JP3283729B2 - Induction motor control device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a control device for an induction motor for improving the operation efficiency of the induction motor.

[0002]

2. Description of the Related Art FIG. 15 shows a conventional control device for an induction motor disclosed in Japanese Patent Publication No. 6-69307. In the figure, reference numeral 1 denotes an induction motor, and 2 denotes an electric rotation frequency ω _{r of the} induction motor 1. , A current detector for detecting the primary currents i _vs , i _us of the induction motor 1,
Reference numeral 4 denotes a voltage source inverter that drives the induction motor 1 at a variable frequency. 5 is a primary current i obtained from the current detector 3
_vs , _ius coordinate axes (d−q) rotating in synchronization with the secondary magnetic flux
Coordinate converter for converting coordinates on the axis), 6, 7 are subtractors,
8 and 9 are controllers, and 10 is d- obtained from the controllers 8 and 9.
The primary voltage commands v _qs ^* and v _ds ^* on the q-axis are _converted into three-phase voltage commands v
_This is a coordinate converter for converting into _us ^* , v _vs ^* , v _ws ^* .

A divider 11 divides a primary current q-axis component command i _qs ^* by a secondary magnetic flux command φ _dr ^*.
A coefficient unit 13 outputs a slip frequency ω _s by multiplying the output of by a constant, and 13 adds the electrical rotation frequency ω _r obtained from the rotation frequency detector 2 and the slip frequency ω _s obtained from the coefficient unit 12. An adder that outputs a primary frequency ω, 1
Reference numeral 4 denotes an integrator that integrates the primary frequency ω and gives the phase θ of the dq coordinate axis. 15 is a coefficient unit, 16 is a function generator that gives an amplitude ratio C between a primary current command and a secondary magnetic flux command based on the primary frequency ω, and 17 is a unit for dividing the output of the coefficient unit 15 by the output C of the function generator 16. A divider 18 is a function generator for generating the square root of the absolute value of the output of the divider 17, 19 is a divider for dividing the output of the coefficient unit 15 by the output φ _dr ^* of the function generator 18, and 20 is a differential element. It is a current command calculator that performs calculations that include it.

Next, the operation will be described. First, the basic operation principle of the control device for the induction motor will be described. The slip frequency ω _s of the induction motor, the secondary magnetic flux φ _dr, and the q-axis component _iqs of the primary current have a relationship represented by Expression (1).

[0005]

(Equation 1) Where ω _s : slip frequency of induction motor M: mutual inductance value of induction motor R _r : secondary resistance value of induction motor L _r : secondary inductance value of induction motor φ _dr : d axis of secondary magnetic flux of induction motor Component (secondary magnetic flux of the induction motor) i _qs : q-axis component of the primary current of the induction motor Therefore, the divider 11 and the output of the divider 11 are represented by MR _r / L
The calculation of the equation (2) is performed using the coefficient unit 12 multiplying by _r .

[0006]

(Equation 2) However, φ _dr ^* : d-axis component command of the secondary magnetic flux of the induction motor (secondary magnetic flux command of the induction motor) i _qs ^* : q-axis component command of the primary current of the induction motor Primary frequency ω and electrical rotation frequency ω _r And the slip frequency ω _s , the relationship represented by the equation (3) holds. Therefore, the primary frequency ω is obtained by adding ω _s and ω _r by the adder 13.

[0007]

[Equation 3] Then, when the primary frequency ω is integrated by the integrator 14, the phase of the dq axis, that is, the phase θ of the secondary magnetic flux is obtained. The coordinate converter 5 uses the phase θ of the secondary magnetic flux obtained from the integrator 14 and the primary currents i _vs and i _us obtained from the current detector 3,
The d-axis component _ids and the q-axis component _iqs of the primary current are calculated according to equation (4).

[0008]

(Equation 4) Where, _ids : d-axis component of the primary current of the induction motor, i _us : primary current of the u-phase winding of the induction motor, i _vs : primary current of the v-phase winding of the induction motor, and d-axis component _{ids of the} primary current Since the secondary magnetic flux φ _dr has the relationship of the equation (5), the current command calculator 20 calculates the equation (6) including the differential operator P based on the secondary magnetic flux command φ _dr ^* to calculate the primary magnetic flux. A current d-axis component command _ids ^* is generated.

[0009]

(Equation 5) Here, _Tr : the secondary time constant of the induction motor (= _Lr / R
_r ) The subtractor 6 calculates the deviation between the d-axis component _ids of the primary current and the command _ids ^* , and amplifies the deviation with the controller 8 to obtain the d-axis component command _vds ^{* of the} primary voltage. . Similarly, the subtractor 7 calculates a deviation between the q-axis component i _qs of the primary current and the command i _qs ^* , and amplifies the deviation by the controller 9 to obtain a q-axis component command v _qs ^{* of the} primary voltage. . Then, the three-phase voltage commands v _us ^* , v _vs ^* , and v _ws ^* are given by Equation (7).
Is calculated by the coordinate converter 10.

[0010]

(Equation 6) The voltage type inverter 4 has three-phase voltage commands v _us ^* , v _vs ^* ,
The three-phase voltages v _us , v _vs , and v _ws are generated so as to match v _ws ^* . As described above, the secondary magnetic flux command φ _dr ^* and the primary current q-axis component command i _qs ^* can be controlled.

[0011] Then, no matter how the secondary magnetic flux command φ _dr ^* and the q-axis component command i _qs ^* of the primary current are given, the induction motor 1
The following describes how to minimize the loss. If the loss of the induction motor is classified by factor, the current 2
The element is classified into an element proportional to the product, a factor proportional to the square of the voltage such as a snubber circuit loss of the power converter, and the like. An element proportional to the squared product of the current can be expressed by K _I ( _ids ² + _iqs ² ) (where K _I is a proportional constant). Also,
Element proportional to the product of voltage can be simplified representation in K _V (ωMi _ds) ² (where, K _V is a proportionality constant). On the other hand, since the generated torque τ _m is proportional to the product of the secondary magnetic flux φ _dr and the q-axis component _iqs of the primary current, the relationship of Expression (8) using the proportionality constant K _T holds.

[0012]

(Equation 7) Now, as can be seen from equation (8), there are countless combinations of φ _dr and i _qs for obtaining a certain value of generated torque. Therefore, in the device disclosed in Japanese Patent Publication No. 6-69307, the ratio of i _qs to φ _dr (= M _ds ), that is, the amplitude ratio | i _qs
^* / _Φdr ^* |, the combined loss K _I ( _ids ² + i
^{_{qs 2) + K V (ωMi}} ds) gives the condition for ² minimizes the following equation.

[0013]

(Equation 8) In other words, the condition that the loss of the induction motor is almost minimized is the amplitude ratio
| _iqs ^* / _φdr ^* | and the proportionality constants K _I and K _V are given by equation (9). Equation (10) and equation (1)
By solving 1), equations (12) and (13) are obtained.

[0014]

(Equation 9) Where: C: Amplitude ratio command According to equations (12) and (13), q of the secondary magnetic flux and the primary current
By controlling the axial component, the induction motor can be controlled with minimum loss.

[0015] The device in the process of generating the phi _dr ^* and i _qs ^* from the torque command tau _m ^*, the amplitude ratio | given by the function generator ^{_{16 | i qs * / φ dr}} *. That is, the function generator 16 performs the calculation of the equation (9) to generate the amplitude ratio command C. Then, 1 / K _T multiplying the coefficient unit 15 performs the calculation of Expression (12) by the divider 17 and the function generator 18, coefficient unit 1
5. The operation of the equation (13) is performed by the divider 19. As described above, the three-phase voltage commands v _us ^* , v _vs ^* , v _ws ^* are calculated,
Further, by a control method of controlling the actual primary voltages v _us , v _vs , and v _ws to follow the corresponding command values, it is possible to substantially minimize the combined loss of the induction motor and the power converter.

By the way, in such a control device, since the primary current command is calculated ignoring the iron loss resistance, the control performance of the secondary magnetic flux and the torque current is deteriorated due to the influence of ignoring the iron loss resistance. Things happen. If the control of the secondary flux and the torque current is not performed correctly, the amplitude ratio command C and the amplitude ratio | i _qs / φ _dr | simultaneously will not match, that does not match the generated torque tau _m torque command tau _m ^* Become.

As a control device for an induction motor that copes with the deterioration of control performance due to ignoring the iron loss resistance, that is, controls the secondary magnetic flux and the torque current without being affected by the iron loss resistance, as shown in FIG. There was one disclosed in Japanese Patent Application Laid-Open No. Hei 1-311884. In the figure, 1 to 10 and 13,
14 is the same as the conventional device shown in FIG. 15, and the description thereof is omitted. Further, 21 to 24 are operation units, 25 is a divider, 26 is a coefficient unit, and 27 and 28 are adders.

Next, the basic principle of the device will be described. The voltage / current equation of the induction motor on the dq axes is given by equation (14), as shown in the above-mentioned Japanese Patent Application Laid-Open No. 1-311884.

[0019]

(Equation 10) Where, v _ds : d-axis component of the primary voltage of the induction motor v _qs : q-axis component of the primary voltage of the induction motor R _m : iron loss resistance of the induction motor a: ratio of iron loss resistance of induction motor to frequency (= R _m /
ω) L _s : primary inductance value of the induction motor R _s : primary resistance value of the induction motor i _dr : d-axis component of the secondary current of the induction motor i _qr : q-axis component of the secondary current of the induction motor If the zero value of R _m at 14), consistent with the voltage-current equation of the induction motor in the case of ignoring the core loss. Next, when iron loss is considered, the d-axis component φ _dr and the q-axis component φ _qr of the secondary magnetic flux of the induction motor are given by Expression (15).

[0020]

(Equation 11) Further, when the secondary magnetic flux vector is made to coincide with the d-axis, the generated torque τ _m is given by Expression (16).

[0021]

(Equation 12) Here, p _{m is the number of} pole pairs. Equation (16) holds regardless of the presence or absence of iron loss. From equation (15), the presence of an iron loss resistance R _m, d-axis component phi _dr of secondary flux receives the q-axis current component i _qs, the effect of i _qr,
Conversely, the q-axis component φ _qr of the secondary magnetic flux is the d-axis current component _ids , _idr
It can be seen that it is affected by As a result, the generated torque τ
Equation (16) shows that _{m is} also affected by iron loss resistance.

Now, in the vector control method of the induction motor, the direction of the secondary magnetic flux vector is made to coincide with the d-axis or the q-axis.
That is, control is performed such that the d-axis component φ _dr or q-axis component φ _{qr of the} secondary magnetic flux is always zero. Then, next, it is examined whether vector control is possible even when iron loss is considered. In the vector control, the direction of the secondary magnetic flux vector is usually made to coincide with the d-axis. Therefore, the d-axis is also used as the direction of the secondary magnetic flux vector. First, equation (15) is replaced with equation (1)
By substituting the third and fourth lines in 4), equations (17) and (18) are obtained.

[0023]

(Equation 13) Therefore, in order to make the direction of the secondary magnetic flux vector coincide with the d-axis, the conditions for setting the q-axis component φ _qr to zero are given by the following equations (17) and (1).
Equations (19) and (20) are obtained from equation (8).

[0024]

[Equation 14] Here, the following exciting current component i ₀ and torque current component i _T are defined.

[0025]

(Equation 15) Then, from Expression (16), the generated torque τ _m is calculated by Expression (2)
It becomes like 3).

[0026]

(Equation 16) From equation (23), if i ₀ is controlled to be constant, d of the secondary magnetic flux
The axial component φ _dr is constant, and the generated torque is i
_It can be seen that it is proportional to _T. Note that the slip frequency ω _s at this time is given by the equation (2) from the equations (20), (21) and (22).
What is necessary is just to control according to 4).

[0027]

[Equation 17] As a result, the direction of the secondary magnetic flux vector coincides with the d-axis, and φ
_qr = 0 holds.

Incidentally, the defined currents i ₀ and i _T cannot be directly controlled. Therefore, the d-axis component i _ds and q-axis component i _qs of the primary current in the steady state, i ₀ and i
Investigate the relationship of _T. First, equation (15) is solved for i _ds and i _qs, further i _dr than the P = 0 Equation (19)
= 0, φ _qr = 0, and elimination of φ _dr and i _qr using equations (21) and (22) yields equations (25) and (26).

[0029]

(Equation 18) Therefore, the command values of i ₀ and i _T are set to i ₀ ^* and i _T ^* , respectively ^.
Then, using equations (25) and (26), the primary current d
The axis component command _ids ^* and the q-axis current component command _iqs ^* may be obtained. Incidentally, the iron loss resistance in issue the Hei 1-311884 gives R _m as a function of the to be proportional to 1.6 square of the primary frequency omega omega.

Next, the operation will be described. In FIG. 16, i _T / i ₀ is calculated by a divider 25 to obtain a coefficient unit 2
By multiplying R _r / M by 6, the value on the left side of equation (24) is obtained as follows:
In other words, to obtain a slip frequency ω _s. The first term on the right side of the equation (25) is calculated by the arithmetic
When the terms are calculated and the outputs of the calculators 23 and 24 are added by the adder 28, the value on the left side of the equation (25), that is, _ids ^* is obtained. Similarly, the first term on the right side of the equation (26) is calculated by the calculator 22, the second term is calculated by the calculator 21, and an adder 27
By adding the outputs of the computing units 21 and 22, the value on the left side of the equation (26), that is, i _qs ^* is obtained. Subsequent vector control operations operate in the same manner as the device shown in FIG.

[0031]

Since the conventional control device for an induction motor is constructed as described above, the control device for an induction motor as shown in FIG.
The calculation of _dr ^* and the q-axis component command i _qs ^* of the primary current is given by equation (8).
Based on Therefore, since equation (8) is an equation ignoring iron loss resistance, it is affected by ignoring iron loss resistance.
A situation occurs in which the secondary magnetic flux φ _dr does not match the secondary magnetic flux command φ _dr ^* , and the amplitude ratio command C does not match the amplitude ratio | _iqs ^* / φ _dr ^* |, and at the same time, the accuracy of torque control deteriorates. There were issues such as. In addition, the minimum loss condition is only an approximate solution and is not strict, and at the same time, since only the primary frequency ω is given as a function, there is a problem that it is impossible to cope with a case where the minimum loss condition changes due to other factors.

On the other hand, in the induction motor control device as shown in FIG. 16, the vector control law is obtained from the voltage / current equation of the induction motor in the steady state where P = 0 in equation (14). If the secondary magnetic flux command φ _dr ^* changes with time, a desired secondary magnetic flux φ _dr cannot be obtained,
As a result, there is a problem that a desired torque τ _m cannot be obtained. In addition, since the iron loss resistance is given as a function of the primary frequency ω, it is not assumed that the iron loss resistance fluctuates due to factors other than the primary frequency ω, and the iron loss resistance is determined by factors other than the primary frequency ω. If it fluctuates, it will be affected,
There were problems such as deterioration of the control performance of the secondary magnetic flux and the torque current.

The present invention has been made to solve the above-described problems. Even when the iron loss resistance fluctuates due to factors other than the primary frequency, the secondary magnetic flux is not affected by the iron loss resistance. It is an object of the present invention to provide an induction motor control device that controls a torque current and realizes driving of the induction motor while achieving a minimum loss condition.

[0034]

According to a first aspect of the present invention, there is provided a control apparatus for an induction motor, comprising: a d-axis component of a secondary magnetic flux based on a function of a torque command, a primary frequency of the induction motor, and a secondary magnetic flux of the induction motor. The command and the q-axis component command of the secondary current are calculated, and the d-axis component command of the secondary magnetic flux and the q-axis component command of the secondary current are converted into the d-axis component command and the q-axis component command of the primary current by the command conversion means. In addition, the control is performed so that the d-axis component and the q-axis component of the primary current of the induction motor match the d-axis component command and the q-axis component command of the primary current.

A control device for an induction motor according to a second aspect of the present invention provides a d-axis component command for a secondary magnetic flux and a secondary current for a secondary current based on a function of a torque command, a primary frequency of the induction motor and a secondary magnetic flux of the induction motor. Calculate the q-axis component command and calculate the secondary magnetic flux d
The axis component command and the q-axis component command of the secondary current are converted into the d-axis component command and the q-axis component command of the primary current by the current component command calculating means, and the d-axis component and the q-axis component of the primary current of the induction motor are changed. The primary current of the induction motor is controlled so as to match the d-axis component command and the q-axis component command of the primary current.

A control device for an induction motor according to a third aspect of the present invention provides a d-axis component command of a secondary magnetic flux and a secondary current of a secondary current based on a function of a torque command, a primary frequency of the induction motor and a secondary magnetic flux of the induction motor. Calculate the q-axis component command, calculate the d-axis component of the secondary magnetic flux of the induction motor based on the d-axis component and the q-axis component of the primary current calculated by the current component calculation circuit, and calculate by the current component calculation circuit. The primary frequency at which the q-axis component of the secondary magnetic flux of the induction motor becomes zero based on the d-axis component and the q-axis component of the primary current, the d-axis component of the secondary magnetic flux, and the rotation frequency detected by the detecting means. It is calculated.

According to a fourth aspect of the present invention, the control apparatus for an induction motor includes a d-axis component command for the secondary magnetic flux and a secondary current for the secondary current based on a function of the torque command, the primary frequency of the induction motor and the secondary magnetic flux of the induction motor. A q-axis component command is calculated, and based on the d-axis component and the q-axis component of the primary current calculated by the current component calculation circuit, the d-axis component of the secondary magnetic flux of the induction motor is calculated. The primary frequency at which the q-axis component of the secondary magnetic flux of the induction motor becomes zero is calculated based on the axis component and the q-axis component command of the secondary current output from the command generation means and the rotation frequency detected by the detection means. Things.

According to a fifth aspect of the present invention, there is provided the induction motor control device, wherein the d-axis component of the secondary magnetic flux and the secondary current are calculated based on the d-axis component and the primary frequency of the secondary magnetic flux calculated by the primary frequency calculating means. A correction amount for preventing mutual interference of the q-axis components is calculated, and based on the d-axis component command of the secondary magnetic flux and the q-axis component command of the secondary current output from the command generation means and the correction amount, the primary current is calculated. This is obtained by calculating a d-axis component command and a q-axis component command.

According to a sixth aspect of the present invention, there is provided a control apparatus for an induction motor, wherein the primary frequency and the d-axis of the secondary magnetic flux represent the relationship between the ratio of the q-axis component of the secondary current to the d-axis component of the secondary magnetic flux of the induction motor. Based on the component or the function of the command, and the relationship that the product of the d-axis component of the secondary magnetic flux and the q-axis component of the secondary current is proportional to the generated torque. This is obtained by calculating a current q-axis component command.

According to a seventh aspect of the present invention, there is provided a control apparatus for an induction motor, wherein the primary frequency and the d-axis of the secondary magnetic flux represent the relationship between the ratio of the q-axis component of the secondary current to the d-axis component of the secondary magnetic flux of the induction motor. The d-axis component command of the secondary magnetic flux is calculated based on the component or the function of the d-axis component command and the torque command, and the torque command is divided by the d-axis component of the secondary magnetic flux calculated by the primary frequency calculator. This is obtained by calculating a q-axis component command of the secondary current based on the value.

In the control apparatus for an induction motor according to the present invention, when the calculated d-axis component command of the secondary magnetic flux is larger than a predetermined maximum value or smaller than a predetermined minimum value, the secondary The d-axis component command of the magnetic flux is limited to the maximum value or the minimum value, and the q-axis component command of the secondary current is calculated according to the d-axis component command of the secondary magnetic flux.

According to a ninth aspect of the present invention, there is provided a control apparatus for an induction motor, wherein the primary frequency and the d-axis of the secondary magnetic flux represent the relationship between the ratio of the q-axis component of the secondary current to the d-axis component of the secondary magnetic flux of the induction motor. If the d-axis component command of the secondary magnetic flux calculated based on the component or function of the d-axis component command and the torque command is larger than a predetermined maximum value or smaller than a predetermined minimum value, The d-axis component command is limited to the maximum value or the minimum value, and the q-axis component command of the secondary current is determined based on a value obtained by dividing the torque command by the d-axis component of the secondary magnetic flux calculated by the primary frequency calculation means. Is calculated.

[0043]

BEST MODE FOR CARRYING OUT THE INVENTION

Embodiment 1 FIG. Hereinafter, embodiments of the present invention will be described. Figure 1 is a block diagram showing a control apparatus for an induction motor according to a first embodiment of the present invention. In the figure, 1 is an induction motor, 2 is the rotation frequency detector for detecting the electrical rotation frequency omega _r of the induction motor 1 (Detection means) 3 is an induction motor 1
Current detectors (detection means) 4 for detecting the primary currents i _vs , i _us are voltage-type inverters for driving the induction motor 1 at a variable frequency, which are the same as those of the prior art.

Reference numeral 30 denotes a torque command τ of the induction motor 1.
_m ^* , based on the torque command τ _m ^* , the primary frequency ω, and the function φ _dr of the secondary magnetic flux, the d-axis component command φ _dr ^{* of the} secondary magnetic flux and the q-axis component command i _{qr of the} secondary current A command generation circuit (command generation means) 31 for outputting ^* outputs a primary frequency ω and a secondary frequency ω _r based on the rotation frequency ω _r and the primary currents i _vs , i _us detected by the rotation frequency detector 2 and the current detector 3. The secondary magnetic flux function φ _dr is calculated and output to the command generation circuit 30, and the d-axis component command φ _dr ^{* of the} secondary magnetic flux output from the command generation circuit 30 and the q-axis component command i _{qr of the} secondary current are output.
^* Is the primary current d-axis component command i _ds ^* and q-axis component command i
_This is command conversion means for converting to _qs ^* , and comprises a current component command calculation circuit (current component command calculation means) 34 and a primary frequency calculation means including a primary frequency calculation circuit 35 and a current component calculation circuit 36. _{Reference numeral} 32 indicates that the d-axis component _ids and the q-axis component _{iqs of the} primary current of the induction motor 1 match the d-axis component command _ids ^* and the q-axis component command _iqs ^* converted by the current component command calculation circuit 34. The current control circuit 37 and the voltage-type inverter 4
It is composed of

Next, the operation will be described. First, the basic principle of the present invention will be described. When the direction of the secondary magnetic flux vector is made to coincide with the d-axis, it is understood from Expression (16) that there are countless combinations of φ _dr and i _qr for obtaining a certain value of generated torque τ _m . Then, next, φ _dr and i
_{The following} describes how to select the value of _qr to minimize the loss of the induction motor. Considering that φ _qr = 0 when the secondary magnetic flux vector coincides with the d-axis, Equation (1)
5) is solved for i _ds and i _qs , and in the steady state, P = 0 and i _dr = 0 from equation (19), then equation (27)
Is obtained.

[0046]

[Equation 19] However, l _r: secondary leakage inductance value of the induction motor (= L _r -M) Now, the effective power P _in is input to the induction motor is given by equation (28) in a known manner.

[0047]

(Equation 20) Therefore, the active power Pin _in the steady state is obtained. Since it is a steady state, P = 0, and the first and second lines of the equation (14) and the equation (2)
By substituting 7) into equation (28), equation (29) is obtained.

[0048]

(Equation 21) Next, the mechanical output P _out of the induction motor is given by equation (30) as is known.

[0049]

(Equation 22) Where ω _m is the mechanical rotation frequency of the induction motor,
The relationship with the electrical rotation frequency ω _r is represented by Expression (31).

[0050]

(Equation 23) Substituting equation (20) into equation (31) and eliminating ω _s ,
Equation (32) is obtained.

[0051]

(Equation 24) Therefore, when Equations (16) and (32) are substituted into Equation (30) to eliminate τ _m and ω _m , Equation (33) is obtained.

[0052]

(Equation 25) Then, from the equations (29) and (33), the loss P _loss generated in the induction motor is given by the equation (34).

[0053]

(Equation 26) Then, under the condition that the generated torque is constant, Expression (3)
Φ _dr and i that minimize the loss P _{lo ss} shown in 4)
_Find the combination of _qr . First, the condition that the generated torque is constant is expressed by Expression (35) using the proportionality constant K from the relationship of Expression (16).

[0054]

[Equation 27] Then, substituting equation (35) into equation (34) and eliminating φ _dr gives equation (36).

[0055]

[Equation 28] Then, the loss P _loss is minimized when the condition that the value obtained by differentiating the right side of Expression (36) with _iqr ² becomes zero is satisfied. Therefore, φ _dr and i obtained from this condition and equation (35)
The relationship of _qr is given by equation (37).

[0056]

(Equation 29) That is, the minimum loss operation of the induction motor can be realized by controlling φ _dr and i _qr according to the torque command so that the amplitude ratio between φ _dr and i _qr satisfies Expression (37). Expression (14)
Represents the voltage / current equation of the induction motor on the rotating coordinate axis as described above. Accordingly, when the induction motor is accelerated / decelerated with a constant torque, the differential term of equation (14) becomes zero, and the minimum loss operation can be realized by equation (37).

Next, a description will be given of iron loss resistance R _m. As an example, FIG. 14 shows actually measured graph of iron loss resistance R _m of the induction motor of 1.5 kW. In FIG. 14, the vertical axis is the iron loss resistance R _m [Ω], and the horizontal axis is a value obtained by converting the exciting current into a secondary magnetic flux and normalizing the same with a rated value.
Iron loss resistance in issue the Hei 1-311884 is to be proportional to approximately 1.6 square of the primary frequency omega, and given by a function of the R _m omega. In practice, however, at the same time the series core-loss resistance R _m as shown in FIG. 14 is a function of the primary frequency omega, the function of the exciting current, i.e. seen is also a function of the secondary flux.

As in the conventional example shown in FIG.
In the case of the control device to keep the ₀ constant, variations in R _m may be considered only for omega. However, as the amplitude ratio of phi _dr and i _qr satisfies the equation (37), when controlling the phi _dr and i _qr according to the torque command, the secondary magnetic flux phi _dr is necessary to change depending on the torque And therefore the excitation current changes accordingly. In other words, in this case, the iron loss resistance changes due to the influence of the change in the exciting current other than the change in the primary frequency ω. Therefore, the iron loss resistance may be given by a function of ω and φ _dr .

When the induction motor is driven with the minimum loss, that is, when the secondary magnetic flux command φ _dr ^* and the secondary current command i _qr ^* are given according to the equation (37), the equation between φ _dr ^* and i _qr ^* is obtained. (3
8) and (39) hold.

[0060]

[Equation 30] When driving the induction motor by changing the secondary magnetic flux, R
_m and a are functions of the secondary magnetic flux φ _dr and the primary frequency ω,
As a result, the right side of equation (39) is a function of φ _dr and ω.

Next, a specific operation of the first embodiment will be described. The command generation circuit 30 generates a secondary magnetic flux command φ _dr ^* that can drive the induction motor 1 with minimum loss and a secondary current based on the secondary magnetic flux φ _dr and the primary frequency ω obtained from the command conversion unit 31. q-axis component command (secondary current command)
Generates i _qr ^* . Primary frequency arithmetic circuit 35, the primary current obtained from the rotation frequency detector 2 and the electrical rotational frequency omega _r obtained from the current component calculation circuit 36 d-axis component i _ds
And primary frequency based on the q-axis component i _qs omega secondary flux φ
Calculate _dr . Thus, the primary frequency calculating means 33
Generates a secondary magnetic flux φ _dr and a primary frequency ω based on the primary currents i _vs , i _us obtained from the current detector 3 and the electric rotation frequency ω _r obtained from the rotation frequency detector 2.

The current component command calculation circuit 34 calculates the secondary magnetic flux φ _dr and the primary frequency ω calculated by the primary frequency calculation means 33 and the secondary magnetic flux command φ _dr ^* output from the command generation circuit 30 ^.
When generating a primary current of the d-axis component command i _ds ^* and q-axis component command i _qs ^* based on the secondary current command i _qr ^*. As described above, the command conversion unit 31 including the primary frequency calculation unit 33 and the current component command calculation unit 34 converts the secondary magnetic flux command φ _dr ^* and the secondary current command i _qr ^* output by the command generation circuit 30 into the primary current. It is converted into a d-axis component command i _ds ^* and a q-axis component command i _qs ^* . The control unit 32 controls the primary current so that the d-axis component _ids and the q-axis component _iqs follow the primary current d-axis component command _ids ^* and the q-axis component command _iqs ^* .

FIG. 2 is a block diagram showing a command generation circuit 30 of the control device for the induction motor according to the first embodiment.
In the figure, 38 and 39 are coefficient units, 40 and 41 are dividers, and 42 is a function generator. Function generator 42 taking into account the variation of the core-loss resistance R _m from the primary frequency ω and the secondary magnetic flux phi _dr, equation (38), a table of data stored in the operation, or the memory circuit based on (39) See | i _qr
^* / Φ _dr ^* | The coefficient unit 38 outputs the torque command τ _m ^*
Multiplied by the 1 / p _m outputs -φ _dr ^* · i _qr ^* value, the divider 40 is -φ _dr ^* · i _qr ^* of the value ^{_{| i qr * / φ dr *}} | divided by, phi Outputs _dr ^{* 2} (or -φ _dr ^{* 2} ). The function generator 18 calculates the square root of the absolute value of the output of the divider 40 to generate φ _dr ^* . Also, the divider 41 outputs a divided by i _qr ^* values of φ _{d r} ^* · i _qr ^* obtained by the coefficient multiplier 39 in phi _dr ^*.

In the conventional control device, the minimum loss condition is given by a function of only the primary frequency. However, as mentioned above,
Since the minimum loss condition changes not only with the primary frequency ω but also with the secondary magnetic flux φ _dr , it is difficult to give the minimum loss condition as a function of only the primary frequency ω when performing control so that φ _dr changes. is there. However, in the configuration shown in FIG. 2, even when the secondary magnetic flux phi _dr ^* core-loss resistance R _m changes due to fluctuates, the function generator 42 is not only the primary frequency ω also secondary magnetic flux phi _dr As a reference, since the relation of the ratio of the q-axis component of the secondary current to the d-axis component of the secondary magnetic flux of the induction motor is output, the secondary magnetic flux command φ _dr ^* satisfying the minimum loss condition
And the secondary current command _iqr ^* .

In the current component command calculating means 34, the secondary magnetic flux φ _dr and the q of the secondary current are calculated based on the secondary magnetic flux φ _dr and the primary frequency ω calculated by the primary frequency calculating means 33.
A correction amount for preventing mutual interference of the axial components _iqr is calculated, and d of the secondary magnetic flux output from the command generation means 30 is calculated.
Calculating a i _ds ^* and i _qs ^* based on the q-axis component command i _qr ^* and the correction amount of the axial component command phi _dr ^* and secondary currents. FIG. 3 is a configuration diagram showing a current component command calculation circuit 34 of the control device for an induction motor according to the first embodiment, in which 43 to 46 are function generators, 47 and 48 are calculation units,
49 to 51 are multipliers, 52 is a coefficient unit, 53 is an adder, 5
4 is a subtractor. As described above, the value of iron loss resistance R _m is also a function of the secondary flux phi _dr well primary frequency omega.
In addition, when iron loss resistance is considered, φ _dr , i _qr and i _ds , i
_From Equations (15) and (19), it can be seen that Equation (40) has a relationship with _qs .

[0066]

[Equation 31] ^{_{However, T r2: Tr + a 2}} Rr / M formula from (40) φ _dr and i _ds disturbance a exerted by the iron loss between the
l _r / (M ² + a ² ) · i _{q r} . Similarly, i _qr and i
Disturbance a (1 + l _r P / R _r ) due to iron loss during _qs /
It can be seen that (M ² + a ² ) · φ _dr exists. By adding a correction amount for the d-axis component command i _ds ^* and q-axis component command i _qs ^* these disturbances minute to prevent mutual interference of phi _dr and i _qr of the primary current, phi _dr and i _qr Can be prevented from mutual interference. Then, φ _dr ^* , i _qr ^* is substituted for φ _dr , i _{qr on} the right side of equation (40), and equation (4)
1), (42) in i _ds ^*, i _qs ^* give the without being affected by the mutual interference phi _dr, i _qr is controlled.

[0067]

(Equation 32) a (= R _m / ω) is a function of the secondary magnetic flux φ _dr and the primary frequency ω for the reasons described above. Therefore, the function generator 43 refers to the table of data stored in the memory circuit based on the primary frequency ω and the secondary magnetic flux φ _dr to obtain a (= g (φ
_dr , ω)).

The function generator 44 generates _Tr2 based on a output from the function generator 43, and similarly, the function generator 4
5, each of the function generator ^{46 a / (M + 2 a} 2),
^{_{(ML r + a 2) /}} (M 2 + a 2) to generate. M calculator 47 includes a differential element to ^{_{φ dr * (1 + T r2}} P) /
(M ² + a ²⁾ performs an operation of similarly calculator 48 phi _dr
^A (1 + l _r / R _r P) / (M ²
+ A ² ). The adder 53 that calculates the sum of the output of the arithmetic unit 47 and the output of the coefficient unit 52 that multiplies the output of the multiplier 49 by l _r outputs the right side of Expression (41). Further, a subtractor 54 that calculates the difference between the output of the multiplier 50 and the output of the multiplier 51 outputs the right side of Expression (42).

In the conventional control device shown in FIG. 16, a value proportional to the 1.6th power of the primary frequency ω is given as the value a including the iron loss resistance. However, when the secondary flux φdr changes, since the iron loss resistance varies actually despite changes the correction amount for preventing the influence of mutual interference of phi _dr and i _qr, the iron loss resistance An accurate correction amount could not be given because the function was given only by the primary frequency ω. However, since the correct correction amount can be calculated by outputting the value a including the iron loss resistance value while referring to φ _dr and ω as in the function generator 43, it is possible to calculate φ _dr and i
The d-axis component command and the q-axis component command of the primary current can be obtained without being affected by the mutual interference of _qr .

FIG. 4 is a block diagram showing a primary frequency calculation circuit 35 of the control device for an induction motor according to the first embodiment.
5 to 58 are function generators, 59 to 64 are multipliers, and 65 to 6
7 is a coefficient unit, 68 and 69 are subtractors, 70 and 71 are adders, 72 is a divider, 73 is an integrator, and 74 is a (= R _m /
ω). Equation (15) and φ _qr =
By substituting 0 into equation (19), the following equation is obtained.

[0071]

[Equation 33] However, T _r1: Since ^{_{T r + a 2 / L r}} R r actual secondary flux can not be detected, from equation (43) phi
_What is necessary is to estimate _dr . On the other hand, equation (44) is obtained from equation (15) and φ _qr = 0.

[0072]

(Equation 34)Actual secondary current i as well as secondary magnetic flux_qrCan't detect
From equation (44), i _qrIs estimated, the following equation (20) is obtained.
Frequency ω without being affected by iron loss resistance_s Calculate
can do.

The function generator 74 outputs the value of a (= R _m / ω) based on φ _dr and ω, similarly to the function generator 43 described above. The multiplier 63 outputs M + a ² /
Multiplying the value of L _r and i _ds, it outputs the _{^{(M + a 2 / L r}} ) i ds. On the other hand, the coefficient unit 66 calculates a
_Multiply i _qs by l _r / L _r and output al _r / L _r · i _qs As is well known, the operation of the first-order lag system can be realized by a closed loop including an integrator. Subtractor 69, an integrator 73, the function generator 58, multiplier 64, a calculation of ^{_{1 / [1+ (L r 2}} + a 2) P / L r R r] of the first-order lag with respect to the output of the adder 71 Do. The output of the adder 71 is (M + a ² / L
because it is _{r) i ds + al r /} L r · i qs, equation (43)
Is output from the multiplier 64.

The function generators 55 and 56 have a / (L
_r ² + a ² ) and (ML _r + a ² ) / (L _r ² + a ² ). Therefore, the function generators 55 and 56 and the multipliers 59 and 6
The right side of equation (44) is calculated by 1, 62, coefficient unit 65, subtractor 68, and adder 70. That is, the adder 70 outputs the secondary current _iqr . And -R _r multiplied by the coefficient multiplier 67 by a divider 72 is calculated the formula (20) right side, coefficient unit 67 the slip frequency omega _s outputs. Then, by adding the slip frequency omega _s and electrical rotational frequency omega _r by the adder 13 to obtain a primary frequency omega. Since the function generator 74 outputs the value a including the iron loss resistance based on the secondary magnetic flux and the primary frequency, it is possible to accurately calculate the secondary magnetic flux and the primary frequency even when the secondary magnetic flux changes. is there. Thus, the primary frequency calculation circuit 35 generates the secondary magnetic flux φ _dr and the primary frequency ω.

FIG. 5 is a block diagram showing a current component calculation circuit 36 of the control device for an induction motor according to the first embodiment. In FIG. 5, reference numeral 5 denotes a coordinate converter, and 14 denotes an integrator. They are the same. The integrator 14 integrates the primary frequency ω obtained from the primary frequency calculation circuit 35 to generate a phase θ. The coordinate converter 5 includes the phase θ and the current detector 3
Then, a d-axis component _ids and a q-axis component _iqs of the primary current are generated based on the primary currents i _us and i _vs obtained from. As described above, the current component calculation circuit 36 generates the d-axis component _ids and the q-axis component _iqs of the primary current based on the primary currents i _us , i _vs and the primary frequency ω.

FIG. 6 is a block diagram showing a current control circuit 37 of the control device for the induction motor according to the first embodiment.
In the figure, 6 and 7 are subtractors, 8 and 9 are controllers, 10 is a coordinate converter, and 14 is an integrator, which is the same as the conventional device. D of the primary current obtained from the command conversion means 31
The subtractor 6 outputs the difference between the axis component command _ids ^* and the d-axis component _ids , and the controller 8 amplifies the difference to generate a primary voltage d-axis component command _vds ^* . Similarly, the q-axis component command i _qs ^{* of the} primary current obtained from the command conversion means 31 and the q-axis component i _qs
Is output from the subtracter 7, and the controller 9 amplifies the deviation to generate a q-axis component command v _qs ^* of the primary voltage. Integrator 1
4 integrates the primary frequency ω obtained from the command conversion means 31 to generate a phase θ. The coordinate converter 10 outputs a primary voltage d-axis component command v _ds ^* and a q-axis component command v _qs based on the phase θ.
^* _Is converted into three-phase voltage commands v _us ^* , v _vs ^* , v _ws ^* .
As described above, the d-axis component and the q-axis component of the primary current follow the d-axis component command and the q-axis component command of the primary current, respectively.

As described above, in the first embodiment, even when the iron loss resistance fluctuates due to the change of the secondary magnetic flux, the d-axis component command of the secondary magnetic flux and the q-axis component command of the secondary current are given. The d-axis component of the secondary magnetic flux and the q-axis component of the secondary current can be controlled so as to follow.

Embodiment 2 In the first embodiment, the primary frequency calculation means 33 obtains the q-axis component i _qr of the secondary current based on the primary currents i _vs , i _us and the rotation frequency ω _r. , I _qr, a secondary current q-axis component command i _qr ^* may be used. 7, the same reference numerals as those in the first embodiment denote the same or corresponding parts, and a description thereof will not be repeated. 31b is command conversion means, 3
3b is a primary frequency calculating means, and 35b is a primary frequency calculating circuit. Primary frequency arithmetic circuit 35b is of primary current d-axis component i _ds, q-axis component i _qs of the primary current, secondary flux phi _dr on the basis of the q-axis component command i _qr ^* and electrical rotation frequency omega _r of the secondary current And a primary frequency ω.

As described above, the primary frequency calculating means 33b
Primary currents i _vs , i _us detected by the current detector 2
D-axis component _{ids of the} primary current of the induction motor 1 based on
And a current component calculation circuit 36 for calculating the q-axis component i _qs ,
The d-axis component φ _dr of the secondary magnetic flux of the induction motor 1 is calculated based on the d-axis component _ids and the q-axis component _iqs of the primary current calculated by the current component calculation circuit 36, and the secondary magnetic flux is calculated. Of the induction motor based on the d-axis component φ _dr of the above, the q-axis component command i _qr ^{* of the} secondary current output from the command generation means 30, and the rotation frequency ω _r detected by the rotation frequency detector 3. It comprises a primary frequency calculation circuit 35b for calculating a primary frequency ω at which the q-axis component φ _dr of the secondary magnetic flux becomes zero.

FIG. 8 is a block diagram showing a primary frequency calculation circuit 35b of the control device for an induction motor according to the second embodiment. In the figure, reference numeral 13 denotes an adder, which is the same as the conventional device. 80 is a magnetic flux calculation circuit, 81 is a divider, and 82 is a coefficient unit. The magnetic flux calculation circuit 80 calculates the secondary magnetic flux φ _dr based on the d-axis component _ids and the q-axis component _iqs of the primary current obtained from the current component calculation circuit 36. The divider 81 converts the secondary current command i _qr ^* into the magnetic flux calculation circuit 8.
Divide by 0 output φ _dr . Then, the slip frequency ω _s is obtained by multiplying the output of the divider 81 by −R _r by the coefficient unit 82. The adder 13 has an electric rotation frequency ω
by adding the _r and _the slip frequency ω _s to output a primary frequency ω. As described above, the primary frequency calculation circuit 35b generates the secondary magnetic flux φ _dr and the primary frequency ω.

FIG. 9 is a block diagram showing a magnetic flux calculation circuit 80 of the control device for an induction motor according to the second embodiment.
In the figure, the same reference numerals as those in the first embodiment denote the same or corresponding parts, and a description thereof will be omitted. The configuration of FIG.
In this embodiment, the function of the slip frequency calculation is omitted from the configuration of the primary frequency calculation circuit 35 of the first embodiment shown in FIG. 8 and 9, the primary frequency ω can be obtained without calculating the secondary current i _qr from the primary current, and the secondary magnetic flux φ _dr according to the equation (43) can be calculated. .

Embodiment 3 In the first and second embodiments, the current component command calculation circuit 34 calculates the primary current d.
Although as previously mentioned for calculating the axial component command i _ds ^* and q-axis component command i _qs ^*, as shown in FIG. 10, based on the primary frequency secondary flux calculated by the calculating means 33 phi _dr and primary frequency ω Then, a correction amount for preventing mutual interference between φ _dr and the q-axis component _iqr of the secondary current is calculated, and the secondary magnetic flux command φ _dr ^* and the secondary magnetic flux φ output from the command generation circuit 30 are calculated.
based on the deviation and the q-axis component command i _qr ^* and the correction amount of the secondary current of _dr i _ds ^* and i _qs ^* may be calculated.

In FIG. 10, the same reference numerals as in the first embodiment denote the same or corresponding parts, and a description thereof will not be repeated. 34b is a current component command calculation circuit (current component command calculation means), 83 is a subtractor, and 84 is a controller. As described above, from equation (40), there is a disturbance al _r / (M ² + a ² ) · i _qr caused by iron loss between φ _dr and i _ds , and similarly, i _qr
And i _qs , the disturbance a (1 + l _r P / R) caused by iron loss
_r ) / (M ² + a ² ) ・ φ _dr Therefore, i _ds ^*, i _qs ^* each formula (45), given by (46), a disturbance of iron loss resistance exerts i.e. phi _dr and without the interference of the i _qr φ _dr, i _qr are obtained .

[0084]

(Equation 35) However, K _fp: proportional gain K _fi: integral gain s: Laplace operator expression (45), by performing i _ds ^*, i _qs ^* calculation according (46), phi _dr, i _qr is phi _dr ^*, i Follow _qr ^* . In the equation (45), the first term on the right side is a magnetic flux control calculation term, and the magnetic flux response can be adjusted by designing the gain.

In mounting, when _ids does not follow _ids ^{* due} to the limitation of the current capacity of voltage source inverter 4, secondary magnetic flux _φdr does not follow secondary magnetic flux command _φdr ^* . In the current component command calculating means 34 as described in the first embodiment, the correction amount for preventing the mutual interference is calculated based on φ _dr ^* .
_ds ^* and _iqs ^* . Further, when the torque command changes stepwise, there is a problem that the differential calculation of the secondary magnetic flux command cannot be performed. However, equation (4)
5) (by computing according to 46), and at the same time can be controlled to φ _dr ^* φ _dr without differential operation follows the phi _dr ^*, uses phi _dr the calculation of the correction amount since, the correction amount even when phi _dr does not follow the phi _dr ^* is accurately calculated.

The subtracter 83 outputs a deviation between the secondary magnetic flux command φ _dr ^* and the secondary magnetic flux φ _dr, and the controller 84 amplifies the deviation to calculate the first term on the right side of the equation (45). a / (M ²
+ A ² ), a function generator 45 for generating the value of
The second term of Expression (45) is calculated by the coefficient unit 52, and _ids ^* expressed by Expression (45) is generated by the adder 55.
Similarly, the equation (46) is obtained by the multiplier 50 and the function generator 45.
The second term on the right side is calculated by a function generator 46 and a multiplier 51 which calculate the first term to generate a value of (ML _r + a ² ) / (M ² + a ² ). Generate the represented _iqs ^* . As described above, the d-axis component command _{ids of the} primary current is set so that the secondary magnetic flux φ _dr follows the secondary magnetic flux command φ _dr ^* without being affected by the mutual interference between φ _dr and i _qr.
^{* And} q-axis component command i _qs ^* can be generated.

Embodiment 4 In the first to third embodiments, the command generation circuit 30 calculates φ _dr ^* and i _qr ^* . However, the secondary magnetic flux φ _dr of the induction motor 1 is calculated.
Based on the primary frequency representing the relationship of the ratio of the secondary current i _qr and the function of the d-axis component of the secondary magnetic flux, a relationship that the product of the secondary flux phi _dr and secondary current i _qr is proportional to the torque command for hand,
At the same time as calculating the secondary magnetic flux command φ _dr ^* , a q-axis component command i _qs ^* of the secondary current is calculated based on a value obtained by dividing the torque command by the secondary magnetic flux φ _dr calculated by the primary frequency calculating means. May be. FIG. 11 shows the fourth embodiment.
FIG. 2 is a configuration diagram showing a command generation circuit (command generation means) 30b of the control device for an induction motor according to the first embodiment. In the figure, the same reference numerals as those in the first embodiment denote the same or corresponding parts, and a description thereof will be omitted. 41b is a divider for dividing the output of the coefficient unit 39 by the secondary magnetic flux φ _dr .

[0088] If the secondary magnetic flux φ _dr ^* to the secondary magnetic flux φ _dr does not ^{_{follow, τ m * = φ dr *}} · i qr * of the relationship is not established. Therefore, the command generation circuit shown in FIG.
A situation where the generated torque did not follow the torque command occurred.
However, as shown in FIG. 11, the secondary current command i _qr
^* To impart to the torque command is proportional to a value obtained by dividing the secondary magnetic flux phi _dr, phi even _{if dr} is not follow the phi _dr ^* tau _m ^* =
Since the relationship of φ _dr · i _qr ^* holds, a desired torque can be obtained regardless of the response of φ _dr .

Embodiment 5 In the first to fourth embodiments, the secondary magnetic flux command φ _dr satisfying the minimum loss condition is used.
^* And the calculation of the secondary current command i _qr ^* have been described. Further, when the calculated secondary magnetic flux command φ _dr ^* is larger than a predetermined maximum value or smaller than a predetermined minimum value, The d-axis component command φ _dr ^* of the secondary magnetic flux is limited to the maximum value or the minimum value, and the secondary current command i _qr ^* is calculated according to the d-axis component command φ _dr ^{* of the} secondary magnetic flux. Good. Thereby, the driving efficiency and the speed responsiveness can be improved. FIG. 12 shows the fifth embodiment.
FIG. 2 is a configuration diagram showing a command generation circuit 30c of the control device for an induction motor according to the first embodiment. 90 is a limiting circuit.

Except that a limiting circuit 90 is provided on the output side of the function generator 18, it is almost the same as the first embodiment.
Mainly, the limiting circuit 90 will be described. First, when the limiting circuit 90 is not provided as in the first embodiment, the secondary magnetic flux command φ _dr ^* can take a large value as long as the expression (38) is satisfied. Although the amplitude can be increased, if the amplitude of the secondary magnetic flux is increased to a certain degree or more, magnetic saturation occurs, so that there is a problem that high-precision torque control performance cannot be obtained.

The d-axis component φ _dr of the secondary magnetic flux is given by the following equation (4).
As is clear from FIG. 0), the secondary magnetic flux responds to the d-axis component _ids of the primary current with a primary delay characteristic.
When the shaft component phi _dr becomes too small and the need to increase rapidly generated torque occurs, d-axis component of the primary current i _ds
, The response of the d-axis component φ _dr of the secondary magnetic flux is slow, so that there is a problem that the time required to obtain the generated torque as instructed is long. Therefore, in the fifth embodiment, in order to solve the above-described problem, when the d-axis component command φ _dr ^{* of the} secondary magnetic flux calculated by the function generator 18 is larger than a predetermined maximum value, The d-axis component command φ _dr ^* of the secondary magnetic flux is limited to the maximum value, and if smaller than a predetermined minimum value, the d-axis component command φ _dr ^{* of the} secondary magnetic flux is restricted ^.
Is limited to the minimum value, thereby limiting the magnitude of the amplitude of the d-axis component φ _dr of the secondary magnetic flux.

Embodiment 6 FIG. FIG. 13 is a block diagram showing a command generation circuit 30d of the control device for an induction motor according to the sixth embodiment. In the figure, the same reference numerals as those in the fifth embodiment denote the same or corresponding parts, and a description thereof will be omitted. I do. In the fifth embodiment, the restriction circuit 90 is provided on the output side of the function generator 18 in the command generation circuit 30, but similarly, the restriction circuit 90 is limited to the output side of the function generator 18 in the command generation circuit 30b shown in the fourth embodiment. A circuit 90 may be provided. Thereby, the driving efficiency and the speed responsiveness can be improved.

Embodiment 7 FIG. When the secondary magnetic flux φ _dr is controlled normally, the secondary magnetic flux φ _dr matches the command value φ _dr ^* . Moreover, since the substantially proportional in the steady state, the d-axis component i _ds of secondary flux phi _dr and the primary current, the iron loss resistance R
_m is a _simplified function of _ids . Accordingly, the had been using a secondary magnetic flux phi _dr and primary frequency ω as input of the function generator 42,43,74 In Modes 1 6 embodiment, phi secondary flux command instead of _dr phi _dr ^*, Either the d-axis component _ids of the primary current or the d-axis component command _ids ^* of the primary current may be used.

Embodiment 8 FIG. In the above-described embodiment, the configuration configured by hardware has been described. However, the configuration may be realized by software processing using a microcomputer.

[0095]

As described above, according to the first aspect of the present invention, the command converter converts the d-axis component command of the secondary magnetic flux and the q-axis component command of the secondary current into the d-axis component command of the primary current. And a q-axis component command, and the control means converts the d-axis component and the q-axis component of the primary current of the induction motor into d of the primary current.
Since it is configured to match the axis component command and the q axis component command, even if the iron loss resistance fluctuates due to the change of the secondary magnetic flux, the d axis component command of the secondary magnetic flux and the q axis of the secondary current The d-axis component of the secondary magnetic flux and the q-axis component of the secondary current are controlled so as to follow the component command, and there is an effect that the induction motor can be controlled without being affected by the fluctuation of the iron loss resistance.

According to the second aspect of the present invention, the primary frequency calculating means calculates the d-axis component and the primary frequency of the secondary magnetic flux based on the primary current, and the current component command calculating means calculates the secondary magnetic flux. The d-axis component command and the q-axis component command of the secondary current are converted into the d-axis component command and the q-axis component command of the primary current, and the d-axis component and the q-axis component of the primary current of the induction motor are controlled by the control means. D-axis component command of current and q
Since it is configured to match the axis component command, even if the iron loss resistance fluctuates due to a change in the secondary magnetic flux, it follows the d-axis component command of the secondary magnetic flux and the q-axis component command of the secondary current. Thus, the d-axis component of the secondary magnetic flux and the q-axis component of the secondary current are controlled, and there is an effect that the induction motor can be controlled without being affected by the fluctuation of the iron loss resistance.

According to the third aspect of the present invention, the primary frequency calculating means in the second aspect calculates the d-axis component and the q-axis component of the primary current based on the primary current by the current component calculating circuit, and The frequency arithmetic circuit calculates the q of the secondary magnetic flux of the induction motor based on the d-axis component and the q-axis component of the primary current and the rotation frequency detected by the detection means.
Since the primary frequency at which the axial component becomes zero and the d-axis component of the secondary magnetic flux of the induction motor are calculated, even if the iron loss resistance fluctuates due to a change in the secondary magnetic flux, the secondary frequency is calculated. The d-axis component of the secondary magnetic flux and the q-axis component of the secondary current are controlled so as to follow the d-axis component command of the magnetic flux and the q-axis component command of the secondary current, without being affected by the fluctuation of the iron loss resistance. There is an effect that the induction motor can be controlled.

According to the fourth aspect of the present invention, the primary frequency calculating means according to the second aspect of the present invention uses the secondary magnetic flux of the induction motor based on the d-axis component and the q-axis component of the primary current calculated by the current component calculating circuit. Of the induction motor based on the d-axis component of the secondary magnetic flux, the q-axis component command of the secondary current output from the command generation means, and the rotation frequency detected by the detection means. Since the primary frequency calculation circuit for calculating the primary frequency at which the q-axis component of the secondary magnetic flux becomes zero is provided, the primary frequency can be calculated without converting the q-axis component of the primary current into the q-axis component of the secondary current. The calculation can be performed, and as a result, there is an effect that the configuration of the primary frequency calculation means is simplified.

According to the fifth aspect of the present invention, the current component command calculating means according to any one of the second to fourth aspects is configured such that the current component command calculating means is controlled based on the d-axis component of the secondary magnetic flux calculated by the primary frequency calculating means and the primary frequency. A correction amount for preventing mutual interference between the d-axis component of the secondary magnetic flux and the q-axis component of the secondary current is calculated, and the d-axis component command of the secondary magnetic flux output from the command generation means and the q-axis of the secondary current Since the configuration is such that the d-axis component command and the q-axis component command of the primary current are calculated based on the component command and the correction amount, even when the iron loss resistance fluctuates due to a change in the secondary magnetic flux. There is an effect that the response characteristics of the secondary magnetic flux and the generated torque are improved without being affected by the influence.

According to the sixth aspect of the present invention, the command generation means according to any one of the first to fifth aspects represents the relationship between the ratio of the q-axis component of the secondary current to the d-axis component of the secondary magnetic flux of the induction motor. Primary frequency and d-axis component of secondary magnetic flux or d-axis component command function, d-axis component of secondary magnetic flux and q of secondary current
Based on the relationship that the product of the shaft components is proportional to the generated torque,
Since the d-axis component command of the secondary magnetic flux and the q-axis component command of the secondary current are configured to be calculated, the d-axis component command of the secondary magnetic flux and the q of the secondary current that minimize the operating loss of the induction motor The shaft component command is obtained, and the operation loss of the induction motor can be minimized.

According to the seventh aspect of the present invention, the command generating means according to any one of the second to fifth aspects represents the relationship between the ratio of the q-axis component of the secondary current to the d-axis component of the secondary magnetic flux of the induction motor. Based on the function of the primary frequency and the d-axis component of the secondary magnetic flux or the d-axis component command, and the product of the d-axis command component of the secondary magnetic flux and the q-axis component of the secondary current being proportional to the torque command, Since the d-axis component command of the secondary magnetic flux and the q-axis component command of the secondary current are configured to be calculated, the d-axis component command of the secondary magnetic flux and the q of the secondary current that minimize the operating loss of the induction motor There is an effect that the shaft component command can be obtained and the response of the generated torque can be improved.

According to the eighth aspect of the present invention, the command generation means according to any one of the second to fifth aspects is adapted to determine whether the calculated d-axis component command of the secondary magnetic flux is larger than a predetermined maximum value or a predetermined minimum value. If smaller, the d-axis component command of the secondary magnetic flux is limited to the maximum value or the minimum value, and the q-axis component command of the secondary current is calculated according to the d-axis component command of the secondary magnetic flux. As a result, the occurrence of magnetic saturation due to the amplitude of the secondary magnetic flux being too large is suppressed, and even if the torque is insufficient, the amplitude of the secondary magnetic flux is maintained within a range where the torque insufficiency can be resolved immediately, and the induction is maintained. This has the effect of improving the response speed of the motor and preventing the occurrence of magnetic saturation.

According to the ninth aspect of the present invention, the command generation means according to any one of the second to fifth aspects is adapted to determine whether the calculated d-axis component command of the secondary magnetic flux is larger than a predetermined maximum value or a predetermined minimum value. If smaller, the d-axis component command of the secondary magnetic flux is limited to the maximum value or the minimum value, and the torque command is divided by the d-axis component of the secondary magnetic flux calculated by the primary frequency calculator. Since the configuration is such that the q-axis component command of the secondary current is calculated on the basis of this, the occurrence of magnetic saturation due to the amplitude of the secondary magnetic flux becoming too large is suppressed. Within the range that can be eliminated, the amplitude of the secondary magnetic flux is maintained, good torque response is obtained, the response speed of the induction motor can be improved, and the effect of preventing the occurrence of magnetic saturation can be obtained. .

[Brief description of the drawings]

FIG. 1 is a configuration diagram showing a control device for an induction motor according to a first embodiment of the present invention.

FIG. 2 is a configuration diagram showing a command generation circuit according to the first embodiment of the present invention.

FIG. 3 is a configuration diagram illustrating a current component command calculation circuit according to Embodiment 1 of the present invention;

FIG. 4 is a configuration diagram illustrating a primary frequency calculation circuit according to Embodiment 1 of the present invention;

FIG. 5 is a configuration diagram showing a current component calculation circuit according to the first embodiment of the present invention.

FIG. 6 is a configuration diagram showing a current control circuit according to the first embodiment of the present invention.

FIG. 7 is a configuration diagram showing a control device for an induction motor according to a second embodiment of the present invention.

FIG. 8 is a configuration diagram showing a primary frequency calculation circuit according to a second embodiment of the present invention.

FIG. 9 is a configuration diagram showing a magnetic flux calculation circuit according to a second embodiment of the present invention.

FIG. 10 is a configuration diagram showing a current component command calculation circuit according to a third embodiment of the present invention.

FIG. 11 is a configuration diagram showing a command generation circuit according to a fourth embodiment of the present invention.

FIG. 12 is a configuration diagram showing a command generation circuit according to a fifth embodiment of the present invention.

FIG. 13 is a configuration diagram showing a command generation circuit according to a sixth embodiment of the present invention.

FIG. 14 is a characteristic diagram showing a relationship between a secondary magnetic flux and a primary frequency of the induction motor and an iron loss resistance of the induction motor.

FIG. 15 is a block diagram showing a conventional control device for an induction motor.

FIG. 16 is a block diagram showing a conventional control device for an induction motor.

[Explanation of symbols]

1 induction motor, 2 rotation frequency detector (detection means),
3 Current detector (detection means), 30, 30b-30d
Command generation circuit (command generation means), 31, 31b command conversion means, 32 control means, 33, 33b primary frequency calculation means, 34, 34b current component command calculation circuit (current component command calculation means), 35, 35b primary frequency calculation circuit,
36 Current component calculation circuit.

Continued on the front page (58) Fields surveyed (Int.Cl. ⁷ , DB name) H02P 5/408-5/412 H02P 7/628-7/632 H02P 21/00 JICST file (JOIS)

Claims (9)

(57) [Claims] 1. A d-axis component on a rotating Cartesian coordinate axis which rotates at a primary frequency based on a function of the torque command, a primary frequency and a secondary magnetic flux, and q
Command of d-axis component of secondary magnetic flux and q of secondary current as axial component
Command generation means for outputting an axis component command, detection means for detecting the primary current and rotation frequency of the induction motor, and calculation of the primary frequency and secondary magnetic flux based on the primary current and rotation frequency detected by the detection means And outputting the d-axis component command of the secondary magnetic flux and the q-axis component command of the secondary current output from the command generation means to the d-axis component command and the q-axis component command of the primary current. Command conversion means, and control means for controlling the d-axis component and the q-axis component of the primary current of the induction motor to match the d-axis component command and the q-axis component command converted by the command conversion means. Control device for induction motor. 2. A d-axis component on a rotating Cartesian coordinate axis which rotates at a primary frequency based on a torque command, a primary frequency, and a function of a secondary magnetic flux.
Command of d-axis component of secondary magnetic flux and q of secondary current as axial component
Command generation means for outputting an axis component command, detection means for detecting the primary current and rotation frequency of the induction motor, d-axis component of the primary current of the induction motor based on the primary current detected by the detection means, and The primary frequency and the d-axis component of the secondary magnetic flux where the q-axis component is calculated and the q-axis component of the secondary magnetic flux of the induction motor becomes zero based on the d-axis component and the q-axis component of the primary current and the rotation frequency. , A d-axis component command of the secondary magnetic flux output from the command generating means based on the d-axis component of the secondary magnetic flux and the primary frequency calculated by the primary frequency calculating means, and a secondary A current component command calculating means for converting the q-axis component command of the current into the d-axis component command and the q-axis component command of the primary current; and the d-axis component and the q-axis component of the primary current of the induction motor being the current component Control device for an induction motor and a control means for controlling so as to coincide with the transformed d-axis component command and a q-axis component command by decree calculating means. 3. A current component calculation circuit for calculating a d-axis component and a q-axis component of a primary current of the induction motor based on the primary current detected by the detection device, The primary frequency at which the q-axis component of the secondary magnetic flux of the induction motor becomes zero based on the d-axis component and the q-axis component of the primary current calculated by the calculation circuit and the rotation frequency detected by the detection means, and the induction motor 3. A control device for an induction motor according to claim 2, further comprising a primary frequency calculation circuit for calculating a d-axis component of the secondary magnetic flux. 4. A current component calculation circuit for calculating a d-axis component and a q-axis component of a primary current of the induction motor based on the primary current detected by the detection device, The d-axis component of the secondary magnetic flux of the induction motor is calculated based on the d-axis component and the q-axis component of the primary current calculated by the arithmetic circuit, and the d-axis component of the secondary magnetic flux and the command output from the command generation means are output. A primary frequency calculation circuit for calculating a primary frequency at which the q-axis component of the secondary magnetic flux of the induction motor becomes zero based on the q-axis component command of the secondary current and the rotation frequency detected by the detection means. The control device for an induction motor according to claim 2, wherein 5. The current component command calculating means, based on the d-axis component and the primary frequency of the secondary magnetic flux calculated by the primary frequency calculating means, the d-axis component of the secondary magnetic flux and the q-axis of the secondary current. A correction amount for preventing mutual interference of components is calculated, and the d-axis component command of the secondary magnetic flux and the q-axis component command of the secondary current output from the command generation means and the d-axis of the primary current are calculated based on the correction amount. The control device for an induction motor according to any one of claims 2 to 4, wherein a component command and a q-axis component command are calculated. 6. The command generation means includes: a d-axis component of a secondary magnetic flux representing a ratio of a q-axis component of a secondary current to a d-axis component of a secondary magnetic flux of the induction motor; Based on the function and the relationship that the product of the d-axis component of the secondary magnetic flux and the q-axis component of the secondary current is proportional to the generated torque, the d-axis component command of the secondary magnetic flux and the q-axis component of the secondary current The control device for an induction motor according to any one of claims 1 to 5, wherein a command is calculated. 7. The command generating means includes: a d-axis component of a secondary magnetic flux representing a relation of a ratio of a q-axis component of a secondary current to a d-axis component of a secondary magnetic flux of the induction motor; The d-axis component command of the secondary magnetic flux is calculated from the torque command based on the function, and the torque command is divided by the d-axis component of the secondary magnetic flux calculated by the primary frequency calculating means. The control device for an induction motor according to any one of claims 2 to 5, wherein a q-axis component command of the next current is calculated. 8. The command generating means includes: a d-axis component of a secondary magnetic flux representing a relation of a ratio of a q-axis component of a secondary current to a d-axis component of a secondary magnetic flux of the induction motor; Based on the function, the d-axis component command of the secondary magnetic flux is calculated from the torque command, and the calculated d-axis component command of the secondary magnetic flux is larger than a predetermined maximum value or smaller than a predetermined minimum value. Wherein the d-axis component command of the secondary magnetic flux is limited to the maximum value or the minimum value, and the q-axis component command of the secondary current is calculated according to the d-axis component command of the secondary magnetic flux. The control device for an induction motor according to any one of claims 1 to 5. 9. The command generation means includes: a d-axis component of a secondary magnetic flux representing a relation of a ratio of a q-axis component of a secondary current to a d-axis component of a secondary magnetic flux of the induction motor; Based on the function, the d-axis component command of the secondary magnetic flux is calculated from the torque command, and the calculated d-axis component command of the secondary magnetic flux is larger than a predetermined maximum value or smaller than a predetermined minimum value. In this case, the d-axis component command of the secondary magnetic flux is limited to the maximum value or the minimum value, and the torque command is divided by the d-axis component of the secondary magnetic flux calculated by the primary frequency calculating means. The control device for an induction motor according to any one of claims 2 to 5, wherein a q-axis component command of the next current is calculated.