JP7324630B2 - Motor magnet temperature estimation method and magnet temperature estimation device - Google Patents

Description

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

In order to improve the control accuracy of a motor, a technique of estimating the magnet temperature of a rotating motor and controlling the motor using the estimated magnet temperature is being studied. For example, according to the technique disclosed in Patent Document 1, a magnetic flux sensor is provided at the coil end, the magnetic flux sensor detects the magnetic flux leaking from the rotor, and the leaked magnetic flux and the magnet temperature are stored in advance. The magnet temperature is estimated from the relationship of

Japanese Patent Application Laid-Open No. 2004-222387

According to the technique disclosed in Patent Document 1, the load magnetic flux is generated not only by the magnet magnetic flux but also by the load current flowing through the coil, and the magnetic flux sensor existing near the coil detects the load magnetic flux and the magnet magnetic flux. may detect the total magnetic flux of Therefore, there is a problem that the measurement accuracy of the magnet magnetic flux is lowered, and the estimation accuracy of the magnet temperature may be lowered.

A method for estimating the magnet temperature of a motor according to the present invention controls rotation of a motor by applying a target current according to a torque command value. A method of controlling a motor includes changing a target current, obtaining a d-axis magnetic flux linkage number in each of a first state before changing the target current and a second state after changing the target current, and obtaining a first Based on the number of d-axis magnetic flux linkages in the state and the second state, the number of magnetic flux linkages of the permanent magnets provided in the rotor is calculated, and the magnet temperature of the permanent magnets is calculated according to the calculated number of magnetic flux linkages. to estimate

According to the method for estimating the magnet temperature of the motor of the present invention, the magnet flux linkage number of the permanent magnet is calculated without using a magnetic flux sensor, and the estimated temperature of the permanent magnet is obtained according to the magnet flux linkage number. , to improve the accuracy of the estimated temperature of the permanent magnet.

FIG. 1 is a schematic configuration diagram of the motor system of the first embodiment. FIG. 2 is a block diagram showing the detailed configuration of the magnet flux linkage number calculator. FIG. 3 is a block diagram showing the detailed configuration of the magnetic flux linkage number estimator. FIG. 4 is a diagram showing the current flowing to the controlled object. FIG. 5 is a diagram showing the current flowing to the motor of the second embodiment. FIG. 6 is a diagram showing current flowing to the motor of the third embodiment. FIG. 7 is a block diagram showing the detailed configuration of the magnet flux linkage number calculator. FIG. 8 is a diagram showing the configuration of a neural network that constitutes the motor system of the fourth embodiment. FIG. 9 is a block diagram showing the configuration of a part of the torque error compensator of the motor system of the fifth embodiment.

A motor system having a magnet temperature estimation device according to an embodiment of the present invention will be described.

(First embodiment)
FIG. 1 is a schematic configuration diagram of a motor system having a magnet temperature estimation device according to the first embodiment.

A motor system 10 includes a motor 1 to be controlled. Therefore, the portion A indicated by the dotted line other than the motor 1 corresponds to the motor control device. Note that the motor control device estimates the magnet temperature of the permanent magnets provided in the rotor of the motor 1 . Furthermore, the motor control device controls the rotational operation of the motor 1 using the estimated magnet temperature.

In the motor system 10, the current command value calculator 11 calculates torque current command values _id ^* _{and iq} ^* according to the torque command value T ^* . A correction unit 11A is provided in parallel with the current command value calculation unit 11, and the correction unit 11A outputs a correction value corresponding to the estimated magnet temperature _Tmag to the current command value calculation unit 11. For example, when the magnet temperature T _mag increases, the output torque value tends to decrease, so the correction unit 11A outputs positive correction values so that the torque current command values i _d ^* _and i _q ^* increase. .

In the calculated torque current command values i _d ^{* and} i _q ^* _, the minute current command value Δi _d ^* output from the minute current superimposing unit 12 is added by the adder 13 to the d-axis torque current command value i _d ^* . superimposed. Furthermore, current values _id ^and _{iq ,} which are feedback inputs from the motor ₁ , are negatively fed back by a subtractor 14 to the superimposed torque current command values id* and _iq ^* . The torque current command values i _d ^* _and i _q ^* that have passed through the adder 13 and the subtractor 14 are input to the load current control section 15 .

The load current control unit 15 is a general PI controller, and performs feedback control using current values _{id and iq} , which are observed values in the motor 1 . The load current control unit 15 generates ^voltage command values _vd ^* _and vq* such that the current values id and _{iq in} the motor 1 follow the torque current command values _id ^* _{and iq} ^* , and _generates Then, the voltage command values v _d ^* _and v _q ^* are output to the motor 1 .

The motor 1 may be configured to include an inverter and a sensor. A three-phase AC voltage generated by an inverter in response to the input of voltage command values v _d ^* _and v _q ^* is applied to the busbar of motor 1 to rotate the rotor of motor 1 . A current sensor is provided on the wiring between the inverter and the motor 1, and the three-phase AC current detected by the current sensor is phase-converted to obtain the current values id _{and iq} of the dq axes. can be obtained.

When Trig is input from a host device in response to a magnet temperature estimation request, the minute current superimposing unit 12 generates a minute current command value _Δid ^* so that a minute DC current _Δid flows only during that period. . In the motor system 10, the magnet temperature, which will be described later, is estimated by superimposing the minute current command value _Δid ^* on the torque current command values _id ^* _{and iq} ^* . Then, the magnet temperature T _mag of the permanent magnet provided in the rotor of the motor 1 is estimated using measured values during two periods, the period during which the minute current command value Δi _d ^* is superimposed and the period during which it is not superimposed. The details of the method of estimating the magnet temperature _Tmag will be described later.

The magnet flux linkage calculation unit 16 includes voltage command values v _d ^* _and v _q ^* to be input to the motor 1 , current values id _and i _q detected in the motor 1 , and the minute current superimposition unit 12 In addition to Trig input to , an electrical phase angle θe detected by a resolver provided near the rotor of the motor 1 is input. The magnet flux linkage number calculator 16 estimates the magnet flux linkage number ψ _a resulting from the permanent magnets provided in the rotor of the motor 1 based on these inputs.

The magnet temperature estimation unit 17 uses a table stored in advance to obtain the magnet flux linkage number ψ _a estimated by the magnet flux linkage number calculation unit 16 and the current values _id, i Based on _q , estimate the magnet temperature _Tmag .

The estimated magnet temperature T _mag is recursively input to the current command value calculation unit 10 via the correction unit 11A, and the torque current command values _id ^* _and i _q ^* are changed according to the magnet temperature T _mag. By doing so, the accuracy of the rotation control of the motor 1 can be improved. Further, as in the fifth embodiment, a torque error correction unit (see FIG. 9) is provided in the motor _system 10, and the motor The accuracy of rotation control of 1 may be improved.

FIG. 2 is a block diagram showing a detailed configuration of the magnet flux linkage number calculator 16. As shown in FIG.

The magnet flux linkage number calculation unit 16 has a magnetic flux linkage number estimation unit 21 and a magnet flux linkage number determination unit 22 .

Upon receiving inputs of the voltage command values v _d ^* _, v _q ^* , the current values _id, i _q , and the rotor electrical phase angle θe, the flux linkage number estimator 21 calculates the flux linkage number estimation value ψ _d ^{^} _, ψ _q ^{^} are estimated and output to the magnet flux linkage number determination unit 22 . Detailed processing in the magnetic flux linkage number estimating unit 21 will be described later with reference to FIG. In the magnetic flux linkage number estimation unit 21, the dq-axis magnetic flux linkage number estimated values ψ _d ^{^} _and ψ _q ^{^} are calculated. Only the linkage number estimate ψ _d ^{^} is used.

The magnet ^flux linkage number determination unit 22 determines the d _- axis flux linkage number estimated value ψ d ^ among the dq-axis flux linkage number estimated values ψ _d ^{^} _and ψ _q ^{^} estimated by the magnetic flux linkage number estimation unit 21 . , current values i _{d ,} i _q , and Trig. Since the minute current superimposing unit 12 shown in FIG. 1 superimposes the minute current command value Δi _d ^* only during the period when Trig is input, Trig is input to the magnet flux linkage number determining unit 22. The d-axis flux linkage number estimated values ψ _d ^{^} for two periods, one period and the other that are not input, are input. Then, the magnet flux linkage number determination unit 22 uses the d-axis flux linkage number estimated values ψ _d ^{^} for these two periods to estimate the magnet temperature T _mag according to Equation (4) described later.

FIG. 3 is a block diagram showing the detailed configuration of the magnetic flux linkage number estimator 21. As shown in FIG. It is assumed that the dq axes are a rotating coordinate system synchronized with the rotor, and the αβ axes are a stationary coordinate system.

The magnetic flux linkage estimation unit 21 includes a voltage model unit including a resistance value calculation unit 31, a dq/αβ conversion unit 32, and a subtractor 301, an inductance calculation unit 33, an adder 302, a dq/αβ conversion unit 34, It has a subtractor 303 and a current model section consisting of a PI controller 35 . Then, the outputs from the voltage model section and the current model section are added in the adder 304, and the addition result is time-integrated in the integrator 36, so that the αβ-axis flux linkage number estimated values ψ _α ^{^} _and ψ _β ^{^} are Calculated. Finally, the dq-axis magnetic flux linkage number estimated values ψ _d ^̂ _and ψ _q ^̂ are output through the αβ/dq conversion unit 37 . Note that the rotor electrical phase angle θe detected by the resolver is used in the conversion processing in the dq/αβ conversion unit 32, the dq/αβ conversion unit 34, and the αβ/dq conversion unit 37.

First, the voltage model section will be described.

The resistance value calculator 31 multiplies the input current values id _{and iq} by the resistance values Rd _{and Rq} to calculate the voltage values generated in the winding resistances of the motor 1 . This value is converted into an αβ coordinate value by a dq/αβ conversion unit 32 provided at a later stage. Then, subtractor 301 calculates Δv _α and _{Δv β by} subtracting the voltage value of the winding resistance output from dq/αβ conversion unit ³² from voltage command values v α _{* and} v β ^* .

Δv _{α and} Δv _β output from the voltage model section are added to an output value from the current model section in adder 304 as will be described later. The integrator 36 integrates the addition result of the adder 304 to calculate the αβ-axis magnetic flux linkage number estimated values ψ _α ^̂ _and ψ _β ^̂ . The αβ/dq conversion unit 37 performs αβ/dq conversion on the input αβ-axis magnetic flux linkage estimated values ψ _α ^{^} _and ψ _β ^{^} to obtain the dq-axis magnetic flux linkage estimated values ψ _d ^{^} _, ψ _q ^{^} .

Here, in _the motor 1, an induced voltage is generated according to the amount of change in the magnetic flux linkage over time _. Equivalent to. Therefore, the number of interlinkage magnetic fluxes in the motor 1 can be obtained by time-integrating Δv _{α and} Δv _β corresponding to the induced voltage. Therefore, by time-integrating Δv _{α and} Δv _β in the post-stage integrator 36, αβ-axis magnetic flux linkage estimated values ψ _α ^̂ _and ψ _β ^̂ are obtained as the magnetic flux linkages in the motor 1 .

However, due to the integration process, an indefinite integral multiplier is generated. Therefore, in order to suppress the error caused by the integral multiplier, the current model section including the inductance calculator 33 to the PI controller 35 is configured. The current model section will be described below.

The inductance calculator 33 multiplies the current values id _{and iq} by the inductance values Ld _{and Lq} of the motor 1 to calculate the number of magnetic flux linkages generated in the motor 1 according to the current load. This process is based on common current, inductance and flux linkage relationships. It is assumed that the inductance values L _{d and} L _q are fixed values.

The adder 302 adds the magnetic flux linkage number resulting from the current calculated in the inductance calculation unit 33 and the magnet flux linkage fixed value ψ _a ' to obtain the dq-axis magnetic flux linkage estimated value (current Model) Calculate ψ _{d_i} ^{^} _, ψ _{q_i} ^{^} . The magnet flux linkage number fixed value ψ _a ' is the magnet flux linkage number caused by the permanent magnet in the no-load state in which no current is applied to the motor 1, and is stored in advance in the flux linkage number estimator 21. ing. In this way, by adding the magnet flux linkage fixed value ψ _a ' in advance, it is possible to suppress an error in a state such as immediately after driving when there is no initial state.

In the dq/αβ conversion unit ₃₄ , the ^estimated _{αβ -} axis magnetic ^flux linkage number ( current model) ψ _{α_i} ^{^} _, ψ _{β_i} ^{^} are calculated.

In the subtractor 303, the αβ-axis magnetic flux linkage estimated values (current model) ψ _{α_i} ^{^} _, ψ _{β_i} ^{^} are converted to the αβ-axis magnetic flux linkage estimated values ψ _α ^{^} _, ψ _β output from the integrator 36 in the subsequent stage. Δψ _{α_i and} Δψ _{β_i} are calculated by subtracting ^{^} .

Then, the PI controller 35 performs PI control on Δψ _{α_i and} Δψ _{β_i} to obtain αβ-axis magnetic flux linkage estimated values (current models) ψ _{α_i} ^{^} _, ψ _{β_i} ^{^} and αβ-axis magnetic flux linkage Control is performed so that deviations from the estimated values ψ _α ^{^} _and ψ _β ^{^} are small.

When the output from the voltage model section is integrated by the integrator 36 as described above, an integration constant may be generated and the system may become unstable. However, in the current model section, a feedback system is formed by the PI controller 35, and the magnet flux linkage number fixed value ψ _a ' is input to the subtractor 301 as an initial value. With such a configuration, in any state including the initial state, it is possible to suppress deterioration in the accuracy of the αβ-axis magnetic flux linkage number estimation values ψ _α ^{^} _and ψ _β ^{^} due to the constant of integration becoming indefinite. can be done.

Here, the PI controller 35 can determine the degree of contribution of each of the voltage model section and the current model section to the estimation of the dq-axis magnetic flux linkage estimated values ψ _d ^{^} _and ψ _{q ̂} ^. For example, by designing the gain in the PI controller 35 to decrease, the voltage model has a stronger influence on the estimation of the αβ-axis magnetic flux linkage number estimated values ψ _α ^{^} _and ψ _β ^{^} than the current model. . It is also known that when the number of revolutions of the motor 1 is large, the gain of the PI controller 35 provided in the current model section decreases. A vessel 35 is designed.

FIG. 4 is a diagram showing the current flowing to the motor 1. As shown in FIG. In this figure, the x-axis indicates time and the y-axis indicates the d-axis current value _id .

During the period 1, the minute current superimposing unit 12 does not output anything, and during the period 2, the minute current superimposing unit 12 outputs the minute current command value Δi _d ^* according to Trig. Therefore, the current value i _d in the period 1 becomes the d-axis current value i _d ′ in the period 2 by superimposing the minute current command value Δi _d ^* from the minute current superimposing unit 12 . Note that this period 2 is a period during which Trig is input to the minute current superimposing unit 12 . Note that the period 1 is an example of the first state, and the period 2 is an example of the second state.

Next, a method for calculating the magnet flux linkage number in the magnet flux linkage number determination unit 22 will be described.

As described above, the magnetic flux linkage number estimator 21 estimates the magnetic flux linkage numbers ψ _{d and} ψ _q from the current values _{id and} i _q . The d-axis magnetic flux linkage number ψ _d generated in the motor 1 while the current values _{id and} i _q flow is the sum of the magnet magnetic flux linkage number ψ _a and the magnetic flux linkage number caused by the current. . Note that the number of magnetic flux linkages caused by the current is determined by the product (L _d · _id ) of the d-axis inductance L _d and the d-axis current value _id .

Therefore, if the number of d-axis magnetic flux linkages in period 1 is ψ _d and the d-axis current is _id , and the number of d-axis magnetic flux linkages in period 2 is ψ _d ′ and the d-axis current is _id ′, period 1 and In period 2, the following equations are respectively established.

Assuming that the inductance L is equal for each of these equations (1) and (2), the inductance L can be expressed as follows from equation (1).

By substituting equation (3) into equation (2), the following equation can be derived.

The magnet flux linkage number determination unit 22 calculates the d-axis magnetic flux linkage numbers ψ _d and ψ _d ′ using the measured values in the two periods 1 and 2, and based on the equation (4), the d-axis The magnetic flux linkage number ψ _a can be estimated using the magnetic flux linkage numbers ψ _d , ψ _{d ′ and} the d-axis current values id , _id ′.

The magnet temperature estimator 17 stores in advance a table in which the d-axis current value i _d , the q-axis current value i _q , and the magnet flux linkage number ψ _a are associated with the magnet temperature T _mag , Estimate the magnet temperature T _mag using the input values and the table. It should be noted that the magnet temperature estimator 17 can improve the estimation accuracy of the magnet temperature T _mag by individually storing tables not only for one current operating point but also for many current operating points.

Note that the table value is a table having four parameters of the d-axis current value i _d , the q-axis current value i _q , the magnet flux linkage number ψ _a , and the magnet temperature T _mag . It is difficult to remember well-matched tables. Therefore, when the input value does not exist in the table, the table is interpolated using a method such as linear interpolation. By doing so, it is possible not only to shorten the time required to prepare the table in advance, but also to reduce the capacity of the table stored in the magnet temperature estimating section 17 . In the fourth embodiment, a neural network is used to estimate the magnet temperature T _mag without using a table.

In the present embodiment, an example of superimposing a minute current on the d-axis using the minute current superimposing unit 12 has been described, but the present invention is not limited to this. A minute current serving the d-axis component may be superimposed. For example, when the magnitude of the current changes at a desired timing according to the accelerator operation, etc., by estimating the d-axis magnetic flux linkage number _ψd according to the timing, the magnet flux linkage number _ψa can be calculated as can ask.

According to the first embodiment, the following effects can be obtained.

According to the method for estimating the magnet temperature of the motor 1 of the first embodiment, the minute current superimposing unit 12 generates torque current command values i _d ^* _and i _q ^* corresponding to the target torque according to the input of Trig. , torque _current command values _id ^{* and} _{iq *} ^, _which are smaller than the torque current command values _id ^{* and} _iq ^* . Then, the magnetic flux linkage number estimator 21 calculates the _d ^- axis magnetic flux linkage number Estimate the estimated value ψ _d ^{^} . The magnet flux linkage number determination unit 22 calculates the magnet flux linkage number ψ _a of the permanent magnets included in the rotor based on the d-axis flux linkage number estimated value ψ _d ^{^} in the case of period 1 and period 2. do. Then, the magnet temperature estimator 17 estimates the magnet temperature T _mag of the permanent magnet based on the magnet flux linkage number ψ _a .

Also, Δv _{α and} Δv _β corresponding to the induced voltages generated according to the change in the magnetic flux are obtained, and the induced voltages are integrated in the integrator 36 to estimate the flux linkage number estimated values ψ _d ^{^} _and ψ _q ^̂ . do. As a result, the magnet flux linkage number ψ _a can be obtained without using a magnetic flux sensor. Therefore, the magnetic flux sensor is not likely to measure the load magnetic flux other than the magnet magnetic flux, and the magnet interlinkage magnetic flux number can be obtained with high accuracy. As a result, the estimation accuracy of the magnet temperature _Tmag can be improved. As a result, by controlling the target current using the magnet temperature _Tmag estimated with high accuracy, the accuracy of the rotation control of the motor 1 can be improved.

According to the method for estimating the magnet temperature of the motor 1 of the first embodiment, different _d ^- axis magnetic flux linkage number estimated values ψ _d ^̂ Desired. Here, it is assumed that the magnet flux linkage number ψ _a , which is a part of the d-axis magnetic flux linkage number estimated value ψ _d ^{^} , does not change depending on whether or not the minute current command value Δi _d ^* is superimposed. Furthermore, the other part of the d-axis flux linkage estimated value ψ _d ^{^} corresponds to the product of the d-axis current value id and the d-axis inductance _{L d ,} but the d-axis inductance L _d is the minute current command value Δi It is assumed that _d ^* does not change with or without superimposition.

Therefore, first, in the case of period 1 in which the minute current command value Δi _d ^* is not superimposed, the d-axis inductance _{L d is} calculated using the d-axis flux linkage estimated value ψ _d ^{^} and the d-axis current value id. Keep Then, by substituting the calculated d-axis inductance L _d for the case of period 2 in which the minute current command value Δi _d ^* is superimposed, the magnet flux linkage number ψ _a can be obtained. Specifically, the magnet flux linkage number ψ _a can be obtained by using the equation (4).

According to the method for estimating the magnet temperature of the motor 1 of the first embodiment, the magnet temperature estimator 17 preliminarily calculates the d-axis current value i _d , the q-axis current value i _q , and the magnet flux linkage number ψ _a and , magnet temperature T _mag , and the magnet temperature T _mag is estimated using these input parameters and the table showing their correspondence. By using the table in this way, the magnet temperature T _mag can be estimated only by searching the table without increasing the processing load of the magnet temperature estimator 17 .

In addition, when the number of samples stored in the table is small, if the input parameter is not included in the table, the parameter that does not exist in the table is complemented in the table, and the magnet temperature T _mag is calculated using the complemented table. presume. By doing so, the processing load of the magnet temperature estimating unit 17 is slightly increased, but the table can be made smaller, so that the amount of memory used can be reduced.

(Second embodiment)
In the first embodiment, the micro-current superimposing unit 12 does not output a micro-current in period 1 and outputs a positive micro-current in period 2, but it is not limited to this. In the second embodiment, the micro-current superimposing unit 12 may repeatedly perform non-output of micro-current, superimposition of positive micro-current, and superimposition of negative micro-current.

FIG. 5 is a diagram showing the current flowing through the motor 1. As shown in FIG. In the period 1, the minute current superimposing unit 12 does not output anything and the current value is _id . In period 2, the minute current superimposing unit 12 outputs the minute current command value Δi _d ^* so that a positive minute current is superimposed, so the current value flowing through the motor 1 becomes _id2 . In the period 3, the minute current superimposing unit 12 outputs the command value -Δi _d ^* so that the minute negative current is superimposed, so the current value becomes i _d3 .

Here, in the periods 1 and 2 and in the periods 1 and 3, since the relationship of formula (3) holds respectively, the following two formulas hold.

However, ψ _a1 is the magnet flux linkage number calculated using the periods 1 and 2, and ψ _a2 is the magnet flux linkage number calculated using the periods 1 and 3. Furthermore, ψ _d1 and i _d1 are the d-axis flux linkage number and d-axis current in period 1, respectively, and ψ _d2 and i _d2 are the d-axis flux linkage number and d-axis current in period 2, respectively. , and ψ _d3 and i _d3 are the d-axis flux linkage number and the d-axis current in period 3, respectively.

Then, by averaging the equations (5) and (6), the magnet flux linkage number ψ _a can be obtained as in the following equation.

By using such equation (7), the magnet flux linkage number _ψa can be calculated using the state in which the positive and negative minute currents are superimposed without significantly changing the configuration of the minute current superimposing unit 12. , can improve the estimation accuracy. In this embodiment, minute currents of the same magnitude but different signs are superimposed, but the present invention is not limited to this. Three or more minute currents of different magnitudes may be superimposed, three or more magnet flux linkages may be calculated, and an average of these may be obtained.

According to the second embodiment, the following effects can be obtained.

According to the method for estimating the magnet temperature of the motor 1 of the second embodiment, the minute current superimposing unit 12 does not superimpose a minute current in period 1, and superimposes a positive minute current command value Δi _d ^* in period 2. , and in period 3, a negative minute current command value Δi _d ^* is superimposed. Then, the magnet flux linkage number calculated using the d-axis flux linkage number ψ _d in periods 1 and 2, and the magnet flux linkage number calculated using the d-axis flux linkage number ψ _d in periods 1 and 3 and the final magnet flux linkage number ψ _a . By increasing the number of samples in this way, the magnet flux linkage ψ _a can be estimated with higher accuracy, so that the estimation accuracy of the magnet temperature T _mag can be improved.

(Third embodiment)
In the first and second embodiments, a predetermined minute DC current is superimposed, but the present invention is not limited to this. In the third embodiment, an example of superimposing a very small alternating current will be described. According to this method, since the motor 1 is controlled by the DC component and the AC component can be distinguished as being used only for estimating the magnet temperature, the estimation accuracy of the magnet temperature _Tmag is further improved. can be achieved.

FIG. 6 is a diagram showing the current flowing through the motor 1 by the motor system 10 of the third embodiment. As shown in this figure, the minute current superimposing unit 12 outputs an alternating current of frequency f _HF and amplitude i _HF in period 2 according to Trig, and the alternating current is superimposed on _{the d} -axis current value id. be done.

FIG. 7 is a diagram showing the configuration of the magnet flux linkage number calculator 16 in the motor system 10 of the third embodiment. The magnet flux linkage number calculator 16 of the present embodiment has an additional inductance estimator 71 when compared with the magnet flux linkage number calculator 16 of the first embodiment shown in FIG.

Here, in the period 2 in which the alternating current is input from the minute current superimposing unit 12, the voltage vector in the motor 1 has a voltage component caused by the inductance L, which is the current vector to be superimposed. A 90 degree phase lead component v _{HF_img} is included. By measuring _{vHF_img} , which is a component contributed by this inductance, the measured _{vHF_img} can be used to calculate the d-axis inductance _Ld based on the following equation.

v _{HF_img} detected by a lock-in amplifier or the like is input to the inductance estimator 71 . Further, the inductance estimator 71 stores the frequency f _HF and the amplitude i _HF of the AC component generated by the minute current superimposing unit 12, which are stored in advance. The inductance estimator 71 can estimate the d-axis inductance _Ld based on the equation (8) in the interval 2 in which Trig is input.

Then, the magnet flux linkage number determination unit 22 estimates the magnet flux linkage number ψ _a using the following equation.

Equation (9) results from the fact that the estimated d-axis flux linkage number ψ _d is the sum of the magnet flux linkage number ψ _a and the magnetic flux L _d · _id caused by the current. Also in this way, the magnet flux linkage number ψ _a can be calculated. It should be noted that it is preferable to calculate the magnet flux linkage number ψ _a during the period 1 in which the AC signal is not superimposed, because the d-axis current value _{id is} stable. However, it is not limited to this, and may be performed in period 2.

According to the third embodiment, the following effects can be obtained.

According to the method for estimating the magnet temperature of the motor 1 of the third embodiment, the minute current superimposing unit 12 superimposes a minute AC current. When such an alternating current is superimposed, in the voltage vector observed in the motor 1, the component v _{HF_img} whose phase leads the superimposed current vector by 90 degrees due to the inductance component is included. Therefore, the d-axis inductance L _d is calculated from the observed v _{HF_img} and the superimposed minute AC current. In this way, since the d-axis inductance _Ld can be directly calculated, the magnet flux linkage is greater than the case where the d-axis inductance _Ld is assumed to be fixed as in the first and second embodiments. The estimation accuracy of the number ψ _a can be improved.

(Fourth embodiment)
In the first to third embodiments, the magnet temperature estimator 17 previously associates the d-axis current value i _d , the q-axis current value i _q , and the magnet flux linkage number ψ _a with the magnet temperature T _mag . Although an example of storing the attached table has been described, the present invention is not limited to this. In the fourth embodiment, an example in which the magnet temperature estimator 17 estimates the magnet temperature _Tmag using a neural network will be described.

FIG. 8 is an example showing the configuration of a neural network. In a neural network, a plurality of hidden layers are provided between an input layer and an output layer. In this embodiment, the magnet flux linkage number ψ _a is input to the input layer, and the magnet temperature T _mag is output from the output layer. Also, in the hidden layer, neurons 1-4 are shown. In this example, it is assumed that the nonlinear function 1/(1+e ^-ax ) is used as the firing function in the neuron.

In this example, the input layers are multiplied by input weights 1 to 4 (Win-1 to Win-4) and input to neurons 1 to 4, respectively. In neurons 1 to 4, after offsets 1 to 4 are added, output weighting 1 to 4 (Wout-1 to Wout-4) is performed and output to the output layer. Also in the output layer, an offset (Offset_out) is given. Therefore, the estimated magnet temperature T _mag can be expressed as follows.

Thus, by multiplying the input by the weight, adding the offset value, and using the nonlinear function, the output data can be obtained approximately from the input data. In the actual magnet temperature estimator 17, a neural network can be realized by implementing these weights, offsets, and nonlinear functions as matrices. It should be noted that other methods such as the kernel method may be used instead of the neural network.

According to the fourth embodiment, by estimating the magnet temperature T _mag from the magnet flux linkage number ψ _a by a method such as a neural network using a matrix having constants and nonlinear functions as components, Since the magnet temperature estimator 17 does not need to store a table relating to the magnet flux linkage number, the configuration of the magnet temperature estimator 17 can be simplified.

(Fifth embodiment)
In the fifth embodiment, as a correction to the load current control unit 15 for the motor 1, an example of performing a correction according to the estimated magnetic flux linkage number estimated values ψ _d ^̂ and ψ _q ^̂ will be described. This correction is performed by correcting the q-axis current value _iq .

Here, it is known that the torque T generated in the motor 1 can be estimated as the outer product of the estimated values of magnetic flux linkage ψ _d ^{^} and ψ _q ^̂ and the current values id _and i _q , and can be expressed by the following equation. It is known. Note that the torque estimated by the following equation is the torque generated per pole pair.

FIG. 9 is a block diagram when torque error compensation is performed on the load current control unit 15. As shown in FIG.

Of this configuration, the configuration from the flux linkage number estimating section 21 to the multipliers 901 and 902, the adder 903, and the multiplier 904 corresponds to Equation (11). That is, the product of the d-axis flux linkage number estimated value ψ _d ^{^} and the q-axis current value i _q by the multiplier 901 and the q-axis flux linkage number estimate value ψ _q ^{^} and the d-axis current value i _d by the multiplier 902 is added by the adder 903 to calculate the torque per pole pair. Furthermore, according to the multiplier 904 in the latter stage, the torque estimated value T̂ is calculated by multiplying by the number of pole pairs.

Then, the subtractor 905 subtracts the estimated torque value T^ from the torque command value T ^* , and this result is input to the torque error compensator 91 . In the torque error compensator 91, the q-axis current correction value is calculated so that the estimated torque T^ follows the torque command value T ^* , and is added to the q-axis current command value _iq ^* in the adder 906.

A torque error is calculated by subtracting the estimated torque value T^ from the torque command value T ^* in the preceding stage of the torque error compensating unit 91, and the torque error compensating unit 91 compensates for the torque error. q-axis current correction value is obtained. Then, in the subsequent stage of the torque error compensator 91, the q-axis current correction value is subtracted from the q-axis current command value i _q ^* . The q-axis current value i _q is suitable not only for torque control, but also because the minute current used for magnet temperature measurement is superimposed on the d-axis current value i _d , the q-axis current value i _q can be adjusted by the current correction value. I can afford to be. Therefore, the torque error can be corrected by controlling the q-axis current value i _q .

According to the fifth embodiment, the following effects can be obtained.

According to the method of estimating the magnet temperature of the motor 1 of the fifth embodiment, the estimated magnet temperature T _mag is used to estimate the estimated torque value T^ occurring in the motor 1, and the estimated torque value T^ is the torque command value. The q-axis current command value i _q ^* is corrected so as to follow T ^* . The magnet temperature _Tmag is measured by superimposing a minute current on the _d -axis current value id, which has little effect on the torque of the motor 1, and the q-axis current value _iq has a margin for torque control, so it is relatively small. Torque correction is easy. By correcting the q-axis current command value i _q ^* in this way, the motor 1 is controlled in consideration of the magnet temperature _Tmag , so that torque fluctuations can be reduced and noise can be reduced. can.

Although the embodiments of the present invention have been described above, the above embodiments merely show a part of application examples of the present invention, and the technical scope of the present invention is not limited to the specific configurations of the above embodiments. do not have. Moreover, the above-described embodiments can be combined as appropriate.

REFERENCE SIGNS LIST 10 motor system 1 motor 11 current command value calculation unit 11A correction unit 12 minute current superimposition unit 15 load current control unit 16 magnet flux linkage calculation unit 17 magnet temperature estimation unit 21 magnetic flux linkage number estimation unit 22 magnet flux linkage number decision part

Claims (12)

A method for estimating a magnet temperature of a motor for controlling the rotation of the motor by applying a target current according to a torque command value,
changing the target current by superimposing a d-axis minute current smaller than the target current on the target current ;
Obtaining the d-axis magnetic flux linkage number in each of a first state before superimposing the minute current on the target current and a second state after the minute current is superimposed on the target current;
based on the d-axis magnetic flux linkage numbers in the first state and the second state, calculating the magnetic flux linkage numbers of the permanent magnets included in the rotor;
A method for estimating the magnet temperature of a motor, wherein the magnet temperature of the permanent magnet is estimated according to the calculated magnet flux linkage. A method for estimating a magnet temperature of a motor according to claim 1,
obtaining a difference between a measured value of the voltage flowing through the motor and a voltage command value corresponding to the target current;
A method for estimating a magnet temperature of a motor, wherein a magnetic flux linkage number including the d-axis magnetic flux linkage number is obtained by integrating the difference. A method for estimating the magnet temperature of a motor according to claim 2 ,
the minute current is a direct current,
calculating the magnet flux linkage number based on the d-axis magnetic flux linkage number in the first state, the d-axis magnetic flux linkage number in the second state , and the d-axis current flowing through the motor; method for estimating the magnet temperature. A method for estimating the magnet temperature of a motor according to claim 3 ,
The method for estimating the magnet temperature of the motor, wherein the magnet flux linkage number is calculated by Equation (1).

_id is the d-axis current in the first state;
ψ _d is the d-axis magnetic flux linkage number in the first state,
i _d ' is the d-axis current in the second state;
ψ _d ′ is the d-axis magnetic flux linkage number in the second state. A method for estimating the magnet temperature of a motor according to claim 2 ,
Calculating two or more magnet flux linkages using the minute currents of two or more different magnitudes,
A method for estimating a magnet temperature of a motor, wherein the magnet flux linkage number is calculated by averaging two or more calculated magnet flux linkage numbers. A method for estimating the magnet temperature of a motor according to claim 2 ,
the minute current is an alternating current,
In the second state, obtaining the inductance of the motor based on the 90-degree lead component of the voltage vector of the motor with respect to the vector of the minute current and the amplitude and frequency of the minute current;
A method for estimating the magnet temperature of a motor, wherein the magnet flux linkage number is calculated by subtracting the product of the inductance and the target current from the obtained d-axis flux linkage number. A method for estimating the magnet temperature of a motor according to claim 6 ,
A method for estimating a magnet temperature of a motor, wherein the inductance is obtained by equation (2), and the magnet flux linkage is calculated by equation (3).

L _d is the inductance;
v _{HF_img} is the leading component of the voltage applied to the motor by 90 degrees with respect to the current in the second state;
f _HF is the frequency of said minute current;
i _HF is the amplitude of said minute current;
_id is the d-axis current flowing through the motor;
ψ _d is the obtained d-axis magnetic flux linkage number. A method for estimating a magnet temperature of a motor according to claim 1 ,
Using a pre -stored table showing the correspondence relationship between the parameters of the magnet flux linkage, the d-axis current value and the q-axis current value flowing through the motor , and the magnet temperature, the parameters to be input are A method for estimating the magnet temperature of a motor, estimating the temperature of said permanent magnet accordingly. A method for estimating the magnet temperature of a motor according to claim 8 ,
A method for estimating a magnet temperature of a motor, wherein when the input parameter is not included in the table, the parameter not included is complemented in the table. A method for estimating a magnet temperature of a motor according to claim 1 ,
A method for estimating the magnet temperature of a motor, wherein the magnet temperature is estimated according to the magnet flux linkage number using a neural network. A method for estimating the magnet temperature of a motor according to claim 2 ,
estimating an estimated torque value in the motor according to the magnetic flux linkage and the magnet temperature;
A method for estimating a magnet temperature of a motor, wherein the target current of the q-axis input to the motor is corrected so that a deviation between the torque command value and the torque estimation value is reduced. A magnet temperature estimating device for controlling the rotation of the motor by causing a target current corresponding to a torque command value to flow through the motor,
a changing unit that changes the target current by superimposing a d-axis minute current that is smaller than the target current on the target current ;
Magnetic flux linkage calculation for obtaining a d-axis magnetic flux linkage in each of a first state before superimposing the minute current on the target current and a second state after the minute current is superimposed on the target current. Department and
a magnet flux linkage number calculation unit that calculates a magnet flux linkage number of a permanent magnet included in a rotor based on the d-axis flux linkage numbers in the first state and the second state;
A magnet temperature estimating device for a motor, comprising: a magnet temperature estimating unit that estimates the magnet temperature of the permanent magnet according to the calculated magnet flux linkage.

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