JPS6110113A - Synchronous eccentric rotation suppressor for magnetic bearing - Google Patents

Abstract

PURPOSE:To eliminate uncontrolled state under low displacement detection signal by operating the proper gap on the basis of a rotary angle detection signal obtained from the detection signal of a gap detector and a swing amplituide detection signal passed through lowest amplitude compensator. CONSTITUTION:PLL unit 3 is comprised of multipliers 36, 37, adders 38, 39, an amplifier 32, rotor rotation command frequency transmitter 35 and two-phase oscillator 34. While an amplitude operating unit 5 is comprised of two multipliers 51, 52, an adder 53, a sign inversion amplifier and a lowpss filter 55. The input signal DELTAdeltasintheta for the amplifier 32 in PLL unit 3 is brough to 0 through PLL 3 while the input signal DELTAdeltacostheta for the lowpass filter 55 is also brought to 0, thereby DELTAdeltacostheta will be DELTAdelta, to produce only the swing amplitude. In the invention, a lowest amplitude compensator 13 is provided before PLL unit 3.

Description

[Detailed description of the invention] [Industrial field of application and its purpose] The present invention relates to synchronous eccentric rotation of a magnetic bearing device used for a rotating shaft that rotates at high speed such as a high-speed machine tool, a centrifugal separator, or a gyro drive electric motor. This invention relates to an improvement of a suppression control device, and its purpose is to provide a control device of this type with a simple structure that can perform a control function even when a displacement detection signal is small.

[Conventional technology]

As is well known, the rotating shaft and rotating body are not made homogeneous, so in a magnetic bearing device that supports the rotating shaft in the air using magnetic hoe force, eccentric loads remain no matter how much the balance weight is adjusted. Eccentric rotation occurs due to
This hinders the movement of the rotating shaft and causes contact between the rotating shaft and the fixed part, which can easily cause damage or noise, and in order to obtain stable rotation, control of synchronous eccentric rotation is necessary.

Of course, this synchronous eccentric rotation increases as the rotation speed increases, but when a magnetic bearing device is applied to a machine tool, dynamic unbalance will inevitably occur due to the load from the cutting tool. Therefore, it is essential to have a control device that compensates for this.

Conventional control devices used for this purpose use rotation detectors or rotation angle detectors (e.g. resolnog, Hikari City conversion type tachogenerator, etc.) as shown in Japanese Patent Publication No. 52-93852. It was something to do.

[Problem that the invention seeks to solve]

The present invention aims to provide a control device for this building that does not use a rotation detector or a rotation angle detector, and which does not cause an uncontrolled state even when the displacement detection signal is small.

[Structure of the invention]

The present invention utilizes the detection signal of the air gap detector, which is always provided in magnetic bearing equipment, and uses the detection signal to determine the PLLf P
A hase-Lock Loop) device is used to detect the rotation angle, and an appropriate air gap is calculated from this rotation angle detection signal and a swing width detection signal to appropriately control the amount of eccentricity. Instead, a signal passed through a minimum amplitude compensator is used, and control is performed as a displacement signal higher than the control level.

First, the principle of the present invention will be described.

As shown in Fig. 1(a), the rotating body R has an eccentric load WL.
air gap detector 1 placed on the X and Y axes when rotated;
2 changes as shown in FIG. 1(b).

The control system N without compensation control performs foot check control using the detected value of the air gap detector 1.2, and the control system is shown in a block diagram in FIG. 2.

In the figure, δsld is the initial air gap setting value, P is the gain, D is the differential constant, S is the Laplace operator, and I is the integral constant.

KF is the machine constant of the control system, M is the mass of the rotating body, δ is the proportionality constant of the air gap detector, T is the delay time constant of the filter, r
radius up to the eccentric load I11, ω is the synchronous rotational angular velocity, F
D is an external force.

In this case, a synchronous runout of Δ1JtJ is detected in the air gap J due to the unbalanced force mrω2.

In order to provide negative feedback and suppress this runout, the magnetic bearing's PI
D controller operates. However, the synchronous rotational angular velocity ω
When ω becomes large, this unbalanced force increases in proportion to ω8, and the magnetic force for control becomes insufficient, causing problems such as the stator vibrating, the sensor vibrating and fc, and the electromagnet generating heat. As a result, high-speed rotation becomes impossible.

The present invention first attempts to solve this problem, and FIG. 3 is a basic control system diagram of the compensated control device according to the present invention in a block diagram.

This is the synchronous runout amount lha from the air gap detector output.
, Jw (1 +
TS In this method, the PID controller is unlimited only with respect to runout, so the drawbacks of the conventional method shown in FIG. 2 are eliminated and high-speed operation is possible.

In this case, there is a steady displacement of △δ=M+m', but 1For example, if m=0.1f r=25m M-2- then Δ
It is about 1.25 (μm) in δ.

However, if control is performed according to the conventional method shown in Fig. 2 to make 1△δ→0 μm, the magnetic 111 receiver becomes N
= 1000 (R/s), it is necessary to control the control force at I KHz, and this is a difficult problem in which such control is considered impossible.

FIG. 4 is a block diagram of the synchronous run-out calculator, in which the amount of run-out can be expressed as the rotation vector △δ, Jo
t, the two-phase generator 34 is controlled by PLL so that ε
j (art+(j l , and ω→0.

Next, when calculating 1mu δ1, it is passed through filter 4.

Remove changes other than synchronous runout, and calculate δ=δ(1)+△
δεJ (δ = δ by removing only ΔδεjQQ from '1
(1) is obtained.

〔Example〕

FIG. 5 shows an embodiment of the basic synchronous deflection p calculator according to the present invention, in which the PLL device 3 necessary for calculating the equation. It is composed of an amplitude calculator 51, a multiplier 6, and a comparator 1.

The PLL device 3 includes passenger devices 36, 37. Adder 38°39,
Amplifier 32. It is composed of a rotor rotation command frequency (ωl) transmitter 35 and a two-phase oscillator 34, and input gap deviation signals Δδsinωt and Δδcosωt at 5 inches.
Convert (ωt+θ) and cos iω to 10), respectively.

The amplitude calculator 5 includes two multipliers 51 and 52 and an adder 53,
It is composed of a gradient sign inversion amplifier 54 and a low/ξ filter 5 (this filter may be omitted), and it converts the input signal from the Δδ sin ωt and Δδ cos(I)t to ΔδC
Create o1tθ.

The input signal Δ of the amplifier 32 in the PLL device 31
δsinθ Δδ5in(/−Δδ(sinfωt+θIcosω+
−cos(ω1+θ)sin(υt) becomes Δδsinθ→0 due to the PLL control function of the PLL device 3, so the input signal Δac of the low-pass □ filter 55
osθ Δδcosθ=Δδ(cos(ωt+θ)cosωj+
5 inches (ω=10θ) sinω1 becomes θ→0, so Δδcosθ→Δδ. The only thing that can be obtained is the ability to take pictures of people who are talented.

Fig. 6 shows a proper embodiment. Focusing on the fact that △δ or It is composed of a Δδ operation circuit 56 consisting of a generator and a low-pass filter 55, and can be used as a practical device Fr.The Δδ operation 3γ circuit 56 is composed of a function generator based on a polygonal line crank. I can do it.

As mentioned above, in order to perform optimal control against the synchronized shooting phenomenon caused by the dynamic aperture, conventionally it was necessary to use a rotation detector or a rotation angle detector, but with the present invention. If the basic synchronous runout calculator is used, this becomes unnecessary, and its practical value is great.

However, in the device ^IV using the basic synchronization (bulge rotation calculator) explained above, the displacement output signal Δδ5in(ω
10) and Δδcos'ωt+0) are uncontrollably small, the VC will be in an uncontrolled state.

Therefore, the present invention provides a constant setting device at the front stage of the PLL device. A minimum amplitude compensator is further added to ensure a displacement output signal higher than the control level, thereby eliminating the possibility of an uncontrolled state.

FIG. 7 is a block diagram of an embodiment of the present invention, in which 13 is a minimum amplitude compensator 114 is a setting device. Blocks with the same reference numerals as in FIG. 5 are the same as those in FIG.

Figure 288 is a detailed diagram of the minimum amplitude compensator 13, which includes a 131-digit reference amplitude calculator, 132 an adder, 133 an amplifier, 13
4 and 135 are multipliers.

In the t1 low digging width compensator 13, the reference amplitude calculator 131 calculates the reference amplitude of the input signal, and sets the reference amplitude as: ',
'; The deviation is amplified by the amplifier 133, and the value is applied to the multiplier 134
Multiply each input signal by 135, always.

The signal is useful as a control signal.

〔Effect of the invention〕

As described above, since this invention does not use a rotation detector or a rotation angle detector, it can be provided in a smaller size and at a lower cost, and can be provided without control! Since the flow does not become a river, it is possible to obtain a device that performs optimal control against the synchronous run-out phenomenon caused by dynamic imbalance, which is effective.

[Brief explanation of the drawing]

Figure 1 is an explanatory diagram showing the functional position of the rotating body and the gap detector, and changes in the output signal of the gap detector, Figure 2 is a block diagram of the control device without compensation control, and Figure 3 is the diagram with compensation control. Block diagram of the control device Fig. 1 is a block diagram of the synchronous run-out calculation 2:÷, Fig. 5 is a block diagram of an embodiment of the basic synchronous run-out calculation ≠ according to the present invention, and Fig. 6 is a block diagram of the synchronous run-out calculation 2: ÷. Figure 7 is a block diagram of an embodiment of the present invention, and Figure 8 is a block diagram showing details of the minimum amplitude compensator. 3... PLL device, 5... amplitude calculator, 6...
- Multiplier, 7... Comparator, 11.12... Adder,
13... Minimum amplitude compensator, 14... Setting device. Figure 1 (α) (b) Engineering Figure 2 Figure 6 Figure 4 Figure 5 L''!!, 9 g7゛6 Figure 6 81

Claims (1)

[Claims] In a magnetic bearing control device in which a gap detector is arranged so as to be able to be converted into an orthogonal or orthogonal axis system, displacement output signals in each orthogonal direction obtained by subtracting a reference gap value from the air gap detection value converted to an orthogonal or orthogonal axis system are input. an amplitude calculator that outputs a reference amplitude signal; a minimum amplitude compensator that receives the displacement output signal as input, compares the reference amplitude with a set value, and outputs a value obtained by multiplying the input signal by the difference; a PLL device that receives the output of the minimum amplitude compensator and outputs its sine wave signal and cosine wave signal; a multiplier that multiplies each of the output signals of the PLL device by the output of the amplitude calculator; 1. A synchronous eccentric rotation suppression control device for a magnetic bearing device, comprising a comparator for comparing an output signal of the device with each of the displacement output signals.