JPS6011553B2 - Induction machine vector control device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention particularly relates to a vector control device for an induction machine using a frequency converter such as a current source inverter.

In recent years, a control method called a vector control method has been attracting attention as a control method for induction machines.

This control method is also described in Japanese Patent Publication No. 50-34725 and Hakama-Seki No. 52-149314. In summary, this method attempts to control the stator current vector so that the rotor current vector in the induction machine always flows perpendicular to the rotor magnetic flux vector. That is, FIG. 4 shows a current vector diagram inside the induction machine when vector control is performed.

In the figure, the rotor magnetic flux vector spring is represented by the string excitation current vector. This excitation current vector' width is the interangular wave number o, which is the sum of the rotor angular frequency r and the steady slip angular frequency .

The angle 8o that rotates at 2 r+Sゞ"...[11 and then the vector's stationary axis o-kawa is 8.

:' no putko J (no r+■s,) dt...■. 1
2 is a current vector related to the rotating Viscount flow, which is the generated torque of the induction machine or the S.sub.2 of the steady slip angle frequency. is proportional to.

Now, with the stator current vector, the following '3' equation between the excitation current vector 'wide' and the current vector 12, that is, the phase angle 0.
Anchor Misaki skin system. ．． ．． ．． ．． [3, (However, if 12 is ahead of L, the value will be positive, and if it is behind, it will be negative.

)and, 『ー＝R.

-20-hair-2...[4] has the following relationship.
Now, when vector control is performed by combining a frequency converter and an inductor, [a] detects the rotational angular frequency r of the rotor, and 'b} adds the steady slip angle calculated in the vector calculator to this. From the frequency s, the rotation angle of the Evector is 8.

(=J's.dt=J(r+S.)dt...■Formula) is calculated, and 'C' is the angle 8 which is obtained by adding the 8 scales of the '3' formula to this angle, i.e. 0, = 8.

A current of magnitude l1, l according to the '41 formula is caused to flow at point os2, to create a current vector 1. Therefore, the frequency converter must be capable of establishing the required stator current vector 1 in the induction machine at any given time. Frequency converters include sine wave current cycloconverters, voltage source inverters that perform current control, and current source inverters, but in reality commutation of current takes time, so it is not possible to convert current at the required time. It may not always be possible to establish a stator current vector in the commanded direction. In particular, when a current source inverter is used, the control range becomes narrower because the overlap time of currents due to commutation becomes longer. For example, in Figure 1, figure a is a typical circuit of a current source inverter, figure b is a diagram depicting the movement of the stator current vector, and figure c is an inverter circuit corresponding to the movement of the current vector in figure b (a The commutation sequences in Figure 1) are shown respectively.

In each of the above figures, QU, Qv, Qw, Qx, QY,
Q2 is a thyristor, DU, Dv, Dw, Dx, DY, D
2 is a diode, 1u, lv, lw are currents of each phase, I
M'ma induction machine, L~t, 4 is the time point shown according to the commutation order of the current vector. Now, at time 5 in diagram c, commutation occurs from Qu to Qv, and the commutation ends after time Tu, but at time 7, the stator current vector is commanded to return to the rear, so Qv again →Transfer to QU is performed.

If vector control is not performed, commutation is Qli→Q
Only a forward commutation such as v → Qw is sufficient, but in the case of vector control, depending on the load requirements, for example, as shown in diagram c, the current transferred from QU → Qv may be reversed from Qv → QU.
This results in repeated complicated commutation operations, such as backward commutation such as transfer to Therefore, the control circuit becomes complicated, and since the current overlap period TU is relatively long, even if a command is received, the fixed Viscount flow vector cannot be moved during this period TU. This problem is caused by the fact that the inverter is operated obediently to the command to "return" the fixed Viscount flow vector. SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a control device that can perform vector control of an induction machine using a current source inverter, even if the commutation of the inverter is limited only to the forward direction. .

The present invention will be explained below with reference to an illustrated embodiment.

First, FIG. 2 shows a drive circuit for an induction motor according to the present invention. In the figure, reference numeral 1 denotes a current controller, which functions to cause a DC current value commanded by an input command signal 2 to flow through terminals 3 and 4, and its configuration is typically in the form of the illustrated circuit. Fin flow controller 1
, 5 is a three-phase AC power supply, and 6 is a rectifier, which is constituted by a thyristor bridge, rectifies the three-phase AC 5 and supplies DC output to the terminals 3 and 4. 7 is a current detector, and 8 is a regulator, which converts the current value detected by the current detector 7 into a control signal 9 suitable for the control circuit.

10 is an error detector which detects the current command signal 2 and the detected current signal (
The error with control signal) 9 is output as signal 11.

12 is an error amplifier, 13 is an error amplification output, and 14 is a rectification controller. The rectification controller 14 sends, for example, a suitable firing pulse to the rectifier 6 through a signal 15 to control the conduction of the rectifier 6.

The above is the configuration of the current controller 1. Next, 16 is a DC reactor, and 17 is an inverter, and this combination constitutes, for example, a current source inverter as shown in FIG. 1A, and converts DC current into variable frequency three-phase AC.

18, 19, and 20 are three-phase AC output terminals, and 21 is a three-phase induction motor (hereinafter abbreviated as dielectric machine) to be controlled.

). A pulse oscillator 22 outputs a pulse train r' having a frequency proportional to the rotational angular frequency of the rotor of the promoter 21 as a signal 23.

24 is a rotation speed command device which outputs a command signal 25.

A vector calculator 26 calculates and outputs the following command signal from the rotational speed command signal 25, the rotational angular frequency signal 23 of the induction machine 21, the electrical constant of the induction machine 21, etc.

In other words, stator current command (stator tortoise current vector/signal 2 as the absolute side of the fin, for example, a binary signal as the torque angle command os2 between the stator tortoise current vector and the excitation current vector ball) 27, a signal 28 is output as a rotation angular frequency command obtained by shaping the pulse of the signal 23, and a signal 29 is output as a slip angular frequency command s,' of a pulse train with a frequency proportional to the steady slip frequency. Vector control is performed by controlling the stator current vector of the induction machine 21 according to the command output from the vector calculator 26. ,'), 27
(8), and the stator current vector is changed to the phase command o.
It outputs a signal 31 of , and also has a built-in oscillator (not shown) to output an advance pulse signal 32 consisting of a pulse train of an appropriate frequency.

33 is a phase adjuster according to the present invention, which receives signals 31 (0,) and 32 (whiskers) from the phase calculator 30, processes the signals internally, and outputs the main circuit phase command of the stator current vector to its output 34. 8,. However, main circuit phase commands 0, . 34 is characterized in that it follows by changing only in the increasing direction.

The phase calculator 30 and phase adjuster 33 described above are collectively referred to as a phase command unit 35, the details of which will be described later with reference to FIG. 36 is an inverter controller, and the fixed Viscount's position fence is connected to the main circuit. 34, commands a, . For example, the switching elements of the inverter 17 are controlled to fire so as to create the stator current vector 1 in the phase indicated by 34.

This inverter controller 36 and the above-mentioned phase controller 35 are collectively called a fixed viscount flow phase controller 37, and this controller 3
7 is the command unit 28 (throat'), 29 (s,'), 27 (
As2), for example, in order to create the stator current vector shown in FIG. It acts like flowing. The above is the configuration of the circuit shown in FIG. next,
The phase adjuster 33 according to the present invention will be explained in association with the phase calculator 30.

FIG. 3 is a block diagram showing the configuration of the phase calculator 30 and the phase adjuster 33.

It should be noted that input/output signals in the same figure that are the same as or corresponding to those in FIG. 2 are given the same reference numerals. In the phase calculator 30, 38 is a pulse synthesis circuit, which combines the pulse train of rotation angular frequency command r'28 and the slip angular frequency command s,'2.
9 pulse trains are added and the result is .

It outputs a pulse with a pulse frequency of {5}, that is, a signal 39 with an excitation current vector angular frequency o' proportional to the rotation angular frequency of the excitation current vector.

By integrating this angular frequency o'39 over an appropriate time, it is possible to obtain the rotation angle of the exciting current vector in FIG. 4 with respect to the stationary coordinates 01U, that is, the exciting current vector phase oo. Reference numeral 40 denotes a counter, which may be, for example, a binary counter, which counts the input pulses of the signal 39 (o') in binary.

Therefore, if the counter 40 is considered as a kind of integrator, the output of the counter 40 is 8.

=No's illusion=ノ('r+ws,')dt.・・・．
...The phase of the binary excitation current vector is '6'.

An output signal 41 of (formula {6}) is obtained. 42 is an adder, for example, a binary adder or the like is used.

The input of this adder 42 is the excitation current vector phase 8.
41 and torque angle command 8s227 are derived, and the value of both is 8.
. Add 41 and 8227 and get the algebraic sum 81 d 80
18 """ {7, is the phase command of the stator current vector 8
, outputs a signal 31.

Furthermore, 43 is a leading pulse oscillator which outputs a signal 32 on the day of the leading pulse of a pulse train having a sufficiently high repetition frequency.
Next, in the phase adjuster 33 according to the present invention, a comparator 44 compares the magnitude of two binary numbers, for example, and outputs the result as a logic signal.

The comparator 44 receives phase commands 0 and 31 of the fixed Viscount flow vector.
and the output of the counter 48 (described later), that is, the actual phase commands a, . . . of the main circuit of the stator current vector. 34 has been introduced, and these 8, 31 and 8, . For example, 8,>8, . (The phase command 8, is higher than the actual phase.
When the state is in a more advanced state), a “logic 1” is output to output 45.
Output OS8, . When the phase command 0, lags behind or is equal to the actual phase HI, ., a logic 0 is output to the output 45. 46 is a gate circuit, and the advance pulse of the signal 32 is output to the terminal 47 when the logic of the signal 45 is 1, and is not output when the signal 45 is logic 0.

A counter 48 is composed of, for example, a binary counter, and performs binary counting of the pulse signal 47 which is controlled to be "passed or not passed" by the gate circuit 46.

The output of this counter 48 is a command representing the actual phase of the fixed Viscount flow vector, that is, the main circuit phase commands 8, . 34, and this phase command is 0, . 341 is input to the inverter controller 36 in FIG. To summarize the above operation of the phase adjuster 33, for example, the phase controller 8, . When the relationship is “0,>0,.”, the signal 45
The logic of is "1", the gate 46 is "open", the advance pulse day 32 is input to the counter 481, and 0, . increases, and finally becomes "8.=hi,r. Also, "
0,kua,. ”, the signal 45 is logic “0” and the gate 46 is “open”, so the advance pulse day 32 is no longer input to the counter 48 and 8,. stops increasing; on the other hand, 8,. For example, since 8. continues to increase, 0, also increases, and finally "0, = 0, . '1
becomes. Therefore, by setting the frequency of the advance pulse sufficiently high, 8,≠0, . The operation is stable even in the vicinity of a, . will move almost following 8. That is, for the phase command a, the main circuit phase commands 8, . 8, . As a result, these commands 8, . The inverter 17 controlled by the above also eliminates backward commutation as in the conventional case. This can prevent the commutation circuit from becoming complicated and facilitate circuit design. Next, in order to further facilitate understanding of the present invention, the operation of vector control of the induction machine using the phase adjuster 39 will be briefly explained.

Assume now that the load on the induction machine is steady and a vector relationship as shown in FIG. 4 is required.

Here, from the vector calculator 26 (Fig. 2), the rotation angular frequency command r'28, the slip angular frequency command s, '29
, torque angle command as227, and stator current command IL
l2 is being output. Each of these command outputs is processed by the phase calculator 30, and the excitation current vector phase oo 41,
and 81:oo +OS2, which becomes the stator current vector phase command 8,31. On the other hand, in the steady state in the phase adjuster 33, the phase commands HI, 31 and the main circuit phase commands 0, .
34 are equal, and these 8, . 34, the inverter controller 36 adjusts the phase angles 8, . is controlled to create a fixed Viscount flow vector in the direction of . In addition, since the current controller 1 receives the current command "-2" and injects a current of a certain magnitude into the induction machine 21, the vector relationship as shown in Fig. 4 is established in the induction machine 21. There is. Next, consider a case where the load increases stepwise.

A vector diagram at this time is shown in FIG. In Figure 6, the vector diagram (01 above, 1 etc.) indicated by the solid line is before the change,
The vector diagram (01t, 1V) indicated by a broken line is the state to be taken after the change. Now, before the negative change, the output signal 27 of the vector calculator 26 (Fig. 2) is 8s2 in Fig. 6.
A torque angle command is issued. Now, when the negative complement increases rapidly and the torque angle command 8s2 increases rapidly, the phase calculator 30 (FIG. 3) also increases rapidly by 6 due to the rapid increase in the torque angle 8s2. Then, in the phase adjuster 33, due to the sudden increase in the phase command 8, 0,>8, . Therefore, the counter 48' advances to count the pulse day 32 and 8, . increase and immediately follow the enemy. As a result, as mentioned earlier,
Almost immediately, the dashed line vector diagram in Figure 6 (01L
-t2') will be established within the induction machine.
Next, consider a case where the load on the induction machine decreases in steps, contrary to the above.

A vector diagram at this time is shown in FIG. In Fig. 7, the solid line vector diagram (0-mu t2) is before the load change,
The broken line vector diagram (0-t', -t'2) is the state of the vector that is about to be reached after the change. Now, when the load suddenly decreases and as a result, the torque angle command 8s2 suddenly decreases, in the phase calculator 30, due to the sudden decrease in the torque angle, a also suddenly decreases. In the phase adjuster 33, due to the sudden decrease in the phase command 8, 8,
8,. Therefore, the counter 48 stops the counting operation and a, . stop increasing. On the other hand, as the induction machine continues to rotate, the excitation current vector phase ao continues to increase as pulses continue to be output, and as a result, a also increases, and finally becomes equal to a. The counter 48 starts counting again, and following 8, a,. starts to move as well.The current controller 1 is also operating, and as a result,
The vector diagram (01t', 1t'2) indicated by the broken line in FIG. 7 can be established in the transfer machine 21, although it is delayed by a delay time related to the speed of rotation of the exciting current vector. What is important here is that in normal vector control, when the load suddenly decreases, the phase of the stator current vector is temporarily moved backwards to achieve the desired vector state, for example (01 to -r2) in Fig. 5. However, in the present invention, phase 8 of the stator current vector is stopped, and the excitation current vector of the motor is expanded and rotated (see Fig. 7, where it increases from ao to 8'. Note) The point is that the desired vector state is achieved. However, the embodiments of the present invention are not limited to the examples described above.

For example, FIG. 8 shows another example of the phase adjuster according to the present invention. In FIG. 8, the same or corresponding parts as in FIG. 3 are given the same reference numerals. The comparator 44 has two logic outputs 45 and 49, and one output 49 has its logic inverted via an inverter 50 to obtain an output 51. 46,
52 is a gate circuit, one gate circuit 46 is inputted with the advance pulse date 32, and the other 52 is inputted with the rotational angular frequency 'o 39 of the excitation current vector, and the signals 47 and 49 are inputted, respectively. Gate controlled.

The outputs of the gate circuits 45 and 52 are pulse-added in a synthesis circuit 53, and the output is input to a counter 48. The operation is, for example, 0,=8,. When , the signal 45 is logic 0, the signal 49 is also logic 0, that is, the output 51 is logic 1, so the counter 48 counts o'39 of the rotational angular frequency of the excitation current vector in the same way as the counter 40, and the same Count quickly.
Also, 0・>8, . At this time, the signal 45 becomes logic 1, the signal 49 becomes logic 0, that is, the output 51 becomes logic 1, so the counter 48 counts the pulses corresponding to 'o+' of H=. =8,. It becomes an equilibrium state. Furthermore, the enemy <011
At this time, the signal 45 becomes logic 0, the signal 49 becomes logic 1, that is, the output 51 becomes logic 0, and the counter 48 stops counting because there is no input pulse, but oo of one counter 40 increases and its As a result, 8, increases and 8,=8,. An equilibrium state is reached. In any case, in the circuit of Fig. 8, 8, . moves only in the increasing direction and follows 8. "
There are various ways to create the advance pulse 32. One example is to create a signal with a frequency that is at least twice as high as o', using o', the rotational angular frequency of the excitation current vector, as a reference. It can be used as the day of the day.

Thus, according to the invention, no matter how the load condition of the induction machine changes, the stator current vector can be stopped or rotated only in the forward direction, and therefore only forward commutation is considered for the inverter. This has the advantage that the control circuit has a very simple structure and is easy to design and manufacture.

[Brief explanation of the drawing]

Figure 1 is an explanatory diagram of the vector control operation of an induction machine using a current source inverter, where a is a connection diagram between the current source inverter and the induction machine, b is an explanatory diagram showing the movement of the stator current vector, and c
is an explanatory diagram showing the commutation sequence of the inverter corresponding to diagram b, FIG. 2 is a motor drive circuit diagram to which the present invention is applied,
Fig. 3 is a block diagram showing the main configuration of the phase adjuster according to the present invention, Figs. 4 and 5 are vector diagrams for explaining vector control of an induction machine, and Figs. 6 and 7 are diagrams showing the main configuration of the phase adjuster according to the present invention. FIG. 8 is a block diagram showing another embodiment of the present invention. 1... Current controller, 2... Input command signal, 3, 4... Condition, 5... Three-phase AC power supply, 6... Rectifier, 7... Current detector , 8...Adjuster, 9
...Control signal, 10...Error detector,
11...Error signal, 12...Error amplifier, 13
...Error amplification output, 14... Rectification controller,
15...Ignition signal, 16...DC reactor, 17...Inverter, 18, 19, 20.
...Output terminal, 21...Induction machine, 22...
...Pulse oscillator, 23...Rotation angle frequency signal, so
24...Rotation speed command device, 25...Command signal, 26...Vector calculator, 27...
・Torque angle command signal 8s2, 28...Rotation angle frequency command signal r', 29...Slip angle frequency command s,', 30...Phase calculator, 31...
...Stator current vector phase command signal 8, 32
... Advance pulse day, 33 ... Phase adjuster, 34 ... Main circuit phase command 8. ,,35...
...Phase command device, 36...Inverter controller, 37.
...Fixed Viscount flow phase controller, 38...Pulse synthesis circuit, 39...'o of excitation current vector angular frequency signal, 40...Counter, 41... ...
Excitation vector phase signal oo, 42...adder,
43... Advance pulse oscillator, 44... Comparator, 45... Comparator output, 46... Gate circuit, 47... Terminal, 48 ......Counter, 49...Comparator output, 50...Inverter, 51...Inverter output, 52...Gate circuit, 53...Composition circuit . Article 1 Business Figure 2 Figure 4 Figure 3 Figure 5 Figure 6 Figure 7 Figure 8

Claims (1)

[Claims] 1. In a vector control device that controls the stator current vector of an induction machine using a frequency converter, a comparator that uses the phase command of the stator current vector as one comparison input, and a frequency that the phase command of the stator current vector has. A gate circuit that receives a pulse train signal of a higher frequency as input and controls the passage of the pulse train signal using the output of the comparator, counts the signal that has passed through the gate circuit, and applies the counted output to the other comparison input of the comparator. and a counter that outputs an actual phase command of the stator current vector, and the comparator compares the phase command of the stator current vector with the output of the counter and determines when the phase command value is larger than the count value. A vector control device for an induction machine, wherein the count value of the counter moves only in an increasing direction with respect to a phase command of a stator current vector.