JP2001136775A - Estimation method for load of permanent magnet rotor- type synchronous motor and control device for the permanent magnet rotor-type synchronous motor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method and apparatus in which the estimation of a load is realized, without being influenced by changes in the resistance value due to the change in the temperature of a synchronous motor. SOLUTION: When a load is estimated, a load estimating device 14 gives a speed command ωrm** to a speed controller 1. A γ-axis induced-voltage estimation value εγest which is obtained from a γ-δ axis current and induced-voltage estimation device 8 is input. A plurality of kinds of γ-axis current commands iγ*1, iγ*2 for load estimation are given to a γ-axis current controller 3. A load- estimation correction amount Δεγest is found. The load-estimation correction amount Δεγest is corrected. A correction load amount is estimated. An optimum γ-axis current command iγ*, which corresponds to the load amount, is calculated to be given to the γ-axis current controller 3. In operation, a speed command ωrm* is first set at 0. Then, γ-axis induced-voltage estimation values εγest1, εγest with reference to the two kinds of γ-axis current commands iγ*1, iγ*2 are plotted on a straight line. The inclination of the straight line is proportional to a resistance change ΔRS generated caused by heating with a γ-axis current.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a sensorless vector control method for a permanent magnet rotor type synchronous motor, and more particularly to a load estimation method for a permanent magnet rotor type synchronous motor.

[0002]

2. Description of the Related Art As a conventional sensorless vector control method for a synchronous motor, there is a method described in Japanese Patent Application Laid-Open No. H11-018499. Hereinafter, this method is referred to as prior art. In this method, the U-phase of the stator of the synchronous motor is set to the α-axis, the β-axis is set in the positive rotation direction of the electrical angle of 90 degrees from the α-axis, and the U, V, and W-phase currents are set in the α-β fixed rectangular coordinate system To two-phase conversion. Next, a dq orthogonal coordinate system that rotates at a rotation speed ω _rm of the rotor with the magnetic axis of the permanent magnet rotor type synchronous motor as the d axis and the axis advanced by 90 electrical degrees from the d axis as the q axis is described. Define. Then, the α-phase current and the β-phase current (or the α-axis current and the β-axis current) are converted into a dq coordinate system.
At this time, the d-axis points in the direction of the magnetic axis (true magnetic axis) of the permanent magnet rotor type synchronous motor as described above, and the q-axis
The direction of the rotating magnetic flux produced by the stator, and therefore the direction of the current producing the rotating magnetic flux (the direction of the stator current vector).

Next, a γ-δ coordinate axis is defined as a control axis of the permanent magnet rotor type synchronous motor. When performing control to rotate the permanent magnet rotor type synchronous motor at a desired angular speed and at a desired phase, the host device transmits the angular velocity of the rotor magnetic shaft and the control to the synchronous motor control device (inverter device). A command for directly or indirectly specifying the desired value of the phase is given. At this time, a two-dimensional rectangular coordinate system for control for controlling the rotation of the rotor (here, “orthogonal” means orthogonal in the sense of an electrical angle) is assumed, and this coordinate axis is defined as γ.
Axis and δ axis. The γ-δ coordinate system is a coordinate system that rotates with the rotor, and the δ axis is γ-δ when the stator current to be realized by the command is converted from the α-β coordinate system to the γ-δ coordinate system. The direction of the stator current vector in the coordinate system is set, and the γ axis is set at an angular position delayed by 90 degrees in electrical angle with respect to the δ axis. Therefore, the γ-axis becomes the direction of the magnetic axis of the rotor when the stator current flows in the δ-axis direction by the current command or the voltage command. The magnetic axis facing the γ-axis direction is called a designated magnetic axis or a control magnetic axis.

Since the current and voltage in the dq coordinate system represent the actual current and voltage of the stator in a rotating coordinate system, the direction of the current vector and the magnetic axis of the rotor in the dq coordinate system. The direction can be considered to represent the direction of the actual current vector or the direction of the magnetic axis. On the other hand, the current and voltage in the γ-δ coordinate system represent the current and voltage of the stator specified by the command in the rotating coordinate system. The direction can be considered to represent the direction of the current vector or the direction of the magnetic axis specified by the command, that is, the target of the direction of the current vector or the direction of the magnetic axis. Therefore, when the dq coordinate axis is displaced from the γ-δ coordinate axis, it is an object of the control of the permanent magnet rotor type synchronous motor to retract the dq coordinate axis so as to coincide with the γ-δ coordinate axis.

As is well known, when the phase of the true magnetic axis d-axis lags behind the γ-axis by the load angle θ _e , when a positive DC current iγ flows on the γ-axis, iγ sin θ _e
, A torque is generated in the γ-axis direction proportional to. Therefore, when the load torque is 0, the true magnetic axis always receives a torque directed toward the designated magnetic axis γ-axis. Normally, in a synchronous machine having no braking winding, the damping constant is almost 0, so that when the load torque is 0, the true magnetic axis becomes the designated magnetic axis γ.
Upon receiving a torque directed toward the axis, the d-axis generates a simple oscillation around the γ-axis.

In order to solve this problem, in the prior art, a deviation angle θ _e of the d-axis with respect to the γ-axis is estimated from a speed estimation value ω _rmest and a γ-axis induced voltage estimation value εγ _est , and a deviation angle θ _e based on, so as to reduce the deviation angle theta _e, corrects the δ-axis current and γ-axis current. This correction is performed by correcting the δ-axis current command and the γ-axis current command using the δ-axis current correction signal and the γ-axis current correction signal, respectively. Thus, the transient vibration of the d-axis is suppressed.

In order to reduce the deviation between the true magnetic axis and the designated magnetic axis due to the load torque, a corrected current command is generated by proportionally integrating the estimated value of the γ-axis induced voltage εγ _est. Add to the δ-axis current command. As a result, the correction current flows until εγ is 0, that is, the γ-axis and the d-axis coincide with each other, whereby the γ-axis coincides with the magnetic axis d-axis. Since the γ-axis rotates at the command speed, the true magnetic axis d-axis also rotates at the command speed.

In this way, the load angle generated between the true magnetic axis d axis and the γ axis due to the load is suppressed, and as a result, the true magnetic axis d rotates on the γ axis rotating at the command speed ω _rm ^*. Constrain the axis,
The sensorless speed control can be satisfactorily performed even in a low speed range.

In this prior art, the estimated value of the γ-axis current, the estimated value of the δ-axis induced voltage, the estimated value of the γ-axis induced voltage, and the estimated value of the δ-axis induced voltage are calculated based on the u-phase current, the v-phase current, and the w-phase current. Γ-axis current and δ-axis current obtained by γ-δ conversion of any two of them, γ-axis voltage command and δ-axis voltage command as variables, and γ-axis induced voltage and δ-axis induced voltage set as disturbance The γ-axis voltage / current equation and the δ-axis voltage / current equation are estimated.

[0010]

In the above prior art, there is no means for detecting the load when the true magnetic axis d-axis is constrained to the γ-axis rotating at the commanded speed ω _rm ^*. Regardless of the control, the control always considered the maximum load. Furthermore, since there was no means for detecting the load, γ
The current value of the current command iγ ^* flowing in the axial direction was designed to be a fixed value in consideration of the maximum load. As a result, there is a problem that the efficiency is poor when the load is small, and a load is applied to the power element of the inverter circuit when the continuous operation is performed in a low speed range. When trying to further estimate the load, the γ-axis voltage / current equation and δ-axis voltage /
There has been a problem that the resistance value used in the current equation fluctuates and the accuracy of load estimation deteriorates.

Accordingly, a first object of the present invention is to provide a method and a device for estimating the magnitude of a load connected to a synchronous motor driven by an inverter device without a sensor.

A second object of the present invention is to provide a method and an apparatus for realizing a load estimation which is not affected by a change in resistance due to a change in motor temperature.

A third object of the present invention is to optimally adjust the command value of the current command iγ ^* to be given in the γ-axis direction according to the magnitude of the estimated load, thereby increasing the operating efficiency and continuously operating in the low speed range. It is an object of the present invention to provide a method and an apparatus for reducing a load applied to a power element of an inverter circuit during operation.

[0014]

In order to achieve the first object, a method of estimating the load of a permanent magnet rotor type synchronous motor according to the present invention comprises: And δ-axis voltage / current equation,
The independent variable describing the non-disturbance γ-axis voltage / current equation and the non-disturbance δ-axis voltage / current equation and the dependent variable determined depending on the independent variable are used to determine the γ-axis voltage / current when there is an induced voltage. Equations and δ-axis voltage / current equations, that is, voltage / current state equations including a disturbance system γ-axis voltage / current equation and a disturbance system δ-axis voltage / current equation, and set the voltage / current state equation in a steady state Then, according to the voltage / current state equation in the steady state,
Estimate the induced voltage value for the specified independent variable value and calculate γ
The load angle is estimated from the induced voltage estimation value using the load angle dependence of the induced voltage, in which the shaft induced voltage and the δ-axis induced voltage depend trigonometrically on the load angle.

The independent and dependent variables of the voltage / current state equation are given to the control device as independent and dependent commands. The independent command is a command whose value can be arbitrarily set by the host device (in the block diagram of FIG. 1, the command is the angular velocity command and the γ-axis current command). The dependent variable is a command determined depending on the independent command (in the block diagram of FIG. 1, a δ-axis current command, a δ-axis voltage command, and a γ-axis voltage command).

In order to achieve the second object, a method for estimating the load of a permanent magnet rotor type synchronous motor according to the present invention comprises an independent command specified according to a disturbance-system γ-axis voltage / current equation in a steady state. Estimating a γ-axis induced voltage value corresponding to the value, setting the γ-axis induced voltage estimated value as a first γ-axis induced voltage estimated value, and when the resistance R of the synchronous motor changes to R + ΔR, For the same independent command value as the value, the value of the γ-axis induced voltage obtained according to the disturbance system γ-axis voltage-current equation in the steady state is used as the second γ-axis induced voltage estimated value, and the second γ-axis induced voltage The γ-axis induced voltage estimated value difference obtained by subtracting the first γ-axis induced voltage estimated value from the estimated value is determined by the Joule heat generated by the current flowing through the synchronous motor corresponding to the specified independent command value. Γ-axis induced electricity due to resistance change It is determined that the estimated value change, gamma
Corrects the axis induced voltage estimated value, estimates the load angle theta _e from the corrected γ-axis induced voltage estimated value.

In this case, the independent command is given by γ-axis current and δ-axis current.
An independent command is applied so that a predetermined value of the γ-axis current and a predetermined value of the δ-axis current flow in a stepwise manner with respect to time. The estimated value of the γ-axis induced voltage immediately after the current rises in a step function and enters the electric steady state is the first estimated value of the γ-axis induced voltage, and the synchronous motor is brought into a thermal equilibrium state while maintaining the same independent command. The estimated value of the γ-axis induced voltage at the time of reaching is referred to as a second estimated value of the γ-axis induced voltage. In order to achieve the third object, in the load estimating method for a permanent magnet rotor type synchronous motor according to the present invention, a γ-axis current command iγ ^* determined as an independent command or a dependent command assuming a full load is provided ^. Is multiplied by a coefficient K having a load angle characteristic that is equal to 1 when the load angle θ _e is 90 ° and decreases monotonically as the load angle θ _e decreases, and Kiγ ^* that changes according to the load angle θ _e ^. Is given to the γ-axis as a γ-axis current command.

The control device for a permanent magnet type synchronous motor according to the present invention has a load estimator. The load estimator outputs an angular velocity command for load estimation and a γ-axis current command for load estimation during the load estimation operation, and the γ-axis induction generated in response to the output angular velocity command and γ-axis current command. Enter the voltage estimate and
Calculate the change in the estimated value of the γ-axis induced voltage caused by the change in the resistance of the synchronous motor caused by the Joule heat of the current flowing through the synchronous motor in response to the angular velocity command and the γ-axis current command, and The load angle estimation value is corrected from the change.

At this time, the load estimator sets the angular velocity command and the γ-axis current command for the load estimation to 0 at the initial stage of the load estimation, and then sets the angular velocity command and the γ-axis current command of predetermined values, respectively, in time. A step function is applied to the speed controller and the γ-axis current controller, and the γ-axis induced voltage estimated value immediately after the δ-axis current and the γ-axis current rise in a step function to be in the electric steady state is obtained by the first γ-axis. As the induced voltage estimated value, the γ-axis induced voltage estimated value when the synchronous motor reaches the thermal equilibrium state while maintaining the angular velocity command and the γ-axis current command at the same value, as the second γ-axis induced voltage estimated value, The γ-axis induced voltage estimated value difference obtained by subtracting the first γ-axis induced voltage estimated value from the γ-axis induced voltage estimated value of No. 2 flows through the synchronous motor in accordance with the angular velocity command and the γ-axis current command. Is determined as a change in the estimated value of the γ-axis induced voltage due to the resistance change due to the Joule heat generated by the generated current, and the estimated value of the γ-axis induced voltage is corrected using the change in the estimated value of the γ-axis induced voltage. The load angle θ _e is estimated from the estimated value of the γ-axis induced voltage.

[0020]

According to the present invention, the estimated γ-axis current values iγ _est , δ
Axis current estimated value iδ _est , γ-axis induced voltage estimated value εγ _est , δ
The estimated value of the shaft induced voltage εδ _est is represented by the u-phase current, the v-phase current, w
Γ obtained by performing γ-δ conversion on any two phases of the phase current
Axis current iγ and δ-axis current iδ, and γ-axis voltage command Vγ ^*
And the δ-axis voltage command Vδ ^* are input, and the γ-axis induced voltage ε
It is estimated by the γ-axis current equation and the δ-axis current equation set with the γ and δ-axis induced voltages εδ as disturbances.

Equation (1) indicates that when there is no disturbance (when there is no rotor), the three-phase current of the stator (or α-β phase current)
Is a current equation obtained by dq conversion.

[0022]

(Equation 1)

In equation (1), i _d and _iq are d
Axis current and q-axis current (projection of stator current onto d-axis and q-axis), and v _d and v _q are d-axis voltage and q axis, respectively.
Axial voltage (projection of stator voltage on dq axes).

The coefficient matrix of the first term on the right side of the equation (1) corresponds to a known impedance matrix. (However, d
The first row corresponding to the axis is divided by the d-axis inductance L _d , and the second row corresponding to the q-axis is the q-axis inductance L _q
Divided by ) The diagonal elements of this matrix are
This corresponds to a voltage drop due to the circuit resistance R _S. In the off-diagonal element, the d-axis and the q-axis rotate with respect to the stator u-axis, the v-axis, and the w-axis, so that the projections of the u-, v-, and w-phase magnetic fluxes on the d-axis and the q-axis change. Corresponding to the generated electromotive force. The second term on the right side of equation (1) corresponds to the voltage applied to the d-axis and the q-axis.

Although the dq conversion of the equation (1) is a current / voltage coordinate conversion, it is very convenient to apply this to a permanent magnet rotor type synchronous motor. In this case, if ω _rm is the rotational angular velocity of the rotor, the dq coordinate axes rotate at the same angular velocity as the rotor. That is, the dq coordinate axes are coordinate axes fixed to the rotor. More conveniently, the relationship between the direction of the magnetic axis of the rotor (true magnetic axis) and the direction of the rotating magnetic flux generated by the three-phase current of the stator (therefore, the direction of the current generating the rotating magnetic flux) (magnetic direction). The direction of the shaft is delayed by 90 degrees in the rotational direction with respect to the direction of the magnetic flux generated by the stator current) is d
-The same as the relationship between the direction of the d-axis and the direction of the q-axis in the q coordinate system.

However, when the dq conversion is applied to a permanent magnet rotor type synchronous motor, a speed electromotive force (hereinafter referred to as an induced voltage) induced by the magnetic flux φ _{mag of} the rotor intersects the stator coil. ) Is also subjected to dq conversion and enters equation (1) as an additional term. In the present invention, this additional term is treated as a disturbance. "Treated as a disturbance"
Means that based on the solution of the differential equation of the current when the rotor is not present, the solution of the differential equation when the rotor is present is constructed. The solution of the differential equation of the current when the rotor is not present is an equation obtained by substituting γ and δ for the current suffixes p and q in equation (1).

[0027]

(Equation 2)

In the present invention, the induced voltage is taken into the control model as a disturbance as the following equation.

[0029]

(Equation 3)

In equations (3) and (4), the suffix “est” represents an estimated value. Since the current value and the induced voltage value obtained from these equations are referred to as “estimated values” in the following description, the values of the equations (3) and (4) are indicated with est. In contrast, there are a γ-axis current iγ and a δ-axis current iδ without the symbol “est” on the fourth term on the right side of equation (3) and on the right side of equation (4). These are “detected” γ-axis currents and δ-axis currents obtained by γ-δ conversion of the detected values of the α-phase current and the β-phase current.

In the present invention, in order to treat the induced voltage as a disturbance, the induced voltage is calculated by calculating the γ-axis current iγ _est and the δ-axis current iδ _est (the solution of the equation (2)) when there is no disturbance. Expressed by a linear bond. Now, the time is represented by a discrete time in units of a sampling time T _S , and the current time is set to k + 1. And
Γ-axis induced voltage estimated value at the discrete time k immediately before εγ _{es t}
When (k) is represented by a linear combination of the estimated value of the γ-axis current and the estimated value of the δ-axis current, the following expression is obtained. _{εγ est (k) = k 5} iγ est (k) + k 6 iδ est (k). . . . . (5) (iγ _est (k) and iδ _est (k) correspond to the detected γ-axis current value iγ and the detected δ-axis current value iδ “detected” at the discrete time k−1). k + 1 (current)
Expressed in a linear combination of the γ-axis induced voltage estimated value εγ _est (k + 1) of the γ-axis current estimated value and the δ-axis current estimated value in, the following equation. εγ _est (k + 1) = k ₅ i γ _est (k + 1) + k ₆ iδ _est (k + 1). . . . . . . . . . (6) However, at the current discrete time k + 1, iγ _est
Since (k + 1) and iδ _est (k + 1) are not calculated, the γ-axis current detection value iγ detected at the discrete time k
(K) and the detected δ-axis current value iδ (k), iγ _est
(K + 1) and iδ _est (k + 1) are approximated. (Iγ _est
(K + 1) and iδ _est (k + 1) are iγ
(K) and estimated values corresponding to iδ (k). ) In this way, the following equation is obtained. εγ _est (k + 1) = k ₅ iγ (k) + k ₆ iδ (k). . . . (7) By subtracting equation (5) from equation (7), the following equation is obtained as the rate of change of the estimated value of the γ-axis induced voltage per unit sampling time. Δεγ _est (k + 1) = k ₅ (iγ (k) −iγ _est (k)) + k ₆ (iδ (k) −iδ _est (k)... (8) Is the same equation as the first row of Equation (4). Therefore, Equation (4) shows that the γ-axis induced voltage is
In a linear combination with the shaft current estimate (ie, as a disturbance)
Indicates that it is being processed. The same applies to the δ-axis induced voltage.

The third term on the right side of the equation (3) is used to correct the angular deviation between the true magnetic axis and the designated magnetic axis as shown in the equation (4), as described later. , Γ-axis current and δ-axis current are changed, the terms describing the effects of the changes in the respective axis currents on the voltage / current state equations of the synchronous motor.

Equation (4) is equivalent to the γ-axis induced voltage estimated value εγ _est
And the estimated δ-axis induced voltage εδ _est is the estimated γ-axis current i
It shows that the change is in proportion to the change in γ _est and the estimated δ-axis current value iδ _est . This represents the following phenomenon. As is well known, when a positive current is applied to the γ-axis when there is an angle deviation θ _e between the true magnetic axis (d-axis) of the rotor and the designated magnetic axis (γ-axis), the d-axis becomes the γ-axis. Receives torque in the direction of. As a result, the angle shift changes, thereby changing the estimated γ-axis induced voltage εγ _est and the estimated δ-axis induced voltage εδ _est . Also, result in a change in the angular velocity of the true magnetic axis by a change in [delta]-axis current estimated value i? _Est, whereby the angle deviation is changed, as a result, gamma-axis induced voltage estimated value εγ _est, δ
The estimated value of the shaft induced voltage εδ _est changes.

In order to incorporate the equations (3) and (4) into the inverter device, the state equations (3) and (4) in the γ-δ axis coordinate system of the synchronous motor are developed into the following discrete value system. You.

[0035]

(Equation 4)

[0036]

(Equation 5)

Here, θ _est is the estimated value of the angular position of the true magnetic axis.

[0038]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention estimates the load of a synchronous motor according to the above-mentioned equations (9) to (12). However, in the present embodiment, k in the third term on the right side of Expression (9)
₅ = k, k ₆ = 0, and k ₇ = 0. As described above, when present in delayed phase load angle theta _e from axis true magnetic axis d-axis gamma, the positive direction of the DC current iγ flows gamma shaft, torque is generated toward the gamma axially , The magnitude of which is proportional to iγ sin θ _e . As a result, when the load torque is 0, the true magnetic axis always receives a torque directed toward the designated magnetic axis γ axis, but if the load torque is not 0, the magnetic axis becomes
The motor rotates with the load angle corresponding to the load torque and the DC current iγ open.

When the load torque is not 0 and the magnetic axis is rotating at the load angle θ steadily, from the equation (9),
The following γ-axis current equation is obtained.

[0040]

(Equation 6)

In the steady state, iγ _est (k + 1)
= I γ _est (k) and i γ (k) = i γ _est (k), so the following equation holds.

[0042]

(Equation 7)

In the equation (14), a voltage command is used as vγ, and a speed command is set so that ω _rmest becomes a predetermined value (as described later, in this embodiment, the δ-axis current command is a speed command. Is a subordinate directive determined by subordinate)
If, gamma-axis induced voltage estimated value εγ _{es t} is, gamma-axis current estimated value i
It is expressed as a linear function of γ _est . εγ _est = ε · sin
Given θ _e , the following equation is obtained.

[0044]

(Equation 8)

As is apparent from the equation (15), the load angle θ
_e can be estimated from the estimated γ-axis current value iγ _est , the γ-axis voltage command vγ, the estimated δ-axis current value _{iδ est} , and the estimated angular velocity ω _rmest . Equation (15) can be solved by simultaneously solving the following equations (16a) and (16b), as shown in FIG. y = ε sin θ _e . . . . . . . . . . . . . . . . (16a) y = aiγ _est -b. . . . . . . . . . . . . . . (16b) where a = εA, b = εBvγ + εCω _{rmest iδ est} . . . . (16c).

When equation (14) is solved for the estimated γ-axis current value iγ _est , the following equation is obtained.

[0047]

(Equation 9)

The estimated γ-axis current value iγ _est is obtained when the load angle θ _e is 0.
It increases sinusoidally from D to E + D as it changes from ° to 90 °. This means the following. Since the estimated γ-axis current value iγ _est that balances with the load angle θ _e is given by Expression (17), the γ-axis current command iγ ^* given to the γ-axis to draw the true magnetic axis to the γ-axis is:
It suffices if the size satisfies Expression (17).

Therefore, for example, sin θ_e≒ θ_eIs formed
When the load angle is small enough to stand up, the γ-axis current command i
γ^*May be about D. θ_e= 30 °, the γ-axis
Flow command iγ^*May be about 0.5E + D. However, θ_e
= 90 °, the γ-axis current command iγ^*Is about E + D
I have to take into account the degree. Therefore, the γ-axis induced
Pressure estimation value εγ_estLoad angle estimated from_e(Equation (1
7)), a coefficient K is calculated as shown in FIG.
Γ-axis current command iγ for restraining the d-axis to the γ-axis ^*To
Kiγ^*Switch to

The coefficient K is given by the equation (Esinθ _e + D) / (E + D) obtained by dividing the right side of the equation (17) by the normalization constant E + D. . . . . . . . . . . . . It has the same characteristics as (18a), and when θ _e = 90 °, K = 1 and monotonically decreases as θ _e decreases. In practice, the coefficient K is determined empirically with reference to Equations (17) and (18).

As described above, by designing the γ-axis current command corresponding to the load angle with reference to the equation (17),
It is possible to prevent adverse effects caused by always giving the γ-axis current command in anticipation of the maximum load.

Equation (14) is always satisfied when the synchronous motor _whose rotor is rotating at ω _rmest is in a steady state. Now, consider a case where a synchronous motor rotating in a steady state undergoes a resistance change due to a temperature change. At this time, the same speed command ω _rm ^* and the same γ-axis current command i
against gamma ^* and the same shift angle theta _e, gamma-axis voltage v?, gamma
Axis current estimated value i? _Est, [delta]-axis current estimated value i? _Est, the rotation speed omega _rm is maintained at the same value (see FIG. 1 below). As a result, in order to compensate for the γ-axis voltage drop ΔR _S iγ _est due to the resistance change ΔR _S , the estimated γ-axis induced voltage ε
A change in γ _est Δεγ _est occurs. That is, the following equation is established.

[0053]

(Equation 10)

By subtracting equation (14) from equation (19),
The following equation is obtained.

[0055]

[Equation 11]

This equation is a linear equation of the estimated γ-axis induced voltage deviation, using the estimated γ-axis current value iγ _est as a variable and the resistance error ΔR _s as the slope. The resistance error ΔR _s is given by the equation (2)
0) based on the γ-axis induced voltage estimated value deviation Δεγ _est and γ
It can be determined from the estimated shaft current value iγ _est . Or, gamma axis flushed with different currents, different gamma seek gamma-axis induced voltage estimated value deviation Derutaipushironganma _est respect to the axis current i?, Obtains the [Delta] R _S from the slope. In this manner, the change Δεγ of the estimated value of the γ-axis induced voltage due to the temperature change of the motor is calculated from the slope ΔR _S and the γ-axis current iγ, and the calculated value is used.
Correct an arbitrary load estimation amount (Equations (15) and (16))
reference).

It should be noted here that Δεγ _{est on} the left side of the equation (20) is an “apparent” change in the γ-axis induced voltage. That is, this Δεγ
_est is irrelevant to the change in the deviation angle of the true magnetic axis from the designated magnetic axis, and is also irrelevant to the change in the angular velocity ω _rm . This is apparent from the fact that, when the equation (20) is derived, the calculation is performed on the assumption that “the same speed command ω _rm ^* ” and “the same shift angle θ _e ” are used. In equation (20), ω
The does not include the _rm and iδ _est is due to this reason.

However, the reason why it is necessary to correct the “apparent” change in the γ-axis induced voltage is that the information processing device of the inverter device recognizes this “apparent” change in the γ-axis induced voltage as “true”. This is because the control is performed so as to compensate for this “apparent” change in the γ-axis induced voltage, considering the change in the γ-axis induced voltage (depending on the angular velocity ω _rm and the deviation angle θ _e ). In other words, this “apparent” change in the γ-axis induced voltage contributes to the control of the synchronous motor in the same manner as the “true” change in the γ-axis induced voltage.

In the present embodiment, the deviation Δεγ _{est in} the equation (20) is identified as follows. First, reference values of the resistance R and the estimated value of the γ-axis induced voltage εγ _est are determined.
The purpose of the present invention is to correct the influence of the resistance change due to the Joule heat of the γ-axis current iγ and the δ-axis current iδ on the estimated γ-axis induced voltage εγ _est.
The resistance value when both the axis current iγ and the δ-axis current iδ are 0 is set as a reference value. Then, the estimated value of the γ-axis induced voltage at this time is set as the reference value of the estimated value of the γ-axis induced voltage εγ _est .
In order to set both the γ-axis current iγ and the δ-axis current iδ to 0, the γ-axis current command iγ ^* and the speed command ω _rm ^* are set to 0, respectively.
Set to. Thus, the γ-axis current iγ and the δ-axis current iδ
Are set to 0 in the following description.
This is referred to as “reference state”. In the reference state, the speed command ω
_{Since rm} ^* is set to 0, the angular velocity ω _rm becomes 0 in a steady state. As a result, the γ-axis induced voltage estimated value ε
gamma _{es t} will identically 0 regardless of the size of the deviation angle theta _e. For this reason, the reference value of the estimated value of the γ-axis induced voltage εγ _est is 0.

Next, a step function type γ-axis current command iγ ^* and a speed command ω _rm ^* having desired heights are applied, and when an electrically stable state is reached, a γ-axis induced voltage estimated value εγ _{est is} immediately obtained.
Find the value of Normally, the time constant of the step response when a step function command signal is applied to the inverter device is:
It is much larger than the thermal time constant determined by the heat capacity and thermal conductivity of the synchronous motor. Accordingly, when the step function type γ-axis current command iγ ^* and the speed command ω _rm ^* are applied and the electric stable state is reached, the value of the estimated γ-axis induced voltage estimated value εγ _est immediately It can be considered to correspond to the resistance R _S before being heated by the current iγ and the δ-axis current iδ. Therefore, the relationship between the estimated value of the γ-axis induced voltage εγ _est and the resistance R _{S at} this time corresponds to Expression (14).

The γ-axis current command iγ ^{* of the} step function type
After the application of the speed command ω _rm ^* and the time corresponding to the thermal time constant elapses, the synchronous motor approaches the thermal equilibrium state. The relationship between the estimated value of the γ-axis induced voltage εγ _est and the resistance R _S when the synchronous motor reaches the thermal equilibrium state is given by Equation (19).
Corresponding to Therefore, Δεγ on the left side of equation (20)
_est synchronizes the value of the estimated γ-axis induced voltage εγ _est immediately obtained when the step function type γ-axis current command iγ ^* and the speed command ω _rm ^* are applied to reach an electrically stable state. It is obtained by subtracting from the value of the estimated γ-axis induced voltage εγ _est obtained when the motor has reached the thermal stable state.

[0062] As a special case, there is a case where the resistance change [Delta] R _S caused by Joule heat γ axis current iγ is generated to correct for the effects Derutaipushironganma _est on γ-axis induced voltage estimated value εγ _est. This correction is necessary when a γ-axis current is applied to eliminate the deviation angle between the designated magnetic axis of the synchronous motor and the true magnetic axis. This correction amount Δεγ _est can be obtained by the following processing.

First, the γ-axis current command iγ ^* and the speed command ω _rm ^*
Are set to 0 and the reference state is set. (At this time, since the angular velocity ω _rm becomes 0, εγ _est automatically becomes 0.
become). Next, with the speed command ω _rm ^* set to 0,
A desired γ-axis current command iγ ^* is applied. γ-axis current command i
Even if γ ^* is applied, the angular velocity ω _rm is 0 and γ
Before the heating by the axial current i? To proceed, gamma-axis induced voltage estimated value Ipushironganma _est is independently become identically zero gamma-axis current estimated value i? _Est. Therefore, in this case, there is no need to apply the step function type γ-axis current command iγ ^* and obtain the value of the estimated γ-axis induced voltage εγ _est when the electric stable state is reached. Then, when the synchronous motor reaches the thermal equilibrium state next time, the estimated value of the γ-axis induced voltage ε
When γ _est is obtained, the estimated γ-axis induced voltage value εγ _est corresponds to Δεγ _est in Expression (20).

[0064]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an embodiment of the present invention will be described in more detail.

FIG. 1 is a block diagram showing an embodiment of a control device for a synchronous motor to which a load estimation method and a sensorless control method according to the present invention are applied. FIG. 2 is a flowchart showing the digital control operation of the load estimation method and the sensorless control method.

A block diagram of the control device shown in FIG. 1 will be described. During normal operation, the speed controller 1
Angular velocity command ω _rm ^* and angular velocity estimated value ω _rmest are input, and at the time of load estimation operation, load estimation speed instruction ω _rm ^** and angular velocity estimated value ω _rmest are input, and δ-axis current command iδ ^* is input. Output. The δ-axis current controller 2 outputs the δ-axis current command iδ
^* And δ-axis current command correction value iδθ and δ-axis current correction value iδ _cor
And outputs the δ-axis voltage command Vδ ^* . On the other hand, γ
The shaft current controller 3 inputs the γ-axis current command iγ ^* and the γ-axis current correction value iγ _cor during the normal operation, and the γ-axis current command iγ ^** (i
γ ^** 1, iγ ^** 2) are input, and a γ-axis voltage command Vγ ^* is output. The vector control circuit 4 receives the δ-axis voltage command Vδ ^* , the γ-axis voltage command Vγ ^*, and the γ-δ-axis position information, and inputs a voltage value absolute value (Vγ ² + Vδ ² ) ^1/2 and a voltage command phase tan.
^-1 (Vδ / Vγ). The inverter circuit 5 converts the output of the vector control circuit 4 into u-phase, v-phase, and w-phase, and fires according to the voltage and phase of each of the uvw phases.

[0067] phase converter 7 receives the detected value i _su and i _sv the stator current i _u and i _v of the synchronous motor 6, respectively,
Output as the γ-axis current iγ and the δ-axis current iδ. The γ-δ axis current / induced voltage estimator 8 receives the γ-axis current iγ and the δ-axis current iδ, the γ-δ axis position information, the δ-axis voltage command Vδ ^*, and the γ-axis voltage command Vγ ^* , performing the operation of the expression (9), and outputs a γ-axis current estimated value i? _est and δ-axis current estimated value i? _est, the γ-axis induced voltage estimated value Ipushironganma _est and δ-axis induced voltage .epsilon..DELTA _est.

The angular velocity deriving unit 9 calculates the γ-axis induced voltage estimated value ε
γ _est and δ-axis induced voltage εδ _est are input, and equations (10) and (11) are executed to derive an estimated angular velocity ω _rmest .

The deviation angle deriving unit 10 calculates the angular velocity estimated value ω
_rmest and the γ-axis induced voltage estimated value εγ _est are input, and the following equation is calculated to calculate the deviation angle estimated value θ _eest . εγ _est = ω _rmest φ _mag sin θ _eest . . . . . . . . . . (21) Here, φ _mag is the magnetic flux of the rotor.

The γ-δ axis position corrector 11 outputs the angular velocity command ω
_rm ^* and the deviation angle estimation value θ _eest , and input the angular velocity command ω _rm ^*
(In practice, this integration operation corresponds to updating the phase angle at each sampling time k + 1 in accordance with equation (12)) to calculate a phase angle estimated value θ _est The phase angle estimation value θ _est and the deviation angle estimation value θ _eest are output to the vector control circuit 4, the inverter circuit 5, the phase converter 7, and the γ-δ axis current / induced voltage estimator 8 as the γ-δ axis position.

The γ-axis / δ-axis current corrector 12 is configured to output the γ-δ axis position.
From the displacement compensator 11_{ee st}Enter
Then, the γ-axis current is estimated from the γ-δ-axis current / induced voltage estimator 8.
Value iγ _estAnd δ-axis current estimated value iδ_estEnter the deviation angle
Constant value θ_eestΓ-axis current estimated value and δ-axis current
Γ-axis current command iγ_cor ^*And supplement
Positive δ-axis current command iδ_cor ^*Γ-axis current controller
Output to the roller 3 and the δ-axis current controller 2.

The δ-axis current command corrector 13 receives the estimated value of the γ-axis induced voltage εγ _est and corrects the δ-axis current command to correct the rotor speed ω _rm so that the estimated value of the deviation angle θ _{eest becomes} zero. Output value iδθ. The δ-axis current controller 2 calculates
The corrected δ-axis current command is generated by adding the axis current command iδ ^* and the δ-axis current command correction value iδθ. Then, based on the corrected δ-axis current command iδ _cor ^* output from the γ-axis / δ-axis current corrector 12, the deviation of the corrected δ-axis current command is proportionally integrated to obtain a δ-axis voltage command vδ ^* . Generate.

Although the δ-axis current command correction value iδθ, the corrected γ-axis current command iγ _cor ⁺ and the corrected δ-axis current command iδ _cor ^* are both current commands for correcting the deviation angle θ _e , The current command correction value iδθ functions to change the angular velocity of the rotor to reduce the deviation angle. However, since the true magnetic axis oscillates around the γ-axis only by the action of the δ-axis current command correction value iδθ, the corrected γ-axis current command iγ _cor ^* and the corrected δ-axis current command iδ _cor ^*
Works.

The load estimator 14 performs speed control at the time of load estimation.
Speed command ω to roller 1_rm ^**And the γ-δ axis current
Γ-axis induced voltage estimated value obtained from current / induced voltage estimator 8
εγ _estInput to the γ-axis current controller 3
Γ-axis current command i for load estimation (two types in this embodiment)
γ^* ₁, Iγ^* _TwoAnd the load estimation correction amount Δεγ_est(Formula (2
0)) and obtain the load estimation correction amount Δεγ_estComplement
Correct, estimate the corrected load, and match the load
Optimal γ-axis current command iγ^*Γ-axis current controller
Give to roller 3.

FIG. 5 is a diagram for explaining an example of a method of correcting a load estimation error caused by heating by the γ-axis current. First, the speed command ω _rm ^* is set to 0. Then, two kinds of gamma-axis current iγ ^* 1, iγ ^* γ-axis with respect to 2 induced voltage estimated value εγ _est 1, plotting a straight line the value of εγ _est. This straight line is the vertical axis (γ-axis induced voltage axis)
Is set to the reference value 0 of the γ-axis induced voltage (in this case, since the angular velocity ω _rm becomes 0, εγ _est automatically becomes 0). The slope of this line is proportional to the resistance change [Delta] R _S caused by the heating by γ-axis current.

Next, the inverter during the load estimation operation
The control operation of the device with respect to the load estimator 14 is shown in FIG.
This will be described with reference to a flowchart. First, the speed command ω_rm ^**
Is set to 0 (step S1), and the γ-axis current command is set to iγ^* ₁= I
γ^* _Two/ 2 to give to the γ-axis current controller 3
(Step S2). In response to the γ-axis current command, γ-δ
Γ-axis induction generated by axis current / induced voltage estimator 8
Voltage estimate εγ_estIs detected (step S3). next
iγ for γ-axis current command^* _Two(Step S4), and at this time
Estimated value of γ-axis induced voltage εγ_estIs detected (step S
5). Γ-axis current command iγ according to the graph of FIG.^* _TwoWith load
Load estimation amount correction value Δεγ at the time of estimation _estAsk for
(Step S6). Next, the low speed command ω_rm ^**The speed
Is given to the controller 1 (step S7), and the γ axis at that time
Estimated induced voltage εγ_estFrom the load obtained in step S6
The estimated value correction value Δεγ is subtracted, and the load angle is calculated from the subtraction result.
θ_e(Step S8), and a negative value is obtained according to the graph of FIG.
Load angle θ_eIs calculated (step S9).
γ-axis current command is iγ^**= K × iγ^*Switch to
Step S10). However, after switching the current, the control is
Shall wait for a sufficient amount of time to establish.

[0077]

As described above, according to the load estimating method of the present invention, the magnitude of the load connected to the synchronous motor driven by the inverter device can be changed without being affected by the resistance value fluctuation due to the motor temperature change. It can be estimated without a sensor, and by optimally adjusting the current value of the current command iγ ^* given in the γ-axis direction, the operating efficiency is increased, and the load on the power element of the inverter circuit in the case of continuous operation in the low-speed range is reduced. Can be reduced.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating a control device for a synchronous motor according to an embodiment of the present invention.

FIG. 2 is a flowchart showing digital control operations of a load estimation method and a sensorless control method.

FIG. 3 is a graph showing a relationship between a γ-axis induced voltage and a load angle.

FIG. 4 is a graph showing a relationship between a load angle and a coefficient K;

FIG. 5 is a graph showing a relationship between a γ-axis current command and a γ-axis induced voltage correction amount.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 speed controller 2 δ-axis current controller 3 γ-axis current controller 4 vector control circuit 5 inverter circuit 6 synchronous motor 7 phase converter 8 γ-δ-axis current / induced voltage estimator 9 angular velocity deriver 10 deviation angle deriver 11 γ- δ-axis position corrector 12 γ-axis / δ-axis current corrector 13 δ-axis current command corrector 14 Load estimator

Continuation of front page (72) Inventor Ryuichi Oguro 2-1 Kurosaki Castle Stone, Yawatanishi-ku, Kitakyushu-shi, Fukuoka Prefecture F-term (reference) 5H560 BB04 BB12 DA13 DC03 DC04 DC12 DC13 EB01 XA13 5H576 DD05 EE01 EE16 EE18 HB01 JJ25 LL22 LL24 LL35 LL38 LL39 MM15

Claims (8)

[Claims] 1. A three-phase voltage and current of a stator of a permanent magnet rotor type synchronous motor are projected onto a γ-δ coordinate system rotating at a rotation speed of the rotor, and a stator coil is formed by a magnetic flux of the rotating rotor. Voltage / current state including the γ-axis voltage-current equation and the δ-axis voltage-current equation, describing the γ-axis induction voltage and the δ-axis induction voltage, which are projections of the induced voltage onto the γ-δ coordinate system, as disturbances In the method for estimating the load of the permanent magnet rotor type synchronous motor controlled according to the equation, the γ-axis voltage / current equation and the δ-axis voltage / current equation in the absence of the induced voltage, that is, the non-disturbance γ-axis voltage /
The independent equation describing the current equation and the non-disturbed δ-axis voltage / current equation and the dependent variable determined depending on the independent variable are used to determine the γ-axis voltage / current equation and the δ-axis voltage / current when there is an induced voltage. Equations, that is, voltage / current state equations including a disturbance system γ-axis voltage / current equation and a disturbance system δ-axis voltage / current equation, and the voltage / current state equations in a steady state are set, and the voltage in the steady state is set.・ According to the current state equation,
Estimate the induced voltage value for the specified independent variable value, and use the load angle dependence of the induced voltage, in which the γ-axis induced voltage and the δ-axis induced voltage trigonometrically depend on the load angle, from the estimated induced voltage value. A load estimating method for a permanent magnet rotor type synchronous motor, comprising estimating a load angle. 2. The disturbance system γ-axis voltage / current equation in a steady state, wherein the independent variable is an independent command whose value can be arbitrarily set, and the dependent variable is a dependent command determined depending on the independent command. , The γ-axis induced voltage value corresponding to the designated independent command value is estimated, the γ-axis induced voltage estimated value is set as the first γ-axis induced voltage estimated value, and the resistance R of the synchronous motor has changed to R + ΔR. When, for the same independent command value as the specified independent command value,
The value of the γ-axis induced voltage obtained according to the disturbance system γ-axis voltage / current equation in the steady state is defined as a second γ-axis induced voltage estimated value, and the first γ-axis induced voltage is calculated from the second γ-axis induced voltage estimated value. The γ-axis induced voltage difference obtained by subtracting the estimated value is used to estimate the γ-axis induced voltage caused by the resistance change due to Joule heat generated by the current flowing through the synchronous motor corresponding to the specified independent command value. it is determined that the value changes, gamma corrected axis induced voltage estimated value, estimates the load angle theta _e from the corrected gamma-axis induced voltage estimated value, the permanent magnet rotor synchronous motor according to claim 1 Load estimation method. 3. The independent command is set so that neither the γ-axis current nor the δ-axis current flows, and then the predetermined values of the γ-axis current and the δ-axis current flow in a time-step function. In this manner, an independent command is applied, and the γ-axis induced voltage estimated value immediately after the γ-axis current and the δ-axis current rise in a step function and enter an electric steady state is set as a first γ-axis induced voltage estimated value, 3. The γ-axis induced voltage estimated value when the synchronous motor reaches a thermal equilibrium state while maintaining the independent command at the same value, as a second γ-axis induced voltage estimated value.
The load estimation method of the permanent magnet rotor type synchronous motor according to the above. 4. The disturbance system γ-axis voltage in the steady state.
An independent command value is set so that the angular velocity estimated value 0 and the δ-axis current estimated value 0 are estimated by the current equation, and a predetermined γ-axis current estimated value is estimated. The estimated value of the γ-axis induced voltage is corrected by assuming that the estimated value of the γ-axis induced voltage estimated by the equation is a change in the estimated value of the γ-axis induced voltage caused by a change in the resistance of the synchronous motor caused by heating by the current of the γ-axis. The load estimating method for a permanent magnet rotor type synchronous motor according to claim 2. 5. An independent command or dependent finger assuming full load
Γ-axis current command iγ specified as^*And the load angle θ_eBut
At 90 ° it is equal to 1 and the load angle θ_eTo decrease
Therefore, multiply by a coefficient K having a load angle characteristic that decreases monotonically.
And the load angle θ _eKiγ that changes in response to^*The gamma current finger
3. The permanent magnet rotor according to claim 2, which is given to the gamma axis as a command.
Load estimation method for synchronous motors. 6. The stator of a permanent magnet rotor type synchronous motor
Set the α-β coordinate system with the β-axis as the α-axis, the axis advanced by 90 ° in the forward rotation direction from the α-axis, and the designated magnetic axis of the synchronous motor in the forward rotation direction from the γ-axis. 90 ° electrical angle
Γ-δ that rotates with the angular velocity command ω _rm ^* with the advanced axis as the δ axis
A speed controller that sets an axis in the α-β coordinate system and outputs a δ-axis current command in response to a deviation signal of an angular velocity estimated value with respect to an angular velocity command; and a phase-corrected δ-axis current estimated value with respect to the δ-axis current command. From the deviation signal and the deviation signal of the phase-corrected γ-axis current estimated value with respect to the γ-axis current command,
a δ-axis current controller and a γ-axis current controller for respectively calculating a δ-axis voltage command and a γ-axis voltage command;
A vector control circuit that outputs a voltage command absolute value and a voltage command phase based on a shaft voltage command and a γ-axis voltage command, and an inverter circuit that supplies a drive current to a synchronous motor based on the voltage command absolute value and the voltage command phase. , Γ-axis current detection value, δ-axis current detection value, γ-axis voltage command,
A δ-axis voltage command and γ-δ-axis position information are input, and γ-δ coordinates of a three-phase AC voltage and current of a stator are set as disturbances, with an induced voltage induced in a stator coil by a magnetic flux of a rotating rotor as a disturbance. Calculate the estimated γ-axis current, estimated δ-axis current, estimated γ-axis induced voltage, and estimated δ-axis induced voltage according to the γ-axis voltage / current equation and δ-axis voltage / current equation describing the projection to the system. Γ-δ-axis current / induced voltage estimating means, and an angular velocity estimated value is generated from the γ-axis induced voltage estimated value and the δ-axis induced voltage estimated value output from the γ-δ axis current / induced voltage estimating means. Angular velocity deriving device that outputs to the controller, and the deviation angle between the true magnetic axis and the γ-axis are calculated from the γ-axis induced voltage estimated value and the δ-axis induced voltage estimated value,
-Output as δ-axis position information, correct the phases of the γ-axis current estimated value and the δ-axis current estimated value so as to reduce the deviation angle, and respectively correct the phase-corrected γ-axis current estimated value and Γ as the phase-corrected δ-axis current estimated value
In the control device of the permanent magnet rotor type synchronous motor including the deviation angle derivation / correction means for outputting to the shaft current controller and the δ-axis current controller, an angular velocity command for load estimation and a load estimation A γ-axis current command is output, and a γ-axis induced voltage estimation value output from the γ-δ axis current / induced voltage estimation means is input in response to the output angular velocity command and the γ-axis current command,
Calculate the change in the estimated value of the γ-axis induced voltage caused by the change in the resistance of the synchronous motor caused by the Joule heat of the current flowing through the synchronous motor in response to the angular velocity command and the γ-axis current command, and A load estimator that corrects the load angle estimated value from the change, wherein the load estimator sets the angular velocity command and the γ-axis current command for the load estimation to 0 at the initial load estimation,
A predetermined angular velocity command and a γ-axis current command are applied to the speed controller and the γ-axis current controller in a time-step function, respectively, and the δ-axis current and the γ-axis current rise in a step function to be in an electric steady state. The estimated value of the γ-axis induced voltage immediately after is referred to as a first estimated value of the γ-axis induced voltage, and the γ-axis induced voltage is estimated when the synchronous motor reaches a thermal equilibrium state while maintaining the angular velocity command and the γ-axis current command at the same value. The value is defined as a second γ-axis induced voltage estimated value, and the γ-axis induced voltage estimated value difference obtained by subtracting the first γ-axis induced voltage estimated value from the second γ-axis induced voltage estimated value is:
It is determined that the estimated value of the γ-axis induced voltage changes due to the resistance change due to the Joule heat generated by the current flowing through the synchronous motor in response to the angular velocity command and the γ-axis current command, and uses the estimated γ-axis induced voltage change. To correct the estimated value of the γ-axis induced voltage, and from the corrected estimated value of the γ-axis induced voltage, the load angle θ _e
A control device for a permanent magnet rotor type synchronous motor, characterized in that: 7. The load estimator sets the angular velocity command and the γ-axis current command to 0 at the initial stage of load estimation, and then sets γ-δ axis current / induced voltage estimation means
The estimated value of the shaft induced voltage is set to the reference value 0, and then, while maintaining the angular velocity command at 0, a predetermined value of the γ-axis current command is output, and after the synchronous motor reaches the thermal equilibrium state, the γ-δ-axis current The estimated γ-axis induced voltage output from the induced voltage estimating means is regarded as a change in the estimated γ-axis induced voltage caused by a change in the resistance of the synchronous motor caused by heating by the γ-axis current corresponding to the γ-axis current command. 7. The control device for a permanent magnet rotor type synchronous motor according to claim 6, wherein the estimated value of the γ-axis induced voltage is corrected. 8. The load estimator sets the angular velocity command and the γ-axis current command to 0 at the initial stage of load estimation, and then maintains the angular velocity command at 0 while maintaining the first predetermined value of the γ-axis A current command is output, and after the synchronous motor reaches a thermal equilibrium state, a first γ-axis induced voltage estimation value output from the γ-δ axis current / induced voltage estimation means is input. Γ-axis current command of the second predetermined value is output, and the second γ-axis induced voltage estimation output from the γ-δ-axis current / induced voltage estimation means after the synchronous motor reaches the thermal equilibrium state. Inputting a value, and calculating a change in resistance of the synchronous motor caused by heating by the γ-axis current corresponding to the γ-axis current command from a change in the estimated γ-axis induced voltage corresponding to a change in the γ-axis current command value. Item 7. A control device for a permanent magnet rotor type synchronous motor according to item 6.