Motor drive device for calculating motor insulation resistance value

Abstract

This motor drive device comprises an insulation resistance value detection unit for calculating an insulation resistance value of a motor on the basis of: a measurement value of voltage of a smoothing capacitor provided between a rectifier circuit and an inverter; a measurement value of inter-terminal voltage of a measurement resistor; a measurement error calculated on the basis of an estimated value and the measurement value of the inter-terminal voltage of the measurement resistor in the state of being connected to an external DC power supply; and a resistance value of the measurement resistor.

Description

[Technical field]

[0001] The present invention relates to a motor drive device that calculates the insulation resistance value of a motor. [Background technology]

[0002] In servo motors installed in machine tools, the insulation resistance value (insulation resistance value) of the motor coil (winding) against the ground decreases due to the infiltration of oil over time. When the insulation resistance value of the motor coil decreases, a leakage current flows in the closed circuit consisting of the motor, the motor drive device, and the ground. When the leakage current flows in the motor drive device in addition to the normal motor drive current, the servo amplifier performs an overcurrent detection operation and the breaker installed in the input stage trips. As a result, the machine tool in which the motor is installed will come to an emergency stop. When such an emergency stop occurs, the machine tool may be stopped for a long period of time to determine the cause, which reduces efficiency. For this reason, the task of measuring the insulation resistance value of the motor is essential for the operation of the motor drive device.

[0003] For example, there is known a method for detecting insulation resistance deterioration of a motor driven by a motor drive device including a power supply unit that rectifies power supplied from an AC power source via a switch in a rectifier circuit and smoothes it with a capacitor, and a motor drive amplifier that converts the DC voltage from the power supply unit into AC to drive the motor, the method comprising turning off the switch to stop operation of the motor, connecting one end of the capacitor to the ground and connecting the other end to the motor coil, detecting the current flowing in the closed circuit formed by the capacitor, the motor coil, and the ground, and detecting insulation resistance deterioration of the motor (see, for example, Patent Document 1).

[0004] For example, the present invention may include a power supply unit that rectifies an AC voltage supplied from an AC power supply via a switch into a DC voltage using a rectifier circuit and smoothes the rectified DC voltage using a capacitor, a motor drive amplifier unit that converts the DC voltage from the power supply unit into an AC voltage using upper arm and lower arm switching elements to drive a motor, a power supply voltage measurement unit that measures the voltage of the power supply unit, a contact unit that connects one end of the capacitor to the ground, and a current detection unit that is provided between the other end of the capacitor and a motor coil, and the switch is turned off and the contact unit is turned on, and the contact unit, the capacitor, the motor, and the motor are connected to the ground by the current detection unit. A motor drive device equipped with a failure detection function for an insulation resistance deterioration detection unit of a motor, characterized in that it comprises: an insulation resistance deterioration detection unit that detects whether or not the insulation resistance of the motor has deteriorated based on a detection signal obtained from a closed circuit formed by a motor coil and the ground; and a failure detection unit that changes the contact unit from an on state to an off state, arbitrarily switches a switching element of an upper arm or a lower arm of the motor drive amplifier unit, and detects whether or not the insulation resistance deterioration detection unit has a failure based on the detection signal in the insulation resistance deterioration detection unit and a voltage value measured by the power supply voltage measurement unit (see, for example, Patent Document 2).

[0005] For example, a device for detecting insulation deterioration of a motor connected to a motor drive device having a converter unit having a rectifier circuit that rectifies an AC power supply, a smoothing capacitor that smoothes the output of the rectifier circuit, and a plurality of inverter units that convert DC from the converter unit to AC to drive a plurality of motors, the device including: a first switch that, when insulation deterioration is detected, is brought into conduction to ground one end of the smoothing capacitor; a voltage detection unit that measures the voltage across the smoothing capacitor; a plurality of second switches that, when insulation deterioration is detected, are brought into conduction to connect the other end of the smoothing capacitor to windings of the plurality of motors, respectively; a plurality of current detection units that, when the first switch and the plurality of second switches are brought into conduction, respectively detect the discharge current of the smoothing capacitor that flows through the insulation resistance of each of the plurality of motors; A motor insulation deterioration detection device is known that includes a plurality of insulation resistance calculation units that calculate the insulation resistance of each of the plurality of motors from the current detected by each of the current detection units, wherein the one first switch and the one voltage detection unit are provided in the converter unit, the plurality of second switches, the plurality of current detection units, and the plurality of insulation resistance calculation units are provided in the plurality of inverter units, respectively, and the device includes communication means that transmits from the converter unit to the plurality of inverter units a voltage value detected by the one voltage detection unit and a signal notifying the timing of turning on the one first switch, and wherein connection by the second switch, detection of current by the current detection unit, and calculation of insulation resistance by the insulation resistance calculation unit are performed simultaneously at the same timing in each of the plurality of inverter units (see, for example, Patent Document 3).

[0006] For example, a motor drive device is known which comprises: a rectifier circuit which rectifies an AC voltage supplied from an AC power supply via a first switch into a DC voltage; a power supply unit which smoothes the DC voltage rectified by the rectifier circuit with a capacitor; an inverter unit which converts the DC voltage smoothed by the power supply unit into an AC voltage by the switching operation of a semiconductor switching element to drive a motor; a current detection unit which measures a current value flowing through a resistor having one end connected to a coil of the motor and the other end connected to one terminal of the capacitor; a voltage detection unit which measures a voltage value across the capacitor; a second switch which grounds the other terminal of the capacitor; and an insulation resistance detection unit which stops operation of the motor, turns off the first switch, and detects an insulation resistance value of the motor, which is the resistance between the motor coil and the ground, using two sets of the current values ​​and the voltage values ​​measured in two states, namely, a state in which the second switch is turned off and a state in which the second switch is turned on (see, for example, Patent Document 4).

[0007] For example, there is known a motor control device that includes a first power supply unit, a first switch that can turn off the power supply from the first power supply unit, a DC supply unit that outputs power from the first power supply unit to a bus bar, a capacitor connected to the bus bar, and a switching element that converts the DC supplied to the bus bar into AC to drive and control a motor, the motor control device including a second power supply unit having one end connected to the bus bar and the other end grounded via a second switch, a current detection unit that detects a current value between a winding of the motor and the bus bar to which the second power supply unit is connected, and an insulation resistance calculation unit that turns off the power supply using the first switch unit, and calculates an insulation resistance value of the motor based on the current values ​​detected by the current detection unit when the second switch is open and closed, the voltage value of the capacitor, and the voltage value of the second power supply unit (see, for example, Patent Document 5). [Prior art documents] [Patent documents]

[0008] [Patent Document 1] Patent No. 4554501 [Patent Document 2] Patent No. 5832578 [Patent Document 3] Patent No. 4565036 [Patent Document 4] Patent No. 5788538 [Patent Document 5] JP 2021-018163 A Summary of the Invention [Problem to be solved by the invention]

[0009] In order to accurately detect the insulation resistance value, it is extremely important to eliminate error factors caused by the components that make up the insulation resistance value detection circuit. In addition, it is preferable to detect the insulation resistance value with less burden on the worker. Thus, in the motor drive device, a technology is desired that can detect the insulation resistance value of the motor with high accuracy and easily. [Means for solving the problem]

[0010] According to one aspect of the present disclosure, there is provided a power supply unit that rectifies an AC voltage supplied from the AC power supply via the first switch in a closed state into a DC voltage using a rectifier circuit, smoothes the rectified DC voltage using a capacitor, and outputs the DC voltage, a motor drive amplifier unit that converts the DC voltage from the power supply unit input via a DC input unit into an AC voltage for driving the motor using switching elements in an upper arm and a lower arm, and supplies the AC voltage to the motor via an AC output unit, a first voltage measurement unit that acquires a measured value of the voltage of the power supply unit, and an insulation resistance value detection unit having: a second switch that connects one end of the capacitor to the ground and does not connect one end of the capacitor to the ground when in an open state; a measurement resistor provided between one terminal in the DC input unit to which the other end of the capacitor is connected and one terminal in the AC output unit to which the motor coil of the motor is connected; a second voltage measurement unit that obtains a measured value of a voltage between the terminals of the measurement resistor; and a calculation unit that calculates an insulation resistance value of the motor using at least the measured value of the voltage between the terminals of the measurement resistor obtained by the second voltage measurement unit; a voltage estimating unit that calculates an estimated value of the terminal-to-terminal voltage of the measurement resistor based on a value of a DC voltage from the DC power source and a resistance value of the measurement resistor when a second closed circuit including the DC power source and the measurement resistor is formed by applying a voltage between one terminal in the DC input unit and one terminal in the AC output unit and opening the first and second switches and turning off the switching element of the motor drive amplifier unit while the first and second switches are applied between one terminal in the DC input unit and one terminal in the AC output unit, and calculates an estimated value of the terminal-to-terminal voltage of the measurement resistor based on a value of a DC voltage from the DC power source and a resistance value of the measurement resistor when the second closed circuit is formed; and an error detection unit that detects a measurement error of the second voltage measurement unit using an estimated value of the terminal voltage of the fixed resistor, and the calculation unit calculates an insulation resistance value of the motor based on the measured value of the voltage of the power supply unit acquired by the first voltage measurement unit and the measured value of the terminal voltage of the measurement resistor acquired by the second voltage measurement unit when a first closed circuit is formed including the second switch, the capacitor, the measurement resistor, the motor coil, and the ground by opening the first switch and closing the second switch. Effect of the Invention

[0011] According to one aspect of the present disclosure, it is possible to realize a motor drive device that can easily detect the insulation resistance value of a motor with high accuracy. [Brief description of the drawings]

[0012] [Figure 1] FIG. 1 illustrates a motor drive device according to an embodiment of the present disclosure. [Diagram 2] 11 is a diagram illustrating a DC power supply connected when detecting a measurement error for a second voltage measurement unit in a motor drive device according to an embodiment of the present disclosure. FIG. [Diagram 3] 11 is a diagram illustrating a second closed circuit configured when detecting a measurement error for a second voltage measurement unit in a motor drive device according to an embodiment of the present disclosure. FIG. [Figure 4] 5 is a flowchart showing an operational flow of a measurement error detection process according to a first mode in a motor drive device according to an embodiment of the present disclosure. [Diagram 5] 10 is a flowchart showing an operational flow of a measurement error detection process according to a second mode in a motor drive device according to an embodiment of the present disclosure. [Figure 6] 1 is a diagram illustrating a first closed circuit that is configured when an insulation resistance value detection process is performed by an insulation resistance value detection unit in a motor drive device according to an embodiment of the present disclosure. FIG. [Figure 7] 5 is a flowchart showing an operation flow of an insulation resistance value detection process performed by an insulation resistance value detection unit in the motor drive device according to the embodiment of the present disclosure. [Figure 8] The second switch 31 in the closed state is not shown. [Figure 9] 1 is a perspective view illustrating a servo amplifier which is a motor drive amplifier section in a motor drive device according to an embodiment of the present disclosure. FIG. [Figure 10] 1 is a front view illustrating a servo amplifier which is a motor drive amplifier section in a motor drive device according to an embodiment of the present disclosure. [Figure 11]1 is an exploded perspective view illustrating a servo amplifier which is a motor drive amplifier section in a motor drive device according to an embodiment of the present disclosure. FIG. [Figure 12] 2 is a schematic diagram illustrating a first board and a second board in a servo amplifier that is a motor drive amplifier section in a motor drive device according to an embodiment of the present disclosure. FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0013] A motor drive device for calculating the insulation resistance value of a motor will be described below with reference to the drawings. In each drawing, the same components are given the same reference symbols. In addition, the scale of these drawings is appropriately changed to facilitate understanding. In addition, the embodiment shown in the drawings is one example for carrying out the invention, and the invention is not limited to the illustrated embodiment.

[0014] FIG. 1 is a diagram illustrating a motor drive device according to an embodiment of the present disclosure.

[0015] As an example, a case where a motor 3 is controlled by a motor drive device 1 connected to an AC power source 2 is shown. In this embodiment, the type of the motor 3 is not particularly limited, and may be, for example, an induction motor or a synchronous motor. The number of phases of the AC power source 2 and the motor 3 is not particularly limited in this embodiment, and may be, for example, three-phase or single-phase. Machines in which the motor 3 is provided include, for example, machine tools, robots, forging machines, injection molding machines, industrial machines, various electrical appliances, trains, automobiles, and aircraft. Examples of the AC power source 2 include a three-phase AC 400V power source, a three-phase AC 200V power source, a three-phase AC 600V power source, and a single-phase AC 100V power source. In the illustrated example, the AC power source 2 and the motor 3 are each three-phase.

[0016] An insulation resistor 4 exists between the motor coil (winding) of the motor 3 and the ground. The insulation resistance value Rm [Ω] of the insulation resistor 4 is infinite when there is no degradation, and as degradation progresses, it gradually decreases from infinity to several MΩ, several hundred kΩ, and so on. The motor drive device 1 according to an embodiment of the present disclosure has a function of detecting the insulation resistance value Rm [Ω] of the motor 3.

[0017] As shown in FIG. 1, a motor driving device 1 according to one embodiment of the present disclosure includes a first switch 11, a power supply unit 12, a motor driving amplifier unit 13, a first voltage measurement unit 14, an insulation resistance value detection unit 15, a voltage estimation unit 16, an error detection unit 17, a memory unit 18, and an erasure unit 19.

[0018] The first switch 11 opens and closes an electric path between the AC power source 2 and the rectifier circuit 21 in the power source unit 12. The opening and closing of the electric path by the first switch 11 is controlled, for example, by the control unit 30 in the insulation resistance value detection unit 15. Alternatively, the first switch 11 may be controlled by an arbitrary control unit (not shown) consisting of a calculation processing device provided outside the insulation resistance value detection unit 15. The first switch 11 is, for example, an electromagnetic contactor. The closed state of the electric path from the AC power source 2 to the rectifier circuit 21 in the power source unit 12 is realized by closing the contacts of the first switch 11 which is an electromagnetic contactor, and the open state of the electric path from the AC power source 2 to the rectifier circuit 21 in the power source unit 12 is realized by opening the contacts of the first switch 11 which is an electromagnetic contactor. Note that the first switch 11 may be, for example, a relay or a semiconductor switching element instead of an electromagnetic contactor, as long as it can open and close the electric path from the AC power source 2.

[0019] The power supply unit 12 and the motor drive amplifier unit 13 are connected via a DC link. The "DC link" refers to a circuit portion that electrically connects the DC output side of the power supply unit 12 and the DC input side of the motor drive amplifier unit 13, and may also be called a "DC link unit," "DC link," "DC link unit," or "DC intermediate circuit."

[0020] The power supply unit 12 has a rectifier circuit 21 and a capacitor 22, and rectifies the AC voltage supplied from the AC power supply 2 via the first switch 11 in an open state into a DC voltage by the rectifier circuit 21, and smoothes the rectified DC voltage by the capacitor 22 before outputting it.

[0021] The rectifier circuit 21 in the power supply unit 12 may be any circuit capable of converting AC voltage into DC voltage, and may be, for example, a diode rectifier circuit, a 120-degree conduction type rectifier circuit, or a PWM switching control type rectifier circuit having a switching element therein. The rectifier circuit 21 is configured as a three-phase bridge circuit when the AC power source 2 is a three-phase AC power source, and is configured as a single-phase bridge circuit when the AC power source 2 is a single-phase AC power source. When the rectifier circuit 21 is a PWM switching control type rectifier circuit, it is made up of a bridge circuit of a switching element and a diode 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 this embodiment, and other switching elements may be used.

[0022] The capacitor 22 in the power supply unit 12 has a function of smoothing the DC voltage output by the rectifier circuit 21 and a function of storing DC power in the DC link. The capacitor 22 may also be called a smoothing capacitor or a DC link capacitor. Examples of the capacitor 22 include an electrolytic capacitor and a film capacitor.

[0023] A first voltage measuring unit 14 is connected to both pole terminals of the capacitor 22. The first voltage measuring unit 14 is a measurement circuit that acquires a measured value of the (DC) voltage of the power supply unit 12, which is the voltage applied to the capacitor 22.

[0024] The motor drive amplifier unit 13 has an inverter configured with a bridge circuit in which a pair of switching elements and diodes connected in anti-parallel to the switching elements are provided on the upper and lower arms. In the illustrated example, the motor 3 is a three-phase AC motor, so the inverter in the motor drive amplifier unit 13 is configured with a three-phase bridge circuit. The switching element of the upper arm of the U phase is S u1 , the switching element of the lower arm of U phase is S u2 , the switching element of the upper arm of the V phase is S v1 , the switching element of the lower arm of the V phase is S v2 , the upper arm switching element of the W phase is S w1 , the switching element of the lower arm of the W phase is S w2 Let us assume that.

[0025] The motor drive amplifier unit 13 has a DC input unit 41 on the DC link side and an AC output unit 42 on the AC motor side. A positive power line of the DC link is connected to a positive DC terminal 41P of the DC input unit 41, and a negative power line of the DC link is connected to a negative DC terminal 41N of the DC input unit 41. A U-phase motor power line is connected to a U-phase AC terminal 42U of the AC output unit 42, a V-phase motor power line is connected to a V-phase AC terminal 42V of the AC output unit 42, and a W-phase motor power line is connected to a W-phase AC terminal 42W of the AC output unit 42. The U-phase motor power line, the V-phase motor power line, and the W-phase motor power line are connected to the U-phase motor coil, the V-phase motor coil, and the W-phase motor coil of the motor 3, respectively.

[0026] The motor drive amplifier unit 13 performs power conversion operation by controlling the on / off operation of the switching elements of the upper arm and the lower arm by a PWM switching command from a higher-level control device (not shown). That is, the motor drive amplifier unit 13 converts the DC voltage in the DC link input via the DC input unit 41 into an AC voltage for driving the motor by turning on and off the switching elements of the upper arm and the lower arm, and supplies the AC voltage to the motor 3 via the AC output unit 42. In one embodiment of the present disclosure, the on / off operation of the switching elements of the upper arm and the lower arm in the motor drive amplifier unit 13 is also controlled by the control unit 30 of the insulation resistance value detection unit 15, the details of which will be described later.

[0027] The insulation resistance value detection unit 15 detects an insulation resistance value Rm [Ω] which is a resistance value of the insulation resistance 4 between the motor coil (winding) of the motor 3 and the ground. The insulation resistance value detection unit 15 has a control unit 30, a second switch 31, a measurement resistor 32, a second voltage measurement unit 33, a calculation unit 34, a correction value generation unit 35, and a correction unit 36. The detection of the insulation resistance value Rm [Ω] of the insulation resistance 4 of the motor 3 by the insulation resistance value detection unit 15 is performed using various data obtained regarding a first closed circuit obtained by opening the first switch 11 and closing the second switch 31, and turning off all switching elements in the motor drive amplifier unit 13. The first closed circuit is an insulation resistance value detection closed circuit including the second switch 31, the capacitor 22, the measurement resistor 32, the motor coil of the motor 3, and the ground.

[0028] The second switch 31 in the insulation resistance value detection unit 15 has one terminal connected to a voltage dividing resistor 38 and the other terminal connected to a voltage dividing resistor 39. The voltage dividing resistor 38 has one terminal connected to a positive power line connecting the rectifier circuit 21 and the capacitor 22 in the power supply unit 12. The voltage dividing resistor 39 has one terminal connected to the ground. The second switch 31 is controlled to be grounded by opening and closing it, that is, when in a closed state, the positive terminal of the capacitor 22 is connected to the ground, and when in an open state, one end of the capacitor is not connected to the ground. The opening and closing of the second switch 31 is controlled by the control unit 30. The second switch 31 is composed of, for example, a relay, a semiconductor switching element, or an electromagnetic contactor.

[0029] The measuring resistor 32 is provided between the negative terminal of the capacitor 22 and the motor coil of the motor 3. More specifically, one terminal of the measuring resistor 32 is connected to the negative terminal of the capacitor 22 via the negative DC terminal 41N in the DC input section 41 of the motor drive amplifier section 13. The other terminal of the measuring resistor 32 is connected to one of the motor power lines of the U-phase motor power line, the V-phase motor power line, and the W-phase motor power line of the motor 3 via a voltage dividing resistor 37. In the illustrated example, as an example, the other terminal of the measuring resistor 32 is connected to a U-phase motor power line connecting the U-phase AC terminal 42U in the AC output section 42 of the motor drive amplifier section 13 and the U-phase motor coil of the motor 3. The second voltage measuring section 33 is a measuring circuit that acquires a measured value of the voltage between the terminals of the measuring resistor 32. For example, the measuring resistor 32 and the second voltage measuring section 33 may be configured by an insulating amplifier. The voltage dividing resistor 37 is provided to adjust the input voltage to the isolation amplifier so that it falls within an appropriate range.

[0030] The correction value generating unit 35 generates a correction value based on a measurement error of the second voltage measuring unit 33 detected by the error detecting unit 17 described later. The correction unit 36 ​​generates a corrected measurement value of the terminal voltage of the measurement resistor 32 by correcting the measurement value of the terminal voltage of the measurement resistor 32 acquired by the second voltage measuring unit 33 when the first closed circuit is configured, using the correction value generated by the correction value generating unit 35. The corrected measurement value of the terminal voltage of the measurement resistor 32 generated by the correction unit 36 ​​based on the measurement error of the second voltage measuring unit 33 is used by the calculation unit 34 to calculate the insulation resistance value Rm [Ω] of the motor 3.

[0031] The calculation unit 34 calculates the insulation resistance value of the motor 3 using at least the measurement value of the terminal voltage of the measurement resistor 32 acquired by the second voltage measurement unit 33 when a first closed circuit is configured including the second switch 31, the capacitor 22, the measurement resistor 32, the motor coil of the motor 3, and the ground. That is, when the first closed circuit is configured, the calculation unit 34 calculates the insulation resistance value Rm [Ω] of the insulation resistor 4 of the motor 3 based on the measurement value of the voltage of the power supply unit 12 acquired by the first voltage measurement unit 14, the corrected measurement value of the terminal voltage of the measurement resistor 32 generated by the correction unit 36, and the resistance value of the measurement resistor 32. Details of the calculation process of the insulation resistance value by the calculation unit 34 will be described later.

[0032] The detection of the measurement error of the second voltage measurement unit 33 is performed using various data obtained regarding a second closed circuit obtained by opening the first switch 11 and the second switch 31 and turning off all switching elements of the upper arm or the lower arm of the motor drive amplifier unit 13 while applying a DC voltage from a DC power supply different from the power supply unit 12 between one terminal in the DC input unit 41 (negative DC terminal 41N in the illustrated example) and one terminal in the AC output unit 42 (U-phase AC terminal 42U in the illustrated example). The second closed circuit is an error detection closed circuit including a DC power supply and a measurement resistor 32.

[0033] The voltage estimation unit 16 calculates an estimate of the terminal-to-terminal voltage of the measurement resistor 32 based on the measured value of the voltage of the power supply unit 12 acquired by the first voltage measurement unit 14 and the resistance value of the measurement resistor 32 in accordance with a circuit equation for a second closed circuit including the DC power supply and the measurement resistor 32, which is obtained by applying a DC voltage from a DC power supply other than the power supply unit 12 between one terminal in the DC input unit 41 (negative DC terminal 41N in the illustrated example) and one terminal in the AC output unit 42 (U-phase AC terminal 42U in the illustrated example), and based on the measured value of the voltage of the power supply unit 12 acquired by the first voltage measurement unit 14 and the resistance value of the measurement resistor 32.

[0034] The error detection unit 17 detects the error between the measured value of the terminal voltage of the measurement resistor 32 acquired by the second voltage measurement unit 33 when the second closed circuit is configured and the estimated value of the terminal voltage of the measurement resistor 32 calculated by the voltage estimation unit 16. The measurement error of the second voltage measurement unit 33 detected by the error detection unit 17 is used in the correction value generation process by the correction value generation unit 35. It should be noted that the "measured value of the terminal voltage of the measurement resistor 32 acquired by the second voltage measurement unit 33" used in the error detection process by the error detection unit 17 is not the value corrected by the correction unit 36.

[0035] The storage unit 18 stores the measurement error of the second voltage measuring unit 33 detected by the error detection unit 17. The storage unit 18 may be composed of an electrically erasable and recordable non-volatile memory such as an EEPROM (registered trademark), or a high-speed readable and writable random access memory such as a DRAM or an SRAM. The measurement error stored in the storage unit 18 is used by the correction value generation unit 35 to generate a correction value. The measurement error stored in the storage unit 18 may be erased by the erasure unit 19 in a predetermined case.

[0036] An arithmetic processing device (processor) is provided in the motor drive device 1. Examples of the arithmetic processing device include an IC, an LSI, a CPU, an MPU, and a DSP. The arithmetic processing device includes a first voltage measurement unit 14, a control unit 30, a second voltage measurement unit 33, a calculation unit 34, a correction value generation unit 35, a correction unit 36, a voltage estimation unit 16, an error detection unit 17, and an erasure unit 19. Each of these units included in the arithmetic processing device is a functional module realized by, for example, a computer program executed on the processor. For example, when the first voltage measurement unit 14, the control unit 30, the second voltage measurement unit 33, the calculation unit 34, the correction value generation unit 35, the correction unit 36, the voltage estimation unit 16, the error detection unit 17, and the erasure unit 19 are constructed in the form of a computer program, the functions of each unit can be realized by operating the arithmetic processing device according to the computer program. Computer programs for executing the processes of the first voltage measurement unit 14, the control unit 30, the second voltage measurement unit 33, the calculation unit 34, the correction value generation unit 35, the correction unit 36, the voltage estimation unit 16, the error detection unit 17, and the erasure unit 19 may be provided in a form recorded on a computer-readable recording medium such as a semiconductor memory, a magnetic recording medium, or an optical recording medium. Alternatively, the first voltage measurement unit 14, the control unit 30, the second voltage measurement unit 33, the calculation unit 34, the correction value generation unit 35, the correction unit 36, the voltage estimation unit 16, the error detection unit 17, and the erasure unit 19 may be realized as a semiconductor integrated circuit in which a computer program for realizing the function of each unit is written.

[0037] The insulation resistance value of the motor 3 detected by the insulation resistance value detection unit 15 is sent to a display unit (not shown), and the display unit displays the "insulation resistance value of the motor 3" to notify an operator. Examples of the display unit include a standalone display device, a display device attached to the motor drive device 1, a display device attached to a higher-level control device (not shown), and a display device attached to a personal computer or a mobile terminal. In addition, for example, the insulation resistance value of the motor 3 detected by the insulation resistance value detection unit 15 is sent to an alarm output unit (not shown), and the alarm output unit may output an alarm when the insulation resistance value of the motor 3 falls below a predetermined value. The alarm output from the alarm output unit is sent to a light-emitting device (not shown), such as an LED or lamp, and the light-emitting device emits light when it receives the alarm to notify an operator of the "deterioration of the insulation resistance 4 of the motor 3." Also, for example, the alarm output from the alarm output unit is sent to, for example, an audio device (not shown), and when the audio device receives the alarm, it emits a sound such as a voice, speaker, buzzer, or chime to notify the worker of "deterioration of the insulation resistance 4 of the motor 3." This allows the worker to reliably and easily grasp the insulation resistance value of the motor 3 and the deterioration of the insulation resistance 4 of the motor 3, and can easily take measures such as replacing the motor 3 or disassembling and cleaning the motor 3.

[0038] Next, detection of a measurement error in second voltage measuring unit 33 will be described in more detail.

[0039] 2 is a diagram illustrating a DC power supply connected when detecting a measurement error for the second voltage measurement unit in a motor drive device according to an embodiment of the present disclosure. In order to detect a measurement error for the second voltage measurement unit 33, as shown in FIG. 2, a DC power supply 200 for applying a DC voltage different from that of the power supply unit 12 is connected between the negative DC terminal 41N in the DC input unit 41 and one terminal in the AC output unit 42. In the example shown in FIGS. 1 and 2, the other terminal of the measurement resistor 32 is connected to the U-phase motor power line via the voltage dividing resistor 37 and the U-phase AC terminal 42U in the AC output unit 42 of the motor drive amplifier unit 13, so that the DC power supply 200 is connected between the negative DC terminal 41N in the DC input unit 41 and the U-phase AC terminal 42U in the AC output unit 42. When the other terminal of the measurement resistor 32 is connected to the V-phase motor power line via the voltage dividing resistor 37 and the V-phase AC terminal 42V in the AC output section 42 of the motor drive amplifier section 13, a DC power supply 200 is connected between the negative DC terminal 41N in the DC input section 41 and the V-phase AC terminal 42V in the AC output section 42. When the other terminal of the measurement resistor 32 is connected to the W-phase motor power line via the voltage dividing resistor 37 and the W-phase AC terminal 42W in the AC output section 42 of the motor drive amplifier section 13, a DC power supply 200 is connected between the negative DC terminal 41N in the DC input section 41 and the W-phase AC terminal 42W in the AC output section 42.

[0040] The DC power supply 200 is electrically and detachably connected to one terminal in the DC input section 41 and one terminal in the AC output section 42 of the motor drive amplifier section 13, and a specific example is as follows. For example, an operator may manually connect a portable battery as the DC power supply 200 between one terminal in the DC input section 41 and one terminal in the AC output section 42 of the motor drive amplifier section 13. Alternatively, for example, a shipping test device having the DC power supply 200 may be prepared in advance, and the shipping test device may be connected to one terminal in the DC input section 41 and one terminal in the AC output section 42 of the motor drive amplifier section 13 during shipping testing of the motor drive device 1. Alternatively, for example, the DC power supply 200 may be mounted in the main body of the motor drive amplifier section 13 or in a module adjacent to the motor drive amplifier section 13, and a configuration may be made in which the presence or absence of electrical connection between one terminal in the DC input section 41 of the motor drive amplifier section 13 and one terminal in the AC output section 42 of the motor drive amplifier section 13 and the DC power supply 200 can be switched by operating a changeover switch.

[0041] 3 is a diagram illustrating a second closed circuit configured when detecting a measurement error for a second voltage measurement unit in a motor drive device according to an embodiment of the present disclosure. In FIG. 3, the control unit 30, the calculation unit 34, the correction value generation unit 35, the correction unit 36, the voltage estimation unit 16, the error detection unit 17, and the erasure unit 19 are omitted from the illustration.

[0042] To detect a measurement error for the second voltage measuring unit 33, a DC power supply 200 is connected between the negative side DC terminal 41N in the DC input unit 41 and the U-phase AC terminal 42U in the AC output unit 42. In addition, the first switch 11 and the second switch 31 are opened and all switching elements of the upper arm or lower arm of the motor drive amplifier unit 13 are turned off. This forms a second closed circuit 102 for detecting a measurement error, as indicated by a thick arrow in the figure.

[0043] By using the value of the DC voltage of the DC power supply 200 in a state in which the second closed circuit 102 is formed, it is possible to estimate the voltage between the terminals of the measurement resistor 32. When the resistance value of the measurement resistor 32 is Rb [Ω], the resistance value of the voltage dividing resistor 37 is Ra [Ω], and the DC voltage value of the DC power supply 200 is Ve [V], the estimated value Vin1 [V] of the voltage between the terminals of the measurement resistor 32 in a state in which the second closed circuit 102 is formed can be calculated based on Equation 1.

[0044]

number

[0045] The voltage estimation unit 16 calculates an estimated value Vin1 [V] of the voltage between the terminals of the measurement resistor 32 when the second closed circuit 102 is configured, using the DC voltage value Ve [V] of the DC power supply 200, the resistance value Rb [Ω] of the measurement resistor 32, and the resistance value Ra [Ω] of the voltage dividing resistor 37 based on Equation 1. The resistance value Rb [Ω] of the measurement resistor 32 and the resistance value Ra [Ω] of the voltage dividing resistor 37 are known, and for example, the nominal values ​​of the manufacturers of these components may be used. The resistance value Rb [Ω] of the measurement resistor 32 and the resistance value Ra [Ω] of the voltage dividing resistor 37 may be input in advance into the arithmetic processing device constituting the voltage estimation unit 16, and may be used in the calculation of the estimated value Vin1 [V] of the voltage between the terminals of the measurement resistor 32 by the voltage estimation unit 16.

[0046] On the other hand, when the second closed circuit 102 is similarly configured, the second voltage measuring unit 33 can also obtain the measured value (actual measured value) Vin2 [V] of the inter-terminal voltage of the measuring resistor 32.

[0047] When the second closed circuit 102 is configured, the estimated value Vin1 [V] of the terminal voltage of the measurement resistor 32 and the measured value (actual value) Vin2 [V] of the terminal voltage of the measurement resistor 32 are ideally equal. However, in reality, there exists a measurement error between the two due to component errors and aging of the second voltage measuring unit 33, the measurement resistor 32, and the voltage dividing resistor 37 that configure the isolation amplifier. The measurement error includes an offset error and a gain error. Here, several forms of measurement error detection processing are listed.

[0048] First, the measurement error detection process according to the first embodiment will be described.

[0049] The measurement error detection process according to the first embodiment detects only the offset error. When the second closed circuit 102 is configured with the DC voltage value Ve [V] of the DC power supply 200 applied between the negative side DC terminal 41N in the DC input unit 41 and the U-phase AC terminal 42U in the AC output unit 42, the offset error ΔV [V] between the estimated value Vin1 [V] of the inter-terminal voltage of the measurement resistor 32 and the measured value (actual value) Vin2 [V] of the inter-terminal voltage of the measurement resistor 32 is expressed as in Equation 2.

[0050]

number

[0051] In the measurement error detection process according to the first embodiment, the error detection unit 17 detects an offset error ΔV [V], which is a measurement error, using the measured value Vin2 [V] of the inter-terminal voltage of the measurement resistor 32 acquired by the second voltage measurement unit 33 when the second closed circuit 102 is configured and the estimated value Vin1 [V] of the inter-terminal voltage of the measurement resistor 32 calculated by the voltage estimation unit 16, based on Equation 2. The offset error ΔV [V], which is the measurement error for the second voltage measurement unit 33 detected by the error detection unit 17, is stored in the storage unit 18.

[0052] FIG. 4 is a flowchart showing an operational flow of a measurement error detection process according to a first mode in a motor drive device according to an embodiment of the present disclosure.

[0053] In the measurement error detection process according to the first embodiment, first, in step S101, the control unit 30 controls the first switch 11 to an open state and the second switch 31 to an open state. In addition, the control unit 30 controls all switching elements in the motor drive amplifier unit 13 to an off state.

[0054] In step S102, the DC power supply 200 is connected between the negative side DC terminal 41N in the DC input unit 41 and the U-phase AC terminal 42U in the AC output unit 42, and a DC voltage Ve [V] is applied. This forms a second closed circuit 102 for error detection including the DC power supply 200 and the measurement resistor 32.

[0055] In step S103, the voltage estimation unit 16 calculates an estimated value Vin1 [V] of the inter-terminal voltage of the measurement resistor 32 based on Equation 1, using the DC voltage value Ve [V] of the DC power supply 200, the resistance value Rb [Ω] of the measurement resistor 32, and the resistance value Ra [Ω] of the voltage dividing resistor 37 when the second closed circuit 102 is configured.

[0056] In step S104, the second voltage measurement unit 33 acquires a measured value Vin2 [V] of the inter-terminal voltage of the measurement resistor 32 when the second closed circuit 102 is configured. Note that steps S103 and S104 may be executed in reverse order.

[0057] In step S105, the error detection unit 17 detects the offset error ΔV [V] based on Equation 2, using the measurement value Vin2 [V] of the inter-terminal voltage of the measurement resistor 32 acquired by the second voltage measurement unit 33 when the second closed circuit 102 is constructed, and the estimated value Vin1 [V] of the inter-terminal voltage of the measurement resistor 32 calculated by the voltage estimation unit 16.

[0058] In step S106, the storage unit 18 stores the offset error ΔV [V] detected by the error detection unit 17. After that, the insulation resistance detection process S300, which will be described later, is started.

[0059] Next, the measurement error detection process according to the second embodiment will be described.

[0060] The measurement error detection process according to the second embodiment detects both the offset error and the gain error. When the gain error and the offset error of the second voltage measurement unit 33 are a and b [V], the relationship of Equation 3 is established between the measured value Vin2 [V] of the inter-terminal voltage of the measurement resistor 32 acquired by the second voltage measurement unit 33 when the second closed circuit 102 is configured and the estimated value Vin1 [V] of the inter-terminal voltage of the measurement resistor 32 calculated by the voltage estimation unit 16.

[0061]

number

[0062] When the second closed circuit 102 is configured, if the DC voltage value Ve [V] of the DC power supply 200 differs, the estimated value Vin1 [V] of the measurement resistor 32 estimated by the voltage estimation unit 16 also differs, and the measured value Vin2 [V] of the measurement resistor 32 acquired by the second voltage measurement unit 33 also differs. Therefore, if two types of voltages are applied between the negative side DC terminal 41N in the DC input unit 41 and the U-phase AC terminal 42U in the AC output unit 42 as the DC voltage value Ve of the DC power supply 200, two types of relational expressions based on Equation 3 are obtained.

[0063] Let Vin11 [V] be the first estimated value of the inter-terminal voltage of the measurement resistor 32 estimated in a state in which the second closed circuit 102 is configured when the value of the first DC voltage of the DC power supply 200 is Ve1 [V], and let Vin21 [V] be the first measured value of the inter-terminal voltage of the measurement resistor 32 in a state in which the second closed circuit 102 is configured. In this case, Equation 4 and Equation 5 hold.

[0064]

number

[0065]

number

[0066] When the value of the second DC voltage of the DC power supply 200 is Ve2 [V], a second estimated value of the inter-terminal voltage of the measurement resistor 32 estimated in the state in which the second closed circuit 102 is formed is Vin12 [V], and a second measured value of the inter-terminal voltage of the measurement resistor 32 in the state in which the second closed circuit 102 is formed is Vin22 [V]. However, the value of the second DC voltage of the DC power supply 200, Ve2 [V], is a value different from the value of the first DC voltage, Ve1 [V]. In this case, Equation 6 and Equation 7 hold.

[0067]

number

[0068]

number

[0069] In the measurement error detection process according to the second embodiment, the voltage estimation unit 16 calculates a first estimated value Vin11 [V] of the inter-terminal voltage of the measurement resistor using the value Ve1 [V] of the first DC voltage from the DC power supply 200, the resistance value Rb [Ω] of the measurement resistor 32, and the resistance value Ra [Ω] of the voltage dividing resistor 37 when the second closed circuit 102 is configured based on Equation 4. The voltage estimation unit 16 calculates a second estimated value Vin12 [V] of the inter-terminal voltage of the measurement resistor using the value Ve2 [V] of the second DC voltage from the DC power supply 200, the resistance value Rb [Ω] of the measurement resistor 32, and the resistance value Ra [Ω] of the voltage dividing resistor 37 when the second closed circuit 102 is configured based on Equation 6.

[0070] In addition, in the measurement error detection process according to the second form, when the second closed circuit 102 is configured, the second voltage measurement unit 33 obtains a first measurement value Vin21 [V] of the inter-terminal voltage of the measurement resistor 32 when a first DC voltage Ve1 [V] from the DC power supply 200 is applied, and obtains a second measurement value Vin22 [V] of the inter-terminal voltage of the measurement resistor 32 when a second DC voltage Ve2 [V] from the DC power supply 200 is applied.

[0071] By solving the linear equations with two unknowns in Equation 5 and Equation 7, the gain error a shown in Equation 8 and the offset error b [V] shown in Equation 9 can be obtained.

[0072]

number

[0073]

number

[0074] In the measurement error detection process according to the second embodiment, the error detection unit 17 detects a gain error a, which is a measurement error, based on Equation 8, and detects an offset error b [V], which is a measurement error, based on Equation 9, using the first measured value Vin21 [V] of the terminal voltage of the measurement resistor 32 and the second measured value Vin22 [V] of the terminal voltage of the measurement resistor 32 acquired by the second voltage measurement unit 33, and the first estimated value Vin11 [V] of the terminal voltage of the measurement resistor 32 and the second estimated value Vin12 [V] of the terminal voltage of the measurement resistor 32 calculated by the voltage estimation unit 16. The gain error a and offset error b [V], which are measurement errors for the second voltage measurement unit 33, detected by the error detection unit 17, are stored in the storage unit 18.

[0075] FIG. 5 is a flowchart showing an operational flow of a measurement error detection process according to the second mode in the motor drive device according to an embodiment of the present disclosure.

[0076] In the measurement error detection process according to the second embodiment, first, in step S201, the control unit 30 controls the first switch 11 to an open state and the second switch 31 to an open state. In addition, the control unit 30 controls all switching elements in the motor drive amplifier unit 13 to an off state.

[0077] In step S202, the DC power supply 200 is connected between the negative side DC terminal 41N in the DC input unit 41 and the U-phase AC terminal 42U in the AC output unit 42 to apply a first DC voltage Ve1 [V]. This forms a second closed circuit 102 for error detection that includes the DC power supply 200 that outputs the first DC voltage Ve1 [V] and the measurement resistor 32.

[0078] In step S203, the voltage estimation unit 16 calculates a first estimated value Vin11 [V] of the inter-terminal voltage of the measurement resistor 32 based on Equation 4, using the value Ve1 [V] of the first DC voltage of the DC power supply 200, the resistance value Rb [Ω] of the measurement resistor 32, and the resistance value Ra [Ω] of the voltage dividing resistor 37 when the second closed circuit 102 is configured.

[0079] In step S204, the second voltage measurement unit 33 acquires a first measurement value Vin21 [V] of the inter-terminal voltage of the measurement resistor 32 when the DC power supply 200 forms the second closed circuit 102 that outputs the first DC voltage value Ve1 [V]. Note that steps S203 and S204 may be executed in reverse order.

[0080] In step S205, the DC power supply 200 is connected between the negative side DC terminal 41N in the DC input unit 41 and the U-phase AC terminal 42U in the AC output unit 42 to apply the second DC voltage Ve2 [V]. This forms a second closed circuit 102 for error detection that includes the DC power supply 200 that outputs the second DC voltage Ve2 [V] and the measurement resistor 32.

[0081] In step S206, the voltage estimation unit 16 calculates a second estimated value Vin12 [V] of the inter-terminal voltage of the measurement resistor 32 based on Equation 6, using the second DC voltage value Ve2 [V] of the DC power supply 200, the resistance value Rb [Ω] of the measurement resistor 32, and the resistance value Ra [Ω] of the voltage dividing resistor 37 when the second closed circuit 102 is configured.

[0082] In step S207, the second voltage measurement unit 33 acquires a second measurement value Vin22 [V] of the inter-terminal voltage of the measurement resistor 32 when the DC power supply 200 forms the second closed circuit 102 that outputs the second DC voltage value Ve2 [V]. Note that steps S206 and S207 may be executed in reverse order.

[0083] In step S208, the error detection unit 17 detects a gain error a, which is a measurement error, based on Equation 8, and detects an offset error b [V], which is a measurement error, based on Equation 9, using the first measurement value Vin21 [V] of the inter-terminal voltage of the measurement resistor 32 and the second measurement value Vin22 [V] of the inter-terminal voltage of the measurement resistor 32 acquired by the second voltage measurement unit 33, and the first estimated value Vin11 [V] of the inter-terminal voltage of the measurement resistor 32 and the second estimated value Vin12 [V] of the inter-terminal voltage of the measurement resistor 32 calculated by the voltage estimation unit 16.

[0084] In step S209, the storage unit 18 stores the gain error a and the offset error b [V], which are the measurement errors for the second voltage measurement unit 33 detected by the error detection unit 17. After that, the insulation resistance detection process S300, which will be described later, is started.

[0085] Next, detection of the insulation resistance value Rm [Ω] of the insulation resistor 4 of the motor 3 by the insulation resistance value detection unit 15 will be described in more detail.

[0086] 6 is a diagram illustrating a first closed circuit configured when an insulation resistance value detection process is executed by an insulation resistance value detection unit in a motor drive device according to an embodiment of the present disclosure. In FIG. 6, the control unit 30, the calculation unit 34, the correction value generation unit 35, the correction unit 36, the voltage estimation unit 16, the error detection unit 17, and the erasure unit 19 are not shown.

[0087] In executing the insulation resistance value detection process by the insulation resistance value detection unit 15, first, the first switch 11 is closed, the second switch 31 is open, and all switching elements in the motor drive amplifier unit 13 are turned off to charge the capacitor 22 with power flowing in from the AC power source 2 via the rectifier circuit 21. Once charging of the capacitor 22 is complete, the first switch 11 is opened, the second switch 31 is closed, and all switching elements of the upper and lower arms of the motor drive amplifier unit 13 are turned off to form a first closed circuit 101 for insulation resistance value detection, as indicated by the bold arrow in the figure. In addition, when the motor 3 has already been driven by the motor drive device 1 and then the drive of the motor 3 is stopped, the capacitor 22 is already sufficiently charged. In this case, the "process of charging the capacitor 22 with the power flowing from the AC power source 2 through the rectifier circuit 21" may be omitted, and the first closed circuit 101 may be configured by opening the first switch 11, closing the second switch 31, and turning off all the switching elements of the upper arm and the lower arm of the motor drive amplifier unit 13. FIG. 8 is a circuit diagram showing a portion related to the first closed circuit. In FIG. 8, the second switch 31 in the closed state is not shown. As shown in FIGS. 6 and 8, the first closed circuit 101 includes the capacitor 22, the voltage dividing resistor 38, the second switch 31 in the closed state, the voltage dividing resistor 39, the insulation resistor 4 of the motor coil of the motor 3, the voltage dividing resistor 37, and the measurement resistor 32.

[0088] When the first closed circuit 101 is formed, the leakage current I1 [A] flowing through the first closed circuit 101 can be calculated according to equation 10 from the measurement value (actual value) Vin3 [V] of the terminal voltage of the measurement resistor 32 obtained by the second voltage measurement unit 33 and the resistance value Rb [Ω] of the measurement resistor 32.

[0089]

number

[0090] When the first closed circuit 101 is configured, a circuit equation such as that expressed by Equation 11 is established from the measured value Vdc [V] of the voltage of the power supply unit 12 (the voltage of the capacitor 22) acquired by the first voltage measuring unit 14, the leakage current I1 [A] flowing through the first closed circuit 101, the resistance value Rb [Ω] of the measurement resistor 32, the resistance value Ra [Ω] of the voltage dividing resistor 37, the resistance value Rc [Ω] of the voltage dividing resistor 38, the resistance value Rd [Ω] of the voltage dividing resistor 39, and the insulation resistance value Rm [Ω] for the insulation resistor 4 of the motor 3.

[0091]

number

[0092] Substituting equation 11 into equation 10 and rearranging it gives equation 12.

[0093]

number

[0094] According to the formula 12, the insulation resistance value Rm [Ω] of the insulation resistor 4 of the motor 3 can be calculated. However, the output of the second voltage measurement unit 33 includes measurement errors due to component errors and aging of the second voltage measurement unit 33, the measurement resistor 32, and the voltage dividing resistor 37 constituting the insulation amplifier. Therefore, the calculation unit 34 calculates the insulation resistance value Rm [Ω] of the insulation resistor 4 of the motor 3 based on the measured value Vdc [V] of the voltage of the power supply unit 12 acquired by the first voltage measurement unit 14 when the first closed circuit 101 is configured, the measured value Vin3 [V] of the voltage between the terminals of the measurement resistor 32 acquired by the second voltage measurement unit 33, the measurement error of the second voltage measurement unit 33, and the resistance value Rb [Ω] of the measurement resistor 32. In this calculation, the measured value Vin3 [V] of the voltage between the terminals of the measurement resistor 32 acquired by the second voltage measurement unit 33 is corrected using the measurement error of the second voltage measurement unit 33. Below, we list an insulation resistance value detection process according to a first form corresponding to a first measurement error detection process that detects only the offset error ΔV [V], and an insulation resistance value detection process according to a second form corresponding to a second measurement error detection process that detects the gain error a and the offset error b [V].

[0095] First, the insulation resistance value detection process according to the first embodiment will be described.

[0096] As described with reference to Fig. 3 and Fig. 4, in the measurement error detection process according to the first embodiment, the error detection unit 17 detects an offset error ΔV [V], which is a measurement error, using the measured value Vin2 [V] of the terminal voltage of the measurement resistor 32 acquired by the second voltage measurement unit 33 when the second closed circuit 102 is configured and the estimated value Vin1 [V] of the terminal voltage of the measurement resistor 32 calculated by the voltage estimation unit 16 based on Equation 2. When only the offset error ΔV [V] is considered as the measurement error detected by the measurement error detection process according to the first embodiment, a value "-ΔV [V]" obtained by inverting the polarity of the error ΔV [V] is used as a correction value Vamend1 [V] for correcting the measured value Vin3 [V] of the terminal voltage of the measurement resistor 32 acquired by the second voltage measurement unit 33 when the first closed circuit 101 is configured. The correction value Vamend1 [V] is expressed as Equation 13 using the offset error ΔV [V].

[0097]

number

[0098] The correction value generating section 35 generates a correction value Vamend[V] based on Equation 13, using the offset error ΔV[V] detected by the measurement error detection process according to the first embodiment.

[0099] When the first closed circuit 101 is constructed, a correction value Vamend1 [V] for canceling out the offset error ΔV [V] is added (plused) to the measurement value Vin3 [V] of the terminal voltage of the measurement resistor 32 acquired by the second voltage measurement unit 33, thereby obtaining the corrected measurement value Vin41 [V] of the terminal voltage of the measurement resistor 32, as shown in Equation 14.

[0100]

number

[0101] Based on Equation 14, the correction unit 36 ​​corrects the measurement value Vin3 [V] of the inter-terminal voltage of the measurement resistor 32 obtained by the second voltage measurement unit 33 when the first closed circuit 101 is constructed, using the correction value Vamend1 [V] generated by the correction value generation unit 35, to generate a corrected measurement value Vin41 [V] of the inter-terminal voltage of the measurement resistor 32.

[0102] In the insulation resistance value detection process according to the first form, the calculation unit 34 calculates the insulation resistance value Rm [Ω] for the insulation resistor 4 of the motor 3 based on Equation 15 obtained by replacing the measurement value Vin3 [V] of the terminal voltage of the measurement resistor 32 in Equation 12 with the corrected measurement value Vin41 [V] of the terminal voltage of the measurement resistor 32.

[0103]

number

[0104] Here, we will explain, using numerical examples, the effect that the offset error ΔV [V] caused by component errors and deterioration over time of the second voltage measurement unit 33, the measurement resistor 32, and the voltage dividing resistor 37 that constitute the isolation amplifier has on the detection accuracy of the insulation resistance value Rm [Ω] of the motor 3.

[0105] For example, consider a numerical example in which the resistance value Rc of voltage-dividing resistor 38 is 1000 kΩ, the resistance value Rd of voltage-dividing resistor 39 is 5 kΩ, the resistance value Rb of measurement resistor 32 is 5 kΩ, the resistance value Ra of voltage-dividing resistor 37 is 1000 kΩ, and the voltage Vdc of power supply unit 12 (voltage of capacitor 22) is 300 V.

[0106] If the actual insulation resistance value Rm of the motor 3 is 1 MΩ, the terminal voltage of the measurement resistor 32 is calculated to be 498 mV using Equation 12 based on the first closed circuit 101. If the measured value Vin3 of the terminal voltage of the measurement resistor 32 acquired by the second voltage measurement unit 33, which is 498 mV, contains an offset error ΔV of 10 mV, the correct measured value Vin3 of the terminal voltage of the measurement resistor 32 should be 488 mV. Therefore, if Vin3 = 488 mV is substituted into Equation 12 and the insulation resistance value Rm of the motor 3 is recalculated to be 1.06 MΩ, which is deviated from the actual insulation resistance value Rm = 1 MΩ of the motor 3.

[0107] If the actual insulation resistance value Rm of the motor 3 is 10 MΩ, the terminal voltage of the measurement resistor 32 is calculated to be 125 mV using Equation 12 based on the first closed circuit 101. If the measured value Vin3 of the terminal voltage of the measurement resistor 32 acquired by the second voltage measurement unit 33, which is 125 mV, contains an offset error ΔV of 10 mV, the correct measured value Vin3 of the terminal voltage of the measurement resistor 32 should be 115 mV. Therefore, if Vin12=115 mV is substituted into Equation 12 and the insulation resistance value Rm of the motor 3 is recalculated to be 11.03 MΩ, which is deviated from the actual insulation resistance value Rm=10 MΩ of the motor 3.

[0108] If the actual insulation resistance value Rm of the motor 3 is 50 MΩ, the terminal voltage of the measurement resistor 32 is calculated to be 29 mV using Equation 12 based on the first closed circuit 101. If the measured value Vin3 of the terminal voltage of the measurement resistor 32 acquired by the second voltage measurement unit 33, which is 29 mV, contains an offset error ΔV of 10 mV, the correct measured value Vin3 of the terminal voltage of the measurement resistor 32 should be 19 mV. Therefore, if Vin3 = 19 mV is substituted into Equation 12 and the insulation resistance value Rm of the motor 3 is recalculated, the result becomes 76.94 MΩ, which is deviated from the actual insulation resistance value Rm = 50 MΩ of the motor 3.

[0109] As the above-mentioned numerical example shows, the larger the actual insulation resistance value Rm [Ω] of the motor 3, the larger the error will be in the insulation resistance value of the motor 3 calculated in a state where the offset error ΔV remains included in the measured value Vin3 of the voltage between the terminals of the measurement resistor 32 acquired by the second voltage measurement unit 33 when the first closed circuit 101 is configured. According to the insulation resistance value detection process of the first embodiment, the measured value Vin3 [V] of the voltage between the terminals of the measurement resistor 32 acquired by the second voltage measurement unit 33 is corrected using the value "-ΔV [V]" obtained by inverting the polarity of the offset error ΔV [V] as the correction value Vamend1 [V], and the insulation resistance value Rm [Ω] is calculated using the corrected measured value Vin41 [V] of the voltage between the terminals of the measurement resistor 32, so that the insulation resistance value Rm [Ω] of the motor 3 can be accurately detected.

[0110] Next, the insulation resistance value detection process according to the second embodiment will be described.

[0111] As described with reference to Figures 3 and 5, in the measurement error detection process according to the second form, the error detection unit 17 detects the gain error a, which is a measurement error, based on Equation 8, and detects the offset error b [V], which is a measurement error, based on Equation 9, using the first measured value Vin21 [V] of the terminal voltage of the measurement resistor 32 and the second measured value Vin22 [V] of the terminal voltage of the measurement resistor 32 acquired by the second voltage measurement unit 33, and the first estimated value Vin11 [V] of the terminal voltage of the measurement resistor 32 and the second estimated value Vin12 [V] of the terminal voltage of the measurement resistor 32 calculated by the voltage estimation unit 16. When taking into account the gain error a and offset error b [V] as the measurement errors detected by the measurement error detection process in the second form, a correction equation such as that shown in Equation 16 is used to correct the measurement value Vin3 [V] of the inter-terminal voltage of the measurement resistor 32 acquired by the second voltage measurement unit 33 when the first closed circuit 101 is constructed, to generate a corrected measurement value Vin42 [V] of the inter-terminal voltage of the measurement resistor 32.

[0112]

number

[0113] The correction value generating unit 35 generates a correction value (i.e., the correction equation shown in Equation 16) based on Equation 16, using the gain error a and offset error b [V] detected by the measurement error detection process according to the second embodiment.

[0114] The correction unit 36 ​​corrects the measurement value Vin3 [V] of the inter-terminal voltage of the measurement resistor 32 acquired by the second voltage measurement unit 33 when the first closed circuit 101 is constructed, using the correction equation shown in equation 16 generated by the correction value generation unit 35, to generate a corrected measurement value Vin42 [V] of the inter-terminal voltage of the measurement resistor 32.

[0115] In the insulation resistance value detection process according to the second form, the calculation unit 34 calculates the insulation resistance value Rm [Ω] for the insulation resistor 4 of the motor 3 based on Equation 17 obtained by replacing the measurement value Vin3 [V] of the terminal voltage of the measurement resistor 32 in Equation 12 with the corrected measurement value Vin42 [V] of the terminal voltage of the measurement resistor 32.

[0116]

number

[0117] Here, examples of numerical values ​​of the gain error a and the offset error b [V] calculated by the correction value generating unit 35 based on Equation 16 will be illustrated.

[0118] For example, consider a numerical example in which the resistance value Rc of voltage dividing resistor 38 is 1000 kΩ, the resistance value Rd of voltage dividing resistor 39 is 5 kΩ, the resistance value Rb of measurement resistor 32 is 5 kΩ, the resistance value Ra of voltage dividing resistor 37 is 1000 kΩ, the first measurement value V22 of measurement resistor 32 when DC power supply 200 outputs a first DC voltage of 100 V is 511 mV, and the second measurement value V22 of measurement resistor 32 when DC power supply 200 outputs a second DC voltage of 90 V is 460 mV.

[0119] When the DC power supply 200 outputs a first DC voltage value of 100 V, the first estimated value V12 of the measurement resistor 32 is 498 mV according to Equation 6. When the DC power supply 200 outputs a second DC voltage value of 90 V, the second estimated value V12 of the measurement resistor 32 is 448 mV according to Equation 6. Substituting these numerical values ​​into Equations 8 and 9, the gain error a becomes 1.02 and the offset error b becomes 3 mV.

[0120] In addition, since the measurement error for the second voltage measurement unit 33 is dominated by offset error rather than gain error, the insulation resistance value Rm [Ω] of the motor 3 can be detected with high accuracy even in the insulation resistance value detection process according to the first form that takes into account only the offset error, but the insulation resistance value Rm [Ω] of the motor 3 can be detected with even higher accuracy according to the insulation resistance value detection process according to the second form that takes into account both the gain error and the offset error.

[0121] Fig. 7 is a flowchart showing an operation flow of an insulation resistance value detection process by an insulation resistance value detection unit in a motor drive device according to an embodiment of the present disclosure. The flowchart shown in Fig. 7 is applicable to both the first insulation resistance value detection process and the second insulation resistance value detection process. Before starting the insulation resistance value detection process in step S300, the measurement error detection process according to the first mode shown in Fig. 4 or the measurement error detection process according to the second mode shown in Fig. 5 is completed, thereby storing the measurement error in the storage unit 18.

[0122] In step S301, the correction value generating unit 35 reads out the stored measurement error from the storage unit 18.

[0123] In step S302, the correction value generating unit 35 generates a correction value based on the measurement error.

[0124] In step S303, the control unit 30 controls the first switch 11 to a closed state and the second switch 31 to an open state. The control unit 30 also controls all switching elements in the motor drive amplifier unit 13 to an off state. As a result, in step S304, the capacitor 22 is charged with power flowing from the AC power source 2 via the rectifier circuit 21. The charge state of the capacitor 22 is monitored by the control unit 30 via the first voltage measurement unit 14. Note that in a state in which the motor 3 has already been driven by the motor drive device 1 and the drive of the motor 3 is then stopped, the capacitor 22 is sufficiently charged, and in this case, step S304 may be omitted.

[0125] When charging of the capacitor 22 is completed, in step S305, the control unit 30 controls the first switch 11 to an open state and the second switch 31 to a closed state. Also, all of the switching elements of the upper arm and the lower arm of the motor drive amplifier unit 13 are turned off. As a result, a first closed circuit 101 for detecting an insulation resistance value is formed.

[0126] In step S306, the first voltage measuring unit 14 obtains a measurement value of the voltage of the power supply unit 12 (the voltage of the capacitor 22).

[0127] In step S307, the second voltage measuring unit 33 acquires a measured value Vin3 [V] of the inter-terminal voltage of the measuring resistor 32 when the first closed circuit 101 is configured.

[0128] In step S308, the correction unit 36 ​​corrects the measurement value Vin3 [V] of the inter-terminal voltage of the measurement resistor 32 acquired by the second voltage measurement unit 33 when the first closed circuit 101 is configured, using the correction value generated by the correction value generation unit 35, to generate a corrected measurement value of the inter-terminal voltage of the measurement resistor 32. When only the offset error ΔV [V] is detected by the measurement error detection process according to the first form shown in FIG. 4, the correction unit 36 ​​corrects the measurement value Vin3 [V] of the inter-terminal voltage of the measurement resistor 32 acquired by the second voltage measurement unit 33 when the first closed circuit 101 is configured, using the correction value Vamend1 [V] generated by the correction value generation unit 35 based on Equation 14, to generate a corrected measurement value Vin41 [V] of the inter-terminal voltage of the measurement resistor 32. When both the gain error a and the offset error b [V] are detected by the measurement error detection process of the second form shown in Figure 5, the correction unit 36 ​​corrects the measurement value Vin3 [V] of the inter-terminal voltage of the measurement resistor 32 acquired by the second voltage measurement unit 33 when the first closed circuit 101 is constructed, using the correction equation shown in Equation 16 generated by the correction value generation unit 35, thereby generating a corrected measurement value Vin42 [V] of the inter-terminal voltage of the measurement resistor 32.

[0129] In step S309, when the first closed circuit 101 is configured, the calculation unit 34 calculates the insulation resistance value Rm [Ω] of the insulation resistance 4 of the motor 3 based on the measured value of the voltage of the power supply unit 12 acquired by the first voltage measurement unit 14, the corrected measured value of the voltage between the terminals of the measurement resistor 32 generated by the correction unit 36, and the resistance value of the measurement resistor 32. More specifically, in the insulation resistance value detection process according to the first form, the calculation unit 34 calculates the insulation resistance value Rm [Ω] of the insulation resistance 4 of the motor 3 based on Equation 15. The calculation unit 34 calculates the insulation resistance value Rm [Ω] of the insulation resistance 4 of the motor 3 based on Equation 17.

[0130] Next, a description will be given of a specific example of the motor drive amplifier section 13. An example of the motor drive amplifier section 13 is a servo amplifier.

[0131] Fig. 9 is a perspective view illustrating a servo amplifier that is a motor drive amplifier section in a motor drive device according to an embodiment of the present disclosure. Fig. 10 is a front view illustrating a servo amplifier that is a motor drive amplifier section in a motor drive device according to an embodiment of the present disclosure. Fig. 11 is an exploded perspective view illustrating a servo amplifier that is a motor drive amplifier section in a motor drive device according to an embodiment of the present disclosure. Fig. 12 is a schematic diagram illustrating a first board and a second board in a servo amplifier that is a motor drive amplifier section in a motor drive device according to an embodiment of the present disclosure.

[0132] The housing of the servo amplifier, which is the motor drive amplifier unit 13, is provided with a DC input unit 41 and an AC output unit 42. The DC input unit 41 has a positive DC terminal 41P and a negative DC terminal 41N. The AC output unit 42 has a U-phase AC terminal 42U, a V-phase AC terminal 42V, and a W-phase AC terminal 42W. Since the housing of the servo amplifier is provided with the DC input unit 41 and the AC output unit 42, it is easy to connect a DC power supply 200 from outside. For example, during shipping tests or maintenance of the motor drive device 1, the DC power supply 200 can be connected to perform measurement error detection processing. In addition, an EEPROM (registered trademark) is provided in the servo amplifier, which is the motor drive amplifier unit 13, and this may be used as the storage unit 18.

[0133] In addition, a plurality of boards on which various parts, a processor, and wiring are mounted are provided in the servo amplifier, which is the motor drive amplifier unit 13. Conventionally, when any failure occurs in the motor drive amplifier unit 13, only the failed board is replaced, and the other boards are reused. In one embodiment of the present disclosure, among the plurality of boards provided in the servo amplifier, which is the motor drive amplifier unit 13, a first board 51 as a power PCB is provided with a main circuit of the inverter, a processor in which an insulation resistance value detection unit 15 and an erasure unit 19 are constructed, and a storage unit 18. In addition, a second board 52 as a control PCB is provided with a processor in which an error detection unit 17 and a voltage estimation unit 16 are constructed. The first board and the second board are electrically and mechanically connected to each other so as to be detachable via a connector 53A provided on the first board 51 and a connector 53B provided on the second board 52.

[0134] For example, when replacing a part other than the first board 51 due to a malfunction or the like, the error factor of the second voltage measurement unit 33 in the insulation resistance value detection unit 15 mounted on the first board does not change, but since the memory unit 18 in which the measurement error is stored is mounted on the first board 51, the measurement error stored in the memory unit 18 can continue to be used as is for the insulation resistance value detection process. Therefore, since it is not necessary to remeasure the measurement error of the second voltage measurement unit 33, the burden on the worker is reduced, and high-precision insulation resistance value detection process can be achieved easily in a short time.

[0135] On the other hand, when replacing parts of the first board 51, particularly those related to the insulation resistance value detection unit 15, for example, in response to a failure, the measurement error stored in the memory unit 18 cannot be used for the insulation resistance value detection process using the replaced insulation resistance value detection unit 15. In this case, for example, an operator operates the erasing unit 19 via an input device or the like to erase the measurement error stored in the memory unit 18. Then, the measurement error detection process is executed again for the replaced insulation resistance value detection unit 15, and the measurement error for the second voltage measurement unit 33 in the replaced insulation resistance value detection unit 15 is detected and stored in the memory unit 18. This makes it possible to realize the subsequent insulation resistance value detection process again with high accuracy.

[0136] As described above, according to the motor drive device 1 according to an embodiment of the present disclosure, the insulation resistance value Rm [Ω] of the motor 3 is calculated based on measurement errors caused by component errors and aging of the second voltage measurement unit 33, the measurement resistor 32, and the voltage dividing resistor 37, and therefore it is possible to accurately detect the insulation resistance value Rm [Ω] of the motor 3. Furthermore, the magnitude of the DC voltage output by the DC power supply 200 only needs to be large enough to allow the measurement error of the second voltage measurement unit 33 to be measured, and since no high voltage is applied to the motor power line, it is safe. [Explanation of symbols]

[0137] 1 Motor drive unit 2 AC power supply 3 Motor 4. Insulation resistance 11 First Switch 12 Power supply section 13 Motor drive amplifier section 14 First voltage measuring unit 15 Insulation resistance detector 16 Voltage Estimation Unit 17 Error detection section 18 Memory section 19 Erasing Section 21 Rectifier circuit 22 Capacitor 30 Control section 31 Second Switch 32 Measuring resistance 33 Second voltage measurement section 34 Calculation section 35 Correction value generator 36 Correction section 37, 38, 39 Voltage divider resistor 41 DC input section 41P Positive DC terminal 41N Negative DC terminal 42 AC output section 42U U-phase AC terminal 42V V-phase AC terminal 42W W phase AC terminal 51 First Substrate 52 Second Board 53A, 53B Connectors 101 First Closed Circuit 102 Second Closed Circuit 200 DC power supply

Claims

1. a first switch for opening and closing an electric path from an AC power source; a power supply unit that rectifies an AC voltage supplied from the AC power supply through the first switch in a closed state into a DC voltage using a rectifier circuit, smoothes the rectified DC voltage using a capacitor, and outputs the smoothed DC voltage; a motor drive amplifier section that converts a DC voltage input from the power supply section via a DC input section into an AC voltage for driving a motor using switching elements of upper and lower arms and supplies the AC voltage to the motor via an AC output section; a first voltage measurement unit that acquires a measurement value of the voltage of the power supply unit; an insulation resistance value detection unit having: a second switch that connects one end of the capacitor to the ground when in a closed state and does not connect one end of the capacitor to the ground when in an open state; a measurement resistor provided between one terminal in the DC input unit to which the other end of the capacitor is connected and one terminal in the AC output unit to which a motor coil of the motor is connected; a second voltage measurement unit that obtains a measured value of a voltage between the terminals of the measurement resistor; and a calculation unit that calculates an insulation resistance value of the motor using at least the measured value of the voltage between the terminals of the measurement resistor obtained by the second voltage measurement unit; a voltage estimation unit that calculates an estimate of a voltage between the terminals of the measurement resistor based on a value of a DC voltage from the DC power supply and a resistance value of the measurement resistor when a second closed circuit including the DC power supply and the measurement resistor is formed by applying a DC voltage from a DC power supply different from the power supply unit between the one terminal in the DC input unit and the one terminal in the AC output unit and opening the first switch and the second switch to an off state and turning off the switching element of the motor drive amplifier unit; an error detection unit that detects a measurement error of the second voltage measurement unit by using a measured value of the inter-terminal voltage of the measurement resistor acquired by the second voltage measurement unit when the second closed circuit is configured and an estimated value of the inter-terminal voltage of the measurement resistor calculated by the voltage estimation unit; Equipped with a measurement value of the insulation resistance of the motor based on the measurement value of the voltage of the power supply unit acquired by the first voltage measurement unit and the measurement value of the voltage between the terminals of the measurement resistor acquired by the second voltage measurement unit when a first closed circuit including the second switch, the capacitor, the measurement resistor, the motor coil, and ground is formed by opening the first switch and closing the second switch, the measurement error, and the resistance value of the measurement resistor.

2. The insulation resistance value detection unit includes: a correction value generating unit that generates a correction value based on the measurement error; a correction unit that corrects a measurement value of the inter-terminal voltage of the measurement resistor obtained by the second voltage measurement unit when the first closed circuit is configured based on the correction value, and outputs a corrected measurement value of the inter-terminal voltage of the measurement resistor; having 2. The motor drive device according to claim 1, wherein the calculation unit calculates the insulation resistance value of the motor based on a measured value of the voltage of the power supply unit acquired by the first voltage measurement unit when the first closed circuit is configured, a corrected measured value of the inter-terminal voltage of the measurement resistor output from the correction unit, and a resistance value of the measurement resistor.

3. the error detection unit detects an offset error, which is the measurement error, by using a measured value of the inter-terminal voltage of the measurement resistor acquired by the second voltage measurement unit when the second closed circuit is configured and an estimated value of the inter-terminal voltage of the measurement resistor calculated by the voltage estimation unit; The motor drive device according to claim 2 , wherein the correction value generating section generates the correction value based on the offset error.

4. the voltage estimation unit, when the second closed circuit is configured, calculates a first estimate of a voltage between the terminals of the measurement resistor based on a value of a first DC voltage from the DC power supply and a resistance value of the measurement resistor, and calculates a second estimate of the voltage between the terminals of the measurement resistor based on a value of a second DC voltage from the DC power supply different from the value of the first DC voltage and the resistance value of the measurement resistor; the second voltage measurement unit, when the second closed circuit is configured, obtains a first measured value of a voltage between the terminals of the measurement resistor when the first DC voltage from the DC power source is applied, and obtains a second measured value of a voltage between the terminals of the measurement resistor when the second DC voltage from the DC power source is applied, the error detection unit detects an offset error and a gain error, which are the measurement errors, using a first measured value of the inter-terminal voltage of the measurement resistor and a second measured value of the inter-terminal voltage of the measurement resistor acquired by the second voltage measurement unit, and a first estimated value of the inter-terminal voltage of the measurement resistor and a second estimated value of the inter-terminal voltage of the measurement resistor calculated by the voltage estimation unit; The motor drive device according to claim 2 , wherein the correction value generating section generates the correction value based on the offset error and the gain error.

5. a storage unit that stores the measurement error detected by the error detection unit, The motor drive device according to claim 2 , wherein the correction value generating section generates the correction value based on the measurement error stored in the storage section.

6. a first substrate on which at least the insulation resistance value detector and the memory unit are provided; a second substrate that is electrically and mechanically detachably connected to the first substrate and that has at least the error detection unit provided thereon; The motor drive device according to claim 5 .

7. 7. The motor drive device according to claim 6, further comprising an erasing unit that erases the measurement error stored in the memory unit.

8. 8. The motor drive device according to claim 1, wherein the DC power supply is electrically and detachably connected to the one terminal in the DC input section and the one terminal in the AC output section.

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