Parking device, parking system and electric vehicle

Abstract

The present application discloses a parking device, a parking system and an electric vehicle. The parking device includes a synchronous motor and a locking mechanism; the synchronous motor includes a stator and a rotor, the stator is fixed to the electric vehicle; the rotor is used for drivingly connecting with the wheels of the electric vehicle; the locking mechanism is used for locking the rotor so that the vector angle between the rotor and the stator is 0° or 180°; during boost charging, the torque output by the synchronous motor has the minimum absolute value. During fast power-off or other emergency power-off, it is possible to avoid the gear clash phenomenon occurring in the mechanical transmission structure caused by fast power-off, and the NVH problem can be alleviated or eliminated.

Description

[0001] This application is a divisional application. The application number of the original application is 202210589168.5, and the original application date is May 26, 2022. The entire contents of the original application are incorporated into this application by reference. Technical Field

[0002] The present application relates to the technical field of electric vehicles, and in particular to a parking device, a parking system and an electric vehicle. Background Art

[0003] When the voltage of the charging pile is lower than the voltage of the electric vehicle's power battery, a boost charging circuit is usually used to charge the high-voltage power battery. The boost charging circuit uses the motor windings of the synchronous motor, which generates torque during the charging process. When the charging current drops rapidly, the torque generated by the synchronous motor quickly decreases to zero, causing the mechanical structure in the transmission system to rebound and cause noise, vibration, harshness (NVH) problems. Summary of the invention

[0004] The present application provides a parking device, a parking system and an electric vehicle, which can alleviate or eliminate the gear-smacking sound generated when the electric torque drops to zero under a charging pile.

[0005] In the first aspect, the present application provides a parking device that can be used for parking an electric vehicle. The parking device includes a synchronous motor and a locking mechanism. The synchronous motor here is a synchronous motor in a boost charging circuit, which can be connected to a three-phase current, in which the sum of two-phase currents is equal to the third-phase current. The synchronous motor includes a stator and a rotor, the stator is fixed to the electric vehicle, and the rotor can be connected to the wheels of the electric vehicle through a series of mechanical transmission structures. When the electric vehicle is boosted and charged by a charging pile controlled charging method, the synchronous motor will generate torque, and the torque can continue to act on the mechanical transmission structure between the rotor and the wheel. When the charging is completed and the power is turned off or other emergency situations are caused, the torque generated by the synchronous motor is sharply reduced to zero, and the mechanical transmission structure may rebound and cause NVH problems. In the parking device provided by the present application, before the electric vehicle is boosted and charged, the locking mechanism can lock the rotor so that the vector angle between the rotor and the stator is 0° or 180°. When the rotor and the stator are in such a state, the synchronous motor has the minimum absolute value of torque when the electric vehicle is boosted and charged. When the charging station finishes charging or when the charging station is powered off in an emergency, the synchronous motor torque drops quickly to zero without causing much impact on the mechanical transmission structure between the synchronous motor and the wheel, alleviating the tooth-clinching phenomenon caused by the rapid disappearance of torque in the mechanical transmission structure, and thus alleviating the NVH problem caused by mechanical tooth-clinching.

[0006] Possibly, the locking mechanism includes a ratchet wheel and a pawl. The ratchet wheel can be drivingly connected to the rotor. A plurality of ratchet slots are uniformly arranged on the circumferential edge of the ratchet wheel. The pawl is movably mounted on the electric vehicle, and when the pawl falls into any one of the ratchet slots, the locking mechanism can lock the ratchet wheel; the reaction force of the ratchet wheel on the synchronous motor can lock the rotor of the synchronous motor. To make the vector angle between the rotor and the stator be 0° or 180°, it can be achieved by controlling the ratchet wheel. Specifically, the ratchet wheel is set such that when the pawl falls into the ratchet slot, the vector angle between the rotor and the stator is 0° or 180°.

[0007] In a possible implementation manner, the ratchet wheel is coaxially connected to the rotor, and the angular velocity ratio between the rotor and the ratchet wheel is 1. The synchronous motor can directly drive the ratchet wheel to rotate through the rotor. Among them, the angle between the midlines of any two adjacent ratchet slots is inversely proportional to the number of pole pairs of the rotor. When the rotor has n pairs of pole pairs, the angle θ between the midlines of any two adjacent ratchet slots along the radial direction of the ratchet wheel is 180° / n. As long as the pawl falls into any one of the ratchet slots, the vector angle between the rotor and the stator is 0° or 180°. During the boost charging process of the electric vehicle, the torque output by the synchronous motor has the minimum absolute value.

[0008] It is set that when the pawl falls into one of the ratchet slots, there is a mechanical angle between the ratchet wheel and the stator; when the rotor is locked, the vector angle of the rotor and the mechanical angle between the ratchet wheel and the stator when the pawl falls into one of the ratchet slots satisfy the following conditions:

[0009] γ = n(β + θ·q);

[0010] Wherein, γ is the vector angle when the rotor is locked, β is the mechanical angle between the ratchet wheel and the stator when the pawl falls into one of the ratchet slots, and q is a positive integer less than or equal to the number of ratchet slots.

[0011] In another possible implementation manner, the parking device further includes a reducer, and the rotor and the ratchet wheel are drivingly connected through the reducer. Specifically, the reducer includes an input wheel, a transmission wheel, and an output wheel that are sequentially drivingly connected. The input wheel is coaxially connected to the rotor, so that the input end of the reducer has the same angular velocity as the rotor. The output wheel is coaxially connected to the ratchet wheel, so that the output end of the reducer has the same angular velocity as the ratchet wheel. The transmission ratio of the reducer is equivalent to the angular velocity ratio between the rotor and the ratchet wheel mentioned above. Among them, the angle between the midlines of any two adjacent ratchet slots is inversely proportional to the product of the number of pole pairs of the rotor and the transmission ratio. When the rotor has n pairs of pole pairs, the angle (i.e., the ratchet slot angle) between the midlines of any two adjacent ratchet slots along the radial direction of the ratchet wheel is 180° / (m·n). As long as the pawl falls into any one of the ratchet slots, the vector angle between the rotor and the stator is 180°. During the boost charging process of the electric vehicle, the torque output by the synchronous motor has the minimum absolute value.

[0012] When the pawl falls into one of the ratchet slots, there is a mechanical angle between the ratchet and the stator; when the rotor is locked, the vector angle of the rotor and the mechanical angle between the ratchet and the stator when the pawl falls into one of the ratchet slots meet the following conditions:

[0013] γ=m·n(β+θ·q);

[0014] Among them, γ is the vector angle when the rotor is locked, β is the mechanical angle between the ratchet and the stator when the pawl falls into one of the ratchet slots, and q is a positive integer less than or equal to the number of ratchet slots.

[0015] Generally, there is a transmission structure in transmission connection between the synchronous motor and the wheel, and the above-mentioned reducer may be a part of the transmission structure. The ratchet may be transmission connected to any position on the transmission structure, as long as the rotation of the rotor can drive the ratchet to rotate.

[0016] In the second aspect, the present application also provides a parking system, including a vehicle controller and any one of the parking devices in the above technical solutions, wherein the vehicle controller is used to control the locking mechanism. When the charging pile ends charging or the charging pile is powered off in an emergency, the mechanical transmission structure between the synchronous motor and the wheel has a smaller gear-gripping sound, and the NVH problem is alleviated or eliminated.

[0017] In a third aspect, the present application further provides an electric vehicle, comprising a vehicle body, wheels, and the above-mentioned parking system. The stator of the synchronous motor is fixed to the vehicle body, and the rotor is connected to the wheels through a series of mechanical transmission structures. When the electric vehicle charging pile ends charging or the charging pile is powered off in an emergency, the NVH problem caused by the mechanical structure can be alleviated or eliminated. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 It is a schematic diagram of a boost charging circuit structure in the prior art;

[0019] Figure 2 A schematic diagram of a power transmission structure of a parking device provided in an embodiment of the present application;

[0020] Figure 3a A schematic diagram of the structure of a synchronous motor in a parking device provided in an embodiment of the present application;

[0021] Figure 3b A diagram showing the relationship between the stator-rotor vector angle and the synchronous motor torque in a parking device provided in an embodiment of the present application;

[0022] Figure 3c A three-phase current vector relationship diagram of a synchronous motor in a parking device provided in an embodiment of the present application;

[0023] Figure 4a and Figure 4bSchematic diagram of the structure of a parking device provided by an embodiment of the present application;

[0024] Figure 5 Schematic diagram of the structure of a locking mechanism in a parking device provided by an embodiment of the present application;

[0025] Figure 6 Schematic diagram of the stator and rotor structure of a synchronous motor in a parking device provided by an embodiment of the present application;

[0026] Figure 7 Schematic diagram of the structure of a ratchet wheel in a parking device provided by an embodiment of the present application;

[0027] Figure 8a and Figure 8b Schematic diagram of the state of rotation of a ratchet wheel in a parking device provided by an embodiment of the present application;

[0028] Figure 9a Schematic diagram of the stator and rotor structure of a synchronous motor in a parking device provided by an embodiment of the present application;

[0029] Figure 9b Schematic diagram of the structure of a ratchet wheel in a parking device provided by an embodiment of the present application;

[0030] Figure 10a Schematic diagram of the stator and rotor structure of a synchronous motor in a parking device provided by an embodiment of the present application;

[0031] Figure 10b Schematic diagram of the structure of a ratchet wheel in a parking device provided by an embodiment of the present application;

[0032] Figure 11 Schematic diagram of the structure of a parking device provided by an embodiment of the present application;

[0033] Figure 12 Schematic diagram of the ratchet wheel structure of a synchronous motor in a parking device provided by an embodiment of the present application;

[0034] Figure 13 Schematic diagram of the structure of a parking system provided by an embodiment of the present application;

[0035] Figure 14 Schematic diagram of the structure of an electric vehicle provided by an embodiment of the present application.

[0036] Reference numerals:

[0037] 100’ - DC power supply; 200’ - Power battery; 300’ - Inverter;

[0038] 1-synchronous motor; 11-stator; 1111-first winding; 1112-second winding; 1113-third winding; 12-rotor; 121-magnetic pole; 2-locking mechanism; 21-ratchet; 211-ratchet; 212, 212a, 212b-ratchet groove; 22-pawl; 3-reducer; 31-input wheel; 32-transmission wheel; 33-output wheel; 4-differential; 5-drive half shaft; 51-half shaft spline; 6-transmission assembly; 61-transmission spline; 7-wheel; 20-vehicle controller; 100-electric vehicle; 101-frame. DETAILED DESCRIPTION

[0039] Figure 1 Figure 1 is a schematic diagram of a boost charging circuit for an electric vehicle. Figure 1 As shown, the boost charging circuit uses a DC power supply 100' to charge the power battery 200'. Wherein, the DC power supply 100' can be a charging pile. The boost charging circuit includes an inverter 300'. The inverter 300' includes a synchronous motor E and six diodes. Exemplarily, the six diodes are a first diode T1, a second diode T2, a third diode T3, a fourth diode T4, a fifth diode T5, and a sixth diode T6. Wherein, the first diode T1 and the second diode T2 form a first bridge arm, the third diode T3 and the fourth diode T4 form a second bridge arm, and the fifth diode T5 and the sixth diode T6 form a third bridge arm. The midpoint Q1 of the first bridge arm is connected to the U phase of the three-phase circuit of the synchronous motor E, the midpoint Q2 of the second bridge arm is connected to the W phase of the three-phase circuit of the synchronous motor E and the negative pole of the DC power supply 100', and the midpoint Q3 of the third bridge arm is connected to the V phase of the three-phase circuit of the synchronous motor E. The power battery 200' is connected in parallel with a capacitor C. The positive electrode of the power battery 200 ′ is connected to the positive electrode of the DC power source 100 ′, and the negative electrode of the power battery 200 ′ is connected to the first bridge arm, the second bridge arm and the third bridge arm respectively.

[0040] During the charging process of the boost charging circuit, the charging current will cause the synchronous motor E to generate torque. The output shaft of the synchronous motor E is connected to the wheel transmission through a mechanical transmission structure, and the torque of the synchronous motor E will continue to act on the mechanical transmission structure. When the charging pile finishes charging or the charging pile is powered off in an emergency, the charging pile will stop outputting the charging current. Accordingly, the charging current of the boost charging circuit drops rapidly to zero, causing the torque of the synchronous motor E to drop rapidly to zero, which in turn causes the mechanical transmission structure to cause NVH problems.

[0041] To this end, embodiments of the present application provide a parking device, a parking system, and an electric vehicle, which can alleviate or eliminate the NVH problem caused by the boost charging circuit.

[0042] The terms used in the following embodiments are for the purpose of describing specific embodiments only and are not intended to limit the present application. As used in the specification and appended claims of the present application, the singular forms "a", "an", "the", "above-mentioned", "said", and "this" are also intended to include expressions such as "one or more", unless the context clearly indicates otherwise.

[0043] Reference to "one embodiment" or "some embodiments" etc. described in this specification means that a specific feature, structure, or characteristic described in connection with that embodiment is included in one or more embodiments of the present application. Thus, statements such as "in one embodiment", "in some embodiments", "in other some embodiments", "in still other embodiments", etc. that appear in different places in this specification do not necessarily refer to the same embodiment, but mean "one or more but not all embodiments", unless otherwise specifically emphasized in other ways. The terms "comprising", "including", "having", and their variants mean "including but not limited to", unless otherwise specifically emphasized in other ways.

[0044] Figure 2 It is a schematic diagram of the mechanical transmission structure of an electric vehicle. As Figure 2 shown, the mechanical transmission structure between the synchronous motor 1 of the electric vehicle and the wheels includes a speed reducer 3, a differential 4, drive half shafts 5, and a drive transmission assembly 6. The synchronous motor 1 is Figure 1 the synchronous motor E shown.

[0045] Among them, the speed reducer 3 and the differential 4 are connected by gear meshing transmission. The drive half shaft 5 includes a half shaft spline 51. The drive transmission assembly 6 includes a transmission spline 61. The differential 4 is meshed and transmitted with the half shaft spline 51 of the drive half shaft 5. The drive half shaft 5 and the drive transmission assembly 6 are also transmitted through the transmission spline 61. There may also be mechanical transmission structures such as a transmission, a clutch, a drive shaft, etc. between the synchronous motor 1 and the speed reducer 3, which are not shown here.

[0046] Figure 3a It is a schematic diagram of the structure of a synchronous motor in a parking device provided by an embodiment of the present application. As Figure 3a shown, the synchronous motor 1 includes a stator 11 and a rotor 12. Among them, the rotor 12 can rotate relative to the stator 11. Combining Figure 1 shown, during the charging process, the charging current will continuously act on the synchronous motor 1, causing the synchronous motor 1 to generate a torque. When the charging pile finishes charging or the charging pile suddenly cuts off power, the torque generated by the synchronous motor 1 drops rapidly to zero, which may cause gear clashing in the mechanical transmission structure between the synchronous motor 1 and the wheels 7, thereby causing NVH problems.

[0047] Figure 3b It is a relationship diagram between the stator-rotor vector angle and the motor torque of a parking device provided by an embodiment of the present application. It should be understood that Figure 3b The shown angles are only approximate data and there is a certain range of error. From an electrical perspective, when the vector angle between the rotor 12 and the stator 11 of the synchronous motor 1 is different, the torque generated by the synchronous motor 1 during the charging process is different. As Figure 3b shown, the line S1 is the curve of the motor torque of the synchronous motor 1 varying with the vector angle between the rotor 12 and the stator 11 during single-motor measurement, and the line S2 is the curve of the motor torque of the synchronous motor 1 varying with the vector angle between the rotor 12 and the stator 11 during MotorCAD simulation. When the vector angle between the rotor 12 and the stator 11 is 0° or 180°, the absolute value of the torque of the synchronous motor 1 is the smallest during the charging process. Among them, the minimum absolute value of the torque of the synchronous motor 1 can be zero.

[0048] Figure 3c It is a three-phase current vector relationship diagram of a synchronous motor in a parking device provided by an embodiment of the present application. As shown in combination with Figure 1 shown, the coils on the stator 11 of the synchronous motor 1 are connected to the U-phase current, the V-phase current, and the W-phase current. Exemplarily, as Figure 3c shown, the vector angle of the U-phase current of the synchronous motor 1 is 0°, the vector angle of the V-phase current is 120°, and the vector angle of the W-phase current is 240°. Among them, the sum of the U-phase current and the V-phase current is half of the W-phase current. In Figure 3c , the vector angle of the synthesized stator 11 is the direction of the W-phase current, that is, the direction of 240°. In combination with Figure 3b and Figure 3c , when the vector angle of the rotor 12 is in the direction of 240° or 60°, the electrical vector angle between the rotor 12 and the stator 11 is 0° or 180°. At this time, when boosting the charge of the electric vehicle, the torque generated by the synchronous motor 1 has the smallest absolute value.

[0049] When the vector angle between the rotor 12 and the stator 11 of the synchronous motor 1 is locked at 0° or 180°, the electric vehicle is boosted for charging. Then, when the charging pile ends charging or the charging pile powers off emergently, the torque of the synchronous motor 1 quickly drops to zero and will not have too much impact on the mechanical transmission structure. That is, the torque of the synchronous motor 1 is basically 0. When the charging pile ends charging or the charging pile powers off emergently, the change range of the torque of the synchronous motor 1 dropping to zero is very small, and the NVH problem of the mechanical transmission structure caused by the end of charging of the charging pile or the emergency power-off of the charging pile will be alleviated or eliminated. Taking the three-phase current direction of the synchronous motor shown in Figure 3c as an example, the vector angle between the rotor 12 and the stator 11 can be locked at 0° or 180° by locking the rotor 12 to the direction of 240° or 60°.

[0050] The locking mechanism in the parking device provided by the embodiments of the present application is used to lock the rotor 12 of the synchronous motor 1, so that the vector angle between the rotor 12 and the stator 11 is 0° or 180°. When the electric vehicle is charging with boosted voltage, ensure that the torque of the synchronous motor 1 is in the state with the minimum absolute value. Of course, the minimum absolute value here is an ideal state, which can be understood as the minimum absolute value of the torque of the synchronous motor 1 is approximately 0, and it can be considered that the synchronous motor 1 is in a zero-torque state.

[0051] As Figure 4a shown in a parking device, the synchronous motor 1 specifically includes a stator 11 and a rotor 12. The stator 11 and the rotor 12 are relative concepts, that is, the stator 11 is relatively fixed and the rotor 12 rotates relatively. Among them, the stator 11 can be fixed to the vehicle frame of the electric vehicle, so that the stator 11 can remain stationary relative to the electric vehicle. The rotor 12 can rotate relative to the stator 11 around the axis line L0 of the rotor 12 to realize the output of rotational power. The locking mechanism 2 includes a ratchet wheel 21 and a pawl 22. Among them, the ratchet wheel 21 can be coaxially connected to the rotor 12. That is to say, the axis line L1 of the ratchet wheel 21 coincides with the axis line L0 of the rotor 12. A plurality of ratchet slots 212 are uniformly arranged on the circumferential edge of the ratchet wheel 21. The pawl 22 is movably hinged to the vehicle frame, and the pawl 22 can move relative to the ratchet wheel 21 to switch between a first state and a second state. Among them, the first state means that the pawl 22 falls into one of the ratchet slots 212, and the second state means that the pawl 22 disengages from the ratchet slot 212. When the pawl 22 falls into one of the ratchet slots 212, the pawl 22 can lock the ratchet wheel 21, and thus can lock the rotor 12.

[0052] When the parking device includes a speed reducer 3, as Figure 4b shown, the speed reducer 3 has an input wheel 31, a transmission wheel 32 and an output wheel 33. Among them, the input wheel 31 is coaxially connected to the rotor 12, that is, the axis line of the input wheel 31 coincides with the axis line L0 of the rotor 12. One side of the transmission wheel 32 meshes with the input wheel 31, and the other side meshes with the output wheel 33. The rotor 12, the ratchet wheel 21 and the input wheel 31 are coaxially connected. As a part of the mechanical transmission structure of the electric vehicle, the synchronous motor 1 can transmit power to the subsequent mechanical transmission structure through the speed reducer 3 and finally transmit it to the wheels of the electric vehicle. When the pawl 22 falls into any one of the ratchet slots 212, the locking mechanism 2 can lock the rotor 12, and thus lock the power transmission between the synchronous motor 1 and the speed reducer 3, and can block the power transmission of the subsequent mechanical transmission structure to realize the braking of the wheels.

[0053] Please refer to Figure 5The structure of the locking mechanism 2 is shown. The ratchet wheel 21 has ratchet grooves 212 for mating with the pawl 22, and the ratchet teeth 211 are located between any two adjacent ratchet grooves 212. The pawl 22 can be hinged to the vehicle frame of the electric vehicle. Driving the pawl 22 to fall into any one of the ratchet grooves 212 can lock the ratchet wheel 21 so that the ratchet wheel 21 no longer rotates.

[0054] Combined with Figure 4a , the rotor 12 of the synchronous motor 1 is coaxially connected to the ratchet wheel 21. The rotation of the rotor 12 relative to the stator 11 around the axis L0 of the rotor 12 can drive the ratchet wheel 21 to rotate around the axis L1 of the ratchet wheel 21. When the ratchet wheel 21 rotates to a position where the pawl 22 corresponds to any one of the ratchet grooves 212, the pawl 22 can fall into this ratchet groove 212. Driving the pawl 22 to fall into any one of the ratchet grooves 212 can lock the ratchet wheel 21 so that the ratchet wheel 21 no longer rotates. In Figure 4a In the parking device shown, the ratchet wheel 21 is coaxially fixed to the rotor 12, and the locking mechanism 2 can directly lock the rotor 12 of the synchronous motor 1. That is to say, a certain rotational correspondence can be established between the locking mechanism 2 and the rotor 12 of the synchronous motor 1, so that when the pawl 22 of the locking mechanism 2 falls into the ratchet groove 212, the vector angle between the rotor 12 and the stator 11 is 0° or 180°. Specifically, before boost charging, the pawl 22 of the locking mechanism 2 falls into one of the ratchet grooves 212 to cut off the power transmission between the synchronous motor 1 and the wheels, and make the vector angle between the rotor 12 and the stator 11 be 0° or 180°. When the vector angle between the rotor 12 and the stator 11 is 0° or 180°, boost charging is performed on the electric vehicle, and the torque generated by the synchronous motor 1 has the minimum absolute value. When the charging at the charging pile ends or the charging pile performs an emergency power-off, the torque of the synchronous motor 1 quickly drops to zero, and the mechanical transmission structure between the synchronous motor 1 and the wheels is not prone to mechanical gear clash, thereby alleviating or eliminating the NVH problem caused by mechanical gear clash.

[0055] Therefore, it is necessary to establish an association between the locking structure 2 and the synchronous motor 1 so that when the pawl 22 falls into any one of the ratchet grooves 212 on the ratchet wheel 21, the vector angle between the rotor 12 and the stator 11 is 0° or 180°. Based on Figure 5As shown in the figure, the included angle between the midlines of two ratchet slots 212 is set as the ratchet slot included angle θ, and it is set that when the ratchet wheel 21 rotates by an angle of one or more ratchet slot included angles θ, the pawl 22 just falls into one of the ratchet slots 212. Among them, the midline of the ratchet slot 212 refers to the connecting line between the center of the ratchet slot 212 and the center of the ratchet wheel 21 with the circumference of the ratchet wheel 21 as the reference. The rotation of the ratchet wheel 21 can drive the rotation of the rotor 12. When the ratchet wheel 21 rotates by an angle of one or more ratchet slot included angles θ, the rotor 12 will rotate by a mechanical angle of one or more ratchet slot included angles θ relative to the stator 11. It is set that when the rotor 12 rotates this mechanical angle relative to the stator 11, the vector included angle between the rotor 12 and the stator 11 is 0° or 180°. And the electrical angle of the synchronous motor 1 is the product of the mechanical angle of the rotor 12 rotating relative to the stator 11 and the number of pole pairs of the rotor 12, that is to say, the product of the mechanical angle of the rotor 12 rotating relative to the stator 11 and the number of pole pairs is 0° or 180°. From this, it can be known that when the ratchet wheel 21 is coaxially connected to the rotor 12, the included angle between the midlines of any two adjacent ratchet slots 212 is inversely proportional to the number of pole pairs of the rotor 12.

[0056] Based on Figure 4a For the parking device shown in the figure, the ratchet wheel 21 is coaxially fixed to the rotor 12. Among them, when the rotor 12 rotates a certain mechanical angle relative to the stator 11, the electrical angle of the synchronous motor 1 is the product of the mechanical angle and the number of pole pairs. Specifically, the rotor 12 has multiple pairs of pole pairs, and the following conditions are satisfied between the rotor 12 and the ratchet slot 212:

[0057] θ = 180 / n;

[0058] Among them, θ is the included angle between the midlines of any two ratchet slots 212 (that is, the ratchet slot included angle θ), and n is the number of pole pairs. Of course, the number of ratchet slots 212 is an integer. For the synchronous motor 1, if the rotor 12 is provided with n pairs of pole pairs, and n is an integer greater than or equal to 1. Then when the rotor 12 rotates a certain mechanical angle relative to the stator 11, the electrical angle of the synchronous motor 1 is n times the mechanical angle. To keep the vector included angle between the rotor 12 and the stator 11 at 0° or 180°, it is necessary for the rotor 12 to rotate relative to the stator 11 by at least one mechanical angle of 180° / n. The ratchet wheel 21 has the same angular velocity as the rotor 12, so the included angle between the midlines of the two ratchet slots 212 of the ratchet wheel 21 (that is, the ratchet slot included angle θ) can be set to 180° / n. It is set that when the ratchet wheel 21 rotates an integer multiple angle of this ratchet slot included angle θ, the pawl 22 falls into one of the ratchet slots 212, and the rotor 12 is locked. At this time, the rotor 12 also rotates an integer multiple of the mechanical angle of the ratchet slot included angle θ relative to the stator 11, and the vector included angle between the rotor 12 and the stator 11 at this time is 0° or 180°.

[0059] Taking Figure 6Taking the stator 11 and the rotor 12 shown as an example, a first winding 1111, a second winding 1112, and a third winding 1113 are arranged inside the stator 11. Specifically, the first winding 1111 is connected to the U-phase power supply, the second winding 1112 is connected to the V-phase power supply, and the third winding 1113 is connected to the W-phase power supply. Each type of winding on the stator 11 has 3 coils connected in series. On the outer peripheral surface of the rotor 12, 3 pairs of magnetic pole pairs are evenly arranged (two adjacent magnetic poles 121 are a pair, a total of 6 magnetic poles). In Figure 6 the included angle between any two magnetic poles 121 (i.e., the included angle between the midlines of two magnetic poles 121 along the radial direction of the rotor 12) is 60°. Among them, the midline of the magnetic pole 121 refers to the line connecting the center of the magnetic pole 121 and the center of the stator 11 with the circumference of the stator 11 as a reference.

[0060] Correspondingly, the structure of the ratchet 21 should be as Figure 7 shown. 6 ratchet slots 212 are evenly arranged on the circumferential edge of the ratchet 21. The included angle between the midlines of any two adjacent ratchet slots 212 (i.e., the ratchet slot included angle θ) is 60°, and this 60° is obtained by dividing 180° by 3 (the number of pole pairs).

[0061] Continuing to refer to Figure 8a and Figure 8b shown, initially, it is set that the pawl 22 corresponds to one of the ratchet slots 212a on the ratchet 21. In the clockwise direction of the ratchet slot 212a, the adjacent ratchet slot is the ratchet slot 212b. When the synchronous motor 1 drives the ratchet 21 to rotate 60° counterclockwise from Figure 8a shown to the state shown in Figure 8b the pawl 22 is opposite to another ratchet slot 212b on the ratchet 21. If the pawl 22 falls into the ratchet slot 212b at this time, the pawl 22 can lock the ratchet 21.

[0062] Exemplarily, referring to Figure 7 and Figure 8a 、 Figure 8b , 6 ratchet slots 212 are evenly arranged on the circumferential edge of the ratchet 21. Correspondingly, 3 pairs of magnetic pole pairs should be arranged on the rotor 12 of the synchronous motor 1, and n is 3. When the ratchet 21 is locked (when the pawl 22 falls into one of the ratchet slots 212), the mechanical included angle between the ratchet 21 and the stator 11 is β, and it can be considered that the mechanical angle of the synchronous motor 1 is β. When the ratchet 21 rotates from Figure 8a shown to Figure 8bIn the state shown, since the rotor 12 and the ratchet wheel 21 have the same angular velocity during rotation, the rotor 12 of the synchronous motor 1 rotates 60° relative to the stator 11, and the mechanical angle of the synchronous motor 1 is β + 60°. When n = 3, the electrical angle of the synchronous motor 1 is 3×(β + 60°). That is to say, if the ratchet wheel 21 rotates 60° so that the pawl 22 can fall into one of the ratchet slots 212, the vector angle between the rotor 12 and the stator 11 is 180° or 0°, and thus the absolute value of the torque of the synchronous motor 1 is minimized during the boost charging of the electric vehicle. It can be considered that the angle between the midlines of any two adjacent ratchet slots 212 along the ratchet wheel 21 is 180° / n. As long as the ratchet wheel 21 rotates an integer multiple of this angle to make the pawl 22 fall into one of the ratchet slots 212, the synchronous motor 1 will be locked with the vector angle between the rotor 12 and the stator 11 being 180° or 0°, and the absolute value of the torque of the synchronous motor 1 is minimized during the boost charging of the electric vehicle.

[0063] By analogy, when the ratchet wheel 21 rotates relative to the pawl 22 by any one of 60°, 120°, 180°, 240°, 300°, 360° (multiples of 60°) counterclockwise from the Figure 8a state shown, the pawl 22 will be opposite to one of the ratchet slots 212 on the ratchet wheel 21. Driving the pawl 22 to fall into this ratchet slot 212 can lock the ratchet wheel 21, and further lock the synchronous motor 1 with the vector angle between the rotor 12 and the stator 11 being 0° or 180°. Corresponding to the ratchet wheel 21 rotating 60°, 120°, 180°, 240°, 300°, 360° relative to the pawl 22, the rotor 12 rotates 60°, 120°, 180°, 240°, 300°, 360° relative to the stator 11, and the mechanical angles of the synchronous motor 1 are β + 60°, β + 2×60°, β + 3×60°, β + 4×60°, β + 5×60° respectively. The electrical angles of the synchronous motor 1 are 3×(β + 60°), 3×(β + 2×60°), 3×(β + 3×60°), 3×(β + 4×60°), 3×(β + 5×60°), 3×(β + 6×60°) respectively.

[0064] In order to ensure that when the pawl 22 falls into one of the ratchet slots 212, the synchronous motor 1 will be locked with the vector angle between the rotor 12 and the stator 11 being 180° or 0°. It is set that when the pawl 22 falls into one of the ratchet slots 212, there is a mechanical angle between the ratchet wheel 21 and the stator 11; when the rotor 12 is locked, the vector angle of the rotor 12 and the mechanical angle between the ratchet wheel 21 and the stator 11 when the pawl 22 falls into one of the ratchet slots 212 satisfy the following conditions:

[0065] γ = n(β + q·θ);

[0066] Wherein, γ is the vector angle when the rotor 12 is locked, β is the mechanical angle between the ratchet wheel 21 and the stator 11 when the pawl 22 falls into one of the ratchet slots 212, and q is a positive integer less than or equal to the number of ratchet slots 212.

[0067] It should be understood that the vector angle between the rotor 12 and the stator 11 needs to be judged based on the vector angle of the rotor 12 and the vector angle of the stator 11. Taking Figure 3c as a reference, the vector angle when the rotor 12 is locked is 240° or 60°, the vector angle of the stator 11 is 240°, the vector angle between the rotor 12 and the stator 11 is 0° or 180°, and β here is 20°. Corresponding to the ratchet wheel 21 rotating 60°, 120°, 180°, 240°, 300°, 360° (these degrees are all integer multiples of 60°) relative to the pawl 22, the rotor 12 rotates 60°, 120°, 180°, 240°, 300°, 360° relative to the stator 11, and the mechanical angles of the synchronous motor 1 are 80°, 140°, 200°, 260°, 320°, 380° (i.e., 20°) respectively, and the electrical angles of the synchronous motor 1 are 240°, 420° (i.e., 60°), 600° (i.e., 240°), 780° (i.e., 60°), 960° (i.e., 240°), 1140° (i.e., 60°) respectively. The vector angle of the rotor 12 is Figure 3c 240° or 60° in, and the vector angle between the rotor 12 and the stator 11 is 0° or 180°. When the electric vehicle is boosting for charging, the absolute value of the torque of the synchronous motor 1 is the smallest. That is to say, when the rotor 12 is locked by rotating any one of the angles 60°, 120°, 180°, 240°, 300°, 360° (integer multiples of 60°) of the ratchet wheel 21 relative to the pawl 22, the absolute value of the torque of the synchronous motor 1 during boosting for charging has the minimum value. At this time, when the charging pile ends charging or the charging pile powers off emergently, the NVH problem caused by mechanical gear clash of the mechanical transmission structure between the synchronous motor 1 and the wheel can be alleviated or eliminated.

[0068] It should be understood that based on Figure 7 the shown ratchet wheel 21 structure, if there are other possible vector distributions of the three-phase current of the synchronous motor 1 and other possible vector angles of the stator 11, the above β needs to be adjusted accordingly so that when the rotor 12 is locked, the vector angle between the rotor 12 and the stator 11 still remains 0° or 180°, and the torque of the synchronous motor 1 has the minimum absolute value during boosting for charging of the electric vehicle.

[0069] Based on the situation where the ratchet wheel 21 is coaxially fixed to the rotor 12, as Figure 9aAs shown, when the synchronous motor 1 has 2 pairs of magnetic pole pairs, that is, n is 2. Then when the rotor 12 needs to rotate by an integer multiple of 180° / 2 in mechanical angle relative to the stator 11, the vector angle between the rotor 12 and the stator 11 is 0° or 180°. The mechanical angle here should be 90° or an integer multiple of 90°. Correspondingly, as Figure 9b shown, 4 ratchet slots 212 are evenly arranged on the circumferential edge of the ratchet wheel 21 coaxially connected to the rotor 12, and the slot angle θ between any two adjacent ratchet slots 212 is 90°. When the pawl 22 falls into one of the ratchet slots 212 of the ratchet wheel 21, the rotor 12 is locked, the electrical angle of the synchronous motor 1 is 0° or 180°, and the vector angle between the rotor 12 and the stator 11 is 0° or 180°. When the electric vehicle is boosting charging, the torque of the synchronous motor 1 has the minimum absolute value.

[0070] Based on the situation that the ratchet wheel 21 is coaxially fixed to the rotor 12, as Figure 10a shown, when the synchronous motor 1 has 4 pairs of magnetic pole pairs, that is, n is 4. Then when the rotor 12 needs to rotate by an integer multiple of 180° / 4 in mechanical angle relative to the stator 11, the vector angle between the rotor 12 and the stator 11 is 0° or 180°. The mechanical angle here should be 45° or an integer multiple of 45°. Correspondingly, as Figure 10b shown, 8 ratchet slots 212 are evenly arranged on the circumferential edge of the ratchet wheel 21 coaxially connected to the rotor 12, and the angle between any two adjacent ratchet slots 212 is 45°. When the pawl 22 falls into one of the ratchet slots 212 of the ratchet wheel 21, the rotor 12 is locked, the electrical angle of the synchronous motor 1 is 0° or 180°, and the vector angle between the rotor 12 and the stator 11 is 0° or 180°. When the electric vehicle is boosting charging, the torque of the synchronous motor 1 has the minimum absolute value.

[0071] In some other embodiments, as Figure 11 shown, the ratchet wheel 21 of the locking mechanism 2 (the structure can be referred to Figure 5 shown) can also be coaxially fixed to the output wheel 33 of the speed reducer 3. As Figure 11As shown in the figure, the speed reducer 3 has an input wheel 31, a transmission wheel 32, and an output wheel 33. The input wheel 31 is the output end of the speed reducer 3, and the output wheel 33 is also the output end of the speed reducer 3. Among them, the input wheel 31 is coaxially connected to the rotor 12, that is, the axis line of the input wheel 31 coincides with the axis line L0 of the rotor 12. One side of the transmission wheel 32 meshes with the input wheel 31, and the other side meshes with the output wheel 33. The ratchet wheel 21 is coaxially connected to the output wheel 33. That is to say, the axis line L1 of the ratchet wheel 21 coincides with the axis line of the output wheel 33. The rotation of the rotor 12 of the synchronous motor 1 drives the input wheel 31, the transmission wheel 32, and the output wheel 33 to rotate in sequence, and then drives the ratchet wheel 21 to rotate. When the pawl 22 locks the ratchet wheel 21, the locking mechanism 2 can lock the output wheel 33, and then lock the power transmission between the speed reducer 3 and the subsequent power transmission structure, and thus block the power transmission of the subsequent mechanical transmission structure to achieve the braking of the wheel. In Figure 11 In the parking device shown, the locking mechanism 2 can act on the speed reducer 3 to indirectly lock the rotor 12 of the synchronous motor 1. It is also possible to establish a certain rotational correspondence relationship between the locking mechanism 2 and the rotation of the rotor 12 of the synchronous motor 1, so that when the pawl 22 of the locking mechanism 2 falls into the ratchet groove 212, the vector angle between the rotor 12 and the stator 11 is 0° or 180°. When the electric vehicle is performing boost charging, the synchronous motor 1 has the minimum absolute value of torque. When the charging pile ends charging or the charging pile performs an emergency power-off, the mechanical transmission structure between the speed reducer 3 and the wheel has the minimum absolute value (which can be 0) of torque due to the synchronous motor 1, and it is not easy to generate mechanical gear clash, thereby alleviating or eliminating the NVH problem caused by mechanical gear clash.

[0072] Based on Figure 11 In the parking device shown, the ratchet wheel 21 is coaxially fixed to the output wheel 33 of the speed reducer 3. The correlation between the rotation angle of the ratchet wheel 21 and the rotation angle of the rotor 12 will be affected by the transmission ratio of the speed reducer 3. And the electrical angle of the synchronous motor 1 is the product of the mechanical angle of the rotor 12 rotating relative to the stator 11 and the number of pole pairs of the rotor 12. That is to say, the product of the mechanical angle of the rotor 12 rotating relative to the stator 11 and the number of pole pairs is 0° or 180°, and the mechanical angle of the rotor 12 rotating relative to the stator 11 has a multiple relationship of the transmission ratio with the rotation angle of the ratchet wheel 21. It can be seen from this that when the ratchet wheel 21 is coaxially connected to the rotor 12, the angle between the midlines of any two adjacent ratchet grooves 212 is inversely proportional to the transmission ratio of the speed reducer 3 and the number of pole pairs of the rotor 12.

[0073] Based on Figure 4aThe parking device shown has a transmission connection between the ratchet wheel 21 and the rotor 12 through the speed reducer 3. Among them, when the ratchet wheel 21 rotates by a mechanical angle, the rotor 12 rotates relative to the stator 11 by a mechanical angle that is the product of this mechanical angle and the transmission ratio. The electrical angle of the synchronous motor 1 is the product of the mechanical angle and the number of pole pairs. Specifically, the rotor 12 has multiple pairs of pole pairs, and the following conditions are met between the rotor 12 and the ratchet groove 212:

[0074] θ = 180 / m·n;

[0075] Among them, θ is the angle between the center lines of any two ratchet grooves 212 (i.e., the ratchet groove angle θ), m is the transmission ratio of the speed reducer (which can also be regarded as the ratio of the angular velocities of the rotor 12 and the ratchet wheel 21), and n is the number of pole pairs.

[0076] For the synchronous motor 1, if the rotor 12 is provided with n pairs of pole pairs, where n is an integer greater than or equal to 1. Then when the rotor 12 rotates by a certain mechanical angle relative to the stator 11, the electrical angle of the synchronous motor 1 is n times the mechanical angle. To keep the vector angle between the rotor 12 and the stator 11 at 0° or 180°, the rotor 12 needs to rotate relative to the stator 11 by at least a mechanical angle of 180° / n. There is a transmission ratio m between the ratchet wheel 21 and the rotor 12, and the angle between the center lines of the two ratchet grooves 212 of the ratchet wheel 21 (i.e., the ratchet groove angle θ) can be set to 180° / m·n. Set the ratchet wheel 21 to rotate by an integer multiple of this ratchet groove angle θ, and the pawl 22 falls into one of the ratchet grooves 21, locking the rotor 12. At this time, the rotor 12 rotates relative to the stator 11 by a mechanical angle that is m times the ratchet groove angle θ, and the vector angle between the rotor 12 and the stator 11 is 0° or 180°. Still taking Figure 6 the stator 11 and the rotor 12 shown as an example, the inner side of the stator 11 is provided with a first winding 1111, a second winding 1112, and a third winding 1113. Specifically, the first winding 1111 is connected to the U-phase electricity, the second winding 1112 is connected to the V-phase electricity, and the third winding 1113 is connected to the W-phase electricity. Each type of winding on the stator 11 has 3 coils connected in series. 3 pairs of pole pairs are evenly arranged on the outer peripheral surface of the rotor 12 (two adjacent magnetic poles 121 are a pair, with a total of 6 magnetic poles 121). In Figure 6 it, the angle between any two magnetic poles 121 (i.e., the angle between the center lines of the two magnetic poles 121 along the radial direction of the rotor 12) is 60°.

[0077] Set the transmission ratio of the speed reducer 3 to m. The ratio of the rotational angular velocity of the rotor 12 (i.e., the rotational angular velocity of the input wheel 31) to the rotational angular velocity of the output wheel 33 (i.e., the rotational angular velocity of the ratchet wheel 21) is m:1. Correspondingly, the structure of the ratchet wheel 21 should be as Figure 12As shown, 12 ratchet slots 212 are evenly arranged on the circumferential edge of the ratchet wheel 21. The angle between the midlines of any two adjacent ratchet slots 212 (i.e., the ratchet slot angle θ) is 30°, which is obtained by dividing 180° by the multiple of 3 (number of pole pairs) and 2 (transmission ratio). When the pawl 22 falls into one of the ratchet slots 212, the pawl 22 can lock the ratchet wheel 21.

[0078] Exemplarily, referring to Figure 6 and Figure 12 , 12 ratchet slots 212 are evenly arranged on the circumferential edge of the ratchet wheel 21. The angular velocity ratio of the rotor 12 to the ratchet wheel 21 is 2 (m is 2). Correspondingly, 3 pairs of magnetic pole pairs should be provided on the rotor 12 of the synchronous motor 1, and n is 3. When it is assumed that the ratchet wheel 21 is locked (when the pawl 22 falls into one of the ratchet slots 212), the mechanical angle between the ratchet wheel 21 and the stator 11 is β, and it can be considered that the mechanical angle of the synchronous motor 1 is β. Since the angular velocity ratio between the rotor 12 and the ratchet wheel 21 is 2, when the ratchet wheel 21 rotates 30°, the rotor 12 of the synchronous motor 1 rotates 60° relative to the stator 11, and the mechanical angle of the synchronous motor 1 is β + 60°. When n is 3, the electrical angle of the synchronous motor 1 is 3×(β + 60°). That is to say, if the ratchet wheel 21 rotates 30°, the pawl 22 can fall into one of the ratchet slots 212. The vector angle between the rotor 12 and the stator 11 is 180° or 0°, so that the absolute value of the torque of the synchronous motor 1 is the smallest when the electric vehicle is boost-charging. It can be considered that the angle between the midlines of any two adjacent ratchet slots 212 along the ratchet wheel 21 is 180° / n·m. As long as the ratchet wheel 21 rotates an integer multiple of this angle, the pawl 22 can fall into one of the ratchet slots 212, and the synchronous motor 1 will be locked so that the vector angle between the rotor 12 and the stator 11 is 180° or 0°, and the absolute value of the torque of the synchronous motor 1 is the smallest when the electric vehicle is boost-charging.

[0079] And so on. When the ratchet wheel 21 rotates relative to the pawl 22 at any one of the angles of 30°, 60°, 120°, 150°, 180°, 210°, 240°, 270°, 300°, 330°, 360° (multiples of 30°), the position of one of the ratchet slots 212 on the ratchet wheel 21 is opposite to the pawl 22. When the pawl 22 falls into the ratchet slot 212, the ratchet wheel 21 can be locked, and further, the rotor 12 of the synchronous motor 1 can be locked at a vector angle of 0° or 180° between the rotor 12 and the stator 11. Corresponding to the ratchet wheel 21 rotating relative to the pawl 22 at 30°, 60°, 120°, 150°, 180°, 210°, 240°, 270°, 300°, 330°, 360°, the rotor 12 rotates relative to the stator 11 at 60°, 120°, 180°, 240°, 300°, 360°, 420° (i.e., 60°), 480° (i.e., 120°), 540° (i.e., 180°), 600° (i.e., 240°), 660° (i.e., 200°), 720° (i.e., 360°). The mechanical angles between the rotor 12 and the stator 11 of the synchronous motor 1 are β + 60°, β + 2×60°, β + 3×60°, β + 4×60°, β + 5×60°, β + 6×60°, β + 7×60°, β + 8×60°, β + 9×60°, β + 10×60°, β + 11×60°, β + 12×60° respectively. The electrical angles of the synchronous motor 1 are 3×(β + 60°), 3×(β + 2×60°), 3×(β + 3×60°), 3×(β + 4×60°), 3×(β + 5×60°), 3×(β + 6×60°), 3×(β + 7×60°), 3×(β + 8×60°), 3×(β + 8×60°), 3×(β + 9×60°), 3×(β + 10×60°), 3×(β + 11×60°), 3×(β + 12×60°) respectively.

[0080] It is set that when the pawl 22 falls into one of the ratchet slots 212, there is a mechanical angle between the ratchet wheel 21 and the stator 11; when the rotor 12 is locked, the vector angle of the rotor 12 and the mechanical angle between the ratchet wheel 21 and the stator 11 when the pawl 22 falls into one of the ratchet slots 212 satisfy the following conditions:

[0081] γ = n·m(β + q·θ);

[0082] Where γ is the vector angle when the rotor 12 is locked, β is the mechanical angle between the ratchet wheel 21 and the stator 11 when the pawl 22 falls into one of the ratchet slots 212, and q is a positive integer less than or equal to the number of ratchet slots 212.

[0083] Take Figure 3cFor reference, when the rotor 12 is locked, the vector angle is 240° or 60°, the vector angle of the stator 11 is 240°, the vector angle of the stator 11 is 240°, the vector angle between the rotor 12 and the stator 11 is 0° or 180°, and β here is 10°. Corresponding to the ratchet 21 rotating relative to the pawl 22 by 30°, 60°, 90°, 120°, 150°, 180°, 210°, 240°, 270°, 300°, 330°, 360° (these degrees are all integer multiples of 30°), the rotor 12 rotates relative to the stator 11 by 60°, 120°, 180°, 240°, 300°, 360°, 420°, 480°, 540°, 600°, 660°, 720°. The mechanical angles of the synchronous motor 1 are 70°, 130°, 190°, 250°, 310°, 430° (i.e., 70°), 490° (i.e., 130°), 550° (i.e., 190°), 610° (i.e., 250°), 670° (i.e., 310°), 730° (i.e., 10°), and the electrical angles of the synchronous motor 1 are 420° (i.e., 60°), 780° (i.e., 60°), 1140° (i.e., 60°), 1500° (i.e., 60°), 1860° (i.e., 60°), 2580° (i.e., 60°), 2940° (i.e., 60°), 3300° (i.e., 60°), 3660° (i.e., 60°), 4020° (i.e., 60°), 4380° (i.e., 60°). The vector angle corresponding to the rotor 12 is Figure 3c 240° or 60° in Figure 3c , and the vector angle between the rotor 12 and the stator 11 is 0° or 180°. When the electric vehicle is in boost charging, the absolute value of the torque of the synchronous motor 1 is the smallest. That is to say, when the ratchet 21 rotates relative to the pawl 22 by any one of 30°, 60°, 120°, 150°, 180°, 210°, 240°, 270°, 300°, 330°, 360° (integer multiples of 30°) to lock the rotor 12, the absolute value of the torque of the synchronous motor 1 during boost charging has the minimum value. At this time, when the charging pile ends charging or the charging pile powers off emergently, the NVH problem caused by mechanical gear meshing of the mechanical transmission structure between the synchronous motor 1 and the wheel can be minimized or eliminated.

[0084] It should be understood that based on Figure 12 the structure of the ratchet 21 shown, if there are other possible vector distributions of the three-phase current of the synchronous motor 1 and the vector angle of the stator 11 has other possibilities, the above β needs to be adjusted accordingly so that when the rotor 12 is locked, the vector angle between the rotor 12 and the stator 11 still remains 0° or 180°, and the torque of the synchronous motor 1 has the minimum absolute value during boost charging of the electric vehicle.

[0085] Based on the ratchet 21 being coaxially fixed toFigure 11 The output wheel 33 of the reducer 3 is shown in FIG. 1 , and the transmission ratio of the reducer 3 is m. Figure 9a As shown, when the synchronous motor 1 has 2 pairs of magnetic pole pairs, that is, n is 2. When the rotor 12 is required to rotate relative to the stator 11 by a mechanical angle of an integer multiple of 180° / 2m, the vector angle between the rotor 12 and the stator 11 is 0° or 180°. The circumferential edge of the ratchet 21 is evenly provided with 4×m ratchet grooves 212, and the ratchet groove angle θ between any two adjacent ratchet grooves 212 is 90° / m. When the pawl 22 falls into one of the ratchet grooves 212 of the ratchet 21, the rotor 12 is locked, the electrical angle of the synchronous motor 1 is 0° or 180°, and the vector angle between the rotor 12 and the stator 11 is 0° or 180°. When the electric vehicle is boosted and charged, the torque of the synchronous motor 1 has the minimum absolute value.

[0086] Based on the ratchet 21 coaxially fixed Figure 11 The output wheel 33 of the reducer 3 is shown in FIG. 1 , and the transmission ratio of the reducer 3 is m. Figure 10a As shown, when the synchronous motor 1 has 4 pairs of magnetic pole pairs, that is, n is 4. When the rotor 12 is required to rotate relative to the stator 11 by a mechanical angle of an integer multiple of 180° / 4m, the vector angle between the rotor 12 and the stator 11 is 0° or 180°. The circumferential edge of the ratchet 21 is evenly provided with 8×m ratchet grooves 212, and the ratchet groove angle θ between any two adjacent ratchet grooves 212 is 90° / 4m. When the pawl 22 falls into one of the ratchet grooves 212 of the ratchet 21, the rotor 12 is locked, the vector angle between the rotor 12 and the stator 11 is 0° or 180°, the electrical angle of the synchronous motor 1 is 0° or 180°, and the vector angle between the rotor 12 and the stator 11 is 0° or 180°. When the electric vehicle is boosted and charged, the torque of the synchronous motor 1 has the minimum absolute value.

[0087] It should be understood that Figure 4a and Figure 11 In the schematic diagram of the braking device 10, the transmission connection between the ratchet 21 and the synchronous motor 1 is only for illustration. Possibly, the ratchet 21 can also be transmission-connected to other structures between the synchronous motor 1 and the wheel, as long as the synchronous motor 1 can drive the ratchet 21 to rotate. The above association between the ratchet 21 and the synchronous motor 1 is based on Figure 4a and Figure 11Two specific transmission structures are established. If the ratchet 21 is connected to other mechanical transmission structures between the synchronous motor 1 and the wheel, other connections can be established between the ratchet 21 and the synchronous motor 1. As long as the pawl 22 can fall into any ratchet groove 212 in the ratchet 21, the synchronous motor 1 can be locked so that the vector angle between the rotor 12 and the stator 11 is 0° or 180°. When the electric vehicle is boosted and charged, the torque output by the synchronous motor 1 has the smallest absolute value. Therefore, when the charging pile finishes charging or the charging pile is powered off in an emergency, the tooth-playing phenomenon between the synchronous motor 1 and the wheel can be alleviated or eliminated, and the NVH problem can also be alleviated or solved.

[0088] For the parking device, the locking mechanism 2 provided in the above embodiment is only a possible implementation mode. Other locking structures may also be used. As long as the rotor 12 of the synchronous motor 1 can be locked to a vector angle of 0° or 180° between the rotor 12 and the stator 11, so that the absolute value of the torque output by the synchronous motor 1 in the boost charging state is minimized, the tooth-clutching phenomenon of the transmission structure between the synchronous motor 1 and the wheel can be alleviated, thereby alleviating or eliminating the NVH problem.

[0089] Based on the above parking device, the embodiment of the present application also provides a parking system, such as Figure 13 As shown, the parking system includes a vehicle controller 20 and any one of the above-mentioned parking devices, wherein the ratchet 21 of the locking mechanism 2 is transmission-connected to the rotor 12 of the synchronous motor 1, and the power transmission structure between the ratchet 21 and the rotor 12 is not shown. The vehicle controller 20 is signal-connected to the locking mechanism 2. Before boost charging, the vehicle controller 20 controls the ratchet 22 of the locking mechanism 2 to fall into the ratchet groove 212 to lock the rotor 12, so that the vector angle between the rotor 12 and the stator 11 is 0° or 180°. During the boost charging process, the torque of the synchronous motor 1 has the smallest absolute value. When the power is turned off at the end of charging or other emergency situations, the tooth-smacking sound between the mechanical transmission structure between the synchronous motor 1 and the wheel is small, and the NVH problem is alleviated or eliminated.

[0090] In addition, the embodiment of the present application also provides an electric vehicle 100, which includes the above parking system. Figure 14As shown, the synchronous motor 1 and the vehicle controller 20 are fixed to the frame 101 of the electric vehicle 100. The synchronous motor 1 is drivingly connected to the wheel 7 through a series of mechanical transmission structures. The locking mechanism 2 is disposed between the synchronous motor 1 and the wheel 7, and the locking mechanism 2 can lock the synchronous motor 1 through a locking mechanical structure. Among them, a corresponding association is established between the locking mechanism 2 and the synchronous motor 1, so that the locking mechanism 2 can lock the synchronous motor 1 with the vector angle between the rotor 12 and the stator 11 maintained at 0° or 180°. During boost charging, the synchronous motor 1 has the minimum absolute value of torque. When the charging pile ends charging or when the charging pile powers off emergently, the mechanical transmission structure between the synchronous motor 1 and the wheel 7 will not produce a severe mechanical gear clash phenomenon due to the torque of the synchronous motor 1 dropping to zero. This alleviates or eliminates the NVH problem.

[0091] The above is only the specific implementation manner of the present application, but the protection scope of the present application is not limited thereto. Any person skilled in the art within the technical scope disclosed by the present application can easily think of changes or substitutions, which should all be covered within the protection scope of the present application. Therefore, the protection scope of the present application shall be subject to the protection scope of the claims.

Claims

1. A parking device, characterized in that, The parking device includes a synchronous motor and a locking mechanism. The synchronous motor includes a stator and a rotor. The locking mechanism is used to lock the rotor. The locking mechanism includes a ratchet and a pawl. The ratchet is drivingly connected to the rotor. A plurality of ratchet grooves are uniformly arranged on the circumferential edge of the ratchet. Wherein: The synchronous motor is used to transmit power to the subsequent mechanical transmission structure through a speed reducer and finally transmit it to the wheels of the electric vehicle. The pawl falls into any one of the ratchet grooves to lock the ratchet. The number of magnetic pole pairs of the rotor is n, the transmission ratio of the speed reducer or the angular velocity ratio of the rotor to the ratchet is m, and the angle θ between the midlines of any two of the ratchet grooves is 180 / (m·n). When the ratchet is coaxially fixed to the output wheel of the speed reducer, when the pawl falls into one of the ratchet grooves, the mechanical angle between the ratchet and the stator and the vector angle when the rotor is locked satisfy γ = m·n(β + q·θ), where γ is the vector angle of the rotor, β is the mechanical angle between the ratchet and the stator, and q is a positive integer less than or equal to the number of ratchet grooves. When the ratchet is coaxially connected to the rotor, when the pawl falls into one of the ratchet grooves, the mechanical angle between the ratchet and the stator and the vector angle when the rotor is locked satisfy γ = n(β + q·θ), where γ is the vector angle when the rotor is locked, β is the mechanical angle between the ratchet and the stator when the pawl falls into one of the ratchet grooves, and q is a positive integer less than or equal to the number of ratchet grooves. The electric vehicle includes a boost charging circuit. The boost charging circuit uses a DC power source to charge the power battery of the electric vehicle. During the charging process, the charging current of the boost charging circuit causes the synchronous motor to generate torque. Before boost charging, the pawl falls into one of the ratchet grooves to lock the rotor, and the vector angle between the rotor and the stator is 0° or 180°.

2. The parking device according to claim 1, characterized in that, The speed reducer includes an input wheel, a transmission wheel, and an output wheel that are sequentially drivingly connected. The input wheel is used to be coaxially connected to the rotor. One side of the transmission wheel is used to mesh with the input wheel, and the other side of the transmission wheel is used to mesh with the output wheel. The ratchet is coaxially connected to the output wheel.

3. The parking device according to claim 1, characterized in that, The angular velocity ratio of the rotor to the ratchet is 1, the number of magnetic pole pairs of the rotor is 3, the number of ratchet grooves is 6, and the angle θ between the midlines of any two adjacent ratchet grooves is 60°.

4. The parking device according to claim 1, characterized in that The ratchet is coaxially fixed to the rotor, the number of magnetic pole pairs of the rotor is 2, the number of ratchet grooves is 4, and the angle θ between the midlines of any two adjacent ratchet grooves is 90°.

5. The parking device according to claim 1, characterized in that, The ratchet is coaxially fixed to the rotor, the number of magnetic pole pairs of the rotor is 4, the number of ratchet grooves is 8, and the angle θ between the midlines of any two adjacent ratchet grooves is 45°.

6. A parking system, characterized in that, It includes a vehicle controller and the parking device as described in claim 1. The vehicle controller is used to control the locking mechanism.

7. An electric vehicle, characterized in that, Including: A vehicle body and wheels, and The parking device according to claim 1 or the parking system according to claim 6.

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