JPH02163511A - Control circuit for magnetic searing device and magnetic floating carrier - Google Patents

Abstract

PURPOSE:To reduce the loss of power by providing a pulse amplifying circuit and a switching circuit having a switching element performing On and Off operation by the output of the pulse amplifying circuit as a power amplifier. CONSTITUTION:Relative displacement between a rotating shaft 1 and the stator of an electromagnet is detected by a displacement sensor 5 and inputted to a phase compensating circuit 11. An output liner detected in a linear detecting circuit 12a is pulse width modulated in a pulse width modulating circuit 16a and control current is supplied to an exciting coil 4a through a PWM waveform amplifying circuit 15a and a switching circuit 16a. The control current supplied to the exciting coil 4b is detected by the voltage of a current feeding back resistor 17b and negative fed back to the pulse width modulating circuit 14b. In such a way, the loss of power is extremely decreased in a power switching element.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a magnetic bearing device used as a bearing for a turbo machine, a machine tool, etc., and a control circuit for a magnetically levitated conveyance device.

[Prior art]

Magnetic bearing devices and magnetic levitation conveyance devices use displacement sensors to detect the relative position between a rotating body and a stator, and the relative displacement between a magnetically levitated moving body and a track, and then send the detection signal of the displacement sensor to a compensation circuit and a power amplification circuit. It is supplied through a circuit to an electromagnetic coil that generates magnetic attraction force or magnetically levitated blades, and the relative displacement between the rotating body and stator of the magnetic bearing device, and the relative displacement between the magnetically levitated moving body of the magnetically levitated transport device and the track are kept constant. It is a device for holding.

FIG. 4 is a diagram showing a circuit configuration of a conventional control device for a magnetic bearing device. In the figure, 31 is a rotating shaft, 32 is a rotor yoke fixed to the rotating shaft 31, 33a and 33b are stator electromagnets, 34a and 34b are excitation coils, and 35 is a relative position between the rotating body and the stator. 36 is a phase compensation circuit, 37a, 37b are linear detectors,
38a and 38b are power amplifiers.

In the control device having the circuit configuration described above, the relative position of the rotating body and the stator is detected by the displacement sensor 35, this detection signal is input to the phase compensation circuit 36, and its output is used to control the linear detectors 37a, 37b and the power amplifier. The currents supplied to the excitation coils 34a and 34b are controlled via the excitation coils 38a and 38b so as to maintain the axial center of the rotating body at a predetermined position.

FIG. 5 is a block diagram showing the circuit configuration of a control device for a magnetically levitated conveyance device in which control electromagnets are provided on the track. In the figure, 41 is a moving body, 42 is a yoke fixed to the moving body,
43 is a stator electromagnet, 44 is an excitation coil, 45 is a displacement sensor that detects the relative position of the moving body 41 and the stator, 46 is a phase compensation circuit, 47 is a linear detection circuit, and 48 is a power amplifier.

In the control device having the above circuit configuration, the relative position between the movable body 41 and the stator is detected by the displacement sensor 45, and this detection signal is input to the phase compensation circuit 46, and its output is transmitted via the linear detection circuit 47 and the power amplifier 48. The current supplied to the excitation coil 44 is controlled so that the distance between the movable body 41 and the stator is maintained at a predetermined position.

FIG. 6 is a block diagram showing a circuit configuration of a control device for a magnetic float transport device in which a control electromagnet is provided in a moving body. In the figure, 51 is a track, 52 is a yoke fixed to the track, 53 is a moving body, and the moving body 53 includes an electromagnetic yoke 5.
4, an exciting coil 55, a displacement sensor 56 that detects the relative position of the track 51 and the moving body 53, a phase compensation circuit 57, a linear detection circuit 58, and a power amplifier 59 are installed.

In the control device having the above circuit configuration, the moving body 53 and the track 5
1 is detected by a displacement sensor 56, this detection signal is input to a phase compensation circuit 57, and its output controls the current supplied to the exciting coil 55 via a linear detector 58 and a power amplifier 59. The distance between the moving body 53 and the track 51 is controlled to be at a predetermined position.

[Problem to be solved by the invention]

In the circuit of the control device for the conventional magnetic bearing device and magnetic levitation conveyance device, the power amplifiers 38a, 38b, 4
The circuit configuration of 8.59 is a so-called series type power amplifier as shown in Fig. 7, and a static magnetic attraction force must always be generated in the stator electromagnet, and the power transistor Tr
It is necessary to constantly apply a large DC current to the As a result, the colleter loss of the power I transistor Tr increases, which shortens the element life of the power transistor Tr, and requires a large capacity heat sink fan, which increases running costs and initial costs. .

The present invention has been made in view of the above-mentioned points, and eliminates the above-mentioned drawbacks, provides a long life of the elements constituting the power amplifier, and provides a magnetic bearing device with low running cost and low initial cost, and control of a magnetically levitated conveyance device. The purpose is to provide circuits.

[Means to solve the problem]

In order to solve the above problems, the present invention provides a pulse amplification circuit as a power amplifier in a control circuit of a magnetic bearing device or a magnetic float-1 = conveyance device, and an output of the pulse amplification circuit that can be turned on and off.
A switching circuit having a power switching element that operates as an FF is provided, and the switching circuit is configured to supply current to the coil of the electromagnet, and a rectangular wave generation circuit that outputs a rectangular wave signal with a predetermined period, and an output of a phase compensation circuit. A pulse width modulation circuit is provided which modulates the pulse width of the rectangular wave signal from the rectangular wave generation circuit using the modulation input signal, and the output of the pulse width modulation circuit is configured to be input to the pulse amplification circuit. The present invention is characterized in that a current detection means for detecting the current that can be supplied to the coil is provided, and the output of the current detection means is negatively fed back to the pulse width modulation circuit.

[Function] By configuring the control circuit of the magnetic bearing device and the magnetic floating device as described above, a switching system having a pulse amplification circuit as a power amplifier and a power switching element that is turned on and off by the output of the pulse amplification circuit can be realized. Since a circuit is provided and the switching circuit is configured to supply current to the coil of the electromagnet, power loss in the power switching element is reduced compared to a conventional series type power amplifier.

〔Example〕

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a block diagram showing a control circuit of a magnetic bearing device according to the present invention. In the figure, 1 is a rotating shaft, 2 is a rotor yoke fixed to the rotating shaft 1, 3a and 3b are stator yokes constituting an electromagnetic stator, 4a and 4b are stator yokes 3a, 3b are excitation coils each wound with a wire.

These stator yokes 3a, 3b, excitation coils 4a, 4b, rotor yoke 2, etc. constitute a magnetic bearing that supports the rotating shaft 1 in the radial direction.

5 is a displacement sensor that does not detect relative displacement between the rotating shaft 1 and the electromagnetic stator; 11 is a phase compensation circuit; 12a and 12b are linear detection circuits; 13 is a rectangular wave generation circuit; 14a and 1
4b are pulse width modulation circuits, 15a, 1.
5b are the pulse width modulation circuits 14a and 14b, respectively.
a PWM waveform amplification circuit that amplifies a PWM waveform subjected to pulse width modulation (PWM); 16a and 16b are switching circuits that supply excitation current to the excitation coils 4a and 4b;
7a and 17b are current feedback resistors.

In the control circuit configured as described above, the relative displacement between the rotating shaft 1 and the electromagnetic stator is detected by the displacement sensor 5, and the detected signal is input to the phase compensation circuit 11. The phase compensation circuit 11 gives a phase advance to this detection signal. Furthermore, add this signal to 2
The signals are divided, and bias voltage (6) is directly applied to one signal, which is then input to the linear detection circuit 12a. The other signal is inverted, applied with a bias voltage V, and input to the linear detection circuit 12b. The output linearly detected by the linear detection circuit 12a is pulse width modulated by the pulse width modulation circuit 14a, and PWM
A control current is supplied to the excitation coil 4a through the waveform amplification circuit 15a and the switching circuit 16a. Excitation coil 4
The control current supplied to a is detected by the voltage of the current feedback resistor 17a, and is negatively fed back to the pulse width modulation circuit 14a. On the other hand, the output linearly detected by the linear detection circuit 12b is pulse width modulated by the pulse width modulation circuit 14b, and the PW
A control current is supplied to the exciting coil 4b through the M waveform amplification circuit 15b and the switching circuit 16b. The control current supplied to the excitation coil 4b is detected by the voltage of the current feedback resistor 17b, and is negatively fed back to the pulse width modulation circuit 14b. Thereby, the position of the rotating shaft 1 in the radial direction is controlled. The pulse width modulation circuit 14a has a capacitor C1.
, a switching element FET, a resistor R, a comparator IC, an R-S flip-flop FF, and an inverter IC.

The PWM waveform amplification circuit 15a is a power transistor Tr+
and resistor R5.

The switching circuit 16a is a power switching element FE.
T, and a diode D.

Note that +y, , +y are power supply voltages.

Figure 2 shows the modulated input waveform (a) which is the output of the linear detection circuit 1.2a, the output waveform (b) of the rectangular wave generation circuit 13, the output waveform (C) of the pulse width modulation circuit 14a, and the output waveform of the switching circuit 16a. It is a figure which shows an input waveform (d). The positive signal that has passed through the linear detection circuit 12a is pulse-modulated in the pulse width modulation circuit 14a as follows. The rectangular wave signal from the rectangular wave generating circuit 13 sets the R-S flip-flop FF, and the setting of the R-S flip-flop FF causes the signal to be sent to the switching element F via the inverter IC.
E T is turned off and capacitor C5 is charged. Voltage due to charge of capacitor C+ and linear detection circuit 1
Compare the modulation input from 2a with comparator IC1,
When the voltage on capacitor C1 becomes higher than the modulation input voltage, it resets the R-S flip-flop FF. R-S
When the flip-flop FF is reset, the switching element FET is turned on, the charge in the capacitor C8 is discharged, and the voltage value becomes zero. This operation is repeated, and a pulse width modulated pulse signal as shown in FIG. 2(C) is output from the pulse width modulation circuit 14a. The output of this pulse width modulation circuit 14'a is amplified by the PWM waveform amplification circuit 15a, resulting in an output with the waveform shown in FIG. 2(d),
The signal is input to the switching circuit 16a. As a result, the power switching element FET of the switching circuit 16a
.

is ON-0FFL, and supplies an excitation current to the excitation coil 4a. Here, the PWM waveform amplification circuit 15a and the switching circuit 16a correspond to a power amplifier that supplies excitation current to the excitation coil 4a, so the power switching element FET, through which a large current flows, performs a high frequency switching operation, and a large DC current does not flow. . Therefore, almost no loss occurs in the element.

Linear detection circuit 12b, pulse width modulation circuit 14b, PWM
The operations of the waveform amplification circuit 15b and the switching circuit 16b are also similar, so the explanation thereof will be omitted.

FIG. 3 is a block diagram showing a control circuit of the magnetic levitation device according to the present invention. In this figure, parts given the same reference numerals as those in FIG. 1 indicate the same or equivalent parts. 21 is a mobile object,
22 is a yoke fixed to the movable body, 23 is a stator yoke constituting an electromagnetic stator, 24 is an excitation coil wound around the stator yoke 23, and 25 is a relative between the movable body 21 and the stator. Displacement sensor that detects position.

In the control circuit configured as described above, the displacement sensor 25 detects the relative displacement between the moving body 21 and the electromagnetic stator, and the detected signal is input to the phase compensation circuit 11. Phase compensation circuit 11
Then, this detection signal is given a phase lead and output as a modulation input. A bias voltage VB is added to this modulation input and input to the linear detection circuit 12. The output linearly detected by the linear detection circuit 12 is pulse width modulated by the pulse width modulation circuit 14, and a control current is supplied to the excitation coil 24 through the PWM waveform amplification circuit 15 and the switching circuit 16. The control current supplied to the excitation coil 24 is detected by the voltage of the current feedback resistor 17 and is negatively fed back to the pulse width modulation circuit 14.

The operation of the pulse width modulation circuit 14 is the same as that of the pulse width modulation circuit 14a in FIG. 1, and its effects are also substantially the same, so detailed explanation thereof will be omitted.

In addition, the control circuit of the magnetic levitation conveyance device in which a control electromagnet is provided in a moving body can be implemented by mounting the yoke 23, excitation coil 24, and displacement sensor 25 shown in Fig. 3 on the moving body, and installing the yoke 22 on the track. Since the other parts are the same as those in FIG. 3, the explanation thereof will be omitted.

〔Effect of the invention〕

As explained above, according to the present invention, the power loss in the power switching element is extremely reduced compared to the conventional Schiffuse type power amplifier, so the reliability of the power switching element is improved, and the heat sink of the power switching element is improved. The capacity can be reduced, and therefore a cooling fan is not required, and the life and reliability of magnetic bearing devices and magnetic levitation conveyance devices can be improved. A block diagram showing the control circuit of the bearing device, FIG. 2 is a waveform diagram showing the waveforms of the modulation input, the output of the rectangular wave generation circuit, the output of the pulse width modulation circuit, and the input of the switching circuit, and FIG. A block diagram showing a control circuit of a magnetic levitation device, FIG. 4 is a block diagram showing a circuit configuration of a conventional magnetic bearing device control device, and FIG. FIG. 6 is a block diagram showing the circuit configuration of a control device, and FIG. 6 shows a conventional magnetic levitation transport system in which a control electromagnet is provided on a moving body 1...rotating shaft, 2...rotor yoke, 3... Stator yoke, 4a,
4b... Excitation displacement sensor, 11... Phase compensation circuit 12b, 12... Linear detection circuit, 1.13...
Rectangular wave generation circuit, 14 14... Pulse width modulation circuit, 15 15... PWM waveform amplification circuit, 16 16... Switching circuit, 17 17... Current feedback resistor, 21 22.・Yoke, 23...Stator electromagnetic/excitation coil.

In the figure, a, 3b Ile, 5 Road, 12a.

3a, 13h a, 14b.

a, 15b.

a, 16b.

a r 17 b +...mobile object, stone, 24... Applicant: Ebara Research Institute, Inc. (one other person) Agent: Patent attorney Takashi Kumagai (one other person)

Claims (3)

[Claims] (1) A rotor yoke made of a magnetic material that is fixed to the rotating shaft, a stator electromagnet that is fixed to the casing with a small gap from the rotor and equipped with a coil that generates a magnetomotive force, and the rotor yoke that is fixed to the rotating shaft. A displacement sensor that measures the relative displacement between the casings, a phase compensation circuit that controls the magnetic attraction force acting between the rotor yoke and the stator electromagnet based on the output signal from the displacement sensor, and electric power. In a magnetic bearing device equipped with an amplifier, a switching circuit having a pulse amplification circuit and a power switching element that is turned on and off by the output of the pulse amplification circuit is provided as the power amplifier, and the switching circuit is connected to the coil of the stator electromagnet. A rectangular wave generating circuit configured to supply current and outputting a rectangular wave signal of a predetermined period, and using the output of the phase compensation circuit as a modulation input signal to modulate the pulse width of the rectangular wave signal from the rectangular wave generating circuit. a pulse width modulation circuit configured to input the output of the pulse width modulation circuit to the pulse amplification circuit; further provided with current detection means for detecting the current supplied to the coil of the stator electromagnet; A control circuit for a magnetic bearing device, characterized in that the output of the current detection means is negatively fed back to the pulse width modulation circuit. (2) A movable body yoke made of a magnetic material fixed to the movable body, a stator electromagnet equipped with a coil that is fixed to a track with a minute gap from the movable body yoke and generates a magnetomotive force, and a displacement sensor that measures the relative displacement between the body and the track, and a phase compensation circuit that controls the magnetic attraction force that acts between the movable body yoke and the stator electromagnet based on the output signal from the displacement sensor. and a power amplifier, a switching circuit having a pulse amplification circuit and a power switching element that is turned on and off by the output of the pulse amplification circuit is provided as the power amplifier, and the stator electromagnet is connected to the stator electromagnet from the switching circuit. a rectangular wave generating circuit configured to supply current to the coil and outputting a rectangular wave signal of a predetermined period, and a pulse of the rectangular wave signal from the rectangular wave generating circuit using the output of the phase compensation circuit as a modulation input signal. A pulse width modulation circuit for modulating the width is provided, the output of the pulse width modulation circuit is input to the pulse amplification circuit, and further current detection means is provided for detecting the current supplied to the coil of the stator electromagnet. A control circuit for a magnetic levitation conveyance device, characterized in that the output of the current detection means is negatively fed back to the pulse width modulation circuit. (3) A stator yoke made of a magnetic material fixed to a track, a moving body electromagnet fixed to a moving body with a minute gap from the stator yoke and equipped with a coil that generates a magnetomotive force, and the track. and a displacement sensor that measures the relative displacement between the moving body and the moving body, and a phase compensation circuit that controls the magnetic attraction force acting between the stator yoke and the moving body electromagnet based on the output signal from the displacement sensor. and a power amplifier, a switching circuit having a pulse amplification circuit and a power switching element that is turned on and off by the output of the pulse amplification circuit is provided as the power amplifier, and the mobile electromagnet is connected to the mobile electromagnet from the switching circuit. a rectangular wave generating circuit configured to supply current to the coil and outputting a rectangular wave signal of a predetermined period, and a pulse of the rectangular wave signal from the rectangular wave generating circuit using the output of the phase compensation circuit as a modulation input signal. A pulse width modulation circuit for modulating the width is provided, the output of the pulse width modulation circuit is input to the pulse amplification circuit, and further current detection means is provided for detecting the current supplied to the coil of the moving body electromagnet. A control circuit for a magnetic levitation conveyance device, characterized in that the output of the current detection means is negatively fed back to the pulse width modulation circuit.