JP2007202307A - Leak current detection circuit and water-cooled motor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a leak current detection circuit which can detect a small leak current from a winding when water is used as cooling liquid. <P>SOLUTION: A leak detection electrode DET1 is provided in a motor M1, and wiring therefrom is connected with a DC power supply HiV and further connected through a leak detector DET2 to the minus side of the wiring from the DC power supply for supplying a DC voltage to a PWM driver. The leak detector DET2 has a filter for cutting AC component, and detects only the magnitude of the DC current. When at least one of the winding lines U1, V1 and W1 becomes insulation failure, current from the DC power supply HiV flows through the insulator failure and detected by the leak detector DET2. A decision is made that the winding of the motor M1 is insulation failure when a predetermined threshold is exceeded. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a leakage current detection circuit and a water-cooled motor.

  In recent years, high throughput of a semiconductor exposure apparatus has been demanded, and in order to meet this demand, there is an increasing demand for high-speed and high-output motors. As a cooling method for a high-speed and high-power motor, conventionally, an insulating liquid such as florinate is circulated in the motor, thereby cooling the windings. However, insulating liquids such as florinate have low specific heat and poor cooling efficiency, and recently, water has been used as a cooling liquid.

  However, since water has poor insulating properties, if the motor winding deteriorates or is damaged and current leaks from it, the entire motor will be damaged. Therefore, when water is used as the cooling liquid, it is necessary to detect a minute current leak from the winding, to give an alarm, or to stop use.

  The present invention has been made in view of such circumstances, and provides a leakage current detection circuit that can detect a small leakage current from a winding, and a water-cooled motor that can use the leakage current detection circuit. Let it be an issue.

  A first means for achieving the above object is a circuit for detecting a leakage current from a winding of a water-cooled motor driven by a PWM drive device, in which the water-cooled winding is housed and insulated. A direct current flowing between the leak detection electrode provided in the motor casing and the positive or negative side of the direct current line supplying power to the PWM drive device is detected, and the direct current exceeds a predetermined value. This is a leakage current detection circuit in which a leakage current is generated in the winding.

  When detecting the leakage current from the motor winding, if you try to detect the AC component, in addition to the leakage current, a minute current leaked by the inductive component and capacitive coupling will be detected and become noise, and the S / N ratio Becomes worse. In this means, since the DC current flowing between the positive electrode side or the negative electrode side of the DC line that supplies power to the PWM drive device and the leak detection electrode is detected, it is difficult to be affected by these noises. Detection with a good / N ratio is possible.

  A second means for solving the above problem is a circuit for detecting a leakage current from a winding of a water-cooled motor driven by a PWM drive device, in which the water-cooled winding is housed and insulated. A current detector for detecting a current flowing between a leak detection electrode provided in a motor housing and a positive or negative side of a DC line supplying power to the PWM drive device; and the current detector A synchronous detector for synchronously detecting the detected current in accordance with the phase of the current flowing in the winding, and a leakage current that causes a leakage in the winding when the output of the synchronous detector exceeds a predetermined value This is a detection circuit.

  In this means, since the AC current flowing between the positive electrode side or the negative electrode side of the DC line supplying power to the PWM drive device and the leak detection electrode is detected, the S / N ratio is poor as described above. However, since synchronous detection is performed in accordance with the phase of the current flowing through the winding and the leakage current is determined based on the output, the S / N ratio is increased and detection with high sensitivity is possible.

  A third means for solving the above-mentioned problems is a water-cooled motor characterized by having a leak detection electrode connected to the leak current detection circuit as the first means or the second means. is there.

  According to the present invention, when water is used as a cooling liquid, a leakage current detection circuit capable of detecting a small leakage current from a winding and a water-cooled motor capable of using the leakage current detection circuit are provided. can do.

  Hereinafter, an example of an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a diagram showing an outline of a motor and a leakage current detection circuit as a first example of an embodiment of the present invention. A power source supplied from a DC power source (not shown) is supplied to a well-known three-phase AC generating PWM drive circuit composed of IGBT1 to IGBT6 which are switching elements, and outputs thereof are (L1, C1), (L2, C2), It is supplied to the windings U1, V1, W1 of the motor M1 through an LC filter composed of (L3, C3). This is a known PWM drive circuit and an electrical circuit of a three-phase motor driven by the PWM drive circuit. The housing of the motor M1 is made of an insulator, and cooling water flows into the housing from the cooling water inlet, cools the windings U1, V1, and W1 of the motor M1, and then discharges from the cooling water outlet. Is done.

  Inside the motor M1, a leak detection electrode DET1 is provided, the wiring from there is connected to the DC power supply HiV, and further, the wiring from the DC power supply that supplies a DC voltage to the PWM drive circuit through the leak detector DET2 is provided. Connected to the negative electrode side. The line from the leak detector DET2 may be connected to the positive side of the wiring from the DC power supply that supplies the DC voltage to the PWM drive circuit. The leak detector DET2 has a filter that cuts off the alternating current and detects only the magnitude of the direct current.

  When at least one of the windings U1, V1, and W1 has an insulation failure, a current from the DC power supply HiV flows through the insulation failure portion. This current is detected by the leak detector DET2, and has a predetermined threshold level. Is exceeded, it is determined that the insulation of the winding of the motor M1 is defective.

  FIG. 2 is a diagram showing an outline of a motor and a leakage current detection circuit which are a second example of the embodiment of the present invention. The circuit for driving the motor in FIG. 2 is the same as that shown in FIG. 1, so the same components as those shown in FIG.

  In FIG. 2, a leak detection electrode DET1 is provided inside the motor M1, and the wiring from there goes through the leak detector DET3, and the negative side of the wiring from the DC power supply that supplies a DC voltage to the PWM drive circuit Connected to. The line from the leak detector DET3 may be connected to the positive side of the wiring from the DC power supply that supplies the DC voltage to the PWM drive circuit.

  A pulse is input to the leak detector DET3 from the oscillator OSC1. These pulses are three pulses synchronized with the U-phase current, V-phase current, and W-phase current, respectively. The leak detector DET3 detects the current flowing between the leak detection electrode DET1 and the negative electrode side of the wiring from the DC power supply that supplies the DC voltage to the PWM drive circuit, and these are detected as these three pulses, respectively. Synchronously rectifies and forms three detection signals. When at least one of these detection signals exceeds a predetermined threshold level, it is determined that the insulation of the winding of the motor M1 is defective.

  As described above, in the leak detector DET3, a minute current leaked due to an inductive component or capacitive coupling flows between the leak detection electrode DET1 and the negative electrode side of the wiring from the DC power supply. However, by performing synchronous rectification in synchronization with the U-phase current, the V-phase current, and the W-phase current, it is possible to improve the S / N ratio against these noises and perform leak detection.

It is a figure which shows the outline | summary of the motor which is the 1st example of embodiment of this invention, and a leakage current detection circuit. It is a figure which shows the outline | summary of the motor which is the 2nd example of embodiment of this invention, and a leakage current detection circuit.

Explanation of symbols

IGBT1 to IGBT6 ... switching elements (IGBT), L1 to L3 ... reactance, C1 to C3 ... capacitor, M1 ... motor, U1 to W1 ... winding, DET1 ... leak detection electrode, HiV ... DC power supply, DET2 ... leak detector , DET3 ... leak detector, OSC1 ... oscillator

Claims (3)

  A circuit for detecting a leakage current from a winding of a water-cooled motor driven by a PWM drive device, wherein the leakage-detecting electrode is housed in an insulated motor housing, in which the water-cooled winding is housed. When a DC current flowing between the positive electrode side or the negative electrode side of the DC line that supplies power to the PWM driving device is detected and the DC current exceeds a predetermined value, a leakage current is generated in the winding. Leakage current detection circuit.   A circuit for detecting a leakage current from a winding of a water-cooled motor driven by a PWM drive device, wherein the leakage-detecting electrode is housed in an insulated motor housing, in which the water-cooled winding is housed. , A current detector for detecting a current flowing between a positive electrode side or a negative electrode side of a DC line that supplies power to the PWM drive device, and a current detected by the current detector A synchronous detector that performs synchronous detection in accordance with a phase; and a leak current detection circuit that detects that a leak has occurred in the winding when the output of the synchronous detector exceeds a predetermined value.   A water-cooled motor comprising a leak detection electrode connected to the leak current detection circuit according to claim 1.

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