JP2009183140A - Motor drive system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a motor control system for power assistance, capable of quickly responding to a sensor output. <P>SOLUTION: A motor drive system comprises stators 10 and 12 in a plurality of phases and a moving element 14, exciting means 16 and 18 which alternately excite the stators in different polarity. A load connected to the moving piece, a control circuit which outputs an excitation signal to the exciting means, a magnetizing means for alternately magnetizing the moving piece in different polarity, and a means of controlling the control circuit so that, when a stress is applied on the load, the excitation signal is outputted in one phase of the stators of the control circuit and then the excitation signal is outputted to the stator in remaining phase such that the load acts in the stress direction. When a motor is applied with an external stress, it is supplied with a drive signal to realize a required power assisting mechanism. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a motor control system, and more particularly to a motor control system that realizes power assist control. The motor control system of the present invention is used for an electric vehicle, an electric construction machine, an electric agricultural instrument, an electric robot control, an electric power assist device (for example, an electric bicycle, a cassette loading / ejecting device), an electric toy, an electric airplane, and the like. The

  As a conventional technique related to the present invention, there is a compact disk loading / ejecting apparatus (for example, JP-A-9-139002). In this case, when external stress acts on the CD drive tray, the acceleration detector works, and the CPU drives the drive unit with the signal from this acceleration detector to accelerate the tray and reproduce the compact disc. It was loaded into the recording device.

JP-A-9-139002

  As in the past, if the CPU performs a calculation once based on the signal from the sensor and controls the drive unit based on the result of the calculation, the control of the power assist mechanism for the load cannot be responded to the sensor output at high speed. There's a problem. Accordingly, an object of the present invention is to provide a power assist motor control system capable of responding to sensor output at high speed.

  In order to achieve the above object, the present invention comprises a stator and a moving element, one of which is a permanent magnet that is alternately magnetized with a different polarity, and the other can be excited with a different polarity. A drive control unit that outputs to the electromagnetic coil a drive signal consisting of an alternating current signal that alternately switches the excitation pattern of the electromagnetic coil, and a position sensor of the mover, the mover comprising: Connected to a load, the drive control unit determines a direction of stress with respect to the load, and forms the drive signal for rotating the movable element in the direction in synchronization with an output from the position sensor, This is a motor drive system configured to output this to the electromagnetic coil.

  In a preferred embodiment of the present invention, the stator is composed of two phases of a first magnetic body and a second magnetic body, and the mover is disposed between the magnetic bodies, and the first and second magnetic bodies are arranged. The first magnetic body and the second magnetic body each include a plurality of electromagnetic coils that can be alternately excited with different polarities. The third magnetic body has a configuration in which permanent magnets alternately magnetized with different polarities are sequentially arranged, and the first magnetic body has a configuration in which the first magnetic body is arranged in order. The second magnetic body has a configuration in which the electromagnetic coil of the first magnetic body and the electromagnetic coil of the second magnetic body are arranged so as to have an arrangement pitch difference.

  Further, a plurality of N sets, each having two excitation coils N / S pole side and S / N pole side, are arranged at equal intervals, and at least two phases are provided. An arrangement is provided with an angular difference, which is used as the stator, and the phases are opposed to each other, and the movable element is provided between them. Further, the drive control unit is a duty ratio control means for the drive signal. Further, the drive control unit includes means for selecting a stator to which a drive signal is supplied.

  Furthermore, the present invention provides a multi-phase stator and moving element, exciting means for alternately exciting the stator to different polarities, a load connected to the moving element, and a control for outputting an excitation signal to the exciting means. A circuit, magnetizing means for alternately magnetizing the mover to different polarities, and when the stress on the load is applied, the excitation signal is output to one phase of the stator of the control circuit, and And a means for controlling the control circuit to output the excitation signal to the remaining one-phase stator so that the load operates in the direction of the stress.

  A stator and a mover are provided, and one of the stator and the mover is a permanent magnet that is alternately magnetized with a different polarity, and the other is an electromagnetic coil that can be alternately excited with a different polarity. A drive control unit that outputs a drive signal composed of an alternating current signal for alternately switching patterns to the electromagnetic coil; and a position sensor for the mover, wherein the mover is connected to a load, and the drive control unit Is configured to determine the direction of stress with respect to the load, form the driving signal for rotating the moving element in the direction in synchronization with the output from the position sensor, and output this to the electromagnetic coil. This is a motor drive system. According to the present invention, it is possible to provide a power assist motor control system capable of responding to a sensor output at high speed in order to form a drive signal in synchronization with a sensor output after starting.

The schematic diagram of a motor structure and the principle of operation are shown. FIG. 2 shows an operation principle following FIG. FIG. 3 shows an operation principle following FIG. 2. FIG. FIG. 4 shows an operation principle following FIG. 3. FIG. It is an equivalent circuit diagram which shows the connection state of an electromagnetic coil. It is a block diagram of the driver part of a motor. It is the detailed block diagram. (1) is a perspective view of a synchronous motor, (2) is a schematic plan view of the motor, (3) is a side view thereof, (4) is an A phase electromagnetic coil (first magnetic member), and (5) is a B phase. An electromagnetic coil (second magnetic member) is shown. It is a PWM control waveform characteristic figure of the exciting current output to a coil. It is a control waveform characteristic by the block configuration of FIG. FIG. 3 shows a detailed view of an A-phase / B-phase buffer circuit.

  1 to 4 are schematic views showing the driving principle of an excitation driven motor according to the present invention. This motor has a configuration in which a third magnetic body 14 is interposed between a first magnetic body (A-phase coil) 10 and a second magnetic body (B-phase coil) 12. These magnetic materials may be formed in an annular shape (arc shape, circular shape) or linear shape. When the magnetic body is formed in an annular shape, either the third magnetic body or the first or second magnetic body functions as a rotor, and when the magnetic body is formed linearly, either Become. For example, the first magnetic body and the second magnetic body correspond to a stator, and the third magnetic body corresponds to a mover.

  The first magnetic body 10 has a configuration in which coils 16 that can be alternately excited with different polarities are arranged in order at predetermined intervals, preferably at equal intervals. An equivalent circuit diagram of the first magnetic body is shown in FIG. According to FIGS. 1 to 4, as will be described later, the two-phase excitation coils are always excited with the polarity described above during the starting rotation (2π). Therefore, driven means such as a rotor and a slider can be rotated and driven with high torque.

  As shown in FIG. 5A, a plurality of electromagnetic coils 16 (magnetic units) are connected in series at equal intervals. Reference numeral 18A denotes an excitation circuit block for applying a frequency pulse signal to the magnetic coil. When an excitation signal for exciting the coil to the electromagnetic coil 16 is sent from the excitation circuit, each coil is set to be excited so that the direction of the magnetic poles alternately changes between adjacent coils. As shown in FIG. 5 (2), the electromagnetic coils 16 may be connected in parallel.

  When a signal having a frequency for alternately switching the direction of the polarity of the excitation current supplied is applied to the electromagnetic coil 16 of the first magnetic body 10 from the excitation circuit (drive control circuit) 18A, As shown in FIGS. 1 to 4, a magnetic pattern is formed in which the polarity on the third magnetic body 14 side alternately changes from N pole → S pole → N pole. When the frequency pulse signal has a reverse polarity, a magnetic pattern is generated in which the polarity of the first magnetic body on the third magnetic body side alternately changes from S pole → N pole → S pole. As a result, the excitation pattern appearing in the first magnetic body 10 changes periodically.

  The structure of the second magnetic body 12 is the same as that of the first magnetic body 10, but the electromagnetic coil 18 of the second magnetic body is arranged so as to be displaced with respect to the electromagnetic coil 16 of the first magnetic body. The point is different. That is, as described in the claims, the arrangement pitch of the coils of the first magnetic body and the arrangement pitch of the coils of the second magnetic body are set to have a predetermined pitch difference (angle difference). Yes. This pitch difference is the distance that the permanent magnet (third magnetic body) 14 moves with respect to the coils 16 and 18 corresponding to one period (2π) of the frequency of the excitation current, that is, a pair of N pole and S pole. A distance corresponding to π / 2, which is 1/4 of the total distance, is preferable.

  Next, the third magnetic body 14 will be described. As shown in FIGS. 1 to 4, the third magnetic body 14 is disposed between the first magnetic body and the second magnetic body, and a plurality of permanent magnets having alternately opposite polarities. 20 (filled in black) are arranged in a line (straight line or arc) in a predetermined interval, preferably an equal interval. The arc shape includes a closed loop such as a complete circle or ellipse, an unspecified annular structure, a semicircle, or a fan shape.

  The first magnetic body 10 and the second magnetic body 12 are arranged, for example, in parallel via an equal distance, and the third magnetic body is located at the center position between the first magnetic body and the second magnetic body. 14 is arranged. In the third magnetic body, the arrangement pitch of the individual permanent magnets is almost the same as the arrangement pitch of the magnetic coils in the first magnetic body 10 and the second magnetic body 12.

  Next, the operation of the magnetic body structure in which the above-described third magnetic body 14 is disposed between the first magnetic body 10 and the second magnetic body 12 will be described with reference to FIGS. As shown in (1) of FIG. 1, the electromagnetic circuits 16 and 18 of the first magnetic body and the second magnetic body are provided at a certain moment by the excitation circuit described above (18 in FIG. 5 to be described later). Exciting pattern is generated.

  At this time, a magnetic pole is generated in a pattern of → S → N → S → N → S → on each coil 16 on the surface of the first magnetic body 10 facing the third magnetic body 14, and the second magnetic body 12 In the coil 18 on the surface facing the 3 magnetic body 14 side, magnetic poles are generated in a pattern of → N → S → N → S → N →. Here, an arrow displayed with a solid line in the figure indicates an attractive force, and an arrow displayed with a one-dot chain line indicates a reaction force.

  At the next moment, as shown in (2), when the polarity of the pulse wave applied to the first magnetic body via the drive circuit 18 (FIG. 5) is reversed, the first magnetic body 10 of (1) A repulsive force is generated between the magnetic pole generated in the coil 16 and the magnetic pole of the permanent magnet 20 on the surface of the third magnetic body 14, while the magnetic pole generated in the coil 18 of the second magnetic body 12 Since the attractive force is generated between the magnetic body 14 of the third magnetic body 14 and the magnetic poles on the surface of the permanent magnet, the third magnetic body sequentially moves in the right direction in the drawing as shown in (1) to (5). To do.

  A pulse wave that is out of phase with the exciting current of the first magnetic body is applied to the coil 18 of the second magnetic body 12, and as shown in (6) to (8), the second magnetic body The magnetic poles of the twelve coils 18 and the magnetic poles on the surface of the permanent magnet 20 of the third magnetic body 14 repel each other to move the third magnetic body 14 further to the right. (1) to (8) show the case where the permanent magnet has moved a distance corresponding to π, and (9) to (16) have moved the distance corresponding to the remaining π, that is, (1) Through (16), the third magnetic body moves relative to the first and second magnetic bodies by a distance corresponding to one period (2π) of the frequency signal supplied to the electromagnetic coils 16 and 18.

  In this manner, the third magnetic body 14 is slid linearly by supplying frequency signals having different phases to the first magnetic body (A phase) and the second magnetic body (B phase), respectively. Or the third magnetic body 14 can be rotated as a rotor.

  When the first magnetic body, the second magnetic body, and the third magnetic body are formed in an arc shape, the magnetic structure shown in FIG. 1 constitutes a rotating rotor. When these magnetic bodies are formed in a linear shape, The magnetic structure constitutes a linear motor. That is, a rotary drive body such as a motor can be realized by the structure of these magnetic bodies.

  According to this magnetic structure, since the third magnetic body can move by receiving magnetic force from the first magnetic body and the second magnetic body, the torque when moving the third magnetic body increases, Since the torque / weight balance is excellent, it is possible to provide a small motor that can be driven with high torque.

  FIG. 6 shows an excitation circuit (drive control circuit) for applying an excitation current to the first magnetic electromagnetic coil (A phase electromagnetic coil) 16 and the second magnetic electromagnetic coil (B phase electromagnetic coil) 18. It is a block diagram which shows an example. This excitation circuit is configured to supply controlled pulse frequency signals to the A-phase electromagnetic coil 16 and the B-phase electromagnetic coil 18, respectively. Reference numeral 30 denotes a crystal oscillator, and reference numeral 32I denotes a D-PLL circuit for generating a reference pulse signal by dividing the oscillation frequency signal by M.

  Reference numeral 34 denotes a sensor that generates a position detection signal corresponding to the rotational speed of the third magnetic body (in this case, the rotor) 14. As this sensor, a Hall sensor (magnetic sensor) or an optical sensor can be suitably selected. The number of holes corresponding to the number of permanent magnets is formed in the magnetic rotor. When this hole corresponds to the sensor, the sensor generates a pulse every time it passes through the hole. Symbol 34A is a phase A side sensor for supplying a detection signal to the driver circuit of the phase A electromagnetic coil, and symbol 34B is a phase B side sensor for supplying the detection signal to the driver circuit of the phase B electromagnetic coil. is there.

  The pulse signals from the sensors 34A and 34B are output to a driver 32 for supplying excitation current to the first and second magnetic bodies, respectively. Reference numeral 33 denotes a CPU which outputs a predetermined control signal to the D-PLL circuit 32I and the driver 32. Reference numeral 32G is an A-phase buffer that outputs an excitation signal to the A-phase coil, and 32H is a B-phase buffer that outputs an excitation signal to the B-phase coil.

  As shown in FIG. 7, the drive control unit includes an A phase coil, a B phase coil start control unit 302, and a sensor follow-up control unit 304. The start control unit controls the start of the motor due to the stress applied to the addition of the motor, and the sensor tracking control unit supplies the phase wave to each phase coil without the need to supply the fundamental wave to the buffer unit after the motor starts. An operation is performed in which the detected signal wave is made to follow the detection pulse from each phase sensor by feeding it back to the driver and is synchronized therewith. The frequency from the crystal oscillator 30 is divided by the D-PLL 32I, and this is supplied to the drive controller 300.

  In FIG. 7, a rotation start / stop instruction 306 and a rotation direction instruction 308 from the CPU 33 are input to the start control unit 302 and the sensor follow-up control unit 304. A multiplexer 310 switches between a control output from the start control unit and an output from the sensor following control unit. The output (fundamental wave) from the D-PLL 32I is supplied to the start control unit 302. The multiplexer 310 receives a switching command value for switching between the output from the start control unit 302 and the output from the sensor follow-up control unit 304 (A phase drive, B phase drive) from the start control unit 302 to the input terminal SEL of the multiplexer. Is output.

  The start control unit 302 outputs an output Ti for converting the control mode from the start control phase to the sensor follow-up control phase to the multiplexer 310 and the sensor follow-up control unit 304. Reference numeral 312 denotes a PWM control unit, which changes the duty ratio of the drive signal supplied to each phase coil based on the duty ratio command value 340 from the CPU 33.

  FIG. 8 shows a magnetic material according to the present invention embodied as a synchronous motor. (1) is a perspective view of the motor, (2) is a schematic plan view of the motor (third magnetic material), (3 ) Is a side view thereof, (4) is an A phase electromagnetic coil (first magnetic body), and (5) is a B phase electromagnetic coil (second magnetic body). The reference numerals given in FIG. 8 are the same as the corresponding components in the above-described drawings.

  This motor includes a pair of A-phase magnetic body 10 and B-phase magnetic body 12 corresponding to a stator, and includes the above-described third magnetic body 14 constituting the motor, and includes an A-phase magnetic body and a B-phase magnetic body. An annular rotor (third magnetic body) 14 is rotatably disposed around the shaft 37 between the body and the body. The rotary shaft 37 is press-fitted into the rotary shaft opening hole at the center of the rotor so that the rotor and the rotary shaft rotate integrally. As shown in FIGS. 8 (2), (4), and (5), the rotor is provided with six permanent magnets equally in the circumferential direction, and the polarities of the permanent magnets are alternately reversed. The stator is provided with six electromagnetic coils equally in the circumferential direction.

  The A-phase sensor 34A and the B-phase sensor 34B are provided on the case inner side wall of the A-phase magnetic body (first magnetic body) via a specific distance T (a distance corresponding to π / 2). The distance between the A phase sensor 34A and the B phase sensor 34B has a value corresponding to providing a predetermined phase difference between the frequency signal supplied to the A phase coil 16 and the frequency signal supplied to the B phase coil 18. Applied.

  As described above, a plurality of holes 35 are equally formed on the circumferential edge of the rotor (for example, the number of permanent magnets equally arranged in the circumferential direction of the rotor, six in this embodiment). Is formed. The sensor includes a light emitting unit and a light receiving unit. A member that constantly reflects infrared light from the light emitting part of the sensor and absorbs it when detecting the position is applied to the hole. The main body of the rotor is formed of an insulator or a conductor.

  Now, the A-phase / B-phase sensor generates a pulse each time the above-described hole 35 passes through the sensor while the rotor 14 is rotating. That is, the hole 35 is provided with a groove or a light absorbing material for absorbing light, and the light receiving part of the sensor does not receive the light emitted from the light emitting part every time the hole passes through the sensor. Therefore, the sensor generates a pulse wave at a predetermined frequency according to the rotational speed of the rotor 14 and the number of holes.

  The rotor is connected to a load, and a drive signal is supplied to the above-described electromagnetic coils 16 and 18 to rotate the rotor, thereby causing the rotor to perform power assist of the load. The start control unit 302 captures a signal from the A phase sensor or the B phase sensor at the beginning when stress is applied to the load, and outputs a drive signal only to the electromagnetic coil of either the A phase or the B phase. This corresponds to an idle period. The start control unit determines the rotation direction of the load, and supplies a drive signal to the remaining phase electromagnetic coils after the determination. This period corresponds to the entire driving period (sensor tracking control).

  During this period, since the drive signal is supplied to the two-phase electromagnetic coil, the rotor is rotated strongly. That is, the load can be driven by power assist. Such a power assist mechanism can be applied to an electric bicycle with power assist, for example. The CPU can determine the load driving direction based on the order and timing of the outputs from the A-phase sensor and the B-phase sensor.

  The degree of power assist can be achieved by changing the duty ratio of the drive current output to the two-phase electromagnetic coils during the entire drive period. For example, the stress applied to the load and the rotation speed of the load are detected, and when the stress is large and the rotation speed is low, it is determined that the assist is strongly required and the duty ratio is set to a large percentage, and in the opposite case, the assist is excessive. Judging that it is not necessary, the duty ratio is set to a small percentage.

  FIG. 9 is a waveform characteristic diagram of a drive signal whose duty ratio is controlled, and the duty ratio is changed under the control of the CPU during the H period of each of the A-phase and B-phase drive outputs. For example, the duty ratio may be set to 100% when the maximum torque of the motor (load) is necessary (when all assists are required), and the duty may be decreased at other times, for example, after shifting to constant speed operation of the motor. The CPU obtains a load change of the motor by measuring sensor outputs from the magnetic material on the A phase side and the magnetic material on the B phase side, and determines a predetermined duty ratio from a table set and stored in the memory. This drive signal is a rectangular wave AC signal whose polarity changes alternately, and a two-phase drive signal is supplied to each phase of the A-phase coil and the B-phase coil.

  FIG. 10 shows waveforms in the circuit of FIG. 7, where (1) is the output value of the A phase sensor, (2) is the output value of the B phase sensor, and (3) is the drive signal waveform to the A phase coil. , (4) are drive signal waveforms to the B-phase coil. a is the initial setting area, b is the standby area, c is the idle period described above, and d is the entire driving period described above.

  First, in the period a, the CPU outputs an H signal only to the A-phase electromagnetic coil for a predetermined time to set the position of the rotor 14 to the initial position. This is executed when the system power is turned on. Next, in the standby state b, the CPU waits for an output from each phase sensor. When the output from the sensor is input to the CPU, the CPU detects the moving direction (rotation direction) of the rotor from the sensor output value (b), and then sends a control status setting signal reaching the idle period c to the start control unit 302. With this setting, the start control unit supplies the drive signal only to the A-phase electromagnetic coil 34A in synchronization with the output value of the A-phase sensor. During this time, since the drive signal is supplied only to the one-phase electromagnetic coil, the load and the rotor 14 rotate in either direction. The CPU determines the load and the rotational direction of the rotor by looking at the output states of the A-phase sensor and B-phase sensor (b).

  When the CPU finishes the determination, it sends an output switching command to the multiplexer 310. As a result, the control status of the motor reaches the full drive control d. Upon receiving this command, the multiplexer switches the switch mechanism so that the output of the sensor tracking control unit 304 is sent to the PWM control unit 312. The sensor tracking control unit sends a drive rectangular wave signal to the A phase electromagnetic coil 10 in synchronization with the output value of the A phase sensor 34A, and sends a rectangular wave signal to the B phase electromagnetic coil 14 in synchronization with the B phase sensor output value. The pattern of each drive signal is such that the rotor is further rotated in the rotational direction of the rotor. The CPU may detect the stress applied to the load by a stress detection means (potentiometer or the like), and may determine that the assist control is necessary when the detected value is higher than a predetermined value.

  The sensor follow-up control unit 304 generates a drive signal to each phase coil from the output of each phase sensor (FIGS. 10 (3) and (4)) via a Philip flop (FIGS. 10 (5) and (6)). . During the sensor follow-up control period after the start is completed, the sensor follow-up control unit 304 does not use the output of the D-PLL to generate a drive signal to each phase coil. In the PWM control unit, the duty ratio of the drive output to each phase coil is changed or adjusted, or is controlled and sent to the buffer circuits 32G and 32H of each phase coil.

  According to the embodiment described here, the drive control unit forms the excitation signals for the A-phase magnetic body and the B-phase magnetic body so as to follow the output of the sensor. Corresponding excitation signals can be supplied to the magnetic material of each phase.

  FIG. 11 shows a detailed view of the aforementioned A-phase / B-phase buffer circuit (32G, H). This circuit includes switching transistors TR1 to TR4 for applying an exciting current made of a pulse wave to the A phase electromagnetic coil or the B phase electromagnetic coil. In addition, an inverter 35A is included.

  Now, when “H” is applied as a signal to the buffer circuit, TR1 is turned off, TR2 is turned on, TR3 is turned on, TR4 is turned off, and an exciting current having the direction of Ib is applied to the coil. On the other hand, when “L” is applied to the buffer circuit as a signal, TR1 is turned on, TR2 is turned off, TR3 is turned off, TR4 is turned on, and a current having a direction of Ia opposite to Ib is applied to the coil. The Accordingly, the excitation patterns of the A-phase electromagnetic coil and the B-phase electromagnetic coil can be changed alternately. This is as explained in FIG.

  In FIG. 10, the drive signal wave is supplied to both the A-phase coil and the B-phase coil, but either one or both may be selected according to the load state. This is achieved by the drive controller controlling the buffer circuit.

10: first magnetic member, 12: second magnetic member, 14: third magnetic member, 16, 18: electromagnetic coil, 20: permanent magnet, 300: driver for excitation drive side motor

Claims (6)

A stator and a mover are provided, and one of the stator and the mover is made of a permanent magnet alternately magnetized with a different polarity, and the other is made of an electromagnetic coil that can be alternately excited with a different polarity,
A drive control unit that outputs to the electromagnetic coil a drive signal composed of an alternating current signal that alternately switches the excitation pattern of the electromagnetic coil, and a position sensor of the mover,
The moving element is connected to a load, and the drive control unit determines a direction of stress with respect to the load, and synchronizes the driving signal for rotating the moving element in the direction with an output from the position sensor. A motor drive system configured to be formed and output to the electromagnetic coil. The stator is composed of two phases of a first magnetic body and a second magnetic body, and the mover is disposed between the magnetic bodies and is relative to the first and second magnetic bodies in a predetermined direction. A third magnetic body that is movable
Each of the first magnetic body and the second magnetic body has a configuration in which a plurality of electromagnetic coils that can be alternately excited with different polarities are arranged in order, and the third magnetic body has an alternating configuration. The first magnetic body and the second magnetic body are composed of an electromagnetic coil of the first magnetic body and a second magnetic body. 2. The motor control system according to claim 1, comprising a configuration in which the magnetic coil and the electromagnetic coil are arranged so as to have an arrangement pitch difference.   Form a phase in which a plurality of N sets, each having two excitation coils N / S pole side and S / N pole side as a set, are arranged at equal intervals, and at least two phases are provided for the excitation coil arrangement of each phase. 3. The motor control system according to claim 1 or 2, wherein the motor control system is arranged by providing an angular difference, which is used as the stator, and the phases are faced to each other and the moving element is provided therebetween.   The motor control system according to claim 1, wherein the drive control unit is a duty ratio control unit for the drive signal.   The motor control system according to claim 1, wherein the drive control unit includes means for selecting a stator to which a drive signal is supplied.   Multi-phase stator and mover, excitation means for exciting the stator alternately in different polarities, a load connected to the mover, a control circuit for outputting an excitation signal to the excitation means, and the movement Magnetizing means for alternately magnetizing the child to different polarities, and when a stress is applied to the load, the excitation signal is output to one phase of the stator of the control circuit, and then in the direction of the stress Means for controlling the control circuit to output the excitation signal to the remaining one-phase stator so that the load operates.

Images