JP2957222B2 - Active bearing rotor support controller - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a rotor support control device for an active bearing for reducing vibration of a rotor supported by the active bearing.

[Prior art] As a bearing for supporting a rotor or the like of a machine used at high speeds such as various turbomachines, by receiving the radial load of the rotor by an active bearing, vibration is not controlled by strict balancing but by active control. It has been studied to reduce it and thereby safely pass dangerous speeds.

An elastic rotor that rotates at a speed exceeding the critical speed,
When passing through the critical speed, there is a problem in that the rotor is bent due to a deviation between the rotation center of the rotor and the center of mass, and large vibration energy (referred to as unbalance force) is generated.

Active vibration control of the elastic rotor can be broadly classified into two types, a non-contact type and a contact type, depending on the type of actuator installation. The former is a method represented by a magnetic bearing, and the latter is a bearing housing control method. Until now, researches on the active vibration control of elastic rotors, such as the optimal regulator method, quasi-mode control method, output feedback method, and variable speed feedback method, have been conducted mainly from the viewpoint of feedback control. As a result, it was found that the output feedback method was extremely effective when it was difficult to model the elastic rotor.

FIG. 3 shows an example of a rotor support control device of an active bearing by a feedback control which is generally performed in the related art. The rotor 3 is supported in a radial direction by active bearings 1 and 2 and is rotationally driven by a motor 4. It has become so.

The active bearings 1 and 2 support the rotor 3 so that the rotor 3 can be actively controlled by actuators 5a, 5b, 5c and 5d such as electromagnets and piezoelectric elements. The position can be controlled freely.

Position sensors 6a, 6b, 6 for detecting the radial position of the rotor 3 in the X-axis and Y-axis directions are provided on the active bearings 1 and 2.
c and 6d are provided, and the position detection signals 7a, 7b, 7c and 7d are output.

Position detection signals 7a from the respective position sensors 6a, 6b, 6c, 6d,
A feedback control circuit 9 for inputting 7b, 7c, 7d and calculating and outputting feedback control signals 8a, 8b, 8c, 8d for canceling the deviation from the reference position is provided, and a feedback control signal from the feedback control circuit 9 is provided. 8a, 8b, 8c, 8d are amplified by the amplifier 10 and input to the actuators 5a, 5b, 5c, 5d of the active bearings 1, 2 to control the position of the rotor 3 in the X-axis and Y-axis directions. The controller 11 is configured to reduce the vibration of the rotor 3.

[Problems to be Solved by the Invention] However, in the above-described system in which the vibration is reduced by the feedback control, the control delay is inevitable, so that a resonance peak remains at some level near the critical speed of the rotor 3. There is a problem that a large feedback gain is required to reduce the vibration. However, increasing the feedback gain is not preferable in terms of stability of the system, which may cause automatic vibration.

The present invention focuses on the above conventional problems,
By estimating the unbalance force generated in synchronization with the rotation speed of the rotor supported by the active bearing, and performing feedforward control that cancels out the estimated value of the unbalance force in addition to the conventional feedback control, vibration It is an object of the present invention to provide a rotor support control device for an active bearing in which a critical speed is safely passed by reducing the occurrence of the critical speed.

Means for Solving the Problems The present invention provides a position sensor for detecting a radial position of a rotor that is actively controlled by an actuator of an active bearing, and receives a position detection signal from the position sensor to receive a position signal. A feedback control circuit that calculates and outputs a feedback control signal that cancels the deviation of the rotation speed, a rotation speed sensor that detects the rotation speed of the rotor, a position detection signal from the position sensor, and a rotation speed detection signal from the rotation speed sensor. And an unbalanced force estimation control circuit for estimating an unbalanced force from a disturbance synchronized with the rotation speed, calculating and outputting a feedforward control signal for canceling the estimated value of the unbalanced force, and the feedback control. The feedforward control signal of the unbalanced force estimation control circuit is used as the feedback control signal of the circuit. And an adder for adding the output to the actuator.

[Operation] When a deviation occurs in the position detection signal from the position sensor,
The feedback control circuit immediately calculates and outputs a feedback control signal that cancels the deviation, and at the same time, the unbalanced force estimation control circuit synchronizes with the rotation speed based on the position detection signal and the rotation speed detection signal from the rotation speed sensor. Estimate the unbalanced force from the disturbance that occurs, immediately calculate and output a feedforward control signal that cancels out the estimated value, and the actuator of the active bearing in which the feedback control signal and the feedforward control signal are added by an adder , The position of the rotor is controlled in a direction in which the deflection is eliminated.

As described above, by controlling the feedback control signal by adding the feedforward control signal based on the unbalance force, the vibration of the rotor is significantly reduced.

[Example] Hereinafter, an example of the present invention will be described with reference to the drawings.

The present invention, in addition to the conventional feedback control,
The feedforward control which directly cancels the unbalance force itself is applied to the control of the active bearing of the elastic rotor.

FIG. 1 shows an embodiment of the present invention, in which parts denoted by the same reference numerals as in FIG. 3 represent the same parts.

As shown in FIG. 1, the position detection signals 7a, 7b, 7c, 7d from the position sensors 6a, 6b, 6c, 6d are guided to a feedback control circuit 9 to output feedback control signals 8a, 8b, 8c, 8d. On the other hand, the position detection signals 7a, 7b, 7c, 7d are input to the unbalanced force estimation control circuit 12, and the rotation speed detection from a rotation speed sensor 13 such as a rotary encoder provided to detect the rotation speed of the rotor 3. The signal 14 is input.

In the active bearings 1 and 2, the actuators 5a, 5b, 5c, and 5d and the position sensors 6a, 6b, 6c, and 6d are arranged at controllable and observable positions, respectively. Observations can be made. At this time, the rotation speed detection signal 14 is input in order to estimate the unbalance force by focusing only on the rotation speed synchronization component.

Since it is difficult to obtain the unbalanced force itself in real time, the unbalanced force estimation control circuit 12 derives an expanded state equation by regarding a disturbance synchronized with the rotational speed, which is the unbalanced force, as a state variable. The estimated value of the unbalanced force is obtained in real time, and the feedforward control signals 15a, 15b, 15c, 15d that cancel the estimated value of the unbalanced force thus calculated are output. .

Further, feedforward control signals 15a, 15b, 15c, 15d from the unbalanced force estimation control circuit 12 and feedback control signals 8a, 8b, 8 from the feedback control circuit 9
c, 8d are added, and control signals 17a, 17b, 17c, and 17a, 17b, 17c, which are added in the adder 16 and whose signals are reversed in order to control the displacement of the rotor 3 in the direction of canceling out. 17d
Is guided to the actuators 5a, 5b, 5c, 5d via the amplifier 10 to control the support of the rotor 3.

As described above, the feed-forward control for canceling the unbalanced force by the unbalanced force estimation control circuit 12 is added to the feedback control by the feedback control circuit 9, so that the critical speed is lower than that of the conventional active bearing using only the feedback control. The effect of reducing vibration due to the unbalance force at the time of passing can be significantly improved. Thus, the rotor 3 can be rotated while safely passing the critical speed.

The feedback control is a method of designing the pole of the denominator of the transfer function at a desired position, whereas the feedforward control generates a numerator zero at a desired position. That is, if the critical speed of the denominator is canceled by the zero point of the numerator, the amplitude becomes zero even immediately below the critical speed. More specifically, the unbalanced disturbance itself is regarded as a state variable, an expanded state equation is derived, and a disturbance synchronized with the rotation speed based on the unbalance force is estimated by the unbalance force estimation control circuit 12, and then eliminated. That is, the control force to be applied is provided by feedforward.

FIG. 2 shows the result of a simulation of a steady unbalanced response in order to confirm the effect of the present invention. The poles are changed as A1, A2, A3, and A4 by adjusting the unbalanced force estimation control circuit 12 (adjusting the gain). The comparison is shown. According to FIG. 2, it is confirmed that the amplitude is zero at the set frequency, and the response is like a notch of a notch filter in the vicinity of the set frequency. In addition, a peak appears at a frequency corresponding to the imaginary part of the pole given by the unbalanced force estimation control circuit 12, and the magnitude of the peak is represented by the imaginary axis of the real part of the pole given by the unbalanced force estimation control circuit 12. It was confirmed that the distance became smaller when moving away from in the negative direction. As described above, it can be seen that the amplitude is considerably reduced in the vicinity of the rotation speed specified by the position of the pole provided by the unbalance force estimation control circuit 12.

As is usually done, in order to reduce the amplitude (vibration) only by the feedback control, the feedback gain must be increased. However, in practice, problems such as limitation due to the performance of the controller and oscillation occur, so that the magnitude of the feedback gain is limited. According to the present invention, control can be always performed with a stable gain without such a problem.

In addition, as shown in the figure, in addition to controlling the rotation speed at the time of passing the critical speed, the feedforward control signals 15a, 15
By using the variable gain method of changing the gains of b, 15c, and 15d in synchronization with the rotation speed, it is possible to increase the speed to a required rotation speed while keeping the amplitude (vibration) at zero.

Incidentally, the rotor support control device for the active bearing of the present invention is not limited to the above-described embodiment, but in the illustrated case, both ends of the rotor are supported by the active bearing. It is needless to say that the present invention can be applied to a case in which it is supported by an active bearing, and that various changes can be made without departing from the scope of the present invention.

[Effects of the Invention] As described above, according to the active bearing rotor support control device of the present invention, in addition to performing feedback control of the active bearing rotor by providing a feedback control circuit, The unbalanced force is estimated from a disturbance synchronized with the unbalanced force, and the unbalanced force estimation control circuit that outputs a feedforward control signal for canceling the estimated value of the unbalanced force is provided. As compared with the case of the control alone, the effect of reducing the vibration due to the unbalanced force at the time of passing the dangerous speed can be greatly expected, and therefore, an excellent effect of safely passing the dangerous speed can be obtained.

[Brief description of the drawings]

FIG. 1 is a block diagram of one embodiment of the present invention, FIG. 2 is a diagram confirming the effect of reducing vibration according to the present invention, and FIG. 3 is a block diagram of a conventional rotor support control device for an active bearing. 1, 2 are active bearings, 3 is a rotor, 5a, 5b, 5c, 5d are actuators, 6a, 6b, 6c, 6d are position sensors, 7a, 7b, 7c, 7d are position detection signals, 8a, 8b, 8c, 8d is a feedback control signal, 9
Is a feedback control circuit, 12 is an unbalanced force estimation control circuit, 13 is a rotation speed sensor, 14 is a rotation speed detection signal, 15a,
15b, 15c and 15d indicate feedforward control signals, and 16 indicates an adder.

Claims (1)

(57) [Claims] 1. A position sensor for detecting a radial position of a rotor supported by an actuator of an active bearing so as to be actively controllable, and a feedback control for inputting a position detection signal from the position sensor and canceling a deviation of the position signal. A feedback control circuit that calculates and outputs a signal, a rotation speed sensor that detects the rotation speed of the rotor, and a position detection signal from the position sensor and a rotation speed detection signal from the rotation speed sensor are input. The unbalanced force is estimated from the synchronized disturbance, and the unbalanced force estimation control circuit that calculates and outputs a feedforward control signal that cancels out the estimated value of the unbalanced force; The feedforward control signal of the unbalanced force estimation control circuit is added to the Rotor support control device of an active bearing, characterized in that an adder output to.