JPH07279962A - Magnetic bearing type rotary device - Google Patents

Abstract

PURPOSE:To stop the rotation of a rotary body in a short time even though a rotary body touches down upon power failure. CONSTITUTION:During power supply, a relay 61 is energized by an output from a drive control circuit power source 60 so as to open a brake contact 61a and to charge a capacitor 63. Further, upon power failure, since no output is delivered from the drive control circuit power source 60, the relay 61 is deenergized so that the contact 61a is closed. Then, the charge having been accumulated in the capacitor 63 is applied to the gate of a transistor through diodes 65a through 65c. When the transistor is turned on so that three phase windings of a motor is shortcircuited through transistor, etc., so as to effect electric brake operation. As a result, the rotation of a rotary body which has touched down comes to a stop in a short time, the rotational speed of a protecting bearing, thereby it is possible to prolong the life of the protecting bearing.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic bearing type rotating device, for example, a magnetic bearing which prevents a protective bearing from being destroyed when a rotating magnetic bearing type turbo molecular pump or the like touches down during a power failure. Rotary device.

[0002]

2. Description of the Related Art Conventionally, a magnetic bearing type rotating device has generally been equipped with a battery as a backup power source when a power failure occurs during high speed rotation of a rotating body. And
At the time of power failure, the magnetic levitation of the rotating body is continued by the electric power of the battery, and the inverter performs a braking operation to stop the rotation of the rotating body.

However, in recent years, for example, in a magnetic bearing type turbo-molecular pump or the like, a battery as a backup power source is not used, and in the event of a power failure, the rotational energy of the rotating body is regenerated to the motor driving device side and used as the power source for the magnetic bearing. As a result, a method of continuing the magnetic levitation of the rotating body (hereinafter referred to as a batteryless method) is becoming mainstream.

In the batteryless system, the rotational energy of the rotating body is regenerated and the rotational speed of the rotating body is reduced, and the regenerated electric power is reduced as the rotational speed is reduced. Then, when the regenerated electric power falls below the electric power required for magnetic levitation, the magnetic levitation operation of the magnetic bearing cannot be continued, and the rotating body descends onto the protective bearing (hereinafter referred to as touchdown).

On the other hand, in the batteryless system, the rotational speed at which the magnetic bearing becomes inoperable during a power failure is about 1/3 to 1/5 of the rated rotational speed. The rotational energy when the rotating body touches down on the protective bearing is almost consumed as heat energy due to mechanical friction of the protective bearing, and the rotation is stopped in several minutes to several tens of minutes.

[0006]

However, when the rotating body rotates on the protective bearing for several minutes to several tens of minutes as described above, the weight of the rotating body causes the protective bearing to be severely worn. Due to this severe wear, the protective bearing may be destroyed by touchdown of the rotating body at the time of several tens of times of power failure, or due to the rattling of the bearing that is caused by the abrasion of the balls constituting the protective bearing, For example, there is a risk that the rotor blades of the turbo molecular pump and the fixed blades may come into contact with each other and be destroyed.

Therefore, an object of the present invention is to provide a magnetic bearing type rotating device which stops rotation in a short time when a power failure occurs during high speed rotation of the rotating body and the rotating body touches down.

[0008]

According to a first aspect of the present invention, a direct current supply means, an electromagnet for magnetically levitating a rotating body of a motor by a current supplied from the direct current supply means, and a magnetic field generated by the electromagnet are controlled. Magnetic bearing control means for controlling the position of the rotating body, power converting means for converting the supply current from the direct current supplying means into alternating current for forming a rotating magnetic field for rotating the rotating body of the motor, and the direct current supplying means. Detecting a stop of the power supply by, and short-circuit means for short-circuiting the winding of the motor to which the alternating current is supplied from the power conversion means,
To achieve the above objectives.

According to a second aspect of the present invention, the power conversion means includes a switching element for controlling current supply to the winding of the motor, and the short-circuit means is provided on the output side of the direct current supply means. A relay and a capacitor connected in parallel; and a break contact of the relay, one end of which is connected to a connection point of the relay and the capacitor and the other end of which is connected to a conduction control unit which controls conduction of the switching element. To achieve the above-mentioned object.

According to a third aspect of the present invention, it is arranged between the DC supply means and the relay, and when the magnetic bearing control means is supplied with power, the DC supply means and the relay are connected to each other, and The object is achieved by providing an opening / closing means for disconnecting the direct current supply means and the relay when the bearing control means is deenergized.

[0011]

In the magnetic bearing type rotating device according to the first aspect of the invention, the electromagnet is supplied with direct current from the direct current supplying means to magnetically levitate the rotating body of the motor. The magnetic bearing control means controls the position of the magnetically levitated rotating body. The power conversion means converts the direct current supplied from the direct current supply means into alternating current for forming a rotating magnetic field for rotating the rotating body of the motor. The short-circuit means detects the stop of the power supply by the DC supply means and short-circuits the winding of the motor.

When the rotating body continues to rotate while the winding of the motor is short-circuited when the power supply is stopped, the motor acts as a generator and the rotating body of the motor receives an electric braking action. Therefore, when the power supply is stopped, the rotating body stops rotating within a short time by the electric braking action, so that the life of the protective bearing can be extended.

According to another aspect of the magnetic bearing type rotating device of the present invention,
The winding of the motor is connected to the switching element forming the power conversion means. Since the relay is connected to the output side of the DC supply means, the presence or absence of power supply of the DC supply means is detected. Since the contact of the relay is a break contact, the contact is opened when power is supplied, and the capacitor is not connected to the switching element. Therefore, electric charges are stored in the capacitor when power is supplied from the DC supply means.

On the other hand, since the relay is not supplied with power when the power supply is stopped, the break contact is brought into a connected state, and the electric charge stored in the capacitor is supplied to the conduction control section of the switching element. Therefore, the winding of the motor is short-circuited via the switching element. In the magnetic bearing type rotating device according to the third aspect, the opening / closing means is arranged between the direct current supplying means and the relay. The opening / closing means connects the DC supply means and the relay when the magnetic bearing control means is powered, and disconnects the DC supply means and the relay when the magnetic bearing control means is powered off. .

Therefore, when the power supply to the magnetic bearing control means is stopped, the break contact is immediately put into the connected state, the electric charge accumulated in the capacitor makes the switching element conductive, and the winding of the motor is short-circuited.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the magnetic bearing type rotating device of the present invention will be described in detail below with reference to FIGS. FIG. 1 is a block diagram showing the overall configuration of a batteryless magnetic bearing system to which this embodiment is applied.

As shown in FIG. 1, an AC power supply 1 is connected to an input side of a rectifier circuit 2 as "DC supply means", and two power supply lines La1 and Lb1 are connected to an output side of the rectifier circuit 2. Has been done. The two power supply lines La1 and Lb1 are connected to the input side of the motor drive main circuit 4 as “power conversion means” that converts single-phase power into three-phase power via the smoothing capacitor 3. Three-phase electric power is output from the output side of the motor drive main circuit 4, and the output is connected to the motor winding MC of the DC brushless motor that constitutes the magnetic bearing type rotating device MB.

The two power supply lines La1 and Lb1 on the output side of the rectifier circuit 2 are connected to the input side of the stabilized DC power supply circuit 5. Two power supply lines La2 and Lb2 are connected to the output side of the DC stabilized power supply circuit 5. Two power lines La
2, Lb2 is connected to the motor drive control circuit 6, and supplies magnetic power to the magnetic bearing winding BC of the magnetic bearing type rotating device MB to control the position of the rotating body. It is connected to the bearing control circuit 7. The output side of the motor drive control circuit 6 is connected to the control input terminal of the motor drive main circuit 4.

Next, the first and second embodiments will be described. Note that these embodiments are different only in the circuit configurations of the motor drive main circuit 4 and the motor drive control circuit 6 shown in FIG. 1, and the other parts are the same. (1) First Embodiment In this embodiment, the charge stored in the capacitor during energization is added to the gate of the N-MOS transistor at the time of power failure,
This is a case where the MOS transistor is turned on and the motor winding MC is short-circuited to perform an electric braking action.

FIG. 2 is a circuit diagram showing a motor drive main circuit 4A having a specific configuration of the motor drive main circuit 4, and FIG.
FIG. 6 is a circuit diagram showing a motor drive control circuit 6A similarly. As shown in FIG. 2, a series circuit including a resistor 41 and a transistor 42 is connected between the two power supply lines La1 and Lb1. The resistor 41 is a regenerative resistor for consuming the energy regenerated from the DC brushless motor at the time of deceleration of the rotating body due to the power failure, so that the amount of energy regenerated and the amount of energy consumed by the resistor 41 become equal. The transistor 42 is on / off controlled.

Between the two power supply lines La1 and Lb1, there are a series circuit including transistors 43a and 43b, a series circuit including transistors 43c and 43d, and a series circuit including transistors 43e and 43f. , Each connected. Each transistor 42, 43a-43
For f, a power transistor such as N-MOSFET or IGBT (insulated gate bipolar mode transistor) is used, and a diode 44 for a regenerative current path is provided between the source and drain of each transistor 42, 43a to 43f.
a to 44 g are connected. Also, each transistor 4
The connection points of 3a and 43b, 43c and 43d, 43e and 43f are connected to the motor winding MC.

The gates of the transistors 43b, 43d, and 43f are connected to the motor drive control circuit 6A shown in FIG.
Are connected to the portions indicated by reference signs A, B, and C. As shown in FIG. 3, the input side of the drive control circuit power supply 60 is connected to the two power supply lines La2 and Lb2 of the DC stabilized power supply circuit 5, and the drive control circuit power supply 60 is connected to the DC stabilized power supply circuit 5. The output voltage of is converted into the voltage for driving the relay. Between the output-side + terminal and the-terminal of the drive control circuit power supply 60, a relay 6 forming a “short-circuit means” that operates while the AC power supply 1 is energized.
1 is connected, and the + side terminal is connected to one terminal of the break contact 61a which forms the "short-circuit means" of the relay 61 via the diode 62 for blocking direct current.

Since the relay 61 is energized when the AC power supply 1 is energized, the break contact 61a is opened, and the break contact 61a is connected when the AC power supply 1 fails. Diode 62
Between the cathode and one terminal of the break contact 61a,
The + side terminal of the capacitor 63 forming the “short-circuit means” is connected, and the − side terminal of this capacitor 63 is connected to the − side output terminal of the drive control circuit power supply 60 and is also grounded.

The other terminal of the break contact 61a is connected to the respective anodes of the DC blocking diodes 65a, 65b, 65c, and the diodes 65a, 65b,
The cathode of 65c corresponds to each transistor 4 shown in FIG.
It is connected to a gate drive circuit 64 for controlling and driving the gates of 2, 43a to 43f at a predetermined timing.

Next, the operation of the first embodiment constructed as described above will be explained. When the AC power supply is energized In this case, power can be supplied to all parts shown in FIG. 1, including the motor drive main circuit 4A and the motor drive control circuit 6A.

A predetermined DC voltage is applied from the drive control circuit power supply 60 to the relay 61 shown in FIG. 3, the relay 61 is turned on, and the break contact 61a is opened. Therefore, the DC voltage is applied to the capacitor 63 from the drive control circuit power supply 60 to charge it.

The transistors 42, 43a to 43f of the motor drive main circuit 4A are connected to the motor drive control circuit 6A.
On / off control is performed at a predetermined timing by a gate signal output from the gate drive circuit 64 shown in FIG. Further, the magnetic bearing control circuit 7 supplies a magnetic levitation current to the magnetic bearing winding BC. Therefore, the rotating body (rotor) of the DC brushless motor that constitutes the magnetic bearing type rotating device MB is rotated at a high speed at a predetermined speed.

At the time of power failure of AC power supply When a power failure occurs during high-speed rotation of the magnetic bearing type rotating device MB, the DC brushless motor immediately starts decelerating. Part of the electric power regenerated during deceleration is the motor drive main circuit 4A.
Is supplied to the stabilized DC power supply circuit 5 via the power supply, so that the motor drive control circuit 6A and the magnetic bearing control circuit 7 continue to operate even when a power failure occurs, and the rotating body rotates without touching down on the protective bearing. continue.

Even during a power failure, the drive control circuit power supply 60 operates while the magnetic bearing type rotating device MB operates by the regenerative energy, and the break contact 61a of the relay 61 remains open. The charging of the capacitor 63 is continued. Eventually, when the rotation speed of the DC brushless motor decreases and the regenerative power becomes smaller than the power consumed by the magnetic bearing control circuit 7 and the motor drive control circuit 6A, the DC stabilized power supply circuit 5 stops operating, The rotating body touches down on the protective bearing.

At this time, the drive control circuit power source 6 shown in FIG.
Since 0 also stops the operation, the relay 61 is turned off and the break contact 61a is restored to the connected state. Due to the connection of the break contact 61a, the electric charge accumulated in the capacitor 63 up to that time is changed to the break contact 61a and the diode 6
Transistors 43b, 43d, 4 through 5a-65c
Since 3f is turned on, the three-phase coil of the DC brushless motor is short-circuited.

At this time, the DC brushless motor acts as a generator, the rotational energy is consumed by the motor winding resistance and the cable resistance, and the speed is quickly reduced. Therefore, since the protective bearing is not rotated for a long time, the protective bearing is not worn.

Here, the transistors 43b, 43d, 4
Since the FET or the IGBT is used for the 3f as described above, the gate leakage current is extremely small, and the transistors 43b, 43d, 43f are provided until the rotating body stops.
The ON state of can be continued.

The charging voltage of the capacitor 63 is set to 12
V, FET gate leakage current is 100nA, FET
The capacity of the capacitor 63 required to supply a voltage of 10 V or more to the above for 5 minutes or more can be obtained by the following equation. 100 × 10 ^-9 × 3 × 5 × ^60/2 = 45 × 10 ^-6 F Therefore, the capacitor 63 should be 100 μ with a margin.
An electrolytic capacitor of about F may be used.

Modified Example of Motor Drive Control Circuit in First Embodiment By the way, a power failure occurs and the magnetic bearing control circuit 7 shown in FIG.
When the power supply to the magnetic bearing winding BC is stopped, the power supply to the magnetic bearing winding BC is also stopped. On the other hand, even if a power failure occurs, electric charges may still remain in the capacitors and the like around the power supply circuit in the entire magnetic bearing type rotating device. Therefore, even if the power supply to the magnetic bearing control circuit 7 is stopped due to the power failure as described above, the current for turning on the relay 61 may be continuously supplied from the drive control circuit power supply 60. Therefore, the motor drive control circuit 6 shown in FIG.
In some cases, A does not operate and the three-phase coil of the DC brushless motor is not short-circuited. Therefore, since the electric braking action does not work, the rotating body may continue to rotate for a long time after the rotating body is touched down.

As a means for avoiding such an inconvenience,
The motor drive control circuit 6B shown in FIG. 4 is suitable. Figure 4
As shown in, an opening / closing circuit 66 is arranged between the drive control circuit power supply 60 and the relay 61. This switching circuit 66
Is closed during energization and is opened when the magnetic bearing control circuit 7 is stopped due to a power failure.

According to this structure, when the magnetic bearing control circuit 7 stops, the opening / closing circuit 66 opens, so that the relay 61 is turned off and the break contact 61a is connected. Due to the connection of the break contact 61a, the electric charge stored in the capacitor 63 turns on the transistors 43b, 43d and 43f, so that the three phases of the motor are short-circuited.

Therefore, the DC brushless motor acts as a generator, and since the touch-down rotating body does not rotate the protective bearing for a long time, the protective bearing is not worn. (2) Second Embodiment In this embodiment, the electric charge stored in the capacitor during energization is added to the gate of the P-MOSFET at the time of power failure, and this P-MOS is added.
This is a case where the FET is turned on and the motor winding MC is short-circuited.

FIG. 5 shows a motor drive main circuit 4 of the second embodiment.
6 is a circuit diagram of B, and FIG. 6 is a circuit diagram of a motor drive control circuit 6C of the second embodiment. In this embodiment, P-MOSFETs are used for the transistors 45a to 45c and the directions of the diodes 66 and 68a to 68c are reversed.

Even with such a configuration, as in the first embodiment, current is supplied from the drive control circuit power supply 52 to the capacitor 67 via the diode 66 during energization, and the capacitor 67 stores electric charge. Then, at the time of a power failure, the transistor 45 is charged by the electric charge stored in the capacitor 67.
The a, 45c, and 45e are electrically connected to short-circuit the three-phase motor windings. Therefore, the DC brushless motor acts as a generator, and the rotating body touched down does not rotate the protective bearing for a long time, so that the protective bearing is not worn.

Also in the second embodiment, if an opening / closing circuit 66 similar to that shown in FIG. 4 is provided between the drive control circuit power source 60 and the relay 61, the same effect as in the first embodiment is obtained. Can be raised.

[0041]

As described above, according to the first aspect of the present invention, the short-circuit means short-circuits the winding of the motor by detecting the stop of the direct-current supply by the direct-current supply means. When is stopped, the motor acts as a generator,
The rotating body of the motor is electrically braked. Therefore, when the power supply is stopped, the rotating body stops rotating within a short time by the electric braking action, so that the life of the protective bearing can be extended.

According to the second aspect of the invention, the current supply to the winding of the motor is controlled via the switching element,
By using a relay, a break contact of this relay, and a capacitor as a short-circuit means, when the power supply is stopped, the rotating body stops rotating within a short time due to an electric braking action.

According to the third aspect of the invention, the opening / closing means disconnects the DC supplying means and the relay from each other when the magnetic bearing control means is deenergized, so that the break contact is immediately brought into the connected state. The electric charge stored in the capacitor causes the switching element to conduct, and the winding of the motor is short-circuited.

Therefore, even if electric charge remains in the capacitor of the power supply circuit constituting the magnetic bearing type rotating device at the time of power failure, the rotating body of the motor is immediately subjected to the electric braking action.

[Brief description of drawings]

FIG. 1 is a block diagram showing an overall configuration of an embodiment of the present invention.

FIG. 2 is a circuit diagram of a first embodiment of a motor drive main circuit of the above.

FIG. 3 is a circuit diagram of a first embodiment of a motor drive control circuit of the above.

FIG. 4 is a circuit diagram of a modified example of the first embodiment of the motor drive control circuit.

FIG. 5 is a circuit diagram of a second embodiment of the motor drive main circuit of the above.

FIG. 6 is a circuit diagram of a second embodiment of the motor drive control circuit of the above.

[Explanation of symbols]

 MB magnetic bearing device MC motor winding of magnetic bearing device 1 AC power supply 2 rectifier circuit (DC supply means) 4 motor drive main circuit (power conversion means) 4A motor drive main circuit 4B 4B motor of the second embodiment Drive main circuit 5 DC stabilized power supply circuit 6 Motor drive control circuit 6A Motor drive control circuit 6B of the first embodiment 6B Motor drive control circuit of the second embodiment 7 Magnetic bearing control circuit 41 Regenerative resistor 42, 43a to 43f N-MOS Transistors 45a to 45c P / MOS transistor 60 Power supply for drive control circuit 61 Relay (detection means) 61a Relay break contact (detection means) 63 Capacitor (detection means) 66 Switching circuit (opening and closing means)

Claims (3)

[Claims] 1. A direct current supplying means, an electromagnet for magnetically levitating a rotating body of a motor by a current supplied from the direct current supplying means, and a magnetic bearing control for controlling a position of the rotating body by controlling a magnetic field generated by the electromagnet. Means, power conversion means for converting the supply current from the DC supply means into AC for forming a rotating magnetic field for rotating the rotor of the motor, and detection of stop of power supply by the DC supply means, and the power conversion means A magnetic bearing type rotating device, comprising: a short-circuit means for short-circuiting a winding of a motor to which an alternating current is supplied from. 2. The power conversion means includes a switching element for controlling current supply to the winding of the motor, and the short-circuit means is a relay connected in parallel to an output side of the DC supply means. A break contact of the relay, one end of which is connected to a connection point of the relay and the capacitor, and the other end of which is connected to a conduction control unit that controls conduction of the switching element. Item 1. A magnetic bearing type rotating device according to item 1. 3. The magnetic bearing control means is arranged between the direct current supply means and the relay, connects the direct current supply means and the relay when the magnetic bearing control means is supplied with power, and stops the power supply by the magnetic bearing control means. 3. The magnetic bearing type rotating device according to claim 2, further comprising an opening / closing means for disconnecting the direct current supplying means and the relay if they are provided.