JP6663368B2 - Motor control device - Google Patents

Description

  The present invention relates to a motor control device having a function of diagnosing a disconnection state on a motor side.

  2. Description of the Related Art As a technique for diagnosing an open phase, that is, a disconnection state between an inverter circuit provided in a motor control device and a motor driven by the inverter circuit, a conventional technique described in Patent Document 1 is known.

  In this prior art, before starting the three-phase motor, an operation of supplying current to one phase and sinking current from the other two phases is executed for each phase, and the inverter circuit switches from the inverter circuit to the DC / DC conversion circuit for each operation. The presence or absence of an abnormality is determined by determining whether or not a DC current flows. Furthermore, after starting, when the drive current is supplied from the inverter circuit to the three-phase motor to rotate the three-phase motor, the DC current is continuously detected, and when there is no phase loss, one rotation of the motor is performed. The presence or absence of an abnormality is determined by determining the number of sawtooth peaks that appear during the cycle and decrease to two at the time of phase loss. If it is determined that there is an abnormality, the driving of the motor is temporarily stopped, the same disconnection detection processing as before the start is performed, the phase in which the open phase occurs is confirmed, and the abnormality is notified.

JP 2013-132099 A

In the above-described conventional technology, a new DC current sensor needs to be mounted in order to detect a DC current flowing from the inverter circuit to the DC / DC conversion circuit. Furthermore, since the amount of power supply to the motor is not controlled, the motor may be turned at the time of diagnosis (before traveling) at the time of startup, causing vibration, abnormal noise, or unintended traveling.
Therefore, the present invention provides a motor control device capable of diagnosing a disconnection state between a motor and an inverter circuit while controlling the amount of current using a normal current sensor installed between the motor and the inverter circuit.

To solve the above SL problem, the motor control apparatus according to the present invention includes an inverter circuit for driving a three-phase AC motor, a current sensor is provided between the three-phase AC motor and the inverter circuit is detected by the current sensor A control device that controls the inverter circuit based on the three-phase AC current value . The control device controls the high-voltage side and the low-voltage side in the second phase and the third phase before starting the three-phase AC motor. While turning on one of the arms, the other arm on the high voltage side and the low voltage side in the first phase is turned on for a predetermined time, and the three-phase AC current flowing through the three-phase AC motor is detected by the current sensor. Is detected, and while the first current is flowing through the three-phase AC motor, the high-voltage side and the low-voltage side in the first phase and the third phase are temporally continuous. One of While on the arm, the other arm of the high-voltage side and the low voltage side in the second phase only on the predetermined time, by a current sensor, a second current of the three-phase AC currents flowing through the three-phase AC motor detecting a value based on the first current value and second current value, if disconnection state between the three-phase AC motor and the inverter circuit, no abnormalities, if only the first phase is disconnected When only the second phase is disconnected, when only the third phase is disconnected, two phases of the first phase, the second phase, and the third phase are disconnected, or the first phase is disconnected. If all the phases of the second phase and the third phase are broken, only the one of them is diagnosed, and for a predetermined time, the DC input voltage of the inverter circuit is reduced so that the three-phase AC motor does not rotate. It is set according to .

According to the present invention, while one arm of the high voltage side and the low voltage side of the two phases of the AC three phases is turned on, the other of the high voltage side and the low voltage side of the other one phase is turned on. Is turned on for a predetermined time, and at this time, the disconnection state is diagnosed based on the current flowing through the three-phase AC motor. The disconnection state can be diagnosed.

  Problems, configurations, and effects other than those described above will be apparent from the following description of the embodiments.

1 is a configuration diagram of a motor control device according to a first embodiment. 6 is a flowchart illustrating a processing operation of the control device in disconnection diagnosis. It is an example of ON timing and ON time of a conduction phase. 4 shows an example of the relationship between the ON time of the upper arm of the U-phase and the V-phase and the DC input voltage in the inverter circuit. This shows the energized state of the UVW phase upper and lower arms when the U-phase and V-phase are energized. It is a circuit diagram which shows the current route at the time of U-phase conduction and V-phase conduction. 7 shows waveform examples of UVW-phase current when U-phase current and V-phase current are applied. The relationship between the diagnosis result of the disconnection state and the current of each phase when the UV phase is energized is shown. 13 shows an example of ON timing and ON time of a conducting phase at the time of disconnection diagnosis in the second embodiment. 9 shows the current of each phase when the U-phase is energized in the second embodiment.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings using Example 1 and Example 2. In each of the drawings, components having the same reference number indicate the same components or components having similar functions.

  FIG. 1 is a configuration diagram of a motor control device that is Embodiment 1 of the present invention.

  As shown in FIG. 1, in the present embodiment, the inverter circuit 200 and the battery 400 are connected to each other to form a closed circuit. Inverter circuit 200 forms a main circuit of a so-called voltage-type inverter. In the motor control device of the present embodiment, the DC power of the battery 400 is converted into AC power by the inverter circuit 200, and the motor 100 is energized by the AC power output from the inverter circuit 200. Further, as will be described later, the motor control device according to the present embodiment energizes two of the three phases of the motor 100, the U-phase and the V-phase in the present embodiment, by the inverter circuit 200. A diagnostic function is provided for determining which of the 200 phases is disconnected in a relatively short time.

  The motor 100 is a power source of a hybrid vehicle or an electric vehicle, and is a three-phase AC synchronous motor driven by three-phase AC power. In this embodiment, the motor 100 is a permanent magnet synchronous motor having a rotor provided with permanent magnets and a stator having windings for three phases of U, V and W phases. Rotational force is generated in the rotor by the interaction between the rotating magnetic field generated by the alternating current flowing through each winding and the permanent magnet magnetic flux.

  In this embodiment, the U-phase winding, the V-phase winding, and the W-phase winding of the motor 100 are connected in a Y (or star) connection.

  The inverter circuit 200 includes six semiconductor switching elements (insulated gate bipolar transistors (IGBTs) in FIG. 1), is connected in series two by two, and has upper and lower arms for three phases (U phase, V phase, W phase). Is configured. The three-phase high-voltage side and low-voltage side arms, that is, the upper and lower arms, are connected in series via the AC power supply cable 300 to the U-phase winding, the V-phase winding, and the W-phase winding of the motor 100, respectively. It is electrically connected to the winding. Both ends of the upper and lower arms are electrically connected to the battery 400 via the DC power supply cable 500. In the inverter circuit 200, a smoothing capacitor 800 is connected to the DC input side. A diode is electrically connected in anti-parallel between each semiconductor switching element (between the collector and the emitter of the IGBT in FIG. 1). This diode operates as a so-called freewheeling diode.

  In the inverter circuit 200, DC power input from the battery 400 is converted into AC power by the switching operation of the semiconductor switching element, and this AC power is output to the motor 100 from the series connection point of the upper and lower arms. Note that the smoothing capacitor 800 suppresses a change in the input-side voltage due to the switching operation, and stabilizes the operation of the inverter circuit 200.

  Battery 400 is a secondary battery such as a nickel hydrogen battery or a lithium ion battery. In this embodiment, the terminal voltage of the battery 400 is a relatively high voltage of about 100 V to 400 V.

  The control device 600 outputs a control signal (PWM signal) to a control terminal (a gate terminal of the IGBT in FIG. 1) of each semiconductor switching element in the inverter circuit 200, and controls each semiconductor switching element to control the motor. By controlling the current supplied to the motor 100, the torque and speed of the motor 100 are controlled. In the present embodiment, the control device 600 converts the iu, iv, iw into a current command value for obtaining a desired torque or speed based on the three-phase AC current values iu, iv, iw detected by the current sensor 700. Each semiconductor switching element is controlled so as to approach.

  In FIG. 1, a sensor for detecting a three-phase alternating current is represented by one current sensor 700 for simplicity.

  Further, control device 600 diagnoses a disconnection state between motor 100 and inverter circuit 200 based on three-phase AC current values iu, iv, iw detected by current sensor 700, as described later.

  The control device 600 includes an arithmetic processing device such as a microcomputer. The arithmetic processing device performs a processing operation according to a predetermined program, thereby controlling the torque and speed of the motor 100 and controlling the speed of the motor 100 and the inverter circuit 200. Diagnosis of disconnection between the two.

  Next, a description will be given of a diagnosis of disconnection between the motor 100 and the inverter circuit 200 by the control device 600 before starting the motor (that is, before starting driving of the hybrid vehicle or the electric vehicle).

  FIG. 2 is a flowchart illustrating the processing operation of the control device 600 in the disconnection diagnosis according to the present embodiment.

  In step S1000, the processing operation starts by the activation of the inverter circuit 200.

  Next, in step S1001, it is determined whether a high voltage (DC voltage) is input from the battery 400 to the inverter circuit 200. In this determination, it is determined whether the DC voltage exceeds a predetermined threshold or whether a high-voltage relay (not shown) is ON based on the ON / OFF signal of the high-voltage relay. Here, the high voltage relay is connected between the inverter circuit 200 and the battery 400. The DC voltage is detected, for example, at both ends of the smoothing capacitor 800 and input to the control device 600.

  Further, in step S1001, before the motor 100 is energized, it is determined whether the rotation speed of the motor 100 is smaller than a predetermined threshold. That is, it is determined whether it is before the motor is started, that is, before the traveling is started. The rotation speed of the motor 100 is detected by a known means such as a rotary encoder or a resolver.

  If it is determined in step S1001 that a high voltage (DC voltage) has been input to the inverter circuit 200 and that it is determined that the motor has not been started (YES in S1001), then step S1002 is executed, and so on. If not (NO in S1001), the determination processing in step S1001 is repeatedly executed.

  In step S1002, the duty of the U phase and the V phase, that is, the ON timing and the ON time according to the DC voltage are set. Then, at each current detection timing for disconnection diagnosis in one disconnection diagnosis period, U-phase energization or V-phase energization is set according to Duty. Thereby, the U-phase and the V-phase are sequentially energized in one disconnection diagnosis period. In the case of U-phase conduction, only the U-phase upper arm of the three-phase upper arms is turned on, and only the V-phase and W-phase of the three-phase lower arms are turned on. In the case of V-phase conduction, only the V-phase upper arm of the three-phase upper arms is turned on, and only the U-phase and W-phase of the three-phase lower arms are turned on. The duty is set so that the amount of current supplied to the motor is such that the state before the motor 100 is started is maintained. Thereby, at the time of disconnection diagnosis, rotation of the motor is suppressed, and vibration, abnormal noise, unintended running, and the like are prevented.

  Next, in step S1003, it is determined whether or not the absolute values of the U-phase, V-phase, and W-phase current values iu, iv, and iw exceed a predetermined threshold in order to detect the presence or absence of a disconnection. If it is determined that the absolute value of any of the current values iu, iv, iw exceeds any of the predetermined thresholds (YES in S1003), that is, if it is estimated that there is no disconnection, then step S1004 is executed. Is done. If it is determined that the absolute values of all the current values do not exceed the threshold (NO in S1003), that is, if it is estimated that there is a disconnection, step S1005 is executed next.

  In step S1004, among the OK flag counters vCnt_iu, vCnt_iv, and vCnt_iw for each phase, the counter of the phase for which it is determined in step S1003 that the absolute value of the current value exceeds the predetermined threshold is incremented. That is, in this step S1004, the number of times that power is supplied, that is, the number of times that it is estimated that there is no disconnection, is counted in one disconnection diagnosis period for each phase. After step S1004 has been executed, step S1005 is next executed.

  In step S1005, the energization time counter vCnt_Ripoff is incremented. The elapsed time of the current detection, that is, the disconnection diagnosis, is monitored by the count value of the energization time counter. After step S1005 has been executed, step S1006 is next executed.

  In step S1006, it is determined whether the energization time counter vCnt_Ripoff exceeds a predetermined threshold. That is, it is determined whether one disconnection diagnosis period has ended. When it is determined that the energization time counter vCnt_Ripoff exceeds a predetermined threshold (YES in step S1006), step S1007 is executed next. Further, when it is determined that it does not exceed (NO in step S1006), that is, when it is determined that the disconnection diagnosis period is still in progress, the process returns to step S1002, and the processes after step S1002 are repeatedly executed.

  In step S1007, based on the count value of the OK flag counter for each phase, a disconnection state, that is, whether there is an abnormality or a disconnected phase is determined. First, when all of the OK flag counters vCnt_iu, vCnt_iv, and vCnt_iw are equal to or greater than a predetermined threshold, it is determined that there is no abnormality (no disconnection of all phases), assuming that all three phases are energized. Next, when only vCnt_iu is smaller than the threshold, it is determined that only the U-phase is not energized, and it is determined that the U-phase is open (U-phase disconnection). Similarly, if only vCnt_iv is smaller than the threshold, it is determined that only the V phase is not energized, and it is determined that the V phase is open (V phase disconnection). If only vCnt_iw is smaller than the threshold value, it is determined that only the W phase is not energized, and it is determined that the W phase is open (W phase disconnection). In step S1007, if the count value of the OK flag counter is not any of the above cases, it is determined that two or three phases (all phases) of the U, V, and W phases are not energized, and It is determined that the phase or three-phase is open (two-phase or three-phase disconnection).

  FIG. 3 is an example of the ON timing and ON time of the energized phase set in step S1002 in FIG.

  In the example of FIG. 3, the U phase is turned on at Timing = 0 [ms], is kept turned on for an ON time of 0.1 ms (100 μs), and is then turned off. The V-phase is turned on 5 ms after the U-phase is turned on (Timing = 5 [ms] in FIG. 3), is kept on for 0.1 ms (100 μs), and is then turned off. The U-phase ON period is an ON period of the semiconductor switching element of the U-phase upper arm, that is, a period in which an ON signal is supplied to the control terminal (the gate terminal of the IGBT in this embodiment) of the semiconductor switching element. The V-phase ON period is an ON period of the semiconductor switching element of the V-phase upper arm, that is, a period in which an ON signal is given to the control terminal (the IGBT gate terminal in this embodiment) of the semiconductor switching element. Further, as shown in FIG. 3, the W phase is not turned on.

  Note that a circulating current may flow even after the U and V phase upper arms are turned off. Therefore, in the present embodiment, the ON period of the upper arm and the period in which the circulating current flows after the OFF state flow are both energized. In the present embodiment, as shown in FIG. 3, the time when the U-phase is energized and the time when the V-phase is energized are about 5 ms. Therefore, the ON times of the U-phase and the V-phase are shorter than when the U-phase is energized and when the V-phase is energized, respectively.

  FIG. 4 shows an example of the relationship between the ON time of the upper arm of the U-phase and the V-phase and the DC input voltage (DC voltage) in the inverter circuit in the present embodiment.

  As shown in FIG. 4, in the present embodiment, in order to suppress the amount of energization to the U and V phases to a predetermined amount, for example, about 20 Arms, the ON time becomes shorter as the DC voltage increases. The ON time is set. As a result, the amount of energization to the U and V phases is set so that the motor 100 does not rotate, that is, the amount of energization that maintains the state before the motor 100 is started. Rotation is suppressed, and vibration, abnormal noise, and unintended running are prevented.

  FIG. 5 shows the energized state of the UVW-phase upper and lower arms when the U-phase and the V-phase are energized.

  As shown in FIG. 5, when the U-phase is energized, the U-phase upper arm is turned on and then turned off (see FIG. 3), but the VW-phase upper arm is kept off. When the U-phase is energized, the UVW-phase lower arm is maintained in the OFF state, the ON state, and the ON state, respectively (the ON / OFF state of the lower arm is omitted in FIG. 3 described above).

  Further, as shown in FIG. 5, when the V-phase is energized, the V-phase upper arm is turned on and then turned off (see FIG. 3), but the U-phase upper arm is kept off. When the V-phase is energized, the UVW-phase lower arm is maintained in the ON state, the OFF state, and the ON state, respectively.

  FIG. 6 is a circuit diagram showing current routes when the U-phase is energized (when the U-phase upper arm UH is ON) and when the V-phase is energized (when the V-phase upper arm VH is ON) shown in FIG. is there.

  As shown in FIG. 6, when the U-phase upper arm UH is turned on during the U-phase conduction, the V-phase lower arm VL and the W-phase lower arm WL are turned on. Cable, U-phase winding (resistance, inductance), V-phase winding, V-phase power supply cable, route that follows the V-phase lower arm VL, and U-phase upper arm UH, U-phase power supply cable, U-phase A current (iu, iv, iw) flows through a path that sequentially follows the winding, the W-phase winding, the W-phase power supply cable, and the W-phase lower arm WL. When the U-phase upper arm UH is turned off, the current is commutated from the U-phase upper arm UH to the U-phase lower arm UL (reflux diode), and the current flows while attenuating due to the energy accumulated in the inductance of the winding. to continue.

  Also, as shown in FIG. 6, when the V-phase upper arm VH is turned on during the V-phase conduction, the U-phase lower arm UL and the W-phase lower arm WL are on, so that the V-phase upper arms VH, V Phase feeding cable, V-phase winding, U-phase winding, U-phase feeding cable, path for sequentially tracing the U-phase lower arm UL, and V-phase upper arm VH, V-phase feeding cable, V-phase winding, A current (iu, iv, iw) flows through a path that sequentially follows the W-phase winding, the W-phase power supply cable, and the W-phase lower arm WL. When the V-phase upper arm UH is turned off, the current is commutated from the V-phase upper arm VH to the V-phase lower arm VL (reflux diode) and flows while attenuating due to the energy accumulated in the winding inductance. to continue.

  Here, between the inverter circuit and the motor, if any one or more of the UVW phases is disconnected and becomes an open state, one or more of the above-described current paths are disconnected. A phase in which no current flows occurs. As will be described later, and as can be seen from FIG. 6, the phase in which the current flows and the phase in which the current does not flow differ depending on the disconnection state and whether the U-phase or V-phase current is applied. For this reason, since the count value of the OK flag counter in FIG. 2 (step S1004) is different for each phase, the disconnection state can be diagnosed as in step S1007 in FIG.

  FIG. 7 shows a waveform example of the UVW-phase current when the U-phase is energized and the V-phase is energized at the timing shown in FIG.

  As shown in FIG. 7, from the time the U-phase upper arm UH is turned on to the time it is turned off, that is, during the ON time of the U-phase upper arm UH (for example, 100 μs), each current of the UVW phase (the U-phase current is positive, The absolute value of (VW phase current is negative) rises sharply and increases to the peak value. After the U-phase upper arm UH is turned off, the UVW-phase currents continue to flow while attenuating.

  Here, the positive current is a current flowing from the inverter circuit toward the motor. The negative current is a current flowing from the motor toward the inverter circuit.

  Further, as shown in FIG. 7, 5 ms after the U-phase upper arm UH is turned on, the U-phase current is switched to the V-phase current. At this time, from the time the V-phase upper arm VH is turned on to the time it is turned off, that is, during the ON time (for example, 100 μs) of the V-phase upper arm VH, each UVW-phase current (the V-phase current is positive and the UW-phase current is The absolute value of (negative) rises sharply and increases to the peak value. After the U-phase upper arm UH is turned off, the UVW-phase currents continue to flow while attenuating.

  As shown in FIG. 7, the U-phase energization, the W-phase energization, and the current detection during each energization are executed temporally continuously, so that the time required for disconnection diagnosis can be reduced. For example, according to the study of the present inventor, the total energization time can be within 20 ms, so the disconnection diagnosis time can be within 20 ms. As described above, according to the present embodiment, since the disconnection diagnosis can be performed in a short time, the disconnection diagnosis can be performed without causing the driver to feel a delay before the traveling starts after the vehicle is started. .

  FIG. 8 shows the relationship between the diagnosis result of the disconnection state shown in FIG. 2 (step S1007) and the current of each phase when the UV phase is energized. The notations “X” and “Y” in the figure indicate that a current is flowing. The notation “0” indicates that no current is flowing. Note that “X” indicates a current value (for example, about 20 Arms) according to the setting of the ON time shown in FIG. 2 (step S1002) and FIG. “Y” indicates a predetermined current value equal to or less than X.

  As shown in FIG. 8, the seven disconnection states (Case 1-7 including “No disconnection” (No Open)) correspond to the diagnosis result of the disconnection state shown in FIG. 2 (step S1007), that is, “No abnormality”, “U-phase open” (only U-phase is broken), “V-phase open” (only V-phase is broken), “W-phase open” (only W-phase is broken), “2,3 phase open” (2 of UVW phases) Phase or three phases (all phases) correspond to disconnection).

  For example, in FIG. 8, when the U-phase is disconnected (Case 2, 5, 6), if only the U-phase is energized (U-phase H side), in each case, each current of the UVW phase is “0”. Therefore, it is not possible to distinguish between “U-phase only disconnection” (Case 2) and “2-phase or 3-phase disconnection” (Case 5, 6). On the other hand, if the V-phase energization (V-phase H side) is further executed, as can be seen from FIG. 8, "U-phase only disconnection" (Case 2) and "2-phase or 3-phase disconnection" (Case 5, 6) ), The flow of each current of the UVW phase is different. As a result, by executing both the U-phase energization and the V-phase energization, it is possible to distinguish between “U-phase only disconnection” and “2-phase or 3-phase disconnection”. In addition, in the case of “V phase only disconnection” and “W phase only disconnection”, it can be similarly identified as “two phase or three phase disconnection”.

  As described above, the flow of each current of the UVW phase differs between the case where only one phase of the UVW phase is broken and the case where 2 or 3 phase is broken. Accordingly, since the count value of the OK flag counter in FIG. 2 (step S1004) is different for each phase, disconnection diagnosis can be performed by the processing in FIG.

  In FIG. 8, when "UW phase disconnection" (Case 6) is V-phase energized (V-phase H side) and when "VW phase disconnection" (Case 7) is U-phase energized (U-phase H side), energization is performed. A current (X) flows through the phase, and no current flows through the other two phases. This is because a current flows between the winding of the motor 100 and a virtual ground point (virtual neutral point) (not shown) via a stray capacitance in the motor (see FIG. 10 (Case 7 described later)). )). Therefore, in the present embodiment, Cases 1, 2, 3, 4, 5, 6, and 7 in FIG. 8 can be identified by executing U-phase energization and V-phase energization.

  In the present embodiment, the current is detected when the U-phase is energized and when the V-phase is energized. However, the present invention is not limited to this. When the U-phase and the W-phase are energized, or when the V-phase and the W-phase are energized. The current at that time may be detected. The current of each phase may be detected by a current sensor provided for each phase, or a current sensor may be provided for two phases of the UVW phase, and the remaining one of the two phases may be calculated from the detected current values of the two phases. The phase current value may be calculated.

  Further, in the present embodiment, as shown in FIG. 5, the U-phase upper arm and the V-phase upper arm are turned ON / OFF when the U-phase is energized and the V-phase is energized, respectively. The V-phase lower arm may be turned ON / OFF. However, according to the ON / OFF state of FIG. 5, when the U-phase lower arm is ON / OFF, the VW-phase upper arm is ON, and when the V-phase lower arm is ON / OFF, the UW-phase upper arm is ON. Such a point is not limited to the UV-phase energization but also applies to the UW-phase energization and the VW-phase energization.

  As described above, according to the motor control device of the first embodiment, the disconnection between the motor and the inverter circuit is performed while suppressing the amount of current by using the current sensor used between the motor and the inverter circuit and used for motor control. Can be detected.

  In addition, since only two of the three phases are energized and energized continuously in time, the time required for disconnection diagnosis can be reduced.

  Also, as shown in FIG. 2, in one disconnection diagnosis period, the current is detected a plurality of times, the number of times the current value exceeds a predetermined threshold is counted, and the disconnection state is diagnosed based on this number. Erroneous diagnosis resulting from erroneous detection due to noise or the like is prevented. Therefore, the accuracy of diagnosis is improved.

  FIG. 9 shows an example of the ON timing and ON time of the conducting phase at the time of disconnection diagnosis in the motor control device according to the second embodiment of the present invention.

  In the second embodiment, as shown in FIG. 9, the energization by the inverter circuit differs from the first embodiment (FIG. 3) only in the U-phase.

  In the second embodiment, the configuration of the motor control device, the processing operation of the control device in detecting disconnection, the relationship between the ON time of the upper arm of the U-phase when the U-phase is energized and the DC input voltage in the inverter circuit, The current state of the upper and lower arms of the UVW phase, the current route when the U phase is energized, and the waveform of the UVW phase current when the U phase is energized are shown in FIG. 1, FIG. 2, FIG. 4, and FIG. 6, FIG. 6 and FIG.

  Hereinafter, differences from the first embodiment will be described.

  As shown in FIG. 9, the U phase is turned on at Timing = 0 [ms], is kept turned on for an ON time of 0.1 ms (100 μs), and is then turned off. The U-phase ON period is an ON period of the semiconductor switching element of the U-phase upper arm, that is, a period in which an ON signal is supplied to the control terminal (the gate terminal of the IGBT in this embodiment) of the semiconductor switching element.

  Note that the V phase and the W phase are not turned on. That is, the V-phase and W-phase upper-arm semiconductor switching elements are not turned on (for the lower arm, see FIG. 5).

  FIG. 10 shows the current of each phase when the U-phase is energized in the second embodiment.

  As shown in FIG. 10, in the second embodiment, the disconnection state can be diagnosed similarly to the first embodiment. Regarding the diagnosis of the disconnection state, "No abnormality" (Case 1), "V-phase only disconnection" (Case 3), "W-phase only disconnection" (Case 4), "U-phase only disconnection, or 2 or 3 phase" Disconnection ”(Case 2, 5-7) can be identified.

  Instead of energizing only the U-phase, energizing only the V-phase or energizing only the W-phase can be used.

  In the second embodiment, the upper arm of the U-phase is turned on for a predetermined ON time during the energization of only the U-phase (the lower arm turns on the VW phase). May be turned ON for a predetermined ON time (the upper arm turns ON the VW phase). The same applies to energization of only the V phase or energization of only the W phase.

  As described above, according to the motor control device of the second embodiment, similarly to the first embodiment, the disconnection between the motor and the inverter circuit is detected using the current sensor used for motor control while suppressing the amount of current supply. it can. Also, since only one of the three phases is energized, the time required for disconnection diagnosis can be reduced. As in the first embodiment, during one disconnection diagnosis period, the current is detected a plurality of times, the number of times the current value exceeds a predetermined threshold is counted, and the disconnection state is diagnosed based on the number of times. As a result, an erroneous diagnosis caused by an erroneous detection due to the above is prevented. Therefore, the accuracy of diagnosis is improved.

  Note that the present invention is not limited to the above-described embodiment, and includes various modifications. For example, the above-described embodiments have been described in detail for easy understanding of the present invention, and are not necessarily limited to those having all the configurations described above. Further, for a part of the configuration of each embodiment, it is possible to add, delete, or replace another configuration.

  For example, the control lines and signal lines in the figure indicate those which are considered necessary for explanation, and do not necessarily indicate all control lines and signal lines in a product.

100: Motor 200: Inverter circuit 300: AC power supply cable 400: Battery 500: DC power supply cable 600: Control device 700: Current sensor 800: Smoothing capacitor

Claims (2)

An inverter circuit for driving a three-phase AC motor;
A current sensor provided between the three-phase AC motor and the inverter circuit;
A control device that controls the inverter circuit based on a three-phase AC current value detected by the current sensor ;
In a motor control device comprising:
The control device includes:
Before starting the three-phase AC motor, one of the high voltage side and the low voltage side in the second phase and the third phase is turned on, and the high voltage side and the low voltage side in the first phase are turned on. The other arm is turned on for a predetermined time, and the current sensor detects a first current value of the three-phase AC current flowing through the three-phase AC motor,
Further, while the three-phase AC current for detecting the first current value is flowing through the three-phase AC motor, the three-phase AC motor is temporally continuous.
The other of the high voltage side and the low voltage side in the second phase is turned on while turning on the one arm of the high voltage side and the low voltage side in the first phase and the third phase. Is turned on for the predetermined time, and the current sensor detects a second current value of the three-phase AC current flowing through the three-phase AC motor,
Based on the first current value and the second current value , a disconnection state between the three-phase AC motor and the inverter circuit ,
If there is no abnormality,
When only the first phase is disconnected,
When only the second phase is disconnected,
When only the third phase is disconnected,
Either the first phase, the second phase, and the third phase are disconnected, or all of the first phase, the second phase, and the third phase are disconnected. If so,
Diagnose only which of
The motor control device , wherein the predetermined time is set according to a DC input voltage of the inverter circuit so that the three-phase AC motor does not rotate . The motor control device according to claim 1,
The control device includes:
A motor control device, wherein the number of times the absolute value of the first current value exceeds a predetermined threshold value is counted, and the disconnection state is diagnosed based on the counted number.

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