JPS6234300Y2 - - Google Patents

Description

[Detailed explanation of the invention] This invention is a control controller that uses a one-chip integrated circuit that accommodates multiple high-performance operational amplifiers, especially for linearly amplifying the deviation (difference between the target value and the controlled variable). , a controller having an adjusting operation circuit that generates a two-position output proportional to the resulting amplified deviation signal.

In most conventional controllers, the operational amplifier for linear amplification and the operational amplifier for the two-position output adjustment operation circuit are each provided as separate integrated circuits.

However, recent trends in controllers include demands for high performance and miniaturization, and furthermore, due to diversification of purposes of use, an increase in additional functions is also required.

The above-mentioned miniaturization and increase in additional functions are requirements that are not easy to coexist, and in order to achieve both objectives, it is necessary to reduce the number of parts of the controller and simplify the electric circuit. As one of the means for achieving this, it is first proposed to employ the above-mentioned one-chip integrated circuit containing a plurality of operational amplifiers.

However, in this type of one-chip integrated circuit currently being developed, one operational amplifier is used for linear amplification, and the other operational amplifier is used as a two-position amplifier like a comparator. When used as an output (i.e., saturated output) amplifier, the output of the linear amplifier will change every time the output of the two-position output amplifier is reversed due to the internal impedance of the integrated circuit itself, the pattern configuration of the integrated circuit, etc. It was impossible to obtain a highly accurate amplifier.

Therefore, this proposal provides a simple additional circuit consisting of a resistor and a capacitor, and as mentioned above, it is possible to create an operational amplifier (in a one-chip integrated circuit with multiple built-in amplifiers, it is impossible to implement a single operational amplifier). This makes it possible to use one unit as a linear amplifier and the other as a two-position output amplifier.
That is, a feedback circuit consisting of a resistor and a capacitor is provided from the output of a two-position output amplifier to the input of another linear amplifier. The main idea will be explained below with reference to the figures.

Figure 1 shows an example of a controller using the present invention. E _i on the left side of the figure is a signal of the measured value of the controlled variable (hereinafter also simply referred to as measured value, the same applies to other cases), E _s is the control Q target value, and E _D is the difference or deviation between the measured value E _i and the target value E _s . E _A is the deviation E _D
The amplified output of E _B is the output of the present controller, which is a two-position saturated output. OP(A)
is an operational amplifier for amplifying the deviation E _D (hereinafter simply referred to as OP(A)), and OP(B) receives the output E _A of OP(A) as explained below, and receives the adjustment operation signal E _B This is an operational amplifier (hereinafter simply referred to as OP(B)) that generates . OP is a one-chip integrated circuit with built-in operational amplifiers OP(A) and OP(B). +V and -V are power supplies for OP, that is, common power supplies for operational amplifiers OP(A) and OP(B), and M is a deviation indicator. R ₁ , R ₂ , R ₃ , R ₄ , R ₅ , R ₆ , R ₇ ,
R _A , R _B , and _RC are resistors, and C ₁ and C _A are capacitors.

The deviation E _D between the measured value E _i and the target value E _s is added to the + side input terminal of the operational amplifier OP(A). In addition, the output E _A of OP(A) is connected to the resistor R ₁ and the side input terminal.
The voltage is divided by _R2 and fed back. The output E A of the operational amplifier OP (A) is applied to the side input terminal of the operational amplifier OP (B) via the resistor R ₃ , and the output E _B of the operational amplifier OP (B) is applied to the _side input terminal of the operational amplifier OP (B). It is fed back through resistor _R4 . Further, the output E _B is fed back to the side input terminal of the operational amplifier OP(B) via a circuit provided with a first-order delay element consisting of resistors R ₅ , R ₆ , R ₇ and C ₁ .

Next, for convenience of explanation, a portion C surrounded by a dotted line in FIG. 1 will be explained separately as shown in FIG. 2. The operational amplifier OP(A) uses the measured value E _i and the target value E _s
This is a so _- called linear amplification of the output E _A in which the low level deviation E _D from _the
This deviation value is displayed by a deviation indicator M connected to the output of OP(A).

Operational amplifier OP (B) has an operational amplifier at the side input terminal.
The output E _A of OP(A) is applied via the resistor R ₃ , and at the same time the output E _B is fed back positively via the resistor R _4. If the amount of positive feedback is E _M , then there is a hysteresis width (dead band) of 2E _M. occurs. Further, negative feedback is provided from the output E _B to the side input terminal of the operational amplifier OP(B) via a circuit provided with a first-order lag element consisting of resistors R ₅ , R ₆ , R ₇ and a capacitor C ₁ . At this time, let E _N be the amount of negative feedback consisting of resistors R ₅ , R ₆ , and R ₇ when C ₁ is removed, and adjust the resistance so that the condition E _N > E _M is satisfied.
Determine the values of R ₃ , R ₄ , R ₅ , R ₆ , and R ₇ , and calculate the amount by which the output E _A of OP(A) is applied to the side input terminal of OP(B) via the resistor R ₃ by E _A ′ _, if E _A ′ is within the range |E _{N −E M} It becomes a two-position output, that is, the output E _B of the operational amplifier OP(B) becomes a two-position output of pulse width modulation proportional to the output E _A (deviation signal) of the operational amplifier OP(A), so-called time It becomes a proportional action controller.

FIG. 3 shows the operation of each part when E _i =E _s , that is, the deviation signal E _D is 0. Figure a is OP
Output E _B of (B) is a sharp rising pulse output with two saturated outputs of either negative or positive polarity. Figure b is the output E _A of OP(A). Originally, E _A is the output of E _D multiplied by K, so E
When _D = 0, E _A = 0, but with only the circuit shown in Figure 2, the waveform as shown in Figure 3b, due to the internal impedance of the one-chip integrated circuit OP itself, the pattern configuration of the integrated circuit, etc. That is, figure a
+△E _A , - of the characteristics delayed by △t with respect to t ₁ , t _{2 of}
The output fluctuates by △E _A , and E _A does not become 0, resulting in a deviation error. Therefore, the time proportional operation of OP(B) itself becomes abnormal, and it is impossible to perform normal adjustment operation. be.

Therefore, the gist of this invention is as shown in Figure 1.
The above-mentioned drawbacks are attempted to be eliminated by adding circuits outside the dotted line frame in the figure, and the principle thereof will be explained below.

Error due to fluctuation of output E _A of operational amplifier OP(A) ±
When △E _A is converted to the input value ±δE _A of OP(A), it becomes ±δE _A = ±△E _A /K (K is the closed loop gain of OP(A)). Therefore, it is synchronized with the fluctuation of the output E _A By feeding back a value equal to ±δE _A to the input of OP(A), the above error ±ΔE _A can be eliminated.

FIG. 1 shows an embodiment of a controller using the present invention. In Fig. 1 (the part C surrounded by the dotted line) is exactly the same as in Fig. 2, but in addition to this, the output of the operational amplifier OP(B) is connected to the resistors R _A , R _B , R _C capacitor C The above objective is achieved by adding a circuit for feeding back _A to the side input terminal of OP(A).

In other words, the resistance R of the output E _B of the operational amplifier OP(B)
If the voltage is divided by _A , R _B , R _C , R ₁ and the value is E _f , then if the voltage division ratio is determined so that ±E _f = ±δE _A , then E _f is the input terminal on the OP(A) side. Therefore, E _A =±△E _A −K(±E _f )=0
(However, when E _i =E _s ). The waveform A in c of FIG. 3 is a diagram of the operation of E _f . However, in reality, ±△E _A occurs with a delay of △t from the rising point of the output E _B at t ₁ and t ₂ , so the output E _A
A large pulse-like waveform is generated during the transition period of operation.

The above operation is explained assuming that the capacitor C _A is not provided in the feedback circuit. However, if the above pulse-like waveform has an adverse effect on the operation, the feedback circuit should be changed as shown in Figure 1. If a capacitor C _A is provided and the feedback value E _f has a delay characteristic of △t, E _f will have a waveform as shown by the dotted line in c in Fig. 3, and as a result, the output E _A will be as shown in the figure. The waveform becomes as shown by the dotted line in d, and the output E _A is obtained in a nearly normal form. The value of the time constant T at this time (this CR circuit) is T=C _A・R _B・R _C /R _B +R _C (R _A ≫
It is given by the formula R _B R _C ), and it is sufficient to set T=Δt. Also, it is useful in mass production to use a variable resistor between R _B and R _C to adjust the level of E _f .

As explained above, the present controller can provide a highly reliable controller at a low cost by reducing the number of circuit elements, downsizing the instrument, reducing failure rate, and shortening production time.

[Brief explanation of the drawing]

Figure 1 is a circuit diagram of the proposed controller, Figure 2 is an explanatory circuit diagram showing part c in Figure 1, and Figure 3 is an explanatory circuit diagram of the controller according to the present invention.
The figure is an explanatory diagram showing the operating voltages of each part of the proposed circuit.

Claims (1)

[Scope of utility model registration request] A linear amplifier that uses a one-chip integrated circuit containing two or more operational amplifiers, and uses one of the operational amplifiers to amplify the deviation between the control target value and the measured value of the controlled variable. In a controller in which one operational amplifier is used as an adjustment operation circuit that generates a two-position output for control proportional to this deviation, the output due to the two-position saturation characteristic of this adjustment operation circuit is A controller characterized in that the above deviation is fed back to the input of a linear amplifier that amplifies it via a time constant circuit having a resistor and a capacitor.