Motor drive device having dynamic braking circuit

Abstract

This motor drive device comprises: a storage unit for storing the prespecified parameters of a registered motor; a dynamic braking circuit; a calculation unit for calculating, using the rotational speed per unit time of a driven motor when the dynamic braking circuit starts braking and the parameters stored in the storage unit, information about an estimated value of dynamic braking current flowing while the dynamic braking circuit is braking; a measurement unit for obtaining information about the measured value of the dynamic braking current during braking by the dynamic braking circuit; and a determination unit for determining, on the basis of the result of the comparison between the information about the estimated value of the dynamic braking current and the information about the measured value of the dynamic braking current, whether the driven motor is consistent with the registered motor or not.

Description

[Technical Field]

[0001] The present invention relates to a motor drive device having a dynamic braking circuit. [Background technology]

[0002] 2. Description of the Related Art Dynamic braking, which applies dynamic braking by short-circuiting the input terminals of a motor, is widely used in motor drive devices that drive motors that power machines such as machine tools and robots.

[0003] For example, there is known a power semiconductor module in which electronic components are mounted on an insulating substrate inside a housing and which controls a three-phase AC motor provided outside the housing, the power semiconductor module comprising, on the insulating substrate, a plurality of sets of switching elements each having a pair of upper-side element and lower-side element connected in series to each other, diode elements connected in anti-parallel to the switching elements, and dynamic braking switching elements provided between any two phases of the three-phase AC motor (see, for example, Patent Document 1).

[0004] For example, a servo device is known that includes a power conversion means for converting DC power into three-phase AC power, a current detection means for detecting the current flowing in the output lines of the power conversion means for each phase, a motor driven by the current flowing in the output lines, a speed detection means for detecting the rotational speed of the motor, a relay for short-circuiting each of the output lines directly or via a current limiting means by a back contact when the motor is in an out-of-drive state, and a fault detection means for detecting a fault in the relay or the current limiting means based on the detection output of the current detection means and the detection output of the speed detection means when the motor is in an out-of-drive state while rotating (see, for example, Patent Document 2).

[0005] For example, a motor drive device having a dynamic braking circuit that generates a deceleration torque in a motor includes a dynamic braking current calculation unit that calculates a value of a dynamic braking current flowing in the dynamic braking circuit based on the motor rotation speed and predetermined parameters for the motor and the dynamic braking circuit; a Joule heat calculation unit that calculates Joule heat due to the dynamic braking current applied to the contacts of the relay during a dynamic braking period based on the value of the dynamic braking current obtained by the dynamic braking current calculation unit; and a Joule heat calculation unit that calculates the value of the dynamic braking current at the start of dynamic braking and the Joule heat generated near the contacts of the relay in accordance with the value of the dynamic braking current at the start of dynamic braking. a storage unit that stores in advance a table that defines the relationship between the Joule heat due to the arc and the Joule heat due to the arc; an integrating unit that, each time dynamic braking is performed, integrates the Joule heat due to the arc obtained from the table as corresponding to the value of the dynamic braking current obtained by the dynamic braking current calculation unit at the start of the dynamic braking, the Joule heat due to the dynamic braking current obtained by the Joule heat calculation unit during the dynamic braking period, or the sum of the Joule heat due to the arc and the Joule heat due to the dynamic braking current; and a comparing unit that compares the integrated value obtained by the integrating unit with a preset reference value and outputs the comparison result (see, for example, Patent Document 3). [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Laid-Open No. 2010-098919 [Patent Document 2] Japanese Patent Application Laid-Open No. 2000-253687 [Patent Document 3] Japanese Patent Application Laid-Open No. 2017-022940 Summary of the Invention [Problem to be solved by the invention]

[0007] For machines such as machine tools and robots, the optimal motor is selected for the machine's operation, and the motor drive unit is designed to match the selected motor. Machines such as machine tools and robots are used for many years, often undergoing repairs. When a machine is repaired, the motor powering the machine may be replaced with a different motor than originally selected—for example, a third-party motor rather than a genuine manufacturer motor, or even a genuine manufacturer motor that is not suitable for use with the machine. If a replaced motor with specifications different from the selected motor is connected to a motor drive unit and operated, the motor may behave unexpectedly, causing damage to the machine, the motor installed in the machine, and the motor drive unit that drives the motor, or adversely affecting the surrounding area. For example, a method could be considered to determine whether a genuine manufacturer motor is suitable for use with a machine based on ID information assigned to the motor, but this requires a memory unit to store the ID information in the motor, which is costly. Furthermore, this requires complex design, such as a process for transferring ID information between the motor and the motor drive unit, and the additional effort required to write the ID information to the memory unit. Therefore, there is a need for a motor drive device that is low cost and easy to manufacture and that can determine whether or not an expected motor is attached. [Means for solving the problem]

[0008] According to one aspect of the present disclosure, a motor drive device includes: a storage unit that stores predetermined parameters for a registered motor; a dynamic braking circuit that generates a deceleration torque in the driving motor by short-circuiting input terminals of the driving motor via a dynamic braking resistor, thereby braking the driving motor; a calculation unit that calculates information regarding an estimate of the dynamic braking current flowing between the driving motor and the dynamic braking circuit during braking by the dynamic braking circuit, using the number of rotations per unit time of the driving motor at the time braking by the dynamic braking circuit starts and the parameters stored in the storage unit; a measurement unit that obtains information regarding a measured value of the dynamic braking current flowing between the driving motor and the dynamic braking circuit during braking by the dynamic braking circuit; and a determination unit that determines whether the driving motor matches the registered motor based on a comparison result between the information regarding the estimated value of the dynamic braking current and the information regarding the measured value of the dynamic braking current. [Effects of the Invention]

[0009] According to one aspect of the present disclosure, it is possible to realize a motor drive device that is low cost and easy to manufacture and that can determine whether or not an expected motor is attached. [Brief explanation of the drawings]

[0010] [Figure 1] FIG. 1 illustrates a motor drive device according to an embodiment of the present disclosure. [Figure 2] 10 is a flowchart illustrating an operation flow of a motor drive device according to an embodiment of the present disclosure. [Figure 3] FIG. 10 is a diagram illustrating a current waveform of an estimated value of a dynamic braking current calculated by a calculation unit in the motor drive device according to the embodiment of the present disclosure. DETAILED DESCRIPTION OF THE INVENTION

[0011] A motor drive device having a dynamic braking circuit will now be described with reference to the drawings. In the various drawings, like components are designated by like reference numerals. The scale of the drawings has been changed appropriately to facilitate understanding. The illustrated embodiments are merely examples for carrying out the present invention, and the present invention is not limited to these embodiments.

[0012] FIG. 1 is a diagram illustrating a motor drive device according to an embodiment of the present disclosure.

[0013] A motor driven by a motor drive device 1 according to an embodiment of the present disclosure is referred to as a "driving motor." A motor that has been registered in advance as one permitted to be connected to the motor drive device 1 is referred to as a "registered motor." The driving motor and the registered motor may be, for example, an induction motor or a synchronous motor. For example, a registered motor may be a motor selected at the time of design as a power source for a machine such as a machine tool or robot and permitted to be connected to the motor drive device 1 installed in that machine, or it may be a motor manufactured by the original manufacturer. Examples of motors that differ from registered motors include, for example, a motor manufactured by the original manufacturer that differs from the original design specifications, and a motor manufactured by a third party.

[0014] In one embodiment of the present disclosure, motors permitted to be connected to motor drive device 1 are registered in advance as registered motors, and when the dynamic braking circuit 12 brakes the driving motor, it is determined whether the driving motor is a registered motor. If it is determined that the driving motor does not match the registered motor, the driving motor is an unexpected motor (e.g., a motor manufactured by the original manufacturer that differs from the original design specifications even if manufactured by the original manufacturer, or a motor manufactured by a third party) that is different from the registered motors (e.g., a motor selected in advance as a power source for a machine tool, robot, or other machine at the time of design, or a motor manufactured by the original manufacturer), and the operator is notified of this fact.

[0015] A motor drive device 1 according to an embodiment of the present disclosure includes a converter 101, an inverter 102, a DC link capacitor 103, a motor control unit 10, a memory unit 11, a dynamic braking circuit 12, a calculation unit 13, a measurement unit 14, a determination unit 15, a position detector 16, and a brake control unit 17.

[0016] The converter 101 converts AC power supplied from the AC power source 2 into DC power and outputs it to a DC link. Examples of the converter 101 include a diode rectifier circuit, a 120-degree conduction rectifier circuit, and a rectifier circuit using a PWM switching control method. For example, if the converter 101 is a rectifier circuit using a PWM switching control method, it is made up of switching elements and a bridge circuit of diodes connected in antiparallel to the switching elements, and each switching element is controlled to be turned on and off in response to a drive command received from a higher-level control device (not shown), thereby performing bidirectional AC / DC power conversion. Examples of semiconductor switching elements include unipolar transistors such as FETs, bipolar transistors, IGBTs, thyristors, and GTOs. However, the type of semiconductor switching element itself does not limit the present embodiment, and other semiconductor switching elements may also be used.

[0017] The "DC link" refers to a circuit portion that electrically connects the DC output side of the converter 101 and the DC input side of the inverter 102, and may also be referred to as a "DC link portion," a "DC link," a "DC link portion," a "DC bus," or a "DC intermediate circuit." A DC link capacitor 103 is provided in the DC link. The DC link capacitor 103 has the function of storing energy (DC power) in the DC link and the function of suppressing pulsation in the DC side output of the converter 101. When the DC link capacitor 103 is charged, DC power is stored in the DC link.

[0018] The inverter 102 converts power between DC power in the DC link and AC power, which is the drive power or regenerative power of the driving motor 3. An example of the inverter 102 is a PWM inverter equipped with a semiconductor switching element therein. The semiconductor switching element is formed of, for example, a unipolar transistor such as an FET, a bipolar transistor, an IGBT, a thyristor, a GTO, or the like, but the type of the semiconductor switching element itself does not limit this embodiment, and other semiconductor switching elements may also be used.

[0019] The motor control unit 10 generates drive commands for controlling the on / off of each semiconductor switching element of the inverter 102 and outputs these to the inverter 102. The motor control unit 10 controls the power conversion operation of the inverter 102 based on the rotational speed (speed feedback) of the driving motor 3 detected by the position detector 16, the current (current feedback) flowing in the power line between the inverter 102 and the driving motor 3 detected by the measurement unit 14, a predetermined torque command, and an operation program for the driving motor 3. The speed, torque, or rotor position of the driving motor 3 is controlled based on the AC power supplied from the inverter 102. Note that the configuration of the motor control unit 10 described here is merely an example, and the configuration of the motor control unit 10 may be specified using terms such as a position command generator, a position control unit, a speed control unit, a current control unit, and a torque command creation unit.

[0020] The storage unit 11 stores predetermined parameters for the registered motor. The storage unit 11 may be configured with an electrically erasable and recordable nonvolatile memory such as an EEPROM (registered trademark), or a high-speed read / write random access memory such as a DRAM or an SRAM. The parameters may be rewritten as necessary even after they have been stored in the storage unit 11. The parameters include motor parameters for the registered motor, such as mechanical friction T f [kgm 2 ], back electromotive force coefficient K v [Vsec / rad], motor winding resistance value R m[Ω], number of motor poles p, motor inductance L m [H] and rotor moment of inertia J [kgm 2 The storage unit 11 also stores, as dynamic braking circuit parameters related to the dynamic braking circuit 12, the value R of the dynamic braking resistance 21. DB [Ω] is also stored.

[0021] The dynamic braking (DB) circuit 12 has a dynamic braking resistor 21 and a switch 22 connected in series with the dynamic braking resistor 21. As shown in the figure, a series circuit consisting of the dynamic braking resistor 21 and the switch 22 is provided between the input terminals of the driving motor 3 (between the phases of the windings of the driving motor 3). The switch 22 is composed of a relay, a semiconductor switching element, or the like, and its on / off switching is controlled by a brake command (on / off command) generated by a brake control unit 17 (described below). When braking the driving motor 3 using the dynamic braking circuit 12, the supply of drive power from the inverter 102 to the driving motor 3 is interrupted, and the brake control unit 17 outputs an on command as a brake command, turning on the switch 22 in the dynamic braking circuit 12 and shorting the input terminals of the driving motor 3 via the dynamic braking resistor 21. At this time, even though the driving motor 3 is electrically disconnected from the power supply, a field magnetic flux exists, and the driving motor 3, rotating by inertia, functions as a generator, so the dynamic braking current generated by this flows into the dynamic braking resistor 21 via the switched-on switch 22, where it is converted into Joule heat and consumed, resulting in a deceleration torque being generated in the driving motor 3. This deceleration torque brakes the driving motor 3, and ultimately the driving motor 3 comes to a stop.

[0022] The calculation unit 13 uses the number of rotations per unit time of the driving motor 3 detected by the position detector 16 at the start of braking by the dynamic braking circuit 12 and the parameters stored in the storage unit 11 to calculate information related to an estimate of the dynamic braking current flowing between the driving motor 3 and the dynamic braking circuit 12 during braking by the dynamic braking circuit 12.

[0023] As a calculation formula used to calculate information related to the estimated value of the dynamic braking current, for example, a formula derived as follows can be used.

[0024] When the switch 22 is turned on to apply braking to the driving motor 3 by the dynamic braking circuit 12, the value of the energy consumption contribution resistance R [Ω] that contributes to the energy consumption for braking the driving motor 3 is calculated by multiplying the value of the motor winding resistance by R m [Ω], the value of the dynamic brake resistor 21 is R DB When [Ω], it is expressed as Equation 1.

[0025]

number

[0026] The back electromotive force constant of the driving motor 3 is K v [Vsec / rad], rotational angular velocity is ω [rad / sec], the number of motor poles is p, and the stator voltage of the first phase of the three phases of the driving motor 3 is e I [V] is expressed as in Equation 2.

[0027]

number

[0028] The current of the first phase of the three phases of the driving motor 3 is i I When [A] is used, the circuit equation of Equation 3 holds.

[0029]

number

[0030] If D is the differential operator, Equation 3 can be expressed as Equation 4.

[0031]

number

[0032] Define Equation 5 as a cofunction with C as a constant.

[0033]

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[0034] However, since Equation 6 holds, i I is a periodic function and C=0.

[0035]

number

[0036] A particular solution is obtained as expressed by Equation 7, with X and Y being constants.

[0037]

number

[0038] By substituting the above particular solution into Equation 3 and comparing the resulting equation with Equation 2, Equations 8 and 9 are obtained.

number

[0039]

number

[0040] Here, X and Y are expressed as in Equation 10 and Equation 11.

[0041]

number

[0042]

number

[0043] Organizing the above formula, the current of the first phase is i I [A] can be expressed as in Equation 12.

[0044]

number

[0045] where θ α is expressed as in Equation 13.

[0046]

number

[0047] Second phase stator voltage e II and current i II , the third phase stator voltage e III and current i III is the stator voltage e of the first phase I and current i I Since the phases are shifted by 2 / 3π and -2 / 3π, the stator power P [W] can be expressed as in Equation 14.

[0048]

number

[0049] Here, the torque constant K t [N·m / Ap] is expressed as in Equation 15.

[0050]

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[0051] cosθ α can be expressed as Equation 16.

[0052]

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[0053] By substituting Equation 15 and Equation 16 into Equation 14, the power P [W] of the stator of the driving motor 3 is obtained as expressed by Equation 17.

[0054]

number

[0055] Since the energy applied to the stator of the driving motor 3 is equal to the energy of the rotor (torque x angle = power x time), Equation 18 holds true. In Equation 18, the torque of the rotor of the driving motor 3 is T [N], and the rotation angle of the rotor is θ [rad].

[0056]

number

[0057] Substituting equation 17 into equation 18 and rearranging it gives equation 19. The rotational angular velocity of the rotor is assumed to be ω [rad / sec].

[0058]

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[0059] The equation of motion of the rotor of the driving motor 3 is expressed by Equation 20.

[0060]

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[0061] Substituting the torque T [N] expressed by Equation 19 into Equation 20 and solving it, Equation 21 is obtained.

[0062]

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[0063] Here, A, B, α, β, δ, and γ are expressed as in Equation 22.

[0064]

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[0065] From the above, equation 23 is obtained.

[0066]

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[0067] By integrating both sides of equation 23 with C1 as the integration constant, equation 24 is obtained.

[0068]

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[0069] In Equation 24, if the time when braking by the dynamic braking circuit 12 starts is t=0 and the rotational angular velocity at this time is ω0 [rad / sec], then the integral constant C1 can be expressed as Equation 25, since ω=ω0 at the numerical initial condition t=0.

[0070]

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[0071] The rotational angular velocity ω0 [rad / sec] of the driving motor 3 at the time when braking by the dynamic braking circuit 12 begins is expressed as shown in Equation 26, using the number of rotations per unit time N0 [rotations / sec] of the driving motor 3 at the time when braking by the dynamic braking circuit 12 begins:

[0072]

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[0073] Substituting Equation 25 into Equation 24 and rearranging it, Equation 27 is obtained.

[0074]

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[0075] In summary, when the time when braking by the dynamic braking circuit 12 starts is set to t=0, the estimated value i of the dynamic braking current flowing between the driving motor 3 and the dynamic braking circuit 12 at each time t is DB (ωt)[A] can be expressed as Equation 28 based on Equation 12. In Equation 28, θ α is expressed by Equation 29.

[0076]

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[0077]

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[0078] Furthermore, the relationship between the rotational angular velocity ω [rad / sec] of the driving motor 3 after braking by the dynamic braking circuit 12 has started and time t can be expressed as Equation 30 based on Equation 27.

[0079]

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[0080] In Equation 30, each constant is expressed by Equation 31.

[0081]

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[0082] Based on Equation 28, the estimated peak value of the dynamic braking current, i DBpeak [A] is obtained.

[0083]

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[0084] Also, the estimated settling time t is the time required from the start of braking by the dynamic braking circuit 12 (t=0) until the rotation speed per unit time of the driving motor 3 falls below a predetermined threshold. set By substituting ω = 0 into Equation 30, [sec] can be expressed as Equation 33. Here, the predetermined threshold is set to a very small value close to 0. When the number of rotations per unit time of the driving motor 3 becomes equal to or less than the predetermined threshold (becomes a value close to 0), it may be considered that this is equivalent to the dynamic braking current becoming a value close to 0.

[0085]

number

[0086] The calculation unit 13 calculates the estimated current peak value i shown in Equation 32 as information about the estimated value of the dynamic braking current generated when braking is performed by the dynamic braking circuit 12, using the number of rotations per unit time of the driving motor 3 detected by the position detector 16 at the start of braking by the dynamic braking circuit 12 and the parameters stored in the storage unit 11. DBpeak [A], the settling time estimate t set[sec], or the estimated value i of the dynamic braking current shown in Equation 28, which shows the current waveform of the estimated value of the dynamic braking current at each time t. DB 3 is a diagram illustrating the current waveform of the estimated value of the dynamic braking current calculated by a calculation unit in a motor drive device according to one embodiment of the present disclosure. In the illustrated example, the estimated value of the dynamic braking current becomes zero 0.668 [sec] after time t = 0, which is the start of braking by the dynamic braking circuit 12, and therefore the settling time estimate t set [sec] is 0.668[sec].

[0087] The above-described formula used to calculate the information related to the estimated value of the dynamic braking current is merely an example, and other formulas may be used to calculate the information related to the estimated value of the dynamic braking current.

[0088] The measurement unit 14 acquires information related to the measured value of the dynamic braking current flowing between the driving motor 3 and the dynamic braking circuit 12 during braking by the dynamic braking circuit 12. A current sensor installed in the power line connecting the driving motor 3 and the dynamic braking circuit 12 sequentially measures the measured value of the dynamic braking current at short time intervals from the start of braking by the dynamic braking circuit 12, and these values ​​are sequentially stored in a memory (not shown) as current waveforms. From the current waveforms stored in the memory, the measurement unit 14 acquires either the peak current value of the measured dynamic braking current, the measured settling time, which is the time required for the number of rotations per unit time of the driving motor 3 from the start of braking by the dynamic braking circuit 12 to fall below a predetermined threshold, or the measured value (current waveform) of the dynamic braking current at each time t. The measurement unit 14 acquires information related to the measured value of the dynamic braking current from t=0, when braking by the dynamic braking circuit 12 begins, until the amplitude of the measured value of the dynamic braking current flowing between the driving motor 3 and the dynamic braking circuit 12 falls below a predetermined amplitude threshold. By setting the amplitude threshold to a minute value close to 0 (zero), it is possible to detect when the driving motor 3 is stopped due to braking of the driving motor 3 by the dynamic braking circuit 12 and the dynamic braking current becomes 0.

[0089] The determination unit 15 determines whether the currently driven motor 3 matches a registered motor based on the comparison result between the information on the estimated value of the dynamic braking current calculated by the calculation unit 13 and the information on the measured value of the dynamic braking current acquired by the measurement unit 14. That is, if the information on the estimated value of the dynamic braking current matches the information on the measured value of the dynamic braking current, the determination unit 15 determines that the currently driven motor 3 matches a registered motor, and if the information on the estimated value of the dynamic braking current does not match the information on the measured value of the dynamic braking current, the determination unit 15 determines that the currently driven motor 3 does not match a registered motor.

[0090] The determination result by the determination unit 15 is sent to a display unit (not shown), which displays the determination result, "The driven motor does not match the registered motor" or "The driven motor matches the registered motor." Examples of display units include a standalone display device, a display device attached to the motor drive device 1, a display device attached to a higher-level control device (not shown), a display device attached to a personal computer or mobile terminal, and light-emitting devices such as LEDs and lamps. For example, if the display unit is composed of a light-emitting device such as an LED or lamp, the light-emitting device will emit light when an alarm is received to notify the worker that "The driven motor does not match the registered motor" or "The driven motor matches the registered motor." For example, the determination result by the determination unit 15 is sent to, for example, an audio device (not shown), which will emit a sound such as a voice, speaker, buzzer, or chime to notify the worker that "The driven motor does not match the registered motor" or "The driven motor matches the registered motor." From the determination result by the determining unit 15, the worker can easily know whether the currently driven motor 3 matches the registered motor or not.

[0091] In addition, the judgment result by the judgment unit 15 is sent to the motor control unit 10, and if the judgment unit 15 determines that the driving motor 3 does not match the registered motor, the motor control unit 10 may control the inverter 102 to stop.

[0092] Thus, according to one embodiment of the present disclosure, it is possible to determine whether the currently driven motor 3 is an unexpected motor (e.g., a motor manufactured by the original manufacturer that differs from the original design specifications even if manufactured by the original manufacturer, or a motor manufactured by a third party) that differs from a registered motor (e.g., a motor that was previously selected at the time of design as a power source for a machine tool, robot, or other machine, or a motor manufactured by the original manufacturer). According to one embodiment of the present disclosure, whether the currently driven motor 3 matches a registered motor is determined in conjunction with the function of the dynamic braking circuit 12 provided in the motor drive device 1 that drives the currently driven motor 3, which makes manufacturing easier and less costly than when determination processing is performed based on ID information assigned to the motor.

[0093] Here, several modes of the determination process by the determination unit 15 will be listed.

[0094] The determination process according to the first embodiment determines whether the currently driven motor 3 matches a registered motor based on the peak current value of the dynamic braking current. The calculation unit 13 calculates the peak current value of the estimated dynamic braking current, for example, according to Equation 32, as information related to the estimated dynamic braking current. The measurement unit 14 acquires the peak current value of the measured dynamic braking current as information related to the measured dynamic braking current. The determination unit 15 determines that the currently driven motor 3 does not match a registered motor if the difference between the peak current value of the estimated dynamic braking current and the peak current value of the measured dynamic braking current is outside a predetermined range, and determines that the currently driven motor 3 matches a registered motor if the difference is within the predetermined range. Here, the predetermined range may be set to, for example, approximately ±30% of the peak current value of the dynamic braking current, but this value is merely an example and other values ​​may also be used. The predetermined range may be stored in a rewritable storage unit (not shown) and rewritable by an external device. Even after the predetermined range is set, it can be changed to an appropriate value as needed.

[0095] The determination process according to the second embodiment determines whether the driven motor 3 matches a registered motor based on the settling time, which is the time required for the rotational speed of the driven motor 3 per unit time from the start of braking by the dynamic braking circuit 12 (t = 0) to fall below a predetermined threshold. The calculation unit 13 calculates, as information related to the estimated value of the dynamic braking current, an estimated settling time, which is the time required for the rotational speed of the driven motor 3 per unit time from the start of braking by the dynamic braking circuit 12 to fall below a predetermined threshold, for example, according to Equation 33. The measurement unit 14 acquires, as information related to the measured value of the dynamic braking current, a measured settling time, which is the time required for the rotational speed of the driven motor 3 per unit time from the start of braking by the dynamic braking circuit 12 to fall below a predetermined threshold. The determination unit 15 determines that the driven motor 3 does not match a registered motor if the difference between the estimated settling time and the measured settling time is outside a predetermined range, and determines that the driven motor 3 matches a registered motor if the difference is within the predetermined range. Here, the predetermined range may be set to, for example, about ±30% of the estimated settling time value, but the numerical values ​​given here are merely examples and other numerical values ​​may be used. Note that the predetermined range may be stored in a rewritable storage unit (not shown) and rewritable by an external device, and even after the predetermined range has been set, it can be changed to an appropriate value as needed.

[0096] The determination process according to the third embodiment determines whether the currently driven motor 3 matches a registered motor based on the current waveform of the dynamic braking current during braking by the dynamic braking circuit 12. The calculation unit 13 calculates the current waveform of the estimated dynamic braking current, for example, according to Equation 28, as information related to the estimated dynamic braking current. The measurement unit 14 acquires the current waveform of the measured dynamic braking current as information related to the measured dynamic braking current. The determination unit 15 compares the difference between the current waveform of the estimated dynamic braking current and the current waveform of the measured dynamic braking current at short time intervals, and determines that the currently driven motor 3 does not match the registered motor if the difference is outside a predetermined range for, for example, several milliseconds. However, if the difference is within the predetermined range for, for example, several milliseconds, the determination unit 15 determines that the currently driven motor 3 matches the registered motor. Here, the predetermined range may be set to, for example, approximately ±30% of the amplitude of the dynamic braking current, but the values ​​given here are merely examples and other values ​​may be used. The above-mentioned predetermined range may be stored in a rewritable memory unit (not shown) and may be rewritable by an external device, and even after the above-mentioned predetermined range has been set, it may be changed to an appropriate value as needed.

[0097] FIG. 2 is a flowchart showing the operation flow of the motor drive device according to one embodiment of the present disclosure.

[0098] While the driving motor 3 is being driven by AC current supplied from the inverter 102 under the control of the motor control unit 10 (step S101), in step S102 the calculation unit 13 and the measurement unit 14 determine whether braking of the driving motor 3 has begun by the dynamic braking circuit 12. The start of braking of the driving motor 3 by the dynamic braking circuit 12 can be determined by the fact that the brake command output from the brake control unit has switched from an OFF command to an ON command. When braking of the driving motor 3 by the dynamic braking circuit 12 has begun, the motor control unit 10 controls the inverter 102 to cut off the supply of drive power to the driving motor 3, and the dynamic braking circuit 12 turns on the switch 22 to short-circuit the input terminals of the driving motor 3 via the dynamic braking resistor 21. The dynamic braking current generated thereby flows into the dynamic braking resistor 21 via the turned-on switch 22 and is converted to Joule heat in the dynamic braking resistor 21 and consumed, resulting in a deceleration torque being generated in the driving motor 3. This deceleration torque brakes the driving motor 3.

[0099] If it is determined in step S102 that the dynamic braking circuit 12 has started braking the driving motor 3, the process proceeds to steps S103 and S105; if it is not determined that the dynamic braking circuit 12 has started braking the driving motor 3, the process returns to step S101.

[0100] In step S103, the calculation unit 13 obtains the parameters stored in the memory unit 11 and obtains the number of rotations per unit time at the start of braking of the driving motor 3 by the dynamic braking circuit 12 from the position detector 16. Next, in step S104, the calculation unit 13 calculates information regarding an estimate of the dynamic braking current flowing between the driving motor 3 and the dynamic braking circuit 12 during braking by the dynamic braking circuit 12, using the number of rotations per unit time of the driving motor 3 detected by the position detector 16 at the start of braking by the dynamic braking circuit 12 and the parameters stored in the memory unit 11. Then, the process proceeds to step S107.

[0101] Meanwhile, in step S105, the measurement unit 14 acquires information about the measured value of the dynamic braking current flowing between the driving motor 3 and the dynamic braking circuit 12 during braking by the dynamic braking circuit 12. Next, in step S106, the measurement unit 14 determines whether the amplitude of the measured value of the dynamic braking current has become equal to or less than a predetermined amplitude threshold. If it is determined that the amplitude of the measured value of the dynamic braking current has become equal to or less than the predetermined amplitude threshold, the process proceeds to step S107; if it is determined that the amplitude of the measured value of the dynamic braking current has not become equal to or less than the predetermined amplitude threshold, the process returns to step S105. By going through steps S105 and S106, the measurement unit 14 acquires information about the measured value of the dynamic braking current from t=0, when braking by the dynamic braking circuit 12 starts, until the amplitude of the measured value of the dynamic braking current flowing between the driving motor 3 and the dynamic braking circuit 12 becomes equal to or less than the predetermined amplitude threshold.

[0102] In step S107, the determination unit 15 determines whether the information relating to the estimated value of the dynamic braking current calculated by the calculation unit 13 matches the information relating to the measured value of the dynamic braking current acquired by the measurement unit 14. If it is determined in step S107 that the information relating to the estimated value of the dynamic braking current matches the information relating to the measured value of the dynamic braking current, then in step S108 the determination unit 15 determines that the currently driven motor matches the registered motor. If it is determined in step S107 that the information relating to the estimated value of the dynamic braking current does not match the information relating to the measured value of the dynamic braking current, then in step S108 the determination unit 15 determines that the currently driven motor does not match the registered motor. The determination result by the determination unit 15 is sent to a display unit (not shown), and the display unit displays the determination result as "The currently driven motor does not match the registered motor" or "The currently driven motor matches the registered motor." Furthermore, for example, if the display unit is configured with a light-emitting device such as an LED or lamp, the light-emitting device will emit light when an alarm is received to notify the worker that "the driving motor does not match the registered motor" or "the driving motor matches the registered motor." Furthermore, for example, the determination result by the determination unit 15 is sent to, for example, an audio device (not shown), which will emit a sound such as a voice, speaker, buzzer, or chime to notify the worker that "the driving motor does not match the registered motor" or "the driving motor matches the registered motor." This allows the worker to easily understand whether the driving motor 3 matches the registered motor.

[0103] If the rotation speed per unit time of the driving motor 3 at the start of braking by the dynamic braking circuit 12 is low, the amplitude of the estimated and measured dynamic braking current will be small and the estimated and measured settling time will also be short, which may reduce the accuracy of the determination process by the determination unit 15. Therefore, after it is determined in step S102 that braking of the driving motor 3 has been started by the dynamic braking circuit 12, a process may be provided to determine whether the rotation speed of the driving motor at the start of braking by the dynamic braking circuit 12 is equal to or greater than a predetermined rotation speed threshold, so that if it is determined that the rotation speed of the driving motor at the start of braking by the dynamic braking circuit 12 is equal to or greater than the predetermined rotation speed threshold, the process proceeds to steps S103 and S105, but if it is not determined that the rotation speed of the driving motor at the start of braking by the dynamic braking circuit 12 is equal to or greater than the predetermined rotation speed threshold, the process simply executes the braking process by the dynamic braking circuit 12 and terminates.

[0104] In addition, among the motor parameters, the rotor moment of inertia J [kgm 2 ] varies depending on the load on the motor, and this may affect the accuracy of the determination process by the determination unit 15. Therefore, after it is determined in step S102 that braking of the driving motor 3 has been started by the dynamic braking circuit 12, the rotor moment of inertia J [kgm 2 ] may be input. The operator may input the rotor moment of inertia J [kgm 2 ] is required, the rotor moment of inertia J [kgm 2 ] is input via an input unit (not shown) and written into the storage unit 11, and then the process proceeds to steps S103 and S105. This makes it possible to further improve the accuracy of the determination by the determination unit 15.

[0105] The motor drive device 1 described above includes an arithmetic processing device (processor). Examples of the arithmetic processing device include an IC, an LSI, a CPU, an MPU, and a DSP. The arithmetic processing device includes a motor control unit 10, a calculation unit 13, a measurement unit 14, a determination unit 15, and a brake control unit 17. Each of these units included in the arithmetic processing device is a functional module implemented by, for example, a computer program executed on the processor. For example, if the motor control unit 10, the calculation unit 13, the measurement unit 14, the determination unit 15, and the brake control unit 17 are implemented in the form of a computer program, the functions of each unit can be realized by operating the arithmetic processing device in accordance with the computer program. The computer programs for executing the processes of the motor control unit 10, the calculation unit 13, the measurement unit 14, the determination unit 15, and the brake control unit 17 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, recorded thereon. Alternatively, the motor control unit 10, the calculation unit 13, the measurement unit 14, the determination unit 15, and the brake control unit 17 may be realized as a semiconductor integrated circuit in which a computer program that realizes the functions of each unit is written. The storage unit 11 may be configured as an electrically erasable and recordable nonvolatile memory such as an EEPROM (registered trademark), or a high-speed read / write random access memory such as a DRAM or an SRAM. [Explanation of symbols]

[0106] 1. Motor drive unit 2 AC power supply 3 Driving motor 10 Motor control unit 11 Storage section 12 Dynamic brake circuit 13 Calculation section 14 Measuring part 15 Judgment section 16 Position detector 17 Brake control unit 21 Dynamic brake resistor 22 Switch 101 Converter 102 Inverter 103 DC link capacitor

Claims

1. A storage unit that stores predefined parameters related to the registered motor; a dynamic braking circuit that generates a deceleration torque in a driving motor by shorting input terminals of the driving motor via a dynamic braking resistor, thereby braking the driving motor; a calculation unit that calculates information regarding an estimated value of the dynamic braking current flowing between the driving motor and the dynamic braking circuit during braking by the dynamic braking circuit, using the rotation speed per unit time of the driving motor at the start of braking by the dynamic braking circuit and the parameters stored in the memory unit; a measurement unit that obtains information regarding a measured value of a dynamic braking current flowing between the driving motor and the dynamic braking circuit during braking by the dynamic braking circuit; a determination unit that determines whether the currently driven motor matches the registered motor based on a comparison result between information about the estimated value of the dynamic braking current and information about the measured value of the dynamic braking current; A motor drive device comprising:

2. 2. The motor drive device according to claim 1, wherein the measurement unit acquires information about the measured value of the dynamic braking current from a time when braking by the dynamic braking circuit starts until an amplitude of the measured value of the dynamic braking current flowing between the driven motor and the dynamic braking circuit becomes equal to or less than a predetermined amplitude threshold.

3. the calculation unit calculates, as information relating to the estimated value of the dynamic braking current, a current peak value of the estimated value; the measurement unit acquires a current peak value of the measured value as information related to the measured value of the dynamic braking current, 3. The motor drive device according to claim 1, wherein the determination unit determines that the currently driven motor does not match the registered motor when a difference between the current peak value of the estimated value and the current peak value of the measured value is outside a predetermined range.

4. the calculation unit calculates, as information regarding the estimated value of the dynamic braking current, an estimated settling time value which is a time required from when braking by the dynamic braking circuit starts until the number of rotations per unit time of the driven motor becomes equal to or less than a predetermined threshold value; and the measurement unit acquires, as information relating to the measured value of the dynamic braking current, a measured settling time which is the time required from when braking by the dynamic braking circuit starts until the number of rotations per unit time of the driven motor becomes equal to or less than a predetermined threshold value, 3. The motor drive device according to claim 1, wherein the determination unit determines that the currently driven motor does not match the registered motor when a difference between the estimated settling time value and the measured settling time value is outside a predetermined range.

5. the calculation unit calculates a current waveform of the estimated value as information related to the estimated value of the dynamic braking current; the measurement unit acquires a current waveform of the measured value as information related to the measured value of the dynamic braking current, 3. The motor drive device according to claim 1, wherein the determination unit determines that the currently driven motor does not match the registered motor when a difference between the current waveform of the estimated value and the current waveform of the measured value is outside a predetermined range.

6. The motor drive device according to any one of claims 1 to 5, wherein the parameters include at least one of mechanical friction, back electromotive force coefficient, motor resistance value, motor pole number, motor inductance, and rotor moment of inertia for the registered motor.

7. 7. The motor drive device according to claim 1, wherein the registered motor is a motor that is registered in advance as a motor that is permitted to be connected to the motor drive device.

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