Motor drive device that calculates insulation resistance value of motor

Abstract

The motor drive device includes an insulation resistance value detection unit that calculates an insulation resistance value of the motor based on a measured value of a voltage of a smoothing capacitor provided between a rectifier circuit and an inverter, a measured value of a voltage between terminals of a measurement resistor, a measurement error calculated based on a measured value and an estimated value of a voltage between terminals of the measurement resistor in a state in which a direct-current power supply is connected externally, and a resistance value of the measurement resistor.

Description

Technical Field

[0001] This invention relates to a motor drive device for calculating the insulation resistance value of a motor. Background Technology

[0002] In servo motors installed in machine tools, the insulation resistance (insulation resistance value) of the motor coil (winding) to ground decreases due to oil intrusion over time. When the insulation resistance of the motor coil decreases, leakage current flows in the closed circuit formed by the motor, motor drive, and ground. In addition to the normal motor drive current, leakage current also flows in the motor drive, causing the servo amplifier to perform overcurrent detection or the circuit breaker at the input stage to trip. As a result, the machine tool equipped with the motor experiences an emergency stop. When such an emergency stop occurs, the machine tool may be stopped for an extended period to determine the cause, reducing efficiency. Therefore, measuring the insulation resistance value of the motor is essential for the operation of the motor drive.

[0003] For example, a method for detecting insulation resistance degradation in a motor is known, wherein the motor is driven by a motor drive device, the motor drive device comprising: a power supply unit that rectifies power supplied from an AC power source via a switch through a rectifier circuit and smooths it through a capacitor; and a motor drive amplifier that converts DC voltage from the power supply unit into AC voltage to drive the motor. The method for detecting insulation resistance degradation in this motor is characterized in that, after the switch is turned off to stop the motor operation, one end of the capacitor is connected to ground and the other end of the capacitor is connected to the motor coil, and the current flowing through the closed circuit formed by the capacitor, the motor coil, and ground is detected to detect insulation resistance degradation in the motor (see, for example, Patent Document 1).

[0004] For example, a known motor drive device includes a fault detection function for a motor insulation resistance degradation detection unit. The motor drive device is characterized by comprising: a power supply unit that rectifies an AC voltage supplied from an AC power source via a switch into a DC voltage using a rectifier circuit, and smooths the rectified DC voltage using a capacitor; a motor drive amplifier unit that uses upper and lower bridge arm switching elements to convert the DC voltage from the power supply unit into an AC voltage to drive the motor; a power supply voltage measuring unit that measures the voltage of the power supply unit; and an insulation resistance degradation detection unit that includes a contact portion for connecting one end of the capacitor to ground and a contact portion provided between the other end of the capacitor and the motor coil. The insulation resistance degradation detection unit sets the switch to the open state and the contact portion to the closed state, and detects whether the insulation resistance of the motor has deteriorated based on the detection signal obtained by the current detection unit from the closed circuit formed by the contact portion, the capacitor, the motor coil, and the ground; and the fault detection unit sets the contact portion from the closed state to the open state, and arbitrarily switches the switching element of the upper arm or the lower arm of the motor drive amplifier section, and detects whether the insulation resistance degradation detection unit is faulty based on the detection signal in the insulation resistance degradation detection unit and the voltage value measured by the power supply voltage measuring unit (for example, see Patent Document 2).

[0005] For example, a known insulation degradation detection device for motors is a device connected to a motor drive unit for detecting insulation degradation of the motor. The motor drive unit includes a converter section, a smoothing capacitor, and multiple inverter sections. The converter section has a rectifier circuit for rectifying AC power, the smoothing capacitor smooths the output of the rectifier circuit, and the multiple inverter sections convert DC from the converter section into AC to drive multiple motors respectively. The insulation degradation detection device is characterized by comprising: a first switch that, when activated during insulation degradation detection, grounds one end of the smoothing capacitor; a voltage detection unit that measures the voltage across the smoothing capacitor; multiple second switches that, when activated during insulation degradation detection, connect the other end of the smoothing capacitor to the windings of the multiple motors respectively; and multiple current detection units that detect the current flowing through the insulation resistance of each of the multiple motors when the first switch and the multiple second switches are activated. The discharge current of the smoothing capacitor; and multiple insulation resistance calculation units, which calculate the insulation resistance of each of the multiple motors based on the voltage detected by the voltage detection unit and the current detected by each of the multiple current detection units. In the motor insulation degradation detection device, the first switch and the voltage detection unit are disposed in the converter unit, and the multiple second switches, the multiple current detection units, and the multiple insulation resistance calculation units are respectively disposed in the multiple inverter units. The motor insulation degradation detection device also includes a communication unit, which transmits the voltage value detected by the voltage detection unit and a signal for notifying the timing of turning on the first switch from the converter unit to the multiple inverter units. In each of the multiple inverter units, the connection made by the second switch, the current detection made by the current detection unit, and the insulation resistance calculation made by the insulation resistance calculation unit are performed simultaneously at the same time (for example, see Patent Document 3).

[0006] For example, a known motor drive device is characterized by comprising: a rectifier circuit that rectifies an AC voltage supplied from an AC power source via a first switch into a DC voltage; a power supply unit that smooths the DC voltage obtained by the rectifier circuit through a capacitor; an inverter unit that converts the smoothed DC voltage obtained by the power supply unit into an AC voltage to drive the motor by switching an element of a semiconductor switch; a current detection unit that measures the current flowing through a resistor, one end of which is connected to the coil of the motor, and the other end of which is connected to one terminal of a capacitor; a voltage detection unit that measures the voltage across the capacitor; a second switch that grounds the other terminal of the capacitor; and an insulation resistance detection unit that uses a set of current and voltage values ​​measured when the motor is stopped, the first switch is turned off, and the second switch is turned off, and a set of current and voltage values ​​measured when the motor is stopped, the first switch is turned off, and the second switch is turned on, to detect the resistance between the motor coil and ground, i.e., the insulation resistance of the motor (see, for example, Patent Document 4).

[0007] For example, a known motor control device includes a first power supply unit, a first switch, a DC supply unit, a capacitor, and a switching element. The first switch is capable of disconnecting the power supply from the first power supply unit. The DC supply unit outputs power from the first power supply unit to a bus. The capacitor is connected to the bus. The switching element converts the DC power supplied to the bus into AC power to drive and control the motor. The motor control device is characterized by further comprising: a second power supply unit, one end of which is connected to the bus, and the other end which is grounded via the second switch; a current detection unit that detects the current value between the motor windings and the bus connected to the second power supply unit; and an insulation resistance calculation unit that calculates the insulation resistance value of the motor based on the current value detected by the current detection unit when the power supply is disconnected by the first switch and when the second switch is open and closed, the voltage value of the capacitor, and the voltage value of the second power supply unit (for example, see Patent Document 5).

[0008] Existing technical documents

[0009] Patent documents

[0010] Patent Document 1: Japanese Patent No. 4554501

[0011] Patent Document 2: Japanese Patent No. 5832578

[0012] Patent Document 3: Japanese Patent No. 4565036

[0013] Patent Document 4: Japanese Patent No. 5788538

[0014] Patent Document 5: Japanese Patent Application Publication No. 2021-018163 Summary of the Invention

[0015] The problem the invention aims to solve

[0016] Eliminating errors caused by components within the insulation resistance detection circuit is crucial for accurately measuring insulation resistance values. Furthermore, minimizing the operator's workload during insulation resistance testing is also desirable. Therefore, for motor drive devices, a technology that allows for high-precision and easy measurement of the motor's insulation resistance is desired.

[0017] Solution for solving the problem

[0018] According to one aspect of this disclosure, a motor drive device includes: a first switch for opening and closing a circuit from an AC power source; a power supply unit that rectifies the AC voltage supplied from the AC power source via the closed first switch into a DC voltage using a rectifier circuit, and smooths the rectified DC voltage using a capacitor before outputting it; a motor drive amplifier unit that uses switching elements of the upper and lower bridge arms to convert the DC voltage input from the power supply unit via a DC input unit into an AC voltage for motor drive, and supplies the AC voltage to the motor via an AC output unit; and a first voltage measuring unit that acquires... The power supply section measures the voltage; the insulation resistance detection section includes a second switch, a measuring resistor, a second voltage measuring unit, and a calculation unit. When the second switch is closed, one end of a capacitor is connected to ground; when open, one end of the capacitor is not connected to ground. The measuring resistor is located between a terminal in the DC input section connected to the other end of the capacitor and a terminal in the AC output section connected to the motor coil of the motor. The second voltage measuring unit acquires the measured value of the voltage between the terminals of the measuring resistor. The calculation unit uses at least the measured value of the voltage between the terminals of the measuring resistor acquired by the second voltage measuring unit. The system calculates the insulation resistance value of the motor; a voltage estimation unit, when a second closed circuit including a DC power supply and a measuring resistor is formed by applying a DC voltage from a DC power supply different from the power supply to a terminal in the DC input section and a terminal in the AC output section, setting the first and second switches to the open state and setting the switching element of the motor drive amplifier section to the open state, calculates an estimated value of the voltage between the terminals of the measuring resistor based on the value of the DC voltage from the DC power supply and the resistance value of the measuring resistor; and an error detection unit, which uses the voltage obtained by the second voltage measuring unit when the second closed circuit is formed. The measurement error of the second voltage measuring unit is detected by measuring the voltage between the terminals of the measuring resistor and estimating the voltage between the terminals of the measuring resistor calculated by the voltage estimation unit. The calculation unit calculates the insulation resistance value of the motor based on the voltage of the power supply obtained by the first voltage measuring unit when a first closed circuit including the second switch, capacitor, measuring resistor, motor coil and ground is formed by setting the first switch to the open state and the second switch to the closed state, the voltage between the terminals of the measuring resistor obtained by the second voltage measuring unit, the measurement error, and the resistance value of the measuring resistor.

[0019] The effects of the invention

[0020] According to one aspect of this disclosure, a motor drive device is capable of accurately and easily detecting the insulation resistance value of a motor. Attached Figure Description

[0021] Figure 1This is a diagram illustrating a motor drive device based on one embodiment of the present disclosure.

[0022] Figure 2 This diagram illustrates the DC power supply connected when detecting the measurement error of the second voltage measuring unit in a motor drive device based on one embodiment of the present disclosure.

[0023] Figure 3 This is a diagram illustrating a second closed circuit configured in a motor drive device based on an embodiment of the present disclosure when detecting the measurement error of the second voltage measuring unit.

[0024] Figure 4 This is a flowchart illustrating the operation flow of measurement error detection processing based on a first method in a motor drive device according to one embodiment of the present disclosure.

[0025] Figure 5 This is a flowchart illustrating the operation flow of a measurement error detection process based on a second method in a motor drive device according to one embodiment of the present disclosure.

[0026] Figure 6 This diagram illustrates a first closed circuit formed when an insulation resistance value detection process performed by an insulation resistance value detection unit is executed in a motor drive device based on an embodiment of the present disclosure.

[0027] Figure 7 This is a flowchart illustrating the operation flow of the insulation resistance value detection process performed by the insulation resistance value detection unit in a motor drive device based on an embodiment of the present disclosure.

[0028] Figure 8 The diagram of the second switch 31 in the closed state is omitted.

[0029] Figure 9 This is a perspective view illustrating a servo amplifier, which is a motor drive amplifier section, within a motor drive device based on one embodiment of the present disclosure.

[0030] Figure 10 This is a front view illustrating a servo amplifier, which is a motor drive amplifier section, within a motor drive device based on one embodiment of the present disclosure.

[0031] Figure 11 This is an exploded perspective view illustrating a servo amplifier, which is a motor drive amplifier section, within a motor drive device according to one embodiment of the present disclosure.

[0032] Figure 12 This is a schematic diagram illustrating the first and second substrates within a servo amplifier that serves as a motor drive amplifier section in a motor drive device based on an embodiment of the present disclosure. Detailed Implementation

[0033] The motor drive device for calculating the insulation resistance value of the motor will now be described with reference to the accompanying drawings. In all the drawings, the same reference numerals are used to label the same components. Furthermore, the scales in these drawings have been appropriately changed for ease of understanding. Also, the arrangement shown in the drawings is an example for implementation and is not limited to the illustrated arrangement.

[0034] Figure 1 This is a diagram illustrating a motor drive device based on one embodiment of the present disclosure.

[0035] As an example, the illustration shows a motor 3 controlled by a motor drive device 1 connected to an AC power supply 2. Furthermore, in this embodiment, the type of motor 3 is not particularly limited; for example, it can be either an induction motor or a synchronous motor. Additionally, the number of phases of the AC power supply 2 and the motor 3 is not specifically limited to this embodiment; for example, it can be either three-phase or single-phase. Machines equipped with the motor 3 include, for example, machine tools, robots, forging machines, injection molding machines, industrial machinery, various electrified products, trams, automobiles, and airplanes. Furthermore, if we consider an example of the AC power supply 2, there are three-phase AC 400V power supplies, three-phase AC 200V power supplies, three-phase AC 600V power supplies, and single-phase AC 100V power supplies, etc. In the illustrated example, both the AC power supply 2 and the motor 3 are three-phase.

[0036] There is an insulation resistance 4 between the motor coil (winding) of motor 3 and ground. The resistance value of the insulation resistance 4, i.e., the insulation resistance value Rm [Ω], is infinitely large when there is no degradation, and gradually decreases from infinity in the order of several MΩ, hundreds of kΩ, etc. as degradation progresses. According to one embodiment of the present disclosure, the motor drive device 1 has the function of detecting the insulation resistance value Rm [Ω] of motor 3.

[0037] like Figure 1 As shown, a motor drive device 1 based on one embodiment of the present disclosure includes a first switch 11, a power supply unit 12, a motor drive amplifier unit 13, a first voltage measuring unit 14, an insulation resistance value detection unit 15, a voltage estimation unit 16, an error detection unit 17, a storage unit 18, and an erasure unit 19.

[0038] The first switch 11 is used to disconnect and close the circuit between the AC power supply 2 and the rectifier circuit 21 within the power supply unit 12. The disconnection and closure of the circuit via the first switch 11 is controlled, for example, by the control unit 30 within the insulation resistance detection unit 15. Alternatively, it can be controlled by any control unit (not shown) consisting of an arithmetic processing device located outside the insulation resistance detection unit 15. The first switch 11 is, for example, an electromagnetic contactor. The closed state of the circuit from the AC power supply 2 to the rectifier circuit 21 within the power supply unit 12 is achieved by closing the contacts of the first switch 11, which is an electromagnetic contactor; the open state of the circuit from the AC power supply 2 to the rectifier circuit 21 within the power supply unit 12 is achieved by opening the contacts of the first switch 11, which is an electromagnetic contactor. Furthermore, regarding the first switch 11, as long as it can disconnect and close the circuit from the AC power supply 2, it can be replaced by, for example, a relay, a semiconductor switching element, or the like.

[0039] The power supply unit 12 and the motor drive amplifier unit 13 are connected via a DC support. The "DC support" refers to the circuit part 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. It is also called the "DC support section", "DC support", "DC support part" or "DC intermediate circuit", etc.

[0040] The power supply unit 12 has a rectifier circuit 21 and a capacitor 22. The rectifier circuit 21 rectifies the AC voltage supplied from the AC power supply 2 via the first switch 11 which is in the off state into a DC voltage. The capacitor 22 smooths the DC voltage obtained by rectification and outputs it.

[0041] The rectifier circuit 21 within the power supply unit 12 can be any circuit capable of converting AC voltage to DC voltage. Examples include diode rectifier circuits, 120-degree energized rectifier circuits, or PWM switching control rectifier circuits with internal switching elements. The rectifier circuit 21 is configured as a three-phase bridge circuit when the AC power supply 2 is a three-phase AC power supply, and as a single-phase bridge circuit when the AC power supply 2 is a single-phase AC power supply. When the rectifier circuit 21 is a PWM switching control rectifier circuit, it is composed of a bridge circuit consisting of a switching element and a diode connected in reverse parallel with that switching element. Examples of switching elements in this case include IGBTs, thyristors, GTOs (gate turn-off thyristors), and transistors. The type of switching element is not intended to limit this embodiment; other switching elements may also be used.

[0042] The capacitor 22 within the power supply section 12 has the function of smoothing the DC voltage output from the rectifier circuit 21 and also has the function of storing DC power in the DC support. The capacitor 22 is sometimes referred to as a smoothing capacitor or a DC support capacitor. Examples of capacitors 22 include electrolytic capacitors and film capacitors.

[0043] In addition, a first voltage measuring unit 14 is connected to the two terminals of capacitor 22. The first voltage measuring unit 14 is a measuring circuit that acquires the measured value of the voltage applied to capacitor 22, that is, the (DC) voltage of power supply unit 12.

[0044] The motor drive amplifier section 13 has an inverter composed of a bridge circuit. The upper and lower arms of this bridge circuit are equipped with groups consisting of switching elements and diodes connected in reverse parallel to these switching elements. In the illustrated example, the motor 3 is a three-phase AC motor; therefore, the inverter within the motor drive amplifier section 13 is composed of a three-phase bridge circuit. The switching element of the upper arm of phase U is set as S... u1 Set the switching element of the lower bridge arm of phase U to S. u2 Set the switching element of the upper bridge arm of phase V as S. v1 Set the switching element of the lower bridge arm of phase V as S. v2 Set the switching element of the upper bridge arm of phase W as S. w1 Set the switching element of the lower bridge arm of phase W as S. w2 .

[0045] Furthermore, the motor drive amplifier section 13 has a DC input section 41 on the DC support side and an AC output section 42 on the AC motor side. The positive DC terminal 41P of the DC input section 41 is connected to the positive power line of the DC support, and the negative DC terminal 41N of the DC input section 41 is connected to the negative power line of the DC support. The U-phase AC terminal 42U of the AC output section 42 is connected to the U-phase motor power line, the V-phase AC terminal 42V of the AC output section 42 is connected to the V-phase motor power line, and the W-phase AC terminal 42W of the AC output section 42 is connected to the W-phase motor power line. The U-phase motor power line, the V-phase motor power line, and the W-phase motor power line are respectively connected to the U-phase motor coil, the V-phase motor coil, and the W-phase motor coil of the motor 3.

[0046] The motor drive amplifier section 13 performs power conversion operations by switching the upper and lower bridge arms' switching elements on and off according to PWM switching commands from a higher-level control device (not shown). Specifically, the motor drive amplifier section 13 switches the upper and lower bridge arms' switching elements on and off to convert the DC voltage input via the DC input section 41 into an AC voltage for motor drive, and supplies this AC voltage to the motor 3 via the AC output section 42. Furthermore, in one embodiment of this disclosure, the switching elements of the upper and lower bridge arms within the motor drive amplifier section 13 are controlled by the control section 30 of the insulation resistance detection section 15, details of which will be described later.

[0047] The insulation resistance detection unit 15 detects the insulation resistance 4 between the motor coil (winding) of the motor 3 and the ground, i.e., the insulation resistance value Rm [Ω]. The insulation resistance detection unit 15 includes a control unit 30, a second switch 31, a measuring resistor 32, a second voltage measuring unit 33, a calculation unit 34, a correction value generation unit 35, and a correction unit 36. The detection of the insulation resistance 4 of the motor 3, Rm [Ω], performed by the insulation resistance detection unit 15, is conducted using various data obtained with respect to a first closed circuit. This first closed circuit is obtained by setting the first switch 11 to the open state, the second switch 31 to the closed state, and all switching elements within the motor drive amplifier unit 13 to the open state. The first closed circuit includes the second switch 31, the capacitor 22, the measuring resistor 32, the motor coil of the motor 3, and the ground.

[0048] One terminal of the second switch 31 within the insulation resistance detection unit 15 is connected to a voltage divider resistor 38, and the other terminal is connected to a voltage divider resistor 39. One terminal of the voltage divider resistor 38 is connected to the positive power line connecting the rectifier circuit 21 within the power supply unit 12 and the capacitor 22. One terminal of the voltage divider resistor 39 is connected to ground. The second switch 31 controls the grounding switch by its opening and closing; that is, in the closed state, the positive terminal of the capacitor 22 is connected to ground, and in the open state, one end of the capacitor is not connected to ground. The opening and closing of the second switch 31 is controlled by the control unit 30. The second switch 31 may be composed of, for example, a relay, a semiconductor switching element, or an electromagnetic contactor.

[0049] A measuring resistor 32 is positioned between the negative terminal of capacitor 22 and the motor coil of motor 3. More specifically, one terminal of the measuring resistor 32 is connected to the negative terminal of capacitor 22 via the negative DC terminal 41N in the DC input section 41 of motor drive amplifier section 13. The other terminal of the measuring resistor 32 is connected to one of the motor power lines of motor 3, namely the U-phase motor power line, V-phase motor power line, and W-phase motor power line, via a voltage divider resistor 37. In the illustrated example, as an example, the other terminal of the measuring resistor 32 is connected to the U-phase motor power line that connects the U-phase AC terminal 42U in the AC output section 42 of motor drive amplifier section 13 to the U-phase motor coil of motor 3. The second voltage measuring unit 33 is a measuring circuit that obtains the measured value of the voltage between the terminals of the measuring resistor 32. For example, the measuring resistor 32 and the second voltage measuring unit 33 can be configured using an isolation amplifier. The voltage divider resistor 37 is provided to adjust the input voltage to the isolation amplifier to converge within an appropriate range.

[0050] The correction value generation unit 35 generates a correction value based on the measurement error of the second voltage measuring unit 33 detected by the error detection unit 17 (described later). The correction unit 36 ​​uses the correction value generated by the correction value generation unit 35 to correct the measured value of the inter-terminal voltage of the measuring resistor 32 obtained by the second voltage measuring unit 33 when the first closed circuit is formed, thereby generating a corrected measured value of the inter-terminal voltage of the measuring resistor 32. The corrected measured value of the inter-terminal voltage of the measuring resistor 32 generated by the correction unit 36 ​​based on the measurement error of the second voltage measuring unit 33 is used in the calculation of the insulation resistance value Rm [Ω] of the motor 3 performed by the calculation unit 34.

[0051] The calculation unit 34 uses at least the measured value of the inter-terminal voltage of the measuring resistor 32, obtained by the second voltage measuring unit 33 when a first closed circuit is formed, including the second switch 31, capacitor 22, measuring resistor 32, motor coil of motor 3, and ground, to calculate the insulation resistance value of motor 3. That is, the calculation unit 34 calculates the insulation resistance value Rm [Ω] of the insulation resistance 4 of motor 3 based on the measured value of the voltage of power supply unit 12 obtained by the first voltage measuring unit 14 when the first closed circuit is formed, the corrected measured value of the inter-terminal voltage of measuring resistor 32 generated by the correction unit 36, and the resistance value of measuring resistor 32. Details of the insulation resistance value calculation process performed by the calculation unit 34 will be described later.

[0052] The measurement error of the second voltage measuring unit 33 is detected using various data obtained about the second closed circuit. This second closed circuit is obtained by applying a DC voltage from a DC power supply different from the power supply unit 12 between a terminal in the DC input unit 41 (the negative DC terminal 41N in the illustrated example) and a terminal in the AC output unit 42 (the U-phase AC terminal 42U in the illustrated example), setting the first switch 11 and the second switch 31 to the open state, and setting all switching elements of the upper or lower bridge arm of the motor drive amplifier unit 13 to the open state. The second closed circuit is an error detection closed circuit that includes the DC power supply and the measuring resistor 32.

[0053] The voltage estimation unit 16 calculates the estimated value of the voltage between the terminals of the measuring resistor 32 based on the measured value of the voltage of the power supply 12 obtained by applying a DC voltage from a DC power supply different from that of the power supply 12 between a terminal in the DC input unit 41 (in the illustrated example, the negative DC terminal 41N) and a terminal in the AC output unit 42 (in the illustrated example, the U-phase AC terminal 42U). The first switch 11 and the second switch 31 are set to the open state, and all switching elements of the upper or lower bridge arm of the motor drive amplifier unit 13 are set to the open state. This is done according to the circuit equation involving the second closed circuit including the DC power supply and the measuring resistor 32. The estimated value of the voltage between the terminals of the measuring resistor 32 is obtained by the first voltage measuring unit 14.

[0054] The error detection unit 17 detects the error between the measured value of the voltage between the terminals of the measuring resistor 32 obtained by the second voltage measuring unit 33 when the second closed circuit is formed and the estimated value of the voltage between the terminals of the measuring resistor 32 calculated by the voltage estimation unit 16. The measurement error of the second voltage measuring unit 33 detected by the error detection unit 17 is used in the correction value generation process performed by the correction value generation unit 35. Furthermore, it should be noted that the "measured value of the voltage between the terminals of the measuring resistor 32 obtained by the second voltage measuring unit 33" used in the error detection process performed by the error detection unit 17 is not the measured value corrected by the correction unit 36.

[0055] 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 can be constructed of electrically erasable and recordable non-volatile memory such as EEPROM (registered trademark), or high-speed read / write random access memory such as DRAM or SRAM. The measurement error stored in the storage unit 18 is used to generate a correction value by the correction value generation unit 35. Furthermore, the measurement error stored in the storage unit 18 can also be erased by the erasure unit 19 under specified conditions.

[0056] An arithmetic processing unit (processor) is provided within the motor drive unit 1. Examples of such arithmetic processing units include ICs, LSIs, CPUs, MPUs, and DSPs. This arithmetic processing unit includes a first voltage measuring unit 14, a control unit 30, a second voltage measuring 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 is implemented as a functional module, for example, by a computer program executed on the processor. For instance, when the first voltage measuring unit 14, control unit 30, second voltage measuring unit 33, calculation unit 34, correction value generation unit 35, correction unit 36, voltage estimation unit 16, error detection unit 17, and erasure unit 19 are constructed as a computer program, the functions of each unit can be realized by causing the arithmetic processing unit to operate according to the computer program. The computer programs for performing the processes of the first voltage measuring unit 14, control unit 30, second voltage measuring unit 33, calculation unit 34, correction value generation unit 35, correction unit 36, voltage estimation unit 16, error detection unit 17, and erasure unit 19 may also be provided in the form of a computer-readable recording medium such as a semiconductor memory, magnetic recording medium, or optical recording medium. Alternatively, the first voltage measuring unit 14, control unit 30, second voltage measuring unit 33, calculation unit 34, correction value generation unit 35, correction unit 36, voltage estimation unit 16, error detection unit 17, and erasure unit 19 may be implemented using semiconductor integrated circuits in which computer programs for implementing the functions of each unit are written.

[0057] 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), which displays the "insulation resistance value of the motor 3" to the operator. Examples of display units include a separate display device, a display device attached to the motor drive unit 1, a display device attached to a higher-level control device (not shown), and a display device attached to a personal computer or portable terminal. Alternatively, the insulation resistance value of the motor 3 detected by the insulation resistance value detection unit 15 may be sent to an alarm output unit (not shown), which outputs an alarm when the insulation resistance value of the motor 3 is lower than a predetermined value. The alarm output from the alarm output unit may be sent to a light-emitting device (not shown), such as an LED or lamp, which notifies the operator of "deterioration of the insulation resistance 4 of the motor 3" by emitting light upon receiving the alarm. Furthermore, the alarm output from the alarm output unit may be sent to an audio device (not shown), which notifies the operator of "deterioration of the insulation resistance 4 of the motor 3" by emitting a sound, such as a audible sound, speaker, buzzer, or doorbell, upon receiving the alarm. As a result, the operator can reliably and easily grasp the insulation resistance value of motor 3 and the deterioration of the insulation resistance 4 of motor 3, making it easier to replace motor 3 or disassemble and clean motor 3.

[0058] Next, the detection of measurement error in the second voltage measuring unit 33 will be explained in more detail.

[0059] Figure 2 This diagram illustrates the DC power supply connected when detecting the measurement error of the second voltage measuring unit in a motor drive device based on one embodiment of the present disclosure. To detect the measurement error of the second voltage measuring unit 33, as... Figure 2 As shown, a DC power supply 200, different from the power supply unit 12, for applying DC voltage is connected between the negative DC terminal 41N in the DC input section 41 and a terminal in the AC output section 42. Figure 1 and Figure 2In the example shown, the other terminal of the measuring resistor 32 is connected to the U-phase motor power line via the voltage divider resistor 37 and the U-phase AC terminal 42U in the AC output section 42 of the motor drive amplifier section 13. Therefore, the DC power supply 200 is connected between the negative DC terminal 41N in the DC input section 41 and the U-phase AC terminal 42U in the AC output section 42. Furthermore, when the other terminal of the measuring resistor 32 is connected to the V-phase motor power line via the voltage divider resistor 37 and the V-phase AC terminal 42V in the AC output section 42 of the motor drive amplifier section 13, the 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 measuring resistor 32 is connected to the W-phase motor power line via the voltage divider resistor 37 and the W-phase AC terminal 42W in the AC output section 42 of the motor drive amplifier section 13, the 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.

[0060] The DC power supply 200 is electrically connected to a terminal in the DC input section 41 and a terminal in the AC output section 42 of the motor drive amplifier section 13 in a detachable manner, as illustrated in the following example. For instance, an operator may manually connect a portable battery, which serves as the DC power supply 200, between a terminal in the DC input section 41 and a terminal in the AC output section 42 of the motor drive amplifier section 13. Alternatively, a shipping test device equipped with the DC power supply 200 may be prepared in advance, and during the shipping test of the motor drive device 1, the shipping test device may be connected to a terminal in the DC input section 41 and a terminal in the AC output section 42 of the motor drive amplifier section 13. Furthermore, the DC power supply 200 may be configured to be installed in advance, for example, within the main body of the motor drive amplifier section 13 or in a module adjacent to the motor drive amplifier section 13, and the connection between the terminal in the DC input section 41 and the terminal in the AC output section 42 of the motor drive amplifier section 13 and the DC power supply 200 may be switched by operating a switch.

[0061] Figure 3 This diagram illustrates a second closed circuit configured to detect the measurement error of the second voltage measuring unit in a motor drive device based on one embodiment of the present disclosure. Figure 3 The diagrams of the control unit 30, calculation unit 34, correction value generation unit 35, correction unit 36, voltage estimation unit 16, error detection unit 17, and erasure unit 19 are omitted.

[0062] When detecting the measurement error of the second voltage measuring unit 33, a 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. Additionally, the first switch 11 and the second switch 31 are set to the open state, and all switching elements of the upper or lower bridge arm of the motor drive amplifier unit 13 are set to the open state. This constitutes the second closed circuit 102 for detecting the measurement error, as indicated by the thick arrow in the figure.

[0063] With the second closed circuit 102 configured, the voltage between the terminals of the measuring resistor 32 can be estimated by using the DC voltage of the DC power supply 200. When the resistance value of the measuring resistor 32 is set to Rb [Ω], the resistance value of the voltage divider resistor 37 is set to Ra [Ω], and the DC voltage of the DC power supply 200 is set to Ve [V], the estimated value Vin1 [V] of the voltage between the terminals of the measuring resistor 32 with the second closed circuit 102 configured can be obtained based on Equation 1.

[0064] [Number 1]

[0065]

[0066] The voltage estimation unit 16, based on Equation 1, uses the DC voltage value Ve [V] of the DC power supply 200, the resistance value Rb [Ω] of the measuring resistor 32, and the resistance value Ra [Ω] of the voltage divider resistor 37 to calculate the estimated value Vin1 [V] of the voltage between the terminals of the measuring resistor 32 when the second closed circuit 102 is formed. The resistance values ​​Rb [Ω] of the measuring resistor 32 and Ra [Ω] of the voltage divider resistor 37 are known, for example, the nominal values ​​of the manufacturers using these components. The resistance values ​​Rb [Ω] of the measuring resistor 32 and Ra [Ω] of the voltage divider resistor 37 are input beforehand into the arithmetic processing device constituting the voltage estimation unit 16, and used in the calculation of the estimated value Vin1 [V] of the voltage between the terminals of the measuring resistor 32 by the voltage estimation unit 16.

[0067] On the other hand, similarly, when the second closed circuit 102 is formed, the measured value (actual value) Vin2[V) of the voltage between the terminals of the measuring resistor 32 can also be obtained by the second voltage measuring unit 33.

[0068] When the second closed circuit 102 is formed, the estimated value Vin1 [V] of the voltage between the terminals of the measuring resistor 32 is ideally equal to the measured value (actual value) Vin2 [V] of the voltage between the terminals of the measuring resistor 32. However, in reality, there is a measurement error between the two due to component errors of the second voltage measuring unit 33 constituting the insulating amplifier, the measuring resistor 32, and the voltage divider resistor 37, as well as deterioration over time. The measurement error includes offset error and gain error. Here, several methods for detecting and processing measurement errors are listed.

[0069] First, the measurement error detection and processing based on the first method will be explained.

[0070] The measurement error detection processing based on the first method is a processing that only detects offset error. When the second closed circuit 102 is formed with the value Ve[V] of the DC voltage of the DC power supply 200 applied between the negative DC terminal 41N in the DC input section 41 and the U-phase AC terminal 42U in the AC output section 42, the offset error ΔV[V] between the estimated value Vin1[V] of the voltage between the terminals of the measuring resistor 32 and the measured value (actual value) Vin2[V] of the voltage between the terminals of the measuring resistor 32 is expressed as in Equation 2.

[0071] [Number 2]

[0072] ΔV=Vin1-Vin2 …(2)

[0073] In the measurement error detection processing based on the first method, the error detection unit 17, based on Equation 2, uses the measured value Vin2[V] of the inter-terminal voltage of the measuring resistor 32 obtained by the second voltage measuring unit 33 when the second closed circuit 102 is formed, and the estimated value Vin1[V] of the inter-terminal voltage of the measuring resistor 32 calculated by the voltage estimation unit 16, to detect the offset error ΔV[V] as a measurement error. The offset error ΔV[V] of the second voltage measuring unit 33, detected by the error detection unit 17, is stored in the storage unit 18.

[0074] Figure 4 This is a flowchart illustrating the operation flow of measurement error detection processing based on a first method in a motor drive device according to one embodiment of the present disclosure.

[0075] In the measurement error detection processing based on the first method, firstly, in step S101, the control unit 30 controls the first switch 11 to the open state and the second switch 31 to the open state. Additionally, the control unit 30 controls all switching elements within the motor drive amplifier unit 13 to the open state.

[0076] In step S102, a DC power supply 200 is connected between the negative DC terminal 41N in the DC input section 41 and the U-phase AC terminal 42U in the AC output section 42 to apply a DC voltage Ve[V]. This constitutes a second closed circuit 102 for error detection, including the DC power supply 200 and the measuring resistor 32.

[0077] In step S103, when the second closed circuit 102 is formed, the voltage estimation unit 16 calculates the estimated value Vin1 [V] of the inter-terminal voltage of the measuring resistor 32 based on Equation 1, using the value of the DC voltage Ve [V] of the DC power supply 200, the resistance value Rb [Ω] of the measuring resistor 32, and the resistance value Ra [Ω] of the voltage divider resistor 37.

[0078] In step S104, when the second closed circuit 102 is formed, the second voltage measuring unit 33 acquires the measured value Vin2[V] of the voltage between the terminals of the measuring resistor 32. Furthermore, steps S103 and S104 can be performed in a different order.

[0079] In step S105, the error detection unit 17 detects the offset error ΔV[V] based on Equation 2, using the measured value Vin2[V] of the inter-terminal voltage of the measuring resistor 32 obtained by the second voltage measuring unit 33 when the second closed circuit 102 is formed and the estimated value Vin1[V] of the inter-terminal voltage of the measuring resistor 32 calculated by the voltage estimation unit 16.

[0080] In step S106, the storage unit 18 stores the offset error ΔV[V] detected by the error detection unit 17. Then, the insulation resistance detection process S300, described later, begins.

[0081] Next, the measurement error detection and processing based on the second method will be explained.

[0082] The measurement error detection processing based on the second method involves processing both offset error and gain error. When the gain error of the second voltage measuring unit 33 is set to a and the offset error is set to b[V], the measured value Vin2[V] of the voltage between the terminals of the measuring resistor 32 obtained by the second voltage measuring unit 33 when the second closed circuit 102 is formed is related to the estimated value Vin1[V] of the voltage between the terminals of the measuring resistor 32 calculated by the voltage estimation unit 16, according to Equation 3.

[0083] [Number 3]

[0084] Vin2=a×Vin1+b …(3)

[0085] When the second closed circuit 102 is configured, when the DC voltage value Ve[V] of the DC power supply 200 is different, the estimated value Vin1[V] of the measuring resistor 32 estimated by the voltage estimation unit 16 also becomes different, and the measured value Vin2[V] of the measuring resistor 32 obtained by the second voltage measuring unit 33 also becomes different. Therefore, as long as the two voltages are applied as the DC voltage value Ve of the DC power supply 200 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, the two relationships based on Equation 3 can be obtained.

[0086] Let the first estimated value of the voltage between the terminals of the measuring resistor 32, when the first DC voltage of the DC power supply 200 is Ve1 [V] and the second closed circuit 102 is configured, be Vin11 [V]. Let the first measured value of the voltage between the terminals of the measuring resistor 32, when the second closed circuit 102 is configured, be Vin21 [V]. At this time, Equations 4 and 5 are valid.

[0087] [Number 4]

[0088]

[0089] [Number 5]

[0090] Vin21=a×Vin11+b …(5)

[0091] The second estimated value of the voltage between the terminals of the measuring resistor 32, estimated when the second DC voltage of the DC power supply 200 is Ve2 [V] and the second measured value of the voltage between the terminals of the measuring resistor 32 in the state of the second closed circuit 102, is set as Vin12 [V]. However, the value of the second DC voltage of the DC power supply 200, Ve2 [V], is a different value from the value of the first DC voltage, Ve1 [V]. In this case, Equations 6 and 7 hold.

[0092] [Number 6]

[0093]

[0094] [Number 7]

[0095] Vin22=a×Vin12+b …(7)

[0096] In the measurement error detection processing based on the second method, when the second closed circuit 102 is configured, the voltage estimation unit 16 calculates a first estimated value Vin11 [V] of the inter-terminal voltage of the measuring resistor based on Equation 4, using the value of the first DC voltage Ve1 [V] from the DC power supply 200, the resistance value Rb [Ω] of the measuring resistor 32, and the resistance value Ra [Ω] of the voltage divider resistor 37. When the second closed circuit 102 is configured, the voltage estimation unit 16 calculates a second estimated value Vin12 [V] of the inter-terminal voltage of the measuring resistor based on Equation 6, using the value of the second DC voltage Ve2 [V] from the DC power supply 200, the resistance value Rb [Ω] of the measuring resistor 32, and the resistance value Ra [Ω] of the voltage divider resistor 37.

[0097] In addition, in the measurement error detection processing based on the second method, when the second closed circuit 102 is configured, the second voltage measuring unit 33 acquires the first measured value Vin21[V] of the inter-terminal voltage of the measuring resistor 32 when the first DC voltage Ve1[V] from the DC power supply 200 is applied, and acquires the second measured value Vin22[V] of the inter-terminal voltage of the measuring resistor 32 when the second DC voltage Ve2[V] from the DC power supply 200 is applied.

[0098] If we solve the two linear equations in equations 5 and 7, we can obtain the gain error a shown in equation 8 and the offset error b [V] shown in equation 9.

[0099] [Number 8]

[0100]

[0101] [Number 9]

[0102]

[0103] In the measurement error detection processing based on the second method, the error detection unit 17 uses the first measured value Vin21[V] and the second measured value Vin22[V] of the inter-terminal voltage of the measuring resistor 32 obtained by the second voltage measurement unit 33, and the first estimated value Vin11[V] and the second estimated value Vin12[V] of the inter-terminal voltage of the measuring resistor 32 calculated by the voltage estimation unit 16, to detect the gain error a as a measurement error based on Equation 8, and the offset error b[V] as a measurement error based on Equation 9. The gain error a and the offset error b[V] detected by the error detection unit 17 as measurement errors of the second voltage measurement unit 33 are stored in the storage unit 18.

[0104] Figure 5This is a flowchart illustrating the operation flow of a measurement error detection process based on a second method in a motor drive device according to one embodiment of the present disclosure.

[0105] In the measurement error detection processing based on the second method, firstly, in step S201, the control unit 30 controls the first switch 11 to the open state and the second switch 31 to the open state. Additionally, the control unit 30 controls all switching elements within the motor drive amplifier unit 13 to the open state.

[0106] In step S202, a DC power supply 200 is connected between the negative DC terminal 41N in the DC input section 41 and the U-phase AC terminal 42U in the AC output section 42 to apply a first DC voltage Ve1[V]. This forms a DC power supply 200 that outputs the first DC voltage Ve1[V] and a second closed circuit 102 for error detection of the measuring resistor 32.

[0107] In step S203, when the second closed circuit 102 is formed, the voltage estimation unit 16 calculates the first estimated value Vin11 [V] of the inter-terminal voltage of the measuring resistor 32 based on Equation 4, using the value of the first DC voltage Ve1 [V] of the DC power supply 200, the resistance value Rb [Ω] of the measuring resistor 32, and the resistance value Ra [Ω] of the voltage divider resistor 37.

[0108] In step S204, when the second closed circuit 102, which forms the first DC voltage value Ve1 [V] output by the DC power supply 200, is established, the second voltage measuring unit 33 acquires the first measured value Vin21 [V] of the inter-terminal voltage of the measuring resistor 32. Furthermore, steps S203 and S204 can be executed in a different order.

[0109] In step S205, a DC power supply 200 is connected between the negative DC terminal 41N in the DC input section 41 and the U-phase AC terminal 42U in the AC output section 42 to apply a second DC voltage Ve2[V]. This creates a DC power supply 200 that outputs the second DC voltage Ve2[V] and a second closed circuit 102 for error detection of the measuring resistor 32.

[0110] In step S206, when the second closed circuit 102 is formed, the voltage estimation unit 16 calculates the second estimated value Vin12 [V] of the inter-terminal voltage of the measuring resistor 32 based on Equation 6, using the value of the second DC voltage Ve2 [V] of the DC power supply 200, the resistance value Rb [Ω] of the measuring resistor 32, and the resistance value Ra [Ω] of the voltage divider resistor 37.

[0111] In step S207, when the second closed circuit 102, which forms the second DC voltage value Ve2[V] output by the DC power supply 200, is in place, the second voltage measuring unit 33 acquires the second measured value Vin22[V] of the voltage between the terminals of the measuring resistor 32. Furthermore, steps S206 and S207 can be performed in a different order.

[0112] In step S208, the error detection unit 17 uses the first measured value Vin21[V] and the second measured value Vin22[V] of the inter-terminal voltage of the measuring resistor 32 obtained by the second voltage measurement unit 33, and the first estimated value Vin11[V] and the second estimated value Vin12[V] of the inter-terminal voltage of the measuring resistor 32 calculated by the voltage estimation unit 16, to detect the gain error a as a measurement error based on Equation 8, and to detect the offset error b[V] as a measurement error based on Equation 9.

[0113] In step S209, the storage unit 18 stores the gain error a and offset error b[V], which are the measurement errors of the second voltage measuring unit 33, detected by the error detection unit 17. Then, the insulation resistance detection process S300, described later, begins.

[0114] Next, the detection of the insulation resistance value Rm [Ω] of the motor 3 insulation resistance 4 by the insulation resistance value detection unit 15 will be explained in more detail.

[0115] Figure 6 This diagram illustrates the first closed circuit constructed when the insulation resistance value detection process performed by the insulation resistance value detection unit is executed in a motor drive device based on one embodiment of the present disclosure. Figure 6 The diagrams of the control unit 30, calculation unit 34, correction value generation unit 35, correction unit 36, voltage estimation unit 16, error detection unit 17, and erasure unit 19 are omitted.

[0116] When performing insulation resistance value detection processing by the insulation resistance value detection unit 15, firstly, the first switch 11 is set to the closed state, the second switch 31 is set to the open state, and all switching elements in the motor drive amplifier unit 13 are set to the open state. The capacitor 22 is charged by the power flowing from the AC power supply 2 through the rectifier circuit 21. When the capacitor 22 is fully charged, the first switch 11 is set to the open state, the second switch 31 is set to the closed state, and all switching elements in the upper and lower bridge arms of the motor drive amplifier unit 13 are set to the open state. This forms the first closed circuit 101 for insulation resistance value detection, as indicated by the thick arrow in the figure. Furthermore, since the motor 3 has been driven by the motor drive device 1 and then the driving of the motor 3 has been stopped, the capacitor 22 has been fully charged. Therefore, in this case, the process of charging the capacitor 22 by the power flowing in from the AC power supply 2 through the rectifier circuit 21 can be omitted, and the first closed circuit 101 can be formed by setting the first switch 11 to the open state, setting the second switch 31 to the closed state, and setting all the switching elements of the upper and lower bridge arms of the motor drive amplifier section 13 to the open state. Figure 8 This is a circuit diagram showing the portion associated with the first closed circuit. Figure 8 The diagram of the second switch 31 in the closed state is omitted. (See diagram for example.) Figure 6 and Figure 8 As shown, the first closed circuit 101 includes a capacitor 22, a voltage divider resistor 38, a second switch 31 in a closed state, a voltage divider resistor 39, an insulation resistance 4 of the motor coil of the motor 3, a voltage divider resistor 37, and a measuring resistor 32.

[0117] 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 based on the measured value (actual value) Vin3 [V] of the inter-terminal voltage of the measuring resistor 32 obtained by the second voltage measuring unit 33 and the resistance value Rb [Ω] of the measuring resistor 32.

[0118] [Number 10]

[0119]

[0120] With the first closed circuit 101 in place, the circuit equation expressed by Equation 11 holds true based on the measured value Vdc[V] of the voltage of the power supply unit 12 (voltage of capacitor 22) obtained 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 measuring resistor 32, the resistance value Ra[Ω] of the voltage divider resistor 37, the resistance value Rc[Ω] of the voltage divider resistor 38, the resistance value Rd[Ω] of the voltage divider resistor 39, and the insulation resistance value Rm[Ω] of the insulation resistance 4 of the motor 3.

[0121] [Number 11]

[0122] Vdc=(Rc+Rd+Rm+Ra+Rb)×I1…(11)

[0123] If we substitute Equation 11 into Equation 10 and transform it, we can obtain Equation 12.

[0124] [Number 12]

[0125]

[0126] According to Equation 12, the insulation resistance value Rm[Ω] of the insulation resistance 4 of the motor 3 can be calculated. However, the output of the second voltage measuring unit 33 includes measurement errors caused by component errors of the second voltage measuring unit 33 constituting the insulation amplifier, the measuring resistor 32, and the voltage divider resistor 37, as well as deterioration over time. Therefore, 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 Vdc[V] of the voltage of the power supply unit 12 obtained by the first voltage measuring unit 14 when the first closed circuit 101 is formed, the measured value Vin3[V] of the inter-terminal voltage of the measuring resistor 32 obtained by the second voltage measuring unit 33, the measurement error of the second voltage measuring unit 33, and the resistance value Rb[Ω] of the measuring resistor 32. When performing this calculation, the measurement error of the second voltage measuring unit 33 is used to correct the measured value Vin3[V] of the inter-terminal voltage of the measuring resistor 32 obtained by the second voltage measuring unit 33. Below, we list the insulation resistance value detection process based on the first method, which corresponds to the first measurement error detection process that only detects the offset error ΔV[V], and the insulation resistance value detection process based on the second method, which corresponds to the second measurement error detection process that detects the gain error a and the offset error b[V].

[0127] First, the insulation resistance value detection and processing based on the first method will be explained.

[0128] For reference Figure 3 and Figure 4As explained, in the measurement error detection processing based on the first method, the error detection unit 17, based on Equation 2, uses the measured value Vin2[V] of the inter-terminal voltage of the measuring resistor 32 obtained by the second voltage measuring unit 33 when the second closed circuit 102 is formed, and the estimated value Vin1[V] of the inter-terminal voltage of the measuring resistor 32 calculated by the voltage estimation unit 16 to detect the offset error ΔV[V] as the measurement error. When only the offset error ΔV[V] is considered as the measurement error detected by the measurement error detection processing based on the first method, the value “-ΔV[V]” obtained by reversing the polarity of the error ΔV[V] is used as a correction value Vamend1[V] to correct the measured value Vin3[V] of the inter-terminal voltage of the measuring resistor 32 obtained by the second voltage measuring unit 33 when the first closed circuit 101 is formed. The correction value Vamend1[V] is expressed as the offset error ΔV[V] as in Equation 13.

[0129] [Number 13]

[0130] Vamend1=-ΔV …(13)

[0131] The correction value generation unit 35 generates a correction value Vamend[V] based on Equation 13 using the offset error ΔV[V] detected by the measurement error detection processing based on the first method.

[0132] By adding (plus) a correction value Vamend1[V] for offsetting offset error ΔV[V] to the measured value Vin3[V] of the voltage between the terminals of the measuring resistor 32 obtained by the second voltage measuring unit 33 when the first closed circuit 101 is formed, the corrected measured value Vin41[V] of the voltage between the terminals of the measuring resistor 32 is obtained as shown in Equation 14.

[0133] [Number 14]

[0134] Vin41=Vin3+Vamend …(14)

[0135] Based on Equation 14, the correction unit 36 ​​uses the correction value Vamend1[V] generated by the correction value generation unit 35 to correct the measured value Vin3[V] of the inter-terminal voltage of the measuring resistor 32 obtained by the second voltage measurement unit 33 when the first closed circuit 101 is formed, thereby generating the corrected measured value Vin41[V] of the inter-terminal voltage of the measuring resistor 32.

[0136] In the insulation resistance value detection processing based on the first method, the calculation unit 34 calculates the insulation resistance value Rm[Ω] of the insulation resistance 4 of the motor 3 based on Equation 15, which is obtained by replacing the measured value Vin3[V] of the inter-terminal voltage of the measuring resistor 32 in Equation 12 with the corrected measured value Vin41[V] of the inter-terminal voltage of the measuring resistor 32.

[0137] [Number 15]

[0138]

[0139] Here, numerical examples will be used to explain the impact of the offset error ΔV[V] caused by component errors and deterioration over time on the detection accuracy of the insulation resistance value Rm[Ω] of the motor 3, which is caused by the component errors of the second voltage measuring unit 33 constituting the insulation amplifier, the measuring resistor 32, and the voltage divider resistor 37.

[0140] For example, consider setting the resistance value Rc of voltage divider resistor 38 to 1000kΩ, the resistance value Rd of voltage divider resistor 39 to 5kΩ, the resistance value Rb of measuring resistor 32 to 5kΩ, the resistance value Ra of voltage divider resistor 37 to 1000kΩ, and the voltage Vdc of power supply unit 12 (voltage of capacitor 22) to 300V.

[0141] When the actual insulation resistance value Rm of motor 3 is 1MΩ, if the inter-terminal voltage of measuring resistor 32 is calculated using Equation 12 based on the first closed circuit 101, the inter-terminal voltage is 498mV. If the 498mV of the measured value Vin3 of the inter-terminal voltage of measuring resistor 32 obtained by the second voltage measuring unit 33 includes 10mV as an offset error ΔV, then the correct measured value Vin3 of the inter-terminal voltage of measuring resistor 32 should be 488mV. Therefore, if Vin3 = 488mV is substituted into Equation 12 to recalculate the insulation resistance value Rm of motor 3, the insulation resistance value Rm is 1.06MΩ, which deviates from the actual insulation resistance value Rm = 1MΩ of motor 3.

[0142] If the actual insulation resistance value Rm of motor 3 is 10MΩ, and the inter-terminal voltage of measuring resistor 32 is calculated using Equation 12 based on the first closed circuit 101, then the inter-terminal voltage is 125mV. If the 125mV of the measured value Vin3 of the inter-terminal voltage of measuring resistor 32 obtained by the second voltage measuring unit 33 includes 10mV as an offset error ΔV, then the correct measured value Vin3 of the inter-terminal voltage of measuring resistor 32 should be 115mV. Therefore, if Vin12 = 115mV is substituted into Equation 12 to recalculate the insulation resistance value Rm of motor 3, then the insulation resistance value Rm is 11.03MΩ, which deviates from the actual insulation resistance value Rm = 10MΩ of motor 3.

[0143] When the actual insulation resistance value Rm of motor 3 is 50MΩ, if the inter-terminal voltage of measuring resistor 32 is calculated using Equation 12 based on the first closed circuit 101, the inter-terminal voltage is 29mV. If the 29mV of the measured value Vin3 of the inter-terminal voltage of measuring resistor 32 obtained by the second voltage measuring unit 33 includes 10mV as an offset error ΔV, then the correct measured value Vin3 of the inter-terminal voltage of measuring resistor 32 should be 19mV. Therefore, if Vin3 = 19mV is substituted into Equation 12 to recalculate the insulation resistance value Rm of motor 3, the insulation resistance value Rm is 76.94MΩ, which deviates from the actual insulation resistance value Rm = 50MΩ of motor 3.

[0144] As shown in the numerical example above, the larger the actual value Rm[Ω] of the insulation resistance of motor 3, the larger the error in the insulation resistance value of motor 3 calculated when the measured value Vin3 of the inter-terminal voltage of measuring resistor 32 obtained by the second voltage measuring unit 33, which contains the offset error ΔV, is formed when the first closed circuit 101 is established. According to the insulation resistance value detection processing based on the first method, the value "-ΔV[V]" obtained by reversing the polarity of the offset error ΔV[V] is used as the correction value Vamend1[V] to correct the measured value Vin3[V] of the inter-terminal voltage of measuring resistor 32 obtained by the second voltage measuring unit 33. The insulation resistance value Rm[Ω] is calculated using the corrected measured value Vin41[V] of the inter-terminal voltage of measuring resistor 32. Therefore, the insulation resistance value Rm[Ω] of motor 3 can be accurately detected.

[0145] Next, the insulation resistance value detection and processing based on the second method will be explained.

[0146] For reference Figure 3 and Figure 5As explained, in the measurement error detection processing based on the second method, the error detection unit 17 uses the first measured value Vin21[V] of the inter-terminal voltage of the measuring resistor 32 obtained by the second voltage measurement unit 33 and the second measured value Vin22[V] of the inter-terminal voltage of the measuring resistor 32, as well as the first estimated value Vin11[V] of the inter-terminal voltage of the measuring resistor 32 and the second estimated value Vin12[V] of the inter-terminal voltage of the measuring resistor 32 calculated by the voltage estimation unit 16, to detect the gain error a as a measurement error based on Equation 8, and to detect the offset error b[V] as a measurement error based on Equation 9. Taking into account the gain error a and offset error b[V] as measurement errors detected by the measurement error detection processing based on the second method, the measured value Vin3[V] of the inter-terminal voltage of the measuring resistor 32 obtained by the second voltage measuring unit 33 when the first closed circuit 101 is formed is corrected using a correction formula as shown in Equation 16, so as to generate a corrected measured value Vin42[V] of the inter-terminal voltage of the measuring resistor 32.

[0147] [Number 16]

[0148]

[0149] The correction value generation unit 35 generates a correction value (i.e., the correction formula shown in Equation 16) based on Equation 16, using the gain error a and offset error b[V] detected by the measurement error detection processing based on the second method.

[0150] The correction unit 36 ​​uses the correction formula shown in Formula 16 generated by the correction value generation unit 35 to correct the measured value Vin3[V] of the inter-terminal voltage of the measuring resistor 32 obtained by the second voltage measuring unit 33 when the first closed circuit 101 is formed, thereby generating the corrected measured value Vin42[V] of the inter-terminal voltage of the measuring resistor 32.

[0151] In the insulation resistance value detection processing based on the second method, the calculation unit 34 calculates the insulation resistance value Rm[Ω] of the insulation resistance 4 of the motor 3 based on Equation 17, which is obtained by replacing the measured value Vin3[V] of the inter-terminal voltage of the measuring resistor 32 in Equation 12 with the corrected measured value Vin42[V] of the inter-terminal voltage of the measuring resistor 32.

[0152] [Number 17]

[0153]

[0154] Here, numerical examples of the gain error a and offset error b[V] calculated by the correction value generation unit 35 based on Equation 16 are shown.

[0155] For example, consider the following values: the resistance value Rc of voltage divider resistor 38 is set to 1000kΩ, the resistance value Rd of voltage divider resistor 39 is set to 5kΩ, the resistance value Rb of measuring resistor 32 is set to 5kΩ, the resistance value Ra of voltage divider resistor 37 is set to 1000kΩ, the first measured value V22 of measuring resistor 32 when the DC power supply 200 outputs a first DC voltage of 100V is set to 511mV, and the second measured value V22 of measuring resistor 32 when the DC power supply 200 outputs a second DC voltage of 90V is set to 460mV.

[0156] When the DC power supply 200 outputs a first DC voltage of 100V, according to Equation 6, the first estimated value V12 of the measuring resistor 32 is 498mV. When the DC power supply 200 outputs a second DC voltage of 90V, according to Equation 6, the second estimated value V12 of the measuring resistor 32 is 448mV. If these values ​​are substituted into Equations 8 and 9, the gain error a is 1.02 and the offset error b is 3mV.

[0157] Furthermore, regarding the measurement error of the second voltage measuring unit 33, the offset error is more dominant than the gain error. Therefore, the insulation resistance value Rm[Ω] of the motor 3 can be detected with high accuracy by the insulation resistance value detection processing based on the first method that only considers the offset error. However, the insulation resistance value Rm[Ω] of the motor 3 can be detected with even higher accuracy by the insulation resistance value detection processing based on the second method that considers both the gain error and the offset error.

[0158] Figure 7 This is a flowchart illustrating the operation flow of the insulation resistance value detection process performed by the insulation resistance value detection unit in a motor drive device based on an embodiment of the present disclosure. Figure 7 The flowchart shown can be applied to both the first insulation resistance value detection process and the second insulation resistance value detection process. In step S300, before starting the insulation resistance value detection process, by completing... Figure 4 The measurement error detection processing based on the first method shown is or Figure 5 The measurement error detection processing based on the second method shown is used to store the measurement error in the storage unit 18.

[0159] In step S301, the correction value generation unit 35 reads the stored measurement error from the storage unit 18.

[0160] In step S302, the correction value generation unit 35 generates a correction value based on the measurement error.

[0161] In step S303, the control unit 30 controls the first switch 11 to the closed state and the second switch 31 to the open state. Additionally, the control unit 30 controls all switching elements within the motor drive amplifier unit 13 to the open state. Therefore, in step S304, the capacitor 22 is charged by the power flowing from the AC power supply 2 via the rectifier circuit 21. The control unit 30 monitors the charging state of the capacitor 22 via the first voltage measuring unit 14. Furthermore, since the capacitor 22 is already fully charged after the motor 3 has been driven by the motor drive device 1 and then stopped, step S304 can be omitted in this case.

[0162] When capacitor 22 is fully charged, in step S305, control unit 30 controls first switch 11 to the open state and second switch 31 to the closed state. Additionally, all switching elements of the upper and lower bridge arms of motor drive amplifier unit 13 are set to the open state. As a result, a first closed circuit 101 for insulation resistance value detection is formed.

[0163] In step S306, the first voltage measuring unit 14 acquires the measured value of the voltage of the power supply unit 12 (the voltage of the capacitor 22).

[0164] In step S307, the second voltage measuring unit 33 acquires the measured value Vin3[V] of the inter-terminal voltage of the measuring resistor 32 that constitutes the first closed circuit 101.

[0165] In step S308, the correction unit 36 ​​uses the correction value generated by the correction value generation unit 35 to correct the measured value Vin3[V] of the inter-terminal voltage of the measuring resistor 32 obtained by the second voltage measuring unit 33 when the first closed circuit 101 is formed, thereby generating a corrected measured value of the inter-terminal voltage of the measuring resistor 32. Figure 4 In the case where the measurement error detection processing based on the first method only detects the offset error ΔV[V], the correction unit 36, based on Equation 14, uses the correction value Vamand1[V] generated by the correction value generation unit 35 to correct the measured value Vin3[V] of the inter-terminal voltage of the measuring resistor 32 obtained by the second voltage measuring unit 33 when the first closed circuit 101 is formed, thereby generating the corrected measured value Vin41[V] of the inter-terminal voltage of the measuring resistor 32. (The last sentence appears to be incomplete and possibly refers to a different process.) Figure 5In the case where the measurement error detection processing based on the second method detects both gain error a and offset error b [V], the correction unit 36 ​​uses the correction formula shown in Equation 16 generated by the correction value generation unit 35 to correct the measured value Vin3 [V] of the inter-terminal voltage of the measuring resistor 32 obtained by the second voltage measurement unit 33 when the first closed circuit 101 is formed, thereby generating the corrected measured value Vin42 [V] of the inter-terminal voltage of the measuring resistor 32.

[0166] In step S309, 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 obtained by the first voltage measuring unit 14 when the first closed circuit 101 is formed, the corrected measured value of the inter-terminal voltage of the measuring resistor 32 generated by the correction unit 36, and the resistance value of the measuring resistor 32. More specifically, in the insulation resistance value detection processing based on the first method, 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.

[0167] Next, a specific example of the motor drive amplifier section 13 will be described. For example, a servo amplifier may be considered as an example of the motor drive amplifier section 13.

[0168] Figure 9 This is a perspective view illustrating a servo amplifier, which is a motor drive amplifier section, within a motor drive device based on one embodiment of the present disclosure. Figure 10 This is a front view illustrating a servo amplifier, which is a motor drive amplifier section, within a motor drive device based on one embodiment of the present disclosure. Figure 11 This is an exploded perspective view illustrating a servo amplifier, which is a motor drive amplifier section, within a motor drive device according to one embodiment of the present disclosure. Figure 12 This is a schematic diagram illustrating the first and second substrates within a servo amplifier that serves as a motor drive amplifier section in a motor drive device based on an embodiment of the present disclosure.

[0169] A DC input section 41 and an AC output section 42 are provided in the housing of the servo amplifier, which serves as the motor drive amplifier section 13. The DC input section 41 has a positive DC terminal 41P and a negative DC terminal 41N. The AC output section 42 has a U-phase AC terminal 42U, a V-phase AC terminal 42V, and a W-phase AC terminal 42W. Because the DC input section 41 and the AC output section 42 are provided in the housing of the servo amplifier, it is easy to connect a DC power supply 200 from an external source. For example, during shipment testing of the motor drive device 1, maintenance, etc., a DC power supply 200 can be connected to perform measurement error detection processing. Furthermore, an EEPROM (registered trademark) is provided within the servo amplifier, which serves as the motor drive amplifier section 13, and can therefore be used as a storage unit 18.

[0170] Furthermore, multiple substrates are provided within the servo amplifier, which serves as the motor drive amplifier section 13, for mounting various components, processing units, and wiring. Conventionally, in the event of any malfunction within the motor drive amplifier section 13, only the malfunctioning substrate is replaced, and other substrates are used continuously. In one embodiment of this disclosure, the first substrate 51, which is a power PCB, within the multiple substrates of the servo amplifier serving as the motor drive amplifier section 13, houses the inverter's main circuitry, a processing unit for building insulation resistance detection 15 and an erasure unit 19, and a storage unit 18. Additionally, a processing unit for building error detection 17 and a voltage estimation unit 16 is provided on the second substrate 52, which serves as a control PCB. The first substrate and the second substrate are electrically and mechanically connected in a detachable manner via a connector 53A provided on the first substrate 51 and a connector 53B provided on the second substrate 52.

[0171] For example, when replacing components other than the first substrate 51 during troubleshooting, the error of the second voltage measuring unit 33, which is mounted in the insulation resistance detection unit 15 on the first substrate, remains unchanged. However, the storage unit 18 for storing measurement errors is mounted on the first substrate 51. Therefore, the measurement errors stored in the storage unit 18 can be directly reused in the insulation resistance detection process. Thus, it is not necessary to re-measure the measurement error of the second voltage measuring unit 33, thereby reducing the workload of the operator and enabling high-precision insulation resistance detection processing to be achieved quickly and easily.

[0172] On the other hand, if, for example, during troubleshooting, a component related to the insulation resistance value detection unit 15 is replaced on the first substrate 51, the measurement error stored in the storage unit 18 cannot be used in the insulation resistance value detection process using the replaced insulation resistance value detection unit 15. In this case, for example, an operator can activate the erasure unit 19 via an input device to erase the measurement error stored in the storage unit 18. Then, the measurement error detection process is re-executed for the replaced insulation resistance value detection unit 15, detecting the measurement error of the second voltage measurement unit 33 within the replaced insulation resistance value detection unit 15 and storing this measurement error in the storage unit 18. This allows for the re-implementation of subsequent high-precision insulation resistance value detection processes.

[0173] As explained above, according to the motor drive device 1 based on one embodiment of this disclosure, the insulation resistance value Rm[Ω] of the motor 3 is calculated based on the measurement error caused by component errors of the second voltage measuring unit 33, the measuring resistor 32, and the voltage divider resistor 37, as well as by years of deterioration. Therefore, the insulation resistance value Rm[Ω] of the motor 3 can be accurately detected. In addition, the magnitude of the DC voltage output by the DC power supply 200 is only sufficient to measure the degree of measurement error of the second voltage measuring unit 33, and a large voltage is not applied to the motor power line, so it is safe.

[0174] Explanation of reference numerals in the attached figures

[0175] 1: Motor drive unit; 2: AC power supply; 3: Motor; 4: Insulation resistance; 11: First switch; 12: Power supply unit; 13: Motor drive amplifier unit; 14: First voltage measurement unit; 15: Insulation resistance value detection unit; 16: Voltage estimation unit; 17: Error detection unit; 18: Storage unit; 19: Eraser unit; 21: Rectifier circuit; 22: Capacitor; 30: Control unit; 31: Second switch; 32: Measuring resistor; 33: Second voltage measurement unit; 34: Calculation 35: Correction value generation unit; 36: Correction unit; 37, 38, 39: Voltage divider resistors; 41: DC input unit; 41P: Positive DC terminal; 41N: Negative DC terminal; 42: AC output unit; 42U: U-phase AC terminal; 42V: V-phase AC terminal; 42W: W-phase AC terminal; 51: First substrate; 52: Second substrate; 53A, 53B: Connectors; 101: First closed circuit; 102: Second closed circuit; 200: DC power supply.

Claims

1. A motor drive device, comprising: The first switch is used to disconnect and close the circuit from the AC power source; The power supply unit rectifies the AC voltage supplied from the AC power source via the first switch in a closed state into a DC voltage through a rectifier circuit, and then smooths the rectified DC voltage through a capacitor before outputting it. The motor drive amplifier section uses the switching elements of the upper bridge arm and the lower bridge arm to convert the DC voltage input from the power supply section via the DC input section into an AC voltage for motor drive, and supplies the AC voltage to the motor via the AC output section. The first voltage measuring unit acquires the measured value of the voltage of the power supply unit; An insulation resistance detection unit includes a second switch, a measuring resistor, a second voltage measuring unit, and a calculation unit. When the second switch is closed, one end of the capacitor is connected to ground; when it is open, one end of the capacitor is not connected to ground. The measuring resistor is positioned between a terminal in the DC input section connected to the other end of the capacitor and a terminal in the AC output section connected to the motor coil of the motor. The second voltage measuring unit acquires a measured value of the voltage between the terminals of the measuring resistor. The calculation unit uses at least the measured value of the voltage between the terminals of the measuring resistor acquired by the second voltage measuring unit to calculate the insulation resistance value of the motor. When the voltage estimation unit forms a second closed circuit including the DC power supply and the measuring resistor by setting the first switch and the second switch to the open state and setting the switching element of the motor drive amplifier to the open state, under the condition that a DC voltage from a DC power supply different from that of the power supply is applied between the DC input terminal and the AC output terminal, the voltage estimation unit calculates an estimated value of the voltage between the terminals of the measuring resistor based on the value of the DC voltage from the DC power supply and the resistance value of the measuring resistor. as well as The error detection unit uses the measured value of the voltage between the terminals of the measuring resistor obtained by the second voltage measuring unit when the second closed circuit is formed, and the estimated value of the voltage between the terminals of the measuring resistor calculated by the voltage estimation unit, to detect the measurement error of the second voltage measuring unit. The calculation unit calculates the insulation resistance value of the motor based on the measured voltage of the power supply unit obtained by the first voltage measuring unit when a first closed circuit including the second switch, the capacitor, the measuring resistor, the motor coil, and the ground is formed by setting the first switch to the open state and the second switch to the closed state, the measured value of the inter-terminal voltage of the measuring resistor obtained by the second voltage measuring unit, the measurement error, and the resistance value of the measuring resistor.

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

3. The motor drive device according to claim 2, wherein, The error detection unit uses the measured value of the voltage between the terminals of the measuring resistor obtained by the second voltage measuring unit when the second closed circuit is formed, and the estimated value of the voltage between the terminals of the measuring resistor calculated by the voltage estimation unit, to detect the offset error as the measurement error. The correction value generation unit generates the correction value based on the offset error.

4. The motor drive device according to claim 2, wherein, When the second closed circuit is formed, the voltage estimation unit calculates a first estimated value of the inter-terminal voltage of the measuring resistor based on the value of a first DC voltage from the DC power supply and the resistance value of the measuring resistor, and calculates a second estimated value of the inter-terminal voltage of the measuring resistor based on the value of a second DC voltage from the DC power supply, which is different from the value of the first DC voltage, and the resistance value of the measuring resistor. When the second closed circuit is formed, the second voltage measuring unit acquires a first measured value of the inter-terminal voltage of the measuring resistor when the first DC voltage from the DC power supply is applied, and acquires a second measured value of the inter-terminal voltage of the measuring resistor when the second DC voltage from the DC power supply is applied. The error detection unit uses a first measured value and a second measured value of the inter-terminal voltage of the measuring resistor obtained by the second voltage measurement unit, and a first estimated value and a second estimated value of the inter-terminal voltage of the measuring resistor calculated by the voltage estimation unit, to detect offset error and gain error, which are the measurement errors. The correction value generation unit generates the correction value based on the offset error and the gain error.

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

6. The motor drive device according to claim 5, further comprising: A first substrate, wherein at least the insulation resistance value detection unit and the storage unit are disposed on the first substrate; and The second substrate is electrically and mechanically connected to the first substrate in a detachable manner, and at least the error detection unit is disposed on the second substrate.

7. The motor drive device according to claim 6, wherein, It also includes an erasing section for erasing the measurement error stored in the storage section.

8. The motor drive device according to any one of claims 1 to 7, wherein, The DC power supply is electrically connected to one terminal in the DC input section and one terminal in the AC output section in a detachable manner.

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