function diagnosis after confirming that the discharge function is normal, it is possible to avoid erroneous determination that the shutoff signal SO is normal despite the occurrence of an abnormality in the shutoff signal SO.

(2nd Embodiment)
FIG. 8 shows a second embodiment that differs from the first embodiment in the configuration for detecting a change in the capacitor voltage. An abnormality determination system 902 of the second embodiment includes a current sensor 52 instead of the voltage sensor 51 of FIGS. The current sensor 52 is provided on the DC bus Lp between the smoothing capacitor 50 and the bridge circuit 60, and detects the current Ic flowing out of the high potential side electrode of the smoothing capacitor 50. Since the current Ic flowing out of the high potential side electrode of the smoothing capacitor 50 to the bridge circuit 60 has a correlation with the capacitor voltage Vc, in this configuration, a change in the capacitor voltage Vc is indirectly detected.

  Specifically, when the output value of the current sensor 52 is approximately 0 [A], “no voltage drop” is determined, that is, “NO” is determined in S23 of FIG. 4, and the cutoff function is determined to be normal. On the other hand, when the output value of the current sensor 52 is not substantially 0 [A], “there is a voltage drop”, that is, “YES” is determined in S23 of FIG. 4, and the cutoff function is determined to be abnormal. As described above, in the second embodiment, similarly to the first embodiment, abnormality diagnosis of the shutoff function can be performed.

  However, there is a possibility that an abnormality in the cutoff function is erroneously determined when the current sensor 52 is stuck. Therefore, in order to prevent an erroneous determination, it is preferable to confirm in advance that a current value is output by the current sensor 52 at the time of a discharge process before operating the cutoff function. In each of the following embodiments, the capacitor voltage Vc may be detected using either the method using the voltage sensor 51 according to the first embodiment or the method using the current sensor 52 according to the second embodiment.

(Third embodiment)
A third embodiment will be described with reference to FIGS. As shown in FIG. 9, in the abnormality determination system 903 of the third embodiment, a plurality of cutoff signals are used. The control device 40 includes an OR circuit 47 and an AND circuit 48 in addition to a main microcomputer 42 that controls the entire control of the inverter 30 and a motor control microcomputer 43 that controls the driving of the motor 80. The main microcomputer 42 includes an abnormality determination unit 45, and the motor control microcomputer 43 includes a gate command unit 44.

  When the power relay 15 is opened, a diagnosis command from the vehicle control device 20 is transmitted to the main microcomputer 42 of the control device 40 by CAN communication. Based on this, the main microcomputer 42 generates a main cutoff signal SO-A, and the motor control microcomputer 43 generates a motor control cutoff signal SO-B. Further, vehicle control device control signal SO-C is transmitted from vehicle control device 20. When any one or more of the main cutoff signal SO-A, the motor control cutoff signal SO-B, and the vehicle control device control signal SO-C are input, the OR circuit 47 is turned on, which means "there is a cutoff signal". Output a signal.

  The AND circuit 48 outputs the drive signal DR to the bridge circuit 60 when the drive signal DR is input from the motor control microcomputer 43 and the ON signal is not input from the OR circuit 47. On the other hand, when the ON signal is input from the OR circuit 47, the AND circuit 48 does not output the drive signal DR to the bridge circuit 60, thereby operating the cutoff function.

  By generating a plurality of cutoff signals SO-A, SO-B, and SO-C redundantly by the plurality of microcomputers 42 and 43 and the vehicle control device 20 in the control device 40, any of the cutoff signals can be generated. Even if a failure occurs for some reason, the cutoff function is realized by another cutoff signal. Therefore, the reliability of securing the blocking function is improved.

  The flowchart in FIG. 10 and the time chart in FIG. 11 show the diagnosis processing when there are a plurality of cutoff signals. When the power supply relay is opened in S01 in FIG. 10, the control device 40 starts discharging the smoothing capacitor in S02, and performs a discharge function diagnosis in S10. Next, the control device 40 performs a shut-down function diagnosis of the main cut-off signal SO-A in S20A, performs a cut-off function diagnosis of the motor control cut-off signal SO-B in S20B, and executes a vehicle control device cut-off signal SO-C in S20C. Carry out diagnosis of the shut-off function. When the shutdown function diagnosis of all shutdown signals is completed, the abnormality diagnosis is completed in S30.

  When a plurality of cutoff signals are simultaneously diagnosed as abnormal, it is not possible to identify which cutoff signal is abnormal when the abnormality is detected. This is called "interference of abnormality detection". For example, in the related art of Patent Document 1, it is not specified which of the abnormalities of the emergency shutoff command HSDN from the HV-ECU or the shutoff commands HSDN1 # and HSDN2 # from the control unit. That is, no consideration is given to the interference of abnormality detection for a plurality of shutoff commands.

  On the other hand, in the third embodiment, the control device 40 sequentially performs the diagnosis on each of the cutoff signals SO-A, SO-B, and SO-C. Here, each cutoff signal is turned off when the diagnosis of the own signal is not performed. That is, the abnormality determination unit 45 determines an abnormality for the plurality of cutoff signals SO-A, SO-B, and SO-C based on a voltage drop of the smoothing capacitor 50 during a period in which the operations are exclusive. Therefore, interference of abnormality detection can be avoided.

  Note that, as indicated by “OL” in FIG. 11, it is preferable that the ON periods of the cut-off signals be continued so as to overlap each other. This is because, if the OFF period of the cutoff signal occurs, the discharge proceeds, the capacitor voltage Vc decreases, and the range of the voltage drop to be diagnosed decreases. When all the cutoff signals SO-A, SO-B, and SO-C are normal, the capacitor voltage Vc is maintained at the constant value Vcs from time t2 to time t3.

  Further, although any shutoff signal may be diagnosed first, it is preferable to turn on the shutoff signal of the control device or the microcomputer that determines “discharge function diagnosis” first. As a result, it is possible to reduce the communication delay time from the completion of the “discharge function diagnosis” to the turning-off signal ON. Therefore, unnecessary charge discharge of the smoothing capacitor 50 can be prevented, and the range of voltage drop to be diagnosed in the subsequent diagnosis can be as large as possible.

(Fourth embodiment)
Next, a configuration example of an abnormality determination system including a plurality of inverters will be described as a fourth embodiment with reference to FIGS. As shown in FIG. 12, in an abnormality determination system 904 according to the fourth embodiment, a plurality of inverters 301 and 302 are connected to a battery 10 in parallel. The first inverter 301 supplies power to the first motor 801, and the second inverter 302 supplies power to the second motor 802. The first motor 801 and the second motor 802 may be configured as one dual winding motor. Further, the present invention is similarly applicable to a system including three or more inverters.

  12, the reference numerals of the components of the first inverter 301 are denoted by “1”, and the components of the second inverter 302 are denoted by “2”. The DC voltage of the battery 10 is input to the bridge circuits 601 and 602 of the inverters 301 and 302 via the branch point B of the DC bus Lp. The power supply relay 15 is provided on the DC bus Lp closer to the battery 10 than the branch point B to each of the inverters 301 and 302.

  A shutoff signal for shutting off its own inverter is input to the control devices 401 and 402 of the inverters 301 and 302. FIG. 13 shows the input / output configuration of the cutoff signal in the control devices 401 and 402 of the inverters 301 and 302. FIG. 13 shows a configuration in which a plurality of shutoff signals are used for each inverter according to FIG. 9 of the third embodiment. However, one shutoff signal is provided for each inverter according to FIG. 3 of the first embodiment. May be used. Each of the main microcomputers 421 and 422 includes abnormality determination units 451 and 452, and each of the motor control microcomputers 431 and 432 includes gate command units 441 and 442.

  When the power supply relay 15 is opened, a diagnostic command from the vehicle control device 20 is transmitted to the main microcomputers 421 and 422 of the control devices 401 and 402 by CAN communication. Based on this, the main microcomputers 421 and 422 generate main cutoff signals SO-A1 and SO-A2, and the motor control microcomputers 431 and 432 generate motor control cutoff signals SO-B1 and SO-B2. Further, vehicle control device control signals SO-C1 and SO-C2 are transmitted from vehicle control device 20 to control devices 401 and 402. When one of the shutoff signals is input to the OR circuits 471 and 472, each of the AND circuits 481 and 482 outputs the shutoff signal to the bridge circuits 601 and 602 prior to the drive signals DR1 and DR2.

  The diagnostic processing of the fourth embodiment is shown in the flowchart of FIG. In FIG. 14, S100 and S200 indicate steps of “inverter diagnosis” including abnormality diagnosis of the discharge processing and the interruption function of the first inverter 301 and the second inverter 302, respectively. In the fourth embodiment, after the power supply relay 15 opens, the abnormality diagnosis of the discharge processing and the cutoff function of each of the inverters 301 and 302 is sequentially performed for each inverter.

  When the power supply relay 15 is opened in S01, the control device 401 of the first inverter 301 first diagnoses the first inverter in S100, and completes the diagnosis of the first inverter in S130. Next, the control device 402 of the second inverter 302 performs the diagnosis of the second inverter in S200, and completes the diagnosis of the second inverter in S230. The diagnosis order of the inverters 301 and 302 may be changed.

  In the system configuration of the fourth embodiment, the high-potential electrodes of the smoothing capacitors 501 and 502 of the plurality of inverters 301 and 302 are connected via the DC bus Lp, and the low-potential electrodes are connected via the ground line Ln. Have been. For this reason, if one of the plurality of inverters 301 and 302 has a normal shut-off function and the other shut-down function is abnormal, if abnormality diagnosis is performed simultaneously, current will flow from the normal inverter to the abnormal inverter. Therefore, it is difficult to independently and accurately detect a decrease in the capacitor voltages Vc1 and Vc2 of each inverter.

  Hereinafter, a situation in which a current flows between a plurality of inverters via the DC bus Lp and the capacitor voltages Vc1 and Vc2 are confused is referred to as “capacitor voltage interference”. In addition, the fact that the influence on the abnormality detection of the inverters 301 and 302 is referred to as “interference of abnormality detection”.

  In the related art of Patent Document 1, in a system configuration in which a common system main relay is provided immediately after a power storage device for a plurality of inverters, motor currents MCRT1 and MCRT2 of each inverter can be detected by a current detection unit without discriminating timing. Is input to That is, no consideration is given to interference of abnormality detection between a plurality of inverters. On the other hand, in the fourth embodiment, by diagnosing each of the inverters 301 and 302 one by one, interference of abnormality detection due to interference of the capacitor voltage Vc can be avoided, and accurate diagnosis can be performed.

(Fifth embodiment)
As another example of the abnormality diagnosis in the system including a plurality of inverters as in the fourth embodiment, a diagnosis process of the fifth embodiment is shown in a flowchart of FIG. For the system configuration, refer to FIGS. 12 and 13 in common with the fourth embodiment. The control devices 401 and 402 of each of the inverters 301 and 302 perform an abnormality diagnosis of a discharge process and a cutoff function for one or more inverters selected in order in response to one relay opening operation.

  In FIG. 15, “S01-1” of the step number indicates the first opening operation of the power supply relay 15 with reference to a certain time point, and “S01-2” indicates the second power supply operation after the power supply relay 15 is once closed. The opening operation of the relay 15 is shown. For example, the time when the vehicle stops running and ready-off for the first time corresponds to S01-1, the time when the vehicle is ready-on again, stops after running, and the time when the vehicle is ready-off for the second time corresponds to S01-2.

  When the power relay 15 is opened for the first time in S01-1, the control device 401 of the first inverter 301 performs diagnosis of the first inverter in S100, and completes diagnosis of the first inverter in S130. Then, in S09, the power supply relay 15 is closed. Thereafter, when the power supply relay 15 is opened for the second time in S01-2, the control device 402 of the second inverter 302 performs diagnosis of the second inverter in S200, and completes diagnosis of the second inverter in S230. The diagnosis order of the inverters 301 and 302 may be changed.

  In the fifth embodiment, as in the fourth embodiment, it is possible to avoid interference of abnormality detection during diagnosis of the plurality of inverters 301 and 302. Further, in the fifth embodiment, the allowable amount of charge that can be discharged per inverter in one diagnosis is increased, so that a large voltage drop for the diagnosis can be secured. Therefore, the range of the vehicle system to which this diagnosis can be applied can be expanded.

  In a system including a large number of inverters, the fourth embodiment and the fifth embodiment may be combined to perform the abnormality diagnosis. For example, when diagnosing six inverters sequentially, two inverters may be sequentially diagnosed for each relay opening operation, and diagnosis of six inverters may be completed by three relay opening operations.

(Sixth embodiment)
FIG. 16 shows another configuration example of the abnormality determination system including a plurality of inverters as the sixth embodiment. The abnormality determination system 906 according to the sixth embodiment includes a plurality of inverters 301 and 302 and a plurality of power relays 151 and 152. The power relays 151 and 152 are provided closer to the inverters 301 and 302 than the branch point B of the DC bus Lp, and individually cut off power supply from the battery 10 to the bridge circuits 601 and 602 of the inverters 301 and 302. It is possible. That is, interference of abnormality detection is avoided by the system configuration.

  In the abnormality determination system 906, the abnormality diagnosis of the discharge processing and the cutoff function can be independently and simultaneously performed for each inverter corresponding to the power supply relay that has opened. Therefore, unlike the fourth and fifth embodiments, it is not necessary to perform the abnormality diagnosis of the discharge processing and the cutoff function of each of the inverters 301 and 302 at different timings, so that the diagnosis time can be reduced.

(Seventh embodiment)
Next, an abnormality determination system 907 according to a seventh embodiment in which the boost converter 18 is provided between the battery 10 and one inverter 30 will be described with reference to FIG. The boost converter 18 includes a well-known chopper circuit including an inductor and a switching element, and boosts the voltage of the battery 10 by a switching operation and outputs the boosted voltage to the inverter 30. On the battery 10 side of the boost converter 18, a pre-converter capacitor 17 different from the smoothing capacitor 50 of the inverter 30 is provided. However, the pre-converter capacitor 17 has nothing to do with “capacitor voltage Vc” used for abnormality diagnosis. Note that boost converter 18 corresponds to an example of “other device 19” in FIG.

  The abnormality determination system 907 performs an abnormality diagnosis of the shutoff function for one inverter 30 by a method according to the first to third embodiments. In this case, the abnormality determination system 907 stops the switching operation of the boost converter 18 before performing the abnormality diagnosis of the cutoff function. Thus, it is possible to eliminate the influence on the capacitor voltage Vc due to the boosting operation of the boosting converter 18 and current consumption.

(Eighth embodiment)
Next, an abnormality determination system 908 of the eighth embodiment in which the boost converter 18 is provided between the battery 10 and the plurality of inverters 301 and 302 will be described with reference to FIGS. The configuration in FIG. 18 corresponds to a configuration in which the boost converter 18 is provided between the power supply relay 15 and the branch point B of the DC bus Lp in the abnormality determination system 904 of the fourth embodiment shown in FIG.

  The abnormality determination system 908 performs abnormality diagnosis of the shutoff function for the plurality of inverters 301 and 302 by a method according to the fourth to sixth embodiments. In this case, the abnormality determination system 908 stops the switching operation of the boost converter 18 before performing the abnormality diagnosis of the cutoff function. Thus, it is possible to eliminate the influence on the capacitor voltages Vc1 and Vc2 due to the boosting operation of the boosting converter 18 and the current consumption.

  As shown in FIG. 19, in the abnormality determination system 908, the inverter to be diagnosed may be limited to only some of the inverters (for example, the first inverter 301). When the diagnosis target is limited to one inverter, the abnormality determination system 908 performs abnormality diagnosis of the shutoff function by a method according to the first to third embodiments. In this case, similarly, the abnormality determination system 908 stops the switching operation of the boost converter 18 before performing the abnormality diagnosis of the cutoff function. Thus, it is possible to eliminate the influence on the capacitor voltage Vc1 due to the boosting operation of the boost converter 18 and current consumption.

(Other embodiments)
(A) In the above embodiment, the vehicle control device 20 and the control device 40 of the inverter 30 cooperate to realize the operation of the discharge processing and the cutoff function. Here, which function is assigned to which device may be appropriately designed. For example, the control device 40 may directly operate the power supply relay 15. Alternatively, the vehicle control device 20 may include a function as an “inverter control device”.

  (B) The DC power supply source is not limited to a battery, and may be an electric double layer capacitor, a converter that rectifies AC power and outputs DC power, or the like. Further, a boost converter may be provided between the battery and the inverter as in the system of Patent Document 1.

  (C) The abnormality determination system according to the present invention is not limited to an inverter that supplies power to a motor of a vehicle, and may be applied to an inverter that supplies power to a rotating electric machine for any purpose. In this case, instead of the “vehicle control device” in the above-described embodiment, a discharge instruction or a diagnosis instruction may be given by a “general control device” that manages the operation of the entire system including the periphery of the inverter.

  As described above, the present invention is not limited to the above embodiment, and can be implemented in various forms without departing from the spirit of the present invention.

  The control device and the method according to the present disclosure are realized by a dedicated computer provided by configuring a processor and a memory programmed to execute one or a plurality of functions embodied by a computer program. May be done. Alternatively, the control device and the technique described in the present disclosure may be implemented by a dedicated computer provided by configuring a processor with one or more dedicated hardware logic circuits. Alternatively, the control device and the method described in the present disclosure may be implemented by a combination of a processor and a memory programmed to perform one or more functions and a processor configured by one or more hardware logic circuits. It may be realized by one or more dedicated computers configured. Further, the computer program may be stored in a computer-readable non-transitional tangible recording medium as instructions to be executed by a computer.

10 ... battery (DC power supply source)
15 (151, 152) ... inverter
30 (301, 302) ... inverter
40 (401, 402) ... control device,
44: gate command unit, 45: abnormality determination unit,
48... AND circuit (signal switching unit)
50 (501, 502) ... smoothing capacitor,
60 (601, 602) ... bridge circuit, 61-66 ... switching element,
80 (801, 802) ... motor (rotary electric machine),
90 (901-904, 906-908) ... abnormality determination system.

Claims (8)

A bridge circuit (60) in which a plurality of switching elements (61-66) are bridge-connected, a smoothing capacitor (50) provided at an input portion of the bridge circuit, and a control device (40) for controlling driving of the bridge circuit An inverter (30) that converts DC power input from the DC power supply (10) to the bridge circuit into AC power and supplies the AC power to the rotating electric machine (80);
A power relay (15) that is provided between the DC power supply and the smoothing capacitor and that can shut off power supply from the DC power supply to the bridge circuit;
With
The control device includes:
A gate command unit (44) for generating a drive signal for driving gates of the plurality of switching elements of the bridge circuit; a cutoff signal to which the drive signal is input and for stopping gate driving of the plurality of switching elements of the bridge circuit; A signal switching unit (48) that outputs the drive signal to the bridge circuit when no is input, and stops the output of the drive signal when the cutoff signal is input, and operates a cutoff function of the inverter; An abnormality determining unit (45) for determining an abnormality of the shut-off function,
When the power relay is opened, the control device starts a discharge process for driving the bridge circuit to discharge the electric charge of the smoothing capacitor, and operates the cutoff function during the execution of the discharge process. When it is determined that the voltage (Vc) of the smoothing capacitor detected directly or indirectly has decreased during the operation of the cutoff function, the abnormality determination unit determines that the cutoff function is abnormal. An abnormality determination system to determine.   After the start of the discharge process, before the cutoff function operates, when it is determined that the voltage of the smoothing capacitor is maintained, the abnormality determination unit determines that the discharge function of the inverter is abnormal. The abnormality determination system according to claim 1, wherein the determination is performed. The signal switching unit operates the cutoff function based on any one or more of the input cutoff signals,
3. The abnormality determination system according to claim 1, wherein the abnormality determination unit determines an abnormality based on a voltage drop of the smoothing capacitor during a period when the operations of the plurality of cutoff signals are mutually exclusive. 4. A plurality of the inverters (301, 302);
The abnormality determination system according to any one of claims 1 to 3, wherein the control device (401, 402) of each of the inverters performs abnormality diagnosis of the discharge process and the cutoff function at different timings.   The abnormality according to claim 4, wherein the control device of each of the inverters performs the discharge process and the abnormality diagnosis of the cutoff function for each of the inverters one by one in order after the power relay is opened. Judgment system.   The control device of each of the inverters performs an abnormality diagnosis of the discharge process and the cutoff function for one or more of the inverters selected in order in response to one relay opening operation. Abnormality determination system described. A plurality of the inverters (301, 302);
A plurality of power relays (151, 152) capable of individually shutting off power supply to the bridge circuit of each inverter;
The abnormality determination system according to any one of claims 1 to 6, further comprising: A boost converter (18) provided between the DC power supply and the inverter, for boosting the voltage of the DC power supply and outputting the boosted voltage to the inverter;
The abnormality determination system according to any one of claims 1 to 7, wherein the operation of the boost converter is stopped before the abnormality diagnosis of the cutoff function is performed.

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