Motor drive device and motor winding diagnosis method

Abstract

This motor drive device comprises an inverter unit that applies voltage to windings between each phase of a three-phase AC motor, and a command unit that generates commands to control the voltage applied to the windings between each phase by the inverter unit, where the inverter unit applies an impulse voltage for diagnosing the state of the windings of the motor to the windings between each phase according to the command of the command unit.

Description

Motor drive device and motor winding diagnosis method

[0001] The present disclosure relates to a motor drive device and a motor winding diagnosis method.

[0002] When a motor is used for many years, it becomes prone to malfunctions such as deterioration of the motor winding insulation, short circuits between winding phases, and open circuit failures depending on the operating environment.

[0003] For example, it is known to detect deterioration of the insulation resistance of a motor in a motor drive device that includes a power supply unit that rectifies power supplied from an AC power supply via a switch using a rectifier circuit and smooths it using a capacitor, and a motor drive amplifier that converts the DC voltage from the power supply unit into AC to drive the motor.

[0004] JP 2007-159289 A JP 2016-73127 A JP 2007-232517 A

[0005] It is desirable to be able to predict motor failures and perform preventative maintenance without removing the motor from the motor drive device.

[0006] According to one aspect of the present disclosure, a three-phase AC motor includes an inverter unit that applies a voltage to windings between each phase of the motor, and a command unit that generates commands to control the voltage applied by the inverter unit to the windings between each phase, and the inverter unit applies an impulse voltage to the windings between each phase in response to a command from the command unit to diagnose the condition of the motor windings.

[0007] FIG. 1 is a diagram illustrating a motor drive device according to a first embodiment of the present disclosure. FIG. 2 is a diagram illustrating an example of the position of magnetic poles of a rotor of a synchronous motor. FIG. 3 is a diagram illustrating the relationship between the position of magnetic poles of the rotor of a synchronous motor and the inductance of each phase winding. FIG. 4 is a diagram illustrating an example of a voltage detection result by a voltage detection unit when an impulse voltage is applied by an inverter unit to windings between phases in a diagnostic mode when the motor windings are normal. FIG. 5 is a diagram illustrating an example of a voltage detection result by a voltage detection unit when an impulse voltage is applied by an inverter unit to windings between phases in a diagnostic mode when there is a short circuit inside the V-phase winding of the motor. FIG. 6 is a diagram illustrating an example of a voltage detection result by a voltage detection unit when an impulse voltage is applied by an inverter unit to windings between phases in a diagnostic mode when there is a short circuit between the W-phase winding and the U-phase winding of the motor. FIG. 7 is a diagram illustrating a diagnostic process by a diagnostic unit in the motor drive device according to the first embodiment of the present disclosure. FIG. 8 is a flowchart illustrating an operation flow in the diagnostic mode of the motor drive device according to a modification of the first embodiment of the present disclosure. FIG. 9 is a flowchart illustrating an operation flow in the diagnostic mode of the motor drive device according to a modification of the first embodiment of the present disclosure. Fig. 1 is a diagram showing a motor drive device according to a second embodiment of the present disclosure; Fig. 2 is a flowchart showing an operation flow in a diagnostic mode of the motor drive device according to the second embodiment of the present disclosure; Fig. 3 is a diagram showing a motor drive device according to a third embodiment of the present disclosure; Fig. 4 is a flowchart showing an operation flow in a diagnostic mode of the motor drive device according to the third embodiment of the present disclosure;

[0008] A motor drive device and a motor winding diagnosis method 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, and duplicate descriptions of those components may be omitted.

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

[0010] In the first embodiment (including modifications) and the second and third embodiments described below, a case where a three-phase AC motor 3 is controlled by a motor drive device 1 connected to an AC power source 2 is shown as an example. Generally, a switch such as a breaker or an electromagnetic contactor is provided between the AC power source 2 and the motor drive device 1, but the switch is not shown in the following drawings. In the following description of each embodiment, it is assumed that the switch is in a closed state and that the motor drive device 1 receives an AC voltage input from the AC power source 2.

[0011] The number of phases of the AC power supply 2 is not particularly limited in each embodiment, and may be, for example, three-phase or single-phase. Examples of the AC power supply 2 include a three-phase 400V AC power supply, a three-phase 200V AC power supply, a three-phase 600V AC power supply, and a single-phase 100V AC power supply. Here, as an example, the AC power supply 2 is a three-phase AC power supply.

[0012] In each embodiment, the motor 3 may be, for example, a synchronous motor or an induction motor. The motor 3 has a U-phase winding 3U, a V-phase winding 3V, and a W-phase winding 3W. Machines in which the motor 3 is installed include, for example, machine tools, robots, forging machines, injection molding machines, industrial machines, and the like.

[0013] According to the first embodiment of the present disclosure, the motor drive device 1 includes a power supply unit 101 , a motor drive amplifier unit 102 , a command unit 12 , a phase detection unit 13 , a voltage detection unit 14 , and a diagnosis unit 15 .

[0014] The power supply unit 101 has a rectifier circuit 21 and a smoothing capacitor 22. The power supply unit 101 rectifies the AC voltage supplied from the AC power supply 2 into a DC voltage using the rectifier circuit 21, smoothes the rectified DC voltage using the smoothing capacitor 22, and outputs the DC voltage.

[0015] The rectifier circuit 21 in the power supply unit 101 may be any circuit capable of converting AC voltage to DC voltage, such as a diode rectifier circuit, a 120-degree conduction rectifier circuit, or a PWM switching control rectifier circuit having a switching element therein. The rectifier circuit 21 is configured as a three-phase bridge circuit when the AC power supply 2 is a three-phase AC power supply, and is configured as a single-phase bridge circuit when the AC power supply 2 is a single-phase AC power supply. When the rectifier circuit 21 is a PWM switching control rectifier circuit, it is configured as a bridge circuit of switching elements and diodes connected in antiparallel to the switching elements. In this case, examples of the switching elements include FETs, IGBTs, thyristors, and GTOs (gate turn-off thyristors). The type of switching element itself is not limited to this embodiment, and other switching elements may also be used.

[0016] The smoothing capacitor 22 in the power supply unit 101 has the function of smoothing the DC voltage output by the rectifier circuit 21 and the function of storing DC power in the DC link. When the motor 3 is driven by the motor drive device 1, and when the motor drive device 1 is used to diagnose the state of the windings of the motor 3, the smoothing capacitor 22 must be charged in advance to a predetermined voltage. The smoothing capacitor 22 is sometimes referred to as a DC link capacitor. Examples of the smoothing capacitor 22 include an electrolytic capacitor and a film capacitor.

[0017] The power supply unit 101 and the motor drive amplifier unit 102 are connected via a DC link. The "DC link" refers to a circuit portion that electrically connects the DC output side of the power supply unit 101 and the DC input side of the motor drive amplifier unit 102, and may also be called a "DC link unit," "DC link," "DC link unit," or "DC intermediate circuit."

[0018] The motor drive amplifier unit 102 has an inverter unit 11. The inverter unit 11 applies a voltage to windings between the phases of the three-phase AC motor 3.

[0019] The inverter unit 11 in the motor drive amplifier unit 102 is configured as a three-phase bridge circuit in which pairs of switching elements and diodes connected in antiparallel to the switching elements are provided in the upper and lower arms. In the illustrated example, the switching element of the upper arm of the U phase is u1 , the switching element of the lower arm of the U phase is S u2 The switching element of the upper arm of the V phase is S v1 , the V-phase lower arm switching element is S v2 The upper arm switching element of the W phase is S w1 , the switching element of the lower arm of the W phase is S w2 Examples of the switching element include an FET, an IGBT, a thyristor, a GTO, etc. The type of the switching element itself does not limit this embodiment, and other switching elements may be used.

[0020] The command unit 12 generates commands to control the voltages applied to the windings between each phase by the inverter unit 11, and outputs the commands to each switching element within the inverter unit 11. The motor 3 has an operating mode including a normal drive mode in which the motor 3 is driven, and a diagnostic mode in which the condition of the windings of the motor 3 is diagnosed. In the normal drive mode, the command unit 12 generates drive commands to cause the inverter unit 11 to output a three-phase AC voltage for driving the motor 3, and outputs the drive commands to each switching element within the inverter unit 11. In the diagnostic mode, the command unit 12 generates diagnostic commands to cause the inverter unit 11 to output an impulse voltage for diagnosing the condition of the windings of the motor 3, and outputs the diagnostic commands to each switching element within the inverter unit 11. Switching between the normal drive mode and the diagnostic mode is performed, for example, by an operator operating an operation unit (not shown) provided in the motor drive device 1. Alternatively, after the power supply of the motor drive device 1 is turned on, a diagnostic mode may be executed, and if it is determined in the diagnostic mode that the windings of the motor 3 are normal, the diagnostic mode may be switched to the normal drive mode.

[0021] When the inverter unit 11 receives a drive command from the command unit 12, it applies a three-phase AC voltage for driving the motor 3 to the windings between each phase of the motor 3. The drive command is, for example, a PWM switching command. In accordance with the PWM switching command received from the command unit 12, the inverter unit 11 performs a power conversion operation by PWM-controlling the on / off of the switching elements of the upper and lower arms. As the power conversion operation, the inverter unit 11 performs one of a power running operation, a regenerative operation, and a stopping operation depending on the content of the PWM switching command. In the power running operation, the inverter unit 11 converts a DC voltage in the DC link into an AC voltage for driving the motor and supplies it to the motor 3, which rotates the motor 3. In the regenerative operation, the inverter unit 11 converts the AC voltage regenerated by the motor 3 into a DC voltage and returns it to the DC link, which decelerates the motor 3. In the stopping operation, the inverter unit 11 turns off all switching elements and does not output voltage, so the motor 3 remains stopped or rotates by inertia and then stops. In this way, in the normal drive mode, the speed, torque, or rotor position of the motor 3 is controlled based on the AC voltage supplied from the inverter unit 11.

[0022] Furthermore, when the inverter unit 11 receives a diagnostic command from the command unit 12, it applies an impulse voltage to the windings between the phases of the motor 3 to diagnose the state of the windings of the motor 3. When the diagnostic command commands the application of an impulse voltage to the windings between the UV phases of the motor 3 (U-phase winding 3U and V-phase winding 3V), the inverter unit 11 applies an impulse voltage to the windings between the UV phases of the motor 3 (U-phase winding 3U and V-phase winding 3V), and the inverter unit 11 applies an impulse voltage to the windings between the UV phases of the motor 3 to diagnose the state of the windings of the motor 3. u1 and S v2 Only the switching element S is turned on for a short time (for example, several tens of milliseconds). u2 , S v1 , S w1 , S w2 When the diagnostic command commands application of an impulse voltage to the V-phase windings (V-phase winding 3V and W-phase winding 3W) of the motor 3, the inverter unit 11 keeps the switching element S in the OFF state. v1 and S w2Only the switching element S is turned on for a short time (for example, several tens of milliseconds). u1 , S u2 , S v2 , S w1 When the diagnostic command commands application of an impulse voltage to the W-phase winding 3W and the U-phase winding 3U of the motor 3, the inverter unit 11 keeps the switching element S in the OFF state. w1 and S u2 Only the switching element S is turned on for a short time (for example, several tens of milliseconds). u1 , S v1 , S v2 , S w2 The OFF state is maintained for the

[0023] In this manner, the inverter unit 11 applies impulse voltage to the windings of the motor 3 based on the diagnostic command during a diagnostic mode in which the condition of the windings of the motor 3 is diagnosed. As will be described in detail later, in the diagnostic mode, the rotor of the motor 3 is positioned at a phase where the impedance between each of the three phases of the motor 3 is a predetermined value. That is, there is a phase a of the motor 3 where the impedance between the UV phases of the motor 3 is a certain value X, a phase b of the motor 3 where the impedance between the VW phases of the motor 3 is the same value X, and a phase c of the motor 3 where the impedance between the WU phases of the motor 3 is the same value X. As will be described later, the value X is, for example, the maximum value of the impedance. In the diagnostic mode, the inverter unit 11 applies impulse voltage to the windings between the phases of the motor 3 for each of the three phases where the impedance between the three phases of the motor 3 is approximately the same. Thus, a total of three impulse voltage applications are performed during the diagnostic mode. In the diagnostic mode, the rotor of the motor 3 is positioned at a phase where the impedance values ​​between the phases of the motor 3 are approximately the same (such as the value X in the above example), and the inverter unit 11 applies an impulse voltage to each of the windings of the motor 3.

[0024] The phase detection unit 13 detects the phase of the motor 3. Information relating to the phase detected by the phase detection unit 13 is sent to the command unit 12 and the diagnosis unit 15. The information relating to the phase detected by the phase detection unit 13 is used by the command unit 12 to control the drive of the motor 3 in the normal drive mode, and is used to control the output timing of a diagnostic command in the diagnosis mode. The information relating to the phase detected by the phase detection unit 13 is also used by the diagnosis unit 15 to diagnose the state of the windings of the motor 3.

[0025] The voltage detection unit 14 detects at least one of the phase-to-phase voltages on the output side of the inverter unit 11 and the phase-to-ground voltages (phase-to-ground voltages) on the output side of the inverter unit 11. In the example shown in FIG. 1 , the voltage detection unit 14 detects the phase-to-phase voltages on the output side of the inverter unit 11. The phase-to-phase voltages on the output side of the inverter unit 11 are the voltage between the UV phases, the voltage between the VW phases, and the voltage between the WU phases. By detecting only two phases of the three-phase power line connecting the inverter unit 11 and the motor 3, information on the three phase-to-ground voltages on the output side of the inverter unit 11 can be obtained. Furthermore, while the phase-to-ground voltages on the output side of the inverter unit 11 are affected by fluctuations in the potential of the earth (ground point), the phase-to-ground voltages on the output side of the inverter unit 11 are not affected by such fluctuations. Information on each phase-to-ground voltage detected by the voltage detection unit 14 is sent to the diagnosis unit 15. Information relating to the interphase voltages detected by the voltage detection unit 14 is used for driving control of the motor 3 in the normal drive mode, and is used when diagnosing the state of the windings of the motor 3 in the diagnosis mode.

[0026] The diagnosing unit 15 diagnoses the state of fault / deterioration of the windings of the motor 3 based on the voltage detection results obtained by the voltage detection unit 14 when the inverter unit 11 applies an impulse voltage to the windings between each phase of the motor 3. That is, the diagnosing unit 15 diagnoses the state of fault / deterioration of the windings between each phase of the motor 3 based on the impulse response of the windings between each phase of the motor 3. As described above, in the diagnosing mode, the inverter unit 11 applies an impulse voltage to the (inter-phase) windings of the motor 3 for each of the three phases where the impedance between the three phases of the motor 3 is approximately the same. Therefore, in the diagnosing mode, three voltage detection results are obtained by the voltage detection unit 14, one for each of the three phases where the impedance between the three phases of the motor 3 is approximately the same. In the diagnosing mode, each voltage detection result obtained by the voltage detection unit 14 is temporarily stored in a memory (not shown). After all three voltage detection results are obtained, the diagnosing unit 15 performs the diagnosing process. Details of the diagnosing process by the diagnosing unit 15 will be described later.

[0027] 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 command unit 12, a diagnosis unit 15, a brake control unit 18 (described later), and other processing circuits. 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 command unit 12, the diagnosis unit 15, the brake control unit 18, and other processing circuits 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 of the command unit 12, the diagnosis unit 15, the brake control unit 18, and other processing circuits 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 command unit 12, the diagnosis unit 15, the brake control unit 18, and other processing circuits may be implemented as semiconductor integrated circuits in which programs for implementing the functions of each unit are written.

[0028] The motor drive device 1 also includes at least one memory serving as a storage device. 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 device may also have a configuration such as an HDD or SSD. The memory stores programs for operating the command unit 12, diagnosis unit 15, brake control unit 18, and other processing circuits. The memory also stores voltage detection results obtained by the voltage detection unit 14 in the diagnosis mode. The memory also stores various data related to the motor drive device 1.

[0029] Next, the relationship between the position of the magnetic poles of the rotor of the motor 3 and the impedance between the phases of the motor 3 in the diagnostic mode will be described.

[0030] Fig. 2 is a diagram illustrating the positions of the magnetic poles of the rotor of a synchronous motor. For simplicity, components other than the inverter unit 11 in the motor drive device 1 are omitted from Fig. 2. Fig. 3 is a diagram illustrating the relationship between the positions of the magnetic poles of the rotor of the synchronous motor and the inductance of each phase winding. In Fig. 3, the inductance Lu of the U-phase winding 3U is indicated by a solid line, the inductance Lv of the V-phase winding 3V is indicated by a dashed line, and the inductance Lw of the W-phase winding 3W is indicated by a dashed line.

[0031] As shown in Fig. 2, a synchronous motor, motor 3, is connected to the AC output side of inverter unit 11. A Y-connected U-phase winding 3U, V-phase winding 3V, and W-phase winding 3W are provided on the stator of motor 3. A magnet 32 ​​is provided on a rotor 31 of motor 3. In the example shown in Fig. 2, motor 3 has two poles, and arrows indicate the direction from the south pole to the north pole of magnet 32. Note that although three arrows are shown for magnet 32 ​​in Fig. 2, these merely indicate three magnetic pole positions a, b, and c (which are offset from each other by 120 degrees) for one magnet 32, and do not indicate the presence of three magnets.

[0032] As shown in Figure 3, the inductances of the U-phase winding 3U, V-phase winding 3V, and W-phase winding 3W of the motor 3, which is a synchronous motor, vary with a phase shift of 120 degrees depending on the phase (the magnetic pole position of the rotor 31). The parasitic capacitances of the U-phase winding 3U, V-phase winding 3V, and W-phase winding 3W also vary with a phase shift of 120 degrees depending on the phase (the magnetic pole position of the rotor 31). Therefore, the impedances (the sum of the inductance and parasitic capacitance) of the U-phase winding 3U, V-phase winding 3V, and W-phase winding 3W vary with a phase shift of 120 degrees depending on the phase (the magnetic pole position of the rotor 31).

[0033] For example, when the magnetic pole position θ is 90 degrees, the inductance Lu of the U-phase winding 3U is maximum, but the inductance Lv of the V-phase winding 3V and the inductance Lw of the W-phase winding 3W are approximately the same. Because each phase within the motor 3 is structurally symmetric, the parasitic capacitance also shows a similar trend, that is, the parasitic capacitance of the U-phase winding 3U is maximum, and the parasitic capacitance of the V-phase winding 3V and the parasitic capacitance of the W-phase winding 3W are approximately the same. Therefore, when the magnetic pole position θ is 90 degrees, the impedance between the U-phase and V-phases (the U-phase winding 3U and the V-phase winding 3V) and the impedance between the U-phase and W-phases (the U-phase winding 3U and the W-phase winding 3W) are approximately the same. Furthermore, theoretically, when the impedance of the U-phase winding 3U is at its maximum, the impedance of the U-phase winding 3U is approximately the same as the impedance between the UV phases (the U-phase winding 3U and the V-phase winding 3V) and also approximately the same as the impedance between the U-phase and W phases (the U-phase winding 3U and the W-phase winding 3W).

[0034] Similarly, for example, when the magnetic pole position θ is 210 degrees, the inductance Lv of the V-phase winding 3V is maximum, but the inductance Lu of the U-phase winding 3U and the inductance Lw of the W-phase winding 3W are approximately the same magnitude. Also, the parasitic capacitance of the V-phase winding 3V is maximum, and the parasitic capacitance of the U-phase winding 3U and the parasitic capacitance of the W-phase winding 3W are approximately the same magnitude. Therefore, when the magnetic pole position θ is 210 degrees, the impedance between the V-U phase (between the V-phase winding 3V and the U-phase winding 3U) and the impedance between the V-W phase (between the V-phase winding 3V and the W-phase winding 3W) are approximately the same magnitude. Furthermore, theoretically, when the impedance of the V-phase winding 3V is at its maximum, the impedance of the V-phase winding 3V is approximately the same as the impedance between the V-U phase (the V-phase winding 3V and the U-phase winding 3U) and also approximately the same as the impedance between the V-W phase (the V-phase winding 3V and the W-phase winding 3W).

[0035] Similarly, for example, when the magnetic pole position θ is 330 degrees, the inductance Lw of the W-phase winding 3W is maximum, but the inductance Lu of the U-phase winding 3U and the inductance Lv of the V-phase winding 3V are approximately the same magnitude. Also, the parasitic capacitance of the W-phase winding 3W is maximum, and the parasitic capacitance of the U-phase winding 3U and the parasitic capacitance of the V-phase winding 3V are approximately the same magnitude. Therefore, when the magnetic pole position θ is 330 degrees, the impedance between the W-U phase (W-phase winding 3W and U-phase winding 3U) and the impedance between the W-V phase (W-phase winding 3W and V-phase winding 3V) are approximately the same magnitude. Furthermore, theoretically, when the impedance of the W-phase winding 3W is at its maximum, the impedance of the W-phase winding 3W is approximately the same as the impedance between the W-U phase (W-phase winding 3W and U-phase winding 3U) and also approximately the same as the impedance between the W-V phase (W-phase winding 3W and V-phase winding 3V).

[0036] Thus, for example, when the rotor 31 of the motor 3 is located in the phase (magnetic pole position) where the inductance Lu of the U-phase winding 3U is maximum, the phase (magnetic pole position) where the inductance Lv of the V-phase winding 3V is maximum, and the phase (magnetic pole position) where the inductance Lw of the W-phase winding 3W is maximum, the impedances of the windings between the phases are substantially identical when the rotor 31 of the motor 3 is located in these three positions. Note that there are cases where the impedances of the windings between the phases are substantially identical, other than the phases where the inductances of the windings of the phases are maximum as described above. However, since the phase where the inductance of the windings of the phases is maximum can be easily determined, for example, during the design of the motor 3, it is convenient to use this information when setting the "phase where the impedances of the windings between the phases are substantially identical."

[0037] During the design of the motor 3, for example, three phases at which the impedances of the windings between the phases of the motor 3 are approximately the same are identified, and this phase information is stored in the memory of the motor drive device 1. In the diagnostic mode, the "three phases at which the impedances of the windings between the phases of the motor 3 are approximately the same" stored in the memory of the motor drive device 1 are first read. The command unit 12 then generates a drive command to move the rotor 31 of the motor 3 so that it is in one of the "three phases at which the impedances of the windings between the phases of the motor 3 are approximately the same," while referring to the phase detected by the phase detection unit 13, and outputs the drive command to the switching elements in the inverter unit 11. Upon receiving this drive command, the inverter unit 11 applies an AC voltage to the windings between the phases of the motor 3, necessary to move the rotor 31 of the motor 3 to the corresponding phase. As a result, the rotor 31 of the motor 3 rotates until it reaches the corresponding phase and then stops. In the diagnostic mode, this motor drive process is executed for each of the "three phases at which the impedances of the windings between the phases of the motor 3 are approximately the same."

[0038] Next, the diagnosis process performed by the diagnosis unit 15 will be described.

[0039] As described above, in the diagnostic mode, the inverter unit 11 applies an impulse voltage to the windings (between phases) of the motor 3 for each of the three phases where the impedances between the three phases of the motor 3 are approximately the same. That is, in the diagnostic mode, the inverter unit 11 applies an impulse voltage to the windings of the motor 3 while the rotor of the motor 3 is positioned at each of the phases where the impedances between the three phases of the motor 3 are approximately the same. Therefore, in the diagnostic mode, three voltage detection results are obtained by the voltage detection unit 14, corresponding to each of the three phases where the impedances between the three phases of the motor 3 are approximately the same. If the windings of the motor 3 are normal, the three voltage waveforms obtained by the voltage detection unit 14 in the diagnostic mode should be approximately the same. On the other hand, if there is a discrepancy between the three voltage waveforms obtained by the voltage detection unit 14 in the diagnostic mode, it can be said that the windings of the motor 3 have deteriorated or failed. Therefore, the diagnosing unit 15 diagnoses the state of fault or deterioration of the windings of the motor 3 based on the voltage detection results by the voltage detecting unit 14 when the inverter unit 11 applies an impulse voltage to the windings between each phase in the diagnosing mode.

[0040] 4 is a diagram illustrating the voltage detection result by the voltage detector when the inverter unit applies an impulse voltage to the windings between each phase in the diagnosis mode when the motor windings are normal. In FIG. 4, the voltage v between the U and V phases detected by the voltage detector 14 in the three-phase power line between the inverter unit 11 and the motor 3 when the inverter unit 11 applies an impulse voltage is uv is shown by a solid line, and the voltage between the V and W phases v vw is shown by a dashed line, and the voltage between the W and U phases v wu In the diagnosis mode, when an impulse voltage is applied by the inverter unit 11, the impedances between the three phases of the motor 3 are substantially the same. Therefore, if the windings of the motor 3 are normal, the voltage v between the U and V phases obtained by the voltage detection unit 14 in the diagnosis mode is uv The waveform of the voltage between the V and W phases vw The waveform of the voltage between the W and U phases v wu The waveforms are almost identical to those of

[0041] 5 is a diagram illustrating the voltage detection result by the voltage detector when an impulse voltage is applied to the windings between each phase by the inverter unit in the diagnosis mode in the case where a short circuit occurs inside the V-phase winding of the motor. In FIG. 5, the voltage V between the U and V phases detected by the voltage detector 14 in the three-phase power line between the inverter unit 11 and the motor 3 when the impulse voltage is applied by the inverter unit 11 is uv is shown by a solid line, and the voltage between the V and W phases v vw is shown by a dashed line, and the voltage between the W and U phases v wu is indicated by a dashed line. For example, if a short circuit occurs inside the V-phase winding 3V of the motor 3, the impedance of the V-phase winding 3V in the diagnostic mode changes. In this case, the voltage v between the U and V phases acquired by the voltage detection unit 14 in the diagnostic mode uv The waveform of the voltage between the V and W phases vw On the other hand, the impedance of the W-phase winding 3W and the U-phase winding 3U between the W and U phases does not change in the diagnostic mode. Therefore, the voltage v between the W and U phases acquired by the voltage detection unit 14 in the diagnostic mode wu The waveform of the voltage between the UV phases v uv and the voltage between the V and W phases v vw The waveform will be deviated from the waveform shown.

[0042] 6 is a diagram illustrating the voltage detection result by the voltage detection unit when an impulse voltage is applied to the windings between each phase by the inverter unit in the diagnosis mode in the case where a short circuit occurs between the W-phase winding and the U-phase winding of the motor. In FIG. 6, when an impulse voltage is applied by the inverter unit 11, the voltage v between the U-phase winding and the U-phase winding detected by the voltage detection unit 14 in the three-phase power line between the inverter unit 11 and the motor 3 is uv is shown by a solid line, and the voltage between the V and W phases v vw is shown by a dashed line, and the voltage between the W and U phases v wu is indicated by a dashed line. For example, if a short circuit occurs between the W-phase winding 3W and the U-phase winding 3U of the motor 3, the W-phase power line and the U-phase power line among the three-phase power lines between the inverter unit 11 and the motor 3 will have the same potential. In this case, the voltage v between the W and U phases acquired by the voltage detection unit 14 in the diagnostic mode wuThe waveform of is almost zero (0), and the voltage between the UV phases v uv and the voltage between the V and W phases v vw The waveform will be deviated from the waveform shown.

[0043] It should be noted that the voltage detection results shown in FIGS. 4 to 6 are merely examples, and voltage detection results other than those shown may also be obtained.

[0044] In this way, when the windings of the motor 3 are normal, the voltage v between the U and V phases acquired by the voltage detection unit 14 when the impulse voltage is applied by the inverter unit 11 in the diagnostic mode is uv The waveform of the voltage between the V and W phases vw The waveform of the voltage between the W and U phases v wu The waveforms of the phase-to-phase voltages acquired by the voltage detection unit 14 substantially coincide with the waveforms of the phase-to-phase voltages acquired by the voltage detection unit 14 in the diagnosis mode. On the other hand, if there is some abnormality in the windings of the motor 3, some deviation will occur in the waveforms of the phase-to-phase voltages acquired by the voltage detection unit 14 in the diagnosis mode when an impulse voltage is applied by the inverter unit 11. In the first embodiment, the diagnosis unit 15 determines that the windings of the motor 3 are normal if there is no deviation in the waveforms of the phase-to-phase voltages acquired by the voltage detection unit 14 in the diagnosis mode. The diagnosis unit 15 determines that the windings of the motor 3 are abnormal if there is some deviation in the waveforms of the phase-to-phase voltages acquired by the voltage detection unit 14 in the diagnosis mode.

[0045] FIG. 7 is a diagram illustrating the diagnostic processing by the diagnostic unit in the motor drive device according to the first embodiment of the present disclosure.

[0046] The first threshold value S is used as a threshold value for the diagnosis process by the diagnosis unit 15. th1 and a second threshold value S th2 is set in advance. The first threshold value S th1 is the second threshold S th2 The first threshold S th1 is used to determine whether the windings of the motor 3 are normal or deteriorated. th2is used to determine whether the windings of the motor 3 have deteriorated or broken. Here, "failure" refers to, for example, an abnormality to the extent that the motor 3 is completely unable to operate normally. "Deterioration" refers to, for example, an abnormality to the extent that the motor 3 has not yet broken down, but the operating performance has deteriorated and a future breakdown is predicted. The first threshold value S th1 and a second threshold value S th2 The first threshold value S may be set by, for example, operating the motor drive device 1 through an experiment or actual operation, or by computer simulation, after determining in advance the relationship between the voltage detection result by the voltage detection unit 14 and the state of the windings of the motor 3, and then taking into account the usage environment of the motor drive device 1 and the motor 3. th1 and a second threshold value S th2 The first threshold value S may be stored in a rewritable memory and may be rewritable by an external device. th1 and a second threshold value S th2 Even after being set, it can be changed to an appropriate value as needed.

[0047] The diagnostic unit 15 calculates the area (hereinafter referred to as the "diagnosis area") of the region surrounded by the maximum and minimum voltage waveforms among the three voltage waveforms (the area indicated by diagonal lines in FIG. 7) for a certain time period (from time t1 to time t2 in FIG. 7) for the three voltage detection results obtained by the voltage detection unit 14 when an impulse voltage is applied by the inverter unit 11 in the diagnosis mode. The diagnostic unit 15 calculates the area (hereinafter referred to as the "diagnosis area") of the region surrounded by the maximum and minimum voltage waveforms among the three voltage waveforms during a certain time period (from time t1 to time t2 in FIG. 7) when the diagnosis area is greater than or equal to a first threshold value S th1 If the diagnosis area is smaller than the first threshold value S th1 and a second threshold S th2 If the diagnosis area is smaller than the second threshold value S th2 If it is greater than , it is determined that the winding of the motor 3 is faulty.

[0048] For example, if the diagnostic unit 15 determines that the windings of the motor 3 are normal, the diagnostic unit 15 outputs a normal signal as the diagnostic result. For example, if the diagnostic unit 15 determines that the windings of the motor 3 are deteriorated, the diagnostic unit 15 outputs a warning signal as the diagnostic result. For example, if the diagnostic unit 15 determines that the windings of the motor 3 are faulty, the diagnostic unit 15 outputs a fault signal as the diagnostic result.

[0049] The diagnosis results from the diagnosing unit 15 may be displayed on, for example, a display device. Examples of display devices include a standalone display device, a display device attached to the motor drive device 1, and a display device attached to a personal computer or a mobile terminal. For example, the display device may display, for example, "Motor winding is normal," "Motor winding is deteriorated," or "Motor winding is faulty." The above-mentioned display example on the display device is merely one example, and "Motor winding is normal," "Motor winding is deteriorated," and "Motor winding is faulty" may be displayed using other expressions or pictures.

[0050] The diagnosis results from the diagnosing unit 15 may be output by an audio device that emits sounds such as voice, a speaker, a buzzer, or a chime. For example, a tone, scale, rhythm, or melody may be set so that the differences between "motor winding is normal," "motor winding is deteriorated," and "motor winding is faulty" can be distinguished. Furthermore, the audio device may be silent when "motor winding is normal," and emit a sound only when "motor winding is deteriorated" or "motor winding is faulty."

[0051] The diagnosis results from the diagnosis unit 15 may be printed out on paper or the like using a printer and displayed.

[0052] The above describes examples of notifying the operator of the diagnosis results by the diagnosing unit 15, but these may be combined as appropriate. Furthermore, each time a diagnosis result is obtained by the diagnosing unit 15, it may be stored and accumulated in memory, and the data may be compiled into a database, which may be used for failure prediction and preventive maintenance.

[0053] The worker can quickly and reliably grasp the state of the windings of the motor 3 based on the notified diagnosis result by the diagnosing unit 15. Therefore, if the worker determines from the diagnosis result by the diagnosing unit 15 that the motor 3 has failed or deteriorated, the worker can take action such as replacing or repairing the motor 3.

[0054] FIG. 8 is a flowchart showing an operation flow in the diagnosis mode of the motor drive device according to the first embodiment of the present disclosure.

[0055] In step S101, when the power supply of the motor drive device 1 is turned on, AC current flows into the rectifier circuit 21 from the AC power supply 2. The rectifier circuit 21 converts the AC current into DC current and outputs it, which pre-charges the smoothing capacitor 22. Once the pre-charging of the smoothing capacitor 22 is complete, the system can enter either a diagnostic mode or a normal drive mode. When the system enters the diagnostic mode, the command unit 12 reads out, from the memory of the motor drive device 1, "three phases for which the impedance of the winding between each phase of the motor 3 becomes a predetermined value." Here, an example of the predetermined value is the maximum value of the impedance. Next, the system proceeds to step S102.

[0056] In step S102, the command unit 12, while referring to the phase detected by the phase detection unit 13, generates a drive command to position the rotor of the motor 3 at a phase where the impedance of the winding between the U and V phases of the motor 3 becomes a predetermined value, and outputs the drive command to the switching elements in the inverter unit 11. In response to this drive command, the inverter unit 11 applies an AC voltage required to move the rotor 31 of the motor 3 to the winding between each phase of the motor 3 so as to achieve that phase. As a result, the rotor 31 of the motor 3 rotates until it reaches that phase and then stops.

[0057] In step S103, the command unit 12 outputs a diagnostic command to the switching elements in the inverter unit 11 to instruct the application of an impulse voltage to the windings between the U and V phases of the motor 3 (U-phase winding 3U and V-phase winding 3V). In response to this diagnostic command, the inverter unit 11 applies an impulse voltage to the windings between the U and V phases of the motor 3.

[0058] In step S104, the voltage detection unit 14 detects the voltage between the UV phases on the output side of the inverter unit 11. The voltage detection result by the voltage detection unit 14 is temporarily stored in memory.

[0059] In step S105, the command unit 12, while referring to the phase detected by the phase detection unit 13, generates a drive command to position the rotor of the motor 3 at a phase where the impedance of the winding between the V and W phases of the motor 3 becomes a predetermined value, and outputs the drive command to the switching elements in the inverter unit 11. In response to this drive command, the inverter unit 11 applies an AC voltage required to move the rotor 31 of the motor 3 to the winding between each phase of the motor 3 so as to achieve that phase. As a result, the rotor 31 of the motor 3 rotates until it reaches that phase and then stops.

[0060] In step S106, the command unit 12 outputs a diagnostic command to the switching elements in the inverter unit 11 to instruct the application of an impulse voltage to the VW inter-phase windings (V-phase winding 3V and W-phase winding 3W) of the motor 3. In response to this diagnostic command, the inverter unit 11 applies an impulse voltage to the VW inter-phase windings of the motor 3.

[0061] In step S107, the voltage detection unit 14 detects the voltage between the V and W phases on the output side of the inverter unit 11. The voltage detection result by the voltage detection unit 14 is temporarily stored in memory.

[0062] In step S108, the command unit 12, while referring to the phase detected by the phase detection unit 13, generates a drive command to position the rotor of the motor 3 at a phase where the impedance of the winding between the W and U phases of the motor 3 becomes a predetermined value, and outputs the drive command to the switching elements in the inverter unit 11. In response to this drive command, the inverter unit 11 applies an AC voltage required to move the rotor 31 of the motor 3 to the winding between each phase of the motor 3 so as to achieve that phase. As a result, the rotor 31 of the motor 3 rotates until it reaches that phase and then stops.

[0063] In step S109, the command unit 12 outputs a diagnostic command to the switching elements in the inverter unit 11 to instruct the application of an impulse voltage to the W-phase windings (W-phase winding 3W and U-phase winding 3U) of the motor 3. In response to this diagnostic command, the inverter unit 11 applies an impulse voltage to the W-phase windings of the motor 3.

[0064] In step S110, the voltage detection unit 14 detects the voltage between the W and U phases on the output side of the inverter unit 11. The voltage detection result by the voltage detection unit 14 is temporarily stored in memory.

[0065] In step S111, the diagnosing unit 15 diagnoses the state of the windings of the motor 3 based on the voltage detection result stored in memory by the voltage detecting unit 14. The diagnosis result by the diagnosing unit 15 is notified to the operator by the display device, audio device, etc., as described above.

[0066] According to the first embodiment of the present disclosure, failure prediction and preventive maintenance of the motor 3 can be performed without removing the motor 3 from the motor drive device 1. Because the inverter unit 11 outputs an impulse voltage for diagnosing the condition of the windings of the motor 3, there is no need to remove the motor 3 from the motor drive device 1 to diagnose the condition of the windings of the motor 3. For example, after the motor drive device 1 is powered on, a diagnostic mode is executed. If the diagnostic mode determines that the windings of the motor 3 are normal, the diagnostic mode is switched to a normal drive mode, thereby periodically diagnosing the condition of the windings of the motor 3. Furthermore, for example, an operator can switch from the normal drive mode to the diagnostic mode by operating an operation unit (not shown) provided on the motor drive device 1, thereby periodically diagnosing the condition of the windings of the motor 3 at a desired timing. Furthermore, because the operator can quickly and reliably grasp the condition of the windings of the motor 3 based on the diagnosis results from the diagnostic unit 15, failure prediction and preventive maintenance are facilitated. If the diagnosis result of the diagnosing unit 15 indicates that the motor 3 has broken down or deteriorated, the worker can take action such as replacing or repairing the motor 3.

[0067] <Modification of First Embodiment> FIG. 9 is a diagram showing a motor drive device according to a modification of the first embodiment of the present disclosure.

[0068] The voltage detection unit 14 detects at least one of the phase-to-phase voltages on the output side of the inverter unit 11 and the phase-to-ground voltages (phase-to-ground voltages) on the output side of the inverter unit 11. In the modified example shown in FIG. 9 , the voltage detection unit 14 detects the phase-to-ground voltages (phase-to-ground voltages) on the output side of the inverter unit 11. The phase-to-ground voltages on the output side of the inverter unit 11 are detected for all three phases of the three-phase power line connecting the inverter unit 11 and the motor 3. Therefore, the three phase-to-ground voltages on the output side of the inverter unit 11 are the U phase-to-ground voltage (hereinafter referred to as the "voltage between the U and G phases"), the V phase-to-ground voltage (hereinafter referred to as the "voltage between the V and G phases"), and the W phase-to-ground voltage (hereinafter referred to as the "voltage between the W and G phases"). Information about each phase-to-ground voltage detected by the voltage detection unit 14 is sent to the diagnosis unit 15. Information relating to each phase-to-ground voltage detected by the voltage detection unit 14 is used for driving control of the motor 3 in the normal drive mode, and is used when diagnosing the state of the windings of the motor 3 in the diagnosis mode.

[0069] The components within the power supply unit 101, the components within the motor drive amplifier unit 102, the command unit 12, the phase detection unit 13, the AC power supply 2, and the motor 3 are as described in the first embodiment with reference to FIGS. 1 and 2.

[0070] In the first embodiment described above, the relationship between the position of the magnetic poles of the rotor of the motor 3 and the impedance between the phases of the motor 3 in the diagnosis mode, and the diagnosis process by the diagnosis unit 15 were explained with reference to Figures 2 to 7. This explanation can be similarly applied to this modified example due to the symmetry of the structure of the motor 3. In other words, if the windings of the motor 3 are normal, the voltage v between the U and G phases acquired by the voltage detection unit 14 when the impulse voltage is applied by the inverter unit 11 in the diagnosis mode is ug The waveform of the VG phase voltage v vg The waveform of the WG phase and the voltage v wgThe waveforms of the phase-to-ground voltages obtained by the voltage detection unit 14 in the diagnostic mode substantially coincide with those of the phase-to-ground voltages obtained by the voltage detection unit 14 in the diagnostic mode. On the other hand, if there is some abnormality in the windings of the motor 3, some deviation will occur in the waveforms of the phase-to-ground voltages obtained by the voltage detection unit 14 in the diagnostic mode when an impulse voltage is applied by the inverter unit 11. In this modified example, if there is no deviation in the waveforms of the phase-to-ground voltages obtained by the voltage detection unit 14 in the diagnostic mode, the diagnostic unit 15 determines that the windings of the motor 3 are normal. If there is some deviation in the waveforms of the phase-to-ground voltages obtained by the voltage detection unit 14 in the diagnostic mode, the diagnostic unit 15 determines that the windings of the motor 3 are abnormal. The diagnostic process by the diagnostic unit 15 described with reference to FIG. 7 can also be applied to this modified example. An example of notifying the operator of the diagnosis result by the diagnostic unit 15 is the same as that described in the first embodiment.

[0071] FIG. 10 is a flowchart showing an operation flow in the diagnosis mode of the motor drive device according to the modified example of the first embodiment of the present disclosure.

[0072] The explanation regarding step S201 is the same as that regarding step S101 in FIG.

[0073] In step S202, the command unit 12, while referring to the phase detected by the phase detection unit 13, generates a drive command to position the rotor of the motor 3 at a phase where the impedance of the winding between the U and V phases of the motor 3 becomes a predetermined value, and outputs the drive command to the switching elements in the inverter unit 11. In response to this drive command, the inverter unit 11 applies an AC voltage required to move the rotor 31 of the motor 3 to the winding between each phase of the motor 3 so as to achieve that phase. As a result, the rotor 31 of the motor 3 rotates until it reaches that phase and then stops.

[0074] In step S203, the command unit 12 outputs a diagnostic command to the switching elements in the inverter unit 11 to instruct the application of an impulse voltage to the windings between the U and V phases of the motor 3 (U-phase winding 3U and V-phase winding 3V). In response to this diagnostic command, the inverter unit 11 applies an impulse voltage to the windings between the U and V phases of the motor 3.

[0075] In step S204, the voltage detection unit 14 detects the voltage between the U and G phases (voltage between the U phase and ground) on the output side of the inverter unit 11. The voltage detection result by the voltage detection unit 14 is temporarily stored in memory.

[0076] In step S205, the command unit 12, while referring to the phase detected by the phase detection unit 13, generates a drive command to position the rotor of the motor 3 at a phase where the impedance of the winding between the V and W phases of the motor 3 becomes a predetermined value, and outputs the drive command to the switching elements in the inverter unit 11. In response to this drive command, the inverter unit 11 applies an AC voltage required to move the rotor 31 of the motor 3 to the winding between each phase of the motor 3 so as to achieve that phase. As a result, the rotor 31 of the motor 3 rotates until it reaches that phase and then stops.

[0077] In step S206, the command unit 12 outputs a diagnostic command to the switching elements in the inverter unit 11 to instruct the application of an impulse voltage to the VW inter-phase windings (V-phase winding 3V and W-phase winding 3W) of the motor 3. In response to this diagnostic command, the inverter unit 11 applies an impulse voltage to the VW inter-phase windings of the motor 3.

[0078] In step S207, the voltage detection unit 14 detects the voltage between the V and G phases (the voltage between the V phase and ground) on the output side of the inverter unit 11. The voltage detection result by the voltage detection unit 14 is temporarily stored in memory.

[0079] In step S208, the command unit 12, while referring to the phase detected by the phase detection unit 13, generates a drive command to position the rotor of the motor 3 at a phase where the impedance of the winding between the W and U phases of the motor 3 becomes a predetermined value, and outputs the drive command to the switching elements in the inverter unit 11. In response to this drive command, the inverter unit 11 applies an AC voltage required to move the rotor 31 of the motor 3 to the winding between each phase of the motor 3 so as to achieve that phase. As a result, the rotor 31 of the motor 3 rotates until it reaches that phase and then stops.

[0080] In step S209, the command unit 12 outputs a diagnostic command to the switching elements in the inverter unit 11 to instruct the application of an impulse voltage to the W-phase windings (W-phase winding 3W and U-phase winding 3U) of the motor 3. In response to this diagnostic command, the inverter unit 11 applies an impulse voltage to the W-phase windings of the motor 3.

[0081] In step S210, the voltage detection unit 14 detects the voltage between the W and G phases (the voltage between the W phase and ground) on the output side of the inverter unit 11. The voltage detection result by the voltage detection unit 14 is temporarily stored in memory.

[0082] In step S211, the diagnosing unit 15 diagnoses the state of the windings of the motor 3 based on the voltage detection result stored in memory by the voltage detecting unit 14. The diagnosis result by the diagnosing unit 15 is notified to the operator by the display device, audio device, etc., as described above.

[0083] According to the modified example of the first embodiment of the present disclosure, the same effects as those of the first embodiment described with reference to FIGS. 1 to 8 are achieved.

[0084] Second Embodiment FIG. 11 is a diagram showing a motor drive device according to a second embodiment of the present disclosure.

[0085] In the first embodiment (including its modified examples) described with reference to Figures 1 to 10, diagnostic processing was performed by diagnostic unit 15 based on the voltage detection result of voltage detection unit 14 when impulse voltage was applied by inverter unit 11 to the interphase windings of motor 3. In the second embodiment, instead of diagnostic unit 15 in Figure 1, a display unit 16 is provided that displays the voltage detection result of voltage detection unit 14 when impulse voltage is applied by inverter unit 11 to the interphase windings of motor 3. Examples of display unit 16 include a standalone display device, a display device attached to motor drive device 1, and a display device attached to a personal computer or mobile terminal.

[0086] The components within the power supply unit 101, the components within the motor drive amplifier unit 102, the command unit 12, the phase detection unit 13, the voltage detection unit 14, the AC power supply 2, and the motor 3 are as described with reference to Figures 1 to 10 in the first embodiment and its modified examples. In the example shown in Figure 11, the voltage detection unit 14 detects the phase-to-ground voltage on the output side of the inverter unit 11. In the second embodiment, too, the voltage detection unit 14 may be configured to detect the phase-to-ground voltage (phase-to-ground voltage) on the output side of the inverter unit 11, as described with reference to Figures 9 and 10.

[0087] FIG. 12 is a flowchart showing an operation flow in the diagnosis mode of the motor drive device according to the second embodiment of the present disclosure.

[0088] The explanation regarding steps S101 to S110 in FIG. 12 is the same as that regarding steps S101 to S110 in FIG.

[0089] The voltage detection results of the voltage detection unit 14 when the inverter unit 11 applies an impulse voltage to the windings between each phase of the motor 3 are stored in memory in steps S104, S107, and S110. In step S112 following step S110, the display unit 16 displays the voltage detection results of the voltage detection unit 14 stored in memory.

[0090] 4 to 6, the display unit 16 displays the voltage detection result of the voltage detection unit 14 when the inverter unit 11 applies an impulse voltage to the windings between each phase of the motor 3. By visually checking the display unit 16, the operator can determine whether the windings of the motor 3 are normal or whether the windings of the motor 3 are deteriorated or broken.

[0091] According to the second embodiment of the present disclosure, similarly to the first embodiment, failure prediction and preventive maintenance of the motor 3 can be performed without removing the motor 3 from the motor drive device 1. Because an impulse voltage for diagnosing the state of the windings of the motor 3 is output from the inverter unit 11, there is no need to remove the motor 3 from the motor drive device 1 to diagnose the state of the windings of the motor 3. Furthermore, according to the second embodiment of the present disclosure, the state of the windings of the motor 3 can be diagnosed periodically or at a desired timing based on the voltage detection results by the voltage detection unit 14 displayed on the display unit 16. Furthermore, because the worker can quickly and reliably grasp the state of the windings of the motor 3 based on the voltage detection results by the voltage detection unit 14 displayed on the display unit 16, failure prediction and preventive maintenance are facilitated. If the worker determines that the motor 3 has failed or deteriorated based on the voltage detection results by the voltage detection unit 14 displayed on the display unit 16, the worker can take action, such as replacing or repairing the motor 3.

[0092] Third Embodiment FIG. 13 is a diagram showing a motor drive device according to a third embodiment of the present disclosure.

[0093] The third embodiment is the same as the first embodiment (including its modifications) or the second embodiment, except that a brake device 17 is attached to the motor 3 and a brake control unit 18 is provided to control the brake device 17. Here, as an example, a case where the brake device 17 and the brake control unit 18 are provided in the first embodiment (including its modifications) will be described. The following description is also applicable to the case where the brake device 17 and the brake control unit 18 are provided in the second embodiment.

[0094] A brake device 17 is attached to the motor 3. The brake device 17 is a friction-type brake device that applies a brake to the motor 3 by frictional force by sandwiching a friction plate between an armature and an end plate. In the brake device 17, the elastic force of a spring presses the armature against the friction plate connected to the motor shaft to lock the motor 3 (brake ON), and the brake coil voltage is applied to the brake coil to generate an electromagnetic force that separates the armature from the friction plate to unlock the motor 3 (brake OFF).

[0095] The operation of the brake device 17 is controlled by a brake control unit 18. The brake control unit 18 is provided in the motor drive amplifier unit 102.

[0096] In the diagnosis mode, the inverter unit 11 applies an impulse voltage to the interphase windings of the motor 3, which may cause the rotor of the motor 3 to rotate, even if only slightly. This tendency is particularly strong when the rotor of the motor 3 is lightweight. If the rotor of the motor 3 rotates when the impulse voltage is applied to the interphase windings of the motor 3, the above-mentioned "three phases in which the impedance of the interphase windings of the motor 3 is approximately the same" cannot be maintained, leading to an erroneous diagnosis by the diagnosis unit 15. Therefore, in the third embodiment, the brake control unit 18 brakes the motor 3 under control of the brake control unit 18 while the inverter unit 11 applies an impulse voltage to the interphase windings in the diagnosis mode.

[0097] FIG. 14 is a flowchart showing an operation flow in the diagnosis mode of the motor drive device according to the third embodiment of the present disclosure.

[0098] The explanation regarding step S301 is the same as that regarding step S101 in Fig. 8. At this point, the brake device 17 is not applying the brake to the motor 3 (brake OFF).

[0099] In step S302, the command unit 12, while referring to the phase detected by the phase detection unit 13, generates a drive command to position the rotor of the motor 3 at a phase where the impedance of the winding between the U and V phases of the motor 3 becomes a predetermined value, and outputs the drive command to the switching elements in the inverter unit 11. In response to this drive command, the inverter unit 11 applies an AC voltage required to move the rotor 31 of the motor 3 to the winding between each phase of the motor 3 so as to achieve that phase. As a result, the rotor 31 of the motor 3 rotates until it reaches that phase and then stops.

[0100] In step S303, the brake control unit 18 applies the brake to the motor 3 (brake ON) under the control of the brake control unit 18.

[0101] In step S304, the command unit 12 outputs a diagnostic command to the switching elements in the inverter unit 11 to instruct the application of an impulse voltage to the windings between the U and V phases of the motor 3 (U-phase winding 3U and V-phase winding 3V). In response to this diagnostic command, the inverter unit 11 applies an impulse voltage to the windings between the U and V phases of the motor 3.

[0102] In step S305, the voltage detection unit 14 detects the voltage between the UV phases on the output side of the inverter unit 11. The voltage detection result by the voltage detection unit 14 is temporarily stored in memory.

[0103] In step S306, the brake control unit 18 controls the brake control unit 18 to release the brake on the motor 3 (brake OFF).

[0104] In step S307, the command unit 12, while referring to the phase detected by the phase detection unit 13, generates a drive command to position the rotor of the motor 3 at a phase where the impedance of the winding between the V and W phases of the motor 3 becomes a predetermined value, and outputs the drive command to the switching elements in the inverter unit 11. In response to this drive command, the inverter unit 11 applies an AC voltage required to move the rotor 31 of the motor 3 to the winding between each phase of the motor 3. As a result, the rotor 31 of the motor 3 rotates until it reaches the phase and then stops.

[0105] In step S308, the brake control unit 18 applies the brake to the motor 3 (brake ON) under the control of the brake control unit 18.

[0106] In step S309, the command unit 12 outputs a diagnostic command to the switching elements in the inverter unit 11 to instruct the application of an impulse voltage to the VW inter-phase windings (V-phase winding 3V and W-phase winding 3W) of the motor 3. In response to this diagnostic command, the inverter unit 11 applies an impulse voltage to the VW inter-phase windings of the motor 3.

[0107] In step S310, the voltage detection unit 14 detects the voltage between the V and W phases on the output side of the inverter unit 11. The voltage detection result by the voltage detection unit 14 is temporarily stored in memory.

[0108] In step S311, the brake control unit 18 controls the brake control unit 18 to release the brake on the motor 3 (brake OFF).

[0109] In step S312, the command unit 12, while referring to the phase detected by the phase detection unit 13, generates a drive command to position the rotor of the motor 3 at a phase where the impedance of the winding between the W and U phases of the motor 3 becomes a predetermined value, and outputs the drive command to the switching elements in the inverter unit 11. In response to this drive command, the inverter unit 11 applies an AC voltage required to move the rotor 31 of the motor 3 to the winding between each phase of the motor 3 so as to achieve that phase. As a result, the rotor 31 of the motor 3 rotates until it reaches that phase and then stops.

[0110] In step S313, the brake control unit 18 applies the brake to the motor 3 (brake ON) under the control of the brake control unit 18.

[0111] In step S314, the command unit 12 outputs a diagnostic command to the switching elements in the inverter unit 11 to instruct the application of an impulse voltage to the W-phase windings (W-phase winding 3W and U-phase winding 3U) of the motor 3. In response to this diagnostic command, the inverter unit 11 applies an impulse voltage to the W-phase windings of the motor 3.

[0112] In step S315, the voltage detection unit 14 detects the voltage between the W and U phases on the output side of the inverter unit 11. The voltage detection result by the voltage detection unit 14 is temporarily stored in memory.

[0113] In step S316, the diagnosing unit 15 diagnoses the state of the windings of the motor 3 based on the voltage detection result by the voltage detecting unit 14 stored in memory. The diagnosis result by the diagnosing unit 15 is notified to the operator by the display device, audio device, etc., as described above.

[0114] The third embodiment of the present disclosure provides the same effects as the first embodiment (including its modifications) and the second embodiment. Furthermore, the third embodiment of the present disclosure applies a brake to the motor 3 by the brake device 17 while the inverter unit 11 applies an impulse voltage to the windings between the phases in the diagnosis mode, so that the state of the windings of the motor 3 can be diagnosed more accurately.

[0115] <Further Modifications of Each Embodiment> In the first embodiment (including modifications thereof), second embodiment, and third embodiment, the voltage detection unit 14 is provided outside the motor drive amplifier unit 102, but as a modification, the voltage detection unit 14 may be provided inside the motor drive amplifier unit 102. Furthermore, in the first embodiment (including modifications thereof) and third embodiment, the diagnosis unit 15 is provided outside the motor drive amplifier unit 102, but as a modification, the diagnosis unit may be provided inside the motor drive amplifier unit 102, or may be provided outside the motor drive device 1.

[0116] <Motor Fault Prediction and Fault Maintenance by Diagnosing Motor Windings> According to at least one of the embodiments (including its modifications) described above, fault prediction and preventive maintenance of the motor 3 can be performed without removing the motor 3 from the motor drive device 1. Because an impulse voltage for diagnosing the state of the windings of the motor 3 is output from the inverter unit 11, there is no need to remove the motor 3 from the motor drive device 1 in order to diagnose the state of the windings of the motor 3. Furthermore, the state of the windings of the motor 3 can be diagnosed periodically or at any desired timing.

[0117] Although the present disclosure has been described in detail above, the present disclosure is not limited to the individual embodiments described above. Various additions, substitutions, modifications, partial deletions, etc. are possible in these embodiments without departing from the gist of the present disclosure or the spirit of the present disclosure derived from the content of the claims and their equivalents. These embodiments can also be implemented in combination. For example, in the above-described embodiments, 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 expressions are used in the description of the above-described embodiments.

[0118] <Supplementary Notes> The following supplementary notes are further disclosed regarding the above-described embodiment and modifications.

[0119] (Supplementary Note 1) A motor drive device 1 comprising: an inverter unit 11 that applies a voltage to windings between each phase of a three-phase AC motor 3; and a command unit 12 that generates commands to control the voltage applied to the windings between each phase by the inverter unit 11, wherein the inverter unit 11 applies an impulse voltage to the windings between each phase in response to a command from the command unit 12, for diagnosing the state of the windings of the motor 3. (Supplementary Note 2) The motor drive device 1 according to Supplementary Note 1, wherein the inverter unit 11 applies the impulse voltage to the windings between each phase when the rotor of the motor 3 is in a phase where the impedance between each phase is a predetermined value for each of the three phases of the motor 3. (Supplementary Note 3) The motor drive device 1 according to Supplementary Note 2, wherein the impedance between each phase when the inverter unit 11 applies the impulse voltage is approximately the same. (Supplementary Note 4) The motor drive device 1 of any one of Supplements 1 to 3, comprising a voltage detection unit 14 that detects at least one of the inter-phase voltages on the output side of the inverter unit 11 and the phase-to-ground voltages on the output side of the inverter unit 11. (Supplementary Note 5) The motor drive device 1 of Supplementary Note 4, comprising a diagnosis unit 15 that diagnoses the state of the windings of the motor 3 based on the voltage detection result by the voltage detection unit 14 when an impulse voltage is applied to the windings between the phases by the inverter unit 11. (Supplementary Note 6) The motor drive device 1 of Supplementary Note 4, comprising a display unit 16 that displays the voltage detection result by the voltage detection unit 14 when an impulse voltage is applied to the windings between the phases by the inverter unit 11. (Supplementary Note 7) The motor drive device 1 of any one of Supplements 1 to 6, comprising a brake device 17 that brakes the motor 3 while the impulse voltage is being applied to the windings between the phases by the inverter unit 11.(Supplementary Note 8) A motor winding diagnosis method comprising: a phase adjustment step of positioning a rotor of the motor (3) at a phase where an impedance between the phases of the three-phase AC motor (3) is a predetermined value; an application step of applying impulse voltages to the windings between the phases by the inverter unit (11) after the phase adjustment step has been executed, for diagnosing the state of the windings of the motor (3); a voltage detection step of detecting at least one of each inter-phase voltage on the output side of the inverter unit (11) and each phase-to-ground voltage on the output side of the inverter unit (11) when the impulse voltage is applied to the windings between the phases by the inverter unit (11); and a diagnosis step of diagnosing the state of the windings of the motor (3) based on the voltage detection results obtained in the voltage detection step for the three phases of the motor (3). (Supplementary Note 9) A motor winding diagnosis method comprising: a phase adjustment step of positioning a rotor of motor 3 at a phase where an impedance between phases of three-phase AC motor 3 becomes a predetermined value; an application step of applying impulse voltages to the windings between the phases by inverter unit 11 after the phase adjustment step has been executed, the impulse voltages being used to diagnose the state of the windings of motor 3; a voltage detection step of detecting at least one of each inter-phase voltage on the output side of inverter unit 11 and each phase-to-ground voltage on the output side of inverter unit 11 when the impulse voltage is applied to the windings between the phases by inverter unit 11; and a display step of displaying the voltage detection results obtained in the voltage detection step between the three phases of motor 3. (Supplementary Note 10) A motor winding diagnosis method according to Supplementary Note 8 or 9, wherein the impedance values ​​between the phases when the impulse voltage is applied by inverter unit 11 are substantially the same. (Supplementary Note 11) The motor winding diagnosis method according to any one of Supplementary Notes 8 to 10, further comprising a braking step of applying a brake to the motor 3 by a braking device 17 while the inverter unit 11 applies an impulse voltage to the windings between each phase.

[0120] REFERENCE SIGNS LIST 1 Motor drive device 2 AC power supply 3 Motor 3U U-phase winding 3V V-phase winding 3W W-phase winding 11 Inverter unit 12 Command unit 13 Phase detection unit 14 Voltage detection unit 15 Diagnosis unit 16 Display unit 17 Brake device 18 Brake control unit 21 Rectifier circuit 22 Smoothing capacitor 31 Rotor 32 Magnet 101 Power supply unit 102 Motor drive amplifier unit

Claims

1. An inverter unit that applies a voltage to windings between each phase of a three-phase AC motor; a command unit that generates a command to control an applied voltage to each of the interphase windings by the inverter unit; Equipped with The inverter unit applies an impulse voltage for diagnosing a condition of the windings of the motor to the windings between the phases in response to a command from the command unit.

2. 2. The motor drive device according to claim 1, wherein the inverter unit applies the impulse voltage to a winding between each of the three phases of the motor when a rotor of the motor is in a phase in which an impedance between the phases has a predetermined value.

3. 3. The motor drive device according to claim 2, wherein impedances between the phases when the impulse voltage is applied by the inverter unit are substantially the same.

4. 4. The motor drive device according to claim 1, further comprising a voltage detection unit that detects at least one of each interphase voltage on the output side of the inverter unit and each phase-to-ground voltage on the output side of the inverter unit.

5. 5. The motor drive device according to claim 4, further comprising a diagnosis unit that diagnoses a state of a winding of the motor based on a voltage detection result by the voltage detection unit when the impulse voltage is applied to the winding between each of the phases by the inverter unit.

6. 5. The motor drive device according to claim 4, further comprising a display unit that displays a result of voltage detection by said voltage detection unit when said impulse voltage is applied to each of said interphase windings by said inverter unit.

7. 4. The motor drive device according to claim 1, further comprising a brake device that brakes the motor while the impulse voltage is applied to the windings between the phases by the inverter unit.

8. a phase adjustment step of positioning a rotor of the motor at a phase where an impedance between phases of the three-phase AC motor becomes a predetermined value; an application step of applying an impulse voltage for diagnosing a state of the winding of the motor to the winding between the phases by an inverter unit after the phase adjustment step is performed; a voltage detection step of detecting at least one of each inter-phase voltage on the output side of the inverter unit and each phase-to-ground voltage on the output side of the inverter unit when the impulse voltage is applied to each inter-phase winding by the inverter unit; a diagnosing step of diagnosing a state of a winding of the motor based on the voltage detection results acquired in the voltage detection step between the three phases of the motor; A motor winding diagnosis method comprising:

9. a phase adjustment step of positioning a rotor of the motor at a phase where an impedance between phases of the three-phase AC motor becomes a predetermined value; an application step of applying an impulse voltage for diagnosing a state of the winding of the motor to the winding between the phases by an inverter unit after the phase adjustment step is performed; a voltage detection step of detecting at least one of each inter-phase voltage on the output side of the inverter unit and each phase-to-ground voltage on the output side of the inverter unit when the impulse voltage is applied to each inter-phase winding by the inverter unit; a display step of displaying the voltage detection results obtained in the voltage detection step between the three phases of the motor; A motor winding diagnosis method comprising:

10. 10. The motor winding diagnosis method according to claim 8, wherein impedance values ​​between the phases when the impulse voltage is applied by the inverter unit are substantially the same.

11. 10. The motor winding diagnosis method according to claim 8, further comprising a braking step of braking the motor by a braking device while the impulse voltage is being applied to the windings between the phases by the inverter unit.