JPS6277605A - I-pd control circuit - Google Patents

Abstract

PURPOSE:To eliminate overshooting in integral-proportional plus derivative (I-PD) control by maximizing a manipulated variable command in an integrating capacitor when the manipulated variable command exceeds a maximum manipu lated variable slightly. CONSTITUTION:A limiter 7 outputs an expression I with the limiter of a manipu lated variable command ir. A level decision circuit 8 outputs a pulse the moment the manipulated variable command ir satisfies an equation II. An integrating capacitor charging circuit 9 charges the capacitor in an integration circuit 1 every time the pulse is outputted by the level decision circuit 8 so that a voltage shown by an expression III is obtained. When there is an input r' at time t0, the command is saturated a time t1 later with the expression I and the manipulated variable command ir' is set to imax at the time of the equation III, so that a linear range is entered at time t2.

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention relates to an integral-proportional-derivative (I-PD) control circuit and an integral-proportional B-p) control circuit that have saturation characteristics in manipulated variables or components. .

[Conventional technology]

FIG. 4 is a block diagram of a conventional example of this type of integral-proportional differential control circuit (if K2 = 0, it becomes an integral-proportional differential control circuit).
From the outputs of the integral action circuit 1 which integrates the deviation e of the control amount Set the manipulated variable command value ir to edτ- of the proportional operation circuit 2, and set 2x to X-.
element 4 with saturation characteristics (i r++ax, -i ra layer! are the maximum and minimum manipulated variables, respectively), which inputs the manipulated variable i and outputs the manipulated variable i, and inputs the manipulated variable i and outputs the controlled variable
It consists of a controlled object 5 (Gp(S) is a transfer function of the controlled object) that outputs.

The saturation characteristic of the element 4 is representative of the saturation characteristic of the controlled object or the integral operation circuit 1. When the controlled object has no zero point, the closed loop transfer field number Gp(S) in Fig. 4 also has no zero point, which is an advantage over the proportional-integral (PI) control circuit and provides better operating characteristics. be able to.

[Problem that the invention seeks to solve]

However, normally, the manipulated variable i has a saturation characteristic as shown by element 4 in FIG. For example, in a motor control system, maximum current (=maximum torque) and maximum speed correspond to such saturation characteristics.

In a system with such saturation characteristics, the deviation e is large,
Once ir > imax, the manipulated variable i is suppressed to the value i = i wax due to its saturation characteristic, but
Since the output of the operation circuit 1 continues to increase by vX, the manipulated variable command value ir will rapidly increase. For this reason,
Even after the controlled amount It turns out.

FIG. 5 is a diagram showing an example of a response to a step-like command in a conventional I-PD control circuit.

Assume that step input r is input at time t0. At first, the deviation e = r - Since r<X and the deviation e is positive, the integral capacitor continues to be charged in the positive direction even though the manipulated variable i is saturated, and as a result, the manipulated variable command value ir also continues to increase.

Then, after time L2, the deviation e becomes negative, so the manipulated variable command value ir begins to decrease, and finally shifts from the saturation level to a linear region, that is, a non-saturation level, at time t3, but at time t4, the controlled variable produces a maximum overshoot Z and finally reaches a steady state at time t5.

An object of the present invention is to provide an integral-proportional-differential control circuit and an integral-proportional-differential control circuit that eliminate overshoot that occurs after a manipulated variable or an element with saturation characteristics is saturated and improve transient response. .

[Means for solving problems]

The I-PD control circuit of the present invention inputs the operation amount command signal ir, and the maximum operation amount in the negative direction and the positive direction is irm.
ax-, i rmax+, and a manipulated variable command signal ir which is an input signal of the limiter, ir≧i
rrmax+++δ or ir<-i r+5ax--δ
(When δ becomes a small positive value), the integrating capacitor is disconnected from the circuit, and the voltage V becomes V=+irmax+ +K1*X +K2*X (
When ir > O) = −irmax−+K1*X +K2*X (ir
<0 (7)) However, X: Controlled amount X: Time differential value Kl of controlled amount X,
(2) The present invention is characterized by comprising a control circuit that charges the integrating capacitor with electric charge so as to maintain a constant value and connects the integrating capacitor to the circuit again.

[Effect]

FIG. 3 is a diagram showing an example of a response to a stepped human input ir in the I-PD control circuit of the present invention.

Assume that the step input r is input at time to. After time t1, i'r≧i rmax+ and the manipulated variable command i'r is saturated at the maximum value i rmax+K.
The manipulated variable command i'r is set to the maximum value i rmax now at the time when i'r= i rmax++δ, and since δ is sufficiently small, the manipulated variable command ir does not become excessive and is set at time t2 in a preferable manner. enters the linear region at ,
The control amount X provides an ideal response without causing overshoot.

〔Example〕

Embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a block diagram of one embodiment of the I-PD control circuit of the present invention. Elements with the same symbols and numbers as in FIG. 4 indicate the same elements.

The limiter 7 is a limiter for the manipulated variable command ir (ir + ax is the maximum output), and when l i r l < irmaxc7), i '
When r= i rlirl≧i rmax, i 'r
= i rmax output i'r.

The level determination circuit 8 determines that the operation amount command ir is 1irl=ir
A pulse is output at the moment when max+δ is reached. Here, δ is a small positive value, and is selected to be small enough not to cause a response delay in the control system. The integral capacitor charging circuit 9 charges the integral capacitor in the integral operation circuit l to V = + i rmax + KIX every time a pulse is output from the level determination circuit 8.
+K2X (when i r > 0) = −i rm
ax+KIX+K2X (when i r < 0)
Charge the voltage so that it reaches the voltage.

Figure 2 is a circuit diagram of a specific example of the I-PD control circuit in Figure 1 (
However, the element 4 and the operational amplifier 5 are not shown). In FIG. 2, elements having the same numbers and symbols as those in FIGS. 1 and 4 indicate the same elements.

The maximum operation amount command i rmax is set by the variable resistor 21.
It is set so that i rmax≦i wax. The limiter 7 includes a resistor R1 operational amplifier 17. It is composed of a diode bridge 18, and its output i'r is the maximum operation amount ±i
Limited to within rmax. The absolute value circuit 23 outputs the absolute value 1irl of the manipulated variable command ir. Variable resistor 25
The value of δ is set by . The adder 26 (i r++
+ax+δ) is output. The comparator 24 is (i r
+++ax+δ) and l1rl, (i r+sa
Low level when x+δ)>1irl, (i r+++
When ax+δ)≦1irl, a high level signal is output. The monostable multivibrator 24 is a comparator 24
1 at the moment the output changes from low level to high level.
Outputs two positive pulses. That is, l ir 1<
From the state of (irmax+δ), 1irl≧(irm
A pulse is output at the moment of transition to the state of ax+δ). The comparator 19 determines the sign of the manipulated variable command ir, and outputs a control signal a that is high level when ir≧O and low level when ir<O. In the analog switch 20, when the control signal a is at a high level, the terminals TI and T2 are connected, and the maximum operation amount command i rmax is input to the adder 16, and when the control signal a is at a low level, the terminals T3 and T2 are connected. The maximum operation amount command -imax is input to the adder IB. In other words, the output V of the adder 16 is V = + i rmax + KIX + K2X (i
r≧0)V=-ir+++ax+KIX +K2X
(ir<O). Analog switch 13.14
is the output signal of the monostable multivibrator 27. When the control signal is low level, it is connected to terminals T1-T2.
When the control signal is at high level, the terminals T2 and T3 are connected, and the integrating capacitor 12 is connected between the output of the adder 16 and ground. connected to, and once disconnected from the circuit, ■=±i, rmax+KIX+K
After being charged to a voltage of 2X, it is connected to the circuit again by analog switches 13 and 14.

As described above, the manipulated variable command ir is l'irl≧i rm
At each instant when ax+δ, the integrating capacitor 12 increases ±
Since it is charged at i rmax + KIX + K2X (+ when ir≧O, - when ir < O),
The manipulated variable command ir is set to the maximum manipulated variable command ±irmax (symbols are the same).

Note that when the integrating capacitor is disconnected from the operational amplifier, a sudden change in output voltage occurs because the operational amplifier operates with a large release gain. If such saturation is undesirable, connect a sufficiently small auxiliary capacitor in parallel with the integrating capacitor, and leave this auxiliary capacitor connected to the operational amplifier even when the integrating capacitor is disconnected from the operational amplifier. Just leave it there.

〔Effect of the invention〕

As explained above, the present invention is capable of controlling the manipulated variable command by charging the integrating capacitor with such a charge that the manipulated variable command just exceeds the maximum manipulated variable when the manipulated variable command slightly exceeds the maximum manipulated variable. This has the effect of preventing overshoot after saturation and improving the transient response characteristics of the control system.

[Brief explanation of drawings]

1 is a block diagram showing an embodiment of the I-PD control circuit of the present invention, FIG. 2 is a circuit diagram of a specific example of the I-PD control circuit of FIG. 1, and FIG. 3 is a block diagram showing an embodiment of the I-PD control circuit of the present invention. A diagram showing an example of a response to a step-like command in a PD control circuit, FIG. 4 is a block diagram of a conventional example of an I-PD control circuit, and FIG. 5 is a response to a step-like command in a conventional I-PD control circuit. It is a figure showing an example. 1... Integral operation circuit, 2... Proportional operation circuit, 3.
... Differential operation circuit, 4... Element having saturation characteristics. 5... Controlled object, 6... Differential element, 7...
・Limiter, 8...Level judgment circuit, 9...
- Integral capacitor charging circuit.

Claims (1)

[Claims] In an I-PD control circuit that has saturation characteristics in the manipulated variable or circuit elements and is composed of an operational amplifier, a resistor, and a capacitor, a manipulated variable command signal ir is input, and A limiter whose maximum operation amount is irmax^- and irmax^+, respectively, and an operation amount command signal ir which is an input signal of the limiter,
ir≧irmax^++δ or ir<-irmax^
− When it reaches -δ (δ is a small positive value), the integrating capacitor is disconnected from the circuit, and the voltage V becomes V=+irmax^+ +K_1・X+K_2・X(i
When r>0) =-irmax^- +K_1・X+K_2・X(ir
<0) However, X: Controlled amount X: Time differential value K_1 of controlled amount X
, K_2: An I-PD control circuit characterized by comprising a control circuit that charges the integration capacitor with electric charge so as to maintain a constant value, and connects the integration capacitor to the circuit again.