A multi-emission type anti-offset loosely coupled transformer and its compensation circuit

Abstract

The present invention discloses a multi-emission, anti-deviation, loosely coupled transformer for rotary ultrasonic machining. The transformer comprises an annular secondary core and three arcuate primary cores. A secondary coil is wound around the radial outer wall of the secondary core, and the primary cores are provided with a primary coil. Several of the primary cores are equally spaced and arranged on the radial outer wall of the secondary core, with gaps defined between the secondary cores and the opposing sides of the primary cores. The primary cores of the multi-emission loosely coupled transformer are arranged at equal angles around the secondary core, improving the transformer's coupling coefficient and ensuring uniform magnetic flux distribution between the primary and secondary cores. Regardless of the direction in which the secondary cores deviate, the overall coupling coefficient fluctuation range of the transformer remains minimal.

Description

Technical Field

[0001] The present invention relates to the technical field of contactless power transmission, and in particular to a multi-emission anti-deviation loosely coupled transformer and a compensation circuit thereof for rotary ultrasonic machining. Background Art

[0002] With the continuous development of materials science, new hard and brittle materials, such as sapphire, carbon fiber composites, and new ceramics, are finding widespread application in consumer electronics, advanced optics, aerospace, and other fields due to their high-temperature resistance, wear resistance, and high hardness. However, these excellent physical properties also present significant challenges in machining. As a new specialty machining technology, rotary machining, with its advantages of long tool life, excellent machining quality, and high precision, has proven to be an effective method for machining these new hard and brittle materials.

[0003] Unlike traditional machine tool tools, ultrasonic tools usually have an integrated transducer, which is driven by an ultrasonic power supply and converts electrical energy into mechanical energy through the inverse piezoelectric effect, thereby generating micron-level amplitude at the tool end to assist in processing. There are two existing solutions for powering ultrasonic tools: contact power transmission represented by carbon brushes and conductive slip rings, and non-contact power transmission represented by rotating loosely coupled transformers. Among them, non-contact power transmission has the advantages of no speed limit, no friction, and good safety, and is gradually replacing the former. In actual processing, it is often necessary to replace multiple ultrasonic tools according to the actual processing technology. In order to meet the flexibility of automatic tool changing, scholars and engineers have designed a loosely coupled transformer with an arc-shaped main side magnetic core, such as patents CN107104514A and CN107124042A, to achieve automatic tool changing during machine tool processing. However, in actual applications, it was found that this new type of loosely coupled transformer not only has a low coupling coefficient, which easily causes core saturation, but also requires extremely high assembly precision of the machine tool. After changing the tool, the slight offset of the original and secondary cores will cause large fluctuations in the transformer coupling coefficient, affecting the transmission efficiency and output power, and ultimately affecting the consistency of the workpiece being processed. Summary of the Invention

[0004] In response to the existing shortcomings of the new loosely coupled transformer, the present invention proposes a multi-emission anti-offset loosely coupled transformer and its compensation circuit, which not only improves the coupling coefficient of the loosely coupled transformer, but also achieves stable power transmission even if a certain relative offset occurs between the primary and secondary magnetic cores, while also maintaining the flexibility of automatic tool changing of machine tools.

[0005] In order to solve the above technical problems, the technical solution of the present invention is:

[0006] A multi-emission anti-bias loosely coupled transformer includes a ring-shaped secondary magnetic core and three arc-shaped primary magnetic cores. The radial outer wall of the secondary magnetic core is wound with a secondary coil, and the primary magnetic core is provided with a primary coil. The three primary magnetic cores are equally arranged on the radial outer wall of the secondary magnetic core, and a gap is provided between the opposite sides of the secondary magnetic core and the primary magnetic core.

[0007] Preferably, a groove is provided on the inner side of the main side magnetic core, and the main side coil is wound around the main side magnetic core along the groove.

[0008] Preferably, the radial outer wall of the secondary magnetic core is provided with an annular groove, and the secondary coil is wound on the annular groove.

[0009] Preferably, the core angle α of the main side magnetic core is 60°.

[0010] Preferably, the main side coils of the three main side magnetic cores have the same winding direction and number of coil turns.

[0011] The present invention also discloses a compensation circuit for the above-mentioned multi-emission anti-offset loosely coupled transformer, including a power supply input voltage U i , the equivalent series resistance R of the three main side coils P1 、R P2 、R P3 , the self-inductance L of the three main side coils P1 、L P2 、L P3 , the self-inductance L of the secondary coil S , the equivalent series resistance R of the secondary coil S , the equivalent impedance R of the ultrasonic transducer t and equivalent capacitive reactance X t , the power input voltage U i The output terminals are connected to three equivalent series resistors R P1 、R P2 、R P3 One end of the three equivalent series resistors R P1 、R P2 、R P3 The other end of the corresponding three main side coils are connected to the self-inductance L P1 、L P2 、L P3 One end of the three main side coils is connected to the self-inductance L P1 、L P2 、L P3 The other end is grounded, and the self-inductance of the secondary coil is L S , the equivalent series resistance R of the secondary coil S , the equivalent impedance R of the ultrasonic transducer t and equivalent capacitive reactance X tConnected in series, the self-inductance L of the secondary coil S The self-inductance L of the three main side coils P1 、L P2 、L P3 Mutual induction.

[0012] Preferably, the power input voltage U i The equivalent series resistance R of the three main coils P1 、R P2 、R P3 A main side compensation capacitor C is added between P .

[0013] As a preference, the self-inductance L of the secondary coil S and equivalent capacitive reactance X t A secondary compensation capacitor C is set between S .

[0014] The present invention has the following characteristics and beneficial effects:

[0015] Using this technical solution, the primary cores of a multi-emitter loosely coupled transformer are arranged at equal angles around the secondary cores. This not only improves the transformer's coupling coefficient but also ensures a uniform magnetic flux distribution between the primary and secondary cores. Regardless of the direction in which the secondary cores shift, the overall coupling coefficient fluctuation range of the transformer is minimal. Secondly, an anti-offset compensation circuit suitable for multi-emitter loosely coupled transformers is provided. The secondary capacitors are used to match the inductance of the secondary coils, while a single primary capacitor is used to match the inductance of all primary coils. This treats all primary coils as a whole, reducing inductance changes during offsets. Ultimately, this maintains the system's output power and transmission efficiency within a stable range, ensuring consistent machining quality during rotary ultrasonic machining. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0017] Figure 1 A schematic diagram of the magnetic core structure of a multi-emission anti-skew loosely coupled transformer according to an embodiment of the present invention.

[0018] Figure 2 An overall schematic diagram of a multi-emission anti-skew loosely coupled transformer according to an embodiment of the present invention.

[0019] Figure 3The embodiment of the present invention provides a multi-emission contactless power transmission mutual inductance coupling model.

[0020] In the figure, 1-secondary magnetic core, 2-primary magnetic core, 3-groove, 4-annular groove, 5-gap, 6-primary coil, 7-secondary coil. DETAILED DESCRIPTION

[0021] It should be noted that, in the absence of conflict, the embodiments of the present invention and the features in the embodiments may be combined with each other.

[0022] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the present invention. In addition, the terms "first", "second", etc. are only used for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, features defined as "first", "second", etc. may explicitly or implicitly include one or more of the features. In the description of the present invention, unless otherwise specified, "multiple" means two or more.

[0023] In the description of the present invention, it should be noted that, unless otherwise expressly specified or limited, the terms "mounted," "connected," and "connected" should be understood in a broad sense. For example, they may refer to fixed connections, detachable connections, or integral connections; mechanical connections or electrical connections; direct connections or indirect connections through an intermediate medium; and internal communication between two components. Those skilled in the art will understand the specific meanings of the above terms in the present invention based on specific circumstances.

[0024] The present invention provides a multi-emission anti-skew loosely coupled transformer, such as Figure 1 and Figure 2As shown, it includes a ring-shaped secondary magnetic core 1 and three arc-shaped main magnetic cores 2. The radial outer wall of the secondary magnetic core 1 is wound with a secondary coil 7, and the main magnetic core 2 is provided with a main coil 6. The three main magnetic cores 2 are equally arranged on the radial outer wall of the secondary magnetic core 1, and a gap 5 is provided between the opposite sides of the secondary magnetic core 1 and the main magnetic core 2. A groove 3 is provided on the inner side of the main magnetic core 2, and the main coil 6 is wound on the main magnetic core 2 along the groove. An annular groove 4 is provided on the radial outer wall of the secondary magnetic core 1, and the secondary coil 7 is wound on the annular groove 4. The core angle α of the main magnetic core 2 is 60°. The winding direction and number of turns of the main coils 6 of the three main magnetic cores are the same.

[0025] Specifically, the three primary magnetic cores 2 surround the secondary magnetic core 1 at intervals of 360° / 3=120°.

[0026] As can be understood, in practical applications of the above technical solution, three primary cores 2 are assembled on an ultrasonic machine tool. When a tool change is required, one or more of the primary cores can be moved, thereby enabling the ultrasonic tool equipped with the secondary core 1 to move laterally or vertically, thus meeting the flexibility required for tool changes. In this case, after moving the primary core 2, the secondary core 1 can then move laterally with the ultrasonic tool.

[0027] Furthermore, a through hole is provided in the center of the secondary magnetic core 1 for assembling an ultrasonic cutter.

[0028] In the above technical solution, the primary magnetic cores of the multi-emission loosely coupled transformer are arranged at equal angles around the secondary magnetic cores, which not only has a simple structure, but also improves the coupling coefficient of the transformer, while making the magnetic flux distribution of the primary and secondary magnetic cores uniform. Regardless of the direction in which the secondary magnetic cores are offset, the overall coupling coefficient fluctuation range of the transformer is very small, so that the output power and transmission efficiency of the system are maintained within a stable range, ensuring the consistency of the processing quality of rotary ultrasonic machining.

[0029] The present invention also discloses a compensation circuit for the above-mentioned multi-emission anti-offset loosely coupled transformer, such as Figure 3 As shown, including the power input voltage U i , the equivalent series resistance R of the three main side coils P1 、R P2 、R P3 , the self-inductance L of the three main side coils P1 、L P2 、L P3 , the self-inductance L of the secondary coil S , the equivalent series resistance R of the secondary coil S , the equivalent impedance R of the ultrasonic transducer t and equivalent capacitive reactance X t , the power input voltage Ui The output terminals are connected to three equivalent series resistors R P1 、R P2 、R P3 One end of the three equivalent series resistors R P1 、R P2 、R P3 The other end of the corresponding three main side coils are connected to the self-inductance L P1 、L P2 、L P3 One end of the three main side coils is connected to the self-inductance L P1 、L P2 、L P3 The other end is grounded, and the self-inductance of the secondary coil is L S , the equivalent series resistance R of the secondary coil S , the equivalent impedance R of the ultrasonic transducer t and equivalent capacitive reactance X t Connected in series, the self-inductance L of the secondary coil S The self-inductance L of the three main side coils P1 、L P2 、L P3 Mutual induction.

[0030] Through the above technical solution, we can obtain L P1 and L P2 、L P2 and L P3 、L P1 and L P3 The mutual inductance between them is M 12 , M 23 , M 13 ;L P1 、L P2 、L P3 With L S The mutual inductance between them is M 1S 、M 2S and M 3S .

[0031] According to the coupling coefficient calculation formula of multi-emission loosely coupled transformer

[0032]

[0033] It is found that when the primary and secondary cores are offset, the coupling coefficient K does not fluctuate much because all the primary cores are regarded as a whole.

[0034] Furthermore, in order to compensate for the reactive power in the entire circuit and reduce the current stress of the power supply, it is necessary to compensate the entire current. The coupling model of the multi-transmitter contactless power transmission in the present invention proposes an anti-offset compensation method of series-series capacitors.

[0035] Specifically, the power input voltage U i The equivalent series resistance R of the three main coils P1 、R P2 、R P3 A main side compensation capacitor C is added between P .

[0036] It can be understood that, unlike the traditional compensation method, the anti-offset compensation method of the present invention does not compensate each main side coil individually, but rather compensates the main side coil self-inductance L P1 、L P2 、L P3 Perform parallel connection, since L P1 =L P2 =L P3 =L Pi , L Pi is the self-inductance corresponding to the i-th main side coil, where i = 1, 2, 3…n, and the main side inductance L after parallel equivalent P =L P1 / n, so the primary side compensation capacitance is

[0037] When the primary and secondary cores are relatively offset, the self-inductance of one part of the primary coil will decrease while the self-inductance of the other part will increase, which will eventually make the equivalent primary inductance L P The fluctuation is not large, so the main side compensation capacitor C P Reactive power compensation can still be performed on circuits with certain offsets.

[0038] Specifically, the self-inductance L of the secondary coil S and equivalent capacitive reactance X t A secondary compensation capacitor C is set between S .

[0039] It can be understood that the secondary compensation capacitor C S Mainly used to compensate for the secondary coil self-inductance L S And the transducer equivalent capacitive reactance X t ,therefore where ω s =2πf s is the series resonant frequency f of the connected transducer s The corresponding angular frequency, X ts is the equivalent capacitive reactance of the transducer operating at the resonant frequency.

[0040] In this embodiment, the above technical solution is specifically analyzed through Table 1 and Table 2:

[0041]

[0042]

[0043] Table 1 Parameters of multi-emission loosely coupled transformer at offset

[0044] Table 1 shows the coupling coefficient fluctuation diagram of the multi-emission loosely coupled transformer when offset occurs. It can be seen that when a small offset occurs, the coupling coefficient K only increases slightly and the change is very small.

[0045] Transmission efficiency Output power Initial state 91.18％ 4.6028 (Horizontal 74.50％ 4.2945 (Horizontal 68.24％ 4.155

[0046] Table 2 Transmission efficiency and output power changes of multi-transmitter loosely coupled transformers at offset

[0047] Table 2 is a table showing the changes in transmission efficiency and output power of a multi-transmitter loosely coupled transformer when offset occurs. It can be seen that even when a slight offset occurs, the multi-transmitter anti-offset loosely coupled transformer and its compensation circuit of the present invention can maintain relative stability in output power and transmission efficiency, thereby ensuring the processing quality of rotary ultrasonic machining.

[0048] The embodiments of the present invention are described in detail above with reference to the accompanying drawings, but the present invention is not limited to the described embodiments. It will be apparent to those skilled in the art that various changes, modifications, substitutions, and variations of these embodiments, including components, without departing from the principles and spirit of the present invention are still within the scope of protection of the present invention.

Claims

1. A multi-emission anti-skew loosely coupled transformer, characterized in that: The invention comprises an annular secondary magnetic core (1) and three arc-shaped primary magnetic cores (2), wherein a secondary coil (7) is wound around the radial outer wall of the secondary magnetic core (1), and a primary coil (6) is provided on the primary magnetic core (2). The three primary magnetic cores (2) are equally spaced and arranged on the radial outer wall of the secondary magnetic core (1), a gap (5) is provided between the opposite sides of the secondary magnetic core (1) and the primary magnetic core (2), a groove (3) is provided on the inner side of the primary magnetic core (2), and the primary coil (6) is wound around the primary magnetic core (2) along the groove, an annular groove (4) is provided on the radial outer wall of the secondary magnetic core (1), and the secondary coil (7) is wound around the annular groove (4), and the winding direction and number of coil turns of the primary coils (6) on the three primary magnetic cores (2) are the same.

2. The multi-emission anti-skew loosely coupled transformer according to claim 1, wherein: The core angle α of the main side magnetic core (2) is 60°.

3. A compensation circuit for a multi-emission anti-skew loosely coupled transformer according to claim 1 or 2, characterized in that: Including power input voltage U i , the equivalent series resistance R of the three main side coils P1 、R P2 、R P3 , the self-inductance L of the three main side coils P1 、L P2 、L P3 , the self-inductance L of the secondary coil S , the equivalent series resistance R of the secondary coil S , the equivalent impedance R of the ultrasonic transducer t and equivalent capacitive reactance X t , the power input voltage U i The output terminals are connected to three equivalent series resistors R P1 、R P2 、R P3 One end of the three equivalent series resistors R P1 、R P2 、R P3 The other end of the corresponding three main side coils are connected to the self-inductance L P1 、L P2 、L P3 One end of the three main side coils is connected to the self-inductance L P1 、L P2 、L P3 The other end is grounded, and the self-inductance of the secondary coil is L S , the equivalent series resistance R of the secondary coil S , the equivalent impedance R of the ultrasonic transducer t and equivalent capacitive reactance X t Connected in series, the self-inductance L of the secondary coil S The self-inductance L of the three main side coils P1 、L P2 、L P3 Mutual induction.

4. The multi-emission anti-skew loosely coupled transformer compensation circuit according to claim 3, characterized in that: The power input voltage U i The equivalent series resistance R of the three main coils P1 、R P2 、R P3 A main side compensation capacitor C is added between P .

5. The multi-emission anti-skew loosely coupled transformer compensation circuit according to claim 3, characterized in that: The self-inductance L of the secondary coil S and equivalent capacitive reactance X t A secondary compensation capacitor C is set between S .

Images