An induction motor
By adopting a solid metal rotor design with a two-phase four-wire stator drive, the high cost and eddy current loss problems of motors without permanent magnets are solved, achieving cost reduction and energy efficiency improvement.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- SHANGHAI SHENGGE NEW POWER TECHNOLOGY CO LTD
- Filing Date
- 2025-04-12
- Publication Date
- 2026-06-19
AI Technical Summary
In existing permanent magnet-free motor designs, material costs and eddy current losses are high, leading to problems with low manufacturing costs and energy efficiency.
It adopts a two-phase four-wire stator to drive an integrally formed metal rotor. The rotor has a solid structure to avoid slotted or hollowed-out designs. It is combined with a specific drive waveform to reduce eddy current losses and uses materials such as copper, brass, and pure aluminum to reduce costs.
It effectively reduces the material and manufacturing costs of motors, improves energy efficiency under high temperature and high speed conditions, and reduces eddy current losses and heat loss.
Smart Images
Figure CN224385158U_ABST
Abstract
Description
Technical Field
[0001] This utility model relates to the field of motors, and more particularly to an induction motor. Background Technology
[0002] Motors without permanent magnets primarily operate based on the principle of electromagnetic induction. They typically consist of a stator and a rotor. The stator is the stationary part, composed of a core of stacked silicon steel sheets and coils wound around it. When energized, these coils generate a magnetic field. The rotor is the rotating part, usually composed of a squirrel-cage design or windings made of conductive material. When the stator windings are energized, a magnetic field is generated around the stator according to the right-hand rule. Under the influence of the stator's magnetic field, an electromotive force is induced in the rotor conductors according to Faraday's law of electromagnetic induction. When the rotor conductors cut through the stator's magnetic field, an induced current is generated in the rotor conductors. According to the left-hand rule, this induced current experiences a force in the magnetic field, which generates torque, driving the rotor to rotate. The maximum torque is generated when the direction of the induced current in the rotor conductors is perpendicular to the direction of the stator's magnetic field. The motor drive adjusts the energizing phase sequence of the stator coils according to the rotor's position information, ensuring continuous rotor rotation.
[0003] Two-phase four-wire windings are commonly used in synchronous stepper motors. These motors generate a magnetic field through two sets of windings (each with two terminals) on the stator, which interacts with permanent magnets on the rotor to achieve precise stepping motion. Utility Model Content
[0004] The induction motor described in this utility model includes:
[0005] A stator, the stator comprising two or more poles and a plurality of stator windings corresponding to the poles;
[0006] The rotor is coaxially arranged with the stator, and is configured to face the stator winding and rotate along the coaxial axis, thereby undergoing relative displacement with the stator winding;
[0007] The rotor is manufactured using a one-piece molding process, resulting in a solid structure with a smooth surface and no slots or hollows.
[0008] Furthermore, the rotor is cylindrical and surrounds the stator, with the output shaft connected to the side of the rotor facing away from the stator.
[0009] Furthermore, the rotor is rod-shaped and is surrounded by the stator.
[0010] Furthermore, the rotor is disc-shaped, and the stator is disposed on one side of the rotor, with the other side connected to the output shaft.
[0011] Furthermore, the induction motor includes a first stator and a second stator, the rotor is disc-shaped, the first stator and the second stator are disposed on both sides of the rotor, and the output shaft of the rotor passes through the first stator and the second stator.
[0012] Furthermore, the induction motor includes a first rotor and a second rotor, both of which are disc-shaped. The first rotor and the second rotor are disposed on both sides of the stator, and the first rotor and the second rotor are respectively provided with output shafts facing away from the stator.
[0013] Furthermore, the stator winding adopts a two-phase four-wire configuration. In the four wire ends after the opposite windings are reversed and connected, any two adjacent wire ends are connected to form three wire ends with the remaining two wire ends.
[0014] Furthermore, the three wire ends are connected to a three-phase full-bridge drive.
[0015] Furthermore, the section where the wire ends are pinched together is called the third phase. The third phase is connected to half of the constant DC voltage of the other two phases, and the other two phases are driven at a 90-degree offset.
[0016] Furthermore, the third phase is connected to a separate half-bridge drive, and the duty cycle of this half-bridge waveform is 50%.
[0017] Furthermore, the stator frame and rotor are made of one or a combination of copper, brass, pure aluminum, aluminum alloy 6061, aluminum alloy 7075, No. 45 steel, A3 steel, electrical pure iron, and martensitic stainless steel.
[0018] To further reduce manufacturing costs by eliminating the use of permanent magnets, this invention employs a two-phase four-wire stator to drive an integrally formed metal rotor, thereby significantly reducing the material and manufacturing costs of the motor and making it suitable for various applications such as high temperature and high speed.
[0019] The following will further explain the concept, specific structure and technical effects of this utility model in conjunction with the accompanying drawings, so as to fully understand the purpose, features and effects of this utility model. Attached Figure Description
[0020] Figure 1 This is a schematic diagram of the inner stator and cylindrical outer rotor of a preferred embodiment of the present invention;
[0021] Figure 2 This is a schematic diagram of the outer stator and the roller-shaped inner rotor of a preferred embodiment of the present invention;
[0022] Figure 3 This is a schematic diagram of a single stator and single rotor disc motor according to a preferred embodiment of the present invention;
[0023] Figure 4 This is a schematic diagram of a disc motor with a dual stator and a single rotor, representing a preferred embodiment of the present invention. Detailed Implementation
[0024] The preferred embodiments of this utility model are described below with reference to the accompanying drawings to make the technical content clearer and easier to understand. This utility model can be embodied in many different forms, and the scope of protection of this utility model is not limited to the embodiments mentioned herein.
[0025] In the accompanying drawings, components with the same structure are indicated by the same numerical designation, and components with similar structures or functions are indicated by similar numerical designations. The dimensions and thicknesses of each component shown in the drawings are arbitrary, and this invention does not limit the dimensions and thicknesses of each component. To make the illustrations clearer, the thickness of some components has been appropriately exaggerated in the drawings.
[0026] Example 1
[0027] This embodiment describes an induction motor, which includes a stator and a rotor, with the stator inside and the rotor outside, as shown below. Figure 1 As shown, the stator winding adopts a two-phase four-wire configuration, namely, four wires A, B, C, and D, and eight wire ends A1, A2, B1, B2, C1, C2, D1, and D2. Among them, A2 and D2 are connected, and B2 and C2 are connected to form two independent wires A1A2D2D1 and B1B2C2C1. Then, A1 and B1 of the remaining four wire ends A1, B1, C1, and D1 are connected or C1 and D1 are pinched together to form one wire end (one phase), and the other two wire ends (two phases).
[0028] The drive employs one of three methods. The first method uses a three-phase full-bridge drive with three wires connected to a three-phase AC power supply. It includes six power switches, with two switches connected to each phase. The on / off state of the six power switches is controlled by a PWM waveform to control the phase current, thereby controlling the rotational speed and torque of the outer rotor. The second method uses four-phase control, with each pair of phases differing by 90 degrees. The third phase is actually the reverse of the first phase, and the fourth phase is the reverse of the second phase. Therefore, it can be reduced to two-phase control. The phase with the wires pinched together is called the third phase. The third phase is connected to half of the constant DC voltage of the other two phases, and the other two phases are driven at a 90-degree offset to achieve the rotating magnetic field. The third method connects the third phase to a separate half-bridge drive. The duty cycle of this half-bridge waveform is 50%, and the rest is the same as the second method.
[0029] The stator windings described in this embodiment can also be stacked with more levels, such as a three-level six-winding system.
[0030] In the radial flux design, the rotor described in this embodiment adopts a cylindrical structure, such as... Figure 1 As shown, the cylindrical wall is coaxial with the stator, the stator is installed inside the cylindrical rotor, and the bottom of the cylindrical rotor is connected to the output shaft on the side opposite to the stator. This output shaft is also coaxial with the stator.
[0031] In this embodiment, the stator (excluding the frame portion after winding) and the cylindrical rotor are integrally formed by machining methods such as cutting, casting or forging. The surface is smooth, without grooves or hollows, and it is a solid structure.
[0032] The stator (excluding the frame part after winding) and solid rotor described in this embodiment are made of copper or brass, pure aluminum, aluminum alloy 6061, aluminum alloy 7075, No. 45 steel, A3 steel, electrical pure iron, martensitic stainless steel, etc.
[0033] In this embodiment, the stator and solid rotor are combined. When alternating current is applied to the two-phase four-wire winding stator, an alternating magnetic field is generated in the stator core. Due to the spatial distribution and current phase difference of the two-phase windings, these magnetic fields combine to form a rotating magnetic field. Under the action of the rotating magnetic field, the conductive material inside the solid metal rotor cuts the magnetic lines of force. According to Faraday's law of electromagnetic induction, an electromotive force is induced in the conductor when it cuts the magnetic lines of force. The induced electromotive force forms eddy currents, i.e., induced currents, in the solid metal rotor. These currents flow inside the solid rotor and are subjected to the Lorentz force in the magnetic field. The magnetic field generated by the induced current interacts with the rotating magnetic field of the stator to form an electromagnetic torque, which drives the solid rotor to rotate. In the input waveform of the stator described in this embodiment, excluding the phase with the pinched wire, one phase provides the stator peak current but its rate of change is zero, and the other phase provides the excitation current, whose stator portion has zero amplitude but the largest rate of change. Therefore, the induced current in the solid rotor described in this embodiment is not only concentrated on the material surface, but also coupled into the interior of the solid rotor. As a result, the overall resistance is small and the eddy current loss is not large.
[0034] Eddy currents exist in all electrical devices that utilize the principle of electromagnetic induction. The presence of eddy currents primarily affects the utilization rate of electrical energy in AC circuits. This is because eddy currents generate Joule heat, and the amount of heat generated is proportional to the square of the current. The more heat generated by eddy currents, the more electrical energy is wasted, and the lower the efficiency of the conversion between electrical and mechanical energy. Therefore, in traditional induction motor designs, the rotor core is typically made of stacked silicon steel sheets, and the rotor core has several slots in which rotor windings are installed. The purpose of this design is to minimize the generation of eddy currents, thereby reducing heat loss caused by them.
[0035] Unlike the traditional induction motor design described above, this embodiment employs a solid rotor design. Since the driving waveform of the induction motor significantly affects the spatial distribution of the fundamental and harmonic eddy currents within the solid rotor, when the driving waveform is an ideal sine wave, the fundamental magnetic field exhibits a sinusoidal spatial distribution. The fundamental eddy currents induced by the fundamental magnetic field in the solid rotor are mainly concentrated on the rotor surface, and their distribution is closely related to the spatial distribution of the fundamental magnetic field; typically, the eddy current density is higher in areas of higher magnetic field strength. If the driving waveform is not an ideal sine wave but a non-sinusoidal waveform containing harmonic components, the distribution of the fundamental magnetic field will be disturbed. These harmonic components will induce additional eddy currents in the solid rotor, thereby altering the spatial distribution of the fundamental eddy currents.
[0036] Harmonic components in the drive waveform generate harmonic magnetic fields between the stator and the solid rotor. The spatial distribution of harmonic magnetic fields varies depending on their order. For example, the induced eddy current distribution in the solid rotor by the 5th and 7th harmonic magnetic fields differs from that of the fundamental wave. Generally, the spatial distribution of higher-order harmonic magnetic fields is more complex, inducing eddy currents of varying intensities at different locations on the solid rotor.
[0037] The spatial distribution of harmonic eddy currents in a solid rotor depends on the wavelength of the harmonic magnetic field and the geometry of the solid rotor. For certain specific harmonic orders, the wavelength may match the dimensions of the solid rotor, resulting in strong localized eddy current concentrations at certain locations within the rotor (deeper interior, not the surface). These locally concentrated eddy currents can cause localized overheating of the solid rotor. However, since this embodiment uses a solid rotor, although the localized eddy currents are relatively large, the overall resistance of the solid rotor is very low, thus significantly reducing the heat generated by the eddy currents.
[0038] Example 2
[0039] The induction motor described in this embodiment includes a stator and a rotor, with the stator on the outside and the rotor on the inside, as shown below. Figure 2 As shown, the stator winding configuration is the same as in Embodiment 1. The rotor adopts a rod-shaped structure, a standard solid cylinder with a smooth surface, no slots, and no hollow sections. It is a solid structure, and the cylindrical rotor is coaxial with the outer stator, allowing for direct output. The remaining parts of the induction motor described in this embodiment are the same as in Embodiment 1.
[0040] Example 3
[0041] In axial flux design, such as Figure 3 As shown, the rotor in this embodiment adopts a solid disc structure. The solid disc rotor is coaxial with the stator, one side of the solid disc rotor is in contact with the stator, leaving an air gap in the middle, and the other side is connected to the output shaft. The rest of the induction motor in this embodiment is the same as in Embodiment 1.
[0042] Example 4
[0043] In axial flux design, such as Figure 4 As shown, the rotor in this embodiment adopts a solid disc structure. The solid disc rotor is coaxial with the two stators, and the two sides of the disc rotor are respectively attached to the two stators, with an air gap in the middle. The middle part of the two stators is left empty. The middle disc rotor is connected to the output shaft, outputting mechanical rotation to one or both sides. The rest of the induction motor in this embodiment is the same as in Embodiment 1.
[0044] Example 5
[0045] In the axial flux design (not shown in the attached figures), as a variant of Embodiment 4, this embodiment employs a configuration of a single stator fitted with dual-sided disc-shaped rotors. The single stator has a disc-shaped frame with windings arranged on both sides, or the same winding penetrating the frame of the stator. The dual-sided disc-shaped rotors are fitted with the stator frame and windings respectively, outputting mechanical rotation to both sides.
[0046] The preferred embodiments of this utility model have been described in detail above. It should be understood that those skilled in the art can make numerous modifications and variations based on the concept of this utility model without creative effort. Therefore, all technical solutions that can be obtained by those skilled in the art based on the concept of this utility model through logical analysis, reasoning, or limited experimentation on the basis of existing technology should be within the scope of protection defined by the claims.
Claims
1. An induction motor, comprising: A stator, the stator comprising two or more poles and a plurality of stator windings corresponding to the poles; The rotor is coaxially arranged with the stator, and is configured to face the stator winding and rotate along the coaxial axis, thereby undergoing relative displacement with the stator winding; Its characteristic is that the rotor processing technology is integral molding, and it is a solid structure with a smooth surface and no slots or hollows.
2. The induction motor as described in claim 1, characterized in that, The rotor is cylindrical and surrounds the stator. The side of the rotor opposite to the stator is connected to the output shaft.
3. The induction motor as described in claim 1, characterized in that, The rotor is rod-shaped and is surrounded by the stator.
4. The induction motor as described in claim 1, characterized in that, The rotor is disc-shaped, and the stator is located on one side of the rotor, with the other side connected to the output shaft.
5. The induction motor as described in claim 1, characterized in that, The induction motor includes a first stator and a second stator, and the rotor is disc-shaped. The first stator and the second stator are disposed on both sides of the rotor, and the output shaft of the rotor passes through the first stator and the second stator.
6. The induction motor as described in claim 1, characterized in that, The induction motor includes a first rotor and a second rotor, both of which are disc-shaped. The first rotor and the second rotor are disposed on both sides of the stator, and the first rotor and the second rotor are respectively provided with output shafts facing away from the stator.
7. The induction motor as described in claim 1, characterized in that, The stator winding adopts a two-phase four-wire configuration. After the four wire ends of the opposite windings are reversed and connected, any two adjacent wire ends are connected to form three wire ends with the remaining two wire ends.
8. The induction motor as described in claim 7, characterized in that, The three wires are connected to the three-phase full-bridge drive.
9. The induction motor as described in claim 7, characterized in that, The section where the wire ends are pinched together is called the third phase. The third phase is connected to half of the constant DC voltage of the other two phases, and the other two phases are driven at a 90-degree offset.
10. The induction motor as described in claim 9, characterized in that, The third phase is connected to a separate half-bridge drive, and the duty cycle of this half-bridge waveform is 50%.