Rotor magnet temperature estimation method and rotor magnet temperature estimation device

Abstract

To estimate a temperature of a permanent magnet disposed on a rotor with higher accuracy.SOLUTION: In a rotor magnet temperature estimation method of a permanent magnet synchronous motor in which a rotor core is axially divided into three or more split cores, and each split core is axially stacked and arranged with a skew angle, a present value of the number of magnetic flux interlinkage or an inductance on a d-axis and a q-axis in a rotor synchronization coordinate system is calculated from a current and a voltage applied to the motor, and a rotor magnet temperature of each split core having a different skew angle is estimated on the basis of the calculated number of magnetic flux interlinkage or the inductance on the d-axis and the q-axis,.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to a rotor magnet temperature estimation method and a rotor magnet temperature estimation device. [Background technology]

[0002] Patent Document 1 discloses a device that estimates the temperature of a permanent magnet using a magnetization element made of a temperature-sensitive magnetic material, arranged on the end plate of a rotor, and magnetized by leakage flux that leaks from the rotor core out of the magnetic flux generated by a permanent magnet arranged in the rotor core, and a Hall element that detects the strength of the magnetic field generated by the magnetization element itself. Specifically, since the magnetization element is made of a temperature-sensitive magnetic material and its magnetic properties change with changes in its own temperature, the temperature of the magnetization element is estimated from the strength of the magnetic field detected by the Hall element, and the temperature of the permanent magnet is indirectly estimated from that. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 4165229 Summary of the Invention [Problem to be solved by the invention]

[0004] It is known that the temperature of the permanent magnets arranged in the rotor varies depending on their position in the rotor axial direction, with the temperature increasing the closer to the center of the rotor axial direction. In the device described in the above document, the temperature of the permanent magnets is estimated indirectly from the temperature of the magnetizing elements arranged on the end plates of the rotor, which means that the temperature is estimated at the end of the rotor axial direction, making it difficult to accurately estimate the temperature of parts closer to the center.

[0005] Therefore, an object of the present invention is to estimate with higher accuracy the temperature of the permanent magnets (hereinafter also referred to as rotor magnets) arranged in the rotor, including the portion near the center in the rotor axial direction. [Means for solving the problem]

[0006] According to one aspect of the present invention, there is provided a rotor magnet temperature estimation method for a permanent magnet synchronous motor in which the rotor core is divided into three or more divided cores in the axial direction, and each divided core is stacked in the axial direction with a skew angle. This method includes calculating the magnetic flux linkage numbers of the d-axis and q-axis in the rotor synchronous coordinate system or the current values ​​of the inductance from the current and voltage applied to the motor, Let n be the number of divided cores with different skew angles. Under no load, the magnetic flux linkage λ observed on the d axis of each divided core is calculated from the magnetic flux linkages on the d axis and q axis. d_core-n Calculate the magnetic flux linkage number λ of each divided core. d_core-n and the electrical angle θ between the d axes of the divided cores nn Using the following formula (1), the d-axis magnetic flux linkage number λ, which is the magnetic flux linkage number on the d-axis generated by the magnets in each divided core, is calculated. d-n Separately calculate the d-axis magnet flux linkage λ of each coil d-n Based on the average rotor magnet temperature of each divided core Estimate.

[0007] According to another aspect of the present invention, there is provided a rotor magnet temperature estimation device for a permanent magnet synchronous motor in which a rotor core is divided into three or more divided cores in the axial direction, and each divided core is stacked in the axial direction at a skew angle. This device comprises: a state estimator that calculates the current values ​​of the magnetic flux linkages or inductances of the d-axis and q-axis in a rotor synchronous coordinate system from the current and voltage applied to the motor; Let n be the number of divided cores with different skew angles. Under no load, the magnetic flux linkage λ observed on the d axis of each divided core is calculated from the magnetic flux linkages on the d axis and q axis. d_core-n Calculate the magnetic flux linkage number λ of each divided core. d_core-n and the electrical angle θ between the d axes of the divided cores nn Using the following formula (1), the d-axis magnetic flux linkage number λ, which is the magnetic flux linkage number on the d-axis generated by the magnets in each divided core, is calculated. d-n Separately calculate the d-axis magnet flux linkage λ of each coil d-n Based on the average rotor magnet temperature of each divided core and a magnet temperature calculator for estimating the magnet temperature.

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[0008] According to the above aspect, the rotor magnet temperature can be estimated with higher accuracy, including the temperature of the rotor magnet in the portion near the center in the axial direction. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 1 is a schematic configuration diagram of a rotor core according to a first embodiment. [Figure 2] FIG. 2 is a diagram showing the relationship between the d and q axes of the divided cores and the d and q axes in motor output control. [Figure 3] FIG. 3 is a schematic configuration diagram of the control system according to the first embodiment. [Figure 4] FIG. 4 is a block diagram showing an example of a flux linkage number estimator. [Figure 5] FIG. 5 is a block diagram showing another example of the flux linkage number estimator. [Figure 6] FIG. 6 is a diagram showing the relationship between the magnet temperature and the axial position. [Figure 7] FIG. 7 is a schematic configuration diagram of a control system according to the second embodiment. [Figure 8] FIG. 8 is a diagram showing the dependency of the inductance value on the change in magnet temperature. [Figure 9] FIG. 9 is a schematic configuration diagram of a control system according to the third embodiment. [Figure 10] FIG. 10 is a diagram showing the dependency of the interlinkage magnetic flux on the d and q axes in motor control on the magnet temperature of each divided core. DETAILED DESCRIPTION OF THE INVENTION

[0010] Hereinafter, an embodiment of the present invention will be described with reference to the accompanying drawings.

[0011] [First embodiment] 1 is a schematic diagram of a rotor core 1 of a permanent magnet synchronous motor (hereinafter simply referred to as a motor) to which a first embodiment of the present invention is applied. This motor is a radial gap type motor having an air gap in the radial direction of the rotor.

[0012] The rotor core 1 contains permanent magnets (hereinafter simply referred to as magnets) and is divided into multiple sections along the rotation axis (hereinafter also referred to as the rotation axis direction). In this embodiment, it is divided into three sections, with the central divided core being referred to as the central core 2 and the divided cores on both ends being referred to as the end cores 3.

[0013] If the angle in the rotational direction of the rotor core 1 is defined as a mechanical angle, the rotor core 1 has a so-called step skew structure in which the center core 2 and the end cores 3 are arranged so that they are offset by a mechanical angle of θ. In the following explanation, this relative mechanical angle offset θ between the center core 2 and the end core 3 is referred to as the skew angle θ. Note that the two end cores 3 have the same mechanical angle.

[0014] In the following description, the central core 2 may be referred to as Core1, and the edge core 3 may be referred to as Core2.

[0015] 2 is a diagram showing the relationship between the d- and q-axes (d-core1, 2, q-core1, 2) of the center core 2 and the end cores 3 and the d- and q-axes (d-master, q-master) in motor output control. d-1 , λ d-2 indicate the magnetic flux linkage numbers generated by the magnets of the center core 2 and the end core 3, respectively.

[0016] These magnetic flux linkages λ d-1,2 is a vector. Since the central core 2 and the end core 3 are skewed, the magnetic flux linkage λ d-1,2 has a deviation in the rotation direction by the skew angle θ on the d, q coordinates, and also has a deviation in the rotation direction by ±θ / 2 with respect to the d-master.

[0017] Magnet flux linkage λ d-1,2 is generated on the d axis of each core 2, 3, and has a temperature characteristic in which its magnitude changes with changes in the magnet temperature. d-1,2 are separately detected and compared with the temperature characteristics acquired in advance, thereby estimating the temperature of the magnet contained in each core 2, 3.

[0018] In the no-load state, the magnetic flux linkage λ d-1,2 is the magnetic flux linkage λ calculated by the magnetic flux linkage estimator 14 described later. d-core1,2 (the magnetic flux linkages observed on the d-axis of each of Cores 1 and 2) can be calculated using the following formula (1): Note that n in formula (1) is the number of divided cores with different skew angles, and in this embodiment, the two end cores 2 have the same skew angle, so n=2.

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[0019] The temperature estimation device includes a subtractor 11, a PI controller 12, a magnetic flux linkage estimator 14 as a state estimator, and a λ d-n A calculator 15 and a magnet temperature calculator 16 are provided.

[0020] The subtractor 11 subtracts the torque current command value i corresponding to the torque command value. * d,q The feedback input from the motor 13 is the current value i d,q is negatively fed back. Then, the torque current command value i * d,q is input to the PI controller 12.

[0021] The PI controller 12 calculates the current value i d,q Specifically, the current value i in the motor 13 is used for feedback control. d,q is the torque current command value i * d,q The voltage command value v * d,q is generated and output to the motor 13.

[0022] The motor 13 may include an inverter and a sensor. * d,q The three-phase AC voltage generated by the inverter in response to the input is applied to the bus bar of the motor 13, causing the rotor core 1 of the motor 13 to rotate. A current sensor is provided on the wiring between the inverter and the motor 13, and the three-phase AC current detected by this current sensor is phase-converted to produce a current value i d,q can be obtained.

[0023] The magnetic flux linkage estimator 14 receives a voltage command value v * d,q , the current value i detected in the motor 13 d,q , and an electrical phase angle θe detected by a resolver provided near the rotor of the motor 13. Based on these inputs, the magnetic flux linkage estimator 14 calculates the magnetic flux linkage λ , which is the magnetic flux linkage observed on the d-axis of Core1 and Core2. d,q-core1,2 The specific estimation method is as follows.

[0024] Magnetic flux linkage is defined as the total magnetic flux linking the coils wound around the stator multiplied by the number of coil turns, and the time derivative of this is the induced voltage generated in the coil. Therefore, the magnetic flux linkage can be found by integrating the induced voltage over time. However, when applying it to actual control, simple time integration will result in an error in the calculation of magnetic flux linkage due to the integral constant, so it is desirable to apply a method to suppress the error, such as combining it with a high-pass filter (see Figure 4) or combining it with a model that uses nominal values ​​of the motor constants (see Figure 5).

[0025] 4 is a block diagram showing an example of the magnetic flux linkage estimator 14 combined with a high-pass filter. Note that the dp axis is a rotating coordinate system synchronized with the rotor, and the αβ axis is a stationary coordinate system.

[0026] In this case, the magnetic flux linkage estimator 14 includes an integrator 20, a high-pass filter 21, and an αβ / dq converter 22. * d,q The voltage command value v is converted into the value of the αβ coordinate. * α,β is time-integrated in the integrator 20, and the αβ-axis magnet flux linkage λ α,β The αβ-axis magnet flux linkage number λ is calculated. α,β is passed through the high-pass filter 21 and the αβ / dq converter 22 to obtain the magnetic flux linkage λ d,q-core1,2 is output as

[0027] FIG. 5 is a block diagram showing an example of the magnetic flux linkage estimator 14 combined with a model using nominal values ​​of the motor constants.

[0028] In this case, the magnetic flux linkage estimator 14 includes an inductance calculator 30, a dq / αβ converter 31, a subtractor 32, a PI controller 33, a dq / αβ converter 34, an adder 35, an integrator 36, and an αβ / dq converter 37.

[0029] The inductance calculator 30 calculates the current value i d,q The inductance value L of motor 13 d,q By multiplying this, the dq-axis magnet flux linkage (current model) λ generated in the motor 13 according to the current load is obtained. d-i,q-i This process is based on the general relationship between current, inductance, and magnetic flux linkage. Note that the inductance value L d,q is a fixed value, and specifically, a nominal value is used.

[0030] In the dq / αβ converter 31, the dq-axis magnet flux linkage number (current model) λ d-i,q-i By performing dq / αβ transformation on the αβ axis magnet flux linkage (current model) λ α-i,β-i Calculate.

[0031] In the subtractor 32, the αβ-axis magnet flux linkage number (current model) λ α-i,β-i The αβ-axis magnet flux linkage number λ output from the downstream integrator 36 isα,β By subtracting Δλ α-i,β-i Calculate.

[0032] In the PI controller 33, the αβ-axis magnet flux linkage (current model) λ α-i,β-i By performing PI control on the αβ-axis magnet flux linkage (current model) λ α-i,β-i and αβ-axis magnet flux linkage λ α,β The difference between the two is controlled to be small.

[0033] In the dq / αβ converter 34, the voltage command value v * d,q Perform dq / αβ transformation on

[0034] The output from the PI controller 33 and the output from the dq / αβ converter 34 are added together in an adder 35, and the result of the addition is time-integrated in an integrator 36, thereby obtaining the αβ-axis magnet flux linkage λ α,β Finally, the magnetic flux linkage number λ is calculated through the αβ / dq converter 37. d,q-core1,2 will be output.

[0035] The magnetic flux linkage λ calculated using one of the above methods d,q-core1,2 is λ d-n The magnetic flux linkage λ generated by the magnets contained in Core 1 and Core 2 is input to the calculator 15 and calculated by the above-mentioned formula (1). d-1,2 is calculated.

[0036] The magnet temperature calculator 16 calculates the magnetic flux linkage λ d-1,2 Based on the relationship between the magnet temperature and core1,2 Estimate the magnetic flux linkage λ d-1,2 The relationship between the magnet temperature and the temperature of the magnet is determined by mapping data previously obtained through experiments, for example, as shown in FIG. 3, and stored in the magnet temperature calculator 16. Although the magnet temperature in each divided core has a temperature gradient in the axial direction, the magnet temperature used for mapping is the average temperature in the axial direction. In other words, the magnet temperature T estimated by the above procedure is core1,2 is the average temperature in the axial direction of each magnet contained in Core 1 and Core 23.

[0037] This is shown in Figure 6. The horizontal axis of Figure 6 is the axial position, and the vertical axis is the magnet temperature, with T core1 , T core2 is the magnet temperature estimated using the above procedure. This result also shows that the magnet temperature near the center, which is relatively high, can be estimated with greater accuracy than the method described in the above-mentioned literature. However, to further improve estimation accuracy, the actual temperature gradient can be estimated using, for example, linear extrapolation from the estimation results shown in Figure 6, and the magnet temperature distribution and maximum temperature within rotor core 1 can be estimated as shown by the dashed line in Figure 6. Estimating the maximum temperature more accurately makes it easier to avoid thermal demagnetization of the magnets during operation.

[0038] As described above, this embodiment provides a rotor magnet temperature estimation method for a permanent magnet synchronous motor in which the rotor core 1 is divided axially into three or more divided cores 2, 3, and each divided core 2, 3 is stacked in the axial direction with a skew angle θ. This method calculates the magnetic flux linkages of the d-axis and q-axis in the rotor synchronous coordinate system from the current and voltage applied to the motor, and estimates the rotor magnet temperature of each divided core with a different skew angle based on the calculated magnetic flux linkages of the d-axis and q-axis. Because the magnetic flux linkages are observable values ​​and depend on the magnet temperature distribution, this embodiment allows for accurate estimation of the magnet temperature. Furthermore, the rotor core 1 has a so-called step skew, and the temperatures of divided cores with different skew angles are estimated, allowing for accurate estimation of the magnet temperature with a temperature distribution in the axial direction.

[0039] In this embodiment, each of the split cores 2, 3 is stacked with a split core (center core 2) located approximately in the center of the axial direction and a split core (end core 3) located at an end in the axial direction at a skew angle. Because the center core 2 and the end cores 3 are stacked with different skew angles, the magnet temperature in the center, which becomes relatively high, can be accurately estimated.

[0040] In this embodiment, the number of divided cores with different skew angles is n, and the magnetic flux linkage λ observed on the d axis of each divided core is calculated from the magnetic flux linkages on the d axis and q axis in an unloaded state. d_core-n Calculate the magnetic flux linkage number λ of each divided core. d_core-n and the electrical angle θ between the d axes of the divided cores nn Using equation (1), the d-axis magnetic flux linkage number λ, which is the magnetic flux linkage number on the d-axis generated by the magnets in each divided core, is calculated. d-n Separately calculate the d-axis magnet flux linkage λ of each coil d-n The average rotor magnet temperature of each divided core is estimated based on the d-axis magnet flux linkage number λ of each divided core using equation (1). d-n is calculated separately and the magnet temperature of each divided core is estimated based on this, so that the magnet temperature of each divided core can be detected separately.

[0041] In this embodiment, the magnetic flux linkage number λ of each divided core in the d axis direction is d_core-n is calculated by integrating the voltage applied to the motor with respect to time. This allows the actual state of magnetic flux generated in the motor to be detected with high accuracy, improving the accuracy of estimating the magnet temperature.

[0042] In this embodiment, the temperature gradient of the rotor magnet temperature in the axial direction is calculated based on the calculated average rotor magnet temperature of each divided core and the relative axial distance between the axial center positions of each divided core. This allows for more accurate magnet temperature distribution in the rotor, making it possible to estimate the maximum magnet temperature and avoid partial thermal demagnetization of the magnet.

[0043] In this embodiment, the rotor magnet temperature at the axial center position of rotor core 1 is estimated using the rotor magnet average temperature of any one of the divided cores, the temperature gradient, and the distance from the axial center position of that divided core to the axial center position of rotor core 1. This makes it possible to obtain the magnet temperature at approximately the axial center, which is the hottest, and thus makes it possible to avoid partial thermal demagnetization of the magnet.

[0044] In this embodiment, the magnetic flux linkage number λ is calculated by observing the magnetic flux linkage on the d-cores 1 and 2. d,q-core1,2 However, the calculation method is not limited to this. For example, d -master , q -master The magnetic flux linkage λ on d-master , λ q-master Alternatively, the calculation may be performed by performing coordinate transformation using the observed value of and the skew angle θ.

[0045] [Second embodiment] In the first embodiment, the magnet temperature is estimated using the temperature characteristics of the magnetic flux linkages of Core1 and Core2. In this embodiment, however, instead of this, d, q -master Inductance value L d,q-master This utilizes the characteristic that the magnet temperature of Core1 and Core2 is dependent on the magnet temperature change.

[0046] Inductance value L d,q-master is calculated by applying an AC voltage to any position between the d-axis and q-axis, and using the ratio between the amplitude of the applied AC voltage and the amplitude of the current generated at the same frequency as the applied AC voltage. Note that the frequency of the applied AC voltage must be equal to or greater than the frequency of the current command value for motor control.

[0047] 7 is a schematic diagram showing an example of a control system 10 in which the temperature estimation device according to this embodiment is implemented. The differences from FIG. 3 are that a high-frequency current superimposer 40 and an adder 41 are added, and that a magnetic flux linkage estimator 14 and a λ d-n The difference is that a bandpass filter 42 and an inductance calculator 43 as a state estimator are provided instead of the calculator 15. The calculation method performed by the magnet temperature calculator 16 is also different. The following will mainly explain these differences.

[0048] When Trig is input in response to a request for estimating the magnet temperature from a higher-level device (not shown), the high-frequency current superimposer 40 generates a high-frequency current command value so that the high-frequency current Δi flows only during that period. d,q-HFThe frequency is ω. The frequency ω is an angular velocity defined by the frequency f of the superimposed high-frequency current, and can be calculated by 2πf.

[0049] The adder 41 calculates the torque current command value i * d,q The high frequency current command value Δi is superimposed on the * d,q is input to the subtractor 11 described above.

[0050] The band-pass filter 42 is a voltage command value v * d,q The voltage required for superimposing the high frequency current (amplitude V d,q-HF ) and extract the current value i d,q and inputs these to the inductance calculator 43.

[0051] The inductance calculator 43 calculates the inductance value L by the following formula (2): d,q-master Calculate.

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[0052] In Figure 8, the horizontal axis is the inductance value L of the d-master. d-master The vertical axis is the inductance value L of the q-master q-master In the coordinate system of Core1, the magnet temperature T core1 and Core2 magnet temperature T core2 The combinations of Core 2 and Core 2 are plotted. Rows q1 to q4 are combinations where the magnet temperature of Core 2 is constant and the magnet temperature of Core 1 varies, with q1 being the lowest and q4 being the highest. Columns d1 to d4 are combinations where the magnet temperature of Core 1 is constant and the magnet temperature of Core 2 varies, with d1 being the lowest and d4 being the highest.

[0053] Inductance value L d,q-master is the load current I d,q The magnet temperature T core1,2 As shown in Figure 8, the inductance value L calculated by equation (2) d,q-master From Figure 8, the magnet temperatures of Core 1 and Core 2 can be estimated even under load.

[0054] The magnet temperature estimated by the above procedure is the average temperature in the axial direction of Core 1 and Core 2, just like in the first embodiment. Then, just like in the first embodiment, the axial temperature gradient is calculated from the estimated magnet temperature, and the actual magnet temperature can be estimated from this and the axial length of each core.

[0055] As described above, this embodiment provides a rotor magnet temperature estimation method for a permanent magnet synchronous motor in which the rotor core is divided axially into three or more divided cores 2, 3, and each divided core 2, 3 is stacked in the axial direction with a skew angle. This method calculates the current values ​​of the d-axis and q-axis inductances in the rotor synchronous coordinate system from the current and voltage applied to the motor, and estimates the rotor magnet temperature of each divided core with a different skew angle based on the calculated d-axis and q-axis inductances. This allows for accurate estimation of the magnet temperature, as in the first embodiment.

[0056] In this embodiment, the d-axis and q-axis inductances are calculated by applying an AC voltage to any position between the d-axis and q-axis, and using the ratio between the amplitude of the applied AC voltage and the amplitude of a current generated at the same frequency as the applied AC voltage. This reduces the time required to calculate the inductance, thereby preventing deterioration of motor controllability.

[0057] In this embodiment, the frequency of the applied AC voltage is equal to or higher than the frequency of the current command value for motor control, which prevents interference with motor control and suppresses deterioration of motor controllability.

[0058] In this embodiment, the correlation between the rotor magnet average temperature of each divided core and the d-axis and q-axis inductance under load is calculated in advance and stored, and the d-axis and q-axis inductance under load are used as input values ​​to calculate the rotor magnet average temperature of each divided core based on this correlation. This reduces the influence of fluctuations in magnetic flux linkage due to the load state, thereby further improving the accuracy of magnet temperature estimation.

[0059] [Third embodiment] In the first embodiment, the magnet temperature is estimated using the temperature characteristics of the magnetic flux linkage of Core1 and Core2. However, in this embodiment, instead of this, the magnetic flux linkage λ of the d, q-master is used. d,q-master is the load current I d,q This utilizes the fact that the magnet temperature of Cores 1 and 2 is dependent on the magnet temperature (see FIG. 10).

[0060] 9 is a schematic diagram showing an example of a control system 10 that implements the temperature estimation device according to this embodiment. The difference from FIG. 3 is that the magnet temperature calculator 16 calculates the d, q-master interlinkage magnetic flux λ as described above. d,q-master The magnet temperature is calculated based on the output of the magnetic flux linkage estimator 14 as a state estimator. d,q-master This is the same as the λ d,q-core1,2 It is the same as:

[0061] In Fig. 10, the horizontal axis is λ d-master The vertical axis is λ q-master The magnet temperature T of Core1 is calculated in the coordinate system of core1 and Core2 magnet temperature T core2 The rows q1 to q4 and columns d1 to d4 are the same as in Figure 8.

[0062] d,q-master interlinkage flux λ d,q-master is the load current I d,q 10 shows the dependency on the magnet temperature of Core 1 and Core 2, so the λ calculated by the magnetic flux linkage estimator 14 d,q-masterFrom Figure 10, the magnet temperatures of Core 1 and Core 2 can be estimated even under load.

[0063] The magnet temperature estimated by the above procedure is the average temperature in the axial direction of Core 1 and Core 2, just like in the first embodiment. Then, just like in the first embodiment, the axial temperature gradient is calculated from the estimated magnet temperature, and the actual magnet temperature can be estimated from this and the axial length of each core.

[0064] As described above, according to this embodiment, the same effects as those of the first embodiment can be obtained.

[0065] In this embodiment, the correlation between the rotor magnet average temperature of each divided core and the d-axis and q-axis magnetic flux linkages under load is calculated in advance and stored, and the d-axis and q-axis magnetic flux linkages under load are used as input values ​​to calculate the rotor magnet average temperature of each divided core based on this correlation. This reduces the influence of magnetic flux linkage fluctuations due to load conditions, thereby further improving the accuracy of magnet temperature estimation.

[0066] The present invention is not limited to the above-described embodiment, and various modifications can be made within the scope of the technical concept described in the claims. For example, in the embodiment, the rotor core 1 is divided into three parts, but this is not limiting and the invention can be applied to a case where the rotor core is divided into four or more parts. When the number of divisions is odd, the magnet temperature at the axial center, which is the highest, can be estimated from the temperature of the divided core located in the axial center, as in the case of division into three parts. On the other hand, when the number of divisions is even, the magnet temperature at the axial center can be estimated from the temperature of the divided core located approximately in the axial center. [Explanation of symbols]

[0067] 1 Rotor, 2 Center core (Core1), 3 End core (Core2)

Claims

1. A rotor magnet temperature estimation method for a permanent magnet synchronous motor in which a rotor core is divided into three or more divided cores in an axial direction, and each divided core is stacked in the axial direction at a skew angle, comprising: Calculating the current values ​​of the magnetic flux linkages or inductances of the d-axis and q-axis in the rotor synchronous coordinate system from the current and voltage applied to the motor; The number of divided cores with different skew angles is n, Calculating the magnetic flux linkage number λ d_core-n observed on the d axis of each divided core from the magnetic flux linkage numbers on the d axis and q axis in a no-load state; Using the magnetic flux linkage number λ d_core-n of each divided core and the electrical angle θ nn between the d-axes of the divided cores, the d-axis magnetic flux linkage number λ d-n , which is the magnetic flux linkage number on the d-axis generated by the magnets of each divided core, is calculated separately using the following equation (1): A rotor magnet temperature estimation method, characterized in that the rotor magnet average temperature of each divided core is estimated based on the d-axis magnet flux linkage number λ d−n of each coil. [Equation 1]

2. 2. The rotor magnet temperature estimation method according to claim 1, A rotor magnet temperature estimation method, wherein each divided core is stacked with a divided core located approximately in the center of the axial direction and a divided core located at an end in the axial direction at a skew angle.

3. 3. The rotor magnet temperature estimation method according to claim 1, further comprising: A rotor magnet temperature estimation method in which d-axis and q-axis inductances are calculated by applying an AC voltage to any position between the d-axis and q-axis, and using the ratio between the amplitude of the applied AC voltage and the amplitude of a current generated at the same frequency as the applied AC voltage.

4. 4. The rotor magnet temperature estimation method according to claim 3, A rotor magnet temperature estimation method, wherein the frequency of the applied AC voltage is equal to or higher than the frequency of a current command value for motor control.

5. 5. The rotor magnet temperature estimation method according to claim 1, The magnetic flux linkage number λ of each divided core on the d axis ｄ＿ｃｏｒｅ－ｎ This is a rotor magnet temperature estimation method that calculates the temperature by integrating the voltage applied to the motor over time.

6. A rotor magnet temperature estimation method for a permanent magnet synchronous motor in which a rotor core is divided into three or more divided cores in the axial direction, and each divided core is stacked and arranged in the axial direction with a skew angle, The correlation between the rotor magnet average temperature of each divided core and the magnetic flux linkage number or inductance of the d-axis and q-axis magnets under load is calculated and stored in advance, Calculating the current values ​​of the magnetic flux linkages or inductances of the d-axis and q-axis in the rotor synchronous coordinate system from the current and voltage applied to the motor; A rotor magnet temperature estimation method that calculates the average rotor magnet temperature of each divided core based on the correlation using the d-axis and q-axis magnetic flux linkages or inductance in a loaded state as input values.

7. 7. The rotor magnet temperature estimation method according to claim 1, A rotor magnet temperature estimation method for calculating a temperature gradient of the rotor magnet temperature in the axial direction based on the calculated average rotor magnet temperature of each divided core and the relative distance in the axial direction between the axial center positions of each divided core.

8. 8. The rotor magnet temperature estimation method according to claim 7, A rotor magnet temperature estimation method for estimating the rotor magnet temperature at the axial center position of the rotor core using the average rotor magnet temperature of any one of the divided cores, the temperature gradient, and the distance from the axial center position of the divided core to the axial center position of the rotor core.

9. A rotor magnet temperature estimation device for a permanent magnet synchronous motor in which a rotor core is divided into three or more divided cores in the axial direction, and each divided core is stacked in the axial direction at a skew angle, a state estimator that calculates the current values ​​of the magnetic flux linkages of the d-axis and q-axis in the rotor synchronous coordinate system or the inductance from the current and voltage applied to the motor; a magnet temperature calculator which calculates a magnetic flux linkage λ d_core-n observed on the d-axis of each split core from the magnetic flux linkages on the d-axis and q-axis in a no-load state, where n is the number of split cores with different skew angles, and which separately calculates a d-axis magnetic flux linkage λ d-n which is the magnetic flux linkage on the d-axis generated by the magnets in each split core using the magnetic flux linkage λ d_core-n of each split core and the electrical angle θ nn formed by the d-axes of each split core using the following formula (1), and estimates the rotor magnet average temperature of each split core based on the d-axis magnetic flux linkage λ d-n of each coil; A rotor magnet temperature estimation device comprising: [Equation 1]

10. A rotor magnet temperature estimation device for a permanent magnet synchronous motor in which a rotor core is divided into three or more divided cores in the axial direction, and each divided core is stacked and arranged in the axial direction with a skew angle, a storage unit that preliminarily determines and stores the correlation between the rotor magnet average temperature of each divided core and the magnetic flux linkage number or inductance of the d-axis and q-axis magnets under load; a state estimator that calculates the current values ​​of the magnetic flux linkages of the d-axis and q-axis in the rotor synchronous coordinate system or the inductance from the current and voltage applied to the motor; a magnet temperature calculator that calculates the rotor magnet average temperature of each divided core based on the correlation using the d-axis and q-axis magnetic flux linkages or inductance in a loaded state as input values; A rotor magnet temperature estimation device comprising:

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