CN105656282A - Linear permanent magnet servo motor with embedded position detection device - Google Patents

Abstract

The present invention proposes an embedded position detection method of a linear permanent magnet servo motor, aiming at the mechanically divided permanent magnet array inside the linear permanent magnet servo motor, using a tunneling reluctance (TMR) chip to realize the motion position detection of the linear permanent magnet servo motor Embedded detection. The embedded sensor includes a spatially orthogonal TMR chip combined with a time grid signal processing system. The embedded sensor moves with the mover, so that the TMR chip senses the periodic magnetic field distribution of the mechanically divided permanent magnet to generate a voltage output. The grid signal processing system realizes the position measurement of the linear permanent magnet servo motor. The invention has simple structure, convenient assembly and strong reliability, breaks through the traditional method of installing an independent grating position sensor in the linear motor, and has the advantages of compact motor structure size, enhanced anti-interference performance and effective cost reduction.

Description

A Linear Permanent Magnet Servo Motor with Embedded Position Detection Device

technical field

The invention belongs to the technical field of linear permanent magnet servo motors and relates to the position detection technology of the motors.

Background technique

With the development of advanced manufacturing technologies such as ultra-high-speed cutting and ultra-precision machining, various performance indicators of machine tools have been given higher requirements. In particular, higher requirements are put forward for the servo performance of the feed system of the machine tool: high driving thrust, fast feed speed and extremely high fast positioning accuracy. In order to meet the ever-increasing requirements, a transmission device that directly converts electrical energy into linear motion mechanical energy without any intermediate conversion mechanism - linear servo motor came into being and has achieved considerable development.

At present, the most widely used linear permanent magnet AC servo motor motion position detection method is usually to use a side-mounted linear grating for detection. Although the measurement accuracy of this method is high, on the one hand, it causes an inevitable increase in the size of the motor, and the operating performance of the linear motor is affected by the installation effect of the position sensor; on the other hand, the grating position detection method relies on mechanical precision equal divisions Line, measurement accuracy will be affected by machining accuracy.

In recent years, a time grating position detection technology that directly uses mechanical equalization to realize metering equalization has appeared, and has developed high-precision circular and linear time grating position sensors, and further proposed a method based on the measured object. A parasitic time grating position detection method with mechanical bisection characteristics. However, the existing parasitic time grating position detection technology is based on the principle of electromagnetic induction and uses a coil for detection, and the coil winding is difficult to ensure uniformity and the volume is usually large, making it difficult to effectively apply this detection method to linear motors.

Contents of the invention

The purpose of the present invention is to propose a linear permanent magnet servo motor with an embedded position detection device, aiming at reducing the volume and cost of the linear permanent magnet servo motor by replacing the existing external position detection sensor of the linear motor , to promote the wider application of linear servo motors.

In order to achieve the above object, the present invention adopts the following technical solutions:

The invention is aimed at the mechanically divided permanent magnet array inside the linear permanent magnet servo motor. Based on the time grating position measurement principle, the embedded detection of the motion position of the linear permanent magnet servo motor is realized by using a tunneling reluctance (TMR) chip.

The linear permanent magnet servo motor with an embedded position detection device proposed by the present invention includes a stator, a mover and an embedded position detection device.

The stator includes a mechanically divided permanent magnet array and a yoke for fixing the permanent magnets, and the mover includes a magnetic core and a coil group wound thereon.

The embedded position detection device includes an embedded position sensing head, an excitation module and a time grid signal processing system; Composed of TMR chips, the embedded position sensing head is fixed on the mover. The embedded position sensing head is fixed on any position on the mover that can feel the magnetic field generated by the mechanically divided permanent magnet. The length of the embedded position sensing head The direction is parallel to the moving direction of the mover; the embedded position sensing head applies sine excitation and cosine excitation to each group of TMR chips respectively through the excitation module to realize the time orthogonality of the excitation signal, and then in the process of moving with the mover , by feeling the periodic magnetic field distribution of the mechanically divided permanent magnet array on the stator of the linear permanent magnet servo motor, two signals and outputs are obtained, and the synthesized signal is input to the time grid signal processing system, and finally the position of the linear permanent magnet servo motor is realized. embedded detection. The above embedded position detection device is applicable to any linear permanent magnet servo motor including the mechanically divided permanent magnet array.

As a preferred solution, the space-orthogonal TMR chip set usually uses two TMR chips to form a set. The sensitive directions of the two TMR chips in each set of spatially orthogonal TMR chips are placed along the same direction, and the sensitive directions can be placed along the moving direction of the motor mover or perpendicular to the moving direction of the motor mover.

As a preferred solution, assuming that the center distance between two adjacent permanent magnets in the mechanically divided permanent magnet array is 2 l , and the center distance between two TMR chips in the group is L , then the spatial orthogonality must satisfy the relationship L= ( 2 n + 1) l .

As a preferred solution, the space-orthogonal TMR chipset, under the excitation of the time-orthogonal signal, will generate a signal reflecting the position change along with the linear motor movement, which is processed by a known time-grid signal processing system. After amplification, filtering, phase demodulation, and calculation of motion displacement, the motion position of the linear permanent magnet servo motor is finally obtained.

Preferably, the embedded position sensing head can use multiple sets of space-orthogonal TMR chips, and the outputs of multiple sets of TMR chips are averaged to improve measurement accuracy. Further, in order to save space, when multiple sets of TMR chips are used, the two TMR chips of one set are alternately arranged with the TMR chips of another set.

Compared with the prior art, the present invention has significant advantages in that:

The embedded position detection sensor head composed of the PCB bottom plate and the TMR chipset has a simple structure, small size and is easy to be integrated with any existing linear permanent magnet servo motor containing the mechanically divided permanent magnet array, which will not increase the size of the motor The increase of the linear servo motor will not cause additional carrying load; directly use the mechanically divided permanent magnet array inside the linear motor for position detection, and the position signal of the linear servo motor for motion control can be realized. Compared with the current Generally used linear grating, this method has low cost, strong environmental adaptability, and high reliability; the embedded position detection device has a simple structure and low cost, which is a great technological breakthrough for the position sensing technology of linear permanent magnet servo motors With innovation, it has broad application prospects in the field of linear permanent magnet servo motors.

Description of drawings

Fig. 1 is a schematic structural diagram of the embedded position detection method of a single-layer linear permanent magnet servo motor according to the present invention.

Fig. 2 is a schematic structural diagram of a method for detecting the embedded position of a double-layer linear permanent magnet servo motor according to the present invention.

Fig. 3 is a schematic diagram of the structure of a single spatially orthogonal TMR chipset in which the chip sensitive direction is perpendicular to the moving direction.

Fig. 4 is a schematic diagram of the structure of a single spatially orthogonal TMR chipset in which the chip sensitive direction is parallel to the moving direction.

Fig. 5 is a schematic structural diagram of a dual-group space-orthogonal TMR chip set in which the chip sensitive direction is parallel to the moving direction.

Fig. 6 is a schematic diagram of the distribution of magnetic force lines of a single-layer mechanically divided permanent magnet in an embodiment of the present invention.

Fig. 7 is a schematic diagram of the distribution of magnetic force lines of a double-layer mechanically divided permanent magnet in an embodiment of the present invention.

detailed description

It is easy to understand that, according to the technical solution of the present invention, those skilled in the art can imagine various implementations of the present invention without changing the essence and spirit of the present invention. Therefore, the following specific embodiments and drawings are only exemplary descriptions of the technical solution of the present invention, and should not be regarded as the entirety of the present invention or as a limitation or limitation on the technical solution of the present invention.

Referring to FIG. 1 , for a linear permanent magnet servo motor 1 with a mechanically equally divided permanent magnet array 112 , the embedded position detection device includes a PCB bottom plate 21 and a spatially orthogonal TMR chip 22 attached to it along the length direction of the PCB bottom plate 21 . Embedded position sensing head 2, excitation module 3 and time grating signal processing system 4. The embedded position sensor head 2 is fixed on the mover 12 of the linear permanent magnet servo motor 1 , and the length direction of the sensor head 2 is parallel to the moving direction of the mover 12 of the linear permanent magnet servo motor 1 . The sensing head 2 applies sine excitation and cosine excitation to the two TMR chips respectively through the excitation module 3, so as to realize the time orthogonality of the excitation signals, and then in the process of moving with the mover 12, by feeling the linear permanent magnet servo motor stator Mechanically divide the magnetic field distribution around the permanent magnet array 112 on 11 to obtain two signal outputs, and the synthesized signals are input to the time grid signal processing system 4, and finally realize the embedded detection of the position of the linear permanent magnet servo motor.

The present invention is not only applicable to the linear permanent magnet servo motor 1 with a single-layer mechanically divided permanent magnet array, but also applicable to any linear permanent magnet servo motor with a mechanically divided permanent magnet array. With reference to FIG. 2 , the application of the embedded position detection device on the linear permanent magnet servo motor 6 with a double-layer mechanically equally divided permanent magnet array 612 is described. The embedded position sensing head 2 is also fixed on the mover 62 of the linear permanent magnet servo motor 6. Similarly, as long as the length of the embedded position sensing head 2 can be guaranteed without affecting the operation of the linear permanent magnet servo motor The direction is parallel to the moving direction of the motor, and the embedded position sensing head 2 can be fixed on any installable area on the mover 62 .

Below in conjunction with Fig. 3, Fig. 4 and Fig. 5, the embedded position sensing head 2 is further described in detail as follows:

The TMR chip 22 has a definite magnetic field sensitive direction. When the measured magnetic field direction is consistent with the sensitive direction of the TMR chip 22, the output of the TMR chip 22 is maximum; otherwise, when the measured magnetic field direction is perpendicular to the sensitive direction of the TMR chip 22, the TMR chip 22 has the smallest output. At the same time, the magnetic fields generated by the single-layer and double-layer mechanically divided permanent magnet arrays 112 and 612 are widely distributed in the surrounding space, and there may be magnetic field components in all directions. Therefore, the embedded position sensing head 2 can be fixed on any installable area on the mover 62 of the mover 12 . Even in the fixing manner shown in FIG. 1 and FIG. 2 , there are also multiple placement forms of the TMR chip 22 on the PCB bottom plate 21 .

It can be seen from FIG. 3 that two spatially orthogonal TMR chips 22 are pasted on the PCB base 21 of the embedded position sensing head 2 . The sensitive direction of the TMR chip 22 is perpendicular to the length direction of the PCB bottom plate 21 . When the embedded position sensing head 2 is fixed on the mover 12 or 62 parallel to the moving direction of the mover 12, the sensitive direction of the TMR chip 22 is also perpendicular to the moving direction of the motor.

Referring to FIG. 4 , it further shows that the sensitive direction of the TMR chip 22 is arranged parallel to the length direction of the PCB bottom plate 21 .

Both Fig. 3 and Fig. 4 show the situation that only two TMR chips 22 are pasted on the embedded position sensing head 2 to form a group of spatially orthogonal. In addition, multiple sets of space-orthogonal TMR chipsets can be attached to the embedded position sensor head 2, and the outputs of multiple sets of TMR chipsets can be averaged to further improve the measurement accuracy.

FIG. 5 shows an embedded position sensing head structure with two sets of spatially orthogonal TMR chipsets 22 . In order to save space, the first and third TMR chips from the left are spatially orthogonal, and the remaining two TMR chips are spatially orthogonal. The first and second TMR chips from the left can be excited by the same sine (or cosine) signal, and the third and fourth TMR chips from the left can be excited by the same cosine (or sine) signal.

In conjunction with Fig. 6 and Fig. 7, the magnetic field line distribution of two forms of linear permanent magnet servo motor 1 described in the present invention is illustrated: for a linear permanent magnet servo motor 1 with a single-layer mechanically divided permanent magnet array 112, its single-layer The mechanically equally divided permanent magnet array 112 is composed of a plurality of rectangular permanent magnets magnetized along the thickness direction in a manner of alternately placing magnetic poles, and the distribution of magnetic force lines around it is shown in FIG. 6 . It can be seen that the lines of magnetic force are alternately distributed around the multiple permanent magnets. The magnetic field components in the left and right directions of the upper and lower regions of the permanent magnet array 112 are discussed below: in the region between two permanent magnets, the magnetic field components in the left and right directions are the largest, and in the central region of the permanent magnets, the magnetic field components in the left and right directions are the smallest.

For the linear permanent magnet servo motor 2 with a double-layer mechanically divided permanent magnet array 612 , the distribution of magnetic force lines around it is shown in FIG. 7 . It can be seen that the lines of magnetic force are alternately distributed around the multiple permanent magnets. The distribution of the magnetic field components in the upper and lower regions of the permanent magnet array 612 is the same as the distribution of the magnetic field components in the upper and lower regions of the single-layer permanent magnet array 112 . The magnetic field distribution between the layers of the double-layer permanent magnet array 612 is very complicated, so the requirements for the installation position of the embedded position sensing head are higher. A slight change in the installation position may cause a drastic change in the magnetic field distribution.

For the spatial orthogonality between each group of TMR chips 22 in the embedded position sensor head 2, as shown in Figure 6 and Figure 7, it is assumed that the center distance between two adjacent permanent magnets in the mechanically divided permanent magnet array is 2 l , the distance between the centers of two TMR chips in the group is L, as shown in Figure 3, Figure 4 and Figure 5, then the spatial orthogonality must satisfy the relationship L= (2 n+ 1) l .

Next, in conjunction with the embedded position sensing head 2 shown in FIG. 4 , it is placed on the permanent magnet array 112 parallel to the direction of motion of the motor, that is, it is placed on the upper area of the permanent magnet array 112 from left to right in FIG. 6 for analysis. . Since the two TMR chips are orthogonal in space, when one of the TMR chips is located in the area between the two permanent magnets and the other TMR is located in the central area of the permanent magnet, the output signals of the two TMR chips have a phase difference of 90°. With the movement of the mover, the spatial orthogonal characteristics of the two TMR chips remain unchanged, and the output signal phases of the two TMR chips always differ by 90°.

The embedded position sensing head 2 moves with the mover, so that the TMR chip senses the periodic magnetic field distribution of the mechanically divided permanent magnet to generate a voltage output. Under the action of the time-orthogonal excitation signal, the two TMR chips output two The signals are added to obtain the signal with position information required by the time grid signal processing system 4, and finally output the motion position information of the linear motor after being processed by the time grid signal processing system 4, so as to realize the motion position measurement of the linear permanent magnet servo motor.

Claims (6)

1. A linear permanent magnet servo motor with an embedded position detection device, comprising a stator and a mover, the stator comprising a mechanically bisected permanent magnet array and a yoke for fixing the permanent magnets, the mover comprising a magnetic core and a winding The coil group on it; it is characterized in that: It also includes an embedded position detection device, which includes an embedded position sensing head, an excitation module and a time grid signal processing system; The embedded position sensing head is composed of a PCB bottom plate and at least one group of spatially orthogonal TMR chips attached to it along the length direction of the board. Each group has two pieces. The embedded position sensing head is fixed on the mover to sense mechanical Any position of the magnetic field generated by the permanent magnet array is equally divided, and the length direction of the embedded position sensing head is parallel to the moving direction of the mover; The excitation module is connected with the embedded position sensing head, and the sine excitation and cosine excitation are respectively applied to each group of two TMR chips through the excitation module to realize the time orthogonality of the excitation signal. Mechanically divide the periodic magnetic field distribution of the permanent magnet array on the stator of the permanent magnet servo motor to obtain two signal outputs; The time grid signal processing system is connected with the embedded position sensing head, and the signal obtained after the synthesis of the two signals is input into the time grid signal processing system, and finally realizes the embedded detection of the position of the linear permanent magnet servo motor. 2. the linear permanent magnet servo motor with embedded position detection device as claimed in claim 1, is characterized in that, the sensitive direction of two TMR chips in each group of TMR chips of described spatial orthogonality is placed along same direction, and sensitive direction It can be placed along the moving direction of the motor mover or perpendicular to the moving direction of the motor mover. 3. The linear permanent magnet servo motor with embedded position detection device as claimed in claim 1, is characterized in that, the center distance of two adjacent permanent magnets in the mechanical equal division permanent magnet array is 2 l , two in each group The center distance of a piece of TMR chip is L , then the spatial orthogonality must satisfy the relationship L= (2 n+ 1) l . 4. have the linear permanent magnet servomotor of embedded position detecting device as claimed in claim 1, it is characterized in that, the mechanical equal division permanent magnet of described linear permanent magnet servomotor is a single-layer or double-layer structure, embedded position detection The devices are all fixed on the linear motor mover. 5. the linear permanent magnet servo motor with embedded position detection device as claimed in claim 1, is characterized in that, described embedded position sensing head adopts the TMR chip of multiple groups of space orthogonality, the output of multiple groups of TMR chips passes through Average processing, thereby improving measurement accuracy. 6. The linear permanent magnet servo motor with an embedded position detection device as claimed in claim 6, wherein when multiple sets of TMR chips are used, the two TMR chips of one set are arranged alternately with the TMR chips of another set.