Motor device, wiper device, and motor control method

Abstract

To reduce the number of times of operation stop caused by sudden reduction in number of rotations.SOLUTION: A motor device comprises: a motor which performs rotational driving; a drive signal generation unit which controls a duty ratio indicating a drive output of the motor in such a manner that the duty ratio does not exceed a duty ratio upper limit and which generates a drive signal which corresponds to the duty ratio; an inverter which outputs an output signal for rotationally driving the motor on the basis of the drive signal; a number of rotations detection unit which detects the number of rotations of the motor; an acceleration detection unit which detects whether or not the motor is in acceleration; and an upper limit setting unit which, when the rotation of the motor is accelerated, changes the duty ratio upper limit to a second upper limit higher than a preliminarily set first upper limit.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a motor device, a wiper device, and a motor control method. [Background technology]

[0002] In recent years, motor devices used in vehicle wiper devices and the like have been known to have a function of limiting the motor's output duty according to the motor's rotation speed in order to protect the magnet from demagnetization and prevent overcurrent (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 2019-43203 Summary of the Invention [Problem to be solved by the invention]

[0004] However, when the above-mentioned motor device is used in a wiper device, for example, if a sudden load such as a strong wind or falling snow is applied to the wiper blade while the motor is operating and the motor rotation speed drops, the above-mentioned output duty limiting function will be activated, stopping the motor operation and preventing it from immediately returning to normal operation.

[0005] The present invention has been made to solve the above problems, and its purpose is to provide a motor device, a wiper device, and a motor control method that can reduce operation stoppages due to a sudden drop in rotation speed. [Means for solving the problem]

[0006] In order to solve the above problems, one aspect of the present invention is a motor that is driven to rotate; a drive signal generation unit that controls a duty ratio that indicates a drive output of the motor so that the duty ratio does not exceed an upper duty ratio limit value and generates a drive signal corresponding to the duty ratio; an inverter that outputs an output signal that drives the motor to rotate based on the drive signal; and a rotation speed detection unit that detects the rotation speed of the motor. When the motor is accelerating The motor is accelerating Being Detect and detecting that the motor is decelerating or is not accelerating when rotating at a constant speed. and an upper limit value setting unit that sets the duty ratio upper limit value to a predetermined first upper limit value when the rotation of the motor is not accelerating, and changes the duty ratio upper limit value to a second upper limit value higher than the first upper limit value when the rotation of the motor is accelerating.

[0007] Another aspect of the present invention is a motor control method for controlling a motor that is rotationally driven by an output signal output from an inverter based on a drive signal, the method comprising: a drive signal generation step in which a drive signal generation unit controls a duty ratio indicating a drive output of the motor so as not to exceed a duty ratio upper limit value, and generates the drive signal according to the duty ratio; a rotation speed detection step in which a rotation speed detection unit detects the rotation speed of the motor; and an acceleration detection step in which: an acceleration detection step of detecting that the motor is accelerating when the motor is accelerating, and detecting that the motor is not accelerating when the motor is decelerating or rotating at a constant speed; and an upper limit value setting unit The motor control method includes an upper limit value setting step of setting the duty ratio upper limit value to a predetermined first upper limit value when the rotation of the motor is not accelerating, and changing the duty ratio upper limit value to a second upper limit value higher than the first upper limit value when the rotation of the motor is accelerating. [Effects of the Invention]

[0008] According to the present invention, it is possible to reduce the occurrence of operation stoppages due to a sudden drop in rotation speed. [Brief explanation of the drawings]

[0009] [Figure 1] 1 is a block diagram showing an example of a motor device according to a first embodiment. [Figure 2]5 is a flowchart showing an example of a process for switching a duty limit value of the motor device according to the first embodiment. [Figure 3] 5A and 5B are diagrams illustrating an example of a switching operation of a duty limit value of the motor device according to the first embodiment. [Figure 4] FIG. 1 is a diagram illustrating the operation of a duty limit value in the prior art. [Figure 5] FIG. 4 is a diagram illustrating an example of an operation related to a duty limit value of the motor device according to the first embodiment. [Figure 6] 5A and 5B are diagrams illustrating an example of operation when there is no function to disable the process of changing the duty limit value of the motor device according to the first embodiment. [Figure 7] 10A and 10B are diagrams illustrating an example of operation when a function for disabling the process of changing the duty limit value of the motor device according to the first embodiment is provided. [Figure 8] FIG. 6 is a configuration diagram illustrating an example of a wiper device according to a second embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0010] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A motor device, a wiper device, and a motor control method according to an embodiment of the present invention will be described below with reference to the accompanying drawings. [First embodiment] FIG. 1 is a block diagram showing an example of a motor device 100 according to a first embodiment. As shown in FIG. 1, the motor device 100 includes a motor 2, a rotation axis sensor 30, a control unit 40, and an inverter 50. The motor device 100 according to this embodiment is used, for example, in a wiper device that wipes the window glass of a vehicle.

[0011] The motor 2 is, for example, a three-phase, four-pole brushless motor. The motor 2 is driven to rotate by an output signal output from an inverter 50 based on a drive signal, which will be described later. The motor 2 also includes a stator 21 and a rotor 22.

[0012] The stator 21 is fixed to the inner periphery of the case of the motor 2. The stator 21 includes three-phase armature coils (21u, 21v, 21w). The armature coils (21u, 21v, 21w) are wound around the stator 21. For example, the three-phase armature coils (21u, 21v, 21w) are connected by a delta connection.

[0013] In the delta connection, the armature coil 21u and the armature coil 21w are connected by the connection point 21a, the armature coil 21v and the armature coil 21w are connected by the connection point 21b, and the armature coil 21u and the armature coil 21v are connected by the connection point 21c.

[0014] The rotor 22 is provided inside the stator 21. The rotor 22 includes, for example, a rotor shaft 22a and a four-pole permanent magnet 22b attached to the rotor shaft 22a. A plurality of bearings (not shown) are provided inside the case of the motor 2, and the rotor shaft 22a is rotatably supported by the plurality of bearings.

[0015] The rotational shaft sensor 30 detects a signal corresponding to the rotation of the rotor 22. The rotational shaft sensor 30 includes, for example, three Hall ICs (not shown). When the rotor 22 rotates, these three Hall ICs output pulse signals that are shifted in phase by 120 degrees to the control unit 40. That is, as the rotor 22 rotates, the rotational shaft sensor 30 generates pulse signals based on changes in the magnetic poles of a sensor magnet (not shown) arranged on the rotor shaft 22a, and outputs the pulse signals to the control unit 40. Each Hall IC detects a position that is shifted by 120 electrical degrees.

[0016] The control unit 40 is a processor including, for example, a CPU (Central Processing Unit) and performs overall control of the motor device 100. The control unit 40 performs PWM (Pulse Width Modulation) control, sets a duty ratio according to a target rotation output of the rotor 22 (for example, a target rotation speed TRPM), and outputs a drive signal according to the set duty ratio to the inverter 50. The control unit 40 also controls the drive of the motor 2 via the inverter 50, for example, by supplying rectangular wave current. The control unit 40 also includes a position detection unit 41, a rotation speed detection unit 42, an acceleration detection unit 43, an upper limit setting unit 44, a command generation unit 45, and a drive signal generation unit 46.

[0017] The position detection unit 41 detects the rotational position (θ) of the rotor 22 based on the pulse signal supplied from the rotational axis sensor 30. The position detection unit 41 outputs the detected rotational position of the rotor 22 to a drive signal generation unit 46, which will be described later.

[0018] The rotation speed detection unit 42 detects, for example, the rotation speed (RPM) of the motor 2 (rotor 22) based on the pulse signal supplied from the rotation axis sensor 30, and outputs the detected rotation speed of the motor 2 (rotor 22) to the acceleration detection unit 43, upper limit value setting unit 44, and command generation unit 45 described later. In this specification, the term "number of rotations" refers to the "rotational speed" which indicates the number of rotations per unit time.

[0019] The acceleration detection unit 43 detects whether the rotation of the motor 2 is accelerating. For example, the acceleration detection unit 43 detects that the motor 2 is accelerating when the rotation speed detected by the rotation speed detection unit 42 at predetermined time intervals increases a predetermined number of times in succession. The acceleration detection unit 43 outputs the detection result of whether the motor 2 is accelerating or not to the upper limit setting unit 44.

[0020] The upper limit value setting unit 44 sets a duty limit value (duty ratio upper limit value) that is the upper limit value of the duty ratio (also called output duty) that indicates the drive output of the motor 2. The duty limit value includes a normal duty limit value (first upper limit value) that is set in advance, and a corrected duty limit value (second upper limit value) that is used during acceleration of the motor 2, and the upper limit value setting unit 44 switches between and outputs the normal duty limit value (first upper limit value) and the corrected duty limit value (second upper limit value).

[0021] The normal duty limit value is a limit value used during normal operation other than during acceleration. The upper limit value setting unit 44 changes and sets the normal duty limit value according to the rotation speed of the motor 2 (hereinafter sometimes referred to as the motor rotation speed). For example, the upper limit value setting unit 44 changes the normal duty limit value to a higher value as the rotation speed increases, and changes the normal duty limit value to a lower value as the rotation speed decreases. Specifically, the upper limit value setting unit 44 changes the normal duty limit value according to the motor rotation speed, as shown in FIG. 3, which will be described later.

[0022] The upper limit setting unit 44 keeps the normal duty limit value constant at a minimum value when the motor rotation speed is lower than a first threshold value, and keeps the normal duty limit value constant at a maximum value when the motor rotation speed is higher than a second threshold value. The second threshold value is higher than the first threshold value. Furthermore, the upper limit setting unit 44 changes the normal duty limit value in accordance with the motor rotation speed when the motor rotation speed is between the first threshold value and the second threshold value. In Figures 3 and 5 described below, the first threshold value and the rotation speed threshold value (RPMth) described below are set to the same value, but the present invention is not limited to this, and the first threshold value may be set to a value smaller than the rotation speed threshold value.

[0023] Furthermore, when the rotation of the motor 2 is accelerating, the upper limit value setting unit 44 changes the duty limit value to a corrected duty limit value that is higher than a preset normal duty limit value. The upper limit value setting unit 44 switches between and outputs the normal duty limit value and the corrected duty limit value, for example, depending on the detection result of whether the motor 2 is accelerating or not output from the acceleration detection unit 43. For example, as shown in FIG. 3, which will be described later, the upper limit value setting unit 44 switches from the normal duty limit value (LMT1) to the corrected duty limit value (LMT2) while the motor 2 is accelerating.

[0024] That is, when the motor 2 is accelerating, the upper limit value setting unit 44 outputs the corrected duty limit value (LMT2) as the duty limit value (LMT) to the drive signal generating unit 46. Furthermore, when the motor 2 is not accelerating (when the motor 2 is decelerating or is being driven at a constant speed), the upper limit value setting unit 44 outputs the normal duty limit value (LMT1) as the duty limit value (LMT) to the drive signal generating unit 46.

[0025] The upper limit setting unit 44 sets the corrected duty limit value by adding a correction amount (α) to the normal duty limit value, as shown in the following equation (1), where α is a predetermined fixed value.

[0026] Corrected duty limit value = Normal duty limit value + α (1)

[0027] When a correction amount is generated for the normal duty limit value using equation (1), if the normal duty limit value is changed according to the rotation speed of the motor 2, the correction duty limit value will also be changed according to the rotation speed of the motor 2. In other words, the upper limit value setting unit 44 changes the correction duty limit value according to the rotation speed of the motor 2.

[0028] Furthermore, the upper limit setting unit 44 may change the correction amount depending on the rotation speed, as shown in the following equation (2).

[0029] Corrected duty limit value = Normal duty limit value + α × RPM (2)

[0030] In this case, (α × rotation value) corresponds to the correction value. In this case, the upper limit value setting unit 44 changes the correction amount according to the rotation speed, and as a result, the correction duty limit value changes according to the rotation speed of the motor 2.

[0031] The upper limit value setting unit 44 may also change the correction duty limit value in accordance with the magnitude of the rotational acceleration of the motor 2. In this case, for example, the upper limit value setting unit 44 changes the above-mentioned correction value to a larger value as the rotational acceleration increases.

[0032] Furthermore, the upper limit value setting unit 44 disables the change process of changing from the normal duty limit value to the corrected duty limit value when the rotation speed of the motor 2 is equal to or lower than a threshold value (equal to or lower than the rotation speed threshold value). In other words, when the rotation speed of the motor 2 is low, the upper limit value setting unit 44 performs control to output the normal duty limit value without using the corrected duty limit value even during acceleration.

[0033] The command generating unit 45 generates an output command value (command value for PWM control) according to a target rotation output (for example, target rotation speed TRPM) of the motor 2. The command generating unit 45 generates a duty ratio, which is a command value for PWM control, according to, for example, the current rotation speed (RPM) of the motor 2 acquired from the position detecting unit 41 and the target rotation speed TRPM, and outputs the generated output command value to the drive signal generating unit 46 as an output command value (DT).

[0034] The drive signal generating unit 46 generates drive signals based on the output command value (DT) output by the command generating unit 45 so that sinusoidal wave-shaped voltages are applied to the three-phase armature coils (21u, 21v, 21w) at energization timings according to the rotational position of the rotor 22. The drive signal generating unit 46 generates three-phase energization timing signals based on the rotational position (θ), for example, and generates drive signals (three-phase drive signals) that drive (turn on / off) switching elements (51a to 51f) of the inverter 50 (described later) by PWM control based on the output command value (DT), and outputs the generated drive signals (three-phase drive signals) to the inverter 50.

[0035] Furthermore, when the output command value (DT) has a duty ratio greater than the duty limit value (LMT) output from the upper limit value setting unit 44, the drive signal generating unit 46 generates a drive signal (three-phase drive signal) by PWM control using the duty limit value (LMT) instead of the output command value (DT). In this way, the drive signal generating unit 46 controls the duty ratio indicating the drive output of the motor 2 so that it does not exceed the duty limit value (LMT), and generates a drive signal according to the duty ratio.

[0036] The inverter 50 outputs an output signal that rotates the motor 2 based on the drive signal generated by the drive signal generation unit 46. That is, the inverter 50 drives the switching elements (51a to 51f) based on the drive signal generated by the drive signal generation unit 46, and applies an applied voltage based on a current waveform to the three-phase armature coils (21u, 21v, 21w). The inverter 50 generates an applied voltage using DC power supplied from the battery 3 .

[0037] The inverter 50 includes six switching elements 51a to 51f connected in a three-phase bridge configuration and diodes 52a to 52f. The switching elements 51a to 51f are, for example, N-channel metal oxide semiconductor field effect transistors (MOSFETs), and form a three-phase bridge circuit.

[0038] Switching element 51a and switching element 51d are connected in series between the positive and negative terminals of battery 3 to form a U-phase bridge circuit. Switching element 51a has a drain terminal connected to the positive terminal of battery 3, a source terminal connected to node N1, and a gate terminal connected to the signal line for the upper U-phase drive signal. Switching element 51d has a drain terminal connected to node N1, a source terminal connected to the negative terminal of battery 3, and a gate terminal connected to the signal line for the lower U-phase drive signal. Node N1 is connected to connection point 21a of motor 2.

[0039] Switching element 51b and switching element 51e are connected in series between the positive and negative terminals of battery 3 to form a V-phase bridge circuit. Switching element 51b has a drain terminal connected to the positive terminal of battery 3, a source terminal connected to node N2, and a gate terminal connected to the signal line for the upper V-phase drive signal. Switching element 51e has a drain terminal connected to node N2, a source terminal connected to the negative terminal of battery 3, and a gate terminal connected to the signal line for the lower V-phase drive signal. Node N2 is connected to connection point 21b of motor 2.

[0040] Switching element 51c and switching element 51f are connected in series between the positive and negative terminals of battery 3 to form a W-phase bridge circuit. Switching element 51c has a drain terminal connected to the positive terminal of battery 3, a source terminal connected to node N3, and a gate terminal connected to the signal line for the upper W-phase drive signal. Switching element 51f has a drain terminal connected to node N3, a source terminal connected to the negative terminal of battery 3, and a gate terminal connected to the signal line for the lower W-phase drive signal. Node N3 is connected to connection point 21c of motor 2.

[0041] The diode 52a has an anode terminal connected to the node N1 and a cathode terminal connected to the positive terminal of the battery 3. The diode 52d has an anode terminal connected to the negative terminal of the battery 3 and a cathode terminal connected to the node N1.

[0042] The diode 52b has an anode terminal connected to the node N2 and a cathode terminal connected to the positive terminal of the battery 3. The diode 52e has an anode terminal connected to the negative terminal of the battery 3 and a cathode terminal connected to the node N2.

[0043] The diode 52c has an anode terminal connected to the node N3 and a cathode terminal connected to the positive terminal of the battery 3. The diode 52f has an anode terminal connected to the negative terminal of the battery 3 and a cathode terminal connected to the node N3.

[0044] The battery 3 is a DC power supply such as a lead storage battery or a lithium ion battery, and supplies power to drive the motor 2.

[0045] Next, the operation of the motor device 100 according to this embodiment will be described with reference to the drawings. 2 is a flowchart showing an example of a process for switching the duty limit value of the motor device 100 according to this embodiment. Here, the operation of the upper limit setting unit 44 of the control unit 40 will be described.

[0046] 2, the upper limit setting unit 44 first determines whether the motor rotation speed is greater than the rotation threshold value (step S101). The upper limit setting unit 44 acquires the motor rotation speed RPM detected by the rotation speed detection unit 42, and determines whether the motor rotation speed RPM is greater than the rotation threshold value (whether the motor rotation speed RPM is equal to or less than the rotation threshold value). If the motor rotation speed RPM is greater than the rotation threshold value (step S101: YES), the upper limit setting unit 44 proceeds to step S102. If the motor rotation speed RPM is equal to or less than the rotation threshold value (step S101: NO), the upper limit setting unit 44 proceeds to step S104.

[0047] In step S102, the upper limit setting unit 44 determines whether the motor 2 is accelerating. The upper limit setting unit 44 determines whether the motor 2 is accelerating, for example, based on the detection result output by the acceleration detection unit 43. If the motor 2 is accelerating (step S102: YES), the upper limit setting unit 44 proceeds to step S103. If the motor 2 is not accelerating (step S102: NO), the upper limit setting unit 44 proceeds to step S104.

[0048] In step S103, the upper limit setting unit 44 selects the corrected duty limit value as the duty limit value. That is, the upper limit setting unit 44 outputs the corrected duty limit value as the duty limit value (LMT) to the drive signal generating unit 46. After the processing of step S103, the upper limit setting unit 44 returns the processing to step S101.

[0049] Furthermore, in step S104, the upper limit setting unit 44 selects the normal duty limit value as the duty limit value. That is, the upper limit setting unit 44 outputs the normal duty limit value as the duty limit value (LMT) to the drive signal generating unit 46. After the processing of step S104, the upper limit setting unit 44 returns the processing to step S101.

[0050] Next, the switching operation of the duty limit value of the motor device 100 according to this embodiment will be described with reference to FIG. FIG. 3 is a diagram illustrating an example of the switching operation of the duty limit value of the motor device 100 according to this embodiment.

[0051] In FIG. 3, the horizontal axis represents the rotation angle, and the vertical axis represents the motor rotation speed and output duty. Waveform W1 indicates the motor rotation speed, and waveform W2 indicates the output duty, which is the output command value. Furthermore, dashed line LMT1 indicates the normal duty limit value, and dashed line LMT2 indicates the corrected duty limit value. Furthermore, dashed line RPMth indicates the rotation speed threshold value. 3, it is assumed that the motor 2 is driven at the target rotation speed. In other words, the waveform W1 is the motor rotation speed and also the target rotation speed.

[0052] 3 shows an example of a case where the motor device 100 is operating normally, and the control unit 40 controls the motor 2 to increase the rotation speed from a stopped state to rotate at a predetermined speed, and then decelerate the rotation speed to reduce the rotation speed and stop the motor, as shown in waveform W1. In this case, the command generation unit 45 of the control unit 40 outputs an output command value (DT) as shown in waveform W2.

[0053] The operation of the motor device 100 in Fig. 3 will be described in more detail. First, from point P1 to just before point P2, the motor rotation speed is equal to or less than the rotation speed threshold value (RPMth). In this case, the upper limit value setting unit 44 of the control unit 40 generates a normal duty limit value (LMT1) according to the motor rotation speed. Furthermore, the upper limit value setting unit 44 outputs the normal duty limit value (LMT1) as the duty limit value (LMT).

[0054] Next, from point P2 to just before point P3, the motor rotation speed is greater than the rotation speed threshold (RPMth) and is accelerating. In this case, the upper limit value setting unit 44 switches the duty limit value (LMT) from the normal duty limit value (LMT1) to the corrected duty limit value (LMT2) and outputs it.

[0055] Next, from point P3 to immediately before point P4, the motor rotation speed is greater than the rotation speed threshold (RPMth) and the motor is not accelerating. In this case, the upper limit value setting unit 44 switches the duty limit value (LMT) from the corrected duty limit value (LMT2) to the normal duty limit value (LMT1) and outputs it.

[0056] Furthermore, from point P4 to point P5, the motor rotation speed is equal to or less than the rotation speed threshold (RPMth) and the motor is not accelerating. In this case, the upper limit value setting unit 44 continues to output the normal duty limit value (LMT1) as the duty limit value (LMT).

[0057] In the example shown in FIG. 3, the output command value (DT) indicated by the waveform W2 is lower than the duty limit value (LMT=LMT1 or LMT2), and therefore the drive signal generating unit 46 generates a drive signal (three-phase drive signal) based on the output command value (DT) so that the motor rotation speed changes to the target rotation speed (waveform W1) without being restricted by the duty limit value (LMT).

[0058] Next, with reference to FIGS. 4 and 5, the operation of the motor device 100 according to this embodiment when an unexpected load is applied will be described. For comparison, Fig. 4 is a diagram showing the operation of a conventional motor device when only a normal duty limit value is used as the duty limit value.

[0059] In FIG. 4, the horizontal axis represents the rotation angle, and the vertical axis represents the motor rotation speed and output duty. 4, waveform W10 indicates the target rotation speed, and waveform W11 indicates the motor rotation speed. Waveform W21 indicates the output duty, which is the output command value. Dashed line LMT1 indicates the duty limit value, which is the normal duty limit value. Dashed line RPMth indicates the rotation speed threshold value.

[0060] Furthermore, point P11 indicates the timing when an unexpected load is applied to the motor device of the prior art, and point P13 indicates the timing when the unexpected load on the motor device of the prior art is eliminated or reduced.

[0061] As shown in Figure 4, in a conventional motor device, when a sudden load is applied at point P11, the motor rotation speed shown in waveform W11 falls below the target rotation speed shown in waveform W10. The output duty shown in waveform W21 then increases to raise the motor rotation speed to the target rotation speed. However, if the load on the conventional motor device is heavy, the motor rotation speed may continue to decrease even if the output duty is increased. In such a case, as shown at point P12, the normal duty limit value (LMT1) decreases as the motor rotation speed decreases.

[0062] Next, at point P13, even if the load on the motor device is eliminated or reduced and the conventional motor device temporarily accelerates, the output duty shown in waveform W21 reaches and is limited to the normal duty limit value (LMT1), preventing the motor rotation speed from continuing to increase and causing the motor rotation speed to further decrease. This repeated decrease in the normal duty limit value (LMT1) and the decrease in the motor rotation speed prevents the motor rotation speed from returning to the target rotation speed shown in waveform W10 and stops.

[0063] In contrast to this, FIG. 5 is a diagram showing an example of the operation of the motor device 100 according to this embodiment with respect to the duty limit value. In FIG. 5, the horizontal axis represents the rotation angle, and the vertical axis represents the motor rotation speed and output duty. Furthermore, waveform W10 indicates the target rotation speed, and waveform W12 indicates the motor rotation speed. Furthermore, waveform W22 indicates the output duty, which is the output command value. Furthermore, dashed line LMT1 indicates the normal duty limit value, and dashed line LMT2 indicates the corrected duty limit value. Furthermore, point P23 indicates the timing when an unexpected load is applied to motor device 100. Furthermore, point 25 indicates the timing when the unexpected load on motor device 100 is eliminated or reduced.

[0064] In the example shown in Fig. 5, when a sudden load is applied to motor device 100 at point P23, the motor rotation speed shown in waveform W12 decreases and the output duty shown in waveform W22 increases, similar to the prior art shown in Fig. 4 above. However, in motor device 100 according to this embodiment, as shown from point P25 onwards, upper limit value setting unit 44 switches from duty limit value (LMT) to corrected duty limit value (LMT2) while motor 2 is accelerating. This allows motor device 100 to avoid restrictions imposed by the duty limit value, and as shown in waveform W12, the motor rotation speed can be increased again, allowing normal operation to be restored.

[0065] The operation of motor device 100 in Fig. 5 will be described in more detail. First, from point P21 to just before point P22, the motor rotation speed is equal to or less than the rotation speed threshold value (RPMth). In this case, upper limit value setting unit 44 of control unit 40 generates a normal duty limit value (LMT1) according to the motor rotation speed. Furthermore, upper limit value setting unit 44 outputs the normal duty limit value (LMT1) as the duty limit value (LMT).

[0066] Next, from point P22 to just before point P24, the motor rotation speed is greater than the rotation speed threshold (RPMth) and is accelerating. In this case, the upper limit value setting unit 44 switches the duty limit value (LMT) from the normal duty limit value (LMT1) to the corrected duty limit value (LMT2) and outputs it.

[0067] Here, at point P23, an unexpected load occurs, causing the motor rotation speed to decrease. Therefore, from point P24 to just before point P25, the motor rotation speed is greater than the rotation speed threshold (RPMth) and the motor is not accelerating. In this case, the upper limit value setting unit 44 switches the duty limit value (LMT) from the corrected duty limit value (LMT2) to the normal duty limit value (LMT1) and outputs it.

[0068] Next, at point P25, the load on the motor device 100 is eliminated or reduced, and the motor rotation speed increases. Therefore, from point P25 to just before point P26, the motor rotation speed is equal to or less than the rotation speed threshold value (RPMth) and is accelerating. In this case, the upper limit value setting unit 44 switches the duty limit value (LMT) from the normal duty limit value (LMT1) to the corrected duty limit value (LMT2) and outputs it. This increases the output duty, allowing the motor rotation speed to continue to increase.

[0069] Next, from point 26 to just before point 27, the motor rotation speed is greater than the rotation speed threshold (RPMth) and the motor is not accelerating. In this case, the upper limit value setting unit 44 switches the duty limit value (LMT) from the corrected duty limit value (LMT2) to the normal duty limit value (LMT1) and outputs it.

[0070] Next, from point P27 to point P28, the motor rotation speed is equal to or less than the rotation speed threshold (RPMth) and the motor is not accelerating. In this case, the upper limit value setting unit 44 continues to output the normal duty limit value (LMT1) as the duty limit value (LMT).

[0071] As described above, the motor device 100 according to this embodiment includes the motor 2 that is driven to rotate, a drive signal generator 46, an inverter 50, a rotation speed detector 42, an acceleration detector 43, and an upper limit value setter 44. The drive signal generator 46 controls the duty ratio, which indicates the drive output of the motor, so that it does not exceed the duty ratio upper limit value, and generates a drive signal corresponding to the duty ratio. The inverter 50 outputs an output signal that drives the motor 2 to rotate based on the drive signal. The rotation speed detector 42 detects the rotation speed of the motor 2. The acceleration detector 43 detects whether the motor 2 is accelerating. If the motor rotation is accelerating, the upper limit value setter 44 changes the duty limit value (upper limit value of the duty ratio) to a corrected duty limit value (second upper limit value) that is higher than a preset normal duty limit value (first upper limit value).

[0072] As a result, even when the motor device 100 according to this embodiment is subjected to the above-mentioned sudden load shown in Fig. 5, the corrected duty limit value (second upper limit value) can avoid the output limitation due to the duty limit value, and the motor rotation speed can be increased again (see waveform W12 in Fig. 5). Therefore, the motor device 100 according to this embodiment can reduce operation stoppages due to a sudden drop in rotation speed.

[0073] In addition, in this embodiment, the upper limit value setting unit 44 disables the change process that changes from the normal duty limit value (first upper limit value) to the corrected duty limit value (second upper limit value) when the rotation speed of the motor 2 is below a threshold value (below the rotation speed threshold RPMth).

[0074] As a result, the motor device 100 according to this embodiment can prevent an overcurrent from flowing to the motor 2 when, for example, fluctuations in the motor rotation speed are judged to be acceleration when the motor behavior becomes unstable in the low rotation range, causing the duty limit value (LMT) to increase. Here, the overcurrent suppression effect of the motor device 100 according to this embodiment will be described with reference to Figs. 6 and 7.

[0075] Fig. 6 is a diagram showing an example of the operation of motor device 100 according to this embodiment when there is no function to disable the process of changing the duty limit value. That is, for comparison, Fig. 6 shows an example of the case where upper limit setting unit 44 does not disable the process of changing the duty limit value using the rotation speed threshold RPMth.

[0076] In FIG. 6, the horizontal axis represents time, and the vertical axis represents the motor rotation speed, motor current consumption, and output duty. 6, waveform W3 indicates the duty limit value (LMT), waveform W4 indicates the output command value (DT), waveform W5 indicates the current consumption of motor 2, and waveform W6 indicates the motor rotation speed.

[0077] 6, if the behavior of the motor 2 becomes unstable in the low rotation range (see waveform W6) and the motor 2 temporarily accelerates, the duty limit value change process is activated and the upper limit value setting unit 44 changes the duty limit value (LMT) to the corrected duty limit value. This enables the command generation unit 45 to further increase the output command value (DT), as shown in waveform W4, causing an overcurrent to flow, as shown in waveform W5.

[0078] In contrast to this, Fig. 7 is a diagram showing an example of the operation when there is a function to disable the process of changing the duty limit value of motor device 100 according to this embodiment. That is, for comparison, Fig. 7 shows an example of the case where upper limit value setting unit 44 disables the process of changing the duty limit value using the rotation speed threshold RPMth.

[0079] In FIG. 7, the horizontal axis represents time, and the vertical axis represents the motor rotation speed, motor current consumption, and output duty. 7, waveform W31 indicates the duty limit value (LMT), waveform W41 indicates the output command value (DT), waveform W51 indicates the current consumption of motor 2, and waveform W61 indicates the motor rotation speed. Furthermore, dashed line RPMth indicates the rotation speed threshold.

[0080] 7, even if the behavior of motor 2 becomes unstable in the low rotation range (see waveform W61) and motor 2 temporarily accelerates, the motor rotation speed is below the rotation speed threshold (RPMth), so upper limit setting unit 44 selects the normal duty limit value as the duty limit value. As a result, drive signal generation unit 46 limits the increase in output command value (DT) as shown in waveform W41, and therefore can suppress the occurrence of overcurrent as shown in waveform W51. In this way, the motor device 100 according to this embodiment can prevent an overcurrent from flowing to the motor 2 when, for example, the motor behavior becomes unstable in the low rotation speed range.

[0081] In this embodiment, the upper limit setting unit 44 changes the normal duty limit value (first upper limit value) in multiple stages according to the rotation speed of the motor 2. As a result, the motor device 100 according to this embodiment can appropriately set the duty limit value depending on the state of the rotation speed of the motor 2.

[0082] In this embodiment, the upper limit setting unit 44 changes the corrected duty limit value (second upper limit value) in accordance with the rotation speed of the motor 2. As a result, the motor device 100 according to this embodiment can set the duty limit value more appropriately depending on the state of the rotation speed of the motor 2.

[0083] In this embodiment, the upper limit setting unit 44 may change the corrected duty limit value (second upper limit value) in accordance with the magnitude of the rotation acceleration of the motor 2. As a result, the motor device 100 according to this embodiment can appropriately set the corrected duty limit value (second upper limit value) according to the degree of acceleration, for example, by changing the corrected duty limit value (second upper limit value) more significantly as the rotational acceleration increases.

[0084] Furthermore, the motor control method according to this embodiment is a motor control method for controlling the motor 2, which is driven to rotate by an output signal output from the inverter 50, based on a drive signal, and includes a drive signal generating step, a rotation speed detecting step, an acceleration detecting step, and an upper limit value setting step. In the drive signal generating step, the drive signal generating unit 46 controls the duty ratio indicating the drive output of the motor 2 so that it does not exceed a duty limit value (upper limit value of the duty ratio), and generates a drive signal according to the duty ratio. In the rotation speed detecting step, the rotation speed detecting unit 42 detects the rotation speed of the motor 2. In the acceleration detecting step, the acceleration detecting unit 43 detects whether the motor 2 is accelerating. In the upper limit value setting step, if the rotation of the motor 2 is accelerating, the upper limit value setting unit 44 changes the duty limit value (upper limit value of the duty ratio) to a corrected duty limit value (second upper limit value) that is higher than a preset normal duty limit value (first upper limit value). As a result, the motor control method according to this embodiment has the same effect as the motor device 100 described above, and can reduce operation stoppages due to sudden drops in rotation speed.

[0085] Moreover, the motor control method according to this embodiment further includes an upper limit setting invalidation step in which the upper limit setting unit 44 invalidates the upper limit setting step when the rotation speed of the motor 2 is equal to or less than the threshold value. As a result, the motor control method according to this embodiment can prevent an overcurrent from flowing to motor 2 when, for example, when the motor behavior becomes unstable in the low rotation speed range, the fluctuation in the motor rotation speed is judged to be an acceleration, which would result in an increase in the duty limit value (LMT).

[0086] [Second embodiment] Next, a wiper device 200 according to a second embodiment will be described with reference to the drawings. FIG. 8 is a diagram showing an example of a configuration of a wiper device 200 according to the second embodiment.

[0087] 8, the wiper device 200 performs a wiping operation on the windshield surface of a window glass 10 of a vehicle 1. The wiper device 200 includes a motor device 100, a link mechanism 11, two wiper arms 12, and wiper blades 13 attached to the tip of each wiper arm 12.

[0088] The motor device is the motor device 100 of the first embodiment described above, and a detailed description thereof will be omitted here. The wiper arm 12 is driven to rotate by the motor device 100, and moves along the windshield surface of the window glass 10, performing a wiping operation with the wiper blade 13 attached to the tip thereof. The two wiper arms 12 are connected by a link mechanism 11.

[0089] The wiper blade 13 is provided so as to be pressed against the window glass 10 by the wiper arm 12. The wiper blade 13 includes a blade rubber (not shown) held by a blade holder attached to the tip of the wiper arm 12. When the wiper arm 12 is swung by the motor device 100, the wiper blade 13 reciprocates within a wiping range on the outer surface of the window glass 10, wiping the window glass 10 with the blade rubber (not shown).

[0090] As described above, the wiper device 200 according to this embodiment uses the motor device 100 to cause the wiper members (the wiper arm 12 and the wiper blade 13) to perform a wiping operation on the windshield surface. As a result, the wiper device 200 according to this embodiment has the same effect as the motor device 100 described above, and can reduce operation stoppages due to a sudden drop in rotation speed. Even if the load on the wiper device 200 according to this embodiment increases due to, for example, a sudden strong wind blowing against the wiper members (wiper arm 12 and wiper blade 13), falling snow, or an attempt to wipe away large foreign objects (insects, bird droppings, etc.) that have adhered to the window glass 10, the wiper device 200 can re-accelerate and return to normal wiping operation when the strong wind stops or the snow or foreign objects are removed.

[0091] The present invention is not limited to the above-described embodiments, and can be modified within the scope of the present invention. For example, in the above embodiment, an example was described in which the three-phase armature coils (21u, 21v, 21w) of the motor 2 are connected by a delta connection, but this is not limited to this and other connections such as a star connection may also be used.

[0092] Furthermore, in the above embodiment, an example has been described in which the upper limit value setting unit 44 sets the corrected duty limit value by adding the correction amount (α) to the normal duty limit value, but this is not limiting, and the corrected duty limit value may be set by other methods, such as multiplying the normal duty limit value by a coefficient value.

[0093] Furthermore, in the above embodiment, an example has been described in which the motor device 100 is used in the wiper device 200, but the present invention is not limited to this, and the motor device 100 may be used for other purposes.

[0094] Each of the components of the motor device 100 described above has an internal computer system. A program for realizing the functions of each of the components of the motor device 100 described above may be recorded on a computer-readable recording medium, and the program recorded on the recording medium may be read into a computer system and executed to perform processing in each of the components of the motor device 100 described above. Here, "reading a program recorded on a recording medium into a computer system and executing it" includes installing the program into a computer system. The "computer system" referred to here includes hardware such as an OS and peripheral devices. Furthermore, a "computer system" may include multiple computer devices connected via a network, including communication lines such as the Internet, WAN, LAN, and dedicated lines. Furthermore, a "computer-readable recording medium" refers to portable media such as flexible disks, optical magnetic disks, ROMs, and CD-ROMs, as well as storage devices such as hard disks built into a computer system. Thus, the recording medium storing the program may be a non-transitory recording medium such as a CD-ROM.

[0095] Furthermore, some or all of the above-described functions may be realized as an integrated circuit such as an LSI (Large Scale Integration). Each of the above-described functions may be individually implemented as a processor, or some or all of the functions may be integrated into a processor. Furthermore, the integrated circuit implementation method is not limited to LSI, and may be implemented using a dedicated circuit or a general-purpose processor. Furthermore, if an integrated circuit implementation technology that can replace LSI emerges due to advances in semiconductor technology, an integrated circuit based on that technology may be used. [Explanation of symbols]

[0096] 1...vehicle, 2...motor, 3...battery, 10...window glass, 11...link mechanism, 12...wiper arm, 13...wiper blade, 21...stator, 21u, 21v, 21w...armature coil, 22...rotor, 22a...rotor shaft, 22b...permanent magnet, 30...rotation shaft sensor, 40...control unit, 41...position detection unit, 42...rotation speed detection unit, 43...acceleration detection unit, 44...upper limit value setting unit, 45...command generation unit, 46...drive signal generation unit, 50...inverter, 51, 51a to 51f...switching elements, 52, 52a to 52f...diodes, 100...motor device, 200...wiper device

Claims

1. a motor that rotates the a drive signal generating unit that controls a duty ratio indicating a drive output of the motor so that the duty ratio does not exceed an upper duty ratio limit value, and generates a drive signal according to the duty ratio; an inverter that outputs an output signal for driving the motor to rotate based on the drive signal; a rotation speed detection unit that detects the rotation speed of the motor; an acceleration detection unit that detects that the motor is accelerating when the motor is accelerating, and that detects that the motor is not accelerating when the motor is decelerating or rotating at a constant speed; an upper limit value setting unit that sets the duty cycle upper limit value to a preset first upper limit value when the rotation of the motor is not accelerating, and changes the duty cycle upper limit value to a second upper limit value that is higher than the first upper limit value when the rotation of the motor is accelerating; A motor device comprising:

2. The upper limit value setting unit disables a change process of changing the first upper limit value to the second upper limit value when the rotation speed of the motor is equal to or less than a threshold value. The motor device according to claim 1 .

3. The upper limit setting unit changes the first upper limit in a plurality of stages according to the rotation speed of the motor. The motor device according to claim 1 or 2.

4. The upper limit setting unit changes the second upper limit in accordance with the rotation speed of the motor. The motor device according to any one of claims 1 to 3.

5. The upper limit setting unit changes the second upper limit in accordance with the magnitude of the rotational acceleration of the motor. The motor device according to any one of claims 1 to 3.

6. A motor device according to any one of claims 1 to 4, The motor device is used to cause the wiper member to perform a wiping operation on the windshield surface. Wiper device.

7. A motor control method for controlling a motor that is driven to rotate by an output signal output from an inverter based on a drive signal, comprising: a drive signal generating step in which a drive signal generating unit controls a duty ratio indicating a drive output of the motor so as not to exceed an upper duty ratio upper limit value, and generates the drive signal according to the duty ratio; a rotation speed detection step in which a rotation speed detection unit detects the rotation speed of the motor; an acceleration detection step in which an acceleration detection unit detects that the motor is accelerating when the motor is accelerating, and detects that the motor is not accelerating when the motor is decelerating or rotating at a constant speed; an upper limit setting step in which an upper limit setting unit sets the duty ratio upper limit to a preset first upper limit when the rotation of the motor is not accelerating, and changes the duty ratio upper limit to a second upper limit that is higher than the first upper limit when the rotation of the motor is accelerating; A motor control method comprising:

8. The method further includes an upper limit value setting invalidation step in which the upper limit value setting unit invalidates the upper limit value setting step when the rotation speed of the motor is equal to or less than a threshold value.

8. The motor control method of claim 7.

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