WO2022190550A1

WO2022190550A1 - Magnetic saturation detecting circuit, noise filter, motor driver, and magnetic saturation detecting method

Info

Publication number: WO2022190550A1
Application number: PCT/JP2021/047132
Authority: WO
Inventors: 浩太郎淺羽
Original assignee: オムロン株式会社
Priority date: 2021-03-08
Filing date: 2021-12-20
Publication date: 2022-09-15
Also published as: JP2022136924A

Abstract

This magnetic saturation detecting circuit is provided with: a detecting unit for detecting a physical quantity related to magnetic saturation in a common mode choke coil provided in series with a path from a power source; a determining unit for determining that magnetic saturation has occurred in the common mode choke coil, on the condition that a magnetic field intensity of the common mode choke coil, estimated from the detected physical quantity, satisfies a predetermined criterion; and a reporting unit for reporting the result of the determination to the outside.

Description

Magnetic saturation detection circuit, noise filter, motor driver, and magnetic saturation detection method

The present invention relates to a magnetic saturation detection circuit, a noise filter, a motor driver, and a magnetic saturation detection method for detecting magnetic saturation of a choke coil.

Conventionally, in the field of FA (Factory Automation), robotics, etc., a noise filter with a common mode choke coil is installed on the power supply path to suppress high-frequency noise that occurs during the switching operation of power conversion. When a common mode current exceeding the regulation flows into the power supply path as high frequency noise accompanying switching operation, the common mode choke coil installed in the noise filter causes magnetic saturation, which is effective in suppressing high frequency noise. may not be available. In the above fields, if a sufficient suppression effect against high-frequency noise cannot be obtained, the effects of noise that enters through the power supply path may cause circuit malfunctions or stoppages in facilities or peripheral devices that involve power conversion. may invite. For this reason, at a work site where equipment or equipment that involves power conversion is installed, workers can visually check the sound emitted by the noise filter during operation of the equipment, or the current waveform flowing through the noise filter using an oscilloscope, etc. monitoring work is carried out. In this way, it takes time and effort to confirm that magnetic saturation does not occur, and the monitoring work is a burden on the operator. The following patent documents exist as prior art documents that describe technology related to the technology described in this specification.

JP 2019-100579 A

By the way, Patent Document 1 discloses detecting a ground fault current flowing through a choke coil for the purpose of reducing the cost of a device (current transformer, zero-phase current transformer, etc.) that detects a ground fault current in a power supply path. . Although Patent Document 1 describes whether or not the magnetic flux generated in the core by the alternating current and the magnetic flux generated in the core by the return current cancel each other out in the core, consideration is given to the effect of suppressing magnetic saturation or high-frequency noise. not done. Conventionally, the magnetic saturation of the noise filter for motor drivers is determined by the manufacturer using a noise terminal voltage test to check the amount of noise, or if the user selects it, the magnetic saturation is not detected by checking the coil sound and current waveform. I was sure. SUMMARY OF THE INVENTION In view of the above problems, it is an object of the present invention to provide a technique capable of detecting magnetic saturation of a choke coil and monitoring the effect of suppressing high-frequency noise.

One form of the disclosed technology for solving the above problems is
a detection unit that detects a physical quantity related to magnetic saturation of a common mode choke coil provided in series in a path from a power supply;
a determination unit that determines that magnetic saturation has occurred in the common mode choke coil on condition that the strength of the magnetic field of the common mode choke coil estimated from the detected physical quantity satisfies a predetermined criterion;
a notification unit that notifies the result of the determination to the outside;
A magnetic saturation detection circuit, comprising:

As a result, the magnetic saturation detection circuits (10, 10a, 10b) detect physical quantities (current value, core magnetic flux), the strength of the magnetic field of the common mode choke coil 21 can be estimated. The magnetic saturation detection circuit (10, 10a, 10b) determines that the magnetic field is in a magnetic saturation state when the estimated strength of the magnetic field exceeds a set threshold value or exceeds the threshold value, and the result of the determination can be notified to the outside. Since the magnetic saturation of the choke coil can be detected and the effect of suppressing high-frequency noise can be monitored, the workload associated with monitoring magnetic saturation can be reduced.

Further, in one form of the disclosed technique, the notification unit may notify information related to suppression of high-frequency noise in a circuit including the power supply. As a result, the magnetic saturation detection circuits (10, 10a, 10b) send information (cable length, cable type (with or without shield), appropriate filter Inductor settings, etc.) and the degree of margin until magnetic saturation, etc., can be notified, so usability related to magnetic saturation countermeasures can be improved.

Further, in one aspect of the disclosed technique, the detection unit detects a current flowing through a common mode choke coil, and the determination unit estimates the magnetic field strength of the common mode choke coil from the detected current value. In addition, it may be determined that magnetic saturation has occurred in the common mode choke coil on condition that the estimated magnetic field strength exceeds a first threshold. As a result, the magnetic saturation detection circuit (10, 10a, 10b), which is a detection circuit, obtains the magnetic field strength H, which is the strength of the magnetic field generated in the common mode choke coil 21, from the current value using equation (1). By comparing the obtained magnetic field intensity with the magnetic field at which magnetic saturation occurs, which is the first threshold value, it can be determined whether or not the obtained magnetic field intensity exceeds the threshold value. Magnetic saturation detection circuits ( 10 , 10 a , 10 b ) can determine whether or not magnetic saturation has occurred based on the strength of the magnetic field formed by the current flowing through the common mode choke coil 21 .

Further, in one aspect of the disclosed technology, the detection unit detects magnetic flux of a common mode choke coil,
The determination unit estimates a magnetic flux density of the common mode choke coil from the detected magnetic flux, and the magnetic saturation of the common mode choke coil is detected on condition that the estimated magnetic flux density exceeds a second threshold. It may be determined that it has occurred. As a result, the magnetic saturation detection circuit (10, 10a, 10b), which is a detection circuit, obtains the magnetic flux density B, which is the strength of the magnetic field generated in the common mode choke coil 21 from the core magnetic flux, using equation (2). can be performed, and it can be determined whether or not the obtained magnetic flux density exceeds the threshold by comparison with the magnetic flux saturation density, which is the second threshold. Magnetic saturation detection circuits ( 10 , 10 a , 10 b ) can determine whether or not magnetic saturation has occurred based on the magnetic flux density of core 21 a of common mode choke coil 21 .

Further, in another aspect of the technology disclosed, a noise filter including a common mode choke coil, wherein the notification unit notifies information related to the degree of noise removal by the noise filter. It may be a noise filter comprising the described magnetic saturation detection circuit. Even in such a form, the noise filter 20 determines that magnetic saturation has occurred when the strength of the magnetic field estimated by the magnetic saturation detection circuit (10, 10a, 10b) satisfies a predetermined condition, The result of the determination can be notified to the outside. In addition, as information related to the degree of noise removal by the noise filter via the notification unit 105, the current magnetic field strength H, magnetic flux density B, margin until magnetic saturation, etc. can be notified. Usability can be improved. It is possible to detect the magnetic saturation of the choke coil and monitor the effect of suppressing high-frequency noise without stopping the operation of the equipment, etc., even during the operation of the equipment, equipment, etc. accompanying power conversion.

In another aspect of the technology disclosed, a motor driver comprising the magnetic saturation detection circuit according to any one of claims 1 to 4 or the noise filter according to claim 5, wherein the magnetic saturation detection circuit, or The motor driver may perform notification prompting a predetermined process based on the determination result notified from the noise filter. The motor driver 3 can take measures according to the presence or absence of magnetic saturation of the common mode choke coil 21 determined by the magnetic saturation detection circuit (10, 10a, 10b) without stopping the operation even during operation. . Since the magnetic saturation of the choke coil can be detected and the effect of suppressing high-frequency noise can be monitored, the workload associated with monitoring magnetic saturation can be reduced.

In another aspect of the disclosed technique, the predetermined process includes exchanging a power line connecting between the motor driver and a motor to which drive power generated by the motor driver is supplied, or and prompting the user to review the stray capacitance between the power line and the motor. When magnetic saturation occurs, it is possible to prompt specific measures to eliminate the magnetic saturation that has occurred in the noise filter 20 through the display panel of the motor driver 3 or the like.

Further, in another aspect of the disclosed technique, the magnetic saturation detection circuit calculates a margin amount until the magnetic saturation occurs when the common mode choke coil is not magnetically saturated, and the calculated You may make it alert|report the margin amount which was carried out. When magnetic saturation does not occur, the amount of margin leading to magnetic saturation can be displayed on the display panel of the motor driver 3, so the number of motors 50 that can be driven by the motor driver 3, the number of cables that can be connected, etc. can be grasped. As a result, the usability of countermeasures against magnetic saturation can be improved.

In another aspect of the disclosed technology, a physical quantity related to magnetic saturation of a common mode choke coil provided in series in a path from a power supply is detected,
Determining that magnetic saturation has occurred in the common mode choke coil on condition that the strength of the magnetic field of the common mode choke coil estimated from the detected physical quantity satisfies a predetermined criterion;
Notifying the result of the determination to the outside;
A magnetic saturation detection method, comprising:

Even in such a form, the magnetic saturation detection circuit (10, 10a, 10b) is related to the magnetic saturation of the common mode choke coil 21 detected by the current transformer CT and the magnetic flux measuring coil 23, which are the detection units. The strength of the magnetic field of the common mode choke coil 21 can be estimated from physical quantities (current value, core magnetic flux). The magnetic saturation detection circuit (10, 10a, 10b) determines that the magnetic field is in a magnetic saturation state when the estimated strength of the magnetic field exceeds a set threshold value or exceeds the threshold value, and the result of the determination can be notified to the outside. Since it is possible to detect the magnetic saturation of the choke coil and monitor the suppression effect of high-frequency noise without stopping the operation of the equipment, etc., even during the operation of equipment and devices that involve power conversion, the work burden related to monitoring magnetic saturation can be reduced. can be reduced.

According to the present invention, the magnetic saturation of the choke coil can be detected and the effect of suppressing high-frequency noise can be monitored, so the workload associated with monitoring magnetic saturation can be reduced.

1 is a block diagram showing a schematic configuration of a noise filter according to Example 1 of the present invention; FIG. 1 is a block diagram showing a schematic configuration of a magnetic saturation detection circuit in Example 1 of the present invention; FIG. It is a figure explaining the measurement of the core magnetic flux of the common mode choke coil based on the modification of this invention. FIG. 11 is a block diagram showing a schematic configuration of a magnetic saturation detection circuit according to a modification of the invention; FIG. 3 is a block diagram showing a schematic configuration of a motor drive system according to Example 2 of the present invention; It is a figure which shows an example of the hardware constitutions of the control part which concerns on Example 2 of this invention. 9 is a flowchart showing an example of magnetic saturation detection processing according to Example 2 of the present invention;

[Example of application]
Hereinafter, application examples of the present invention will be described with reference to the drawings.
FIG. 1 illustrates a block diagram showing a schematic configuration of a noise filter 20 according to an application example of the present invention. A noise filter 20 according to an application example includes a pair of input terminals (TP1, TP2), a pair of output terminals (TP3, TP4), and a common mode choke coil 21, and a power supply input between the pair of input terminals. Suppress high-frequency noise of electric power and output to a pair of output terminals. When the common mode current I defined by the specifications of the noise filter 20 or the like flows through the power supply path, the common mode choke coil 21 is magnetically saturated, and the effect of suppressing high frequency noise is not sufficient. was there. For this reason, in equipment or the like that generates desired power through switching operation, the current flowing through the noise filter 20 during power conversion is detected via the test circuit 9 or the like, and the waveform of the current is measured using an oscilloscope or the like. It was confirmed that magnetic saturation did not occur by visually recognizing with .

In the form according to this application example, as shown in FIG. 2, a magnetic saturation detection circuit detects whether or not magnetic saturation has occurred in the common mode choke coil 21 of the noise filter 20 based on the current value flowing through the common mode choke coil 21. set up. The magnetic saturation detection circuit detects, for example, the current value flowing through the common mode choke coil 21 of the noise filter 20 via the current detection section. Then, the magnetic saturation detection circuit obtains the magnetic field strength, which is the strength of the magnetic field generated in the common mode choke coil 21, from the detected current value, and determines whether or not the magnetic field strength exceeds the magnetic field in which magnetic saturation occurs. judge. The magnetic saturation detection circuit according to this application example notifies the outside of the determination result indicating the presence or absence of occurrence of magnetic saturation determined by the magnetic field intensity formed by the current flowing through the common mode choke coil 21 . According to this application example, since the magnetic saturation generated in the common mode choke coil 21 can be detected through the magnetic saturation detection circuit, the trouble of connecting the test circuit 9 to the noise filter 20 and monitoring the current waveform as in the conventional art is eliminated. does not occur.

In another embodiment according to this application example, as shown in FIGS. 3 and 4, the core magnetic flux of the common mode choke coil 21 is measured, the magnetic flux density indicating the strength of the magnetic field is obtained, and the magnetic flux density indicates the magnetic saturation. It can also be determined whether the magnetic flux density that produces Another form of magnetic saturation detection circuit 10a can determine magnetic saturation occurring in the common mode choke coil 21 based on the magnetic flux density B obtained from the core magnetic flux. Then, the magnetic saturation detection circuit 10a can notify the determination result to the outside. For example, in the noise filter 20 that integrally accommodates the magnetic saturation detection circuit 10a, if the housing is provided with an LED or the like indicating that magnetic saturation has occurred, the notification unit 105 based on the determination result , the LED can be lit. When the noise filter 20 has a terminal for outputting a signal indicating the detection result, a host device (power converter, power conversion system, etc.) having the filter on the power supply path receives the detection result output from the output terminal. Based on the indicated signal, processing such as display lighting of an LED or the like and notification display on a display panel or the like may be performed. In this embodiment as well, the magnetic saturation detection circuit 10a makes it possible to detect the magnetic saturation of the choke coil and monitor the effect of suppressing high-frequency noise during the operation of equipment that involves power conversion.

As another embodiment according to this application example, as shown in FIGS. 5 to 7, the physical quantity related to the magnetic saturation of the common mode choke coil 21 is measured through the detection unit 29 of the noise filter 20, and the magnetic saturation is detected from the physical quantity. A system form including a magnetic saturation detection circuit for detection may be employed. In this system, based on the notification from the magnetic saturation detection circuit, an LED or the like provided on the housing etc. that indicates the magnetic saturation state is lit, a message is displayed on the display panel etc. to the effect that magnetic saturation has occurred, an electronic sound or Notification through a speaker or the like is possible. According to the reported contents, the length of the power line W2, wiring routing, change of cable type (with or without shield), review of stray capacitance between the ground that causes magnetic saturation, and appropriate action according to the operating environment, etc. It is possible to encourage selection of a noise filter having an inductor. It is also possible to display the amount of margin until magnetic saturation calculated by the magnetic saturation detection circuit. Therefore, the usability of monitoring magnetic saturation can be improved.

[Example 1]
Specific embodiments of the present invention will be described in more detail below with reference to the drawings.

<Circuit configuration>
FIG. 1 is a block diagram showing a schematic configuration of a noise filter 20 according to an embodiment of the invention. The noise filter 20 shown in FIG. 1 includes a pair of input terminals (TP1, TP2), a pair of output terminals (TP3, TP4), and a common mode choke coil 21. The noise filter 20, for example, is provided in series on the path of the power supply, suppresses high-frequency noise of the power supply power input between the pair of input terminals (TP1, TP2), and Output. The common mode choke coil 21 is inserted in series between a pair of input terminals (TP1, TP2) and a pair of output terminals (TP3, TP4), and comprises a core 21a, windings 21b, and windings 21c. have. The winding 21b is connected in series between the input terminal TP1 and the output terminal TP3, and the winding 21c is connected in series between the input terminal TP2 and the output terminal TP4. Between

lines

22a and 22b to which common mode choke coil 21 and output terminals (TP3, TP4) are connected, X capacitors (interphase capacitors) C1 and C2 and Y capacitor C3 are provided. X capacitors C1 and C2 are inserted in series between

lines

22a and 22b, and Y capacitor C3 has one end connected to the connection point between X capacitor C1 and X capacitor C2, and the other end connected to the ground reference potential on the side of the housing. It is connected to a certain FG (Frame Ground). X capacitors C1, C2 reduce normal mode noise between lines 22a-22b, and Y capacitor C3 reduces common mode noise.

Here, when a current I that generates a magnetic flux density exceeding the magnetic flux saturation density of the core of the noise filter 20 flows through the power supply path, the common mode choke coil 21 is magnetically saturated, and high frequency noise is sufficiently suppressed. In some cases, it did not have the desired effect. For example, in a facility that generates desired power from alternating current power supplied from a main power supply through switching operations of switching elements or the like, the current flowing through the noise filter 20 when power conversion is performed is passed through the test circuit 9 or the like. It was confirmed that magnetic saturation did not occur by detecting the current through an oscilloscope or the like and visually recognizing the waveform of the current.

The test circuit 9 includes, for example, a rectifier circuit 9a, a voltage dividing circuit 9b, and a regulator 9c. AC power output from a pair of output terminals (TP3, TP4) of the noise filter 20 is input to the rectifier circuit 9a. The rectifier circuit 9a rectifies the AC power through a bridge circuit composed of, for example, rectifying elements (diode elements), and the rectified DC power is output to the voltage dividing circuit 9b. In the voltage dividing circuit 9b, the voltage value of the DC power rectified through the rectifying circuit 9a is divided into predetermined voltage values, which are input to the regulator 9c. The voltage value after voltage division is stabilized via the regulator 9c and supplied to a detection circuit such as an oscilloscope. In a facility equipped with power conversion equipment, an operator or the like connects the test circuit 9 to the pair of output terminals (TP3, TP4) of the noise filter 20, and the current output from the test circuit 9 is The waveform was observed using an oscilloscope, etc., and the presence or absence of magnetic saturation was confirmed. As described above, in the conventional work, there was a work burden for checking the presence or absence of magnetic saturation.

In the embodiment according to the present embodiment, a magnetic saturation detection circuit is provided for detecting whether or not magnetic saturation has occurred in the common mode choke coil 21 of the noise filter 20 based on the current value flowing through the common mode choke coil 21 . The magnetic saturation detection circuit detects, for example, the current value flowing through the common mode choke coil 21 of the noise filter 20 via the current detection section. Then, the magnetic saturation detection circuit obtains the magnetic field strength, which is the strength of the magnetic field generated in the common mode choke coil 21, from the detected current value, and determines whether or not the magnetic field strength exceeds the magnetic field in which magnetic saturation occurs. judge. The magnetic saturation detection circuit according to the present embodiment notifies the outside of the determination result indicating the presence or absence of occurrence of magnetic saturation, which is determined by the strength of the magnetic field formed by the current flowing through the common mode choke coil 21 . According to this embodiment, the magnetic saturation occurring in the common mode choke coil 21 can be detected through the magnetic saturation detection circuit. does not occur. In addition, through the magnetic saturation detection circuit, it is possible to grasp the magnetic saturation during the operation of facilities, equipment, etc. that involve power conversion.

In this embodiment, a current transformer CT is exemplified as an example of a current detector that detects the current flowing through the common mode choke coil 21 . As shown in FIG. 1, the current transformer CT may detect a current flowing between a pair of input terminals (TP1, TP2) on the input side and the common mode choke coil 21, and on the output side, A current flowing between the common mode choke coil 21 and the pair of output terminals (TP3, TP4) may be detected. When measuring the current flowing on the output side, in order to accurately measure the common mode current flowing through the common mode choke coil 21, the current flowing through the common mode choke coil side from the Y capacitor C3 provided between the

lines

22a and 22b is measured. should be measured.

FIG. 2 is a block diagram showing a schematic configuration of the magnetic saturation detection circuit 10 according to this embodiment. FIG. 2 shows an example of a detection circuit for obtaining the magnetic field strength generated in the common mode choke coil 21 from the current value detected by the current transformer CT and determining whether or not the magnetic field strength exceeds the magnetic field causing magnetic saturation. are exemplified. The magnetic saturation detection circuit 10 of FIG. 2 includes a low-pass filter 101, a determination section 11, and a notification section 105. The low-pass filter 101 suppresses high-frequency components of the current detected by the current transformer CT other than the switching frequency that causes magnetic saturation. The notification unit 105 is an interface that outputs a signal indicating magnetic saturation detected by the magnetic saturation detection circuit 10 to the outside. A current value (CT detection value) detected by the current transformer CT is low-pass filtered through the low-pass filter 101 and input to the determination section 11 .

In the determination unit 11 , the calculation unit 102 obtains the magnetic field strength H indicating the strength of the magnetic field generated in the common mode choke coil 21 from the current value input through the low-pass filter 101 . The magnetic field intensity H (A/m) can be obtained using the following formula (1).

In equation (1), "N" represents the number of turns of the windings (21b, 21c), and "l" represents the magnetic path length. Such parameters are defined by the specifications of the common mode choke coil 21 and the like.

The magnetic field strength H obtained by the calculation unit 102 is input to the comparator 104 and compared with the threshold value 103 . Here, the threshold value 103 is set with information indicating the strength of the magnetic field at which the common mode choke coil 21 is magnetically saturated. For example, when it is defined by the magnetic flux saturation density Bs, the threshold value 103 is set to ([Bs·k/μ], k; adjustment coefficient, μ; magnetic permeability). In this embodiment, the information (Bs·k/μ) indicating the strength of the magnetic field set as the threshold 103 corresponds to an example of the “first threshold”. The comparator 14, for example, compares the magnetic field intensity H input to the positive terminal with the threshold value 103 input to the negative terminal to determine whether the magnetic field intensity H exceeds the magnetic field at which magnetic saturation occurs. judge. The determination result is input to the notification unit 105 and notified to the outside of the magnetic saturation detection circuit 10 via the notification unit 105 .

Note that the notification unit 105 may notify the outside of information related to suppression of high-frequency noise along with notification of the determination result. For example, information (cable length, cable type (with or without shield), appropriate filter inductor setting, etc.) that prompts review of stray capacitance on the power supply path can be notified. Further, when it is determined that magnetic saturation does not occur, the notification unit 105 may notify the magnetic field intensity H calculated by the calculator 102 together with the determination result. A difference amount (margin amount) between the intensity H and the threshold value 103 may be obtained and notified to the outside. By notifying the magnetic field strength H calculated by the calculator 102, it is possible to grasp the current high-frequency noise suppression effect. In addition, by notifying the difference amount (margin amount) between the magnetic field strength H calculated by the computing unit 102 and the threshold value 103, it is possible to recognize the degree of margin until magnetic saturation occurs. Based on the margin amount, for example, it becomes possible to grasp the number of connectable cables and the number of connectable motors, etc. in the host device (power converter, power conversion system, etc.), so that usability related to magnetic saturation countermeasures can be improved. .

The noise filter 20 shown in FIG. 1 integrally accommodates the magnetic saturation detection circuit 10 according to the present embodiment, and the housing of the noise filter 20 is provided with an LED or the like indicating that magnetic saturation has occurred. In this case, the notification unit 105 may turn on the LED based on the determination result. From the lighting display of the LED, it can be grasped that the common mode choke coil 21 is magnetically saturated. The noise filter 20 can also have a terminal for outputting a signal indicating the detection result. Information related to suppression of high-frequency noise can be notified to the outside via the terminal. High-level equipment (power converter, power conversion system, etc.) provided on the power supply path with the noise filter 20 integrally housing the magnetic saturation detection circuit 10 according to the present embodiment indicates the detection result output from the output terminal Based on the signal, it is possible to perform processing such as lighting of an LED or the like and notification display on a display panel or the like. According to the present embodiment, the magnetic saturation of the choke coil can be detected through the magnetic saturation detection circuit 10 during the operation of equipment that involves power conversion.

[Modification]
In Example 1, an example of a circuit for determining magnetic saturation based on the magnetic field strength H obtained from the current flowing through the common mode choke coil 21 is illustrated. Magnetic saturation occurring in the common mode choke coil 21 can also be detected using the core magnetic flux of the core 21a. In the modified example, a magnetic saturation detection circuit 10a using the core magnetic flux of the core 21a will be described.

FIG. 3 is a diagram explaining measurement of the core magnetic flux of the common mode choke coil 21 according to the modification. In the modified example, the core magnetic flux (Φ) of the common mode choke coil 21 is detected through the magnetic flux measuring coil 23 having n turns. The core magnetic flux (Φ) detected by the magnetic flux measuring coil 23 is input to the magnetic saturation detection circuit 10a.

FIG. 4 is a block diagram showing a schematic configuration of a magnetic saturation detection circuit 10a according to a modification. In FIG. 4, the magnetic flux density indicating the strength of the magnetic field is obtained from the magnetic flux (Φ) detected through the magnetic flux measuring coil 23, and it is determined whether or not the magnetic flux density exceeds the magnetic flux density that causes magnetic saturation. An example of a detection circuit is illustrated. The determination unit 11a of the magnetic saturation detection circuit 10a includes a calculation unit 106 that obtains the magnetic flux density B (Wb/m ² ) from the core magnetic flux (Φ) detected by the magnetic flux measuring coil 23 .

The calculation unit 106 indicates the strength of the magnetic field generated in the common mode choke coil 21 based on the core magnetic flux (Φ) detected by the magnetic flux measuring coil 23 and the cross-sectional area S (m ² ) of the core 21a. A magnetic flux density B is obtained. The magnetic flux density B (Wb/m ² ) can be obtained using the following formula (2).

In equation (2), "n" represents the number of turns of the magnetic flux measuring coil 23, and "∫vdt" represents voltage change due to common mode current.

The magnetic flux density B obtained by the calculation unit 106 is input to the comparator 104 and compared with the threshold value 103a. Here, the magnetic flux saturation density (B·m) indicating the strength of the magnetic field at which the common mode choke coil 21 is magnetically saturated is set as the threshold value 103a. In the modified example, the magnetic flux saturation density set as the threshold 103a corresponds to an example of the "second threshold". The comparator 14 compares, for example, the magnetic flux density B input to the positive terminal with the threshold value 103 input to the negative terminal, and the magnetic flux density B exceeds the magnetic flux saturation density (B/m). determine whether or not there is The determination result is input to the notification unit 105 and notified to the outside of the magnetic saturation detection circuit 10a via the notification unit 105 .

Also in the modified example, the notification unit 105 can externally notify the information related to the suppression of high-frequency noise together with the notification of the determination result. That is, when magnetic saturation occurs, information (cable length, cable type (whether shielded or not), suitable filter inductor settings, etc.) prompting a review of stray capacitance on the power supply path can be notified. Furthermore, when magnetic saturation does not occur, the magnetic flux density B calculated by the calculator 106 can be notified together with the determination result, and the magnetic flux density B calculated by the calculator 106 and the magnetic flux saturation density that is the threshold value 103a can be notified. A difference amount (margin amount) can be obtained and notified to the outside. By notifying the magnetic flux density B calculated by the calculator 106, the current high-frequency noise suppression effect can be grasped, and the difference amount between the magnetic flux density B calculated by the calculator 102 and the magnetic flux saturation density ( By notifying the margin amount), the margin up to magnetic saturation can be recognized. Even in the modified example, it is possible to consider the number of connectable cables and the number of connectable motors, etc. in the host device (power converter, power conversion system, etc.) based on the margin amount, so usability related to magnetic saturation countermeasures is improved. can improve.

Also in the modified example, the magnetic saturation detection circuit 10a can determine magnetic saturation occurring in the common mode choke coil 21 based on the magnetic flux density B obtained from the core magnetic flux. Then, the magnetic saturation detection circuit 10a can notify the determination result to the outside in the same manner as in the first embodiment. For example, in the noise filter 20 that integrally accommodates the magnetic saturation detection circuit 10a, if the housing is provided with an LED or the like indicating that magnetic saturation has occurred, the notification unit 105 based on the determination result , the LED can be lit. When the noise filter 20 has a terminal for outputting a signal indicating the detection result, a host device (power converter, power conversion system, etc.) having the filter on the power supply path receives the detection result output from the output terminal. Based on the indicated signal, processing such as display lighting of an LED or the like and notification display on a display panel or the like may be performed. Also in the modified example, the magnetic saturation of the choke coil can be detected through the magnetic saturation detection circuit 10a during the operation of the facility involving power conversion.

[Example 2]
Next, a form of a motor drive system including the magnetic saturation detection circuit (10, 10a) according to the first embodiment will be described. In the following, the magnetic

saturation detection circuits

10 and 10a are also collectively referred to as "magnetic saturation detection circuit 10b". Also, the noise filter 20 is provided with a detector 29 , and a physical quantity related to magnetic saturation of the common mode choke coil 21 is measured through the detector 29 . Such a physical quantity is the current flowing through the common mode choke coil 21 and the core magnetic flux of the core 21a, as described in the first embodiment. The former is measured by a current transformer CT or the like, and the latter is measured by a magnetic flux measuring coil 23 or the like having the number of turns of n. These physical quantities can be measured using appropriate detectors according to the configuration of equipment or equipment that accompanies power conversion. Further, the noise filter 20 may include a magnetic saturation detection circuit (10, 10a), and may appropriately notify the devices and the like constituting the motor drive system.

<System configuration>
FIG. 5 is a block diagram showing a schematic configuration of a motor drive system 1 according to Embodiment 2 of the present invention. FIG. 5 illustrates a system form including a motor driver 3 that converts electric power supplied from a main power supply 2 for driving a motor into desired driving electric power and outputs the electric power to a motor 50 . The main power supply 2 is, for example, a commercial AC power supply, and supplies AC power to the motor driver 3 through the power line W1. The motor driver 3 converts the supplied AC power into DC power via the converter 30 and outputs the converted DC power to the inverter 40 via the DC bus 14 . The DC bus 14 is provided with a smoothing capacitor C for smoothing fluctuations in the DC power supplied to the inverter 40 through the DC bus 14 . The inverter 40 performs ON/OFF driving of the switching element based on the control command from the motor control unit 12, converts the DC power output from the converter 30 into desired AC power, and drives and controls the motor 50. Generate driving power. The generated drive power is output to the motor 50 through the power line W2. The motor 50 controls the workpiece, the robot arm, and the like to be controlled based on the driving power supplied from the motor driver 3 . Main power supply 2 and motor 50 are grounded to reference potential G1 and reference potential G2, respectively. Also, the Y capacitor C3 of the noise filter 20 is connected to the FG of the motor driver 3 .

The motor driver 3 includes a control section 4, a current detector 13, a noise filter 20, a converter 30, and an inverter 40. The control unit 4 includes a magnetic saturation detection circuit 10b, a motor control unit 12, and a notification unit 15. The control unit 4 is a unit including, for example, a processor (CPU, etc.), a memory, a gate driver, a communication interface circuit, and the like. The noise filter 20 is connected to the power line W1 via a pair of input terminals (TP1, TP2) and connected to the converter 30 via a pair of output terminals (TP3, TP4). The detection section 29 of the noise filter 20 is connected to the magnetic saturation detection circuit 10b of the control section 4. FIG. The converter 30 includes, for example, a bridge circuit composed of rectifying elements (diode elements), and outputs DC power rectified from AC power by the bridge circuit to the intermediate bus 14 . The inverter 40 has a power conversion circuit including switching elements (IGBT, thyristor, GTO, MOSFET, etc.) as components, and performs on/off driving (PWM control) of the switching elements according to a control command from the motor control unit 12. , converts the DC power input through the DC bus 14 into AC power to generate the desired driving power. The generated driving power is supplied to the motor 50 through the power line W2, and the current flowing through the power line is detected by a current detector (CT, clamp-type current sensor, etc.) 13. The current detector 13 is, for example, a CT (Current Transformer) provided at the output end of the inverter 40 of the motor driver 3 . A current value detected by the current detector 13 is input to the motor control section 12 of the control section 4 . The motor control unit 12 uses the current value detected by the current detector 13 and the rotation speed of the motor 50 as feedback information, and determines the rotation speed of the motor based on a predetermined torque command and a program stored in a memory or the like. It generates control commands for controlling torque, rotational position, and the like.

As described in the first embodiment, in the detection unit 29 of the noise filter 20, the current flowing through the common mode choke coil 21 from the pair of input terminals (TP1, TP2) to the pair of output terminals (TP3, TP4) is current. A current value measured by a transformer CT or the like is input to the magnetic saturation detection circuit 10b. Further, the core magnetic flux (Φ) of the core 21a of the common mode choke coil 21 is measured by the magnetic flux measuring coil 23 and the like, and the measured core magnetic flux (Φ) is input to the magnetic saturation detection circuit 10b.

In the magnetic saturation detection circuit 10b, from the current value measured by the detection unit 29, the magnetic field strength H (A/m) indicating the strength of the magnetic field generated in the common mode choke coil 21 and the strength of the magnetic field causing magnetic saturation Whether or not magnetic saturation has occurred is determined based on a comparison with a threshold indicating the degree of saturation. Alternatively, the magnetic flux density B (Wb/m ² ) indicating the strength of the magnetic field is obtained from the core magnetic flux (Φ) of the core 21a measured by the detection unit 29 and the cross-sectional area S (m ² ) of the core 21a, Based on the comparison between the magnetic flux density B and a threshold value indicating the magnetic flux saturation density, it is determined whether or not magnetic saturation has occurred. The result of determination by the magnetic saturation detection circuit 10b is output to the notification unit 15. FIG.

The notification unit 15 notifies the result of determination by the magnetic saturation detection circuit 10b through a display device, an LED, or the like provided on the housing of the motor driver 3 or the like. When the determination result indicates that magnetic saturation has occurred, for example, a message indicating that magnetic saturation has occurred may be displayed on a display panel provided in the motor driver 3, and an LED or the like indicating the magnetic saturation state may be displayed. may be lit. The operator can grasp the magnetic saturation occurring in the noise filter 20 from the displayed message and the lighting of the LED. In addition, the notification unit 15 may notify the length of the power line W2 connecting the motor driver 3 and the motor 50, wiring routing, a message prompting change of the cable type (with or without a shield), an alarm sound, or the like.

The magnetic saturation detection circuit 10b calculates the difference (margin amount) between the magnetic field strength H indicating the strength of the magnetic field generated in the common mode choke coil 21 and the threshold, and outputs the calculated difference information (margin information). You may output to the alerting|reporting part 15. FIG. Similarly, the magnetic saturation detection circuit 10 b may calculate the difference between the magnetic flux density B and the magnetic flux saturation density, which is the threshold value, and output the difference information to the notification unit 15 . The notification unit 15 may display the margin amount output from the magnetic saturation detection circuit 10b on a display panel or the like so that the number of motors 50 driven by the motor driver 3, the number of connectable cables, and the like can be grasped. . Usability for monitoring magnetic saturation can be improved.

<Control unit configuration>
FIG. 6 is a diagram illustrating an example of the hardware configuration of the controller 4 according to the second embodiment. As shown in FIG. 6, the control unit 4 is configured as a computer including a processor 111, a main storage device 112, an auxiliary storage device 113, a communication IF 114, and an input/output IF 115, which are interconnected by a connection bus . The main storage device 112 and the auxiliary storage device 113 are recording media readable by the control unit 4 . A plurality of the above components may be provided, or some of the components may be omitted.

The processor 111 is a central processing unit that controls the control unit 4 as a whole. The processor 111 is, for example, a CPU (Central Processing Unit), an MPU (Micro-Processing Unit), a DSP (Digital Signal Processor), or the like. The processor 111, for example, develops a program stored in the auxiliary storage device 113 in a work area of the main storage device 112 so that it can be executed, and controls peripheral devices through execution of the program to perform a function that meets a predetermined purpose. I will provide a. However, some or all of the functions provided by the processor 111 may be provided by an ASIC (Application Specific Integrated Circuit), a GPU (Graphics Processing Unit), an SoC (System on a Chip), or the like. Similarly, some or all of the functions may be implemented by FPGAs (Field-Programmable Gate Arrays), dedicated LSIs (large scale integration) such as numerical processors, or other hardware circuits.

The main storage device 112 and the auxiliary storage device 113 constitute the memory of the control unit 4 . The main storage device 112 stores programs executed by the processor 111, data processed by the processor, and the like. The main storage device 112 includes flash memory, RAM (Random Access Memory), and ROM (Read Only Memory). The auxiliary storage device 113 is a storage medium that stores programs executed by the processor 111 or the like, operation setting information, and the like. The auxiliary storage device 113 includes, for example, a HDD (Hard-disk Drive), SSD (Solid State Drive), EPROM (Erasable Programmable ROM), flash memory, USB memory, SD (Secure Digital) memory card, and the like. Communication IF 114 is a communication interface with a communication network. The communication IF 114 can adopt an appropriate configuration according to the connection method with the communication network to be connected. The input/output IF 115 is an interface for inputting/outputting data between an input device and an output device provided in the motor driver 3 . Through the input/output IF 115, predetermined information is output to a display device such as an LCD, an LED or the like provided on the housing of the motor driver 3 or the like. Further, through the input/output IF 115, an operation instruction is received via an operation button or an operation panel provided on the housing or the like, and processing based on the operation instruction is performed.

<Process flow>
FIG. 7 is a flowchart showing an example of magnetic saturation detection processing executed by the motor driver 3 according to the second embodiment. In this flow, the physical quantity related to magnetic saturation detected by the detection unit 29 is measured, the magnetic field intensity H or the magnetic flux density B obtained based on the physical quantity is compared with a threshold value, and the common mode choke coil The magnetic saturation that occurred at 21 is determined. The determination result is notified to the operator or the like via a notification device (LED, display panel, speaker, etc.) provided on the housing. The processing of this flow is periodically executed at predetermined periodic intervals.

After the process is started, the physical quantity related to the magnetic saturation of the common mode choke coil 21 detected through the detector 29 of the noise filter 20 is acquired (step S101), and the process proceeds to step S102. The current value flowing through the common mode choke coil 21 detected by the current transformer CT or the core magnetic flux of the core 21a detected by the magnetic flux measuring coil 23 is acquired.

In step S102, the magnetic field strength H or the magnetic flux density B indicating the strength of the magnetic field of the common mode choke coil 21 is obtained from the acquired physical quantity. The magnetic field intensity H is obtained using the equation (1) using the current value detected by the current transformer CT, the number of turns N defined by the specifications of the common mode choke coil 21, etc., and the magnetic path length l as parameters. . Further, the magnetic flux density B is obtained using the equation (2) using the core magnetic flux (Φ) detected by the magnetic flux measuring coil 23 and the cross-sectional area S of the core 21a as parameters. After the magnetic field intensity H or the magnetic flux density B obtained from the detected physical quantity is temporarily stored in a predetermined area of the main storage unit 112 constituting the memory, the process proceeds to step S103.

In step S103, the magnetic field strength H or magnetic flux density B is compared with a threshold, and the process proceeds to step S104. The magnetic field strength H is compared with a threshold representing the strength of the magnetic field that causes magnetic saturation, and the magnetic flux density B is compared with a threshold representing the saturation magnetic flux density. Such a threshold value is stored in memory or the like in advance. In step S104, determination of magnetic saturation is performed based on the result of the comparison. In step S104, if the magnetic field intensity H or the magnetic flux density B exceeds the threshold value, or is equal to or greater than the threshold value, it is determined that magnetic saturation has occurred (step S104, "Yes"), and the process proceeds to step S105. Otherwise (step S104, "No"), the process proceeds to step S106.

It should be noted that in step S104, magnetic saturation may be determined on the condition that the threshold value is exceeded or the state of the threshold value or more continues for a certain period of time. For example, a flag is set when the threshold value is exceeded or the state is equal to or higher than the threshold value, a timer is provided to count the period after the flag is set, and it is determined that magnetic saturation has occurred when the timer value is equal to or longer than a certain period. Just do it. The flag may be reset when the state becomes equal to or less than the threshold value or less than the threshold value within a certain period of time. As a result, for example, malfunction due to sudden surge current generation can be suppressed.

In step S105, the magnetic saturation occurring in the common mode choke coil 21 is reported. For example, an LED or the like provided on the housing of the motor driver 3 or the like to indicate the magnetic saturation state is lit. Further, a message indicating that magnetic saturation has occurred may be notified on a display panel or the like provided on the housing or the like, or the occurrence of magnetic saturation may be notified through an electronic sound, a speaker, or the like. Magnetic saturation occurring in the noise filter 20 is grasped based on a message displayed on a display panel or the like, LED lighting, electronic sound or the like. Note that the control unit 4 that executes step S105 displays on the display panel a message prompting a change in the length of the power line W2 connecting the motor driver 3 and the motor 50, the wiring routing, and the cable type (with or without a shield). You may It is possible to encourage the review of the stray capacitance between the motor driver 3 and the motor 50 to ground, which causes magnetic saturation in the noise filter 20, or the installation of a noise filter having an appropriate inductor according to the operating environment. . After the process of step S105, the process proceeds to step S107.

In step S106, the difference (margin amount) between the magnetic field intensity H indicating the strength of the magnetic field obtained from the physical quantity detected by the detection unit 29 and the threshold, or the difference between the magnetic flux density B and the magnetic flux saturation density that is the threshold is calculated, and the difference (margin amount) is displayed on a display panel or the like provided on the housing of the motor driver 3 or the like. The number of motors 50 that can be driven by the motor driver 3, the number of connectable cables, and the like can be grasped based on the margin amount displayed on the display panel or the like. Note that when the stray capacitance to ground for each motor and the stray capacitance to ground for each cable are held as known information, the control unit 4 that executes step S105 performs the above-described driving based on the stray capacitance to ground. The number of motors that can be connected, the number of cables that can be connected, and the like may be displayed on a display panel or the like. Usability regarding magnetic saturation countermeasures can be improved. After the process of step S106, the process proceeds to step S107.

In step S107, the magnetic field intensity H or the magnetic flux density B used to determine magnetic saturation is recorded in a memory or the like. The magnetic field strength H or the magnetic flux density B is stored in a predetermined area of the main storage unit 103 in association with, for example, time information when the process of this flow is executed or attribute information. Examples of attribute information include the identification number of the noise filter 20, the identification number of the motor 50, the identification number of the power line W2, and the like. At the time of analysis of magnetic saturation, it can be used as information for grasping the setting environment, operating environment, etc. of the motor driver 3 when magnetic saturation is detected. After the process of step S107, this routine is terminated.

As described above, in the motor driver 3 according to the second embodiment, magnetic saturation of the noise filter 20 due to high-frequency noise during operation can be detected based on the physical quantity related to magnetic saturation detected by the detection unit 29. . In the second embodiment, the current value flowing through the common mode choke coil 21 is detected by the current transformer CT, and the magnetic field intensity H is obtained. Further, the core magnetic flux formed in the core 21a of the common mode choke coil 21 is detected by the magnetic flux measuring coil 23, and the magnetic flux density B is obtained. Then, in Example 2, the magnetic field strength H is compared with a threshold representing the strength of the magnetic field that causes magnetic saturation, and the magnetic flux density B is compared with a threshold representing the saturation magnetic flux density, The presence or absence of magnetic saturation occurring in the common mode choke coil 21 can be determined.

In the motor driver 3 according to the second embodiment, when magnetic saturation occurs, for example, an LED or the like provided on the housing or the like that indicates the magnetic saturation state is turned on, or a display panel or the like provided on the housing or the like is turned on. It is possible to display a message to the effect that an error has occurred, and to notify the user by means of an electronic sound or a voice using a speaker or the like. According to the second embodiment, magnetic saturation occurring in the common mode choke coil can be detected without stopping the operation of the motor driver 3 .

It should be noted that the motor driver 3 according to the second embodiment can change the length of the power line W2 connecting between the motor driver 3 and the motor 50, the wiring routing, the cable type (with or without a shield), and the appropriate inductor according to the operating environment. may be displayed on the display panel or the like to prompt selection of a noise filter having It is possible to appropriately prompt the review of the equipment environment, the operating environment, etc. at the facility where the motor driver 3 is provided.

In addition, when the magnetic saturation does not occur, the motor driver 3 according to the second embodiment has the difference between the current magnetic field strength H and the strength of the magnetic field at which magnetic saturation occurs, or the difference between the current magnetic flux density B and the magnetic flux saturation density. The difference can be calculated as a margin amount and displayed on a display panel or the like. The operator can grasp the number of motors 50 that can be driven by the motor driver 3, the number of cables that can be connected, etc. based on the margin amount displayed on the display panel, etc., improving the usability related to magnetic saturation countermeasures. can.

(others)
The above-described embodiment is merely an example, and the disclosure of the present embodiment can be modified as appropriate without departing from the gist thereof. The processes and means described in the present disclosure can be freely combined and implemented as long as there is no technical contradiction.

Further, the processing explained as being performed by one device may be shared and performed by a plurality of devices. Alternatively, processes described as being performed by different devices may be performed by one device. In a computer system, it is possible to flexibly change what kind of hardware configuration realizes each function.

《Computer-readable recording medium》
A computer-readable recording medium can record a program that causes an information processing device or other machine or device (hereinafter referred to as a computer or the like) to implement any of the functions described above. By causing a computer or the like to read and execute the program of this recording medium, the function can be provided.

Here, a computer-readable recording medium is a recording medium that stores information such as data and programs by electrical, magnetic, optical, mechanical, or chemical action and can be read by a computer, etc. Say. Examples of such recording media that can be removed from a computer or the like include memories such as flexible disks, magneto-optical disks, CD-ROMs, CD-R/Ws, DVDs, Blu-ray disks, DATs, 8 mm tapes, and flash memories. There are cards, etc. In addition, there are a hard disk, a ROM, and the like as recording media fixed to a computer or the like.

In order to allow comparison between the constituent elements of the present invention and the configurations of the embodiments, the constituent elements of the present invention will be described below with reference numerals in the drawings.
<Invention 1>
a detection unit (CT, 23) for detecting a physical quantity related to magnetic saturation of a common mode choke coil (21) provided in series in a path from a power supply;
It is determined that magnetic saturation has occurred in the common mode choke coil (21) on condition that the strength of the magnetic field of the common mode choke coil (21) estimated from the detected physical quantity satisfies a predetermined criterion. a determination unit (11);
a notification unit (15) that notifies the result of the determination to the outside;
A magnetic saturation detection circuit (10, 10a, 10b) comprising:
<Invention 2>
The magnetic saturation detection circuit (10, 10a, 10b) according to invention 1, wherein the notification unit (15) notifies information related to suppression of high-frequency noise in a circuit including the power supply.

1 motor drive system 2 main power supply 3 motor driver (driving device)
4

control units

10, 10a, 10b magnetic saturation detection circuit 11 determination unit 15 notification unit 20 noise filter 21 common mode choke coil 21a core, 21b, 21c winding 23 magnetic flux measurement coil 29 detection unit 101 low-

pass filters

102, 106

calculation unit

103, 103a Threshold 104 Comparator 105 Notification Unit 111 Processor 112 Main Storage Device 113 Auxiliary Storage Device 114 Communication IF
115 input/output IF
116 Connection bus CT Current transformer

Claims

a detection unit that detects a physical quantity related to magnetic saturation of a common mode choke coil provided in series in a path from a power supply;
a determination unit that determines that magnetic saturation has occurred in the common mode choke coil on condition that the strength of the magnetic field of the common mode choke coil estimated from the detected physical quantity satisfies a predetermined criterion;
a notification unit that notifies the result of the determination to the outside;
A magnetic saturation detection circuit, comprising:
2. The magnetic saturation detection circuit according to claim 1, wherein said notification unit notifies information related to suppression of high frequency noise in a circuit including said power supply.
The detection unit detects a current flowing through the common mode choke coil,
The determination unit estimates a magnetic field intensity of the common mode choke coil from the detected current value, and, on the condition that the estimated magnetic field intensity exceeds a first threshold, causes the common mode choke coil to undergo magnetic saturation. 3. The magnetic saturation detection circuit of claim 1, wherein the magnetic saturation detection circuit determines that a has occurred.
The detection unit detects magnetic flux of a common mode choke coil,
The determination unit estimates a magnetic flux density of the common mode choke coil from the detected magnetic flux, and the magnetic saturation of the common mode choke coil is detected on condition that the estimated magnetic flux density exceeds a second threshold. 3. A magnetic saturation detection circuit as claimed in claim 1 or 2, for determining that a magnetic saturation has occurred.
A noise filter comprising a common mode choke coil,
5. A noise filter comprising the magnetic saturation detection circuit according to claim 1, wherein said notification unit notifies information related to the degree of noise removal by said noise filter.
A motor driver comprising the magnetic saturation detection circuit according to claims 1 to 4 or the noise filter according to claim 5,
A motor driver, wherein a notification prompting a predetermined process is performed based on the determination result notified from the magnetic saturation detection circuit or the noise filter.
The predetermined process includes exchanging a power line connecting the motor driver and a motor to which driving power generated by the motor driver is supplied, or replacing a ground between the power line and the motor. 7. The motor driver according to claim 6, prompting a review of stray capacitance.
When the common mode choke coil is not magnetically saturated, the magnetic saturation detection circuit calculates a margin amount until the magnetic saturation occurs, and notifies the calculated margin amount. A motor driver according to claim 6 or 7.
Detecting a physical quantity related to magnetic saturation of a common mode choke coil provided in series in the path from the power supply,
Determining that magnetic saturation has occurred in the common mode choke coil on condition that the strength of the magnetic field of the common mode choke coil estimated from the detected physical quantity satisfies a predetermined criterion;
Notifying the result of the determination to the outside;
A magnetic saturation detection method, comprising: