Control device and charging device

Abstract

To provide a technique capable of reducing noises while preventing the occurrence of motor step-out in a situation where the ambient temperature changes.SOLUTION: A control device 500 controls the operation of a stepper motor. An output unit 530 is configured to cause a stopped motor to operate at a first drive frequency and to operate after switching to a second drive frequency at a stable point. The first drive frequency is a frequency lower than the resonant frequency region of the motor, while the second drive frequency is a frequency higher than the resonant frequency region of the motor.SELECTED DRAWING: Figure 9

Description

[Technical Field]

[0001] The present disclosure relates to control technology, and more particularly to a control device for controlling the operation of a motor and a charging device. [Background technology]

[0002] When accelerating or decelerating a stepping motor, if the drive control is performed using a drive frequency within the resonant frequency band of the stepping motor itself, vibrations will occur in the stepping motor. In order to reduce the vibrations that occur in the stepping motor, a method has been proposed in which the stepping motor is accelerated, driven at a constant speed, and decelerated while avoiding the resonant frequency band of the stepping motor itself (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 10-98898 Summary of the Invention [Problem to be solved by the invention]

[0004] Stepping motors are also used, for example, to move coils in charging devices mounted on vehicles and capable of wireless charging. For this reason, stepping motors are sometimes used even at ambient temperatures of -20°C. At low temperatures, the viscosity of grease increases, increasing the torque required to drive the stepping motor. However, if a stepping motor is driven at a frequency that avoids the resonant frequency band, proper driving is not possible, resulting in insufficient torque and a high risk of step-out.

[0005] The present disclosure has been made in light of these circumstances, and its purpose is to provide a technology that reduces noise while preventing loss of synchronization of a motor in situations where the ambient temperature changes. [Means for solving the problem]

[0006] In order to solve the above problem, a control device according to an embodiment of the present disclosure includes: For motors that operate with microstep drive, operating the stopped motor at the first drive frequency; This is the timing when either the drive waveform for the motor's A-phase coil or the drive waveform for the B-phase coil reaches a maximum or minimum value. Motor stability point The stable point after the motor starts rotating The control unit switches from the first drive frequency to the second drive frequency.

[0007] Another aspect of the present disclosure is also a control device. For motors that operate with microstep drive, A control unit defines a first timing for starting the operation of a motor and a second timing that is later than the first timing, operates a stopped motor at a first drive frequency from the first timing, and switches from the first drive frequency to a second drive frequency at the second timing, and the second timing is This is the timing when either the drive waveform for the motor's A-phase coil or the drive waveform for the B-phase coil reaches a maximum or minimum value. Motor stability point The stable point after the motor starts rotating is. [Effects of the Invention]

[0008] According to the present disclosure, it is possible to reduce noise while preventing the motor from losing synchronization in situations where the ambient temperature changes. [Brief explanation of the drawings]

[0009] [Figure 1] 1 is a perspective view showing the interior of a vehicle according to an embodiment; [Figure 2] FIG. 2 is a perspective view showing the structure of the charging device of FIG. [Figure 3] 3 is a perspective view showing a state in which an electronic device is placed on the charging device of FIG. 2. FIG. [Figure 4] 3 is a perspective view showing the charging device of FIG. 2 with a part removed. [Figure 5] FIG. 5 is a top view showing the structure of the charging device of FIG. [Figure 6] FIG. 3 is a cross-sectional view showing the structure of the charging device of FIG. [Figure 7] 3 is a cross-sectional view showing the structure of a support plate of the charging device of FIG. 2. [Figure 8] 3 is a plan view showing the structure of a support plate of the charging device of FIG. 2. [Figure 9] FIG. 3 is a diagram showing the configuration of the charging device of FIG. 2. [Figure 10] 10 is a diagram showing drive waveforms for the XA-phase coil and the XB-phase coil in FIG. 9. FIG. [Figure 11] 11(a) to 11(c) are diagrams showing the characteristics of a stepping motor. [Figure 12] FIG. 10 is a diagram showing the relationship between the drive frequency and the noise level. [Figure 13] 13(a) to 13(d) are diagrams showing an outline of the operation of the motor. [Figure 14] FIG. 10 is a diagram illustrating another operation outline of the motor. [Figure 15] 15(a) and 15(b) are diagrams showing an outline of the operation of a motor according to a modified example. [Figure 16] 16(a) and 16(b) are flowcharts showing a motor control procedure according to a modified example. DETAILED DESCRIPTION OF THE INVENTION

[0010] Before describing the present disclosure in detail, an overview will be provided. An embodiment of the present disclosure relates to a charging device capable of performing contactless charging, i.e., wireless charging. The charging device performs wireless charging on an electronic device placed on the upper surface of the charging device. An example of an electronic device is a portable terminal device such as a smartphone. Qi, established by the Wireless Power Consortium (WPC), is an international standard for wireless charging. In such wireless charging, charging is efficient when the charging coil of the charging device and the coil of the electronic device face each other. Therefore, a charging device according to an embodiment moves the charging coil so that it faces the coil of the electronic device. The charging coil is moved by converting the rotation of a stepping motor driven by microsteps into linear motion.

[0011] In microstep driving, a table of values ​​obtained by dividing a pseudo-sine wave, for example, by 64, is prepared in advance, and the table values ​​are output in sequence using PWM (Pulse Width Modulation) or DA (Digital-to-Analog). The stepping motor operates according to this output. To start charging quickly, the stepping motor operates by increasing the speed of the charging coil from a stopped state. To do this, the rotation speed of the stepping motor must be changed. In this case, if the frequency of the stepping motor's rotation matches the motor's own resonant frequency, it becomes a source of vibration and generates noise within the device.

[0012] In order to suppress noise generation, in prior art, stepping motors are driven by avoiding drive frequencies in the resonant frequency band. As mentioned above, when stepping motors are used in vehicles, they are required to be driven in low-temperature environments. In low-temperature environments, the viscosity of grease increases, so the torque required to drive the stepping motor is greater than at room temperature. However, when a stepping motor is driven by avoiding drive frequencies in the resonant frequency band, proper driving cannot be performed, resulting in insufficient torque and a high risk of step-out.

[0013] In this embodiment, a drive frequency (hereinafter referred to as the "first drive frequency") lower than the resonant frequency band is used to initiate startup in the motor's self-start region at a drive frequency that generates the largest torque, thereby escaping the static friction region where the drive load is the largest in a stationary state. After the stepping motor starts rotating, when the stepping motor reaches a stable point, the drive frequency is switched from the first drive frequency to a drive frequency (hereinafter referred to as the "second drive frequency") higher than the resonant frequency band, transitioning to constant speed drive (maximum speed). In the following explanation, "parallel" and "orthogonal" do not only mean perfectly parallel or orthogonal, but also include cases where they deviate from parallel or orthogonal within a margin of error. Furthermore, "approximately" means roughly the same.

[0014] 1 is a perspective view showing a passenger compartment 12 of a vehicle 10. A steering wheel 14 is installed on the right side in the front of the passenger compartment 12 of the vehicle 10. The steering wheel 14 may also be installed on the left side. A center console 16 is also arranged to the side of the steering wheel 14, that is, in the center of the front of the passenger compartment 12 of the vehicle 10. Furthermore, a charging device 100 is installed behind the center console 16 in the passenger compartment 12.

[0015] FIG. 2 is a perspective view showing the structure of charging device 100. FIG. 3 is a perspective view showing a state in which electronic device 300 is placed on charging device 100. As shown in FIGS. 2 and 3, a Cartesian coordinate system including x-, y-, and z-axes is defined. The x- and y-axes are mutually orthogonal. The z-axis is perpendicular to the x- and y-axes and extends in the thickness direction of charging device 100. The positive direction of each of the x-, y-, and z-axes is defined as the direction of the arrow in FIGS. 2 and 3, and the negative direction is defined as the direction opposite to the arrow. Here, the positive direction of the z-axis may also be referred to as "upper," "upper side," or "top side," and the negative direction of the z-axis may also be referred to as "lower," "lower side," or "bottom side."

[0016] The charging device 100 includes a support plate 110 and a main body case 120. The combination of the support plate 110 and the main body case 120 has a box-like shape. The support plate 110 is placed on the upper side of the main body case 120. The electronic device 300 is a device to be charged by the charging device 100, and as described above, is, for example, a portable terminal device such as a smartphone. When the electronic device 300 is placed on the support plate 110, the charging device 100 charges the electronic device 300.

[0017] FIG. 4 is a perspective view showing a state in which a portion of charging device 100 has been removed. This corresponds to a state in which support plate 110 has been removed from charging device 100 in FIG. 2. FIG. 5 is a top view showing the structure of charging device 100 in FIG. 4. FIG. 6 is a cross-sectional view showing the structure of charging device 100, taken along line A-A' in FIG. 2. FIG. 7 is a cross-sectional view showing the structure of support plate 110 of charging device 100. FIG. 8 is a plan view showing the structure of support plate 110 of charging device 100. Within main body case 120, charging coil 130 is provided so as to be movable horizontally while facing the underside of support plate 110 in FIG. 2. Also provided within main body case 120 are a drive unit 140 that moves charging coil 130 horizontally while facing the underside of support plate 110, and a control device (not shown) connected to drive unit 140 and charging coil 130.

[0018] As shown in FIG. 6 , the support plate 110 includes a top plate 112, a middle plate 114, and a back plate 116 stacked vertically. The top plate 112 and the back plate 116 are made of synthetic resin, and the middle plate 114 is made of ceramic. This allows magnetic flux from a charging coil 130 (described later) to pass through the support plate 110 toward the electronic device 300. Furthermore, as shown in FIGS. 7 and 8 , a plurality of detection coils 132 are provided on the top and bottom surfaces of the middle plate 114 so as to be distributed within the xy plane of the middle plate 114. For example, a plurality of detection coils 132 extending in the x-axis direction and a plurality of detection coils 132 extending in the y-axis direction are arranged in a matrix pattern, overlapping each other. This arrangement of the plurality of detection coils 132 is one example, and the plurality of detection coils 132 may also be arranged in a matrix pattern so as not to overlap each other. Detection coil 132 detects whether electronic device 300 is placed on support plate 110, and also detects at what position on support plate 110 electronic device 300 is placed. Based on the detection result, drive unit 140 moves charging coil 130 to a position facing the coil of electronic device 300.

[0019] As shown in Figures 4 and 5, charging coil 130 has an annular shape formed by spirally wound wire. The outer periphery and underside of charging coil 130 are held by holder 150 made of synthetic resin. Support legs 152, which extend downward from charging coil 130, are integrally formed of synthetic resin on the underside of holder 150, as shown in Figure 6. A gap of 0.3 mm is provided between the underside of support legs 152 and the upper surface of metal support plate 154 located below support legs 152. This gap prevents the underside of support legs 152 from contacting the upper surface of support plate 154 when charging coil 130 moves. A control board 156 and a lower panel 158 of main body case 120 are located below support plate 154. For example, the aforementioned control device is installed on control board 156. A support body 160 that penetrates the control board 156 is provided between the lower surface of the support plate 154 and the upper surface of the lower plate 158. In other words, in order to increase strength against excessive weight, the lower surface side of the support plate 154 is supported by the lower plate 158 of the main body case 120 via the support body 160.

[0020] 4 and 5, drive unit 140 has a Y-axis direction drive shaft 200 and an X-axis direction drive shaft 202. The intermediate portions of Y-axis direction drive shaft 200 and X-axis direction drive shaft 202 contact portions of holder 150 other than the portion where charging coil 130 is held. For this reason, holder 150 is provided with a through-hole (not shown) through which Y-axis direction drive shaft 200 passes and a through-hole 204 through which X-axis direction drive shaft 202 passes, the through-holes being vertically spaced a predetermined distance apart and intersecting each other. Y-axis direction drive shaft 200 and X-axis direction drive shaft 202 come into contact with through-hole 204.

[0021] A worm wheel 206 is provided on one end of the Y-axis direction drive shaft 200, and a gear 208 is provided on the worm wheel 206. A gear 208 is also provided on the other end of the Y-axis direction drive shaft 200, where the worm wheel 206 is not provided. The worm wheel 206 engages with a worm 210, which is connected to a Y-axis motor 212. The gears 208 on both sides engage with gear plates 214, respectively. With this structure, when the Y-axis motor 212 is driven, the worm 210 rotates, thereby moving the worm wheel 206 in the y-axis direction together with the Y-axis direction drive shaft 200. Furthermore, the charging coil 130, which is integrated with the Y-axis direction drive shaft 200, also moves in the y-axis direction. Hereinafter, the mechanical part moved by the motor will be referred to as the drive load.

[0022] A worm wheel 216 is provided on one end of the X-axis drive shaft 202, and a gear 218 is provided on the worm wheel 216. A gear 218 is also provided on the other end of the X-axis drive shaft 202, where the worm wheel 216 is not provided. The worm wheel 216 engages with a worm 220, which is connected to an X-axis motor 222. The gears 218 on both sides engage with gear plates 224. With this structure, when the X-axis motor 222 is driven, the worm 220 rotates, thereby moving the worm wheel 216 in the x-axis direction together with the X-axis drive shaft 202. Furthermore, the charging coil 130, which is integrated with the X-axis drive shaft 202, moves in the x-axis direction. Current is applied to the charging coil 130 via a flexible wiring 226 shown in FIG. 4. An end of the flexible wiring 226 is fixed to the side of the support leg 152.

[0023] 9 shows the configuration of charging device 100. Charging device 100 includes charging coil 130, detection coil 132, Y-axis motor 212, X-axis motor 222, control device 500, first LPF 600a, second LPF 600b, third LPF 600c, and fourth LPF 600d, collectively referred to as LPFs (Low-Pass Filters) 600, motor drive device 620, YA-phase coil 630, YB-phase coil 640, XA-phase coil 650, XB-phase coil 660, charging coil control unit 700, and detection coil control unit 710. Control device 500 includes processing unit 510, storage unit 520, and output unit 530.

[0024] As mentioned above, a plurality of detection coils 132 are provided, but they are shown collectively here. A detection coil control unit 710 is connected to the detection coils 132. The detection coil control unit 710 controls the operation of the detection coils 132 to identify the position on the support plate 110 where the coil of the control device 500 is to be placed. The detection coil control unit 710 outputs information relating to the identified position (hereinafter referred to as "position information") to the control device 500. The position information is represented by x-axis coordinates and y-axis coordinates.

[0025] A stepping motor consists of an iron stator and a magnetized rotor. When current is passed through the coil, the stator becomes an electromagnet. The magnetized rotor and the electromagnetized stator attract each other, causing the rotor to stably stop. Switching the magnetized points on the stator generates a rotating magnetic field, causing the rotor to rotate. In the typical structure of a claw-pole PM (Permanent Magnet) stepping motor, the rotor incorporates a permanent magnet magnetized with alternating north and south poles. The stator has claw-shaped metal parts, and when current flows through the winding coil, the claws become magnetized and become south or north poles. Rotational torque is generated by utilizing the attraction and repulsion between the stator's magnetic poles, which are magnetized by the winding current, and the rotor's magnetic poles. Below, we will explain the case of a stepping motor with a step angle of 18 degrees as an example. In this case, there are 20 stable points 820 per motor rotation. Naturally, the same concept can be applied to different step angles.

[0026] The control device 500 receives position information from the detection coil control unit 710. The control device 500 moves the charging coil 130 by rotating the Y-axis motor 212 and the X-axis motor 222 so that the charging coil 130 is positioned at the position indicated by the position information. In particular, the control device 500 moves the charging coil 130 in the x-axis direction by rotating the X-axis motor 222, and moves the charging coil 130 in the y-axis direction by rotating the Y-axis motor 212. In other words, the Y-axis motor 212 or the X-axis motor 222 moves the position of the charging coil 130, and the control device 500 controls the drive of the Y-axis motor 212 or the X-axis motor 222. The X-axis motor 222 and the Y-axis motor 212 are collectively referred to as "motors." After moving the charging coil 130, the control device 500 instructs the charging coil control unit 700 to start charging. The charging coil control unit 700 controls the operation of the charging coil 130 in response to instructions from the control device 500, thereby charging the electronic device 300.

[0027] As described above, microstep driving is performed to rotate the Y-axis motor 212 and the X-axis motor 222. To provide an overview of microstep driving, FIG. 10 is used here. FIG. 10 shows the drive waveforms for the XA-phase coil 650 and the XB-phase coil 660. The drive waveform for the XA-phase coil 650 is indicated as Phase A, and the drive waveform for the XB-phase coil 660 is indicated as Phase B. As shown in the figure, the A-phase drive waveform and the B-phase drive waveform are out of phase by 90 degrees. Therefore, in microstep driving, the X-axis motor 222 is rotated by outputting drive waveforms that are out of phase by 90 degrees to the XA-phase coil 650 and the XB-phase coil 660. As described above in relation to the motor structure, the strongest attractive force is generated at the maximum and minimum values ​​of each phase, which are the stable points of the motor. When one current waveform, for example, phase A, is viewed, the extreme values ​​(maximum / minimum values) or zero values ​​of the sine wave correspond to the stable points of the motor.

[0028] When the A-phase drive waveform and the B-phase drive waveform are changed by 1 / 4 cycle (90 degrees) of the pseudo-sine wave, the X-axis motor 222 rotates one step, i.e., the motor shaft rotates 18 degrees. At this time, the point at which the motor shaft rotates 18 degrees from the stable point of the motor also becomes the stable point of the motor. As described above, if one cycle of the pseudo-sine wave is divided into, for example, 64 steps, each step corresponds to a motor rotation angle of 1.125 degrees. Therefore, if the motor rotation angle is the same step as the stable point of the motor in the steps obtained by dividing the pseudo-sine wave, even if it deviates from the motor rotation angle, it can be considered an error. The division of the pseudo-sine wave is not limited to 64 divisions and can be set as appropriate. Furthermore, when the X-axis motor 222 rotates one step, i.e., the motor shaft rotates 18 degrees, the charging coil 130 moves, for example, 0.1 mm. Shortening the period of one step increases the rotation speed of X-axis motor 222, shortening the period required for charging coil 130 to move 0.1 mm. This corresponds to faster movement of charging coil 130. On the other hand, lengthening the period of one step decreases the rotation speed of X-axis motor 222, lengthening the period required for charging coil 130 to move 0.1 mm. This corresponds to slower movement of charging coil 130. The same applies to YA-phase coil 630, YB-phase coil 640, and Y-axis motor 212, so a description thereof will be omitted here. Return to FIG. 9.

[0029] To achieve this microstep drive, a table in which one period of a pseudo-sine wave is divided into multiple periods, for example, 64 periods, is stored in the storage unit 520. The processing unit 510 reads values ​​from the table at time intervals corresponding to the drive frequency and generates a pseudo-sine wave-like drive waveform. The drive waveform has, for example, a stepped waveform. The drive waveform generated by the processing unit 510, for example, an A-phase drive waveform in the x-axis direction, is output from the output unit 530 to the third LPF 600c. The third LPF 600c smooths the stepped drive waveform to make the shape of the drive waveform closer to a sine wave. The third LPF 600c outputs the drive waveform to the motor drive device 620. The motor drive device 620 generates a drive current based on the received drive waveform and passes the drive current to the XA-phase coil 650.

[0030] For the B phase in the x-axis direction, the previous drive waveform is simply shifted by 90 degrees, and the processing unit 510, output unit 530, fourth LPF 600d, motor drive device 620, and XB-phase coil 660 operate in the same manner as described above. Also, for the y-axis direction, the processing unit 510, output unit 530, first LPF 600a, second LPF 600b, motor drive device 620, YA-phase coil 630, and YB-phase coil 640 operate in the same manner as described above.

[0031] Figures 11(a)-(c) show the characteristics of a stepping motor. Figure 11(a) in particular shows the typical speed-torque characteristics of a stepping motor. The horizontal axis represents the drive frequency, and the vertical axis represents torque. The drive frequency represents the input signal used to drive the stepping motor, measured in units of pulses per second (pps) or Hertz (Hz). The self-start region is the frequency range in which the motor can synchronize with an external pulse signal to start, rotate forward, or rotate backward. If the motor is no longer able to synchronize with the input pulse, it will lose synchronization and become unable to operate normally. The self-start region is the region in which the motor can be switched from a stopped state to a rotating state. Because the motor is stopped, static friction between the motor and the drive load becomes dominant. The through region is the region in which the motor can maintain synchronization with the input signal and respond when the frequency is increased beyond the self-start region, and dynamic friction between the motor and the drive load becomes dominant. Taking these characteristics into consideration, when starting a stopped motor, the drive start frequency is set low because it is necessary to start the motor with a large generated torque in the self-start region. Also, even if the frequency is set high after the motor has started rotating in the self-start region, the motor's response range has expanded to the motor's through region, so it is possible to respond while maintaining synchronization with the input signal, and it is possible to increase the drive frequency without causing step-out.

[0032] 12 shows the relationship between drive frequency and noise level. The horizontal axis represents drive frequency, and the vertical axis represents noise level. The drive frequency range from approximately 150 pps to approximately 350 pps is a resonant frequency range 800, where noise levels increase.

[0033] Figures 13(a)-(d) show an overview of the operation of the motor. Figures 13(a)-(b) show an overview of the operation of the motor used for comparison, and Figures 13(c)-(d) show an overview of the operation of the motor according to this embodiment. Figure 13(a) shows the relationship between the time from the start of driving the motor used for comparison and the driving frequency. The driving frequency is gradually increased over time up to 500 pps, and in this case, driving is performed without using the resonant frequency range 800 in order to suppress an increase in motor noise.

[0034] Figure 13(b) shows the relationship between time and torque for a motor driven as shown in Figure 13(a). Room-temperature required torque 810 indicates the torque required to drive a motor at room temperature, e.g., 25°C. First, the torque required to drive a motor using room-temperature required torque 810 will be explained. As shown in the figure, room-temperature required torque 810 is high in the self-starting region, i.e., the state from when the motor starts rotating to when it is stationary, and is low in the through region, i.e., the state after the motor starts rotating. Low-temperature required torque 812 indicates the torque required to drive a motor at a low temperature, e.g., -20°C. The low-temperature required torque 812 has the same characteristics as the room-temperature required torque 810, but because grease viscosity increases at low temperatures, a higher torque than the room-temperature required torque 810 is required in both the self-starting region and the through region.

[0035] Motor drive torque 814 indicates the torque when operating at a drive frequency such as that shown in Figure 13(a). As described above, the drive frequency is increased in stages over time, so motor drive torque 814 decreases in stages over time. As long as motor drive torque 814 is greater than the required torque, the motor will not lose synchronization. At low temperatures, low-temperature required torque 812 becomes greater than normal-temperature required torque 810, and motor drive torque 814 may become smaller than low-temperature required torque 812, increasing the likelihood of loss of synchronization at low temperatures.

[0036] Figure 11(b) shows the transition of the required torque for the motor operation shown in Figure 13(b). By gradually increasing the drive frequency, the motor approaches the boundary of the self-activation region. However, at room-temperature required torque 810, the motor rotates within the self-activation region, expanding the motor's response range into the motor's through region. This allows the motor to respond in synchronization with the input signal, making it possible to increase the drive frequency without losing synchronism. Meanwhile, at low-temperature required torque 812, the low temperature increases the viscosity of the grease, increasing the load and causing the motor to exceed the self-activation region without rotating, resulting in loss of synchronization with the input signal and loss of synchronism.

[0037] FIG. 13(c) shows the relationship between the time from when the motor starts to drive and the drive frequency in this embodiment. When the motor rotates at a constant speed in this embodiment, stable points 820 also occur periodically. For example, if the motor rotation speed is 50 pps, stable points 820 occur every 20 msec. This disclosure is characterized in that the timing for switching the motor's operation is determined at the stable points 820. As the motor rotates within the self-activation region, the drive frequency is lowered until the first stable point 820 is reached after the motor's response range expands to the motor's through region, and then the drive frequency is increased at the stable point 820. Furthermore, the timing at which the operation is actually switched (the time at which the first stable point 820 is reached after the motor's response range expands from the self-activation region to the through region) is determined by a value measured in advance, such as through an experiment.

[0038] In FIG. 13(c), the drive frequency that is lowered to perform operation at motor startup is the "first drive frequency," and the drive frequency that is set higher to perform high-speed operation is the "second drive frequency." The first drive frequency is a frequency lower than the resonant frequency range 800 of the motor, and is set to, for example, "50 pps." The second drive frequency is a frequency higher than the resonant frequency range 800 of the motor, and is set to, for example, "500 pps." As shown in FIG. 12, the noise at 50 pps and 500 pps is lower than the noise in the resonant frequency range 800, so an increase in noise caused by motor operation can be suppressed.

[0039] Figure 13(d) shows the relationship between time and torque for a motor driven as shown in Figure 13(c). The room-temperature required torque 810 and low-temperature required torque 812 are the same as those in Figure 13(b). Motor drive torque 814 shows the torque when operating at the drive frequency shown in Figure 13(c). That is, the motor drive torque 814 is driven at a first drive frequency with a sufficiently large torque and begins operation in the self-start region, and then changes to a second drive frequency in the through region where the required torque has decreased. Therefore, the motor drive torque 814 generates a torque greater than not only the room-temperature required torque 810 but also the low-temperature required torque 812, and step-out does not occur at either room temperature or low temperatures.

[0040] Figure 11(c) shows the transition of the required torque during the motor operation shown in Figure 13(c). Because operation begins at the first drive frequency, which provides a large drive torque, the motor rotates within its self-start region. The motor's response range then expands to the motor's slew region, allowing it to respond while maintaining synchronization with the input signal even when switched to the higher second drive frequency. Therefore, the room-temperature required torque 810 and the low-temperature required torque 812 can be synchronized with the motor's rotation, allowing operation without loss of synchronization.

[0041] As described above, the processing unit 510 in Fig. 9 reads values ​​from the table at time intervals corresponding to the drive frequency and generates a pseudo-sinusoidal drive waveform. In this case, the processing unit 510 manages the second timing, which is later than the first timing for starting the motor operation. At the first timing, the motor starts operating at the first drive frequency, and at the second timing, the processing unit 510 manages switching to the second drive frequency, which further increases the motor speed. This second timing is managed after the motor's response range expands to the motor's slew region due to the motor rotating within its self-start region.

[0042] The second timing is preset to a set value selected from among the timings at which the motor reaches a stable point. Here, for example, a case where the second timing at a low temperature is set to 160 msec will be described. The processing unit 510 reads out the table values ​​at time intervals corresponding to the first drive frequency between the first timing and the second timing. Furthermore, the processing unit 510 reads out the table values ​​at time intervals corresponding to the second drive frequency from the second timing onwards. The output unit 530 operates the stopped motor at the first drive frequency from the first timing, and switches the drive frequency from the first drive frequency to the second drive frequency at the second timing.

[0043] Figure 14 shows another overview of motor operation. The motor starts driving using a first drive frequency, and over time the drive frequency is switched from the first drive frequency to a second drive frequency. After a further time has passed, the motor switches from the second drive frequency back to the first drive frequency and stops.

[0044] This configuration can be realized in hardware terms by any computer's CPU (Central Processing Unit), memory, and other LSIs (Large Scale Integration), and in software terms by programs loaded into memory, but here we depict functional blocks realized by the cooperation of these. Therefore, those skilled in the art will understand that these functional blocks can be realized in various forms by hardware alone or a combination of hardware and software.

[0045] (Variation) Up until now, the second timing has been set in advance as a fixed value. In this modified example, the second timing is adjusted according to the ambient temperature. The charging device 100 according to this modified example further includes a temperature sensor in addition to the configuration of FIG. 9, and the temperature sensor is connected to the control device 500. The temperature sensor measures the ambient temperature of the motor, for example, the temperature of the vehicle interior 12. Known techniques may be used to measure the temperature with the temperature sensor, and therefore a description thereof will be omitted here.

[0046] The processing unit 510 of the control device 500 in FIG. 9 acquires the temperature measured by the temperature sensor. The processing unit 510 adjusts the second timing according to the acquired temperature. For example, when the detected temperature is low, the grease viscosity increases and the load increases, so it is necessary to set a longer time for driving at a low speed with a large generated torque. Therefore, the processing unit 510 sets a longer period from the first timing to the second timing as the acquired temperature decreases. On the other hand, when the detected temperature is high, the required torque is smaller than at room temperature, but in order to suppress heat generation in the motor, the processing unit 510 sets a shorter period from the first timing to the second timing as the acquired temperature increases.

[0047] More specifically, the storage unit 520 stores a temperature conversion table indicating the correspondence between temperature and the second timing. More specifically, the temperature conversion table of the storage unit 520 sets the value of the second timing at which to switch to the second drive frequency for each temperature. At this time, the set value is set to the motor stable point as described above. In the temperature conversion table, for low temperatures, for example, 160 ms for temperatures below -20°C, 120 ms for temperatures between -20 and 25°C, and 80 ms for temperatures above 25°C. Similarly, for high temperatures, for example, 80 ms for temperatures below 25°C, 40 ms for temperatures between 25 and 50°C, and 0 ms for temperatures above 50°C.

[0048] Figures 15(a) and 15(b) show an overview of motor operation. Figure 15(a) shows a first example of a modified example, where the detected temperature is low. When the detected temperature is low, the grease viscosity is high and the load is large, so it is necessary to set a long time for driving at low speed, which generates a large torque. The normal temperature drive frequency 832 indicates the second timing when the temperature is 25° C. or higher, and is set to 80 msec as described above.

[0049] On the other hand, low-temperature drive frequency 830 indicates the second timing at low temperatures. Since the viscosity of grease changes with temperature, the set value is changed according to the change in torque characteristics due to temperature. Figure 15(a) shows the case of -20°C or below, and as mentioned above, the second timing at this time is set to 160 ms, which is the same as the example shown in Figure 13(c). For example, when the temperature is -10 to 25°C, low-temperature drive frequency 830 is set to 120 ms.

[0050] FIG. 15(b) shows a second example of the modified example, where the detected temperature is high. When the detected temperature is high, the required torque is smaller than at room temperature. However, the high ambient temperature increases the possibility that heat generated by the motor will adversely affect the reliability of the motor and driver IC. Driving the motor at low speeds with high torque also increases the amount of heat generated. For this reason, when the detected temperature is high, it is desirable to reduce the amount of heat generated by the motor by shortening the period from the first timing to the second timing. Room-temperature drive frequency 832 indicates the second timing when the temperature is 25°C or higher, and is set to 80 msec as described above.

[0051] On the other hand, high temperature drive frequency 834 indicates the second timing when the temperature is high. At high temperatures, the setting is changed according to the temperature to suppress heat generation by the motor. FIG. 15(b) shows the case of 25 to 50°C, and as mentioned above, the second timing is set to 40 ms at this time. For example, when the temperature is 50°C or higher, high temperature drive frequency 834 is set to 0 ms. This corresponds to matching the first timing and the second timing. At this time, output section 530 in FIG. 9 operates the stopped motor at the second drive frequency, not at the first drive frequency.

[0052] The operation of the charging device 100 with the above configuration will be described. FIGS. 16(a)-(b) are flowcharts showing the control procedure of the motor. FIG. 16(a) shows the operation of the first example. The temperature sensor measures the ambient temperature θ (S10). If the ambient temperature θ is less than or equal to the threshold value θcl (Y in S12), the processing unit 510 sets the second timing to the current application time t1 (S14). Here, t1 > tc. If the ambient temperature θ is not less than or equal to the threshold value θcl (N in S12), the processing unit 510 sets the second timing to the current application time tc (S16).

[0053] FIG. 16(b) shows the operation of the second example. The temperature sensor measures the ambient temperature θ (S50). If the ambient temperature θ is greater than the threshold value θch (Y in S52), the processing unit 510 sets the second timing to the current application time t2 (S54). Here, t2 < tc. If the ambient temperature θ is not greater than the threshold value θch (N in S52), the processing unit 510 sets the second timing to the current application time tc (S56).

[0054] According to this embodiment, at the first timing of starting the motor, it operates at the first driving frequency with a sufficiently large torque, and when the rotation of the motor occurs within the self-starting region, the motor is switched from the first driving frequency to the high-speed second driving frequency and operated at the second timing when the response range of the motor is expanded up to the through region of the motor. Therefore, in a situation where the ambient temperature changes, the occurrence of motor detuning can be prevented. Also, the second timing is set using one of the timings when the motor reaches a stable state. Since the first driving frequency is a frequency lower than the resonance frequency region of the motor and the second driving frequency is a frequency higher than the resonance frequency region of the motor, the noise of the motor can be reduced.

[0055] Furthermore, since the second timing is adjusted according to the temperature, control appropriate for the temperature can be performed. At low temperatures, the lower the temperature, the greater the torque required. Therefore, by lengthening the section in which the motor generates a large torque, i.e., the period from the first timing to the second timing, it is possible to prevent the motor from losing synchronization. On the other hand, at high temperatures, the higher the temperature, the shorter the period from the first timing to the second timing, which makes it possible to suppress heat generation by the motor. Furthermore, at high temperatures, the first timing and the second timing are matched, and a stopped motor is operated at the second drive frequency rather than the first drive frequency, thereby further suppressing heat generation by the motor.

[0056] An overview of one aspect of the present disclosure is as follows: A control device according to one aspect of the present disclosure includes a control unit that operates a stopped motor at a first drive frequency and switches from the first drive frequency to a second drive frequency at a stable point of the motor.

[0057] According to this aspect, the drive frequency is switched from the first drive frequency to the second drive frequency at the stable point of the motor, so that even in a situation where the ambient temperature changes, there is no shortage of torque and it is possible to prevent the motor from losing synchronization.

[0058] The first drive frequency is lower than the resonant frequency range of the motor, and the second drive frequency is higher than the resonant frequency range of the motor. Furthermore, since the first drive frequency and the second drive frequency are outside the resonant frequency range of the motor, noise generated by the motor can be suppressed.

[0059] Another aspect of the present disclosure is also a control device, which defines a first timing for starting operation of a motor and a second timing that is later than the first timing, and a control unit that operates a stopped motor at a first drive frequency from the first timing and switches from the first drive frequency to the second drive frequency at the second timing, the second timing being a stable point of the motor.

[0060] According to this embodiment, the second timing is a stable point of the motor, so that even in a situation where the ambient temperature changes, there is no shortage of torque and it is possible to prevent the motor from losing synchronization.

[0061] The first drive frequency is lower than the resonant frequency range of the motor, and the second drive frequency is higher than the resonant frequency range of the motor. Furthermore, since the first drive frequency and the second drive frequency are outside the resonant frequency range of the motor, noise generated by the motor can be suppressed.

[0062] The control unit may acquire the temperature measured by the temperature sensor and adjust the second timing in accordance with the acquired temperature. In this case, the second timing is adjusted in accordance with the temperature, so that control in accordance with the temperature can be performed.

[0063] The control unit may extend the period from the first timing to the second timing as the acquired temperature decreases. In this case, the period from the first timing to the second timing is extended as the temperature decreases, thereby preventing the motor from losing synchronization.

[0064] The control unit may shorten the period from the first timing to the second timing as the acquired temperature increases. In this case, the period from the first timing to the second timing decreases as the temperature increases, thereby suppressing heat generation by the motor.

[0065] The control unit may synchronize the first timing with the second timing, and operate the stopped motor at the second drive frequency instead of the first drive frequency. In this case, by synchronizing the first timing with the second timing and operating the stopped motor at the second drive frequency instead of the first drive frequency, heat generation in the motor can be suppressed.

[0066] The charging device may include a motor that moves the position of the charging coil and a control device that controls the driving of the motor. In this case, since the charging device includes a motor that moves the position of the charging coil, it is possible to move the charging coil.

[0067] The present disclosure has been described above based on examples. These examples are merely illustrative, and it will be understood by those skilled in the art that various modifications are possible in the combination of each component or each treatment process, and that such modifications are also within the scope of the present disclosure.

[0068] In this embodiment, the charging device 100 is mounted on the vehicle 10. However, the present invention is not limited to this, and the charging device 100 may be placed on a stand or the like instead of being mounted on the vehicle 10. According to this modification, the range of application can be expanded. [Explanation of symbols]

[0069] 10 vehicle, 12 passenger compartment, 14 steering wheel, 16 center console, 100 charging device, 110 support plate, 112 front plate, 114 middle plate, 116 back plate, 120 main body case, 130 charging coil, 132 detection coil, 140 drive unit, 150 holder, 152 support leg, 154 support plate, 156 control board, 158 lower plate, 160 support, 200 Y-axis drive shaft, 202 X-axis drive shaft, 204 through hole, 206 worm wheel, 208 gear, 210 worm, 212 Y-axis motor, 214 gear plate, 216 worm wheel, 218 gear, 220 worm, 222 X-axis motor, 224 gear plate, 226 flexible wiring, 300 electronic device, 500 control device, 510 processing unit, 520 memory unit, 530 output unit, 600 LPF, 620 motor drive device, 630 YA phase coil, 640 YB phase coil, 650 XA phase coil, 660 XB phase coil.

Claims

1. A control device for a motor that operates using microstep drive, which operates the stopped motor at a first drive frequency and has a control unit that switches from the first drive frequency to a second drive frequency at one of the stable points of the motor, which are the timings when one of the drive waveforms for the motor's A-phase coil and B-phase coil becomes a maximum or minimum value, after the motor starts rotating.

2. the first drive frequency is a frequency lower than a resonance frequency range of the motor, The control device according to claim 1 , wherein the second drive frequency is higher than a resonance frequency range of the motor.

3. A motor that operates in a microstep drive mode is defined to have a first timing for starting the operation of the motor and a second timing that is later than the first timing; A control device that operates the stopped motor at a first drive frequency from the first timing and switches from the first drive frequency to a second drive frequency at the second timing, wherein the second timing is one of the stable points of the motor, which are timings at which one of the drive waveforms for the A-phase coil and the B-phase coil of the motor reaches a maximum value or a minimum value, and is the stable point after the motor starts rotating.

4. the first drive frequency is a frequency lower than a resonance frequency range of the motor, The control device according to claim 3 , wherein the second drive frequency is higher than a resonance frequency range of the motor.

5. The control device according to claim 4 , wherein the control unit acquires a temperature measured by a temperature sensor and adjusts the second timing in accordance with the acquired temperature.

6. The control device according to claim 5 , wherein the control unit extends the period from the first timing to the second timing as the acquired temperature decreases.

7. The control device according to claim 5 , wherein the control unit shortens the period from the first timing to the second timing as the acquired temperature increases.

8. the control unit matches the first timing with the second timing, 5. The control device according to claim 3, wherein the motor, when stopped, does not operate at the first drive frequency but operates at the second drive frequency.

9. a motor that moves the position of the charging coil; a control device according to any one of claims 1 to 8, which controls driving of the motor; A charging device comprising:

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