JPS6264284A - Signal switching circuit - Google Patents

Abstract

PURPOSE:To switch a speed control to a current control or vice versa shocklessly by eliminating the abrupt change in the command input of a current regulator immediately before and after switching when switching the command input of the regulator. CONSTITUTION:A subtracting circuit 1 has a subtractor 11 and a polarity inverter 12 to form Y-X, X-Y from the output X of a speed regulator 7 and the output Y of a current command generator 6 and to input them to switches 21, 22. The switch 21 opens or closes the output Y-X of the subtractor 11, and the switch 22 opens or closes the output X=Y of the inverter 12. Calculators 31, 32 delay the outputs Y-X, X-Y to attenuate them. An adder 41 adds the signal X to the output Y-X of the calculator 31. An adder 42 adds the signal Y to the output X-Y of the calculator 32. A selector 5 selects either one of the adders 41, 42 and outputs the input Z of the regulator 8.

Description

[Detailed Description of the Invention] [Field of Industrial Application] This invention relates to a signal switching circuit that switches between speed control and current sterilization in, for example, a speed control system with a current control minor lube. This invention relates to a signal switching circuit.

[Conventional technology]

FIG. 6 is a block diagram showing a general example of a motor speed control system. In the figure, 6 is a current command generator, 7 is a speed regulator (AS R), 8 is a current regulator (ACR),
9 is a signal opening/closing circuit (changeover switch), 15 is a power converter, 16 is an electric motor, 17 is a current detector, 18 is a speed detector, and 19 is a speed setter. This is good (as is known, the speed control loop with the current control loop as a minor loop allows the motor 16 to pass through the power converter 15
It performs variable speed control.

By the way, in such a control system, this is not the original speed control, but current control (the purpose is to control the torque of the electric motor, but it is used when indirectly controlling the torque by using the current index 1). ) may also be used.

That is, in the same figure, when switching from speed control to current control, the command human power Z of the current regulator 8 is changed to the speed regulator 7.
The output X of the current command generator 6 is switched to the output Y of the current command generator 6. Since the current command generator output Y and the speed regulator output
This results in a sudden change in the motor current, resulting in a sudden change in torque, which adversely affects the mechanical system.

Therefore, as one of the conventional methods, there is a method in which the electric motor is once stopped and then the command human power Z of the current regulator 8 is switched from the output X of the speed regulator 7 to the output Y of the current command generator 6. This reduces production efficiency and is not necessarily a desirable method.However, as a method of switching without stopping the motor, it is possible to use a signal sudden change prevention circuit (as a substitute, a − next lag circuit). ), but this is not necessarily a good method as it reduces the coordination and stability of the control.

Furthermore, the following method is also adopted as a method when neither of the above two methods can be adopted. In other words, when switching from speed control to current control, at the same time as the switching command, the command value of the current regulator is first reduced to a light value, and after switching, it is slowly increased to the final command value, and conversely, when switching from current control to speed control, When switching, the zero hold of the speed regulator, which has been held at zero during the current control period, is released, and the current is switched as is, so that sudden changes in current depend on the control function of the current regulator.

[Problem that the invention seeks to solve]

However, this method also cannot prevent sudden changes in current during switching, and is not necessarily a satisfactory method.

Therefore, in order to eliminate the drawbacks of the conventional method, the present invention provides a switching circuit that can switch from speed control to current or vice versa without causing a sudden change in current. With the goal.

[Failure to solve the problem]

The first step calculates the difference Y-X, X-Y between the two signals X, Y.
a second subtraction circuit; a first subtraction circuit; The first one opens and closes the second mari subtraction circuit output. a second switch, and a first switch via the first switch and the second switch. The first subtractor circuit delays and attenuates the output of the second subtractor circuit. Output Y-X of the second arithmetic circuit and the first arithmetic circuit
A first addition circuit that adds signal X to , a 26th addition circuit that adds output A selection circuit is provided.

[Effect]

FIG. 1 is a main diagram that best represents the percentage fineness of this invention. In the figure, 1 is a subtracting circuit consisting of a subtracting section 11 and a polarity inverting section 12, 5, 21, 22 are signal opening/closing circuits (switches), 51, 52 are arithmetic circuits such as a first-order delay circuit, 41, 42 is the addition circuit, X is the speed regulator output, Y is the current command generator output, and 2 is the current regulator manual power.

In the same figure, when switching the command human power Z of the current regulator from the output X of the speed regulator to the output Yt of the current command generator 6, X-Y is added to Y in advance, and Yt-Y+ (X
-Y), that is, by switching after setting it as Y') is finally changed to Y. Therefore, the command power 2 of the current regulator is changed from the initial speed regulator output X to Y+(X-Y)
Then, the output of the current command generator can be switched to Y without causing a sudden change.

Similarly, when switching the command power Z of the current regulator from the output Y of the current command generator to the output X of the speed regulator, (Y-X) is added to X in advance, and X+(Y-X)=Y By creating , and setting Y-X to 0 after a predetermined delay time after switching, Z can be switched from Y to X without causing a sudden change. By doing so, it is possible to shift from speed control to current control or vice versa without abruptly changing the current.

[Embodiments of the invention]

FIG. 2 is a block diagram showing an embodiment of the present invention.

That is, Y is calculated from the output X of the speed regulator 7 and the output Y of the current command generator B through the subtractor 11 and the polarity inverter
-X and X-Y are generated and inputted to arithmetic circuits 1 and 32, such as first-order delay circuits, through switches 21 and 22, respectively.

The output of the arithmetic circuit 61 is added to X in the adder 41, and the output of the arithmetic circuit 62 is added to Y in the adder 42. Both signals become the command manual power Z of the current regulator 8 through switches 51 and 52, respectively.

Now, the command manual power Z of the current regulator 8 is converted to the output X of the speed regulator 7.
Let us consider the case where the output Y of the current command generator 6 is switched.

When the commanded human power Z of the current regulator 8 is to be the output X of the speed regulator 7, the switches 21.52 are off and the switches 22.51 are on, as shown. At this time, the output of the adder 42, that is, the input of the switch 52 is Y+(X-Y
)-X.

Here, when switching the command human power Z of the current regulator 8 from the output X of the speed regulator 7 to the output Y of the current command generator B, the switch 21.52 is turned on and the switch 22.51 is turned off. This ensures that the current regulator 8 immediately after switching
The commanded human power Z is switched from the original X via the switch 51 to Y+(X-Y)-X via the switch 52, but the value itself does not change. - Since the switch 22 is turned off, the output (X-Y) of the arithmetic circuit 62 converges to 0 over time, and as a result, the output of the adder 42, that is, the commanded human power Y+(X- Y) also X-
Since Y becomes 0, it converges to Y, and the switching from X to Y is completed.

In addition, when switching from Y to X, switch 22,
51 from off to on and switch 21.52 from on to off.

〔Effect of the invention〕

According to this invention, for example, in a speed control system for a variable speed motor having a speed control loop with a current control minor loop, when switching the command input of the current regulator, the command input of the current regulator does not suddenly change immediately before and after switching. This provides the advantage that it is possible to switch from speed control to current control or vice versa in a shockless manner without abruptly changing the current.

Although the switching of the command input of the current regulator has been described here, the present method can similarly be applied to general control circuits that require shockless switching between two signals.

[Brief explanation of the drawing]

Figure 1 is the main diagram that best represents the features of this invention;
The figure is a block diagram showing an embodiment of the present invention, and FIG. 3 is a block diagram showing a general example of a motor speed control system. Code explanation 1...Subtraction circuit, 11...Subtraction unit, 1
2...Polarity inversion part, 21.22.5, 51, 5
2.9...'°・Signal switching circuit (switch), 31
．． 32... Arithmetic circuit, 41.42...
Addition circuit, 6...Current command generator, 7...
...Speed regulator (ASR), ...Current regulator (
ACR), 15...Power converter, 16...
...Electric motor, 17...Current detector, 18...
...Speed detector, 19...Speed setter.

Claims (1)

[Claims] In a control system having a second control loop as a minor loop within the first control loop, the output signal (X) from the first control loop or the output signal (Y) from the command signal generation circuit is input to the second control loop. A signal switching circuit for switching these signals from one to the other and from the other to one in order to give one of them and control the other, and includes a subtraction circuit that calculates the difference Y-X between the signals X and Y, and an output of the subtraction circuit. a polarity inversion circuit that inverts the polarity of the subtraction circuit, and first and second switches that open and close the subtraction circuit output and the polarity inversion circuit output, respectively;
first and second arithmetic circuits that respectively delay and attenuate the subtraction circuit output and the polarity inversion circuit output via the switch; and a first addition circuit that adds a signal X to the first arithmetic circuit output; The output of the second arithmetic circuit includes a second addition circuit that adds the signal Y, and a selection circuit that selects either the output of the first or second addition circuit, and the output of the first addition circuit is connected to the output of the first addition circuit. When selecting, the first and second switches are opened and closed, respectively, and when selecting the output of the second addition circuit, the first and second switches are opened and closed, respectively.
, a signal switching circuit characterized in that the second switch is closed and opened, respectively.