JP2016067079A - Controller for motor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a controller for a motor capable of discriminating that an abnormality occurs in the motor at the time of phase difference control.SOLUTION: The controller operates an application voltage of an armature coil of the motor by operating an inverter in such a manner that a power factor angle ξr which is a phase difference is controlled into target power factor angle ξ*. The controller includes a fail discrimination part 30j for discriminating that the abnormality occurs in the motor when a power factor angle ξ exceeds an upper limit threshold and the power factor angle ξr is below a lower limit threshold. The upper limit threshold is adapted on the basis of a normalization ratio parameter corresponding to a current phase in which the abnormality of the motor occurs in the case where a current phase is changed to an advanced angle side. The lower limit threshold is adapted on the basis of the normalization ratio parameter corresponding to the current phase in which the abnormality of the motor occurs in the case where a current phase is changed to a delayed angle side. The normalization ratio parameter is a value which is obtained by standardizing a ratio parameter that is a ratio of a rate of change of the power factor angle in a rate of change of the phase current with a maximum value.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a control device for an electric motor.

  Conventionally, as can be seen in Patent Document 1 below, sensorless drive that performs phase difference control for controlling the phase difference between the applied voltage of the armature winding constituting the motor and the current flowing through the armature winding to the target value. Control devices are known. This control device has a function of detecting the occurrence of a start abnormality of the motor when the motor is started. Specifically, when the control device detects the phase difference at the start abnormality determination timing and determines that the detected phase difference is not within a preset range, it determines that a start abnormality has occurred in the motor. .

JP 2009-254191 A

  Here, the abnormality of the electric motor can occur not only at the time of starting but also at the time of sensorless control after starting. For this reason, the technique which determines the presence or absence of abnormality of an electric motor at the time of sensorless control after starting is desired.

  The main object of the present invention is to provide a motor control device that can determine that an abnormality has occurred in the motor during sensorless control after startup.

  Hereinafter, means for solving the above-described problems and the operation and effects thereof will be described.

  The present invention is applied to a system including an electric motor (10) and a power conversion circuit (20) capable of applying an AC voltage to the electric motor, and an applied voltage of an armature winding (10u to 10w) constituting the electric motor. And a phase difference calculating means (30a) for calculating a phase difference between the current flowing through the armature winding and the power conversion circuit for controlling the phase difference calculated by the phase difference calculating means to the target value. When the phase difference calculated by the operating means (30b-30i) operating the applied voltage of the armature winding by the operation of the phase difference calculating means exceeds the upper limit threshold, the phase difference is the lower limit An abnormality determining means (30j) for determining that an abnormality has occurred in the electric motor when it is below a threshold, and the phase difference with respect to a change amount of a current phase that is a phase of a current flowing through the armature winding The ratio of the amount of change is a ratio parameter, the current phase region in which the phase difference is uniquely determined with respect to the current phase is a monotone change region, the ratio parameter in the monotone change region is the ratio parameter in the monotone change region The upper limit threshold corresponds to the current phase at which the abnormality of the motor has occurred when the current phase is changed to the advance side in the monotonic change region. Preliminarily adapted based on the normalized ratio parameter, and the lower threshold corresponds to the current phase at which the abnormality of the motor has occurred when the current phase is changed to the retard side in the monotonic change region It is preliminarily adapted based on the normalized ratio parameter.

  There is a monotonic change region that is a current phase region that is determined according to the driving state of the electric motor and that is a current phase region in which the phase difference is uniquely determined with respect to the current phase. The phase difference control for controlling the phase difference to the target value is established on the condition that the actual current phase is in the monotonous change region. For this reason, if the actual current phase goes out of the monotonic change region or near the boundary value of that region even within the monotone change region, the controllability of the phase difference is greatly reduced, and the motor step-out There is a risk that the motor will be abnormal.

  Here, the inventors defined the ratio parameter, and further defined the normalized ratio parameter using the ratio parameter. The normalized ratio parameter is smaller when the current phase is near the advance side and retard side boundary values of the monotone change region than when the current phase is near the center of the monotone change region. Further, the phase difference control can be normally executed in the vicinity of the center, and there is a possibility that the abnormality of the electric motor may occur in the vicinity of the boundary value. For this reason, the normalization ratio parameter can be used for adapting the threshold value for abnormality determination.

  Therefore, in the above invention, the upper limit threshold used for abnormality determination is pre-adapted based on the normalized ratio parameter corresponding to the current phase in which the abnormality of the motor occurs when the current phase is changed to the advance side in the monotonic change region. To do. Further, based on the normalized ratio parameter corresponding to the current phase in which the abnormality of the motor occurs when the current phase is changed to the retard side in the monotonous change region, the lower limit threshold value used for the abnormality determination is adapted in advance. Using the upper and lower threshold values thus adapted, the abnormality determination means can determine that an abnormality has occurred in the motor during sensorless control after startup.

The whole block diagram of a vehicle-mounted motor control system. The functional block diagram of the motor control in a control apparatus. The figure which shows the phase difference of a phase voltage and a phase current. The figure which shows a power factor angle map, an advance angle side map, and a retard angle side map. The flowchart which shows the procedure of the abnormality determination process of a motor. The figure for demonstrating the various parameters in a dq coordinate system. The figure which shows the calculation result of the relationship between an electric current phase and a power factor angle. The figure which shows the experimental result which investigated the electric current phase in which abnormality of a motor generate | occur | produces. The figure which shows the experimental result which investigated the normalization ratio parameter which motor abnormality generate | occur | produces. The figure for demonstrating the calculation method of a normalization ratio parameter. The figure which shows the calculation result of the relationship between a power factor angle and a normalization ratio parameter.

  Hereinafter, an embodiment in which a control device according to the present invention is applied to an in-vehicle motor control system will be described with reference to the drawings.

  As shown in FIG. 1, the motor control system includes a motor 10, an inverter 20 as a “power conversion circuit”, and a control device 30 that controls the motor 10. In the present embodiment, the motor 10 is used to drive a vehicle interior fan that constitutes the vehicle-mounted air conditioner or the vehicle-mounted radiator fan. In the present embodiment, the motor 10 is a three-phase synchronous motor including a permanent magnet.

  The motor 10 includes U, V, and W phase windings 10u, 10v, and 10w that are armature windings. The motor 10 is connected to a DC power source 21 (for example, a battery) via an inverter 20. The inverter 20 includes a series connection body of upper arm switches Sup, Svp, Swp and lower arm switches Sun, Svn, Swn. One end of the U-phase winding 10u is connected to the connection point of the U-phase upper and lower arm switches Sup and Sun, and one end of the V-phase winding 10v is connected to the connection point of the V-phase upper and lower arm switches Svp and Svn. Are connected, and one end of the W-phase winding 10w is connected to the connection point of the W-phase upper and lower arm switches Swp and Swn. Incidentally, in the present embodiment, a voltage control type semiconductor switching element is used as each of the switches Sup to Swn, and more specifically, a MOS-FET is used. And each freewheel diode Dup-Dwn is connected to each switch Sup-Swn in antiparallel. Each of the free wheel diodes Dup to Dwn may be a MOS-FET body diode or an external diode.

  The motor control system includes a phase current sensor 22 and a bus current sensor 23. In the present embodiment, the phase current sensor 22 detects the phase current of the motor 10. The bus current sensor 23 detects a current flowing through an electrical path connecting the emitters of the lower arm switches Sun, Svn, and Swn and the negative terminal of the DC power source 21. In the present embodiment, the phase current sensor 22 and the bus current sensor 23 are configured to include resistors.

  The control device 30 is mainly composed of a microcomputer, and operates the inverter 20 so as to feedback control the control amount (rotation speed in the present embodiment) of the motor 10 to its command value (hereinafter, command rotation speed ω *). Specifically, the control device 30 generates and generates operation signals gup to gwn corresponding to the switches Sup to Swn based on the detection values of the various sensors in order to turn on and off the switches Sup to Swn constituting the inverter 20. The operation signals gup to gwn thus output are output to the switches Sup to Swn. Here, the upper arm operation signals gup, gvp, gwp and the corresponding lower arm operation signals gun, gvn, gwn are complementary signals (signals whose logics are inverted). That is, the upper arm switch and the corresponding lower arm switch are alternately turned on. The command rotational speed ω * is, for example, a control device provided outside the control device 30 and is input to the control device 30 from a control device higher than the control device 30.

  Next, motor phase difference control executed by the control device 30 will be described with reference to FIG. The control according to the present embodiment is sensorless sine wave drive control.

  The phase difference calculation unit 30a will explain the U phase. Based on the U phase current Ir detected by the phase current sensor 22 and the voltage phase Vθr output from the voltage phase calculation unit 30b described later, the phase difference calculation unit 30a has a sinusoidal U shape. A phase difference (hereinafter, power factor angle ξr) between phase current Ir and sinusoidal U-phase voltage Vr is calculated. In the present embodiment, as shown in FIG. 3A, the power factor angle ξr when the U-phase voltage Vr is advanced with respect to the U-phase current Ir (the phase is advanced) is a positive value. The power factor angle ξr when the angle is retarded (the phase is delayed) is represented by a negative value. 3A shows the transition of the U-phase voltage Vr and the U-phase current Ir, and FIG. 3B shows the transition of the interlinkage magnetic flux φ of each phase winding 10u to 10w. Incidentally, in the phase difference calculation unit 30a, the processing for the V and W phases can be performed in the same manner as the processing for the U phase. In the present embodiment, the power factor angle ξr is calculated based on the detection value of the phase current sensor 22, but the present invention is not limited to this. For example, without providing the phase current sensor 22 in the control system, the phase current is estimated based on the bus current IDC detected by the bus current sensor 23 and the switching mode, and the estimated phase current is calculated as the power factor angle ξr. You may use for.

  The power factor angle setting unit 30c variably sets a target power factor angle ξ * that is a target value of the power factor angle ξr. In the present embodiment, a power factor angle map (see FIG. 4) in which the command rotational speed ω *, the estimated torque Trq, and the target power factor angle ξ * are related is a storage unit (not shown) provided in the control device 30. Is remembered. The power factor angle setting unit 30c receives the command rotational speed ω * and the estimated torque Trq, and variably sets the target power factor angle ξ * using a power factor angle map. In the present embodiment, the estimated torque Trq is calculated by subjecting the bus current IDC detected by the bus current sensor 23 to low-pass filter processing and torque-converting the bus current IDC subjected to low-pass filter processing in the filter unit 30d. To do.

  The power factor deviation calculation unit 30e calculates a power factor deviation Δξ that is a deviation between the target power factor angle ξ * output from the power factor angle setting unit 30c and the power factor angle ξr output from the phase difference calculation unit 30a. To do. Specifically, the power factor deviation Δξ is calculated by subtracting the power factor angle ξr from the target power factor angle ξ *.

  The first controller 30f calculates a correction amount Δω as an operation amount for performing feedback control of the power factor angle ξr to the target power factor angle ξ * based on the power factor deviation Δξ. In the present embodiment, the correction amount Δω is calculated by proportional-integral control based on the power factor deviation Δξ.

  The adder 30g calculates the corrected rotational speed ωb by adding the correction amount Δω to the command rotational speed ω *. The voltage phase calculation unit 30b calculates the voltage phase Vθr as a time integral value of the corrected rotation speed ωb output from the addition unit 30g. The voltage phase Vθr is the phase of the armature voltage vector applied from the inverter 20 to each phase winding 10u, 10v, 10w. This voltage vector will be described later with reference to FIG.

  The second controller 30h calculates a voltage amplitude Vmod as an operation amount for feedback control of the power factor angle ξr to the target power factor angle ξ * based on the power factor deviation Δξ. In the present embodiment, the voltage amplitude Vmod is calculated by proportional-integral control based on the power factor deviation Δξ. The voltage amplitude Vmod is the magnitude of the voltage vector.

  The sine wave calculation unit 30i has the U, V, and W phases of the motor 10 that are sine waves that are 120 ° out of phase with each other at the electrical angle of the motor 10, as represented by the following equation (eq1) , W-phase command voltages Vu *, Vv *, and Vw * are generated and operation signals gup to gwn are generated and output to the inverter 20.

Here, the operation signals gup to gwn may be generated by PWM processing based on the magnitude comparison between the sine wave data represented by the above equation (eq1) and a carrier signal such as a triangular wave. The switches Sup to Swn are applied based on the operation signals gup to gwn so that the U, V, and W phase command voltages Vu *, Vv *, and Vw * are applied to the U, V, and W phase windings 10u, 10v, and 10w. Is turned on / off to control the rotational speed of the motor 10 to the command rotational speed ω *.

  The failure determination unit 30j determines whether or not an abnormality has occurred in the motor 10 based on the power factor angle ξr, the command rotational speed ω *, and the estimated torque Trq output from the phase difference calculation unit 30a. I do. When the failure determination unit 30j determines that an abnormality has occurred, the failure determination unit 30j instructs the sine wave calculation unit 30i to stop generating the operation signals gup to gwn by outputting the failure signal FL. Thereby, the motor 10 is stopped.

  In the present embodiment, the abnormality of the motor 10 includes step-out (out of synchronization) of the motor 10, an excess current abnormality of the motor 10, an undercurrent abnormality, oscillation, and the like. The excess current abnormality occurs, for example, in a state where a large load acts on the motor 10 and rotation of the motor 10 is stopped. Oscillation is when the motor 10 repeats forward and reverse rotation.

  FIG. 5 illustrates the abnormality determination process performed by the fail determination unit 30j. This process is repeatedly executed at a predetermined processing cycle, for example.

  In this series of processing, first, in step S10, the upper limit threshold value ξHi and the lower limit threshold value ξLo are variably set based on the command rotational speed ω * and the estimated torque Trq. Here, as shown in FIG. 4, the upper limit threshold value ξHi is set using a retard angle side map in which the command rotational speed ω *, the estimated torque Trq, and the upper limit threshold value ξHi are related. Further, the lower limit threshold value ξLo is set using an advance side map in which the command rotational speed ω *, the estimated torque Trq, and the lower limit threshold value ξLo are related. The retard side map and the advance side map are stored in the storage means of the control device 30. A method for fitting the upper threshold ξHi and the lower threshold ξLo will be described in detail later.

  In the subsequent step 11, the logical sum of the condition that the power factor angle ξr output from the phase difference calculation unit 30a exceeds the upper limit threshold value ξHi and the condition that the power factor angle ξr is less than the lower limit threshold value ξLo is true. Determine whether or not. This process is a process for determining whether or not an abnormality has occurred in the motor 10.

  If it is determined in step S11 that the power factor angle ξr is equal to or less than the upper limit threshold ξHi and equal to or greater than the lower limit threshold ξLo, the process proceeds to step S12 to determine that the motor 10 is normal. On the other hand, if an affirmative determination is made in step S10, the process proceeds to step S13 to determine that an abnormality has occurred in the motor 10. Then, a fail signal FL is output to the sine wave calculation unit 30i.

  Next, an adaptation method for the upper limit threshold value ξHi and the lower limit threshold value ξLo will be described.

  First, each parameter used in the description of the adaptation method will be described with reference to FIG. In FIG. 6, the magnetic pole direction of the rotor constituting the motor 10 is the d axis, and the direction orthogonal to the d axis is the q axis.

  In FIG. 6, “Vn” represents an armature voltage vector applied from the inverter 20 to each phase winding 10u, 10v, 10w, “Vθ” represents a voltage phase of the voltage vector Vn with respect to the q axis, and “Va "Indicates the voltage amplitude of the voltage vector Vn. “In” indicates an armature current vector flowing through each phase winding 10u, 10v, 10w, “β” indicates the current phase of the current vector In with respect to the q axis, and “Ia” indicates the magnitude of the current vector In. The current amplitude is shown. “Ξ” indicates a power factor angle. The voltage phase Vθ and the current phase β are an advance angle when rotated counterclockwise from the q axis, a retard angle when rotated clockwise from the q axis, and 0 ° when coincident with the q axis. The voltage vector Vn can be represented by d and q-axis voltages Vd and Vq, and the current vector In can be represented by d and q-axis currents Id and Iq.

  Next, the adaptation method will be described. This adaptation method is based on a normalized ratio parameter described later. Specifically, the voltage equation of the brushless synchronous motor is expressed by the following equation (eq2).

In the above equation (eq2), “Ld, Lq” represents d and q axis inductance, “Ra” represents winding resistance, “ω” represents the electrical angular velocity of the motor, and “φa” represents the flux linkage. “P” indicates a differential operator. In the above equation (eq2), the following equation (eq3) is derived by assuming the steady state and excluding the transient term.

From the above equation (eq3) and the following equation (eq4), the following equation (eq5) representing the voltage phase Vθ is derived.

Using the above equation (eq5), the power factor angle ξ is expressed by the following equation (eq6).

The above equation (eq6) indicates that there is a correlation between the power factor angle ξ and the current phase β. FIG. 7 shows calculation results of the current phase β and the power factor angle ξ when the torque of the motor having a positive correlation with the current amplitude Ia is set to various values T1 to T5. According to FIG. 7, the power factor angle ξ decreases as the current phase β moves toward the advance side with respect to the reference phase (0 ° is exemplified) as the reference current phase β, and then the current phase β As the lead angle advances, the power factor angle ξ increases. On the other hand, the power factor angle ξ increases as the current phase β moves toward the retard side, and thereafter, the power factor angle ξ decreases with the delay of the current phase β. That is, in each of the calculation results of each torque, a region in which the power factor angle ξ monotonously decreases as the current phase β moves toward the advance side (in other words, a proportional relationship is established between the current phase β and the power factor angle ξ). There is a monotonic change region that is a region. In the monotonous change region, the power factor angle ξ is uniquely determined with respect to the current phase β. The phase difference control is a control that is established on the condition that the current phase β is in the monotonous change region.

  Here, an absolute value of a value obtained by dividing the change amount of the current phase β by the change amount of the power factor angle ξ is defined as a ratio parameter. In the monotonous change region, the ratio parameter tends to be smaller as the current phase β is advanced or retarded with respect to the reference phase. In the current phase region where the ratio parameter is small (in the vicinity of the boundary value of the monotonic change region), the controllability of the phase difference is greatly reduced, and there is a possibility that the abnormality of the motor 10 such as step out occurs. In particular, in this embodiment, the phase difference cannot be controlled in the current phase region where the ratio parameter is zero.

  FIG. 8 shows the current phase β when the motor abnormality occurs when the current phase β is changed from the reference phase (for example, 0 °) to the advance side and the retard side while performing the phase difference control. It is the experimental result investigated in relation to each of torque. Here, in FIG. 8, the current phase β where the motor abnormality has occurred is shown as a step-out point “×”. In FIG. 8, the absolute value of the current phase β to be investigated for motor abnormality is within 90 °. This is because if the absolute value of the current phase β exceeds 90 °, the positive / negative of the torque of the motor 10 is reversed.

  As shown in the figure, even when the rotational speed and torque are set to various values, a motor abnormality occurs in the current phase β shifted by substantially the same phase from the reference phase to the advance side and the retard side. .

  FIG. 9 shows the experimental results shown in FIG. 8 arranged using the normalized ratio parameter Sth. Specifically, FIG. 9 shows the normalized ratio parameter Sth corresponding to the current phase where the motor abnormality has occurred when the current phase β is changed. FIGS. 9A to 9C correspond to FIGS. 8A to 8C. Here, the normalized ratio parameter Sth is normalized by the ratio parameter “Δβ0 / Δξ0” in the monotonic change region with the maximum ratio parameter “Δβmax / Δξmax” in the monotone change region, as shown in the following equation (eq7). It is the value that was done.

A method for calculating the normalized ratio parameter Sth corresponding to the current phase in which the motor abnormality has occurred will be described with reference to FIG. FIG. 10 shows an example in which the normalization ratio parameter is maximum “Δβmax / Δξmax” in the vicinity of the reference phase.

  FIG. 10A shows the normalized ratio parameter Sth corresponding to the current phase β2 in which the motor abnormality has occurred when the current phase β is changed to the advance side with respect to the reference phase. Specifically, when the current phase β is changed to the advance side, the difference between the current phase β1 immediately before the motor abnormality occurs and the current phase β2 where the motor abnormality occurs is calculated as the first deviation Δβ0. Further, when the current phase β is changed to the advance side, the power factor angle ξ1 corresponding to the current phase β1 immediately before the motor abnormality occurs, and the power factor angle ξ2 corresponding to the current phase β2 where the motor abnormality occurs, Is calculated as the second deviation Δξ0. Then, a value obtained by dividing the absolute value of the first deviation Δβ0 by the absolute value of the second deviation Δξ0 is calculated as a normalized ratio parameter Sth corresponding to the current phase β2 in which the motor abnormality has occurred.

  FIG. 10B shows the normalized ratio parameter Sth corresponding to the current phase β4 where the motor abnormality has occurred when the current phase β is changed to the retard side with respect to the reference phase. Specifically, when the current phase β is changed to the retard side, the difference between the current phase β3 immediately before the motor abnormality occurs and the current phase β4 where the motor abnormality occurs is calculated as the first deviation Δβ0. When the current phase β is changed to the retard side, the power factor angle ξ3 corresponding to the current phase β3 immediately before the motor abnormality occurs, and the power factor angle ξ4 corresponding to the current phase β4 where the motor abnormality occurs are Is calculated as the second deviation Δξ0. Then, a value obtained by dividing the absolute value of the first deviation Δβ0 by the absolute value of the second deviation Δξ0 is calculated as a normalized ratio parameter Sth corresponding to the current phase β4 where the motor abnormality has occurred.

  The normalized ratio parameter Sth calculated in this way will be described with reference to FIG. 9. Even when the torque and the rotational speed are changed to various values, the normalized ratio parameter Sth causing the motor abnormality is greatly different. do not do. In the present embodiment, when the torque and the rotational speed are variously set, the motor is normally driven when the normalized ratio parameter Sth is in the range of 60% to 100%. However, when the normalized ratio parameter Sth is less than 60%, a motor abnormality may occur.

  For this reason, in this embodiment, when each of the command rotational speed ω * and the torque Trq is set to various values, when the current phase β is changed to the advance side with respect to the reference phase, the normalized ratio The power factor angle ξ corresponding to the current phase when the parameter Sth is 60% is used as the upper threshold ξHi. As a result, a retard angle side map in which the upper limit threshold value ξHi is defined in association with the command rotational speed ω * and the torque Trq is created.

  In this embodiment, when each of the command rotational speed ω * and the torque Trq is set to various values, the normalized ratio parameter is obtained when the current phase β is changed to the retard side with respect to the reference phase. The power factor angle ξ corresponding to the current phase when Sth is 60% is set as the lower threshold ξLo. As a result, an advance side map in which the lower limit threshold value ξLo is defined in relation to the command rotational speed ω * and the torque Trq is created.

  FIG. 11A shows the calculation result of the relationship between the power factor angle ξ and the normalized ratio parameter Sth when the torque is set to various values. The normalized ratio parameter Sth decreases as the torque increases. FIG. 11B shows the calculation result of the relationship between the power factor angle ξ and the normalized ratio parameter Sth when the rotation speed is set to various values. The normalization ratio parameter Sth decreases as the rotation speed decreases. In FIG. 11, the normalized ratio parameter Sth when the current phase β is on the advance side with respect to the reference phase is shown as a negative value.

  Thus, in this embodiment, the power factor angle ξ corresponding to the current phase when the normalized ratio parameter Sth is 60% on the retard side and the advance side is preliminarily adapted as the upper limit threshold value ξHi and the lower limit threshold value ξLo. . Even when each of the command rotational speed ω * and the torque Trq is set to various values, the motor 10 does not malfunction as long as the normalized ratio parameter Sth is 60% or more. For this reason, the power phase corresponding to the current phase when the normalized ratio parameter Sth is 60% is preliminarily adapted as the respective thresholds ξHi and ξLo, so that the current phase changes from the reference phase and is delayed in the monotonic change region. Abnormalities in the motor 10 such as step-out can be determined in advance in the current phase sufficiently before the angle side and advance side boundary values are reached.

  Furthermore, according to the present embodiment, the failure determination unit 30j determines whether the motor 10 is abnormal at substantially the same timing as referring to the power factor angle ξr output from the phase difference calculation unit 30a and the power factor angle map. can do. In addition, because of the abnormality determination using the map, the calculation load on the control device 30 can be reduced, and consequently the cost of the control device 30 can be reduced. Note that the abnormality of the motor 10 based on the abnormality determination process can be determined during the transient operation as well as during the steady operation of the motor 10 as long as the phase difference control is being executed.

(Other embodiments)
The above embodiment may be modified as follows.

  Each of the upper limit threshold value ξHi and the lower limit threshold value ξLo may be adapted to the power factor angle corresponding to the current phase when the normalized ratio parameter Sth is a value less than 60% (for example, 50%). Further, as the normalization ratio parameters used in the adaptation of the upper limit threshold value ξHi and the lower limit threshold value ξLo, the same value is not used, for example, 60% is used on the advance side and 50% is used on the retard side. Different values may be used.

  The detection value of the bus current sensor that detects the current flowing through the electrical path connecting the collectors of the upper arm switches Sup, Svp, Swp and the positive terminal of the DC power supply 21 may be used as the input of the filter unit 30d.

  The motor is not limited to a permanent magnet type but may be a wound field type, for example. Further, the motor is not limited to a three-phase motor and may be a four-phase or more motor. Furthermore, the application of the motor is not limited to fan driving, but may be, for example, pump driving.

  The power conversion circuit capable of applying an AC voltage to the motor 10 is not limited to a three-phase inverter, and may be another power conversion circuit as long as an AC voltage can be applied.

  DESCRIPTION OF SYMBOLS 10 ... Motor, 20 ... Inverter, 30 ... Control apparatus.

Claims (5)

Applied to a system comprising an electric motor (10) and a power conversion circuit (20) capable of applying an AC voltage to the electric motor;
A phase difference calculating means (30a) for calculating a phase difference between an applied voltage of the armature winding (10u to 10w) constituting the motor and a current flowing through the armature winding;
Operating means (30b to 30i) for operating the applied voltage of the armature winding by operating the power conversion circuit in order to control the phase difference calculated by the phase difference calculating means to the target value;
An abnormality determination unit that determines that an abnormality has occurred in the electric motor when the phase difference calculated by the phase difference calculation unit exceeds an upper limit threshold value and when the phase difference falls below the lower limit threshold value ( 30j),
The ratio parameter is the ratio of the change amount of the phase difference to the change amount of the current phase that is the phase of the current flowing through the armature winding,
A current phase region in which the phase difference is uniquely determined with respect to the current phase is a monotonic change region,
The ratio parameter in the monotonic change region, a value normalized by the maximum value of the ratio parameter in the monotonous change region is a normalized ratio parameter,
The upper limit threshold is preliminarily adapted based on the normalized ratio parameter corresponding to the current phase where the abnormality of the electric motor has occurred when the current phase is changed to the advance side in the monotonous change region,
The lower limit threshold is preliminarily adapted based on the normalized ratio parameter corresponding to the current phase at which the abnormality of the electric motor has occurred when the current phase is changed to the retard side in the monotonous change region. An electric motor control device. The upper limit threshold is the current phase at which the abnormality of the motor has occurred when the current phase is changed to the advance side in the monotonous change region determined according to the rotation speed of the motor and the torque of the motor. Pre-adapted based on the corresponding normalized ratio parameter,
The lower limit threshold is the current phase at which the abnormality of the motor has occurred when the current phase is changed to the retard side in the monotonic change region determined according to the rotation speed of the motor and the torque of the motor. Pre-adapted based on the corresponding normalized ratio parameter,
The motor control device according to claim 1, further comprising setting means for variably setting each of the upper limit threshold and the lower limit threshold based on a rotation speed of the motor and a torque of the motor. The upper limit threshold is the phase difference when the normalization ratio parameter is a specified value greater than 0 and less than or equal to 0.6 when the current phase is changed to the advance side in the monotonic change region. Is adapted to
The lower limit threshold is adapted to the phase difference when the normalized ratio parameter becomes the specified value when the current phase is changed to the retard side in the monotonic change region. The motor control device described.   The motor control apparatus according to claim 3, wherein the specified value is 0.6.   The electric motor control device according to claim 1, wherein the electric motor is used for driving an in-vehicle fan.