Motor drive device that detects power failure during regenerative operation

Abstract

A motor drive device according to the present invention comprises: a converter that performs a regenerative operation according to a 120-degree conduction method and a rectification operation; an inverter that performs a powering operation and a regenerative operation; a current detection unit that detects the value of an electric current input into the converter and the value of an electric current output from the converter; a voltage detection unit that detects a voltage input into the converter; a distortion rate calculation unit that calculates the total harmonic distortion rate of the voltage detected by the voltage detection unit; and a power failure determination unit that, during the regenerative operation of the converter, determines the presence or absence of a power failure on the AC power supply side on the basis of the value of the electric current detected by the current detection unit and of the total harmonic distortion rate.

Description

Motor drive device that detects power outages during regenerative operation

[0001] The present disclosure relates to a motor drive device that detects a power outage during regenerative operation.

[0002] In a motor drive device that drives a motor installed in a machine tool or robot, AC power supplied from an AC power source is converted into DC power by a converter (rectifier) ​​and output to a DC link, and then the DC power in the DC link is converted into AC power for driving the motor by an inverter and supplied to the motor. Power outages that may occur on the AC power source side of the motor drive device are detected by monitoring the AC input voltage.

[0003] JP 01-248968 JP 2015-124074 JP 04-117103

[0004] A motor drive device with a power regeneration function can return regenerative power generated when the motor decelerates to the AC power supply. If a power outage occurs on the AC power supply side during regenerative operation of the motor drive device, the power outage cannot be detected by monitoring the AC input voltage. Therefore, there is a need for the development of technology that can detect a power outage even during regenerative operation in a motor drive device with a power regeneration function.

[0005] According to one aspect of the present disclosure, a motor drive device includes: a converter that performs a rectification operation of converting AC power input from an AC power supply side into DC power and outputs the DC power to a DC link side; and a regeneration operation of converting the DC power on the DC link side into AC power in accordance with a 120-degree conduction method and returning the DC power to the AC power supply side; an inverter that performs a powering operation of converting the DC power input from the DC link side into AC power for driving a motor and outputs the AC power to the motor side; and a regeneration operation of converting the AC power regenerated by the motor into DC power and returning the DC power to the DC link side; a current detection unit that detects the value of a current input to or a current output from the converter; a voltage detection unit that detects the voltage input to the converter; a distortion factor calculation unit that calculates the total harmonic distortion factor of the voltage detected by the voltage detection unit; and a power outage determination unit that determines whether or not a power outage has occurred on the AC power supply side based on the value of the current and the total harmonic distortion factor detected by the current detection unit during regenerative operation of the converter.

[0006] FIG. 1 is a circuit diagram showing a motor drive device according to a first embodiment of the present disclosure. FIG. 2 is a diagram showing line voltage waveforms on the AC input / output sides of a converter using a 120-degree conduction method during regenerative operation when there is no power outage on the AC power supply side. FIG. 3 is a diagram showing line voltage waveforms on the AC input / output sides of a converter using a 120-degree conduction method during regenerative operation when a power outage occurs on the AC power supply side. FIG. 4 is a flowchart showing an operation flow of power outage detection processing in the motor drive device according to the first embodiment of the present disclosure. FIG. 5 is a circuit diagram showing a motor drive device according to a second embodiment of the present disclosure. FIG. 6 is a flowchart showing an operation flow of power outage detection processing in the motor drive device according to the second embodiment of the present disclosure. FIG. 7 is a circuit diagram showing a motor drive device according to a third embodiment of the present disclosure. FIG. 8 is a flowchart showing an operation flow of power outage detection processing in the motor drive device according to the third embodiment of the present disclosure. FIG. 9 is a circuit diagram showing a motor drive device according to a fourth embodiment of the present disclosure. FIG. 10 is a flowchart showing an operation flow of power outage detection processing in the motor drive device according to the fourth embodiment of the present disclosure. FIG. 11 is a flowchart showing an operation flow when power outage determination processing according to a first mode is executed in power outage detection processing in the motor drive device according to the fourth embodiment of the present disclosure. FIG. 12 is a flowchart showing an operation flow when power outage determination processing according to a second mode is executed in power outage detection processing in the motor drive device according to the fourth embodiment of the present disclosure. FIG. 10 is a circuit diagram showing a motor drive device according to a fifth embodiment of the present disclosure. FIG. 11 is a flowchart showing an operation flow of power failure detection processing in the motor drive device according to the fifth embodiment of the present disclosure. FIG. 12 is a flowchart showing an operation flow when power failure determination processing according to a first form is executed in power failure detection processing in the motor drive device according to the fifth embodiment of the present disclosure. FIG. 13 is a flowchart showing an operation flow when power failure determination processing according to a second form is executed in power failure detection processing in the motor drive device according to the fifth embodiment of the present disclosure. FIG. 14 is a circuit diagram showing a motor drive device according to a sixth embodiment of the present disclosure. FIG. 15 is a flowchart showing an operation flow of power failure detection processing in the motor drive device according to the sixth embodiment of the present disclosure.

[0007] Hereinafter, an embodiment of a motor drive device that detects a power outage during regenerative operation will be described with reference to the drawings. In the following description, components having the same or similar functions will be assigned the same reference numerals. Duplicate descriptions of those components may be omitted. The scale of the drawings has been appropriately changed to facilitate understanding.

[0008] In the following description, "electrically connected" may be simply referred to as "connected." A converter that converts AC power supplied from a three-phase AC power source into DC power and outputs it is also called a "rectifier," "rectifier device," "rectifier circuit," or "forward converter." An inverter that converts DC power into AC power and outputs it is also called an "inverter." A "DC link" refers to a circuit portion that electrically connects the DC output side of a converter and the DC input side of an inverter. A "DC link" is also called a "DC link section," "DC link," "DC link section," "DC bus," or "DC intermediate circuit." A "DC link voltage" refers to the potential difference between the positive potential of the positive power line of the DC link and the negative potential of the negative power line. The "on" operation of a switching element means that the switching element is closed, thereby forming an electric path through the switching element. The "off" operation of a switching element means that the switching element is opened, thereby interrupting the electric path through the switching element. Furthermore, the numerical examples illustrated below are merely examples, and numerical values ​​other than those described here may be used.

[0009] First Embodiment of the Present Disclosure FIG. 1 is a circuit diagram showing a motor drive device according to a first embodiment of the present disclosure.

[0010] In the first embodiment of the present disclosure described below and each of the embodiments described later, a case will be described in which a motor 300 is driven by a motor drive device 1 connected to an AC power supply 200, as an example. Examples of the AC power supply 200 include a three-phase 400V AC power supply, a three-phase 200V AC power supply, a three-phase 600V AC power supply, and a single-phase 100V AC power supply. Here, as an example, the AC power supply 200 is three-phase. Machines in which the motor 300 is installed include, for example, machine tools and robots.

[0011] The motor drive device 1 according to the first embodiment of the present disclosure includes a converter 11, an inverter 12, a current detection unit 13, a voltage detection unit 14, a distortion factor calculation unit 15, a power failure determination unit 16, a DC link voltage detection unit 17, and an inverter control unit 40. The motor drive device 1 also includes a capacitor 101, a breaker 102, an electromagnetic contactor 103, and a reactor 104. Note that, in order to enable the current detection unit 13, the voltage detection unit 14, the distortion factor calculation unit 15, the power failure determination unit 16, the DC link voltage detection unit 17, and the inverter control unit 40 to operate even in the event of a power failure on the AC power supply 200 side, it is preferable that a power supply for supplying power to these units be provided on a system separate from the AC power supply 200.

[0012] The converter 11 is a 120-degree conduction type rectifier with a power regeneration function. The converter 11 is composed of a three-phase bridge circuit of switching elements and diodes connected in antiparallel to the switching elements. Examples of the switching elements include FETs, IGBTs, thyristors, GTOs, and transistors, but other switching elements may also be used. In the illustrated example, for the U phase, a switching element S is connected to the upper arm. UU is provided, and the lower arm is provided with a switching element S UL For the V phase, a switching element S is provided in the upper arm. VU is provided, and the lower arm is provided with a switching element S VL For the W phase, a switching element S is provided in the upper arm. WU is provided, and the lower arm is provided with a switching element S WLThe converter 11 performs a rectification operation of converting AC power input from the AC power source 200 into DC power and outputs the DC power to the DC link, and a regeneration operation of converting DC power from the DC link side into AC power by turning on and off switching elements in accordance with the 120-degree conduction method and returning the AC power to the AC power source 200. The converter 11 is controlled to perform the regeneration operation by turning on and off switching elements in accordance with the 120-degree conduction method when the DC link voltage detected by the DC link voltage detection unit 17 becomes equal to or higher than a predetermined voltage threshold. A converter control unit that controls the on and off switching of the switching elements in the converter 11 is not shown in the figure.

[0013] A breaker 102, an electromagnetic contactor 103, and a reactor 104 are provided on the AC power supply 200 side of the converter 11.

[0014] A capacitor 101 is connected to the DC link between the converter 11 and the inverter 12. The capacitor 101 may be referred to as a "DC link capacitor," "direct-current link capacitor," or "smoothing capacitor." The capacitor 101 has the function of suppressing oscillations in the DC output of the converter 11 and the function of storing DC power used by the inverter 12 to generate AC power. Examples of the capacitor 101 include an electrolytic capacitor and a film capacitor. A pre-charging circuit for pre-charging the capacitor 101 may be provided, but is not shown here.

[0015] The inverter 12 is connected to the converter 11 via a DC link. The inverter 12 is composed of a three-phase bridge circuit of switching elements and diodes connected in antiparallel to the switching elements. The switching elements provided in the inverter 12 are not shown. Examples of the switching elements include FETs, IGBTs, thyristors, GTOs, and transistors, but other switching elements may also be used. The inverter 12 receives PWM switching commands from the inverter control unit 40 and turns on and off the switching elements to perform a powering operation in which the inverter 12 converts DC power input from the DC link side into AC power for driving the motor 300 and outputs the AC power to the motor 300, and a regenerative operation in which the inverter 12 converts AC power regenerated by the motor 300 into DC power and returns the DC power to the DC link. As a result, the motor 300 is driven by the AC power output from the inverter 12.

[0016] Inverter control unit 40 executes control to drive motor 300. Inverter control unit 40 generates drive commands for controlling the rotational speed, position, or torque of the rotor of motor 300 based on the rotational speed of motor 300 (rotational speed feedback), the current flowing through the windings of motor 300 (current feedback), a rotational speed command, a torque command, a position command, an operation program for motor 300, and the like. Note that the configuration of inverter control unit 40 defined here is merely an example, and the configuration of inverter control unit 40 may be defined by including terms such as a position command generation unit, a torque command generation unit, a current control unit, a position control unit, and a torque control unit, for example.

[0017] The DC link voltage detector 17 detects the DC link voltage, which is the potential difference between the positive potential on the positive power line and the negative potential on the negative power line of the DC link between the converter 11 and the inverter 12.

[0018] The current detection unit 13 detects the value of the current input to the converter 11 or the value of the current output from the converter 11. The current input to or output from the converter 11 is a current that flows from the DC link side to the AC power supply 200 side or from the AC power supply 200 side to the DC link side via the converter 11. In the illustrated example, the current detection unit 13 detects the value of the current input to the converter 11.

[0019] The voltage detection unit 14 detects the voltage input to the converter 11. The voltage input to the converter 11 detected by the voltage detection unit 14 may be the line voltage of the power line between the breaker 102 and the electromagnetic contactor 103, or may be the phase voltage of the power line of each phase. In the illustrated example, the voltage detection unit 14 detects the line voltage of the power line between the breaker 102 and the electromagnetic contactor 103, as an example.

[0020] The distortion factor calculation unit 15 calculates the total harmonic distortion (THD) of the voltage (line voltage) detected by the voltage detection unit 14. The total harmonic distortion (THD) is an index that indicates the degree of harmonic components contained in the voltage. The higher the total harmonic distortion (THD), the more distorted the waveform is, and the lower the total harmonic distortion (THD), the closer the waveform is to a sine wave. The fundamental wave component of the voltage (one of the three line voltages) detected by the voltage detection unit 14 is defined as V1, and the kth-order (where k is an integer of 2 or more) harmonic component is defined as V2. k Then, the total harmonic distortion factor THD can be expressed as in Equation 1.

[0021]

[0022] During the regenerative operation of the converter 11, the power outage determination unit 16 determines whether or not a power outage has occurred on the AC power supply 200 side based on the current value detected by the current detection unit 13 and the total harmonic distortion THD. As described above, when the DC link voltage detected by the DC link voltage detection unit 17 becomes equal to or higher than a predetermined voltage threshold, the converter 11 is controlled to perform regenerative operation by turning on and off its switching elements. Therefore, whether the converter 11 is performing regenerative operation or rectification operation can be determined based on any one of the following: whether the DC link voltage detected by the DC link voltage detection unit 17 becomes equal to or higher than a predetermined voltage threshold; whether a regenerative command has been output from a converter control unit (not shown) to the converter 11; or whether the switching elements in the converter 11 are performing on and off operations.

[0023] When there is no power outage on the AC power supply 200 side, the motor 300 decelerates, generating regenerative power, and the converter 11 and inverter 12 each perform a regenerative operation. As shown by the thick dotted arrow in the figure, the regenerative power generated by the motor 300 flows toward the AC power supply 200 side via the inverter 12, DC link, and converter 11. As a result, the voltage on the AC input / output side of the converter 11 (for example, the line voltage of the power line between the breaker 102 and the electromagnetic contactor 103) is increased by the DC link voltage V DC A voltage related to

[0024] A power outage may occur in which the AC power supply 200 side is open at point A in the figure. When such a power outage occurs, the motor 300 decelerates, generating regenerative power, causing the converter 11 and the inverter 12 to perform regenerative operations. The regenerative power generated by the motor 300 flows into the capacitor 101 in the DC link via the inverter 12, as indicated by the bold solid arrow in the figure. However, since the converter 11 and the AC power supply 200 are separated, no power flows through the converter 11. As a result, the voltage on the AC input / output side of the converter 11 (for example, the line voltage of the power line between the breaker 102 and the electromagnetic contactor 103) is increased by the DC link voltage V DCappears, but no current flows from the converter 11 to the AC power supply 200. The regenerative power flows into the capacitor 101, and the DC link voltage V DC may rise, possibly causing an overvoltage alarm.

[0025] In this way, regardless of whether or not there is a power outage on the AC power supply 200 side, during the regenerative operation of the converter 11 and the inverter 12, the DC link voltage V DC Therefore, during the regenerative operation of the converter 11 and the inverter 12, it is not possible to determine whether or not a power outage has occurred on the AC power supply 200 side by using the magnitude of the voltage input to the converter 11 detected by the voltage detection unit 14. In contrast, in the first embodiment of the present disclosure, the total harmonic distortion (THD) of the voltage (line voltage) detected by the voltage detection unit 14 is used to determine whether or not a power outage has occurred on the AC power supply 200 side.

[0026] 2A is a diagram showing the line voltage waveforms on the AC input / output sides of a converter using a 120-degree conduction method during regenerative operation when the AC power supply side is not powered off. Also, FIG. 2B is a diagram showing the line voltage waveforms on the AC input / output sides of a converter using a 120-degree conduction method during regenerative operation when a power outage occurs on the AC power supply side. In FIGS. 2A and 2B, the line voltage V between the R-phase power line and the S-phase power line RS is shown by a solid line, and the line voltage V between the S-phase power line and the T-phase power line ST is shown by a dashed line, and the line voltage V between the T-phase power line and the R-phase power line TR is shown by a dashed line.

[0027] As shown in FIG. 2A , when there is no power outage on the AC power supply 200 side, the line voltage waveform on the AC input / output side of the converter using the 120-degree conduction method during regenerative operation is approximately sinusoidal, and the total harmonic distortion (THD) at this time is a value close to 0 (for example, THD = 0.009).

[0028] 2B , when a power outage occurs on the AC power supply 200 side, the line voltage waveform on the AC input / output sides of the converter using the 120-degree conduction method during regeneration is not sinusoidal but pulsed. In other words, the total harmonic distortion (THD) of the line voltage waveform on the AC input / output sides of the converter using the 120-degree conduction method during regeneration deteriorates (for example, THD = 0.31).

[0029] Therefore, in the first embodiment of the present disclosure, a comparison result between the total harmonic distortion THD during the regenerative operation of the converter 11 and a predetermined distortion threshold is used to determine whether or not there is a power outage on the AC power supply 200 side. The distortion threshold for determining whether or not there is a power outage on the AC power supply 200 side is set to, for example, about 0.1, but may be any other value.

[0030] Furthermore, when a power outage occurs on the AC power supply 200 side, the AC power supply 200 is disconnected from the motor drive device 1, and the value of the current input to the converter 11 or the value of the current output from the converter 11 to the AC power supply 200 side detected by the current detection unit 13 becomes approximately 0 (zero). Therefore, in the first embodiment of the present disclosure, the comparison result between the value (absolute value) of the current detected by the current detection unit 13 during the regenerative operation of the converter 11 and a predetermined current threshold is also used to determine whether or not a power outage has occurred on the AC power supply 200 side. The current threshold is set to, for example, approximately 0.1 mA, but may be any other value.

[0031] The distortion rate threshold and / or current threshold may be stored in a rewritable memory unit (not shown) and rewritable by an external device, so that even after the distortion rate threshold and / or current threshold have been set, they can be changed to appropriate values ​​as needed.

[0032] As described above, in the first embodiment of the present disclosure, when the value (absolute value) of the current detected by the current detection unit 13 is smaller than a predetermined current threshold and the total harmonic distortion factor THD is larger than a predetermined distortion factor threshold during regenerative operation of the converter 11, the power outage determination unit 16 determines that a power outage has occurred on the AC power supply 200 side. In the following description, the value of the current detected by the current detection unit 13 to be compared with the current threshold value is an absolute value.

[0033] When the power outage determination unit 16 determines that a power outage has occurred on the AC power supply 200 side, the power outage determination unit 16 outputs a power outage detection signal. When the power outage detection signal is output from the power outage determination unit 16, for example, control may be performed to discharge regenerative power returned to the DC link to a discharge circuit (not shown). Alternatively, when the power outage detection signal is output from the power outage determination unit 16, for example, a machine tool or robot equipped with the motor drive device 1 may be caused to perform a protective operation. Protective operations performed when a power outage occurs on the AC power supply 200 side include retraction control, braking control, and fall prevention control. Retraction control is a control that, in a machine tool in which a workpiece and a tool are numerically controlled in synchronization with each other, retracts the workpiece and the tool to a position where they do not interfere with each other while maintaining synchronization when a power outage occurs on the AC power supply 200 side. This prevents damage due to missynchronization between the workpiece and the tool. Braking control is a control that decelerates and stops the feed axis to prevent collisions due to coasting of the feed axis in a machine tool in which the inertial distance of the feed axis is a problem when a power outage occurs on the AC power supply 200 side. The fall prevention control is a control for maintaining the current position of a machine equipped with a gravity shaft so that the gravity shaft does not fall and damage the workpiece or tool when a power outage occurs on the AC power supply 200 side. The control described here is an example, and other controls may be performed when a power outage occurs on the AC power supply 200 side. Power for performing the control performed when a power outage occurs on the AC power supply 200 side is secured, for example, by a backup power supply or a power system separate from the power system on the AC power supply 200 side. For example, an energy buffer such as a capacitor that stores power supplied from the power system on the AC power supply 200 side may be used as the backup power supply.

[0034] The power outage determination unit 16 may be provided inside the converter 11 , inside a converter control unit that controls the converter 11 , or inside the inverter control unit 40 .

[0035] FIG. 3 is a flowchart showing the operation flow of a power failure detection process in the motor drive device according to the first embodiment of the present disclosure.

[0036] While the motor drive device 1 is operating, in step S101, the power failure determination unit 16 determines whether the converter 11 is in regenerative operation. Whether the converter 11 is in regenerative operation or rectifying operation can be determined based on whether the DC link voltage detected by the DC link voltage detection unit 17 is equal to or higher than a predetermined voltage threshold, whether a regenerative command has been output from a converter control unit (not shown) to the converter 11, or whether a switching element in the converter 11 is performing an on / off operation.

[0037] If it is determined in step S101 that converter 11 is in a regenerative operation, current detection unit 13 detects the value of the current input to converter 11 or the value of the current output from converter 11 in step S102.

[0038] In step S103, the voltage detection unit 14 detects the voltage input to the converter 11. The order of the processing in step S102 and the processing in step S103 may be reversed.

[0039] In step S104 , the distortion factor calculation unit 15 calculates the total harmonic distortion factor THD of the voltage detected by the voltage detection unit 14 .

[0040] In step S105, the power outage determination unit 16 determines whether or not the value (absolute value) of the current detected by the current detection unit 13 is smaller than a predetermined current threshold value.

[0041] If it is not determined in step S105 that the value (absolute value) of the current detected by the current detection unit 13 is smaller than the predetermined current threshold, in step S108, the power outage determination unit 16 determines that a power outage has not occurred on the AC power supply 200 side. Then, the process returns to step S101.

[0042] If it is determined in step S105 that the value (absolute value) of the current detected by the current detection unit 13 is smaller than the predetermined current threshold, in step S106, the power outage determination unit 16 determines whether the total harmonic distortion factor THD is greater than the predetermined distortion factor threshold.

[0043] If it is not determined in step S106 that the total harmonic distortion factor THD is greater than the predetermined distortion factor threshold, in step S108, the power outage determination unit 16 determines that a power outage has not occurred on the side of the AC power supply 200. Then, the process returns to step S101.

[0044] If it is determined in step S106 that the total harmonic distortion THD is greater than the predetermined distortion threshold, the power outage determination unit 16 determines in step S107 that a power outage has occurred on the AC power supply 200 side, and outputs a power outage detection signal. Then, the process ends.

[0045] The series of processes from steps S101 to S108 is repeatedly executed at a predetermined control period (for example, 10 ms), which may be changed as appropriate.

[0046] Second Embodiment of the Present Disclosure FIG. 4 is a circuit diagram showing a motor drive device according to a second embodiment of the present disclosure.

[0047] A motor drive device 2 according to a second embodiment of the present disclosure includes a converter 11, an inverter 12, a current detection unit 13, a DC link voltage detection unit 17, a storage unit 21, a regenerative power acquisition unit 22, a temperature calculation unit 23, a temperature determination unit 24, a power outage determination unit 27, and an inverter control unit 40. The motor drive device 1 also includes a capacitor 101, a breaker 102, an electromagnetic contactor 103, and a reactor 104. Note that, in order to enable the current detection unit 13, the DC link voltage detection unit 17, the regenerative power acquisition unit 22, the temperature calculation unit 23, the temperature determination unit 24, the power outage determination unit 27, and the inverter control unit 40 to operate even in the event of a power outage on the AC power supply 200 side, it is preferable that a power supply for supplying power to these units be provided on a system separate from the AC power supply 200.

[0048] The converter 11, the inverter 12, the current detection unit 13, the inverter control unit 40, the DC link voltage detection unit 17, the capacitor 101, the breaker 102, the electromagnetic contactor 103, and the reactor 104 are as described in the first embodiment.

[0049] When there is no power outage on the AC power supply 200 side, the motor 300 decelerates, generating regenerative power, causing the converter 11 and the inverter 12 to each perform a regenerative operation. As indicated by the thick dotted arrow in the figure, the regenerative power generated by the motor 300 flows toward the AC power supply 200 side via the inverter 12, the DC link, and the converter 11. When regenerative power (regenerative current) flows through a switching element in the converter 11, the switching element generates heat. In a second embodiment of the present disclosure, the temperature of the switching element when there is no power outage on the AC power supply 200 side is used as a reference, and whether or not a power outage has occurred on the AC power supply 200 side is determined based on how much the temperature deviates from this reference temperature.

[0050] In an experimental stage prior to normal operation of motor drive device 1, a table showing the relationship between the value of regenerative power of converter 11 acquired in advance when there is no power outage on the AC power supply 200 side and the degree of temperature rise of the switching elements in converter 11 acquired in advance corresponding to the time point at which the regenerative power was acquired is stored in storage unit 21. The table stored in storage unit 21 specifies an approximation curve determined by the value of regenerative power of converter 11 and the degree of temperature rise of the switching elements in converter 11 corresponding to the regenerative power.

[0051] The relationship between the value of the regenerative power of converter 11 and the corresponding degree of temperature rise of the switching elements in converter 11 can be obtained in the following experimental stage before the normal operation of motor drive device 1. Converter 11 is actually operated in regenerative mode under various regenerative power outputs without a power outage on the AC power supply 200 side. The degree of temperature rise of the switching elements during regenerative operation for a predetermined period of time is measured multiple times for each magnitude of regenerative power. An approximate curve showing the relationship between the value of regenerative power and the degree of temperature rise of the switching elements is then created. A table consisting of these approximate curves is stored in storage unit 21. The regenerative power of converter 11 may be calculated based on the current and voltage measured for converter 11 when converter 11 is actually operated in regenerative mode under various conditions without a power outage on the AC power supply 200 side, or it may be measured using a wattmeter.

[0052] On the other hand, the regenerative power acquisition unit 22, the temperature calculation unit 23, the temperature determination unit 24, and the power outage determination unit 27 operate during normal operation of the motor drive device 1.

[0053] The regenerative power acquisition unit 22 acquires the value of the regenerative power of the converter 11. The value of the regenerative power of the converter 11 may be acquired by calculation based on the current and voltage measured for the converter 11, or may be acquired using a power meter.

[0054] The temperature calculation unit 23 calculates an estimated temperature rise value of the switching element using the value of the current detected by the current detection unit 13 during the regenerative operation of the converter 11. For example, if the switching element is an IGBT, the degree of temperature rise ΔT between the base and chip of the IGBT at time t is C [℃] is the thermal resistance K [℃ / A], and the thermal time constant τ C [sec] and the value (instantaneous value) of the current detected by the current detection unit 13 I [A], it can be expressed as in Equation 2.

[0055]

[0056] Then, the temperature calculation unit 23 calculates an estimated temperature rise ΔT of the switching element from the start of the regenerative operation of the converter 11. C Calculate the estimated temperature rise ΔT C is the degree of increase in the temperature estimate over a given time period.

[0057] The temperature determination unit 24 refers to the table stored in the storage unit 21 and calculates the temperature rise estimated value ΔT for the regenerative power acquired by the regenerative power acquisition unit 22 during the regenerative operation of the converter 11. C [°C] is normal or abnormal. When there is no power outage on the AC power supply 200 side, as the regenerative power passing through the converter 11 increases, the current flowing through the converter 11 increases, which increases the current loss in the switching elements and the generation of heat. However, when a power outage occurs on the AC power supply 200 side, no regenerative power flows through the converter 11, and therefore no current flows through the converter 11, so the switching elements do not generate heat. The temperature determination unit 24 calculates the estimated temperature rise ΔT for the regenerative power acquired by the regenerative power acquisition unit 22 during the regenerative operation of the converter 11. C [°C] deviates from the degree of temperature rise corresponding to the regenerative current specified in the table stored in the storage unit 21, the estimated temperature rise value ΔT C [℃] is judged to be abnormal. More details are as follows.

[0058] As described above, the table stored in the storage unit 21 defines an approximate curve showing the relationship between the value of regenerative power and the degree of temperature rise of the switching element. The temperature determination unit 24 determines the estimated temperature rise ΔT C [°C] with an approximate curve defined in a table stored in the storage unit 21. As a result of the comparison, the temperature determination unit 12 determines the estimated temperature rise ΔT C If the temperature rise estimate ΔT is within a range of, for example, ±10%, which includes the approximate curve, C For example, the estimated temperature rise ΔT C [°C] is compared with the degree of temperature rise of the switching element on the approximate curve corresponding to the value of the regenerative power, and if it falls within the range of ±10%, the estimated temperature rise value ΔT C [°C] is normal. Furthermore, the temperature determination unit 12 determines that the estimated temperature rise ΔT C If the temperature rise estimate ΔT [°C] does not fall within the range of, for example, ±10% that includes the approximate curve, C For example, the temperature rise estimated value ΔT C [°C] is compared with the degree of temperature rise of the switching element on the approximation curve corresponding to the value of the regenerative power, and if it does not fall within the range of ±10%, the estimated temperature rise value ΔT C [°C] is determined to be abnormal. Note that the value of "±10%" given here is merely an example, and other values ​​may also be used.

[0059] The power failure determination unit 27 determines whether or not the value (absolute value) of the current detected by the current detection unit 13 is smaller than a predetermined current threshold value during the regenerative operation of the converter 11 and whether or not the temperature determination unit 24 determines whether or not the temperature rise estimated value ΔT CIf it is determined that the temperature [°C] is abnormal, it is determined that a power outage has occurred on the AC power supply 200 side. When the power outage determination unit 27 determines that a power outage has occurred on the AC power supply 200 side, a power outage detection signal is output from the power outage determination unit 27. The various operations after the power outage detection signal is output from the power outage determination unit 27 are as described in the first embodiment.

[0060] The power outage determination unit 27 may be provided inside the converter 11 , inside a converter control unit that controls the converter 11 , or inside the inverter control unit 40 .

[0061] FIG. 5 is a flowchart showing the operation flow of a power failure detection process in the motor drive device according to the second embodiment of the present disclosure.

[0062] When the motor drive device 2 is operating, the current detection unit 13 detects the value of the current input to the converter 11 or the value of the current output from the converter 11 in step S201.

[0063] In step S202, the temperature calculation unit 23 calculates an estimated temperature rise ΔT of the switching element using the value of the current detected by the current detection unit 13. C Calculate [℃].

[0064] In step S203, power failure determination unit 27 determines whether converter 11 is in a regenerative operation.

[0065] If it is not determined in step S203 that converter 11 is in a regenerative operation (i.e., is in a rectifying operation), the process returns to step S201.

[0066] If it is determined in step S203 that the converter 11 is in a regenerative operation, the temperature determination unit 24 determines in step S204 the estimated temperature rise ΔT C Save [℃].

[0067] In step S205 , the current detection unit 13 detects the value of the current input to the converter 11 or the value of the current output from the converter 11 .

[0068] In step S206 , the regenerative power acquisition unit 22 acquires the value of the regenerative power of the converter 11 .

[0069] In step S207, the temperature calculation unit 23 calculates an estimated temperature rise ΔT of the switching element using the value of the current detected by the current detection unit 13 in step S205. C Calculate [℃].

[0070] In step S208, the power outage determination unit 27 determines whether or not the value (absolute value) of the current detected by the current detection unit 13 is smaller than a predetermined current threshold value.

[0071] If it is not determined in step S208 that the value (absolute value) of the current detected by the current detection unit 13 is smaller than the predetermined current threshold, in step S211, the power outage determination unit 27 determines that a power outage has not occurred on the AC power supply 200 side. Then, the process returns to step S203.

[0072] If it is determined in step S208 that the value (absolute value) of the current detected by the current detection unit 13 is smaller than the predetermined current threshold, in step S209, the power outage determination unit 27 refers to the table stored in the storage unit 21 and determines whether the temperature rise estimated value ΔT calculated in step S207 is smaller than the predetermined current threshold. C Determine whether [℃] is normal or abnormal.

[0073] In step S209, the estimated temperature rise ΔT C If the temperature [°C] is not determined to be abnormal (i.e., normal), in step S211, the power outage determination unit 27 determines that a power outage has not occurred on the side of the AC power supply 200. Then, the process returns to step S203.

[0074] In step S209, the estimated temperature rise ΔT C If it is determined that the temperature [°C] is abnormal, in step S210, the power outage determination unit 27 determines that a power outage has occurred on the AC power supply 200 side, and outputs a power outage detection signal. Then, the process ends.

[0075] The series of processes from steps S201 to S211 is repeatedly executed at a predetermined control period (for example, 10 ms), which may be changed as appropriate.

[0076] 6 is a circuit diagram showing a motor drive device according to a third embodiment of the present disclosure. In the second embodiment of the present disclosure, the temperature of the switching elements in the converter 11 is obtained by calculation, but in the third embodiment of the present disclosure, the temperature of the switching elements in the converter 11 is obtained by actual measurement.

[0077] A motor drive device 3 according to a third embodiment of the present disclosure includes a converter 11, an inverter 12, a current detection unit 13, a DC link voltage detection unit 17, a storage unit 21, a regenerative power acquisition unit 22, a temperature detection unit 25, a temperature determination unit 26, a power outage determination unit 28, and an inverter control unit 40. The motor drive device 1 also includes a capacitor 101, a breaker 102, an electromagnetic contactor 103, and a reactor 104. Note that, in order to enable the current detection unit 13, the DC link voltage detection unit 17, the regenerative power acquisition unit 22, the temperature detection unit 25, the temperature determination unit 26, the power outage determination unit 28, and the inverter control unit 40 to operate even in the event of a power outage on the AC power supply 200 side, it is preferable that a power supply for supplying power to these units be provided on a system separate from the AC power supply 200.

[0078] The converter 11, the inverter 12, the current detector 13, the DC link voltage detector 17, the inverter controller 40, the capacitor 101, the breaker 102, the electromagnetic contactor 103, and the reactor 104 are as described in the first embodiment. The storage unit 21 and the regenerative power acquisition unit 22 are as described in the second embodiment.

[0079] The temperature detection unit 25 acquires the temperature detection value of the switching element from a temperature sensor provided near at least one of the switching elements in the converter 11. When the temperature detection values ​​are acquired from the temperature sensors provided for each of the multiple switching elements, the average value is calculated and used as the temperature detection value acquired by the temperature detection unit 25. Then, the temperature calculation unit 23 calculates the degree of increase ΔT of the temperature detection value of the switching element from the start of the regenerative operation of the converter 11. C Calculate the degree of rise ΔT Cis the difference between the temperature detection value at a certain point in time and the temperature detection value at the start of the regenerative operation of the converter 11.

[0080] The temperature determination unit 26 refers to the table stored in the storage unit 21 and determines the degree of increase ΔT of the temperature detection value relative to the regenerative power acquired by the regenerative power acquisition unit 22 during the regenerative operation of the converter 11. C [°C] is normal or abnormal. When there is no power outage on the AC power supply 200 side, as the regenerative power passing through the converter 11 increases, the current flowing through the converter 11 increases, which increases the current loss in the switching elements and the generation of heat. However, when a power outage occurs on the AC power supply 200 side, no regenerative power flows through the converter 11, and therefore no current flows through the converter 11, so the switching elements do not generate heat. The temperature determination unit 24 calculates the degree of increase ΔT of the temperature detection value relative to the regenerative power acquired by the regenerative power acquisition unit 22 during the regenerative operation of the converter 11. C If the temperature detection value [°C] deviates from the degree of increase in the temperature detection value corresponding to the regenerative current specified in the table stored in the storage unit 21, the degree of increase in the temperature detection value ΔT C [℃] is judged to be abnormal. More details are as follows.

[0081] As described above, the table stored in the storage unit 21 defines an approximate curve showing the relationship between the value of regenerative power and the degree of temperature rise of the switching element. The temperature determination unit 24 determines the degree of rise ΔT of the temperature detection value relative to the regenerative power acquired by the regenerative power acquisition unit 22. C The temperature determination unit 12 compares the temperature [°C] with the approximate curve defined in the table stored in the storage unit 21. As a result of the comparison, the temperature determination unit 12 determines the degree of increase ΔT C If [°C] falls within a range that includes the approximate curve, for example, within ±10%, the degree of increase in the temperature detection value ΔT C For example, the degree of increase ΔT of the temperature detection value with respect to the value of the regenerative power acquired by the regenerative power acquisition unit 22 is determined to be normal. C[°C] is compared with the degree of temperature rise of the switching element on the approximate curve corresponding to the value of the regenerative power, and if it falls within the range of ±10%, the degree of rise in the temperature detection value ΔT C [°C] is normal. Furthermore, the temperature determination unit 12 determines, as a result of the comparison, the degree of increase ΔT C If the temperature [°C] does not fall within the range of, for example, ±10%, which includes the approximate curve, the degree of increase in the temperature detection value ΔT C For example, the degree of increase ΔT of the temperature detection value with respect to the value of the regenerative power acquired by the regenerative power acquisition unit 22 is determined to be abnormal. C [°C] is compared with the degree of temperature rise of the switching element on the approximate curve corresponding to the value of the regenerative power, and if it does not fall within the range of ±10%, the degree of rise in the temperature detection value ΔT C [°C] is determined to be abnormal. Note that the value of "±10%" given here is merely an example, and other values ​​may also be used.

[0082] The power failure determination unit 28 determines whether or not the value (absolute value) of the current detected by the current detection unit 13 is smaller than a predetermined current threshold value during the regenerative operation of the converter 11 and whether or not the degree of increase in the temperature detection value by the temperature determination unit 26 is ΔT C If it is determined that the temperature [°C] is abnormal, it is determined that a power outage has occurred on the AC power supply 200 side. If the power outage determination unit 28 determines that a power outage has occurred on the AC power supply 200 side, a power outage detection signal is output from the power outage determination unit 28. The various operations after the power outage detection signal is output from the power outage determination unit 27 are as described in the first embodiment.

[0083] The power outage determination unit 28 may be provided inside the converter 11 , inside a converter control unit that controls the converter 11 , or inside the inverter control unit 40 .

[0084] FIG. 7 is a flowchart showing the operation flow of a power failure detection process in the motor drive device according to the third embodiment of the present disclosure.

[0085] When the motor drive device 3 is operating, in step S301, the temperature detection unit 25 acquires a temperature detection value of the switching element from a temperature sensor provided near at least one of the switching elements in the converter 11.

[0086] In step S302, power failure determination unit 28 determines whether converter 11 is in a regenerative operation.

[0087] If it is not determined in step S302 that converter 11 is in a regenerative operation (i.e., is in a rectifying operation), the process returns to step S301.

[0088] If it is determined in step S302 that converter 11 is in a regenerative operation, temperature determination unit 26 stores the temperature detection value at that time in step S303.

[0089] In step S304 , the current detection unit 13 detects the value of the current input to the converter 11 or the value of the current output from the converter 11 .

[0090] In step S305 , the regenerative power acquisition unit 22 acquires the value of the regenerative power of the converter 11 .

[0091] In step S306 , the temperature detection unit 25 acquires a detected temperature value of at least one of the switching elements in the converter 11 from a temperature sensor provided near the switching element.

[0092] In step S307, the temperature detection unit 25 calculates the difference between the detected temperature value acquired in step S306 and the detected temperature value at the start of the regenerative operation of the converter 11 stored in step S303, and calculates this difference as the degree of increase ΔT C Output as [℃].

[0093] In step S308, the power outage determination unit 28 determines whether or not the value (absolute value) of the current detected by the current detection unit 13 is smaller than a predetermined current threshold value.

[0094] If it is not determined in step S308 that the value (absolute value) of the current detected by the current detection unit 13 is smaller than the predetermined current threshold, in step S311, the power outage determination unit 28 determines that a power outage has not occurred on the side of the AC power supply 200. Then, the process returns to step S302.

[0095] If it is determined in step S308 that the value (absolute value) of the current detected by the current detection unit 13 is smaller than the predetermined current threshold, in step S309, the power outage determination unit 28 refers to the table stored in the storage unit 21 and calculates the degree of increase ΔT C Determine whether [℃] is normal or abnormal.

[0096] In step S309, the degree of increase in the temperature detection value ΔT C If the temperature [°C] is not determined to be abnormal (i.e., normal), in step S311, the power outage determination unit 28 determines that a power outage has not occurred on the side of the AC power supply 200. Then, the process returns to step S302.

[0097] In step S309, the degree of increase in the temperature detection value ΔT C If it is determined that the temperature [°C] is abnormal, then in step S310, the power outage determination unit 28 determines that a power outage has occurred on the AC power supply 200 side, and outputs a power outage detection signal. Then, the process ends.

[0098] The series of processes from steps S301 to S311 is repeatedly executed at a predetermined control period (for example, 10 ms), which may be changed as appropriate.

[0099] <Fourth Embodiment of the Present Disclosure> Fig. 8 is a circuit diagram showing a motor drive device according to a fourth embodiment of the present disclosure. The fourth embodiment of the present disclosure is a combination of the first embodiment and the second embodiment.

[0100] A motor drive device 4 according to a fourth embodiment of the present disclosure includes a converter 11, an inverter 12, a current detection unit 13, a voltage detection unit 14, a distortion factor calculation unit 15, a DC link voltage detection unit 17, a storage unit 21, a regenerative power acquisition unit 22, a temperature calculation unit 23, a temperature determination unit 24, a power outage determination unit 29, and an inverter control unit 40. The motor drive device 4 also includes a capacitor 101, a breaker 102, an electromagnetic contactor 103, and a reactor 104. Note that, in order to enable the current detection unit 13, the voltage detection unit 14, the distortion factor calculation unit 15, the DC link voltage detection unit 17, the regenerative power acquisition unit 22, the temperature calculation unit 23, the temperature determination unit 24, the power outage determination unit 29, and the inverter control unit 40 to operate even in the event of a power outage on the AC power supply 200 side, it is preferable that a power supply for supplying power to these units be provided on a system separate from the AC power supply 200.

[0101] The converter 11, inverter 12, current detection unit 13, voltage detection unit 14, distortion factor calculation unit 15, DC link voltage detection unit 17, inverter control unit 40, capacitor 101, breaker 102, electromagnetic contactor 103, and reactor 104 are as described in the first embodiment. The storage unit 21, regenerative power acquisition unit 22, temperature calculation unit 23, and temperature determination unit 24 are as described in the second embodiment.

[0102] The fourth embodiment of the present disclosure is a combination of the first embodiment in which a power outage determination is performed using the total harmonic distortion factor THD and the second embodiment in which a power outage determination is performed using a temperature rise estimated value. In the fourth embodiment of the present disclosure, the power outage determination unit 29 determines whether or not a power outage has occurred when, during regeneration operation of the converter 11, the value (absolute value) of the current detected by the current detection unit 13 is smaller than a predetermined current threshold value and the total harmonic distortion factor THD is larger than a predetermined distortion factor threshold value, and when, during regeneration operation of the converter 11, the value (absolute value) of the current detected by the current detection unit 13 is smaller than the predetermined current threshold value and the temperature determination unit 24 determines whether or not a power outage has occurred. C When at least one of the cases where it is determined that the temperature [°C] is abnormal is met, it is determined that a power outage has occurred on the AC power supply 200 side. There are two modes of power outage determination processing by the power outage determination unit 29.

[0103] In the power outage determination process of the power outage determination unit 29 according to the first embodiment, when the value (absolute value) of the current detected by the current detection unit 13 is smaller than a predetermined current threshold and the total harmonic distortion factor THD is larger than a predetermined distortion factor threshold, or when the value (absolute value) of the current detected by the current detection unit 13 is smaller than a predetermined current threshold and the temperature determination unit 24 determines that the temperature rise estimated value ΔT C If it is determined that the temperature [°C] is abnormal, it is determined that a power outage has occurred on the side of AC power supply 200. That is, in the power outage determination process of power outage determination unit 29 according to the first embodiment, if it is determined that a power outage has occurred in either the power outage determination process using the total harmonic distortion THD or the power outage determination process using the temperature rise estimated value, it is determined that a power outage has occurred.

[0104] In the power outage determination process of the power outage determination unit 29 according to the second embodiment, the value (absolute value) of the current detected by the current detection unit 13 is smaller than a predetermined current threshold, and the total harmonic distortion factor THD is larger than a predetermined distortion factor threshold, and the temperature determination unit 24 determines the temperature rise estimated value ΔT C If it is determined that the temperature [°C] is abnormal, it is determined that a power outage has occurred on the AC power supply 200 side. That is, in the power outage determination process of the power outage determination unit 29 according to the second embodiment, if it is determined that a power outage has occurred in both the power outage determination process using the total harmonic distortion THD and the power outage determination process using the temperature rise estimated value, it is determined that a power outage has occurred.

[0105] The power outage determination unit 29 may be provided inside the converter 11 , inside a converter control unit that controls the converter 11 , or inside the inverter control unit 40 .

[0106] Fig. 9 is a flowchart showing an operation flow of power failure detection processing in the motor drive device according to the fourth embodiment of the present disclosure. Fig. 10 is a flowchart showing an operation flow when power failure determination processing according to a first mode is executed in the power failure detection processing in the motor drive device according to the fourth embodiment of the present disclosure. Fig. 11 is a flowchart showing an operation flow when power failure determination processing according to a second mode is executed in the power failure detection processing in the motor drive device according to the fourth embodiment of the present disclosure.

[0107] When the motor drive device 4 is operating, the current detection unit 13 detects the value of the current input to the converter 11 or the value of the current output from the converter 11 in step S401.

[0108] In step S402, the temperature calculation unit 23 calculates an estimated temperature rise ΔT of the switching element using the value of the current detected by the current detection unit 13. C Calculate [℃].

[0109] In step S403, the power outage determination unit 16 determines whether the converter 11 is in a regenerative operation.

[0110] If it is not determined in step S403 that converter 11 is in a regenerative operation (i.e., is in a rectifying operation), the process returns to step S401.

[0111] If it is determined in step S403 that the converter 11 is in a regenerative operation, the temperature determination unit 24 determines in step S404 the estimated temperature rise ΔT C Save [℃].

[0112] In step S405 , the current detection unit 13 detects the value of the current input to the converter 11 or the value of the current output from the converter 11 .

[0113] In step S406 , the voltage detection unit 14 detects the voltage input to the converter 11 .

[0114] In step S407, the regenerative power acquisition unit 22 acquires the value of the regenerative power of the converter 11. The order of the processing of step S405, the processing of step S406, and the processing of step S407 may be reversed.

[0115] In step S408, the temperature calculation unit 23 calculates an estimated temperature rise ΔT of the switching element using the value of the current detected by the current detection unit 13 in step S405. C Calculate [℃].

[0116] In step S409, the distortion factor calculation unit 15 calculates the total harmonic distortion factor THD of the voltage detected by the voltage detection unit 14. Thereafter, if the power outage determination unit 29 performs the power outage determination process according to the first mode, the process proceeds to step S410 in Fig. 10, and if the power outage determination unit 29 performs the power outage determination process according to the second mode, the process proceeds to step S415 in Fig. 11.

[0117] In the power outage determination process of the power outage determination unit 29 in the first form, in step S410 of Figure 10, the power outage determination unit 29 determines whether the value (absolute value) of the current detected by the current detection unit 13 is smaller than a predetermined current threshold.

[0118] If it is not determined in step S410 that the value (absolute value) of the current detected by the current detection unit 13 is smaller than the predetermined current threshold, in step S414, the power outage determination unit 29 determines that a power outage has not occurred on the AC power supply 200 side. Then, the process returns to step S403 in FIG. 9 .

[0119] If it is determined in step S410 that the value (absolute value) of the current detected by the current detection unit 13 is smaller than the predetermined current threshold, in step S411, the power outage determination unit 29 refers to the table stored in the storage unit 21 and calculates the estimated temperature rise ΔT calculated in step S408. C Determine whether [℃] is normal or abnormal.

[0120] In step S411, the estimated temperature rise ΔT C If the temperature [°C] is not determined to be abnormal (i.e., normal), in step S413, the power outage determination unit 29 determines whether the total harmonic distortion factor THD is greater than a predetermined distortion factor threshold value.

[0121] If it is not determined in step S413 that the total harmonic distortion factor THD is greater than the predetermined distortion factor threshold, in step S414, the power outage determination unit 29 determines that a power outage has not occurred on the side of the AC power supply 200. Then, the process returns to step S403 in FIG. 9 .

[0122] If it is determined in step S413 that the total harmonic distortion THD is greater than the predetermined distortion threshold, the power outage determination unit 29 determines in step S412 that a power outage has occurred on the AC power supply 200 side, and outputs a power outage detection signal. Then, the process ends.

[0123] In step S411, the estimated temperature rise ΔT C If it is determined that the temperature [°C] is abnormal, then in step S412, the power outage determination unit 29 determines that a power outage has occurred on the AC power supply 200 side, and outputs a power outage detection signal. Then, the process ends.

[0124] In the power outage determination process of the power outage determination unit 29 in the second form, in step S415 of Figure 11, the power outage determination unit 29 determines whether the value (absolute value) of the current detected by the current detection unit 13 is smaller than a predetermined current threshold.

[0125] If it is not determined in step S415 that the value (absolute value) of the current detected by the current detection unit 13 is smaller than the predetermined current threshold, in step S419, the power outage determination unit 29 determines that a power outage has not occurred on the side of the AC power supply 200. Then, the process returns to step S403 in FIG. 9 .

[0126] If it is determined in step S415 that the value (absolute value) of the current detected by the current detection unit 13 is smaller than the predetermined current threshold, in step S416, the power outage determination unit 29 refers to the table stored in the storage unit 21 and calculates the estimated temperature rise ΔT calculated in step S408. C Determine whether [℃] is normal or abnormal.

[0127] In step S416, the estimated temperature rise ΔT C If the temperature [°C] is not determined to be abnormal (i.e., normal), in step S419, the power outage determination unit 29 determines that a power outage has not occurred on the side of the AC power supply 200. Then, the process returns to step S403 in FIG. 9 .

[0128] In step S416, the degree of temperature rise estimated value ΔT CIf the temperature [°C] is determined to be abnormal, in step S417, the power outage determination unit 29 determines whether the total harmonic distortion THD is greater than a predetermined distortion threshold value. The order of the processing in step S416 and the processing in step S417 may be reversed.

[0129] If it is not determined in step S417 that the total harmonic distortion factor THD is greater than the predetermined distortion factor threshold, in step S419, the power outage determination unit 29 determines that a power outage has not occurred on the side of the AC power supply 200. Then, the process returns to step S403 in FIG. 9 .

[0130] If it is determined in step S417 that the total harmonic distortion THD is greater than the predetermined distortion threshold, in step S418, the power outage determination unit 29 determines that a power outage has occurred on the AC power supply 200 side, and outputs a power outage detection signal. Then, the process ends.

[0131] The series of processes in steps S401 to S414, as well as the series of processes in steps S401 to S409 and S415 to S419, are repeatedly executed at a predetermined control period (for example, 10 ms). The control period may be changed as appropriate.

[0132] Fifth Embodiment of the Present Disclosure Fig. 12 is a circuit diagram showing a motor drive device according to a fifth embodiment of the present disclosure. The fifth embodiment of the present disclosure is a combination of the first embodiment and the third embodiment.

[0133] A motor drive device 5 according to a fifth embodiment of the present disclosure includes a converter 11, an inverter 12, a current detection unit 13, a voltage detection unit 14, a distortion factor calculation unit 15, a DC link voltage detection unit 17, a storage unit 21, a regenerative power acquisition unit 22, a temperature detection unit 25, a temperature determination unit 26, a power failure determination unit 30, and an inverter control unit 40. The motor drive device 5 also includes a capacitor 101, a breaker 102, an electromagnetic contactor 103, and a reactor 104. Note that, in order to enable the current detection unit 13, the voltage detection unit 14, the distortion factor calculation unit 15, the DC link voltage detection unit 17, the regenerative power acquisition unit 22, the temperature detection unit 25, the temperature determination unit 26, the power failure determination unit 30, and the inverter control unit 40 to operate even in the event of a power failure on the AC power supply 200 side, it is preferable that a power supply for supplying power to these units be provided on a system separate from the AC power supply 200.

[0134] The converter 11, inverter 12, current detection unit 13, voltage detection unit 14, distortion factor calculation unit 15, DC link voltage detection unit 17, inverter control unit 40, capacitor 101, breaker 102, electromagnetic contactor 103, and reactor 104 are as described in the first embodiment. The storage unit 21, regenerative power acquisition unit 22, temperature detection unit 25, and temperature determination unit 26 are as described in the third embodiment.

[0135] A fifth embodiment of the present disclosure is a combination of the first embodiment, which performs a power outage determination using the total harmonic distortion (THD), and the third embodiment, which performs a power outage determination using a temperature detection value. In the fifth embodiment of the present disclosure, the power outage determination unit 30 determines that a power outage has occurred on the AC power supply 200 side when at least one of the following occurs during regenerative operation of the converter 11: the value (absolute value) of the current detected by the current detection unit 13 is smaller than a predetermined current threshold and the total harmonic distortion (THD) is greater than a predetermined distortion threshold; or the value (absolute value) of the current detected by the current detection unit 13 is smaller than the predetermined current threshold and the temperature determination unit 26 determines that the degree of increase in the temperature detection value is abnormal. There are two types of power outage determination processing by the power outage determination unit 30.

[0136] In the power outage determination process of the power outage determination unit 30 according to the first embodiment, if the value (absolute value) of the current detected by the current detection unit 13 is smaller than a predetermined current threshold and the total harmonic distortion factor THD is larger than a predetermined distortion factor threshold, or if the value (absolute value) of the current detected by the current detection unit 13 is smaller than a predetermined current threshold and the temperature determination unit 26 determines the degree of increase in the temperature detection value ΔT C If it is determined that the temperature [°C] is abnormal, it is determined that a power outage has occurred on the side of AC power supply 200. That is, in the power outage determination process of power outage determination unit 30 according to the first embodiment, if it is determined that a power outage has occurred in either the power outage determination process using the total harmonic distortion THD or the power outage determination process using the temperature detection value, it is determined that a power outage has occurred.

[0137] In the power outage determination process of the power outage determination unit 30 according to the second embodiment, the current value (absolute value) detected by the current detection unit 13 is smaller than a predetermined current threshold, the total harmonic distortion factor THD is larger than a predetermined distortion factor threshold, and the temperature determination unit 26 determines the degree of increase in the temperature detection value ΔT C If it is determined that the temperature [°C] is abnormal, it is determined that a power outage has occurred on the side of the AC power supply 200. That is, in the power outage determination process of the power outage determination unit 30 according to the second embodiment, if it is determined that a power outage has occurred in both the power outage determination process using the total harmonic distortion THD and the power outage determination process using the temperature detection value, it is determined that a power outage has occurred.

[0138] The power outage determination unit 30 may be provided inside the converter 11 , inside a converter control unit that controls the converter 11 , or inside the inverter control unit 40 .

[0139] Fig. 13 is a flowchart showing an operation flow of power failure detection processing in the motor drive device according to the fifth embodiment of the present disclosure. Fig. 14 is a flowchart showing an operation flow when power failure determination processing according to a first form is executed in the power failure detection processing in the motor drive device according to the fifth embodiment of the present disclosure. Fig. 15 is a flowchart showing an operation flow when power failure determination processing according to a second form is executed in the power failure detection processing in the motor drive device according to the fifth embodiment of the present disclosure.

[0140] When the motor drive device 5 is operating, in step S501, the temperature detection unit 25 acquires a temperature detection value of the switching element from a temperature sensor provided near at least one of the switching elements in the converter 11.

[0141] In step S502, the power outage determination unit 16 determines whether the converter 11 is in a regenerative operation.

[0142] If it is not determined in step S502 that converter 11 is in a regenerative operation (i.e., is in a rectifying operation), the process returns to step S501.

[0143] If it is determined in step S502 that converter 11 is in a regenerative operation, temperature determination unit 26 stores the temperature detection value at that time in step S503.

[0144] In step S504 , the current detection unit 13 detects the value of the current input to the converter 11 or the value of the current output from the converter 11 .

[0145] In step S505 , the voltage detection unit 14 detects the voltage input to the converter 11 .

[0146] In step S506, the regenerative power acquisition unit 22 acquires the value of the regenerative power of the converter 11. The order of the processing of step S504, the processing of step S505, and the processing of step S506 may be reversed.

[0147] In step S507 , the temperature detection unit 25 acquires a detected temperature value of at least one of the switching elements in the converter 11 from a temperature sensor provided in the vicinity of the switching element.

[0148] In step S508, the temperature detection unit 25 calculates the difference between the detected temperature value acquired in step S507 and the detected temperature value at the start of the regenerative operation of the converter 11 stored in step S503, and calculates this difference as the degree of increase ΔT C Output as [℃].

[0149] In step S509, the distortion factor calculation unit 15 calculates the total harmonic distortion factor THD of the voltage detected by the voltage detection unit 14. Thereafter, if the power outage determination unit 30 performs the power outage determination process according to the first embodiment, the process proceeds to step S510 in Fig. 14, and if the power outage determination unit 29 performs the power outage determination process according to the second embodiment, the process proceeds to step S515 in Fig. 15.

[0150] In the power outage determination process of the power outage determination unit 30 in the first form, in step S510 of Figure 14, the power outage determination unit 30 determines whether the value (absolute value) of the current detected by the current detection unit 13 is smaller than a predetermined current threshold.

[0151] If it is not determined in step S510 that the value (absolute value) of the current detected by the current detection unit 13 is smaller than the predetermined current threshold, in step S514, the power outage determination unit 30 determines that a power outage has not occurred on the AC power supply 200 side. Then, the process returns to step S502 in FIG. 13 .

[0152] If it is determined in step S510 that the value (absolute value) of the current detected by the current detection unit 13 is smaller than the predetermined current threshold, in step S511, the power outage determination unit 30 refers to the table stored in the storage unit 21 and calculates the degree of increase ΔT C Determine whether [℃] is normal or abnormal.

[0153] In step S511, the degree of increase in the temperature detection value ΔT C If the temperature [°C] is not determined to be abnormal (i.e., normal), in step S513, the power outage determination unit 29 determines whether the total harmonic distortion factor THD is greater than a predetermined distortion factor threshold value.

[0154] If it is not determined in step S513 that the total harmonic distortion factor THD is greater than the predetermined distortion factor threshold, in step S514, the power outage determination unit 30 determines that a power outage has not occurred on the side of the AC power supply 200. Then, the process returns to step S502 in FIG. 13 .

[0155] If it is determined in step S513 that the total harmonic distortion factor THD is greater than the predetermined distortion factor threshold, the power outage determination unit 30 determines in step S512 that a power outage has occurred on the AC power supply 200 side, and outputs a power outage detection signal. Then, the process ends.

[0156] In step S511, the degree of increase in the temperature detection value ΔT C If it is determined that the temperature [°C] is abnormal, then in step S512, the power outage determination unit 30 determines that a power outage has occurred on the AC power supply 200 side, and outputs a power outage detection signal. Then, the process ends.

[0157] In the power outage determination process of the power outage determination unit 30 in the second form, in step S515 of Figure 15, the power outage determination unit 30 determines whether the value (absolute value) of the current detected by the current detection unit 13 is smaller than a predetermined current threshold.

[0158] If it is not determined in step S515 that the value (absolute value) of the current detected by the current detection unit 13 is smaller than the predetermined current threshold, in step S519, the power outage determination unit 30 determines that a power outage has not occurred on the side of the AC power supply 200. Then, the process returns to step S502 in FIG. 13 .

[0159] If it is determined in step S515 that the value (absolute value) of the current detected by the current detection unit 13 is smaller than the predetermined current threshold, in step S516, the power outage determination unit 30 refers to the table stored in the storage unit 21 and calculates the degree of increase ΔT C Determine whether [℃] is normal or abnormal.

[0160] In step S516, the degree of increase in the detected temperature value ΔT C If the temperature [°C] is not determined to be abnormal (i.e., normal), in step S519, the power outage determination unit 30 determines that a power outage has not occurred on the side of the AC power supply 200. Then, the process returns to step S502 in FIG. 13 .

[0161] In step S516, the degree of increase in the detected temperature value ΔT CIf the temperature [°C] is determined to be abnormal, in step S517, the power outage determination unit 30 determines whether the total harmonic distortion THD is greater than a predetermined distortion threshold value. The order of the processing in step S516 and the processing in step S517 may be reversed.

[0162] If it is not determined in step S517 that the total harmonic distortion factor THD is greater than the predetermined distortion factor threshold, in step S519, the power outage determination unit 30 determines that a power outage has not occurred on the side of the AC power supply 200. Then, the process returns to step S502 in FIG. 13 .

[0163] If it is determined in step S517 that the total harmonic distortion THD is greater than the predetermined distortion threshold, the power outage determination unit 30 determines in step S518 that a power outage has occurred on the AC power supply 200 side, and outputs a power outage detection signal. Then, the process ends.

[0164] The series of processes in steps S501 to S514, as well as the series of processes in steps S501 to S509 and S515 to S519, are repeatedly executed at a predetermined control period (for example, 10 ms). The control period may be changed as appropriate.

[0165] Sixth Embodiment of the Present Disclosure The sixth embodiment of the present disclosure is applicable to a motor drive device provided with multiple inverters for driving multiple motors. Generally, in motor drive devices, one converter is provided for multiple inverters in order to reduce the cost and space required for the motor drive device. That is, a converter that converts AC power supplied from an AC power source into DC power serves as a common power supply unit for the multiple inverters, and the multiple inverters use the DC power output from the power supply unit to generate AC power for driving each motor.

[0166] 16 is a circuit diagram showing a motor drive device according to a sixth embodiment of the present disclosure. Here, as an example, a case will be described in which two motors, designated by reference numerals 300-1 and 300-2, are driven by a motor drive device 6 according to the sixth embodiment of the present disclosure. An inverter 12-1 is provided corresponding to motor 300-1, and an inverter 12-2 is provided corresponding to motor 300-2. The number of motors is not particularly limited to the sixth embodiment of the present disclosure, and may be one, three, or more.

[0167] A motor drive device 6 according to a sixth embodiment of the present disclosure includes a converter 11, inverters 12-1 and 12-2, a current detection unit 13, a DC link voltage detection unit 17, a converter power acquisition unit 31, an inverter power acquisition unit 32, a power failure determination unit 33, and an inverter control unit 40. The motor drive device 1 also includes a capacitor 101, a breaker 102, an electromagnetic contactor 103, and a reactor 104. Note that, in order to enable the current detection unit 13, the DC link voltage detection unit 17, the converter power acquisition unit 31, the inverter power acquisition unit 32, the power failure determination unit 33, and the inverter control unit 40 to operate even in the event of a power failure on the AC power supply 200 side, it is preferable that a power supply for supplying power to these units be provided on a system separate from the AC power supply 200.

[0168] The converter 11, the current detector 13, the DC link voltage detector 17, the inverter controller 40, the capacitor 101, the breaker 102, the electromagnetic contactor 103, and the reactor 104 are as described in the first embodiment. The inverters 12-1 and 12-2 are as described for the inverter 12 in the first embodiment.

[0169] The converter power acquisition unit 31 acquires the value of the power converted by the converter 11. The value of the power converted by the converter 11 may be acquired by calculation based on the current and voltage measured for the converter 11, or may be acquired using a power meter.

[0170] The inverter power acquisition unit 32 acquires the sum of the values ​​of the power converted by the inverters 12-1 and 12-2. The value of the power converted by each of the inverters 12-1 and 12-2 may be acquired by calculation based on the current and voltage measured for the converter 11, or may be acquired using a power meter. The power converted by the inverters 12-1 and 12-2 includes running power (energy consumption) for driving each of the motors 300-1 and 300-2 and regenerative running power (energy generation) generated by each of the motors 300-1 and 300-2.

[0171] Note that the power in the direction in which the converter 11 converts DC power to AC power is positive, and the power in the direction in which the inverters 12-1 and 12-2 convert AC power to DC power is positive. Therefore, for the converter 11, the regenerative power returned from the DC link to the AC power supply 200 is positive, and the rectified power flowing from the AC power supply 200 to the DC link is negative. For the inverter, the regenerative power returned from the motor to the DC link is positive, and the running power flowing from the DC link to the motor is negative.

[0172] When no power outage occurs on the AC power supply 200 side and the AC power supply 200 is not disconnected from the motor drive device 1, the power converted by the inverters 12-1 and 12-2 flows to the AC power 200 side via the converter 11, so there is a small difference between the sum of the power values ​​converted by the inverters 12-1 and 12-2 acquired by the inverter power acquisition unit 32 and the power value converted by the converter 11 acquired by the converter power acquisition unit 31. On the other hand, when a power outage occurs on the AC power supply 200 side and the AC power supply 200 is disconnected from the motor drive device 1, no current flows from the converter 11 to the AC power supply 200 side, so there is a large difference between the sum of the power values ​​converted by the inverters 12-1 and 12-2 acquired by the inverter power acquisition unit 32 and the power value converted by the converter 11 acquired by the converter power acquisition unit 31. That is, the presence or absence of a power outage on the AC power supply 200 side can be determined by monitoring the magnitude of the difference between the sum of the power values ​​converted by the inverters 12-1 and 12-2 acquired by the inverter power acquisition unit 32 and the power value converted by the converter 11 acquired by the converter power acquisition unit 31. Therefore, in the sixth embodiment of the present disclosure, the power outage determination unit 33 determines the presence or absence of a power outage on the AC power supply 200 side during regenerative operation of the converter 11 based on the current value detected by the current detection unit 13, the sum of the power value converted by the converter 11 acquired by the converter power acquisition unit 31, and the power value converted by the inverters 12-1 and 12-2 acquired by the inverter power acquisition unit 32.

[0173] More specifically, when the value (absolute value) of the current detected by the current detection unit 13 is smaller than a predetermined current threshold during the regenerative operation of the converter 11, and the difference between the sum of the power values ​​converted by the inverters 12-1 and 12-2 acquired by the inverter power acquisition unit 32 and the power value converted by the converter 11 acquired by the converter power acquisition unit 31 is greater than a predetermined power threshold, the power outage determination unit 33 determines that a power outage has occurred on the AC power supply 200 side. In the sixth embodiment of the present disclosure, when multiple inverters are present, the sum of the power values ​​converted by these multiple inverters is used to determine the power outage, and therefore the sixth embodiment of the present disclosure is applicable to a motor drive device provided with multiple inverters to drive multiple motors.

[0174] The current threshold is set to determine whether the value (absolute value) of the current input to the converter 11 detected by the current detection unit 13 or the value (absolute value) of the current output from the converter 11 is approximately 0 (zero). The current threshold is set to, for example, about 0.1 mA, but may be any other numerical value. The power threshold is set to determine whether the difference between the sum of the values ​​of the power converted by the inverters 12-1 and 12-2 acquired by the inverter power acquisition unit 32 and the value of the power converted by the converter 11 acquired by the converter power acquisition unit 31 is large or small. The power threshold is set to, for example, about several watts to several tens of watts, but may be any other numerical value.

[0175] The power threshold and / or current threshold may be stored in a rewritable memory unit (not shown) and rewritable by an external device, so that even after the power threshold and / or current threshold have been set, they can be changed to appropriate values ​​as needed.

[0176] The power outage determination unit 33 may be provided inside the converter 11 , inside a converter control unit that controls the converter 11 , or inside the inverter control unit 40 .

[0177] FIG. 17 is a flowchart showing the operation flow of power failure detection processing in the motor drive device according to the sixth embodiment of the present disclosure.

[0178] When the motor drive device 1 is operating, in step S601, the power outage determination unit 33 determines whether the converter 11 is in a regenerative operation.

[0179] If it is determined in step S601 that the converter 11 is in a regenerative operation, the current detection unit 13 detects the value of the current input to the converter 11 or the value of the current output from the converter 11 in step S602.

[0180] In step S603 , the converter power acquisition unit 31 acquires the value of the power converted by the converter 11 .

[0181] In step S604, the inverter power obtaining unit 32 obtains the sum of the values ​​of the power converted by the inverters 12-1 and 12-2. The order of the processing in step S603 and the processing in step S604 may be reversed.

[0182] In step S605, the power outage determination unit 33 determines whether or not the value (absolute value) of the current detected by the current detection unit 13 is smaller than a predetermined current threshold value.

[0183] If it is not determined in step S605 that the value (absolute value) of the current detected by the current detection unit 13 is smaller than the predetermined current threshold, in step S608, the power outage determination unit 33 determines that a power outage has not occurred on the AC power supply 200 side. Then, the process returns to step S601.

[0184] If it is determined in step S605 that the current value (absolute value) detected by the current detection unit 13 is smaller than a predetermined current threshold, in step S606, the power outage determination unit 33 determines whether the difference between the sum of the power values ​​converted by the inverters 12-1 and 12-2 acquired by the inverter power acquisition unit 32 and the power value converted by the converter 11 acquired by the converter power acquisition unit 31 is greater than a predetermined power threshold.

[0185] If it is not determined in step S606 that the difference between the sum of the values ​​of power converted by the inverters 12-1 and 12-2, acquired by the inverter power acquisition unit 32, and the value of power converted by the converter 11, acquired by the converter power acquisition unit 31, is greater than the power threshold value, then in step S608, the power outage determination unit 33 determines that no power outage has occurred on the AC power supply 200 side. Then, the process returns to step S601.

[0186] If it is determined in step S606 that the difference between the sum of the power values ​​converted by the inverters 12-1 and 12-2, acquired by the inverter power acquisition unit 32, and the power value converted by the converter 11, acquired by the converter power acquisition unit 31, is greater than the power threshold value, then in step S607, the power outage determination unit 33 determines that a power outage has occurred on the AC power supply 200 side, and outputs a power outage detection signal. Then, the processing ends.

[0187] The series of processes from step S601 to step S408 is repeatedly executed at a predetermined control period (for example, 10 ms), which may be changed as appropriate.

[0188] <Notification to Workers> The determination results by the power outage determination units 16, 27, 28, 29, 30, and 33 may be notified to workers by a notification unit (not shown) such as a display device, an audio device, or a printer. Based on the notified determination results by the power outage determination units 16, 27, 28, 29, 30, and 33, the workers can quickly and reliably grasp whether or not there is a power outage on the AC power supply 200 side.

[0189] Examples of display devices include a standalone display monitor, a display monitor attached to motor drive devices 1 to 6, a display monitor attached to a higher-level control device (not shown) that controls motor drive devices 1 to 6, and a display monitor attached to a personal computer or a mobile terminal. Alternatively, the display device may be configured as an illuminant such as an LED or lamp. For example, the illuminant may not emit light when there is no power outage on the AC power supply 200 side, and may emit light when a power outage occurs.

[0190] For example, the acoustic device does not emit sound when there is no power outage on the AC power supply 200 side, but emits sound when a power outage occurs. Examples of the acoustic device include a speaker, a buzzer, and a chime.

[0191] When a power outage occurs on the AC power supply 200 side, the printer prints out the date and time of the power outage on paper or the like.

[0192] Furthermore, each time a determination result is obtained by the power outage determination units 16, 27, 28, 29, 30, and 33, it may be stored in memory and accumulated, and by creating a database, it may be useful for maintenance work, parts ordering work, and the like.

[0193] <Processor and Memory> Each of the motor drive devices 1 to 6 is provided with at least one processor, which is a processing device. Examples of the processing device include an IC, an LSI, a CPU, an MPU, and a DSP. The processing device includes a current detection unit 13, a voltage detection unit 14, a distortion factor calculation unit 15, a DC link voltage detection unit 17, a regenerative power acquisition unit 22, a temperature calculation unit 23, a temperature detection unit 25, temperature determination units 24 and 26, power outage determination units 16, 27, 28, 29, 30, and 33, a converter power acquisition unit 31, an inverter power acquisition unit 32, an inverter control unit 40, and other processing units. Each of these units included in the processing device is a functional module implemented by a program executed on the processor, for example. For example, when the current detection unit 13, the voltage detection unit 14, the distortion rate calculation unit 15, the DC link voltage detection unit 17, the regenerative power acquisition unit 22, the temperature calculation unit 23, the temperature detection unit 25, the temperature determination units 24 and 26, the power outage determination units 16, 27, 28, 29, 30 and 33, the converter power acquisition unit 31, the inverter power acquisition unit 32, the inverter control unit 40, and other processing units are constructed in the form of a program, the functions of each unit can be realized by operating the arithmetic processing device in accordance with the program. The programs for executing the processes in the current detection unit 13, the voltage detection unit 14, the distortion rate calculation unit 15, the DC link voltage detection unit 17, the regenerative power acquisition unit 22, the temperature calculation unit 23, the temperature detection unit 25, the temperature determination units 24 and 26, the power outage determination units 16, 27, 28, 29, 30 and 33, the converter power acquisition unit 31, the inverter power acquisition unit 32, the inverter control unit 40, and other processing units 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 current detection unit 13, the voltage detection unit 14, the distortion rate calculation unit 15, the DC link voltage detection unit 17, the regenerative power acquisition unit 22, the temperature calculation unit 23, the temperature detection unit 25, the temperature determination units 24 and 26, the power failure determination units 16, 27, 28, 29, 30 and 33, the converter power acquisition unit 31, the inverter power acquisition unit 32, the inverter control unit 40, and other processing units may be realized as semiconductor integrated circuits in which programs for realizing the functions of each unit are written.

[0194] Each of the motor drive devices 1 to 6 is provided with at least one memory serving as a storage device. The memory includes a storage unit 21. The memory also includes a current detector 13, a voltage detector 14, a distortion factor calculator 15, a DC link voltage detector 17, a storage unit 21, a regenerative power acquisition unit 22, a temperature calculator 23, a temperature detector 25, temperature determination units 24 and 26, power outage determination units 16, 27, 28, 29, 30 and 33, a converter power acquisition unit 31, an inverter power acquisition unit 32, an inverter control unit 40, and various storage units within other processing units. Examples of the memory include electrically erasable and recordable nonvolatile memory such as an EEPROM (registered trademark), or high-speed read / write random access memory such as a DRAM or SRAM. The storage device may also have a configuration such as a hard disk drive (HDD) or a solid state drive (SSD). The memory stores programs for operating the current detection unit 13, the voltage detection unit 14, the distortion factor calculation unit 15, the DC link voltage detection unit 17, the storage unit 21, the regenerative power acquisition unit 22, the temperature calculation unit 23, the temperature detection unit 25, the temperature determination units 24 and 26, the power outage determination units 16, 27, 28, 29, 30 and 33, the converter power acquisition unit 31, the inverter power acquisition unit 32, the inverter control unit 40, and other processing units. The memory also stores the current value detected by the current detection unit 13, the voltage value detected by the voltage detection unit 14, and the DC link voltage value detected by the DC link voltage detection unit 17. The memory also stores the total harmonic distortion factor THD calculated by the distortion factor calculation unit 15. The memory also stores the regenerative power value acquired by the regenerative power acquisition unit 22. The temperature rise estimated value calculated by the temperature calculation unit 23. The memory also stores the temperature detection value acquired by the temperature detection unit 25. The memory stores a table showing the relationship between regenerative power acquired in advance when there is no power outage on the AC power supply 200 side and the temperature of the switching elements in the converter 11 acquired in advance corresponding to the time of acquisition. The memory stores the determination results by the temperature determination units 24 and 26. The memory stores power values ​​acquired by the converter power acquisition unit 31. The memory stores power values ​​acquired by the inverter power acquisition unit 32.The memory stores the determination results of the power outage determination units 16, 27, 28, 29, 30, and 33. The memory stores a current threshold, a distortion factor threshold, and a power threshold. The memory stores various programs and data related to the converter control unit that controls the 120-degree conduction type converter 11. The memory stores various programs and data related to the inverter control unit 40. The memory stores various programs and data related to each of the motor drive devices 1 to 6.

[0195] Advantages of Each Embodiment of the Present Disclosure According to each embodiment of the present disclosure, a motor drive device having a power regeneration function can detect a power outage even during regeneration operation. According to each embodiment of the present disclosure, a power outage can be detected even during regeneration operation, thereby preventing the DC link voltage from becoming overvoltage during regeneration operation. According to each embodiment of the present disclosure, a power outage can be detected even during regeneration operation, thereby reliably outputting a power outage detection signal. Therefore, discharge operations of discharge circuits based on the power outage detection signal and various protective operations (retraction control, braking control, fall prevention control, etc.) for machine tools and robots based on the power outage detection signal can be reliably performed, thereby improving safety. Furthermore, according to a sixth embodiment of the present disclosure, a power outage on the AC power supply side during regeneration operation can be detected even in a motor drive device provided with multiple inverters to drive multiple motors.

[0196] Although the present disclosure has been described in detail above, the present disclosure is not limited to the individual embodiments and individual variations described above. Various additions, substitutions, modifications, partial deletions, etc. are possible for these embodiments and variations within the scope of the gist of the present disclosure, or within the scope of the gist of the present disclosure derived from the content of the claims and their equivalents. These embodiments and variations can also be implemented in combination. For example, in the above-described embodiments and variations, the order of each operation and the order of each process are shown as examples and are not limited to these. The same applies when numerical values ​​or mathematical formulas are used in the description of the above-described embodiments and variations.

[0197] <Supplementary Notes> The following supplementary notes are further disclosed regarding the above-described embodiment and modifications.

[0198] (Supplementary Note 1) A motor drive device comprising: a converter that performs a rectification operation of converting AC power input from an AC power supply side into DC power and outputs the power to a DC link side, and a regeneration operation of converting the DC power on the DC link side into AC power in accordance with a 120-degree conduction method and returning the power to the AC power supply side; an inverter that performs a powering operation of converting DC power input from the DC link side into AC power for driving a motor and outputting the power to the motor side, and a regeneration operation of converting AC power regenerated by the motor into DC power and returning the power to the DC link side; a current detection unit that detects the value of a current input to the converter or the value of a current output from the converter; a voltage detection unit that detects the voltage input to the converter; a distortion factor calculation unit that calculates the total harmonic distortion factor of the voltage detected by the voltage detection unit; and a power outage determination unit that determines whether or not a power outage has occurred on the AC power supply side, based on the current value and the total harmonic distortion factor detected by the current detection unit, during the regeneration operation of the converter. (Supplementary Note 2) The motor drive device according to Supplementary Note 1, wherein the power failure determination unit determines that a power failure has occurred on the AC power supply side when the current value detected by the current detection unit is smaller than a predetermined current threshold and the total harmonic distortion rate is greater than a predetermined distortion rate threshold during regenerative operation of the converter. (Supplementary Note 3) The motor drive device according to Supplementary Note 1, further comprising a DC link voltage detection unit that detects a DC link voltage between the converter and the inverter.(Supplementary Note 4) A motor drive device according to Supplementary Note 2 or 3, comprising: a memory unit that stores a table showing the relationship between a value of regenerative power of the converter acquired in advance when there is no power outage on the AC power supply side and a temperature of a switching element in the converter acquired in advance corresponding to a time point at which the regenerative power is acquired; a regenerative power acquisition unit that acquires the value of the regenerative power of the converter; a temperature calculation unit that calculates an estimated value of temperature rise of the switching element using a value of current detected by the current detection unit during regenerative operation of the converter; and a temperature determination unit that determines whether the estimated value of temperature rise for regenerative power acquired by the regenerative power acquisition unit during regenerative operation of the converter is normal or abnormal by referring to the table stored in the memory unit, wherein the power outage determination unit determines that a power outage has occurred on the AC power supply side when, during regenerative operation of the converter, the value of current detected by the current detection unit is smaller than a predetermined current threshold and the total harmonic distortion rate is greater than a predetermined distortion rate threshold, or when the value of current detected by the current detection unit is smaller than the predetermined current threshold and the temperature determination unit determines that the estimated value of temperature rise is abnormal. (Supplementary Note 5) A motor drive device according to Supplementary Note 2 or 3, comprising: a memory unit that stores a table showing the relationship between a value of regenerative power of the converter acquired in advance when there is no power outage on the AC power supply side and a temperature of a switching element in the converter acquired in advance corresponding to the time point at which the regenerative power was acquired; a regenerative power acquisition unit that acquires the value of the regenerative power of the converter; a temperature detection unit that acquires a detected temperature value of the switching element; and a temperature determination unit that refers to the table stored in the memory unit and determines whether a degree of increase in the temperature detection value relative to the regenerative power acquired by the regenerative power acquisition unit during regenerative operation of the converter is normal or abnormal, wherein the power outage determination unit determines that a power outage has occurred on the AC power supply side during regenerative operation of the converter when at least one of the following applies: the value of the current detected by the current detection unit is smaller than a predetermined current threshold and the total harmonic distortion rate is larger than a predetermined distortion rate threshold, and the value of the current detected by the current detection unit is smaller than the predetermined current threshold and the temperature determination unit determines that the degree of increase in the temperature detection value is abnormal.(Supplementary Note 6) A converter that performs a rectification operation of converting AC power input from an AC power supply side into DC power and outputs it to a DC link side, and a regeneration operation of converting DC power on the DC link side into AC power in accordance with a 120-degree conduction method and returning it to the AC power supply side; an inverter that performs a powering operation of converting DC power input from the DC link side into AC power for driving a motor and outputting it to the motor side, and a regeneration operation of converting AC power regenerated by the motor into DC power and returning it to the DC link side; a current detection unit that detects the value of a current input to the converter or the value of a current output from the converter; a storage unit that stores a table showing the relationship between values ​​of regenerative power of the converter acquired in advance when there is no power outage on the AC power supply side and temperatures of switching elements in the converter acquired in advance corresponding to the time points at which the regenerative power was acquired; a regenerative power acquisition unit that acquires the value of the regenerative power of the converter; and a temperature calculation unit that calculates an estimated value of temperature rise of the switching elements using the value of the current detected by the current detection unit during the regenerative operation of the converter. a temperature determination unit that determines whether an estimated value of a temperature rise for regenerative power acquired by a regenerative power acquisition unit during regenerative operation of the converter is normal or abnormal by referring to a table stored in a storage unit, and a power outage determination unit that determines whether or not a power outage has occurred on the AC power supply side during regenerative operation of the converter based on the value of the current detected by the current detection unit and the determination result by the temperature determination unit. (Supplementary Note 7) The motor drive device according to Supplementary Note 6, wherein the power outage determination unit determines that a power outage has occurred on the AC power supply side when the value of the current detected by the current detection unit is smaller than a predetermined current threshold and the temperature determination unit determines that the estimated value of the temperature rise is abnormal during regenerative operation of the converter.(Supplementary Note 8) A motor drive device comprising: a converter that performs a rectification operation of converting AC power input from an AC power supply side into DC power and outputs the DC power on the DC link side to AC power in accordance with a 120-degree conduction method and a regeneration operation of converting DC power on the DC link side into AC power and returning the DC power to the AC power supply side; at least one inverter that performs a power running operation of converting DC power input from the DC link side into AC power for driving a motor and outputting the AC power to the motor side, and a regeneration operation of converting AC power regenerated by the motor into DC power and returning the DC power to the DC link side; a current detection unit that detects a value of a current input to the converter or a value of a current output from the converter; a converter power acquisition unit that acquires a value of the power converted by the converter; an inverter power acquisition unit that acquires a sum of the values ​​of the power converted by the inverters; and a power outage determination unit that, during the regenerative operation of the converter, determines whether or not a power outage has occurred on the AC power supply side based on the value of the current detected by the current detection unit, the sum of the value of the power converted by the converter acquired by the converter power acquisition unit, and the value of the power converted by the inverter acquired by the inverter power acquisition unit. (Supplementary Note 9) The motor drive device according to Supplementary Note 8, wherein the power outage determination unit determines that a power outage has occurred on the AC power supply side when, during regenerative operation of the converter, the value of the current detected by the current detection unit is smaller than a predetermined current threshold and the difference between the sum of the values ​​of power converted by the inverter acquired by the inverter power acquisition unit and the value of power converted by the converter acquired by the converter power acquisition unit is larger than a predetermined power threshold.(Supplementary Note 10) A converter that performs a rectification operation of converting AC power input from an AC power supply side into DC power and outputting it to a DC link side, and a regeneration operation of converting DC power on the DC link side into AC power in accordance with a 120-degree conduction method and returning it to the AC power supply side; an inverter that performs a powering operation of converting DC power input from the DC link side into AC power for driving a motor and outputting it to the motor side, and a regeneration operation of converting AC power regenerated by the motor into DC power and returning it to the DC link side; a current detection unit that detects the value of a current input to the converter or the value of a current output from the converter; a storage unit that stores a table showing the relationship between values ​​of regenerative power of the converter acquired in advance when there is no power outage on the AC power supply side and temperatures of switching elements in the converter acquired in advance corresponding to the time points at which the regenerative power was acquired; a regenerative power acquisition unit that acquires the value of the regenerative power of the converter; and a temperature detection unit that acquires the detected temperature value of the switching element. a temperature determination unit that determines whether a degree of increase in a temperature detection value relative to regenerative power acquired by a regenerative power acquisition unit during regenerative operation of the converter is normal or abnormal by referring to a table stored in a storage unit, and a power outage determination unit that determines whether a power outage has occurred on the AC power supply side during regenerative operation of the converter based on a value of current detected by a current detection unit and a determination result by the temperature determination unit. (Supplementary Note 11) The motor drive device according to Supplementary Note 10, wherein the power outage determination unit determines that a power outage has occurred on the AC power supply side when, during regenerative operation of the converter, the value of current detected by the current detection unit is smaller than a predetermined current threshold and the temperature determination unit determines that the degree of increase in the temperature detection value is abnormal.

[0199] 1, 2, 3, 4, 5, 6 Motor drive device 11 Converter 12, 12-1, 12-2 Inverter 13 Current detection unit 14 Voltage detection unit 15 Distortion rate calculation unit 16, 27, 28, 29, 30, 33 Power outage determination unit 17 DC link voltage detection unit 21 Memory unit 22 Regenerative power acquisition unit 23 Temperature calculation unit 24, 26 Temperature determination unit 25 Temperature detection unit 31 Converter power acquisition unit 32 Inverter power acquisition unit 40 Inverter control unit 101 Capacitor 102 Breaker 103 Electromagnetic contactor 104 Reactor 200 AC power supply 300, 300-1, 300-2 Motor S UU , S UL , S VU , S VL , S WU , S WL Switching element

Claims

1. A motor drive device comprising: a converter that performs a rectification operation of converting AC power input from an AC power supply side into DC power and outputting it to a DC link side, and a regeneration operation of converting the DC power on the DC link side into AC power in accordance with a 120-degree conduction method and returning it to the AC power supply side; an inverter that performs a powering operation of converting DC power input from the DC link side into AC power for driving a motor and outputting it to the motor side, and a regeneration operation of converting AC power regenerated by the motor into DC power and returning it to the DC link side; a current detection unit that detects the value of the current input to the converter or the value of the current output from the converter; a voltage detection unit that detects the voltage input to the converter; a distortion rate calculation unit that calculates the total harmonic distortion rate of the voltage detected by the voltage detection unit; and a power outage determination unit that determines whether or not there is a power outage on the AC power supply side based on the value of the current detected by the current detection unit and the total harmonic distortion rate during the regeneration operation of the converter.

2. The motor drive device of claim 1, wherein the power outage determination unit determines that a power outage has occurred on the AC power supply side when the current value detected by the current detection unit is smaller than a predetermined current threshold and the total harmonic distortion rate is greater than a predetermined distortion rate threshold during regenerative operation of the converter.

3. The motor drive device according to claim 1, further comprising a DC link voltage detection unit that detects a DC link voltage between the converter and the inverter.

4. A storage unit that stores a table showing the relationship between the value of regenerative power of the converter acquired in advance when there is no power outage on the AC power supply side and the temperature of a switching element in the converter acquired in advance corresponding to the time point at which the regenerative power is acquired; a regenerative power acquisition unit that acquires the value of regenerative power of the converter; a temperature calculation unit that calculates an estimated value of temperature rise of the switching element using the value of current detected by the current detection unit during regenerative operation of the converter; and a temperature determination unit that refers to the table stored in the storage unit and determines whether the estimated value of temperature rise for regenerative power acquired by the regenerative power acquisition unit during regenerative operation of the converter is normal or abnormal, 4. The motor drive device according to claim 2, wherein the power outage determination unit determines that a power outage has occurred on the AC power supply side when at least one of the following cases applies during regenerative operation of the converter: a current value detected by the current detection unit is smaller than a predetermined current threshold and the total harmonic distortion rate is larger than a predetermined distortion rate threshold; and a current value detected by the current detection unit is smaller than a predetermined current threshold and the temperature determination unit determines that the temperature rise estimated value is abnormal.

5. A motor drive device according to claim 2 or 3, comprising: a memory unit that stores a table showing the relationship between the value of regenerative power of the converter acquired in advance when there is no power outage on the AC power supply side and the temperature of a switching element in the converter acquired in advance corresponding to the time point at which the regenerative power was acquired; a regenerative power acquisition unit that acquires the value of the regenerative power of the converter; a temperature detection unit that acquires the detected temperature value of the switching element; and a temperature determination unit that refers to the table stored in the memory unit and determines whether a degree of increase in the temperature detection value relative to the regenerative power acquired by the regenerative power acquisition unit during regenerative operation of the converter is normal or abnormal, wherein the power outage determination unit determines that a power outage has occurred on the AC power supply side during regenerative operation of the converter when at least one of the following applies: the value of the current detected by the current detection unit is smaller than a predetermined current threshold and the total harmonic distortion rate is larger than a predetermined distortion rate threshold; or the value of the current detected by the current detection unit is smaller than the predetermined current threshold and the temperature determination unit determines that the degree of increase in the temperature detection value is abnormal.

6. A converter that performs a rectification operation of converting AC power input from an AC power supply side into DC power and outputting it to a DC link side, and a regeneration operation of converting the DC power on the DC link side into AC power in accordance with a 120-degree conduction method and returning it to the AC power supply side; an inverter that performs a powering operation of converting DC power input from the DC link side into AC power for driving a motor and outputting it to the motor side, and a regeneration operation of converting AC power regenerated by the motor into DC power and returning it to the DC link side; a current detection unit that detects the value of a current input to the converter or the value of a current output from the converter; a memory unit that stores a table showing the relationship between values ​​of regenerative power of the converter acquired in advance when there is no power outage on the AC power supply side and temperatures of switching elements in the converter acquired in advance corresponding to the time points at which the regenerative power was acquired; a regenerative power acquisition unit that acquires the value of the regenerative power of the converter; and a temperature calculation unit that calculates an estimated temperature rise value of the switching element using the value of the current detected by the current detection unit during the regenerative operation of the converter. a temperature determination unit that determines whether the estimated value of temperature rise for the regenerative power acquired by the regenerative power acquisition unit during regenerative operation of the converter is normal or abnormal by referring to the table stored in the memory unit; and a power outage determination unit that determines whether or not there is a power outage on the AC power supply side during regenerative operation of the converter, based on the value of the current detected by the current detection unit and the determination result by the temperature determination unit.

7. The motor drive device according to claim 6, wherein the power outage determination unit determines that a power outage has occurred on the AC power supply side when, during regenerative operation of the converter, the value of the current detected by the current detection unit is smaller than a predetermined current threshold and the temperature determination unit determines that the estimated temperature rise value is abnormal.

8. A motor drive device comprising: a converter that performs a rectification operation of converting AC power input from an AC power supply side into DC power and outputting it to a DC link side, and a regeneration operation of converting the DC power on the DC link side into AC power in accordance with a 120-degree conduction method and returning it to the AC power supply side; at least one inverter that performs a power running operation of converting DC power input from the DC link side into AC power for driving a motor and outputting it to the motor side, and a regeneration operation of converting AC power regenerated by the motor into DC power and returning it to the DC link side; a current detection unit that detects the value of a current input to the converter or the value of a current output from the converter; a converter power acquisition unit that acquires the value of the power converted by the converter; an inverter power acquisition unit that acquires the sum of the values ​​of the power converted by the inverters; and a power outage determination unit that, during the regeneration operation of the converter, determines whether or not there is a power outage on the AC power supply side based on the value of the current detected by the current detection unit, the value of the power converted by the converter acquired by the converter power acquisition unit, and the sum of the value of the power converted by the inverter acquired by the inverter power acquisition unit.

9. The motor drive device according to claim 8, wherein the power outage determination unit determines that a power outage has occurred on the AC power supply side when, during regenerative operation of the converter, the value of the current detected by the current detection unit is smaller than a predetermined current threshold and the difference between the sum of the values ​​of power converted by the inverter acquired by the inverter power acquisition unit and the value of power converted by the converter acquired by the converter power acquisition unit is larger than a predetermined power threshold.

Images