Direct current asynchronous motor

Abstract

This invention discloses a DC asynchronous motor, relating to the field of motor drive technology. It includes: a stator, multiple teeth, and windings wound around the stator, with the windings having two phases; a rotor, which is a poleless rotor nested within the stator, with a gap between the stator and rotor between 0.1 and 10 mm; and a control circuit for outputting two independent power supplies, each electrically connected to one of the two phase windings of the stator. The control circuit synchronously supplies power to the two phase windings of the stator, and the two phase power supplies output have a signal phase angle. The two phase windings are wound around the teeth to form coils. The coils on the teeth of the same phase winding are connected in series with adjacent coils of the same phase, with the winding directions of the coils on adjacent teeth of the same phase winding being opposite. The technical solution provided by this invention solves the technical problems of relatively large size and low power density in existing two-phase asynchronous motors.

Description

Technical Field

[0001] This invention relates to the field of motor drive technology, and in particular to a DC asynchronous motor. Background Technology

[0002] Existing asynchronous motors often employ capacitor phase-shifting starting. However, these motors are directly powered by AC, and the power frequency cannot be adjusted, thus limiting speed control. To achieve multiple speeds, multiple wire ends need to be pulled from the windings, resulting in higher production costs and limited power density. Furthermore, capacitor phase-shifting motors exhibit uneven magnetic force at low speeds, generating harmonic vibrations that cannot be eliminated. Summary of the Invention

[0003] The main objective of this invention is to propose a DC asynchronous motor that aims to solve the problems of maximum speed limitation and multi-speed regulation limitation of capacitor phase-shifting asynchronous motors in the prior art, eliminate harmonic and harmonic vibration noise, and improve the power density of asynchronous motors.

[0004] One embodiment of the present invention provides a DC asynchronous motor comprising:

[0005] A stator, comprising a plurality of teeth and a winding wound around the stator, the winding having two phases; and The rotor, which is a poleless rotor, is nested within the stator, with a gap between the stator and rotor ranging from 0.1 mm to 10 mm; and, The control circuit is used to output two independent power supplies, which are electrically connected to the two phase windings of the stator respectively. The control circuit synchronously supplies power to the two phase windings of the stator, and the phase angle of the two-phase power supply output by the power supply is between 80 degrees and 100 degrees. The two-phase windings are wound around the teeth to form coils. The coils on the teeth of the windings belonging to the same phase are connected in series with the adjacent same-phase coils in turn. The coils on two adjacent teeth are out-of-phase coils. In the windings of the same phase, the winding directions of the coils on two adjacent teeth are opposite.

[0006] In one embodiment, each phase of the two-phase winding has independent input and output lines, and the independent power supply output by the control circuit is connected to the input and output lines of one phase of the winding.

[0007] In one embodiment, the stator further includes a yoke; the yoke is an annular ring, and each of the teeth is fixedly connected to the surface of the yoke; each of the teeth extends radially along the yoke.

[0008] In one embodiment, each of the teeth has a boot at its end, and the end of the boot facing the rotor has an arcuate surface, the axis of which coincides with the rotation center of the rotor.

[0009] In one embodiment, the rotor includes an iron core, a plurality of conductors, and two conductive rings; a plurality of conductor slots are uniformly formed along the circumference of the iron core, each conductor slot is formed along the axial direction of the iron core, and each conductor passes through the conductor slot; the conductive rings are disposed on both sides of the iron core, and the conductive rings are fixedly connected to both ends of each conductor.

[0010] In one embodiment, the rotor is a squirrel cage structure, and the conductor passes through the iron core and is electrically connected to the conductive rings on both sides; In one embodiment, the conductor is inclined relative to the axis of the iron core, and the angle between the extension direction of the conductor and the end face of the conductive ring is an acute angle.

[0011] In one embodiment, the conductive ring is a distributed conductive ring structure; The distributed conductive ring includes multiple arc segments, each arc segment having an equal radius, and every two opposite arc segments are connected to the same number of conductors. The distributed conductive rings on at least one side of the iron core are spliced ​​together to form mutually spaced circular rings.

[0012] In one embodiment, the conductive ring is an integral ring structure, and the conductive ring is fixedly connected to both sides of each iron core.

[0013] In one embodiment, the DC asynchronous motor is an internal rotor motor; The yoke is annular, and the teeth are located on the inner wall of the yoke and extend inward. The teeth surround and form the stator cavity, the rotor is rotatably disposed in the stator cavity, and an air gap is left between the outer peripheral surface of the rotor and the shoe portion; The rotor has a motor shaft at its center, and the motor shaft is fixedly connected to the iron core.

[0014] In one embodiment, the DC asynchronous motor is an external rotor motor; The rotor has an inner cavity, and the stator passes through the inner cavity of the rotor; The teeth are located on the outer wall of the yoke and extend outward, and an air gap is left between the outer surface of the boot and the inner wall of the rotor cavity; The stator center is connected to a support shaft via a bearing.

[0015] The technical solution of the present invention adopts a concentrated winding structure with independent coils and an adjacent layout with opposite phases. Compared with the distributed winding of the traditional capacitor motor, this results in shorter winding ends, higher tooth slot utilization, increased power density, and allows for the generation of greater magnetic flux in the same volume, thereby reducing the size of the motor while maintaining the same power.

[0016] Each tooth's coil is connected end-to-end with the adjacent in-phase coil; the input terminals of out-of-phase coils are adjacent, and their output terminals are adjacent. This differs from traditional sinusoidal windings or conventional distributed windings, optimizing the magnetomotive force waveform and reducing ineffective high-order harmonic components. Reduced harmonics mean lower core losses and rotor stray losses, directly improving motor efficiency. Furthermore, the arrangement of the input and output terminals of adjacent out-of-phase coils helps shorten the end winding length, reducing copper losses. Compared to traditional technologies, this invention can improve motor efficiency by 10%-20%, while also having a more compact structure. Attached Figure Description

[0017] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the structures shown in these drawings without creative effort.

[0018] Figure 1 This is a schematic diagram of a DC asynchronous motor according to an embodiment of the present invention; Figure 2 This is a schematic diagram of the stator structure of an embodiment of a DC asynchronous motor provided by the present invention; Figure 3 This is a schematic diagram of the rotor structure of an embodiment of the DC asynchronous motor provided by the present invention; Figure 4 A schematic diagram of the rotor core of an embodiment of a DC asynchronous motor provided by the present invention; Figure 5 A schematic diagram of the structure of an integral rotor of a DC asynchronous motor according to another embodiment of the present invention; Figure 6 A schematic diagram of the stator structure of another embodiment of the DC asynchronous motor provided by the present invention; Figure 7 A schematic diagram of the external rotor structure of another embodiment of the DC asynchronous motor provided by the present invention; Figure 8 A schematic diagram of the inner stator structure of another embodiment of the DC asynchronous motor provided by the present invention; Figure 9A schematic diagram of an embodiment of the DC asynchronous motor provided by the present invention; Figure 10 A waveform diagram of an embodiment of the alternating voltage output by a DC asynchronous motor provided by the present invention; Figure 11 A circuit diagram of an embodiment of the inverter circuit provided by the present invention; Figure 12 A circuit diagram of another embodiment of the inverter circuit provided by the present invention; Figure 13 A circuit diagram of an embodiment of the pre-driving circuit provided by the present invention.

[0019] Explanation of icon numbers: 10. Stator; 11. Yoke; 12. Tooth section; 13. Boot section; 14. Coil; 15. Stator inner cavity; 20. Rotor; 21. Iron core; 22. Conductor; 221. Conductor groove; 23. Conductor ring; 231. Integrated conductor ring; 30. Motor shaft; 31. Support shaft; 32. Bearing.

[0020] The realization of the objective, functional features and advantages of the present invention will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0021] 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 a part of the embodiments of the present invention, and not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0022] It should be noted that if the embodiments of the present invention involve directional indicators (such as up, down, left, right, front, back, etc.), the directional indicators are only used to explain the relative positional relationship and movement of the components in a specific posture. If the specific posture changes, the directional indicators will also change accordingly.

[0023] Furthermore, if the embodiments of this invention involve descriptions such as "first" or "second," these descriptions are for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined with "first" or "second" may explicitly or implicitly include at least one of those features. Additionally, the use of "and / or" or "and / or" throughout the text includes three parallel solutions. For example, "A and / or B" includes solution A, solution B, or a solution that simultaneously satisfies A and B. Furthermore, the technical solutions of the various embodiments can be combined with each other, but this must be based on the ability of those skilled in the art to implement them. When the combination of technical solutions is contradictory or impossible to implement, it should be considered that such a combination of technical solutions does not exist and is not within the scope of protection claimed by this invention.

[0024] This invention proposes a DC asynchronous motor.

[0025] Please see Figures 1 to 8 In one embodiment of the present invention, the DC asynchronous motor includes: a stator 10, including a plurality of teeth 12 and windings wound around the stator, wherein the number of windings is 2; The rotor 20 is a non-magnetic rotor and does not have magnetism when it is not energized; the rotor 20 and the stator 10 are nested together, and the gap between the stator 10 and the rotor 20 is between 0.1 mm and 10 mm. The control circuit is used to output two independent power supplies, which are electrically connected to the two phase windings of the stator 10 respectively. The control circuit synchronously supplies power to the two phase windings of the stator 10. The phase angle of the two-phase power supply output by the power supply is between 80 degrees and 100 degrees. The two-phase windings are wound around the tooth 12 to form coils. The coils on the tooth of the winding of the same phase are connected in series with the adjacent same-phase coils in turn. The coils on two adjacent tooth 12s are out-of-phase coils. In the winding of the same phase, the winding directions of the coils on two adjacent tooth 12s are opposite.

[0026] The stator 10 includes a plurality of teeth 12 facing the rotor 20, and two-phase windings are wound around the teeth 12 to form coils 14; the coils 14 on each tooth 12 are connected in series with adjacent coils 14 of the same phase; in the windings of the same phase, there is a gap of one tooth 12 between the coils 14 on two adjacent teeth 12.

[0027] Specifically, the non-magnetic rotor itself does not have magnetic poles, and the non-magnetic rotor is magnetically conductive; the stator 10 and the rotor 20 are nested together and coaxially arranged, and each tooth 12 is wound with at least one turn of coil 14. The coil 14 on the tooth 12 is electrically connected to two phases, and each tooth 12 coil 14 is connected end to end with the adjacent same-phase coil 14 in sequence. The input ends of the opposite-phase coils 14 are adjacent, and the output ends of the opposite-phase coils 14 are adjacent.

[0028] In the winding of the same phase, the coils on two adjacent teeth are spaced apart by one tooth, and the winding directions of the coils on two adjacent teeth are opposite.

[0029] The signal phase angle of the two-phase winding is ; Where, θ max θ is the maximum value of the difference between the drive signals of the two phase windings; mi两 The minimum difference between the drive signals of the two phase windings is given by x, where x is the number of winding phases. The torque of an asynchronous motor can be altered by controlling the signal phase angle of the two-phase windings, thus achieving stepless speed regulation. Employing a concentrated winding configuration with adjacent, non-phase windings significantly shortens the length of the winding ends. The end windings do not participate in electromagnetic energy conversion; they only generate heat. Shortening the ends directly reduces ineffective resistance, thereby lowering copper losses.

[0030] For a two-phase asynchronous motor, the strength and shape (circular or elliptical) of the rotating magnetic field directly depend on the signal phase angle of the two-phase currents. When the signal phase angle is close to the ideal value, the resulting magnetic field is close to a circular rotating magnetic field, and the motor output torque is at its maximum. When the signal phase angle deviates from the limit value, the resulting magnetic field gradually becomes a flattened elliptical magnetic field, and the effective torque component decreases. By continuously adjusting the signal phase angle θ within a wide range of 175.5° to 4.5°, the control circuit can directly change the characteristics of the resulting magnetic field, thereby linearly changing the motor's output torque. Under a constant load, the change in torque directly manifests as a change in speed, thus achieving stepless speed regulation.

[0031] In existing technologies, traditional capacitor-driven asynchronous motors are difficult to miniaturize due to the need to accommodate the secondary winding and capacitor. This invention directly generates a drive signal with a signal phase angle through a control circuit, eliminating the need for a bulky starting capacitor and dedicated space for the secondary winding. Because it is no longer constrained by the slot requirements for accommodating the secondary winding, the stator 10 design can be more compact, significantly improving the motor's power density and solving the problem of relatively large size in existing technologies.

[0032] See Figure 2In one embodiment of the present invention, the stator 10 further includes a yoke 11; the yoke 11 is an annular ring, and each of the teeth 12 is fixedly connected to the surface of the yoke 11; each of the teeth 12 extends radially along the yoke 11.

[0033] Specifically, the yoke 11 is in the shape of a ring; each tooth 12 is fixedly connected to the surface of the yoke 11, and each tooth 12 extends radially along the yoke 11; a boot 13 is fixedly connected to one end of each tooth 12 away from the yoke 11, and the coil 14 is sleeved on the circumference of the tooth 12 and extends axially.

[0034] The included angle between every two adjacent teeth 12 , ; Where θ c θ is the included angle between every two adjacent teeth 12. c mi两 θ is the minimum value of the included angle between two adjacent teeth 12. c max Z represents the maximum included angle between two adjacent teeth 12, and Z represents the number of teeth 12 in a single stator 10. The included angles of the teeth 12 do not need to be uniformly set. The minimum included angle between two adjacent teeth 12 is 6°, and the maximum included angle between two adjacent teeth 12 is 54°. Teeth 12 are allowed between these two extreme values, reducing the difficulty of production and assembly.

[0035] Please see Figure 2 In one embodiment of the present invention, each of the teeth 12 is provided with a boot 13 at its end. The end of the boot 13 facing the rotor 20 has an arcuate surface, and the axis of the arcuate surface coincides with the rotation center of the rotor 20.

[0036] Specifically, the toothed portion 12 is arranged radially along the yoke portion 11 and extends toward the rotor 20. The end of the boot portion 13 facing the rotor 20 has an arc, and the end of each boot portion 13 facing the rotor 20 forms an approximately circular curved surface. The boot portion 13 is an arc surface and coaxial with the rotor 20, ensuring uniform air gap length.

[0037] See Figures 3 to 4 In one embodiment of the present invention, the rotor 20 includes an iron core 21, a plurality of conductors 22 and two conductive rings 23; a plurality of conductor grooves 221 are uniformly opened along the circumference of the iron core 21, each conductor groove 221 is opened along the axial direction of the iron core 21, and each conductor 22 passes through the conductor groove 221; the conductive rings 23 are disposed on both sides of the iron core 21, and the conductive rings 23 are fixedly connected to both ends of each conductor 22.

[0038] Specifically, the iron core 21 is provided with a plurality of conductor grooves 221, each of which is an axial through groove facing the axis of the stator 10.

[0039] See Figure 3 In one embodiment of the present invention, the conductive ring 23 is a distributed conductive ring 23 structure; The distributed conductive ring 23 includes multiple arc segments, each arc segment having an equal radius, and every two opposite arc segments are connected to the same number of conductors 22. The distributed conductive rings 23 on at least one side of the iron core 21 are spliced ​​together to form a closed ring that is in contact with each other.

[0040] Specifically, the conductive rings 23 are distributed conductive rings 23, each with an equal arc, and the number of conductors 22 between any two opposing distributed conductive rings 23 is equal. The distributed conductive rings 23 on one side of the iron core 21 form mutually contacting rings. The distributed conductive rings 23 alter the current path of the rotor 20, coordinating with the magnetic field distribution of the stator 10 to optimize the motor's starting or speed regulation performance.

[0041] Please see Figure 5 In one embodiment of the present invention, the conductive ring 23 is an integral ring structure, and the conductive ring 23 is fixedly connected to both sides of each iron core 21. Specifically, the conductive ring 23 is an integral conductive ring 231. The conductive ring 23 and the conductor 22 are integrally formed by aluminum die casting process, or connected by welding copper strips to copper rings. The integral conductive ring 231 has a simple structure, low resistance, and is suitable for high-efficiency operation conditions; the integral conductive ring 231 is suitable for large-scale automated production, reducing costs.

[0042] In one embodiment of the present invention, the rotor 20 is a squirrel cage structure, and the conductor 22 passes through the iron core 21 and is electrically connected to the conductive rings 23 on both sides. The conductor 22 is inclined relative to the axis of the iron core 21, and the angle between the extension direction of the conductor 22 and the end face of the conductive ring 23 is an acute angle.

[0043] Specifically, the angle between each conductor 22 and the conductive ring 23 is an acute angle; the extension of the axis of the rotor core 21 intersects the projection of the extension of the central axis of the conductor 22 onto the vertical plane; the rotor core 21 has a plurality of inclined slots for accommodating the conductor 22 in the inner circumference, the inclination angle of the inclined slots is the same as the inclination angle of the conductor 22, and the inclined slots are coaxially arranged with the conductor 22 inside them.

[0044] Conductor 22 is inclined relative to tooth 12. When the magnetic field of tooth 12 sweeps across rotor 20, conductor 22 does not enter or leave the strong magnetic field region instantaneously, but gradually enters. This effectively weakens the high-order harmonic magnetic field caused by the concentrated winding. High-order harmonics will generate high-frequency eddy current losses on the surface of iron core 21 and in conductor 22 of rotor 20. Suppressing harmonics reduces the heat generated in this part and improves the effective output power. At the same time, the inclined conductor 22 has a larger cross-sectional area than the vertically arranged conductor 22. Each conductor 22 is helical, and the projection of each conductor 22 toward the winding coincides with at least three of the windings, thereby increasing the traction force exerted by the windings on each conductor 22 and thus increasing the torque of the overall rotor 20.

[0045] In one embodiment of the present invention, the DC asynchronous motor is an internal rotor 20 motor; The yoke 11 is annular, and the teeth 12 are provided on the inner wall of the yoke 11 and extend inward. The teeth 12 surround and form the stator cavity 15, and the rotor 20 is rotatably disposed in the stator cavity 15. An air gap is left between the outer peripheral surface of the rotor 20 and the shoe 13. The rotor 20 has a motor shaft 30 at its center, and the motor shaft 30 is fixedly connected to the iron core 21.

[0046] Specifically, the stator 10 has a stator cavity 15, the rotor 20 is disposed in the stator cavity 15, and there is a gap between the inner wall of the stator cavity 15 and the side surface of the iron core 21.

[0047] A motor shaft 30 is inserted between the rotor 20 and the iron core 21. The motor shaft 30 is fixedly connected to the center of the iron core 21. The axis of the motor shaft 30 coincides with that of the iron core 21. The motor shaft 30 can be integrally formed with the iron core 21. Alternatively, a hole can be made in the center of the iron core 21 to allow the motor shaft 30 to be interference-fitted with the iron core 21.

[0048] Please see Figures 7 to 8 In one embodiment of the present invention, the DC asynchronous motor is an external rotor 20 motor; The rotor 20 has a rotor cavity, and the stator 10 passes through the rotor cavity; The toothed portion 12 is provided on the outer wall of the yoke portion 11 and extends outward, and an air gap is left between the outer surface of the boot portion 13 and the inner wall of the rotor cavity; The center of the stator 10 is connected to a support shaft 31 via a bearing 32.

[0049] Specifically, the rotor 20 has an inner cavity, the stator 10 passes through the inner cavity, there is a gap between the inner cavity and each shoe part 13, and the center of the stator 10 is fixedly connected to a support shaft 31 through a bearing 32. The support shaft 31 and the rotor 20 can be connected through a support rod or other structure.

[0050] Please see Figure 9 In one embodiment of the present invention, the control circuit includes a main circuit, two pre-drive circuits, and two inverter circuits. The main circuit generates two sets of pulse width modulation signals. The two pre-drive circuits, connected to the main circuit, receive the two sets of pulse width modulation signals and output corresponding power drive signals. The two inverter circuits have power supply terminals for connecting to a DC power source, output terminals for connecting to two stator windings, and controlled terminals for connecting to the signal output terminals of the two pre-drive circuits. The two inverter circuits convert the connected DC power source into two independent alternating voltages based on the two sets of power drive signals. Each alternating voltage drives one stator winding. A certain signal phase angle exists between any two adjacent alternating voltages.

[0051] Please see Figure 10 "A-path alternating voltage" and "B-path alternating voltage" are two independent sinusoidal waves with specific signal phase angles, which work together to synthesize a rotating magnetic field. The main circuit is configured to output two sets of pulse width modulation (PWM) signals. These two sets of PWM signals can be generated by a microcontroller with multiple PWM output channels, with the output timing and waveform of each channel programmed. Alternatively, multiple independent oscillators and phase-shifting circuits can be used to generate logic control signals with specific phase relationships.

[0052] The power supply terminals of the two inverter circuits are used to connect to a DC power source. This DC power source can be directly generated by connecting an external AC power source through the rectifier circuit built into the control circuit, or it can be a DC power source input after being rectified and filtered by an external rectifier circuit, such as an external power adapter or switching power supply module. Furthermore, the DC power source can also be a pure DC power source directly provided by a battery pack, lithium battery pack, supercapacitor, or photovoltaic power generation unit. In this way, the control circuit can flexibly adapt to various application scenarios such as mains power supply, industrial DC bus power supply, and mobile battery power supply.

[0053] Two pre-drive circuits are connected between the main circuit and the two inverter circuits. The controlled terminals of the two inverter circuits are connected one-to-one with the signal output terminals of the two pre-drive circuits, while the input terminals of the two pre-drive circuits are connected one-to-one with the multiple signal output terminals of the main circuit. Each inverter circuit converts the DC power supply into an alternating voltage based on the power drive signal it receives from the corresponding pre-drive circuit. For example, each inverter circuit can consist of an H-bridge composed of four switching transistors. In this architecture, the control circuit first outputs two sets of pulse width modulation signals containing complementary logic. After level shifting and power amplification by the corresponding pre-drive circuits, the two sets of pulse width modulation signals form two sets of power drive signals that can drive the gates of the switching transistors, thereby periodically turning the switching transistors on and off, and generating an alternating voltage at the output.

[0054] The asynchronous motor has two phases. The main circuit outputs two sets of pulse width modulation signals, which are amplified by two pre-drive circuits to output two sets of power drive signals to drive two inverter circuits. These two inverter circuits generate two alternating voltages with a certain signal phase angle to control the energization of two independent windings of the motor stator.

[0055] In one embodiment, the inverter circuit includes a first bridge arm and a second bridge arm. The first bridge arm of the inverter circuit includes a first switch Q1 and a second switch Q2, and the second bridge arm includes a third switch Q3 and a fourth switch Q4. The first terminal of the first switch Q1 is connected to a DC power supply, and the second terminal of the first switch Q1 is connected to the first terminal of the second switch Q2. The second terminal of the second switch Q2 is grounded. The first terminal of the third switch Q3 is connected to a DC power supply, and the second terminal of the third switch Q3 is connected to the first terminal of the fourth switch Q4. The second terminal of the fourth switch Q4 is grounded. The connection point between the first switch Q1 and the second switch Q2 is the midpoint of the first bridge arm, and the connection point between the third switch Q3 and the fourth switch Q4 is the midpoint of the second bridge arm. The midpoints of the first and second bridge arms are connected one-to-one to the two ends of the same stator winding.

[0056] The midpoint of the first bridge arm and the midpoint of the second bridge arm are used to output one alternating voltage.

[0057] In one feasible embodiment, each set of power drive signals may include a first drive signal and a second drive signal to drive the first switch Q1 of the first bridge arm and the third switch Q3 of the second bridge arm, respectively. At this time, the second switch Q2 of the first bridge arm and the fourth switch Q4 of the second bridge arm can be connected to external control signals as the third and fourth drive signals. These signals can be output from a control module outside the DC asynchronous motor; alternatively, the main circuit within the DC asynchronous motor can be configured to output the third and fourth drive signals (skipping the pre-drive step). In this configuration, the first drive signal drives the first switch Q1 of the first bridge arm, the third drive signal drives the second switch Q2 of the first bridge arm, the second drive signal drives the third switch Q3 of the second bridge arm, and the fourth drive signal drives the fourth switch Q4 of the second bridge arm, thereby achieving complete takeover and integrated control of the entire H-bridge inverter circuit. In other words, the inverter circuit requires a first drive signal, a second drive signal, a third drive signal, and a fourth drive signal for driving. The first and second drive signals are two signals output by a pre-drive circuit after a set of pulse width modulation signals output by the main circuit are processed by a pre-drive circuit. The third and fourth drive signals can be directly output by the main circuit without pre-drive (because the transistors do not need pre-drive), or they can be connected by an external circuit. The third and fourth drive signals can be drive signals with a high level of 1 and a low level of 0, which are only used to drive the normally open and normally closed second switch Q2 and fourth switch Q4. Therefore, their generation is relatively simple, as explained in the following details.

[0058] The first and second drive signals are configured as high-frequency modulated signals, operating alternately in time. Each operating cycle includes a high-level period (operating period) and a low-level period (off-end period). During the high-level period, the duty cycle increases progressively from zero to a preset peak value, then gradually decreases back to zero. The frequency of the duty cycle variation is not limited and can be adjusted according to actual accuracy requirements. For example, a high-level period can contain 256 discrete duty cycle changes, or it can have 10, or any other number of modulations. The magnitude of the preset peak value is also not limited and depends on the rated voltage or power requirement of the target load. It should be noted that one operating cycle is defined as the time it takes for either the first or second drive signal to complete one full electrical cycle, which includes a high-level period and a low-level period in time.

[0059] The third and fourth drive signals are configured as power frequency commutation signals (or normally-on signals). During the period when the first drive signal is at a high level, the fourth drive signal, which is diagonally opposite to it, remains at a constant high level (duty cycle of 1). The first switch Q1 and the fourth switch Q4 are turned on, and the current flows from the power input terminal into the load through the first switch Q1 and back to ground through the fourth switch Q4, making the midpoint voltage of the first bridge arm higher than the midpoint voltage of the second bridge arm, thus forming a positive output voltage. Similarly, during the period when the second drive signal is at a high level, the third drive signal, which is diagonally opposite to it, remains at a constant high level, and the third switch Q3 and the second switch Q2 are turned on. The current flows from the power input terminal into the load through the third switch Q3 and back to ground through the second switch Q2, making the midpoint voltage of the second bridge arm higher than the midpoint voltage of the first bridge arm, thus forming a reverse output voltage. Thus, through the above hybrid driving strategy, the potential difference between the midpoints of the two bridge arms periodically reverses between positive and negative polarities as the timing changes, thereby achieving precise generation and modulation of the AC output waveform (i.e., alternating voltage).

[0060] In this embodiment, the midpoint of the first bridge arm can be connected to one end of a stator winding, and the midpoint of the second bridge arm can be connected to the other end of the stator winding; the midpoint of the first bridge arm and the midpoint of the second bridge arm are used to output an alternating voltage.

[0061] It is important to note that the above describes the power drive signal, which is actually mapped and executed by the pulse width modulation signal output from the main circuit. Specifically, the main circuit first generates a pulse width modulation signal that is completely consistent with the power drive signal in terms of timing, frequency, and duty cycle variation. These pulse width modulation signals are then processed by the aforementioned pre-drive circuit and finally converted into a power drive signal with driving capability, thereby driving the first to fourth switching transistors Q4 to turn on or off according to a preset strategy, synthesizing the required alternating voltage waveform across the stator winding.

[0062] In one embodiment, such as Figure 11As shown, the first switch Q1 and the third switch Q3 are MOSFETs or IGBTs, and the second switch Q2 and the fourth switch Q4 are transistors. The main circuit includes N signal output ports, each used to output a set of pulse width modulation signals. The signal output ports include: a first output terminal, a second output terminal, a third output terminal, and a fourth output terminal. The pre-drive circuit includes a first pre-drive unit and a second drive unit. The input terminal of the first pre-drive unit is connected to the first output terminal of the main circuit, and the output terminal of the first pre-drive unit is connected to the controlled terminal of the first switch Q1. The input terminal of the second pre-drive unit is connected to the second output terminal of the main circuit, and the output terminal of the second pre-drive unit is connected to the controlled terminal of the third switch Q3. The controlled terminal of the second switch Q2 is connected to the third output terminal of the main circuit, and the controlled terminal of the fourth switch Q4 is connected to the fourth output terminal of the main circuit.

[0063] First, for the first switch Q1 and the third switch Q3, this embodiment adopts a "MOSFET + pre-drive unit" configuration. Since the first switch Q1 and the third switch Q3 are responsible for high-frequency chopping, they have extremely high requirements for switching speed and losses. Therefore, MOSFETs with low on-resistance and fast switching characteristics are selected. However, as high-side switches, the gate drive voltage of MOSFETs usually needs to be higher than the DC bus voltage (for NMOS) or requires high-voltage level shifting (for PMOS), and their gates have large parasitic capacitances. Therefore, the main circuit and the MOSFETs can be connected through a first pre-drive unit and a second pre-drive unit. The pre-drive unit converts the low-voltage logic signal output from the main circuit into a high-voltage signal with sufficient driving capability, ensuring that the MOSFETs can be quickly and completely turned on and off, thereby guaranteeing the waveform quality and efficiency of high-frequency modulation.

[0064] Secondly, for the second switch Q2 and the fourth switch Q4, this embodiment adopts a low-cost configuration of "transistor + direct connection control". Since the second switch Q2 and the fourth switch Q4 mainly undertake the task of power frequency commutation (low frequency constant on) in the control strategy of this invention, the requirement for switching speed is relatively low, so a cheaper transistor is selected. More importantly, the emitter of the lower bridge arm switch is directly grounded, which is a low-side switch. As a current-controlled device, the transistor has a low base conduction threshold voltage (about 0.7V), and the reference potential is the ground potential. This means that the normal logic level (such as 3.3V or 5V) output by the third and fourth output terminals of the main circuit is sufficient to drive the transistor to saturation conduction. Therefore, this embodiment creatively eliminates the pre-drive circuit of the lower bridge arm and directly connects the control port to the controlled terminal of the transistor, simplifying the circuit structure.

[0065] It is understood that each set of pulse width modulation signals specifically includes an independent first pulse width modulation signal and a second pulse width modulation signal. The first pre-drive unit is configured to receive the first pulse width modulation signal to drive and control the first switch Q1; the second pre-drive unit is configured to receive the second pulse width modulation signal to drive and control the second switch Q2. In terms of waveform characteristics, the first or second pulse width modulation signal presents as a high-frequency pulse sequence within one working cycle, exhibiting alternating high-level and low-level periods. Specifically, during the high-level period, its pulse duty cycle discretely changes according to the rule of "gradually increasing from zero to a preset peak value, and then gradually decreasing from the preset peak value back to zero." Based on this, the first pre-drive unit can analyze the received first pulse width modulation signal to output complementary high-side and low-side drive signals to control the on / off state of the first switch Q1; similarly, the second pre-drive unit can perform the same processing on the received second pulse width modulation signal to output a corresponding drive signal to control the on / off state of the third switch Q3.

[0066] When the second switch Q2 and the fourth switch Q4 are transistors, circuit costs can be saved.

[0067] In one embodiment, such as Figure 12 As shown, the first switching transistors Q1 to the fourth switching transistors Q4 are all MOSFETs or IGBTs. Correspondingly, the first pre-drive unit of the pre-drive circuit can output a first drive signal based on one pulse width modulation signal from a set of pulse width modulation signals, and the second pre-drive unit of the corresponding pre-drive circuit can output a second drive signal based on another pulse width modulation signal from the same set of pulse width modulation signals. In this case, the main circuit can also generate another N sets of pulse width modulation signals (here referred to as N sets of lower-transistor pulse width modulation signals). The first pre-drive unit of the corresponding pre-drive circuit can also output a third drive signal based on one lower-transistor pulse width modulation signal from a set of lower-transistor pulse width modulation signals, and the second pre-drive unit of the corresponding pre-drive circuit can also output a fourth drive signal based on another lower-transistor pulse width modulation signal from the same set of lower-transistor pulse width modulation signals.

[0068] like Figure 13The diagram illustrates an embodiment of an integrated driver chip used in a pre-drive circuit. This chip can be an LKS580 / SOP8 or a half-bridge driver chip with the same pin functions. The chip has a power supply pin (Pin1VCC), a ground pin (Pin4COM / GND), a bootstrap voltage pin (Pin8VB) for constructing the bootstrap circuit, and a high-side floating ground pin (Pin6VS). Regarding the specific connection and application logic: First, for a hybrid architecture of "upper MOS + lower transistor": only the chip's high-side drive capability is utilized. The chip's input (e.g., Pin2HIN) receives signals from the main circuit, while the seventh pin (Pin7HO, i.e., the high-side output) is connected as an output to the gate of the first switching transistor Q1 (the upper transistor). The floating high voltage generated by the external bootstrap diode and capacitor is used to pre-drive the upper transistor; in this case, the fifth pin (Pin5LO) can be left floating or unused. Second, for an "all-MOS" architecture: the chip is fully utilized to drive a complete bridge arm. The chip's two input terminals (Pin2HIN and Pin3LIN) receive complementary PWM signals from the main circuit. Pin 7HO outputs a first drive signal (high-voltage drive) to drive the first switch Q1, and pin 5LO (low-side output) outputs a third drive signal (low-voltage drive) to drive the second switch Q2. Similarly, another identical chip uses its seventh and fifth pins to output a second and a fourth drive signal, respectively, to drive the third and fourth switches Q4.

[0069] In one embodiment, the alternating voltage changes periodically, and the waveform of the alternating voltage changes from zero to a preset peak value and then back to zero within a single cycle.

[0070] In this embodiment, the waveform of the alternating voltage within a single cycle is a sine wave.

[0071] Understandably, during the first half of the operating cycle (positive half-cycle), the first drive signal is at a high level with its duty cycle varying from zero to a peak value and back to zero. At this time, the upper transistor of the first bridge arm (the first switch Q1) performs high-frequency chopping, while the fourth switch Q4 on the diagonal is constantly conducting, allowing current to flow through the stator winding in the positive direction. Since the average voltage across the stator winding depends on the duty cycle of the drive signal, the stator winding exhibits a positive dome-shaped wave consistent with the envelope of the first drive signal during this phase (i.e., the voltage rises from 0 to a positive peak value and then drops to 0). In the second half of the operating cycle (negative half-cycle), the first drive signal is cut off, and the second drive signal begins to operate. At this time, the second drive signal controls the upper transistor of the second bridge arm (the third switch Q3) to perform high-frequency chopping with the same duty cycle, while the second switch Q2 on the diagonal is constantly conducting. Crucially, at this time, the current flows through the stator winding in the opposite direction (inflow from the second bridge arm and outflow from the first bridge arm), thus creating voltages of opposite polarity across the stator winding. During this stage, the stator winding exhibits a negative peak wave (i.e., the voltage drops from 0 to a negative peak and then rises back to 0). Thus, as the first and second drive signals alternate in timing, the voltage across the stator winding is composed of positive and negative peak waves, forming a complete, periodically changing AC voltage waveform (sine wave-like).

[0072] This type of sinusoidal drive method enables the drive current waveform in the stator winding to remain continuous and smoothly transition in the time domain, reducing the high-order harmonic content in the voltage / current waveform, thereby making the air gap magnetic field distribution inside the motor closer to the ideal circular rotating magnetic field.

[0073] Furthermore, the reason why this quasi-sine wave drive method can effectively reduce motor vibration is fundamentally due to the elimination of commutation shock in traditional square wave drives. Specifically, in traditional square wave or trapezoidal wave drives, the current undergoes a drastic change at the moment of commutation. This discontinuous current step causes huge instantaneous fluctuations in the motor's output torque (i.e., torque pulsation), which in turn causes vibration of the rotor's mechanical structure. In this embodiment, by gradually modulating the duty cycle, the drive voltage and current present a smooth quasi-sine wave, eliminating the drastic current change point. This allows the electromagnetic torque generated by the motor to remain constant or fluctuate slightly on the time axis, achieving flexible commutation and thus improving the smoothness and quietness of motor operation.

[0074] In one embodiment, the DC asynchronous motor further includes a power supply circuit, which includes a rectifier module, a first voltage conversion module, and a second voltage conversion module connected in sequence. The input terminal of the rectifier module is used to connect to an external AC power supply and to convert the external AC power supply into DC power supply for output. The power supply terminals of N inverter circuits are connected to the output terminal of the rectifier module. The input terminal of the first voltage conversion module is connected to the output terminal of the rectifier module and is used to step down the DC power supply output by the rectifier module to a first voltage DC power supply and output it. The power supply terminals of N pre-drive circuits are connected to the output terminal of the first voltage conversion module. The input terminal of the second voltage conversion module is connected to the output terminal of the first voltage conversion module and is used to step down the first voltage DC power supply output by the first voltage conversion module to a second voltage DC power supply and output it. The power supply terminal of the main circuit is connected to the output terminal of the second voltage conversion module.

[0075] The power supply circuit has a rectifier module at the front end, which is directly connected to an external AC power source (such as 220V AC mains) and converts it into a high-voltage DC power supply. This high-voltage DC bus is directly connected to the power supply terminals of N inverter circuits, providing the main energy source for the motor drive, i.e., the power loop. The pre-drive circuit (and the power transistor gate) requires a medium-voltage DC power supply of a specific amplitude, such as 12V or 15V, to overcome the gate capacitance and maintain reliable conduction. This embodiment includes a first voltage conversion module, which can be a high-voltage Buck converter or a flyback switching power supply. The input of the first voltage conversion module is connected to the output of the rectifier module, stepping down the DC power output of the rectifier module to the first voltage DC power supply to supply the N pre-drive circuits, ensuring that the drive signal has sufficient power strength. In addition, the main circuit requires a low-voltage logic power supply, such as 3.3V or 5V. Therefore, this power supply circuit further includes a second voltage conversion module, which can be an LDO linear regulator or a low-voltage DC-DC converter. The input of the second voltage conversion module is connected to the output of the first voltage conversion module, which steps down the first voltage DC power supply to the second voltage DC power supply. This avoids the large voltage drop losses that occur when directly stepping down from the high-voltage bus to the low-voltage bus, significantly optimizing power conversion efficiency and thermal management performance.

[0076] In summary, through this integrated power management strategy, the entire DC asynchronous motor can operate independently with only one external AC input, without the need for an additional auxiliary power adapter, which greatly simplifies the external wiring and installation costs of the system.

[0077] In one embodiment, the main circuit is configured to adjust the duty cycle and / or frequency of the generated N sets of pulse width modulation signals according to the target load, so as to change the torque of the DC asynchronous motor to adapt to the target load; wherein the duty cycle and / or frequency of the pulse width modulation signal is positively correlated with the torque of the DC asynchronous motor.

[0078] This embodiment provides a closed-loop control scheme. In one feasible implementation, the main circuit can dynamically adjust the duty cycle and / or frequency of each pulse width modulation signal in each generated pulse width modulation signal according to the real-time operating status parameters of the target load, such as the magnitude of the feedback current in the stator winding or the difference between the real-time speed of the rotor and the target speed. This changes the average voltage amplitude or magnetic field rotation speed applied across the stator winding, so that the electromagnetic torque output by the motor can follow and match the torque demand of the load in real time. For example, it can automatically increase torque when the load increases and automatically save energy when the load decreases.

[0079] On the one hand, the duty cycle directly determines the effective value of the inverter circuit's output voltage, i.e., the average voltage. Specifically, when the duty cycle is increased, the average voltage applied to the stator windings increases. According to Ohm's law and the principle of the equivalent circuit of a motor, the increase in input voltage will cause the excitation current flowing through the windings to increase. Since the electromagnetic torque of the motor is proportional to the product of the air gap flux and the stator current, the increase in current directly translates into an increase in electromagnetic driving force, enabling the motor to output greater torque to overcome load resistance.

[0080] On the other hand, frequency directly determines the synchronous speed of the stator rotating magnetic field, which in turn determines the mechanical speed of the rotor. According to the power formula (power = torque × angular velocity), under the premise of maintaining torque, increasing the drive frequency means that the motor speed increases, enabling it to output more mechanical work per unit time, i.e., increasing the output power. Therefore, simultaneously increasing the duty cycle and frequency can comprehensively improve the motor's output torque reserve and work efficiency, thereby achieving effective adaptation to heavy loads or high-power target loads.

[0081] Working principle and effect The DC asynchronous motor provided by this invention is powered by a sinusoidal power supply with two phases 90 degrees out of phase. The stator 10, with its end-to-end, opposite-phase adjacent connections, generates a rotating magnetic field in the air gap. This magnetic field cuts through the rotor 20 conductor 22, inducing a current in the conductor 22. The induced current interacts with the rotating magnetic field to generate electromagnetic torque, driving the rotor 20 to rotate.

[0082] Compared with traditional capacitor motors, the motor of this invention has reduced leakage reactance and improved power factor. Tests have verified that it can improve operating efficiency by 10%-20%, and it also has the advantages of small size and light weight.

[0083] The above description is merely an exemplary embodiment of the present invention and does not limit the patent scope of the present invention. Any equivalent structural transformations made using the contents of the present invention's specification and drawings under the technical concept of the present invention, or direct / indirect applications in other related technical fields, are included within the patent protection scope of the present invention.

Claims

1. A DC asynchronous motor, characterized in that, include: The stator (10) includes a plurality of teeth (12) and a winding wound around the stator (10), the winding having two phases; as well as The rotor (20) is a poleless rotor and is nested with the stator (10), with a gap between the stator and the rotor between 0.1 mm and 10 mm; and, The control circuit is used to output two independent power supplies. The two independent power supplies are electrically connected to the two phase windings of the stator (10) respectively. The control circuit supplies power to the two phase windings of the stator (10) synchronously. The phase angle of the two phase power supply output by the power supply is between 80 degrees and 100 degrees. The two-phase windings are wound around the teeth (12) to form coils (14). The coils (14) on the teeth (12) of the windings belonging to the same phase are connected in series with the adjacent same-phase coils (14) in turn. The coils (14) on the two adjacent teeth are out-of-phase coils. In the windings of the same phase, the winding directions of the coils (14) on the two adjacent teeth (12) are opposite.

2. The DC asynchronous motor as described in claim 1, characterized in that, Each phase of the two-phase winding has an independent input and output line, and the independent power supply output by the control circuit is connected to the input and output lines of one phase of the winding.

3. The DC asynchronous motor as described in claim 1, characterized in that, The stator (10) also includes a yoke (11); each of the teeth (12) is fixedly connected to the surface of the yoke (11); each of the teeth (12) extends radially along the yoke (11).

4. The DC asynchronous motor as described in claim 3, characterized in that, Each of the teeth (12) has a boot (13) at its end, and the end of the boot (13) facing the rotor (20) has an arc surface, the axis of which coincides with the rotation center of the rotor.

5. The DC asynchronous motor as described in claim 4, characterized in that, The rotor (20) includes an iron core (21), multiple conductors (22) and two conductive rings (23); multiple conductor slots (221) are evenly provided on the iron core (21) along the circumferential direction, each conductor slot (221) is opened along the axial direction of the iron core (21), and each conductor (22) passes through the conductor slot (221); the conductive rings (23) are disposed on both sides of the iron core (21), and the conductive rings (23) are fixedly connected to both ends of each conductor (22).

6. The DC asynchronous motor as described in claim 5, characterized in that, The rotor (20) has a squirrel cage structure, and the conductor (22) passes through the iron core (21) and is electrically connected to the conductive rings (23) on both sides.

7. The DC asynchronous motor as described in claim 6, characterized in that, The conductor (22) is inclined relative to the axis of the iron core (21), and the angle between the extension direction of the conductor (22) and the end face of the conductive ring (23) is an acute angle.

8. The DC asynchronous motor as described in claim 7, characterized in that, The conductive ring (23) is a distributed conductive ring (23) structure. The distributed conductive ring (23) includes multiple arc segments. The arc of each arc segment is equal, and every two opposite arc segments are connected to the same number of conductors (22). The distributed conductive rings (23) on at least one side of the iron core (21) are spliced ​​together to form mutually spaced circular rings. Alternatively, the conductive ring (23) is an integral ring structure, and the conductive ring (23) is fixedly connected to both sides of each iron core (21).

9. The DC asynchronous motor as described in claim 7, characterized in that, The DC asynchronous motor is an internal rotor (20) motor; the teeth (12) are provided on the inner wall of the yoke (11) and extend inward; the teeth (12) surround and form the stator inner cavity (15), the rotor (20) is rotatably disposed in the stator inner cavity (15), and an air gap is left between the outer peripheral surface of the rotor (20) and the shoe (13); the center of the rotor (20) is provided with a motor shaft (30), and the motor shaft (30) is fixedly connected to the iron core (21); Alternatively, the DC asynchronous motor is an external rotor (20) motor; the rotor (20) has a rotor cavity, and the stator (10) passes through the rotor cavity; the tooth (12) is located on the outer wall of the yoke (11) and extends outward, and there is an air gap between the outer surface of the boot (13) and the inner wall of the rotor cavity; the center of the stator (10) is connected to a support shaft (31) through a bearing (32).

10. The DC asynchronous motor as described in claim 1, characterized in that, The control circuit includes: The main circuit is used to generate two sets of pulse width modulation signals; Two pre-drive circuits, connected to the main circuit, are used to receive two sets of pulse width modulation signals and output two corresponding sets of power drive signals; Two inverter circuits are provided, with the power supply terminals of the two inverter circuits being connected to a DC power supply, the output terminals of the two inverter circuits being connected to the two stator windings in a one-to-one correspondence, and the controlled terminals of the two inverter circuits being connected to the signal output terminals of the two pre-drive circuits in a one-to-one correspondence. The two inverter circuits are used to convert the input DC power supply into two independent alternating voltages according to the two sets of power drive signals, each alternating voltage being used to drive a stator winding.

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