JP3187982B2 - Magnetic levitation device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic levitation device, and more particularly to a magnetic bearing device, a magnetic levitation type transfer device, and a magnetic levitation type device for levitating and supporting a support object having a magnetic yoke fixed thereto in a non-contact manner. The present invention relates to control of a control electromagnet such as a vibration device.

[0002]

2. Description of the Related Art FIG. 5 shows an example of a magnetic bearing as an example of a magnetic levitation apparatus using a control electromagnet which levitates and supports a support object having a magnetic yoke fixed thereto in a non-contact manner.

[0003] The rotating shaft 1 as a support object to which the magnetic yoke 2 is fixed is levitated and supported by the magnetic attraction of a pair of control electromagnets 3 facing each other. The gap between the control electromagnet 3 and the magnetic yoke 2 fixed to the rotating shaft 1 which is the object to be supported is relatively detected by the displacement sensor 9 measuring the displacement with respect to the surface of the rotating shaft 1. You. The output of the displacement sensor 9 is input to a controller including a compensation circuit 6, a power amplifier 7, and the like. By supplying an exciting current to the coil 5 of the control electromagnet 3, the magnetic attraction force is controlled, and the rotating shaft 1 Floating support at the position.

A control electromagnet 3 for such a magnetic levitation device
The magnetic attractive force exerted on the opposed magnetic yoke 2 is proportional to the square of the exciting current flowing through the coil 5. When the object to be supported is levitated and supported at a fixed target position, a control current I _C for compensating for the variation is superimposed on a bias current I _{0 serving} as a base, and the current is passed through the coil 5 as an excitation current. It controls the magnetic attraction.

That is, at the input stage of the linear detection circuit 8, the bias signal V _B and the control signal for compensating for the change, which is obtained by adjusting the phase and gain of the signal from the displacement sensor 9 by the compensation circuit 6, are added. You. The superimposed signal is detected by the linear detection circuit 8, the low frequency component is amplified by the power amplifier 7, and the exciting current is applied to the coil 5 of the control electromagnet 3. Therefore, the excitation current is a superposition of the base bias current I _O corresponding to the bias signal V _B and the control current I _C corresponding to the control signal for compensating the change from the displacement sensor 9. .

In the above example, the rotary shaft 1 is linearly controlled so as to sandwich the rotating shaft 1 between the pair of electromagnets 3. However, instead of being attracted by such a pair of electromagnets facing each other, for example, only the upper electromagnet is supported. Even when the object is levitated and supported by magnetic attraction, the excitation current is controlled by superimposing the control current I _C on the bias current I _O. In such a case, a steady current for supporting the gravity of the object to be supported flows as a bias current I _O , and a control current I _C for compensating for the change is superimposed on the bias current I _O to perform control for floating and supporting at the target position. It can be carried out.

[0007]

However, when the control current I _C is superimposed on the bias current I _O to control the magnetic attraction force of the control electromagnet, the magnitude of the control current I _C is Below the magnitude of the current I _O , the exciting current flows according to the input signal, and no problem occurs. However, when the magnitude of the control current I _C is equal to or larger than the bias current I _O , an accurate control current cannot be passed with a power amplifier operating in one quadrant of one-way current and one voltage, and the magnetic levitation device Will not work properly.

That is, assuming that the impedance of the coil 5 is Z, the voltage E across the coil is: E = Z (I ₀ ± I _C ) (1) In the equation (1), since I ₀ is only a DC component, RI ₀ ± ZI _C (2) Therefore, the bias voltage V _O corresponding to the bias voltage I _O, the control voltage V _C corresponding to the control voltage I _{C is, V 0 = RI 0, V} C = ZI C, E = V ₀ a ± V _C. In such a case, V ₀ ≧ 6
It is good if V _C1 , but V _C is V ₀ as V ₀ <V _C2.
If it is larger than this, the voltage E becomes negative, so that the control current cannot actually flow and the control cannot be performed stably.

[0009]

SUMMARY OF THE INVENTION A magnetic levitation apparatus according to the present invention comprises a control electromagnet for levitating and supporting a support object to which a magnetic yoke is fixed without contact, and a control electromagnet and the support object. A displacement sensor for detecting a gap between the fixed magnetic yoke, a controller comprising a compensation circuit, a power amplifier operating in one quadrant of one-way current and one voltage, and a bias current I _{0 is} supplied to the coil of the control electromagnet. the magnetic levitation device for performing levitation support control by flowing by superimposing the control current I _c to include a compensation resistor R 'in series to the coil of the control electromagnet, in the control frequency range, the resistance of the electromagnet coil The bias current I ₀ is added to the sum of the component R and the compensation resistor R ′.
Absolute value of multiplied by is characterized by equal to or greater than the absolute value of times the control current I _c to the impedance Z of the electromagnet coil.

[0010]

The coil of the control electromagnet is provided with a compensation resistor R 'in series, and within a control frequency range, the bias current I ₀ is added to the sum of the resistance R of the electromagnet coil and the compensation resistor R'.
Is greater than or equal to the absolute value of the impedance Z of the electromagnet coil multiplied by the control current I _C , so that the bias current I
_The DC bias voltage V _O ′ increases by an amount corresponding to the product of multiplication by _O.

That is, the product of the sum of the resistance R of the electromagnet coil Z and the compensation resistance R 'multiplied by the bias current I ₀ corresponds to a DC bias voltage V ₀ '. The absolute value of times the control current I _C in the impedance Z of the electromagnet coils, corresponds to the control voltage V _c. Accordingly, a control voltage obtained by multiplying the control current I _C in the impedance Z of the coil 5, can be increased correspondingly. Therefore, the operation of the large amplitude can be controlled, and the impedance Z (R +
Since jωL) is mainly an inductance, the control frequency range can be expanded, and the magnetic levitation device can be stably controlled in a wider frequency band.

[0012]

FIG. 1 is an explanatory view of a magnetic levitation apparatus according to an embodiment of the present invention. In the present embodiment, a compensation resistor R 'is provided in series with the coil 5 of the control electromagnet 3. Other components are the same as those shown in FIG. 5, and the same reference numerals are given and the description thereof will be omitted.

[0013] Then, within the control frequency range, absolute value of multiplied by the bias current I ₀ to the sum of the resistance component R and the compensating resistor R of the electromagnet coil 'includes a control current I _c to the impedance Z of the electromagnet coil It is configured to be equal to or greater than the absolute value of the product. That, | meets the condition | (R + R ') I O | ≧ | ZI C.

In order to improve the problem to be solved by the above-mentioned invention, a compensation resistor R 'may be provided so that the bias voltage V _O is always higher than the control voltage V _C. That is, | V ₀ | ≧ | V _C |.

The foregoing equation by providing a compensating resistor R '(2) becomes _{E = RI 0 ± ZI C +} R'I 0 (3). By transforming this, E = the _{(R + R ') I 0} ± ZI C (4). Here, 'since it is _{I 0 V C = ZI C,} | V 0 | ≧ | V C | To _{A, | (R + R V O} = (R + R)') I 0 | ≧ | ZI C | (5 ).

[0016] As described above, the absolute value but multiplied by the bias current I ₀ to the sum of the resistance component R and the compensating resistor R 'of the electromagnet coil, the control current I to the impedance Z of the electromagnet coil
_{If the} absolute value of the product multiplied by _C is equal to or greater than the absolute value, the problem that the output voltage of the power amplifier operating in one quadrant of one-way current and one voltage becomes negative, and the electromagnet is controlled within the maximum control frequency range The control current can be stably supplied to the coil.

FIGS. 2, 3 and 4 illustrate the operation of the compensation resistor R 'connected in series to the coil 5 of the control electromagnet 3 in such a configuration.

FIG. 2 illustrates the voltage sharing between the coil Z and the compensation resistor R '. Excitation current I ₀ ± I _{C in} which control current I _C is superimposed on bias current I ₀ from power amplifier 7
Is applied to a compensation resistor R ′ connected in series with the coil 5. Then, as shown in equation (3), the voltage distribution generated as the bias voltage V _O ′ at both ends of the compensation resistor R ′ is R′I ₀
Becomes The voltage distribution of the impedance Z of the coil becomes RI ₀ ± ZI _C. And the sum of these becomes the voltage E at both ends.

FIG. 3 shows that the bias voltage has increased from V _O to V _O ′ by the compensation resistor R ′, that is, V _O ′ = (R + R ′) I, and the voltage by the compensation resistor R ′ The bias voltage V _O ′ increases by the increase R′I _O. This makes it possible to control the large control voltage V _C2 shown in FIG.

FIG. 4 shows the exciting current I corresponding to the control voltage V _C2 flowing through the coil 5 of the control electromagnet and the compensating resistor R ′. The exciting current I does not become negative as shown in FIG. In addition, it is possible to supply an exciting current according to a control signal corresponding to the control voltage V _C2 , which is impossible with the related art.

[0021]

As described above, according to the present invention, a compensation resistor is provided in series with the coil of the control electromagnet, and the bias voltage is increased by the voltage generated by the compensation resistor. Therefore, if such a condition is satisfied, the power amplifier can always supply the exciting current within the positive range according to the control signal. Therefore large amplitude operation,
Alternatively, in a high-frequency operation, stable control of the control electromagnet becomes possible, and particularly, a remarkable effect is obtained in expanding the frequency range of the control region of the electromagnet.

[Brief description of the drawings]

FIG. 1 is an explanatory view of a magnetic levitation device according to an embodiment of the present invention.

FIG. 2 is an explanatory diagram of voltage sharing related to a coil Z and a compensation resistor R ′ of a control electromagnet.

FIG. 3 is an explanatory diagram of an output voltage of a power amplifier.

FIG. 4 is an explanatory diagram of an output current of a power amplifier.

FIG. 5 is an explanatory view of a conventional magnetic levitation device.

FIG. 6 is an explanatory diagram of an output voltage of a conventional power amplifier.

[Explanation of symbols]

 Reference Signs List 1 rotation axis 2 magnetic yoke 3 electromagnet 5 coil 6 compensation circuit 7 power amplifier 8 linear detection circuit 9 displacement sensor R coil resistance R 'compensation resistance Z coil impedance

──────────────────────────────────────────────────続 き Continuing on the front page (72) Eiji Marui, Inventor 4-2-1 Motofujisawa, Fujisawa-shi, Kanagawa Prefecture Within Ebara Research Institute, Inc. (72) Ikuo Nakaguchi 4-2-2 Motofujisawa, Fujisawa-shi, Kanagawa Prefecture No. 1 EBARA Research Institute, Inc. (56) References Hikaru 1-146014 (JP, U) (58) Fields investigated (Int. Cl. ⁷ , DB name) H02K 7/09 F16C 32/04

Claims (1)

(57) [Claims] 1. A control electromagnet that levitates and supports a support object to which a magnetic yoke is fixed without contact, and detects a gap between the control electromagnet and the magnetic yoke fixed to the support object. a displacement sensor for compensation circuit and unidirectional current, a controller comprising a power amplifier 1 quadrant operation piece voltage, by passing by superimposing the control current I _c to the bias current I ₀ to the coil of the control electromagnet In a magnetic levitation apparatus that performs levitation support control, a coil of the control electromagnet is provided with a compensation resistor R ′ in series, and a bias current is added to a sum of the resistance R of the electromagnet coil and the compensation resistor R ′ within a control frequency range. The absolute value multiplied by I ₀ is the impedance Z of the electromagnetic coil.
Magnetic levitation and wherein the absolute value greater than or equal to those multiplied by a control current I _c to.