JP2630591B2 - Control device for radial magnetic bearing - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a control device for a radial magnetic bearing.

Conventional technology and its problems Rotating body (rotor) supported in a non-contact state by magnetic bearings
In some cases, the operating speed is set to be higher than the critical speed of the rotating body in a magnetic bearing device that rotates the motor at a high speed. In this case, a problem arises when the conventional PID control device passes the critical speed. The difficulty of passing the critical speed is
It depends on the residual balance of the rotating body and the rigidity of the magnetic bearing. It is difficult to improve the residual imbalance even if the balance of the rotating body is improved, because the rotating body, which is an elastic body, is largely bent near the critical speed. For this reason, it is conceivable to increase the rigidity of the magnetic bearing, particularly the damping force. However, if the frequency characteristic is widened, the problem of saturation of the control system occurs, and the power required for the control system increases. An object of the present invention is to provide a control device for a radial magnetic bearing which solves the above problems, minimizes saturation of a control system, and provides a high damping force required for passing a critical speed.

Means for Solving the Problems A control device for a radial magnetic bearing according to the present invention is a device for controlling a radial magnetic bearing based on an output signal of a position sensor for detecting a radial position of a rotating body, A high damping force generation circuit that detects the amplitude and phase of the whirling component synchronized with the rotation speed of the rotor and generates a control signal with a phase advanced from the whirling component only in a narrow band around the rotation speed of the rotating body It is characterized by the following.

It is known that damping can be obtained by giving a vibrating body a control force with an advanced phase to the vibration, and that the damping force is maximized when the phase advance is 90 °.

By generating a high damping force with a frequency component synchronized with the rotation speed of the rotating body, it is possible to reduce whirling at a critical speed and facilitate passage at the critical speed. Also, since high damping force is generated only in a narrow band around the rotation speed,
There is no problem of saturation of the control system as in the case where the frequency characteristic is widened as in the related art.

Embodiments Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the following description, two coordinate axes of a fixed coordinate system perpendicular to a rotation axis of a rotating body (not shown) are defined as an x-axis and a y-axis.
An X axis and a Y axis are two coordinate axes of a rotation coordinate system perpendicular to the rotation axis that rotates together with the rotating body.

The control device (10) is an x-axis position sensor (11x), y
Axis position sensor (11y) and rotational speed sensor (1
2) Radial magnetic bearing for x-axis (1
3x) and the y-axis radial magnetic bearing (13y). As shown in FIG. 1, the x-axis PID control circuit (14x), the y-axis PID control circuit (14y), the high damping force Generator (15), x-axis adder (16x) and y-axis adder (1
6y). x-axis position sensor (11x)
Is for detecting the position of the rotating body in the x-axis direction and outputting a signal S1x proportional to the detected position. The y-axis position sensor (1
1y) detects the position of the rotating body in the y-axis direction and outputs a signal S1y proportional thereto. The rotation speed sensor (12) outputs a pulse signal S2 having a frequency proportional to the rotation speed of the rotating body, for example, the same frequency as the rotation speed. The x-axis PID control circuit (14x) outputs a first x-axis control signal S3x based on the output signal S1x of the x-axis position sensor (11x), and the y-axis PID control circuit (14x).
y) outputs a first y-axis control signal S3y based on the output signal S1y of the y-axis position sensor (11y). Based on the output signal S1x of the x-axis position sensor (11x) and the output signal S2 of the rotation speed sensor (12), the high damping force generation circuit (15) calculates the amplitude of the whirling component synchronized with the rotation speed of the rotating body. The phase is detected, and the second x having a phase advanced from the whirling component at a frequency corresponding to the rotation speed of the rotating body.
It outputs an axis control signal S4x and a y-axis control signal S4y. The x-axis adder (16x) includes the first and second x
The control signals S3x and S4x for the axes are added and the control signal S5x for the x-axis is output to the power amplifier (17x) of the radial magnetic bearing (13x) for the x-axis. The adder (16y) for the y-axis is It adds the first and second y-axis control signals S3y and S4y and outputs a y-axis control signal S5y to the power amplifier (17y) of the y-axis radial magnetic bearing (13y). The position sensor (1
1x) (11y), rotation speed sensor (12), PID control circuits (14x) (14y), adders (16x) (16y), power amplifiers (17x) (17y), and radial magnetic bearings (13x) (13y)
Can have any known configuration, and a detailed description thereof will be omitted.

As shown in FIG. 2, the high damping force generation circuit (15) includes a whirling component detection circuit (18) and a control signal output circuit (19).

The whirling component detection circuit (1) of the high damping force generation circuit (15)
8) is an amplifier (20), X-axis PSD (phase detector) (21
x), Y-axis PSD (phase detector) (21y), X-axis LPF (low-pass filter) (22x), Y-axis LPF (low-pass filter) (22y), waveform shaping circuit (23), and phase control circuit (24) and an x-axis position sensor (11
x) output signal S1x and rotation speed sensor (12) output signal
Based on S2, the amplitude of the whirling component synchronized with the rotation speed of the rotating body is detected.

The whirling Lissajous figure of the rotating body in the fixed coordinate system is as shown in FIG. In the figure, ω is the rotational angular velocity of the rotating body, t is time, and R is the amplitude of whirling. When the X coordinate of the rotating coordinate system is made to coincide with the whirling direction, as shown in FIG. 6, the whirling X-axis component Xo becomes the whirling amplitude R and the Y-axis component Yo becomes zero.

The whirling component detection circuit (18) obtains the whirling amplitude R based on such a principle. That is, the X-axis PSD (21x) and the X-axis LPF (22x) are composed of a signal (x-axis position signal) S6 obtained by amplifying the output signal S1x of the x-axis position sensor (11x) and a phase control circuit (24) to be described later. ), A signal S8x proportional to the swirling X-axis component Xo is output. The Y-axis PSD (21y) and the Y-axis LPF (22y) are based on an x-axis position signal S6 and a Y-axis reference signal S7y from a phase control circuit (24) to be described later, and a wandering Y-axis component Yo. And outputs a signal S8y proportional to. The waveform shaping circuit (23) outputs the output signal of the rotation speed sensor (12).
A signal (rotation speed signal) S9 obtained by shaping S2 into a square wave is output to the phase control circuit (24). Based on the output signal S8y of the Y-axis LPF (22y) and the rotation speed signal S9, the phase control circuit (24) controls the X-axis reference signals S7x and Y7 so that the whirling Y-axis component Yo becomes zero. Controls the axis reference signal S7y.

As shown in FIG. 7, the PSD switches the input signal Es with a reference signal Er which is a square wave having the same frequency as the input signal Es. The output signal Eo is obtained by multiplying the input signal Es by the reference signal Er. It will be. Then, the PSD output signal Eo
When the AC component is removed by using the LPF, only the signal component synchronized with the reference signal Er can be detected. FIG. 7A shows a case where the phase difference between the input signal Es and the reference signal Er is 0, and the signal Ep obtained by passing the output signal Eo through the LPF has a positive value. FIG. 7 (b) shows the phase difference between the input signal Es and the reference signal Er.
This is the case of 90 °, and the signal Ep obtained by passing the output signal Eo through the LPF becomes 0. FIG. 7C shows a case where the phase difference between the input signal Es and the reference signal Er is 180 °, and the signal Ep obtained by passing the output signal Eo through the LPF has a negative value. FIG. 8 shows the input signal E of the PSD.
It shows the relationship between s and the phase difference θ between the reference signal Er and the output signal Ep of the LPF.

The x-axis position signal S6 becomes the input signal Es of the PSD (21x) (21y), and the reference signals S7x and S7y become the reference signal Er. The whirling effect appears on the x-axis position signal S6, and its frequency is equal to the frequency of the rotation speed signal S9. Also, reference signals S7x, S7y
Is also equal to the frequency of the rotation speed signal S9, as described later, so that the frequency of the input signal Es of the PSD (21x) (21y) and the frequency of the reference signal Er are equal. On the other hand, the X axis and Y
The phase difference of the axes is 90 °. Therefore, the PSD for X-axis (21
If the phase difference between the reference signal S7x for x) and the reference signal S7y for the Y-axis PSD (21y) is 90 °, the X-axis LPF (22x)
And the output signal S8y of the Y-axis LPF (22y) respectively represent the wandering X-axis component Xo and Y-axis component Yo. The output signal S8y of the Y-axis LPF (22y)
That is, if the phases of the reference signals S7x and S7y are adjusted so that the Y-axis component Yo of the whirling becomes 0, the output signal S8x of the X-axis LPF (22x) indicates the wandering amplitude R.

The phase control circuit (24) performs such feedback control, an example of which is shown in FIG. FIG. 4 shows the signals of the respective parts.

The phase control circuit (24) includes an oscillator (25) that generates a clock pulse signal CLK having a constant frequency, and a first comparator (2) that determines that the output signal S8y of the Y-axis LPF (22y) is positive.
6) The second comparator (27) for determining that this signal S8y is negative, the clock pulse signal CLK of the oscillator (25) and the output signal S10 of the first comparator (26) are input signals. First
AND circuit (28), clock pulse signal C of transmitter (25)
LK and an output signal S11 of the second comparator (27) as an input signal, a second AND circuit (29), and an output signal of the first AND circuit (28) as an input signal of an up-count terminal (30u). Second A
ND circuit (29) output signal down count terminal (30d)
An up-down counter (30) as an input signal of the reset signal (31) which detects a rise of the rotation speed signal S9 from the waveform shaping circuit (23) and outputs a reset signal RS1;
A PLL multiplication circuit (32) for outputting an angle signal S12 obtained by multiplying one pulse of the rotation speed signal S9 by, for example, 1024, a reset circuit (3
A first 10-bit counter (33) which is reset by the reset signal RSI of 1) and counts the angle signal S12 of the multiplier circuit (32), an output signal S13 of the first counter (33) and an up / down counter (30) A digital comparator (34) for comparing the output signal S14 of the digital camera and the angle signal S12 of the multiplication circuit (32)
And a third AND circuit (35) that receives the output signal S15 of the digital comparator (34) as an input signal, and resets the output signal of the third AND circuit (35) by the reset signal RS1 of the reset circuit (31). The second 10-bit counter to count (3
6), the output signal Q10 of the 10th bit of the second counter (36)
Circuit (37), fourth AND circuit (48), and second counter (36) for producing X-axis reference signal S7x from
9th bit output signal Q9 and 10th bit output signal Q10
, An EOR circuit (38) for generating a Y-axis reference signal S7y from the EOR circuit.

As shown by a point A in FIG. 8, when the output signal S8y of the Y-axis LPF (22y), that is, Yo is 0, the two comparators (26) (2
7) The output signals S10 and S11 are L (Low), and the clock pulse signal CLK is not input to the up / down counter (30). Therefore, the output signal of the up / down counter (30)
S14 is constant. On the other hand, the first and second counters (3
3) (36) is reset by the reset signal RS1 synchronized with the rise (to in FIG. 4) of the rotation speed signal S9, and the first counter (33) counts the angle signal S12. While the output signal S13 of the first counter (33) is smaller than the output signal S14 of the up / down counter (30), the digital comparator (3
Although the output signal S15 of 4) is L, the first counter (33)
When the output signal S13 of the digital comparator (34) exceeds the output signal S14 of the up / down counter (30), the output signal S15 of the digital comparator (34)
Becomes H (High) (t1 in FIG. 4). Therefore, the second counter (36) starts counting the angle signal S12.
T / 2 after the second counter (36) starts counting
After the elapse of (T is the cycle of the rotation speed signal S9), the output signal Q10 of the 10th bit changes from L to H (t2 in FIG. 4).
It changes as shown in the figure. The output signal S16 of the NOT circuit (37) for inverting the signal Q10 changes as shown in FIG. Then, this signal S16 and the output signal S15 of the digital comparator (34) are output.
Is input to the fourth AND circuit (48), so that the fourth
As shown in the figure, the rotation speed signal S9, ie, the x-axis position signal
An X-axis reference signal S7x having the same frequency as S6 is obtained. The ninth bit output signal Q9 of the second counter (36) is
It changes as shown in the figure. Then, by inputting this signal Q9 and the 10th bit output signal Q10 to the EOR circuit (38),
X-axis reference signal S7x and Y-axis reference signal S7y with a phase difference of 90 °
Is obtained.

When Yo becomes positive as shown by point B in FIG. 8, the output signal S10 of the first comparator (26) becomes H, and the clock pulse signal CLk rises through the first AND circuit (28). To input to the up-count terminal (30u) of the down counter (30), the output signal S14 of the up-down counter (30)
growing. Therefore, the time (t1−t0) from when the rotation speed signal S9 rises to when the X-axis reference signal S7x rises becomes longer. This means that the phase difference between the reference signals S7x and S7y with respect to the rotation speed signal S9 has increased, and Yo approaches point A, that is, O from point B. Conversely, point C in FIG.
When Yo becomes negative, as shown by, the output signal S11 of the second comparator (27) becomes H, and the clock pulse signal CLK becomes the second AN.
Since the signal is input to the down-count terminal (30d) of the up-down counter (30) through the D circuit (29), the output signal S14 of the up-down counter (30) becomes small. Therefore, after the rotation speed signal S9 rises, the X-axis reference signal
The time (t1-t0) until S7x rises is shortened. This means that the phase difference between the reference signals S7x and S7y with respect to the rotation speed signal S9 has decreased, and Yo approaches point A, that is, O from point C.

In this way, the phase control circuit (24) controls the X-axis reference signal S7x and the Y-axis reference signal S7y so that Yo becomes 0, and as a result, as described above, the X-axis LPF (22x ), The amplitude R of the rotation of the rotating body is detected.

The control signal output circuit (19) of the high attenuation generation circuit (15)
The phase ωt of the whirling component of the rotating body is detected, and a predetermined angle φ is obtained from the whirling component at a frequency corresponding to the rotation speed of the rotating body.
It outputs a second x-axis control signal S4x and a y-axis control signal S4y advanced in phase only by detecting the rising of the X-axis reference signal S7x and resetting the reset signal as shown in FIG. A reset circuit (47) that outputs RS2 and a third 10-bit counter (39) that is reset by the reset signal RS2 and counts the angle signal S12 are provided. The angle signal S12 is a pulse signal obtained by dividing the cycle T of the rotation speed signal S9 by, for example, 1024. The cycle T of the rotation speed signal S9 is the same as that of the X-axis position signal S6 and the X-axis reference signal S7x. The output signal S17 of the counter (39) represents the whirling phase ωt of the rotating body. The control signal output circuit (19) has four tables (40
a) (40b) (40c) (40d) and four corresponding multiplier type D / A converters (41a) (41b) (41c) (41d) are provided. In the first table (40a), the output signal S17 of the third counter (39), that is, for example, 1
For the value of 024, the value of cos φ · cos ωt is stored. Similarly, the second table (40b) has sin φ · sin
The value of ωt, cos φ · sin ω in the third table (40c)
The value of t, the fourth table (40d) contains sin φ · cos ωt
Is stored. And a third counter (39)
Each table (40a) (40b) based on the output signal S17 of
The data in (40c) and (40d) are stored in the latch circuit (42
a) corresponding multiplier type D / via (42b) (42c) (42d)
It is sent to A converters (41a) (41b) (41c) (41d). The four latch circuits (42a) (42b) (42c) (42d) are controlled by a latch pulse generation circuit (43) that generates a latch pulse synchronized with the angle signal S12. Further, the output signal S8 of the LPF (22x) for the X axis of the whirling component generation circuit (18)
Signal (swirling amplitude signal) S obtained by amplifying X with an amplifier (44)
18 is input to the four multipliers (41a) (41b) (41c) (41d). As a result, in the first multiplier (41a), for the whirling phase ωt that changes every moment, Xo · cos φ · co
sωt is calculated and output. Similarly, in the second multiplier (41b), Xo · sin φ · sin ωt, and in the third multiplier (41b)
In (c), Xo · cos φ · sin ωt is calculated, and in the fourth multiplier (41d), Xo · sin φ · cos ωt is calculated and output. First
The output signal S19 of the multiplier (41a) and the second multiplier (41b)
Is input to the subtractor (45), and the output signal S21 of the third multiplier (41c) and the output signal S22 of the fourth multiplier (41d) are input to the adder (46). Output S of subtractor (45)
4x (= Xo · cos φ · cos ωt−Xo · sin φ · sin ωt)
Is the output S4y (= X) of the adder (46) as in the following equation (1).
o · cos φ · sin ωt + Xo sin φ · cos ωt) can be rewritten as the following equation (2).

S4x = Xo · cos (ωt + φ) (1) S4y = Xo · sin (ωt + φ) (2) Therefore, these output signals S4x and S4y have a phase corresponding to the rotation of the rotating body by an angle φ. It is an advanced signal. These signals S4x and S4y are the first control signals.
Since it is added to S3x and S3y, a high damping force can be generated with a frequency component synchronized with the rotation speed of the rotating body.

According to the radial magnetic bearing control device of the present invention, as described above, by generating a high damping force with a frequency component synchronized with the rotation speed of the rotating body, the whirling at the critical speed is reduced. As a result, it is possible to easily pass the dangerous speed. Further, since high damping force is generated only in a narrow band around the rotation speed, there is no problem of saturation of the control system.

[Brief description of the drawings]

FIG. 1 is a block diagram of a control device for a radial magnetic bearing showing an embodiment of the present invention, FIG. 2 is a block diagram of a high damping force generation circuit, FIG. 3 is a block diagram of a phase control circuit, and FIG. 3 is a time chart showing signals of various parts of the phase control circuit, FIG. 5 is a graph showing a whirling Lissajous figure of a rotating body in a fixed coordinate system, and FIG. 6 is a graph showing a whirling of a rotating body in a rotating coordinate system. FIG. 7 is a time chart showing the PSD signal, and FIG. 8 is a graph showing the relationship between the phase difference and the output of the PSD and LPF. (10) Control device (11x) (11y) Position sensor (12) Rotation speed sensor (13x) (13y)
Radial magnetic bearing (15): High damping force generation circuit.

Claims (1)

(57) [Claims] An apparatus for controlling a radial magnetic bearing based on an output signal of a position sensor for detecting a position of a rotating body in a radial direction, wherein an amplitude and a phase of a whirling component synchronized with a rotation speed of the rotating body are determined. A control device for a radial magnetic bearing, comprising: a high damping force generation circuit for detecting and generating a control signal having a phase advanced from a whirling component only in a narrow band around the rotation speed of a rotating body.