A wirelessly powered brushless electrically excited synchronous motor

Abstract

The present invention belongs to the field of motors, and specifically relates to a wirelessly powered brushless electric excitation synchronous motor. An excitation device based on wireless power supply is installed on the rotating shaft of the brushless electric excitation synchronous motor. The transmitting end of the excitation device adopts a skeleton ring-shaped magnetic core and a double-pole annular transmitting coil, which is fixed to the outside of the electric excitation motor housing through non-conductive and non-magnetic mechanical materials, and connected to the external compensation topology and inverter source; the receiving end of the excitation device adopts three arc-shaped magnetic cores and arc-shaped receiving coils arrayed in the circumferential direction, which are fixed to the motor shaft by gluing and rotate synchronously with the motor rotor. The arc-shaped receiving coil of the excitation device is connected to the rotating rectifier and connected in series with the excitation winding of the electric excitation motor to generate an excitation magnetic field; there is an air gap between the transmitting end and the receiving end of the excitation device, and there is no electrical connection. The brushless electric excitation synchronous motor supplies power to the excitation winding based on wireless power transmission to realize brushless excitation of the motor. The present invention is to solve the problems of poor reliability, low safety, limited speed, easy wear of brush slip rings, and frequent maintenance in the existing electric excitation synchronous motor.

Description

Technical Field

[0001] The invention belongs to the field of motors, and in particular relates to a wirelessly powered brushless electrically excited synchronous motor. Background Art

[0002] In order to reduce costs and reduce the over-exploitation of rare earth permanent magnet materials, the electrically excited synchronous motor has re-entered the vision of various companies and research institutions. Compared with permanent magnet synchronous motors, electrically excited synchronous motors do not require permanent magnet excitation. In the high speed area, the magnetic field generated by the rotor can be controlled by adjusting the excitation current, thereby adjusting the speed. There is no need for weak magnetic current on the stator side, so that under the same conditions, the high speed area has higher efficiency. At the same time, it has the advantages of wide speed regulation range, low cost, strong overload capacity, and simple control, and has gradually become a research hotspot for motors in the fields of wind turbines, ship propulsion, electric vehicles, etc.

[0003] However, the traditional electric excitation motor needs to use brushes and slip rings to power the rotor excitation winding, which has a series of problems such as easy wear, poor reliability, short service life, easy sparks, poor contact, and limited rotation speed. Therefore, there is an urgent need for brushless excitation electric excitation motors to solve the above problems.

[0004] Brushless electric excitation motors have become the focus of research by scholars at home and abroad in the field of motors. Nanjing University of Aeronautics and Astronautics proposed an exciter-type brushless electric excitation motor, which realizes brushless excitation of the electric excitation motor by installing an auxiliary exciter, a rotating exciter and a main generator on the rotating shaft [Y. Li, B. Zhou, J. Weiand C. Han. Modeling of Starter / Generator Based on Three-stage Brushless Synchronous Machines, 2010 International Conference on Electrical and Control Engineering, China, 2010]. However, this method increases the size of the motor, resulting in a decrease in the power density of the motor. A Korean research team proposed a harmonic excitation method [SSH Bukhari. et al. A New Small-Scale Self-Excited Wound Rotor Synchronous Motor Topology [J]. IEEE Transactions on Magnetics, 2021], but this method affects the back electromotive force of the armature winding and increases the torque pulsation of the motor.

[0005] In view of the shortcomings of existing research, the present invention proposes a wirelessly powered brushless electrically excited synchronous motor, which uses wireless power transmission technology to realize wireless power supply of the rotor excitation winding and brushless excitation of the motor. The motor eliminates the brush and slip ring structure of the traditional electrically excited motor, solves the problems of easy wear and poor reliability of the traditional electrically excited motor; there is no need to change the internal structure of the traditional electrically excited motor, and the power density of the motor will not be reduced; it has a low leakage magnetic field, and the wireless power transmission part will not affect the motor shaft and the main magnetic field of the motor, and the efficiency is high; during the rotation of the motor, the input voltage of the excitation winding is constant, which will not affect the excitation power of the motor, thereby improving the application range of the electrically excited motor. Summary of the invention

[0006] The present invention provides a wirelessly powered brushless electrically excited synchronous motor, in order to solve the problems of poor reliability, low safety, limited speed, easy wear of brush slip rings, and frequent maintenance in existing electrically excited synchronous motors.

[0007] The present invention is achieved through the following technical solutions:

[0008] A wirelessly powered brushless electrically excited synchronous motor, wherein an excitation device based on wireless power supply is installed on the rotating shaft of the brushless electrically excited synchronous motor, wherein the transmitting end of the excitation device adopts a skeleton ring-shaped magnetic core and a double-pole annular transmitting coil, is fixed to the outside of the electrically excited motor casing by non-conductive and non-magnetic mechanical materials, and is connected to an external compensation topology and an inverter source;

[0009] The receiving end of the excitation device uses three arc-shaped magnetic cores and arc-shaped receiving coils arrayed in the circumferential direction, which are fixed to the motor shaft by gluing and rotate synchronously with the motor rotor. The arc-shaped receiving coil of the excitation device is connected to the rotating rectifier and then connected in series with the excitation winding of the electric excitation motor to generate an excitation magnetic field;

[0010] There is an air gap between the transmitting end and the receiving end of the excitation device, and there is no electrical connection. The brushless electric excitation synchronous motor supplies power to the excitation winding based on wireless power transmission to achieve brushless excitation of the motor.

[0011] Furthermore, the transmitting end skeleton ring-shaped magnetic core of the excitation device is composed of 3 end ring magnetic cores and 2n strip magnetic cores, wherein n is an integer and n≥6,

[0012] The strip-shaped magnetic cores are arranged in a circumferential direction and connected with two parallel end ring magnetic cores to form a closed magnetic circuit.

[0013] The transmitting end double-pole annular transmitting coil 12 of the excitation device is composed of three double-pole annular coil structures, each coil has m turns, is fixed to the inner surface of the three end ring cores, and the center plane coincides with the center plane of the end ring core; the three transmitting coils are connected in series in the circuit, and the winding directions of two adjacent transmitting coils are opposite; after the coil is energized, two equivalent magnetic poles are generated in the axial direction, and a closed loop is formed through the transmitting end skeleton ring-shaped core 11 and the receiving end arc core 13 to supply power to the receiving coil.

[0014] Furthermore, the circumferential angle between any two adjacent strip cores is 360° / n; the transmitting end skeleton ring-shaped magnetic core 11 is made of soft magnetic manganese-zinc ferrite material, and the thickness of the end ring magnetic core is the same as that of the strip core.

[0015] Furthermore, the transmitting coil uses high-frequency Litz wire or multi-strand enameled wire, which is led out through the gap between the strip magnetic cores and connected to the transmitting end power supply.

[0016] Furthermore, the receiving end type magnetic core of the excitation device is composed of three arc-shaped magnetic cores, and the three arc-shaped magnetic cores are arranged circumferentially along the circumferential direction, and the corresponding circumferential angle between two adjacent magnetic cores is 120°;

[0017] The receiving end coil of the excitation device is composed of 6 completely identical arc coils, using high-frequency Litz wire or multi-strand enameled wire; the length of each arc coil is less than 1 / 2 of the length lTc of the arc core 13 of the arc receiving end, and the width is less than the width of the arc core 13 of the arc receiving end; every two arc receiving coils are connected in reverse series along the axial direction to form a group of receiving coils, and the winding directions of two adjacent receiving coils are opposite and fixed to the outer surface of the arc core, forming a total of 3 groups of receiving coils; the 3 groups of receiving coils are connected in series and then connected to the resonant topology and the rotary transformer to supply power to the excitation winding.

[0018] 6. According to the wireless powered brushless electrically excited synchronous motor of claim 5, the three arc-shaped magnetic cores are arranged in an axial direction, the length of the arc-shaped magnetic core 13 at the arc receiving end is the same as the length of the skeleton ring-shaped magnetic core at the transmitting end, and the thickness is the same as the thickness of the skeleton ring-shaped magnetic core 11 at the transmitting end, and a soft magnetic manganese-zinc ferrite material is used.

[0019] The beneficial effects of the present invention are:

[0020] The present invention utilizes wireless power transmission technology to realize wireless power supply of rotor excitation winding, replaces the brush and slip ring structure of traditional electric excitation motor, solves the problems of easy wear of brush, poor reliability, poor contact, speed limitation, etc., and improves the service life of the motor and the safety and stability of operation; compared with traditional excitation methods such as harmonic excitation and exciter excitation, there is no need to change the internal structure of the motor, and the power density of the motor will not be reduced; the wireless excitation device has a self-shielding function, low leakage magnetic field, will not affect the motor shaft and the main magnetic field of the motor, has high efficiency, adopts a skeleton ring sleeve type magnetic core, has low cost and high power density; compared with exciter type and harmonic brushless excitation methods, the excitation power of the wireless excitation device is adjustable, the speed regulation range is expanded, and the power factor of the motor is improved, and during the constant speed rotation of the motor, the output voltage of the wireless excitation device is constant, which will not affect the excitation power of the motor. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 It is a schematic structural diagram of the wirelessly powered brushless electric excitation motor of the present invention.

[0022] Figure 2 This is a system block diagram of the wirelessly powered brushless electric excitation motor of the present invention.

[0023] Figure 3 It is a schematic diagram of the structure of the brushless excitation device based on wireless power supply described in the present invention.

[0024] Figure 4 for Figure 3 main view.

[0025] Figure 5 for Figure 3 Side view of.

[0026] Figure 6 It is a schematic diagram of the structure of the receiving coil and the magnetic core in the brushless excitation device of the present invention.

[0027] Figure 7 This is a main magnetic circuit diagram of the brushless excitation device based on wireless power supply described in the present invention.

[0028] Brushless excitation device 1; skeleton ring-shaped magnetic core 11; double-pole annular transmitting coil 12; arc-shaped magnetic core 13; receiving end double-pole annular coil 14; electromagnetic excitation motor 2; rotating shaft 3. DETAILED DESCRIPTION

[0029] The technical solutions in the embodiments of the present invention will be described clearly and completely below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0030] As attached Figure 1 As shown, a wirelessly powered brushless electrically excited synchronous motor described in the present invention has an excitation device 1 based on wireless power supply installed on a rotating shaft 3, the transmitting end of the excitation device 1 adopts a skeleton ring-shaped magnetic core 11 and a double-pole annular transmitting coil 12, which are fixed to the outside of the casing of the electrically excited motor 2 by non-conductive and non-magnetic mechanical materials; the receiving end of the excitation device 1 adopts three arc-shaped magnetic cores 13 and an arc-shaped receiving coil 14 arrayed in the circumferential direction, which are fixed to the motor rotating shaft 3 by gluing, and rotate synchronously with the motor rotor, and the arc-shaped receiving coil 14 is connected to the rotating rectifier and then connected in series with the excitation winding of the electrically excited motor 2 to generate an excitation magnetic field; there is an air gap between the transmitting end and the receiving end of the excitation device 1, and there is no electrical connection, and power is supplied to the excitation winding based on wireless power transmission.

[0031] As attached Figure 2 As shown, in the wirelessly powered brushless electrically excited synchronous motor described in the present invention, a dual-pole annular transmitting coil 12 of an excitation device 1 based on wireless power supply is connected to an external compensation topology and an inverter source, wherein the transmitting end compensation topology is series compensation, which is integrated with the inverter source to improve the power factor of the system; the inverter source generates a high-frequency AC voltage to generate a high-frequency current in the transmitting coil, thereby exciting a high-frequency magnetic field in space, and wirelessly transmitting energy to the arc-shaped receiving coil 14 on the rotating shaft 3; after generating an induced electromotive force, the arc-shaped receiving coil 14 is connected to the receiving end compensation topology fixed on the rotating shaft 3 and then connected to the rotating rectifier, and then connected in series with the excitation winding of the electrically excited motor 2 through a wire to generate an excitation current;

[0032] The rotating part of the excitation device rotates synchronously with the motor rotor, realizing brushless excitation of the electromagnetic motor 2. During the rotation of the motor, the total mutual inductance between the double-pole annular transmitting coil 12 and the arc-shaped receiving coil 14 of the excitation device 1 remains unchanged, and the excitation power of the electromagnetic motor 2 can be kept constant under the premise of a fixed transmitting current.

[0033] During the speed regulation of the electromagnetic motor 2, the armature winding current and the rotor excitation power can be coordinated to adjust the speed; by controlling the output voltage of the inverter source at the transmitting end, the output power of the arc receiving coil 14 is changed, and then the excitation current is controlled to achieve the purpose of regulating the air gap magnetic density of the motor and controlling the output characteristics of the motor.

[0034] As attached Figure 3 To Attachment Figure 5As shown, the transmitting end skeleton ring-shaped magnetic core 11 of the excitation device 1 is composed of 3 end ring magnetic cores and 2n strip magnetic cores, wherein n is an integer and n≥6, the strip magnetic cores are arranged in a circumferential direction, and two end ring magnetic cores placed in parallel are connected to form a closed magnetic circuit, and the circumferential angle between any two adjacent strip magnetic cores is 360° / n; the transmitting end skeleton ring-shaped magnetic core 11 is made of soft magnetic manganese-zinc ferrite material, and the thickness of the end ring magnetic core is the same as that of the strip magnetic core; the double-pole type The annular transmitting coil 12 is composed of three double-pole annular coil structures, each coil has m turns, and is fixed to the inner surface of three end ring magnetic cores by gluing or other means, and the center plane coincides with the center plane of the end ring magnetic core; the three double-pole annular transmitting coils 12 are connected in series in the circuit, and the winding directions of two adjacent double-pole annular transmitting coils 12 are opposite; the double-pole annular transmitting coil 12 uses high-frequency Litz wire or multi-strand enameled wire, which is led out through the gap between the strip magnetic cores and connected to the transmitting end power supply;

[0035] As attached Figure 6 As shown, the receiving end magnetic core of the excitation device is composed of three arc-shaped magnetic cores 13, which are arranged in a circumferential direction, and the corresponding circumferential angle between two adjacent magnetic cores is 120°; along the axial direction, the length of the receiving end arc-shaped magnetic core 13 is the same as the length of the transmitting end skeleton ring-shaped magnetic core 11, and the thickness of the receiving end arc-shaped magnetic core 13 is the same as the thickness of the transmitting end skeleton ring-shaped magnetic core 11, and soft magnetic manganese-zinc ferrite material is used; the receiving end coil is composed of 6 completely identical arc-shaped coils, and high-frequency Litz wire or multi-strand enameled wire is used; the length of each arc-shaped receiving coil 14 is slightly less than the length l of the arc-shaped magnetic core 13 Tc 1 / 2 of the width, and the width is slightly smaller than the width of the arc-shaped magnetic core 13 at the arc-shaped receiving end; every two arc-shaped receiving coils 14 are connected in reverse series along the axial direction to form a group of receiving coils, and the winding directions of two adjacent arc-shaped receiving coils 14 are opposite, and they are fixed to the outer surface of the arc-shaped magnetic core 13 by gluing, forming a total of 3 groups of receiving coils; the 3 groups of arc-shaped receiving coils 14 are connected in series and then connected to the resonant topology and the rotary transformer to supply power to the excitation winding. Furthermore, the transmitting end of the excitation device and the receiving end of the excitation device are installed in a coaxial and co-center plane manner, that is, the outer end face of the transmitting end skeleton ring-shaped magnetic core 11 is aligned with the outer end face of the receiving end arc-shaped magnetic core 13, at this time, the arc-shaped receiving coil 14 is directly opposite to the dual-pole annular coil 12 of the transmitting end, the coupling degree is the highest, and the output power and transmission efficiency are the highest; there is an air gap distance between the transmitting coil and the receiving coil, and the length of the air gap distance should be less than 0.08l Tc When the air gap distance does not meet the above conditions, the coupling coefficient between the transmitting and receiving coils decreases rapidly, the excitation power is small, and the excitation of the electromagnetic motor 2 cannot be achieved normally.

[0036] The following is an explanation of the main magnetic field distribution generated by the excitation device. Figure 7 As shown, the currents passed through the two adjacent dual-pole annular transmitting coils 12 are in opposite directions, so the dual-pole annular transmitting coils 12 generate two equivalent magnetic poles in the axial direction after being energized, and a closed loop is formed through the transmitting end skeleton ring-shaped magnetic core 11 and the receiving end arc-shaped magnetic core 13 to supply power to the arc-shaped receiving coil 14; the windings of the two arc-shaped receiving coils in the single group of arc-shaped receiving coils 14 are opposite, and are connected after being connected in anti-phase series, so the induced voltages in the two arc-shaped receiving coils 14 are superimposed on each other, and after the total induced voltage is generated, a direct current is output through the rotary transformer to supply power to the electric excitation winding; during the rotation of the electric excitation motor 2, the transmitting end skeleton ring-shaped magnetic core 11 and the transmitting end dual-pole annular transmitting coil 12 are stationary, while the receiving end arc-shaped magnetic core 13 and the receiving coil rotate synchronously with the rotating shaft. During the rotation, the mutual inductance between the dual-pole annular transmitting coil 12 and the arc-shaped receiving coil 14 remains basically constant, and the constant excitation power during the rotation of the motor can be achieved by controlling the output voltage of the inverter source to be constant. Through the annular magnetic core 11 at the transmitting end skeleton and the arc-shaped magnetic core 13 at the receiving end, the main magnetic flux forms a closed main magnetic circuit. At the same time, the size of the arc-shaped magnetic core 13 at the receiving end is larger than the receiving coil, which can well shield the leakage magnetic field generated by the receiving coil and will not generate induction loss in the metal shaft of the motor; outside the wireless excitation device, the direction of the magnetic field generated by the transmitting coils on both sides is opposite to the direction of the magnetic field generated by the excitation coil in the middle position. Therefore, the main magnetic fields generated by the three double-pole annular coils 12 in the main magnetic circuit part are superimposed on each other, and the leakage magnetic fields generated outside the excitation device cancel each other out, so that the wireless excitation device described in the present invention has good electromagnetic compatibility and low leakage magnetic field characteristics.

Claims

1. A wirelessly powered brushless electrically excited synchronous motor, characterized in that: An excitation device based on wireless power supply is installed on the rotating shaft of the brushless electric excitation synchronous motor. The transmitting end of the excitation device adopts a skeleton ring-shaped magnetic core and a double-pole annular transmitting coil, which is fixed to the outside of the electric excitation motor casing through non-conductive and non-magnetic mechanical materials, and is connected to the external compensation topology and inverter source; The receiving end of the excitation device uses three arc-shaped magnetic cores and arc-shaped receiving coils arrayed in the circumferential direction, which are fixed to the motor shaft by gluing and rotate synchronously with the motor rotor. The arc-shaped receiving coil of the excitation device is connected to the rotating rectifier and then connected in series with the excitation winding of the electric excitation motor to generate an excitation magnetic field; There is an air gap between the transmitting end and the receiving end of the excitation device, and there is no electrical connection. The brushless electric excitation synchronous motor supplies power to the excitation winding based on wireless power transmission to achieve brushless excitation of the motor; The transmitting coil of the excitation device is composed of three double-pole annular coil structures, each coil has m turns, fixed on the inner surface of three end ring magnetic cores, and the center plane coincides with the center plane of the end ring magnetic core; the three transmitting coils are connected in series in the circuit, and the winding directions of two adjacent transmitting coils are opposite; after the coil is energized, two equivalent magnetic poles are generated in the axial direction, and a closed loop is formed by the transmitting end magnetic core and the receiving end magnetic core to supply power to the receiving coil, and the circumferential angle between any two adjacent strip magnetic cores is 360° / n; the transmitting end magnetic core is made of soft magnetic manganese-zinc ferrite material, and the thickness of the end ring magnetic core is the same as that of the strip magnetic core; The receiving end coil of the excitation device is composed of 6 completely identical arc coils, using high-frequency Litz wire or multi-strand enameled wire; the length of each arc coil is less than 1 / 2 of the length lTc of the arc receiving end magnetic core, and the width is less than the width of the arc receiving end magnetic core; every two arc receiving coils are connected in reverse series along the axial direction to form a group of receiving coils, and the winding directions of two adjacent receiving coils are opposite and fixed to the outer surface of the arc magnetic core, forming a total of 3 groups of receiving coils; the 3 groups of receiving coils are connected in series and then connected to the resonant topology and the rotary transformer to supply power to the excitation winding; The transmitting end skeleton ring-shaped magnetic core of the excitation device is composed of 3 end ring magnetic cores and 2n strip magnetic cores, where n is an integer and n≥6. The strip-shaped magnetic cores are arranged in a circumferential direction and connected to two end ring magnetic cores placed in parallel to form a closed magnetic circuit; The receiving end type magnetic core of the excitation device is composed of three arc-shaped magnetic cores, and the three arc-shaped magnetic cores are arranged in a circumferential direction, and the corresponding circumferential angle between two adjacent magnetic cores is 120°.

2. A wirelessly powered brushless electrically excited synchronous motor according to claim 1, characterized in that: The transmitting coil adopts high-frequency Litz wire or multi-strand enameled wire, which is led out through the gap between the strip-shaped magnetic cores and connected to the transmitting end power supply.

3. The wirelessly powered brushless electrically excited synchronous motor according to claim 1, characterized in that: The three arc-shaped magnetic cores are made of soft magnetic manganese-zinc ferrite material, and the length of the arc-shaped receiving end magnetic core is the same as the length of the transmitting end skeleton ring-shaped magnetic core, and the thickness is the same as the thickness of the transmitting end magnetic core along the axial direction.

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