JPH06105584A - Controller for ac motor - Google Patents

Abstract

PURPOSE:To control an AC motor by an AC power having less disorder in an output current waveform by suitably compensating an output voltage command value to an inverter in response to an output current value to the motor. CONSTITUTION:An AC motor controller 1 previously sets and stores relationship between an output current value iu (or iv, iw) regarding an AC power to winding phases of an AC motor and compensating amounts of output voltage command values of winding phases in a memory M of a compensating amount deciding circuit 7 of a current controller 2. Then, when an ammeter 6u detects an output current value iu to be output from an inverter 4u of a PWM circuit 4 to a winding phase U of the motor, the circuit 7 applies the detected output current value iu to the relation of graphic data to obtain a compensating amount of an output voltage command value. An output voltage command value vu* is suitably compensated by using the compensating amount obtained from a comparator 10.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is intended to prevent a short circuit of a direct current between a plurality of semiconductor elements such as transistors, such as a pulse width modulation circuit (hereinafter referred to as a PWM circuit), for example. The present invention relates to a control device for an AC motor that is rotationally driven and controlled by a circuit in which a short-circuit prevention time is set at the operation switching timing of each semiconductor element.

[0002]

[Prior Art] and

The output capacity is relatively large.
Fig. 10 shows the case of controlling the rotation drive of various AC motors.
AC motor control device 1 including such a PWM circuit 4_bBut
Used. The PWM circuit 4 is for each winding of the AC motor 3.
Corresponding to the wire phases U, V, W, two transistors (5_u1When
5_u2, 5_v1And 5_v2, 5_w1And 5_w2,, of multiple semiconductor devices
Example) and diode (D₁And D₂, D₃And D_Four, D_Five
And D₆) Three inverter circuits 4 _u, 4_v, 4
_wIs equipped with. Then, the AC motor control device 1_b
Current control circuit 2_bIs related to DC power set externally
PWM for each winding phase U, V, W based on the current command value i *
Output voltage command value is calculated and each corresponding inverter circuit 4
_u, 4_v, 4_wOutput to. And each of the above inverters
Circuit 4_u, 4_v, 4_wAt a given inverter period
Each transistor 5_u1~ 5_w2By switching
The current control circuit 2_bTo each PWM output voltage command value from
The corresponding AC power is output to the AC motor 3. At this time, each
Output current value i related to AC power of winding phases U, V, W_u, I
_v, I_w(=-(I_u+ I_v)) Is an ammeter 6_u, 6_v
Is detected or calculated by the
The current control circuit 2 for determining the pressure command value_bFee
Will be driven back. Then, each of the above inverter circuits 4_u，
Four_v, 4_wIs a transistor breakdown due to a short circuit of the DC power supply.
All transistors per winding phase to prevent breakdown
The short circuit to stop the operation of
Trouble prevention time (hereinafter dead time t_dSay) is set
ing. Here, the dead time t for each winding phase_dBut that
Affects the output voltage value related to the AC power output to the winding phase
Think about the impact. Here, to make the explanation easier
Inverter circuit 4 corresponding to winding phase U for_uOnly figure
The inverter circuit 4 shown in FIG._uDead in
Im t_dThe effect of the above will be described with reference to FIG. this
Ideally two transistors 5_u1, 5_u2On
-Off switching operation should be performed at the same time. Shi
However, these transistors 5_u1, 5_u2Is predetermined
Turning on / off each in consideration of the time until operation
Sometimes the dead time t as a time difference_dIs set
It And the PWM output voltage command value for winding phase U
Is an ammeter 6_uOutput current value i detected by_uOrientation
PW as a signal with a different pulse waveform depending on (positive or negative)
It is output to the M circuit 4.

Therefore, the current control circuit 2 _b and the PWM
FIG. 13 shows an experimental result when the AC motor 3 is controlled by a general vector control method using the circuit 4.
Shown in. In this experiment, an AC motor 3 having a rated output of 0.4 kW was used, the inverter cycle of the PWM circuit 4 was 100 μs, the dead time t _d was 10 μs, the rotation speed of the AC motor 3 was 1000 rpm, and the DC power current command value i * was used. Is set to 2A. In the controller for the current loop of the current control circuit 2 _b , the d-axis, which is the direction of current that does not generate torque in the AC motor 3, and the q direction, which is the direction of current, that generates torque.
PI control is performed on the coordinates of the dq axes formed by the axis and the current command value i _d * (= in the d-axis direction determined at that time.
0) and the current command value i _q * in the q-axis direction, the output current command values i _u *, _iv *, i _w * of each winding phase are obtained, and the AC power output values corresponding to these are calculated. Winding phase U, V,
A vector control method for outputting each to W is adopted. Due to the influence of the dead time t _d , the output current value i
_u, i _v, when i _w is near 0, is close to zero even if the output voltage value from the PWM circuit 4. Therefore, as shown in FIG. 13, each winding phase U, V, W output current value i _u of, i _v, i _w
When the slope of the waveform of is near 0, it rebounds in the time direction. As a result, the waveform of the output current value is disturbed as a whole. As described above, when the output current value becomes close to 0, the output voltage value remarkably approaches 0 because the voltage amount becomes the output voltage value in the direction of decreasing the output current value due to the influence of the dead time t _d. This is because the added voltage amount has a sufficiently large value as compared with the output voltage command value when the added output current value is near 0. That is, when the output current value is large, the output voltage command value is also large, and the amount of voltage added to the output voltage value by the dead time t _d is smaller than the output voltage command value, so the influence of the dead time t _d is affected. It is difficult to receive, but when the output current value becomes close to 0, the output voltage command value becomes small in the same manner as the output current value in the above vector control method, and the voltage amount added to the output voltage value by the dead dime t _d . Is a value that is sufficiently larger than the output voltage command value, and the dead time t _d greatly affects the amount of voltage added to the output voltage value, whereby the output voltage value remarkably approaches 0. In this way, the output current values _iu , i that have generated waveform disturbances
_{When the} AC power related to _v and i _w is output to the AC motor 3, it causes a torque ripple (small vibration of torque) in the AC motor 3.

An example of a so-called dead time compensation type AC motor control device for compensating the influence of the dead time t _d on the output voltage value is, for example, the book title "AC Servo Motor Theory and Practice" (Sogo Denshi Shuppan). Issued by company, 5th
Those disclosed on pages 4 to 59) can be mentioned. FIG. 14 shows a schematic configuration of the AC motor control device 1 _c disclosed above. Therefore, first, the AC motor control device 1
_The principle of compensating the influence of the dead time t _d due to _c will be described with reference to FIG. In FIG. 15, the influence of the dead time t _d on the output voltage value is shown over one cycle of the output voltage command value v _u *. Figure 15
As is clear from the above, the actual output voltage value v _u = the ideal output voltage v _u component + the output voltage v _u component due to the dead time t _d (= E _d.
In t _d) ··· (1) Here, E _d: the voltage from the DC power supply. Therefore, if the output voltage v _u component due to the dead time t _d is approximated to a square wave voltage, the amplitude Δv of this square wave voltage is expressed by the following equation. Δv≈E _d · t _d · f _c (2) where f _{c is the} inverter frequency. And
When the equation (2) is approximated and modified, Δv = E _d · t _d / Δt (3) Here, Δt (= 1 / f _c ): inverter period.
As is clear from the equations (1) to (3), the amplitude Δv (hereinafter referred to as compensation amount Δv) in the same direction (positive or negative) as the direction of the output current value i _u is output voltage command value for each inverter circuit. By adding to v _u *, v _v *, v _w *, and outputting this as a PWM output voltage value to each inverter circuit 4 _u , 4 _v , 4 _w, to each winding phase U, V, W It is possible to eliminate the influence of the dead time t _d on the output voltage value of. That is, the output current i _u, i _v, when i _w> 0, the calculated output voltage command value by PWM output voltage command value = current control circuit _{(v u *, v v *} , v w *) + E d・ T
_d / Δt (4) When output current values _iu , _iv , and _iw <0, PWM output voltage command value = output voltage command value (v _u *, v _v * calculated by the current control circuit , V _w *)-E _d · t
_d / Δt (5)

Therefore, the output voltage command value relating to the winding phase U
v_u* Indicates from the triangular wave generation circuit 8 in the comparator 10.
After being compared with the triangular wave of
6_uOutput current value i detected by_uIn the direction of (positive or negative)
Output voltage command value compensation amount Δv (equation (4) and
Equation (5) is added. The dead time t_dof
At this time, the output voltage value output to the AC motor 3 becomes unstable.
Therefore, the inductor of the coil of AC motor 3
Due to the influence of the current flow, the output current flows in the opposite direction.
Inverter circuit 4_uDiode D₁, D₂Voltage through
Is applied. In other words, dead time t_dWhen,
As shown in FIGS. 11 and 12, the transistor 5_u1, 5
_u2Are both turned off, but the AC motor 3
The output current is positive due to the influence of the coil inductance.
Direction (i_u> 0), diode D₂Is o
And has the opposite sign to the output current, -E_dThe voltage of / 2V is the mark
Be added. On the contrary, the output current is in the negative direction (i_uFlow to <0)
Diode D₁Turns on and + E_d/ 2
A voltage of V is applied. Therefore, dead time t _dtime
When the output current flows in either positive or negative direction,
Output current value i_uOutput voltage is applied in the direction of
It will be. However, the back electromotive force generated in the AC motor 3
Is large, that is, when the AC motor 3 is rotating.
If there is a large amount of electric power in the q-axis direction that generates torque,
Or the output current value i_uIf is close to 0, the
Dead time t_dIn between, the output current value i_uIs 0 quickly
May become. Also, the output current value i_uBecomes 0
At that time, the applied output voltage also becomes zero. Therefore, this
The optimum compensation amount Δv for the output voltage command value at_d・ T_d/ Δt (6) Therefore, a constant compensation amount Δv (= ± E_d・ T_d/
Δt) As it is, the detected output current value i_uIn the direction of
Conventional AC motor control device 1 for compensating in a corresponding direction_cTo
Therefore, as described above, the back electromotive force of the AC motor 3 is
When it is large or the output current value i_uIf is close to 0,
Dead time t_dCompensation amount Δv rather than the output voltage value affected by
There was a problem that it became too big.
For example, under the same conditions as the experimental results shown in FIG.
AC motor control device 1_cAC motor 3 is controlled by
The experimental results are shown in FIG. According to the figure, for each winding phase
Output current value i_u, I_v, I_wIs, for example, moved from + to-
When trying to do so (that is, when the output current value is close to 0)
In addition, the compensation amount Δv is better than the PWM output voltage command value.
Since it is too large, each winding is affected by the effect of the above compensation amount Δv.
The output current value of the phase must be prevented from shifting from + to-.
It happened that there was a phenomenon that it could not move to the negative side. In addition, the above
When the force current value shifts from − to +, the same current
An elephant was born. This is because the output voltage command value is close to 0, for example.
At times, the output voltage applied to the AC motor 3
Dead time t_dThe effect of is reduced. And output power
The pressure command value is the positive compensation amount + Δ when the output current value is positive.
v, or when the output current value is negative, the negative compensation amount −Δ
v respectively compensated. Furthermore, the compensation amount Δv
The size is constant. Therefore, the output voltage command
The value will be overcompensated. For example, output current value
Is negative, the negative output voltage of the same sign as the AC motor 3
Therefore, the output current value is very negative.
Can't move from positive to positive. In the opposite case (output current value is
The same applies to positive cases). Therefore, the above AC motor control
Device 1_cThe control result of the AC motor 3 by is the PWM output
Vector control method without any compensation for voltage command value
The output current value is more disturbed than the control result by the formula (Fig. 13).
The result has been to increase. Therefore, the object of the present invention is to
AC power output from the inverter circuit to the AC motor
Depending on the output current value, the output voltage command value at that time is appropriately supplemented.
Compensation, the output current value with less disturbance in the waveform
AC motor control that can control the AC motor
To provide a control device.

[0006]

In order to achieve the above-mentioned object, the first means adopted by the present invention is the gist of the present invention, in which each winding phase is connected corresponding to each winding phase of the AC motor. A plurality of semiconductor elements that are switched at a predetermined cycle, and an inverter circuit that outputs AC power based on the voltage command value for each winding phase calculated from the set DC power command value to the AC motor. A controller for an AC motor in which a short-circuit prevention time for stopping the operation of all the plurality of semiconductor elements when switching the plurality of semiconductor elements connected for each winding phase is set, A current value detecting means for detecting an output current value related to the AC power to each winding phase of the AC motor, and a preset current value detecting means for detecting the output current value to each winding phase and the AC power to each winding phase. Storage means for storing the relationship between the output voltage value and the compensation amount; and output voltage value obtained by applying the output current value for each winding phase detected by the current value detection means to the stored relationship. The present invention is configured as a control device for an AC motor, comprising: first voltage command value compensating means for compensating a voltage command value for each winding phase to the inverter circuit according to a compensation amount. In order to achieve the above-mentioned object, the second means adopted by the present invention has as its gist a plurality of semiconductor elements connected to each winding phase corresponding to each winding phase of the AC motor. An inverter circuit is provided which outputs AC power to the AC motor based on the voltage command value for each winding phase calculated from the set DC power command value by switching at a predetermined cycle.
In the AC motor control device in which the short-circuit prevention time for stopping the operation of all the plurality of semiconductor elements when switching the plurality of semiconductor elements connected for each winding phase is set, the winding input by setting Based on the target value of the output current value related to the AC power for each phase, the feedforward calculation means for estimating and outputting the compensation amount of the output voltage value related to the AC power, and the compensation amount of the output voltage value output as described above. Second for compensating the voltage command value for each winding phase to the inverter circuit
And a voltage command value compensating means of the present invention.

[0007]

In the control device for the AC motor according to the first means of the present invention, the output current value related to the AC power to each winding phase of the AC motor and the output voltage value related to the AC power to each winding phase of the AC motor are set. The relationship with the compensation amount is preset as, for example, graph data and stored in the storage means. Therefore, when the current value detecting means detects the output current value from the inverter circuit to each winding phase of the AC motor, the first voltage command value compensating means outputs the detected output current value for each winding phase as described above. The compensation amount of the output voltage value is obtained by applying the stored relation. Further, the first voltage command value compensating means compensates the voltage command value for each winding phase to the inverter circuit using the compensation amount. That is, the output voltage value to each winding phase is appropriately compensated based on the above-mentioned relationship according to the output current value even if the output current value detected at that time is near 0, for example. Further, in the AC motor control device according to the second means of the present invention, when the target value of the output current value related to the AC power for each winding phase of the AC motor is set and input to the feedforward calculation means, The feedforward calculation means estimates and outputs the compensation amount of the output voltage value related to the AC power, based on the target value of the output current value. Therefore, the second voltage command value compensating means forcibly compensates the voltage command value for each winding phase to the inverter circuit by the compensation amount of the output voltage value output from the feedforward computing means. Therefore, even if the output current value is near 0, the voltage command value is compensated independently of the output current value at that time, so the direction of the output current value easily exceeds the value of 0 and is opposite. It becomes the direction of.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments embodying the present invention will be described below with reference to the accompanying drawings for the understanding of the present invention. The following embodiments are examples of embodying the present invention and are not intended to limit the technical scope of the present invention. Here, FIG. 1 is a block diagram showing a schematic configuration of an AC motor control device according to an embodiment of the present invention, and FIG. 2 is preset and stored in a memory of the AC motor control device for each rotational angular velocity of the AC motor. Fig. 3 is a graph showing the relationship between the output current value to the winding phase U and the amount of compensation of the output voltage command value related to the winding phase U, Fig. 3 is the output current value to the winding phase U and the winding FIG. 4 is a graph showing another example of the relationship between the output voltage command value and the compensation amount related to the phase U for each current value in the q-axis direction, and FIG. FIG. 5 is a graph showing the experimental results concerning the output current value for each line phase, and FIG. 5 shows the output current value for each winding phase of the AC motor subjected to the saturation function approximation and the compensation amount of the output voltage command value for each winding phase. Related to the output current value output to the AC motor FIG. 6 is a graph showing test results, FIG. 6 is a block diagram showing a schematic configuration of an AC motor control device according to another embodiment of the present invention, and FIG. 7 is each winding output to the AC motor by the AC motor control device of FIG. FIG. 8 is a graph showing the experimental results regarding the output current value for each phase, and FIG. 8 is the output current value for the AC motor for each winding phase when the feedforward model formula of the AC motor control device of FIG. 6 is approximated by a saturation function. FIG. 9 is a graph showing the experimental results regarding, and FIG. 9 shows the compensation amount obtained by approximating the output voltage command value for each winding phase in the AC motor control device of FIG. 6 by a square wave based on the current command value set from the outside. It is a graph which shows the experimental result regarding the output current value etc. for each winding phase at the time of compensating. However, the conventional AC motor control device 1 _b shown in FIGS.
The same elements as those in 1 _c are designated by the same reference numerals, and detailed description thereof will be omitted.

The AC motor control device 1 according to this embodiment is
As shown in FIG. 1, the above-mentioned conventional AC motor control devices 1
_b, 1_cThe basic structure is similar to
Flow motor controller 1_b, 1_cThe characteristic difference with
For each winding phase to the flow motor 3 (again, for winding phase U
(The example is also the same for the other winding phases V and W)
Output voltage command value v_u* Dead time t for *_d
Compensation amount Δv for compensating the influence of
In the memory M (an example of storage means) of the compensation amount determination circuit 7,
To the winding phase U of the AC motor 3 obtained by the experiment
Output current value i related to AC power_uAnd the output related to the above AC power
Force voltage command value v_uRelationship between * and compensation amount Δv (see Fig. 2)
Is, for example, set and stored as graph data.
And. The output current value and output voltage command value
The relationship with the compensation amount Δv is also related to the winding phase V and the winding phase W.
The same one is preset and stored in the memory M.
It Output current value i_uAnd output voltage command value compensation amount Δv
As shown in FIG. 2, the relationship with
Axial current value i_qIs a constant value (= 0.1A), and rotation
Rotation angle of AC motor 3 detected by angle detector 12
For each rotational angular velocity obtained from the degree θ (see FIG. 10) (for example, 5
Multiples are set every 0 rad / s). Also, the above exchange
The current control circuit 2 of the motor control device 1 has a conventional current control circuit.
Control circuit 2 _cSimilarly, the output voltage command value from the comparator 10
Hysteresis comparator to prevent chattering
Data and the output from this hysteresis comparator 9
The inverter circuit 4 of the PWM circuit 4 based on the voltage command value
_uTransistor 5 in _u1 , 5_u2Do not work at the same time
The dead time (short circuit prevention time) t_dSeeking
Therefore, this dead time t_dUsing each of the above transistors
5_u1 , 5_u2It is equipped with a base amplifier 11 to switch between
Has been. The output current value i_uAnd the output voltage command value
For the relationship with the compensation amount Δv, replace the one shown in FIG.
For example, as shown in FIG. 3, rotation of the AC motor 3 is performed.
The current when the angular velocity is a constant value (= 0 rad / s)
Value i_qIt is also possible to use a relationship for each. 2 and 3
As is clear from the above, the output current value i to the AC motor 3_u
(I_v, I_w) Or back electromotive force generated in the AC motor 3
The above output is obtained according to the rotational angular velocity that represents the electric power equivalently.
Current value i_uDead time t that affects_dAgainst
The optimal compensation amount Δv for the output voltage command value
I understand that Therefore, as the compensation amount Δv,
Output current value i_uA constant value (= E_d・
t_d/ Δt; in FIGS. 2 and 3, for example, ± 50 V
Corresponding to the output current value i_uBut
When it is close to 0, the compensation amount Δv of the output voltage command value is too large.
Something is clear.

The AC motor control device 1 according to this embodiment is constructed as described above. Therefore, when the output current value i _u related to the AC power output from the inverter circuit 4 _u to the winding phase U of the AC motor 3 is detected by the ammeter 6 _u (an example of current value detection means), the current control circuit The compensation amount determination circuit 7 of No. 2 has the detected output current value i of the winding phase U.
_u is applied to the relationship (the relationship shown in FIG. 2 or FIG. 3) previously stored as graph data in the memory M to obtain the compensation amount Δv of the output voltage command value of the winding phase U and the comparator 1
Output to 0. In the comparator 10, the triangular wave generation circuit 8
Is output to the hysteresis comparator 9 after the compensation amount Δv is added to the output voltage command value v _u * relating to the winding phase U to be compared with the triangular wave output from. That is, the configuration including the compensation amount determining circuit 7 and the comparator 10 is obtained by applying the output current value for each winding phase detected by the current value detecting means according to the present invention to the stored relationship. It is an example of first voltage command value compensating means for compensating the voltage command value for each winding phase to the inverter circuit by the compensation amount of the output voltage value. Output current value i _u to the AC motor 3 which is controlled by the AC motor control device 1, i _v, the experimental results on i _w such shown in FIG. As is clear from FIG. 4, according to the AC motor control device 1, the AC motor control device 1 shown in FIG.
Based on the relationship shown in, the output current value and the AC motor 3
The optimum compensation amount Δv of the output voltage command value v _u * which is influenced by the dead time t _d can be obtained according to the rotational angular velocity corresponding to the counter electromotive force. Then ,, the output voltage command value compensated by the compensation amount Δv is given to the inverter circuit 4 _u, fixed compensation amount Δv as conventional the AC motor controller _{1 b, 1 c (= E} d · t _d
Compared to the case where the output voltage command value v _u * is compensated by / Δt), the waveforms of the output current values i _{u to} i _w are, for example, the waveforms of the output current values even when the output current value is close to 0. It can be seen that there is no bouncing in the time direction, and that it has been significantly improved. That is, as compared with the conventional device, the device of this embodiment can eliminate the torque ripple of the AC motor 3 as much as possible. On the other hand, in order to further improve the optimality of the compensation amount Δv with respect to the influence of the dead time t _d , the graph obtained by the saturation function approximation from the experimental result is used as the graph of the relationship shown in FIG. 2 or 3. To be FIG. 5 shows the experimental result when the above-mentioned compensation amount Δv is obtained using the graph at this time. In this case, the shape of the graph approximated to the saturation function is changed as much as possible by changing it according to the rotational angular velocity of the AC motor 3 (corresponding to the back electromotive force).
Alternatively, the shape is set to be close to the relationship graph shown in FIG. Figure 5
The waveforms of the output current values i _{u to} i _w shown in (1) are sufficiently improved as compared with the experimental results (FIG. 13 or FIG. 16) by the conventional device, and thus the torque ripple of the AC motor 3 is sufficiently suppressed. I understand. However, the experimental results when the above saturation function approximation was not performed (see Fig. 4)
Unexpectedly, the waveform was disturbed and the above torque ripple increased compared to.

In the above embodiment, the ammeters 6 _u and 6 _{v are used.}
Output current value i _{u for} each winding phase detected and calculated by
Output voltage command values v _u *, v _v * depending on i _w
Although a configuration in which each compensation amount Δv of (not shown) and v _w * (not shown) is changed is adopted, the above-mentioned configuration is replaced with, for example, the above according to an exemplary current command value i _u * given from the outside. It is also possible to employ the AC motor control device 1 _a (FIG. 6) that uses a feedforward method that calculates each compensation amount Δv. The AC in the memory M _a of the motor control apparatus 1 _a current control circuit 2 compensation amount determining circuit which is deployed in _a 7 _a, the current command value i _u * the output voltage command value based on v _u *
A feedforward model formula for obtaining the optimum compensation amount Δv of is set and stored. Also, the parameters used in the above feedforward model formula (not shown)
Is determined in advance by experiments or the like. Further, the feedforward model formula is also set so that the rotational angular velocity corresponding to the back electromotive force of the AC motor 3 can be input from the outside, thereby improving the accuracy of the compensation amount Δv. Has been. FIG. 7 shows the result of an experiment using the AC motor control device 1 _a . As is clear from the figure, the output current values i _{u to} i _w are significantly improved for each winding phase as compared with the experimental results (see FIG. 13 or FIG. 16) of each conventional device. It can be seen that the torque ripple is getting smaller.

As described above, the AC motor control device 1_a
According to the detected output current value i _u(Or i_v，
i_w), The compensation amount determination circuit 7_aAt the outside
Output current command value i given by_u* And AC motor 3
An appropriate compensation amount Δv is obtained based on the rotation angular velocity of
As a result, the output voltage command value v_u* (Or v_v*, V
_w*) Is forcibly compensated, so the output current
I i_u* ~ I_wEven if * is near 0,
Each output current value i_u~ I_wStays near 0
The change in the direction of the electric current is not hindered.
As a result, each output current value i_u~ I_wThe direction of changes smoothly
As a result, these waveforms are significantly improved. this
AC consisting of the output current value for each winding phase
By the electric power, for example, torque ripple of the AC motor 3
Is extremely suppressed. On the other hand, the AC motor control device 1
_aCompensation amount determination circuit 7_aFeed forwarder set to
When the above saturation function approximation method is applied to
The experimental results are shown in FIG. According to the experimental results shown in the figure
For example, the experimental results when the saturation function approximation method is not used
Output current value i compared to (see FIG. 7)_u~ I_wWaveform is young
Although it is disturbed, it is still significantly improved compared to the past.
You can see that it is. Conventional AC motor control device
1_c(See FIG. 14), the detected output current value i_uDirection
Output voltage command value v with a constant compensation amount ± Δv
_u* Was compensated, but the detected output current above
Value i_uInstead of the compensation amount determining circuit 7_aBy model
Typical current command value i_u*, For example, this current command value
i_uCompensation with square wave approximation according to the direction and size of *
The output voltage command value v according to the amount Δv_uTo compensate *
You may The output voltage command value compensated in this way
The experimental results used are shown in FIG. Each output current shown in Fig. 9
Value i_u~ I_wCompared to those shown in Figures 7 and 8.
For example, when the value is near 0, the waveform is slightly disturbed.
Compared to the experimental results (see Fig. 13 or Fig. 16)
The waveform has been improved. That is, the compensation amount determining circuit 7_a
Is an example of the feedforward calculation means referred to in the present invention.
At this time, the comparator 10 is the second voltage finger according to the present invention.
It is an example of a means for compensating for an official price.

[0013]

The present invention is constructed as described above. Thereby, according to the detected output current value or the command value of the output current value externally set and input for each winding phase relating to the AC power output from the inverter circuit to the AC motor, the inverter circuit is then set. The voltage command value for each winding phase output to is compensated. Therefore, even if the output current value or its command value is near 0, for example, the influence on the voltage command value by the short circuit prevention time for stopping the operation of all the semiconductor elements is compensated according to the value. An appropriate amount of compensation is required. Since the voltage command value for each winding phase to the inverter circuit is compensated by the calculated compensation amount, the AC motor is controlled by the AC power of the output current value for each winding phase with less disturbance in the waveform. can do. As a result, for example, torque ripple of the AC motor can be suppressed as much as possible.

[Brief description of drawings]

FIG. 1 is a block diagram showing a schematic configuration of an AC motor control device according to an embodiment of the present invention.

FIG. 2 is a compensation amount of an output current value to a winding phase U and an output voltage command value related to the winding phase U, which is preset and stored for each rotational angular velocity of the AC motor in a memory of the AC motor control device. The graph figure which shows the relationship with.

FIG. 3 shows the output current value to the winding phase U and the winding phase U.
FIG. 6 is a graph showing another example of the relationship between the output voltage command value and the compensation amount for each q-axis current value.

FIG. 4 is a graph showing experimental results regarding output current values and the like for each winding phase related to AC power output to the AC motor by the AC motor control device.

FIG. 5 is an output current value output to the AC motor by using the relationship between the output current value to each winding phase of the AC motor subjected to the saturation function approximation and the compensation amount of the output voltage command value to each winding phase. FIG. 6 is a graph showing the experimental results regarding the above.

FIG. 6 is a block diagram showing a schematic configuration of an AC motor control device according to another embodiment of the present invention.

FIG. 7 is a graph showing an experimental result regarding output current values and the like for each winding phase output to the AC motor by the AC motor control device of FIG. 6.

FIG. 8 is a graph showing an experimental result regarding an output current value to the AC motor for each winding phase when the feedforward model formula of the AC motor control device of FIG. 6 is approximated by a saturation function.

FIG. 9 is a winding phase when the output voltage command value for each winding phase is compensated by a compensation amount obtained by a square wave approximation based on a current command value set from the outside in the AC motor control device of FIG. The graph figure which shows the experimental result regarding the output current value etc. for every.

FIG. 10 is a block diagram showing a schematic configuration of a conventional AC motor control device as an example of the background of the present invention.

11 is a block diagram showing a schematic configuration of an inverter circuit of a winding phase U of the PWM circuit of the conventional AC motor control device shown in FIG.

12 is an explanatory diagram showing ON / OFF operation of a transistor in the inverter circuit of FIG. 11 and behavior of an output voltage command value to this inverter circuit.

FIG. 13 is a graph showing experimental results regarding output current values and the like for each winding phase output to an AC motor by a general vector control method using the AC motor control device of FIG. 10.

FIG. 14 is a block diagram showing a schematic configuration of a conventional AC motor control device that is another example of the background of the present invention.

15 is an explanatory diagram for explaining a compensation amount of an output voltage command value obtained by a square wave approximation for compensating an influence of dead time on an output current value for each winding phase by the AC motor control device of FIG.

FIG. 16 is an experimental result relating to the output current value for each winding phase when the influence of the dead time on the output voltage command value is compensated by the compensation amount approximated to a square wave using the AC motor control device of FIG. FIG.

[Explanation of symbols]

1, 1 _a , 1 _b , 1 _c ... AC motor control device 2, 2 _a , 2 _b , 2 _c ... Current control circuit 3 ... AC motor 4 ... PWM circuit 4 _u , 4 _v , 4 _w ... Inverter circuit 5 _u1 ... 5 _w2 ... Transistor (semiconductor element) 6 _u , 6 _v ... Ammeter 7, 7 _a , 7 _c ... Compensation amount determination circuit 10 ... Comparator v _u *, v _v *, v _w *, ... Output voltage command value _{i u, i v, i w} ... output current value _{i u *, v v *,} v w *, ... the output current command value (target value) Δv ... compensation amount t _d ... dead time (prevention of short-circuit output voltage command value time) M, M _a ... memory

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Yoshinori Imaizumi 1-2 Nakamura, Sanya-cho, Toyohashi City Kobe Steel Works Toyohashi FA / Robot Center

Claims (2)

[Claims] 1. A winding phase calculated from a set DC power command value by switching a plurality of semiconductor elements connected for each winding phase corresponding to each winding phase of an AC motor in a predetermined cycle. An inverter circuit that outputs AC power based on each voltage command value to the AC motor is provided, and the operation of all of the semiconductor elements is stopped when the plurality of semiconductor elements connected for each winding phase are switched. In a control device for an AC motor for which a short circuit prevention time is set, current value detection means for detecting an output current value related to AC power from the inverter circuit to each winding phase of the AC motor; Storage means for storing the relationship between the output current value to each winding phase and the compensation amount of the output voltage value related to the AC power to the winding phase, and for each winding phase detected by the current value detecting means First voltage command value compensating means for compensating the voltage command value for each winding phase to the inverter circuit by the amount of compensation of the output voltage value obtained by applying the output current value of 1 to the stored relationship. An AC motor control device comprising: 2. A winding phase calculated from a set DC power command value by switching a plurality of semiconductor elements connected for each winding phase corresponding to each winding phase of an AC motor in a predetermined cycle. An inverter circuit that outputs AC power based on each voltage command value to the AC motor is provided, and the operation of all of the semiconductor elements is stopped when the plurality of semiconductor elements connected for each winding phase are switched. In a control device for an AC motor in which a short-circuit prevention time for setting is set, the amount of compensation of the output voltage value related to the AC power is set based on the target value of the output current value related to the AC power set and input for each winding phase. And a second voltage command value compensating means for compensating the voltage command value for each winding phase to the inverter circuit by the compensation amount of the output voltage value outputted. A controller for an AC motor, characterized by comprising comprises.