Method for performing speed synchronization

Abstract

A method for performing speed synchronization, wherein the method is used to perform speed synchronization of a first transmission member (32, 34) having a first initial speed and a second transmission member (18) having a second initial speed during a gear shift in a stepped gear transmission (6) of a powertrain (4), using a three-phase AC motor (2b) rotationally connected to the first transmission member (32, 34), the powertrain (4) having a switching mechanism (50) that enables the stator windings (W1-W3) of the AC motor (2b) to be selectively connected in a star configuration or a delta configuration. The method comprises: (S10) obtaining a command that a gear shift should be performed (S10) or determining that a gear shift should be performed; (S20) transforming the stator winding structure of the AC motor (2b) into a triangular configuration, or ensuring that the stator winding structure of the AC motor (2b) is in a triangular configuration; and (S30) controlling the operation of the AC motor (2b) to achieve speed synchronization of the first transmission component (32, 34) and the second transmission component (18).

Description

Technical Field

[0001] The present disclosure relates to a method for performing a speed synchronization of a first transmission member having a first initial speed and a second transmission member having a second initial speed by means of a three-phase AC electric motor. The present disclosure also relates to an electric powertrain for a vehicle, wherein the electric powertrain comprises a three-phase AC electric propulsion motor arranged to achieve a speed synchronization of the first transmission member and the second transmission member.

[0002] The method and system according to the present disclosure may be arranged in a multi-speed transmission of a vehicle such as an automobile. However, the present disclosure is not limited to implementation in an automobile, but may alternatively be installed or implemented in another type of vehicle, such as a truck, bus, off-road vehicle, mining vehicle, agricultural vehicle, work vehicle, forest vehicle, marine vessel, motorcycle, etc. In addition, the method and system according to the present disclosure may also be installed or implemented in a fixed transmission device, such as an industrial powertrain system. Background Art

[0003] In the field of transmissions, especially multi-speed transmissions, there is a need for continuous improvement in shifting performance, such as shifting speed, shifting smoothness, shifting reliability, etc. One specific sequence of shifting involves the rotational synchronization of transmission members that should be rotationally connected during the shifting.

[0004] From US2019113137 A1 a method for achieving high speed rotational synchronization is known, which shows synchronization by using a three-phase electric machine rotationally connected to a first transmission member. However, despite some activity in the field, there is still a need to further improve the gearshift performance. Summary of the invention

[0005] An object of the present disclosure is to provide a method and system that provide faster rotational synchronization during gear shifting using an electric machine. This object is at least partly achieved by the features of the independent claims.

[0006] According to a first aspect of the present disclosure, a method for performing speed synchronization is provided, the method being used to perform speed synchronization of a first transmission member having a first initial speed and a second transmission member having a second initial speed by using a three-phase AC motor rotationally connected to the first transmission member during a gear shift in a stepped gear transmission of a powertrain. The powertrain has a switching mechanism that enables the stator winding of the AC motor to be selectively connected in a star configuration or a delta configuration. The method includes: obtaining a command that a gear shift should be performed or determining that a gear shift should be performed; switching the stator winding configuration of the AC motor to a delta configuration, or ensuring that the stator winding configuration of the AC motor is in a delta configuration; and controlling the operation of the AC motor to achieve speed synchronization of the first transmission member and the second transmission member.

[0007] According to a second aspect of the present disclosure, an electric power transmission system for a vehicle is provided. The electric power transmission system includes an electric storage system, an inverter, and a three-phase AC electric propulsion motor, which is drivingly connected to the wheel of the vehicle through a stepped gear transmission having a first transmission member and a second transmission member, wherein the AC motor is rotationally connected to the first transmission member. The electric power system also includes: a switching mechanism having a set of electric switches, the electric switches are used to enable the stator winding of the AC motor to be selectively connected in a star configuration or a triangle configuration; and a control unit, which is used to control the operation of the switching mechanism, wherein the control unit is configured to: obtain a command that a gear shift should be performed or determine that a gear shift should be performed; switch the stator winding structure of the AC motor to a triangle configuration, or ensure that the stator winding structure of the AC motor is in a triangle configuration; and control the operation of the AC motor to achieve the speed synchronization of the first transmission member and the second transmission member.

[0008] By providing a powertrain system having a three-phase AC motor that can switch between star and delta configurations, the higher phase voltage available in the delta configuration can be used to produce higher motor output torque and thereby produce a shorter synchronization time period.

[0009] Further advantages are achieved by implementing one or several of the features of the dependent claims.

[0010] In some exemplary embodiments, switching the stator winding configuration of the AC motor to a delta configuration, or ensuring that the stator winding configuration of the AC motor is in a delta configuration, includes: checking a current stator winding configuration; and when the current stator winding configuration is a star configuration, switching the stator winding configuration of the AC motor to a delta configuration, and when the current stator winding configuration is a delta configuration, maintaining the stator winding configuration of the AC motor in a delta configuration. In other words, the switching of the winding configuration is necessary only when the AC motor is in a star connection before starting the synchronization process.

[0011] In some exemplary embodiments, during the synchronization of the speeds of the first transmission member and the second transmission member, the AC motor is controlled in a scalar control mode. This provides a simple and fast control mode that can be started instantly, which can be useful considering that the entire shift sequence is typically executed in less than 1 second, specifically less than 0.5 seconds.

[0012] In some exemplary embodiments, the AC motor is controlled in a vector control mode before and after the rotation speeds of the first transmission member and the second transmission member are synchronized, which provides a highly efficient and accurate control method for the AC motor.

[0013] In some exemplary embodiments, when the speed synchronization is completed, the first transmission member and the second transmission member rotate at an appropriate relative speed suitable for achieving mutual rotational connection.

[0014] In some exemplary embodiments, the method further comprises controlling the switches of the inverter to remain in an open state during the operation of the switching mechanism for converting the stator winding configuration of the AC motor from a star configuration to a delta configuration, thereby preventing undesirable current spikes (spikes) caused by switching between star connection and delta connection from passing through the inverter switches.

[0015] In some exemplary embodiments, the method includes coordinating the operation of the switching mechanism for converting the stator winding configuration of the AC motor from a star configuration to a delta configuration with the operating point of the AC motor so as to ensure the discharge of the phase inductance voltage of the AC motor before triggering the operation of the switching mechanism. Thus, the current spike caused by the inductance in the motor winding is allowed to discharge, thereby preventing interference with the inverter, DC link, battery, etc.

[0016] In some exemplary embodiments, the method includes: providing a switching mechanism with a set of electrical switches for enabling the stator winding of the AC motor to be selectively connected in a star configuration or a delta configuration; and performing switching of all switches in the set substantially simultaneously and transforming the stator winding configuration of the AC motor from a star configuration to a delta configuration, thereby reducing current spikes in the winding.

[0017] In some exemplary embodiments, the set of electrical switches consists of five or six single-way switches or three two-way switches.

[0018] In some exemplary embodiments, the method further includes switching a stator winding configuration of the AC motor to a star configuration when the rotational speed synchronization of the first transmission member and the second transmission member is completed.

[0019] In some exemplary embodiments, the control unit of the above-mentioned electric power system can be configured to check the current stator winding configuration, and when the current stator winding configuration is a star configuration, perform a transformation of the stator winding configuration of the AC motor to a triangle configuration, and when the current stator winding configuration is a triangle configuration, maintain the stator winding configuration of the AC motor in a triangle configuration.

[0020] Furthermore, in some exemplary embodiments, the control unit is configured to control the AC motor in a scalar control mode during the rotational speed synchronization of the first transmission member and the second transmission member. This provides a simple and fast control mode that can be started instantly.

[0021] In addition, in some exemplary embodiments, the control unit is configured to control the AC motor in a vector control mode before and after the rotation speeds of the first transmission member and the second transmission member are synchronized, which provides an efficient and accurate control method for the AC motor.

[0022] The present disclosure also relates to a vehicle comprising an electric powertrain as described above.

[0023] Other features and advantages of the present invention will become apparent when studying the attached claims and the following description. Those skilled in the art realize that different features of the present disclosure may be combined to create other embodiments than those explicitly described above and below, without departing from the scope of the present disclosure. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] The present disclosure will be described in detail below with reference to the accompanying drawings, in which:

[0025] Figure 1 A vehicle having a transmission is schematically shown,

[0026] Figure 2a-2b Schematically shows a powertrain including a transmission of two different exemplary embodiments,

[0027] Figure 3a-3c The sequence of disengagement, neutral and engagement of the transmission mid-range is schematically shown.

[0028] Figure 4Schematically shows the speed profile of a gear during a synchronization process for upshifting,

[0029] Figure 5 Schematically shows the speed profile of a gear during a synchronization process for a downshift,

[0030] Figure 6 Schematically shows the stator windings arranged in a star configuration,

[0031] Figure 7 Schematically shows the stator windings arranged in a triangular configuration,

[0032] Figure 8 A further exemplary embodiment of a powertrain having a remote shift mechanism is schematically shown.

[0033] Fig. 9 Schematically shows a switching mechanism of another exemplary embodiment,

[0034] Figure 10a-10c Three exemplary embodiments of a method for performing a rotational synchronization are schematically shown,

[0035] Fig.11 The speed and phase voltage during upshift are schematically shown,

[0036] Fig.12 The speed and phase voltage during a downshift are schematically shown, and

[0037] Fig.13 A powertrain of a further exemplary embodiment is schematically shown, as well as further details of an inverter of an exemplary embodiment. DETAILED DESCRIPTION

[0038] Various aspects of the present disclosure will be described below in conjunction with the accompanying drawings to illustrate rather than limit the present disclosure, wherein like reference numerals represent like elements, and variations of the described aspects are not limited to the specifically illustrated embodiments, but can be applied to other variations of the present disclosure.

[0039] The present disclosure relates to a method for performing speed synchronization using a three-phase motor that can selectively operate in star and delta configurations. Thus, the synchronization time period can be further shortened.

[0040] To describe this method in this paper, first refer to Figure 1 , Figure 1An exemplary embodiment of a motor vehicle 1 having a propulsion power source 2, such as an internal combustion engine and / or an electric machine, is shown, drivingly connected to drive wheels 3 of the motor vehicle via a multi-speed transmission (i.e. a transmission having a plurality of discrete gears), wherein each gear has a unique transmission ratio. Obviously, the method according to the present disclosure is not limited to transmissions of front-wheel drive motor vehicles, or even to motor vehicles at all, but can be advantageously implemented in many other types of multi-speed transmissions and in many other types of applications.

[0041] Figure 2a A schematic diagram of a two-speed transmission 6 of a powertrain 4 of an automated manual transmission ATM is shown. The powertrain comprises an electric machine 2b as a propulsion source, a transmission 6 and a set of drive wheels 3. The transmission according to this exemplary embodiment has a main drive shaft 7, an input drive shaft 8, a first gear 9 with a first gear ratio, a second gear 10 with a second gear ratio.

[0042] The first gear 9 includes a first gear 31 which is rotationally fixed to the input shaft 8 and is constantly meshed with an idle second gear 32 which is arranged on the main shaft 7 and can rotate relative to the main shaft 7, and the second gear 10 includes a third gear 33 which is rotationally fixed to the input shaft 8 and is constantly meshed with an idle fourth gear 34 which is arranged on the main shaft 7 and can rotate relative to the main shaft 7.

[0043] The axially movable shift sleeve 18 is arranged on the main shaft 7 and is rotationally fixed to the main shaft 7 by a center piece (sleeve) 19. It includes a set of sleeve teeth, also called dog teeth or simply dogs, which can be bidirectionally axially shifted along the shift direction 25 by means of the switching actuator 12 to engage the corresponding teeth, dog teeth or simply dogs of any one of the associated second gear 32 and fourth gear 34 of the first constant mesh gear 9 and the second constant mesh gear 10, so as to selectively change the overall transmission ratio between the input shaft 8 and the main shaft 7.

[0044] In this context, an idler gear refers to a gear that is rotatable relative to the shaft on which it is located and which can be rotationally locked to the shaft via a shift sleeve 18 .

[0045] An electronic controller 20, such as a transmission controller, is used to control the operation of the transmission 6, in particular the operation of the shift actuator 12. Figure 2a As shown, the same controller 20 may also be configured to control the operation of an electric power converter 21 (e.g., an inverter), which is arranged to control the voltage and current provided to the motor 2b from the high voltage battery 22. Alternatively, a more distributed system may be used to control the power source 2b, wherein a separate electronic controller is provided to control the transmission 6, and another separate electronic controller is provided to control the electric power converter 21.

[0046] Obviously, the two-speed transmission shown is purely an example of many possible and optional layouts, and the methods and systems of the present disclosure can be applied to many other types of transmissions, such as transmissions with three speeds up to but not limited to nine speeds, or even transmissions with up to 25 speeds, for example, and the transmissions can be, for example, conventional and hybrid dual clutch transmissions (DCT and DCTH) or automated manual transmissions (AMT).

[0047] The transmission can also be implemented in many different types of powertrains, such as Figure 2b A hybrid powertrain having a combustion engine 2a and an electric machine 2b as power sources for propelling a vehicle is schematically shown in FIG. In this case, a friction clutch 5 can be provided for realizing a selective pure electric drive mode.

[0048] In summary, the method for performing rotational synchronization according to the present disclosure is not limited to transmissions of vehicles and may advantageously or alternatively be implemented or used in other types of transmissions.

[0049] For example, the high-level shifting process of a multi-speed transmission can be divided into the following stages.

[0050] 1. Torque reduction

[0051] 2. The sleeve enters the neutral position

[0052] 3. Speed ​​​​sync

[0053] 4. Sleeve engages with gear

[0054] 5. The torque increases slowly.

[0055] Figure 3a to Figure 3c Shows Figure 2a to Figure 2b Schematic example of a transmission upshift (upshift). For simplicity, Figure 3a to Figure 3c Only shown Figure 2a to Figure 2b A part of a transmission, wherein Figure 3a The transmission is shown with the first gear 9 engaged, ie with the shift sleeve 18 in a torque-transmitting connection with the idler second gear wheel 32 and the main shaft 7 .

[0056] Figure 3b 1 shows a state in which the shift sleeve 18 has been axially moved to the neutral state, that is, the transmission is disconnected from both the idle second gear 32 and the idle fourth gear 34. Since the idle second gear 32 and the idle fourth gear 34 rotate with each other through the first gear 31 and the third gear 33 and the input shaft 8, as shown in FIG. Figure 2a to Figure 2bAs shown, due to the different gear ratios of the first gear 9 and the second gear 10, the idle fourth gear 34 of the second gear 10 has a higher rotation speed than the idle second gear 34 of the second gear 9. Therefore, the rotation speed of the idle fourth gear 34 must be reduced before the shift sleeve 18 can engage with the fourth gear 34. The process in which the rotation speed of the fourth gear 34 becomes synchronized, that is, the process in which the rotation speed is adjusted to be the same as the rotation speed of the shift sleeve is called rotation speed synchronization, or simply synchronization.

[0057] In fact, at the end of the speed synchronization, the axial displacement of the displacement sleeve 18 for the rotational connection between the first transmission member and the second transmission member can be performed at an appropriate relative speed suitable for achieving the mutual rotational connection. Therefore, the relative speed can be zero or close to zero.

[0058] Synchronization is performed by applying a synchronizing torque to the fourth gear 34, usually indirectly via another transmission member, such as a shaft or a constantly meshing gear, which is rotationally connected to the fourth gear 34. Figure 2a In the exemplary transmission of , the synchronizing torque is supplied by the motor 2 b to the input shaft 8 , and is further supplied to the first gear 31 and the third gear 33 , and is finally further supplied to the second gear 32 and the fourth gear 34 .

[0059] When the rotational synchronization speed has been reached, that is, when the shift sleeve 18 and the fourth gear 34 rotate at approximately the same speed, the shift sleeve 18 is axially shifted so that the teeth of the dog clutch of the shift sleeve 18 can enter the grooves between adjacent dog teeth of the fourth gear 34, thereby providing a torque transmission connection between the fourth gear 34 and the main shaft 7.

[0060] Figure 3c The transmission is shown in a state in which the second gear 10 is engaged, ie the shift sleeve 18 is in a torque-transmitting connection with the idle fourth gearwheel 34 and the main shaft 7 .

[0061] Figure 4 A graph with time (seconds) on the X-axis and rotational speed (radians / second) on the Y-axis is shown, a first plot line 40 showing a schematic example of the rotational speed of the upcoming fourth gear 32 to be synchronized during an upshift, and a second plot line 41 showing the rotational speed of the shift sleeve 18 during said upshift.

[0062] In particular, during the duration t1 , the first gear 9 is still engaged, the power source provides propulsion torque, and the rotational speeds of both the shift sleeve 18 and the second gear wheel 32 increase, resulting in acceleration of the vehicle.

[0063] At the end of the time period t1, the transmission controller starts the shift to the second gear 10. Therefore, during the following second time period t2, the propulsion torque is first removed and then the first gear 9 is disengaged by moving the shift sleeve 18 axially away from the second gear 32, disengaging the dog teeth of the shift sleeve and the dog teeth of the second gear 32.

[0064] At this time, the rotation speed 41 of the shift sleeve 18 is still the same as the rotation speed of the second gear 32, and the rotation speed 40 of the upcoming (approaching) fourth gear 34 is higher. Figure 4 shown.

[0065] However, during the subsequent third time period t3 (also referred to as the synchronization time period), the synchronization torque is applied to the fourth gear 34, so that the rotation speed 40 of the upcoming fourth gear 34 is rapidly reduced. The synchronization torque is applied via Figure 2a and Figure 2b The motor 2b shown is applied.

[0066] At the end of the third time period t3, the rotational speed 40 of the fourth gear 34 has reached the rotational speed 41 of the shift sleeve 18, and during the fourth time period t4, the shift sleeve moves axially to rotationally connect and engage with the fourth gear 34, and the propulsion torque can be slowly increased, so that the vehicle can continue to accelerate during the subsequent fifth time period t5.

[0067] also, Figure 5 A corresponding diagram is shown comprising a first plot 42 illustrating a schematic example of the rotational speed of the upcoming second gear wheel 32 to be synchronized during a downshift and a second plot 43 illustrating the rotational speed of the shift sleeve 18 during said downshift.

[0068] Specifically, during the first time period t6, the second gear 10 is still engaged, providing no propulsion torque, and the rotational speeds of both the shift sleeve 18 and the fourth gear wheel 34 are reduced, resulting in a deceleration of the vehicle.

[0069] At the end of the first time period t6, the transmission controller 20 starts downshifting to the first gear 9. Therefore, during the following second time period t7, the second gear 10 is disengaged by axially moving the shift sleeve, whereby the dog teeth of the shift sleeve 18 are disengaged from the fourth gear wheel 34.

[0070] At this time, the rotation speed 43 of the shift sleeve 18 is still the same as the rotation speed of the fourth gear 34, and the rotation speed 42 of the upcoming second gear 32 is lower, such as Figure 5 shown.

[0071] However, during the subsequent third time period t8, the synchronizing torque is applied to the second gear 32, so that the rotation speed of the upcoming second gear 32 increases rapidly. Figure 2a and Figure 2b The motor 2b shown is applied.

[0072] At the end of the third time period t3, the rotational speed 42 of the second gear 32 has reached the rotational speed 43 of the shift sleeve 18. The transmission controller 20 may preferably be arranged to control the synchronization process during the third time period t8 (including the starting point of the third time period t8) so that at the end of the third time period t8, the relative rotational position of the shift sleeve 18 and the second gear 32 enables the shift sleeve 18 to immediately perform an axial shifting movement without interference between the dog teeth of the shift sleeve 18 and the corresponding dog teeth of the second gear 32.

[0073] During the fourth time period t9, the shift sleeve 18 is axially moved to rotationally connect and engage with the second gear 32, and the vehicle can continue to decelerate during the subsequent fifth time period t10.

[0074] refer to Figure 6 , which schematically shows Figure 2a An exemplary embodiment of the electrical portion of a powertrain 4 includes: a high-voltage battery 22, which is connected to a power converter 21 in the form of an inverter via a DC link 24; three windings W1, W2, W3 of a three-phase AC motor 2b (such as an induction motor or a permanent magnet synchronous motor); and a switching mechanism 50 that selectively connects the stator windings W1-W3 of the AC motor 2b in a star configuration or a delta configuration.

[0075] Each winding W1-W3 has a first terminal and a second terminal. The three phases L1, L2, L3 leave the inverter 21 and are each connected to one of the first terminals of the windings W1-W3.

[0076] The switching mechanism 50 includes a first group of switches, the first group of switches including first, second and single-way third switches S1, S2, S3, wherein the first switch S1, when set to a closed state, realizes the connection between the first terminal of the first winding W1 and the second terminal of the second winding W2, wherein the second switch S2, when set to a closed state, connects the first terminal of the second winding W2 with the second terminal of the third winding W3, and wherein the third switch S3, when set to a closed state, connects the first terminal of the third winding W3 with the second terminal of the first winding W1.

[0077] The switching mechanism 50 further includes a second set of switches, which includes a fourth single-way switch S4 and a fifth single-way switch S5. When the fourth single-way switch S4 and the fifth single-way switch S5 are set to a closed state, they jointly connect the second terminals of all three windings W1-W3.

[0078] Therefore, if Figure 6 As shown, when the first set of switches S1-S3 is set to an open state, and the second set of switches S4-S5 is set to a closed state, the stator windings W1-W3 of the AC motor 2b are connected in a star configuration.

[0079] Similarly, if Figure 7 As shown, when the first set of switches S1-S3 is set to a closed state, and the second set of switches S4-S5 is set to an open state, the stator windings W1-W3 of the AC motor 2b are connected in a delta configuration.

[0080] The switching mechanism 50 may be provided integrally with the motor 2b or may be provided away from the motor 2b. Figure 8 Another exemplary embodiment of the electrical part of the powertrain 4 is schematically shown, in which the switching mechanism 50 is arranged away from the motor 2b. In addition, in this exemplary embodiment, the second set of switches includes three separate single-way switches S4-S6, which together realize the connection of the second terminals of all three windings W1-W3 when they are set to the closed state.

[0081] According to the reference Fig. 9 Another exemplary embodiment of the switching mechanism 50, the switching mechanism 50 includes three two-way switches S1, S2, S3, each of which has three poles and two switch states 1 and 2. When each of the switches S1, S2, S3 is set to the first state 1, the stator windings W1-W3 of the AC motor 2b are connected in a delta configuration, and when each of the switches S1, S2, S3 is set to the second state 2, the stator windings W1-W3 of the AC motor 2b are connected in a star configuration.

[0082] Therefore, the method and system according to the contents of the present disclosure may include: providing a group of electrical switches S1-S6 for the switching mechanism to enable the stator windings W1-W3 of the AC motor 2b to be selectively connected into a star configuration or a delta configuration; and when the stator winding structure of the AC motor 2b is changed from a star configuration to a delta configuration, all switches S1-S6 in the group are switched substantially simultaneously.

[0083] Furthermore, as described above, the set of electrical switches S1-S6 is composed of, for example, five or six single-way switches or three two-way switches, or the like.

[0084] Furthermore, it may be advantageous to coordinate the operation of the switching mechanism 50 for converting the stator winding configuration of the AC motor 2b from the star configuration to the delta configuration with the operating point of the AC motor 2b so as to ensure the discharge of the phase inductance voltage of the AC motor 2b before triggering the operation of the switching mechanism 50. After the power supply from the inverter 21 to the motor 2b is stopped, the phase voltage V P It will decay rapidly as the inductive voltage of the motor winding is discharged (eg via a freewheeling diode in the inverter).

[0085] Refer to the following Fig.10a and Figure 2a or Figure 2b A first exemplary embodiment of a method for performing a speed synchronization is described with reference to any one of the above, wherein, for example, a gear shift from the first gear 9 to the second gear 10 or vice versa is performed.

[0086] The method involves synchronizing the speed of first transmission members 32, 34 having a first initial speed with the speed of second transmission member 18 having a second initial speed during a gear shift in a stepped-speed transmission 6 of a powertrain 4, using a three-phase AC motor 2B rotationally connected to first transmission members 32, 34, wherein the powertrain 4 has a switching mechanism 50 that enables the stator windings W1-W3 of the AC motor to be selectively connected in a star configuration or a delta configuration.

[0087] Specifically, the method includes a first step S10 of obtaining a command that a gear shift should be performed or determining that a gear shift should be performed. The method also includes a second step S20 of switching the stator winding configuration of the AC motor 2b to a triangular configuration, or ensuring that the stator winding configuration of the AC motor 2b is in a triangular configuration. Finally, the method includes a third step S30 of controlling the operation of the AC motor 2b so as to achieve speed synchronization of the first transmission member 32, 34 and the second transmission member 18.

[0088] In other words, the second step S20 therefore consists in controlling the stator winding configuration of the alternating current motor 2b so as to place it in a delta configuration.

[0089] Refer to the following Figure 2a or 2b and Figure 8 , to illustrate a first exemplary embodiment of an electric power system 4 for a vehicle. Specifically, the electric powertrain system includes an electric storage system 22, an inverter 21, a three-phase AC electric propulsion motor 2b, which is drivingly connected to the wheels 3 of the vehicle through a stepped gear transmission 6 having a first transmission member 32, 34 and a second transmission member 18, wherein the AC motor 2b is rotationally connected to the first transmission member 32, 34.

[0090] The electric power system also includes: a switching mechanism 50 having a set of electrical switches S1-S6, the electrical switches S1-S6 are used to enable the stator windings W1-W3 of the AC motor 2b to be selectively connected in a star configuration or a triangle configuration; and a control unit 20, which is used to control the operation of the switching mechanism 50, wherein the control unit 20 is configured to: obtain a command that a gear shift should be performed or determine that a gear shift should be performed; switch the stator winding structure of the AC motor 2b to a triangle configuration, or ensure that the stator winding structure of the AC motor 2b is in a triangle configuration; and control the operation of the AC motor 2b to achieve speed synchronization of the first transmission component 32, 34 and the second transmission component 18.

[0091] It is known from documents such as US 5,675,222 that an electric motor with switchable windings can be operated in a star connection at lower travel speeds and in a delta connection at higher travel speeds in order to utilize the higher torque available in the star connection and the higher maximum speed available in the delta connection.

[0092] However, it is not known from this that a delta connection can also be used advantageously during the synchronization phase in order to achieve faster synchronization times.

[0093] Please refer to the following Fig.11 and Fig.12 Advantages of performing speed synchronization during upshifting and downshifting while setting the stator winding configuration of the AC motor 2b to a delta configuration are described. Fig.11 shows a depiction similar to Figure 4 The added file picture, Fig.12 shows a depiction similar to Figure 5 Diagram of downshift.

[0094] Furthermore, in order to illustrate the advantages of a delta connection during the synchronization phase, the rotational speed of an upcoming gear (such as, for example, the fourth gear 32) is shown when a star connection is used during the entire shift sequence, and as a symbol of the prior art solution, the rotational speed of the same upcoming gear is shown when a delta connection is used during the synchronization phase of the shift sequence.

[0095] therefore, Fig.11 A long dashed line 60 is shown which illustrates the rotational speed of the upcoming gear during an upshift when a star connection is used during the entire shift sequence. Fig.11 Further shown is a short dashed line 61, which shows that during the synchronization phase t synch_delta A delta connection is used during the synchronization phase, and in the synch_delta Before and after using a star connection, the speed of the upcoming gear during an upshift in this case.

[0096] also, Fig.11 A dashed line 62 is shown which shows the phase voltage, ie, the voltage level, on each of the windings W1-W3 when a star connection is used during the entire shift sequence. Fig.11 A solid line 63 is shown, which shows that when in the synchronization phase t synch_delta The phase voltage during the delta connection and during the synchronization phase t synch_delta Phase voltages before and after using star connection.

[0097] In other words, the rotational speeds 60, 61 and the associated phase voltages 62, 63 of the incoming gears of the two different systems are included in Fig.11 , to illustrate the difference in shifting time between the two systems.

[0098] First, the rotational speed 60 of the upcoming gear and the associated phase voltage 62 when the star connection is used during the entire shift sequence are discussed. In the time before time point T1, the first gear 9 is still engaged, the electric power provides the propulsion torque, and the rotational speeds of the shift sleeve 18 and the second gear 32 are increased, resulting in the vehicle accelerating.

[0099] The maximum phase voltage is, for example, 230 V, derived from, for example, a maximum supply voltage of 400 V from an inverter, where the phase voltage V P equal: Where V L is the line voltage, ie the voltage level across the supply lines L1 - L3 .

[0100] Phase voltage V P and line voltage V L like Figure 6 as shown in .

[0101] At time point T1, the transmission controller starts the shift to the second gear 10. Thus, the propulsion torque is removed and the first gear 9 is disengaged by moving the shift sleeve 18 axially away from the second gear 32, thereby disengaging the dog teeth of the shift sleeve and the dog teeth of the second gear 32. During the time between T1 and T2, the inverter switches remain open and the phase voltage is therefore zero.

[0102] At the time T2 , the rotational synchronization of the fourth gear 34 is initiated in order to reduce the rotational speed 60 of the fourth gear 34 from ω1 to the rotational speed ω2 of the shift sleeve 18 .

[0103] At the synchronous time phase t synch_starScalar voltage control is applied during this process. This type of control usually involves controlling the speed of the motor by varying the frequency of the AC supply voltage, and wherein the relationship between the voltage "V" and the frequency "f" is kept constant over the motor speed range, i.e. a constant V / f ratio, to provide a constant and desired level of stator flux linkage. The frequency "f" is set according to the desired speed, and the magnitude of the voltage "V" is adjusted to keep the ratio between them constant. This method usually uses an open loop control method without any feedback of the motor parameters or its rotational position.

[0104] However, at time point T2, the speed of the upcoming fourth gear 34 is relatively high, but due to the phase voltage V P It cannot increase to more than 230V, so the desired V / f ratio cannot be provided because the stator voltage is limited to the rated value. In other words, the motor operates in the field weakening region until time point T3, at which time point T3 the desired V / f ratio can be provided. During the operation in the field weakening region between time point T2 and time point T3, the phase voltage V P Keep 230V.

[0105] However, from time point T3 to time point T5, the phase voltage V P It gradually decreases as the frequency "f" (ie the rotation speed of the motor 2b) decreases in order to maintain a constant and desired V / f ratio.

[0106] At the time T5 , the rotational speed 60 of the oncoming gear is synchronized with the rotational speed of the shift sleeve 18 , so that the axial movement of the shift sleeve can be connected in rotation and engaged with the fourth gear wheel 34 .

[0107] During the time between T5 and T7, the inverter switches remain open and thus the phase voltage is zero.

[0108] At time T7, the engagement is complete and the propulsion torque can be ramped up so that the vehicle can continue to accelerate.

[0109] Now, for comparison, the rotational speed 61 of the oncoming gear and the associated phase voltage 63 when a delta connection is used during the synchronization phase, i.e. between time points T2-T4, are discussed. In the time before time point T1, the first gear 9 is still engaged, the motor 2b is star-connected and provides propulsion torque, and the rotational speeds of the shift sleeve 18 and the second gear 32 both increase, resulting in acceleration of the vehicle.

[0110] The maximum phase voltage is, for example, 230 V, resulting from a maximum supply voltage of, for example, 400 V from an inverter.

[0111] At time point T1, the transmission controller initiates the gear change as described above. Thus, the propulsion torque is removed, the first gear 9 is subsequently disengaged, and during the time between T1 and T2, the inverter switches remain open, so that the phase voltage is zero.

[0112] In addition, the switching mechanism 50 is activated to switch the stator winding configuration from star winding to delta winding. As a result, the maximum phase voltage is, for example, 400 V (derived from, for example, a 400 V power supply voltage from an inverter), where the phase voltage V P Equal to the line voltage V during the triangle connection L .

[0113] At the time point T2 , the rotational synchronization of the fourth gear 34 is started to reduce the rotational speed 61 of the fourth gear 34 from ω1 to the rotational speed ω2 of the shift sleeve 18 .

[0114] As described above, during the period of synchronization of the rotational speeds of the first transmission member and the second transmission member, that is, during the synchronization time period t synch_delta During this period, the AC motor is controlled in scalar control mode and, due to the increased maximum voltage level in the delta connection, the desired V / f ratio can be provided during the entire synchronization phase from time point T2 to T4. In other words, the motor 2b is not operated in the field weakening region during the synchronization period. On the contrary, during the entire synchronization phase from time point T2 to T4, the phase voltage V P It gradually decreases as the frequency "f" decreases to maintain a constant and desired V / f ratio.

[0115] As shown by the different slopes of the speeds 60, 61 of the oncoming gear, the rotational acceleration provided by the delta connection is higher than that provided by the star connection because, unlike the star-connected windings, the delta-connected stator windings do not enter the field weakening region and the optimal V / f ratio can be maintained.

[0116] The synchronization time period t extending between time points T2-T4 synch_delta is less than the synchronization time period t extending between time points T2-T5 synch_star In other words, when the motor switches from star connection to delta connection during the synchronization cycle, the entire shifting process can be performed faster.

[0117] The AC motor is controlled in a vector control mode before and after the rotational speeds of the first transmission member and the second transmission member are synchronized.

[0118] Refer to the following Fig.12 , illustrating the advantages of a delta connection during synchronization in a downshift sequence, which corresponds to a downshift of the vehicle during coasting, ie during vehicle deceleration, without any accelerator or brake pedal actuation.

[0119] Fig.12 A long dashed line 60 is shown which illustrates the rotational speed of an upcoming gear (such as the second gear 32 ) during an upshift when a star connection is used during the entire shift sequence. Fig.12 Also shown is a short dashed line 61, which shows that when in the synchronization phase t synch_delta A delta connection is used during the synchronization phase, and in the synch_delta Before and after the rotation speed of the upcoming gear during upshifting when using a star connection.

[0120] also, Fig.12 A dashed line 62 is shown which shows the phase voltage when a star connection is used during the entire shift sequence, and a solid line 63 is shown which shows the phase voltage when in the synchronization phase t of the shift sequence. synch_delta The phase voltage during the delta connection, as well as during the synchronization phase t synch_delta Phase voltages before and after using star connection.

[0121] First, the rotational speed 60 of the upcoming gear and the associated phase voltage 62 when the star connection is used during the entire shift sequence are discussed. During the time before time point T1, the second gear 10 is still engaged, the inverter provides voltage and the back electromotive force of the motor generates a voltage level. Corresponding to the deceleration of the vehicle, the rotational speeds of the shift sleeve 18 and the fourth gear 34 are both reduced.

[0122] At time T1, the transmission controller initiates a downshift, corresponding to, for example, Figure 2a 10 to the first gear 9 in the embodiment of . Therefore, the shift sleeve 18 is axially moved away from the fourth gear 34, so that the dog teeth of the shift sleeve 18 are disengaged from the dog teeth of the fourth gear 32, so that the second gear 10 is disengaged.

[0123] At the time point T2 , the rotational synchronization of the second gear 32 is started to reduce the rotational speed 60 of the second gear 32 from ω1 to the rotational speed ω2 of the shift sleeve 18 .

[0124] At the synchronous time phase t synch_star However, when reaching the time point T3, the speed of the upcoming second gear 32 is relatively high, but due to the phase voltage V P It cannot increase to more than 230V, so the desired V / f ratio cannot be maintained because the stator voltage is limited to the rated value. In other words, the motor enters the field weakening region until time point T5, at which time the synchronization ends. During the field weakening region operation between time point T3 and time point T5, the phase voltage V P Keep 230V.

[0125] At the time T5 , the rotational speed 60 of the oncoming gear is synchronized with the rotational speed of the shift sleeve 18 , so that the axial movement of the shift sleeve is enabled to be connected in rotation and engage with the second gear 32 .

[0126] At time point T7, engagement is complete and vehicle deceleration can continue, but without the higher back EMF voltage generated by motor 2b.

[0127] Now, for comparison, the rotation speed 61 of the upcoming gear and the associated phase voltage 63 when a delta connection is used during the synchronization phase, i.e. between time points T2-T4, are discussed. In the time before time point T1, the second gear 10 is still engaged, the motor 2b is in a star connection and generates a certain back electromotive force voltage, and the rotation speed of the shift sleeve 18 and the fourth gear 34 is slowly reduced, thereby causing the vehicle to slow down.

[0128] At time T1, the transmission controller initiates a downshift as described above. As a result, the second gear 10 is disengaged.

[0129] In addition, the switching mechanism 50 is activated to switch the stator winding configuration from star winding to delta winding. As a result, the maximum phase voltage is, for example, 400 V, which is derived from, for example, a 400 V power supply voltage from an inverter, where the phase voltage V P Equal to the line voltage V during the triangle connection L .

[0130] The control unit may be configured to control the switches of the inverter to remain in an open state during operation of the switching mechanism for converting the stator winding configuration of the AC motor from a star configuration to a delta configuration.

[0131] At the time point T2 , the rotation synchronization of the second gear 32 is started to increase the rotation speed 61 of the second gear 32 from ω1 to the rotation speed ω2 of the shift sleeve 18 .

[0132] As described above, during the period of synchronization of the rotational speeds of the first transmission member and the second transmission member, that is, during the synchronization time period t synch_delta During this period, the AC motor is controlled in scalar control mode and, due to the increased maximum voltage level in the delta connection, the desired V / f ratio can be provided during the entire synchronization phase from time point T2 to T4. In other words, the motor 2b is not operated in the field weakening region during the synchronization period. On the contrary, during the entire synchronization phase from time point T2 to T4, the phase voltage V P It gradually increases as the frequency "f" increases to maintain a constant and desired V / f ratio.

[0133] As shown by the different slopes of the speeds 60, 61 of the oncoming gear, the rotational acceleration provided by the delta connection is higher than that of the star connection because, unlike the star-connected windings, the delta-connected stator windings do not enter the field weakening region and the optimal V / f ratio can be maintained.

[0134] The synchronization time period t extending between time points T2-T4 synch_delta is less than the synchronization time period t extending between time points T2-T5 synch_star In other words, when the motor switches from star connection to delta connection during the synchronization cycle, the entire shifting process can be performed faster.

[0135] The AC motor is controlled in a vector control mode before and after the rotational speeds of the first transmission member and the second transmission member are synchronized.

[0136] Referring to another exemplary embodiment showing the method Fig.10b The second step S20 of switching the stator winding configuration of the AC motor 2b to a triangle configuration or ensuring that the stator winding configuration of the AC motor 2b is in a triangle configuration may be configured to include a first sub-step S20a of checking the current stator winding configuration, and a second sub-step S20b of switching the stator winding configuration of the AC motor to a triangle configuration when the current stator winding configuration is a star configuration. However, when it is determined during the first sub-step S20a that the current stator winding configuration is a triangle configuration, the AC motor 2b should remain in the triangle configuration, and the method then directly proceeds to the third step S30, i.e., controlling the operation of the AC motor 2b to achieve speed synchronization of the first transmission member 32, 34 and the second transmission member 18.

[0137] According to yet another exemplary embodiment, Fig.10c As schematically shown in FIG. 1 , the method may include a fourth step S40 of switching the stator winding configuration of the AC motor 2b to a star configuration when the rotational speed synchronization of the first transmission member and the second transmission member is completed.

[0138] Fig.13 An exemplary embodiment of a more detailed version of the electrical part of the powertrain 4 is shown in FIG. Fig.13 An exemplary embodiment of an inverter 21 is included, where the inverter 21 includes six inverter switches Si1-Si6, wherein two inverter switches Si1-Si6 are associated with three bridge arms 71, 72, 73. Each switch Si1-Si6 also includes a bypass diode D1-D6 for passing current spikes generated by inductive components through the switch Si1-Si6, thereby avoiding potentially damaging voltage levels.

[0139] It is to be understood that the above description is merely exemplary in nature and is not intended to limit the present disclosure, its application, or its use. For example, the present invention is not limited to the example values ​​of the maximum phase voltage or line voltage provided by the inverter described herein. In addition, although specific examples have been described in the specification and shown in the drawings, it will be understood by those skilled in the art that various changes may be made and elements in these examples may be replaced with equivalents without departing from the scope of the present disclosure defined in the claims. In addition, modifications may be made to adapt specific circumstances or materials to the teachings of the present disclosure without departing from the basic scope of the present disclosure.

[0140] Therefore, it is not intended that the present disclosure be limited to the specific examples disclosed as the best mode currently conceived for carrying out the teachings of the present disclosure and illustrated by the drawings and described in the specification, but rather the scope of the present disclosure will include any embodiment falling within the scope of the foregoing description and the appended claims. The reference signs mentioned in the claims shall not be construed as limiting the scope of the subject matter protected by the claims, and their only function is to make the claims easier to understand.

Claims

1. A method for performing speed synchronization, the method being used for performing speed synchronization of a first transmission member (32, 34) having a first initial speed and a second transmission member (18) having a second initial speed during a gear shift in a step-type gear transmission (6) of a powertrain (4), using a three-phase AC motor (2b) capable of being rotationally connected to the first transmission member (32, 34), the powertrain (4) having a switching mechanism (50), the switching mechanism (50) enabling the stator windings (W1-W3) of the AC motor (2b) to be selectively connected in a star configuration or a delta configuration, the method comprising: Obtaining a command that a gear shift should be executed or determining that a gear shift should be executed; Converting the stator winding structure of the AC motor (2b) into a triangular configuration, or ensuring that the stator winding structure of the AC motor (2b) is in a triangular configuration; as well as The operation of the AC motor (2b) is controlled to achieve rotational speed synchronization of the first transmission member (32, 34) and the second transmission member (18).

2. The method according to claim 1, wherein: The step of converting the stator winding structure of the AC motor (2b) into a triangular configuration or ensuring that the stator winding structure of the AC motor (2b) is in a triangular configuration comprises: Check the current stator winding configuration; and When the current stator winding configuration is a star configuration, the stator winding configuration of the AC motor (2b) is converted to a triangle configuration, and when the current stator winding configuration is a triangle configuration, the stator winding configuration of the AC motor (2b) is maintained in a triangle configuration.

3. The method according to claim 1, wherein: During the synchronization of the rotational speeds of the first transmission member (32, 34) and the second transmission member (18), the AC motor (2b) is controlled in a scalar control mode.

4. The method according to claim 1, wherein: The AC motor (2b) is controlled in a vector control mode before and after the rotational speeds of the first transmission member (32, 34) and the second transmission member (18) are synchronized.

5. The method according to claim 1, wherein: When the speed synchronization is completed, the first transmission member (32, 34) and the second transmission member (18) rotate at an appropriate relative speed suitable for achieving mutual rotational connection.

6. The method according to claim 1, comprising: During operation of the switching mechanism (50) for changing the stator winding configuration of the AC motor (2b) from a star configuration to a delta configuration, switches (Si1-Si6) of the control inverter (21) are kept in an open state.

7. The method according to claim 1, comprising: The operation of the switching mechanism (50) for transforming the stator winding configuration of the AC motor (2b) from a star configuration to a delta configuration is coordinated with the operating point of the AC motor (2b) to ensure the discharge of the phase inductance voltage of the AC motor (2b) before triggering the operation of the switching mechanism (50).

8. The method according to claim 1, comprising: A set of electrical switches (S1-S6) is provided for the switching mechanism (50) to selectively connect the stator windings (W1-W3) of the AC motor (2b) in a star configuration or a delta configuration; as well as When the stator winding configuration of the AC motor (2b) is changed from a star configuration to a delta configuration, all switches (S1-S6) in the set of switches are changed simultaneously.

9. The method according to claim 8, wherein: The set of electrical switches (S1-S6) consists of five or six single-way switches or three double-way switches.

10. The method according to any one of the preceding claims, further comprising: When the rotation speed synchronization of the first transmission member (32, 34) and the second transmission member (18) is completed, the stator winding configuration of the AC motor (2b) is changed to a star configuration.

11. An electric power transmission system for a vehicle, the electric power transmission system comprising: Electrical storage systems (22); Inverter (21); a three-phase AC electric propulsion motor (2b) drivingly connected to the wheels (3) of the vehicle (1) via a stepped transmission (6) having a first transmission member (32, 34) and a second transmission member (18), wherein the AC motor (2b) is rotatably connected to the first transmission member (32, 34); Characterized in that the electric power transmission system also includes: a switching mechanism (50) having a set of electrical switches (S1-S6) for enabling the stator windings (W1-W3) of the AC motor (2b) to be selectively connected in a star configuration or a delta configuration; and A control unit (20) for controlling the operation of the switching mechanism (50), wherein the control unit (20) is configured to: - Obtaining a command that a gear shift should be performed or determining that a gear shift should be performed; - transforming the stator winding configuration of the AC motor (2b) into a triangular configuration, or ensuring that the stator winding configuration of the AC motor (2b) is in a triangular configuration; and then - Controlling the operation of the AC motor (2b) to achieve rotational speed synchronization of the first transmission member and the second transmission member.

12. The electric power transmission system for a vehicle according to claim 11, wherein: The control unit (20) is also configured to check a current stator winding configuration, and when the current stator winding configuration is a star configuration, perform a conversion of the stator winding configuration of the AC motor (2b) to a delta configuration, and when the current stator winding configuration is a delta configuration, maintain the delta configuration.

13. The electric power transmission system for a vehicle according to claim 11, wherein: The control unit (20) is configured to control the AC motor (2b) in a scalar control mode during rotational speed synchronization of the first transmission member (32, 34) and the second transmission member (18).

14. An electric powertrain system for a vehicle according to any one of claims 11 to 13, wherein: The control unit (20) is configured to control the AC motor (2b) in a vector control mode before and after the rotation speeds of the first transmission member (32, 34) and the second transmission member (18) are synchronized.

15. A vehicle comprising an electric drivetrain according to any one of the preceding claims 11-14.

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