WO2009087915A1

WO2009087915A1 - Ac motor drive system and method for detecting failure of the system

Info

Publication number: WO2009087915A1
Application number: PCT/JP2008/073600
Authority: WO
Inventors: Shuichi Mihara
Original assignee: Kabushiki Kaisha Yaskawa Denki
Priority date: 2008-01-10
Filing date: 2008-12-25
Publication date: 2009-07-16
Also published as: JPWO2009087915A1

Abstract

It is possible to easily detect a failure of each of AC motors electrically connected in parallel and driven by a single motor drive device. More specifically, by detecting a power cable disconnection or grounding, it is possible to protect the AC motor drive system. The AC motor drive system includes: an AC motor unit formed by a plurality of AC motors arranged into a module; and a motor drive device electrically connected in parallel to respective armature windings of the AC motors for driving the AC motor unit. The system further includes: at least one DC current detector in an arbitrary one of three phases; and a failure detection unit which connects in-phase cables of the two sets of AC motors with opposite current polarities of the in-phase cables of the two sets of the AC motors so that the magnetic field of the DC current detector is cancelled and the detection current of the current detector is zero, thereby judging whether the detection current is greater than a predetermined value.

Description

AC motor drive system and its abnormality detection method

The present invention relates to a system for detecting an abnormality such as a disconnection or a ground fault of a power cable of the AC motor in a system in which a single servo driver controls an AC motor such as a plurality of linear motors, and an abnormality detection method thereof.

Japanese Patent Publication No. 7-28513 is a technique for diagnosing insulation deterioration during normal operation of one linear motor coil (Patent Document 1).
Japanese Patent Application Laid-Open No. 2004-212201 detects a ground fault by supplying a current to a motor coil via a power cable when the motor is stopped (Patent Document 2).
In all of the above patent documents, a ground fault of a motor coil is detected, and a motor power cable that is operating in a system that controls a plurality of linear motors with one servo driver is disconnected without causing a ground fault. In this case, since the disconnection cannot be detected, a normal motor that has not disconnected is broken.

Applicant to a technology that provides a linear motor with a small inertia, suitable for high-speed operation, good controllability, and miniaturization when applying a linear motor with an unusually long mover stroke to semiconductor manufacturing equipment Japanese Patent Laid-Open No. 2003-244929 (Patent Document 3). This technique is a linear motor composed of a mover provided with a permanent magnet and a stator provided with a coil for generating a moving magnetic field. The stator is configured by connecting a plurality of modules divided in length per unit in the longitudinal direction. By sending a command from the host controller to each of the modules via a servo driver device for controlling the position of the motor, this prior art continuously moves and positions the mover. Further, the divided module is an integrated servo driver. That is, the plurality of divided modules are composed of a linear motor and a servo driver (motor driving device) that drives the linear motor.
Japanese Patent Publication No. 7-28513 (Japan) JP 2004-212201 (Japan) JP 2003-244929 A (Japan)

Conventionally, a method for detecting disconnection of a motor power cable has not been established in a system that controls a plurality of linear motors with a single servo driver. Therefore, even when one of the multiple linear motors is disconnected, or when the internal winding coil is disconnected or grounded due to a motor failure, excessive current flows into the normal motor, and even the normal motor It was out of order.

Patent Document 1 is a technique for diagnosing insulation deterioration during normal operation of one linear motor coil. Patent Document 2 is a technique for detecting a ground fault of a motor winding without actually operating a motor.

Patent Documents

1 and 2 are both techniques for detecting a ground fault. In a system in which a single servo driver controls a plurality of linear motors, a disconnection when a motor power cable in operation is disconnected without a ground fault. It could not be detected.

Patent Document 3 is common to the system of the present invention in that the linear motor is made into a plurality of modules. Patent Document 3 is different from the system configuration of the present invention in that each linear motor module is provided with a servo driver which is a driving device for driving each linear motor module. The system configuration of the present invention includes a plurality of linear motors that are modularized, but there is only one driving device that drives and controls them. For this reason, the drive unit itself cannot accurately protect the linear motor from overcurrent if any one of the multiple linear motors electrically connected in parallel causes an abnormality such as disconnection or ground fault. It was.

The present invention has been made in view of such problems. When a plurality of AC motors are driven by a single motor driving device, the power cables of the AC motors electrically connected in parallel are disconnected or grounded. It is an object of the present invention to provide an AC motor drive system that can easily detect and protect those abnormalities when they are entangled and a method for detecting the abnormality.

In order to solve the above-described problems, the present invention provides an AC motor unit composed of a plurality of modularized AC motors, and an armature winding of each of the plurality of AC motors electrically connected in parallel to each other. In an AC motor drive system including a motor drive device that drives an AC motor unit,
At least one DC current detector is provided in any one of the three phases, and the in-phase cables of the two sets of AC motors are connected to the in-phase cables of the two sets of AC motors so that the magnetic fields of the DC current detectors are canceled out. The cable is provided with an abnormality detection unit which is connected so that the current polarity of the cable is reversed and the detection current of the current detector becomes zero, and determines whether the detection current is larger than a predetermined value set in advance. It is a feature.

The DC current detector may be a DCCT having a contact output so that a protection circuit can be assembled.
In addition, the abnormality detection unit according to claim 1 is incorporated in a housing of the motor driving device.
Further, the present invention is characterized in that an emergency stop unit for emergency stopping the AC motor system based on an output signal of the abnormality detection unit is provided.
In addition, the base block of the main circuit transistor of the motor driving device or the input side or the output side of the motor driving device based on the abnormality determination output signal of the abnormality detection unit or the emergency stop signal which is the output signal from the contact output circuit according to claim 1 The power supply is shut off by a power breaker provided in the above.
Further, in the present invention, the AC motor is an AC linear motor.
The AC motor drive system according to claim 1 is applied to any one of a liquid crystal exposure stage drive system, a reticle stage drive system, and a wafer stage drive system.

Also, an AC motor unit composed of a plurality of modularized AC motors, and a motor drive device that drives the AC motor unit by one unit in parallel with each armature winding of the plurality of AC motors. An abnormality detection method for an AC motor drive system comprising: at least one DC current detector in any one of the three phases, wherein the in-phase cables of two sets of AC motors are connected to the magnetic field of the DC current detector. So that the current polarity of the in-phase cable of the two sets of AC motors is reversed and the detection current of the current detector becomes zero, so that the detection current is larger than a predetermined value set in advance In this case, it is determined that abnormality is detected.

According to the present invention, when a plurality of AC motors (linear motors) are driven by a single motor driving device (servo driver), the power cables of the AC motors (linear motors) electrically connected in parallel are disconnected, When a ground fault occurs, those abnormalities can be easily detected, and each AC motor (linear motor) can be protected.
Further, the present invention has a feature that it is possible to detect disconnection of the power cable and abnormality of ground fault before actually operating the AC motor. Therefore, the present invention can be applied to each linear motor system of a liquid crystal exposure stage driving system, a reticle stage driving system, and a wafer stage driving system that require ultra-high accuracy positioning.
Further, according to the present invention, the number of abnormality detecting DCCTs used when the number of connected AC motor modules is two or three can be reduced to one or two, respectively.
Further, the present invention does not simply measure and protect the current value, but detects the current imbalance, so that the current rated capacity of the current detector can be reduced and the malfunction of the system can be prevented.

The figure which shows the structure of the multi-connection linear motor system to which the method of this invention is applied. The figure which shows the detection circuit structure in case two linear motors apply the method of this invention. The figure which shows the detection circuit structure in case three linear motors apply the method of this invention. Block diagram of a detection circuit to which the method of the present invention is applied It is a figure which shows the detection circuit structure of this invention in case there are two linear motors. It is a figure which shows the detection circuit structure of this invention in case there are three linear motors.

Explanation of symbols

1 Servo driver (motor drive device)
2 Linear motor 1 (AC motor)
3 Linear motor 2 (AC motor)
4 Linear motor 3 (AC motor)
5 Magnet 6

Motor power cable

7, 7a, 7b, 7c, 7d Current detector (DCCT)
8 Abnormality detection circuit 9 Contact output circuit 10 Emergency stop circuit 11 Linear scale 12 Pole sensor 13 Serial converter

Hereinafter, specific examples of the method of the present invention will be described with reference to the drawings.

FIG. 1 is a diagram showing a configuration of a multi-coupled linear motor system of the present invention. In the figure, reference numeral 1 denotes a servo driver which is a motor driving device for driving a linear servo motor.

Reference numerals

2 and 3 denote a linear motor 1 (2), which is an AC motor driven by a servo driver, and a linear motor 2 (3). 5 is a magnet for a linear motor, and 6 is a linear motor power cable. 11 is a linear scale which is a position sensor for detecting the position of the moving element, 12 is a pole sensor for detecting the magnetic pole position of the moving element, and 13 is a signal converted from the linear scale and the hall sensor to serial data to the servo driver 1. It is a serial converter that outputs.
The linear motor unit is composed of a plurality of linear motors 1, linear motors 2,. The servo driver 1 is electrically connected in parallel with the armature windings of the plurality of linear motors 1, linear motors 2,..., Applies a voltage to these armature windings, and drives the linear motor. The linear motor magnet 5 is arranged by connecting the magnet portions (field poles) of the plurality of linear motors 1, linear motors 2,... So as to be in line with the linear motor moving direction (hereinafter referred to as tandem type). . In this way, a linear motor having a large rated torque and rated power is configured by connecting and arranging modules having predetermined rated torque and rated power. In FIG. 1, the linear motor 1, linear motor 2,... Are arranged in a straight line along the direction of movement of the linear motor. However, like the gantry type, two different drive shafts are connected in a gate shape (linear The linear motor 1 and the linear motor 2 may be arranged in parallel to the moving direction of the motor. Normally, the armature winding of the linear motor is on the stator side, and the field magnet 5 is on the mover side. Since the movement range of the linear motor is limited, the armature winding of the linear motor can be on the moving element side and the field magnet 5 can be on the stator side.

A motor controller system having a large capacity can be constructed by electrically connecting the module sliders of a plurality of small rated capacity linear motors shown in FIG. 1 in parallel (referred to as a multi-coupled linear motor slider) and supplying power. The feature of this multi-coupled linear motor moving element is that a large capacity linear motor drive system (eg, injection molding, liquid crystal exposure stage, semiconductor exposure apparatus) can be easily constructed without having a lineup of linear motors up to a large capacity.

Fig. 2 shows an example in which two linear motors are connected in tandem or gantry type. FIG. 2 shows a state in which the power lines of the two linear motors are electrically connected in parallel from the servo driver 1. Reference numeral 7 denotes a current detector. As this current detector, a direct current detector (Direct-Current-Current Transformer, hereinafter referred to as DCCT) capable of measuring a high frequency from direct current to several tens of kilometers (Hz) is used. DCCT measures the current by passing the wire to be measured through a toroidal core and detecting the strength of the magnetic field created by the wire. Here, the toroidal core is obtained by solidifying magnetic powder into a donut shape and baking it. For this reason, there exists the characteristic which can detect an electric current non-contactingly. The three-phase outputs (U, V, W) of the servo driver 1 are connected to the three-phase inputs (U1, V1, W1), (U2, V2, W2) of the linear motor 1 and linear motor 2, respectively. At that time, DCCT is installed in any one of the three phases, for example, the U phase. In this case, the current polarities of the U1 and U2 phases are reversed so that the DCCT magnetic field is offset so that the DCCT detection current becomes zero. Two arrows in the DCCT indicate that the current polarities of the U1 and U2 phases are in opposite directions.

By passing the same phase of the power cables of the linear motor 1 (2) and linear motor 2 (3), which are AC motors, through the DCCT of 7 in a staggered direction, the detected current is zero when normal. At the time of disconnection, current flows only through one cable, so that current is detected by DCCT of 7. It is normal to operate the emergency stop circuit that shuts off the drive power to the servo driver of the multi-coupled linear motor system according to the disconnection detection block diagram of FIG. It is possible to protect the motor from malfunctioning due to excessive current flowing through the motor.

The DCCT (7) used here must select a DC component that can be detected. When the linear motor becomes unable to move due to any external factors such as screw engagement, the current of the DC component continues to flow to the motor. In this case, in order to operate the detection circuit normally, DCCT ( For 7), it is necessary to select one capable of detecting a DC component. Further, for application to a linear servo motor, the DCCT (7) needs to be a thing that is not damaged even if the detected current has a high frequency.

FIG. 3 shows a configuration example in the case of three linear motors. 3 is different from FIG. 2 in that a current detector (7b) is added to the four linear motors 3 and the V phase. By passing 2

linear motors

1 and 3 through DCCT (7a) and passing 3

linear motors

2 and 4 through DCCT (7b), the same number of linear motors can be connected. A detection circuit can be configured with the idea. Similar to the DCCT (7) in FIG. 2 described above, the DCCT (7b) has a current polarity of the V1 and V2 phases reversed so that the magnetic field of the DCCT (7b) is canceled out. ) So that the detected current becomes zero.
If both of the power cables passing through the DCCT are disconnected at the same time, this is equivalent to the disconnection of one phase output from the servo driver 1, so that the abnormality detection circuit shown in FIG. (8) operates.
Moreover, if the current of only one phase is compared among the three-phase power supply of the AC linear motor, the unbalanced current is provided with the current detector even if the other phase without the current detector is disconnected. Since it flows to the phase, an abnormality (disconnection, ground fault) can be detected as in the case described above.

FIG. 4 is a block diagram of the abnormality detection circuit of the present invention. In the figure, 8 is an abnormality detection circuit, 9 is a contact output circuit, and 10 is an emergency stop circuit. The abnormality detection circuit 8 receives the output signal of the current detector 7 and determines that it is abnormal when the input signal is larger than a predetermined value set in advance. This predetermined value I0 is ideally when I0> 0 (A) is satisfied, but in reality, it is slightly different due to the difference in the power cable wiring length to each moving element (movable element) and other errors. Unbalanced current is generated. In consideration of this point, the predetermined value I0 is set to (rated current per moving element / 2) or less, and is set as small as possible within a range in which no malfunction occurs during normal operation. A current detector 7 having a high-speed response is used. In order to protect the armature winding of each linear motor from overcurrent, the DCCT uses a DCCT having a contact output so that a protection circuit can be built in the DCCT. In this case, select one that can set the operating current range of the contact within the DCCT rated current value.

The contact output circuit (9) gives an emergency stop signal to the emergency stop circuit (10) based on the abnormality judgment from the abnormality detection circuit (8), and quickly protects the system. As an emergency stop method, whether the main circuit transistor of the servo driver 1 is the base block or the input side of the servo driver (1) based on the abnormality determination output signal of the abnormality detection circuit (8) or the emergency stop signal of the contact output circuit (9). The power is shut off by a power circuit breaker provided on the output side. In addition, an abnormality detection unit that is an abnormality detection circuit (8) may be incorporated in the housing of the motor drive device (servo driver). The predetermined value I0 is stored in a nonvolatile memory of a control unit (not shown) of the servo driver (1), which is a motor driving device, or a nonvolatile memory of a host controller of the servo driver 1. The abnormality detection circuit (8) can be configured by hardware (analog circuit) that compares the analog signal of the current detector 7 and a predetermined value I0 using an operational amplifier. Alternatively, both signals can be A / D converted and compared by the servo driver 1 or the CPU of the host controller.

FIG. 5 is a diagram showing a detection circuit configuration (basic form) according to the present invention when there are two linear motors. FIG. 5 differs from FIG. 2 in that two DCCTs are used. FIG. 2 using one DCCT cannot protect against the abnormality of the DCCT itself. On the other hand, FIG. 5 in which DCCT is used for each of the two phases can protect the abnormality of the DCCT itself and can further improve the reliability of the system as compared with FIG.

FIG. 6 is a diagram showing the configuration of the detection circuit of the present invention when there are three linear motors. It is a figure which shows the detection circuit structure (basic form) of this invention in case there are three linear motors. 6 is different from FIG. 3 in that four DCCTs are used. FIG. 3 using two DCCTs cannot protect against the abnormality of the DCCT itself. On the other hand, FIG. 6 using two DCCTs for two phases (using a total of four DCCTs) can protect the abnormality of the DCCT itself, and can further improve the reliability of the system than FIG.

The semiconductor device manufacturing process includes a lithography process in which a predetermined circuit pattern formed on a reticle is exposed and transferred onto a wafer. An exposure apparatus is used for this exposure transfer. In an exposure apparatus, a reticle and a wafer are fixed to a reticle stage and a wafer stage, respectively, and exposure and transfer are performed while driving the reticle stage and wafer stage in synchronization with a linear motor. The present invention is particularly applicable to reticle stage drive systems, wafer stage drive systems, and liquid crystal exposure stage drive system linear motor systems that require ultra-high precision positioning on the order of several tens of nanometers.

Claims

An AC motor unit including a plurality of modularized AC motors, and a motor driving device that electrically connects the armature windings of the plurality of AC motors in parallel and drives the AC motor unit by one unit. In the provided AC motor drive system,
At least one DC current detector is provided in any one of the three phases, and the in-phase cables of the two sets of AC motors are connected to the in-phase cables of the two sets of AC motors so that the magnetic fields of the DC current detectors are canceled out. Connect the current polarity of the cable in the reverse direction so that the detection current of the current detector becomes zero,
An AC motor drive system comprising an abnormality detection unit for determining whether or not the detected current is larger than a predetermined value set in advance.
2. The AC motor drive system according to claim 1, wherein the DC current detector is a DCCT having a contact output so that a protection circuit can be assembled.
The AC motor drive system according to claim 1, wherein the abnormality detection unit is built in a housing of the motor drive device.
The AC motor drive system according to claim 1, further comprising an emergency stop unit that performs an emergency stop on the AC motor system based on an output signal of the abnormality detection unit.
Based on the abnormality determination output signal of the abnormality detection unit or the emergency stop signal which is the output signal from the contact output circuit, the power block provided on the base block of the main circuit transistor of the motor driving device or on the input side or output side of the motor driving device The AC motor drive system according to claim 1, wherein the power source is shut off by a device.
2. The AC motor drive system according to claim 1, wherein the AC motor is an AC linear motor.
2. The AC motor drive system according to claim 1, wherein the AC motor drive system is applied to any one of a liquid crystal exposure stage drive system, a reticle stage drive system, and a wafer stage drive system.
An AC motor unit including a plurality of modularized AC motors, and a motor driving device that electrically connects the armature windings of the plurality of AC motors in parallel and drives the AC motor unit by one unit. In the AC motor drive system abnormality detection method provided,
At least one DC current detector is provided in any one of the three phases, and the in-phase cables of the two sets of AC motors are connected to the in-phase cables of the two sets of AC motors so that the magnetic fields of the DC current detectors are canceled out. Connect the current polarity of the cable in the reverse direction so that the detection current of the current detector becomes zero,
An abnormality detection method for an AC motor drive system, wherein an abnormality detection is determined when the detected current is larger than a predetermined value set in advance.