JP2006254521A - Control device of synchronous machine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a control device of a synchronous machine that accurately estimates the temperature of a permanent magnet of the synchronous machine having no magnetic pole sensor. <P>SOLUTION: In the control device of the magnetic pole sensor-less synchronous machine: an armature interlinkage magnetic flux operation part 12a of a magnet temperature estimation part 12 performs current-voltage mapping to a coordinated system displaced at an angle of Δθ between a control axis (γ-δ axis) and a magnet axis (d-q axis); the Δθ and an interlinkage magnetic flux amount Φ are dynamically changed; the armature interlinkage magnetic flux amount is operated and a magnet temperature is estimated from the ratio of the armature interlinkage magnetic flux amount and a reference armature interlinkage magnetic flux amount by a magnet temperature estimation operation part 12b on the basis of the armature interlinkage magnetic flux amount; next, a carrier frequency is increased and a modulation system is changed by the magnet temperature automatic lowering operation of a non-reversible demagnetization determination part 13 and by a demagnetization determination operation part 13a; the temperature of the permanent magnet is lowered; a non-reversible demagnetized magnetism generation current obtained from a correlation table between the lowered temperature of the permanent magnet and a non-reversible demagnetized magnetism generation current and a non-reversible demagnetization mode current table value at the failure of an inverter are compared; and an alarm is outputted from an alarm output part 13b. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a controller for a permanent magnet type synchronous machine that uses a magnet for a rotor and does not use a position sensor and a speed sensor.

Industrial equipment such as compressors, fans, and pumps are promoted to save energy in order to reduce carbon dioxide emissions for the purpose of protecting the global environment.
Above all, it is known that the energy saving of the motor can realize a significant energy saving by adopting the magnet type motor, and the research and development is actively carried out.
There are many researches on rotor structure for energy saving, optimal current vector control, etc., but not only energy saving but also irreversible demagnetization of permanent magnets with vector control drive using permanent magnet synchronous machine It is. Once this occurs, motor performance is reduced. Irreversible demagnetization is a composite factor of abnormal magnet temperature and excessive current (armature reaction) from the stator side winding in that state.
However, since it is difficult to directly measure the abnormal magnet temperature, in the control device that performs current vector control, the armature linkage flux amount of the motor is calculated based on the motor voltage and motor current in the dq axis coordinate system. There has been proposed a control device for calculating the magnet temperature from the relationship between the magnet temperature stored in advance in the microcomputer memory and the amount of armature linkage magnetic flux.
The armature interlinkage flux calculation method does not depend on a method of estimating the fundamental wave component by inverse calculation of the voltage equation of the rotating coordinate system (see Patent Document 1) and a motor constant (for example, resistance) in the voltage equation. A method (see Patent Document 2) for newly adding and estimating a rotational coordinate system of harmonic components has been proposed.
JP-A-11-18496 JP 2003-235286 A

However, the motor control devices disclosed in Patent Documents 1 and 2 described above are intended to estimate the amount of armature interlinkage magnetic flux based on speed / magnetic pole position information obtained by a sensor attached to the motor. This is because, for example, in a control device in which a sensor cannot be mounted due to mounting space or cost constraints, the magnet position cannot be accurately grasped, so that the accuracy of the armature interlinkage magnetic flux amount deteriorates (first problem) )was there.
Furthermore, the motor control device disclosed in Patent Document 2 is a method for estimating the magnet temperature from the estimated armature linkage magnetic flux amount, in advance in the microcomputer internal memory, the armature linkage magnetic flux amount of the motor to be controlled. A correlation table obtained by actually measuring the magnet temperature is stored, and the magnet temperature is estimated by referring to the memory address. However, this method has a drawback (second problem) that a versatile control device cannot be made because the table needs to be reviewed when the target motor is different.
Furthermore, in the motor control devices disclosed in Patent Documents 1 and 2, when the magnet temperature exceeds the allowable temperature, the current command is adjusted for motor output adjustment, or the limit of the magnet temperature is irreversible demagnetization. It is proposed to stop the control device by the system stop signal when the temperature is exceeded. However, in this method, when the magnet temperature exceeds the limit temperature, it may be over-protected for industrial equipment that requires continuous operation because of an immediate stop. That is, the occurrence of irreversible demagnetization is affected not only by the magnet temperature but also by the current, and it has been necessary to perform irreversible demagnetization protection and risk management of demagnetization from both sides of the magnet temperature and current (third problem).
The present invention has been made to solve these problems, and is a control device for a synchronous machine with no sensor attached, which performs high-precision armature flux linkage estimation and permanent magnet temperature estimation, The purpose is to prevent irreversible demagnetization. It is another object of the present invention to provide a control device for a synchronous machine that is versatile and does not provide excessive protection for industrial equipment that requires continuous operation.

In order to solve the above-mentioned problems, an invention according to claim 1 relates to a control device for a synchronous machine, wherein a power converter that drives by driving an AC voltage to a synchronous machine using a permanent magnet as a rotor, and the synchronous machine In a Cartesian coordinate system (γ-δ axis coordinate) that rotates in synchronization with the fundamental wave component of the flowing current but with a deviation of Δθ from the magnet axis (dq axis), the fundamental wave current of the synchronous machine is commanded A current control unit that calculates a fundamental voltage command for matching the value, a speed control unit that calculates a torque command to match the rotation speed of the synchronous machine with a rotation speed command value, and a calculation from the current control unit An AC voltage control means for calculating an AC voltage to be applied to the synchronous machine based on the fundamental wave voltage command value, wherein the rotational speed or rotational position of the synchronous machine is synchronized with the synchronous voltage. Machine impedance or power And estimation control means for estimating the observer, such as a current equation inverse model,
Based on the rotation speed of the synchronous machine estimated from the estimation control unit, the fundamental wave current command or fundamental wave current, and the fundamental wave voltage command, the armature interlinkage flux amount of the permanent magnet is converged. Magnetic flux calculation means;
Magnet temperature estimating means for estimating the temperature of the permanent magnet based on the armature linkage magnetic flux of the permanent magnet calculated by the magnetic flux calculating means, and irreversible demagnetization for determining the irreversible demagnetization of the permanent magnet from the magnet temperature. It is characterized by having a judging means.
According to a second aspect of the present invention, there is provided the synchronous machine control device according to the first aspect, wherein the magnetic flux calculation means is a rotation speed of the synchronous machine estimated from the estimation control means and the fundamental wave current command or fundamental wave current. And the armature linkage flux amount of the permanent magnet and the deviation Δθ are dynamically changed based on the fundamental wave voltage command, and the armature linkage flux amount of the permanent magnet is converged and calculated. It is characterized by being.
According to a third aspect of the present invention, in the synchronous machine control device according to the first aspect, the magnet temperature estimating means includes a ratio of the calculated armature interlinkage magnetic flux amount to the reference temperature armature interlinkage magnetic flux amount, and The temperature of the permanent magnet is estimated using a magnet temperature coefficient of the permanent magnet.
According to a fourth aspect of the present invention, in the synchronous machine control device according to the first aspect, when the irreversible demagnetization generation current at the permanent magnet temperature estimated by the irreversible demagnetization determining means exceeds an allowable current, The carrier frequency inside the power converter is increased, or the modulation system inside the power converter is changed from two phases to three phases.
According to a fifth aspect of the present invention, in the control device for a synchronous machine according to the fourth aspect, a table of irreversible demagnetization generation current with respect to the permanent magnet temperature is provided, and the irreversible demagnetization generation current value with respect to the estimated temperature of the permanent magnet. And the irreversible demagnetization generation current value is compared with at least one of an overcurrent value for power conversion protection, a three-phase short-circuit current at the time of IGBT failure, and a one-phase short-circuit current value.
According to a sixth aspect of the present invention, in the control device for the synchronous machine according to the fifth aspect, as a result of the comparison, the overcurrent value, the three-phase short-circuit current value, When the one-phase short circuit current value is larger, a warning alarm is displayed.

According to the first aspect of the present invention, it is possible to accurately estimate the magnet temperatures of the permanent magnet and the synchronous machine that do not include a position / speed sensor.
According to the second aspect of the present invention, based on the rotational speed of the synchronous machine, the fundamental wave current command (or fundamental wave current), and the fundamental wave voltage command, the armature linkage flux amount of the permanent magnet and the deviation Δθ And the amount of armature linkage flux of the permanent magnet can be calculated with high accuracy.
According to the third aspect of the present invention, the temperature of the permanent magnet is accurately estimated by using the ratio of the calculated armature flux linkage to the armature flux linkage of the reference temperature and the magnet temperature coefficient of the permanent magnet. become able to.
According to the fourth aspect of the present invention, the heat generation of the core having the permanent magnet is considered to be an eddy current loss on the core surface which is one of the generation factors, and the eddy current loss is reduced by increasing the carrier frequency to reduce the magnet temperature. It makes it possible to continue driving.
According to the fifth aspect of the present invention, the cause of the irreversible demagnetization can be easily pursued, and as a result, the user can recognize that fact.
According to the sixth aspect of the present invention, the irreversible demagnetization factor can be recognized in advance by the user, and the drive operation can be continued with the user's intention.

The present invention can be broadly divided into two embodiments.
First, the first embodiment is an invention of an armature flux linkage calculating means and a magnet temperature estimating means different from the prior art for estimating the magnet temperature of a permanent magnet synchronous machine not equipped with a position / speed sensor.
The second embodiment is an invention for risk management of a drive system by displaying in advance an alarm to a user to indicate a processing method required for continuing operation by reducing the magnet temperature after estimating the magnet temperature and a mode in which irreversible demagnetization occurs at that temperature. .

FIG. 1 shows the configuration of the first embodiment.
The subtracter 1 subtracts the estimated speed feedback value ω from the speed command ω _ref . The speed control unit 2 calculates a torque command T _ref from the deviation between the speed command and the speed feedback value.
Current command generating unit 3 is optimized (such as the maximum current efficiency) from the torque command T _ref calculates a current command i? _{_Ref} and i? _{_Ref.}
The subtractor 4a subtracts the γ-axis current Iγ from the γ-axis current command value _{Iγ_ref} , and the subtractor 4b subtracts the δ-axis current Iδ from the δ-axis current command value _{Iδ_ref} . The γ / δ-axis current control unit 5 is configured to match the command and the feedback value based on a deviation between the current commands _{Iγ_ref} and _{Iδ_ref} and their feedback currents Iγ and Iδ in the γ / δ-axis coordinate system. The δ-axis voltage command values _{Vγ_ref} and _{Vδ_ref} are calculated.
gamma - [delta] / 3-phase converter 6 magnets estimated position θ estimate gamma-[delta] -axis voltage value based on (calculated from the observer position and speed estimation calculating unit 11 to be described later) Vγ_ _ref, 3-phase voltage commands the V8 _{_ref Converted to} values V _{u_ref} , V _{v_ref} , V _{w_ref} .
Power converter 7 3-phase voltage command value _V u_ref, V _{v_ref,} converts V _{W_ref} and the converter section of the DC voltage (not shown) to an AC voltage from the carrier signal wave is a short form pulse groups, 3 to synchronous machine 8 Phase alternating voltages V _u , V _v and V _w are applied.
The synchronous machine 8 is a permanent magnet three-phase synchronous machine. This synchronous machine has no hardware for detecting the position and speed.

The advantage of the first invention resides in that the permanent magnet temperature is estimated in such a configuration.
The current detector 9 detects the U-phase and V-phase currents Iu and Iv of the synchronous machine 8 using the current sensors 9a and 9b.
The three-phase / γ · δ converter 10 converts the three-phase AC instantaneous value currents I _u and I _v to γ · δ based on the estimated magnet position θ estimated value (calculated from the observer position / velocity estimation calculator 11 described later). Conversion into shaft feedback currents Iγ and Iδ.
The observer phase / speed estimation calculation unit 11 is a part that substitutes software for speed / position calculation based on sensor signals originally provided in the synchronous machine 8.
Examples of the position / velocity estimation method include a high-frequency applied impedance search method and an observer method. Here, an example of position / speed estimation processing by an observer is shown as an estimation example. Input gamma · [delta] -axis voltage value V.gamma _{_ref,} using feedback current Iγ and Iδ of V8 _{_ref,} and gamma · [delta]-axis coordinate system, the output calculates the estimated velocity and the estimated position of the synchronous machine 8. As described above, this part is intended to estimate the speed and position of the synchronous machine 8, and is not limited to the observer method.
The magnet temperature estimator 12 estimates the permanent magnet temperature MR _X ° _C constituting the rotor of the synchronous machine 8.

そして、（２）式に示すｄ・ｑ軸電圧電流座標系のＶ_dとＶ_qを磁石温度Ｘ°Ｃの電機子鎖交磁束量Φ_X°_Cを用いて演算する。

さらに、（３）式に示すγ・δ軸座標系へ逆電圧マッピングを行い、Ｖγ_{_map}、Ｖδ_{_map}を演算する。

このＶγ_{_map}、Ｖδ_{_map}は任意のΔθと磁石温度Ｘ°Ｃの電機子鎖交磁束量Φ_X°_Cでの結果であり、（４）式に示す条件を満たすまでΔθと電機子鎖交磁束量Φ_X°_Cを動的に変化させ収束演算させる。

１２ｂは、この収束演算で得られた電機子鎖交磁束量Φ_X°_Cを用いて（５）式の演算を行うことで運転状態での永久磁石温度ＭＲ_X°_Cを推定する部分である。
ただし、基準温度の電機子鎖交磁束量は、２０°Ｃのそれとしている。また、永久磁石の磁石温度係数を−０．１１（％／°Ｃ）としている。

FIG. 2 is a diagram showing a detailed configuration of the magnet temperature estimation unit 12.
In the figure, reference numeral 12a denotes a part for calculating the armature interlinkage magnetic flux amount Φx ° _C in the hot operation state and the deviation angle Δθ between the control axis (γ · δ axis) and the magnet axis (d · q axis).
FIG 1 gamma · [delta] -axis voltage value _{Vγ _ref, Vδ _ref, γ ·} δ -axis feedback current Iγ and i?, Further speed command ω _ref, d · q-axis inductance of the synchronous machine 8, to enter the resistance value.
According to equation (1), feedback currents Iδ and Iγ are current-mapped to the dq axis coordinate system at an arbitrary Δθ, and I _d and I _q are calculated. (Generally, the γ-δ axis coordinate system is controlled by a phase more advanced than the dq axis coordinate system, so the direction shown in FIG. 3 is considered as the positive direction.)

Then, V _d and V _q in the d · q axis voltage / current coordinate system shown in the equation (2) are calculated using the armature interlinkage magnetic flux amount Φ _X ° _C at the magnet temperature X ° C.

Further, (3) performs inverse voltage mapping to gamma · [delta]-axis coordinate system shown in the expression, V.gamma _{_MAP,} calculates the V8 _{_MAP.}

These _{Vγ_map} and Vδ_map are _results for an arbitrary Δθ and an armature linkage magnetic flux amount Φ _X ° _C at a magnet temperature X ° C, and Δθ and the armature linkage flux until the condition shown in the equation (4) is satisfied. The amount Φ _X ° _C is dynamically changed to perform convergence calculation.

12b is a part for estimating the permanent magnet temperature MR _X ° _C in the operating state by performing the calculation of the formula (5) using the armature flux linkage Φ _X ° _C obtained by the convergence calculation. .
However, the armature flux linkage at the reference temperature is 20 ° C. The permanent magnet has a magnet temperature coefficient of −0.11 (% / ° C.).

  As described above, according to the first embodiment, it is possible to estimate the magnet temperature using the position / speed detection device for the synchronous machine in the conventional technology for estimating the magnet temperature even when the device is omitted. In addition, it is possible to omit the addressing of the armature linkage magnetic flux amount and magnet temperature from the memory table of the microcomputer, and even in different synchronous machines, it is possible to estimate the magnet temperature from the armature linkage magnetic flux amount from information on only the magnet material. Thus, a more versatile magnet temperature estimation technology was established.

ここで、α：比例定数（コアの電気伝導率など）
Ｂ：高周波電流によるギャップ磁束密度（Ｔ）
ｆ：キャリア周波数（Ｈｚ）
キャリア周波数を２倍にした場合、渦電流損失Ｗ_eddyは概算３０（％）低減できるので磁石温度は１０５°Ｃ（周囲温度２０°Ｃ）となる。この場合、不可逆減磁電流を検索すると、値は４００％となる。３相短絡電流（３５０％）では不可逆減磁しなくなり、１相短絡電流（５００％）では不可逆減磁することになるが、故障確率は３相短絡電流から１相短絡電流へと移行し低くなった。このように、不可逆減磁判定部１３ａは電力変換装置７にキャリア可変周波数、あるいはＰＷＭ変調信号を送り磁石温度を低減させる処理を自動的に行い不可逆減磁のリスクを低くすることが可能である。 FIG. 4 shows the configuration of the second embodiment.
In the figure, the magnet temperature estimator 12 includes an armature flux linkage calculator 12a and a magnet temperature estimator 12b. The irreversible demagnetizer determiner 13 includes an automatic magnet temperature reduction calculator and a demagnetizer determiner. 13a and an alarm output unit 13b.
Since the basic configuration is the same as that in FIG. 1, repeated description will be omitted, and only different parts will be described below.
The irreversible demagnetization determination unit 13 automatically causes the magnet to be demagnetized by the demagnetization determination calculation unit 13a when there is a risk of irreversible demagnetization due to the correlation between the magnet temperature MR _X ° _C calculated by the magnet temperature estimation unit 12 and the current. Processing for reducing the temperature is performed, and alarm processing for notifying the user in which failure mode there is a possibility of occurrence of irreversible demagnetization is performed in advance by the alarm output unit 13b. (See Figure 5.)
First, the process of reducing the magnet temperature of the magnet temperature automatic reduction calculation and demagnetization determination calculation unit 13a will be described.
The AC voltage generated by the power conversion device 7 of FIG. 4 has a PWM (Pulse Width Modulation) waveform, and the current flowing through the synchronous machine 8 is a high frequency (carrier frequency) due to the relationship between the inductance of the synchronous machine 8 and the PWM waveform. Becomes a current superimposed on the rotation frequency. Due to this high frequency current, eddy current flows on the core surface, the core generates heat, and the permanent magnet temperature rises due to heat conduction, so it is necessary to reduce eddy current loss.
For example, when the magnet temperature estimated from the magnet temperature estimation unit 12 is 140 ° C. (ambient temperature 20 ° C.) and an irreversible demagnetizing current is searched at that temperature, the value is 290%. As a result, irreversible demagnetization is not caused by overcurrent (200%), but irreversible demagnetization is caused by three-phase short-circuit current (350%). Since the current cannot be changed, in order to reduce the risk of irreversible demagnetization, it is necessary to increase the carrier frequency f from equation (6) to suppress the amplitude value B (the amplitude value of the high-frequency magnetic flux density) of the high-frequency current and reduce the magnet temperature. is there.

Where α: proportionality constant (core electrical conductivity, etc.)
B: Gap magnetic flux density (T) by high frequency current
f: Carrier frequency (Hz)
When the carrier frequency is doubled, the eddy current loss W _eddy can be reduced by approximately 30%, so the magnet temperature becomes 105 ° C. (ambient temperature 20 ° C.). In this case, when the irreversible demagnetizing current is searched, the value is 400%. The three-phase short-circuit current (350%) will not cause irreversible demagnetization, but the one-phase short-circuit current (500%) will cause irreversible demagnetization. became. As described above, the irreversible demagnetization determination unit 13a can automatically reduce the temperature of the irreversible demagnetization by automatically transmitting the carrier variable frequency or the PWM modulation signal to the power converter 7 and reducing the magnet temperature. .

Next, 13b in FIG. 5 will be described.
This part alarms the user about the irreversible demagnetization occurrence mode. The irreversible demagnetization generation current value for each 10 ° C. magnet temperature from 0 ° C. to 200 ° C. is stored in the memory (Table 1). The irreversible demagnetization current value of this memory and the current generated when the inverter fails (Table 2) ) Is compared and the appropriate alarm is output.
The upper and lower limit values are temporarily set to 0 ° C. and 200 ° C., and are not limited to these values. If the magnet temperature obtained from the magnet temperature estimator 12 is 142 ° C, the irreversible demagnetization current I of irreversible demagnetization of 142 ° C from the irreversible demagnetization current values of 140 ° C and 150 ° C of the magnet temperature in the memory table. Interpolate the current. The I irreversible current and the power conversion (IGBT) overcurrent value I overcurrent or three phase short-circuit current I _3-phase short-circuit current at IGBT failure, for protection, comparing the one-phase short-circuit current value I ₁ phase short-circuit current .
If the relation of I overcurrent> I irreversible demagnetizing current is satisfied, an alarm [OC] is output.
If the relationship of I _3- phase short-circuit current> I irreversible demagnetizing current ≧ I overcurrent is satisfied, alarm [3SC] is output.
I _1- phase short-circuit current> I irreversible demagnetizing current ≥ If the relationship of I _3- phase short-circuit current is satisfied, alarm [1SC] is output.
If the relationship of I irreversible demagnetizing current ≧ I ₁ phase short circuit current is satisfied, alarm [OK] is output.
As the motor shifts from the cold state to the hot state, the alarm display changes from [OK] → [1SC] → [3SC] → [OC].
As described above, the alarm output unit 13b outputs an irreversible demagnetization generated due to the cause of the failure of the power conversion device 7 according to the failure mode.
There are advantages that the user can easily plan risk management, such as investigating the failure probability of the IGBT and preparing alternatives for the motor and inverter in advance.

1 is a diagram illustrating a configuration of Example 1. FIG. FIG. 3 is a detailed view of a magnet temperature estimation unit of the configuration unit of the first embodiment. It is a figure which shows the view of a coordinate system. 6 is a diagram illustrating a configuration of Example 2. FIG. FIG. 10 is a detailed view of an irreversible demagnetization determination unit of the configuration unit of Example 2.

Explanation of symbols

1 4a, 4b Subtractor 2 Speed control unit 3 Current command generation unit 5 γ / δ axis current control unit 6 γ · δ / 3 phase conversion unit 7 Power converter 8 Synchronous machine 9 Current detection unit 10 3 phase / γ · δ Conversion unit 11 Observer position / speed estimation calculation unit 12 Magnet temperature estimation unit 12a Armature interlinkage flux amount calculation unit 12b Magnet temperature estimation calculation unit 13 Irreversible demagnetization determination unit 13a Magnet temperature automatic reduction calculation and demagnetization determination calculation unit 13b Alarm Output section

Claims (6)

A power converter that drives by applying an AC voltage to a synchronous machine using a permanent magnet as a rotor;
In a Cartesian coordinate system (γ-δ axis coordinate) that is synchronized with the fundamental wave component of the current flowing through the synchronous machine but rotates with a deviation of Δθ from the magnet axis (dq axis), the fundamental wave of the synchronous machine Current control means for calculating a fundamental voltage command for matching the current to the command value;
Speed control means for calculating a torque command in order to match the rotation speed of the synchronous machine with a rotation speed command value;
An AC voltage control means for calculating an AC voltage applied to the synchronous machine based on a fundamental voltage command value calculated from the current control means;
Estimating control means for estimating the rotational speed or rotational position of the synchronous machine by an observer such as an impedance or voltage-current equation inverse model of the synchronous machine;
Based on the rotation speed of the synchronous machine estimated from the estimation control unit, the fundamental wave current command or fundamental wave current, and the fundamental wave voltage command, the armature interlinkage flux amount of the permanent magnet is converged. Magnetic flux calculation means;
Magnet temperature estimation means for estimating the temperature of the permanent magnet based on the armature linkage magnetic flux of the permanent magnet calculated by the magnetic flux calculation means, and irreversible demagnetization for determining the irreversible demagnetization of the permanent magnet from the magnet temperature. A control device for a synchronous machine, comprising a determination means.   The magnetic flux calculation means is based on the rotation speed of the synchronous machine estimated from the estimation control means, the fundamental wave current command or fundamental wave current, and the fundamental wave voltage command, and the armature linkage of the permanent magnet. 2. The control apparatus for a synchronous machine according to claim 1, wherein the amount of magnetic flux and the deviation [Delta] [theta] are dynamically changed, and the amount of armature linkage magnetic flux of the permanent magnet is converged.   The magnet temperature estimation means estimates the temperature of the permanent magnet using the ratio of the calculated armature flux linkage to the reference temperature armature flux linkage and the magnet temperature coefficient of the permanent magnet. 2. The synchronous machine control apparatus according to claim 1, wherein the control apparatus is a synchronous machine.   When the irreversible demagnetization generation current at the estimated permanent magnet temperature exceeds the allowable current, the irreversible demagnetization determining means increases the carrier frequency inside the power converter or modulates the power converter. 2. The synchronous machine control device according to claim 1, wherein the system is changed from two-phase to three-phase.   A table of irreversible demagnetization generation current with respect to the permanent magnet temperature is provided, the irreversible demagnetization generation current value with respect to the estimated temperature of the permanent magnet is searched, an overcurrent value for power conversion protection, and a three-phase short circuit at the time of IGBT failure 5. The synchronous machine control device according to claim 4, wherein at least one of a current and a one-phase short-circuit current value is compared with the irreversible demagnetization generation current value. 6.   As a result of the comparison, when the overcurrent value, the three-phase short-circuit current value, and the one-phase short-circuit current value are larger than the searched irreversible demagnetization generation current value, a warning alarm is displayed. The control device for a synchronous machine according to claim 5.

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