Synchronous reluctance motor abnormality detection device and abnormality detection method

Abstract

An abnormality detection device (40) is applied to a sensorless control device (100) that performs control to detect rotor position by superimposing a high frequency current on a synchronous reluctance motor (1). The abnormality detection device (40) includes a calculation unit (41) that calculates a physical quantity representing an abnormal state of a rotor (1b) of the synchronous reluctance motor (1) on the basis of the current value of the motor current flowing through the synchronous reluctance motor (1), and a determination unit (42) that determines whether the rotor (1b) is abnormal on the basis of the physical quantity. The abnormality detection device (40) holds a threshold value determined on the basis of a physical quantity when the rotor (1b) is normal. The determination unit (42) determines whether or not there is an abnormality in the rotor (1b) by comparing the physical quantity calculated by the calculation unit (41) with the threshold value.

Description

[Technical Field]

[0001] The present disclosure relates to an abnormality detection device and an abnormality detection method for a synchronous reluctance motor that utilizes rotor saliency. [Background technology]

[0002] The mainstream synchronous motors in recent years are interior permanent magnet synchronous motors and synchronous reluctance motors. Interior permanent magnet synchronous motors are motors that use both magnet torque and reluctance torque, while synchronous reluctance motors are motors that use only reluctance torque. Because reluctance torque is proportional to the salient pole ratio, motors that use reluctance torque require a rotor structure that ensures a sufficient salient pole ratio.

[0003] In the case of a synchronous reluctance motor, to ensure sufficient centrifugal force strength while maintaining a sufficient salient pole ratio, the rotor is provided with a magnetic path through which magnetic flux passes, air slits that form a magnetic barrier, and strength members that support the air slits. In other words, in a synchronous reluctance motor, there is a trade-off between the salient pole ratio and centrifugal force strength. For this reason, synchronous reluctance motors are designed to maximize the salient pole ratio while ensuring sufficient centrifugal force strength. However, this design does not take into account failures due to aging or unexpected failures. Therefore, in order to further improve safety, it is desirable to monitor the rotor condition and detect rotor abnormalities early in synchronous reluctance motors.

[0004] The following Patent Document 1 discloses a technology for detecting the presence or absence of a rotor abnormality based on components extracted by subtracting two waveforms of the same phase from each other in the current flowing through an AC motor. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Patent No. 4062939 Summary of the Invention [Problem to be solved by the invention]

[0006] However, when using the technology of Patent Document 1, the AC motor must rotate at a constant speed in order to subtract two current waveforms of the same phase. Therefore, it is difficult to detect rotor abnormalities when starting the AC motor using the technology of Patent Document 1. Furthermore, even when not starting, the rotation speed fluctuates slightly due to load pulsation. For this reason, the technology of Patent Document 1 may not be able to achieve sufficient detection accuracy.

[0007] The present disclosure has been made in consideration of the above, and aims to provide an abnormality detection device for a synchronous reluctance motor that can detect an abnormality in the rotor even when the synchronous reluctance motor is not rotating at a constant speed. [Means for solving the problem]

[0008] In order to solve the above-mentioned problems and achieve the object, the present disclosure provides an abnormality detection device for a synchronous reluctance motor that is applicable to a sensorless control device that performs control to detect rotor position by superimposing a high-frequency current on the synchronous reluctance motor, and includes a calculation unit and a determination unit. The calculation unit calculates a physical quantity that represents an abnormal state of the rotor of the synchronous reluctance motor based on the current value of the motor current flowing through the synchronous reluctance motor. The determination unit determines an abnormality of the rotor based on the physical quantity. [Effects of the Invention]

[0009] The synchronous reluctance motor abnormality detection device according to the present disclosure has the advantage of being able to detect an abnormality in the rotor even when the synchronous reluctance motor is not rotating at a constant speed. [Brief explanation of the drawings]

[0010] [Figure 1]FIG. 1 is a diagram showing a functional configuration of a synchronous reluctance motor abnormality detection device according to a first embodiment; [Figure 2] FIG. 1 is a diagram showing a configuration example of a sensorless control device including an abnormality detection device according to a first embodiment; [Figure 3] FIG. 3 is a diagram showing an example of a waveform of a high-frequency voltage output from the position estimation voltage generation unit of FIG. 2; [Figure 4] FIG. 1 is a cross-sectional view used to explain the structure of a rotor core in a synchronous reluctance motor assumed in the first embodiment. [Figure 5] Diagram showing the change in inductance in a typical synchronous reluctance motor [Figure 6] FIG. 5 is a diagram showing an example of a current vector locus when a high-frequency current flows through a synchronous reluctance motor having the rotor core shown in FIG. 4. [Figure 7] The flow of magnetic flux generated by the high-frequency current component when the fundamental current component is small is shown in Fig. 4. [Figure 8] FIG. 10 is a diagram showing an example of a coefficient value table used in high frequency boost control according to the first embodiment. [Figure 9] A diagram showing an example of a current vector locus when there is no abnormality in the rotor of the synchronous reluctance motor shown in Figure 2. [Figure 10] A diagram showing an example of a current vector locus when there is an abnormality in the rotor of the synchronous reluctance motor shown in Figure 2. [Figure 11] FIG. 1 is a block diagram showing an example of a hardware configuration that realizes the functions of an abnormality detection device according to a first embodiment. [Figure 12] FIG. 10 is a block diagram showing another example of a hardware configuration that realizes the functions of the abnormality detection device according to the first embodiment. [Figure 13] FIG. 10 is a diagram illustrating a determination process in the abnormality detection process according to the first embodiment. [Figure 14] 1 is a flowchart showing a processing flow of an abnormality detection process according to the first embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0011] An abnormality detection device and an abnormality detection method for a synchronous reluctance motor according to embodiments of the present disclosure will be described in detail below with reference to the accompanying drawings. Hereinafter, the "abnormality detection device for a synchronous reluctance motor" and the "abnormality detection method for a synchronous reluctance motor" will be referred to simply as the "abnormality detection device" and the "abnormality detection method" as appropriate.

[0012] Embodiment 1 FIG. 1 is a diagram illustrating a functional configuration of an abnormality detection device 40 according to the first embodiment. FIG. 2 is a diagram illustrating an example configuration of a sensorless control device 100 including the abnormality detection device 40 according to the first embodiment. As shown in FIG. 1, the abnormality detection device 40 includes a calculation unit 41 and a determination unit 42. As shown in FIG. 2, the sensorless control device 100 includes a current detection unit 2, a voltage applicator 3, a position estimation unit 4, a current control unit 5, a DC power supply 12, an abnormality determiner 25, and a position estimation voltage generation unit 30. In FIG. 1, the calculation unit 41 is configured to include the function of the high-frequency current amplitude calculation unit 7 shown in FIG. 2 and the calculation processing function of the abnormality determiner 25 shown in FIG. 2, and the determination unit 42 is configured to include the determination processing function of the abnormality determiner 25 shown in FIG. 2.

[0013] In FIG. 2, synchronous reluctance motor 1 is a device driven by sensorless control device 100. Synchronous reluctance motor 1 has stator 1a and rotor 1b arranged inside stator 1a. Sensorless control device 100 is a control device that performs control to detect rotor position, which is position information of rotor 1b, by superimposing a high-frequency current on synchronous reluctance motor 1 without using a speed sensor or position sensor. Note that, in this paper, a reluctance-type synchronous reluctance motor is assumed as an example of synchronous reluctance motor 1, but is not limited to this. Synchronous reluctance motor 1 may also be an interior permanent magnet synchronous reluctance motor.

[0014] A DC power supply 12 supplies DC power to the voltage applicator 3. When the synchronous reluctance motor 1 is a motor, the voltage applicator 3 applies a DC voltage V dcis used to generate an AC voltage for driving the motor, and the generated AC voltage is applied to the motor.

[0015] The current detector 2 detects the motor current i flowing between the voltage applicator 3 and the synchronous reluctance motor 1. u ,i v ,i w Detects the motor current i u ,i v ,i w is the stator current flowing through each phase of the stator 1a, i.e., the u-phase, v-phase, and w-phase. A current detector is provided for each phase of the current detection unit 2. An example of a current detector is a current transformer. In FIG. 2, the current detection unit 2 detects all three-phase currents, but this is not limiting. It detects currents for any two of the three phases, and the remaining phase is fed with the motor current i u ,i v ,i w Alternatively, instead of the current detector 2 in FIG. 2, a bus current flowing through a DC bus (not shown) connecting the voltage applicator 3 and the DC power supply 12 may be detected, and the motor current i u ,i v ,i w may be calculated.

[0016] As shown in FIG. 1, the calculation unit 41 calculates the motor current i u ,i v ,i w The calculation unit 41 receives the detected or calculated current value of the motor current i u ,i v ,i w The determining unit 42 determines whether the rotor 1b of the synchronous reluctance motor 1 is abnormal based on the physical quantity calculated by the calculating unit 41, and outputs the determination result J. d Examples of the physical quantities calculated by the calculation unit 41 will be described later.

[0017] Returning to the explanation of FIG. 2, the position estimation unit 4 calculates the motor current i u ,i v ,i wThe estimated value θ of the rotor position, which is the position information of the rotor 1b, is calculated based on the current value of L The current control unit 5 calculates the motor current i u ,i v ,i w The estimated value of the rotor position θ L and a first voltage command V, which is a command value of the synchronous reluctance motor voltage for driving the synchronous reluctance motor 1, is calculated based on the above. u * ,V v * ,V w * The position estimation voltage generating unit 30 generates a q-axis current command i q * Based on this, the first voltage command V u * ,V v * ,V w * High frequency voltage V uh ,V vh ,V wh Generates a high frequency voltage V uh ,V vh ,V wh is a voltage for position estimation for estimating the rotor position. The current control unit 5 controls the first voltage command V u * ,V v * ,V w * High frequency voltage V uh ,V vh ,V wh The superimposed voltage is the second voltage command V up * ,V vp * ,V wp * The voltage applicator 3 outputs the second voltage command V up * ,V vp * ,V wp *A driving voltage is generated based on the above and applied to the synchronous reluctance motor 1. In this paper, the voltage applicator 3 is assumed to be a two-level three-phase inverter, but is not limited to this. In this paper, the voltage applicator 3 may be a three-level three-phase inverter, or a polyphase two-level or three-level inverter.

[0018] The current control unit 5 includes subtractors 13d and 13q, a d-axis current controller 14d, a q-axis current controller 14q, a first coordinate converter 15, a two-phase to three-phase converter 16, a second coordinate converter 17, a three-phase to two-phase converter 18, and adders 23u, 23v, and 23w.

[0019] The subtractor 13d subtracts the d-axis current command i d * and the d-axis current i output from the second coordinate converter 17. d Deviation Δi d The next stage d-axis current controller 14d calculates the deviation Δi d By controlling proportional and integral control so that becomes zero, the d-axis voltage command V d * The subtractor 13q calculates the q-axis current command i q * and the q-axis current i output from the second coordinate converter 17. q Deviation Δi q The next stage q-axis current controller 14q calculates the deviation Δi q By controlling the proportional integral so that V becomes zero, the q-axis voltage command V q * Calculate the d-axis current command i d * is the d-axis current command value for driving the synchronous reluctance motor 1, and the q-axis current command i q * is the command value of the q-axis current to drive the synchronous reluctance motor 1. The d-axis current command i d * and q-axis current command i q * are both given from outside the current control unit 5.

[0020] The first coordinate converter 15 converts the d-axis voltage command V output from the d-axis current controller 14d and the q-axis current controller 14q into d * and q-axis voltage command V q * voltage command V on the stationary two-axis coordinate system α * ,V β * The two-phase to three-phase converter 16 converts the voltage command V α * ,V β * is converted into the first voltage command V, which is the drive voltage command in the three-phase AC coordinate system. u * ,V v * ,V w * The processing of the first coordinate converter 15 uses the estimated value θ of the rotor position output from the position estimation unit 4. L is also used.

[0021] The three-phase to two-phase converter 18 converts the motor current i detected by the current detection unit 2 into u ,i v ,i w The α-axis current i on the stationary two-axis coordinate system α and β-axis current i β The second coordinate converter 17 converts the α-axis current i output from the three-phase to two-phase converter 18 into α and β-axis current i β is the estimated rotor position θ output from the position estimation unit 4. L The d-axis current i on the rotating coordinate system that rotates in synchronization with d and q-axis current i q and outputs the converted values to the subtractors 13d and 13q.

[0022] The first voltage command V output from the two-phase to three-phase converter 16 u * ,V v * ,V w * and the high frequency voltage V output from the position estimation voltage generator 30. uh ,V vh ,Vwh The outputs of the adders 23u, 23v, and 23w are added together to form a second voltage command V up * ,V vp * ,V wp * Therefore, the second voltage command V up * ,V vp * ,V wp * The first voltage command V u * ,V v * ,V w * The high frequency voltage V uh ,V vh ,V wh is superimposed. Note that the high frequency voltage V uh ,V vh ,V wh Details will be described later.

[0023] The position estimation unit 4 includes a high-frequency current amplitude calculation unit 7 and a position calculator 8. The high-frequency current amplitude calculation unit 7 includes current extractors 6u, 6v, and 6w, multipliers 9u, 9v, and 9w, integrators 10u, 10v, and 10w, and square root calculators 22u, 22v, and 22w. These components are provided corresponding to each phase.

[0024] As described above, the second voltage command V applied to the voltage applicator 3 up * ,V vp * ,V wp * The first voltage command V output by the two-phase to three-phase converter 16 is u * ,V v * ,V w * The high frequency voltage V output by the position estimation voltage generator 30 is uh ,V vh ,Vwh Therefore, the motor current i detected by the current detection unit 2 u ,i v ,i w is the high frequency voltage V uh ,V vh ,V wh High frequency current i with the same frequency component as uh ,i vh ,i wh Contains:

[0025] Therefore, each of the current extractors 6u, 6v, and 6w extracts the motor current i detected by the current detection unit 2. u ,i v ,i w From the high frequency voltage V uh ,V vh ,V wh High frequency current i with the same frequency component as uh ,i vh ,i wh Extract the high frequency current i uh ,i vh ,i wh A band-pass filter or a notch filter can be used to extract the motor current i u ,i v ,i w is input to the notch filter to generate the high frequency voltage V uh ,V vh ,V wh The motor current i u ,i v ,i w By subtracting each current after passing through the notch filter from uh ,i vh ,i wh can be extracted.

[0026] The multipliers 9u, 9v, and 9w multiply the high-frequency current i uh ,i vh ,i whThe integrators 10u, 10v, and 10w perform integration processing over a time Tn corresponding to one integration period, and output the integrated value by multiplying the calculated value by (2 / Tn). The square root calculators 22u, 22v, and 22w calculate the position estimation current amplitude I by calculating the square root of each output of the integrators 10u, 10v, and 10w. uh ,I vh ,I wh The current amplitude for position estimation I uh ,I vh ,I wh is output to the position calculator 8 and the abnormality determiner 25.

[0027] In addition, in the high-frequency current amplitude calculation unit 7 in FIG. 2, the high-frequency current i uh ,i vh ,i wh The position estimation current amplitude I is calculated by integrating the autocorrelation value of uh ,I vh ,I wh However, it is not limited to this. uh ,i vh ,i wh The current amplitude I for position estimation is obtained by passing the autocorrelation value of uh ,I vh ,I wh may be generated.

[0028] The position calculator 8 calculates the position estimation current amplitude I uh ,I vh ,I wh Based on this, the rotor position estimate θ L The estimated rotor position θ L A known method is used for the calculation of (a), and a detailed description thereof will be omitted here. Note that the specific calculation procedure is disclosed in, for example, Japanese Patent No. 5324646, and the contents of this publication should be referred to.

[0029] The abnormality determiner 25 detects the position estimation current amplitude I uh ,I vh ,I whThe abnormality determination process by the abnormality determiner 25 will be described in detail later.

[0030] Next, the high frequency voltage V output from the position estimation voltage generator 30 uh ,V vh ,V wh 3 is a diagram showing the high-frequency voltage V output from the position estimation voltage generator 30 shown in FIG. uh ,V vh ,V wh 3 is a diagram showing an example of the waveform of Fig. 3. The waveform of Fig. 3 is an example when the voltage applicator 3 is equipped with a PWM (Pulse Width Modulation) inverter for triangular wave comparison.

[0031] The horizontal axis in Figure 3 represents time. In Figure 3, from top to bottom, there are a triangular wave carrier, a u-phase high-frequency voltage V uh , v-phase high frequency voltage V vh , w-phase high frequency voltage V wh The waveform of the high frequency voltage V uh ,V vh ,V wh One period Th of the high frequency voltage V is a signal that takes six periods (=6 Tc) when one period is a half period Tc of the triangular wave carrier. uh ,V vh ,V wh In order to achieve three-phase balance, the high-frequency voltage V is set to be shifted by two intervals (=2·Tc) between each phase. Note that Figure 3 is an example, and is not limited to this example. uh ,V vh ,V wh Any waveform may be used as long as it is a waveform that results in three-phase balance.

[0032] Returning to Fig. 2, the position estimation voltage generation unit 30 will be described. The position estimation voltage generation unit 30 includes a high frequency amplitude calculator 31 and a high frequency voltage generator 32. The high frequency amplitude calculator 31 receives a q-axis current command i q * The high frequency amplitude calculator 31 receives the q-axis current command i q *Based on the coefficient value W h Select or calculate the coefficient value W h is the high frequency voltage V uh ,V vh ,V wh The coefficient W is a positive real value that is set to determine the voltage amplitude of h The selection of the coefficient value W h Alternatively, the coefficient value W can be calculated by function calculation without using a table. h may be calculated.

[0033] q-axis current command i q * is an example of a physical quantity that is correlated with the magnetic saturation of the rotor 1b. If the physical quantity is correlated with the magnetic saturation of the rotor 1b, the q-axis current command i q * Other examples of physical quantities correlated with the magnetic saturation of the rotor 1b include the q-axis current i q , q-axis voltage command V q * etc. In addition, the d-axis current command i d * , d-axis current i d , d-axis voltage command V d * These may also be physical quantities correlated with the magnetic saturation of the rotor 1b.

[0034] The high frequency voltage generator 32 generates a coefficient value W h Using the above-mentioned high frequency voltage V uh ,V vh ,V wh The operation of the high frequency voltage generator 32 is explained using some equations shown below.

[0035] A mathematical formula expressing the high frequency current will be derived to explain the operation of the high frequency voltage generator 32. First, the voltage equation of the synchronous motor on the αβ axes, which are stationary coordinates, is expressed by the following formula (1).

[0036]

number

[0037] In the above formula (1), i α ,i β are the α-axis current and β-axis current mentioned above. Also, V α ,V β represent the α-axis voltage and the β-axis voltage, respectively. E represent the stator resistance and the induced voltage coefficient, respectively. α ,L β ,L αβ ,L d ,L q represent the α-axis inductance, β-axis inductance, mutual inductance between the α and β axes, d-axis inductance, and q-axis inductance, respectively. Furthermore, L0 is defined by the fifth equation in the above equation (1), and L1 is defined by the sixth equation in the above equation (1). Furthermore, p represents the differential operator.

[0038] The above formula (1) is applicable to both synchronous reluctance motors and interior permanent magnet synchronous motors. In the case of a synchronous reluctance motor that does not use magnets, the induced voltage coefficient K E becomes zero, so the induced voltage coefficient K E It is possible to omit the second term of the above equation (1), which includes: Moreover, when only the high frequency component is considered in the above equation (1), the following equation (2) is obtained.

[0039]

number

[0040] In the above formula (2), V αh ,V βh ,i αh ,i βh represent the high frequency components of the α-axis voltage, β-axis voltage, α-axis current, and β-axis current, respectively. Note that the transformation from equation (1) above to equation (2) also holds true for synchronous reluctance motors that do not use magnets.

[0041] When the above equation (2) is solved for the current differential term, the following equation (3) is obtained.

[0042]

number

[0043] Also, the a, β axis voltage V on the αβ axis α ,V β is defined by the following equation (4).

[0044]

number

[0045] In the above formula (4), V hαβ represents the high frequency voltage amplitude on the αβ axis, and ω h represents the angular frequency on the αβ axis. Note that angular frequency is also called "angular velocity."

[0046] When the above equation (4) is expressed on the three-phase coordinate system, the default high-frequency voltage V is expressed by the following equation (5). uh1 ,V vh1 ,V wh1 is obtained.

[0047]

number

[0048] The high frequency voltage generator 32 calculates the coefficient value W h Use the default high frequency voltage V uh1 ,V vh1 ,V wh1 The coefficient value W h By multiplying this, the high frequency voltage V uh ,V vh ,V wh Generate.

[0049]

number

[0050] Next, the structure of the rotor core that constitutes the rotor 1b in the synchronous reluctance motor 1 will be described. FIG. 4 is a cross-sectional view used to explain the structure of rotor core 50 in the synchronous reluctance motor 1 assumed in the first embodiment. In FIG. 4, rotor core 50 is formed by laminating a plurality of electromagnetic steel sheets, which are plate materials. Shaft 51 is fitted to the inner diameter side of rotor core 50. Rotor core 50 is formed of a laminated body in which core pieces 53, which are annular thin plates, are stacked. Core pieces 53 can be made by punching out electromagnetic steel sheets, which are thin steel plates, with a press machine. When synchronous reluctance motor 1 is assembled, the stacking direction of the thin plates that constitute rotor core 50 is the same as the axial direction of shaft 51.

[0051] A rotor core 50, in which a plurality of core pieces 53 are stacked, has a plurality of slits 52 that form magnetic barriers. The slits 52 are arc-shaped and convex toward the shaft hole into which the shaft 51 fits, and are formed from one d-axis side to the other d-axis side with the q-axis as the center. In the rotor core 50, the d-axis is an axis through which magnetic flux passes relatively easily, and the q-axis is an axis through which magnetic flux passes relatively less easily. The d-axis and q-axis are magnetically and electrically perpendicular to each other.

[0052] Slit groups 54, each consisting of a plurality of slits 52, are formed at intervals in the circumferential direction of the rotor core 50, the number of which corresponds to the number of poles. Fig. 4 shows an example in which the rotor 1b has four poles, and in Fig. 4, slit groups 54 for four poles are formed.

[0053] The rotor core 50 must be strong enough to withstand the centrifugal force generated when the synchronous reluctance motor 1 rotates. For this reason, a center rib 55a is formed in each slit 52, acting as a strength member. In addition to the center rib 55a, each slit 52 except for the outermost periphery is formed with two side ribs 55b, which also act as strength members. The center rib 55a and the side ribs 55b can be formed by leaving the center rib 55a and the side ribs 55b unpunched when punching out the slits 52 from a thin steel plate. Note that the arrangement of the center rib 55a and the side ribs 55b shown in FIG. 4 is merely an example and is not limited to this arrangement. Any arrangement may be used as long as the desired strength is obtained.

[0054] Furthermore, in the rotor core 50, annular portions 57 are formed as annular portions between each slit group 54 and an outer peripheral edge 56 of the rotor core 50 because no slits 52 are formed therebetween. In the rotor core 50, the annular portions 57 also function as strength members. In this document, the center rib 55a, the side ribs 55b, the annular portions 57, and the like, which function as strength members, may be collectively referred to as "bridge portions."

[0055] The fifth and sixth equations of the above equation (1) include the d-axis inductance L d and the q-axis inductance L q Figure 5 shows the change in inductance in a typical synchronous reluctance motor. The horizontal axis represents the rotor position, and the vertical axis represents the magnitude of inductance.

[0056] In a typical synchronous reluctance motor, the inductance changes depending on the electrical angle. Specifically, as shown in Figure 5, the inductance exhibits two local maximum and two local minimum values during one electrical rotation. The local maximum value of the inductance is the d-axis inductance L d The minimum value of the inductance is the q-axis inductance L q That is, the d-axis inductance L d teeth 、q-axis inductance L q Here, the d-axis inductance L d q-axis inductance L q If the ratio of is defined as the salient pole ratio, then the salient pole ratio L q / L d is larger than 1. This is because the d-axis current i d than the interlinkage flux due to the q-axis current i q This is because the synchronous reluctance motor 1 is configured so that the interlinkage magnetic flux due to the axial direction is larger than that due to the axial direction.

[0057] Fig. 6 is a diagram showing an example of a current vector locus when a high-frequency current flows through the synchronous reluctance motor 1 having the rotor core 50 shown in Fig. 4. The horizontal axis of Fig. 6 represents the d-axis current i d The vertical axis represents the q-axis current i q As shown in Fig. 6, the q-axis current i q When is relatively large, the current vector locus becomes elliptical. On the other hand, the q-axis current i q When is small, as shown in the lower left, the current vector locus is not elliptical but is almost circular. The center of the current vector locus represents the fundamental wave current component of the current flowing through the synchronous reluctance motor 1, and the distance from the center of each plot of the current vector locus represents the high frequency current component of the current flowing through the synchronous reluctance motor 1. Therefore, the q-axis current i q A region where is small means that the torque command given to the synchronous reluctance motor 1 is small.

[0058] When the current vector locus is elliptical, the rotor position can be detected based on the difference or ratio between the length of the major axis and the length of the minor axis of the ellipse. qIt can be seen that the larger the value, the better the accuracy of rotor position detection. The reason for this will be further explained with reference to Fig. 7. Fig. 7 is a diagram showing the flow of magnetic flux generated by the high-frequency current component when the fundamental wave current component is small in rotor core 50 shown in Fig. 4.

[0059] In Fig. 7, the solid arrow indicates the q-axis current i q This represents the flow of magnetic flux that can be generated by the high-frequency current component contained in the d-axis current i. In this paper, this magnetic flux component is referred to as the "torque flux" for convenience. The dashed arrow indicates the flow of magnetic flux that can be generated by the high-frequency current component contained in the d-axis current i. d This represents the flow of magnetic flux that can be generated by the high-frequency current components contained in the bridge section. In this paper, this magnetic flux component will be referred to as the "excitation magnetic flux" for convenience. As mentioned above, the rotor core 50 shown in Figure 4 has a structure with salient poles. Therefore, during steady-state operation when the fundamental wave current component is large, the bridge section of the rotor core 50 is fully magnetically saturated, and the q-axis magnetic flux indicated by the solid arrow becomes small. In contrast, when the fundamental wave current component is small, the degree of magnetic saturation in the bridge section is low, and the torque magnetic flux passing through the bridge section does not attenuate much. As a result, the torque magnetic flux passing through the bridge section becomes large, the difference with the excitation magnetic flux becomes small, and the saliency does not appear.

[0060] The sensorless control device 100 according to the first embodiment shown in Fig. 2 is configured to solve the problem of the saliency. Specifically, the sensorless control device 100 calculates the rotor position estimated value θ L If the desired detection accuracy is not obtained, the coefficient value W calculated by the high frequency amplitude calculator 31 h is controlled in the increasing direction, and the high frequency voltage V uh ,V vh ,V wh In this paper, this control is referred to as "high frequency boost control" for convenience.

[0061] Considering the absence of high-frequency current, if the fundamental current is small, its magnetic flux component easily passes through the bridge section. Narrowing the bridge section width reduces the amount of magnetic flux passing through, but weakens the rotor core 50. Furthermore, increasing the fundamental current causes the bridge section to become magnetically saturated. However, this method is undesirable from an operational standpoint, since it causes unnecessary current to flow, reducing efficiency and applying unnecessary torque to the synchronous reluctance motor 1. In contrast, increasing the high-frequency current can magnetically saturate the bridge section without changing the magnitude of the fundamental current. This makes it possible to solve the problem of fundamental current making it difficult for saliency to occur through control.

[0062] The specific processing is as described above, and the coefficient value W h Calculate the default high frequency voltage V uh1 ,V vh1 ,V wh1 The coefficient value W h By multiplying by this, the high frequency voltage V uh ,V vh ,V wh Also, the coefficient value W h A table can be used to calculate the coefficient value. Fig. 8 is a diagram showing an example of a coefficient value table used in the high frequency boost control according to the first embodiment.

[0063] In Fig. 8, the coefficient value table has the d-axis current command i d * The current value i d1 * ,i d2 * ,i d3 * ,…,i dM * is displayed, and the settable q-axis current command i q * The current value i q1 * ,i q2 * ,i q3 * ,…,iqN * The current value i d1 * ,i d2 * ,i d3 * ,…,i dM * The intervals between the current values i do not need to be equal, but may be unequal. q1 * ,i q2 * ,i q3 * ,…,i qN * The same is true for .

[0064] The coefficient value table contains the d-axis current command i d * and q-axis current command i q * The coefficient value W is determined by the relationship h The value of (W h11 ,W h12 ,W h13 ,…,W h1M ,W h21 ,W h22 ,W h23 ,…,W h2M ,W h31 ,W h32 ,W h33 ,…,W h3M ,…,W hN1 ,W hN2 ,W hN3 ,…,W hNM ) is stored. Note that the current value i q1 * ,i q2 * ,i q3 * ,…,i qN * Gai q1 * q2 * q3 * <,…, qN * If W h11 ,W h21 ,W h31 ,…,W​​​hN1 Between h11 >W h21 >W h31 >,…,>W hN1 That is, the coefficient value W h is the q-axis current command i q * There is a negative correlation with the coefficient values of other columns W h The same is true for the current value i d1 * ,i d2 * ,i d3 * ,…,i dM * Gai d1 * d2 * d3 * <,…, dM * If W h11 ,W h12 ,W h13 ,…,W h1M Between h11 >W h12 >W h13 >,…,>W h1M That is, the coefficient value W h is the d-axis current command i d * There is a negative correlation with the coefficient values W of other rows. h The same is true.

[0065] The values stored in the coefficient value table can be obtained by simulation. It is not necessary to obtain all the stored values by simulation, and they may be obtained by calculation processing such as interpolation, extrapolation, or interpolation of some simulation results.

[0066] Next, the coefficient value W in the high frequency boost control h First, in the coefficient value table in FIG. 8, the part surrounded by a bold frame is set as the default. Here, i d1 * = 0. The high frequency amplitude calculator 31 calculates the q-axis current command i​​​q * Based on this, the coefficient value W is calculated by referring to the bold framed part of the coefficient value table in FIG. h For example, the q-axis current command i q * The value of "i q3 * ", then "W h31 ". q-axis current command i q * The value of "i q2 * " and "i q3 * If the value is between "i q2 * " and "i q3 * You may select one of the following.

[0067] In addition, the q-axis current command i q * In addition, the d-axis current command i d * In this case, the entire coefficient value table in FIG. 8 is used. For example, the q-axis current command i q * The value of "i q3 * " and the d-axis current command i d * The value of "i d2 * ", then "W h32 If the coefficient value is not in the coefficient value table, it goes without saying that it may be found by interpolation or the like.

[0068] Next, the concept of the abnormality detection process of the first embodiment will be described with reference to Fig. 9 and Fig. 10. Fig. 9 is a diagram showing an example of a current vector locus when there is no abnormality in the rotor 1b of the synchronous reluctance motor 1 shown in Fig. 2. Fig. 10 is a diagram showing an example of a current vector locus when there is an abnormality in the rotor 1b of the synchronous reluctance motor 1 shown in Fig. 2.

[0069] The horizontal axis of Fig. 9 is the d-axis current i dThe vertical axis represents the q-axis current i q Also, on the left side of Fig. 9, the q-axis current i q =0 and d-axis current i d = 0, the current vector locus is the coefficient value W h But, W h =0.1, W h =0.3 and W h 9. Also, on the right side of Figure 9, the same three coefficient values W h Regarding the q-axis current i q =0 and d-axis current i d The current vector locus when >0 is shown.

[0070] W h When W = 0.1, the center rib 55a, side rib 55b, and annular portion 57 of the rotor core 50 are not magnetically saturated, so the torque magnetic flux passing through these portions increases and saliency does not appear. As a result, the current vector locus is not a clear ellipse, but rather a locus that is close to a perfect circle. In contrast, when W h =0.3 and W h When ρ = 0.5, the center rib 55a, side rib 55b, and annular portion 57 of the rotor core 50 are magnetically saturated by the high-frequency current, so the torque magnetic flux passing through these portions becomes smaller and saliency appears, resulting in a clear ellipse as the current vector locus.

[0071] On the other hand, if there is an abnormality in the rotor 1b, the current vector locus will be different from that in normal operation. In Figure 10, the dashed line K1 indicates that the current vector locus, which was close to a perfect circle, has changed to an ellipse. Furthermore, the dashed-dotted line K2 indicates that the current vector locus, which was close to a perfect circle, has changed to an ellipse and that distortion has occurred in the current vector locus.

[0072] For example, if a crack occurs in at least one of the center rib 55a, the side rib 55b, and the annular portion 57 of the rotor core 50, the magnetic flux passing through the cracked portion is blocked, so the inductance component of that portion decreases and the portion is equivalent to being saturated. Therefore, if a change in the current vector locus from normal can be detected, it is possible to determine whether there is an abnormality in the rotor 1b.

[0073] Fig. 11 is a block diagram showing an example of a hardware configuration for realizing the functions of abnormality detection device 40 according to embodiment 1. When realizing the functions of abnormality detection device 40 according to embodiment 1, the configuration can include processor 400 for performing calculations, memory 402 for storing programs read by processor 400, interface 404 for inputting and outputting signals, and display 406 for displaying detection results, as shown in Fig. 11.

[0074] Processor 400 is an example of a computing means. Processor 400 may be a computing means called a microprocessor, a microcomputer, a microcontroller, a CPU (Central Processing Unit), or a DSP (Digital Signal Processor). Examples of memory 402 include non-volatile or volatile semiconductor memories such as RAM (Random Access Memory), ROM (Read Only Memory), flash memory, EPROM (Erasable Programmable ROM), and EEPROM (registered trademark) (Electrically EPROM), as well as magnetic disks, flexible disks, optical disks, compact disks, minidisks, and DVDs (Digital Versatile Discs).

[0075] The memory 402 stores a program that executes the functions of the anomaly detection device 40 according to the first embodiment. The processor 400 exchanges necessary information via the interface 404, executes the program stored in the memory 402, and refers to the data stored in the memory 402, thereby performing the above-described processing. The calculation results by the processor 400 can be stored in the memory 402. The processing results of the processor 400 can also be displayed on the display 406. The display 406 may be provided outside the anomaly detection device 40.

[0076] Furthermore, when realizing the functions of the abnormality detection device 40 according to the first embodiment, the configuration shown in Fig. 12 may be used. Fig. 12 is a block diagram showing another example of a hardware configuration that realizes the functions of the abnormality detection device 40 according to the first embodiment. In Fig. 12, the processor 400 and memory 402 shown in Fig. 11 are replaced with a processing circuit 403.

[0077] The processing circuit 403 may be a single circuit, a composite circuit, an ASIC (Application Specific Integrated Circuit), an FPGA (Field-Programmable Gate Array), or a combination thereof. Information input to and output from the processing circuit 403 can be exchanged via an interface 404.

[0078] 13 is a diagram illustrating the determination process in the abnormality detection process according to the first embodiment. The left side of FIG. 13 shows the position estimation current amplitude I uh ,I vh ,I wh The right side of Fig. 13 shows the waveform of the current amplitude I for position estimation under normal conditions. uh ,I vh ,I wh In addition to the waveform of the rotor 1b, the position estimation current amplitude I uh ,I vh ,I whThe waveform of is shown by the dashed line. The horizontal axis in Fig. 11 represents the rotor position over one electrical angle period in both the left and right diagrams. The amplitude of the current for position estimation I uh ,I vh ,I wh is the output of the high frequency current amplitude calculation unit 7 calculated by the square root calculators 22u, 22v, and 22w shown in FIG.

[0079] The position estimation current amplitude I obtained by the high frequency current amplitude calculation unit 7 uh ,I vh ,I wh As shown in Figure 11, the DC component I h This DC component I h changes in half of one period of the rotor position, i.e., in half the period of the rotor position.

[0080] The abnormality determiner 25 calculates the DC component I h The DC component I is calculated by averaging the calculated value over one or half cycle of the rotor position. h The time average value of is calculated and stored in memory 402.

[0081]

number

[0082] When an abnormality occurs in the rotor 1b, the DC component I h In Figure 10, the DC component I h The change in the DC component I appears as a change in the center position of the ellipse. h The time average value of the calculated DC component I h The presence or absence of an abnormality in the rotor 1b is determined by comparing the time average value of the abnormality determination unit 25 with the time average value in a normal state stored in the memory 402. The abnormality determination unit 25 displays the determination result on the display unit 406. The determination result by the abnormality determination unit 25 may be stored in the memory 402.

[0083] In addition, the DC component I h is the motor current i u ,i v ,i w and is an example of a physical quantity that indicates an abnormal state of the rotor 1b. In the determination process in the abnormality detection process of the first embodiment, the DC component I h Other physical quantities that represent the abnormal state of the rotor 1b may be used instead of the motor current i u ,i v ,i w or the AC component included in the motor current i u ,i v ,i w It may be a strain component contained in

[0084] 14 is a flowchart showing the processing flow of the abnormality detection processing according to embodiment 1. The operation of FIG. 14 will be explained in association with the calculation unit 41 and the determination unit 42 which are components of the abnormality detection device 40 shown in FIG.

[0085] The calculation unit 41 calculates the motor current i u ,i v ,i w Based on the current amplitude I for position estimation uh ,I vh ,I wh (Step S11). The calculation unit 41 also calculates the DC component I h (Step S12). Furthermore, the calculation unit 41 calculates the DC component I h The DC component I h The time average value of I ha (Step S13). The determination unit 42 calculates the time average value I ha is compared with threshold A (step S14). Threshold A is the DC component I h The time average value of I ha The threshold value is determined based on the above and is stored in advance in the memory 402.

[0086] Time average value I haIf the time average value I is less than the threshold value A (step S15, Yes), the determination unit 42 determines that the rotor 1b is normal (step S16). ha If is equal to or greater than threshold value A (step S15, No), the determination unit 42 determines that the rotor 1b is not normal (step S17). After the processes of steps S16 and S17, the determination unit 42 displays the determination result on the display 406 (step S18). When the process of step S18 ends, the process returns to step S11, and the processes from step S11 are repeated.

[0087] In the determination process of step S15, the time average value I ha is equal to the threshold A is determined as "No", but it may be determined as "Yes". ha If the threshold value A is equal to the threshold value B, the result may be either "Yes" or "No."

[0088] A supplementary explanation will be given regarding the above processing flow. The processing flow shown in FIG. 14 can be performed, for example, when the sensorless control device 100 is started up. When the sensorless control device 100 is started up, the synchronous reluctance motor 1 is often accelerating, increasing its rotational speed, and the rotational speed of the synchronous reluctance motor 1 is not constant. As described above, in the prior art, the synchronous reluctance motor 1 must rotate at a constant speed. For this reason, in the prior art, it is difficult to detect an abnormality in the rotor 1b when the sensorless control device 100 is started up. In contrast, in the abnormality detection device 40 according to the first embodiment, the synchronous reluctance motor 1 does not need to rotate at a constant speed, so it is possible to detect an abnormality in the rotor 1b when the sensorless control device 100 is started up.

[0089] As described above, the abnormality detection device according to the first embodiment is applicable to a sensorless control device that performs control to detect the rotor position by superimposing a high-frequency current on a synchronous reluctance motor. The abnormality detection device according to the first embodiment can be configured to include a calculation unit that calculates a physical quantity representing an abnormal state of the rotor of the synchronous reluctance motor based on the current value of the motor current flowing through the synchronous reluctance motor, and a determination unit that determines an abnormality of the rotor based on the physical quantity. The abnormality detection device holds a threshold value determined based on the physical quantity when the rotor is normal. The determination unit determines the presence or absence of an abnormality of the rotor by comparing the physical quantity calculated by the calculation unit with the threshold value. The abnormality detection device according to the first embodiment does not restrict the rotational speed of the synchronous reluctance motor, so it is possible to detect an abnormality of the rotor even if the synchronous reluctance motor is not rotating at a constant speed. Furthermore, the abnormality detection device according to the first embodiment can detect an abnormality of the rotor when the sensorless control device is started, so it is possible to quickly detect an abnormality of the rotor.

[0090] Furthermore, according to the abnormality detection device of the first embodiment, the device can be configured by using part of the function of the existing high frequency boost control, which makes it possible to easily realize the configuration of the abnormality detection device.

[0091] In the above process, the physical quantity representing the abnormal state of the rotor of the synchronous reluctance motor may be the DC component contained in the motor current, the AC component contained in the motor current, or the distortion component contained in the motor current. Regardless of the physical quantity, the position estimation current amplitude calculated during sensorless control can be used, making it possible to easily realize the configuration of the abnormality detection device.

[0092] The anomaly detection method according to the first embodiment can be applied to a sensorless control device that performs control to detect the rotor position by superimposing a high-frequency current on a synchronous reluctance motor. The anomaly detection method according to the first embodiment can be a process including a calculation step of calculating a physical quantity representing an abnormal state of the rotor of the synchronous reluctance motor based on the current value of the motor current flowing through the synchronous reluctance motor, and a determination step of determining whether the rotor is abnormal based on the physical quantity. A device that performs this anomaly detection method holds a threshold value determined based on the physical quantity when the rotor is normal. In the determination step, the presence or absence of a rotor abnormality is determined by comparing the physical quantity calculated in the calculation step with the threshold value. The anomaly detection method according to the first embodiment does not restrict the rotational speed of the synchronous reluctance motor, so it is possible to detect a rotor abnormality even if the synchronous reluctance motor is not rotating at a constant speed. Furthermore, the anomaly detection method according to the first embodiment can detect a rotor abnormality when the control device that performs sensorless control is started, so it is possible to quickly detect a rotor abnormality.

[0093] Embodiment 2 An abnormality detection device 40 according to the second embodiment has the same configuration as that of the first embodiment. In the second embodiment, the configuration of the abnormality detection device 40 is the same as that of Fig. 1 and Fig. 2, and the configuration of the sensorless control device 100 is the same as that of Fig. 2. In the second embodiment, a technique that can improve the detection accuracy of the abnormality detection method according to the first embodiment will be described.

[0094] When the processing flow of FIG. 14 is performed at startup of the sensorless control device 100, it is conceivable that the results of multiple abnormality determinations will vary. That is, it is conceivable that an abnormality will be detected in one cycle of rotor position detection, and not in another cycle of rotor position detection. In such a case, the abnormality determination of the rotor 1b may be performed multiple times, and the determination result may be output if all the multiple determination results are the same. In this way, it is possible to reduce the probability of erroneously determining that the rotor 1b is abnormal when it is actually normal.

[0095] As explained with reference to FIG. 6, the q-axis current i q When is small, the current vector locus is not elliptical but is almost circular. Also, as explained with reference to FIG. 10, when there is an abnormality in the rotor 1b, the current vector locus changes from a circle to an ellipse. Therefore, the q-axis current i q The smaller the value, the larger the change in the shape of the current vector locus, and therefore the higher the accuracy of abnormality detection. Therefore, in the second embodiment, when abnormality determination of the rotor 1b is performed multiple times and the multiple determination results vary, the q-axis current command i q * The current control unit 5 is instructed to reduce the q-axis current command i q * The smaller the σ, the greater the change in the shape of the current vector locus, which can improve the stability of the abnormality determination process, thereby improving the accuracy of abnormality detection.

[0096] As described above, in the abnormality detection device according to embodiment 2, the judgment unit judges the rotor for abnormality multiple times, and outputs the judgment result if all the judgment results are the same. By adding this processing to the abnormality detection device according to embodiment 1, it is possible to reduce the probability of erroneously judging that the rotor is abnormal when it is actually normal.

[0097] Furthermore, if the determination results vary during the multiple determination processes, the current control unit may be instructed to reduce the torque axis current command applied by the current control unit. This can improve the stability of the abnormality determination process and the accuracy of abnormality detection.

[0098] Furthermore, according to the anomaly detection method of embodiment 2, in the determination step, the rotor is determined to be abnormal multiple times, and if the multiple determination results are all the same, the determination result is output. By adding this process to the anomaly detection method of embodiment 1, it is possible to reduce the probability of erroneously determining that the rotor is abnormal when it is actually normal.

[0099] Furthermore, in the above-described multiple determination processes, if the determination results vary, a command step may be included in which the current control unit is instructed to reduce the torque axis current command applied by the current control unit. By adding such a command step, the stability of the abnormality determination process can be improved, and the detection accuracy of the abnormality can be improved.

[0100] The configurations shown in the above embodiments are merely examples, and may be combined with other known technologies, or different embodiments may be combined with each other. It is also possible to omit or modify parts of the configurations as long as they do not deviate from the gist of the invention. [Explanation of symbols]

[0101] 1 synchronous reluctance motor, 1a stator, 1b rotor, 2 current detection unit, 3 voltage application unit, 4 position estimation unit, 5 current control unit, 6u, 6v, 6w current extractor, 7 high-frequency current amplitude calculation unit, 8 position calculation unit, 9u, 9v, 9w multiplier, 10u, 10v, 10w integrator, 12 DC power supply, 13d, 13q subtractor, 14d d-axis current controller, 14q q-axis current controller, 15 first coordinate converter, 16 two-phase to three-phase converter, 17 second coordinate converter, 18 three-phase to two-phase converter, 22u, 22v, 22w square root calculator, 23u, 23v, 23w adder, 25 abnormality judger, 30 position estimation voltage generation unit, 31 high-frequency amplitude calculator, 32 high-frequency voltage generator, 40 abnormality detection device, 41 Calculation unit, 42 judgment unit, 50 rotor core, 51 shaft, 52 slit, 53 core fragment, 54 slit group, 55a center rib, 55b side rib, 56 edge portion, 57 annular portion, 100 sensorless control device, 400 processor, 402 memory, 403 processing circuit, 404 interface, 406 display.

Claims

1. An abnormality detection device for a synchronous reluctance motor that is applied to a sensorless control device that performs control to detect a rotor position by superimposing a high frequency current on the synchronous reluctance motor, a calculation unit that calculates a physical quantity that indicates an abnormal state of the rotor of the synchronous reluctance motor and that is correlated with magnetic saturation of the rotor based on a current value of a motor current flowing through the synchronous reluctance motor; a determination unit that determines an abnormality of the rotor based on the physical quantity; Equipped with The physical quantity is a DC component included in the motor current. An abnormality detection device for a synchronous reluctance motor, characterized in that:

2. A synchronous reluctance motor abnormality detection device applied to a sensorless control device that performs control to detect rotor position by superimposing a high frequency current on the synchronous reluctance motor, a calculation unit that calculates a physical quantity that indicates an abnormal state of the rotor of the synchronous reluctance motor and that is correlated with magnetic saturation of the rotor based on a current value of a motor current flowing through the synchronous reluctance motor; a determination unit that determines an abnormality of the rotor based on the physical quantity; Equipped with The physical quantity is an AC component included in the motor current. An abnormality detection device for a synchronous reluctance motor, characterized in that:

3. An abnormality detection device for a synchronous reluctance motor that is applied to a sensorless control device that performs control to detect a rotor position by superimposing a high frequency current on the synchronous reluctance motor, a calculation unit that calculates a physical quantity that indicates an abnormal state of the rotor of the synchronous reluctance motor and that is correlated with magnetic saturation of the rotor based on a current value of a motor current flowing through the synchronous reluctance motor; a determination unit that determines an abnormality of the rotor based on the physical quantity; Equipped with The physical quantity is a distortion component contained in the motor current. An abnormality detection device for a synchronous reluctance motor, characterized in that:

4. a threshold value determined based on the physical quantity when the rotor is normal is maintained; The determination unit determines whether or not there is an abnormality in the rotor by comparing the physical quantity calculated by the calculation unit with a threshold value.

4. The abnormality detection device for a synchronous reluctance motor according to claim 1, wherein the abnormality detection device is a synchronous reluctance motor.

5. The determination unit performs a plurality of abnormality determinations on the rotor, and outputs a determination result when the plurality of determination results are all the same.

5. The abnormality detection device for a synchronous reluctance motor according to claim 4.

6. the sensorless control device includes a current control unit that generates a voltage command for driving the synchronous reluctance motor based on a current value of the motor current and the estimated value of the rotor position; If the results of the multiple determinations vary, the current control unit is instructed to reduce the torque axis current command given by the current control unit.

6. The abnormality detection device for a synchronous reluctance motor according to claim 5.

7. A method for detecting an abnormality in a synchronous reluctance motor, which is applied to a sensorless control device that performs control to detect a rotor position by superimposing a high frequency current on the synchronous reluctance motor, comprising: a calculation step of calculating a physical quantity that indicates an abnormal state of the rotor of the synchronous reluctance motor and that is correlated with magnetic saturation of the rotor, based on a current value of a motor current flowing through the synchronous reluctance motor; a determination step of determining an abnormality in the rotor based on the physical quantity; Including, In the determination step, the rotor abnormality determination is performed a plurality of times, and if the plurality of determination results are all the same, the determination result is output. A method for detecting an abnormality in a synchronous reluctance motor, comprising:

8. the sensorless control device includes a current control unit that generates a voltage command for driving the synchronous reluctance motor based on a current value of the motor current and the estimated value of the rotor position; The determining step includes a command step of issuing a command to the current control unit so that the torque axis current command given by the current control unit becomes smaller when the determination results obtained multiple times in the determining step vary.

8. The method for detecting an abnormality in a synchronous reluctance motor according to claim 7.

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