Full-bridge LCL type wireless electric energy transmission system and automobile alternating-current generator

Abstract

The utility model relates to the technical field of brushless alternating-current generators, in particular to a full-bridge LCL type wireless power transmission system and an automobile alternating-current generator. The wireless power transmission mode of the magnetic coupling resonance circuit is used and completed on the automobile alternating current generator, the magnetic coupling resonance circuit, the high-frequency inverter and the transmitting coil are designed to replace a brush carrier and a carbon brush, the transmitting coil and the high-frequency rectifier are designed to replace a collecting ring, and the load is a magnet exciting coil. An original circuit needing connection of a carbon brush and a collector ring is achieved through the wireless electric energy transmission technology, excitation current is not affected by the power transmission defect of the carbon brush and the collector ring any more, and compared with magnetic resistance loss of a claw pole air gap of a traditional brushless automobile alternating current generator, the magnetic resistance loss is reduced within the distance of 2 cm through the wireless electric energy transmission technology. The energy transmission is more than 90%, and the problem of low energy conversion efficiency of the brushless alternating-current generator is solved.

Description

Technical Field

[0001] The utility model relates to the technical field of brushless AC generators, in particular to a full-bridge LCL type wireless power transmission system and an automobile AC generator. Background Art

[0002] The car's alternator is the main power source for the car. When the car is running normally (above idling), it supplies power to all electrical devices (except the starter) and charges the battery at the same time.

[0003] like Figure 1 As shown, automotive AC generators power the rotor excitation coils via a structure of carbon brushes and slip rings. This structure introduces friction during transmission, leading to wear of the slip rings and carbon brushes, which accelerates excitation circuit failure. Sparks are also easily generated during power transmission, impacting the lifespan and safety of the AC generator. These shortcomings of traditional power supply methods can be fatal, leading to fires and equipment damage in severe cases, resulting in significant safety risks and economic losses.

[0004] In order to solve the problem of wear of collector ring and carbon brush, a brushless motor is used, the structure of which is as follows: Figure 2 As shown, this structure secures the rotor assembly's excitation coil and yoke to the rear end cover, preventing them from rotating with the rotor assembly; only the rotor claws rotate. While this overcomes the drawbacks of using a collector ring and carbon brush connection for the excitation circuit, the presence of an air gap between the yoke and claw poles creates significant magnetic resistance during magnetic force transmission, exacerbating hysteresis losses in the rotating magnetic field generated by the rotor assembly and reducing the generator's energy conversion efficiency. Furthermore, due to the rear end structure of brushless AC generators, centrifugal fans cannot be installed, resulting in poorer heat dissipation compared to brushed automotive AC generators. This reduced efficiency and poor heat dissipation results in brushless automotive AC generators requiring a larger volume to achieve the same power as brushed AC generators.

[0005] Therefore, it is hoped to design a solution that can solve the problem of wear on the generator caused by the way the brushed automobile AC generator transmits electric energy through the collector ring and carbon brush, and can also solve the problem of air gaps between the claw poles of the brushless automobile AC generator, which affects the poor energy conversion efficiency of the generator. Utility Model Content

[0006] In view of the above-mentioned deficiencies in the prior art, the purpose of the present invention is to provide a full-bridge LCL type wireless power transmission system and an automobile AC generator.

[0007] To achieve the above objectives, the present invention provides the following technical solutions:

[0008] A full-bridge LCL-type wireless power transmission system includes a transmitting circuit and a receiving circuit. The transmitting circuit includes a power module, a rectifier module, a high-frequency inverter module, a resonance compensation module, a transmitting coil and a voltage regulator. The resonance compensation module is an LCL-type resonant circuit. The power module is connected to the rectifier module, the rectifier module is connected to the high-frequency inverter module, the high-frequency inverter module is connected to the transmitting coil, and the voltage regulator is respectively connected to the high-frequency inverter module and the transmitting coil; the receiving circuit includes a receiving coil, a high-frequency rectifier module and a load. The receiving coil is connected to the high-frequency rectifier module, and the high-frequency rectifier module is connected to the load.

[0009] As a preferred embodiment of the present invention, the power supply module includes an AC power supply, the AC power supply is the AC power generated by the stator assembly, the rectifier module is a rectifier bridge, and the AC power supply is connected to the rectifier bridge.

[0010] As a preferred embodiment of the present invention, the high-frequency inverter module includes a full-bridge inverter circuit composed of a first field-effect transistor, a second field-effect transistor, a third field-effect transistor, and a fourth field-effect transistor.

[0011] As a preferred embodiment of the present invention, the positive pole of the high-frequency inverter is connected to the F terminal of the voltage regulator, and the negative pole of the high-frequency inverter is connected to the E terminal of the voltage regulator.

[0012] As a preferred embodiment of the present invention, the LCL resonant circuit includes a first inductor, a second inductor and a resonant capacitor, the first inductor is connected to the second inductor and the resonant capacitor at the same time, and the second inductor and the resonant capacitor are connected in parallel.

[0013] An automotive AC generator, based on a full-bridge LCL-type wireless power transmission system, includes a pulley, a front cover, a front bearing, a stator assembly, a rotor assembly, a rectifier bridge, a rear bearing, and a rear cover. The rotor assembly includes a rotor shaft, which passes through the rear bearing. The end of the rotor shaft extending outside the rear cover is provided with a receiving coil and a resonant capacitor. A transmitting coil is provided around the receiving coil. An LCL resonant circuit, a high-frequency inverter, a voltage regulator, and a rectifier bridge are provided outside the transmitting coil. A filter capacitor and a high-frequency rectifier are provided on the inner side of the rotor shaft near the rear bearing.

[0014] As a preferred embodiment of the present invention, the axes of the rotor shaft, the receiving coil and the transmitting coil coincide with each other.

[0015] As a preferred embodiment of the present invention, the distance between the receiving coil and the transmitting coil is less than 2 cm.

[0016] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0017] The wireless power transmission method using a magnetically coupled resonant circuit is completed on the automobile AC generator. The magnetically coupled resonant circuit is designed with a high-frequency inverter and a transmitting coil to replace the brush holder and carbon brushes, and the transmitting coil and a high-frequency rectifier to replace the slip ring. The load is the excitation coil. The circuit that originally required the connection of carbon brushes and slip rings is realized by wireless power transmission technology, so that the excitation current is no longer affected by the transmission defects of carbon brushes and slip rings. At the same time, compared with the magnetic resistance loss of the claw pole air gap of the traditional brushless automobile AC generator, the use of wireless power transmission technology can achieve energy transmission of more than 90% within a distance of 2CM, which also overcomes the problem of low energy conversion efficiency of brushless AC generators. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Other features, objects and advantages of the present invention will become more apparent from the detailed description of the non-limiting embodiments with reference to the following drawings:

[0019] Figure 1 It is a cross-sectional schematic diagram of a brushed automotive alternator in the prior art;

[0020] Figure 2 A schematic cross-sectional view of a brushless automotive alternator in the prior art;

[0021] Figure 3 This is the electrical schematic diagram of a traditional automotive AC generator;

[0022] Figure 4 This is a block diagram of the electromagnetic resonance coupled wireless power system;

[0023] Figure 5 This is the overall structure diagram of the coupled wireless power transmission system;

[0024] Figure 6 This is a diagram of a wireless power transmission system;

[0025] Figure 7 This is a diagram of a full-bridge LCL type wireless power transmission system;

[0026] Figure 8 is a schematic diagram of a full-bridge inverter;

[0027] Figure 9 is a schematic diagram of an LCL resonant circuit;

[0028] Figure 10 Schematic diagram of wireless power transmission receiving end;

[0029] Figure 11 This is the electrical schematic diagram of the LCL radio excitation automobile alternator;

[0030] Figure 12 This is a cross-sectional view of the LCL radio-excited automotive alternator structure;

[0031] Figure 13 This is a schematic diagram of the top view of the LCL radio excitation automobile AC generator;

[0032] Figure 14 This is the structural diagram of the rotor assembly of the LCL radio-excited automotive AC generator.

[0033] In the picture:

[0034] AC, AC power supply, DC, DC power supply, Lr, compensation inductor, Cr, resonant capacitor, Cs, filter capacitor, Lp, transmitting coil, Ls, receiving coil, Rr, first inductor, Rp, second inductor, Rs, third inductor, RL, load, R, excitation coil, S1, first field effect transistor, S2, second field effect transistor, S3, first and third field effect transistors, S4, fourth field effect transistor;

[0035] Pulley, front end cover, front bearing, stator assembly, rotor assembly, rectifier bridge, rear bearing and rear end cover

[0036] pulley;

[0037] Front end cover, 201, front bearing;

[0038] stator assembly;

[0039] rotor assembly, 401, rotor shaft;

[0040] Rectifier bridge;

[0041] Rear end cover; 601, rear bearing;

[0042] LCL resonant circuit;

[0043] High-frequency inverter

[0044] voltage regulator;

[0045] High frequency rectifier. DETAILED DESCRIPTION

[0046] In order to make the technical means, creative features, objectives and effects achieved by the present invention easier to understand, the present invention is further described below in conjunction with specific implementation methods.

[0047] The most important electrical components of a generator are the stator assembly and the rotor assembly. The stator assembly consists of armature windings with an angle difference of 120 degrees. The rotor assembly has many parts, generally consisting of a rotor shaft, front and rear claw poles, a field coil and a slip ring. Hybrid excitation rotors also have magnets. The external current passes through the regulator and provides pre-excitation current to the rotor field coil through the upper and lower brushes, generating a magnetic field. The claw poles are magnetized. According to the right-hand rule, the polarity of the front and rear claw poles is divided into S pole and N pole, such as Figure 1As shown in the figure, the rotor generates an axial magnetic field in the yoke after the excitation current passes through it. This magnetic field is converted into multiple radial magnetic fields by the bird's beak claw poles. As the engine drives the pulley, the stator armature winding cuts through this magnetic field, generating multiple sinusoidal induced electromotive forces in the stator wires. This is then rectified by the rectifier bridge and converted into direct current.

[0048] Automotive alternators use a structure of carbon brushes and slip rings to power the rotor excitation coil. This structure introduces friction during transmission, leading to wear of the slip rings and carbon brushes, which accelerates the failure of the excitation circuit. Sparks are also easily generated during power transmission, affecting the lifespan and safety of the alternator. These shortcomings of traditional power supply methods can be fatal, leading to fires and equipment damage, resulting in significant safety risks and economic losses.

[0049] In order to solve the problem of wear of collector rings and carbon brushes, brushless motors are also used. The structure is as follows Figure 2 As shown. This structure fixes the rotor assembly's excitation coil and yoke to the rear end cover, preventing the yoke and excitation coil from rotating with the rotor assembly. Only the rotor claws rotate. While this solves the drawback of using a collector ring-carbon brush connection for the excitation circuit, the presence of an air gap between the yoke and the claw poles creates significant magnetic resistance during magnetic force transmission, exacerbating the hysteresis loss of the rotating magnetic field generated by the rotor assembly and reducing the generator's energy conversion rate. Furthermore, due to the rear end structure of the brushless AC generator, a centrifugal fan cannot be installed, resulting in poorer heat dissipation conditions than brushed automotive AC generators. This reduced efficiency and poor heat dissipation require brushless automotive AC generators to be larger in size to achieve the same power as brushed AC generators. Figure 3 This is the electrical schematic diagram of an automotive alternator. While brushed and brushless automotive alternators differ in structure, their electrical principles are the same. Both utilize a regulator's F terminal to output DC current, energizing the excitation coil and magnetizing the yoke. The magnetic field, guided by the claw poles, converts the axial magnetic field into a radial magnetic field.

[0050] In this application, the theoretical basis of magnetically coupled resonant wireless power transmission is the coupling mode theory: two oscillating circuits with the same resonant frequency are coupled through near-field evanescent waves within the wavelength range, allowing energy to be efficiently transferred from one object to another during the loss time. The interaction with surrounding objects of different frequencies is very weak, and the medium for power transmission is a medium- and high-frequency magnetic field. Simply put, two "resonators" with the same resonant frequency generate resonance through electromagnetic coupling to achieve energy transmission. Under normal circumstances, two charged objects at a certain distance from each other are weakly coupled, but when the resonant frequencies of the two charged objects themselves are consistent, a strong magnetic field coupling will be generated between the two charged objects. At this time, the transmitter can provide power to the system, and the receiver receives and consumes power, thus realizing wireless transmission of power. The system block diagram is shown below. Figure 4 As shown in the figure, the traditional electromagnetic coupling resonant wireless power transmission system mainly includes two parts: the transmitter and the receiver. The transmitter part includes a high-frequency driving source, a primary matching tuning circuit and a transmitting coil; the receiver part includes a receiving coil, a secondary matching tuning circuit and a load. Figure 5 As shown, an existing generator is designed and optimized, based on a magnetically coupled resonant circuit and combined with a wireless power transmission system to form a full-bridge LCL-type wireless power transmission system. The full-bridge LCL-type wireless power transmission system includes a transmitter circuit and a receiver circuit. The transmitter circuit comprises a power module, a rectifier module, a high-frequency inverter module, a resonant compensation module, a transmitter coil Lp, and a voltage regulator 9. The resonant compensation module is an LCL-type resonant circuit 7. The power module is connected to the rectifier module, which is connected to the high-frequency inverter module, which is connected to the transmitter coil Lp. The voltage regulator 9 is connected to the high-frequency inverter module and the transmitter coil Lp, respectively. The receiver circuit comprises a receiver coil Ls, a high-frequency rectifier module, and a load RL. The receiver coil Ls is connected to the high-frequency rectifier module, which is connected to the load RL. AC power is supplied by the stator assembly 3 of the automotive alternator. The voltage regulator 9 of the automotive alternator performs the functions of the controller and sensor, controlling the voltage on and off to control the operating state of the subsequent circuits. Based on the structure of an automotive alternator, a magnetically coupled resonant circuit is implemented on the alternator. A high-frequency inverter 10 and a transmitting coil Lp are used in place of the brush holder and carbon brushes. A receiving coil Ls and a high-frequency rectifier 10 are used in place of the slip rings, with the excitation coil serving as the load.

[0051] In this way, wireless power transmission technology enables circuits that previously required carbon brushes and slip rings to be connected, freeing the excitation current from the transmission imperfections of these brushes and slip rings. Using wireless power transmission technology, energy transfer exceeds 90% within a distance of 2 cm. Compared to the reluctance losses in the claw-pole air gaps of traditional brushless automotive alternators, this approach significantly reduces the advantages of brushed automotive alternators while overcoming the low energy conversion efficiency and poor heat dissipation inherent in brushless alternators.

[0052] like Figure 6 The figure shows the system diagram of the working mode of the entire excitation circuit. The method used is an AC to DC full-bridge LCL type wireless power transmission system. AC is the alternating current generated by the stator assembly 3, which is connected to the rectifier bridge 5 for full-bridge rectification and converted into direct current DC. The process of converting the alternating current generated by the stator assembly 3 and the DC part of the rectifier bridge 5 into direct current is simplified to DC, and then the high-frequency rectifier 10 at the receiving end is simplified. The simplified circuit is Figure 7 Where Lr is the compensation inductor, Cr and Cs are the compensation capacitors, Lp and Ls are the primary and secondary coils respectively, Rr, Rp, and Rs are the equivalent series resistances of the inductors Lr, Lp, and Ls respectively, and RL is the equivalent load. S1, S2, S3, and S4 form a full-bridge inverter, which inverts the DC power supply voltage into an AC high-frequency voltage, thereby exciting the LCL resonant network composed of Lr-Cr-Lp, generating a high-frequency alternating current in the transmitting coil Lp and exciting a high-frequency alternating magnetic field of the same frequency in the surrounding area. At this time, the filter capacitor Cs is used to make the resonant frequency of the receiving coil Ls the same as that of the primary side. Through magnetic field coupling, energy is continuously transmitted from the primary side to the receiving coil Ls.

[0053] like Figure 7 As shown, the entire system has two parts installed on the car AC generator. The left part is the output transmission end of electric energy, and the right part is the electric energy receiving and consuming end. The output transmission end is mainly composed of two parts. The first part is the high-frequency inverter 8, whose main function is to invert the DC power output from the F end of the car AC generator voltage regulator 9 into high-frequency AC power. The high-frequency inverter circuit is a key link in the wireless power transmission system. This circuit needs to have the characteristics of good safety, high efficiency, low loss, high stability, strong anti-interference ability, and simple control. As shown in the figure, the output transmission end is mainly composed of two parts. The first part is the high-frequency inverter 8, which is mainly used to invert the DC power output from the F end of the car AC generator voltage regulator 9 into high-frequency AC power. The high-frequency inverter circuit is a key link in the wireless power transmission system. This circuit needs to have the characteristics of good safety, high efficiency, low loss, high stability, strong anti-interference ability, and simple control. Figure 8 As shown in the figure, it is a full-bridge inverter. The full-bridge inverter has a larger output power and does not have the problem of DC bias of the transformer, which is conducive to high-power transmission. Therefore, the full-bridge inverter circuit is selected as the high-frequency inverter circuit for wireless power transmission. The second part is the resonator, which is an LCL type resonant circuit. Figure 6 After simplifying the high-frequency inverter 8, we get Figure 9 , the figure consists of two inductors and one capacitor, so it is an LCL type.

[0054] Characteristics of LCL resonance:

[0055] The inverter only needs to provide a very low current, yet a larger current flows through the primary coil. This meets the requirement for establishing a strong magnetic field for wireless power transmission. The current in the inverter and energy storage circuit is relatively low, facilitating low-cost system design. Any parasitic inductance of the transmission line can be considered part of the matching compensation inductor Lr, allowing the coupling coil to be located farther away from the inverter. This provides flexible system layout. Compared to a single-stage LC system, the inverter is subject to less voltage and current stress. Multiple inverters and matching inductors can be used in parallel, facilitating modular system design and achieving high power.

[0056] Figure 10 The receiving end of wireless power transmission. It mainly consists of a single-pole LC resonant circuit, a rectifier bridge, a filter capacitor, and a resistor. The resistor R is the excitation coil.

[0057] like Figures 11 to 14 As shown, an automotive AC generator, based on the full-bridge LCL type wireless power transmission system as described above, includes a pulley 1, a front cover 2, a front bearing 201, a stator assembly 3, a rotor assembly 4, a rectifier bridge 5, a rear bearing 601 and a rear cover 6, characterized in that the rotor assembly 4 includes a rotor shaft 401, the rotor shaft 401 crosses the rear bearing 601, and the end of the rotor shaft 401 extending outside the rear cover 6 is provided with a receiving coil Ls and a resonant capacitor, a transmitting coil Lp is provided around the receiving coil Ls, and an LCL resonant circuit 7, a high-frequency inverter 8, a regulator 9, and a rectifier bridge 5 are provided outside the transmitting coil Lp, and a filter capacitor Cs and a high-frequency rectifier 10 are provided on the inner side of the rotor shaft 401 near the rear bearing 601.

[0058] The axes of the rotor shaft 401, the receiving coil Ls and the transmitting coil Lp coincide with each other.

[0059] The distance between the receiving coil Ls and the transmitting coil Lp is less than 2 cm.

[0060] Connect the positive terminal of high-frequency inverter 10 to terminal F of the vehicle's AC generator voltage regulator 9, and the negative terminal of high-frequency inverter 10 to terminal E of the vehicle's AC generator voltage regulator 9. Connect high-frequency inverter 9 to LCL resonator 7. Secure transmitting coil Lp to the center of the rear end cover 6 of the vehicle's AC generator.

[0061] The receiving coil Ls is fixed to the rear end of the rotor shaft 401 (the original location of the collector ring). The receiving coil Ls is connected in series with the filter capacitor Cs to form a single-pole LC resonant circuit to receive electrical energy.

[0062] The unipolar LC at the receiving end is connected to the high-frequency rectifier 10 for full-bridge rectification. After rectification, the positive and negative poles are connected to the excitation coil R. The positive and negative poles of the excitation coil R are connected to the filter capacitor Cs to filter the ripple DC power after rectification, making the current more stable.

[0063] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the utility model and are not limiting. Although the utility model is described in detail with reference to the preferred embodiments, ordinary technicians in this field should understand that the technical solution of the utility model can be modified or replaced by equivalents without departing from the purpose and scope of the technical solution of the utility model, which should be included in the scope of the claims of the utility model.

Claims

1. A full-bridge LCL type wireless power transmission system, comprising a transmitter circuit and a receiver circuit, characterized in that: The transmitting end circuit includes a power supply module, a rectifier module, a high-frequency inverter module, a resonance compensation module, a transmitting coil and a voltage regulator. The resonance compensation module is an LCL-type resonant circuit. The power supply module is connected to the rectifier module, the rectifier module is connected to the high-frequency inverter module, the high-frequency inverter module is connected to the transmitting coil, and the voltage regulator is connected to the high-frequency inverter module and the transmitting coil respectively. The receiving end circuit includes a receiving coil, a high-frequency rectifier module and a load. The receiving coil is connected to the high-frequency rectifier module, and the high-frequency rectifier module is connected to the load.

2. The full-bridge LCL type wireless power transmission system according to claim 1, characterized in that: The power supply module includes an AC power supply, which is the AC power generated by the stator assembly. The rectifier module is a rectifier bridge, and the AC power supply is connected to the rectifier bridge.

3. The full-bridge LCL type wireless power transmission system according to claim 2, characterized in that: The high-frequency inverter module includes a full-bridge inverter circuit composed of a first field-effect transistor, a second field-effect transistor, a third field-effect transistor, and a fourth field-effect transistor.

4. The full-bridge LCL type wireless power transmission system according to claim 3, characterized in that: The positive pole of the high-frequency inverter is connected to the F terminal of the voltage regulator, and the negative pole of the high-frequency inverter is connected to the E terminal of the voltage regulator.

5. The full-bridge LCL type wireless power transmission system according to claim 4, characterized in that: The LCL resonant circuit includes a first inductor, a second inductor and a resonant capacitor, the first inductor is connected to the second inductor and the resonant capacitor at the same time, and the second inductor and the resonant capacitor are connected in parallel.

6. An automotive AC generator based on the full-bridge LCL type wireless power transmission system according to claim 4, comprising a pulley, a front end cover, a front bearing, a stator assembly, a rotor assembly, a rectifier bridge, a rear bearing and a rear end cover, characterized in that: The rotor assembly includes a rotor shaft, which passes through the rear bearing. The end of the rotor shaft extending outside the rear end cover is provided with a receiving coil and a resonant capacitor. A transmitting coil is provided around the receiving coil. An LCL resonant circuit, a high-frequency inverter, a voltage regulator, and a rectifier bridge are provided outside the transmitting coil. A filter capacitor and a high-frequency rectifier are provided on the inner side of the rotor shaft near the rear bearing.

7. The automotive AC generator according to claim 6, characterized in that: The axes of the rotor shaft, the receiving coil and the transmitting coil coincide with each other.

8. The automotive AC generator according to claim 7, characterized in that: The distance between the receiving coil and the transmitting coil is less than 2 cm.

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