Motor drive device equipped with a charge control unit

Abstract

A motor drive device 1 comprises: a converter 11 that converts AC power supplied from an AC power source 100 into DC power and outputs the DC power to a DC link; a capacitor 13 installed in the DC link; an inverter 12 that converts the DC power at the DC link into AC power for driving a motor and outputs the AC power; a charging circuit 14 that has a charging resistor 21 for preventing inrush current during the period of pre-charging of the capacitor 13; a charging control unit 15 that controls the pre-charging of the capacitor 13 executed by the charging circuit 14; and an abnormality determination unit 16 that determines, during the period of pre-charging of the capacitor 13, whether an abnormality has occurred, on the basis of a measurement value of the voltage of the capacitor 13 and / or a measurement value of the current flowing through the DC link.

Description

[Technical field]

[0001] The present invention relates to a motor drive device equipped with a charge control unit. [Background technology]

[0002] In motor drive devices that control the drive of motors in machine tools, presses, injection molding machines, industrial machines, or various robots, AC power supplied from an AC power source is converted to DC power by a converter (rectifier) ​​and output to a DC link, and the DC power in the DC link is further converted to AC power by an inverter, and this AC power is supplied to the motor as motor drive power. The "DC link" refers to the circuit part that electrically connects the DC output side of the converter and the DC input side of the inverter, and is sometimes called a "DC link part," "DC link," "DC link part," "DC bus bar," "DC wiring," or "DC intermediate circuit."

[0003] The DC link is provided with a capacitor that has the function of storing energy and the function of suppressing pulsation in the DC output of the converter. The capacitor provided in the DC link is also called a smoothing capacitor or a DC link capacitor, but hereinafter it will be simply called a "capacitor."

[0004] The capacitor provided in the DC link needs to be charged to a predetermined voltage after the motor drive device is powered on and before the motor starts to drive (i.e., before the inverter starts to convert power). This charging is generally called pre-charging or initial charging. Immediately after pre-charging starts when no energy is stored in the capacitor, a large inrush current is output from the converter to the DC link. The larger the capacitance of the capacitor, the larger the inrush current that occurs. For this reason, a pre-charging circuit (initial charging circuit) for preventing inrush current is generally provided on the DC link, which is the DC output side of the converter, or on the AC input side of the converter. Hereinafter, the pre-charging circuit (initial charging circuit) will be simply referred to as the "charging circuit."

[0005] For example, in an electric vehicle including a battery (3), an inverter (6) that converts DC power output by the battery (3) into AC power, a traction motor (1) driven by the AC power output by the inverter (6), and a capacitor (27) connected in parallel to the inverter (6), a deterioration determination device for a capacitor in an electric vehicle is known, which is characterized by comprising: a charging means (41) that charges the capacitor (27), a voltage detection means (S2) that detects the voltage of the capacitor (27), and a deterioration determination means (10) that determines deterioration of the capacitor (27) based on a change in the voltage of the capacitor (27) detected by the voltage detection means (S2) when the charging means (41) is in operation (see, for example, Patent Document 1).

[0006] For example, an inverter device is known which comprises a converter section which converts AC to DC, a DC capacitor which smoothes the output of the converter section, an inverter section which converts the DC voltage across the DC capacitor into AC voltage to drive an AC motor, a control section which supplies on / off pulses to switching elements which make up the inverter section, and a short-circuit bar provided in the DC wiring between the DC capacitor and the inverter section, wherein the short-circuit bar is removed and a resistor is inserted instead when diagnosing faults in the device offline (see, for example, Patent Document 2).

[0007] For example, there is known a motor drive device comprising: a converter that converts AC power supplied from an AC power supply and outputs DC power; a DC link capacitor provided in a DC link that is the DC output side of the converter; an inverter that converts the DC power in the DC link and outputs AC power for driving a motor; an initial charging circuit that is provided in the DC link and charges the DC link capacitor with the DC power output by the converter; a potential difference occurrence determination unit that determines whether a potential difference has occurred across the initial charging circuit; a DC current detection unit that detects a DC current supplied from the converter to the initial charging circuit; [Prior art documents] [Patent documents]

[0008] [Patent Document 1] Japanese Patent Application Publication No. 09-019003 [Patent Document 2] JP 2010-252536 A [Patent Document 3] JP 2017-017805 A Summary of the Invention [Problem to be solved by the invention]

[0009] In a motor drive device in which a capacitor is provided in a DC link between a converter and an inverter, pre-charging is started after power is turned on, and the pre-charging is completed when the capacitor reaches a predetermined charging voltage (e.g., DC 250V) within a specified time (e.g., within 1 second). Conventionally, if the capacitor does not reach a predetermined charging voltage within a specified time after pre-charging is started, the motor drive device outputs an alarm because there is a possibility that an abnormality has occurred in the motor drive device. In a case in which the same power source (distribution board) is shared by multiple motor drive devices, if the power supplied to one motor drive device decreases, pre-charging is not completed within the specified time and an alarm is output. As long as there is no abnormality in the motor drive device, pre-charging can be safely completed if time is taken, so it is uneconomical to uniformly issue an alarm when pre-charging is not completed within the specified time. On the other hand, continuation of pre-charging when there is an abnormality in the motor drive device must be avoided. Therefore, in a motor drive device including a capacitor provided in a DC link between a converter and an inverter and a charging circuit for the capacitor, a technology is desired that can efficiently and safely complete pre-charging of the capacitor. [Means for solving the problem]

[0010] According to one aspect of the present disclosure, a motor drive device includes a converter that converts AC power supplied from an AC power source into DC power and outputs the DC power to a DC link, a capacitor provided in the DC link, an inverter that converts the DC power in the DC link into AC power for driving a motor and outputs the AC power, a charging circuit having a charging resistor for preventing an inrush current during a period of pre-charging the capacitor, a charging control unit that controls pre-charging of the capacitor by the charging circuit, and an abnormality determination unit that determines whether or not an abnormality has occurred based on at least one of a measured value of a voltage of the capacitor and a measured value of a current flowing through the DC link during the period of pre-charging the capacitor. The abnormality determination unit determines that no abnormality has occurred when a rate of increase in the measured value of the capacitor voltage is equal to or greater than a first threshold, and the charging control unit executes control to disconnect one end of the charging resistor from the electric circuit when a rate of increase in the measured value of the capacitor voltage is less than the first threshold and a measured value of a current flowing through the DC link is equal to or greater than a second threshold, and the abnormality determination unit determines that an abnormality has occurred when a rate of decrease in the measured value of the capacitor voltage is equal to or greater than a third threshold in a state in which the charging control unit executes control to disconnect one end of the charging resistor from the electric circuit, and determines that no abnormality has occurred when the rate of decrease in the measured value of the capacitor voltage is less than the third threshold. do.

[0011] Moreover, according to one aspect of the present disclosure, a motor drive device includes a converter that converts AC power supplied from an AC power source into DC power and outputs the DC power to a DC link, a capacitor provided in the DC link, an inverter that converts the DC power in the DC link into AC power for driving the motor and outputs the AC power, a charging circuit having a charging resistor for preventing an inrush current during a period of pre-charging the capacitor, a charging control unit that controls the pre-charging of the capacitor by the charging circuit, a power consumption status acquisition unit that acquires parameters related to the power consumption status of an electromechanical system that receives AC power from the AC power source, and an abnormality determination unit that determines whether or not an abnormality has occurred based on a measured value of the capacitor voltage, a measured value of the current flowing in the DC link, and the above parameters during the period of pre-charging the capacitor.

[0012] Moreover, according to one aspect of the present disclosure, a motor drive device includes a converter that converts AC power supplied from an AC power source into DC power and outputs the DC power to a DC link, a capacitor provided in the DC link, an inverter that converts the DC power in the DC link into AC power for driving the motor and outputs the AC power, a charging circuit having a charging resistor for preventing inrush current during a period of pre-charging the capacitor, a charging control unit that controls pre-charging of the capacitor by the charging circuit, a power consumption status acquisition unit that acquires parameters related to a power consumption status of an electromechanical system that receives AC power from the AC power source, and an abnormality determination unit that determines whether or not an abnormality has occurred based on the parameters during the period of pre-charging the capacitor. Effect of the Invention

[0013] According to one aspect of the present disclosure, in a motor drive device including a capacitor provided in a DC link between a converter and an inverter and a charging circuit for the capacitor, pre-charging of the capacitor can be completed efficiently and safely. [Brief description of the drawings]

[0014] [Figure 1] FIG. 1 illustrates a motor drive device according to an embodiment of the present disclosure. [Diagram 2] 1 is a diagram showing a case in which a charging circuit is provided between an AC input side of a converter and an AC power supply in a motor drive device according to an embodiment of the present disclosure. [Diagram 3] 5 is a flowchart showing a pre-charging operation in the motor drive device according to an embodiment of the present disclosure. [Figure 4] FIG. 11 is a diagram illustrating a first modified example of a motor drive device according to an embodiment of the present disclosure. [Diagram 5] 13 is a flowchart showing a pre-charging operation in a first modified example of a motor drive device according to an embodiment of the present disclosure. [Figure 6] FIG. 13 is a diagram illustrating a second modified example of a motor driving device according to an embodiment of the present disclosure. [Figure 7] 13 is a flowchart showing a pre-charging operation in a second modified example of a motor drive device according to an embodiment of the present disclosure. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0015] A motor drive device including a charging control unit will be described below with reference to the drawings. The scale of the drawings is appropriately changed to facilitate understanding. The form shown in the drawings is one example for carrying out the invention, and the invention is not limited to the illustrated embodiment.

[0016] FIG. 1 is a diagram illustrating a motor drive device according to an embodiment of the present disclosure.

[0017] As an example, a case where a motor 200 is controlled by a motor drive device 1 connected to an AC power source 100 is shown. In this embodiment, the type of the motor 200 is not particularly limited, and may be, for example, an induction motor or a synchronous motor, and the number of the motors 200 is also not particularly limited. The number of phases of the AC power source 100 and the motor 200 does not particularly limit this embodiment, and may be, for example, three-phase or single-phase. In the example shown in FIG. 1, the AC power source 100 and the motor 200 are each three-phase. Examples of the AC power source 100 include a three-phase 400V AC power source, a three-phase 200V AC power source, a three-phase 600V AC power source, and a single-phase 100V AC power source. Machines in which the motor 200 is provided include, for example, machine tools, robots, forging machines, injection molding machines, and industrial machines.

[0018] In addition to the motor drive device 1, at least one electromechanical system is connected to the AC power source 100. In the example shown in FIG. 1, as an example, n motor drive devices 2-1 to 2-n (where n is a positive integer) are connected to the AC power source 100 as the electromechanical system, but the electromechanical system connected to the AC power source 100 is not limited to the motor drive devices 2-1 to 2-n and may be any machine that receives AC power from the AC power source 100. The motor drive device 1 and the motor drive devices 2-1 to 2-n receive AC power from the same AC power source 100. The motor drive devices 2-1 to 2-n drive motors 200-1 to 200-n, for example, respectively, but each of the motor drive devices 2-1 to 2-n may drive multiple motors 200.

[0019] A motor driving device 1 according to one embodiment of the present disclosure includes a converter 11, an inverter 12, a capacitor 13, a charging circuit 14, a charging control unit 15, an abnormality determination unit 16, a power consumption status acquisition unit 17, a voltage measurement unit 18, and a current measurement unit 19.

[0020] The converter 11 converts AC power supplied from the AC power source 100 into DC power and outputs it to a DC link, which is a DC output side. The converter 11 is configured as a three-phase bridge circuit when three-phase AC power is supplied from the AC power source 100, and is configured as a single-phase bridge circuit when single-phase AC power is supplied from the AC power source 100. In the illustrated example, the AC power source 100 is a three-phase AC power source, so the converter 11 is configured as a three-phase bridge circuit. Examples of the converter 11 include a diode rectifier, a 120-degree conduction type rectifier, and a PWM switching control type rectifier. For example, when the converter 11 is a 120-degree conduction type rectifier or a PWM switching control type rectifier, it is configured as a bridge circuit of switching elements and diodes connected in reverse parallel thereto, and each switching element is controlled to be on and off in response to a drive command received from a higher-level control device (not shown) to perform power conversion in both directions. In this case, examples of the switching elements include FETs, IGBTs, thyristors, GTOs, transistors, etc., but other semiconductor elements may also be used.

[0021] The inverter 12 is connected to the converter 11 via a DC link. The inverter 12 converts the DC power in the DC link into AC power for driving the motor 200 and outputs the AC power. More specifically, the inverter 12 converts the DC power in the DC link into AC power and supplies it to the motor 200 on the AC side by PWM-controlling the on / off operation of the internal switching elements based on the switching command generated by the motor control unit 10, and also converts the AC power regenerated by the deceleration of the motor 200 into DC power and returns it to the DC link. The inverter 12 is composed of a full bridge circuit of switching elements and diodes connected in reverse parallel thereto. Examples of the switching elements include IGBTs, FETs, thyristors, GTOs, transistors, etc., but other semiconductor elements may also be used. In the example shown in FIG. 1, the motor 200 is a three-phase AC motor, so the inverter 12 is composed of a three-phase full bridge circuit. If the motor 200 is a single-phase AC motor, the inverter 12 is composed of a single-phase bridge circuit. When one motor driving device 1 drives a plurality of motors 200, the motor driving device 1 may be provided with inverters 12 in the same number as the number of motors 200.

[0022] The motor control unit 10 controls the driving of the motor 200 by controlling the inverter 12 that performs power conversion between the DC power in the DC link and the AC power that is the driving power or regenerative power of the motor 200. That is, the motor control unit 10 in the motor driving device 1 generates switching commands for controlling the speed, torque, or rotor position of the motor 200 based on the (rotor) rotation speed (speed feedback) of the motor 200, the current (current feedback) flowing through the windings of the motor 200, a predetermined torque command, an operation program of the motor 200, and the like. The power conversion operation by the inverter 12 is controlled based on the switching commands created by the motor control unit 10. The speed, torque, or rotor position of the motor 200 is controlled based on the AC power supplied from the inverter 12.

[0023] A capacitor 13 is provided in a DC link, which is the DC output side of the converter 11. The capacitor 13 has a function of suppressing pulsation of the DC output from the converter 11 and a function of storing DC power. Examples of the capacitor 13 include an electrolytic capacitor and a film capacitor.

[0024] Capacitor 13 provided in the DC link needs to be pre-charged to a predetermined voltage level after power is applied to motor drive device 1 and before motor 200 starts to drive (i.e., before inverter 12 starts to convert power). Immediately after pre-charging starts, a large inrush current flows from converter 11 to the DC link. Charging circuit 14 has a function of preventing inrush current during the pre-charging period of capacitor 13. In the example shown in FIG. 1, charging circuit 14 is provided between the DC output side of converter 11 and capacitor 13.

[0025] The charging circuit 14 has a charging resistor 21, a charging switch 22, and a main circuit switch 23. The charging control unit 15 controls the open / close states of the charging switch 22 and the main circuit switch 23 to control pre-charging of the capacitor 13 by the charging circuit 14. The charging switch 22 is connected in series to the charging resistor 21, and opens and closes the electric path under the control of the charging control unit 15. The main circuit switch 23 is connected in parallel to the set consisting of the serially connected charging resistor 21 and charging switch 22. The main circuit switch 23 opens and closes the electric path between the converter 11 and the capacitor 13 under the control of the charging control unit 15.

[0026] When the motor drive device 1 is powered on, power starts to be supplied from the AC power source 100 to the motor drive device 1, and pre-charging of the capacitor 13 starts. During the pre-charging period from when the motor drive device 1 is powered on until the motor 200 starts to drive, the charging control unit 15 controls the charging switch 22 to a closed state and the main circuit switch 23 to an open state. During the pre-charging period, the charging switch 22 maintains a closed state and the main circuit switch 23 maintains an open state, so that the current output from the converter 11 flows into the capacitor 13 as a charging current via the charging resistor 21, and the capacitor 13 is charged (pre-charging). In this way, during the pre-charging period, the current output from the converter 11 flows through the charging resistor 21, so that the occurrence of an inrush current can be prevented. After the start of pre-charging, when the capacitor 13 is charged to a predetermined charging voltage, the charging control unit 15 controls the charging switch 22 to an open state and the main circuit switch 23 to a closed state, and the pre-charging of the capacitor 13 is completed. After the preliminary charging is completed, the motor drive device 1 starts driving the motor 200, and the current output from the converter 11 flows through the closed main circuit switch 23 toward the capacitor 13 and the inverter 12. Although details will be described later, when one end of the charging resistor 21 is disconnected from the electric circuit to determine whether or not an abnormality has occurred in the DC link, the charging control unit 15 controls the charging switch 22 and the main circuit switch 23 to the open state.

[0027] The voltage measurement unit 18 measures the voltage applied between the positive and negative terminals of the capacitor 13 (hereinafter simply referred to as "the voltage of the capacitor 13"). The voltage of the capacitor 13 is a DC link voltage which is a terminal-to-terminal voltage of a DC link, that is, the voltage measurement unit 18 detects, as the DC link voltage, the value of the potential difference between the positive potential appearing at the positive terminal of the DC output side of the converter 11 and the negative potential appearing at the negative terminal of the DC output side of the converter 11. The measured value of the voltage of the capacitor 13 acquired by the voltage measurement unit 18 is used in the abnormality determination process by the abnormality determination unit 16, the preliminary charging process by the charging control unit 15, and the DC link voltage control.

[0028] The current measuring unit 19 measures the current flowing through the DC link. In the example shown in Fig. 1, the current measuring unit 10 measures the current flowing between the connection point between the capacitor 13 and the inverter 12, and the charging circuit 14. The measured value of the current flowing through the DC link acquired by the current measuring unit 19 is used in the abnormality determination process by the abnormality determination unit 16.

[0029] The power consumption status acquisition unit 17 is communicatively connected via a communication line to each motor control unit in the motor driving devices 2-1 to 2-n, which are electromechanical systems receiving AC power from the AC power source 100. The communication line may be a wired communication line such as various electric communication cables or optical fiber cables, or a wireless communication line such as WiFi or infrared. The power consumption status acquisition unit 17 acquires parameters relating to the power consumption status of the motor driving devices 2-1 to 2-n (hereinafter referred to as "power consumption parameters") via the communication line.

[0030] Examples of power consumption parameters acquired by power consumption status acquisition unit 17 include the total amount of power (watts) consumed by motor driving devices 2-1 to 2-n, the number of motors 200-1 to 200-n being accelerated by motor driving devices 2-1 to 2-n, the number of capacitors being pre-charged that are provided in the DC links within motor driving devices 2-1 to 2-n, and the total number of motors being accelerating and the number of capacitors being pre-charged in motor driving devices 2-1 to 2-n.

[0031] When the total amount of power consumed by motor driving devices 2-1-2-n is used as the power consumption parameter, the motor control unit and its higher-level control device (not shown) in each of motor driving devices 2-1-2-n are configured to calculate the amount of power consumed by that motor driving device. Power consumption status acquisition unit 17 acquires data relating to the amount of power consumed by motor driving devices 2-1-2-n via a communication line, then calculates the total amount of power consumed by motor driving devices 2-1-2-n that has been acquired, and uses this as the power consumption parameter.

[0032] When the number of motors 200-1 to 200-n being accelerated by motor driving devices 2-1 to 2-n is set as a power consumption parameter, the motor control unit is configured to set an "acceleration flag" which is data indicating that acceleration is in progress while the motor driving unit is accelerating the motor in each of motor driving devices 2-1 to 2-n. That is, in each of motor driving devices 2-1 to 2-n, the acceleration flag is set while the motor driving unit is accelerating the motor, and the acceleration flag is not set while the motor driving unit is not accelerating the motor (i.e., during deceleration or when stopped). Power consumption status acquisition unit 17 calculates the number of motors 200-1 to 200-n being accelerated by motor driving devices 2-1 to 2-n based on the number of acceleration flags acquired via a communication line, and sets this as a power consumption parameter.

[0033] When the number of pre-charging capacitors provided on the DC links in the motor driving devices 2-1 to 2-n is set as the power consumption parameter, a higher-level control device (not shown) is configured to set a "charging flag" which is data indicating that charging is in progress while the capacitor is pre-charging in each of the motor driving devices 2-1 to 2-n. That is, in each of the motor driving devices 2-1 to 2-n, the charging flag is set while the capacitor is pre-charging, and the charging flag is not set while the capacitor is not pre-charging. The power consumption status acquisition unit 17 calculates the number of pre-charging capacitors provided on the DC links in the motor driving devices 2-1 to 2-n based on the number of charging flags acquired via the communication line, and sets this as the power consumption parameter.

[0034] In the case where the power consumption parameter is the sum of the number of motors being accelerated and the number of capacitors being pre-charged in the motor driving devices 2-1 to 2-n, the motor control unit in each of the motor driving devices 2-1 to 2-n is configured to set an "accelerating flag" which is data indicating that the motor is being accelerated while the motor driving unit is accelerating, and a higher-level control device (not shown) is configured to set a "charging flag" which is data indicating that the capacitor is being pre-charged while the capacitor is being pre-charged. The power consumption status acquisition unit 17 calculates the sum of the number of motors being accelerated and the number of capacitors being pre-charged in the motor driving devices 2-1 to 2-n based on the number of accelerating flags and charging flags acquired via the communication line, and sets this as the power consumption parameter. Note that, in calculating the power consumption parameter, weighting may be performed between the number of motors being accelerated and the number of capacitors being pre-charged in the motor driving devices 2-1 to 2-n.

[0035] During the period of pre-charging of capacitor 13, abnormality determination unit 16 determines whether or not an abnormality has occurred based on the measured value of the voltage of capacitor 13, the measured value of the current flowing through capacitor 13, and power consumption parameters. The result of the determination by abnormality determination unit 16 is sent to charging control unit 15. Details of the abnormality determination process by abnormality determination unit 16 will be described later.

[0036] If abnormality determination unit 16 determines that an abnormality has occurred, pre-charging of capacitor 13 is stopped. Pre-charging of capacitor 13 is stopped by cutting off the flow of current from converter 11 to capacitor 13. For example, the charge control unit 15 controls both charging switch 22 and main circuit switch 23 to an open state, or controls a switching device (not shown) such as an electromagnetic contactor provided between converter 11 and AC power source 100 to an open state, thereby cutting off the flow of current from converter 11 to capacitor 13.

[0037] An arithmetic processing device (processor) is provided in the motor drive device 1. The arithmetic processing device may be, for example, an IC, an LSI, a CPU, an MPU, or a DSP. The arithmetic processing device has a charging control unit 15, an abnormality determination unit 16, a power consumption status acquisition unit 17, a voltage measurement unit 18, and a current measurement unit 19. Each of these units of the arithmetic processing device is, for example, a functional module realized by a computer program executed on the processor. For example, when the charging control unit 15, the abnormality determination unit 16, the power consumption status acquisition unit 17, the voltage measurement unit 18, and the current measurement unit 19 are constructed in the form of a computer program, the functions of each unit can be realized by operating the arithmetic processing device according to the computer program. The computer program for executing each process of the charging control unit 15, the abnormality determination unit 16, the power consumption status acquisition unit 17, the voltage measurement unit 18, and the current measurement unit 19 may be provided in a form recorded on a computer-readable recording medium such as a semiconductor memory, a magnetic recording medium, or an optical recording medium. Alternatively, the charging control unit 15, the abnormality determination unit 16, the power consumption status acquisition unit 17, the voltage measurement unit 18, and the current measurement unit 19 may be realized as a semiconductor integrated circuit in which a computer program that realizes the functions of each unit is written.

[0038] In the example shown in FIG. 1, the charging circuit 14 is provided between the DC output side of the converter 11 and the capacitor 13, but may be provided between the AC input side of the converter 11 and the AC power source 100. FIG. 2 is a diagram showing a case where the charging circuit is provided between the AC input side of the converter and the AC power source in a motor drive device according to an embodiment of the present disclosure. As shown in FIG. 2, when the AC power source 100 is a three-phase AC power source, a main circuit switch 23 is provided on at least two phases of the three-phase power lines connecting the AC input side of the converter 11 and the three-phase AC power source 100. In the example shown in FIG. 2, as an example, the main circuit switch 23 is provided on all three-phase power lines connecting the AC input side of the converter 11 and the three-phase AC power source 100. A set of a charging resistor 21 and a charging switch 22 connected in series is connected in parallel to the main circuit switch 23. When AC power supply 100 is a single-phase AC power supply, a main circuit switch 23 is provided on at least one of two power lines connecting the AC input side of converter 11 and single-phase AC power supply 100, and a set consisting of a charging resistor 21 and a charging switch 22 connected in series is connected in parallel to main circuit switch 23. Current measuring unit 19 measures the current flowing between converter 11 and the connection point between capacitor 13 and inverter 12, as the current flowing in the DC link.

[0039] Next, the abnormality determination process by the abnormality determination unit 16 will be described.

[0040] In a motor driving device 1 according to one embodiment of the present disclosure, an abnormality determination unit 16 determines whether or not an abnormality has occurred during the period of pre-charging of the capacitor 13, based on the measured value of the voltage of the capacitor 13, the measured value of the current flowing through the capacitor 13, and power consumption parameters.

[0041] During the period in which capacitor 13 is being pre-charged, if there is no abnormality within motor drive device 1 and the power consumption by motor drive devices 2-1 to 2-n does not affect the pre-charging of motor drive device 1, the measured voltage value of capacitor 13 will rise at a certain rate of increase. On the other hand, if there is an abnormality within motor drive device 1 or the power consumption by motor drive devices 2-1 to 2-n affects the pre-charging of motor drive device 1, the rate of increase of the measured voltage value of capacitor 13 will be small during the period in which capacitor 13 is being pre-charged. A first threshold value Th for distinguishing between large and small rates of increase is set. A is set in advance. The abnormality determination unit 16 determines whether the rate of increase of the measured voltage of the capacitor 13 exceeds the first threshold value Th A In the above cases, it is determined that no abnormality has occurred.

[0042] During the pre-charging period of the capacitor 13, the measured voltage of the capacitor 13 is equal to or lower than the first threshold value Th A If a large current flows through the DC link even though the measured voltage of the capacitor 13 is less than 1 V (i.e., the rate of increase in the measured voltage of the capacitor 13 is small), there is a possibility that an abnormality such as a resistance short circuit has occurred in the DC link in the motor drive device 1. By observing the decreasing trend of the DC link voltage with one end of the charging resistor 21 in the charging circuit 14 disconnected from the electric path, it is possible to determine whether an abnormality such as a resistance short circuit has occurred in the DC link. A second threshold value Th for distinguishing between large and small currents flowing through the DC link is set as B , and a third threshold value Th for determining whether an abnormality such as a resistive short circuit has occurred in the DC link. C is set in advance. When the rate of increase of the measured voltage of the capacitor 13 reaches the first threshold value Th A and the measured current in the DC link is less than the second threshold value Th B In the above cases, one end of the charging resistor 21 is disconnected from the electric path in the charging circuit 14. In this state, the abnormality determination unit 16 determines whether or not the rate of decrease in the measured voltage of the capacitor 13 is equal to or lower than the third threshold value Th C In the above cases, it is determined that an abnormality has occurred in the DC link, and the rate of decrease in the measured voltage of the capacitor 13 does not exceed the third threshold value ThC If it is less than this, it is determined that no abnormality has occurred in the DC link.

[0043] During the pre-charging period of the capacitor 13, the measured voltage of the capacitor 13 is equal to or lower than the first threshold value Th A (i.e., the rate of increase of the measured voltage of the capacitor 13 is small) and the measured current flowing through the DC link is less than the second threshold Th B If it is less than 1 V (i.e. the current flowing through the DC link is small), then there is a possibility that the power consumption by the motor driving devices 2-1 to 2-n is affecting the pre-charging of the motor driving device 1, or that an abnormality has occurred in the charging circuit 14. Examples of abnormalities in the charging circuit 14 include a failure of the charging switch 22, a failure of the main circuit switch 23, and a resistance short circuit caused by a foreign object in the charging circuit 14. By looking at the power consumption parameters indicating the power consumption status of the motor driving devices 2-1 to 2-n, it is possible to determine whether the power consumption by the motor driving devices 2-1 to 2-n is affecting the pre-charging of the motor driving device 1. A fifth threshold value Th E The abnormality determination unit 16 determines whether the power consumption parameter is equal to or exceeds the fifth threshold value Th E If it is equal to or greater than this, it is determined that the power consumption by the motor driving devices 2-1 to 2-n is affecting the pre-charging of the motor driving device 1. If no abnormality has occurred in the charging circuit 14 and the power consumption by the motor driving devices 2-1 to 2-n is simply affecting the pre-charging of the motor driving device 1, there is no particular problem in continuing the pre-charging operation. On the other hand, if the power consumption parameter is greater than or equal to the fifth threshold value Th E If it is less than this, the power consumption by motor driving devices 2-1 to 2-n is not affecting the preliminary charging of motor driving device 1, and therefore abnormality determination unit 16 determines that an abnormality has occurred in charging circuit .

[0044] Unless abnormality determination unit 16 determines that there is an abnormality, pre-charging of capacitor 13 continues, and if abnormality determination unit 16 determines that there is an abnormality, pre-charging of capacitor 13 is stopped. This allows pre-charging of capacitor 13 to be completed efficiently and safely.

[0045] In addition, the first threshold Th A , the second threshold Th B , the third threshold Th C , the fourth threshold Th B , and the fifth threshold Th E The selection is made in advance before the normal operation of the motor drive device 1. For example, a system consisting of the motor drive device 1 that has been confirmed to be free of abnormalities and the motor drive devices 2-1 to 2-n that share the AC power source 100 with the motor drive device 1, and a system consisting of the motor drive device 1 that simulates abnormalities in the DC link and the charging circuit 14 and the motor drive devices 2-1 to 2-n that share the AC power source 100 with the motor drive device 1 are constructed by real equipment or computer simulation. Then, the pre-charging operation is reproduced by operating the real system or the computer simulation system, and the measured values ​​of the voltage of the capacitor 13 and the measured values ​​of the current flowing through the DC link are obtained. Taking into account the obtained measured values ​​and the operating environment of the motor drive device 1, etc., as appropriate, a first threshold value Th that can distinguish whether an abnormality has occurred and whether the power consumption of the motor drive devices 2-1 to 2-n has an effect on the pre-charging of the motor drive device 1 is determined. A , the second threshold Th B , the third threshold Th C , the fourth threshold Th B , and the fifth threshold Th E In addition, when the total amount of power (wattage) consumed by the motor driving devices 2-1 to 2-n is used as the power consumption parameter, the fifth threshold value Th E When the number of motors 200-1 to 200-n being accelerated by motor driving devices 2-1 to 2-n is used as the power consumption parameter, the fifth threshold value Th EIn the case where the number of pre-charging capacitors provided in the DC links of the motor driving devices 2-1 to 2-n is set as the power consumption parameter, the fifth threshold value Th E In the case where the total number of motors being accelerated and the total number of capacitors being pre-charged for the motor driving devices 2-1 to 2-n are used as the power consumption parameters, the fifth threshold value Th E The number of capacitors and motors is set.

[0046] The first threshold value Th A , the second threshold Th B , the third threshold Th C , the fourth threshold Th B , and the fifth threshold Th E is stored in a storage unit (not shown) in the abnormality determination unit 16 or in a storage unit (not shown) connected to the abnormality determination unit 16. The storage unit may be configured with an electrically erasable and recordable non-volatile memory such as an EEPROM (registered trademark), or a high-speed readable and writable random access memory such as a DRAM or an SRAM. If the storage unit is realized by a rewritable storage device, the first threshold value Th A , the second threshold Th B , the third threshold Th C , the fourth threshold Th B , and / or a fifth threshold Th E Even after being set once, it can be changed to an appropriate value as necessary. For example, the first threshold value Th stored in the storage unit can be changed according to a change in the capacitance due to deterioration of the capacitor 13. A , the second threshold Th B , the third threshold Th C , and / or a fourth threshold Th B In addition, for example, the number of motor drive devices 2-1 to 2-n in an electromechanical system that shares the motor drive device 1 and the AC power supply 100 may be changed, the operation program may be changed, or the configuration of the machine may be changed. In accordance with such changes in the electromechanical system, the fifth threshold value Th E You can rewrite it as follows:

[0047] FIG. 3 is a flowchart showing a pre-charging operation in the motor drive device according to one embodiment of the present disclosure.

[0048] In step S101, while charging control unit 15 controls charging switch 22 to a closed state and main circuit switch 23 to an open state, when AC power supply 100 is turned on to motor drive device 1, power begins to be supplied from AC power supply 100 to motor drive device 1, and pre-charging of capacitor 13 begins.

[0049] After waiting for a certain period of time in step S102, in step S103, voltage measurement unit 18 measures the voltage of capacitor 13, and current measurement unit 19 measures the current flowing through the DC link. The measured voltage value is sent to abnormality determination unit 16 and charging control unit 15, and the measured current value is sent to abnormality determination unit 16.

[0050] In step S104, the abnormality determination unit 16 determines whether the rate of increase of the measured value of the voltage of the capacitor 13 is equal to or exceeds the first threshold value Th A It is determined whether or not it is equal to or greater than this.

[0051] In step S104, the rate of increase of the measured voltage of the capacitor 13 is determined to be equal to or greater than the first threshold value Th A If it is determined that the rate of increase of the measured voltage of the capacitor 13 is equal to or greater than the first threshold value Th in step S104, the process proceeds to step S105. A If it is determined that the number is less than the above, the process proceeds to step S108.

[0052] In step S105, the abnormality determination unit 16 determines that no abnormality has occurred.

[0053] In step S106 following step S105, the charging control unit 15 determines whether or not pre-charging of the capacitor 13 has been completed based on whether or not the measured voltage value sent from the voltage measurement unit 18 has reached a predetermined charging voltage. If the measured voltage value sent from the voltage measurement unit 18 has not reached the predetermined charging voltage, the charging control unit 15 determines in step S106 that pre-charging of the capacitor 13 has not been completed, and then the process returns to step S102. On the other hand, if the measured voltage value sent from the voltage measurement unit 18 has reached the predetermined charging voltage, the charging control unit 15 determines in step S106 that pre-charging of the capacitor 13 has been completed, and the process proceeds to step S107.

[0054] In step S107, the charging control unit 15 controls the charging switch 22 to an open state and the main circuit switch 23 to a closed state, thereby terminating the preliminary charging of the capacitor. After the preliminary charging is terminated, the motor driving device 1 drives the motor 200 by causing the converter 11 and the inverter 12 to perform normal power conversion operations.

[0055] In step S104, the rate of increase of the measured voltage of the capacitor 13 is determined to be equal to or greater than the first threshold value Th A If it is determined that the measured value of the current flowing through the DC link is equal to or greater than the second threshold value Th in step S108, the abnormality determination unit 16 B In step S108, it is determined whether the measured value of the current flowing through the DC link is equal to or greater than the second threshold value Th B If it is determined that the measured value of the current flowing through the DC link is equal to or greater than the second threshold value Th, the process proceeds to step S109. B If it is determined that the difference is less than the predetermined value, the process proceeds to step S115.

[0056] In step S108, the measured value of the current flowing through the DC link is equal to or exceeds a second threshold value Th BIf it is determined that this is the case, in step S109, charging control unit 15 performs a disconnection operation using charging switch 22. That is, charging control unit 15 performs control to switch charging switch 22 from a closed state to an open state, thereby disconnecting one end of charging resistor 21 in charging circuit 14 from the electric path.

[0057] In step S110, the abnormality determination unit 16 determines whether the rate of decrease of the measured voltage of the capacitor 13 is equal to or smaller than the third threshold value Th C It is determined whether or not it is equal to or greater than this.

[0058] In step S110, the rate of decrease in the measured voltage of the capacitor 13 is equal to or lower than the third threshold value Th C If it is determined that the difference is equal to or greater than this, the process proceeds to step S112, where the abnormality determination unit 16 determines that an abnormality has occurred in the DC link, and then the process proceeds to step S113.

[0059] In step S110, the rate of decrease in the measured voltage of the capacitor 13 is equal to or lower than the third threshold value Th C If it is determined that the difference is less than the predetermined value, the process proceeds to step S111. In step S111, the charging control unit 15 performs a re-connection operation using the charging switch 22. That is, the charging control unit 15 performs control to switch the charging switch 22 from an open state to a closed state, thereby re-connecting the charging resistor 21 to the electric path in the charging circuit 14. Then, the process proceeds to step S105.

[0060] In step S108, the measured value of the current flowing through the DC link is equal to or exceeds a second threshold value Th B If it is determined that the measured value of the current flowing through the DC link is less than the fourth threshold value Th, in step S115, the abnormality determination unit 16 D In step S115, it is determined whether the measured value of the current flowing through the DC link is smaller than the fourth threshold value Th D If it is determined that the measured value of the current flowing through the DC link is smaller than the fourth threshold value Th, the process proceeds to step S116. D If it is determined that the number is equal to or greater than the limit, the process proceeds to step S105.

[0061] In step S116, power consumption status acquisition unit 17 acquires power consumption parameters indicating the power consumption status of motor driving devices 2-1 to 2-n via the communication line.

[0062] In step S117, the abnormality determination unit 16 determines whether the power consumption parameter is equal to or exceeds the fifth threshold value Th E In step S117, it is determined whether the power consumption parameter is smaller than the fifth threshold value Th E If it is determined that the power consumption parameter is smaller than the fifth threshold Th, the process proceeds to step S105. E If it is determined that the number is equal to or greater than the limit, the process proceeds to step S118.

[0063] In step S117, the power consumption parameter is equal to or exceeds a fifth threshold Th E If it is determined that the number is equal to or greater than this, in step S118, abnormality determination unit 16 determines that an abnormality has occurred in charging circuit 14, and then the process proceeds to step S113.

[0064] If the abnormality determination unit 16 determines in step S112 that an abnormality has occurred in the DC link, or if the abnormality determination unit 16 determines in step S117 that an abnormality has occurred in the charging circuit 14, the pre-charging of the capacitor 13 is stopped in step S113. The pre-charging of the capacitor 13 is stopped by interrupting the inflow of current from the converter 11 to the capacitor 13. After the pre-charging of the capacitor 13 is stopped, the process is terminated in the form of "abnormal termination" (step S114). In addition, in the case of abnormal termination in step S114, a display unit (not shown) may be used to notify an operator that "an abnormality has occurred in the DC link" or "an abnormality has occurred in the charging circuit". Examples of the display unit include a standalone display device, a display device attached to the motor drive device 1, a display device attached to a higher-level control device (not shown), and a display device attached to a personal computer and a mobile terminal. In addition, for example, a light-emitting device (not shown) such as an LED or a lamp may be used to notify an operator that "an abnormality has occurred in the DC link" or "an abnormality has occurred in the charging circuit". Also, for example, an audio device (not shown) may be used to notify an operator that "an abnormality has occurred in the DC link" or "an abnormality has occurred in the charging circuit." This allows the operator to easily understand whether the cause of the abnormal termination of pre-charging of capacitor 13 is an abnormality in the DC link or in the charging circuit 14, and the operator can easily take measures such as replacing the part related to the abnormality or removing the cause of the abnormality.

[0065] Next, several modified examples of the motor drive device 1 according to an embodiment of the present disclosure will be listed. In the modified examples described below, the charging circuit 14 is provided between the DC output side of the converter 11 and the capacitor 13, but the charging circuit 14 may be provided between the AC input side of the converter 11 and the AC power source 100.

[0066] A first modified example of the motor driving device 1 according to an embodiment of the present disclosure is applied to the motor driving device 1 of FIG. 1 or FIG. 2 when there is no other electromechanical system connected to the AC power supply 100 other than the motor driving device 1.

[0067] FIG. 4 is a diagram illustrating a first modified example of a motor driving device according to an embodiment of the present disclosure.

[0068] In a first modified example of a motor drive device according to an embodiment of the present disclosure, there is no electromechanical system receiving power from AC power supply 100 other than motor drive device 1, and therefore there is no need for a power consumption status acquisition unit as described with reference to Figures 1 and 2. That is, motor drive device 1 according to the first modified example includes converter 11, inverter 12, capacitor 13, charging circuit 14, charging control unit 15, abnormality determination unit 16, voltage measurement unit 18, and current measurement unit 19.

[0069] Abnormality determination unit 16 determines whether or not an abnormality has occurred based on the measured value of the voltage of capacitor 13 and the measured value of the current flowing through the DC link during the period of pre-charging of capacitor 13. Converter 11, inverter 12, capacitor 13, charging circuit 14, charging control unit 15, voltage measurement unit 18, and current measurement unit 19 are as described with reference to Figures 1 and 2.

[0070] FIG. 5 is a flowchart showing a pre-charging operation in the first modified example of the motor drive device according to an embodiment of the present disclosure.

[0071] In step S201, while charging control unit 15 controls charging switch 22 to a closed state and main circuit switch 23 to an open state, when AC power supply 100 is turned on to motor drive device 1, power begins to be supplied from AC power supply 100 to motor drive device 1, and pre-charging of capacitor 13 begins.

[0072] After waiting for a certain period of time in step S202, in step S203, voltage measurement unit 18 measures the voltage of capacitor 13, and current measurement unit 19 measures the current flowing through the DC link. The measured voltage value is sent to abnormality determination unit 16 and charging control unit 15, and the measured current value is sent to abnormality determination unit 16.

[0073] In step S204, the abnormality determination unit 16 determines whether the rate of increase of the measured value of the voltage of the capacitor 13 is equal to or exceeds the first threshold value Th A It is determined whether or not it is equal to or greater than this.

[0074] In step S204, the rate of increase of the measured voltage of the capacitor 13 is determined to be equal to or greater than the first threshold value Th A If it is determined that the rate of increase of the measured value of the voltage of the capacitor 13 is equal to or greater than the first threshold value Th in step S204, the process proceeds to step S205. A If it is determined that the number is less than the above, the process proceeds to step S208.

[0075] In step S205, the abnormality determination unit 16 determines that no abnormality has occurred.

[0076] In step S206 following step S205, the charging control unit 15 determines whether or not pre-charging of the capacitor 13 has been completed based on whether or not the measured voltage value sent from the voltage measurement unit 18 has reached a predetermined charging voltage. If the measured voltage value sent from the voltage measurement unit 18 has not reached the predetermined charging voltage, the charging control unit 15 determines in step S206 that pre-charging of the capacitor 13 has not been completed, and then the process returns to step S202. On the other hand, if the measured voltage value sent from the voltage measurement unit 18 has reached the predetermined charging voltage, the charging control unit 15 determines in step S106 that pre-charging of the capacitor 13 has been completed, and the process proceeds to step S207.

[0077] In step S207, the charging control unit 15 controls the charging switch 22 to an open state and the main circuit switch 23 to a closed state, thereby terminating the preliminary charging of the capacitor. After the preliminary charging is terminated, the motor driving device 1 drives the motor 200 by causing the converter 11 and the inverter 12 to perform normal power conversion operations.

[0078] In step S204, the rate of increase of the measured voltage of the capacitor 13 is determined to be equal to or greater than the first threshold value Th A If it is determined that the measured value of the current flowing through the DC link is equal to or greater than the second threshold value Th, in step S208, the abnormality determination unit 16 B In step S208, it is determined whether the measured value of the current flowing through the DC link is equal to or greater than the second threshold value Th B If it is determined that the measured value of the current flowing through the DC link is equal to or greater than the second threshold value Th, the process proceeds to step S209. B If it is determined that the difference is less than the predetermined value, the process proceeds to step S205.

[0079] In step S208, the measured value of the current flowing through the DC link is equal to or exceeds a second threshold value Th B If it is determined that this is the case, in step S209, charging control unit 15 performs a disconnection operation using charging switch 22. That is, charging control unit 15 performs control to switch charging switch 22 from a closed state to an open state, thereby disconnecting one end of charging resistor 21 in charging circuit 14 from the electric path.

[0080] In step S210, the abnormality determination unit 16 determines whether the rate of decrease of the measured voltage of the capacitor 13 is equal to or smaller than the third threshold value Th C It is determined whether or not it is equal to or greater than this.

[0081] In step S210, the rate of decrease in the measured voltage of the capacitor 13 is equal to or lower than the third threshold value Th CIf it is determined that the difference is less than the predetermined value, the process proceeds to step S211. In step S211, the charging control unit 15 performs a re-connection operation using the charging switch 22. That is, the charging control unit 15 performs control to switch the charging switch 22 from an open state to a closed state, thereby re-connecting the charging resistor 21 to the electric path in the charging circuit 14. Then, the process proceeds to step S205.

[0082] In step S210, the rate of decrease in the measured voltage of the capacitor 13 is equal to or lower than the third threshold value Th C If it is determined that this is the case, the process proceeds to step S212, where abnormality determination section 16 determines that an abnormality has occurred in motor drive device 1, and then the process proceeds to step S213.

[0083] In step S213, the pre-charging of the capacitor 13 is stopped. The pre-charging of the capacitor 13 is stopped by interrupting the inflow of current from the converter 11 to the capacitor 13. After the pre-charging of the capacitor 13 is stopped, the process ends with an "abnormal end" (step S214). In the case of an abnormal end in step S214, a display unit (not shown), a light-emitting device such as an LED or lamp (not shown), or an audio device (not shown) may be used to notify an operator that "an abnormality has occurred." This allows the operator to easily grasp the occurrence of an abnormality in the motor drive device 1, and to easily take measures such as replacing a part related to the abnormality or removing the cause of the abnormality.

[0084] In this way, in the first modified example, the abnormality determination unit 16 determines whether or not an abnormality has occurred based on the measured value of the voltage of the capacitor 13 and the measured value of the current flowing through the DC link during the period in which the capacitor 13 is pre-charged. However, the abnormality determination unit 16 may determine whether or not an abnormality has occurred based on only one of the measured value of the voltage of the capacitor 13 and the measured value of the current flowing through the DC link. For example, in a configuration in which the abnormality determination unit 16 determines whether or not an abnormality has occurred based only on the measured value of the voltage of the capacitor 13, step S208 in FIG. 5 is omitted, and in step S204, the abnormality determination unit 16 determines whether or not an abnormality has occurred based on the measured value of the voltage of the capacitor 13 when the rate of increase of the measured value of the voltage of the capacitor 13 exceeds the first threshold value Th. AIf it is determined that the difference is less than or equal to the above, the process proceeds to step S209. In addition, for example, in a configuration in which the abnormality determination unit 16 determines whether or not an abnormality has occurred based only on the measurement value of the current flowing through the DC link, step S204 in Fig. 5 is omitted, and after the current measurement unit 19 measures the current flowing through the DC link in step S203, the process of step S208 is executed.

[0085] A second modified example of the motor drive device 1 according to an embodiment of the present disclosure is a device in which, in the motor drive device 1 of FIG. 1 or FIG. 2, a determination is made as to whether or not to continue pre-charging based solely on the power consumption status of an electromechanical system that shares an AC power supply 100 with the motor drive device 1.

[0086] Fig. 6 is a diagram showing a second modified example of a motor drive device according to an embodiment of the present disclosure. In the example shown in Fig. 6, as an example, n (n is a positive integer) motor drive devices 2-1 to 2-n are connected to an AC power source 100 as an electromechanical system, but the electromechanical system connected to the AC power source 100 is not limited to the motor drive devices 2-1 to 2-n and may be any machine that receives a supply of AC power from the AC power source 100.

[0087] In the second modified example of the motor drive device according to an embodiment of the present disclosure, since abnormality determination processing based on the measured value of the current flowing through the DC link is not performed, there is no need for a current detection unit as described with reference to Figures 1 and 2. Note that in the second modified example, abnormality determination processing based on the measured value of the voltage of the capacitor 13 is also not performed, but since the measured value of the voltage of the capacitor 13 is used to determine whether the capacitor 13 has reached a predetermined charging voltage, a voltage measurement unit 18 is necessary. For this reason, the motor drive device 1 according to the second modified example includes a converter 11, an inverter 12, a capacitor 13, a charging circuit 14, a charging control unit 15, an abnormality determination unit 16, a power consumption status acquisition unit 17, and a voltage measurement unit 18.

[0088] During the period of pre-charging of capacitor 13, abnormality determination unit 16 determines whether or not an abnormality has occurred based on power consumption parameters indicating the power consumption status of motor driving devices 2-1 to 2-n, which are electromechanical systems that share AC power source 100 with motor driving device 1. Converter 11, inverter 12, capacitor 13, charging circuit 14, charging control unit 15, power consumption status acquisition unit 17, and voltage measurement unit 18 are as described with reference to Figures 1 and 2.

[0089] FIG. 7 is a flowchart showing a pre-charging operation in the second modified example of the motor drive device according to an embodiment of the present disclosure.

[0090] In step S301, while charging control unit 15 controls charging switch 22 to a closed state and main circuit switch 23 to an open state, when AC power supply 100 is turned on to motor drive device 1, power begins to be supplied from AC power supply 100 to motor drive device 1, and pre-charging of capacitor 13 begins.

[0091] After waiting for a certain period of time in step S302, in step S303, the voltage measuring unit 18 measures the voltage of the capacitor 13. The measured voltage value is sent to the abnormality determination unit 16 and the charging control unit 15.

[0092] In step S304, power consumption status acquisition unit 17 acquires power consumption parameters indicating the power consumption status of motor driving devices 2-1 to 2-n via a communication line.

[0093] In step S305, the abnormality determination unit 16 determines whether the power consumption parameter is equal to or exceeds the fifth threshold value Th E In step S305, it is determined whether the power consumption parameter is smaller than the fifth threshold Th E If it is determined that the power consumption parameter is smaller than the fifth threshold value Th, the process proceeds to step S306. E If it is determined that the number is equal to or greater than the limit, the process proceeds to step S309.

[0094] In step S306, the abnormality determination unit 16 determines that no abnormality has occurred.

[0095] In step S307 following step S306, the charging control unit 15 determines whether pre-charging of the capacitor 13 has been completed based on whether the measured voltage value sent from the voltage measurement unit 18 has reached a predetermined charging voltage. If the measured voltage value sent from the voltage measurement unit 18 has not reached the predetermined charging voltage, the charging control unit 15 determines in step S307 that pre-charging of the capacitor 13 has not been completed, and the process then returns to step S302. On the other hand, if the measured voltage value sent from the voltage measurement unit 18 has reached the predetermined charging voltage, the charging control unit 15 determines in step S307 that pre-charging of the capacitor 13 has been completed, and the process proceeds to step S308.

[0096] In step S308, the charging control unit 15 controls the charging switch 22 to an open state and the main circuit switch 23 to a closed state, thereby terminating the preliminary charging of the capacitor. After the preliminary charging is terminated, the motor driving device 1 drives the motor 200 by causing the converter 11 and the inverter 12 to perform normal power conversion operations.

[0097] In step S305, the power consumption parameter is equal to or exceeds a fifth threshold Th E If it is determined that this is the case, then in step S309, abnormality determination section 16 determines that an abnormality has occurred in motor drive device 1, and then the process proceeds to step S310.

[0098] In step S310, the pre-charging of the capacitor 13 is stopped. The pre-charging of the capacitor 13 is stopped by interrupting the inflow of current from the converter 11 to the capacitor 13. After the pre-charging of the capacitor 13 is stopped, the process ends with an "abnormal end" (step S311). In the case of an abnormal end in step S311, a display unit (not shown), a light-emitting device such as an LED or lamp (not shown), or an audio device (not shown) may be used to notify an operator that "an abnormality has occurred." This allows the operator to easily grasp the occurrence of an abnormality in the motor drive device 1, and to easily take measures such as replacing a part related to the abnormality or removing the cause of the abnormality.

[0099] The first and second modified examples have the advantages of being simpler in configuration and lower in cost than the embodiment described with reference to FIGS.

[0100] As described above, according to one embodiment, the first variant and the second variant of the present disclosure, pre-charging can be continued and completed safely as long as there is no abnormality in the motor drive device, which is efficient and can reduce the number of alarm stops related to pre-charging. [Explanation of symbols]

[0101] 1 Motor drive unit 10 Motor control unit 11 Converter 12 Inverter 13 Capacitor 14 Charging circuit 15 Charging control unit 16 Abnormality determination section 17 Power consumption status acquisition unit 18 Voltage measurement section 19 Current measurement section 21 Charging resistance 22 Charging switch 23 Main circuit switch 100 AC power supply 200 Motor

Claims

1. a converter that converts AC power supplied from an AC power source into DC power and outputs the DC power to a DC link; A capacitor provided in the DC link; an inverter that converts DC power in the DC link into AC power for driving a motor and outputs the AC power; a charging circuit having a charging resistor for preventing inrush current during a period of precharging the capacitor; a charge control unit that controls pre-charging of the capacitor by the charging circuit; an abnormality determination unit that determines whether or not an abnormality has occurred based on at least one of a measured value of a voltage of the capacitor and a measured value of a current flowing through the DC link during a period in which the capacitor is pre-charged; Equipped with the abnormality determination unit determines that no abnormality has occurred when a rate of increase in the measured value of the capacitor voltage is equal to or greater than a first threshold value; the charging control unit executes control to disconnect one end of the charging resistor from an electric path when a rate of increase of a measured value of a voltage of the capacitor is less than the first threshold value and a measured value of a current flowing through the DC link is equal to or greater than a second threshold value; The abnormality determination unit determines that an abnormality has occurred when a rate of decrease in the measured value of the capacitor voltage is equal to or greater than a third threshold value when the charging control unit is executing control to disconnect one end of the charging resistor from the electric circuit, and determines that no abnormality has occurred when the rate of decrease in the measured value of the capacitor voltage is less than the third threshold value.

2. a power consumption status acquisition unit that acquires parameters related to a power consumption status of an electromechanical system that receives AC power from the AC power source, The motor drive device according to claim 1 , wherein the abnormality determination unit determines whether or not an abnormality has occurred based on the parameter.

3. 3. The motor drive device according to claim 2, wherein in a state in which a rate of increase of the measured value of the capacitor voltage is less than the first threshold and the measured value of the current flowing through the DC link is less than a fourth threshold that is smaller than the second threshold, the abnormality determination unit determines that an abnormality has occurred if the parameter is less than a fifth threshold, and determines that no abnormality has occurred if the parameter is equal to or greater than the fifth threshold.

4. a converter that converts AC power supplied from an AC power source into DC power and outputs the DC power to a DC link; A capacitor provided in the DC link; an inverter that converts DC power in the DC link into AC power for driving a motor and outputs the AC power; a charging circuit having a charging resistor for preventing inrush current during a period of precharging the capacitor; a charge control unit that controls pre-charging of the capacitor by the charging circuit; a power consumption status acquiring unit that acquires parameters related to a power consumption status of an electromechanical system that receives a supply of AC power from the AC power source; an abnormality determination unit that determines whether or not an abnormality has occurred based on a measured value of a voltage of the capacitor, a measured value of a current flowing through the DC link, and the parameters during a period in which the capacitor is pre-charged; A motor drive device comprising:

5. a converter that converts AC power supplied from an AC power source into DC power and outputs the DC power to a DC link; A capacitor provided in the DC link; an inverter that converts DC power in the DC link into AC power for driving a motor and outputs the AC power; a charging circuit having a charging resistor for preventing inrush current during a period of precharging the capacitor; a charge control unit that controls pre-charging of the capacitor by the charging circuit; a power consumption status acquiring unit that acquires parameters related to a power consumption status of an electromechanical system that receives a supply of AC power from the AC power source; an abnormality determination unit that determines whether or not an abnormality has occurred based on the parameters during a period in which the capacitor is pre-charged; A motor drive device comprising:

6. 6. The motor drive device according to claim 5, wherein the abnormality determination unit determines that an abnormality has occurred when the parameter is less than a fifth threshold value, and determines that no abnormality has occurred when the parameter is equal to or greater than the fifth threshold value.

7. The motor drive device according to any one of claims 2 to 6, wherein the parameter is a magnitude of power consumption of the electromechanical system.

8. the electromechanical system being at least one further motor drive; The motor drive device according to any one of claims 2 to 6, wherein the parameter is any one of the number of motors being accelerated by the further motor drive device, the number of pre-charging capacitors provided in a DC link in the further motor drive device, and the sum of the number of the motors being accelerating and the number of the pre-charging capacitors.

9. 9. The motor drive device according to claim 1, wherein the charge control unit executes control to stop pre-charging the capacitor when the abnormality determination unit determines that an abnormality has occurred.

10. the charging circuit includes: the charging resistor; a charging switch connected in series to the charging resistor and configured to open and close an electric path under control of the charging control unit; and a main circuit switch connected in parallel to a set of the serially connected charging resistor and the charging switch and configured to open and close an electric path between the converter and the capacitor or between the converter and the AC power source under control of the charging control unit; The charging control unit controls the charging switch to a closed state and the main circuit switch to an open state, thereby performing pre-charging of the capacitor, The motor drive device according to any one of claims 1 to 9, wherein after pre-charging of the capacitor has started, when the capacitor has been charged to a predetermined charging voltage, the charging control unit controls the charging switch to an open state and the main circuit switch to a closed state, thereby completing pre-charging of the capacitor.

11. 11. The motor drive device according to claim 10, wherein the charge control unit controls the charge switch to an open state during a period of pre-charging the capacitor, thereby executing control to disconnect one end of the charging resistor from an electric path.

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