Motor drive device that identifies type of connection of ac power supply

Abstract

This motor drive device comprises: an inverter that drives a motor; a converter that converts AC power supplied from a three-phase AC power supply into DC power and supplies the DC power to the inverter; a preliminary charging circuit that performs a preliminary charging operation for charging a capacitor with the current supplied via a preliminary charging resistor during an open period of a preliminary charging switch, and completes the preliminary charging operation of the capacitor by switching the preliminary charging switch from open to closed; a ground-to-ground voltage detection unit that detects the value of the ground-to-ground voltage between a DC link and the ground; and an identification unit that identifies the type of connection of the three-phase AC power supply on the basis of the value of the ground-to-ground voltage detected by the ground-to-ground voltage detection unit.

Description

Motor drive device for identifying the type of AC power supply wiring

[0001] The present disclosure relates to a motor drive device that identifies the type of wiring of an AC power supply.

[0002] A motor drive device that drives an AC motor is provided with a converter and an inverter. The converter and inverter are connected via a DC link. The converter converts AC power supplied from an AC power source into DC power and outputs it. The inverter converts this DC power into AC power for driving the motor and outputs it.

[0003] Japanese Patent Application Laid-Open No. 2005-016958

[0004] There are two types of connection configurations for a three-phase AC power supply connected to a motor drive device: delta connection (Δ connection) and Y connection (star connection). Selecting the wrong type of connection for the three-phase AC power supply can potentially damage the motor drive device. Therefore, there is a need for technology that can accurately identify the type of connection for a three-phase AC power supply connected to a motor drive device.

[0005] According to one aspect of the present disclosure, a motor drive device includes: an inverter that drives a motor; a converter that converts AC power supplied from an AC power supply into DC power and supplies the DC power to the inverter via a DC link; a pre-charging circuit having a pre-charging resistor that suppresses inrush current during a pre-charging period of a capacitor provided in the DC link; and a pre-charging switch connected in parallel to the pre-charging resistor, wherein the pre-charging circuit performs a pre-charging operation to charge the capacitor with current supplied via the pre-charging resistor while the pre-charging switch is open, and completes the pre-charging operation of the capacitor when the pre-charging switch is switched from open to closed; a ground voltage detection unit that detects a value of a ground voltage between the DC link and ground; and an identification unit that identifies a wiring type of the AC power supply based on the value of the ground voltage detected by the ground voltage detection unit.

[0006] FIG. 1 is a diagram illustrating a motor drive device according to an embodiment of the present disclosure. FIG. 1 is a diagram illustrating a motor drive device connected to an AC power supply configured in a Y connection. FIG. 2 is a waveform diagram illustrating an example of a line-to-ground voltage, an input line voltage, and a DC link voltage in a motor drive device connected to an AC power supply configured in a Y connection. FIG. 2 is a diagram illustrating a motor drive device connected to an AC power supply configured in a delta connection. FIG. 3 is a waveform diagram illustrating an example of a line-to-ground voltage, an input line voltage, and a DC link voltage in a motor drive device connected to an AC power supply configured in a delta connection. FIG. 4 is a simulation waveform diagram illustrating an example of a line-to-ground voltage and a DC link voltage in a motor drive device connected to an AC power supply configured in a Y connection. FIG. 5 is a simulation waveform diagram illustrating an example of a line-to-ground voltage and a DC link voltage in a motor drive device connected to an AC power supply configured in a delta connection. FIG. 6 is a waveform diagram illustrating a first threshold value used in a discrimination process in a motor drive device according to an embodiment of the present disclosure. FIG. 7 is a waveform diagram illustrating a second threshold value used in a discrimination process in a motor drive device according to an embodiment of the present disclosure. FIG. 8 is a waveform diagram illustrating a third threshold value used in a discrimination process in a motor drive device according to an embodiment of the present disclosure. FIG. 1 is a waveform diagram illustrating a fourth threshold value used in the discrimination process in the motor drive device according to an embodiment of the present disclosure. FIG. 2 is a flowchart illustrating the operation of the discrimination process using a first threshold value in the motor drive device according to an embodiment of the present disclosure. FIG. 3 is a flowchart illustrating the operation of the discrimination process using a second threshold value in the motor drive device according to an embodiment of the present disclosure. FIG. 4 is a flowchart illustrating the operation of the discrimination process using a third threshold value in the motor drive device according to an embodiment of the present disclosure. FIG. 5 is a flowchart illustrating the operation of the discrimination process using a fourth threshold value in the motor drive device according to an embodiment of the present disclosure.

[0007] A motor drive device for identifying the type of AC power supply wiring connection according to an embodiment will be described below 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, a converter that converts AC power supplied from an AC power source into DC power and outputs it is also referred to as a “rectifier device,” “rectifier circuit,” “rectifier,” or “forward converter.” An inverter that converts DC power into AC power and outputs it is also referred to as 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, and is also referred to as a “DC link unit,” “DC link,” “DC link unit,” “DC bus,” or “DC intermediate circuit.” A pre-charging circuit is also referred to as an “initial charging circuit” or “inrush current suppression circuit.” A “pre-charging period” refers to a period during which pre-charging of a capacitor is performed. A “DC link voltage” refers to the potential difference between the positive side potential of the positive power line and the negative side potential of the negative power line of the DC link, or the voltage obtained by dividing the potential difference between the positive side potential of the positive power line and the negative side potential of the negative power line of the DC link using a voltage divider resistor. The term "input line voltage" refers to the line voltage of the AC voltage input to the converter from a three-phase AC power source. The term "voltage to ground" refers to the potential difference between the positive potential of the positive power line of the DC link and the ground potential (ground potential), or a voltage obtained by dividing the potential difference between the positive potential of the positive power line of the DC link and the ground potential (ground potential) using a voltage divider resistor. The term "voltage to ground" may also refer to the potential difference between the negative potential of the negative power line of the DC link and the ground potential (ground potential), or a voltage obtained by dividing the potential difference between the negative potential of the negative power line of the DC link and the ground potential (ground potential) using a voltage divider resistor. In the embodiments described below, the term "voltage to ground" refers to the potential difference between the positive potential of the positive power line of the DC link and the ground potential (ground potential), or a voltage obtained by dividing the potential difference between the positive potential of the positive power line of the DC link and the ground potential (ground potential) using a voltage divider resistor, as an example.

[0009] <Configuration of a Motor Drive Device According to an Embodiment of the Present Disclosure> FIG. 1 is a diagram illustrating a motor drive device according to an embodiment of the present disclosure.

[0010] In one embodiment of the present disclosure, as an example, a case is shown in which an AC motor 3 is driven by a motor drive device 1 connected to a three-phase AC power supply 2. Examples of three-phase AC power supplies 2 include a three-phase 480V AC power supply, a three-phase 400V AC power supply, a three-phase 200V AC power supply, and a three-phase 600V AC power supply. The number of phases of the motor 3 is not particularly limited to each embodiment, and may be, for example, three-phase or single-phase. Here, as an example, the motor 3 is three-phase. The number of motors 3 is not particularly limited to each embodiment, and may be multiple. Here, as an example, the number of motors 3 is one. Machines in which the motor 3 is provided include, for example, machine tools and robots.

[0011] 1, a motor drive device 1 according to an embodiment of the present disclosure includes a converter 11, an inverter 12, a pre-charging circuit 13, a line-to-ground voltage detection unit 14, an identification unit 15, a notification unit 16, a switching unit 17, an input line voltage detection unit 18, a switching control unit 19, a motor control unit 20, and a capacitor 21. An AC reactor, an AC line filter, and the like may be provided on the AC input side of converter 11, but are not shown here.

[0012] The switching unit 17 is provided on the AC input side of the converter 11, and opens and closes the electrical path between the AC power source 2 and the converter 11. The opening and closing operation of the switching unit 17 is controlled by a switching control unit 19. A closing operation to form an electrical path between the AC power source 2 and the converter 11 is achieved by closing the contacts of the switching unit 17. An opening operation to interrupt the electrical path between the AC power source 2 and the converter 11 is achieved by opening the contacts of the switching unit 17. The switching unit 17 is configured with, for example, an electromagnetic contactor, a relay, a semiconductor switching element, etc.

[0013] The converter 11 converts AC power supplied from the AC power source 2 via the closed switch 17 into DC power and outputs the DC power to a DC link, which is the DC output side of the converter 11. The converter 11 is configured as a three-phase bridge circuit. Examples of the converter 11 include a diode rectifier, a PWM switching control rectifier, and a 120-degree conduction rectifier. For example, when the converter 11 is configured as a diode rectifier, it is configured as a three-phase bridge circuit of diodes. When the converter 11 is configured as a PWM switching control rectifier or a 120-degree conduction rectifier, it is configured as a three-phase bridge circuit of semiconductor switching elements and diodes connected in antiparallel to the semiconductor switching elements. Examples of the semiconductor switching elements include FETs, IGBTs, thyristors, GTOs (gate turn-off thyristors), and transistors, but other switching elements may also be used.

[0014] The capacitor 21 is provided in a DC link between the DC output side of the converter 11 and the DC input side of the inverter 12. One end of the capacitor 21 is connected to a positive power line 41P of the DC link, and the other end of the capacitor 21 is connected to a negative power line 41N of the DC link. The capacitor 21 is sometimes referred to as a "DC link capacitor," "DC link capacitor," or "smoothing capacitor." The capacitor 21 has the function of suppressing pulsation 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 21 include an electrolytic capacitor and a film capacitor.

[0015] The pre-charging circuit 13 is provided on the DC link and includes a pre-charging resistor 131 and a pre-charging switch 132.

[0016] The pre-charging resistor 131 suppresses inrush current during pre-charging of the capacitor 21. The pre-charging switch 132 is connected in parallel to the pre-charging resistor 131. Examples of the pre-charging switch 132 include a relay and a semiconductor switching element, but other switch components may also be used. Examples of the semiconductor switching element include an IGBT, an FET, a thyristor, a GTO, and a transistor, but other semiconductor switching elements may also be used.

[0017] The pre-charging switch 132 opens and closes the electrical path between the converter 11 and the capacitor 21 under the control of a pre-charging control unit (not shown). The pre-charging control unit commands the pre-charging switch 132 to open during the pre-charging period, and commands the pre-charging switch 132 to close during the motor driving period, which is a period other than the pre-charging period.

[0018] The pre-charging control unit issues an opening / closing command to the pre-charging switch 132, selectively switching between an open state in which a current path is formed via the pre-charging resistor 131 and a closed state in which a short circuit is formed without passing through the pre-charging resistor 131. When the opening / closing unit 17 is closed under the control of the opening / closing control unit 19, the pre-charging control unit commands the pre-charging switch 132 to open during the pre-charging period, and in response, the pre-charging switch 132 maintains its open state. As a result, during the pre-charging period, the current output from the converter 11 flows into the capacitor 21 via the pre-charging resistor 131, charging the capacitor 21. This pre-charging operation causes the current output from the converter 11 to flow through the pre-charging resistor 131, preventing the occurrence of an inrush current. After the pre-charging operation is completed, the pre-charging control unit commands the pre-charging switch 132 to close, and in response, the pre-charging switch 132 maintains its closed state. During the motor driving period after the completion of the pre-charging operation, the current output from the converter 11 flows toward the capacitor 21 and the inverter 12 through the pre-charging switch 132 in the closed state.

[0019] The motor control unit 20 controls the power conversion operation of the inverter 12 to control the driving of the motor 3 .

[0020] The inverter 12 is connected to the converter 11 via a DC link. The motor control unit 20 controls the on / off of semiconductor switching elements within the inverter 12, causing the inverter 12 to convert DC power from the DC link into AC power and supply this AC power to the motor 3 to drive it. The inverter 12 is composed of semiconductor switching elements and a bridge circuit of diodes connected in antiparallel to the semiconductor switching elements. The inverter 12 is composed of a three-phase bridge circuit if the motor 3 is a three-phase AC motor, and a single-phase bridge circuit if the motor 3 is a single-phase AC motor. In the example shown in FIG. 1 , the motor 3 is a three-phase AC motor, so the inverter 12 is composed of a three-phase bridge circuit. Examples of semiconductor switching elements include FETs, IGBTs, thyristors, GTOs, and transistors, but other semiconductor switching elements may also be used. The power conversion operation of the inverter 12 is controlled, for example, by a PWM switching control method. That is, the inverter 12 receives a drive command (PWM switching command) from the motor control unit 20, converts the DC power in the DC link into AC power and outputs this to the motor 3, or converts the AC power regenerated when the motor 3 decelerates into DC power and returns this to the DC link.

[0021] The motor control unit 20 generates drive commands for controlling the rotational speed, torque, or position of the rotor of the motor 3 based on the rotational speed of the motor 3 (rotational speed feedback), the current flowing through the windings of the motor 3 (current feedback), a rotational speed command, a torque command, a position command, an operation program for the motor 3, and the like. The drive commands generated by the motor control unit 20 are sent to the semiconductor switching elements in the inverter 12. Note that the configuration of the motor control unit 20 defined here is merely an example, and the configuration of the motor control unit 20 may also be defined by including terms such as a position command generation unit, a speed command generation unit, a torque command generation unit, and a switching command generation unit.

[0022] Although not shown here, the power line for supplying power to switching control unit 19 is a separate system from the power line for supplying power from AC power supply 2 to converter 11. In other words, even before power is applied to converter 11, power is supplied to drive switching control unit 19 in preparation for operation when power is applied to converter 11. Furthermore, although not shown here, the power line for supplying power to motor control unit 20 is a separate system from the power line for supplying power from AC power supply 2 to converter 11. In other words, even before power is applied to converter 11, power is supplied to drive motor control unit 20 in preparation for operation when power is applied to inverter 12.

[0023] The input line voltage detection unit 18 measures the effective value of the “input line voltage”, which is the line voltage of the AC voltage input to the converter 11 from the AC power supply 2. Data relating to the effective value of the input line voltage measured by the input line voltage detection unit 18 is sent to the identification unit 15.

[0024] The ground voltage detection unit 14 detects the value of the ground voltage between the DC link and the ground. In the present embodiment, as an example, the ground voltage detection unit 14 detects the value of the ground voltage, which is the potential difference between the positive side potential of the positive side power line 41P of the DC link and the ground potential (earth potential). Note that, as a modification of the present embodiment, the ground voltage detection unit 14 may detect the value of the ground voltage, which is the potential difference between the negative side potential of the negative side power line 41N of the DC link and the ground potential (earth potential). Data related to the value of the ground voltage detected by the ground voltage detection unit 14 is sent to the identification unit 15.

[0025] A voltage-divider circuit 42 is provided for detecting the ground voltage so that a voltage within the input range of the ground voltage detection unit 14 is input. The voltage-divider circuit 42 is connected between the positive potential of the positive power line 41P of the DC link and ground potential. The voltage-divider circuit 42 has a first voltage-divider resistor 421 and a second voltage-divider resistor 422 connected in series. The connection point between the first voltage-divider resistor 421 and the second voltage-divider resistor 422 is connected to the input terminal of the ground voltage detection unit 14. Note that, since a voltage-divider circuit for detecting the ground voltage may already be provided in the motor drive device, such an existing circuit may be used as the voltage-divider circuit 42. This makes it possible to prevent an increase in cost of the motor drive device 1.

[0026] The identification unit 15 identifies the type of wiring of the AC power supply 2 based on the value of the voltage to ground detected by the voltage to ground detection unit 14. The identification unit 15 includes a calculation unit 31, a storage unit 32, a comparison unit 33, and a determination unit 34.

[0027] The calculation unit 31 calculates a threshold value based on the effective value of the input line voltage detected by the input line voltage detection unit 18. The threshold value calculated by the calculation unit 31 is sent to the storage unit 32. The details of the threshold value will be described later.

[0028] The storage unit 32 stores the threshold value calculated by the calculation unit 31 .

[0029] The comparison unit 33 compares the value of the voltage to ground detected by the voltage to ground detection unit 14 with the threshold value stored in the storage unit 32. The comparison result by the comparison unit 33 is sent to the determination unit .

[0030] The determination unit 34 determines the type of wiring of the AC power supply 2 based on the comparison result by the comparison unit 33. The determination result by the determination unit 34 is sent to the notification unit 16 and the switching control unit 19. Details of the determination process by the determination unit 34 will be described later.

[0031] The notification unit 16 notifies an operator of the type of connection of the AC power supply 2 determined by the determination unit 34. There are two types of connection states of the AC power supply 2: delta connection (Δ connection) and Y connection (star connection).

[0032] Examples of the notification unit 16 include a display device, an audio device, and a printer.

[0033] When the notification unit 16 is configured as a display device, it displays, for example, "The AC power supply is delta connected" or "The AC power supply is wye connected." The display device may be a standalone display monitor, a display monitor attached to the motor drive device 1, a display monitor attached to a higher-level control device (not shown) that controls the motor drive device 1, or a display monitor attached to a personal computer or mobile terminal. Alternatively, the notification unit 16 may be configured as a light-emitting device such as an LED or lamp. For example, the light-emitting device may emit light when the AC power supply 2 is delta connected and may not emit light when the AC power supply 2 is wye connected.

[0034] When the notification unit 16 is configured as an audio device, the audio device emits a sound such as a voice, a buzzer, or a chime. The audio device may emit a sound such as "The AC power supply is delta-connected" or "The AC power supply is wye-connected." The audio device may emit a buzzer or chime when the AC power supply 2 is delta-connected, and may not emit a sound when the AC power supply 2 is wye-connected.

[0035] If the notification unit 16 is configured as a printer, the printer prints out on paper or the like, for example, "AC power supply is delta-connected" or "AC power supply is Y-connected."

[0036] Although examples of the notification unit 16 have been described above, they may be implemented by appropriately combining them. In addition, every time a determination result is obtained by the determination unit 34 in the identification unit 15, it may be stored and accumulated in memory, and by creating a database, it may be useful for maintenance work, design change work, etc.

[0037] The worker can quickly and reliably grasp the type of wiring of the AC power supply 2 based on the determination result by the determining unit 34 notified by the notifying unit 16 .

[0038] Furthermore, the determination result by the determination unit 34 may be sent to the switching control unit 19. When the determination unit 34 in the identification unit 15 determines that the AC power supply 2 is configured with a delta connection, the switching control unit 19 may control the switching unit 17 to perform an opening operation to interrupt the electric path between the AC power supply 2 and the converter 11.

[0039] The motor drive device 1 includes at least one processor, which is an arithmetic processing device. Examples of the arithmetic processing device include an IC, an LSI, a CPU, an MPU, and a DSP. The arithmetic processing device includes a ground voltage detection unit 14, an identification unit 15, an input line voltage detection unit 18, a switching control unit 19, a motor control unit 20, and other processing units. Each of these units in the arithmetic processing device is a functional module implemented by a program executed on the processor. For example, if the ground voltage detection unit 14, the identification unit 15, the input line voltage detection unit 18, the switching control unit 19, the motor control unit 20, and other processing units are implemented in a program format, 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 ground voltage detection unit 14, the identification unit 15, the input line voltage detection unit 18, the switching control unit 19, the motor control unit 20, and other processing units may be provided in the form of a computer-readable recording medium, such as a semiconductor memory, a magnetic recording medium, or an optical recording medium. Alternatively, the line-to-ground voltage detection unit 14, the identification unit 15, the input line voltage detection unit 18, the switching control unit 19, the motor control unit 20 and other processing units may be realized as a semiconductor integrated circuit in which a program that realizes the function of each unit is written.

[0040] The motor drive device 1 also includes at least one memory serving as a storage device. The memory includes the ground voltage detection unit 14, the identification unit 15, the input line voltage detection unit 18, the switching control unit 19, the motor control unit 20, and various storage units within other processing units. Examples of the memory include electrically erasable and recordable nonvolatile memory such as EEPROM (registered trademark), or high-speed read / write random access memory such as DRAM or SRAM. The storage unit may also be configured as a hard disk drive (HDD) or solid state drive (SSD). The memory stores programs for operating the ground voltage detection unit 14, the identification unit 15, the input line voltage detection unit 18, the switching control unit 19, the motor control unit 20, and other processing units. The memory also stores threshold values, data relating to the value of the ground voltage detected by the ground voltage detection unit 14, data relating to the effective value of the input line voltage detected by the input line voltage detection unit, comparison results by the comparison unit 33, and determination results by the determination unit 34. The memory also stores various programs and data relating to the motor drive device 1.

[0041] <Relationship between voltage to ground and input line voltage> Even if the magnitude of the effective value of the input line voltage of the AC power supply 2 is the same, if the type of wiring of the AC power supply 2 is different, the magnitude and waveform of the voltage to ground of the DC link in the motor drive device 1 to which the AC power supply 2 is connected will also be different.

[0042] 2A is a diagram showing a motor drive device connected to an AC power supply configured with a Y connection. In Fig. 2A, the inverter 12, pre-charging circuit 13, ground voltage detection unit 14, identification unit 15, notification unit 16, switching unit 17, input line voltage detection unit 18, switching control unit 19, motor control unit 20, and capacitor 21 within the motor drive device 1 are not shown.

[0043] The effective value of the input line voltage of AC power supply 2 configured with Y connection is V in [V], the voltage V to ground in the positive power line 41P of the DC link gy [V] can be expressed as in Equation 1.

[0044]

[0045] 2B is a waveform diagram illustrating the voltage to ground, the input line voltage, and the DC link voltage in a motor drive device connected to an AC power supply configured with a Y connection. In FIG. 2B, the thick solid line represents the voltage to ground, the thick dashed line represents the input line voltage, and the thick dotted line represents the DC link voltage.

[0046] 3A is a diagram showing a motor drive device connected to a delta-connected AC power supply, in which the inverter 12, pre-charging circuit 13, ground voltage detection unit 14, identification unit 15, notification unit 16, switching unit 17, input line voltage detection unit 18, switching control unit 19, motor control unit 20, and capacitor 21 within the motor drive device 1 are not shown.

[0047] The effective value of the input line voltage of the delta-connected AC power supply 2 is V in [V], the voltage V to ground in the positive power line 41P of the DC link gd [V] can be expressed as in Equation 2.

[0048]

[0049] 3B is a waveform diagram illustrating the voltage to ground, the input line voltage, and the DC link voltage in a motor drive device connected to a delta-connected AC power supply, in which the thick solid line represents the voltage to ground, the thick dashed-dotted line represents the input line voltage, and the thick dotted line represents the DC link voltage.

[0050] As shown in Equation 1 and Equation 2, even if the effective values ​​of the input line voltages of the AC power supply 2 are the same, when the AC power supply 2 is configured in a delta connection, the voltage V gd is the voltage V to ground when the AC power supply 2 is configured as a Y connection. gy 3A and 3B, the waveform of the voltage to ground when the AC power supply 2 is configured in a delta connection is different from the waveform of the voltage to ground when the AC power supply 2 is configured in a Y connection.

[0051] For example, the effective value V of the input line voltage of an AC power supply 2 configured in a Y connection inis 480V, the voltage V gy On the other hand, the effective value V of the input line voltage of the delta-connected AC power supply 2 is in is 480V, the voltage V gd For example, if the motor drive device 1 is designed for insulation such that the voltage to ground is 300 V or less, the effective value V of the input line voltage is in Even if an AC power supply 2 configured with a Y connection of 480 V is selected and connected to the motor drive device 1, the motor drive device 1 will not be destroyed. in If an AC power supply 2 configured with a delta connection of 480 V is selected and connected to the motor drive device 1, there is a risk that the motor drive device 1 may be destroyed.

[0052] 2A , 2B , 3A , and 3B , even if the magnitude of the effective value of the input line voltage of the AC power supply 2 is the same, if the type of wiring of the AC power supply 2 is different, the magnitude and waveform of the DC link voltage to ground will be different. This tendency becomes more pronounced immediately after the start of the pre-charging operation in the motor drive device 1 and after the pre-charging operation is completed. Here, the behavior of the voltage to ground associated with the pre-charging operation will be illustrated using the simulation waveforms shown in FIGS. 4 and 5 .

[0053] Fig. 4 is a simulation waveform diagram illustrating the ground voltage and DC link voltage in a motor drive device connected to a Y-connected AC power supply. Fig. 5 is a simulation waveform diagram illustrating the ground voltage and DC link voltage in a motor drive device connected to a delta-connected AC power supply. In Fig. 4 and Fig. 5, the thick solid line indicates the ground voltage, and the thick dashed line indicates the DC link voltage.

[0054] In the simulation, the effective value of the input line voltage of the AC power supply 2 configured with a Y connection and the effective value of the input line voltage of the AC power supply 2 configured with a delta connection were both set to 480 V. Furthermore, in the initial state from time 0.0 [second] to time 0.5 [second], the DC link voltage (i.e., the voltage of capacitor 21) was set to 0 V, and the pre-charging operation was set to start at time 0.5 [second] and to end at time 2.0 [second].

[0055] Immediately after the start of the pre-charging operation at time 0.5 seconds, the voltage to ground in motor drive device 1 connected to AC power supply 2 configured with delta connection shown in FIG. 5 is significantly lower in value and fluctuates by a larger range than the voltage to ground in motor drive device 1 connected to AC power supply 2 configured with Y connection shown in FIG. 4 .

[0056] During the pre-charging period from time 0.5 seconds to time 2.0 seconds, the voltage to ground in motor drive device 1 connected to AC power supply 2 configured with delta connection shown in FIG. 5 fluctuates more widely than the voltage to ground in motor drive device 1 connected to AC power supply 2 configured with Y connection shown in FIG. 4.

[0057] Even after the pre-charging operation is completed at time 2.0 seconds, the voltage to ground in the motor drive device 1 connected to the delta-connected AC power supply 2 shown in Fig. 5 fluctuates more widely than the voltage to ground in the motor drive device 1 connected to the Y-connected AC power supply 2 shown in Fig. 4. The maximum value of the voltage to ground in the motor drive device 1 connected to the delta-connected AC power supply 2 shown in Fig. 5 is greater than the maximum value of the voltage to ground in the motor drive device 1 connected to the Y-connected AC power supply 2 shown in Fig. 4. The minimum value of the voltage to ground in the motor drive device 1 connected to the delta-connected AC power supply 2 shown in Fig. 5 is 0 V, but the minimum value of the voltage to ground in the motor drive device 1 connected to the Y-connected AC power supply 2 shown in Fig. 4 is approximately 80 V.

[0058] Thus, even if the input line voltage of the AC power supply 2 is the same magnitude, if the wiring type of the AC power supply 2 is different, there will be significant differences in the magnitude and waveform of the DC link to ground voltage immediately after the start of or after the completion of the pre-charging operation in the motor drive device 1. Therefore, in the motor drive device 1 according to an embodiment of the present disclosure, the wiring type of the AC power supply 2 is identified based on the magnitude of the DC link to ground voltage immediately after the start of or after the completion of the pre-charging operation.

[0059] 2A and 2B , the voltage to ground in a motor drive device 1 connected to an AC power supply 2 configured in a Y connection can be calculated based on the effective value of the input line voltage according to Equation 1. Also, as described with reference to FIGS. 3A and 3B , the voltage to ground in a motor drive device 1 connected to an AC power supply 2 configured in a delta connection can be calculated based on the effective value of the input line voltage according to Equation 2. Also, as described with reference to FIGS. 4 and 5 , the magnitude of the voltage to ground immediately after the start of a pre-charging operation in the motor drive device 1 and after the completion of the pre-charging operation differs depending on whether the AC power supply 2 is configured in a Y connection or a delta connection, even if the input line voltage of the AC power supply 2 is the same. Therefore, in an embodiment of the present disclosure, a threshold for distinguishing whether the connection state of the AC power supply 2 is a Y connection or a delta connection is set using the effective value of the input line voltage to the converter 11 measured by the input line voltage detection unit 18. The voltage to ground calculated based on the effective value of the input line voltage measured by the input line voltage detection unit 18 is used in the process of setting the threshold value, and is different from the voltage to ground detected by the voltage to ground detection unit 14 in the comparison process by the comparison unit 33. Below, several examples of setting the threshold value are listed.

[0060] 6 is a waveform diagram illustrating a first threshold value used in the discrimination process in a motor drive device according to an embodiment of the present disclosure. In FIG. 6, a thick solid line indicates the voltage to ground when it is assumed that the AC power supply 2 is configured as a Y connection, a thick dashed line indicates the voltage to ground when it is assumed that the AC power supply 2 is configured as a delta connection, and the shaded area indicates the range in which the threshold value can be set. The effective value V of the input line voltage of the AC power supply 2 when it is configured as a Y connection is in The effective value V of the input line voltage of AC power supply 2 assumed to be configured with a delta connection in is the same size as

[0061] The first threshold V th1 is compared with the value of the voltage to ground detected by the voltage to ground detection unit 14 immediately after the start of the pre-charging operation by the pre-charging circuit 13. Here, "immediately after the start of the pre-charging operation" refers to the point in time when, for example, several percent of the pre-charging period has elapsed from the start of the pre-charging operation.

[0062] As shown in FIG. 6, the first threshold V th1 is the effective value V of the input line voltage to the converter 11 when it is assumed that the AC power supply 2 is configured as a Y connection. in The maximum value of the voltage to ground calculated based on gy1max is higher than the effective value V of the input line voltage to the converter 11 when it is assumed that the AC power supply 2 is configured in a delta connection. in The maximum value of the voltage to ground calculated based on gd1max is set to a lower value.

[0063] The maximum value of the voltage to ground when the AC power supply 2 is assumed to be configured as a Y connection is V. gy1max is the effective value V of the input line voltage to the converter 11 measured by the input line voltage detector 18 according to Equation 3 when it is assumed that the AC power supply 2 is configured as a Y connection. in It can be calculated based on:

[0064]

[0065] The maximum value of the voltage to ground when it is assumed that the AC power supply 2 is configured in a delta connection is V.gd1max is 0.

[0066] The calculation unit 31 calculates the effective value V of the input line voltage measured by the input line voltage detection unit 18. in The maximum value of the voltage to ground when calculated according to Equation 3, assuming that the AC power supply 2 is configured as a Y connection, is V gy1max is higher, and the maximum value of the voltage to ground when it is assumed that the AC power supply 2 is configured in a delta connection is V gd1max A first threshold V that falls within a range lower than (=0) th1 The storage unit 32 stores the first threshold value V calculated by the calculation unit 31. th1 The comparison unit 33 compares the value of the voltage to ground detected by the voltage to ground detection unit 14 immediately after the pre-charging operation by the pre-charging circuit 13 is started with the first threshold value V th1 The determination unit 34 determines whether the value of the voltage to ground detected by the voltage to ground detection unit 14 immediately after the pre-charging operation by the pre-charging circuit 13 is equal to or greater than the first threshold value V th1 If the comparison result by the comparison unit 33, the value of the voltage to ground detected by the voltage to ground detection unit 14 immediately after the pre-charging operation by the pre-charging circuit 13 is started, is greater than the first threshold value V stored in the memory unit 32, the determination unit 34 determines that the AC power supply 2 is configured with a delta connection. th1 If the following occurs, it is determined that the AC power supply 2 is configured as a Y connection.

[0067] 7 is a waveform diagram illustrating a second threshold value used in the discrimination process in a motor drive device according to an embodiment of the present disclosure. In FIG. 7, the thick solid line indicates the voltage to ground when it is assumed that the AC power supply 2 is configured as a Y connection, the thick dashed line indicates the voltage to ground when it is assumed that the AC power supply 2 is configured as a delta connection, and the shaded area indicates the range in which the threshold value can be set. The effective value V of the input line voltage of the AC power supply 2 when it is configured as a Y connection is in The effective value V of the input line voltage of AC power supply 2 assumed to be configured with a delta connection in is the same size as

[0068] The second threshold V th2 is compared with the value of the voltage to ground detected by the voltage to ground detection unit 14 immediately after the start of the pre-charging operation by the pre-charging circuit 13. Here, "immediately after the start of the pre-charging operation" refers to the point in time when, for example, several percent of the pre-charging period has elapsed from the start of the pre-charging operation.

[0069] As shown in FIG. 7, the second threshold V th2 is the effective value V of the input line voltage to the converter 11 when it is assumed that the AC power supply 2 is configured as a Y connection. in The minimum value of the voltage to ground V calculated based on gy2min and the effective value V of the input line voltage to the converter 11 when it is assumed that the AC power supply 2 is configured in a delta connection. in The minimum value of the voltage to ground V calculated based on gd2min is set to a higher value.

[0070] The minimum value V of the voltage to ground when it is assumed that the AC power supply 2 is configured as a Y connection gy2min is the effective value V of the input line voltage to the converter 11 measured by the input line voltage detector 18 according to Equation 4 assuming that the AC power supply 2 is configured as a Y connection. in It can be calculated based on:

[0071]

[0072] The minimum value V of the voltage to ground when it is assumed that the AC power supply 2 is configured in a delta connection gd2min is the effective value V of the input line voltage to the converter 11 measured by the input line voltage detector 18 according to Equation 5 assuming that the AC power supply 2 is configured in a delta connection. in It can be calculated based on:

[0073]

[0074] The calculation unit 31 calculates the effective value V of the input line voltage measured by the input line voltage detection unit 18. in The minimum value V of the voltage to ground when calculated according to Equation 4, assuming that the AC power supply 2 is configured as a Y connection, is gy2minand the minimum value V of the voltage to ground calculated according to Equation 5 on the assumption that the AC power supply 2 is configured in a delta connection. gd2min A second threshold V that falls within the higher range th2 The storage unit 32 stores the second threshold value V calculated by the calculation unit 31. th2 The comparison unit 33 compares the value of the voltage to ground detected by the voltage to ground detection unit 14 immediately after the pre-charging operation by the pre-charging circuit 13 is started with the second threshold value V th2 The determination unit 34 compares the comparison result by the comparison unit 33 with the second threshold value V th2 , the determination unit 34 determines that the AC power supply 2 is configured with a delta connection when the comparison result by the comparison unit 33, the value of the voltage to ground detected by the voltage to ground detection unit 14 immediately after the pre-charging operation by the pre-charging circuit 13 is equal to or lower than the second threshold value V th2 If this is the case, it is determined that the AC power supply 2 is configured as a Y-connection.

[0075] 8 is a waveform diagram illustrating a third threshold value used in the discrimination process in the motor drive device according to an embodiment of the present disclosure. In FIG. 8, the thick solid line indicates the voltage to ground when it is assumed that the AC power supply 2 is configured as a Y connection, the thick dashed line indicates the voltage to ground when it is assumed that the AC power supply 2 is configured as a delta connection, and the shaded area indicates the range in which the threshold value can be set. The effective value V of the input line voltage of the AC power supply 2 when it is configured as a Y connection is in The effective value V of the input line voltage of AC power supply 2 assumed to be configured with a delta connection in is the same size as

[0076] The third threshold V th3 is compared with the value of the voltage to ground detected by the voltage to ground detection unit 14 after the pre-charging operation by the pre-charging circuit 13 is completed.

[0077] As shown in FIG. 8, the third threshold V th3is the effective value V of the input line voltage to the converter 11 when it is assumed that the AC power supply 2 is configured as a Y connection. in The maximum value of the voltage to ground calculated based on gy3max is higher than the effective value V of the input line voltage to the converter 11 when it is assumed that the AC power supply 2 is configured in a delta connection. in The maximum value of the voltage to ground calculated based on gd3max is set to a lower value.

[0078] The maximum value of the voltage to ground when the AC power supply 2 is assumed to be configured as a Y connection is V. gy3max is the effective value V of the input line voltage to the converter 11 measured by the input line voltage detector 18 according to Equation 6 when it is assumed that the AC power supply 2 is configured as a Y connection. in It can be calculated based on:

[0079]

[0080] The maximum value of the voltage to ground when it is assumed that the AC power supply 2 is configured in a delta connection is V. gd3max is the effective value V of the input line voltage to the converter 11 measured by the input line voltage detector 18 according to Equation 7 assuming that the AC power supply 2 is configured in a delta connection. in It can be calculated based on:

[0081]

[0082] The calculation unit 31 calculates the effective value V of the input line voltage measured by the input line voltage detection unit 18. in The maximum value of the voltage to ground when calculated according to Equation 6, assuming that the AC power supply 2 is configured as a Y connection, is V gy3max The maximum value of the voltage to ground V when calculated according to Equation 7 on the assumption that the AC power supply 2 is configured in a delta connection is higher than gd3max A third threshold V th3 The storage unit 32 stores the third threshold value V calculated by the calculation unit 31. th3The comparison unit 33 compares the value of the voltage to ground detected by the voltage to ground detection unit 14 immediately after the pre-charging operation by the pre-charging circuit 13 is started with the third threshold value V th3 The determination unit 34 compares the comparison result by the comparison unit 33, the value of the ground voltage detected by the ground voltage detection unit 14 after the pre-charging operation by the pre-charging circuit 13 is completed, with the third threshold value V th3 If the comparison result by the comparison unit 33, the value of the voltage to ground detected by the voltage to ground detection unit 14 after the pre-charging operation by the pre-charging circuit 13 is completed, is greater than or equal to the third threshold value V stored in the storage unit 32, the determination unit 34 determines that the AC power supply 2 is configured as a delta connection. th3 If the following occurs, it is determined that the AC power supply 2 is configured as a Y connection.

[0083] 9 is a waveform diagram illustrating a fourth threshold value used in the discrimination process in a motor drive device according to an embodiment of the present disclosure. In FIG. 9, the thick solid line indicates the voltage to ground when it is assumed that the AC power supply 2 is configured as a Y connection, the thick dashed line indicates the voltage to ground when it is assumed that the AC power supply 2 is configured as a delta connection, and the shaded area indicates the range in which the threshold value can be set. The effective value V of the input line voltage of the AC power supply 2 when it is configured as a Y connection is in The effective value V of the input line voltage of AC power supply 2 assumed to be configured with a delta connection in is the same size as

[0084] The fourth threshold V th4 is compared with the value of the voltage to ground detected by the voltage to ground detection unit 14 after the pre-charging operation by the pre-charging circuit 13 is completed.

[0085] As shown in FIG. 9, the fourth threshold V th4 is the effective value V of the input line voltage to the converter 11 when it is assumed that the AC power supply 2 is configured as a Y connection. in The minimum value of the voltage to ground V calculated based on gy4min and the effective value V of the input line voltage to the converter 11 when it is assumed that the AC power supply 2 is configured in a delta connection.in The minimum value of the voltage to ground V calculated based on gd4min is set to a higher value.

[0086] The minimum value V of the voltage to ground when it is assumed that the AC power supply 2 is configured as a Y connection gy4min is the effective value V of the input line voltage to the converter 11 measured by the input line voltage detector 18 according to Equation 8 when it is assumed that the AC power supply 2 is configured as a Y connection. in It can be calculated based on:

[0087]

[0088] The minimum value V of the voltage to ground when it is assumed that the AC power supply 2 is configured in a delta connection gd4min is 0.

[0089] The calculation unit 31 calculates the effective value V of the input line voltage measured by the input line voltage detection unit 18. in The minimum value V of the voltage to ground when calculated according to Equation 8, assuming that the AC power supply 2 is configured as a Y connection, is gy4min and the minimum value V of the voltage to ground when it is assumed that the AC power supply 2 is configured in a delta connection. gd4min (=0) and a fourth threshold V th4 The storage unit 32 stores the fourth threshold value V calculated by the calculation unit 31. th4 The comparison unit 33 compares the value of the voltage to ground detected by the voltage to ground detection unit 14 after the pre-charging operation by the pre-charging circuit 13 is completed with the fourth threshold value V th4 The determination unit 34 determines whether the value of the voltage to ground detected by the voltage to ground detection unit 14 immediately after the pre-charging operation by the pre-charging circuit 13 is equal to or greater than the fourth threshold value V th4 , the determination unit 34 determines that the AC power supply 2 is configured with a delta connection when the comparison result by the comparison unit 33, the value of the ground voltage detected by the ground voltage detection unit 14 immediately after the pre-charging operation by the pre-charging circuit 13 is equal to or lower than the fourth threshold value V th4If this is the case, it is determined that the AC power supply 2 is configured as a Y-connection.

[0090] The maximum and minimum values ​​of the voltage to ground used in the threshold setting process may be specific values ​​that take into account the relationship between the motor drive device 1 and the AC power supply 2.

[0091] <Operation of Motor Drive Device According to Embodiment of Present Disclosure> FIG. 10 is a flowchart showing the operation of the discrimination process using the first threshold value in the motor drive device according to one embodiment of the present disclosure.

[0092] In step S101, the input line voltage detection unit 18 detects the effective value V of the input line voltage to the converter 11. in Measure.

[0093] In step S102, the calculation unit 31 calculates the effective value V of the input line voltage to the converter 11 measured by the input line voltage detection unit 18. in The first threshold V th1 The storage unit 32 stores the first threshold value V calculated by the calculation unit 31. th1 This stores the first threshold value V th1 is set.

[0094] In step S103, immediately after the pre-charging operation by the pre-charging circuit 13 is started, the ground voltage detection unit 14 detects the value of the ground voltage, which is the potential difference between the positive side potential on the positive side power line 41P of the DC link and the ground potential.

[0095] In step S104, the value of the voltage to ground detected by the voltage to ground detection unit 14 is compared with the first threshold value V th1 Determine whether or not the value of

[0096] In step S104, the value of the voltage to ground is equal to or exceeds the first threshold value V th1 If it is determined that the difference may exceed the predetermined value, the determining unit 34 determines in step S105 that the AC power supply 2 is configured as a delta connection.

[0097] In step S104, the value of the voltage to ground is equal to or exceeds the first threshold value V th1If it is not determined that the voltage Vcc is greater than 1 V, the determining unit 34 determines in step S106 that the AC power supply 2 is configured as a Y-connection.

[0098] FIG. 11 is a flowchart showing the operation of the discrimination process using the second threshold value in the motor drive device according to an embodiment of the present disclosure.

[0099] In step S201, the input line voltage detection unit 18 detects the effective value V of the input line voltage to the converter 11. in Measure.

[0100] In step S202, the calculation unit 31 calculates the effective value V of the input line voltage measured by the input line voltage detection unit 18. in The second threshold V th2 The storage unit 32 stores the second threshold value V calculated by the calculation unit 31. th2 This stores the second threshold V th2 is set.

[0101] In step S203, immediately after the pre-charging operation by the pre-charging circuit 13 is started, the ground voltage detection unit 14 detects the value of the ground voltage, which is the potential difference between the positive side potential on the positive side power line 41P of the DC link and the ground potential.

[0102] In step S204, the value of the voltage to ground detected by the voltage to ground detection unit 14 is compared with the second threshold value V th2 Determine whether or not the value of

[0103] In step S204, the value of the voltage to ground is equal to or exceeds the second threshold value V th2 If it is determined that the voltage may fall below 0 V, the determining unit 34 determines in step S205 that the AC power supply 2 is configured in a delta connection.

[0104] In step S204, the value of the voltage to ground is equal to or exceeds the second threshold value V th2 If it is not determined that the voltage Vcc can fall below 1 V, the determining unit 34 determines in step S206 that the AC power supply 2 is configured as a Y-connection.

[0105] FIG. 12 is a flowchart showing the operation of the discrimination process using the third threshold value in the motor drive device according to an embodiment of the present disclosure.

[0106] In step S301, the input line voltage detection unit 18 detects the effective value V of the input line voltage to the converter 11. in Measure.

[0107] In step S302, the calculation unit 31 calculates the effective value V of the input line voltage to the converter 11 measured by the input line voltage detection unit 18. in The third threshold V th3 The storage unit 32 stores the third threshold value V calculated by the calculation unit 31. th3 This stores the third threshold value V th3 is set.

[0108] In step S303, after the pre-charging operation by the pre-charging circuit 13 is completed, the ground voltage detection unit 14 detects the value of the ground voltage, which is the potential difference between the positive side potential on the positive side power line 41P of the DC link and the ground potential.

[0109] In step S304, the value of the voltage to ground detected by the voltage to ground detection unit 14 is compared with the third threshold value V th3 Determine whether or not the value of

[0110] In step S304, the value of the voltage to ground is equal to or exceeds the third threshold value V th3 If it is determined that the difference may exceed the predetermined value, the determining unit 34 determines in step S305 that the AC power supply 2 is configured as a delta connection.

[0111] In step S304, the value of the voltage to ground is equal to or exceeds the third threshold value V th3 If it is not determined that the AC power supply 2 is likely to exceed the predetermined value, the determination unit 34 determines in step S306 that the AC power supply 2 is configured as a Y-connection.

[0112] FIG. 13 is a flowchart showing the operation of the discrimination process using the fourth threshold value in the motor drive device according to an embodiment of the present disclosure.

[0113] In step S401, the input line voltage detection unit 18 detects the effective value V of the input line voltage to the converter 11. in Measure.

[0114] In step S402, the calculation unit 31 calculates the effective value V of the input line voltage to the converter 11 measured by the input line voltage detection unit 18. in The fourth threshold V th4 The storage unit 32 stores the fourth threshold value V calculated by the calculation unit 31. th4 This stores the fourth threshold value V th4 is set.

[0115] In step S403, after the pre-charging operation by the pre-charging circuit 13 is completed, the ground voltage detection unit 14 detects the value of the ground voltage, which is the potential difference between the positive side potential on the positive side power line 41P of the DC link and the ground potential.

[0116] In step S404, the value of the voltage to ground detected by the voltage to ground detection unit 14 is compared with the fourth threshold value V th4 Determine whether or not the value of

[0117] In step S404, the value of the voltage to ground is equal to or exceeds the fourth threshold value V th4 If it is determined that the voltage Vcc may fall below 0 V, the determining unit 34 determines in step S405 that the AC power supply 2 is configured in a delta connection.

[0118] In step S404, the value of the voltage to ground is equal to or exceeds the fourth threshold value V th4 If it is not determined that the voltage Vcc can fall below 1 V, the determining unit 34 determines in step S406 that the AC power supply 2 is configured as a Y-connection.

[0119] 10 to 13, it is possible to determine the wiring state of the AC power supply 2. As a modification of this, it is also possible to perform two or more of the four identification processes described with reference to Fig. 10 to 13, and finally determine the wiring state of the AC power supply 2 based on a majority vote of the determination results obtained by each identification process.

[0120] As described above, according to the embodiment of the present disclosure, it is possible to accurately identify the type of wiring of the AC power supply connected to the motor drive device. For example, if the motor drive device is designed for insulation such that the voltage to ground should be 300 V or less, the effective value V of the input line voltage can be accurately identified. in If an AC power supply with a 480V Y-connection is selected and connected to the motor drive device, the motor drive device will not be destroyed. in If a 480V delta-connected AC power supply is selected and connected to the motor drive device, there is a risk of damaging the motor drive device. The motor drive device according to the embodiment of the present disclosure can accurately identify the type of AC power supply connection, thereby eliminating this risk.

[0121] 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.

[0122] <Supplementary Notes> The following supplementary notes are further disclosed regarding the above-described embodiment and modifications.

[0123] (Supplementary Note 1) A motor drive device 1 comprising: an inverter 12 that drives a motor 3; a converter 11 that converts AC power supplied from an AC power source 2 into DC power and supplies the DC power to the inverter 12 via a DC link; a pre-charging circuit 13 that has a pre-charging resistor 131 that suppresses inrush current during a pre-charging period for a capacitor 21 provided in the DC link and a pre-charging switch 132 connected in parallel to the pre-charging resistor 131, the pre-charging circuit 13 performing a pre-charging operation to charge the capacitor 21 with current supplied via the pre-charging resistor 131 while the pre-charging switch 132 is open, and completing the pre-charging operation of the capacitor 21 when the pre-charging switch 132 is switched from open to closed; a ground voltage detection unit 14 that detects a value of a ground voltage between the DC link and ground; and an identification unit 15 that identifies a type of wiring of the AC power source 2 based on the value of the ground voltage detected by the ground voltage detection unit 14. (Supplementary Note 2) The motor drive device 1 according to Supplementary Note 1, wherein the ground voltage detection unit 14 detects a value of the ground voltage, which is a potential difference between a positive potential of the DC link and a ground potential. (Supplementary Note 3) The motor drive device 1 according to Supplementary Note 2, wherein the identification unit 15 identifies a type of connection of the AC power supply 2 based on a comparison result between the value of the ground voltage detected by the ground voltage detection unit 14 and a predetermined threshold. (Supplementary Note 4) The motor drive device 1 according to Supplementary Note 3, wherein the threshold is set to a value higher than a maximum value of the ground voltage calculated based on the input line voltage to the converter 11 when it is assumed that the AC power supply 2 is configured as a Y connection and lower than a maximum value of the ground voltage calculated based on the input line voltage to the converter 11 when it is assumed that the AC power supply 2 is configured as a delta connection, and the identification unit 15 determines that the AC power supply 2 is configured as a delta connection if the value of the ground voltage detected by the ground voltage detection unit 14 sometimes exceeds the threshold immediately after the start of a pre-charging operation by the pre-charging circuit 13.(Supplementary Note 5) The threshold value is set to a value lower than the minimum value of the ground voltage calculated based on the input line voltage to the converter 11 when it is assumed that the AC power supply 2 is configured with a Y connection and higher than the minimum value of the ground voltage calculated based on the input line voltage to the converter 11 when it is assumed that the AC power supply 2 is configured with a delta connection, and the identification unit 15 determines that the AC power supply 2 is configured with a delta connection when the value of the ground voltage detected by the ground voltage detection unit 14 immediately after the pre-charging operation by the pre-charging circuit 13 is started is lower than the threshold value. (Supplementary Note 5) The motor drive device 1 described in Supplementary Note 3 (Supplementary Note 6) The motor drive device 1 according to Supplementary Note 3, wherein the threshold value is set to a value higher than the maximum value of the ground voltage calculated based on the input line voltage to the converter 11 when it is assumed that the AC power supply 2 is configured with a Y connection and lower than the maximum value of the ground voltage calculated based on the input line voltage to the converter 11 when it is assumed that the AC power supply 2 is configured with a delta connection, and the identification unit 15 determines that the AC power supply 2 is configured with a delta connection when the value of the ground voltage detected by the ground voltage detection unit 14 after the pre-charging operation by the pre-charging circuit 13 is completed sometimes exceeds the threshold value. (Supplementary Note 7) The motor drive device 1 according to Supplementary Note 3, wherein the threshold value is set to a value lower than the minimum value of the ground voltage calculated based on the input line voltage to the converter 11 when it is assumed that the AC power supply 2 is configured as a Y connection and higher than the minimum value of the ground voltage calculated based on the input line voltage to the converter 11 when it is assumed that the AC power supply 2 is configured as a delta connection, and the identification unit 15 determines that the AC power supply 2 is configured as a delta connection if the value of the ground voltage detected by the ground voltage detection unit 14 after the pre-charging operation by the pre-charging circuit 13 has been completed falls below the threshold. (Supplementary Note 8) The motor drive device 1 according to any one of Supplementary Notes 1 to 7, further comprising a notification unit 16 that notifies that the identification unit 15 has determined that the AC power supply 2 is configured as a delta connection. (Appendix 9) The motor drive device 1 according to any one of Appendices 1 to 7, further comprising a switching unit 17 that cuts off an electrical path between the AC power supply 2 and the converter 11 when the identification unit 15 determines that the AC power supply 2 is configured in a delta connection.

[0124] REFERENCE SIGNS LIST 1 Motor drive device 2 AC power supply 3 Motor 11 Converter 12 Inverter 13 Pre-charging circuit 14 Ground voltage detection unit 15 Identification unit 16 Notification unit 17 Switching unit 18 Input line voltage detection unit 19 Switching control unit 20 Motor control unit 21 Capacitor 31 Calculation unit 32 Storage unit 33 Comparison unit 34 Determination unit 41N Negative side power line 41P Positive side power line 42 Voltage dividing circuit 131 Pre-charging resistor 132 Pre-charging switch 421 First voltage dividing resistor 422 Second voltage dividing resistor

Claims

1. A motor drive device comprising: an inverter for driving a motor; a converter for converting AC power supplied from an AC power source into DC power and supplying the DC power to the inverter via a DC link; a pre-charging circuit having a pre-charging resistor for suppressing inrush current during a period of pre-charging a capacitor provided in the DC link, and a pre-charging switch connected in parallel to the pre-charging resistor, the pre-charging circuit performing a pre-charging operation to charge the capacitor with current supplied via the pre-charging resistor while the pre-charging switch is open, and completing the pre-charging operation of the capacitor when the pre-charging switch is switched from open to closed; a ground voltage detection unit for detecting a value of a ground voltage between the DC link and ground; and an identification unit for identifying the type of wiring of the AC power source based on the value of the ground voltage detected by the ground voltage detection unit.

2. The motor drive device according to claim 1, wherein the ground voltage detection unit detects a value of the ground voltage which is a potential difference between a positive side potential of the DC link and a ground potential.

3. The motor drive device according to claim 2, wherein the identification unit identifies the type of wiring of the AC power supply based on a comparison result between the value of the voltage to ground detected by the voltage to ground detection unit and a predefined threshold value.

4. The motor drive device of claim 3, wherein the threshold value is set to a value higher than a maximum value of a ground voltage calculated based on an input line voltage to the converter when it is assumed that the AC power supply is configured with a Y connection and lower than a maximum value of a ground voltage calculated based on an input line voltage to the converter when it is assumed that the AC power supply is configured with a delta connection, and the identification unit determines that the AC power supply is configured with a delta connection if the value of the ground voltage detected by the ground voltage detection unit immediately after the start of a pre-charging operation by the pre-charging circuit exceeds the threshold value.

5. The motor drive device according to claim 3, wherein the threshold value is set to a value lower than a minimum value of the ground voltage calculated based on the input line voltage to the converter when it is assumed that the AC power supply is configured with a Y connection and higher than a minimum value of the ground voltage calculated based on the input line voltage to the converter when it is assumed that the AC power supply is configured with a delta connection, and the identification unit determines that the AC power supply is configured with a delta connection if the value of the ground voltage detected by the ground voltage detection unit immediately after the start of a pre-charging operation by the pre-charging circuit falls below the threshold value.

6. The motor drive device according to claim 3, wherein the threshold value is set to a value higher than a maximum value of a line-to-ground voltage calculated based on an input line voltage to the converter when it is assumed that the AC power supply is configured with a Y connection and lower than a maximum value of a line-to-ground voltage calculated based on an input line voltage to the converter when it is assumed that the AC power supply is configured with a delta connection, and the identification unit determines that the AC power supply is configured with a delta connection if the value of the ground voltage detected by the ground voltage detection unit after completion of a pre-charging operation by the pre-charging circuit sometimes exceeds the threshold value.

7. The motor drive device according to claim 3, wherein the threshold value is set to a value lower than a minimum value of a line-to-ground voltage calculated based on an input line voltage to the converter when it is assumed that the AC power supply is configured with a Y connection and higher than a minimum value of a line-to-ground voltage calculated based on an input line voltage to the converter when it is assumed that the AC power supply is configured with a delta connection, and the identification unit determines that the AC power supply is configured with a delta connection if the value of the ground voltage detected by the ground voltage detection unit falls below the threshold value after completion of a pre-charging operation by the pre-charging circuit.

8. The motor drive device according to any one of claims 1 to 7, further comprising a notification section that notifies that the identification section has determined that the AC power supply is configured with a delta connection.

9. A motor drive device according to any one of claims 1 to 7, further comprising an opening / closing unit that cuts off an electrical path between the AC power supply and the converter when the identification unit determines that the AC power supply is configured with a delta connection.

Images