CN103560632A - Brushless excitation mechanism based on wireless transmission of electric energy - Google Patents

Abstract

The invention discloses a brushless excitation mechanism based on wireless transmission of electric energy. The mechanism comprises a high frequency excitation source, an auxiliary excitation transmitting coil, an auxiliary excitation receiving coil, a rotating rectifier bridge, a soft magnetism optimization layer and a metal shielding layer, wherein the high frequency excitation source and the auxiliary excitation transmitting coil are arranged outside a motor, the auxiliary excitation receiving coil, the rotating rectifier bridge, the soft magnetism optimization layer and the metal shielding layer are arranged in the motor, an electromagnetic field of an excitation system is optimized and shielded through soft magnetism materials and metal materials, an excitation coil of a rotor of the alternating-current motor is supplied with power through the wireless transmission of the electric energy, mechanical connection between the rotor and external terminals is avoided, and brushless excitation of the motor is achieved.

Description

A brushless excitation mechanism based on wireless power transmission

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technical field

The patent of the present invention relates to a brushless excitation mechanism based on wireless transmission of electric energy.

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Background technique

The traditional brushless DC motor realizes the inverter function through the inverter composed of power electronic devices, that is, the commutator and brush are replaced by electronic commutation. Three-phase windings are arranged on the stator, and permanent magnet poles are arranged on the rotor. According to the change of the rotor position, the on-off of the corresponding devices in the inverter is controlled, so that the stator windings are energized in turns in a certain order, so that the rotor can rotate continuously under the drive of the electromagnetic torque. The brushless excitation of the synchronous motor uses an AC exciter with a rotating armature. The armature winding is arranged on the rotor, and the excitation winding is placed on the stator. When the exciter rotates with the synchronous generator, the rotor armature winding of the exciter cuts the stator excitation field. The induced electromotive force is directly connected to the rotor winding of the synchronous generator for excitation after being rectified by the rectifier that rotates synchronously with the rotor armature, without the need for components such as collector rings and brushes. There are also brushless motors that use the inductive coupling between the primary and secondary sides of the resolver to transmit power to achieve the purpose of brushless excitation. However, for brushless DC motors, the control system becomes more complicated due to the position judgment by sensors, and the requirements for the reliability of the control system are very high. The excitation method of the rotary rectifier of the AC motor is composed of the AC exciter and its own stator excitation system, which has a complex structure and high cost. The magnetic core design and manufacturing process of the resolver, the winding method of the winding, etc. have a great influence on the excitation system. Since the secondary side works in a rotating state, a necessary gap is required to ensure its safety, and the efficiency of power transmission will be reduced. , and the existence of the transformer core also increases the weight and volume of the motor. Using wireless power transmission to supply power to the excitation winding can effectively solve the above problems.

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Contents of the invention

Technical problem: The present invention provides a brushless excitation mechanism based on wireless transmission of electric energy, which can realize electric energy transmission between the dynamic and static mechanisms of the motor, reduce the weight of the electric motor, and improve the working reliability.

Technical solution: The brushless excitation mechanism based on wireless power transmission of the present invention includes a high-frequency excitation power supply and an auxiliary excitation transmitting coil arranged outside the motor, and an auxiliary excitation receiving coil arranged inside the motor, a rotating rectifier bridge, and a soft magnetic optimization layer and metal shielding layer, the soft magnetic optimization layer and metal shielding layer isolate the excitation system from other parts inside the motor, and the rotating shaft of the motor rotor passes through the opening on the soft magnetic optimization layer and the metal shielding layer to connect with the auxiliary excitation receiving coil and The rotating rectifier bridge is installed and connected. The auxiliary excitation transmitting coil is connected to the high-frequency excitation power supply after the capacitor is connected in series to form an LC resonance circuit. The auxiliary excitation receiving coil is connected to the AC terminal of the rotating rectifier bridge after the capacitor is connected in series to form an LC resonance circuit. In the electric circuit, the outgoing wires of the DC terminals of the rotary rectifier bridge pass through the soft magnetic optimization layer and the metal shielding layer in sequence, and then are connected to the excitation winding provided on the rotating shaft of the motor rotor.

In the present invention, the resonant frequency of the LC resonant circuit formed by the auxiliary excitation transmitting coil connected in series with capacitors is the same as the frequency of the high-frequency power supply, and the resonant frequency of the LC resonant circuit formed by the auxiliary excitation receiving coil connected in series with capacitors is the same as the frequency of the high-frequency power supply.

In the present invention, the high-frequency excitation power supply and the excitation transmitting coil are arranged on the outside of the motor end cover, the auxiliary excitation receiving coil, the rotating rectifier bridge, the soft magnetic optimization layer and the metal shielding layer are arranged on the inside of the end cover, and the excitation transmitting coil is directly opposite to the end cover. The cover is set, and the distance between the two is adjustable. The auxiliary excitation receiving coil is also set directly opposite the end cover, and the end cover is made of non-metallic material.

In the present invention, the high-frequency excitation power supply and the auxiliary excitation transmitting coil are outside the motor, and the auxiliary excitation receiving coil is inside the motor, and the transmission of electric energy is realized through magnetic resonance coupling to supply power to the excitation winding of the motor. The auxiliary excitation receiving coil and the rotating rectifier bridge are coaxially connected in series with the rotor excitation winding through the openings on the soft magnetic optimization layer and the metal shielding layer, and rotate synchronously with the rotor to supply power to the excitation winding. The soft magnetic optimization layer and the metal shielding layer are circular sheets, fixed inside the motor, close to the motor shell, and parallel to the end surface of the motor side. Both have round holes for the rotor shaft and DC wires to pass through. Soft magnetic optimization layer and metal shielding layer are used to optimize the magnetic field of the motor.

The invention rectifies and inverts power frequency power to obtain high-frequency alternating current, sends it to the auxiliary excitation transmitting coil outside the motor, utilizes magnetic resonance coupling power wireless transmission technology, and the auxiliary excitation receiving coil in the motor is energized, and is supplied to the rotor excitation after rectification , the receiving coil and the rectifier are connected in series with the rotor coaxially to realize the wireless excitation of the AC motor rotor, which has the advantages of convenient control and simple structure.

In the present invention, the motor side end cover adopts a molding compound with little electromagnetic influence and high mechanical strength; a metal shield is added between the receiving coil and the stator and rotor to ensure that the excitation system and the original internal system of the motor do not interfere with each other. In order to compensate for the adverse effects of the metal sheet on the excitation system, optimize the electromagnetic field of the excitation system, and improve the coupling efficiency of the transceiver coil, a soft magnetic layer is added between the auxiliary excitation receiving coil and the metal layer.

Beneficial effect: compared with the prior art, the present invention has the following advantages:

The invention uses the magnetic coupling resonance wireless power transmission technology to supply power to the excitation winding of the motor, the auxiliary excitation receiving coil and the excitation winding rotate coaxially, through the magnetic coupling resonance between the auxiliary excitation transmitting coil and the auxiliary excitation receiving coil, the dynamic and static mechanisms are realized. power transfer between them. Only the auxiliary excitation receiving coil, rotating rectifier bridge, and optimized shielding medium need to be installed inside the motor, avoiding complex mechanisms such as brushes, sensors or transformer cores, which can effectively reduce the weight of the motor and improve its working reliability.

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Description of drawings

FIG. 1 is a schematic structural diagram of a brushless excitation mechanism based on wireless transmission of electric energy according to the present invention.       

In the figure: high frequency excitation power supply 1, auxiliary excitation transmitting coil 2, end cover 3, auxiliary excitation receiving coil 4, rotating rectifier bridge 5, soft magnetic optimization layer 6, metal shielding layer 7, excitation winding 8, rotating shaft 9, rotor 10.

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Detailed ways

Referring to Fig. 1, a brushless excitation mechanism based on wireless transmission of electric energy in the present invention includes a high-frequency excitation power supply 1, an auxiliary excitation transmitting coil 2, an end cover 3, an auxiliary excitation receiving coil 4, a rotating rectifier bridge 5, and a soft magnetic optimization layer 6. Metal shielding layer 7.

The high-frequency excitation power supply 1 uses a phase-shifted full-bridge zero-voltage switching PWM circuit to output high-frequency alternating current of 100kHz~10MHz. Change the output power of the power source by adjusting the phase difference of the drive pulse, that is, change the excitation current value of the motor.

Auxiliary excitation transmitting coil 2 uses copper wire with a wire diameter of 0.2mm~2mm (the wire diameter meets the long-term safe passage of the motor excitation current), tightly wound into a hollow helical column, and the coil diameter is 10cm~20cm (according to the installation requirements, it is about the size of the motor Half), the coil is about 10 turns (coil height does not exceed 2cm, change the number of turns to adjust the inductance), measure the inductance after the coil is wound. The two ends of the coil tap are connected to the high-frequency power supply 1, and a suitable capacitor (its value is calculated by matching parameters) is connected in series to form an LC resonant circuit, and the resonant frequency is equal to the frequency of the high-frequency power supply. The auxiliary excitation transmitting coil 2 is fixed on the outside of the motor with a bracket, facing the end cover 3 of the motor, and its distance is adjustable to achieve the maximum coupling efficiency.

The end cap 3 is a non-metallic material such as BMC, SMC, etc. that has little influence on electromagnetic waves.

The auxiliary excitation receiving coil 4 and the auxiliary excitation transmitting coil 2 are made of the same material and wound into the same columnar shape. The power frequency 1 is the same, so that the auxiliary excitation transmitting coil 2 and the auxiliary excitation receiving coil 4 resonate, and the transmission efficiency of the system is the highest. The auxiliary excitation receiving coil 4 and the rotating rectifier bridge 5 are fixed on the rotating shaft 9 through a bracket, and can rotate synchronously with the rotor 10, and they maintain a certain gap with the static soft magnetic optimization layer 6 and the end cover 3 to prevent contact friction.

The DC terminal of the rotating rectifier bridge 5 is connected to the excitation winding 8, and the excitation winding 8 is installed on the rotating shaft 9 of the rotor 10 to realize wireless power supply from the excitation power supply outside the motor to the excitation winding.

The soft magnetic optimization layer 6 and the metal shielding layer 7 are closely attached to the motor shell and fixed inside the motor to isolate the excitation system from the original internal environment of the motor and optimize the coupling efficiency of the excitation system. There are openings on the soft magnetic optimization layer 6 and the metal shielding layer 7 for the DC outgoing lines of the rotor shaft 9 and the rotary rectifier bridge 5 to pass through. The soft magnetic optimization layer 6 uses MnZn ferrite with a thickness of 5mm, and the metal shielding layer 7 uses a thin iron sheet with a thickness of 2mm.

The above-mentioned mechanism installed inside the motor includes the auxiliary excitation receiving coil 4, the rotating rectifier bridge 5, the soft magnetic optimization layer 6, and the metal shielding layer 7, which occupy about 7 cm in the axial length of the motor. While removing brushes, brush holders and other components of ordinary brushed motors, depending on the size of the internal space of the motor, the axial length of the motor casing can be appropriately increased to facilitate the placement of the brushless excitation system.

Claims (3)

1. A brushless excitation mechanism based on wireless transmission of electric energy, characterized in that the mechanism includes a high-frequency excitation power supply (1) and an auxiliary excitation transmitting coil (2) arranged outside the motor, and an auxiliary excitation coil (2) arranged inside the motor The receiving coil (4), the rotating rectifier bridge (5), the soft magnetic optimization layer (6) and the metal shielding layer (7), the soft magnetic optimization layer (6) and the metal shielding layer (7) connect the excitation system with other parts inside the motor After being isolated, the rotating shaft (9) of the motor rotor (10) passes through the opening on the soft magnetic optimization layer (6) and the metal shielding layer (7) and is installed with the auxiliary excitation receiving coil (4) and the rotating rectifier bridge (5) connection, the auxiliary excitation transmitting coil (2) is connected to the high-frequency excitation power supply (1) after the capacitor is connected in series to form an LC resonant circuit, and the auxiliary excitation receiving coil (4) is connected to the rotating rectifier bridge after the capacitor is connected in series An LC resonant circuit is also formed on the AC terminal of (5), and the outgoing line of the DC terminal of the rotating rectifier bridge (5) passes through the soft magnetic optimization layer (6) and the metal shielding layer (7) successively and connects with the motor rotor (10 ) is connected to the field winding (8) set on the rotating shaft (9). 2. The brushless excitation mechanism based on wireless power transmission according to claim 1, characterized in that the auxiliary excitation transmitting coil (2) is connected in series with a capacitor to form an LC resonant circuit whose resonant frequency is the same as the frequency of the high-frequency power supply, and the auxiliary The excitation receiving coil (4) is connected in series with capacitors to form an LC resonant circuit whose resonant frequency is the same as the frequency of the high-frequency power supply. 3. The brushless excitation mechanism based on wireless power transmission according to claim 1 or 2, characterized in that, the high-frequency excitation power supply (1) and the excitation transmitting coil (2) are arranged on the motor end cover (3) On the outside of the end cover (3), the auxiliary excitation receiving coil (4), rotating rectifier bridge (5), soft magnetic optimization layer (6) and metal shielding layer (7) are arranged on the inner side of the end cover (3), and the excitation transmitting coil (2) is facing The end cover (3) is arranged, and the distance between the two is adjustable, and the auxiliary excitation receiving coil (4) is also arranged facing the end cover (3), and the end cover (3) is made of non-metallic material.