JP3704690B2 - Magnetic bearing control device - Google Patents

Description

[0001]
[Industrial application fields]
The present invention relates to a control device for a magnetic bearing that supports a rotating shaft and a mover in a non-contact manner, and particularly relates to a device that facilitates starting and stopping.
[0002]
[Prior art]
Conventionally, if the rotating shaft and mover are supported by a control-type magnetic bearing in a non-contact manner, there is no mechanical friction, so the life can be drastically increased and no dust is generated. Since many features such as large and variable support characteristics are obtained, many control-type magnetic bearings have already been put to practical use.
For example, as shown in FIG. 3, a rotor 1 is fixed to a rotating shaft, and a stator 2 is provided around the rotor 1 via a gap. The stator 2 forms two electromagnets that are orthogonal to the rotation axis and that are opposed to each other in two directions orthogonal to each other, and can obtain a supporting force in the two directions. The floating position of the rotor 1 in each direction is detected by a displacement sensor 3 provided in the vicinity of the stator 2. The signal X of the displacement sensor 3 is compared with the flying position command XS by the comparator 7 and input to the flying controller 5, and an excitation command is given to the power amplifier 4. As a result, the power amplifier 4 selectively or cooperatively supplies excitation current to the opposing electromagnet coils of each stator 2, and a magnetic attractive force is generated between the stator 2 and the rotor 1. Since the magnetic attraction force is controlled by the levitation controller 5, the rotor 1 is levitated at a designated position between the stators 2. That is, the rotating shaft is supported in a non-contact manner at a floating position designated in advance.
When this bearing is not in operation, the rotating shaft is positioned below, but the rotating shaft or the rotor 1 prevents the lower side of the rotating shaft or the rotor 1 from coming into direct contact with the stator 2 of the electromagnet. 1 is supported in contact with the auxiliary bearing.
Further, when the bearing is operating, the rotor floats in a non-contact manner at a designated position between the stators by the above operation.
When the bearing is started, the rotating shaft or the rotor floats from a lower position at once, and when the bearing is stopped, the rotating shaft or the rotor falls downward from the floating position and contacts the stator or the auxiliary bearing. Although the shock is small at the time of ascent, there is a problem that the shock is large because the rotating shaft or rotor that falls falls on the stator or the auxiliary bearing and stops at the time of stop.
[0003]
JP-A-5-223123 and JP-A-63-173518 are disclosed as methods for solving this problem.
The start / stop method disclosed in Japanese Patent Application Laid-Open No. 5-223123 is such that a command signal for mitigating the impact at the time of floating / sitting is added to the output signal of the sensor for detecting the position of the rotating shaft.
At the time of start-up, the position of the rotary shaft immediately before start-up is first stored in the memory as the initial position. Thereafter, the floating position command is first changed to the central position after the initial position is first commanded. Therefore, the rotating shaft is smoothly levitated from the lower position to the center position.
At the time of stop, the floating position command that commands the center position is gradually changed to the initial position stored in the memory, and then completely stopped. Therefore, the rotating shaft can be smoothly lowered from the central position to the initial position, and can be stopped without causing a shock. Since the position of the rotating shaft before starting is stored as the initial position, smooth starting and stopping can be similarly performed regardless of the direction in which the magnetic bearing is installed.
Japanese Utility Model No. 63-173518 provides smooth start-up by gradually changing the magnetic attraction force by changing the floating position command through a PID circuit with a temporary delay element, etc., for a predetermined period of time when starting and stopping. It will stop.
[0004]
[Problems to be solved by the invention]
However, the conventional technique disclosed in Japanese Patent Application Laid-Open No. 5-223123 requires many components such as an initial position storage memory, a D / A converter, an A / D converter, a software command unit, and a controller, which increases the cost. there were.
In the prior art of Japanese Utility Model Publication No. 63-173518, only one of the two amplifiers is given an input signal through a first-order lag element, so that the control system becomes a non-linear system as a whole, and stability is improved. There was a problem that it was severely damaged and unstable.
In addition, since the PID circuit has been operating from the beginning, the output signal is saturated immediately and becomes uncontrolled, and there is a problem that the shock cannot be eliminated.
The present invention has been made in view of these problems, and an object of the present invention is to provide a control device for a magnetic bearing that stably changes a flying position command and smoothly starts and stops.
[0005]
[Means for Solving the Problems]
In order to solve the above problem, the present invention detects a rotor fixed to a rotating shaft, a stator composed of an electromagnet provided around the rotor via a gap, and a floating position of the rotor. A displacement sensor, a power amplifier that supplies power to the stator, a proportional / differentiator, and an integrator, a levitation controller that provides an excitation command to the power amplifier, a levitation position command, and a signal from the displacement sensor And a sequencer that outputs an ON command S1 issued at a predetermined time in response to a start / stop command and an integrator ON command S2 of the levitation controller after a predetermined time from the ON command S1. In the magnetic bearing control device, the primary delay circuit for inputting the ON command S1, and the output of the primary delay circuit provided between the comparator and the levitation controller are multiplied by the output of the comparator. Said levitation It is characterized in that a multiplier for outputting the control vessel.
Further, the sequencer turns on the power after a predetermined time from receiving the start command, then sets the command S1 to Hi after a predetermined time, and sets the command S2 to Hi after a predetermined time, and then the levitation control. The integrator provided in the generator is operated to receive the stop command, and at the same time the command S1 is set to Lo, and the power is turned off after the integrator is released by setting S2 to Lo.
[0006]
[Action]
By the above means, at the time of start-up, when the start-up command is received and the commands S1 and S2 become Hi, the loop gain of the levitation control system is gradually increased by the first-order delay by the first-order lag circuit of the softening circuit, and the rotor is gradually raised In addition, since the integrator of the levitation controller operates and the deviation between the command position and the rotor position disappears, a smooth start-up operation is performed without causing an impact.
At the time of stop, when the stop command is received and the commands S1 and S2 become Lo, the integrator is released, and at the same time, the loop gain of the levitation control system is gradually reduced by the first order delay by the first order delay circuit of the softening circuit, Since the deviation from the command position increases and the rotor gradually descends, it hits the stator or auxiliary bearing smoothly without causing an impact and stops.
In addition, since the flying position command is not switched as in the prior art, there is no problem that the flying position command becomes unstable at the switching point.
[0007]
【Example】
The present invention will be described below with reference to embodiments shown in the drawings.
FIG. 1 is a block diagram showing an embodiment of the present invention.
In the figure, 1 is a rotor of a bearing fixed to a rotating shaft, 2 is a stator of a bearing constituted by an electromagnet provided around the rotor 1 via a gap, and 3 is a position of the rotor 1. A displacement sensor 4 is a power amplifier that divides an input signal into two signals, adjusts and amplifies the current, and supplies power to the opposing electromagnetic coils of the stator 2 selectively or cooperatively, and 5 is a power amplifier. 4 is a levitation controller that gives an excitation command to 4, 51 is a proportional / differentiator provided in the levitation controller 5, and 52 is an integrator. Reference numeral 6 denotes a software controller composed of a sequencer 61 and a software circuit 62. The software circuit 62 includes a temporary delay circuit 63 composed of a resistor and a capacitor, and a multiplier 64. A comparator 7 compares the flying position command XS and the signal X of the displacement sensor 3.
The sequencer 61 is configured to operate in accordance with the time chart shown in FIG. 2, and when receiving the rising signal of the start command SS, the entire control system is turned on after a predetermined time, and then for a predetermined time. Then, the ON command S1 of the software circuit 62 is set to Hi and is input to the first-order lag circuit 63. The output S3 of the primary delay circuit 63 is one input of the multiplier 64, and the multiplier 64 having the output S4 of the comparator 7 as the other input inputs the output S5 to the levitation controller 5.
After a predetermined time from setting the command S1 to Hi, the integrator ON command S2 of the levitation controller 5 is set to Hi and is input to the levitation controller 5. At this time, the integrator 52 provided in the levitation controller 5 operates when S2 is Hi, and does not operate when S2 is Lo.
Further, when receiving the falling signal of the stop command SS, the sequencer 6 sets the commands S1 and S2 to Lo and simultaneously releases the power supply of the entire control system after a predetermined time. In FIG. 1, the power supply for the entire control system is omitted.
[0008]
In such a configuration, when the start / stop command SS becomes Hi, the sequencer 61 of the software controller 6 turns on the power of the entire control system, and at a predetermined time, the command S1 is set Hi and the software circuit 62 To enter. Since the command S1 is input to the multiplier 64 with a first-order lag, the input signal S5 of the levitation controller 5 gradually increases as shown in FIG. 2, and the loop gain of the normal levitation control system is gradually obtained. Become.
Since the loop gain is small in the first stage, the bearing force of the stator 2 of the bearing is small and the rotor 1 remains positioned below. However, since the loop gain gradually increases, the bearing force gradually increases. The rotor 1 is pulled up. Finally, a normal loop gain is obtained, and the rotor 1 is raised to the vicinity of the center of the stator 2.
At this time, the command S2 of the sequencer 61 becomes Hi and the integrator 52 of the levitation controller 5 starts to operate, so that an excitation command signal S6 indicated by a solid line in FIG. And the rotor 1 is held at the command position. The excitation command signal when the integrator 52 does not operate is shown by a dotted line.
When the levitation / stop command becomes Lo, the commands S1 and S2 of the sequencer 61 are simultaneously Lo, so that the integrator 52 of the levitation controller 5 is released and at the same time, the output 3 which is one input signal of the multiplier 64. Gradually decreases with a first-order lag. At this time, the loop gain of the levitation control system gradually decreases, the output signal S4 of the comparator 7, that is, the deviation XS-X between the two input signals increases, and the rotor 1 gradually decreases. . Finally, the rotor 1 hits the stator 2 or the auxiliary bearing and stops, and then the power supply of the entire control system is released.
In this way, at startup, the integrator is operated after gradually changing the loop gain of the levitation control system, so that the excitation command rises smoothly and the rotor can be gradually raised without causing an impact. Even when stopped, the loop gain is gradually lowered to lower the rotor, so that the impact at the time of lowering can be stopped very lightly.
[0009]
【The invention's effect】
As described above, according to the present invention, when starting and stopping, since the rotor gain is gradually raised or lowered by gradually changing the loop gain of the levitation control system, smooth start and stop can be performed with little impact. It is possible to provide a control device for a magnetic bearing that can be operated at low cost and stably.
[Brief description of the drawings]
FIG. 1 is a block diagram showing an embodiment of the present invention.
FIG. 2 is a time chart showing the sequence of the embodiment of the present invention.
FIG. 3 is a block diagram showing a conventional example.
[Explanation of symbols]
1 rotor, 2 stator, 3 displacement sensor, 4 power amplifier, 5 levitation controller, 51 proportional / differentiator, 52 integrator, 6 software controller, 61 sequencer, 62 software circuit, 63 first order lag circuit, 64 multipliers, 7 comparators

Claims (2)

A rotor fixed to a rotating shaft, a stator composed of an electromagnet provided around the rotor via a gap, a displacement sensor for detecting a floating position of the rotor, and supplying power to the stator A levitation controller that provides an excitation command to the power amplifier, a comparator that compares signals of the levitation position command and the displacement sensor, and a start / stop command In response to the ON command S1 issued at a predetermined time and a sequencer that outputs the integrator ON command S2 of the levitation controller at a predetermined time from the ON command S1, a magnetic bearing control device comprising:
A primary delay circuit for inputting the ON command S1,
A magnetic bearing provided between the comparator and the levitation controller, and a multiplier that multiplies the output of the first-order lag circuit and the output of the comparator and outputs the result to the levitation controller. Control device. The sequencer turns on the power after a predetermined time from receiving the start command,
Thereafter, the command S1 is set to Hi after a predetermined time, the command S2 is set to Hi after a predetermined time, and the integrator provided in the levitation controller is operated to receive the stop command and simultaneously set the command S1 to Lo. 2. The magnetic bearing control device according to claim 1, wherein the power supply is turned off after S2 is set to Lo and the integrator is released.

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