JP2018152930A - Motor drive device determining generation of leakage current - Google Patents

Abstract

PROBLEM TO BE SOLVED: To realize a motor drive device capable of detecting an occurrence state of a leakage current easily and accurately.SOLUTION: A motor drive device 1 includes a power conversion unit 11 for converting AC power supplied from AC power supply 3 into drive power for driving a motor and outputting the drive power, a noise absorption circuit 12 having a resistor 31 and a capacitor 32, and absorbing noise generated between the AC power supply 3 and the power conversion unit 11, a temperature measurement part 13 for measuring a temperature of the resistor 31, and a leakage current determination part 14 for determining presence or absence of a leakage current resultant from motor drive, based on the temperature measured by the temperature measurement part 13.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a motor drive device that determines the occurrence of leakage current.

  In machine tools, forging machines, injection molding machines, industrial machines, or motor drive devices that drive motors in various robots, AC power supplied from an AC power source is once converted into DC power by a forward converter, and then further The AC power is converted to AC power by an inverse converter, and this AC power is used as driving power for a motor provided for each drive shaft.

  In such a motor drive device, when PWM switching control is performed on the inverse converter, a leakage current is generated due to stray capacitance existing in the motor and the motor power cable. Since the leakage current causes malfunction or damage of the motor drive device or its peripheral devices, countermeasures are important.

  For example, the relationship between the inverter element temperature and the leakage current is examined by experiment and stored as a leakage current setting map, and when the inverter element temperature is given, a technique for estimating the magnitude of the corresponding leakage current from the map is derived. Is known (for example, see Patent Document 1).

  For example, a control device for controlling an air conditioner outdoor unit, a converter that converts the output of an alternating current power source into direct current, a current detection means that detects a current flowing through an electrolytic capacitor connected as a smoothing circuit in the converter, And a microcomputer that reads the leakage current of the electrolytic capacitor from the current detected by the current detection means, and the microcomputer uses a leakage current data to predict a failure or life of the electrolytic capacitor (for example, , See Patent Document 2).

JP 2011-172373 A JP 2007-318872 A

  In order to take measures against leakage current, it is necessary to measure the leakage current. Since the leakage current is generated by performing high-speed PWM switching control on the inverse converter that supplies driving power to the motor in the presence of the stray capacitance, the leakage current has a very high frequency. Therefore, it is difficult to directly measure the leakage current itself. Therefore, in the field of motor drive devices, a technique that can easily and accurately detect the occurrence of leakage current is desired.

  According to one aspect of the present disclosure, a motor driving device includes a power conversion unit that converts AC power supplied from an AC power source into driving power for motor driving, a resistor, and a capacitor. A noise absorbing circuit that absorbs noise generated between the power converter and the power converter, a temperature measuring unit that measures the temperature of the resistor, and a leakage current caused by driving the motor based on the temperature measured by the temperature measuring unit. And a leakage current determination unit that determines whether or not it has occurred.

  ADVANTAGE OF THE INVENTION According to this invention, the motor drive device which can detect the generation | occurrence | production state of leakage current easily and accurately is realizable.

It is a figure which shows the motor drive device by one Embodiment. It is a block diagram which shows the 1st form of the leakage current determination part in the motor drive device by one Embodiment. It is a block diagram which shows the 2nd form of the leakage current determination part in the motor drive device by one Embodiment. It is a block diagram which shows the case where an alerting | reporting part is connected to the leakage current determination part by the 1st form shown in FIG. It is a block diagram which shows the case where an alerting | reporting part is connected to the leakage current determination part by the 2nd form shown in FIG. It is FIG. (1) which shows the other form of the noise absorption circuit in the motor drive device by one Embodiment. It is FIG. (2) which shows the other form of the noise absorption circuit in the motor drive device by one Embodiment. It is FIG. (3) which shows the other form of the noise absorption circuit in the motor drive device by one Embodiment. It is a figure (the 1) which shows the other form of the power converter part in the motor drive device by one Embodiment. It is FIG. (2) which shows the other form of the power converter part in the motor drive device by one Embodiment. It is FIG. (3) which shows the other form of the power converter part in the motor drive device by one Embodiment.

  A motor drive device that determines the occurrence of leakage current will be described below with reference to the drawings. In the drawings, similar members are denoted by the same reference numerals. Moreover, what attached | subjected the same referential mark in a different drawing shall mean that it is a component which has the same function. In order to facilitate understanding, the scales of these drawings are appropriately changed. In general, the leakage current is generated more or less when the motor is driven. However, in the present disclosure, “a leakage current that causes malfunction or damage has occurred” is simply referred to as “a leakage current has occurred. ”Or“ There is leakage current ”and“ No leakage current causing malfunction or damage ”is simply expressed as“ No leakage current ”or“ No leakage current ”. There are things to do.

  FIG. 1 is a diagram illustrating a motor drive device according to an embodiment. Here, as an example, the case where the motor driving device 1 controls the three-phase AC motor 2 will be described. However, the present invention is not particularly limited with respect to the type of the motor 2, and for example, an induction motor is synchronized. It may be a motor. In the embodiment shown in FIG. 1, the AC power supply 3 is a three-phase motor, and the motor 2 is a three-phase AC motor. Application examples when the AC power supply 3 is a single phase and when the motor 2 is a single-phase AC motor or a DC motor will be described later.

  As shown in FIG. 1, the motor drive device 1 according to an embodiment includes a power conversion unit 11, a noise absorption circuit 12, a temperature measurement unit 13, and a leakage current determination unit 14.

  The power converter 11 converts the AC power supplied from the AC power supply 3 into drive power for driving the motor 2 and outputs the drive power. Since the motor 2 is a three-phase AC motor, the power conversion unit 11 includes a forward converter 101, an inverse converter 102, and a DC link capacitor 103. Here, each phase of the three-phase AC power supply 3 is R phase, S phase, and T phase, and N is a grounding point.

  The forward converter 101 converts AC power supplied from the three-phase AC power supply 3 into DC power and outputs the DC power. Examples of the forward converter 101 include a diode rectifier circuit, a 120-degree conduction rectifier circuit, or a PWM switching control type rectifier circuit having a switching element therein. When the forward converter 101 is a diode rectifier circuit, the AC current supplied from the AC power supply 3 side is rectified and a DC current is output to the DC link on the DC side. When the forward converter 101 is a 120-degree energization type rectifier circuit or a PWM switching control type rectifier circuit, the forward converter 101 converts the AC power supplied from the AC power supply 3 side into DC power to the DC side. When the motor is decelerated, it can be realized as a power converter that can convert the direct current power supplied from the DC link into alternating current power and output the alternating current power to the alternating current power supply 3 side and can be converted into AC and AC bidirectional directions. When the forward converter 101 is a PWM switching control type rectifier circuit, the forward converter 101 includes a switching element and a diode bridge circuit connected in reverse parallel thereto. In this case, examples of the switching element include an IGBT, a thyristor, a GTO (Gate Turn-OFF thyristor), a transistor, and the like, but the type of the switching element itself does not limit the present invention. It may be a switching element.

  A DC link capacitor (also referred to as a smoothing capacitor) 103 is provided on the DC link connecting the DC output side of the forward converter 101 and the DC input side of the inverse converter 102. The DC link capacitor 103 has a function of accumulating DC power in the DC link and a function of suppressing the pulsation of the DC output of the forward converter 101.

  The inverse converter 102 is connected to the DC link, and each switching element is on / off controlled based on a switching command received from a host controller (not shown), whereby the DC link DC power and the motor 2 drive power or regenerative power are regenerated. Power is converted between AC power, which is power. The inverse converter 102 includes a switching circuit and a bridge circuit of a diode connected in antiparallel with the switching element. For example, each switching element is on / off controlled based on a PWM switching control system. In this embodiment, since the motor 2 connected to the motor driving device 1 is a three-phase AC motor, the inverse converter 102 is configured as a three-phase bridge circuit. Examples of the switching element include an IGBT, a thyristor, a GTO, and a transistor. However, the type of the switching element itself does not limit the present invention, and other switching elements may be used. The reverse converter 102 performs a switching operation of the internal switching element based on the switching command received from the host controller, and the DC power supplied from the forward converter 101 via the DC link is used as a desired power for driving the motor 2. Conversion to AC power of voltage and desired frequency (inverse conversion operation). Accordingly, the motor 2 operates based on the supplied voltage variable and frequency variable AC power. In addition, regenerative power is generated when the motor 2 decelerates, but the internal switching element is switched based on the switching command received from the host controller, and the AC regenerative power generated by the motor 2 is converted to DC power to generate a DC link. Return to (forward conversion operation).

  The noise absorption circuit 12 includes a resistor 31 and a capacitor 32 and absorbs noise generated on the AC input side of the power conversion unit 11 (that is, between the AC power supply 3 and the power conversion unit 11). Since the motor 2 is an inductive load, when the switching element in the inverter 102 is turned on and off, instantaneous high voltage noise called “surge” having a large energy is generated by the back electromotive force. Since each element of the power conversion unit 11 including the inverse converter 102 may be destroyed or malfunction due to the high voltage noise, the noise absorbing circuit 12 is connected to the AC input side of the power conversion unit 11 to prevent this. Installed. In the noise absorbing circuit 12, high voltage noise is received by the capacitor 32 and is removed by the resistor 31. There are various configurations of the noise absorbing circuit 12. In the example shown in FIG. 1, the noise absorption circuit 12 is configured by a delta connection of a resistor 31 and a capacitor 32 connected in series, and an R phase and an S phase between the AC power supply 3 and the power conversion unit 11. And T phase.

  The temperature measuring unit 13 measures the temperature of the resistor 31 in the noise absorbing circuit 12. The sensor portion of the temperature measurement unit 13 is preferably installed as close as possible to the resistor 31. More specifically, the sensor portion of the temperature measurement unit 13 is directly attached to the resistor 31 or is installed via some member with respect to the resistor 31, for example, and the resistor 31 is connected to the noise absorbing circuit 12. If it is housed in a case, it is installed on that case.

  The leakage current determination unit 14 determines whether or not leakage current is generated due to driving of the motor 2 based on the temperature of the resistor 31 measured by the temperature measurement unit 13.

  Next, the leakage current determination process performed by the leakage current determination unit 14 will be described with reference to FIG.

  A stray capacitance exists in the motor 2 and the motor power cable. In FIG. 1, stray capacitance is indicated by reference numeral 200. When high-speed PWM switching control is performed on the switching elements in the inverse converter 102 to supply AC power for driving the motor 2, the AC power source 3, the forward converter 101, the inverse converter 102, and the stray capacitance A leakage current flows through 200. In FIG. 1, an example of a path through which a leakage current resulting from driving of the motor 2 flows is indicated by a thick dashed arrow. The current path shown in FIG. 1 is merely an example. Actually, a current in which a leakage current caused by driving of the motor 2 flows due to a combination with the on / off state of each switching element in the upper arm and the lower arm of the inverse converter 102. The route changes every moment.

  When a leakage current resulting from driving of the motor 2 occurs, a part of the leakage current also flows to the noise absorption circuit 12. In FIG. 1, for example, when a leakage current caused by driving of the motor 2 flows through a current path indicated by a thick dashed arrow, an example of a path through which the leakage current flows in the noise absorbing circuit 12 is indicated by a thick dashed line arrow. Show. Note that if the current path through which the leakage current resulting from driving of the motor 2 changes, the current path of the leakage current in the noise absorbing circuit 12 also changes accordingly.

  The high-frequency leakage current flowing in the noise absorbing circuit 12 is consumed by the resistor 31 in the noise absorbing circuit 12, and the resistor 31 generates heat accordingly. The temperature rise value of the resistor 31 is substantially proportional to the heat loss (power consumption) in the resistor 31. When the resistance value of the resistor 31 in the noise absorbing circuit 12 is R, the magnitude of the leakage current flowing through the resistor 31 is i, and the temperature increase coefficient for heat loss in the resistor 31 is k, the temperature increase value ΔT of the resistor 31 is It is expressed as Equation 1.

  When formula 1 is transformed, formula 2 is obtained.

  From Equation 2, it can be seen that if the temperature rise value ΔT in the resistor 31 is known, the magnitude i of the leakage current flowing through the resistor 31 can be estimated. A part of the leakage current also flows through the resistor 31 along with the generation of the leakage current resulting from the driving of the motor 2. Therefore, in the motor driving device 1 according to the embodiment, the temperature measurement unit 13 measures the temperature of the resistor 31. Then, the leakage current determination unit 14 determines the state of occurrence of leakage current caused by driving of the motor 2 based on the temperature of the resistor 31 (the increased value thereof). Generally, the leakage current is generated more or less when the motor 2 is driven. Therefore, the leakage current determination unit 14 in the motor drive device 1 according to the embodiment determines, for example, that a leakage current that causes malfunction or damage of the motor drive device 1 or its peripheral devices has occurred. If there is a leakage current that does not cause malfunction or damage, it is determined that “a leakage current that causes malfunction or damage has not occurred”.

  As shown in FIG. 1, when there are a plurality of resistors 31 in the noise absorbing circuit 12, it is preferable to measure the temperatures of all the resistors 31 by the temperature measuring unit 13. The reason is as follows. For example, an electrical device such as a device for generating a DC control power source is connected to two phases of the three phases of the cable connecting the AC power source 3 and the motor driving device 1, thereby the motor driving device. Some three-phase imbalance may occur on the AC input side of 1. Due to this three-phase imbalance, the temperature increasing tendency of each resistor 31 in the noise absorbing circuit 12 is different. If the temperature measurement unit 13 measures the temperature of all the resistors 31 and performs the determination process by the leakage current determination unit 14 based on the largest temperature rise value as a result of the measurement, the generation of the leakage current can be determined more accurately. Can do.

  Subsequently, a more specific configuration of the leakage current determination unit 14 will be described with reference to FIGS. 2 and 3.

  FIG. 2 is a block diagram illustrating a first form of a leakage current determination unit in the motor drive device according to the embodiment. The leakage current determination unit 14 according to the first form includes a current estimation unit 21 that estimates the magnitude of the leakage current flowing through the noise absorption circuit 12 based on the temperature of the resistor 31 measured by the temperature measurement unit 13, and a current estimation unit. A current comparing unit 22 that compares the magnitude of the leakage current flowing through the noise absorbing circuit 12 estimated by 21 with a predetermined current threshold value. When the magnitude of the leakage current flowing through the noise absorption circuit 12 estimated by the current estimation unit 21 exceeds the current threshold value, the leakage current determination unit 14 according to the first form has a leakage current due to driving of the motor 2. It is determined that it has occurred. In the process of estimating the magnitude of the leakage current flowing through the noise absorbing circuit 12 by the current estimating unit 21, as shown in Equation 2, the temperature rise ΔT of the resistor 31 measured by the temperature measuring unit 13, the noise absorption Each parameter of the resistance value R of the resistor 31 in the circuit 12 and the temperature increase coefficient k for the heat loss in the resistor 31 is necessary. Among these, the resistance value R of the resistor 31 in the noise absorbing circuit 12 is generally defined as specification data of the noise absorbing circuit 12, and for example, in the specification table or instruction manual of the noise absorbing circuit 12 Since it is described, this may be used. Alternatively, the resistance value of the resistor 31 in the noise absorbing circuit 12 may be directly measured and used. The temperature rise coefficient k for the heat loss in the resistor 31 is obtained by an experiment in which a current is passed through the resistor 31 in the noise absorption circuit 12 by an experiment, and the temperature generated at that time is measured by the loss measurement unit 13. The temperature increase coefficient k may be calculated from the relationship (usually linear) between the obtained current and the temperature increase value and used. The current threshold value used for the leakage current determination process by the current comparison unit 22 may be determined as appropriate by operating the motor drive device 1 by experiment or actual operation, for example. More specifically, the magnitude of the leakage current flowing through the noise absorbing circuit 12 when the motor driving apparatus 1 is operated and the malfunction or damage of the motor driving apparatus 1 or its peripheral devices considered to be caused by the leakage current occurs. What is necessary is just to set the value smaller than the value calculated by the current estimation part 21 and the value calculated by the current estimation part 21 as a current threshold value. That is, this current threshold value is set to a value that does not generate a leakage current that causes malfunction or damage of the motor drive device 1 or its peripheral devices.

  FIG. 3 is a block diagram illustrating a second form of the leakage current determination unit in the motor drive device according to the embodiment. The leakage current determination unit 14 according to the second form includes a temperature comparison unit 23 that compares the temperature of the resistor 31 measured by the temperature measurement unit 13 with a predetermined temperature threshold value. The temperature comparison unit 23 in the leakage current determination unit 14 according to the second embodiment generates a leakage current due to the driving of the motor 2 when the temperature of the resistor 31 measured by the temperature measurement unit 13 exceeds the temperature threshold. It is determined that As can be seen from Equation 2, the magnitude i of the leakage current flowing through the resistor 31 is represented by a function having the temperature rise value ΔT in the resistor 31 as an independent variable. That is, as long as the temperature rise value ΔT in the resistor 31 is known, the relative magnitude (that is, whether it is large or small) of the leakage current flowing through the resistor 31 can be known. What is necessary is just to determine suitably the temperature threshold value used for the determination process of the leakage current by the temperature comparison part 23, for example by operating the motor drive device 1 by experiment or actual operation. More specifically, the temperature of the resistor 31 is measured by the temperature measuring unit 13 when the motor driving device 1 is operated and when the malfunction or damage of the motor driving device 1 or its peripheral devices considered to be caused by leakage current occurs. A temperature lower than the temperature measured by the temperature measuring unit 13 may be set as the temperature threshold value. That is, this temperature threshold value is set to a value that does not generate a leakage current that causes malfunction or damage of the motor drive device 1 or its peripheral devices. As described above, according to the leakage current determination unit 14 according to the second embodiment, the resistance value R of the resistor 31 in the noise absorbing circuit 12 and the temperature increase coefficient k with respect to the heat loss at the resistor 31 are preliminarily determined for the leakage current determination process. Therefore, the presence or absence of leakage current can be determined more easily than in the case of the leakage current determination unit 14 according to the first embodiment.

  Based on the determination result by the leakage current determination unit 14 described above, the user can be notified of the occurrence of leakage current due to the driving of the motor 2. A notification unit that notifies whether or not a leakage current has occurred will be described with reference to FIGS. 4 and 5.

  FIG. 4 is a block diagram illustrating a case where a notification unit is connected to the leakage current determination unit according to the first embodiment illustrated in FIG. FIG. 5 is a block diagram showing a case where a notification unit is connected to the leakage current determination unit according to the second embodiment shown in FIG. When the leakage current determination unit 14 determines that the leakage current due to the driving of the motor 2 has occurred, the notification unit 24 notifies the user that the leakage current has occurred. Examples of the notification unit 24 include a display such as a personal computer, a portable terminal, and a touch panel, and a display attached to a numerical control device (not shown) provided in the motor drive device 1. "A leakage current has occurred" or "A leakage current (not causing malfunction or damage) has not occurred" is displayed on the display with characters or designs. Further, for example, the notification unit 24 may be realized by an acoustic device that emits a sound such as a speaker, a buzzer, or a chime. For example, when the “leakage current (which causes malfunction or damage) occurs” A sound is generated in the device, and in the case of “no leakage current (which causes malfunction or damage)”, a special sound is not generated in the audio device. Alternatively, the notification unit 24 may take a form that is printed out and displayed on a paper surface using a printer. For example, “notifying that a leakage current (which causes malfunction or damage) has occurred” is displayed together with the time of occurrence. You may let them. Alternatively, the notification unit 24 may be realized by appropriately combining these. In addition, the data regarding the determination result output by the leakage current determination unit 14 may be stored in a storage device, and the data may be used for further use.

  From the determination result of the leakage current determination unit 14, the user of the motor drive device 1 can easily and accurately know the occurrence state of the leakage current. For example, a user who knows that “leakage current (which causes malfunction or damage) has occurred” via the notification unit 24, for example, a cable connected to the motor 2, an AC power supply 3, and the motor drive device 1 It is possible to make a design change such as thickening the cable connecting the, and replacing the noise absorbing circuit 12 with one having a different resistance value of the resistor 31 or a capacitor 32 having a different capacitance. Note that the current threshold value or temperature threshold value used in the determination process of the leakage current determination unit 14 is set to a value that does not generate a leakage current that may cause malfunction or damage of the motor drive device 1 or its peripheral devices. Therefore, even if the user makes a design change as described above at the time when the user knows that “leakage current (which causes malfunction or damage) has occurred”, the motor drive device 1 or its peripheral device malfunctions. Or damage.

  Note that the above-described current estimation unit 21, current comparison unit 22, and temperature comparison unit 23 may be constructed, for example, in a software program format, or may be constructed by a combination of various electronic circuits and software programs. For example, when these are constructed in the software program format, a computer for operating according to the software program is provided, or the software program is operated by an arithmetic processing unit in the numerical controller connected to the motor drive device 1. Thus, the function of each unit described above can be realized. Alternatively, the current estimation unit 21, the current comparison unit 22, and the temperature comparison unit 23 may be realized as a semiconductor integrated circuit in which a software program for realizing the function of each unit is written.

  For example, when a plurality of motor drive devices 1 are provided and the control system of each motor drive device 1 is connected via a communication network, the determination result of the leakage current determination unit 14 in each motor drive device 1 is a cloud It may be shared on the server.

  Further, for example, when a plurality of manufacturing cells including a machine tool including the motor drive device 1 are connected via a communication network, the determination result of the leakage current determination unit 14 in each motor drive device 1 It may be shared by the cell controller in the system or the production management apparatus in the higher level of the cell controller.

  A manufacturing cell is a set of a plurality of machine tools that manufacture products flexibly. The production cell is constructed by, for example, a plurality or a plurality of types of machine tools, but the number of machine tools in the production cell is not limited. For example, the manufacturing cell may be a manufacturing line that becomes a final product by sequentially processing a certain workpiece by a plurality of machine tools. In addition, for example, the manufacturing cell is obtained by combining two or more workpieces (parts) processed by each of two or more machine tools with another machine tool in the course of the manufacturing process. ) May be a production line that completes. Further, for example, a final workpiece (product) may be completed by combining two or more workpieces processed by two or more manufacturing cells. The manufacturing cell and the cell controller are interconnected to be communicable via a communication network such as an intranet. The production cell is arranged in a factory for producing a product. On the other hand, the cell controller may be arranged in a factory where the manufacturing cell is arranged, or may be arranged in a building different from the factory. For example, the cell controller may be arranged in another building on the site of a factory where the manufacturing cell is arranged.

  A production management device is provided above the cell controller. The production management device is connected to the cell controller so as to be able to communicate with each other, and instructs the cell controller to produce a production plan. For example, the production management device may be arranged in an office in a remote place from the factory. In this case, the cell controller and the production management apparatus are interconnected so as to be communicable via, for example, an Internet communication network.

  In such a production system, a leakage current (which causes malfunction or damage) has occurred on the display device provided in the cell controller or production management device, or “a leakage current which causes malfunction or damage) A determination result “not generated” may be displayed. Alternatively, instead of the display device or together with the display device, an alarm sound or a buzzer may be generated by an acoustic device to notify the determination result to the user. Thereby, the worker and manager who work in a factory can know easily the motor drive device 1 which should perform the design change for the purpose of leakage current reduction.

  The motor drive device 1 according to the above-described embodiment can be applied to various forms of noise absorption circuits, power conversion units, and motors. Hereinafter, some will be described with reference to FIGS. In addition, about the form shown in FIGS. 6-11, since it is the same as that of the component shown in FIG. 1 about the components other than the component mentioned especially, the same code | symbol is attached | subjected to the same component and the said structure A detailed description of the elements is omitted.

  FIG. 6 is a diagram (part 1) illustrating another form of the noise absorbing circuit in the motor drive device according to the embodiment. As shown in FIG. 6, when the noise absorbing circuit 12 is provided between two phases on the AC input side of the motor driving device 1 (between the R phase and the T phase in the example of FIG. 6), the temperature of the resistor 31 in the noise absorbing circuit 12. Is measured by the temperature measurement unit 13, and the leakage current determination unit 14 may perform a leakage current determination process based on the measurement result.

  FIG. 7 is a diagram (No. 2) illustrating another form of the noise absorbing circuit in the motor drive device according to the embodiment. As shown in FIG. 7, when the noise absorption circuit 12 is provided between one phase of the AC input side of the motor driving device 1 and the ground (between the R phase and the ground in the example of FIG. 7), noise absorption is performed. The temperature of the resistor 31 in the circuit 12 is measured by the temperature measurement unit 13, and the leakage current determination unit 14 may perform a leakage current determination process based on the measurement result.

  FIG. 8 is a diagram (No. 3) illustrating another form of the noise absorbing circuit in the motor drive device according to the embodiment. As shown in FIG. A set of resistor 31 and capacitor 32 connected in series is configured by star connection (Y connection), and one end of the set of resistor 31 and capacitor 32 connected in series is connected to the R phase, S phase, and T phase. When the other end is connected to the ground, the temperature of each resistor 31 in the noise absorbing circuit 12 is measured by the temperature measurement unit 13, and the leakage current determination unit 14 performs a leakage current determination process based on the measurement result. Just do it.

  FIG. 9 is a diagram (part 1) illustrating another configuration of the power conversion unit in the motor drive device according to the embodiment. As shown in FIG. 9, when the AC power supply 3 is a single-phase power supply, the forward converter 104 of the power conversion unit 11 is configured by a single-phase rectifier circuit, and the noise absorption circuit 12 is provided on the AC input side of the motor drive device 1. It is provided between two phases (between the R phase and the T phase in the example of FIG. 9). In this case, the temperature of the resistor 31 in the noise absorption circuit 12 is measured by the temperature measurement unit 13, and the leakage current determination unit 14 may perform a leakage current determination process based on the measurement result.

  FIG. 10 is a diagram (part 2) illustrating another configuration of the power conversion unit in the motor drive device according to the embodiment. As shown in FIG. 10, when the motor 2 is a single-phase AC motor, the inverse converter 105 of the power conversion unit 11 is configured by a single-phase inverse converter. When the noise absorption circuit 12 similar to that shown in FIG. 1 is provided, the temperature of the resistor 31 in the noise absorption circuit 12 is measured by the temperature measurement unit 13, and the leakage current determination unit 14 determines the leakage based on the measurement result. What is necessary is just to perform an electric current determination process.

  FIG. 11 is a diagram (No. 3) illustrating another form of the power conversion unit in the motor drive device according to the embodiment. As shown in FIG. 11, when the motor 2 is a DC motor, the power conversion unit 11 includes a forward converter 101. When the noise absorption circuit 12 similar to that shown in FIG. 1 is provided, the temperature of the resistor 31 in the noise absorption circuit 12 is measured by the temperature measurement unit 13, and the leakage current determination unit 14 determines the leakage based on the measurement result. What is necessary is just to perform an electric current determination process.

  Thus, the motor drive device 1 according to the embodiment can be applied to various forms of noise absorbing circuits, power conversion units, and motors. The motor drive device 1 may be realized by appropriately combining the above-described components. For example, the plurality of motors provided on the AC output side of the reverse converter may include all of a single-phase AC motor, a three-phase AC motor, and a DC motor. In this case, the single-phase AC motor has a single-phase reverse conversion. A three-phase AC converter is connected to the three-phase AC motor, and a forward converter is connected to the DC motor without going through the inverter.

DESCRIPTION OF SYMBOLS 1 Motor drive device 2 Motor 3 AC power supply 11 Power conversion part 12 Noise absorption circuit 13 Temperature measurement part 14 Leakage current determination part 21 Current estimation part 22 Current comparison part 23 Temperature comparison part 24 Notification part 31 Resistance 32 Capacitor 101, 104 Forward conversion 102, 105 Inverter 103 DC link capacitor 200 Floating capacitance

Claims (6)

A power converter that converts AC power supplied from an AC power source into drive power for driving the motor and outputs the drive power;
A noise absorption circuit that has a resistor and a capacitor and absorbs noise generated between the AC power source and the power conversion unit;
A temperature measuring unit for measuring the temperature of the resistor;
Based on the temperature measured by the temperature measurement unit, a leakage current determination unit that determines the presence or absence of leakage current due to motor drive,
A motor drive device comprising: The leakage current determination unit
A current estimation unit for estimating a magnitude of a leakage current flowing in the noise absorption circuit based on the temperature measured by the temperature measurement unit;
A current comparison unit that compares the magnitude of leakage current flowing through the noise absorption circuit estimated by the current estimation unit with a predefined current threshold;
2. The device according to claim 1, wherein when a magnitude of a leakage current flowing through the noise absorption circuit estimated by the current estimation unit exceeds the current threshold, it is determined that a leakage current due to motor driving has occurred. Motor drive device. The leakage current determination unit
A temperature comparison unit that compares the temperature measured by the temperature measurement unit with a predetermined temperature threshold;
The motor driving device according to claim 1, wherein when the temperature measured by the temperature measuring unit exceeds the temperature threshold, it is determined that a leakage current due to motor driving has occurred.   The motor according to any one of claims 1 to 3, further comprising a notification unit that notifies that a leakage current has occurred when the leakage current determination unit determines that a leakage current resulting from motor driving has occurred. Drive device. The power converter is
A forward converter for converting AC power supplied from an AC power source into DC power and outputting the DC power;
An inverter that converts the DC power output from the forward converter into AC driving power for driving an AC motor and outputs the AC power;
The motor drive device according to any one of claims 1 to 4, comprising:   The said power conversion part has a forward converter which converts the alternating current power supplied from alternating current power supply into the direct current drive power for a direct current motor drive, and outputs it. Motor drive device.

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