Hollow cup ring winding reluctance type rotary transformer of axial magnetic circuit

Abstract

The invention discloses a coreless annular winding reluctance type rotary transformer of an axial magnetic circuit. The coreless annular winding reluctance type rotary transformer comprises a cup-shaped stator iron core, an annular excitation winding, a signal winding and a salient pole type rotor iron core. The excitation winding and the signal winding are arranged in a hollow cup of the stator iron core; high-frequency alternating current is connected to the excitation winding to generate an alternating magnetic field to generate an axial magnetic path between the stator iron core and the rotor iron core; non-uniform air gaps are formed between stator and rotor tooth poles and periodically change along with the rotation of the rotor, and the signal winding induces an electric signal changing along with the angle of the rotor; the two groups of rotary transformers are staggered at a certain angle to output sine and cosine signals through signal windings, and the position of a rotor core is obtained through a position decoding circuit. According to the rotary transformer, the high-permeability integral iron core is formed or the soft magnetic composite material is integrally pressed into the cup shape, the machining complexity is reduced, loss is reduced during high-frequency operation, meanwhile, all parts can be machined at the same time, the transformation ratio of the rotary transformer can be flexibly adjusted through the annular winding, and the machining period can be shortened.

Description

Technical Field

[0001] The invention belongs to the field of rotary transformer type position sensors, and in particular relates to a hollow cup annular winding reluctance rotary transformer with an axial magnetic circuit. Background Art

[0002] In the field of modern control, position signals are one of the most important feedback quantities and are usually obtained by position sensors. Common types of position sensors are mainly photoelectric encoders and resolvers. Photoelectric encoders convert position information into digital signals through gratings, which has the advantage of high precision, but poor environmental adaptability. Motor jitter or external vibration factors will affect the accuracy; resolvers are electromagnetic sensors composed of stators and rotors. They obtain the angular displacement and angular velocity of the rotating shaft of rotating objects through the conversion of analog signals. They have the advantages of simple structure, reliable operation and strong anti-interference ability. Compared with wound resolvers, reluctance resolvers have the advantages of small size, simple structure and long life, and are often used in various electric transmission equipment and position signal sensing elements in servo drive systems. The core of the existing reluctance rotary transformer is made of laminated silicon steel sheets, and the stator and rotor cores adopt a salient pole structure. The excitation winding and sine and cosine signal winding of the reluctance rotary transformer are wound on the stator teeth according to a certain rule. On the one hand, the silicon steel sheet has a large loss in the high-frequency magnetic field operating environment, which affects the detection accuracy; on the other hand, due to the influence of the sensor processing link, the stator and rotor laminated with silicon steel sheets have the problems of poor processing accuracy and complicated processing flow; in addition, the conventional reluctance rotary transformer generates a radial magnetic circuit through the excitation winding to excite the sine / cosine signal winding. Both the excitation winding and the sine / cosine signal winding are wound in the stator tooth slots to complete the radial magnetic circuit closure of the reluctance rotary transformer. The winding is greatly affected by the processing accuracy of the stator, and the winding of the winding after the stator is formed increases the production cycle of the reluctance rotary transformer. Summary of the invention

[0003] In view of the problems existing in the prior art, the present invention provides a hollow cup annular winding reluctance rotary transformer with an axial magnetic circuit, which has low operating loss, simple structure and is more suitable for large-scale production.

[0004] To solve the above technical problems, the present invention provides the following technical solutions: a hollow cup annular winding reluctance rotary transformer with an axial magnetic circuit, characterized in that it includes: a stator core, an excitation winding, a signal winding, and a rotor core; the excitation winding and the signal winding are installed in the hollow cup of the stator core, and the stator core, the rotor core, the excitation winding and the signal winding are coaxial; the rotor core rotates along the axial direction of the stator core.

[0005] Furthermore, the aforementioned stator core and salient pole reluctance rotor core are both formed by integrally pressing a high magnetic permeability, high frequency and low eddy current loss integral core material or a soft magnetic composite material.

[0006] Furthermore, the aforementioned stator core adopts a claw pole structure with hollow cup teeth and slots alternately arranged, the excitation winding 3 and the signal winding are annular windings, and the rotor core is a salient pole reluctance rotor core.

[0007] Furthermore, the aforementioned excitation winding and signal winding are respectively wound on two annular iron cores or are wound in parallel on one annular iron core. When they are respectively wound on two annular iron cores, the excitation winding is installed close to the stator core side, and the signal winding is installed close to the rotor core side; the excitation winding and the signal winding are placed in the annular cup groove of the stator core through the winding bracket, and both adopt the annular winding method to wind the coil turns according to the preset transformation ratio requirements.

[0008] Furthermore, the aforementioned excitation winding is connected to a high-frequency alternating current to generate a high-frequency alternating magnetic field to produce an axial magnetic path between the stator core and the rotor core; the air gap between the stator core and the rotor core is an uneven air gap, and changes periodically with the rotation angle of the rotor core, and the signal winding induces an electrical signal containing position signal information that changes with the rotor core angle, and an electrical signal that changes with the rotor core position is obtained through a position decoding circuit.

[0009] Furthermore, the aforementioned number of salient poles P of the rotor core and the number of teeth Z of the stator core satisfy: Z=P, forming a reluctance rotary transformer with 2, 3, or 4 different pole numbers.

[0010] Furthermore, there is an electrical angle difference of 90° between the aforementioned stator cores or rotor cores, and the signal windings on both sides output two electrical signals with a phase difference of 90° that changes with the rotor core angle, which respectively represent the sine and cosine signals of the position high-frequency modulated electrical signal, and the mechanical angle of the rotor is obtained through the position decoding circuit.

[0011] Compared with the prior art, the beneficial technical effects of the present invention using the above technical solution are as follows:

[0012] 1. Through high magnetic permeability integral core molding or one-piece pressing of soft magnetic composite materials, the processing complexity is reduced, and the operating loss of the rotary transformer is reduced during high-frequency operation.

[0013] 2. The excitation winding and signal winding adopt the form of annular winding, which is more conducive to processing and production and changing the transformation ratio; at the same time, with the integrated pressed stator and rotor, the processing of various components of the hollow cup annular winding reluctance rotary transformer with axial magnetic circuit can be carried out simultaneously, which is conducive to shortening the processing cycle. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1A schematic diagram of a hollow cup annular winding reluctance rotary transformer with an axial magnetic circuit adopted by the present invention.

[0015] Figure 2(a) is a hysteresis curve of a conventional silicon steel sheet.

[0016] FIG. 2( b ) is a hysteresis curve diagram of the soft magnetic composite material used in the present invention.

[0017] Figure 3 The figure is a schematic diagram of the axial magnetic circuit of the hollow cup annular winding reluctance rotary transformer with axial magnetic circuit adopted by the present invention.

[0018] Figure 4 This is a schematic diagram of the 90° staggered installation of the hollow cup annular winding reluctance rotary transformer with axial magnetic circuit adopted by the present invention.

[0019] Figure 5 This is a schematic diagram of the periodic output of the hollow cup annular winding reluctance rotary transformer with an axial magnetic circuit adopted by the present invention.

[0020] In the figure: 1- stator core; 2- excitation winding; 3- signal winding; 4- rotor core. DETAILED DESCRIPTION

[0021] In order to better understand the technical content of the present invention, specific embodiments are described below in conjunction with the accompanying drawings.

[0022] Various aspects of the invention are described herein with reference to the accompanying drawings, in which many illustrative embodiments are shown. The embodiments of the invention are not limited to those described in the accompanying drawings. It should be understood that the invention is implemented by any of the various concepts and embodiments described above, as well as the concepts and embodiments described in detail below, because the concepts and embodiments disclosed in the invention are not limited to any implementation. In addition, some aspects disclosed in the invention may be used alone or in any appropriate combination with other aspects disclosed in the invention.

[0023] like Figure 1 As shown, the present invention provides a hollow cup annular winding reluctance rotary transformer with an axial magnetic circuit, comprising a stator core 1; an excitation winding 2; a signal winding 3; and a rotor core 4.

[0024] The stator core 1 is formed by forming a high-permeability integral core or a soft magnetic composite material into a hollow cup structure. The outer side of the hollow cup adopts a claw pole structure, the inner side adopts a hollow cylindrical structure, and the middle part is hollowed out to accommodate the excitation winding and the signal winding; the rotor core 4 is made of silicon steel sheets, a whole electromagnet or a soft magnetic composite material, and the rotor core 4 adopts a reluctance salient pole structure. The salient pole rotor tooth part adopts an arc tooth pole, and the arc of the arc tooth pole is determined by the required air gap. The salient pole rotor core and the outer claw pole structure of the hollow cup stator form an uneven air gap; the excitation winding 2 and the signal winding 3 are composed of a ring core and winding, and the number of coil turns is wound according to the transformation ratio requirements. The voltage transformation ratio can be flexibly changed by changing the number of winding turns of the excitation winding 2 and the signal winding 3. The excitation winding 2 and the signal winding 3 are arranged in the hollow cup of the stator core 1, and the excitation winding 2 is arranged at the bottom of the hollow cup of the stator core 1. The stator core 1, the rotor core 4, the excitation winding 2 and the signal winding 3 are coaxial; the rotor core 1 rotates along the axial direction of the stator core 4. The uneven air gap between the hollow cup-shaped claw pole structure of the stator core 1 and the rotor core 4 changes periodically with the rotation angle of the rotor core 4. The excitation winding 2 is supplied with a high-frequency sinusoidal AC voltage, and the signal winding outputs an induced voltage with the same periodic change with the periodic uneven air gap.

[0025] The stator core 1 and the rotor core 4 of the hollow cup annular winding reluctance rotary transformer with an axial magnetic circuit proposed by the present invention are formed by high magnetic permeability integral core molding or soft magnetic composite material integral pressing molding. As shown in FIG2 (a) the hysteresis curve of the traditional silicon steel sheet and FIG2 (b) the hysteresis curve of the soft magnetic composite material used in the present invention, in high-frequency working conditions, the hysteresis curve of the soft magnetic composite material used is smaller in area than the hysteresis curve of the silicon steel sheet, which is suitable for the high-frequency excitation frequency of the rotary transformer, and can effectively reduce the AC loss during operation, and increase the overall working efficiency and detection sensitivity of the rotary transformer.

[0026] The winding of the hollow cup annular winding reluctance rotary transformer with axial magnetic circuit proposed by the present invention is not on the stator teeth. Figure 1 As shown, compared with the traditional radial magnetic circuit reluctance rotary transformer, the present invention adopts an annular winding, a hollow cup-shaped claw pole stator core and a reluctance salient pole rotor core, and its magnetic circuit will form a closed loop along the axis direction through the stator core 1 and the rotor core 4. The magnetic flux path of the axial magnetic circuit is as shown in FIG. Figure 3 The excitation winding 2 and the signal winding 3 are coupled through the axial magnetic circuit. When a high-frequency sinusoidal AC voltage is applied to the excitation winding 2 and the rotor core 4 rotates, the closed magnetic circuit will change periodically with the uneven air gaps in the cup-shaped claw-pole stator teeth and the salient-pole rotor, and an alternating voltage signal related to the position will be induced in the signal winding.

[0027] The hollow cup annular winding reluctance rotary transformer with axial magnetic circuit proposed in the present invention takes into account the requirements of modularization and simplified production and processing. The annular winding, hollow cup claw pole stator core and reluctance salient pole rotor core in the rotary transformer can be processed independently; its single side can be regarded as an independent module, and the whole rotary transformer can be realized by combining two independent modules. The single side is defined as sine or cosine induction signal output according to the needs. When combining, the two rotary transformers need to be connected with an electrical angle of 90° staggered, such as Figure 4 As shown. Figure 4 In the staggered stator core connection shown, the stator tooth angles of the two unilateral independent modules are staggered by 11.25°. When the motor shaft drives the resolver rotor to rotate, the combined resolver will simultaneously output sine and cosine voltage signals containing position information.

[0028] When the hollow cup annular winding reluctance rotary transformer proposed by the present invention is in working state, the rotor core 4 rotates with the motor shaft, and the uneven air gap between the stator core 1 and the rotor core 4 of the rotary transformer will change periodically. The change of the air gap size causes the magnetic resistance in the axial magnetic flux path to change; at the same time, a periodic sinusoidal AC voltage is passed through the annular excitation winding, and the signal winding will periodically change the corresponding output size according to the change of electromagnetic induction and magnetic resistance, and the frequency and the sinusoidal AC voltage passed through the excitation winding are kept consistent with the induced voltage, such as Figure 5 When the motor shaft drives the resolver rotor to rotate, since the stator tooth angles of the reluctance resolver of the two modules differ by 90°, when the high-frequency sinusoidal AC voltage E is applied to the excitation winding, f When the signal windings on both sides induce an alternating voltage U with a phase difference of 90° s and U c , any side can be defined as a sine signal or a cosine signal. The annular winding reluctance rotary transformer with an axial magnetic circuit proposed in the present invention will output sine and cosine signals on both sides at the same time, and decode the speed and position signal of the motor through the sine and cosine voltage signals.

[0029] The hollow cup annular winding reluctance rotary transformer with axial magnetic circuit proposed by the present invention adopts composite soft magnetic materials to reduce the operating loss of the rotary transformer; the processing difficulty of the stator and rotor is reduced by an integrated processing technology, and the processing flow is reduced; the overall assembly difficulty of the rotary transformer is further reduced by adopting the method of annular winding and axial magnetic circuit; since each assembly part is independently produced, the overall production time of the rotary transformer is reduced, and the relative independence of each spare part also reduces the difficulty of repairing the rotary transformer after damage. In summary, the rotary transformer proposed by the present invention realizes the low loss and low cost design of the rotary transformer with axial magnetic circuit through the application of new materials and innovative structural design.

[0030] Although the present invention has been described above with preferred embodiments, it is not intended to limit the present invention. A person skilled in the art of the present invention may make various modifications and improvements without departing from the spirit and scope of the present invention. Therefore, the scope of protection of the present invention shall be determined by the definition of the claims.

Claims

1. A hollow cup toroidal winding reluctance rotary transformer with an axial magnetic circuit, characterized in that: include: A cup-shaped stator core (1), an annular excitation winding (2), an annular signal winding (3), and a salient-pole reluctance rotor core (4); the excitation winding (2) and the signal winding (3) are installed in the hollow cup of the stator core (1); the stator core (1), the rotor core (4), the excitation winding (2), and the signal winding (3) are coaxial; and the rotor core (4) rotates along the axial direction of the stator core (1).

2. The hollow cup annular winding reluctance rotary transformer with an axial magnetic circuit according to claim 1, characterized in that: The stator core (1) and the salient pole reluctance rotor core (4) are both formed by integrally pressing a high magnetic permeability, high frequency and low eddy current loss integral core material or a soft magnetic composite material.

3. The hollow cup annular winding reluctance rotary transformer with an axial magnetic circuit according to claim 1, characterized in that: The stator core (1) adopts a claw pole structure with hollow cup teeth and slots interlaced, the exciting winding (2) and the signal winding (3) are annular windings, and the rotor core (4) is a salient pole reluctance rotor core.

4. The hollow cup annular winding reluctance rotary transformer with an axial magnetic circuit according to claim 1, characterized in that: The excitation winding (2) and the signal winding (3) are respectively wound on two annular cores or are wound in parallel on one annular core. When the excitation winding (2) and the signal winding (3) are respectively wound on the two annular cores, the excitation winding (2) is installed close to the stator core (1) and the signal winding (3) is installed close to the rotor core (4). The excitation winding (2) and the signal winding (3) are placed in the annular cup groove of the stator core (1) through a winding bracket, and both adopt an annular winding method to carry out coil turns winding according to the preset transformation ratio requirements.

5. The hollow cup annular winding reluctance rotary transformer with an axial magnetic circuit according to claim 1, characterized in that: The excitation winding (2) is connected to a high-frequency alternating current to generate a high-frequency alternating magnetic field to generate an axial magnetic path between the stator core (1) and the rotor core (4); the air gap between the stator core (1) and the rotor core (4) is an uneven air gap, and changes periodically with the rotation angle of the rotor core (4); the signal winding (3) senses an electrical signal containing position signal information that changes with the angle of the rotor core (4), and the electrical signal that changes with the position of the rotor core (4) is obtained through a position decoding circuit.

6. The hollow cup annular winding reluctance rotary transformer with an axial magnetic circuit according to claim 1, characterized in that: The number of salient poles P of the rotor core (4) and the number of teeth Z of the stator core (1) satisfy: Z=P, forming a reluctance type rotary transformer with different pole numbers of 2, 3, and 4.

7. The hollow cup annular winding reluctance rotary transformer with an axial magnetic circuit according to claim 1, characterized in that: There is an electrical angle difference of 90° between the stator cores (1) or between the rotor cores (4), and the signal windings (3) on both sides output two electrical signals with a phase difference of 90° that change with the angle of the rotor core (4), which respectively represent the sine and cosine signals of the position high-frequency modulated electrical signal, and the mechanical angle of the rotor is obtained through a position decoding circuit.

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