JP2006006041A - Abnormality detecting method for three-phase linear motor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To detect the abnormality of a coil while using a three-phase linear motor. <P>SOLUTION: Voltages applied to a U-phase, a V-phase and a W-phase respectively are detected, and inputted to an operational amplifier (summer) OP1 via input resistors R1, R2 and R3, respectively. Applied voltage values of the respective phases added by the operational amplifier OP1 are inputted to two comparators CP1, CP2. An output from the comparator CP1 is made to be 0V (Low level) when an output from the operation amplifier OP1 is higher than a first reference voltage (plus), and made to be a supply voltage (Hi level) when the output of the operation amplifier is lower than the reference voltage. An output from the comparator CP2 is made to be 0V (Low level) when the output from the operational amplifier OP1 is lower than a second reference voltage, and made to be a supply voltage (Hi level) when the output of the operation amplifier is higher than the reference voltage. When output side voltages of the CP1, CP2 fall in Low levels, the W-phase coil can be determined to be abnormal. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a method for detecting an abnormality in a three-phase linear motor.

  The three-phase linear motor is used for driving a reticle stage or wafer stage in an exposure apparatus. These three-phase linear motors are configured by combining a stator and a mover. The moving magnet type has a coil on the stator side and a permanent magnet on the stator side, and a coil on the mover side. There is a moving coil type in which a permanent magnet is provided on the stator side. In the following description, a moving magnet type three-phase linear motor will be described as an example. However, these descriptions also apply to a moving coil type.

  FIG. 2 shows an outline of a circuit of a three-phase linear motor. Upon receiving the speed command signal given as the “command signal”, the controller forms and outputs PWM pulse signals to be given to the U phase, the V phase, and the W phase. This output is amplified by a U-phase, V-phase, and W-phase PWM drive amplifier, and is supplied to a star-connected U-phase coil, V-phase coil, and W-phase coil.

  FIG. 3 shows details of the U-phase coil, the V-phase coil, and the W-phase coil that are shown as rectangles in FIG. The U-phase coil has 10 coils from U-L1 to U-L10, the V-phase coil has 10 coils from V-L1 to VL10, and the W-phase coil has 10 coils from W-L1 to W-L10. It consists of individual coils.

  The U-phase coil will be described. Each of the coils U-L1 to U-L10 has a switch coupled to the U-phase PWM drive amplifier via SW-U1 to SW-U10, and the controller is positioned at the position of the mover. In response, each switch is turned on and off. Normally, a switch corresponding to two coils corresponding to the position of the mover is turned on. The same applies to the V phase and the W phase.

  A coil of a three-phase linear motor may be disconnected or short-circuited during use. When this happens, it may be detected due to an abnormality in the running performance of the stator, but it may not be understood by simply looking at it, which causes poor running control and position control of the stator. You may not even notice it. In particular, when used in a reticle stage or wafer stage of an exposure apparatus, precise control is often required, and if a coil abnormality occurs, it may lead to a serious accident. In addition, these stages have recently been increased in speed, and if an abnormality in the coil is not detected and repaired at an early stage, there is a possibility that the stage may be damaged due to abnormal running of the stage.

  This invention is made | formed in view of such a situation, and makes it a subject to detect abnormality of the coil during use of a three-phase linear motor.

  A first means for solving the above problem is a method for detecting an abnormality in a coil of a three-phase linear motor driven by a current control method, and detects a voltage applied to each phase coil. When the absolute value of the sum is equal to or greater than a predetermined value, it is determined that any one of the coils is abnormal.

  In a three-phase linear motor that controls the current flowing through the coils of each phase, the current value is controlled so that the sum of the currents flowing through the three phases is zero. Since the resistance values of the coils of each phase are the same, if the coils of each phase are normal, the sum of the voltage values applied to the coils of each phase should be zero.

  However, if a break or short occurs in any of the coils, the current value does not change because it is controlled, but the voltage value changes and the sum of the voltage values applied to each phase does not become zero. .

  In this means, taking into account variations in manufacturing errors, etc., a predetermined value that allows for allowances is determined, the voltage applied to the coils of each phase is detected, and the absolute value of the sum exceeds a predetermined value Any of the coils is determined to be abnormal.

  A second means for solving the above problem is a method for detecting an abnormality of a coil of a three-phase linear motor driven by a voltage control method, and detects a current value applied to the coil of each phase. Then, when the absolute value of the sum is equal to or greater than a predetermined value, it is determined that any one of the coils is abnormal. (Claim 2)

  In a three-phase linear motor that controls the voltage applied to each phase coil, the voltage value is controlled so that the sum of the voltages applied to each phase of the three phases becomes zero. Since the resistance values of the coils of each phase are the same, if the coils of each phase are normal, the sum of the current values flowing through the coils of each phase should be zero.

  However, if a break or short occurs in any of the coils, the voltage value does not change because it is controlled, but the current value changes, and the sum of the voltage values flowing through each phase does not become zero.

  In this means, taking into account variations in manufacturing errors, etc., a predetermined value was determined in consideration of allowances, the current value applied to the coils of each phase was detected, and the absolute value of the sum was greater than or equal to the predetermined value At this time, it is determined that any one of the coils is abnormal.

  According to the present invention, the abnormality of the coil can be detected during the use of the three-phase linear motor.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a diagram for explaining an abnormality detection method for a three-phase linear motor according to an embodiment of the present invention, in which a circuit for carrying out the present invention is added to the circuit shown in FIG. is there.

  Upon receiving the speed command signal given as the “command signal”, the controller forms and outputs PWM pulse signals to be given to the U phase, the V phase, and the W phase. This output is amplified by a U-phase, V-phase, and W-phase PWM drive amplifier, and is supplied to a star-connected U-phase coil, V-phase coil, and W-phase coil. The U-phase coil, the V-phase coil, and the W-phase coil that are indicated by rectangles in the figure are actually a collection of a plurality of coils as shown in FIG.

  Hereinafter, although the circuit attached in order to implement this invention is demonstrated, since these circuits are the same about U phase, V phase, and W phase, only the W phase is demonstrated about the following description. . Further, it is assumed that the three-phase linear motor is of a current control type, and the controller determines the pulse width of the PWM control so that the current flowing through each phase coil becomes a predetermined value.

  The voltages applied to the U-phase, V-phase, and W-phase are detected and input to the operational amplifier (adder) OP1 through the input resistors R1, R2, and R3, respectively. The operational amplifier OP1 basically has a function of adding three inputs. However, the operational amplifier OP1 has an integration function by coupling the capacitor C1 to the feedback circuit, and thereby, the ripple component included in each phase voltage. Has the effect of smoothing and removing.

  The applied voltage value of each phase added by the operational amplifier OP1 is input to the two comparators CP1 and CP2. The two reference voltages divided by the resistors R5, R6, and R7 are input to the two comparators CP1 and CP2, respectively. The first reference voltage is positive and the second reference voltage is negative. It is said that.

  The output of the comparator CP1 is set to 0 V (Low level) when the output of the operational amplifier OP1 is higher than the first reference voltage, and is set to the supply voltage (Hi level) otherwise. Yes. On the other hand, the output of the comparator CP2 is set to 0 V (Low level) when the output of the operational amplifier OP1 is lower than the second reference voltage, and is set to the supply voltage (Hi level) otherwise. It has become.

  Accordingly, the output side of the comparators CP1 and CP2 connected in parallel becomes Hi level when the output of the operational amplifier is between the first reference voltage and the second reference voltage, and becomes Low level in other cases. Therefore, by setting the two reference voltages so as to correspond to the maximum value and the minimum value when the W-phase coil is normal, when the output side voltages of CP1 and CP2 become low level, W It can be determined that the phase coil is abnormal.

  Although the above description is about the case where the three-phase pulse motor is driven by the current control method, the same method can be adopted when the three-phase pulse motor is driven by the voltage drive method. In this case, a resistance for current detection is inserted in the wiring to each phase, and the voltage at both ends is detected, or the current value to each phase is detected by CT and the output is output. May be connected to the input resistors R1, R2, and R3 of FIG.

It is a figure for demonstrating the abnormality detection method of the three-phase linear motor which is embodiment of this invention. It is a figure which shows the outline | summary of the circuit of a three-phase linear motor. It is a figure which shows the actual structure of each phase coil.

Explanation of symbols

R1 to R8 ... resistors, OP1 ... operational amplifiers (adders), CP1, CP2 ... comparators, SW1 ... switches, C1 ... capacitors

Claims (2)

A method for detecting an abnormality in a coil of a three-phase linear motor driven by a current control method, in which a voltage applied to a coil of each phase is detected, and the absolute value of the sum exceeds a predetermined value A method of detecting an abnormality of a three-phase linear motor, wherein one of the coils is determined to be abnormal. A method for detecting an abnormality in a coil of a three-phase linear motor driven by a voltage control method, in which a current value applied to a coil of each phase is detected, and the absolute value of the sum becomes a predetermined value or more. An abnormality detection method for a three-phase linear motor, wherein any one of the coils is determined to be abnormal.

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