Motor device, wiper device, and motor control method

Abstract

To prevent stall of a motor even in a case where a load is applied when the motor is started.SOLUTION: A motor device includes: a motor that is rotationally driven; a rotational speed detection unit that detects a rotational speed of the motor; an acceleration detection unit that detects whether the motor is accelerating or not; and a drive control unit that performs control to switch between a first drive mode in which the motor is driven and a second drive mode in which an output of the motor is higher than that in the first drive mode, and that selects the second drive mode in a case where, when the motor is started, the motor is accelerating and the rotational speed of the motor is smaller than a target value by a predetermined value or more.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 control devices have become known that switch between different drive modes depending on the magnitude of the load, such as a free-flow drive mode in which three-phase current is supplied and a square-wave drive mode in which two-phase current is supplied (see, for example, Patent Document 1). Here, the free-flow drive mode is a three-phase current drive mode in which half of the duty is output to the OFF phase (corresponding to the phase open period, hereinafter sometimes referred to as the free phase) of the three phases, and is a low-output drive mode in which the number of rotations (rotational speed) is lower than in the square-wave drive mode when driven with the same power. In Patent Document 1, drive mode switching control is performed based on an integrated load value, which is a value determined according to the load and is obtained by integrating the load. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2020-48401 Summary of the Invention [Problem to be solved by the invention]

[0004] However, with conventional motor control devices such as those described above, if a high load is present from the beginning of driving, the load has not yet been accumulated, so the motor is driven in a low-output drive mode, and the required duty is high in the three-phase energization free-wheeling drive mode. As a result, with conventional motor control devices, the duty upper limit is more likely to be reached than in the two-phase energization square wave drive mode, and there is a possibility that the duty cannot be increased and the motor will stall.

[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 suppress stalling of the motor even when a load is applied when the motor is started. [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 rotationally driven motor, a rotational speed detection unit that detects the rotational speed of the motor, an acceleration detection unit that detects whether the motor is accelerating, and a drive control unit that controls switching between a first drive mode for driving the motor and a second drive mode in which the output of the motor is higher than that of the first drive mode, and that selects the second drive mode when the motor is accelerating and the rotational speed of the motor is smaller than a target value by a predetermined value or more when the motor is started.

[0007] Another aspect of the present invention is a motor control method for controlling a rotationally driven motor, the motor control method including: a rotational speed detection step in which a rotational speed detection unit detects the rotational speed of the motor; an acceleration detection step in which an acceleration detection unit detects whether the motor is accelerating; and a drive control step in which a first drive mode for driving the motor is controlled to be switched between a first drive mode and a second drive mode in which the output of the motor is higher than that of the first drive mode, and in which, when the motor is starting, the motor is accelerating and the rotational speed of the motor is smaller than a target value by a predetermined value or more, the second drive mode is selected. [Effects of the Invention]

[0008] According to the present invention, stalling of the motor can be suppressed even when a load is applied when the motor is started. [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] FIG. 4 is a diagram showing an example of a square wave drive pattern in the first embodiment. [Figure 3] FIG. 4 is a table summarizing an example of a square wave drive pattern according to the first embodiment. [Figure 4] FIG. 4 is a diagram showing a first example of a freeless drive pattern in the first embodiment. [Figure 5] FIG. 4 is a table summarizing a first example of a freeless drive pattern in the first embodiment. [Figure 6] FIG. 10 is a diagram showing a second example of a freeless drive pattern in the first embodiment. [Figure 7] FIG. 10 is a table summarizing a second example of the freeless drive pattern in the first embodiment. [Figure 8] 5 is a flowchart showing an example of a drive mode switching operation of the motor device according to the first embodiment. [Figure 9] FIG. 10 is a diagram illustrating an example of the operation of a conventional motor device. [Figure 10] FIG. 3 is a diagram illustrating an example of the operation of the motor device according to the first embodiment. [Figure 11] 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.

[0011] [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 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.

[0012] In this embodiment, the control unit 40 and the inverter 50 correspond to a motor control device 150. The motor control device 150 is also connected to a battery 3 and an ECU 4 (Engine Control Unit).

[0013] The motor 2 is, for example, a three-phase, four-pole brushless motor. The motor 2 is driven to rotate 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.

[0014] The stator 21 is fixed to the inner periphery of the case of the motor 2. The stator 21 has three-phase windings (21u, 21v, 21w). The windings (21u, 21v, 21w) are wound around the stator 21. For example, the three-phase windings (21u, 21v, 21w) are connected by a delta connection.

[0015] In the delta connection, winding 21u and winding 21w are connected by connection point 21a, winding 21v and winding 21w are connected by connection point 21c, and winding 21u and winding 21v are connected by connection point 21b.

[0016] 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.

[0017] The position detection unit 30 detects a signal corresponding to the rotation of the rotor 22. The position detection unit 30 includes, for example, three Hall elements (30u, 30v, 30w). When the rotor 22 rotates, these three Hall elements (30u, 30v, 30w) output pulse signals that are shifted in phase by 120 degrees to the control unit 40. That is, as the rotor 22 rotates, the position detection unit 30 generates pulse signals based on changes in the magnetic poles of a sensor magnet (not shown) disposed on the rotor shaft 22a, and outputs the pulse signals to the control unit 40. The Hall elements (30u, 30v, 30w) detect positions that are shifted by 120 electrical degrees.

[0018] In this embodiment, the Hall element 30u outputs a digital signal (position detection signal Hu) corresponding to the U phase, and the Hall element 30v outputs a digital signal (position detection signal Hv) corresponding to the V phase. Furthermore, the Hall element 30w outputs a digital signal (position detection signal Hw) corresponding to the W phase. The three Hall elements (30u, 30v, 30w) in this embodiment are disposed with respect to the rotor 22 so that when the output of the inverter 50 is immediately changed at each position where the levels of the output signals of the three Hall elements (30u, 30v, 30w) change, i.e., at each position where an edge occurs in the output signal, an advance angle of 30 electrical degrees is achieved.

[0019] The inverter 50 is controlled, for example, by PWM (Pulse Width Modulation) based on a drive signal generated by the drive control unit 43 (described later), and applies a voltage to the three-phase windings (21u, 21v, 21w) of the motor 2. That is, the inverter 50 performs switching operations (conduction / non-conduction) on the switching elements (51a to 51f) based on the drive signal generated by the drive control unit 43, and changes the magnitude (duty ratio), conduction period (conduction angle), and conduction timing (advance angle) of the output voltage applied to the motor 2. Here, the duty ratio represents the ratio of the conduction period of the corresponding switching element in the PWM period.

[0020] The inverter 50 generates an applied voltage using DC power supplied from the battery 3. 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.

[0021] 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.

[0022] 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.

[0023] 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.

[0024] 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.

[0025] 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.

[0026] 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.

[0027] 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.

[0028] 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 generates a drive signal according 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 transmits and receives predetermined information between the ECU 4 and the motor 2. The control unit 40 includes a rotation speed detection unit 41, an acceleration detection unit 42, and a drive control unit 43.

[0029] The rotation speed detection unit 41 detects the rotation speed of the motor 2. The rotation speed detection unit 41 detects the rotation speed (number of rotations) of the motor 2 (rotor 22) based on the output signals output by the three Hall elements (30u, 30v, 30w) of the position detection unit 30.

[0030] The acceleration detection unit 42 detects whether or not the motor 2 is accelerating. The acceleration detection unit 42 detects whether or not the motor 2 is accelerating, for example, based on the output signals output by the three Hall elements (30u, 30v, 30w) of the position detection unit 30.

[0031] The drive control unit 43 generates a drive signal corresponding to a target rotation output of the rotor 22 (e.g., a target rotation speed TRPM) and outputs the generated drive signal to the inverter 50. The drive control unit 43 controls the duty ratio to be output so as not to exceed a duty upper limit value set according to the rotation speed of the motor 2. The lower the rotation speed of the motor 2, the lower the duty upper limit value is set, thereby preventing an overcurrent from flowing to the motor 2. The drive control unit 43 controls the drive of the motor 2, for example, by switching between a square wave drive mode (an example of a second drive mode) and a free-wheeling drive mode (an example of a first drive mode). When the square wave drive mode and the free-wheeling drive mode are driven at the same duty ratio, the square wave drive mode produces a higher rotation speed of the motor 2. In other words, the square wave drive mode is a drive mode with higher output than the free-wheeling drive mode and is a two-phase current drive mode. Here, the square wave drive mode and the free-wheel drive mode will be described in detail with reference to FIGS.

[0032] 2, 4, and 6 are explanatory diagrams illustrating an example of the position detection signals (Hu, Hv, Hw) output by the Hall elements (30u, 30v, 30w) and the advance angle and conduction angle in the conduction control of the inverter 50. 2, 4, and 6 show the correspondence between the position detection signals (Hu, Hv, Hw) and the angle regions in which the switching elements 51a to 51f are turned on. The horizontal axis represents the rotational position of the magnetic poles of the rotor 22 of the motor 2 in electrical angle.

[0033] The position detection signals (Hu, Hv, Hw) have a phase difference of 120 degrees with one cycle being 360 electrical degrees, and change to an H state (high state) or an L state (low state) every 180 degrees. In this embodiment, a change of the position detection signal Hu from the L state to the H state is referred to as a Hall edge HE1, and a change from the H state to the L state is referred to as a Hall edge HE4. A change of the position detection signal Hv from the L state to the H state is referred to as a Hall edge HE3, and a change from the H state to the L state is referred to as a Hall edge HE6. A change of the position detection signal Hw from the L state to the H state is referred to as a Hall edge HE5, and a change from the H state to the L state is referred to as a Hall edge HE2.

[0034] Assuming that the position detection signals (Hu, Hv, Hw) output by the Hall elements (30u, 30v, 30w) contain no error, the electrical angle between each Hall edge is 60 degrees. The area between Hall edge HE1 and Hall edge HE2 is referred to as Hall stage 1 (hereinafter simply referred to as stage 1, and the same applies hereinafter). The area between Hall edge HE2 and Hall edge HE3 is referred to as stage 2. The area between Hall edge HE3 and Hall edge HE4 is referred to as stage 3. The area between Hall edge HE4 and Hall edge HE5 is referred to as stage 4. The area between Hall edge HE5 and Hall edge HE6 is referred to as stage 5. The area between Hall edge HE6 and Hall edge HE1 is referred to as stage 6.

[0035] FIG. 2 is a diagram showing an example of a square wave drive pattern in this embodiment. 2, the horizontal axis represents the electrical angle, and is a diagram showing the correspondence relationship between the position detection signals (Hu, Hv, Hw) and the energization patterns of the switching elements 51a to 51f. The example of energization control shown in FIG. 2 is for a 20 degree advance angle and a 130 degree energization angle.

[0036] The conduction pattern is a combination of the switching elements 51a to 51f being continuously on ("ON"), continuously off ("OFF") (a period other than "ON" or "PWM", also called a free phase period), or controlled to be on or off at regular intervals (PWM controlled state) ("PWM"). Each of the stages 1 to 6 is further divided into three sections A', B', and C'. Individual conduction patterns are set for Sections A', B', and C'. The periods (electrical angles) of Sections A', B', and C' vary depending on the advance angle and conduction angle.

[0037] For example, in stage 1 surrounded by hall edges HE1 and HE2, the conduction pattern in section A' is a combination of "ON", "OFF", "PWM", "PWM", "OFF", and "OFF" for the switching elements 51a to 51f, respectively. The conduction pattern in section B' is a combination of "ON", "OFF", "PWM", "PWM", "ON", and "OFF" for the switching elements 51a to 51f, respectively. The conduction pattern in section C' is a combination of "OFF", "OFF", "PWM", "PWM", "ON", and "OFF" for the switching elements 51a to 51f, respectively.

[0038] Fig. 3 is a table showing an example of the rectangular wave energization pattern in this embodiment shown in Fig. 2. The ROM (not shown) in the control unit 40 stores the rectangular wave energization pattern in the format shown in Fig. 3, for example. In Fig. 3, "1" represents on, "0" represents off, and "P" represents PWM.

[0039] As described above, the combinations that form the square wave energization pattern include the following three states (1) to (3). (1) First state: Each of the switching elements 51a to 51f is continuously in an on state ("ON"). (2) Second state: Each of the switching elements 51a to 51f is continuously in an "OFF" state (a period other than "ON" or "PWM"). (3) Third state: Each of the switching elements 51a to 51f is in a state in which it is controlled to be on or off at a constant cycle (PWM controlled state) ("PWM").

[0040] In this way, in the square wave drive mode, the drive control section 43 controls the conduction (energization) of the switching elements 51a to 51f using the square wave energization pattern described above.

[0041] Next, the freeless drive mode will be described with reference to FIGS. There are two methods for controlling the free-wheeling current conduction pattern used in the free-wheeling drive mode:

[0042] In the first method of free-flow current control, the duty ratio of the PWM signal for the switching element connected to the coil of one of the three phases is set to a value intermediate between the duty ratios of the PWM signals for the switching elements connected to the coils of the other two phases.

[0043] In the second method of free-flow current control, the duty ratio of the PWM signal for the switching element connected to the coil of one of the three phases is set to half the command duty ratio input from outside, and the duty ratios of the PWM signals for the switching elements connected to the coils of the other two phases are set to the same value as the command duty ratio and 100%, respectively.

[0044] <First method of free-flowing electricity> In the driving and energization according to the freeless energization pattern using the first method, the above states (1) to (3) are changed to the following three states (4) to (6), respectively.

[0045] (4) Fourth state: The first state is changed to a fourth state (hereinafter referred to as the "PL" state) that is PWM controlled by a PWM signal having a maximum duty ratio greater than that of the PWM control in the third state. (5) Fifth state: The third state is changed to a fifth state (hereinafter referred to as the "PS" state) that is PWM controlled by a PWM signal having a minimum duty ratio that is smaller than that of the PWM control in the third state. (6) Sixth state: The second state is changed to a sixth state (hereinafter referred to as the "PM" state) that is PWM controlled by a PWM signal with a duty ratio intermediate between the maximum duty ratio and the minimum duty ratio.

[0046] In other words, the timing at which the U-phase, V-phase, and W-phase windings (21u, 21v, 21w) each enter the PM state (sixth state) in the free-flow current pattern is the same as the timing at which the U-phase, V-phase, and W-phase windings (21u, 21v, 21w) each enter the OFF-phase coil (second state) in the rectangular wave current pattern.

[0047] This addresses the problem of the control circuit (drive control unit 43) that drives the switching elements 51a-51f malfunctioning when a negative voltage occurs at the input terminal of the motor 2 when the current conduction pattern switches from the first state to the second state. Also, even during the timing when 120-degree rectangular wave current conduction is free (phase open period: period in the second state), by performing PWM control as in the sixth state, it becomes 180-degree current conduction, and the current waveform during commutation becomes smooth, which is expected to result in quieter drive noise (reduced motor operating noise).

[0048] In this embodiment, the intermediate duty ratio is 50%. The maximum duty ratio is the duty ratio obtained by adding half the duty ratio of the command duty ratio input from the outside to the intermediate duty ratio. The minimum duty ratio is the duty ratio obtained by subtracting half the duty ratio of the command duty ratio from the intermediate duty ratio.

[0049] For example, if the command duty ratio is 80%, the intermediate duty ratio is preset to 50%, so the maximum duty ratio is 90% (50 + 80 ÷ 2), and the minimum duty ratio is 10% (50 - 80 ÷ 2). It is assumed that the command duty ratio is stored in advance in a ROM (not shown) of the control unit 40 by the user.

[0050] Here, PWM signals having opposite phases to the PWM signals input to the positive switching elements 51a to 51c are input to the negative switching elements 51d to 51f. The duty ratios of the PWM signals that drive the paired switching elements differ between the positive and negative sides, but in this embodiment, the duty ratios of the PWM signals that drive the positive switching elements 51a to 51c are referred to as the duty ratios of the PWM signals that drive the paired switching elements.

[0051] FIG. 4 is a diagram showing an example of a freeless current supply pattern of the first method. FIG. 4 is a diagram showing the correspondence between the position detection signals (Hu, Hv, Hw) and the current conduction patterns of the switching elements 51a to 51f, with the horizontal axis representing the electrical angle.

[0052] 4 shows an example of energization control where the advance angle is 20 degrees and the energization angle is 130 degrees. The energization pattern is a combination of the following for each of the switching elements 51a to 51f: a continuous on state ("ON"), i.e., a state where the switching elements change from "ON" (first state) to "PL" (fourth state); a continuous off state ("OFF") (period other than "ON" or "PWM"), i.e., a state where the switching elements change from "OFF" (second state) to "PM" (sixth state); and a state where the switching elements are controlled to be on or off at a fixed cycle (PWM controlled state) ("PWM"), i.e., a state where the switching elements change from "PWM" (third state) to "PS" (fifth state).

[0053] Each of the stages 1 to 6 is further divided into three sections: Section A, Section B, and Section C. Individual current conduction patterns are set for Section A, Section B, and Section C. The periods (electrical angles) of Section A, Section B, and Section C change depending on the lead angle value and current conduction angle value.

[0054] In the PWM controlled state, each of the switching elements 51a to 51f repeatedly turns ON and OFF, so to be precise, the waveform is a rectangular wave with multiple concave and convex portions, but for convenience in Fig. 4 and Fig. 6 described later, the ON / OFF of each of the switching elements 51a to 51f is not specified and they are expressed as "PWM phases." Here, in Fig. 4, the "PL" state is expressed as "PWM phase (MAX Duty)," the "PS" state as "PWM phase (MIN Duty)," and the "PM" state as "PWM phase (Duty=50)."

[0055] For example, in stage 1 surrounded by hole edges HE1 and HE2, the current conduction pattern in section A is a combination of "PL", "PL", "PS", "PS", "PM", and "PM" for the switching elements 51a to 51f, respectively. The current conduction pattern in section B is a combination of "PL", "PL", "PS", "PS", "PL", and "PL" for the switching elements 51a to 51f, respectively. The current conduction pattern in section C is a combination of "PM", "PM", "PS", "PS", "PL", and "PL" for the switching elements 51a to 51f, respectively.

[0056] 5 is a table showing an example of the freeless current conduction pattern of the first method shown in FIG. 4. The ROM (not shown) in the control unit 40 stores the freeless current conduction pattern in the format shown in FIG.

[0057] In FIG. 5, "PL" represents the fourth state in which PWM control is performed using a PWM signal with the maximum duty ratio, "PS" represents the fifth state in which PWM control is performed using a PWM signal with the minimum duty ratio, and "PM" represents the sixth state in which PWM control is performed using a PWM signal with a duty ratio intermediate between the maximum and minimum duty ratios. In this way, in the freeless drive mode (first method), the drive control unit 43 controls the conduction (energization) of the switching elements 51a to 51f using the freeless energization pattern described above.

[0058] <Second method of free-flowing electricity> In the driving and energization according to the freeless energization pattern using the second method, the above states (1) to (3) are changed to the following three states (4) to (6), respectively. The states are changed to the following three states (7) to (9). Note that the control of each switching element is the same in the states (1) and (7), so the states do not actually change.

[0059] (7) Seventh state: The first state is maintained, and each of the switching elements 51a to 51f is continuously turned on ("ON"). (8) Eighth state: The third state is changed to an eighth state (hereinafter referred to as "P1 state") that is PWM controlled by a PWM signal with an externally input designated duty ratio. (9) Ninth state: The second state is changed to a ninth state (hereinafter referred to as "P2" state) that is PWM controlled by an externally input PWM signal with a duty ratio that is half the designated duty ratio.

[0060] In other words, the timing at which the U-phase, V-phase, and W-phase windings (21u, 21v, 21w) each enter the P2 state (9th state) in the free-flowing current pattern is the same as the timing at which the U-phase, V-phase, and W-phase windings (21u, 21v, 21w) each enter the OFF-phase windings (2nd state) in the rectangular wave current pattern.

[0061] This addresses the problem of the control circuit (controller 40) that drives the switching elements malfunctioning when a negative voltage occurs at the input terminal of the motor 2 when the current conduction pattern switches from the first state to the second state. Also, even during the timing when 120-degree rectangular wave current conduction is free (phase open period: period in the second state), by performing PWM control as in the ninth state, it becomes 180-degree current conduction, and the current waveform during commutation becomes smoother, which is expected to result in quieter drive noise (reduced motor operating noise). That is, whether the driving and energizing method using the free-flowing energizing pattern of the first method or the second method is used, the same effect can be expected.

[0062] In this embodiment, the duty ratio in the seventh state is 100%. For example, if the command duty ratio is 80%, the duty ratio in the eighth state is 80%, and the duty ratio in the ninth state is 40% (80 / 2). The command duty ratio is stored in advance in a ROM (not shown) of the control unit 40 by the user.

[0063] FIG. 6 is a diagram showing an example of a freeless current supply pattern of the second method. FIG. 6 is a diagram showing the correspondence between the position detection signals (Hu, Hv, Hw) and the energization patterns of the switching elements 51a to 51f, with the horizontal axis representing the electrical angle.

[0064] The example of energization control shown in FIG. 6 is for a 20-degree advance angle and a 130-degree energization angle. The energization patterns are a combination of the following: a state in which each switching element 51a-51f is continuously turned on ("ON"), i.e., a state in which it maintains "ON" (first state) (seventh state); a state in which it is continuously turned off ("OFF") (periods other than "ON" or "PWM"), i.e., a state in which it changes from "OFF" (second state) to "P2" (ninth state); and a state in which it is controlled to be on or off periodically (a PWM-controlled state) ("PWM"), i.e., a state in which it changes from "PWM" (third state) to "P1" (eighth state). Each of stages 1-6 is further divided into three sections: A", B", and C". Individual energization patterns are set for sections A", B", and C". The periods (electrical angles) of Section A", Section B", and Section C" vary depending on the advance angle value and conduction angle value. Here, in FIG. 6, the "P1" state is represented as the "PWM phase (command duty)" and the "P2" state is represented as the "PWM phase (1 / 2 duty)".

[0065] For example, in stage 1 surrounded by hall edges HE1 and HE2, the current conduction pattern in section A" is a combination of "1", "0", "P1", "P1", "P2", and "P2" for the switching elements 51a to 51f, respectively. The current conduction pattern in section B" is a combination of "1", "0", "P1", "P1", "1", and "0" for the switching elements 51a to 51f, respectively. The current conduction pattern in section C" is a combination of "P2", "P2", "P1", "P1", "1", and "0" for the switching elements 51a to 51f, respectively.

[0066] 7 is a table showing an example of the freeless current conduction pattern of the second method shown in FIG. 6. The ROM (not shown) in the control unit 40 stores the freeless current conduction pattern in the format shown in FIG.

[0067] In Figure 7, "P1" represents the eighth state PWM controlled by a PWM signal with an externally input designated duty ratio, "P2" represents the ninth state PWM controlled by a PWM signal with a duty ratio that is 1 / 2 of the designated duty ratio, "1" represents on, and "0" represents off. In this way, in the freeless drive mode (second method), the drive control section 43 controls the conduction (energization) of the switching elements 51a to 51f using the freeless energization pattern described above.

[0068] As described above, the square wave drive mode is a drive mode based on the square wave drive method, and is a drive mode with higher output than the free-wheel drive mode. The free-wheeling drive mode is a drive mode of the free-wheeling drive system that outputs an intermediate-power drive signal by PWM control during the open period of the non-energized phases of the multi-phase drive signal lines that drive the motor 2, and is a drive mode with lower output than the square-wave drive mode. Here, the intermediate-power drive signal is a PWM signal with a duty ratio intermediate between the PWM signal with the maximum duty ratio and the PWM signal with the minimum duty ratio (first system), or a PWM signal with a duty ratio that is half the command duty ratio input from outside (second system).

[0069] Returning to the explanation of FIG. 1, when starting the motor 2, the drive control unit 43 selects the square wave drive mode if the motor 2 is accelerating and the rotational speed of the motor 2 is smaller than the target value by a predetermined value or more. Here, whether the motor 2 is accelerating or not is detected using the acceleration detection unit 42 described above. The rotational speed of the motor 2 is the rotational speed (number of rotations) detected by the rotational speed detection unit 41. That is, the drive control unit 43 selects the square wave drive mode when the acceleration detection unit 42 detects that the motor 2 is accelerating and the rotational speed detected by the rotational speed detection unit 41 is smaller than the target rotational speed (target rotational speed) by a predetermined value (predetermined threshold) or more ((target rotational speed - rotational speed) ≧ predetermined threshold).

[0070] In addition, the drive control unit 43 selects the free-wheeling drive mode when the motor 2 is decelerating or when the rotation speed of the motor 2 is smaller than the target value by a predetermined value ((target rotation speed - rotation speed) < predetermined threshold value).

[0071] Next, the operation of the motor device 100 according to this embodiment will be described with reference to the drawings. FIG. 8 is a flowchart showing an example of the drive mode switching operation of the motor device 100 according to this embodiment.

[0072] As shown in FIG. 8, the control unit 40 of the motor device 100 first acquires the driving status of the motor 2 (step S101). The rotational speed detection unit 41 of the control unit 40 detects the rotational speed (number of rotations) of the motor 2 (rotor 22) based on the output signals output by the three Hall elements (30u, 30v, 30w) of the position detection unit 30. The acceleration detection unit 42 of the control unit 40 detects whether the motor 2 is accelerating based on the output signals output by the three Hall elements (30u, 30v, 30w) of the position detection unit 30. The drive control unit 43 of the control unit 40 acquires the detection results of the rotational speed detection unit 41 and the acceleration detection unit 42 as the driving status of the motor 2.

[0073] Next, the drive control unit 43 determines whether the motor 2 is in a start-up state (whether the motor 2 is accelerating) (step S102). The drive control unit 43 determines whether the motor 2 is accelerating at the time of starting the motor 2 based on the detection result of the acceleration detection unit 42. If the motor 2 is in a start-up state (accelerating) (step S102: YES), the drive control unit 43 proceeds to step S104. If the motor 2 is not in a start-up state (accelerating) (step S102: NO), the drive control unit 43 proceeds to step S103. Note that the cases where the motor 2 is not in a start-up state (accelerating) include the cases where the motor 2 is decelerating or rotating at a constant speed.

[0074] In step S103, the drive control unit 43 selects the free-wheeling drive mode. After the process of step S103, the drive control unit 43 advances the process to step S106.

[0075] In step S104, the drive control unit 43 determines whether the deviation between the target rotation speed and the rotation speed is equal to or greater than a predetermined value. For example, the drive control unit 43 determines whether the rotation speed of the motor 2 is smaller than the target rotation speed by equal to or greater than a predetermined value ((target rotation speed - rotation speed) ≥ predetermined threshold value). If the deviation between the target rotation speed and the rotation speed is equal to or greater than the predetermined value ((target rotation speed - rotation speed) ≥ predetermined threshold value) (step S104: YES), the drive control unit 43 proceeds to step S105. If the deviation between the target rotation speed and the rotation speed is not equal to or greater than the predetermined value ((target rotation speed - rotation speed) < predetermined threshold value) (step S104: NO), the drive control unit 43 proceeds to step S103 and selects the above-mentioned freeless drive mode.

[0076] In step S105, the drive control unit 43 selects the square wave drive mode. The drive control unit 43 switches, for example, from the free-wheel drive mode to the square wave drive mode. After processing in step S105, the drive control unit 43 proceeds to the process in step S106.

[0077] In step S106, the drive control unit 43 determines whether or not the reverse position has been reached. The drive control unit 43 temporarily stops the rotational driving of the motor 2, and determines whether or not the reverse position, which is the starting point for rotational driving in the reverse direction, has been reached. If the reverse position has been reached (step S106: YES), the drive control unit 43 ends the control process. If the reverse position has not been reached (step S106: NO), the drive control unit 43 returns the process to step S101 and continues the control process until the reverse position is reached.

[0078] As described above, the motor device 100 according to this embodiment includes the motor 2 that is driven to rotate, a rotational speed detector 41, an acceleration detector 42, and a drive controller 43. The rotational speed detector 41 detects the rotational speed of the motor 2. The acceleration detector 42 detects whether the motor 2 is accelerating. The drive controller 43 controls switching between a first drive mode (e.g., free-wheeling drive mode) in which three-phase current is applied to drive the motor 2 and a second drive mode (e.g., square-wave drive mode) in which the output of the motor 2 is higher than that of the first drive mode (e.g., free-wheeling drive mode). When the motor 2 is accelerating and the rotational speed of the motor 2 is lower than the target value (target rotational speed) by a predetermined value or more, the drive controller 43 selects the second drive mode (e.g., square-wave drive mode).

[0079] As a result, when the rotation speed is insufficient, motor device 100 according to this embodiment selects a second drive mode (e.g., square wave drive mode) in which the output of motor 2 is higher than in the first drive mode (e.g., free-wheeling drive mode) even if the upper duty limit value is small, so that the rotation speed can be increased with a small duty ratio. Therefore, motor device 100 according to this embodiment can prevent the motor from stalling even when a load is applied at the time of motor start.

[0080] Here, the effects of the motor device 100 according to this embodiment will be described by comparing the operations of a conventional motor device and the motor device 100 according to this embodiment with reference to FIGS.

[0081] FIG. 9 is a diagram showing an example of the operation of a conventional motor device for comparison. In Fig. 9, the vertical axis of the graph represents the rotation angle or rotation speed, and the horizontal axis represents time. The example shown in Fig. 9 shows an example in which a conventional motor device is used in a vehicle wiper.

[0082] 9, waveform W1 shows the change over time in the rotation angle of the conventional motor device, waveform W2 shows the change over time in the target rotation speed of the conventional motor device, and waveform W3 shows the change over time in the actual rotation speed of the conventional motor device.

[0083] 9 shows an example in which a high load is generated from the initial stage of driving a conventional motor device. The conventional motor device switches from the free-wheeling drive mode to the square wave drive mode based on the integrated value of the load.

[0084] FIG. 10 is a diagram showing an example of the operation of the motor device 100 according to this embodiment. 10, as in FIG. 9, the vertical axis of the graph represents the rotation angle or rotation speed, and the horizontal axis represents time. The example shown in FIG. 10 illustrates an example in which the motor device 100 according to this embodiment is used in a vehicle wiper.

[0085] 10, waveform W4 shows the change over time in the rotation angle of motor device 100 according to this embodiment, waveform W5 shows the change over time in the target rotation speed of motor device 100 according to this embodiment, and waveform W6 shows the change over time in the actual rotation speed of motor device 100 according to this embodiment.

[0086] In conventional motor devices, if a high load is generated from the beginning of driving, the load has not yet accumulated, so the drive mode is not switched to square wave drive mode. Furthermore, because the rotation speed of motor 2 is low and the upper duty limit is set small, the duty ratio cannot be increased, and as shown by waveform W3 in Figure 9, the actual rotation speed does not reach the target rotation speed during the first wiping operation. Therefore, as shown by waveform W1, in conventional motor devices, wiping cannot be performed at the normal rotation speed during the first wiping operation, and wiping takes a long time.

[0087] In contrast, in the motor device 100 according to this embodiment, the difference between the target speed (waveform W5) and the actual rotation speed (waveform W6) becomes large during acceleration in partial region P1 of FIG. 10, so the motor device 100 switches from the freeless drive mode to the square wave drive mode. As a result, even if a high load is generated from the initial stage of drive and the duty ratio cannot be increased by setting an upper duty limit, the motor device 100 according to this embodiment can maintain a normal rotation speed from the first wiping operation, as shown by waveform W4 in FIG. 10. In this way, the motor device 100 according to this embodiment can prevent the motor from stalling even when a load is applied when the motor is started.

[0088] In addition, in this embodiment, the drive control unit 43 selects the first drive mode (e.g., free-wheel drive mode) when the motor 2 is decelerating or when the rotation speed of the motor 2 is smaller than the target value by a predetermined value.

[0089] The first drive mode (e.g., free-wheel drive mode) with three-phase conduction has higher noise reduction performance than the second drive mode with two-phase conduction. Therefore, the motor device 100 according to this embodiment can improve noise reduction performance when, for example, there is no load by switching to the first drive mode (e.g., free-wheel drive mode) when the motor 2 is decelerating or there is no heavy load.

[0090] In addition, in this embodiment, the second drive mode (rectangular wave drive mode) is a drive mode of a rectangular wave drive system, and the first drive mode (free-wheel drive mode) is a drive mode of a free-wheel drive system in which an intermediate power drive signal is output by PWM control during an open period of a phase that is not energized among the multiple phase drive signal lines that drive the motor 2.

[0091] As a result, in the first drive mode (free-wheel drive mode), current is also applied to the OFF phase, creating a closed circuit and generating a braking force, so that the motor device 100 of this embodiment can stop the motor at the appropriate reversal position, for example, in a wiper device, even if the blade is pushed in the wiping direction by the wind from traveling near the upper reversal position (additional load).

[0092] In addition, in this embodiment, the motor 2 is a brushless motor having three-phase windings, and the drive control unit 43 controls the conduction of multiple switching elements (51a to 51f) of the inverter 50 that generates the three-phase drive signal by switching between a first drive mode (e.g., free-wheeling drive mode) and a second drive mode (e.g., square wave drive mode). As a result, the motor device 100 according to this embodiment can perform more appropriate motor driving for a brushless motor.

[0093] The motor control device 150 according to this embodiment also includes the motor 2 that rotates as described above, a rotational speed detection unit 41, an acceleration detection unit 42, and a drive control unit 43. As a result, the motor control device 150 according to this embodiment has the same effect as the motor device 100 described above, and can suppress stalling of the motor even when a load is applied when the motor is started.

[0094] Furthermore, the motor control method according to this embodiment is a motor control method for controlling a rotationally driven motor 2, and includes a rotation speed detection step, an acceleration detection step, and a drive control step. In the rotation speed detection step, a rotation speed detection unit 41 detects the rotation speed of the motor 2. In the acceleration detection step, an acceleration detection unit 42 detects whether the motor 2 is accelerating. In the drive control step, a drive control unit 43 controls switching between a first drive mode (freeless drive mode) for driving the motor 2 and a second drive mode (square wave drive mode) in which the output of the motor 2 is higher than that in the freeless drive mode. When starting the motor 2, if the motor 2 is accelerating and the rotation speed of the motor 2 is lower than the target value by a predetermined value or more, the second drive mode (square wave drive mode) is selected.

[0095] As a result, the motor control method according to this embodiment has the same effect as the motor device 100 described above, and can suppress stalling of the motor even when a load is applied when the motor is started.

[0096] Next, a wiper device 200 according to a second embodiment of the present invention will be described with reference to the drawings.

[0097] [Second embodiment] Here, an example in which the above-described motor device 100 is applied to a wiper device 200 will be described with reference to FIG. FIG. 11 is a configuration diagram showing an example of a wiper device 200 according to this embodiment.

[0098] 11, 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.

[0099] 11 is the motor device 100 of the present embodiment described above, and a detailed description thereof will be omitted here. The motor device 100 includes a motor 2 and a motor control device 150.

[0100] 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.

[0101] 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).

[0102] As described above, the wiper device 200 according to this embodiment includes the motor device 100 described above, and 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.

[0103] As a result, the wiper device 200 of this embodiment has the same effect as the motor device 100 described above, and can suppress stalling of the motor even when loads such as wind from driving or wear on the wiper blade 13 are applied when the motor is started.

[0104] 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, the motor device 100 has been described as selecting the rectangular wave drive mode when the motor 2 is accelerating at the start of the motor 2 and the rotational speed of the motor 2 is smaller than the target value by a predetermined value or more, but this may also be implemented in combination with drive mode switching control based on the load integrated value obtained by integrating the load.

[0105] In the above embodiment, the first drive mode is the freewheel drive mode and the second drive mode is the square wave drive mode. However, the present invention is not limited to this, and other drive mode combinations may be used. For example, a sine wave drive mode may be used instead of the freewheel drive mode.

[0106] In the sine wave drive mode, the drive control unit 43 outputs a drive signal to the inverter 50 to supply sine wave current to the three-phase windings 21u, 21v, and 21w of the stator 21, thereby driving the rotor 22 to rotate. This makes it possible to reduce torque ripple compared to the square wave drive mode. As a result, the operating noise of the motor 2 is reduced compared to the square wave drive mode. Furthermore, a waveform in which harmonics are superimposed on a sine wave may be used as the current waveform. This also reduces the operating noise of the motor 2.

[0107] 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.

[0108] 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.

[0109] 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]

[0110] 1...vehicle, 2...motor, 3...battery, 4...ECU, 10...window glass, 11...link mechanism, 12...wiper arm, 13...wiper blade, 21...stator, 21u, 21v, 21w...winding, 22...rotor, 22a...rotor shaft, 22b...permanent magnet, 30...position detection unit, 30u, 30v, 30w...hall element, 40...control unit, 41...rotational speed detection unit, 42...acceleration detection unit, 43...drive control unit, 50...inverter, 51a to 51f...switching element, 52a to 52f...diode, 100...motor device, 150...motor control device, 200...wiper device

Claims

1. a motor that drives the rotation; a rotation speed detection unit that detects the rotation speed of the motor; an acceleration detection unit that detects whether the motor is accelerating; a drive control unit that performs control to switch between a first drive mode for driving the motor and a second drive mode in which the output of the motor is higher than that of the first drive mode, and selects the second drive mode when the motor is accelerating and the rotation speed of the motor is smaller than a target value by a predetermined value or more at the start of the motor; A motor device comprising:

2. The drive control unit selects the first drive mode when the motor is decelerating or when the rotation speed of the motor is smaller than the target value by less than a predetermined value. The motor device according to claim 1 .

3. the second driving mode is a square wave driving mode, The first drive mode is a free-wheeling drive mode in which a drive signal of an intermediate power is output by PWM (Pulse Width Modulation) control during an open period of a phase in which no current is applied among a plurality of drive signal lines for driving the motor. The motor device according to claim 1 .

4. the motor is a brushless motor having three-phase windings, The drive control unit controls conduction of a plurality of switching elements included in an inverter that generates a three-phase drive signal by switching between the first drive mode and the second drive mode. The motor device according to claim 1 .

5. 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.

6. A motor control method for controlling a rotationally driven motor, comprising: 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 whether the motor is accelerating; a drive control step in which a drive control unit switches between a first drive mode for driving the motor and a second drive mode in which the output of the motor is higher than that of the first drive mode, and selects the second drive mode when the motor is accelerating and the rotation speed of the motor is smaller than a target value by a predetermined value or more at the start of the motor; A motor control method comprising:

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