MOTOR DEVICE, WIPER DEVICE, AND MOTOR CONTROL METHOD

Abstract

To reduce occurrence of overcurrent.SOLUTION: A motor device comprises: a motor which performs rotational driving and has a three-phase coil; a rotational frequency detection unit which detects the rotational frequency of the motor; 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, which controls a conduction angle of each phase of the three phases and performs advance angle control for shifting the phase from a reference position, and generates a drive signal depending on the duty ratio; and an inverter which applies an AC current to the three-phase coil on the basis of the drive signal. The drive signal generation unit has an advance angle-conduction angle control unit which changes the conduction angle to be equal to or less than 120 degrees while performing the advance angle control when the duty ratio is equal to or more than the duty ratio upper limit and the rotational frequency of the motor is equal to or less than a predetermined threshold in a state where the conduction angle is set to be equal to or more than 120 degrees.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 are known that have a function of limiting the motor output by an upper limit value of the output duty in order to prevent overcurrent. In addition, in such motor devices, a technology is known that uses wide-angle energization, which sets the energization angle to greater than 120 degrees, in order to improve the motor output (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2018-038203 A Summary of the Invention [Problem to be solved by the invention]

[0004] However, in the conventional motor device as described above, when wide-angle energization is performed, an overcurrent may occur even if the output is suppressed by the upper limit value of the output duty.

[0005] The present invention has been made to solve the above problems, and an object of the present invention is to provide a motor device, a wiper device, and a motor control method that are capable of reducing the occurrence of overcurrent. [Means for solving the problem]

[0006] In order to solve the above problems, one aspect of the present invention is a motor device comprising: a motor having three-phase windings and driven to rotate; a rotation speed detection unit that detects the rotation speed of the motor; a drive signal generation unit that controls a duty ratio indicating a drive output of the motor so that it does not exceed a duty ratio upper limit value, and also controls the conduction angle of each of the three phases and performs advance angle control to shift the phase from a reference position, and generates a drive signal corresponding to the duty ratio; and an inverter that supplies AC current to the three-phase windings based on the drive signal, wherein the drive signal generation unit has an advance angle conduction angle control unit that changes the conduction angle to 120 degrees or less while performing the advance angle control when the duty ratio is equal to or greater than the duty ratio upper limit value and the rotation speed of the motor is equal to or less than a predetermined threshold value when the conduction angle is set to be greater than 120 degrees.

[0007] Moreover, one aspect of the present invention is a motor control method for a motor device including a motor having three-phase windings and driven to rotate, and an inverter that supplies AC current to the three-phase windings based on a drive signal, the method including a rotation speed detection step in which a rotation speed detection unit detects the rotation speed of the motor, and 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, controls the conduction angle of each of the three phases, and performs advance angle control to shift the phase from a reference position, and generates a drive signal according to the duty ratio, and further includes an advance angle conduction angle control step in which, in the drive signal generation step, an advance angle conduction angle control unit of the drive signal generation unit changes the conduction angle to 120 degrees or less while performing the advance angle control when the duty ratio is equal to or greater than the duty ratio upper limit value and the rotation speed of the motor is equal to or less than a predetermined threshold value with the conduction angle set to greater than 120 degrees. Effect of the Invention

[0008] According to the present invention, the occurrence of overcurrent can be reduced. [Brief description of the drawings]

[0009] [Figure 1]1 is a block diagram showing an example of a motor device according to a first embodiment. [Diagram 2] 5 is a flowchart showing an example of a current supply control process of the motor device according to the first embodiment. [Diagram 3] FIG. 11 is a diagram illustrating the operation of a current supply control process according to the prior art. [Figure 4] FIG. 4 is a diagram illustrating an example of the operation of a current supply control process of the motor device according to the first embodiment. [Diagram 5] 5A to 5C are diagrams illustrating the current flowing through the motor when the conduction angle of the motor device according to the first embodiment exceeds 120 degrees. [Figure 6] 4 is a diagram illustrating a current flowing through a motor when a conduction angle of the motor device according to the first embodiment is 120 degrees. FIG. [Figure 7] FIG. 11 is a configuration diagram illustrating an example of a wiper device according to a second embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[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 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 shaft 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 rotationally driven by an output signal (applied voltage) output by 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 circumference 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 a connection point 21a, the armature coil 21v and the armature coil 21w are connected by a connection point 21b, and the armature coil 21u and the armature coil 21v are connected by a 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 rotating shaft sensor 30 detects a signal corresponding to the rotation of the rotor 22. The rotating 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 from each other by 120 degrees to the control unit 40. That is, the rotating shaft sensor 30 generates a pulse signal based on the change in the magnetic pole of a sensor magnet (not shown) arranged on the rotor shaft 22a as the rotor 22 rotates, and outputs the pulse signal to the control unit 40. Each Hall IC detects a position shifted by 120 degrees in electrical angle. Also, each Hall IC is installed with respect to the rotor 22 so that when the output of the inverter 50 is immediately changed at each position where the level of the output signal of each Hall IC changes, that is, at each position where an edge occurs in the output signal, an advance angle of 30 degrees in electrical angle is obtained.

[0016] The inverter 50 is PWM (Pulse Width Modulation) controlled based on a drive signal generated by a drive signal generating unit 43 described later, and applies a voltage to three-phase armature coils (21u, 21v, 21w) of the motor 2. That is, the inverter 50 performs switching operations (conducting / non-conducting) of the switching elements (51a to 51f) based on the drive signal generated by the drive signal generating unit 43, and changes the magnitude (duty ratio), energization period (energization angle), and energization timing (advance angle) of the output voltage applied to the motor 2. Here, the duty ratio represents the ratio of the conductive period of the corresponding switching element in the PWM period.

[0017] The inverter 50 generates an applied voltage from DC power supplied from the battery 3. The battery 3 is a DC power source such as a lead storage battery or a lithium ion battery, and supplies power to drive the motor 2.

[0018] 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.

[0019] The switching element 51a and the switching element 51d are connected in series between the positive terminal and the negative terminal of the battery 3 to form a U-phase bridge circuit. The switching element 51a has a drain terminal connected to the positive terminal of the battery 3, a source terminal connected to a node N1, and a gate terminal connected to a signal line of the upper drive signal of the U-phase. The switching element 51d has a drain terminal connected to the node N1, a source terminal connected to the negative terminal of the battery 3, and a gate terminal connected to a signal line of the lower drive signal of the U-phase. The node N1 is connected to a connection point 21a of the motor 2.

[0020] The switching element 51b and the switching element 51e are connected in series between the positive terminal and the negative terminal of the battery 3 to form a V-phase bridge circuit. The switching element 51b has a drain terminal connected to the positive terminal of the battery 3, a source terminal connected to a node N2, and a gate terminal connected to a signal line of the upper V-phase drive signal. The switching element 51e has a drain terminal connected to the node N2, a source terminal connected to the negative terminal of the battery 3, and a gate terminal connected to a signal line of the lower V-phase drive signal. The node N2 is connected to a connection point 21b of the motor 2.

[0021] The switching element 51c and the switching element 51f are connected in series between the positive terminal and the negative terminal of the battery 3 to form a W-phase bridge circuit. The switching element 51c has a drain terminal connected to the positive terminal of the battery 3, a source terminal connected to a node N3, and a gate terminal connected to a signal line of the upper W-phase drive signal. The switching element 51f has a drain terminal connected to the node N3, a source terminal connected to the negative terminal of the battery 3, and a gate terminal connected to a signal line of the lower W-phase drive signal. The node N3 is connected to a connection point 21c of the motor 2.

[0022] 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.

[0023] 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.

[0024] 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.

[0025] The control unit 40 is, for example, a processor including a CPU (Central Processing Unit) and the like, and performs overall control of the motor device 100. The control unit 40 generates a drive signal corresponding to a target rotation output of the rotor 22 (for example, a target rotation speed TRPM) and outputs the generated drive signal 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, a drive signal generation unit 43, and a storage unit .

[0026] The position detection unit 41 detects the rotational position (θ) of the rotor 22 based on the pulse signal supplied from the rotation shaft sensor 30. The position detection unit 41 outputs the detected rotational position of the rotor 22 to a drive signal generation unit 43 described later.

[0027] 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 rotating shaft sensor 30, and outputs the detected rotation speed (motor rotation speed) of the motor 2 (rotor 22) to the drive signal generation unit 43 described later. In this specification, the term "rotational speed" refers to the number of rotations per unit time.

[0028] The drive signal generating unit 43 controls the output command value, which is the duty ratio (output duty) indicating the drive output of the motor 2, so that it does not exceed a duty limit value (upper duty ratio value), and also controls the conduction angle of each of the three phases and performs advance angle control to shift the phase from a reference position, thereby generating a drive signal according to the output command value (output duty).

[0029] The drive signal generating unit 43 also includes a duty control unit 44 , an upper limit setting unit 45 , an advance conduction angle control unit 46 , and a target rotation speed control unit 47 .

[0030] The target rotation speed control unit 47 refers to a target rotation speed map stored in the storage unit 48 described later, and determines the current target rotation speed (TRPM) of the motor 2 based on the output signals of the position detection unit 41 and the rotation speed detection unit 42. The target rotation speed control unit 47 also outputs an output signal indicating the determined target rotation speed to the duty control unit 44. The target rotation speed control unit 47 may also be configured to change the target rotation speed map to be referred to based on a signal (e.g., a signal requesting high-speed wiping or a signal requesting low-speed wiping) from an external switch 31 (e.g., a wiper switch) provided separately from the motor device 100.

[0031] The duty control unit 44 generates an output command value of a duty ratio according to the target rotation speed determined by the target rotation speed control unit 47. For example, the duty control unit 44 compares the current motor rotation speed obtained from the rotation speed detection unit 42 with the target rotation speed, and calculates an output duty ratio so as to bring the motor rotation speed closer to the target rotation speed. The duty control unit 44 then generates an output command value so as to make the duty ratio equal to or less than a duty limit value described later, and outputs the output command value to the inverter 50.

[0032] The upper limit setting unit 45 sets a duty limit value, which is an upper limit value of the duty ratio, according to the motor rotation speed, and outputs it to the duty control unit 44. The upper limit setting unit 45 sets the duty limit value in multiple stages so that, for example, the higher the motor rotation speed, the higher the duty limit value.

[0033] Lead-angle conduction angle control unit 46 generates output command values ​​for the lead angle and conduction angle of the applied voltage that inverter 50 outputs to motor 2. Lead-angle conduction angle control unit 46 performs lead-angle control and conduction angle control according to a result of comparing the motor rotation speed output from rotation speed detection unit 42 with a plurality of predetermined rotation speed thresholds (first threshold, second threshold) and a result of comparing an output command value of the duty ratio output from duty control unit 44 with a duty limit value output from upper limit setting unit 45, and outputs an output command value to inverter 50.

[0034] Here, advance angle control refers to control in which the timing of energization of the voltage output by the inverter 50 to the motor 2 is intentionally shifted from the reference position, which is the position at which an edge of the output signal of the rotating shaft sensor 30 occurs. For example, in this embodiment, the advance angle is mechanically set to 30 degrees in advance, so that an advance angle of 30 degrees is a state in which advance angle control is not being performed, and an advance angle of 40 degrees and an advance angle of 20 degrees are states in which advance angle control is being performed. Note that control to retard the angle from the reference position, such as an advance angle of 20 degrees, is also included in advance angle control.

[0035] Here, the conduction angle control refers to control of the period during which the same conduction state continues in the conduction of the applied voltage output by the inverter 50 to the motor 2. For example, the advance conduction angle control unit 46 performs control to change the conduction angle to a conduction angle of 120 degrees or less, a conduction angle of 121 degrees or more (wide-angle conduction), etc.

[0036] The advance current angle control unit 46 switches between low-speed current control, high-speed current control, boost control, and wide-angle prohibition control to perform control. Here, the low-speed energization control is energization control when the motor 2 is rotating at a low speed at a rotation speed equal to or lower than a predetermined threshold value (second threshold value), and the advance angle energization angle control unit 46 fixes the energization angle to a predetermined value equal to or lower than 120 degrees and does not perform advance angle control (for example, fixes the mechanical advance angle to 30 degrees).

[0037] The high-speed energization control is an energization control when the output command value (output duty) has not reached the duty limit value and when the motor is rotating at a high speed at a rotation speed greater than a predetermined threshold value (second threshold value), and the advance angle energization angle control unit 46 fixes the energization angle to a predetermined value exceeding 120 degrees and performs advance angle control by fixing the advance angle to the predetermined value.

[0038] The boost control is a current control when the output command value (output duty) reaches the duty limit value and the motor is rotating at a high speed with a rotation speed greater than a predetermined threshold value (first threshold value), and the advance-angle current-angle control unit 46 performs advance-angle control to change the current-angle by a value exceeding 120 degrees and to change the advance angle. In the boost control, the advance-angle current-angle control unit 46 performs control to change the advance angle and the current-angle according to the target rotation speed (TRPM). Specifically, the advance-angle current-angle control unit 46 increases the advance angle and the current-angle as the target rotation speed (specifically, for example, the error between the target rotation speed and the motor rotation speed) increases, thereby increasing the motor rotation speed. The advance-angle current-angle control unit 46 may also perform boost control when the output command value (output duty) reaches the duty limit value and the motor is rotating at a high speed with a rotation speed greater than a predetermined threshold value (first threshold value) and the motor rotation speed is less than the target rotation speed.

[0039] Further, the wide-angle prohibition control is a current control that suppresses an overcurrent, and is a current control when the output command value (output duty) reaches the duty limit value and the motor rotates at a rotation speed between the boost control and the low-speed current control (a rotation speed greater than the second threshold and less than the first threshold). In the wide-angle prohibition control, the advance angle current control unit 46 changes the current angle to a fixed value of 120 degrees or less and performs advance angle control. Here, if the advance angle is increased when the motor rotation speed is low, there is a risk that the motor position detection accuracy will decrease. Therefore, in the wide-angle prohibition control, the advance angle current control unit 46 of the present embodiment may perform advance angle control to set the advance angle to a fixed value in a direction smaller than that of the high-speed current control or the boost control, for example, by shifting the mechanical advance angle of 30 degrees to an advance angle of 0 degrees. This makes it possible to suppress a decrease in the detection accuracy of the position detection unit 41 even when the motor rotation speed is reduced by the wide-angle prohibition control.

[0040] The above-mentioned first threshold value is a value larger than the second threshold value, and a predetermined value is set so that an overcurrent does not occur (so that the motor drive current does not reach the overcurrent limit value) when the output duty is equal to or greater than the duty limit value and the conduction angle is set to 120 degrees or less.

[0041] The storage unit 48 is configured with, for example, a ROM, and stores in advance a target rotation speed map that indicates the relationship between the target rotation speed and rotation position of the motor 2, a duty limit value, a rotation speed threshold value, and the like.

[0042] 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 current control process of the motor device 100 according to this embodiment. Here, a change process (switching process) of current control by the motor device 100 will be described.

[0043] 2, the advance conduction angle control unit 46 of the motor device 100 first determines whether the motor rotation speed obtained from the rotation speed detection unit 42 is greater than a second threshold value (step S101). If the motor rotation speed is greater than the second threshold value (step S101: YES), the advance conduction angle control unit 46 proceeds to step S102. If the motor rotation speed is equal to or less than the second threshold value (step S101: NO), the advance conduction angle control unit 46 proceeds to step S108.

[0044] In step S102, motor device 100 performs high speed conduction control. In this case, advance conduction angle control unit 46 performs control with advance angle control and with the conduction angle fixed at a predetermined conduction angle of 121 degrees or more.

[0045] Next, the advance conduction angle control unit 46 determines whether the motor rotation speed is greater than the second threshold value (step S103). If the motor rotation speed is greater than the second threshold value (step S103: YES), the advance conduction angle control unit 46 advances the process to step S104. If the motor rotation speed is equal to or less than the second threshold value (step S103: NO), the advance conduction angle control unit 46 advances the process to step S108.

[0046] In step S104, advance conduction angle control unit 46 determines whether the output duty is equal to or greater than the duty limit value. Advance conduction angle control unit 46 acquires the output duty (output command value) generated by duty control unit 44 and the duty limit value set by upper limit setting unit 45, and determines whether the output duty is equal to or greater than the duty limit value. If the output duty is equal to or greater than the duty limit value (step S104: YES), advance conduction angle control unit 46 advances the process to step S105. If the output duty is less than the duty limit value (step S104: NO), advance conduction angle control unit 46 returns the process to step S102.

[0047] In step S105, advance conduction angle control unit 46 determines whether the motor rotation speed is equal to or less than a first threshold. If the motor rotation speed is equal to or less than the first threshold (step S105: YES), advance conduction angle control unit 46 advances the process to step S106. If the motor rotation speed is greater than the first threshold (step S105: NO), advance conduction angle control unit 46 advances the process to step S107.

[0048] In step S106 (control change step), the motor device 100 performs wide angle prohibition control. In this case, the advance conduction angle control unit 46 performs control with advance angle control (e.g., advance angle 0 degrees) and with the conduction angle fixed to a predetermined conduction angle (e.g., 120 degrees) equal to or less than 120 degrees. After the process of step S106, the advance conduction angle control unit 46 returns the process to step S103.

[0049] In step S107, motor device 100 performs boost control. In this case, advance conduction angle control unit 46 variably controls the advance angle and conduction angle in accordance with the target rotation speed with advance angle control and with the conduction angle being 121 degrees or more. After the process of step S107, advance conduction angle control unit 46 returns the process to step S103.

[0050] In step S108, motor device 100 performs low-speed conduction control. In this case, advance conduction angle control unit 46 performs control without advance angle control and with the conduction angle fixed at 120 degrees, for example. After processing in step S108, advance conduction angle control unit 46 returns the process to step S101.

[0051] Next, the influence of an overcurrent in the current control process of the motor device 100 according to this embodiment will be described with reference to FIGS. Fig. 3 is a diagram showing the operation of the current supply control process of the prior art for comparison, and Fig. 4 is a diagram showing an example of the operation of the current supply control process of motor device 100 according to this embodiment.

[0052] The graph in Figure 3 shows the current control process of the conventional technology, with the horizontal axis of the graph showing time and the vertical axis showing the current angle, output duty, rotation speed, and current. Waveform W1 shows the output duty, waveform W2 shows the duty limit value, and waveform W3 shows the motor rotation speed. Waveform W4 shows the current angle, and waveform W5 shows the current flowing through motor 2.

[0053] 4 shows the energization control process of this embodiment, with the horizontal axis of the graph showing time and the vertical axis showing the energization angle, output duty, rotation speed, and current. Waveform W11 shows the output duty, waveform W21 shows the duty limit value, and waveform W31 shows the motor rotation speed. Waveform W41 shows the energization angle, and waveform W51 shows the current flowing through motor 2.

[0054] 3, in period TR1, as the motor rotation speed decreases (see waveform W3), the output duty increases and reaches the duty limit value (see waveforms W1 and W2), and the current flowing to the motor 2 increases (waveform W5). Here, in the conventional current control process, wide-angle current flow with a current angle greater than 120 degrees is maintained during period TR1, so the current flowing to the motor 2 shown in waveform W5 increases during period TR1, indicating that an overcurrent occurs.

[0055] In contrast, in the current control process of this embodiment shown in Fig. 4, in period TR2, as the motor rotation speed decreases (see waveform W3), the output duty increases and reaches the duty limit value (see waveforms W11 and W21), and high-speed current control with a current angle greater than 120 degrees is changed to wide-angle prohibition control with a current angle of 120 degrees. Therefore, in the current control process of this embodiment, in period TR2, the current flowing through motor 2 shown in waveform W51 does not increase as in the prior art (waveform W5) shown in Fig. 3, and no overcurrent occurs.

[0056] 5 and 6, the principle by which the value of the current flowing through the motor 2 can be limited by changing the conduction angle from a wide-angle conduction angle of more than 120 degrees to a conduction angle of 120 degrees or less will be described.

[0057] FIG. 5 is a diagram illustrating the current flowing through the motor 2 when the conduction angle of the motor device 100 according to this embodiment exceeds 120 degrees. As shown in FIG. 5(a), when the conduction angle exceeds 120 degrees, two-phase conduction occurs, and if the resistance of each winding (armature coil 21u, armature coil 21v, armature coil 21w) is “R”, the inter-terminal resistance is (R / 2).

[0058] Moreover, Fig. 5(b) shows the current flowing through the motor 2 in this case (for example, when the conduction angle is 140 degrees). In Fig. 5(b), the horizontal axis of the graph indicates time, and the vertical axis indicates current.

[0059] Moreover, waveform W6 indicates the waveform of the current flowing through motor 2 in this case (for example, when the conduction angle is 140 degrees), and waveform W7 indicates the current limit value that is the criterion for determining an overcurrent. As shown in FIG. 5(b), when the conduction angle is 140 degrees, the motor 2 is in two-phase conduction, and an overcurrent exceeding the waveform W7 occurs (see waveform W6).

[0060] In contrast to this, FIG. 6 is a diagram illustrating the current flowing through motor 2 when the conduction angle of motor device 100 according to this embodiment is 120 degrees. In this case, as shown in Fig. 6(a), the conduction angle is 120 degrees, resulting in three-phase conduction, and if the resistance of each winding (armature coil 21u, armature coil 21v, armature coil 21w) is "R", the inter-terminal resistance is (2R / 3). In other words, when the conduction angle is 120 degrees, the inter-terminal resistance is (4 / 3) = approximately 1.33 times as large as when the conduction angle exceeds 120 degrees. Therefore, the current flowing through the motor 2 due to three-phase conduction is reduced by approximately 25% compared to the current flowing through the motor 2 due to two-phase conduction.

[0061] Moreover, Fig. 6(b) shows the current flowing through the motor 2 in this case (for example, when the conduction angle is 120 degrees). In Fig. 6(b), the horizontal axis of the graph indicates time, and the vertical axis indicates current.

[0062] Moreover, waveform W61 indicates the waveform of the current flowing through motor 2 in this case (for example, when the conduction angle is 120 degrees), and waveform W7 indicates the current limit value that is the criterion for determining an overcurrent. As shown in FIG. 6(b), when the conduction angle is 120 degrees, the motor 2 is in three-phase conduction, and the current is suppressed to a lower level than that of the waveform W7 (see waveform W61).

[0063] As described above, the motor device 100 according to this embodiment includes the motor 2, the rotation speed detection unit 42, the drive signal generation unit 43, and the inverter 50. The motor 2 has three-phase windings (armature coil 21u, armature coil 21v, and armature coil 21w) and is driven to rotate. The rotation speed detection unit 42 detects the rotation speed of the motor 2. The drive signal generation unit 43 controls the output duty (duty ratio), which is an output command value indicating the drive output of the motor 2, so as not to exceed a duty limit value (upper duty ratio value), and controls the conduction angle of each of the three phases and performs advance angle control to shift the phase from a reference position, thereby generating a drive signal according to the output duty. The inverter 50 supplies AC current to the three-phase armature coils (21u, 21v, and 21w) based on the drive signal. The drive signal generating unit 43 has an advance angle control unit 46 that performs advance angle control and changes the conduction angle to 120 degrees or less when the output duty is equal to or greater than a duty limit value and the rotation speed of the motor 2 is equal to or less than a predetermined threshold value (equal to or less than a first threshold value) in a state in which the conduction angle is greater than 120 degrees.

[0064] As a result, the motor device 100 according to this embodiment can reduce the current flowing through the motor 2 by approximately 25% by changing the conduction angle to 120 degrees or less as shown in Figures 5 and 6 described above, and can reduce the occurrence of overcurrent that may occur even when limited by the duty limit value as shown in Figures 3 and 4. Furthermore, because the motor device 100 according to this embodiment can reduce the occurrence of overcurrent, it can reduce demagnetization of the permanent magnet 22b.

[0065] In this embodiment, when the rotation speed of the motor 2 is equal to or less than a second threshold value that is smaller than the first threshold value, which is a predetermined threshold value, the advance conduction angle control unit 46 changes the conduction angle to 120 degrees without performing advance angle control. As a result, the motor device 100 according to this embodiment can appropriately perform control by low-speed energization control during low-speed rotation where the rotation speed of the motor 2 is equal to or lower than the second threshold value.

[0066] In addition, in this embodiment, when the output duty is equal to or greater than the duty limit value and the rotation speed of the motor 2 is greater than a first threshold value, the advance angle control unit 46 changes the conduction angle to be greater than 120 degrees while performing advance angle control, and performs variable control of the advance angle and conduction angle according to the target rotation speed of the motor 2.

[0067] As a result, the motor device 100 according to this embodiment can perform more appropriate control by boost control when more output is required at high revolutions. Also, by performing boost control only when high output is required, deterioration of quietness during normal operation can be suppressed.

[0068] In addition, in this embodiment, the advance conduction angle control unit 46 sets the advance angle when the duty ratio is equal to or greater than the duty limit value and the rotation speed of the motor 2 is equal to or less than the first threshold value to be smaller than the advance angle when the duty ratio is equal to or greater than the duty limit value and the rotation speed of the motor 2 is greater than the first threshold value. As a result, the motor device 100 according to the present embodiment can further reduce the occurrence of overcurrent and suppress deterioration in motor position detection accuracy.

[0069] In this embodiment, the duty limit value is changed according to the rotation speed of the motor 2. As a result, in the motor device 100 according to the present embodiment, the duty limit value is appropriately set in accordance with the rotation speed of the motor 2, making it possible to further reduce the occurrence of overcurrent.

[0070] Moreover, the motor control method according to the present embodiment is a motor control method for a motor device 100 including a motor 2 having three-phase armature coils (21u, 21v, 21w) that is driven to rotate, and an inverter 50 that supplies AC current to the three-phase armature coils (21u, 21v, 21w) based on a drive signal, and includes a rotation speed detection step and a drive signal generation step. In the rotation speed detection step, a rotation speed detection unit 42 detects the rotation speed of the motor. In the drive signal generation step, a drive signal generation unit 43 controls an output duty indicating the drive output of the motor 2 so as not to exceed a duty limit value, and also controls the conduction angle of each of the three phases and performs advance angle control to shift the phase from a reference position, thereby generating a drive signal according to the output duty. Furthermore, in the drive signal generation step, when the advance angle conduction angle control unit 46 of the drive signal generation unit 43 sets the conduction angle to greater than 120 degrees, the output duty is equal to or greater than the duty limit value, and the rotation speed of the motor 2 is equal to or less than a predetermined threshold value (equal to or less than a first threshold value), the advance angle conduction angle control step is included, in which the advance angle conduction angle control unit 46 performs advance angle control while changing the conduction angle to less than 120 degrees.

[0071] As a result, the motor control method according to this embodiment has the effect of being used in conjunction with the motor device 100 described above, and can reduce the occurrence of overcurrent that can occur even when limited by the duty limit value.

[0072] [Second embodiment] Next, a wiper device 200 according to a second embodiment will be described with reference to the drawings. FIG. 7 is a diagram showing an example of a configuration of a wiper device 200 according to the second embodiment.

[0073] 7, the wiper device 200 performs a wiping operation on the window 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 a wiper blade 13 attached to the tip of each wiper arm 12.

[0074] The motor device shown in FIG. 7 is 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 to move over the window surface of the window glass 10, and performs a wiping operation using a wiper blade 13 attached to the tip of the arm. The two wiper arms 12 are connected by a link mechanism 11.

[0075] 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, and wipes the window glass 10 with the blade rubber (not shown).

[0076] 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 the occurrence of overcurrent that can occur even when limited by the duty limit value.

[0077] The present invention is not limited to the above-described embodiments, and can be modified without departing from the spirit 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 may be other connections such as a star connection.

[0078] In addition, in the above embodiment, control using two thresholds, a first threshold and a second threshold of the motor rotation speed, was described, but this is not limited to this, and the motor device 100 may perform control that does not include control of the second threshold.

[0079] In addition, in the above embodiment, an example has been described in which the first and second threshold values ​​of the motor rotation speed are set to predetermined values ​​in advance, but this is not limited to this, and for example, the first and second threshold values ​​may be set according to the current flowing through motor 2. This allows the motor device 100 to appropriately set the first threshold value and appropriately reduce the occurrence of overcurrent while expanding the range of the wide-angle energization control (e.g., high-speed energization control) described above to the limit. In other words, the motor device 100 can appropriately reduce the occurrence of overcurrent without deteriorating the performance of the motor 2 as much as possible.

[0080] In addition, in the above embodiment, an example was described in which the first threshold value and the second threshold value were the motor rotation speed, but this is not limited to this. For example, a current value detection unit may be provided in the motor device 100, and the first threshold value and the second threshold value may be the current value flowing through the motor 2.

[0081] Further, 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.

[0082] Each of the components of the motor device 100 described above has an internal computer system. A program for implementing 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 the Internet, WAN, LAN, dedicated lines, and other communication lines. Furthermore, a "computer-readable recording medium" refers to portable media such as flexible disks, optical magnetic disks, ROMs, and CD-ROMs, and storage devices such as hard disks built into a computer system. In this way, the recording medium storing the program may be a non-transitory recording medium such as a CD-ROM.

[0083] In addition, some or all of the above-mentioned functions may be realized as an integrated circuit such as LSI (Large Scale Integration). Each of the above-mentioned functions may be individually processed, or some or all of the functions may be integrated into a processor. The integrated circuit method is not limited to LSI, and may be realized by a dedicated circuit or a general-purpose processor. In addition, if an integrated circuit technology that can replace LSI appears due to advances in semiconductor technology, an integrated circuit based on that technology may be used. [Explanation of symbols]

[0084] 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...rotary shaft sensor, 31...external switch, 40...control unit, 41...position detection unit, 42...rotation speed detection unit, 43...drive signal generation unit, 44...duty control unit, 45...upper limit value setting unit, 46...advance conduction angle control unit, 47...target rotation speed control unit, 48...storage unit, 50...inverter, 51, 51a to 51f...switching elements, 52, 52a to 52f...diodes, 100...motor device, 200...wiper device

Claims

1. A motor having three-phase windings and rotating; A rotation speed detection unit that detects the rotation speed of the motor; a drive signal generating unit that controls a duty ratio indicating a drive output of the motor so as not to exceed a duty ratio upper limit value, controls a conduction angle of each of the three phases, and performs advance control to shift the phase from a reference position, and generates a drive signal according to the duty ratio; an inverter that supplies AC current to the three-phase windings based on the drive signal; Equipped with The drive signal generating unit and a lead angle control unit that changes the conduction angle to 120 degrees or less while performing the lead angle control when the duty ratio is equal to or greater than the duty ratio upper limit value and the rotation speed of the motor is equal to or less than a predetermined threshold value in a state where the conduction angle is greater than 120 degrees. Motor device.

2. The advance conduction angle control unit changes the conduction angle to 120 degrees without performing the advance angle control when the rotation speed of the motor is equal to or less than a second threshold value that is smaller than the first threshold value, which is the predetermined threshold value. The motor device according to claim 1 .

3. When the duty ratio is equal to or greater than the duty ratio upper limit value and the rotation speed of the motor is greater than the predetermined threshold value, the advance-angle conduction angle control unit changes the conduction angle to a value greater than 120 degrees while performing the advance-angle control, and changes the advance-angle and the conduction angle to be variably controlled in accordance with the target rotation speed of the motor. The motor device according to claim 1 or 2.

4. The advance conduction angle control unit sets an advance angle when the duty ratio is equal to or greater than the duty ratio upper limit value and the rotation speed of the motor is equal to or less than the predetermined threshold value to be smaller than an advance angle when the duty ratio is equal to or greater than the duty ratio upper limit value and the rotation speed of the motor is greater than the predetermined threshold value. The motor device according to any one of claims 1 to 3.

5. The upper limit of the duty ratio is changed according to the rotation speed of the motor. The motor device according to any one of claims 1 to 4.

6. A motor device according to any one of claims 1 to 5, 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 a motor device including a motor having three-phase windings and rotating, and an inverter that supplies AC current to the three-phase windings based on a drive signal, comprising: a rotation speed detection step in which a rotation speed detection unit detects the rotation speed of the motor; 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 a duty ratio upper limit value, controls a conduction angle of each of the three phases, and performs advance angle control to shift the phase from a reference position, thereby generating a drive signal according to the duty ratio; Including, In the drive signal generating step, The method includes a step of changing the conduction angle to 120 degrees or less while performing the advance angle control by an advance conduction angle control unit of the drive signal generation unit when the duty ratio is equal to or greater than the duty ratio upper limit value and the rotation speed of the motor is equal to or less than a predetermined threshold value in a state where the conduction angle is set to be greater than 120 degrees. Motor control methods.

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