KR20170135531A - System and method for controlling bearing voltage of electric motor - Google Patents

System and method for controlling bearing voltage of electric motor Download PDF

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Publication number
KR20170135531A
KR20170135531A KR1020160067569A KR20160067569A KR20170135531A KR 20170135531 A KR20170135531 A KR 20170135531A KR 1020160067569 A KR1020160067569 A KR 1020160067569A KR 20160067569 A KR20160067569 A KR 20160067569A KR 20170135531 A KR20170135531 A KR 20170135531A
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KR
South Korea
Prior art keywords
bearing voltage
voltage
bearing
control signal
motor
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KR1020160067569A
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Korean (ko)
Inventor
김시경
최철형
김영필
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공주대학교 산학협력단
주식회사 필택
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Priority to KR1020160067569A priority Critical patent/KR20170135531A/en
Publication of KR20170135531A publication Critical patent/KR20170135531A/en

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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R19/00—Arrangements for measuring currents or voltages or for indicating presence or sign thereof
    • G01R19/0084—Arrangements for measuring currents or voltages or for indicating presence or sign thereof measuring voltage only
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R23/00—Arrangements for measuring frequencies; Arrangements for analysing frequency spectra
    • G01R23/16—Spectrum analysis; Fourier analysis
    • G01R23/165—Spectrum analysis; Fourier analysis using filters
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
    • G01R31/00—Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
    • G01R31/34—Testing dynamo-electric machines
    • G01R31/343—Testing dynamo-electric machines in operation
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02P—CONTROL OR REGULATION OF ELECTRIC MOTORS, ELECTRIC GENERATORS OR DYNAMO-ELECTRIC CONVERTERS; CONTROLLING TRANSFORMERS, REACTORS OR CHOKE COILS
    • H02P29/00—Arrangements for regulating or controlling electric motors, appropriate for both AC and DC motors

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  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Mathematical Physics (AREA)
  • Motor Or Generator Frames (AREA)

Abstract

The present invention relates to a system and a method for controlling a bearing voltage of a motor being operated. According to one embodiment of the present invention, the system for controlling a bearing voltage of the present invention comprises: a bearing voltage measuring unit for measuring a bearing voltage of a motor being operated; a control signal generating unit for removing noise included in the bearing voltage, and generating a bearing voltage control signal when pulsation of the bearing voltage is sensed as a result of monitoring a change in the bearing voltage; and a bearing voltage control unit for applying current corresponding to the generated bearing voltage control signal to the motor being operated. The bearing voltage control unit includes: an amplifier for outputting a second voltage which amplifies a first voltage included in a control signal transmitted from the control signal generating unit; a voltage-current converting unit for converting the second voltage output from the amplifier into a first current; and a negative current mirror unit for generating a second current on the basis of the first current.

Description

TECHNICAL FIELD [0001] The present invention relates to a system and a method for controlling a bearing voltage of an electric motor,

The present invention relates to a system and method for controlling the bearing voltage of an operating motor.

The electric motor includes a frame, a stator fixedly installed in the body and including a power-transmission winding, a rotor (not shown) which converts mechanical energy transferred from the stator and transmits the mechanical energy to the outside through a shaft a rotor, and a bearing for fixing the rotor.

In an electric motor, shaft voltage is generated between the shaft and the bearing due to magnetic unbalance, generation of electromotive force, etc., and a shaft current flows when an axial voltage is generated. The axial current flows through the contact portion between the shaft and the bearing, thereby raising the temperature of the shaft and the bearing contact portion. As a result, abrasion such as frosting or sparking occurs on the bearing surface, thereby causing the shaft to be damaged. These problems are directly related to the service life of the motor. Therefore, various methods such as a method of using an insulated bearing, a method of grounding a shaft using a brush, or a method of manually discharging by detecting a shaft voltage and an axial current are utilized . However, since this method needs to consider the internal structure of the motor, there are restrictions on the motor design. In order to use a plurality of sensors and transmit the sensing result to the manager or to secure the communication network for receiving the control signal from the manager The configuration is complicated and the design cost is inevitably increased.

A problem to be solved by one embodiment of the present invention is to provide a control system and method for measuring a bearing voltage of an operating motor and sensing an abnormality through a measured bearing voltage change to reduce a bearing voltage.

Embodiments according to the present invention can be used to accomplish other tasks not specifically mentioned other than the above-described tasks.

According to one embodiment of the present invention, there is provided a bearing voltage measuring unit for measuring a bearing voltage of an electric motor in operation, a noise measuring unit for measuring a bearing voltage, And a bearing voltage control unit for applying a current corresponding to the generated bearing voltage control signal to the motor in operation, wherein the bearing voltage control unit generates a control signal An amplifier for outputting a second voltage amplified from a first voltage included in a control signal transmitted from the amplifier, a voltage-to-current converter for converting a second voltage output from the amplifier into a first current, And a negative current mirror portion for generating a second current by the negative current mirror portion.

Here, the bearing voltage measuring unit is installed at one end of the rotating shaft of the motor, and is connected to a brush that slides up and down with respect to the rotating shaft, thereby measuring the bearing voltage.

In addition, the bearing voltage measuring unit may include a low pass filter.

Also, the control signal generator may generate a bearing voltage control signal by applying a Least Mean Square (LMS) algorithm to the bearing voltage.

According to one embodiment of the present invention, there is provided a method for controlling a bearing voltage, comprising: measuring a bearing voltage of an operating motor; removing noise included in the bearing voltage; monitoring a change in the bearing voltage; Generating a bearing voltage control signal when the pulsation of the bearing voltage is sensed and applying a current corresponding to the generated bearing voltage control signal to the motor in operation, .

Here, the step of measuring the bearing voltage may further include a function of a low pass filter.

Also, in the step of generating the bearing voltage control signal, a bearing voltage control signal can be generated by applying a Least Mean Square (LMS) algorithm to the bearing voltage.

According to one embodiment of the present invention, it is possible to quickly control the bearing voltage of an operating motor to prevent bearing wear such as frosting or sparking, to prevent burnout of the winding due to overheating of the motor, to improve the operation stability of the motor, Can be extended.

1 shows a configuration of a bearing voltage control system according to one embodiment of the present invention.
2 is a circuit diagram of the control signal generator of FIG.
3 shows a block diagram of an LMS algorithm according to one embodiment of the present invention.
4 is a circuit diagram of the bearing voltage control unit of FIG.
Figure 5 is a bearing voltage waveform measured between a motor frame and a brush according to one embodiment of the present invention.
6 is a frequency waveform of a bearing voltage measured between a motor frame and a brush according to an embodiment of the present invention.
Fig. 7 shows a bearing voltage control method using Fig.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings, which will be readily apparent to those skilled in the art to which the present invention pertains. The present invention may be embodied in many different forms and is not limited to the embodiments described herein. In order to clearly illustrate the present invention, parts not related to the description are omitted, and the same reference numerals are used for the same or similar components throughout the specification. In the case of publicly known technologies, detailed description thereof will be omitted.

In this specification, when a part is referred to as "including " an element, it is to be understood that it may include other elements as well, without departing from the other elements unless specifically stated otherwise. Also, "part" described in the specification means a unit for processing at least one function or operation, which can be implemented by hardware, software, or a combination of hardware and software.

In this specification, 'bearing voltage' means a voltage generated between both ends of a shaft of a motor or between a shaft and a bearing, which is also referred to as an 'axial voltage'. Also, 'bearing current' refers to the current flowing through the bearing and the shaft when the bearing voltage is generated, and it is also called 'axial current'.

Hereinafter, a bearing current control system according to an embodiment of the present invention will be described with reference to the drawings.

1 shows a configuration of a bearing voltage control system according to one embodiment of the present invention.

The bearing current control system 100 of FIG. 1 controls a bearing voltage based on a result of measuring a bearing voltage of the electric motor 200 and monitoring a change of the measured bearing voltage, and includes a bearing voltage measurement unit 110, A generation unit 120, and a bearing voltage control unit 130.

The electric motor 200 includes a frame 210, a stator 220 integrally fixed in the frame, a rotor 240 rotating the rotary shaft 230 using magnetic force inside the stator 220, And a brush 250 that slides up and down with respect to the rotary shaft 230. [ Although not shown in FIG. 1, the electric motor 200 further includes a bearing for supporting the rotating shaft 230. At this time, the frame 210 is grounded (GND), and when the frame 210 is charged with electricity due to a leakage current, the charged electricity flows through the ground.

The bearing voltage measuring unit 110 measures the bearing voltage of the motor 200 and measures the bearing voltage of the first amplifier 111 and the second amplifier 111 between the positive input terminal of the first amplifier 111 and the output terminal of the first amplifier 111 And includes a first resistor (Rf) 122 and a first capacitor (C) 123 connected in parallel. According to the embodiment of the present invention, the bearing voltage measuring unit 110 performs a low pass filter function. When the frequency of the input signal is lower than a preset cutoff frequency, the bearing voltage measuring unit 110 amplifies and outputs the signal. . At this time, a bearing voltage transmitted from the brush 250 is applied to the (+) input terminal of the first amplifier 111, and a negative (-) input terminal is grounded through the body 210.

The control signal generating unit 120 will be described with reference to FIGS. 2 to 3 below.

2 is a circuit diagram of the control signal generator of FIG.

2, the control signal generator 120 removes noise from the signal output from the first amplifier 111 and generates a control signal including a control voltage for reducing the bearing voltage. At this time, the control signal may further include a start signal of the bearing voltage controller 130. According to an embodiment of the present invention, the control signal generation unit 120 includes an LMS algorithm processing unit 123 that generates a bearing voltage control signal based on an LMS (Least Mean Square) adaptation algorithm. Specifically, the LMS adaptation algorithm monitors a change in the bearing voltage transmitted from the bearing voltage measuring unit 110, and generates a bearing voltage control signal when an abnormality is detected.

3 shows a block diagram of an LMS algorithm according to one embodiment of the present invention.

The LMS algorithm of FIG. 3 is aimed at achieving control objectives by estimating unknown system coefficients. The bearing noise voltage of the motor varies greatly depending on the environmental factors such as the rotation state of the motor, temperature, vibration, humidity and operating conditions. In the embodiment of the present invention, the noise can be removed from the bearing voltage of the changing motor and the rotation performance of the motor can be improved by using the LMS detection algorithm using the average predicted value.

(N) is a reference input signal, d (n) is a system output signal, y (n) is a control output signal, h (n) is an impulse response signal of H Is an error signal between the system output signal d (n) and the control output signal y (n). P (z) is the primary path transfer function, and W (n) and H (z) are the control filter transfer functions.

The LMS algorithm of FIG. 3 can be expressed as Equation 1 below, and the convergence coefficient mu of Equation 1 is a step size (μ) that determines the stability and convergence of the bearing voltage control system between 0 and 1 . For example, the convergence coefficient may be 0.5. In the embodiment of the present invention, an LMS algorithm having a convergence coefficient (μ) using a vector norm is used to improve convergence speed.

Figure pat00001

2, the control signal generating unit 120 includes a second amplifier 121 for amplifying the output signal of the first amplifier 111, a second amplifier 121 for amplifying the analog signal amplified through the second amplifier 121, To-analog converter 122 for converting the digital control signal generated by the LMS algorithm processing unit 123 into an analog control signal, and an analog-to-digital converter 124 for converting the digital control signal generated by the LMS algorithm processing unit 123 to an analog control signal, And a third amplifier 125 for amplifying the signal and transmitting the amplified signal to the bearing voltage controller 130.

Also, according to an embodiment of the present invention, the control signal generator 120 may be implemented by a DSP (Digital Signal Processor), and may include an LMS algorithm execution function and a memory management function.

The bearing voltage control unit 130 will be described below with reference to FIG.

4 is a circuit diagram of the bearing voltage control unit of FIG.

The bearing voltage controller 130 of FIG. 4 amplifies the voltage V in from the control signal generator 120 through the fourth amplifier 131 and outputs the amplified voltage as V 1. The output voltage of the fourth amplifier 131 V 1 is converted to I c through a voltage-to-current converter located at the output terminal of the inverter. At this time, the voltage-current conversion unit includes the first transistor 132 and the second resistor 133. Then, I out is generated from I c through the current mirror 134. That is, by applying I out to the electric motor body 210 through the bearing voltage control unit 130, the bearing voltage of the electric motor can be reduced.

FIG. 5 shows the measured bearing voltage waveform between the motor frame and the brush according to one embodiment of the present invention. It can be seen that the peak-to-peak of the bearing voltage between the motor frame and the brush is about 9.52V.

6 is a frequency waveform of a bearing voltage measured between a motor frame and a brush according to an embodiment of the present invention.

6, the frequency of the measured bearing voltage between the motor frame and the brush includes a wide frequency component and a dominant harmonic frequency component. At this time, the bearing voltage ripples at a dominant harmonic fundamental frequency, and the maximum value is as large as about -20dB. When the pulsation of the bearing voltage is sensed through the control signal generation unit 120, it is determined that the conductor included in the rotor 240 is broken and a bearing voltage control signal can be generated.

The bearing voltage generated during the operation of the motor is measured using the bearing current control system 100 according to the embodiment of the present invention and the operation stability of the motor can be improved by quickly detecting and removing the dominant harmonic frequency component have.

Fig. 7 shows a bearing voltage control method using Fig.

First, the bearing voltage of the motor in operation is measured through the bearing voltage measuring unit 110 (S10).

Thereafter, the noise of the bearing voltage measured in step S10 is removed through the control signal generator 120 (S20), and it is determined whether the bearing voltage is pulsating (S30).

If pulsation is detected in step S30, a control signal for reducing the bearing voltage is generated (S40).

Thereafter, the bearing voltage controller 130 generates a current corresponding to the control signal generated in operation S40 and applies the generated current to the motor body 210 (S50). Specifically, converting the bearing reducing the voltage (V 1) after amplifying the control signal generated in S40 step with bearing reduced current (I C) and, via the current mirror 134 corresponding to the bearing reducing the current (I C) The mirror current I out can be generated and applied to the motor body 210.

According to the embodiment of the present invention, the bearing voltage generated during the operation of the motor can be controlled to prevent the bearing welding, the overheating and damage of the motor, the breakage of the lubricating oil insulation strength, or the destruction of the stator winding.

The embodiments of the present invention described above are not necessarily implemented only in the apparatus, but may be implemented through a recording medium on which a program or a program for realizing a function corresponding to the configuration of the embodiment of the present invention is recorded.

While the present invention has been particularly shown and described with reference to exemplary embodiments, it is to be understood that the invention is not limited to the disclosed exemplary embodiments, but, on the contrary, It belongs to the scope.

100: Bearing current control system 110: Bearing voltage measurement unit
120: control signal generator 130: bearing voltage controller
200: electric motor 210: body
220: stator 230: rotating shaft
240: Rotor 250: Brush

Claims (7)

A bearing voltage measuring unit for measuring a bearing voltage of an operating motor,
A control signal generator for generating a bearing voltage control signal when a pulsation of the bearing voltage is sensed as a result of monitoring a change in the bearing voltage by removing noise included in the bearing voltage,
A bearing voltage control unit for applying a current corresponding to the generated bearing voltage control signal to the motor in operation,
Lt; / RTI >
The bearing voltage control unit includes:
An amplifier for outputting a second voltage obtained by amplifying a first voltage included in a control signal transmitted from the control signal generator,
A voltage-to-current converter for converting a second voltage output from the amplifier to a first current,
And a negative current mirror part
/ RTI > The method of claim 1,
Wherein the bearing voltage measuring unit is installed at one end of a rotary shaft of the electric motor and connected to a brush slid up and down with respect to the rotary shaft to measure the bearing voltage. The method of claim 1,
Wherein the bearing voltage measuring unit includes a low pass filter. The method of claim 1,
Wherein the control signal generator generates the bearing voltage control signal by applying a Least Mean Square (LMS) algorithm to the bearing voltage. Measuring a bearing voltage of an operating motor,
Removing noise included in the bearing voltage,
Monitoring a change in the bearing voltage to detect a pulsation of the bearing voltage,
Generating the bearing voltage control signal when the pulsation of the bearing voltage is sensed, and
Applying a current corresponding to the generated bearing voltage control signal to the motor in operation
/ RTI > The method of claim 5,
Wherein the step of measuring the bearing voltage further includes the function of a low pass filter. The method of claim 5,
Wherein the bearing voltage control signal generating step generates the bearing voltage control signal by applying a Least Mean Square (LMS) algorithm to the bearing voltage.
KR1020160067569A 2016-05-31 2016-05-31 System and method for controlling bearing voltage of electric motor KR20170135531A (en)

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
KR102558372B1 (en) * 2023-02-03 2023-07-24 멜콘 주식회사 Method for detecting bearing current of inverter-fed-motor

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
KR102558372B1 (en) * 2023-02-03 2023-07-24 멜콘 주식회사 Method for detecting bearing current of inverter-fed-motor

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