New energy electric vehicle pure electric power system mode conversion system

Abstract

The application provides a new energy electric vehicle pure electric power system mode conversion system, and belongs to the technical field of electric vehicle power systems. A self-starting permanent magnet synchronous motor is used as a front wheel driving main drive motor, an auxiliary drive motor is used as a rear drive motor, an inverter connected with the main drive motor and the auxiliary drive motor, a DC-AC inverter connected with the stator winding of a double-stator disc type flywheel energy storage mechanism, a DC-DC inverter connected with a storage battery, and a clutch for connecting the main drive motor and the auxiliary drive motor. The double-stator disc type flywheel energy storage structure combines the flywheel and the motor structure, improves the power density of the flywheel energy storage, fully utilizes the characteristics of the flywheel energy storage fast charging and discharging, can effectively reduce the influence of the power system impact current on the battery health state, can reduce the electric energy dissipation caused by the instantaneous high-power electromechanical energy conversion, improves the efficiency of the power system, can provide the flywheel energy storage as the standby energy of the power system, and improves the automobile driving mileage.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of electric vehicle power systems, in particular to a new energy electric vehicle pure electric power system mode conversion system. BACKGROUND

[0002] Nowadays, new energy electric vehicle technology is developing rapidly, and the industry market has realized double growth in production and sales. However, the range anxiety problem when using electric vehicles still troubles users. When running in actual application situations, there are many factors that affect the driving range of new energy electric vehicles, but there are two main factors, one is the quality of the battery, and the other is the efficiency of the two-electric system. Passenger cars usually face the working state of frequent start-stop during driving, and the charging process of the battery is slow, and the electric vehicle starts and stops with several times the rated current of electromechanical energy exchange, so this process often threatens the health status of the motor and produces a lot of loss. SUMMARY

[0003] The present application aims to provide a new energy electric vehicle pure electric power system mode conversion system to solve at least one of the technical problems in the background art.

[0004] In order to achieve the above-mentioned purpose, the present application adopts the following technical scheme:

[0005] The present application provides a new energy electric vehicle pure electric power system mode conversion system, comprising: a self-starting permanent magnet synchronous motor as a rear wheel drive main drive motor, an auxiliary drive motor as a front drive motor, a converter connected to the main drive motor and the auxiliary drive motor, respectively, a third converter and a fourth converter connected to the stator winding of the double-stator disc flywheel energy storage mechanism, a first converter and a second converter connected to the battery, and a clutch connecting the main drive motor and the auxiliary drive motor.

[0006] Optionally, the double-stator disc flywheel energy storage mechanism comprises: a flywheel arranged in the housing, the flywheel being arranged on a rotating shaft, a tooth groove being arranged on the flywheel, and a flywheel tooth being arranged in the tooth groove; the two sides of the flywheel are stator back irons, winding grooves being arranged on the stator back irons; a sealing layer is arranged between the flywheel and the stator back irons.

[0007] Optionally, the stator teeth are mounted on the rotor back iron, and the stator winding is wound on the stator teeth; the stator back iron is mounted with a non-magnetic compensation pad.

[0008] Optionally, the main drive motor and the auxiliary drive motor are connected to the battery through the first converter and the second converter, respectively.

[0009] Optionally, the stator winding of the first stator of the double-stator disc flywheel energy storage mechanism is connected in parallel with the battery on the charging circuit through the fourth converter, and the stator winding of the second stator of the double-stator disc flywheel energy storage mechanism is connected with the power supply circuit of the main drive motor through the third converter.

[0010] Optionally, the sealing layer is composed of two sealing layers combined in the axial direction; on the side close to the flywheel in the axial direction, the gap between the stator teeth and the gap between the stator teeth and the compensation pad are filled by a non-magnetic pressing plate with a spacing from the assembly edge; on the side away from the flywheel in the axial direction, the gaps between the stator winding and the pressing plate, the tooth slot and the pressing plate, and the compensation pad and the pressing plate are filled by plastic sealing.

[0011] Optionally, the flywheel teeth are made of a magnetic material, and the flywheel core is made of a non-magnetic material.

[0012] Optionally, the number of stator teeth of each stator of the double-stator disc flywheel energy storage mechanism is 24 teeth, the compensation pad is made of carbon fiber, the shape of the compensation pad is circular, the installation position is concentric with the stator back iron, and the radius is smaller than the minimum radius of the stator teeth by one half of the tooth pitch.

[0013] Optionally, the charging port of the electric vehicle is a double-path structure, and when charging, the battery and the double-stator disc flywheel energy storage mechanism are connected in parallel in the circuit, and the flywheel is preferentially charged when charging.

[0014] Optionally, when not charging, the battery and the two charging circuits of the flywheel are connected in series, so that when not charging, the two parts of the energy storage system realize energy transmission.

[0015] The double-stator disc flywheel energy storage structure combines the flywheel and the motor structure, improves the power density of the flywheel energy storage, and fully utilizes the characteristics of the flywheel energy storage fast charging and discharging, which can effectively reduce the influence of the power system impact current on the battery health state, reduce the electric energy dissipation caused by instantaneous high-power mechanical and electrical energy conversion, improve the efficiency of the power system, and provide the flywheel energy storage as a backup energy of the power system, and improve the vehicle driving range.

[0016] Additional aspects and advantages of the application will be described in the following description, which will become apparent from the description, or will be learned by practice of the application. BRIEF DESCRIPTION OF DRAWINGS

[0017] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following will briefly introduce the drawings needed in the embodiment description. Obviously, the drawings in the following description only show some embodiments of the present application, and other drawings can be obtained by those skilled in the art without any creative effort based on these drawings.

[0018] Figure 1 The structure explosion diagram of the double-stator disc flywheel energy storage mechanism described in the embodiments of the present application.

[0019] Figure 2 The new energy electric vehicle pure electric power system mode conversion flow chart of the new energy electric vehicle containing the double-stator disc flywheel energy storage mechanism in the starting condition of the electric vehicle described in the embodiments of the present application.

[0020] Figure 3 The new energy electric vehicle pure electric power system mode conversion flow chart of the new energy electric vehicle containing the double-stator disc flywheel energy storage mechanism in the starting condition of the electric vehicle described in the embodiments of the present application.

[0021] Figure 4 The new energy electric vehicle pure electric power system mode conversion flow chart of the new energy electric vehicle containing the double-stator disc flywheel energy storage mechanism in the starting condition of the electric vehicle described in the embodiments of the present application.

[0022] Wherein: 1 - shell; 2 - stator back iron; 3 - sealing layer; 4 - flywheel; 5 - rotating shaft; 6 - flywheel tooth; 7 - tooth slot. DETAILED DESCRIPTION

[0023] The embodiments of the present application will be described in detail below, and examples of the embodiments are shown in the drawings, wherein the same or similar notations represent the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with the drawings are exemplary and are only used to explain the present application, and cannot be interpreted as a limitation of the present application.

[0024] Those skilled in the art can understand that, unless otherwise defined, all terms (including technical terms and scientific terms) used herein have the same meaning as that generally understood by those skilled in the art in the field to which the present application belongs.

[0025] It should also be understood that terms such as those defined in general dictionaries should be understood to have meanings consistent with those in the prior art, and will not be interpreted with idealized or overly formal meanings unless defined as such.

[0026] It is to be understood that the singular forms "a," "an," and "the" include plural referents unless the context clearly dictates otherwise. It is further understood that the terms "comprising," "including," "containing," and "having" and the like, when used in the specification, specify the presence of stated features, integers, steps, operations, elements, and / or components but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or groups thereof.

[0027] In the description of the present application, the description of the terms "one embodiment", "some embodiments", "an example", "a specific example", or "some examples" etc. means that the specific features, structures, materials or characteristics described in connection with the embodiment or example are contained in at least one embodiment or example of the application. Moreover, the specific features, structures, materials or characteristics described can be combined in any suitable manner in one or more embodiments or examples. In addition, different embodiments or examples described in the specification and characteristics of different embodiments or examples can be combined and combined by those skilled in the art without contradiction.

[0028] In the description of the present application, the terms "first", "second" are only for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined with "first", "second" can explicitly or implicitly include at least one of the features. In the description of the present application, the meaning of "multiple" is two or more, unless otherwise specifically limited.

[0029] In the description of the present application, the terms "center", "upper", "lower", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer" and the like indicate the orientation or positional relationship shown in the drawings, which is only for the convenience of describing the technology and simplifying the description, and cannot be understood as indicating or implying that the device or element referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as limiting the technology.

[0030] Unless otherwise expressly specified and limited, the terms "mounting", "connecting", "connecting", "setting" should be understood broadly, for example, it can be fixedly connected, set, or it can be detachably connected, set, or integrally connected, set. For those skilled in the art, the specific meaning of the above terms in the present technology can be understood according to the specific circumstances.

[0031] In order to facilitate the understanding of the present application, the present application will be further explained and described in specific embodiments in conjunction with the drawings, and the specific embodiments do not constitute a limitation on the embodiments of the present application.

[0032] Those skilled in the art should understand that the drawings are only schematic views of the embodiments, and the components in the drawings are not necessarily essential for implementing the present application.

[0033] Embodiment 1

[0034] In this embodiment 1, a new energy electric vehicle pure electric power system mode conversion system is provided, which comprises: a self-starting permanent magnet synchronous motor as a rear wheel drive main drive motor, an auxiliary drive motor as a front drive motor, a converter connected with the main drive motor and the auxiliary drive motor respectively, a third converter and a fourth converter connected with the stator winding of the double-stator disc flywheel energy storage mechanism, a first converter and a second converter connected with the battery, and a clutch for connecting the main drive motor and the auxiliary drive motor.

[0035] The double-stator disc flywheel energy storage mechanism comprises: a flywheel arranged in an outer shell, the flywheel being arranged on a rotating shaft, a tooth groove arranged on the flywheel, and a flywheel tooth arranged in the tooth groove; the flywheel is provided with stator back irons on both sides thereof, and winding slots are formed in the stator back irons; and a sealing layer is arranged between the flywheel and the stator back irons.

[0036] The stator teeth are mounted on the rotor back iron, and the stator winding is wound on the stator teeth; the stator back iron is provided with a non-magnetic compensation pad. The main drive motor and the auxiliary drive motor are connected with the battery through the first converter and the second converter respectively. The stator winding of the first stator of the double-stator disc flywheel energy storage mechanism is connected with the battery in parallel on the charging circuit through the fourth converter, and the stator winding of the second stator of the double-stator disc flywheel energy storage mechanism is connected with the power supply circuit of the main drive motor through the third converter.

[0037] The sealing layer is composed of two layers of seals and is combined in the axial direction; on the side of the flywheel in the axial direction, the gap between the stator teeth and the gap between the stator teeth and the compensation pad are filled with a non-magnetic pressing plate with a spacing from the assembly edge; on the side away from the flywheel in the axial direction, the gaps between the stator winding and the pressing plate, the tooth groove and the pressing plate, and the compensation pad and the pressing plate are filled by plastic sealing.

[0038] Specifically, the double-stator disc flywheel energy storage mechanism is of a double-stator structure, the number of stator teeth is 24, the stator teeth are mounted on the stator back iron, and the stator winding is a concentrated winding directly wound on the stator teeth. The stator back iron is also provided with a non-magnetic compensation pad made of lightweight material, the shape of the compensation pad is circular, the installation position of the compensation pad is coaxial with the stator back iron, and the radius of the compensation pad is smaller than the minimum radius of the stator teeth by one half of the tooth pitch. Technically, the stator teeth and the stator back iron are cast as a whole; the compensation pad is fixed by eight hexagonal screws distributed in a circle at a position one half of the radius of the compensation pad.

[0039] The double-stator disc flywheel energy storage mechanism has a gear shape, the flywheel teeth are made of a magnetic conductive material, and the flywheel core is made of a non-magnetic conductive material. The flywheel teeth are fixed on the flywheel core by a wedge structure and a fastening bolt. Since the flywheel teeth are magnetic conductive, the entire flywheel structure has a magnetic field modulation effect, and the special flywheel structure can be regarded as a rotor that can provide magnetic flux switching torque. The double-stator disc flywheel energy storage mechanism is composed of an outer shell with an inner diameter greater than the diameter of the flywheel, a sealing layer that seals the stator teeth and the stator winding, and a vacuum chamber with a high vacuum. The vacuum chamber wraps the flywheel structure that plays a role in energy storage.

[0040] The sealing layer is composed of two layers of seals combined in the axial direction. On the side close to the flywheel in the axial direction, the gap between the stator teeth and the gap between the stator teeth and the compensation pad are filled with a non-magnetic conductive pressing plate with a spacing of less than 1 cm from the assembly edge. On the side away from the flywheel in the axial direction, the gaps between the stator winding and the pressing plate, the tooth slot and the pressing plate, and the compensation pad and the pressing plate are filled by a plastic sealing process.

[0041] The double-stator disc flywheel energy storage mechanism is not mechanically connected to other power systems of a new energy electric vehicle, but only electrically connected. The charging port of the vehicle has a double-path structure. In the structural design, the battery and the flywheel energy storage mechanism are in parallel in the circuit during charging, and the flywheel is preferentially charged during charging. When not charging, the two charging circuits of the battery and the flywheel are connected in series, so that the two energy storage systems can freely transfer energy when not charging.

[0042] Based on the double-stator disc flywheel energy storage mechanism, the electric vehicle mainly relies on the flywheel energy storage mechanism that can realize fast charging and discharging to achieve fast energy conversion process. Short-term large energy conversion, such as heavy load downhill, first stores energy through the flywheel mechanism, and then feeds back the energy to the battery after the working condition ends. The mechanical rotating shaft of the double-stator disc flywheel energy storage mechanism is thicker than that of the ordinary flywheel structure, and the diameter of the mechanical rotating shaft is one-third of the diameter of the flywheel, which plays a good heat conduction role.

[0043] Embodiment 2

[0044] In this embodiment 2, a new energy electric vehicle hybrid power system and a non-hybrid power system mode conversion design strategy is provided. The main structural components of the system include a self-starting permanent magnet synchronous motor as a front wheel drive main drive motor, an auxiliary drive motor as a rear drive motor, a converter connected to the main drive and auxiliary drive motor respectively, a double-stator disc flywheel energy storage mechanism, a battery, a third converter connected to the stator winding of the double-stator disc flywheel energy storage mechanism, a fourth converter, a first converter connected to the battery, a second converter, and a clutch mechanically connecting the main drive and auxiliary drive motor.

[0045] The main drive motor and the auxiliary drive motor are connected with the battery through the first converter and the second converter respectively, the two motors are mechanically connected through the clutch, the stator winding of the first stator of the double-stator disc flywheel energy storage mechanism is connected with the battery in parallel on the charging circuit through the fourth converter, and the stator winding of the second stator is connected with the power supply circuit of the main drive motor through the third converter. The double-stator disc flywheel energy storage mechanism is mechanically connected with other power systems of the new energy electric vehicle, and only electrically connected.

[0046] The double-stator disc flywheel energy storage mechanism has a double-stator structure, the stator tooth number is 24, the stator tooth is installed on the rotor back iron, and the stator winding is a concentrated winding and is directly wound on the stator tooth. The stator back iron is also provided with a non-magnetic compensation pad made of carbon fiber, the compensation pad is circular in shape, the installation position is coaxial with the stator back iron, and the radius is smaller than the minimum radius of the stator tooth by one half of the tooth pitch. From the process, the stator tooth and the stator back iron are cast into one body; the compensation pad is fixed by eight hexagonal screws distributed in a circle at a position one half of the radial position of the compensation pad.

[0047] The flywheel of the double-stator disc flywheel energy storage mechanism is gear-shaped, the flywheel tooth is made of magnetic material, the flywheel core is made of non-magnetic material, and the flywheel tooth is fixed on the flywheel core by a wedge structure and a fastening bolt. Since the flywheel tooth can conduct magnetic field, the entire flywheel structure has a magnetic field modulation effect, and this special flywheel structure can be regarded as a rotor that can provide magnetic flux switching torque. The double-stator disc flywheel energy storage mechanism is composed of an outer shell with an inner diameter larger than the diameter of the flywheel, a sealing layer of the sealed stator tooth and the stator winding, and a vacuum cavity with high vacuum.

[0048] The flywheel of the double-stator disc flywheel energy storage mechanism is a magnetic structure, if the stator winding generates a rotating magnetic field, it will inevitably produce magnetic hysteresis loss on the flywheel tooth, and in order to reduce the friction loss of the flywheel, the flywheel tooth must be placed in the vacuum cavity with poor thermal conductivity. In order to prevent the flywheel temperature from rising beyond the allowable range, the design reduces the amount of magnetic material used in the flywheel structure, which can reduce the loss of magnetic energy and reduce the generation of magnetic hysteresis loss. At the same time, the mechanical rotating shaft of the design is thicker than the ordinary flywheel structure, the diameter of the mechanical rotating shaft is one third of the diameter of the flywheel, and the flywheel tooth, the flywheel core and the mechanical rotating shaft are made of materials with good thermal conductivity, so that the heat generated by the magnetic hysteresis loss on the flywheel tooth can be conducted along the predetermined heat conduction path from the flywheel tooth through the flywheel core, the mechanical shaft to the stator back iron which is in direct contact with the outside and has a larger heat dissipation area, and is dissipated as soon as possible, playing a good heat conduction role.

[0049] Electric vehicles need to achieve a large amount of electromechanical energy conversion process in a short time when driving, such as braking, starting and downhill conditions, if the energy conversion hub is the battery, then in these transient conditions, the battery power supply circuit current will be larger, and the passenger car is often frequent start-stop when driving, which will affect the temperature rise and power reserve of the battery, and may affect the battery life. The new energy vehicle driving power system based on the double-stator disc flywheel energy storage mechanism, due to the fast charge and discharge characteristics of the flywheel energy storage, can withstand the large current impact generated by the short-term electromechanical energy exchange.

[0050] When the new energy vehicle adopts a pure electric power system, there are several basic working states of electric vehicles with double-stator disc flywheel energy storage mechanism as the instantaneous energy conversion hub.

[0051] When the electric vehicle is charging near the charging pile, the traditional charging method is that the charging pile charges the battery through the power supply circuit and DC-DC conversion. When the double-stator disc flywheel energy storage mechanism is added to the power system, the power supply circuit preferentially charges the flywheel energy storage during charging, and the electric energy is converted by the 4th converter to AC power suitable for the 1st stator. The 1st stator generates a rotating magnetic field, and the flywheel teeth play a role in magnetic field modulation, gradually accelerating and storing energy under the action of the rotating magnetic field. The current of the flywheel energy storage structure in this stage reaches 80% of the total charging circuit current. When the flywheel reaches 90% of the rated speed, the current of the flywheel energy storage circuit gradually decreases, and the current of the battery energy storage circuit gradually increases; when the flywheel reaches the rated speed, the flywheel energy storage circuit current occupies a very small proportion, only a small part of the charging power is consumed to maintain the flywheel rated speed rotation, and the charging pile charges the battery with a current close to the rated current. Due to the high efficiency of the flywheel energy storage, the flywheel energy storage stage only needs to occupy 5-10 minutes.

[0052] The starting of the electric vehicle is also the process of the driving motor load starting. For the lamination rotor permanent magnet synchronous motor commonly used by the vehicle enterprise, the starting current of the motor is usually 5-6 times of the rated current. When the electric vehicle is in the large torque output working condition such as acceleration and uphill, the power supply circuit also needs to provide larger stator current. The above conditions will impact the power system energy circuit, and the heavier the load, the longer the duration of large current, the greater the impact on the health status of the battery. When the double-stator disc flywheel energy storage mechanism is added to the power system, during starting, on the one hand, the battery outputs the rated current through the first converter for DC-AC conversion, and on the other hand, the flywheel releases energy, through the interaction of electromagnetic fields, an induced electromotive force is generated in the second stator, and the mechanical energy stored in the flywheel is converted into alternating current energy suitable for the driving motor through the AC-DC-AC conversion of the third converter. If the flywheel energy storage is sufficient, the current higher than the rated value during the starting process is completely provided by the flywheel; if the flywheel energy storage is insufficient, during the initial stage of the starting process, the current higher than the rated value is provided by the flywheel, and then the current output by the flywheel gradually decreases, the current output by the battery gradually increases, and until the current output by the flywheel is zero, at this time, the energy required for the starting process is completely provided by the battery. By using this energy supply strategy, when the flywheel energy storage is sufficient, the flywheel energy storage mechanism with more robustness can withstand larger impact current and energy output higher than the rated current, reducing the burden of the power system on the battery; even if the flywheel energy storage is insufficient, the impact of the impact current on the battery can be reduced as much as possible, prolonging the service life of the battery.

[0053] When the vehicle is normally driven, the power required by the motor is relatively stable, and the required energy is mainly provided by the battery. At the same time, since the flywheel will lose energy due to friction, the battery needs to supplement a small amount of energy required by the flywheel to overcome friction. This process is mainly achieved as follows: after the charging is completed, there are only two energy storage components, the battery and the flywheel energy storage mechanism, in the charging circuit, therefore, the battery needs to output direct current energy, which is converted into alternating current energy suitable for the first stator through the original charging circuit and the fourth converter for inversion, to overcome the friction loss. At this time, the current in the charging circuit accounts for about 10% of the rated output current of the battery, and since the flywheel stores a large amount of energy, the energy used to maintain the flywheel is reasonable.

[0054] In addition, the battery mainly bears the energy required by the driving motor during normal driving. When the electric vehicle needs to output small power, such as light load conditions with 1-2 passengers or flat road driving, the auxiliary driving motor is relied on to provide power for the vehicle. When the electric vehicle needs to output large power, such as load conditions with 3-4 passengers, uphill driving, acceleration driving and harsh road driving, the main driving motor and the auxiliary driving motor are both in the electric state, the clutch between the two motors is engaged, and the two motors are jointly driven.

[0055] When the electric vehicle is in downhill working condition, the traditional control system usually makes the auxiliary drive motor work in the generator state, and the converter connected with the auxiliary drive motor works in the inverter state to feed back the energy to the battery to recover the kinetic energy generated by the downhill. However, the time of downhill is usually short, but the time required for stable charging of the battery is short, and the energy recovery efficiency is usually low when the energy is directly fed back to the battery. When the double-stator disc flywheel energy storage mechanism is added to the power system, the downhill working condition can be designed as follows: the first converter and the second converter directly connected with the drive motor and the battery are disabled, the main drive motor works in the generator state, the third converter connected with the main drive motor and the second stator of the flywheel energy storage mechanism performs AC-DC-AC conversion, and the energy fed back by the main drive motor is converted into alternating current energy suitable for the second stator. The third converter connected with the battery and the second stator of the flywheel energy storage mechanism stops working. That is, at this time, the energy required to maintain the rotation of the flywheel is mainly provided by the energy feedback of the main drive motor. Since the flywheel energy storage mechanism itself has fast response speed, the feedback energy can be more efficiently absorbed and utilized.

[0056] When the battery energy storage is insufficient, the charge and discharge relationship between the battery and the flywheel energy storage mechanism changes, the fourth converter works in the rectification mode, the kinetic energy stored in the flywheel is first converted into alternating current energy, and then the alternating current energy is rectified into direct current energy through AC-DC conversion to charge the battery. This process is designed to be started when the battery energy storage is less than 33%, and the flywheel kinetic energy can be used as reserve energy.

[0057] The double-stator disc flywheel energy storage structure in the embodiment combines the flywheel with the motor structure to improve the power density of the flywheel energy storage. The new energy electric vehicle power system mode conversion method based on the double-stator disc flywheel energy storage mechanism fully utilizes the characteristics of fast charge and discharge of the flywheel energy storage, which can effectively reduce the influence of the power system impact current on the battery health state, reduce the electric energy dissipation caused by instantaneous high-power electromechanical energy conversion, improve the efficiency of the power system, and provide the flywheel energy storage as a backup energy of the power system to improve the vehicle driving range.

[0058] Embodiment 3

[0059] As Figure 1As shown, the embodiment provides a double-stator disc flywheel energy storage structure, wherein structure 1 is an outer shell wrapping a vacuum cavity, structure 2 is a stator back iron, structure 2 has winding slots for accommodating windings, and structure 2 is provided with a light compensating pad. Structure 3 is a sealing layer, including a pressing plate and a plastic sealing part, and the sealing layer tightly fills the gap between the outer shell and structure 2 and the stator windings to form the vacuum cavity. Structure 4 is a flywheel, which is designed in a gear shape and the flywheel teeth are made of magnetic material and are fixed on the flywheel core. Structure 5 is a large-diameter rotating shaft, which provides a good heat conduction path. Structure 6 is a magnetic flywheel tooth, which is arranged in a tooth slot 7 and can play a magnetic field modulation role in the magnetic field formed by the double stator.

[0060] The double-stator disc flywheel energy storage mechanism is a double-stator structure, the number of stator teeth is 24, the stator teeth are installed on the rotor back iron, and the stator windings are concentrated windings directly wound on the stator teeth. The stator back iron is also provided with a non-magnetic compensating pad made of carbon fiber, the shape of the compensating pad is a prototype, the installation position is coaxial with the stator back iron, and the radius is smaller than the minimum radius of the stator teeth by one half of a tooth pitch. From the process, the stator teeth and the stator back iron are cast into one body; the compensating pad is fixed by eight hexagonal screws distributed in a circle at a position one half of the radial direction of the compensating pad.

[0061] The flywheel of the double-stator disc flywheel energy storage mechanism is in a gear shape, the flywheel teeth are made of magnetic material, the flywheel core is made of non-magnetic material, and the flywheel teeth are fixed on the flywheel core by a wedge structure and a fastening bolt. Since the flywheel teeth can conduct magnetic field, the entire flywheel structure has a magnetic field modulation effect, and this special flywheel structure can be regarded as a rotor that can provide magnetic flux switching torque. The double-stator disc flywheel energy storage mechanism consists of an outer shell with an inner diameter larger than the diameter of the flywheel, a sealing layer of the plastic sealed stator teeth and stator windings, and a vacuum cavity with high vacuum. The vacuum cavity wraps the flywheel structure that plays a role in energy storage.

[0062] The flywheel of the double-stator disc flywheel energy storage mechanism is a magnetic structure, if the stator windings generate a rotating magnetic field, it will inevitably generate magnetic hysteresis loss on the flywheel teeth. In order to reduce the friction loss of the flywheel, the flywheel teeth must be placed in a vacuum cavity with poor thermal conductivity. In order to prevent the temperature rise of the flywheel from exceeding the allowable range, the design reduces the amount of magnetic material used in the flywheel structure, which can reduce the loss of magnetic energy and the generation of magnetic hysteresis loss. At the same time, the mechanical shaft of the design is thicker than the ordinary flywheel structure, the diameter of the mechanical shaft is one third of the diameter of the flywheel, and the flywheel teeth, the flywheel core and the mechanical shaft are made of materials with good thermal conductivity, so that the heat generated by the magnetic hysteresis loss on the flywheel teeth can be conducted along the predetermined heat conduction path from the flywheel teeth, through the flywheel core and the mechanical shaft to the stator back iron which is in direct contact with the outside and has a larger heat dissipation area, and is dissipated as soon as possible, playing a good heat conduction role.

[0063] Electric vehicles need to achieve a large amount of electromechanical energy conversion process in a short time when driving, such as braking, starting and downhill conditions, if the energy conversion hub is the battery, then in these transient conditions, the battery power supply circuit current will be larger, and the passenger car is often frequent start-stop when driving, which will affect the temperature rise and power reserve of the battery, and may affect the battery life. The new energy vehicle driving power system based on the double-stator disc flywheel energy storage mechanism, due to the fast charge and discharge characteristics of the flywheel energy storage, can withstand the large current impact generated by the short-term electromechanical energy exchange.

[0064] As Figures 2 to 4 shown, in this embodiment, based on the double-stator flywheel energy storage mechanism described above, a new energy electric vehicle pure electric power system mode conversion design scheme is realized:

[0065] The new energy electric vehicle pure electric power system mode conversion design strategy mainly includes a self-starting permanent magnet synchronous motor as a front wheel drive main drive motor, an auxiliary drive motor as a rear drive motor, a converter connected to the main drive and auxiliary drive motor, a double-stator disc flywheel energy storage mechanism, a battery, a fourth converter connected to the stator winding of the double-stator disc flywheel energy storage mechanism, a third converter, a first converter connected to the battery, a second converter, and a clutch mechanically connecting the main drive and auxiliary drive motor.

[0066] The main drive motor and the auxiliary drive motor are respectively connected to the battery through the first converter and the second converter, and the two motors are mechanically connected through the clutch. The stator winding of the first stator of the double-stator disc flywheel energy storage mechanism is connected in parallel with the battery on the charging circuit through the fourth converter, and the stator winding of the second stator is connected with the power supply circuit of the main drive motor through the third converter. The double-stator disc flywheel energy storage mechanism is not mechanically connected to other power systems of the new energy electric vehicle, but only electrically connected.

[0067] When the new energy vehicle adopts a pure electric power system, there are five basic working states of the electric vehicle with the double-stator disc flywheel energy storage mechanism as the transient energy conversion hub.

[0068] When the electric vehicle is charging near the charging pile, the traditional charging method is that the charging pile charges the battery through the power supply circuit and DC-DC conversion. When the double-stator disc flywheel energy storage mechanism is added to the power system, the power supply circuit preferentially charges the flywheel energy storage during charging. The electric energy is converted into AC electric energy suitable for the first stator through the fourth converter. The first stator generates a spatial rotating magnetic field, and the flywheel teeth play a role in magnetic field modulation. Under the action of the rotating magnetic field, the flywheel gradually accelerates and stores energy. The current of the flywheel energy storage structure reaches 80% of the total charging circuit current at this stage. When the flywheel reaches 90% of the rated speed, the current of the flywheel energy storage circuit gradually decreases, and the current of the battery energy storage circuit gradually increases. When the flywheel reaches the rated speed, the flywheel energy storage circuit current accounts for a very small proportion, and only consumes a small part of the charging power to maintain the flywheel at the rated speed. The charging pile charges the battery at a current close to the rated current. Due to the high efficiency of the flywheel energy storage, the flywheel energy storage stage only needs to occupy 5-10 minutes.

[0069] The starting of the electric vehicle is also the process of starting the drive motor load. For the laminated rotor permanent magnet synchronous motor commonly used by vehicle manufacturers as the drive motor, the starting current of the motor is usually 5-6 times the rated current, which produces an impact on the power system energy circuit. The heavier the load, the longer the duration of high current, and the greater the impact on the health of the battery. When the double-stator disc flywheel energy storage mechanism is added to the power system, during starting, on the one hand, the battery outputs the rated current through the first converter for DC-AC conversion, and on the other hand, the flywheel releases energy. Through the interaction of electromagnetic fields, an induced electromotive force is generated in the second stator, and the mechanical energy stored in the flywheel is converted into AC electric energy suitable for the drive motor through AC-DC-AC conversion of the third converter. If the flywheel energy storage is sufficient, the current above the rated value during the starting process is completely provided by the flywheel; if the flywheel energy storage is insufficient, during the initial stage of the starting process, the current above the rated value is provided by the flywheel, and then the output current of the flywheel gradually decreases, and the output current of the battery gradually increases until the output current of the flywheel is zero. At this time, the energy required for the starting process is completely provided by the battery. With this energy supply strategy, when the flywheel energy storage is sufficient, the flywheel energy storage mechanism with better robustness can withstand larger impact current and energy output above the rated current, reducing the burden on the battery of the power system. Even if the flywheel energy storage is insufficient, the impact of the impact current on the battery can be minimized to prolong the life of the battery.

[0070] When the automobile is running normally, the power required by the motor is relatively stable, and the required energy is mainly provided by the battery. At the same time, since the flywheel will lose energy due to friction, the battery needs to supplement a small amount of energy required for the flywheel to overcome friction. This process is mainly achieved as follows: after the charging is completed, only the battery and the flywheel energy storage mechanism are two energy storage components in the charging circuit, so the battery needs to output direct current power, which is converted into alternating current power suitable for the first stator through the original charging circuit via the fourth converter inverter, to overcome the friction loss. At this time, the current in the charging circuit accounts for about 10% of the rated output current of the battery. Since the flywheel stores a large amount of energy, it is reasonable to maintain the energy used by the flywheel.

[0071] In addition, the battery mainly bears the energy required to drive the motor when running normally. When the electric vehicle needs to output small power, such as light load conditions with 1-2 passengers or flat road driving, the auxiliary drive motor is solely relied on to provide power for the automobile. When the electric vehicle needs to output large power, such as load conditions with 3-4 passengers climbing, accelerating driving, and driving in harsh road conditions, the main drive and auxiliary drive motors are both in the electric state, the clutch between the two motors is engaged, and the two motors are jointly driven.

[0072] When the electric vehicle is in the downhill condition, the traditional control system usually operates the auxiliary drive motor in the generator state, and the converter connected to the auxiliary drive motor works in the inverter state to feed back the energy to the battery to recover the kinetic energy generated by the downhill. However, the time of downhill is usually short, but the time required for stable charging of the battery is short, and the energy recovery efficiency is usually low when the energy is directly fed back to the battery. When the double-stator disc flywheel energy storage mechanism is added to the power system, the downhill condition can be designed as follows: the first and second converters directly connected to the drive motor and the battery are disabled, the main drive motor operates in the generator state, the third converter connected to the main drive motor and the second stator of the flywheel energy storage mechanism performs AC-DC-AC conversion, and the energy fed back by the main drive motor is converted into alternating current power suitable for the second stator. The third converter connected to the battery and the second stator of the flywheel energy storage mechanism stops working. That is, at this time, the energy required to maintain the rotation of the flywheel is mainly provided by the energy feeding of the main drive motor. Since the flywheel energy storage mechanism itself has a fast response speed, the fed-back energy can be more efficiently absorbed and utilized.

[0073] When the battery energy storage is insufficient, the charging and discharging relationship between the battery and the flywheel energy storage mechanism changes, the fourth converter works in the rectification mode, the kinetic energy stored in the flywheel is first converted into alternating current power, and then the AC-DC conversion is rectified into direct current power to charge the battery. This process is designed to be started when the battery energy storage is less than 33%, and the flywheel kinetic energy can be used as reserve energy.

[0074] In summary, the new energy electric vehicle pure electric power system mode conversion design provided by the embodiment of the application contains a flywheel energy storage mechanism, aiming at the mechanical and electrical energy conversion process which is easy to cause loss and threatens the health state of the power battery of the pure electric power driven new energy vehicle, reduces the system energy loss, reduces the impact of short-time large current on the power battery and enhances the robustness of the power system, and proposes a pure electric power system containing a double-stator disc type flywheel energy storage mechanism. The flywheel energy storage mechanism is more robust, absorbs and releases energy faster, is the short-time energy conversion hub, withstands current impact, improves the energy extraction efficiency in the energy feeding process, reduces the consumption of limited electric energy, solves the mileage problem of the electric vehicle, and improves the ability of the driving motor to safely and stably operate.

[0075] Although the specific embodiments of the application are described above with reference to the drawings, the description is not a limitation on the scope of protection of the application, and those skilled in the art should understand that various modifications or changes made on the basis of the disclosed technical solutions of the application without creative labor should be covered within the protection scope of the application.

Claims

1. A mode conversion system for a pure electric power system of a new energy electric vehicle, characterized in that, include: A self-starting permanent magnet synchronous motor serves as the main drive motor for the rear wheels, and an auxiliary drive motor serves as the front drive motor. Converters are connected to the main drive motor and auxiliary drive motor respectively. A third and fourth converter are connected to the stator windings of the dual-stator disc flywheel energy storage mechanism. A first and second converter are connected to the battery. A clutch connects the main drive motor and the auxiliary drive motor. The dual-stator disc flywheel energy storage mechanism includes: a flywheel housed within a housing, mounted on a rotating shaft, with toothed slots containing flywheel teeth; stator back irons on both sides of the flywheel, with winding slots on the stator back irons; a sealing layer between the flywheel and the stator back irons; stator teeth mounted on the rotor back irons, with stator windings wound on the stator teeth; and non-magnetic compensation devices mounted on the stator back irons. The main drive motor and the auxiliary drive motor are connected to the battery through the first converter and the second converter, respectively. The stator winding of the first stator of the dual-stator disc flywheel energy storage mechanism is connected in parallel with the battery in the charging circuit through the fourth converter, and the stator winding of the second stator of the dual-stator disc flywheel energy storage mechanism is connected to the power supply circuit of the main drive motor through the third converter. The sealing layer consists of two seals combined in the axial direction. On the side closer to the flywheel in the axial direction, the gaps between the stator teeth and between the stator teeth and the compensation pad are filled by a non-magnetic pressure plate with a gap from the assembly edge. On the side farther from the flywheel in the axial direction, the gaps between the stator winding and the pressure plate, the tooth groove and the pressure plate, and the compensation pad and the pressure plate are filled by plastic sealing.

2. The new energy electric vehicle pure electric power system mode conversion system according to claim 1, characterized in that, The flywheel teeth are made of magnetic material, while the flywheel core is made of non-magnetic material.

3. The new energy electric vehicle pure electric power system mode conversion system according to claim 1, characterized in that, Each stator of the dual-stator disc flywheel energy storage mechanism has 24 stator teeth. The compensation pad is made of carbon fiber and is circular in shape. Its installation position is concentric with the stator back iron, and its radius is half a tooth pitch smaller than the minimum radius of the stator teeth.

4. The new energy electric vehicle pure electric power system mode conversion system according to any one of claims 1-3, characterized in that, The charging port of the electric vehicle has a dual-path structure. When charging, the battery and the dual-stator disc flywheel energy storage mechanism are connected in parallel in the circuit, and the flywheel is given priority in charging.

5. The new energy electric vehicle pure electric power system mode conversion system according to claim 4, characterized in that, When not charging, the two charging circuits of the battery and flywheel are connected in series, enabling energy transfer between the two energy storage systems when not charging.

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