WO2021255956A1

WO2021255956A1 - Motor control device

Info

Publication number: WO2021255956A1
Application number: PCT/JP2020/040671
Authority: WO
Inventors: 賢治武田; 裕司辻; 英人高田
Original assignee: 株式会社日立産機システム
Priority date: 2020-06-16
Filing date: 2020-10-29
Publication date: 2021-12-23
Also published as: JP7246344B2; JP2021197840A

Abstract

Provided is a motor control device capable of realizing highly accurate abnormality diagnosis. A PWM controller 15 controls a plurality of switching elements in a power converter 2 on the basis of a PWM signal. A current controller 11 acquires an output current value of the power converter 2 at a first interval, and sets a duty ratio of the PWM signal on the basis of a difference between the acquired output current value and a current command value. A current monitor 10 monitors the output current value of the power converter 2 by acquiring the output current value at a second interval different from the first interval.

Description

Motor control device

The present invention relates to a motor control device, for example, to a technique for diagnosing an abnormality.

Japanese Unexamined Patent Publication No. 2019-20278 (Patent Document 1) describes a method for determining an abnormality in a rotating machine system based on a current supplied to the rotating machine. Japanese Unexamined Patent Publication No. 2019-191928 (Patent Document 2) describes a method of estimating a motor speed from a current of a power conversion device and using it for monitoring the speed of the motor within a predetermined safety function operation.

Japanese Unexamined Patent Publication No. 2019-20278 JP-A-2019-191928

In Patent Document 1, an abnormality diagnosis of a rotating machine system is performed by methods such as frequency spectrum analysis of motor current, ringing waveform information at the time of switching of a power converter, and Lissajous graphic analysis using a current sensor mainly used for control. Is shown how to do this. Further, in the same document, when the current sensor region used for control is specified, it is described that it is preferable to perform diagnosis based on the output not used for control, but the specific configuration is specified. And the operation is not shown in particular.

In a power converter, for example, it is common to incorporate PWM (Pulse Width Modulation), which obtains a control pulse for switching by comparing a triangular wave-shaped carrier wave with a modulation wave for control, into a control calculation. At this time, it is known that the detection error due to the current ripple component and noise caused by switching can be reduced by synchronizing the timing of detecting the motor current as the control feedback value with the triangular wave.

Therefore, in Patent Document 1, synchronization with the triangular wave is prioritized as the current detection timing used for control. However, when diagnosing a ringing waveform or the like, it is necessary to capture a finer change than the triangular wave period, and it may be desirable to detect the current asynchronously with the triangular wave. In such a case, the method of Patent Document 1 may make highly accurate abnormality diagnosis difficult.

Further, in Patent Document 2, the current supplied to the motor is measured as the speed monitoring of the deceleration stop operation in the safety function (SS1) specified in the functional safety standard IEC6185-5-2. Although speed monitoring is performed by two diagnostic units, both are performed by the same diagnostic method. For this reason, both diagnostic units may make an erroneous diagnosis at the same time due to common factors such as ambient temperature and electromagnetic noise (that is, cause a so-called common cause failure), which is dangerous for the desired functional safety operation. May cause a malfunction.

The present invention has been made in view of the above, and one of the objects thereof is to provide a motor control device capable of realizing highly accurate abnormality diagnosis.

The above and other objects and novel features of the present invention will become apparent from the description and accompanying drawings herein.

The outline of typical embodiments disclosed in the present application is as follows.

A motor control device according to a typical embodiment of the present invention controls a power converter and a power converter that convert DC power into AC power by switching a plurality of switching elements and supply the AC power to the motor. It is equipped with a controller. The controller includes a PWM controller, a current controller, and a current monitor. The PWM controller controls a plurality of switching elements with PWM signals. The current controller acquires the output current value of the power converter at the first interval, and determines the duty ratio of the PWM signal based on the error between the acquired output current value and the current command value. The current monitor monitors the output current value by acquiring the output current value of the power converter at a second interval different from the first interval.

Among the inventions disclosed in the present application, if the effect obtained by a typical embodiment is briefly explained, highly accurate abnormality diagnosis can be realized.

It is a block diagram which shows the structural example of the motor control apparatus according to Embodiment 1 of this invention. It is a figure which shows an example of the current acquisition timing of the current controller and the current monitor in FIG. It is a flow chart which shows an example of the processing contents corresponding to the current acquisition timing of FIG. It is a flow chart which shows an example of the processing contents corresponding to the current acquisition timing of FIG. It is a flow chart which shows an example of the processing contents corresponding to the current acquisition timing of FIG. It is a flow chart which shows an example of the processing contents corresponding to the current acquisition timing of FIG. It is a flow chart which shows an example of the processing contents corresponding to the current acquisition timing of FIG. It is a block diagram which shows the configuration example which modified the motor control device of FIG. It is a block diagram which shows the structural example of the motor control apparatus according to Embodiment 2 of this invention. It is a block diagram which shows the structural example which modified the motor control device of FIG. It is a flow chart which shows the operation example in the case of performing speed monitoring using the control for diagnosis in FIG. It is a block diagram which shows the structural example of the motor control apparatus according to Embodiment 3 of this invention. It is a block diagram which shows the structural example of the motor control apparatus according to Embodiment 4 of this invention. It is a circuit diagram which shows some structural examples in the motor control apparatus according to Embodiment 5 of this invention. It is a circuit diagram which shows some structural examples in the motor control apparatus according to Embodiment 6 of this invention. It is a circuit diagram which shows the configuration example which modified FIG.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In addition, in all the drawings for explaining the embodiment, the same members are designated by the same reference numerals in principle, and the repeated description thereof will be omitted.

(Embodiment 1)
<Outline of motor control device>
FIG. 1 is a block diagram showing a configuration example of a motor control device according to the first embodiment of the present invention. The motor control device of FIG. 1 includes a controller 1, a DC power supply 5, a power converter 2, a motor 3, an encoder 4, a control current sensor 7, and a monitoring current sensor 8. The DC power supply 5 converts the AC power from the commercial AC power supply 6 into DC power by using, for example, a diode bridge circuit, a boost converter circuit, or the like. However, as the DC power supply 5, a storage battery or the like (not shown) may be used.

The power converter 2 converts the DC power from the DC power source 5 into AC power by switching a plurality of switching elements, and supplies the AC power to the motor 3. Specifically, the power converter 2 is, for example, a three-phase inverter in which six switching elements are connected by a three-phase full bridge. The switching element is, for example, an IGBT (Insulated Gate Bipolar Transistor) or a MOSFET (Metal Oxide Semiconductor Field Effect Transistor) or the like.

The encoder 4 measures the rotational state of the motor 3. The controller 1 controls the power converter 2. The controller 1 includes a servo controller 9, a current monitor 10, a current controller 11, a clock generator 12, a carrier wave generator 13, a memory 14, a PWM controller 15, and an encoder communication unit 16. To prepare for.

The details of the current controller 11 will be described. First, the control current sensor 7 is, for example, a CT (Current Transformer) sensor, a Hall element sensor, a resistance element, or the like, and the output current value of the power converter 2 is used as a current feedback signal (for example, an analog voltage signal) Iu1 or Iw1. Detect as. The current controller 11 acquires the output current value (Iu1, Iw1) at a predetermined acquisition interval (first interval) by using, for example, an analog-digital converter or the like. Subsequently, the current controller 11 extracts the current component of the D-axis and Q-axis by converting the acquired output current values (Iu1, Iw1) into coordinates, and the output current value (Id, Iq) of the D-axis and Q-axis. And separately, the error with the current command value of each axis received from the servo controller 9 is calculated.

After that, the current controller 11 determines the duty ratio of the PWM signal by using PI (proportional / integral) control or the like based on the calculated error. Further, the current controller 11 converts the D-axis and the Q-axis into the U-axis and the V-axis and the W-axis to generate a three-phase control modulation wave that reflects the determined duty ratio and outputs the three-phase control modulation wave to the PWM controller 15. .. The PWM controller 15 generates a three-phase PWM signal by comparing the triangular or serrated carrier Fc generated by the carrier generator 13 with the three-phase control modulated wave from the current controller 11.

The PWM controller 15 controls a plurality of switching elements in the power converter 2 with the generated three-phase PWM signals. As a result, the motor current supplied to the motor 3 is generated, and a series of current feedback control loops are formed. The information of the motor control phase current controller 11 is used in the coordinate conversion and current control, current feedback signals Iu1, Iw1, or obtained from a position feedback signal P _FB.

Next, the details of the servo controller 9 will be described. The position signal of the motor 3 measured by the encoder 4 is input to the servo controller 9 as _{a position feedback signal P FB via the encoder communication unit 16.} The servo controller 9 calculates the motor speed and the motor acceleration from the amount of change in the position feedback signal _PFB , and separately for each command value of the position, speed, and acceleration input from the host device (not shown) or the like. Performs feedback control calculation. Then, the servo controller 9 outputs the current command value obtained from the calculation result to the current controller 11.

After that, as described above, the motor 3 is driven according to the functions of the current controller 11 and the power converter 2, and the encoder 4 measures the driving result to form a feedback control loop for the motor position, speed, and acceleration. To. In this example, the control current sensor 7 is attached only to two phases, the U phase and the W phase, from the viewpoint of reducing the number of current sensors. Since the three-phase motor is driven by a current in a substantially three-phase equilibrium, the V-phase current can be estimated from the sum of the U-phase and W-phase currents. Although a configuration example using a position sensor (encoder 4) is shown here, a position sensorless configuration may be used in which the motor position (and thus the speed and acceleration) is calculated by calculation.

Next, the details of the current monitor 10 will be described. First, the monitoring current sensor 8 is, for example, a CT sensor, a Hall element sensor, a resistance element, or the like. In this example, the output current values of all three phases of the power converter 2 are set to a current monitoring signal (for example, an analog voltage signal). ) Detected as Iud, Ivd, Iw1. In this case, for example, it is possible to detect a current leaking from the sum of all three phases through the stray capacitance of the mechanical system after the motor 3 and diagnose an insulation defect or the like. However, the monitoring current sensor 8 does not necessarily have to detect all three phases, and the phase to be detected may be appropriately selected according to the purpose of diagnosis.

The current monitor 10 uses, for example, an analog-digital converter or the like to obtain the output current value (Id, Ivd, Iw1) of the power converter 2 obtained via the monitoring current sensor 8 at a predetermined acquisition interval (first). The output current value is monitored by acquiring it at intervals of 2). Here, although details will be described later, the acquisition interval (second interval) in the current monitor 10 is different from the acquisition interval (first interval) in the current controller 11.

Then, based on the monitoring result of the current monitor 10, an abnormality diagnosis of the motor control device is performed. As specific diagnostic items for abnormality diagnosis, diagnostic items of a motor control device as shown in Patent Document 1 and diagnostic items such as speed associated with a functional safety function as shown in Patent Document 2 can be used. .. The abnormality diagnosis process can be performed by the current monitor 10 or by a higher-level device (not shown) located above the current monitor 10.

The controller 1 is typically composed of a microcontroller (abbreviated as a microcomputer) in which each part is integrated into one package of parts, an FPGA (Field Programmable Gate Array), or the like. However, the present invention is not limited to this, and the controller 1 can be mounted on an integrated printed circuit board or on a plurality of printed circuit boards after each component is an external component in a package separate from the microcomputer or the like. It may be separated and then connected by wiring or wireless communication. The memory 14 is connected to the servo controller 9 and the current controller 11, and is used as a buffer memory for various operations, for example. As the memory 14, a single memory may be shared by both parts, or a plurality of memories may be divided and used by both parts.

As a specific example, the clock generator 12 is a circuit that generates a clock that is frequency-converted by frequency division or a phase-locked loop (PLL) using the arithmetic clock, in addition to elements that are the basis of the arithmetic clock such as an oscillator and an oscillator. Etc. Normally, such a clock generator 12 is built in the microcomputer. The servo controller 9, the current monitor 10, the current controller 11, and the carrier wave generator 13 operate in synchronization with the clock from the clock generator 12. Further, the current controller 11 also operates in synchronization with the carrier wave generated by the carrier wave generator 13.

The encoder communication unit 16 is composed of a communication interface circuit built in a microcomputer or the like. The carrier wave generator 13 and the PWM controller 15 are mainly configured by using a timer circuit or the like. The servo controller 9, the current monitor 10, and the current controller 11 are mainly configured by program processing using a CPU (Central Processing Unit) or the like. However, each part is not limited to such a form, and may be appropriately configured by hardware, software, or a combination thereof.

<Details of current monitor>
FIG. 2 is a diagram showing an example of current acquisition timing of the current controller and the current monitor in FIG. 1. In FIG. 2, first, the carrier wave generator 13 generates a triangular wave-shaped carrier wave 13a having a fixed period Tsw by using a counter, a timer, or the like operating at a clock period Tc from the clock generator 12. In this example, the counter or the like operates so that the count value repeats rising and falling within a predetermined range (for example, 0x0000 to 0xffff).

Further, the carrier wave generator 13 is a triangular wave having the same phase and amplitude as the carrier wave 13a, and generates a carrier wave 13b having an offset with respect to the carrier wave 13a. The PWM controller 15 compares the modulated wave 11o output by the current controller 11 with the

carrier waves

13a and 13b, respectively, and switches the toggle output at the time points tnb, tfb, tna, and tfa where the two intersect, so that the PWM signals PH, PL To generate.

The PWM signals PH and PL are provided with a predetermined dead time, and this section is adjusted by the above-mentioned offset amount. Further, the PWM signal PH corresponds to the switching element on the upper arm side in the power converter 2, and the PWM signal PL corresponds to the switching element on the lower arm side in the power converter 2. The PWM controller 15 switches and controls the switching element of each arm by the PWM signals PH and PL. As a result, the power converter 2 can output a voltage proportional to the modulated wave 11o.

As a result of the pulsed voltage from the power converter 2 being applied to the load, the output current generated in the power converter 2 has a waveform corresponding to the impedance of the load. When the motor 3 is used as a load, it is known that the output current has a waveform in which a sinusoidal fundamental wave corresponding to the number of revolutions and a harmonic component including a pulse wave component are superimposed. On the other hand, as the current used for the control feedback of the power converter 2, it is desirable to use a current in which harmonic noise is removed as much as possible in order to stabilize the control system.

For that purpose, the current controller 11 that bears the control system may acquire the current at the time points tp1 and tp2 when the waveforms of the

carrier waves

13a and 13b are at the top or bottom. Since these time points are at the center of the on / off width of the PWM signals PH and PL, they are not easily affected by noise originating from the edge of each PWM signal, and can avoid aliasing of the current ripple that occurs in the switching cycle Tsw. can. As described above, the timing at which the current controller 11 acquires the output current values Iu1 and Iw1 may be approximately the timing TA shown in FIG. 2 or the thinning out thereof.

Here, in Patent Document 1, as a diagnostic method for a rotating machine system, methods such as frequency spectrum analysis of motor current, ringing waveform information at the time of switching of a power converter, and Lissajous graphic analysis are mentioned. For example, for ringing waveform information, time-series noise currents starting from the edges of the PWM signals PH and PL are diagnostic targets. Therefore, the noise component may not be detected by the output current values (Iu1, Iw1) acquired by the interval (period) Tsc associated with the timing TA.

Therefore, in the embodiment, as shown in the timings TB to TE, the current monitor 10 has a current monitoring signal from the monitoring current sensor 8 at intervals (cycles) Tse and Tsr different from the intervals (period) Tsc. (Output current value) Acquires Iud, Ivd, and Iwd. In the timing TB, the current monitor 10 constantly acquires the output current value (Id, Ivd, Iwd) at an interval Tse shorter than the interval Tsc. This makes it possible to diagnose various motor current waveforms including ringing waveforms.

In the timing TC, the current monitor 10 continuously acquires the output current value (Id, Ivd, Iwd) a predetermined number of times (n) at an interval Tse shorter than the interval Tsc after the predetermined monitoring trigger is established. The monitoring trigger is a rising edge or a falling edge of the PWM signals PH and PL, and in this example, it is a rising edge of the PWM signal PH. In this case, in particular, abnormality diagnosis based on the ringing waveform becomes possible. Further, when the timing TC is used, the calculation load related to the current acquisition can be reduced and the required capacity of the memory 14 can be reduced as compared with the case where the timing TB is used.

In the timing TD, the current monitor 10 has an interval Tse shorter than the interval Tsc, and the output current value (non-overlapping period) is different from the period in which the current controller 11 acquires the output current value (Iu1, Iw1). Iud, Ivd, Iwd) is acquired. As a result, it is possible to acquire a motor current waveform almost the same as in the case of the timing TB, reduce the calculation load of the current monitor 10 due to the overlapping period, reduce the capacity of the memory 14, and the like.

In the timing TE, the current monitor 10 acquires the output current value (Id, Ivd, Iwd) at an interval Tsr randomly determined in time series so as not to depend on the acquisition interval of the current controller 11. In this case, in particular, abnormality diagnosis based on Lissajous figure analysis or the like becomes possible. In the timing TB to TE, the case where the acquisition interval (Tse, Tsr) in the current monitor 10 is shorter than the acquisition interval (Tsc) in the current controller 11 is mainly taken as an example. However, depending on the diagnostic item, the acquisition interval (Tse, Tsr) may be longer than the acquisition interval (Tsc).

Further, in FIG. 1, it is desirable that the current controller 11 acquires an output current value that does not include noise, as described above. Therefore, for example, the current controller 11 obtains the output current value through a low-pass filter or the like, or performs a process of sampling the output current value a predetermined number of times and then averaging the output current value. As a result, the acquisition period of the current per time is effectively extended. On the other hand, since it is desirable for the current monitor 10 to acquire the output current value including noise, the output current value is acquired without going through a low-pass filter or the like. As a result, the acquisition period of the current per time is effectively shortened. In other words, the cutoff frequency of the transfer function of the path in which the current monitor 10 acquires the output current value is higher than the cutoff frequency of the transfer function in the path in which the current controller 11 acquires the output current value. In FIG. 2, such a difference in the acquisition period of the current per time is schematically shown.

As described above, by providing the current monitor 10 that acquires the output current value at an interval (cycle) different from that of the control system, it becomes possible to realize the abnormality diagnosis of the motor control device with high accuracy. Further, in the example of FIG. 1, a monitoring system (that is, a monitoring current sensor 8 and a current monitor 10) is provided separately from the control system (that is, the control current sensor 7 and the current controller 11). By completely separating the control system and the monitoring system in this way, the possibility of a so-called common cause failure is reduced, and functional safety can be contributed.

3A, 3B, 3C, 3D, and 3E are flow charts showing an example of processing contents corresponding to the current acquisition timing of FIG. The processes of FIGS. 3A, 3B, 3C, 3D, and 3E are repeatedly executed, for example, at the clock period Tc of FIG. FIG. 3A shows an example of the processing content corresponding to the timing TA of FIG. In FIG. 3A, the current controller 11 determines whether the ascending / descending flag is ascending or descending (step S101). If the ascending / descending flag is raised, the current controller 11 increments the counter (13a) (step S102), and then determines whether or not the count value is equal to or higher than the upper limit peak (0xffff) (step S103).

If the count value is equal to or greater than the upper limit peak in step S103, the current controller 11 starts analog-to-digital conversion (step S104), changes the ascending / descending flag to descending, and ends the process (step S105). On the other hand, if the count value is less than the upper limit peak in step S103, the current controller 11 ends the process. By repeatedly executing such processing, current acquisition is performed at the top of the carrier wave 13a. On the other hand, when the ascending / descending flag is lowered in step S101, the current controller 11 executes the same processing as in the case of steps S102 to S105 in steps S106 to S109 in the form of decrementing the counter (13a). As a result, current acquisition is performed at the bottom of the carrier wave 13a.

FIG. 3B shows an example of the processing content corresponding to the timing TB of FIG. In FIG. 3B, the current monitor 10 increments the counter (step S201), and whether or not the count value B is equal to or greater than a predetermined upper limit value (B_lim) (that is, the time corresponding to the interval Tse in FIG. 2 has elapsed). Whether or not) is determined (step S202). When the count value B is equal to or greater than the upper limit value (B_lim), the current monitor 10 starts analog-to-digital conversion (step S203), resets the count value B to zero, and ends the process (step S204). On the other hand, when the count value B is less than the upper limit value (B_lim) in step S202, the current monitor 10 ends the process.

FIG. 3C shows an example of the processing content corresponding to the timing TC of FIG. In FIG. 3B, the initial monitoring flag is set to '0', and the current monitor 10 waits for the monitoring trigger to be established (steps S301 and S302). At this time, the current monitor 10 determines whether or not the monitoring trigger is established based on, for example, the PWM signals PH and PL from the PWM controller 15. When the monitoring trigger is established, the current monitor 10 changes the monitoring flag to '1', sets i = 1, and proceeds to the process of step S305 (steps S303 and S304). When the monitoring flag is '1', the current monitor 10 proceeds to the process of step S305 as it is (step S301).

In step S305, when i is n or less, the current monitor 10 performs analog-to-digital conversion at each interval Tse using the same processing as in the case of FIG. 3B (steps S201 to S204). However, unlike the case of FIG. 3B, the current monitor 10 increments i each time the analog-to-digital conversion is performed (step S307). On the other hand, when i exceeds n in step S305, the current monitor 10 returns the monitoring flag to '0' and ends the process (step S306).

FIG. 3D shows an example of the processing content corresponding to the timing TD of FIG. FIG. 3D shows the same processing content as in the case of FIG. 3A. However, unlike the case of FIG. 3A, the processes of steps S104 and S108 are not performed. Further, unlike the case of FIG. 3A, when the count value is less than the upper limit peak (0xffff) in step S103, or when the count value is larger than the lower limit peak (0x0000) in step S107, the current monitor 10 is shown in FIG. The process of 3B is executed (step S401).

Here, in steps S104 and S108 of FIG. 3A, the current controller 11 stores the output current values (Iu1, Iw1) after analog-to-digital conversion in the memory 14, and in step S401 of FIG. 3D, the current monitor 10 May store the output current values (Id, Ivd, Iwd) after analog-to-digital conversion in the memory 14. The current monitor 10 can obtain a continuous output current value based on the output current value stored in the memory 14. Further, since the time-duplicate data does not have to be stored in the memory 14, it is possible to contribute to the reduction of the capacity of the memory 14.

FIG. 3E shows an example of the processing content corresponding to the timing TE of FIG. In FIG. 3E, the current monitor 10 increments the counter (step S501), and whether or not the count value C is equal to or greater than a predetermined upper limit value (C_lim) (that is, the time corresponding to the interval Tsr in FIG. 2 has elapsed). Whether or not) is determined (step S502). When the count value C is equal to or greater than the upper limit value (C_lim), the current monitor 10 starts analog-digital conversion (step S503), updates the upper limit value (C_lim) using a random number generator or the like, and ends the process. (Step S504). On the other hand, when the count value C is less than the upper limit value (C_lim) in step S502, the current monitor 10 ends the process. When FIG. 3E is used, the number of measurements per unit time is smaller than that when FIG. 3B is used, so that the capacity of the memory 14 can be reduced.

Note that the start of analog-digital conversion in FIGS. 3A to 3E corresponds to, for example, the sampling timing of the analog-digital converter. As another form, a form in which the current sensor (7, 8) outputs analog information via a Δ-Σ conversion element instead of an analog signal can be considered. In this case, the analog information is sequentially stored in the memory 14 via the serial communication driver (not shown) in the controller 1. The start of the analog-to-digital conversion in FIGS. 3A to 3E corresponds to the access timing to the memory 14 by the current monitor 10 and the current controller 11. In this case, the access timings of the current monitor 10 and the current controller 11 are set to different multiples of the communication cycle of the Δ—Σ conversion element, respectively.

<Modification example of motor control device>
FIG. 4 is a block diagram showing a configuration example in which the motor control device of FIG. 1 is modified. The motor control device shown in FIG. 4 is not provided with the monitoring current sensor 8 as compared with the configuration example of FIG. 1, and the control current sensor 7 is shared by the current monitor 10 and the current controller 11. ing. In this case, the current monitoring signals (output current value) Iud and Iwd and the current feedback signals (output current value) Iu1 and Iw1 have the same signal source, but the current monitoring device 10 and the current controller 11 have output currents. The intervals at which the values are obtained are different.

By using such a configuration example, highly accurate abnormality diagnosis can be realized as in the case of using the configuration example of FIG. In addition, the cost associated with the current sensor can be reduced as compared with the configuration example of FIG. However, from the viewpoint of functional safety, the configuration example of FIG. 1, which is a form in which the current sensor is separated, is useful.

<Main effect of Embodiment 1>
As described above, by using the motor control device of the first embodiment, the current acquisition interval for control and the current acquisition interval for abnormality diagnosis can be separated, and the timing suitable for each of control and abnormality diagnosis can be set. It will be possible to determine individually. As a result, typically, highly accurate abnormality diagnosis can be realized. Further, by separately providing the current monitor 10 and the current controller 11, and further separately providing the control current sensor 7 and the monitoring current sensor 8, it is possible to obtain a configuration that contributes to functional safety. For example, it is possible to determine the presence or absence of an abnormality by comparing the output current values acquired by the two systems.

Further, for example, in the method of Patent Document 1, it is conceivable to acquire the current at an interval that is a common multiple of the current acquisition interval required for control and the current acquisition interval required for abnormality diagnosis. However, in this case, the interval of the common multiple may be shortened, which may lead to an increase in the calculation load and an increase in the required memory capacity. When the method of the first embodiment is used, the above-mentioned effects can be obtained while suppressing such an increase in the calculation load and the memory capacity.

(Embodiment 2)
<Structure of motor control device>
FIG. 5 is a block diagram showing a configuration example of the motor control device according to the second embodiment of the present invention. FIG. 5 shows a configuration example in which the motor 3 has a plurality of windings (two systems in this example). In FIG. 5, two systems of

controllers

1A and 1B,

power converters

2A and 2B, and control

current sensors

7A and 7B are provided according to the winding of two systems. The DC power sources 5 connected to the

power converters

2A and 2B may be independent or common. In this example, a common method is used, and the DC sides of the

power converters

2A and 2B are connected in parallel to the DC power supply 5, respectively.

The controller 1A is a master for control, and has all the parts in the controller 1 shown in FIG. On the other hand, the controller 1B is a slave device, and in this example, the servo controller 9, the current monitor 10, and the encoder communication unit 16 are deleted from each unit in the controller 1 shown in FIG. .. The

controllers

1A and 1B are driven by

different clock generators

12A and 12B, respectively. By mounting a clock generator in each controller in this way, for example, when the power converter 2A and the power converter 2B are arranged at positions separated to some extent, a long clock signal wiring becomes unnecessary and the clock is clocked. It is possible to prevent malfunctions caused by signals.

Further, the controller 1A and the controller 1B are configured so that information can be transmitted and received via a communication unit (not shown). The current controller 11 in the controller 1B operates by receiving a signal (specifically, a current command value) from the servo controller 9 in the controller 1A. That is, each current controller 11 in the

controllers

1A and 1B operates based on the same command from the servo controller 9 in the controller 1A. As a result, the

power converters

2A and 2B are controlled to output currents having the same phase and amplitude.

The U-phase output wiring from the power converter 2A and the U-phase output wiring from the power converter 2B are connected to the two U-phase input terminals of the motor 3, respectively. The same applies to the V-phase and W-phase output wirings from the

power converters

2A and 2B. Here, in FIG. 5, the monitoring current sensor 8 is provided in a form common to the master device and the slave device. The monitoring current sensor 8 is a through-type current sensor having a through hole formed therein, and a CT (Current Transformer) sensor, a Hall element sensor, or the like is generally known.

The monitoring current sensor 8 is provided in each of the three phases in this example. The U-phase monitoring current sensor 8 is installed so that the U-phase output wirings from the two

power converters

2A and 2B penetrate through their own through holes. As a result, the U-phase monitoring current sensor 8 uses the combined current value obtained by synthesizing the U-phase output current values of the two

power converters

2A and 2B as the U-phase current monitoring signal (for example, an analog voltage signal) Iud2. Detect as. The same applies to the V phase and the W phase. As a result, the V-phase and W-phase monitoring current sensor 8 obtains the combined current values of the V-phase and W-phase, which are the combined output current values of the V-phase and W-phase of the two

power converters

2A and 2B, respectively. It is detected as V-phase and W-phase current monitoring signals Ivd2 and Iwd2, respectively.

As described above, the current monitor 10 is mounted on the master device which is one of the plurality of

controllers

1A and 1B. The current monitor 10 monitors the combined current value by acquiring the combined current value (Id2, Ivd2, Iwd2) detected by the monitoring current sensor 8 at a predetermined interval (second interval). Further, the current monitor 10 determines the output current value (Iu1A, Iv1A, Iw1A) detected by the control current sensor 7A and the output current value (Iu1B, Iv1B, Iw1B) detected by the control current sensor 7B. By acquiring at a predetermined interval (second interval), the output current values of the two

power converters

2A and 2B are monitored.

In the case of a configuration having a plurality of

power converters

2A and 2B in this way, the slave device can be simplified by providing the current monitor 10 only in the master device instead of providing it in the slave device. Further, as compared with the case where the current monitor 10 of the master unit directly monitors the output current value from the control current sensor 7B of the slave unit and the slave unit transmits the monitoring result to the master unit. The amount of communication between the controller 1B and the controller 1A can be reduced. As a result, it becomes possible to reduce the processing load of the motor control device.

Here, as described above, the

power converters

2A and 2B are controlled to have the same phase and the same amplitude. Along with this, the combined current values (Id2, Ivd2, Iwd2) acquired by the current monitor 10 are the output current values (Iu1A, Iv1A, Iw1A) based on the control current sensor 7A unless there is a disturbance or abnormality in the control system. ), And also doubles the output current value (Iu1B, Iv1B, Iw1B) based on the control current sensor 7B. Therefore, it is possible to perform an abnormality diagnosis based on whether or not such consistency can be obtained.

As an example, it is possible to estimate whether the abnormality extracted in the abnormality diagnosis is derived from an individual power converter or a motor. For example, if the output current values from the control

current sensors

7A and 7B are both normal and the current from the monitoring current sensor 8 is abnormal, it is highly possible that the abnormality is derived from the motor. Further, when some system abnormality occurs in the entire system including the load device driven by the motor 3, for example, when there is no abnormality in the output current value from the monitoring current sensor 8, the system abnormality is derived from the load device. Is likely to be.

In this case, the output current value from the monitoring current sensor 8 may be transmitted to a higher-level device (not shown) provided above the motor control device, and the higher-level device may perform detailed abnormality diagnosis. The host device is a device that controls the motor control device and the load device, and issues a speed command or the like to the motor control device according to the control sequence of the load device or the like. The host device can perform abnormality diagnosis by collating, for example, the output current value from the monitoring current sensor 8 with the control sequence of the load device.

Note that the controller 1A and the controller 1B are each realized by different microcomputers and the like. However, in some cases, the controller 1A and the controller 1B can be mounted in one microcomputer. Alternatively, it is also possible to configure the PWM controller 15 in the controller 1A to switch and control the power converter 2B with a PWM signal common to the power converter 2A without providing the controller 1B. Further, in the current monitor 10 of FIG. 5, the interval for acquiring the output current value (Iu1A, Iv1A, Iw1A) and the interval for acquiring the output current value (Iu1B, Iv1B, Iw1B) may be different. It is possible.

<Modification example of motor control device>
FIG. 6 is a block diagram showing a configuration example in which the motor control device of FIG. 5 is modified. In FIG. 6, for the sake of simplification of the explanation, only the parts necessary for the explanation are extracted and shown from the parts shown in FIG. In FIG. 6, the control

current sensors

7A and 7B and the monitoring current sensor 8 all detect two phases of U phase and W phase. However, the number of phases to be detected can be appropriately changed depending on the application. In FIG. 6, the major difference from FIG. 5 is that the current monitor 10 is provided in the diagnostic controller 1C, which is different from the plurality of

controllers

1A and 1B. In other words, the current monitor 10 is commonly provided outside the plurality of

controllers

1A and 1B. Along with this, the controller 1A has substantially the same configuration as the controller 1B in FIG.

By using such a configuration, when the winding system is variously changed such as 3 windings and 4 windings, as many controllers as the number of winding systems having the same configuration as the controller 1A (or 1B) are provided. A diagnostic controller 1C (current monitor 10) may be provided in common with these. As a result, expandability when the number of winding systems is changed becomes easy, and for example, management in manufacturing and inspection becomes easy. The

controllers

1A, 1B, and 1C are realized by, for example, individual microcomputers and the like. However, depending on the case, it is possible to realize the

controllers

1A and 1B excluding the diagnostic controller 1C with one microcomputer or the like.

Further, also in the configuration of FIG. 6, it is desirable to mount

individual clock generators

12A and 12C in the

controllers

1A and 1C, respectively, as in the case of FIG. Further, the

controllers

1A, 1B, 1C can communicate with each other, for example, a current command value, a current feedback signal Iu1A, Iw1A, Iu1B, Iw1B, etc. via a communication unit. Here, as the communication unit of the controller 1C for diagnosis, a communication insulation unit 17 that performs communication in a state of being electrically isolated by using an optical type, a magnetic type, or the like may be provided.

<Operation of diagnostic controller>
Here, the diagnostic controller 1C may be used for speed monitoring in functional safety. As a measure for increasing the failure diagnosis rate on the dangerous side in functional safety, it is known to provide a plurality of different monitors and to separate the power supplies of the plurality of monitors to prevent the failure from spreading to the other side. By using the configuration example as shown in FIG. 6, the speed monitor by the

controllers

1A and 1B and the speed monitor by the diagnostic controller 1C can be independently provided. Further, the

controllers

1A and 1B and the diagnostic controller 1C can be electrically separated by the communication insulation unit 17. As a result, a more reliable functional safety system can be constructed.

FIG. 7 is a flow chart showing an operation example when speed monitoring is performed using the diagnostic controller in FIG. In FIG. 7, the diagnostic controller 1C acquires current feedback signals (output current values) Iu1A, Iw1A, Iu1B, Iw1B (steps S601 and S603), and has a velocity (ω1A) based on the output current values (Iu1A, Iw1A). ) And the speed (ω1B) based on the output current values (Iu1B, Iw1B) (steps S602 and S604).

Further, the diagnostic controller 1C calculates the combined current value of the U phase (Iu1A + Iu1B) and the combined current value of the W phase (Iw1A + Iw1B) based on the current feedback signal (step S605), and the speed based on the combined current value. (Ω1) is calculated (step S606). Further, the diagnostic controller 1C acquires the current monitoring signals (output current values) Iud2 and Iwd2 (step S607), and calculates the speed (ω1d) based on the current monitoring signals (step S607).

After that, the diagnostic controller 1C determines whether or not the respective velocities (ω1A, ω1B, ω1, ω1d) calculated in steps S602, S604, S606, and S608 are equivalent (step S609). If the speeds of the diagnostic controller 1C are the same in step S609 and the speeds are within a predetermined range, the process is terminated with no abnormality (step S610). On the other hand, the diagnostic controller 1C stops the motor 3 as having an abnormality when the speeds in step S609 are not the same or when the speeds are the same but out of the predetermined range (steps S610 and S611). ..

<Main effects of Embodiment 2>
As described above, by using the motor control device of the second embodiment, even when the motor has a plurality of windings, the same effects as the various effects described in the first embodiment can be obtained. In particular, by configuring so that the output current values of the

power converters

2A and 2B and the combined current value obtained by synthesizing the output current values of the

power converters

2A and 2B can be obtained, the consistency of the current values can be improved. It becomes possible to perform an abnormality diagnosis based on this.

(Embodiment 3)
<Structure of motor control device>
FIG. 8 is a block diagram showing a configuration example of the motor control device according to the third embodiment of the present invention. The motor control device shown in FIG. 8 has a different configuration of the monitoring current sensor 8 as compared with the configuration example of FIG. That is, each of the control

current sensors

7A and 7B detects the output current values of two of the three phases (U phase and W phase in this example) as in the case of FIG. 6, and the monitoring current sensor 8 detects the output current values. , Unlike the case of FIG. 6, the combined current value of the remaining 1 phase (V phase) in the 3 phases is detected.

Since the three-phase motor 3 is substantially three-phase balanced, the total of the output current values (Iu1A, Iw1A, Iu1B, Iw1B) detected by the control

current sensors

7A and 7B is the monitoring current unless there is a particular abnormality. It matches the output current value (Ivd2) detected by the sensor 8. Therefore, even by using such a configuration, it is possible to realize an abnormality diagnosis based on the consistency of the current values and an abnormality diagnosis based on the matching of the speeds, as in the case of the second embodiment. Then, such an abnormality diagnosis can be realized after reducing the number of phases of the monitoring current sensor 8.

(Embodiment 4)
<Structure of motor control device>
FIG. 9 is a block diagram showing a configuration example of the motor control device according to the fourth embodiment of the present invention. The motor control device shown in FIG. 9 is not provided with the monitoring current sensor 8 as compared with the configuration example of FIG. 6, and the current monitoring device 10 in the controller 1C is from the control

current sensors

7A and 7B. It differs from the point that the output current value (Iu1A, Iu1B) of the U phase is directly acquired.

For example, in the functional safety speed monitoring as described in FIG. 7, when the speed is obtained from the zero cross period of the current, the speed can be calculated from the current value of one of the three phases. Therefore, it is possible to realize a part of the speed monitoring as shown in FIG. 7 by using the configuration example of FIG. Specifically, the controller 1C of FIG. 9 has a speed based on the U-phase output current value (Iu1A) from the control current sensor 7A and a U-phase output current value (Iu1B) from the control current sensor 7B. Can be compared with the speed based on.

(Embodiment 5)
<Structure of motor control device>
FIG. 10 is a circuit diagram showing a part of a configuration example in the motor control device according to the fifth embodiment of the present invention. In FIG. 10, for example, instead of the monitoring current sensor 8 shown in FIG. 5, a current collecting unit 18 is provided so as to straddle the

controllers

1A and 1B. The current consolidating unit 18 includes an adder composed of an operational amplifier circuit. The adder adds the current feedback signals (for example, analog voltage signals) Iu1A, Iw1A, Iu1B, and Iw1B, which are the detection signals from the plurality of

current sensors

7A and 7B, in analog for each phase, and the current monitoring signal for each phase (combined current). Value) Output to the current monitor 10 as Iud and Iwd.

Further, each detection signal (Iu1A, Iw1A, Iu1B, Iw1B) from the plurality of

current sensors

7A and 7B is composed of a series resistor Rf and a capacitor Cf in the subsequent stage in a path different from that on the current aggregation unit 18 side. It is output to the

current controllers

11A and 11B via the low-pass filter. At this time, the low-pass filter filters the detection signal and outputs it to the

current controllers

11A and 11B, such as removing a high-frequency switching noise component from the detection signal (Iu1A, Iw1A, Iu1B, Iw1B).

The adder in the current aggregation unit 18 is composed of operational amplifiers OPu and OPw, an input resistor R1 and a feedback resistor R2. The U-phase detection signals (Iu1A, Iu1B) from the control

current sensors

7A and 7B are wired or connected via the input resistors R1 provided in each and are input to the operational amplifier OPu. Similarly, the W phase detection signals (Iw1A, Iw1B) from the control

current sensors

7A and 7B are wired or connected via different input resistors R1 and input to the operational amplifier OPw.

As a result, the two common mode current waveforms are added in analog for each phase. As described above, since the

power converters

2A and 2B (not shown) of the plurality of systems operate according to the current command values having the same amplitude phase, the output of the operational amplifier also has a substantially sinusoidal waveform having the same phase as the input. Here, the path through which the current monitor 10 acquires the output current value is called a monitoring path, and the path through which the

current controllers

11A and 11B acquire the output current value is called a control path. In the configuration example of FIG. 10, the cutoff frequency of the transfer function of the monitoring path (that is, the cutoff frequency of the current aggregation unit 18) is higher than the cutoff frequency of the transfer function of the control path (that is, the cutoff frequency of the low-pass filter).

As shown in FIG. 10, each input resistor R1 and the control

current sensors

7A and 7B may be directly connected to each other via a circuit having an insulating / amplifying function such as an insulating amplifier. May be connected to. Further, the operational amplifiers OPu and OPw are mounted only on the controller 1A which is a master device, and the controller 1B which is a slave device mounts only the input resistor R1. Then, each input resistor R1 is connected to each other by a parallel bus connection (wired or connection) by wiring between a master and a slave. This can contribute to the miniaturization of the slave device. Further, by providing two or more connectors for each slave unit, it is possible to connect a large number of slave units in parallel bus wiring.

<Main effects of Embodiment 5>
As described above, by using the motor control device of the fifth embodiment, the same effect as that of the second embodiment can be obtained without using the penetration type current sensor (monitoring current sensor 8) as shown in FIG. 5 and the like. can get. That is, it can contribute to the miniaturization and cost reduction of the system. Further, the cutoff frequency of the current aggregation unit 18 is higher than the cutoff frequency of the low-pass filter. This makes it possible for the current monitor 10 to acquire a current value including a high frequency component, which is required for, for example, analysis of a ringing waveform or Lissajous analysis. As a result, more accurate abnormality diagnosis can be realized without damaging the high frequency component.

(Embodiment 6)
<Structure of motor control device>
FIG. 11 is a circuit diagram showing a part of a configuration example in the motor control device according to the sixth embodiment of the present invention. FIG. 11 shows that the configuration of the current collecting unit 18 is slightly different from that of the configuration example of FIG. The current aggregation unit 18 of FIG. 11 includes a plurality of rectifiers (DH1, DL1, DH2, DL2) and an amplifier circuit (in this example, operational amplifiers OPu and OPw).

Each of the plurality of rectifiers is composed of a diode bridge including four diodes DH1, DL1, DH2, DL2. The plurality of (here, four) rectifiers rectify the detection signals (Iu1A, Iw1A, Iu1B, Iw1B) of each phase from the plurality of control

current sensors

7A and 7B, respectively. When the control

current sensors

7A and 7B output a substantially sinusoidal detection signal proportional to the current value, each of the plurality of rectifiers performs full-wave rectification by a diode bridge. Further, in the output nodes (positive terminal and negative terminal) of the plurality of rectifiers, the positive terminal and the negative terminal are commonly connected to each other for each phase.

The operational amplifier OPu receives the signal from the U-phase common output node in the plurality of rectifiers as the non-inverting input and the inverting input, and outputs the U-phase current monitoring signal Iud to the current monitor 10. Similarly, the operational amplifier OPw receives the signal from the common output node of the W phase in the plurality of rectifiers as the non-inverting input and the inverting input, and outputs the W-phase current monitoring signal Iwd to the current monitor 10.

Due to the action of the diode bridge, only the signal having the largest instantaneous amplitude among the positive and negative detection signals from the control

current sensors

7A and 7B is typically applied to the inputs of the operational amplifiers OPu and OPw. Become. As described above, since the

power converters

2A and 2B (not shown) of multiple systems operate according to the current command values having the same amplitude phase, the outputs of the operational amplifiers OPu and OPw are substantially sinusoidal full-wave rectified waveforms. Become.

Since the instantaneous values of the current monitoring signals Iud and Iwd obtained by the above configuration are representative values of each current sensor, they may be inferior to the configuration example of FIG. 10 from the viewpoint of obtaining the amplitude information of the motor current. However, the speed of the motor 3 can be obtained by detecting the zero cross of the current monitoring signals Iud and Iwd. Therefore, for example, it can be applied when performing speed monitoring or the like in functional safety as described in FIG. 7. Further, since the maximum worst value of the amplitude can be obtained as the amplitude information of the motor current, it is possible to perform an abnormality diagnosis based on the current value depending on the diagnosis item.

FIG. 12 is a circuit diagram showing a configuration example obtained by modifying FIG. 11. FIG. 12 shows a configuration example in which the reference common potential side of the in-phase current sensor is connected in parallel to the plurality of rectifiers (diode bridges) in FIG. 11 and connected to the midpoint of the common diode trains DH2 and DL2. .. The signal potential side of the current sensor is connected to the midpoint of the diode trains DH1 and DL1 provided for each current sensor, and the potentials across the diode trains DH1 and DL1 are input to the operational amplifiers OPu and OPw provided for each phase. The point that they are commonly connected in parallel is the same as in FIG. The current monitoring signals Iud and Iwd have a full-wave rectified waveform in the configuration example of FIG. 11, whereas they have a substantially sinusoidal waveform with positive and negative peaks in the configuration example of FIG. 12. By using the configuration example of FIG. 12, it is possible to perform speed monitoring in functional safety and abnormality diagnosis based on the current value, as in the case of FIG. 11.

<Main effects of Embodiment 6>
As described above, even by using the motor control device of the sixth embodiment, the same effect as that of the fifth embodiment can be obtained. That is, the penetration type current sensor (monitoring current sensor 8) becomes unnecessary, which can contribute to the miniaturization and cost reduction of the system. Further, the cutoff frequency of the current aggregation unit 18 is higher than the cutoff frequency of the low-pass filter. This makes it possible for the current monitor 10 to acquire a current value including a high frequency component, which is required for, for example, analysis of a ringing waveform or Lissajous analysis. As a result, more accurate abnormality diagnosis can be realized without damaging the high frequency component.

Although the invention made by the present inventor has been specifically described above based on the embodiment, the present invention is not limited to the above embodiment and can be variously modified without departing from the gist thereof. For example, the above-described embodiments have been described in detail in order to explain the present invention in an easy-to-understand manner, and are not necessarily limited to those having all the described configurations. Further, it is possible to replace a part of the configuration of one embodiment with the configuration of another embodiment, and it is also possible to add the configuration of another embodiment to the configuration of one embodiment. .. Further, it is possible to add / delete / replace a part of the configuration of each embodiment with another configuration.

1 ... controller, 2 ... power converter, 3 ... motor, 7 ... control current sensor, 8 ... monitoring current sensor, 10 ... current monitor, 11 ... current controller, 15 ... PWM controller, 18 ... current Aggregator, Iu1, Iv1, Iw1 ... Current feedback signal (output current value), Iud, Ivd, Iwd ... Current monitoring signal (output current value), OP ... Optics, Tsc, Tse, Tsr ... Interval (cycle)

Claims

A power converter that converts DC power into AC power by switching multiple switching elements and supplies the AC power to the motor.
A controller that controls the power converter and
It is a motor control device equipped with
The controller
A PWM controller that controls the plurality of switching elements with PWM signals,
A current controller that acquires the output current value of the power converter at the first interval and determines the duty ratio of the PWM signal based on the error between the acquired output current value and the current command value.
A current monitor that monitors the output current value by acquiring the output current value of the power converter at a second interval different from the first interval, and
Have,
Motor control device.
In the motor control device according to claim 1,
The motor has multiple windings
A plurality of the power converters are provided according to the plurality of windings.
The current monitor monitors the output current value of each of the plurality of power converters.
Motor control device.
In the motor control device according to claim 2,
A plurality of the controllers are provided according to the plurality of power converters.
Each of the plurality of controllers has the PWM controller and the current controller.
The current monitor is provided in any one of the plurality of controllers.
Motor control device.
In the motor control device according to claim 2,
A plurality of the controllers are provided according to the plurality of power converters.
Each of the plurality of controllers has the PWM controller and the current controller.
The current monitor is commonly provided outside the plurality of controllers.
Motor control device.
In the motor control device according to claim 2,
A plurality of current sensors installed in a plurality of output wirings from the plurality of power converters and detecting the output current values of the plurality of power converters, respectively.
A through hole is formed, and the plurality of output wirings from the plurality of power converters are installed so as to penetrate the through hole, so that a combined current obtained by synthesizing the output current values of the plurality of power converters. A penetration type current sensor that detects the value, and
Have,
The current monitor monitors the combined current value detected by the through-type current sensor in addition to the output current value detected by each of the plurality of current sensors.
Motor control device.
The motor control device according to claim 5.
The motor is a three-phase motor.
Each of the plurality of current sensors detects the output current value of two of the three phases.
The through-type current sensor detects the combined current value of the remaining one of the three phases.
Motor control device.
In the motor control device according to claim 2,
A plurality of current sensors installed in a plurality of output wirings from the plurality of power converters and detecting the output current values of the plurality of power converters, respectively.
A plurality of low-pass filters that filter the detection signals from the plurality of current sensors and output them to the current controller.
An adder that is composed of an operational amplifier circuit, analog-adds detection signals from the plurality of current sensors, and outputs the detection signals to the current monitor.
Have,
Motor control device.
In the motor control device according to claim 2,
A plurality of current sensors installed in a plurality of output wirings from the plurality of power converters and detecting the output current values of the plurality of power converters, respectively.
A plurality of low-pass filters that filter the detection signals from the plurality of current sensors and output them to the current controller.
A plurality of rectifiers that rectify the detection signals from the plurality of current sensors and connect the output nodes in common,
An amplifier circuit that receives signals from the output nodes of the plurality of rectifiers and outputs them to the current monitor.
Have,
Motor control device.
In the motor control device according to claim 1 or 2.
The second interval is shorter than the first interval,
Motor control device.
In the motor control device according to claim 1 or 2.
The cutoff frequency of the transfer function of the path from which the current monitor acquires the output current value is higher than the cutoff frequency of the transfer function of the path from which the current controller acquires the output current value. ..
In the motor control device according to claim 1 or 2.
After the monitoring trigger is established, the current monitor continuously acquires the output current value a predetermined number of times at the second interval.
The monitoring trigger is a motor control device which is an rising edge or a falling edge of the PWM signal.
In the motor control device according to claim 1 or 2.
The current monitor acquires the output current value in a period different from the period in which the current controller acquires the output current value.
Motor control device.
In the motor control device according to claim 1 or 2.
The second interval is randomly determined in chronological order.
Motor control device.