A concentrated winding stator electrically excited flywheel energy storage motor

Abstract

This invention relates to a concentrated winding stator electrically excited flywheel energy storage motor, comprising: a flywheel rotor and a stator core, armature winding, and excitation winding surrounding the outside of the flywheel rotor. The rotor and shaft may be non-integrated structures, and the magnetic core and rotor may be made of different materials. Open slots exist on both the inner and outer sides of the stator core, with the armature winding and excitation winding respectively placed in the slots on the inner and outer sides of the stator core; upper and lower end covers are respectively disposed on the upper and lower sides of the flywheel rotor; magnetic rings are located above and below the flywheel rotor; and an L-shaped sealing cover is located in the air gap. The motor topology of this invention can improve the heat dissipation coefficient of the excitation winding, not only reducing rotor eddy current losses and motor temperature rise during charging and discharging, but also reducing bearing load and losses. Furthermore, the overall motor structure is robust, durable, simple, reliable, has low standby loss, and is cost-effective.

Description

Technical Field

[0001] This invention relates to the field of motor design technology, and more specifically, to a concentrated winding stator electrically excited flywheel energy storage motor. Background Technology

[0002] With the economical and sustainable development of energy, flywheel energy storage technology has gradually become a research hotspot due to its advantages such as environmental friendliness, short charging and discharging time, long lifespan, and high energy density.

[0003] Flywheel energy storage technology converts electrical energy into the mechanical energy of a rotating object and then stores this energy. In the energy storage phase, the system drives a motor to a certain speed via a power electronic converter, causing a flywheel integrated with the motor rotor to rotate at high speed. The flywheel, with its large inertia, can store the mechanical energy generated by inertia at high speeds, thus achieving the conversion of electrical energy into mechanical energy. In the energy holding phase, the entire system maintains the rotational speed of the motor rotor and flywheel, with almost no energy exchange with the outside world. In the energy release phase, the flywheel energy storage motor operates as a generator. The flywheel drives the magnetic field on the motor rotor to cut the AC windings of the motor to generate electricity. As the rotational speed of the flywheel integrated with the motor rotor gradually decreases, the mechanical energy on the flywheel is converted into electrical energy through electromagnetic induction in the motor, and then released to the outside world as stable electrical energy through the power electronic conversion system.

[0004] The flywheel energy storage motor is the core component of the system's energy conversion, and its performance directly affects the performance of the entire flywheel energy storage system. The motor portion of a flywheel energy storage motor typically employs a permanent magnet synchronous motor, an electrically excited synchronous motor, or an inductor motor. Since flywheel energy storage motors usually operate at high speeds, the motor rotor requires high mechanical strength and high reliability. The inductor motor rotor is a solid structure with slotted teeth on its surface, forged from high-strength alloy steel. The rotor has no permanent magnets, windings, or any other additional components. During operation, it utilizes the difference in air gap magnetic reluctance between the teeth and slots of the inductor (the slotted rotor). As the inductor rotates, the air gap magnetic reluctance between the rotor surface and the stator magnetic field changes periodically. According to the principle of minimum magnetic reluctance, magnetic lines of force tend to pass through the path of least magnetic reluctance, i.e., the rotor teeth, thus inducing magnetic poles in the rotor teeth and generating an induced electromotive force in the stator armature winding. The magnetic field on the rotor is generated by a magnetic source on the stator through a designed magnetic circuit. The magnetic source on the stator is typically the excitation winding or a permanent magnet. The exceptionally simple and reliable structure of the induction motor rotor makes it ideal for high-energy-density, high-voltage applications. Due to its high structural strength, the induction motor can operate at very high linear speeds, and its own inertial energy storage is usually sufficient to meet load requirements. Therefore, it eliminates the need for external flywheel devices, as is common in current inertial energy storage systems, such as the upper and lower structures of permanent magnet synchronous motor rotors with flywheels; in this case, the induction generator rotor also functions as the flywheel.

[0005] However, the excitation winding of a conventional induction motor is located on the stator side and is circular. During motor operation, the heat generated by DC copper losses is difficult to dissipate, resulting in a high temperature rise in the excitation winding. Furthermore, flywheel energy storage motors often use permanent magnets to suspend the flywheel rotor. The permanent magnet magnetic field generates iron losses in the motor, which continuously consume the energy stored in the flywheel. The higher the rotor speed, the greater the losses, reducing the overall energy conversion efficiency of the flywheel energy storage system. Improving the energy utilization rate of flywheel energy storage and reducing the temperature rise of various components of the induction motor are urgent problems to be solved.

[0006] In the prior art, in a stator hybrid excitation flywheel energy storage motor disclosed in Chinese patent CN112398269A, through magnetic circuit innovation, the magnetic field generated by the permanent magnet ring is mainly used to provide an axial upward electromagnetic force to the flywheel rotor during energy storage, resulting in low bearing load and losses. During charging and discharging, the excitation winding and the permanent magnet ring are hybridly excited. Through the cooperation of the excitation winding, the electromagnetic force on the flywheel rotor remains constant, also achieving the effect of unloading the bearings. However, because the upper and lower end covers are made of ferromagnetic materials, the magnetic circuits of the excitation winding and the permanent magnet ring are coupled. If the current of the excitation winding is unstable, the levitation force of the flywheel rotor will also be unstable. In addition, during standby operation, the permanent magnet magnetic field will generate iron losses in the motor, which will continuously consume the energy stored in the flywheel, thereby reducing the overall energy conversion efficiency of the flywheel energy storage system.

[0007] In the prior art, the stator electrically excited flywheel energy storage motor disclosed in Chinese patent CN113300532A achieves the effect of reducing bearing load through the cooperation of permanent magnet unloading bearing and induction motor. Furthermore, through magnetic circuit innovation and the use of non-ferromagnetic materials for the upper and lower end covers, the magnetic coupling between the permanent magnet unloading bearing and the motor is very small, and changes in the motor's excitation current do not affect the rotor's levitation force. During motor operation, the load fluctuation at the bearing is small, resulting in high stability and significantly extending the bearing's service life. However, during motor charging and discharging, the excitation winding generates significant DC copper losses, and the circular winding is not easy to dissipate heat, leading to high temperature rise in various motor components. In addition, during standby operation, the permanent magnet magnetic field generates iron losses in the motor, which continuously consumes the energy stored in the flywheel, thereby reducing the overall energy conversion efficiency of the flywheel energy storage system. Summary of the Invention

[0008] In response to the shortcomings and improvement needs of existing technologies, this invention provides a centralized winding stator electrically excited flywheel energy storage motor, which not only reduces the temperature rise of various components of the flywheel energy storage motor and reduces the self-discharge rate of the flywheel energy storage motor, but also improves the economy and safety of the flywheel energy storage system.

[0009] To achieve the above objectives, according to a first aspect of the present invention, a concentrated winding stator stator electrically excited flywheel energy storage motor is provided, comprising a flywheel rotor, wherein the flywheel rotor is vertically mounted and comprises a rotating shaft, an upper magnetic core, a lower magnetic core and a rotor core, wherein the upper magnetic core and the lower magnetic core are disposed on the rotating shaft and the rotor core is disposed between the two.

[0010] Surrounding the outside of the flywheel rotor are a stator core, an electromagnetic winding, and an excitation winding. The stator core has open slots on both its inner and outer sides for placing the electromagnetic winding and the excitation winding, respectively.

[0011] The upper and lower end covers are respectively located on both sides of the flywheel rotor, and the upper magnetic ring and the lower magnetic ring are respectively installed on the upper and lower end covers;

[0012] One end of the L-shaped sealing cover is embedded in the groove of the upper end cover for sealing, and the other end is fixed to the lower end cover for sealing. The upper and lower ends are reinforced by pins.

[0013] Bearing seats are provided on the upper and lower end covers, and mechanical bearing units are provided inside the bearing seats for connecting the bearing seats and the rotating shaft.

[0014] Furthermore, the bearing housing is made of a non-ferromagnetic material.

[0015] Furthermore, the flywheel energy storage motor also includes a housing, which is fixed between the upper end cover and the lower end cover and surrounds the outside of the stator core.

[0016] Furthermore, the outer side of the rotor core is provided with Np tooth slots, where N is an integer greater than or equal to 1 and p is the number of rotor pole pairs.

[0017] Furthermore, an air gap is formed between the lower surface of the upper magnetic ring and the upper surface of the upper magnetic core, and an air gap is formed between the upper surface of the lower magnetic ring and the upper surface of the lower magnetic core.

[0018] Furthermore, the electromagnetic winding is a single-winding structure that runs through the stator core.

[0019] Furthermore, the rotating shaft and rotor core can be an integral structure or can be made of different materials, and the rotor core and the upper or lower magnetic core can be made of different materials.

[0020] Furthermore, the rotating shaft, upper magnetic core, lower magnetic core, rotor core, upper end cover, lower end cover, housing, upper magnetic ring, and lower magnetic ring are all made of ferromagnetic material.

[0021] Furthermore, the excitation winding carries DC excitation current during charging and discharging, and stops DC excitation during energy storage holding.

[0022] In summary, the above-described technical solutions conceived in this invention can achieve the following beneficial effects:

[0023] (1) The concentrated winding stator electric excitation flywheel energy storage motor proposed in this invention places the excitation winding in the toothed structure outside the stator core, thereby enhancing the heat dissipation coefficient of the excitation winding and reducing the temperature rise of each component of the motor. On the other hand, the non-integrated structure of the flywheel and rotor core in the rotating component allows the rotor core to be made of silicon steel sheet material, which can effectively reduce the eddy current loss of the rotor and thus reduce the temperature rise of the rotor.

[0024] (2) The present invention innovates the magnetic circuit and uses ferromagnetic materials for the upper and lower end covers so that the levitation force generated by the excitation current can offset the gravity of the flywheel rotor. Moreover, the self-discharge rate of the flywheel energy storage system is extremely low after the excitation current is cut off during the standby operation phase, which can effectively improve the overall energy conversion efficiency of the flywheel energy storage system.

[0025] (3) By using a sealing cover to seal the excitation winding and electromagnetic winding, the present invention can eliminate the need for potting with epoxy resin materials, thereby effectively reducing the cost of motor manufacturing.

[0026] (4) The upper and lower end covers of the present invention have enhanced rigidity by using ferromagnetic materials, which can effectively reduce mechanical vibration during motor operation.

[0027] In summary, the electrically excited flywheel energy storage motor of the present invention can solve the problems of motor temperature rise caused by low excitation winding heat dissipation coefficient and high rotor eddy current loss, high self-discharge rate caused by permanent magnet levitation flywheel rotor, and high manufacturing cost caused by winding potting. It can improve the stability and safety of flywheel energy storage system during use and reduce the cost of flywheel energy storage system. Attached Figure Description

[0028] Figure 1 This is a cross-sectional schematic diagram of a concentrated winding stator electrically excited flywheel energy storage motor according to an embodiment of the present invention;

[0029] Figure 2 This is a schematic diagram of a flywheel rotor structure according to an embodiment of the present invention;

[0030] Figure 3 This is a schematic diagram of the rotor core structure in an embodiment of the present invention;

[0031] Figure 4 This is a schematic diagram of the magnetic core structure in an embodiment of the present invention;

[0032] Figure 5 This is a schematic diagram of the rotating shaft structure in an embodiment of the present invention;

[0033] Figure 6This is a schematic diagram of the stator core, excitation winding, and electromagnetic winding structure in an embodiment of the present invention;

[0034] Figure 7 This is a schematic diagram of the stator core structure in an embodiment of the present invention;

[0035] Figure 8 This is a schematic diagram of the sealing cover structure in an embodiment of the present invention;

[0036] Figure 9 The main flux path diagram provided in the embodiments of the present invention;

[0037] Figure 10 This is a cross-sectional schematic diagram of another type of concentrated winding stator electrically excited flywheel energy storage motor according to the present invention;

[0038] Figure 11 This is a schematic diagram of the integrated rotor core and shaft structure of the present invention;

[0039] Figure 12 This is a flux path diagram of another type of concentrated winding stator electrically excited flywheel energy storage motor according to the present invention.

[0040] In all the accompanying drawings, the same reference numerals are used to denote the same elements or structures, wherein:

[0041] 1-Shaft, 201-Upper magnetic core, 202-Lower magnetic core, 3-Rotor core, 4-Stator core, 401-Inner slot, 402-Outer slot, 5-Electromagnetic winding, 6-Excitation winding, 701-Upper end cover, 702-Lower end cover, 8-Housing, 901-Upper magnetic ring, 902-Lower magnetic ring, 10-L-shaped sealing cover, 11-Pin, 12-Mechanical bearing, 13-Bearing seat, 14-First magnetic flux path, 15-Second magnetic flux path, 16-Third magnetic flux path, 17-Fourth magnetic flux path. Detailed Implementation

[0042] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention. Furthermore, the technical features involved in the various embodiments of this invention described below can be combined with each other as long as they do not conflict with each other.

[0043] like Figure 1 As shown, and in combination Figures 2-8The flywheel energy storage motor in this embodiment will be described in detail. The electrically excited flywheel energy storage motor of the present invention mainly includes: a rotating shaft 1, an upper magnetic core 201, a lower magnetic core 202, a rotor core 3, a stator core 4, an electromagnetic winding 5, an excitation winding 6, an upper end cover 701, a lower end cover 702, a housing 8, an upper magnetic ring 901, a lower magnetic ring 902, an L-shaped sealing cover 10, a pin 11, a mechanical bearing 12, and a bearing seat 13.

[0044] Specifically, the outer side of the rotor core 3 is provided with Np slots, where N is an integer greater than or equal to 1 and p is the number of rotor pole pairs. The slots are in the shape of an arc, trapezoid, rectangle or function curve.

[0045] Specifically, the lower surface of the upper magnetic ring 901 forms an air gap with the upper surface of the upper magnetic core 201, and the upper surface of the lower magnetic ring 902 forms an air gap with the upper surface of the lower magnetic core 202.

[0046] Specifically, the electromagnetic winding 5 is a single winding structure that runs through the stator core 4.

[0047] Specifically, the rotating shaft 1 and the rotor core 3 may be non-integrated structures.

[0048] Specifically, the rotating shaft 1, the upper magnetic core 201, the lower magnetic core 202, the rotor core 3, the upper end cover 701, the lower end cover 702, and the housing 8 are all made of ferromagnetic materials.

[0049] In this embodiment, the excitation winding 6 is wound on the teeth on the outside of the stator core 4, which can effectively increase the heat dissipation coefficient of the excitation winding 6, thereby reducing the temperature rise of various components of the motor.

[0050] In this embodiment, during charging and discharging, the first magnetic flux path 14 and the second magnetic flux path 15 of the motor, as follows: Figure 9 As shown, the first magnetic flux path 14 is: flywheel → rotor core → main air gap → stator → housing → upper end cover → upper magnetic ring → axial air gap → upper magnetic core → flywheel. The magnetic flux acts on the upper surface of the upper magnetic core, providing an upward axial electromagnetic force to the flywheel rotor, partially or completely offsetting the weight of the flywheel rotor core, thereby reducing the load on the mechanical bearing unit. When the excitation winding is not energized, there is no magnetic flux in the stator core, flywheel, and magnetic ring; therefore, the motor has no no-load standby loss, thus improving the motor's energy conversion efficiency.

[0051] In this embodiment, the excitation winding 6 and electromagnetic winding 5 on the stator core 4 are sealed by an L-shaped sealing cover 10 instead of using potting, which can effectively reduce the cost of motor manufacturing.

[0052] Understandably, in this embodiment, the motor experiences no electromagnetic losses during energy storage standby, resulting in a high energy conversion rate. The flywheel rotor experiences stable levitation force throughout the entire charging and discharging process, reducing bearing load and losses and extending bearing life. The excitation winding has a high heat dissipation coefficient, and the rotor core poles are made of silicon steel sheets, effectively reducing the temperature rise of various motor components. The flywheel is constructed of alloy steel, resulting in a simple, compact, and low-cost overall motor structure. It also exhibits good rotor dynamics characteristics and is easy to manufacture, making it highly suitable for flywheel energy storage applications.

[0053] Example 2: Based on the concentrated winding stator electrically excited flywheel energy storage motor of Example 1, the present invention will be further explained and described below.

[0054] A concentrated winding stator electrically excited flywheel energy storage motor, comprising:

[0055] The vertically mounted flywheel rotor includes a shaft 1, an upper magnetic core 201, a lower magnetic core 202, and a rotor core 3. The shaft 1 is provided with the upper magnetic core 201 and the lower magnetic core 202, and the rotor core 3 is provided between the upper magnetic core 201 and the lower magnetic core 202.

[0056] The stator core 4, electromagnetic winding 5, and excitation winding 6 are arranged around the outside of the flywheel rotor. There are slots on both the inner and outer sides of the stator core 4. The electromagnetic winding 5 is placed in the slot on the inner side of the stator core 4, and the excitation winding 6 is placed in the slot on the outer side of the stator core 4.

[0057] In this embodiment, the stator core 4 includes an outer opening slot 402 and an inner opening slot 401, and the number of inner opening slots 401 is greater than the number of outer opening slots 402.

[0058] The upper end cover 701 and the lower end cover 702 are respectively installed on the upper and lower sides of the flywheel rotor;

[0059] The magnetic ring includes an upper magnetic ring 901 and a lower magnetic ring 902, which are respectively mounted on the upper end cover 701 and the lower end cover 702.

[0060] L-shaped sealing cover 10, one end of which is embedded in the groove inside the boss of the upper end cover 701 for sealing, and the other end is fixed to the inside of the boss of the lower end cover 702 for sealing. Both the upper and lower ends of the L-shaped sealing cover 10 are reinforced with pins 11.

[0061] Mechanical bearing unit 12 is used to connect bearing housing 13 and flywheel rotor shaft 1, wherein bearing housing 13 is made of non-ferromagnetic material.

[0062] In this embodiment, a housing 8 is also included, which is fixed between the upper end cover 701 and the lower end cover 702 and surrounds the outside of the stator core 4.

[0063] In this embodiment, the outer side of the rotor core 3 is provided with Np tooth slots, where N is an integer greater than or equal to 1 and p is the number of rotor pole pairs.

[0064] In this embodiment, an air gap is formed between the lower surface of the upper magnetic ring 901 and the upper surface of the upper magnetic core 201, and an air gap is formed between the upper surface of the lower magnetic ring 902 and the upper surface of the lower magnetic core 202.

[0065] In this embodiment, the electromagnetic winding 5 is a single winding structure that runs through the stator core 4.

[0066] In this embodiment, the rotating shaft 1 and the rotor core 3 may be an integrated structure or may be made of different materials, and the rotor core 3 and the upper magnetic core 201 or the lower magnetic core 202 may be made of different materials.

[0067] In this embodiment, the excitation winding 6 carries DC excitation current during charging and discharging, and stops DC excitation during energy storage and holding.

[0068] In this embodiment, the electrically excited flywheel energy storage motor can solve the problems of motor temperature rise caused by low excitation winding heat dissipation coefficient and high rotor eddy current loss, high self-discharge rate caused by permanent magnet levitation flywheel rotor, and high manufacturing cost caused by winding potting. It can improve the stability and safety of the flywheel energy storage system during use and reduce the cost of the flywheel energy storage system.

[0069] Example 3: As Figure 10 or Figure 11 As shown, the shaft 1, rotor core 3, upper magnetic core 201, and lower magnetic core 202 in the vertically mounted flywheel rotor are integrally formed structures. The upper end cover is composed of the upper end cover 701 and the upper magnetic ring 901 in Example 2, and the lower end cover is composed of the lower end cover 702 and the lower magnetic ring 902 in Example 2. Both form a structure with bosses, which improves the integrity. The lower surface of the boss of the upper end cover forms an air gap with the upper surface of the flywheel rotor, and the boss on the upper surface of the lower end cover forms an air gap with the lower surface of the flywheel rotor.

[0070] During charging and discharging, the motor's third magnetic flux path 16 and fourth magnetic flux path 17, as... Figure 12As shown, the third magnetic flux path 16 is: flywheel → rotor core → main air gap → stator → housing → upper end cover → axial air gap → flywheel. The magnetic flux acts on the upper surface of the flywheel rotor, providing an upward axial electromagnetic force to partially or completely offset the weight of the flywheel rotor, thereby reducing the load on the mechanical bearing unit. Consistent with Embodiment 2, when the excitation winding is not energized, there is no magnetic flux in the stator core, flywheel, and magnetic ring; therefore, the motor has no no-load standby loss, thus improving the motor's energy conversion efficiency.

[0071] Understandably, in Examples 2 and 3, the motor experiences no electromagnetic loss during energy storage standby, resulting in a high energy conversion rate. The flywheel rotor is subjected to a stable levitation force throughout the entire charging and discharging process, reducing bearing load and wear, and extending bearing life. The excitation winding is placed close to the housing, resulting in a high heat dissipation coefficient and effectively reducing the temperature rise of various motor components. The flywheel is constructed of alloy steel, and the overall motor structure is simple, compact, and low-cost. It exhibits good rotor dynamics characteristics, is easy to manufacture, and is highly suitable for flywheel energy storage applications.

[0072] In summary, this invention not only reduces the temperature rise of various components of the flywheel energy storage motor and reduces the self-discharge rate of the flywheel energy storage motor, but also improves the economy and safety of the flywheel energy storage system.

[0073] Those skilled in the art will readily understand that 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 scope of protection of the present invention.

Claims

1. A concentrated winding stator electrically excited flywheel energy storage motor, comprising a flywheel rotor, characterized in that, The flywheel rotor is vertically mounted and includes a rotating shaft (1), an upper magnetic core (201), a lower magnetic core (202), and a rotor core (3). The upper magnetic core (201) and the lower magnetic core (202) are mounted on the rotating shaft (1), and the rotor core (3) is mounted between them. Surrounding the outside of the flywheel rotor are a stator core (4), an electromagnetic winding (5), and an excitation winding (6). The stator core (4) has slots on both the inner and outer sides for placing the electromagnetic winding (5) and the excitation winding (6), respectively. The excitation winding (6) consists of multiple symmetrically distributed U-shaped radial excitation concentrated windings placed in the slots on the outside of the stator core (4). The upper and lower end covers (701, 702) are respectively set on both sides of the flywheel rotor, and the upper magnetic ring (901) and the lower magnetic ring (902) are respectively installed on the upper and lower end covers; One end of the L-shaped sealing cover (10) is embedded in the groove of the upper end cover (701) for sealing, and the other end is fixed to the lower end cover (702) for sealing. The upper and lower ends are reinforced by pins (11). Bearing seats (13) are provided on the upper and lower end covers (701, 702). A mechanical bearing unit is provided inside the bearing seat (13) for connecting the bearing seat (13) and the rotating shaft (1). It also includes a housing (8), which is fixed between the upper end cover (701) and the lower end cover (702) and surrounds the outside of the stator core (4). The lower surface of the upper magnetic ring (901) forms an air gap with the upper surface of the upper magnetic core (201), and the upper surface of the lower magnetic ring (902) forms an air gap with the upper surface of the lower magnetic core (202). The electromagnetic winding (5) is a single winding structure that penetrates the stator core (4).

2. The concentrated winding stator electrically excited flywheel energy storage motor according to claim 1, characterized in that: The bearing housing (13) is made of a non-ferromagnetic material.

3. The concentrated winding stator electrically excited flywheel energy storage motor according to claim 1, characterized in that: The outer side of the rotor core (3) is provided with Np tooth slots, where N is an integer greater than or equal to 1 and p is the number of rotor pole pairs.

4. The concentrated winding stator electrically excited flywheel energy storage motor according to claim 1, characterized in that: The rotating shaft (1) and the rotor core (3) are either an integrated structure or separate structures made of different materials. The rotor core (3), the upper magnetic core (201), or the lower magnetic core (202) are made of different materials.

5. The concentrated winding stator electrically excited flywheel energy storage motor according to claim 1, characterized in that: The rotating shaft (1), upper magnetic core (201), lower magnetic core (202), rotor core (3), upper end cover (701), lower end cover (702), housing (8), upper magnetic ring (901) and lower magnetic ring (902) are all made of ferromagnetic material.

6. The concentrated winding stator electrically excited flywheel energy storage motor according to claim 1, characterized in that: The excitation winding (6) carries DC excitation current during charging and discharging, and stops DC excitation during energy storage.

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