JPH0667248B2 - Machine drive system shaft torsion angle estimation device - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a control device that suppresses shaft torsion vibration of a mechanical system by using a shaft torsion angle and a speed of the mechanical system as control feedback signals.

[Prior Art] It is known that shaft torsion vibration of a mechanical drive system adversely affects the response of the drive system, and a technique for preventing this is to detect the shaft torsion angle and use it as a control feedback signal. As a result, a drive system response improvement has been proposed (Japanese Patent Publication No. 59-4954).

Further, the estimation of the shaft torsion angle is described in, for example, JP-A-60-17
It is argued that it is possible to estimate the shaft torsion angle using the speed and current signals of the electric motor, as described in Figures 2 and 4 of 7906 "Roll Drive".

FIG. 3 is a block diagram of a control device that controls the speed of the machine with an electric motor. The control device includes a speed controller 41, a current controller 42,
Addition / subtraction element that consists of gate pulse generator 43, power converter 44, electric motor 45, mechanical load 46, torque transmission shaft 47, current detector 48, speed detector 49, and finds the difference between the command signal and the feedback signal It is equipped with 52, 53. The control is a well-known fact, and a description thereof will be omitted.

Reference numerals 50 and 51 in the figure are a gain / phase adjuster 50 and an axial torque detector 51 described in JP-B-59-4954.

FIG. 4 is a transfer function representation of the drive systems 44 to 47 in FIG. 3, where torque coefficient 1 and moment of inertia of the electric motor 45.
2, Comprised of integral element 3 of speed difference between electric motor 45 and mechanical load 46, shaft torque coefficient 4, moment of inertia of mechanical load 46, electric circuit transfer function 61 of power converter 44 to electric motor 45, counter electromotive force coefficient 62 6-8 and 63 are subtraction elements for connecting blocks. Further, T _L in the figure is a load torque applied to 46.

Figure 5 shows the estimated value of shaft torsion angle θ. And estimated mechanical load speed ω ₂ In the control block diagram for subtracting, proportional elements 71 to 76,78,80
81,83 to 84,17,24, integral elements 77,79,82 and addition elements 85 to 9
2 and elements 1 to 8 described in FIG. A digital device is used to calculate these with high accuracy, but since this control block has closed loops of 77 to 84, the calculation time deviation and calculation error due to the adoption of the previous value peculiar to the digital device are reduced. A sampling period of 1/5 to 1/10 of the closed loop response time constant is required. In Figure 3, the closed loop is In this way, three stages of integration elements pass, so the practical sampling cycle is 3 of the response time constant (1/5 to 1/10).
You have to ride. Therefore, a high-speed sampling digital device is required to achieve high precision and high response.

[Problems to be solved by the invention]

In the above, the following conventional techniques have not been considered in the structure of the device.

First, the former conventional technique has the following problems.

(1) Since the shaft torque detecting device is expensive, its use in producing an economical advantage is limited.

(2) Addition of hardware causes maintenance work. The latter conventional technique has the following problems, although the former has been considered.

(1) Since the control block is composed of a plurality of closed loops, high-speed sampling is required to perform high-accuracy and high-response arithmetic, so a dedicated processor must be provided.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a machine drive system shaft torsion estimation device capable of performing highly accurate and high response calculation with low speed sampling without requiring high speed sampling.

[Means for solving problems]

To achieve the above object, in the present invention, a mechanical system driving electric motor, a machine driven by the electric motor via a drive shaft, a current detector for detecting a current of the electric motor, and a speed of the electric motor are detected. A mechanical drive system including a speed detector, the detection value detected by the current detector, the detection value detected by the speed detector, and a predetermined moment of inertia of the electric motor, In a machine drive system shaft torsion angle estimating device for estimating at least one of a shaft torsion angle of the drive shaft and a speed of the machine from a predetermined moment of inertia of the machine and a spring constant of the drive shaft, The mechanical drive system shaft torsion angle estimation device captures each of the detection value detected by the current detector and the detection value detected by the speed detector to obtain a plurality of detection values. A circuit for estimating a shaft twist angle of the drive shaft by providing a secondary delay element, combining an proportional element corresponding to an output value of the primary delay element and an addition element for adding an output value of the proportional element in an open loop. A circuit for estimating the speed of the machine by combining the proportional element corresponding to the output value of the first-order lag element and the addition element for adding the output signal of the proportional element in an open loop. It is characterized by that.

[Action]

The present invention realizes a simple open loop block by utilizing a parameter that decomposes the higher-order equation into a lower-order equation, that is, a first-order lag element and a proportional element.

〔Example〕

Hereinafter, embodiments of the present invention will be described with reference to the drawings, but before that, a theory adopted in the embodiments of the present invention will be described. The means for expanding the closed loop block shown in FIG. 5 into the open loop block will be described below. A determinant is used to simplify the expression of the relational expression. Note that ω ₁ is the angular velocity (rad / sec) of the electric motor, and Ia is the torque current (A) of the electric motor.

However, Z _{1 to} Z ₃ are outputs of the elements 77, 79, 82. Formula (1)
Is expanded to convert Z _{2 to} Z ₃ into the relational expression of ω ₁ and Ia, here, given that, Where e ₁ = b ₃ …… (10) e ₂ ＝ a ₃ b ₅ …… (11) e ₃ ＝ a ₃ a ₄ b ₁ …… (12) e ₄ ＝ b ₄ …… (13) e ₅ = a ₃ b ₆ (14) e ₆ = a ₃ a ₄ b ₂ (15) Becomes

Further, according to the known example, a _{1 to} a ₅ in the formula (3) are And l, m, n can be arbitrarily determined by response parameters for calculating the estimated value, and the others are parameters shown in FIG.

Substituting equations (17) to (21) into equation (7), Becomes When the above cubic equation is decomposed into the product of linear equations, if Δ = (s + p ₁ ) (s + p ₂ ) (s + p ₃ ) ... (23), And can be decomposed into products of arbitrary linear expressions by the values of l, m, and n. From the above, if we decompose equation (16) into a linear equation, Can be Where c _{1 to} c ₆ are Is.

In addition, Z ₃ can be decomposed into a linear equation in the same manner, Where f ₁ = b ₅ …… (36) f ₂ ＝ a ₅ b ₃ −a ₂ b ₅ ＋ a ₄ b ₁ …… (37) f ₃ ＝ a ₁ a ₄ b ₃ −a ₂ a ₄ b ₁ …… (38) f ₄ ＝ b ₆ …… (39) f ₅ ＝ a ₅ b ₄ −a ₂ b ₆ ＋ a ₄ b ₂ …… (40) f ₆ ＝ a ₁ a ₄ b ₄ −a ₂ a ₄ b ₂ …… (41) Becomes Decomposing this into a linear equation like Z ₂ , Becomes Where d _{1 to} d ₆ are Is.

In other words, by doing the above, what was a closed loop as shown in FIG. 5 can be converted into an open loop.

An embodiment of the present invention will be described below with reference to FIG.

FIG. 1 shows elements 11 to 16 and 18 to 18 by using the methods of the equations (27) to (33) and the equations (43) to (49) described above for the element numbers 71 to 90 described in FIG. It is converted to 23 and 25-36. Where 11-16 are first-order lag elements, 18-23 and 25-
30 is a proportional element and 31 to 36 are addition elements.

All the above calculation elements are implemented by a digital calculation device (not shown). Further, 1 to 8, 17, 24, 91 to 92 are the same as those in FIG.

Further, the relationship between 11 to 16 in FIG. 1 and the equations (27) and (43) is as follows. Is. Based on the above relationships, a concrete method of achieving equations (27) and (43) will be described.

First, equation (27) is Substituting equations (50) to (52) into this and removing the cuts, Becomes The numerical value in the circle in the equation (53) is the same as the element No. in FIG. Similarly, the equation (43) can be decomposed into the equation (53), and can be constituted by the elements 11 to 16, 25 to 30, and 34 to 36 in FIG.

FIG. 2 is an estimated value of the shaft torsion angle θ of the present invention shown in FIGS. FIG. 3 is a comparison diagram of the response and accuracy of FIG. As described above, since the embodiment of the present invention is an open loop, there is no error accumulation, so that it substantially matches the shaft torsion angle θ.

Although the proportional elements 18 to 20 and 21 to 23 are provided after the primary delay elements, the proportional elements 18 to 20 and 21 to 23 are the delay elements 1
It may be provided before 1 to 16.

According to the present embodiment, the comparison of the sampling period with the conventional technique is the comparison of the number of stages of the integral element (the first-order lag is also equivalent in sampling time). Therefore, (a) the conventional technique: three stages sampling period = response time constant X (1/5 to 1/10) ³ (b) Example of the present invention: 1 stage Sampling period = Response time constant x (1/5 to 1/10) ¹ Therefore, there is a difference of 25 to 100 times. .

Although the present invention has been described using the electric current, it is needless to say that the same effect can be obtained by using the generated torque that is proportional to the electric current.

〔The invention's effect〕

According to the present invention, the estimated value of the shaft torsion angle θ And estimated mechanical load speed ω ₂ Since the calculation of can be performed in the open loop without using the closed loop, the following effects can be obtained.

(1) High response estimation calculation can be performed even at low speed sampling.

(2) Since it is not in a closed loop, the calculation time deviation and the calculation error due to the adoption of the previous value peculiar to the digital calculation are small.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of the present invention, FIG. 2 is a diagram showing comparison of estimated values, FIG. 3 is a block diagram showing a configuration example of a controller, and FIG. 4 is a drive system control. A block diagram and FIG. 5 are block diagrams of calculation control of estimated values. 1 …… Torque coefficient, 2 …… 45 moment of inertia, 3 ……
Integral element, 4 ... Axial torque coefficient, 5 ... 46 Moment of inertia, 6-8 ... Subtraction element, 11-16 ... First-order lag element,
17 to 30 ... proportional element, 31 to 36 ... addition element, 41 ... speed controller, 42 ... current controller, 43 ... gate pulse generator, 44 ... power converter, 45 ... electric motor, 46 …… Machine load, 47 …… Torque transmission shaft, 48 …… Current detector, 49 …… Speed detector, 50 …… Gain / phase adjuster, 51 …… Axis torque detector, 52 to 53 …… Addition / subtraction Element, 61 ... Electric circuit transfer function, 62 ... Counter electromotive force coefficient, 63 ... Subtraction element, 71 to 76,78,
80〜81,83〜84 …… Proportional element, 77,79,82 …… Integral element, 8
5-92 …… Additional element.

Claims (1)

[Claims] 1. A mechanical system driving electric motor, a machine driven by the electric motor via a drive shaft, a current detector for detecting a current of the electric motor, and a speed detector for detecting a speed of the electric motor. A machine drive system comprising: a detection value detected by the current detector, a detection value detected by the speed detector, a predetermined moment of inertia of the electric motor, and a predetermined value of the machine. In the mechanical drive system shaft torsion angle estimation device that estimates at least one of the shaft torsion angle of the drive shaft and the speed of the machine from the moment of inertia and the spring constant of the drive shaft, the mechanical drive system shaft torsion The angle estimation device takes in each of the detection value detected by the current detector and the detection value detected by the speed detector, and each detection value is provided with a plurality of first-order lag elements. A circuit for estimating the shaft torsion angle of the drive shaft by combining an proportional element corresponding to the output value of the primary delay element and an addition element for adding the output value of the proportional element in an open loop; and an output of the primary delay element A circuit for estimating the speed of the machine by combining the proportional element corresponding to the output value and an addition element for adding the output signal of the proportional element in an open loop System shaft torsion angle estimation device.