JP6428520B2 - Magnet temperature estimation system, motor, and magnet temperature estimation method - Google Patents

Description

  The present invention relates to a magnet temperature estimation system, a motor, and a magnet temperature estimation method.

  As one of synchronous motors, a permanent magnet type motor having a permanent magnet in a rotor is known. In such a permanent magnet type motor, the stator coil provided in the stator generates a rotating magnetic field when electric power is applied, and the rotating magnetic field acts on the permanent magnet, so that the rotor is within the stator. Rotate at.

  Generally, the temperature of the permanent magnet provided in the rotor increases as the rotation speed of the motor increases. Further, it is known that permanent magnets irreversibly demagnetize and lose magnetic force when a certain upper limit temperature is exceeded. Therefore, it is necessary to measure the temperature of the permanent magnet and limit the rotation speed of the motor so that the permanent magnet does not reach the upper limit temperature.

  However, if a temperature sensor is used to measure the temperature of the permanent magnet, it is necessary to incorporate the temperature sensor into the rotor, which makes it difficult to reduce the size of the motor. Therefore, a method for estimating the temperature of the permanent magnet without using a temperature sensor has been studied. For example, Patent Document 1 discloses a method for estimating the temperature of a permanent magnet using a current applied to a motor and an induced voltage generated in a stator.

JP 2007-6613 A

  The method disclosed in Patent Document 1 has a problem that, when the rotation speed of the motor is low, the induced voltage becomes small, so that the estimation accuracy of the temperature of the permanent magnet is deteriorated.

  This invention is made | formed in view of the said subject, The place made into the objective is the magnet temperature estimation system which can improve the estimation precision of the temperature of the permanent magnet with which the rotor of a motor is equipped, a motor, and It is to provide a magnet temperature estimation method.

  The magnet temperature estimation system of the present invention includes a motor including a stator including a stator coil and a rotor including a permanent magnet, and a magnet temperature estimation device that estimates the temperature of the permanent magnet. The rotor is provided so as to be in contact with the permanent magnet, and has a conductor that is arranged so that current flows through the magnetic flux of the stator coil. The magnet temperature estimating device superimposes AC power of a measurement frequency different from the drive frequency on the AC power of the drive frequency, and a power supply unit that applies AC power of the drive frequency that rotates the rotor to the stator coil. A superimposing unit; and a temperature estimating unit that measures impedance based on AC power at a measurement frequency and estimates the temperature of the permanent magnet according to the measured impedance.

  According to the present invention, the temperature of the permanent magnet is estimated using the correlation between the impedance of the motor and the temperature of the permanent magnet. Further, when the motor rotates, a current flows through the conductor due to the rotating magnetic field of the rotor coil acting on the conductor, so that the impedance changes according to the resistance value of the conductor.

  Here, the resistance value of the conductor has a characteristic that changes according to the temperature of the conductor. Therefore, by providing the conductor so as to be adjacent to the permanent magnet, the temperature characteristic of the resistance value of the conductor affects the correlation between the impedance and the temperature of the permanent magnet. Since the change amount per unit temperature of the resistance value of the conductor is relatively large, the change amount per unit temperature of the impedance can be increased by providing the conductor. Thus, since the amount of change per unit temperature of impedance becomes large, the estimation accuracy of the temperature of the permanent magnet by the magnet temperature estimation device can be improved.

FIG. 1 is a schematic configuration diagram of a magnet temperature estimation system according to the first embodiment. FIG. 2 is a sectional view of the motor. FIG. 3 is a schematic configuration diagram of the magnet unit. FIG. 4 is a system configuration diagram of the magnet temperature estimation device. FIG. 5 is a diagram showing an equivalent circuit that models a general motor. FIG. 6 is a graph showing the correlation between the real part Rd of the harmonic impedance and the magnet temperature Tm. FIG. 7 is a diagram showing an equivalent circuit in which the motor shown in FIG. 2 is modeled. FIG. 8 is a graph showing the correlation between the real part Rd of the harmonic impedance and the magnet temperature Tm. FIG. 9A is a cross-sectional view of the motor of the second embodiment. FIG. 9B is a schematic configuration diagram of the magnet unit shown in FIG. 9A. FIG. 10 is a schematic configuration diagram of a magnet unit according to the third embodiment. FIG. 11 is a schematic configuration diagram of a magnet unit according to the fourth embodiment. FIG. 12A is a cross-sectional view of the motor of the fifth embodiment. 12B is a schematic configuration diagram of the magnet unit illustrated in FIG. 12A. FIG. 13 is a graph showing the current flowing through the permanent magnet in the sixth embodiment. FIG. 14 is a graph showing the amount of heat generated in the magnet section.

  Embodiments of the present invention will be described below with reference to the drawings.

(First embodiment)
A magnet temperature estimation system according to a first embodiment of the present invention will be described.

  FIG. 1 is a schematic configuration diagram of a magnet temperature estimation system according to the first embodiment.

  The magnet temperature estimation system 100 includes a motor 1 and a magnet temperature estimation device 2.

  The motor 1 is a permanent magnet type synchronous motor (PMSM) that operates in three phases. The motor 1 includes a hollow cylindrical stator 11 and a rotor 12 rotatably provided in a hollow portion of the stator 11.

  The stator 11 includes a stator coil. When AC power having a predetermined drive frequency is supplied to the stator coil, the stator 11 generates a rotating magnetic field at a predetermined timing.

  The rotor 12 includes a permanent magnet. When the rotating magnetic field generated by the stator coil of the stator 11 acts on the permanent magnet, the stator coil and the permanent magnet are attracted or repelled to generate a rotational driving force, so that the rotor 12 is fixed to the stator 11. Rotate within.

  The magnet temperature estimation device 2 estimates the temperature of a permanent magnet included in the rotor 12 of the motor 1 while supplying AC power with a driving frequency to the motor 1.

  Next, a detailed configuration of the motor 1 will be described with reference to FIG.

  FIG. 2 is a cross-sectional view of the motor 1.

  A plurality of slots 21 penetrating in the axial direction of the stator 11 are formed in the stator 11 of the motor 1 at equal intervals in the circumferential direction of the stator 11. By forming a plurality of slots 21 in the stator 11 as described above, teeth 22 are formed between adjacent slots 21. And the stator coil 23 is provided so that the teeth 22 may be wound.

  In the rotor 12, a gap 24 extending in the axial direction is formed, and a magnet portion 25 including a permanent magnet is inserted into the gap 24. The magnet portions 25 are paired so as to substantially face each other, and the paired magnet portions 25 are provided at equal intervals in the circumferential direction. The substantially opposing magnet portions 25 are arranged so that the facing surfaces of those permanent magnets have the same polarity. Moreover, the magnet part 25 which opposes substantially and the magnet part 25 which opposes substantially next to it are arrange | positioned so that the polarity of the opposing surface of those permanent magnets may differ. Specifically, as shown in FIG. 2, when a magnet part 25 </ b> C and a magnet part 25 </ b> D that are substantially opposed to each other are provided next to the magnet part 25 </ b> A and the magnet part 25 </ b> B, the magnet part 25 </ b> A and the magnet part 25 </ b> A are provided. If the facing surface of the permanent magnet with 25B is the N pole, the facing surface of the permanent magnet between the magnet portion 25C and the magnet portion 25D is the S pole.

  The stator coil 23 generates a rotating magnetic field when AC power is applied from the magnet temperature estimation device 2. Since the direction of the rotating magnetic field by the stator coil 23 changes according to the phase of the applied AC power, the stator coil 23 and the permanent magnet of the magnet portion 25 of the rotor 12 alternately repeat attraction and repulsion. Thus, a rotational driving force is generated, and the rotor 12 rotates in the stator 11.

  Next, a detailed configuration of the magnet unit 25 will be described with reference to FIG.

  FIG. 3 is a schematic configuration diagram of a detailed configuration of the magnet unit 25. 3 indicates the axial direction of the rotor 12, that is, the direction toward the paper surface in FIG. Further, the front direction in FIG. 3 indicates a direction toward the stator 11 side in FIG.

  The magnet unit 25 includes a permanent magnet 31 composed of a plurality of magnet members 31 </ b> A stacked in the axial direction of the rotor 12. For example, a permanent magnet 31 composed of a plurality of such magnet members 31A is often used for a motor 1 such as an electric automobile that is required to operate with high efficiency. When the stator coil 23 generates a rotating magnetic field in accordance with the applied alternating current, an eddy current is generated on the surface of the permanent magnet 31 of the rotor 12, resulting in Joule loss. Therefore, by configuring the permanent magnet 31 with a plurality of magnet members 31A, the surface area per member can be reduced as compared with the case where the permanent magnet 31 is configured with one permanent magnet. By doing in this way, the path | route of an eddy current becomes short and the Joule loss by an eddy current can be reduced.

  In addition, a conductor thin film 32 is provided so as to cover the surface of the permanent magnet 31, that is, the surface forming the permanent magnet 31, and the surface interlinking with the magnetic flux of the permanent magnet 31. In the conductive thin film 32 thus provided, an eddy current is generated in the same manner as the permanent magnet 31. There are two surfaces that interlink with the magnetic flux of the permanent magnet 31 in the surface of the permanent magnet 31. The conductor thin film 32 is provided on the surface on the stator 11 side of the two surfaces.

  The conductor thin film 32 is made of a highly conductive conductor. Examples of the material having high conductivity include aluminum and copper having a mass heavier than aluminum and high conductivity. The conductive thin film 32 composed of such a conductor has a characteristic that the resistance value increases as the temperature rises.

  The thickness of the conductor thin film 32 is substantially equal to the current skin thickness as described below. In general, when harmonic AC power is applied to a coil, an eddy current flows through a conductor provided to be orthogonal to the direction of the magnetic flux generated by the coil. It is known that this eddy current flows through a portion from the surface of the conductor to a predetermined depth determined according to the frequency of the AC power and the material of the conductor. Such a phenomenon is called the skin effect, and the depth from the surface of the conductor through which the eddy current flows in the skin effect is called the current skin thickness. Such a current skin thickness can be obtained by the following equation.

ただし、式（１）においては、以下の各パラメータが用いられている。
ω：交流電力の角周波数
：導体の導電率
μ：導体の透磁率

However, in the formula (1), the following parameters are used.
ω: angular frequency of AC power: conductivity of conductor μ: permeability of conductor

  Even if the conductor thin film 32 is configured to be thicker than the current skin thickness, the eddy current flowing through the conductor thin film 32 is larger than that when the conductor thin film 32 is configured to have a thickness equal to the current skin thickness. Don't be. Therefore, by setting the thickness of the conductor thin film 32 in the stator direction, that is, in the magnetic flux direction to about the current skin thickness, it is possible to sufficiently increase the eddy current while suppressing the amount of conductor used.

  Further, the permanent magnet 31 and the conductor thin film 32 are joined by an adhesive member 33 having high thermal conductivity. The adhesive member 33 is an adhesive containing, as a filler, a material having excellent thermal conductivity such as alumina, aluminum nitride, or boron nitride.

  Next, the magnet temperature estimation device 2 will be described with reference to FIG.

  FIG. 4 is a system configuration diagram of the magnet temperature estimation device 2. Note that the two oblique lines and the three oblique lines attached to the input / output lines of each configuration indicate that the values input / output in each configuration are two-dimensional and three-dimensional vectors, respectively.

  As shown in FIG. 4, the magnet temperature estimation device 2 includes a power supply unit 41, a superposition unit 42, and a magnet temperature estimation unit 43.

The power supply unit 41 generates three-phase voltages vu, vv, and vw that are AC power at the drive frequency (fundamental wave) in accordance with fundamental wave current command values idsf ^* and iqsf ^* that are input from a motor controller (not shown). By outputting to the motor 1, the motor 1 is rotationally driven.

In order to estimate the temperature of the magnet unit 25, the superimposition unit 42 receives harmonic current command values idsc ^* and iqsc ^* of a measurement frequency that is a higher harmonic than the fundamental drive frequency. Then, the superimposing unit 42 outputs the harmonic voltage command values vdsc ^* and vqsc ^* according to the input to the power supply unit 41, whereby the power of the harmonic component is added to the AC power supplied to the motor 1 by the power supply unit 41. Is superimposed.

The magnet temperature estimator 43 obtains the impedance at the measurement frequency using the input harmonic current command values idsc ^* , iqsc ^* and the harmonic voltage command values vdsc ^* , vqsc ^*, and uses the obtained impedance. The magnet temperature Tm of the magnet unit 25 is estimated. Before the estimated magnet temperature Tm reaches the irreversible demagnetizing temperature of the permanent magnet 31, the fundamental wave current command values idsf ^* and iqsf ^* input to the power supply unit 41 are limited to reduce the rotation speed of the motor 1. By limiting, it is possible to prevent the permanent magnet 31 from being irreversibly demagnetized.

Note that the frequencies of the fundamental wave current command values idsf ^* and iqsf ^* vary according to the rotational speed at which the motor 1 is rotated. Further, the fundamental wave current command values idsf ^* and iqsf ^* are expressed using a rotation coordinate axis (dq axis).

The harmonic current command values idsc ^* and iqsc ^* are command values for supplying the motor 1 with harmonic power used for estimating the temperature of the permanent magnet 31 as described above. The frequencies of the harmonic current command values idsc ^* and iqsc ^* are assumed to be constant without being changed while the motor 1 is rotating. Further, in the present embodiment, the harmonic current command value iqsc ^* of the q-axis component is set to zero and the harmonic current command value idsc of the d-axis component is set so that the rotational torque is not generated in the motor 1 by the command value of the harmonic component. It is assumed that only ^* is changed and input to the magnet temperature estimation device 2. The amplitude of the harmonic current command value is assumed to be smaller than the amplitude of the fundamental current command value in order to reduce the influence on the motor 1.

  Next, detailed configurations of the power supply unit 41, the superimposing unit 42, and the magnet temperature estimation unit 43 will be described.

  The power supply unit 41 includes a subtracter 411, a current control unit 412, an adder 413, a coordinate conversion unit 414, a power conversion unit 415, a current detection unit 416, a coordinate conversion unit 417, and a band stop filter 418.

In the power supply unit 41, the fundamental wave current command values idsf ^* and iqsf ^* are input to the subtractor 411, and the harmonic voltage command values vdsc ^* and vqsc ^* are added from the resonance control unit 422 of the superimposing unit 42. Is input to the device 413. Then, the power conversion unit 415 outputs the three-phase voltages vu, vv, vw to the motor 1 in accordance with these inputs.

The subtractor 411 subtracts the fundamental wave detection current values idsf and iqsf from the fundamental wave current command values idsf ^* and iqsf ^* , respectively, and outputs the subtraction results to the current control unit 412. The fundamental wave detection current values idsf and iqsf are fundamental wave components of the detection value of the current applied to the motor 1.

The current control unit 412 is proportional so that the subtraction results of the subtractor 411 approach zero, that is, so that there is no deviation between the fundamental wave current command values idsf ^* and iqsf ^* and the fundamental wave current detection values idsf and iqsf. Integration control is performed, and the first voltage command values vd0 ^* and vq0 ^* are output to the adder 413.

The adder 413 adds the harmonic voltage command values vdsc ^* and vqsc ^* output from the resonance control unit 422 of the superposition unit 42 to the first voltage command values vd0 ^* and vq0 ^* output from the current control unit 412. . Then, the adder 413 outputs the second voltage command values vds ^* and vqs ^{* on} which the harmonic components are superimposed to the coordinate conversion unit 414.

The coordinate conversion unit 414 converts the second voltage command values vds ^* and vqs ^* output from the adder 413 from a rotation coordinate (dq axis) to a three-phase coordinate (uvw phase), and outputs a three-phase voltage. Command values vu ^* , vv ^* , vw ^* are calculated. Then, the coordinate conversion unit 414 outputs the calculated three-phase voltage command values vu ^* , vv ^* , vw ^* to the power conversion unit 415.

The power conversion unit 415 includes a power conversion circuit including, for example, a converter and an inverter. The power converter 415 is supplied with DC power from a battery (not shown). The power conversion unit 415 converts the DC power from the battery into AC three-phase voltages vu, vv, vw by controlling the inverter with the three-phase voltage command values vu ^* , vv ^* , vw ^* , Output to the motor 1. Note that a voltage type inverter or a current type inverter can be used as the inverter.

  The current detection unit 416 is configured using, for example, a Hall element or the like, and when the three-phase voltages vu, vv, and vw are applied to the motor 1, the three-phase current iu that flows from the magnet temperature estimation device 2 to the motor 1 is applied. iv and iw are detected. The current detection unit 416 outputs the detected three-phase currents iu, iv, iw to the coordinate conversion unit 417.

  The coordinate conversion unit 417 performs coordinate conversion from the three-phase coordinates to the rotation coordinates with respect to the three-phase currents iu, iv, iw detected by the current detection unit 416, and obtains detection currents ids, iqs. Then, the coordinate conversion unit 417 outputs the obtained detection currents ids and iqs to the band stop filter 418 and the band pass filter 423 of the superposition unit 42.

  The band stop filter 418 cuts the signal of the superimposed harmonic frequency band. Thereby, the band stop filter 418 outputs the fundamental wave detection current values idsf and iqsf obtained by cutting the harmonic components of the detection currents ids and iqs to the subtractor 411.

The superimposing unit 42 includes a subtractor 421, a resonance control unit 422, and a band pass filter 423. The superimposing unit 42 converts the harmonic voltage command values vdsc ^* and vqsc ^* into the adder 413 and the magnet temperature estimating unit of the power supply unit 41 according to the inputs of the harmonic current command values idsc ^* and iqsc ^* to the subtractor 421. Output to 43.

  The bandpass filter 423 passes only signals in the harmonic frequency band. As a result, the band pass filter 423 outputs the harmonic detection current values idsc and iqsc obtained by cutting the fundamental wave components of the detection currents ids and iqs output from the coordinate conversion unit 417 to the subtractor 421.

To the subtractor 421, the harmonic current command value IDSC ^*, with Iqsc ^* is input, the harmonic current value detected IDSC from band-pass filter 423, Iqsc is feedback input. The subtractor 421 subtracts the harmonic detection current values idsc and iqsc from the harmonic current command values idsc ^* and iqsc ^* , respectively, and outputs the subtraction result to the resonance control unit 422.

The resonance control unit 422 generates the harmonic voltage command values vdsc ^* and vqsc ^* so that the output from the subtracter 421 approaches zero. Then, the resonance control unit 422 outputs the harmonic voltage command values vdsc ^* and vqsc ^* to the adder 413 and the magnet temperature estimation unit 43 of the power supply unit 41.

The resonance control unit 422 can arbitrarily set the amplitude of the harmonic voltage command value and the output interval of the harmonic voltage command value. Note that the harmonic voltage command value vqsc ^* of the q-axis component is used for controlling the rotational torque of the motor 1. Therefore, so as not to affect the rotation torque of the motor 1, the resonance control section 422 outputs zero as the harmonic voltage command value of q-axis component Vqsc ^*, harmonic voltage command values of the d-axis component Vdsc ^* only Change to output.

In the present embodiment, it is assumed that the resonance control unit 422 outputs the harmonic voltage command value vdsc ^* by a pulsating vector injection method. Specifically, the resonance control unit 422 outputs the harmonic voltage command value vdsc ^* with alternating positive and negative signs. In this way, in the second voltage command values vds ^* and vqs ^* output from the adder 413 as a command value to the motor 1, the advance and delay of the harmonic voltage command value vdsc ^{* in} the d-axis direction Will occur alternately.

The magnet temperature estimating unit 43, the harmonic current command value IDSC ^*, with Iqsc ^* is input, the harmonic voltage instruction value vdsc from the resonance control unit 422 of the overlapping portion 42 ^*, vqsc ^* is input. As described above, the harmonic current command value iqsc ^* and the harmonic voltage command value vqsc ^* of the q-axis component are zero. Then, the magnet temperature estimation unit 43 estimates the temperature of the permanent magnet 31 according to the impedance measured using the harmonic voltage command value and the harmonic current command value.

Specifically, the magnet temperature estimation unit 43 has a bandpass filter (not shown) corresponding to the harmonic frequency to be superimposed, and the harmonic voltage command value applied by the pulsating vector injection method. Extract either positive or negative value of vdsc ^* . The magnet temperature estimation unit 43 can calculate the impedance Zh of the harmonic component using the input harmonic current command value idsc ^* and the harmonic voltage command value vdsc ^* that has passed through the band pass filter.

  Here, it is known that the real part Rd of the harmonic component impedance Zh has a correlation with the temperature of the magnet part 25 of the stator 11, that is, the temperature of the permanent magnet 31. Therefore, the magnet temperature estimation unit 43 stores in advance a table indicating the correlation between the real part Rd of the harmonic impedance and the temperature of the permanent magnet 31, and stores the calculated real part Rd of the harmonic impedance. The temperature of the permanent magnet 31 can be estimated using a table indicating the correlation.

  Here, the correlation between the real part Rd of the harmonic impedance measured by the magnet temperature estimation unit 43 and the temperature of the permanent magnet 31 will be described with reference to FIG.

  FIG. 5 is a diagram showing an equivalent circuit that models a general motor that can estimate the temperature of the permanent magnet by the magnet temperature estimation device 2. FIG. 5 (a) shows the configuration of the motor, and FIG. 5 (b) shows a magnetic flux circuit equivalent to the motor of FIG. 5 (a). It is assumed that no conductor thin film 32 is provided in the magnet portion 25 of the rotor 12 of the motor 1 in FIG.

  In FIG. 5A, the harmonic components of the three-phase voltages vu, vv, vw output from the power converter 415 shown in FIG. 4 are applied to the stator coil 23 as the harmonic voltage Vh. Further, the harmonic component of the current applied to the stator coil 23 is shown as a harmonic current Ih. This harmonic current Ih is a harmonic component of the three-phase currents iu, iv, iw detected by the current detector 416 in FIG.

  When the harmonic voltage Vh is applied to the stator coil 23 from the magnet temperature estimation device 2 (not shown in FIG. 5), the stator coil 23 generates a rotating magnetic field having a harmonic component with the magnet unit 25. . Therefore, an eddy current is generated on the surface of the permanent magnet 31 of the magnet unit 25 according to the harmonic component of the rotating magnetic field of the stator coil 23. Therefore, the magnet part 25 has an inductance component. In this way, when the motor 1 is rotating, the stator 11 and the rotor 12 constitute a magnetic flux circuit.

  Here, the stator coil 23 has a resistance component Rc and an inductance component Lc.

  In addition, the magnet unit 25 has a resistance component Rx and an inductance component Lx. In addition, since the magnet part 25 is mainly composed only of the permanent magnet 31, the resistance component Rx of the magnet part 25 becomes the resistance component Rm of the permanent magnet 31. Since the resistance component Rm of the permanent magnet 31 changes according to the magnet temperature Tm, the resistance component of the magnet unit 25 is represented as Rx (Tm). Further, the inductance component Lx of the magnet unit 25 becomes the inductance component Lm of the permanent magnet 31. Moreover, since the inductance component Lm of the magnet part 25 changes according to the magnet temperature Tm and the harmonic current value Ih, it shall be shown as Lx (Tm, Ih).

  Here, the harmonic impedance Zh is calculated from the harmonic voltage Vh and the harmonic current value Ih using the relationship of Zh = Vh / Ih. In such a case, the real part Rd of the harmonic impedance Zh is expressed by Expression (2).

ただし、Ｍは相互インダクタンス、ωは高調波電圧Ｖｈの角周波数である。なお、相互インダクタンスＭは、磁石温度Ｔｍ、および、高調波電流値Ｉｈに応じて変化するため、Ｍ（Ｔｍ，Ｉｈ）と示される。式（２）によれば、高調波インピーダンスの実部Ｒｄは、磁石部２５の温度である磁石温度Ｔｍと、図６に示すような相関関係がある。

Where M is the mutual inductance, and ω is the angular frequency of the harmonic voltage Vh. Since mutual inductance M changes according to magnet temperature Tm and harmonic current value Ih, it is indicated as M (Tm, Ih). According to the equation (2), the real part Rd of the harmonic impedance has a correlation as shown in FIG. 6 with the magnet temperature Tm which is the temperature of the magnet part 25.

  FIG. 6 is a graph showing the correlation between the real part Rd of the harmonic impedance and the magnet temperature Tm in the motor in which the conductor thin film 32 is not provided in the magnet part 25 as shown in FIG. The horizontal axis represents the magnet temperature Tm, and the vertical axis represents the real part Rd of the harmonic impedance. FIG. 6 shows a correlation in which the real part Rd of the harmonic impedance increases as the magnet temperature Tm increases. Therefore, the magnet temperature estimation unit 43 can estimate the magnet temperature Tm by using the real part Rd of the obtained harmonic impedance and the correlation as shown in FIG.

  Next, a motor in which the conductor thin film 32 is provided in the magnet portion 25 as in the present embodiment will be described. In such a motor, when the rotor 12 rotates, an eddy current is generated in the conductive thin film 32 provided perpendicular to the magnetic flux of the rotating magnetic field generated by the stator coil 23. Therefore, the motor 1 becomes an equivalent circuit as shown in FIG.

  FIG. 7 is a diagram showing an equivalent circuit of the motor 1 provided with the conductive thin film 32 as in the present embodiment. Compared with the equivalent circuit of the general motor shown in FIG. 5 in FIG. 7, a resistance component and an inductance component due to the conductive thin film 32 are added. The permanent magnet 31 has a resistance component Rm and an inductance component Lm. The conductive thin film 32 has a resistance component Rf and an inductance component Lf.

  Here, the resistance component Rx of the magnet portion 25 in the equation (2) is obtained by combining the resistance component Rm of the permanent magnet 31 and the resistance component Rf of the conductor thin film 32. Further, the inductance component Lx of the magnet portion 25 is obtained by combining the inductance component Lm of the permanent magnet 31 and the inductance component Lf of the conductor thin film 32. Therefore, the real part Rd of the impedance to be measured is the real part of the impedance of the entire rotor 12, that is, the real part of the impedance of the magnet unit 25 composed of the permanent magnet 21 and the conductive thin film 32.

  As described above, the resistance value of the conductive thin film 32 has a characteristic of increasing as the temperature rises. Therefore, the temperature characteristic of the conductor thin film 32 is added to the temperature characteristic of the resistance value Rx (Tm) of the magnet part 25 in the equation (2).

  FIG. 8 is a diagram showing a correlation between the real part Rd of the harmonic impedance and the magnet temperature Tm in the motor 1 in which the magnet part 25 includes the conductor thin film 32. The horizontal axis represents the magnet temperature Tm, and the vertical axis represents the real part Rd of the harmonic impedance.

  Here, when FIG. 6 when the magnet part 25 is not provided with the conductor thin film 32 and FIG. 8 when the magnet part 25 is provided with the conductor thin film 32 are compared, per unit temperature of the real part Rd of the harmonic impedance. The amount of change is larger when the conductor thin film 32 as shown in FIG. 8 is provided. This is because by providing the conductive thin film 32, the amount of change per unit temperature of the resistance component Rx of the magnet part 25 included in the denominator of the second term in Expression (2) becomes larger.

  The following effects can be obtained by the magnet temperature estimation system of the first embodiment.

  According to the magnet temperature estimation system 100 of the first embodiment, in the magnet temperature estimation device 2, the superimposing unit 42 outputs harmonic power to the fundamental power output from the power supply unit 41 and supplied to the motor 1. Is superimposed. Then, the magnet temperature estimation unit 43 obtains the impedance of the harmonic component by dividing the harmonic voltage Vh by the harmonic current Ih.

  In the rotor 12 of the motor 1, when the motor 1 rotates, a current flows through the conductive thin film 32 due to the rotating magnetic field generated by the stator coil 23. Since the current flows in the conductive thin film 32 in this way, as shown in FIG. 8, in the correlation between the real part Rd of the harmonic impedance measured by the magnet temperature estimation unit 43 and the magnet temperature Tm, the conductive thin film 32 is provided. Is taken into account. That is, compared with the correlation in the general motor shown in FIG. 6, the rate of change, which is the amount of change per unit temperature of the real part Rd of the harmonic impedance, is large. Therefore, the magnet temperature estimation unit 43 can estimate the temperature of the permanent magnet 31 with higher accuracy by using the correlation shown in FIG. 8 than in the case where the correlation shown in FIG. 6 is used.

  Further, according to the magnet temperature estimation system 100 of the first embodiment, the conductor thin film 32 is on the surface that forms the permanent magnet 31, that is, the surface that interlinks with the magnetic flux of the permanent magnet 31 among the surfaces of the permanent magnet 31. Is provided. Here, the rotating magnetic field of the stator coil 23 of the stator 11 and the magnetic field of the permanent magnet 31 of the magnet portion 25 of the rotor 12 are configured to be on the same straight line, and these magnetic fields influence each other. As a result, the motor 1 is rotationally driven. That is, the conductor thin film 32 is configured to be capable of interlinking with a rotating magnetic field. Therefore, when AC power is applied to the stator coil 23, an eddy current flows in the conductive thin film 32 provided so as to be linked to the rotating magnetic field of the stator coil 23.

  Since the eddy current flows in the conductor thin film 32 in this way, as shown in FIG. 8, the conductor thin film 32 is correlated with the real part Rd of the harmonic impedance measured by the magnet temperature estimating unit 43 and the magnet temperature Tm. Is taken into account. Therefore, since the rate of change of the real part Rd of the harmonic impedance is increased, the magnet temperature estimation unit 43 can estimate the temperature of the magnet unit 25 with higher accuracy.

  Moreover, according to the magnet temperature estimation system 100 of 1st Embodiment, the conductor thin film 32 is provided in the surface on the side facing the stator coil 23 among the surfaces where the magnetic flux of the permanent magnet 31 is linked. Here, among the surfaces where the magnetic flux of the permanent magnet 31 is interlinked, the rotating magnetic field of the stator coil 23 is greater on the surface facing the stator 11 than on the surface not facing the stator 11. The size of is large. Therefore, the influence of the temperature characteristics of the conductive thin film 32 on the correlation between the real part Rd of the harmonic impedance and the magnet temperature Tm increases. In this way, the conductor thin film 32 is provided on the surface on the side facing the stator coil among the surfaces where the magnetic flux of the permanent magnet 31 is linked, so that the amount of the conductor used is suppressed and the permanent thin film 32 is permanently removed. The estimation accuracy of the temperature of the magnet 31 can be increased.

  Further, according to the magnet temperature estimation system 100 of the first embodiment, the thickness of the conductor thin film 32 is determined according to the fundamental frequency that is the drive frequency, the conductivity of the conductor, and the permeability of the conductor. It is formed to have a current skin thickness. Since the eddy current flowing through the conductor flows only in the region inside the current skin thickness from the conductor surface, the eddy current cannot be increased even if the conductor thin film 32 is formed thicker than the current skin thickness. Therefore, by making the thickness of the conductor thin film 32 the current skin thickness, the influence of the temperature characteristics of the conductor thin film 32 on the correlation between the real part Rd of the harmonic impedance and the magnet temperature Tm can be sufficiently increased. Accordingly, it is possible to increase the estimation accuracy of the magnet temperature while suppressing the amount of the conductor used.

  Further, according to the magnet temperature estimation system 100 of the first embodiment, the permanent magnet 31 and the conductor thin film 32 are joined by the adhesive member 33 having good thermal conductivity, and thus the permanent magnet constituting the magnet portion 25. The temperature difference between 31 and the conductive thin film 32 can be reduced. Here, if a temperature difference occurs between the permanent magnet 31 and the conductive thin film 32, the correlation between the real part Rd of the measured harmonic impedance and the magnet temperature Tm is ideal as shown in FIG. It does not become a general correlation. Therefore, by reducing the temperature difference between the permanent magnet 31 and the conductor thin film 32, the temperature of the permanent magnet 31 measured using the correlation stored in advance and the actual temperature of the permanent magnet 31 are set. Since it can match more, the estimation precision of the temperature of the permanent magnet 31 can be improved.

  Moreover, according to the magnet temperature estimation system 100 of 1st Embodiment, the conductor thin film 32 is comprised, for example with aluminum. Since aluminum has good electrical conductivity and the eddy current generated is relatively large, by providing the aluminum conductor thin film 32, the rate of change of the real part Rd of the harmonic impedance with respect to the temperature of the magnet temperature Tm can be further increased. Can be bigger. Therefore, the estimation accuracy of the temperature of the permanent magnet 31 by the magnet temperature estimation unit 43 can be improved.

  Moreover, according to the magnet temperature estimation system 100 of 1st Embodiment, the conductor thin film 32 is comprised with copper, for example. Since copper has a better conductivity than aluminum, the rate of change of the harmonic impedance real part Rd with respect to the temperature of the magnet temperature Tm can be further increased by providing the copper conductor thin film 32. Therefore, the estimation accuracy of the temperature of the permanent magnet 31 by the magnet temperature estimation unit 43 can be further improved.

  Further, when the conductive thin film 32 is made of copper, the eddy current in the permanent magnet 31 is smaller because the eddy current in the conductive thin film 32 is larger than in the case where the conductive thin film 32 is made of aluminum. Thus, since the eddy current of the permanent magnet 31 becomes small, the heat loss by the eddy current in the permanent magnet 31 can be reduced. Therefore, by suppressing the temperature rise of the permanent magnet 31, the possibility that the permanent magnet 31 will be irreversibly demagnetized can be reduced.

(Second Embodiment)
In 1st Embodiment, the conductor thin film 32 demonstrated the example provided in the whole surface of the surface which links with the magnetic flux of the permanent magnet 31. FIG. In the second embodiment, an example will be described in which the conductive thin film 32 is provided on a part of the surface interlinked with the magnetic flux of the permanent magnet 31.

  FIG. 9A is a partial cross-sectional view of the motor 1 of the second embodiment. FIG. 9B is a schematic configuration diagram of the magnet unit 25 shown in FIG. 9A. In the present embodiment, it is assumed that the end portion on the stator 11 side among the surfaces that form the permanent magnet 31 is the highest temperature when the motor 1 rotates. As shown in FIGS. 9A and 9B, the conductive thin film 32 is thus provided at a location where the permanent magnet 31 is at the highest temperature when the motor 1 rotates.

  In general, the strength of the rotating magnetic field of the stator coil 23 that reaches the permanent magnet 31 differs for each part of the permanent magnet 31, so that the magnitude of eddy current generated in the permanent magnet 31 is biased, and the permanent magnet 31. The surface temperature is not uniform. In addition, it is known that the temperature of the permanent magnet 31 increases at a position close to an air gap that is a gap between the stator 11 and the rotor 12. The temperature distribution in the stator 11 when the motor 1 rotates can be obtained by design.

  The following effects can be obtained by the magnet temperature estimation system of the second embodiment.

  According to the magnet temperature estimation system 100 of the second embodiment, the conductive thin film 32 is provided at a place where the temperature becomes highest when the motor 1 rotates. Here, the correlation between the real part Rd of the impedance and the temperature of the permanent magnet 31 is influenced by the temperature characteristics of the conductive thin film 32 provided at the highest temperature when the motor 1 is operated. Therefore, the temperature of the permanent magnet 31 estimated by the magnet temperature estimation unit 43 is the temperature of the hottest place on the surface of the permanent magnet 31. Accordingly, by controlling the rotation of the motor 1 so that the estimated temperature of the permanent magnet 31 does not exceed the irreversible demagnetization temperature of the permanent magnet 31, a part of the surface of the permanent magnet 31 is irreversible of the permanent magnet 31. It is possible to prevent the demagnetization temperature from being exceeded. Therefore, in addition to reliably preventing irreversible demagnetization of the permanent magnet 31, the amount of conductor used can be reduced by providing the conductor thin film 32 on a part of the surface of the permanent magnet 32.

(Third embodiment)
In the first and second embodiments, the example in which the conductive thin film 32 made of a conductor is bonded by the bonding member 33 has been described. In the third embodiment, an example in which the conductive thin film 32 is configured by another method will be described.

  FIG. 10 is a schematic configuration diagram of the magnet unit 25 of the third embodiment.

  As shown in FIG. 10, the conductor thin film 32 is configured by plating a permanent magnet 31. Such conductor plating is performed using a plating material having corrosion resistance, such as zinc, copper, or nickel.

  The following effects can be obtained by the magnet temperature estimation system of the third embodiment.

  According to the magnet temperature estimation system 100 of the third embodiment, the conductor thin film 32 is configured by plating a part of the surface of the permanent magnet 31. In the manufacturing process of the motor 1, the magnet portion 25 is formed by providing the conductor thin film 32 so as to be adjacent to the permanent magnet 31, and then the magnet portion 25 is inserted into the gap 24 formed in the rotor 12. Therefore, as compared with the case where the conductor thin film 32 is fixed to the permanent magnet 31 using the adhesive member 33 as in the first embodiment, the permanent magnet 31 and the conductor thin film 32 are formed by providing the conductor thin film 32 by plating. Since it becomes difficult to isolate | separate, the insertion of the magnet part 25 to the space | gap 24 can be made easy.

  According to the magnet temperature estimation system 100 of the third embodiment, the conductor thin film 32 is made of a corrosion-resistant plating material. Therefore, since the permanent magnet 31 can be prevented from being rusted, the durability of the motor 1 can be improved.

(Fourth embodiment)
In the first to third embodiments, the example in which the conductor is provided as the conductor thin film 32 has been described. In the fourth embodiment, an example in which the conductor is provided in another shape will be described.

  FIG. 11 is a schematic configuration diagram of the magnet unit 25 of the fourth embodiment. As shown in FIG. 11, a conductor coil 1101 is provided instead of the conductor thin film 32 as compared with the first embodiment. The conductor coil 1101 is provided adjacent to the permanent magnet 31 and linked to the magnetic flux of the permanent magnet 31. The permanent magnet 31 and the conductor coil 1101 are joined by an adhesive member (not shown in this embodiment) having high thermal conductivity.

  The following effects can be obtained by the magnet temperature estimation system of the fourth embodiment.

  According to the magnet temperature estimation system 100 of the fourth embodiment, the conductor coil 1101 is provided so as to interlink with the magnetic flux of the permanent magnet 31. When the motor 1 rotates, the rotating magnetic field of the stator coil 23 of the stator 11 alternates the conductor coil 1101, so that an induced power is generated in the conductor coil 1101 and a current flows.

  Therefore, similarly to the first embodiment, the temperature characteristic of the conductor coil 1101 is added to the temperature characteristic of the resistance value Rx (Tm) of the magnet unit 25 in the equation (2). Therefore, since the amount of change per unit temperature of the real part Rd of the harmonic impedance can be increased, the accuracy of estimating the temperature of the permanent magnet 31 by the magnet temperature estimation unit 43 can be improved.

(Fifth embodiment)
In 1st thru | or 4th embodiment, the example of the structure of the conductor provided adjacent to the permanent magnet 31 was demonstrated. In the fifth embodiment, another configuration of the magnet portion 25 in the gap 24 will be described.

  FIG. 12A is a part of a cross-sectional view of the motor 1 of the fifth embodiment. FIG. 12B is a perspective view of a configuration in the vicinity of the magnet portion 25 of FIG. 12A. In FIG. 12B, the internal configuration of the resin 1201 shown in FIG. 12A is indicated by a dotted line.

  The conductor provided in the present embodiment is a conductor coil 1101 as in the fourth embodiment. As shown in FIGS. 12A and 12B, the magnet portion 25 is molded with a resin 1201 in the gap 24 in comparison with the configuration in the vicinity of the magnet portion 25 of the fourth embodiment shown in FIG. 11. The point is different.

  The resin 1201 is made of a material having high thermal conductivity and insulation. Examples of the resin 1201 include silicon-based resin and micro silver paste. In addition, the resin 1201 may be, for example, an epoxy resin in which a material having excellent thermal conductivity such as alumina, aluminum nitride, or boron nitride is contained as a filler. It is assumed that the permanent magnet 31 and the conductor coil 1101 are molded by the resin 1201 after being joined by the adhesive member 33 having high thermal conductivity. Note that the permanent magnet 31 and the conductor coil 1101 may be fixed only by the resin 1201 without using the adhesive member 33.

  In addition, although this embodiment demonstrated the example in which the magnet part 25 provided with the conductor coil 1101 like 4th Embodiment was molded with resin 1201, it is not restricted to this. As in the first to third embodiments, the magnet part 25 including the conductor thin film 32 may be molded with the resin 1201.

  The following effects can be obtained by the magnet temperature estimation system of the fifth embodiment.

  According to the magnet temperature estimation system 100 of the fifth embodiment, the magnet unit 25 is molded using the resin 1201 having high thermal conductivity. Therefore, in the magnet part 25, the temperature difference between the permanent magnet 31 and the conductor coil 1101 can be reduced. Therefore, since the correlation between the measured impedance and the permanent magnet 31 can be made more consistent with the ideal correlation as shown in FIG. 8, the temperature estimation accuracy of the permanent magnet 31 can be improved. it can.

  In particular, when the conductor coil 1101 and the permanent magnet 31 are not in close contact with each other and there is an air layer between them, the air layer has a high heat insulating property. A temperature difference may occur. Therefore, since the temperature difference between the permanent magnet 31 and the conductor coil 1101 can be reduced by molding using the resin 1201 having high thermal conductivity, the estimation accuracy of the temperature of the permanent magnet 31 can be improved. .

  Moreover, according to the magnet temperature estimation system 100 of 5th Embodiment, the magnet part 25 is molded by resin 1201 with high insulation. By being configured in this way, the leakage magnetic flux from the permanent magnet 31 to the rotor 12 composed of an electromagnetic steel plate or the like can be reduced, so that a reduction in the rotation efficiency of the motor 1 can be suppressed.

(Sixth embodiment)
In 1st Embodiment, the example which improves the estimation precision of the permanent magnet 31 by providing the conductive thin film 32 was demonstrated. In the sixth embodiment, an example in which the conductor thin film 32 is designed so as to suppress heat generation in the permanent magnet 31 will be described.

  First, the magnitude of the eddy current flowing through the permanent magnet 31 when the conductor thin film 32 is provided in the magnet portion 25 will be examined.

  As described above, FIG. 7 shows a magnetic flux circuit composed of the stator 11 and the rotor 12 when the conductor thin film 32 is provided in the magnet portion 25. In FIG. 7, the magnetic flux φext by the stator coil 23 and the permanent magnet 31 in the electromagnetic steel plates of the stator 11 and the rotor 12 is shown. Further, the eddy current flowing through the permanent magnet 31 is indicated as a magnet eddy current Im, and the current flowing through the conductor thin film 32 is indicated as a conductor current If. In the magnetic flux circuit shown in FIG. 7, the relationship between the magnet eddy current Im and the conductor current If and the magnetic flux φext can be expressed by the following equations, respectively.

ただし、式（３）、（４）においては、以下の各パラメータが用いられている。
Ｎｍ：永久磁石３１を渦電流が流れる導体と仮定した場合の等価ターン数（＝１）
Ｒｍ：永久磁石３１の抵抗成分
Ｌｍ：永久磁石３１のインダクタンス成分
Ｎｆ：導体薄膜３２のターン数
Ｒｆ：導体薄膜３２の抵抗成分
Ｌｆ：導体薄膜３２のインダクタンス成分
Ｒ：固定子１１及び回転子１２により構成される磁路の磁気抵抗値
ｊ：虚数単位
ω：測定周波数の交流電力の角周波数

However, in the equations (3) and (4), the following parameters are used.
Nm: equivalent number of turns when the permanent magnet 31 is assumed to be a conductor through which eddy current flows (= 1)
Rm: Resistance component of permanent magnet 31 Lm: Inductance component of permanent magnet 31 Nf: Number of turns of conductor thin film 32 Rf: Resistance component of conductor thin film 32 Lf: Inductance component of conductor thin film 32 R: By stator 11 and rotor 12 Magnetoresistance value of magnetic path j: imaginary unit ω: angular frequency of AC power at measurement frequency

  Next, the magnitude of the eddy current flowing through the permanent magnet 31 when the conductor thin film 32 is provided in the magnet portion 25 will be examined. In such a case, since there is no eddy current in the conductor thin film 32, the component resulting from the conductor thin film 32 is not included in the equation (3). Therefore, when the conductor thin film 32 is not provided, the frequency characteristics of the basic eddy current Im ′ that is an eddy current flowing through the permanent magnet 31 and the magnetic flux φext can be expressed by the following equation.

ここで、磁石渦電流Ｉｍの基本渦電流Ｉｍ’に対する比率、すなわち、導体薄膜３２を設けることにより永久磁石３１に流れる電流の増減率は、式（３）及び式（５）から、次の式のように表される。

Here, the ratio of the magnet eddy current Im to the basic eddy current Im ′, that is, the rate of increase / decrease of the current flowing through the permanent magnet 31 by providing the conductive thin film 32, is calculated from the following equation from the equations (3) and (5) It is expressed as

そこで、磁石渦電流Ｉｍが基本渦電流Ｉｍ’よりも小さくなるように（Ｉｍ＜Ｉｍ’）、すなわち、式（６）により求まる増減率が1未満となるように、導体薄膜３２の物理量であるパラメータ（ターン数Ｎｆ、電気抵抗Ｒｆ、インダクタンスＬｆ）および測定周波数ｆｈを設計する。このように設計することにより、永久磁石３１に流れる渦電流を減少させることができる。そのため、永久磁石３１の発熱を抑制することができ、永久磁石３１が不可逆消磁してしまうおそれを低減することができる。

Therefore, the physical quantity of the conductor thin film 32 is such that the magnet eddy current Im is smaller than the basic eddy current Im ′ (Im <Im ′), that is, the increase / decrease rate obtained by the equation (6) is less than 1. Design parameters (number of turns Nf, electrical resistance Rf, inductance Lf) and measurement frequency fh. By designing in this way, the eddy current flowing through the permanent magnet 31 can be reduced. Therefore, the heat generation of the permanent magnet 31 can be suppressed, and the possibility that the permanent magnet 31 is irreversibly demagnetized can be reduced.

  When the parameters of the conductor thin film are already determined and the magnetic flux φext is constant, referring to the equations (3) and (5), the magnet eddy current Im and the basic eddy current Im ′ are It changes in accordance with the angular velocity ω of the power applied to the motor 1, that is, the measurement frequency fh. An example of the relationship between the magnet eddy current Im and the basic eddy current Im 'and the measurement frequency fh is shown in FIG.

  FIG. 13 is a diagram illustrating an example of the relationship between the measurement frequency fh and the magnet eddy current Im when the conductor thin film 32 is provided, the basic eddy current Im ′ when the conductor thin film 32 is not provided, and the measurement frequency fh. is there. The vertical axis indicates the current value, the horizontal axis indicates the frequency, the magnet eddy current Im is indicated by a solid line, and the basic eddy current Im 'is indicated by a dotted line.

  This figure shows that the magnet eddy current Im becomes smaller than the basic eddy current Im ′ when the measurement frequency fh exceeds a predetermined frequency fx. Therefore, the eddy current in the permanent magnet 31 can be reduced by making the harmonic measurement frequency fh superimposed by the superimposing unit 42 of the magnet temperature estimation device 2 higher than the predetermined frequency fx.

In the rotor 12, not only the permanent magnet 31 but also the conductive thin film 32 generates heat. Therefore, it is preferable to design the conductor thin film 32 in consideration of the heat generation amount of the entire rotor 12, that is, the heat generation amounts of the permanent magnet 31 and the conductor thin film 32.

  First, the amount of heat generated by the magnet unit 25 when the conductor thin film 32 is provided on the magnet unit 25 will be examined. The calorific value of the magnet unit 25 can be obtained as the sum of the calorific values of the permanent magnet 31 and the conductor thin film 32 constituting the magnet unit 25. The Joule loss Wm generated by the magnet eddy current Im in the permanent magnet 31 is the product of the electric resistance Rm of the permanent magnet 31 and the square of the magnet eddy current Im. The Joule loss Wf generated by the conductor current If in the conductor thin film 32 is the product of the electrical resistance Rf of the conductor thin film and the square of the conductor current If. By obtaining such a sum of Ws and Wf, the amount of generated heat Wall in the magnet portion 25 can be obtained.

  Next, the amount of heat generated by the magnet unit 25 when the conductor thin film 32 is not provided in the magnet unit 25 will be considered. The magnet portion 25 is mainly composed of only the permanent magnet 31, and the Joule loss Wm 'generated by the basic eddy current Im in the permanent magnet 31 is the product of Rm and Im'. Such a Joule loss Wm ′ in the permanent magnet 31 becomes a heat generation amount Wall ′ in the magnet unit 25.

Therefore, the Joule loss Wall when the conductor thin film 32 is provided in the magnet portion 25 is smaller than the Joule loss Wall ′ when the conductor thin film 32 is not provided in the magnet portion 25. Parameters (Nf, Rf, Lf), which are physical quantities, and a measurement frequency fh are designed. By designing in this way, the heat generation of the rotor 12, that is, the entire magnet unit 25 can be suppressed, so that the heat generation of the permanent magnet 31 can be more reliably suppressed.

  FIG. 14 is a diagram illustrating an example of the relationship between each of the joule losses described above and the measurement frequency.

  In this figure, the Joule loss Wm of the permanent magnet 31 and the Joule loss Wf of the conductor thin film 32 when the conductor thin film 32 is provided in the magnet portion 25 are respectively shown by a one-dot broken line and a two-dot broken line. It is shown. And the Joule loss Wall of the magnet part 25 which is the sum of the Joule loss Wm of the permanent magnet 31 and the Joule loss Wf of the conductor thin film 32 is shown by the solid line.

  Further, the Joule loss Wall 'of the magnet portion 25, that is, the Joule loss Wall' of the permanent magnet 31 when the conductor thin film 32 is not provided in the magnet portion 25 is indicated by a dotted line. Since the magnet portion 25 is composed only of the permanent magnet 31, the Joule loss Wall ′ of the permanent magnet 31 is equal to the heat generation amount Wm ′ of the permanent magnet 31.

  As shown in FIG. 14, in the frequency band where the measurement frequency fh is lower than the predetermined frequency fy, the Joule loss Wall becomes smaller than the Joule loss Wall '. Therefore, the heat generation in the magnet unit 25 can be reduced by setting the measurement frequency fh lower than the predetermined frequency fy.

  In the present embodiment, the example in which the conductor provided adjacent to the permanent magnet 31 is the conductor thin film 32 has been described, but the present invention is not limited thereto. Even if the conductor is the conductor coil 1101, it can be optimally designed using the same method.

  The following effects can be obtained by the magnet temperature estimation system of the sixth embodiment.

  According to the magnet temperature estimation system 100 of the sixth embodiment, the parameters (number of turns Nf, electrical resistance Rf, inductance Lf) that are physical quantities of the conductor thin film 32 and the superimposing unit 42 of the magnet temperature estimation device 2 are superimposed. Depending on the measurement frequency fh, the magnitude of the eddy current flowing through the permanent magnet 31 changes.

  Therefore, the physical quantity of the permanent magnet 31 and the measurement frequency fh are set so that the magnet eddy current Im when the magnet unit 25 includes the conductor thin film 32 is smaller than the basic eddy current Im ′ when the conductor thin film 32 is not provided. Determine. By doing so, the eddy current flowing in the permanent magnet 31 can be reduced by providing the conductive thin film 32.

  Specifically, the increase / decrease rate of the eddy current flowing through the permanent magnet 31 when the conductive thin film 32 is provided can be expressed as in Expression (6). Therefore, the parameters (number of turns Nf, electrical resistance Rf, inductance Lf) of the permanent magnet 31 and the measurement frequency fh are designed so that the increase / decrease rate obtained by Expression (6) is less than 1. By using the physical quantity of the conductor thin film 32 designed in this way and the measurement frequency fh, the eddy current flowing through the permanent magnet 31 can be reduced. Therefore, since heat generation due to the eddy current in the permanent magnet 31 can be suppressed, the possibility that the permanent magnet 31 is irreversibly demagnetized can be reduced.

  Further, for example, when the magnet eddy current Im and the basic eddy current Im ′ and the measurement frequency fh are in the relationship as shown in FIG. 13, the magnet eddy current in a frequency band higher than the predetermined frequency fx. The current Im becomes smaller than the basic eddy current Im ′. Therefore, the eddy current flowing through the permanent magnet 31 can be reduced by setting the measurement frequency fh to be higher than the predetermined frequency fx.

  By reducing the eddy current flowing through the permanent magnet 31 in this way, heat generation due to the eddy current in the permanent magnet 31 can be suppressed, and therefore, the possibility that the permanent magnet 31 is irreversibly demagnetized can be reduced.

  Further, according to the magnet temperature estimation system 100 of the sixth embodiment, the physical quantity of the magnet unit 25 and the measurement frequency fh can be determined so as to reduce the heat generation amount of the entire magnet unit 25.

  Here, when the heat generation amount Wall of the magnet portion 25 is examined, when the conductor thin film 32 is provided, the heat generation amount Wall of the magnet portion 25 is the heat generation amount Ws of the permanent magnet 31 and the heat generation amount of the conductor thin film 32. It can be obtained from the sum of Wf. The calorific value Wm in the permanent magnet 31 is the product of the resistance value Rm of the permanent magnet and the square of the magnet eddy current Im in the permanent magnet 31. Further, the heat generation amount Wf in the conductor thin film 32 is a product of the square of the resistance value Rf of the conductor thin film 32 and the conductor current If in the conductor thin film 32.

  Further, when the conductor thin film 32 is provided, the heat generation amount Wall ′ of the magnet portion 25 becomes the heat generation amount Wm ′ of the permanent magnet 31. The heat generation amount Wm ′ in the permanent magnet 31 is the product of the square of the resistance value Rm of the permanent magnet and the basic eddy current Im ′ in the permanent magnet 31.

  Therefore, the measurement frequency fh and the parameters (number of turns Nf, electrical resistance Rf, inductance Lf) of the permanent magnet 31 are designed so that the heat generation amount Wall becomes smaller than Wall ′. And the calorific value in the magnet part 25 can be reduced by forming the conductor thin film 32 based on the design value.

  For example, when the relationship between the Joule heat Wall and Wall ′ and the measurement frequency fh is as shown in FIG. 14, the Joule heat Wall is in a frequency band higher than the predetermined frequency fy. It becomes smaller than Wall '. Therefore, by setting the measurement frequency fh to be smaller than the predetermined frequency fy, it is possible to suppress heat generation in the magnet portion 25 in which the conductor thin film 32 is formed.

  In this way, heat generation in the permanent magnet 31 is suppressed, and the possibility that the permanent magnet 31 is irreversibly demagnetized can be reduced. Moreover, since unnecessary heat generation can be suppressed, the operating efficiency of the motor 1 can be improved.

  The embodiment of the present invention has been described above. However, the above embodiment only shows a part of application examples of the present invention, and the technical scope of the present invention is limited to the specific configuration of the above embodiment. Absent. Moreover, the said embodiment can be combined suitably.

DESCRIPTION OF SYMBOLS 100 Magnet temperature estimation system 1 Motor 11 Stator 12 Rotor 2 Magnet temperature estimation apparatus 21 Slot 22 Teeth 23 Stator coil 24 Air gap 25, 25A, 25B, 25C, 25D Magnet part 31 Permanent magnet 31A Magnet member 32 Conductor thin film 33 Bonding Members 41 Power supply unit 411 Subtractor 412 Current control unit 413 Adder 414 Coordinate conversion unit 415 Power conversion unit 416 Current detection unit 417 Coordinate conversion unit 418 Band stop filter 42 Superposition unit 421 Subtractor 422 Resonance control unit 423 Band pass filter 43 Magnet temperature estimation unit 1101 Conductor coil 1201 Resin

Claims (17)

A magnet temperature estimation system having a motor including a stator including a stator coil and a rotor including a permanent magnet, and a magnet temperature estimation device configured to estimate the temperature of the permanent magnet,
The rotor is
A conductor provided so as to be in contact with the permanent magnet and arranged so that a current flows through the magnetic flux of the stator coil;
The magnet temperature estimation device includes:
A power supply unit that applies AC power of a driving frequency for rotating the rotor to the stator coil;
A superimposing unit that superimposes AC power of a measurement frequency different from the driving frequency on AC power of the driving frequency;
A temperature estimation unit that measures impedance based on alternating current power of the measurement frequency and estimates the temperature of the permanent magnet according to the measured impedance;
A magnet temperature estimation system characterized by that. The magnet temperature estimation system according to claim 1,
The conductor is a conductive thin film provided on a surface where the magnetic flux of the permanent magnet interlinks among the surfaces forming the permanent magnet.
A magnet temperature estimation system characterized by that. The magnet temperature estimation system according to claim 2,
The conductor thin film is provided on the surface facing the stator coil among the surfaces where the magnetic flux of the permanent magnets is linked.
A magnet temperature estimation system characterized by that. The magnet temperature estimation system according to claim 2 or 3,
The thickness of the conductor thin film is determined by the driving frequency and the material of the conductor thin film.
A magnet temperature estimation system characterized by that. The magnet temperature estimation system according to any one of claims 2 to 4,
The conductor thin film is provided in a place where the temperature is highest during rotation of the motor, among the surfaces forming the permanent magnet.
A magnet temperature estimation system characterized by that. The magnet temperature estimation system according to any one of claims 2 to 5,
The conductor thin film and the permanent magnet are joined using a heat conducting member,
A magnet temperature estimation system characterized by that. The magnet temperature estimation system according to any one of claims 2 to 6,
The conductive thin film is made of aluminum.
A magnet temperature estimation system characterized by that. The magnet temperature estimation system according to any one of claims 2 to 6,
The conductor thin film is made of copper.
A magnet temperature estimation system characterized by that. The magnet temperature estimation system according to any one of claims 2 to 5,
The conductor thin film is formed by plating a surface on which the permanent magnet is formed.
A magnet temperature estimation system characterized by that. The magnet temperature estimation system according to claim 9,
The conductor thin film is composed of a corrosion-resistant plating material.
A magnet temperature estimation system characterized by that. The magnet temperature estimation system according to claim 1,
The conductor is a magnet coil wound around the permanent magnet so as to interlink with the magnet magnetic flux.
A magnet temperature estimation system characterized by that. The magnet temperature estimation system according to any one of claims 1 to 11,
In the stator, a gap for arranging the permanent magnet is formed,
The conductor and the permanent magnet are molded with a heat conductive resin in the gap,
A magnet temperature estimation system characterized by that. The magnet temperature estimation system according to any one of claims 1 to 12,
In the stator, a gap for arranging the permanent magnet is formed,
The conductor and the permanent magnet are molded with an insulating resin in the gap.
A magnet temperature estimation system characterized by that. The magnet temperature estimation system according to any one of claims 1 to 13,
The conductor is formed so that a current flowing through the permanent magnet determined based on the measurement frequency and a physical quantity of the conductor is reduced.
A magnet temperature estimation system characterized by that. The magnet temperature estimation system according to any one of claims 1 to 14,
The conductor is formed such that the sum of Joule heat generated in the rotor determined based on the measurement frequency and a physical quantity of the conductor is reduced.
A magnet temperature estimation system characterized by that. The stator including a stator coil and a rotor including a permanent magnet, and the magnet temperature estimation device superimposes alternating current power of a measurement frequency that is different from a driving frequency for rotationally driving the rotor. A motor in which alternating current power at a driving frequency is applied and the temperature of the permanent magnet is estimated according to impedance measured based on alternating current power at the measurement frequency,
The rotor is
A conductor provided so as to be in contact with the permanent magnet and having a conductor arranged so that a current flows through the magnetic flux of the stator coil;
A motor characterized by that. The stator includes a stator coil and a rotor including a permanent magnet. The rotor is provided in contact with the permanent magnet so that the magnetic flux of the stator coil acts and current flows. A magnet temperature estimation method for estimating the temperature of the permanent magnet in a motor having a conductor arranged in
A power supply step of applying AC power of a driving frequency for rotating the rotor to the stator coil;
A superposition step of superimposing AC power of a measurement frequency different from the drive frequency on AC power of the drive frequency;
A temperature estimation step of measuring an impedance based on the power of the measurement frequency and estimating a temperature of the permanent magnet according to the measured impedance.
A method for estimating a magnet temperature.

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