Printed circuit board, three-phase permanent magnet synchronous direct-current brushless motor and air conditioner

Abstract

The application provides a printed circuit board, a three-phase permanent magnet synchronous direct-current brushless motor and an air conditioner. The printed circuit board comprises a carrier plate, a plurality of inductors are integrally arranged on the carrier plate, the plurality of inductors are arranged on the printed circuit board according to an involute track, the winding of a single inductor is wound around a preset axis to form a coil, the two ends of the coil along the preset axis are a large end and a small end respectively, the area of the cross section of the coil perpendicular to the preset axis gradually decreases from the large end to the small end, and the small end of the inductor faces the center of the involute, so that the volume of the common-mode current suppression device can be reduced, and the common-mode current suppression effect can be improved.

Description

Technical Field

[0001] This invention belongs to the field of motor technology, specifically relating to a printed circuit board, a three-phase permanent magnet synchronous DC brushless motor, and an air conditioner. Background Technology

[0002] Brushless DC motors are widely used in home appliances, automotive, and industrial equipment due to their high efficiency, high reliability, and precise controllability. However, their PWM high-frequency modulation mechanism continuously excites parasitic parameters in the windings, generating wideband common-mode currents that cause conducted electromagnetic interference, leading to problems such as power grid pollution, controller malfunctions, and failure to pass EMC tests.

[0003] Traditional methods for suppressing common-mode current use discrete magnetic ring inductors. However, discrete magnetic ring inductors are bulky and require independent brackets and wiring harnesses, which cannot adapt to the trend of motor miniaturization and high integration. Assembly is cumbersome and inconsistent.

[0004] How to reduce the size of devices that suppress common-mode current is a technical problem that urgently needs to be solved. Summary of the Invention

[0005] Therefore, the present invention provides a printed circuit board, a three-phase permanent magnet synchronous DC brushless motor, and an air conditioner, which can reduce the size of the common-mode current suppression device.

[0006] This invention provides a printed circuit board for use in a three-phase permanent magnet synchronous brushless DC motor. The printed circuit board includes a carrier board on which multiple inductors are integrated. The multiple inductors are arranged on the printed circuit board according to an involute trajectory. The windings of a single inductor are wound around a preset axis to form a coil. The two ends of the coil along the preset axis are a large end and a small end, respectively. From the large end to the small end, the area of ​​the cross section of the coil perpendicular to the preset axis gradually decreases. The small end of the inductor faces the center of the involute.

[0007] In some embodiments, a V-shaped gap is formed between two adjacent inductors on a projection toward the printed circuit board, the opening of the V-shaped gap facing away from the center of the involute.

[0008] In some embodiments, the preset axis passes through the center of the involute.

[0009] In some embodiments, in the radial direction of the involute, the distance between two adjacent inductors is L, which gradually increases from the center of the involute outwards.

[0010] In some embodiments, the carrier board is further provided with a controllable switch network, which is electrically connected to all the inductors. The controllable switch network enables at least two inductors to be connected in series or in parallel, and also enables multiple inductors to be connected in series or in parallel.

[0011] In some embodiments, the projected area of ​​the coil along the predetermined axis gradually increases from the center of the involute outwards and along the trajectory of the involute.

[0012] In some embodiments, the carrier board is further provided with a current detection module, a spectrum analysis module, and a topology reconstruction control module.

[0013] The present invention also provides a three-phase permanent magnet synchronous brushless DC motor, including a control circuit board, a stator and the printed circuit board, wherein the printed circuit board is disposed at one end of the stator, or the printed circuit board constitutes part of the control circuit board.

[0014] The present invention also provides an air conditioner, including the above-mentioned three-phase permanent magnet synchronous DC brushless motor.

[0015] This application eliminates the layout defects of sparse inner coils and crowded outer coils by arranging inductors on the carrier board of a printed circuit board according to the trajectory of an involute. The conical coils and the arrangement with the small end facing the center completely eliminate the layout defects of sparse inner coils and crowded outer coils, maximizing space utilization. At the same time, the high-performance magnetic ring inductor unit is standardized and integrated on the PCB carrier board, taking into account the characteristics of high current carrying capacity, high inductance and low loss. Its performance far exceeds that of ordinary planar printed inductors. It avoids the problem of large size of external filter structure from the structural source and adapts to the miniaturization design requirements of motors. Attached Figure Description

[0016] To more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the accompanying drawings used in the description of the embodiments or the prior art will be briefly introduced below. The drawings described below are merely exemplary, and those skilled in the art can derive other embodiments based on the provided drawings without creative effort.

[0017] Figure 1 This is a schematic diagram of inductors connected in series according to an embodiment of the present invention;

[0018] Figure 2 This is a first schematic diagram of inductors connected in series and then in parallel according to an embodiment of the present invention;

[0019] Figure 3 This is a schematic diagram of parallel inductors according to an embodiment of the present invention;

[0020] Figure 4 This is a second schematic diagram of inductors connected in series and then in parallel according to an embodiment of the present invention;

[0021] Figure 5 This is a partial schematic diagram of the switching network according to an embodiment of the present invention;

[0022] Figure 6This is a flowchart illustrating the process of suppressing common-mode current when the three-phase permanent magnet synchronous brushless DC motor is working according to an embodiment of the present invention.

[0023] Figure 7 This is a schematic diagram of a printed circuit board according to an embodiment of the present invention. Detailed Implementation

[0024] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The following description of at least one exemplary embodiment is merely illustrative and is in no way intended to limit the present invention or its application or use. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0025] In the description of this invention, it should be understood that the orientation or positional relationship indicated by directional terms such as "front, back, up, down, left, right", "horizontal, vertical, horizontal" and "top, bottom" is generally based on the orientation or positional relationship shown in the accompanying drawings, and is only for the convenience of describing this invention and simplifying the description. Unless otherwise stated, these directional terms do not indicate or imply that the device or element referred to must have a specific orientation or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation on the scope of protection of this invention; the directional terms "inner" and "outer" refer to the inner and outer contours relative to the outline of each component itself.

[0026] For ease of description, spatial relative terms such as "above," "on top of," "on the upper surface of," "above," etc., are used herein to describe the spatial positional relationship of a device or feature as shown in the figures to other devices or features. It should be understood that spatial relative terms are intended to encompass different orientations in use or operation beyond the orientation of the device as described in the figures. For example, if the device in the figures were inverted, a device described as "above" or "on top of" other devices or structures would subsequently be positioned as "below" or "under" other devices or structures. Thus, the exemplary term "above" can include both "above" and "below." The device may also be positioned in other different ways (rotated 90 degrees or in other orientations), and the spatial relative descriptions used herein will be interpreted accordingly.

[0027] Furthermore, it should be noted that the use of terms such as "first" and "second" to define components is merely for the purpose of distinguishing the corresponding components. Unless otherwise stated, the above terms have no special meaning and therefore should not be construed as limiting the scope of protection of this invention.

[0028] This invention belongs to the field of motor structure design and electromagnetic compatibility technology, specifically involving an integrated, topology-reconfigurable common-mode filter stator structure, which is particularly suitable for adaptive electromagnetic interference suppression scenarios of brushless DC motors under wide operating conditions and wide frequency bands.

[0029] Brushless DC motors are widely used in home appliances, automotive, and industrial equipment due to their high efficiency, high reliability, and precise controllability. However, their PWM high-frequency modulation mechanism continuously excites parasitic parameters in the windings, generating wideband common-mode currents that cause conducted electromagnetic interference, leading to problems such as power grid pollution, controller malfunctions, and failure to pass EMC tests.

[0030] Existing common-mode suppression technologies have the following core shortcomings:

[0031] Traditional discrete magnetic ring inductors have excellent filtering performance and strong current carrying capacity, but they are bulky, require independent brackets and wiring harnesses, cannot adapt to the trend of motor miniaturization and high integration, and are cumbersome to assemble and have poor consistency.

[0032] Fixed parameter filtering structure: The inductor parameters are fixed, which cannot match the interference frequency of dynamic offset under different motor speeds, loads and duty cycles. The filtering effect is uneven under all working conditions, with insufficient low frequency suppression and high frequency redundancy failure coexisting.

[0033] External filter solution: External filter components have lead antenna effect, are prone to coupling secondary interference, and the filtering attenuation is greatly reduced. At the same time, it increases the size, cost and assembly process of the whole machine.

[0034] In summary, existing technologies cannot simultaneously achieve high integration, high inductance, large current carrying capacity, and wide-band adaptive filtering within the limited internal space of a motor. The industry urgently needs an integrated stator filtering solution with structural innovation and topology reconfigurability.

[0035] This application provides a printed circuit board, such as Figure 7 As shown, this is applied to a three-phase permanent magnet synchronous brushless DC motor. The printed circuit board includes a carrier board 1, on which multiple inductors 2 are integrated. The multiple inductors 2 are arranged on the printed circuit board according to an involute trajectory. The winding of a single inductor 2 is wound around a preset axis to form a coil. The two ends of the coil along the preset axis are a large end and a small end, respectively. From the large end to the small end, the area of ​​the cross section of the coil perpendicular to the preset axis gradually decreases. The small end of the inductor 2 faces the center of the involute.

[0036] This structure directly solves the industry pain point of traditional magnetic ring inductors being difficult to integrate on PCBs. It is the first to adopt an involute linear array integrated design to adapt to the irregular ring space of motors. The conical coils, combined with the arrangement of the small end facing the center, completely eliminate the layout defects of sparse inner rings and crowded outer rings, maximizing space utilization. At the same time, the high-performance magnetic ring inductor unit is standardized and integrated on the PCB carrier board 1, taking into account the characteristics of large current carrying capacity, high inductance, and low loss. Its performance far exceeds that of ordinary planar printed inductors. It avoids the problem of large external filter structure size from the structural source and adapts to the miniaturization design requirements of motors.

[0037] This application distributes multiple inductors 2 in the shape of an involute. After multiple sets of inductors 2 are arranged along the involute trajectory, the structural design allows the magnetic fields generated by each inductor 2 to be fully superimposed when the common-mode current flows through, thereby increasing the total impedance of the common-mode circuit and more efficiently blocking and consuming common-mode noise. Compared with conventional arrangement, it can achieve a stronger common-mode current attenuation effect and significantly improve the common-mode suppression capability.

[0038] This near-symmetrical arrangement allows the magnetic fields generated by the differential-mode current during normal operation to essentially cancel each other out. The differential-mode circuit impedance is extremely low, resulting in minimal attenuation of the useful signal, good signal transmission integrity, and almost no loss of the differential-mode signal.

[0039] The special trajectory of the involute allows for the compact arrangement of multiple inductors in a limited space, adapting to complex operating conditions such as high frequency and high current. At the same time, the arrangement parameters can be flexibly adjusted to match the common-mode noise suppression requirements of different frequency bands, optimize EMC performance across the entire frequency band, and achieve better space utilization and performance adaptability.

[0040] Preferred, such as Figure 7 As shown, on the projection toward the printed circuit board, a V-shaped gap is formed between two adjacent inductors 2, and the opening of the V-shaped gap faces away from the center of the involute.

[0041] This V-shaped spacing layout can significantly reduce electromagnetic crosstalk and parasitic capacitance between adjacent inductor 2 units, further optimize the array's operational stability, avoid unnecessary coupling interference between inductors 2, ensure the reliability of each unit's independent operation during full-band filtering, and provide a stable hardware foundation for subsequent topology dynamic reconstruction.

[0042] Preferred, such as Figure 7 As shown, the preset axis passes through the center of the involute.

[0043] By having the preset axis pass through the center of the involute, the magnetic field distribution of all inductors 2 can be better matched with the trajectory of the involute, further compressing the overall space occupied by the array. At the same time, the magnetic field distribution of the inductor 2 array is more uniform, reducing local magnetic field distortion, reducing unnecessary electromagnetic losses, and improving the overall filtering efficiency.

[0044] Preferred, such as Figure 1 As shown, in the radial direction of the involute, the distance between two adjacent inductors 2 is L, and L gradually increases from the center of the involute outwards.

[0045] This non-equal spacing involute layout further optimizes the utilization efficiency of the annular space, avoids the problem of increased parasitic coupling caused by the small spacing of the outer ring inductors 2, and allows the array to achieve a more regular arrangement of inductor 2 units within the limited space at the motor end. The assembly consistency is significantly improved, and there will be no problems of component interference or chaotic arrangement during mass production assembly.

[0046] Preferably, the carrier plate 1 is further provided with a controllable switch network, which is electrically connected to all the inductors 2. The controllable switch network can connect at least two inductors 2 in series or in parallel, and can also connect multiple inductors 2 in series or in parallel.

[0047] By integrating a controllable switching network on carrier board 1, dynamic topology reconfiguration of inductor 2 is achieved, abandoning the traditional fixed parameter filtering mode. The series and parallel topologies are switched in real time through the switching network, and the equivalent inductance 2 is adjustable across orders of magnitude. A single hardware can be compatible with all speed and full load conditions, dynamically adapt to 150kHz–30MHz wideband common-mode interference, and accurately match low-frequency, mid-frequency, and high-frequency common-mode interference. This completely solves the pain point of traditional filtering that "a single parameter cannot take into account both high and low frequencies". At the same time, it can shield distorted waveform current and reduce the non-zero harmonic components entering the armature output terminal, forming an effective current interception system.

[0048] like Figure 2-6 As shown, "series and parallel connection" in this application means that among the multiple inductors 2, some are connected in parallel with each other, some are connected in series with each other, some are connected in series with each other and then in parallel with other inductors 2, and some are connected in parallel with each other and then in series with other inductors 2.

[0049] The controllable switching network uses at least one switching device among MOSFET, IGBT, and relay.

[0050] MOSFET stands for Metal-Oxide-Semiconductor Field-Effect Transistor; IGBT stands for Insulated Gate Bipolar Transistor.

[0051] The combination of various switching devices can be adapted to motor scenarios with different power levels. MOSFETs are suitable for high-frequency, low-power scenarios to ensure switching response speed, IGBTs are suitable for high-power conditions to ensure current carrying capacity, and relays are suitable for high-current, low-loss scenarios. This allows the switching network to stably complete the electrical topology reconstruction of the involute inductor array, adapting to the needs of a full range of products from small household motors to large industrial motors, and ensuring the reliability and stability of topology switching under different operating conditions.

[0052] Preferably, from the center of the involute to the radially outer side, along the trajectory of the involute, the projected area of ​​the coil along the preset axis gradually increases.

[0053] With the above settings, more inductors 2 can be set on the same involute. Moreover, the size and number of turns of the coils of different inductors 2 are also different. By controlling different inductors 2 through a controllable switching network, more common-mode current can be suppressed, more frequency bands of current can be matched, and the suppression effect of common-mode current is better.

[0054] Preferably, the carrier plate 1 is further provided with a current detection module, a spectrum analysis module and a topology reconstruction control module.

[0055] This combination of functional modules constructs a complete closed-loop adaptive control system. The current detection module can collect the motor common-mode current signal in real time, the spectrum analysis module accurately analyzes the interference main frequency band, and the topology reconstruction module outputs switch control commands according to the frequency band characteristics, realizing intelligent dynamic control under all operating conditions. It can automatically match the optimal filtering parameters without manual intervention, further improving the response speed and accuracy of wideband adaptive filtering.

[0056] Specifically, the spectrum analysis module employs either an FFT (Fast Fourier Transform) unit or a compressed sensing sparse spectrum reconstruction unit.

[0057] The topology reconfiguration control module has a built-in memory that stores a mapping table of operating conditions and inductance parameters, and / or a processor equipped with a deep network reinforcement learning algorithm to achieve adaptive intelligent regulation.

[0058] The topologies that can be implemented by the controllable switching network include: all inductors connected in series (2 units), all inductors connected in parallel (2 units), a hybrid connection of multiple series units followed by a parallel connection, and multiple parallel units followed by a series connection.

[0059] The present invention provides a three-phase permanent magnet synchronous brushless DC motor, including a control circuit board, a stator and the printed circuit board, wherein the printed circuit board is disposed at one end of the stator, or the printed circuit board constitutes part of the control circuit board.

[0060] By placing the printed circuit board at one end of the stator, or by making the printed circuit board part of the control circuit board, common-mode current generation is directly suppressed at its source, completely eliminating the lead antenna effect of the external filter and significantly improving filtering attenuation efficiency. The stator blocks the common-mode interference path in situ, effectively avoiding coupling interference from external cables, greatly improving EMI attenuation. Simultaneously, it suppresses the common-mode shaft voltage generated by PWM inverter power supply at its source, reducing shaft current generation, preventing bearing lubrication film breakdown, significantly reducing the risk of motor bearing erosion, extending motor lifespan, and easily meeting overall EMC certification standards.

[0061] The three-phase permanent magnet synchronous brushless DC motor with the aforementioned printed circuit board can achieve full coverage of common mode current at high and low frequencies and adaptive EMI (electromagnetic interference) suppression under all operating conditions.

[0062] The motor of this application inherits the advantages of high saturation, high impedance and low loss of the magnetic ring inductor 2, while realizing standardized high-density integration of PCB (printed circuit board), without the need for additional wiring harness and bracket, and is suitable for miniaturized motor design.

[0063] The printed circuit board of this application can be prefabricated and tested, and the printed circuit board can be produced in a standardized manner. The assembly process is simplified, the yield is high, it is suitable for large-scale batch application, and it has strong mass production capability and controllable cost.

[0064] This section further explains the causes of electrical erosion in DC motor bearings and the generation of shaft voltage: When the motor is running, the potential difference generated between the inner and outer rings of the bearing is called shaft voltage. If a circuit is formed between the two ends of the bearing through the motor frame, the shaft voltage forms a shaft current. Shaft voltage exists as long as the motor rotates. Most DC motors are powered by PWM inverters. In this case, the motor's shaft voltage is mainly generated by the vector sum and non-zero zero-sequence component of the three-phase output voltage of the power supply. The PWM pulse width modulation of the inverter increases the high-frequency harmonic components in the speed control drive system. These harmonic components generate electromagnetic induction in parts such as the shaft, stator windings, and cables. The voltage coupling effect of the distributed capacitors inside the motor forms a common-mode circuit in the system. This common-mode voltage oscillates at high frequency and capacitively couples with the rotor, generating a pulse voltage between the shaft and ground. This voltage will generate a zero-sequence current in the system, and the motor bearing is part of this zero-sequence circuit. In addition, the generation of shaft voltage can also be caused by factors such as unipolar effects, accumulation of static charge, and external power supplies. Under normal circumstances, the shaft voltage of the motor is low, and the lubricating oil film inside the bearing can act as insulation, preventing the generation of shaft current. Once a certain value is exceeded, the oil film is broken down, resulting in a discharge and the formation of an electric current. The energy released by the partial discharge generates high temperatures, melting many tiny areas on the inner and outer rings or balls of the bearing, creating grooves, which increases friction and causes noise. The most significant characteristic of electro-erosion in motor bearings is the formation of dense, washboard-like grooves on the inner and outer rings and balls of the motor bearing.

[0065] The carrier board 1 is set as a ring structure, which is adapted to the shape of the stator end. There are a total of 24 groups of pads, and the radial spacing increases from the inside to the outside, which is adapted to the ring space wiring logic.

[0066] The magnetic ring inductor unit 2 uses a T10×6×5 ferrite magnetic ring and 10 turns of 0.8mm enameled wire. The unit parameters can be consistent (or customized as needed). After the pins are tinned, they are directly soldered to the pad group to form a regular ring inductor array 2.

[0067] like Figures 1-6As shown, the controllable switching network uses multiple MOSFET switching devices to realize three core topologies:

[0068] Fully Serial Mode: Maximum total inductance, suitable for low-frequency common-mode interference suppression;

[0069] Full parallel mode: minimum equivalent inductance, excellent high-frequency characteristics, and adaptable to high-frequency interference;

[0070] Grouped hybrid mode: Multiple groups are combined in series and parallel to adapt to mixed interference in the mid-frequency band.

[0071] The control system collects the common-mode current of the motor neutral point in real time, analyzes the interference frequency through FFT spectrum analysis, matches the optimal topology by looking up a table and switches in real time to achieve closed-loop adaptive filtering.

[0072] The printed circuit board (PCB) forms part of the control circuit board, thus constituting an integrated solution. In this embodiment, the PCB master board is integrated into the motor controller motherboard. An involute pad array is arranged at the power input terminal, and eight sets of magnetic ring inductors (two units) are installed to form a pre-filter array. No additional external filter is required, achieving integrated control, drive, and filtering. Actual measurements show an average reduction of 12dB in conducted emission peak at 150kHz–30MHz, and a 40% reduction in overall size, making it particularly suitable for compact automotive and home appliance motor applications.

[0073] Furthermore, the printed circuit board of this application is located at one end of the motor stator. Thus, inductor 2 is close to the MOSFET / IGBT bridge arm output, directly facing the high di / dt spikes (typically >1A / ns) during PWM commutation of each phase. All three sets of (U / V / W) phase currents flow through this array of inductors 2, with a natural current phase difference of 120° between phases. These three currents with a 120° phase difference interact in space. The inductor 2's involute-shaped arrangement utilizes the 120° phase difference and mutual inductance gradient to better reduce the common-mode current of the three-phase permanent magnet synchronous brushless DC motor.

[0074] Because inductor 2 is arranged in an involute pattern, in the central region (where mutual inductance M is large): strong coupling cancels out the PWM ripple of adjacent phases. This is the mechanism of multi-phase coupled inductor 2. Coupling in the same direction can reduce the amplitude of the output current ripple and double its frequency. In the outer region (where mutual inductance M is small): weak coupling preserves the independence of each phase, preventing one phase from dragging down other phases when it saturates. The involute pattern makes this "strong-weak coupling" transition continuous and controllable, which is better than the abrupt coupling of the "neat matrix arrangement".

[0075] The µ-i curve of the integral molded inductor 2 is a gradual decrease, not a cliff-like one. This means that when the motor starts / locks / is in a transient state, the phase current surges to 3-5 times the rated value, the µ of the magnetic powder core decreases slowly, and L decreases slowly, preventing sudden failure.

[0076] The distribution of inductors 2 along the involute curve ensures that no single inductor 2 is subjected to the maximum magnetic field for an extended period, which is beneficial for improving the overall saturation current capability.

[0077] Involutes can function as differential-mode EMI filters.

[0078] The PWM waveform output by the three-phase bridge is rich in switching frequency harmonics and high-frequency ringing caused by dead-time effects. This noise, when passing through the inductor array 2:

[0079] The distributed ladder network composed of involutes forms a broadband differential mode EMI suppression band with its equivalent cutoff frequency gradually changing along space, which is particularly effective for motor drive EMI in the range of 1-10MHz.

[0080] The involute curve allows the "go-back" paths of the U / V / W phases to be as compact as possible within a limited PCB area, while avoiding the crosstalk caused by the three phase paths intersecting.

[0081] The inductors are naturally arranged along a spreading curve, with sparser distribution in the center and outer rings, resulting in a uniform heat density distribution and avoiding the "central heat buildup" of matrix arrangements. Combined with copper plating on the PCB for heat dissipation, the thermal resistance is effectively reduced.

[0082] The present invention also provides an air conditioner, including the aforementioned three-phase permanent magnet synchronous DC brushless motor.

[0083] Air conditioners equipped with this motor do not require additional external EMI filters, significantly reducing the overall size and simplifying the assembly process. The two inductor units can be prefabricated and tested, and the standardized PCB surface mount production yields high output, making it suitable for large-scale mass production. At the same time, the average peak conducted emission of the entire unit can be reduced by more than 12dB, completely solving the problem of high-frequency harmonic interference in variable frequency air conditioner motors, improving the overall operational stability and electromagnetic compatibility performance, and meeting the compact and highly reliable design requirements of the home appliance industry.

[0084] It will be readily understood by those skilled in the art that, without conflict, the advantageous technical features of the above-mentioned methods can be freely combined and superimposed.

[0085] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention. The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the technical principles of the present invention, and these improvements and modifications should also be considered within the protection scope of the present invention.

Claims

1. A printed circuit board for use in a three-phase permanent magnet synchronous DC brushless motor, the printed circuit board comprising a carrier board (1), characterized in that, Multiple inductors (2) are integrated on the carrier plate (1). The multiple inductors (2) are arranged on the printed circuit board according to the involute trajectory. The winding of a single inductor (2) is wound around a preset axis to form a coil. The two ends of the coil along the preset axis are the large end and the small end, respectively. From the large end to the small end, the area of ​​the cross section of the coil perpendicular to the preset axis gradually decreases. The small end of the inductor (2) faces the center of the involute.

2. The printed circuit board according to claim 1, characterized in that, On the projection toward the printed circuit board, a V-shaped gap is formed between two adjacent inductors (2), the opening of the V-shaped gap facing away from the center of the involute.

3. The printed circuit board according to claim 1, characterized in that, The preset axis passes through the center of the involute.

4. The printed circuit board according to claim 1, characterized in that, In the radial direction of the involute, the distance between two adjacent inductors (2) is L, and L gradually increases from the center of the involute outward.

5. The printed circuit board according to any one of claims 1-4, characterized in that, The carrier plate (1) is also provided with a controllable switch network, which is electrically connected to all the inductors (2). The controllable switch network can connect at least two inductors (2) in series or in parallel, and can also connect multiple inductors (2) in series or in parallel.

6. The printed circuit board according to claim 5, characterized in that, From the center of the involute outwards, along the trajectory of the involute, the projected area of ​​the coil along the preset axis gradually increases.

7. The printed circuit board according to claim 5, characterized in that, The carrier board (1) is also equipped with a current detection module, a spectrum analysis module and a topology reconstruction control module.

8. A three-phase permanent magnet synchronous brushless DC motor, characterized in that, It includes a control circuit board, a stator, and a printed circuit board as described in any one of claims 1-6, wherein the printed circuit board is disposed at one end of the stator, or the printed circuit board constitutes part of the control circuit board.

9. An air conditioner, characterized in that, Including the three-phase permanent magnet synchronous DC brushless motor as described in claim 8.

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