A three-phase connection structure of a permanent magnet synchronous motor for electric vehicles

Abstract

The present invention discloses a three-phase connection structure of a permanent magnet synchronous motor for electric vehicles. When starting in the first gear, four winding units in each phase winding are connected in series in sequence through three electric control switches; when accelerating in the second gear, four winding units in each phase winding are connected in series in pairs into two groups, namely the first winding group and the second winding group, and the first winding group in the three-phase winding is connected in parallel, and the second winding group is connected in parallel; when running at high speed in the third gear, each winding unit in each phase winding constitutes a branch separately, and all the first winding units in the three-phase winding are connected in parallel, all the second winding units are connected in parallel, all the third winding units are connected in parallel, and all the fourth winding units are connected in parallel. The three-phase connection structure of the permanent magnet synchronous motor for electric vehicles provided by the present invention adjusts the three-gear connection by series-parallel conversion, and constructs multiple independent Y-type parallel branches to ensure the three-phase balance of the motor and improve the safety of the motor operation.

Description

Technical Field

[0001] The invention relates to the technical field of electric motors for electric vehicles, and in particular to a three-phase connection structure of a permanent magnet synchronous motor for electric vehicles. Background Art

[0002] The technical requirements of electric vehicles for the speed and torque of motors are: high torque and low speed are required when starting, low torque requirements but high speed are required during normal driving, and a wide range is required between the lowest speed and the highest speed. After the rated speed, the permanent magnet synchronous motor used in ordinary electric vehicles adopts weak magnetic control to increase the speed to avoid excessive back electromotive force, exceeding the bus voltage of the on-board battery, and preventing the motor controller from crashing. The first, second, and third gears are formed by winding switching. In the existing wiring structure, when starting in the first gear, the four phase winding units in each phase winding are all connected in series. When accelerating in the second gear, the four phase winding units in each phase winding are connected in series in two groups, and then the two groups connected in series are connected in parallel to form a Y-shaped connection. When running at high speed in the third gear, the four phase winding units in each phase winding are all connected in parallel to form a Y-shaped connection. This wiring method is easy to cause the three phases of the motor to be unbalanced and burned when a phase winding is accidentally disconnected due to a fault, so it is urgent to improve it. Summary of the invention

[0003] The purpose of the present invention is to provide a three-phase wiring structure of a permanent magnet synchronous motor for an electric vehicle, which adjusts the three-speed wiring of the motor by series and parallel conversion, and constructs a plurality of independent Y-type parallel branches in the second and third gears, which do not affect each other, ensure the three-phase balance of the motor, and can smoothly control the on and off of the three-phase winding, thereby improving the safety of the motor operation.

[0004] To achieve the above object, the present invention provides the following solutions:

[0005] A three-phase wiring structure of a permanent magnet synchronous motor for an electric vehicle, the structure comprising a permanent magnet synchronous motor and a controller, wherein each phase of the stator winding of the three-phase stator winding of the permanent magnet synchronous motor is composed of four winding units with the same total number of turns, the same winding wire diameter, and the same total cross-sectional area of ​​the winding wire, which are winding unit No. 1, winding unit No. 2, winding unit No. 3, and winding unit No. 4, respectively, and an insulating layer is provided between the coils of each phase winding unit, and a plurality of electric control switches are used to implement series, parallel, and series-parallel mixed connection operation modes for four winding units in each phase winding to form a gear shift, and a current sensor is connected in series next to each electric control switch, and a plurality of the electric control switches and the current sensors are electrically connected to the controller respectively;

[0006] When starting in the first gear, the four winding units in each phase winding are connected in series in sequence through three electronically controlled switches; when accelerating in the second gear, the four winding units in each phase winding are connected in series in pairs into two groups, namely the first winding group and the second winding group. The first winding group of the three-phase winding is connected in parallel, and the second winding group is connected in parallel to form two independent Y-type parallel branches; when running at high speed in the third gear, each winding unit in each phase winding constitutes a branch separately, all No. 1 winding units in the three-phase winding are connected in parallel, all No. 2 winding units are connected in parallel, all No. 3 winding units are connected in parallel, and all No. 4 winding units are connected in parallel to form four independent Y-type parallel branches.

[0007] Optionally, the electronically controlled switches are divided into three identical groups, each group of electronically controlled switches includes nine electronically controlled switches, namely a first electronically controlled switch, a second electronically controlled switch, a third electronically controlled switch, a fourth electronically controlled switch, a fifth electronically controlled switch, a sixth electronically controlled switch, a seventh electronically controlled switch, an eighth electronically controlled switch and a ninth electronically controlled switch.

[0008] Optionally, when the first gear is started, a first control switch is connected in series between the No. 1 winding unit and the No. 2 winding unit in each phase winding, a second control switch is connected in series between the No. 2 winding unit and the No. 3 winding unit, and a third control switch is connected in series between the No. 3 winding unit and the No. 4 winding unit. The first electronically controlled switch, the second electronically controlled switch and the third electronically controlled switch in the three-phase winding are respectively electrically connected to the electric shift controller.

[0009] Optionally, when the second gear accelerates, the first group of windings in each phase winding is composed of a No. 1 winding unit and a No. 2 winding unit connected in series, and the second group of windings is composed of a No. 2 winding unit and a No. 4 winding unit connected in series. A first electrically-controlled switch is connected in series between the No. 1 winding unit and the No. 2 winding unit, a third electrically-controlled switch is connected in series between the No. 2 winding unit and the No. 4 winding unit, a fifth electrically-controlled switch is connected between the No. 1 winding unit and the No. 2 winding unit, an eighth electrically-controlled switch is connected to the end of the No. 2 winding unit, and the three eighth electrically-controlled switches in the three-phase winding are connected together, and the first electrically-controlled switch, the third electrically-controlled switch, the fifth electrically-controlled switch and the eighth electrically-controlled switch in the three-phase winding are respectively electrically connected to the electric shift controller.

[0010] Optionally, when the third gear is running at high speed, the head end of the No. 1 winding unit in each phase winding is connected to the head end of the No. 2 winding unit, the head end of the No. 3 winding unit, and the head end of the No. 4 winding unit through the fourth electronically controlled switch, the fifth winding switch, and the sixth winding switch respectively, the end of the No. 1 winding unit in each phase winding is connected to the seventh electronically controlled switch, and the three seventh electronically controlled switches in the three-phase winding are connected together; the end of the No. 2 winding unit in each phase winding is connected to the eighth electronically controlled switch, and the three eighth electronically controlled switches in the three-phase winding are connected together; the end of the No. 3 winding unit in each phase winding is connected to the ninth electronically controlled switch, the three ninth electronically controlled switches in the three-phase winding are connected together, and the ends of all the No. 4 winding units in the three-phase winding are connected together; the fourth electronically controlled switch, the fifth electronically controlled switch, the sixth electronically controlled switch, the seventh electronically controlled switch, the eighth electronically controlled switch and the ninth electronically controlled switch in the three-phase winding are respectively electrically connected to the electric shift controller.

[0011] Optionally, the electronically controlled switch is an AC contactor, a DC relay, a solid-state relay, an IGBT or a MOS field effect transistor.

[0012] According to the specific embodiments provided by the present invention, the present invention discloses the following technical effects: the three-phase wiring structure of the permanent magnet synchronous motor for electric vehicles provided by the present invention uses multiple electronically controlled switches to convert the windings of the permanent magnet synchronous motor for electric vehicles into a three-speed motor through series and parallel conversion, and the speed can be increased without weak magnetic control; the on and off of the electronically controlled switch is controlled by an electric shift controller, and the winding wiring method is switched to form the first gear, the second gear, and the third gear to increase the motor speed. Compared with the existing wiring structure, the wiring structure of the present application does not change in the first gear, but in the second gear or third gear, two or four independent Y-shaped parallel branches are formed by adjusting the positions of multiple electronically controlled switches and adjusting the lines, thereby avoiding mutual influence between multiple branches. Even if a Y-shaped parallel branch is broken due to a fault, it does not affect the operation of other Y-shaped parallel branches, thereby ensuring the three-phase balance of the motor. In addition, in actual wiring, compared with the traditional connection method, three fewer connecting wires are required, and the connection method is simple. When an electronically controlled switch in each phase winding fails and is not closed or disconnected according to a predetermined instruction, the electric shift controller can disconnect other electronically controlled switches corresponding to the electronically controlled switch at the same time, so that the three-phase winding of the motor is still in a balanced state, increasing the redundancy of the three-speed permanent magnet synchronous motor for electric vehicles and improving the safety performance of electric vehicles. Compared with the traditional permanent magnet synchronous three-phase motor weak magnetic speed increase control method, if the weak magnetic control program fails and the weak magnetic control fails, the motor is reversely dragged by the vehicle inertia to generate electricity and brake, causing the electric vehicle to brake immediately, thereby causing the risk of rollover. The present invention can eliminate or reduce the use of weak magnetic control, and eliminates or reduces the possibility of the above-mentioned risks caused by weak magnetic control failure. In addition, even if the problem of weak magnetic control failure occurs in the high-speed weak magnetic area, the present invention can also disconnect 9 electronic control switches at the same time to prevent the motor from being reverse-dragged by the inertia of the car to generate electricity and brake, causing the electric car to brake immediately and cause the risk of rollover. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0014] Figure 1 It is a first gear wiring structure of a motor for electric vehicles in the prior art;

[0015] Figure 2 It is a second-gear wiring structure of a motor for electric vehicles in the prior art;

[0016] Figure 3 It is a three-speed wiring structure of a motor for electric vehicles in the prior art;

[0017] Figure 4The three-phase connection structure of the first gear of the permanent magnet synchronous motor according to the embodiment of the present invention;

[0018] Figure 5 The three-phase connection structure of the second gear of the permanent magnet synchronous motor according to the embodiment of the present invention;

[0019] Figure 6 The three-phase connection structure of the third gear of the permanent magnet synchronous motor according to the embodiment of the present invention;

[0020] Figure 7 This is a block diagram of the gear shift control of a permanent magnet synchronous motor according to an embodiment of the present invention;

[0021] Figure 8 It is a torque-speed curve diagram of a motor for electric vehicles in the prior art;

[0022] Fig. 9 This is a torque-speed curve diagram of the third-gear winding switching of the permanent magnet synchronous motor according to an embodiment of the present invention;

[0023] Description of the accompanying drawings: A1, A2, A3, A4 are the first end contacts of the first winding unit, the second winding unit, the third winding unit and the fourth winding unit in the U phase winding, respectively; X1, X2, X3, X4 are the end contacts of the first winding unit, the second winding unit, the third winding unit and the fourth winding unit in the U phase winding, respectively; B1, B2, B3, B4 are the first end contacts of the first winding unit, the second winding unit, the third winding unit and the fourth winding unit in the V phase winding, respectively; Y1, Y2, Y3, Y4 are the end contacts of the first winding unit, the second winding unit, the third winding unit and the fourth winding unit in the V phase winding, respectively C1, C2, C3, C4 are the starting contacts of winding unit No. 1, winding unit No. 2, winding unit No. 3 and winding unit No. 4 in the W-phase winding respectively, Z1, Z2, Z3, Z4 are the end contacts of winding unit No. 1, winding unit No. 2, winding unit No. 3 and winding unit No. 4 in the W-phase winding respectively; J1, J2, J3, J4, J5, J6, J7, J8, J9 represent the first electric-controlled switch, the second electric-controlled switch, the third electric-controlled switch, the fourth electric-controlled switch, the fifth electric-controlled switch, the sixth electric-controlled switch, the seventh electric-controlled switch, the eighth electric-controlled switch and the ninth electric-controlled switch respectively. DETAILED DESCRIPTION

[0024] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0025] The purpose of the present invention is to provide a three-phase wiring structure of a permanent magnet synchronous motor for an electric vehicle, which adjusts the three-speed wiring of the motor by series and parallel conversion, and constructs a plurality of independent Y-type parallel branches in the second and third gears, which do not affect each other, ensure the three-phase balance of the motor, and can smoothly control the on and off of the three-phase winding, thereby improving the safety of the motor operation.

[0026] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0027] like Figure 1-Figure 3 As shown, in the prior art, in the first-gear connection structure of the electric motor for electric vehicles, all four phase winding units in each phase winding are connected in series; in the second-gear connection structure, the four phase winding units in each phase winding are connected in series in pairs into two groups, and then the two groups connected in series are connected in parallel to form a Y-shaped parallel branch; in the third-gear connection structure, all four phase winding units in each phase winding are connected in parallel to form a Y-shaped parallel branch;

[0028] like Figure 4-Figure 7 As shown, the three-phase connection structure of the permanent magnet synchronous motor for electric vehicles provided by the present invention includes a permanent magnet synchronous motor and a controller. Each phase of the stator winding of the three-phase stator winding of the permanent magnet synchronous motor is composed of four winding units with the same total number of turns, the same winding wire diameter, and the same total cross-sectional area of ​​the winding wire, which are winding unit No. 1, winding unit No. 2, winding unit No. 3, and winding unit No. 4, respectively. An insulating layer is arranged between the coils of each phase winding unit, and an electric control switch for shifting is installed in the stator core space between the motor shaft and the stator slot. The four winding units in each phase winding are connected in series, in parallel, or in a mixed connection of series and parallel through multiple electric control switches. The operation mode of the connection constitutes gear shifting, and a current sensor is connected in series next to each electronically controlled switch, and the multiple electronically controlled switches and current sensors are electrically connected to the electric shift controller respectively; the electronically controlled switches are divided into three identical groups, and each group of the electronically controlled switches includes nine electronically controlled switches, namely the first electronically controlled switch J1, the second electronically controlled switch J2, the third electronically controlled switch J3, the fourth electronically controlled switch J4, the fifth electronically controlled switch J5, the sixth electronically controlled switch J6, the seventh electronically controlled switch J7, the eighth electronically controlled switch J8 and the ninth electronically controlled switch J9. When the motor is working normally, the electric shift controller controls the electronically controlled switches of the connecting branches corresponding to the first gear, the second gear and the third gear to close respectively.

[0029] Figure 4As shown, when starting in the first gear, the four winding units in each phase winding are connected in series in sequence through three electronically controlled switches. The first control switch J1 is connected in series between the first winding unit and the second winding unit in each phase winding, the second control switch J2 is connected in series between the second winding unit and the third winding unit, and the third control switch J3 is connected in series between the third winding unit and the fourth winding unit. The first electronically controlled switch J1, the second electronically controlled switch J2 and the third electronically controlled switch J3 in the three-phase winding are electrically connected to the electric shift controller respectively; taking the connection structure in the U phase winding as an example, one The first end contact A1 of winding unit No. 1 is connected to the U-phase power supply, and the terminal contact X1 is connected to J1, the first end contact A2 of winding unit No. 2 is connected to J1, and the terminal contact X2 is connected to J2, the first end contact A3 of winding unit No. 3 is connected to J2, and the terminal contact X3 is connected to J3, the first end contact A4 of winding unit No. 4 is connected to J3, and the same applies to V-phase winding and W-phase winding, and the terminal contact X4 of winding unit No. 4 in U-phase winding is connected together with the terminal contact Y4 of winding unit No. 4 in V-phase winding and the terminal contact Z4 of winding unit No. 4 in W-phase winding.

[0030] like Figure 5As shown, when accelerating in the second gear, the four winding units in each phase winding are connected in series into two groups, namely the first winding group and the second winding group. The first winding group of the three-phase winding is connected in parallel, and the second winding group is connected in parallel to form two independent Y-type parallel branches; when running at high speed in the third gear, each winding unit in each phase winding constitutes a branch separately, all the No. 1 winding units in the three-phase winding are connected in parallel, all the No. 2 winding units are connected in parallel, all the No. 3 winding units are connected in parallel, and all the No. 4 winding units are connected in parallel. Together, the first winding group in each phase winding is formed by a No. 1 winding unit and a No. 2 winding unit connected in series, and the second winding group is formed by a No. 2 winding unit and a No. 4 winding unit connected in series. A first electric control switch J1 is connected in series between the No. 1 winding unit and the No. 2 winding unit, a third electric control switch J3 is connected in series between the No. 2 winding unit and the No. 4 winding unit, a fifth electric control switch J5 is connected between the No. 1 winding unit and the No. 2 winding unit, and an eighth electric control switch J8 is connected to the end of the No. 2 winding unit. The three phase windings are connected in series. The first and the eighth electric control switches J8 are connected together, and the first electric control switch J1, the third electric control switch J3, the fifth electric control switch J5 and the eighth electric control switch J8 in the three-phase winding are respectively electrically connected to the electric shift controller; taking the connection structure in the U-phase winding as an example, the first end contact A1 of the No. 1 winding unit is connected to the U-phase power supply, and the terminal contact X1 is connected to J1, the first end contact A2 of the No. 2 winding unit is connected to J1, and the terminal contact X2 is connected to J8, the first end contact A3 of the No. 3 winding unit is connected to A1 through J5, and the terminal contact X1 is connected to J1. Contact X3 is connected to J3, the first end contact A4 of the fourth winding unit is connected to J3, the same applies to the V-phase winding and the W-phase winding, and the electric control switch J8 in the U-phase winding is connected with the second electric control switch J8 in the V-phase winding and the electric control switch J8 in the W-phase winding to form an independent Y-shaped zero potential point; the end contact X4 of the fourth winding unit in the V-phase winding is connected with the end contact Y4 of the fourth winding unit in the V-phase winding and the end contact Z4 of the fourth winding unit in the W-phase winding to form another independent Y-shaped zero potential point.

[0031] like Figure 6As shown, when the three-speed high-speed operation is performed, each winding unit in each phase winding independently constitutes a branch, all No. 1 winding units in the three-phase winding are connected in parallel, all No. 2 winding units are connected in parallel, all No. 3 winding units are connected in parallel, and all No. 4 winding units are connected in parallel to form four independent Y-type parallel branches; the head end of the No. 1 winding unit in each phase winding is connected to the head end of the No. 2 winding unit, the head end of the No. 3 winding unit, and the head end of the No. 4 winding unit through the fourth electric control switch J4, the fifth winding switch J5, and the sixth winding switch J6, respectively. The head end of the group unit and the head end of the fourth winding unit are connected, the end of the No. 1 winding unit in each phase winding is connected to the seventh electric control switch J7, and the three seventh electric control switches J7 in the three-phase winding are connected together; the end of the No. 2 winding unit in each phase winding is connected to the eighth electric control switch J8, and the three eighth electric control switches J8 in the three-phase winding are connected together; the end of the No. 3 winding unit in each phase winding is connected to the ninth electric control switch J9, and the three ninth electric control switches J9 in the three-phase winding are connected together, and all the three-phase windings are connected together. The ends of the fourth winding unit are connected together; the fourth electric control switch J4, the fifth electric control switch J5, the sixth electric control switch J6, the seventh electric control switch J7, the eighth electric control switch J8 and the ninth electric control switch J9 in the three-phase winding are respectively electrically connected to the electric shift controller; taking the connection structure in the U-phase winding as an example, the first end connection point A1 of the first winding unit is respectively connected to the first end connection point A2 of the second winding unit, the first end connection point A3 of the third winding unit through the fourth electric control switch J4, the fifth winding switch J5 and the sixth winding switch J6. The first end contact A3 and the first end contact A4 of the fourth winding unit are connected, the end contact X1 of the first winding unit is connected to the seventh electrically controlled switch J7, the end contact X2 of the second winding unit is connected to the seventh electrically controlled switch J8, the end contact X3 of the third winding unit is connected to the seventh electrically controlled switch J9, the three J7s in the UVW three phases are connected together, the three J8s are connected together, the three J9s are connected together, and the end contacts Z4 of the three fourth winding units are connected together, thereby forming four independent Y-shaped zero potential points.

[0032] The electric control switch is an electrical or power electronic switch device such as an AC contactor, a DC relay, a solid-state relay, an IGBT or a MOS field effect tube. The electric shift controller controls the on and off of the corresponding electric control switch according to the control program set by the speed signal, and determines the on and off of the corresponding electric control switch through the signal collected by the current sensor. For example, in the second gear, if any of the three J1 switch devices fails and should be closed but is disconnected, the other corresponding J1s immediately disconnect all J1s through the electric shift controller, then the three-phase winding is still in a three-phase balanced state, but the electric power and torque become half of the original, and the winding cannot work for a long time. At this time, the vehicle can travel slowly at a low speed. Similarly, if any one of the three J3, three J5 or three J8 switch devices fails, the above process is the same; for example, in the third gear, if any one of the three J7 switch devices fails and should be closed but is disconnected, the other corresponding J7s immediately disconnect them through the control program, then the three-phase winding is still in a three-phase balanced state, but the electric power and torque become three quarters of the original, and the winding cannot work for a long time. At this time, the vehicle can travel at a low speed. If any one of the three J4, three J5, three J6, three J8 or three J9 switch devices fails, the above process is the same.

[0033] like Figure 8 As shown, it is a torque-speed curve diagram of a general electric vehicle motor in the prior art. Speed ​​point A is the rated speed point of the motor. Between speed 0 and speed A, the motor is in a constant torque zone, and the motor back electromotive force is lower than the bus voltage of the battery pack of the electric vehicle, and weak magnetic control is not required. Between speed A and speed B, the motor is in a constant power zone, and the motor back electromotive force is higher than the bus voltage of the battery pack of the electric vehicle, and weak magnetic control is required. Between point A and point B, especially in the high-speed zone near point B, if the weak magnetic control software fails and the weak magnetic control fails, the motor is reversely dragged by the inertia of the vehicle to generate electricity and brake, causing the electric vehicle to brake immediately, resulting in a wide rollover risk area and a high risk. The weak magnetic control ratio of the motor is generally about 1.5, that is, the weak magnetic control area accounts for about 1.5 times that of the non-weak magnetic control area. It can be seen that in Figure 8 In the process, the entire weak magnetic field control area from point A to point B is at risk of losing control of the weak magnetic field control software.

[0034] and Fig. 9 : is a torque-speed curve diagram of the three-speed winding switching of the permanent magnet synchronous motor according to an embodiment of the present invention, such as Fig. 9As shown, 0-a, ab, and bc correspond to the constant torque areas of the 1st, 2nd, and 3rd gears of the motor respectively, and only cd is the weak magnetic acceleration area of ​​the highest speed in the three gears. Since the cd section is very narrow and is in the shallow weak magnetic area, the weak magnetic current is very small. If the weak magnetic control software fails and the weak magnetic control fails, the motor is reversely dragged by the inertia of the car to generate electricity and brake, causing the electric vehicle to brake immediately and cause the risk of rollover. The high-speed area of ​​the motor is very narrow and the risk is very small. In addition, if the above-mentioned failure occurs, this wiring method can also immediately disconnect all the electronic control switch devices J1-J9, so that the motor is in an idling state, and the electric vehicle can coast by inertia to avoid rollover caused by sudden braking.

[0035] The three-phase wiring structure of the permanent magnet synchronous motor for electric vehicles provided by the present invention utilizes a plurality of electronically controlled switches to convert the windings of the permanent magnet synchronous motor for electric vehicles into a three-speed motor by means of series and parallel conversion, and can increase the speed without weak magnetic control. The on and off of the electronically controlled switches are controlled by a controller, and the winding wiring mode is switched to form the first gear, the second gear, and the third gear to increase the speed. Compared with the existing wiring structure, the wiring structure of the present application does not change in the first gear, but in the second gear or the third gear, two or four independent Y-shaped parallel branches are formed by adjusting the positions of the plurality of electronically controlled switches and adjusting the circuits, thereby avoiding mutual influence between the plurality of branches. Even if a certain Y-shaped parallel branch is broken due to a fault, it will not affect the operation of other Y-shaped parallel branches, thereby ensuring the three-phase balance of the motor. Balance, and in actual wiring, compared with the traditional connection method, there are three fewer connecting wires, and the connection method is simple; when a certain electric control switch in each phase winding fails and does not close or disconnect according to the predetermined instruction, the controller can disconnect the other electric control switches corresponding to the electric control switch at the same time, so that the three-phase winding of the motor is still in a balanced state, increasing the redundancy of the three-speed permanent magnet synchronous motor for electric vehicles and improving the safety performance of electric vehicles; compared with the traditional permanent magnet synchronous three-phase motor weak magnetic speed control method, if the weak magnetic control program fails, the weak magnetic control fails, so that the motor is reversely dragged by the inertia of the car to generate electricity and brake, causing the electric vehicle to brake immediately, thereby causing the risk of rollover; the present invention can use less or no weak magnetic control, and there is no or reduced possibility of the above-mentioned risks due to the failure of weak magnetic control. In addition, even if the problem of weak magnetic control failure occurs in the high-speed weak magnetic area, the present invention can also disconnect 9 electric control switches at the same time to prevent the motor from being reversely dragged by the inertia of the car to generate electricity and brake, causing the electric vehicle to brake immediately, thereby causing the risk of rollover.

[0036] The principles and implementation methods of the present invention are described in this article using specific examples. The description of the above embodiments is only used to help understand the method and core idea of ​​the present invention. At the same time, for those skilled in the art, according to the idea of ​​the present invention, there will be changes in the specific implementation methods and application scope. In summary, the content of this specification should not be understood as limiting the present invention.

Claims

1. A three-phase connection structure of a permanent magnet synchronous motor for an electric vehicle, comprising a permanent magnet synchronous motor and a controller, wherein each phase of the three-phase stator winding of the permanent magnet synchronous motor is composed of four winding units with the same total number of turns, the same winding wire diameter, and the same total cross-sectional area of ​​the winding wire, namely, winding unit No. 1, winding unit No. 2, winding unit No. 3, and winding unit No. 4, and an insulating layer is provided between the coils of each phase winding unit, characterized in that: The electric shifting is implemented by connecting four winding units in each phase of the winding in series, in parallel, or in a mixed connection of series and parallel by multiple electric control switches, and a current sensor is connected in series next to each electric control switch, and the multiple electric control switches and current sensors are electrically connected to the electric shifting controller respectively; When starting in the first gear, the four winding units in each phase winding are connected in series in sequence through three electronically controlled switches; when accelerating in the second gear, the four winding units in each phase winding are connected in series in pairs into two groups, namely the first winding group and the second winding group. The first winding group of the three-phase winding is connected in parallel, and the second winding group is connected in parallel to form two independent Y-type parallel branches; when running at high speed in the third gear, each winding unit in each phase winding constitutes a branch separately, all the No. 1 winding units of the three-phase winding are connected in parallel, all the No. 2 winding units are connected in parallel, all the No. 3 winding units are connected in parallel, and all the No. 4 winding units are connected in parallel to form four independent Y-type parallel branches; The electric-controlled switches are divided into three identical groups, each group of the electric-controlled switches includes nine electric-controlled switches, namely a first electric-controlled switch, a second electric-controlled switch, a third electric-controlled switch, a fourth electric-controlled switch, a fifth electric-controlled switch, a sixth electric-controlled switch, a seventh electric-controlled switch, an eighth electric-controlled switch and a ninth electric-controlled switch; When the second gear is accelerated, the first group of windings in each phase winding is formed by a No. 1 winding unit and a No. 2 winding unit connected in series, the second group of windings is formed by a No. 2 winding unit and a No. 4 winding unit connected in series, a first electric control switch is connected in series between the No. 1 winding unit and the No. 2 winding unit, a third electric control switch is connected in series between the No. 2 winding unit and the No. 4 winding unit, a fifth electric control switch is connected between the No. 1 winding unit and the No. 2 winding unit, an eighth electric control switch is connected to the end of the No. 2 winding unit, the three eighth electric control switches in the three-phase winding are connected together, and the first electric control switch, the third electric control switch, the fifth electric control switch and the eighth electric control switch in the three-phase winding are respectively electrically connected to the electric shift controller; When the third gear is running at high speed, the head end of the No. 1 winding unit in each phase winding is connected to the head end of the No. 2 winding unit, the head end of the No. 3 winding unit, and the head end of the No. 4 winding unit through the fourth electric control switch, the fifth winding switch, and the sixth winding switch, respectively, the end of the No. 1 winding unit in each phase winding is connected to the seventh electric control switch, and the three seventh electric control switches in the three-phase winding are connected together; the end of the No. 2 winding unit in each phase winding is connected to the eighth electric control switch, and the three eighth electric control switches in the three-phase winding are connected together; the end of the No. 3 winding unit in each phase winding is connected to the ninth electric control switch, the three ninth electric control switches in the three-phase winding are connected together, and the ends of all the No. 4 winding units in the three-phase winding are connected together; the fourth electric control switch, the fifth electric control switch, the sixth electric control switch, the seventh electric control switch, the eighth electric control switch and the ninth electric control switch in the three-phase winding are respectively electrically connected to the electric shift controller; The electric shift controller controls the on and off of the corresponding electric control switch according to the control program set by the speed signal, and determines the on and off of the corresponding electric control switch through the signal collected by the current sensor; in the second gear, if any of the three first electric control switch switching devices fails and should be closed but is disconnected, the other corresponding first electric control switches immediately disconnect all the first electric control switches through the electric shift controller, then the three-phase winding is still in a three-phase balanced state, but the electric power and torque become half of the original, and the winding cannot work for a long time. At this time, the vehicle can travel slowly at a low speed; Similarly, if any one of the three third electronically controlled switches, the three fifth electronically controlled switches or the three eighth electronically controlled switches fails, the above process is the same; for example, in the third gear, if any one of the three seventh electronically controlled switches fails and should be closed but is disconnected, the other corresponding seventh electronically controlled switches immediately disconnect them through the control program, then the three-phase winding is still in a three-phase balanced state, but the electric power and torque become three-quarters of the original, and the winding cannot work for a long time. At this time, the vehicle can travel at a low speed. If any one of the three fourth electronically controlled switches, the three fifth electronically controlled switches, the three sixth electronically controlled switches, the three eighth electronically controlled switches or the three ninth electronically controlled switches fails, the above process is the same.

2. The three-phase connection structure of the permanent magnet synchronous motor for electric vehicles according to claim 1, characterized in that: When the first gear is started, the first control switch is connected in series between the No. 1 winding unit and the No. 2 winding unit in each phase winding, the second control switch is connected in series between the No. 2 winding unit and the No. 3 winding unit, and the third control switch is connected in series between the No. 3 winding unit and the No. 4 winding unit. The first electronically controlled switch, the second electronically controlled switch and the third electronically controlled switch in the three-phase winding are electrically connected to the electric shift controller respectively.

3. The three-phase connection structure of the permanent magnet synchronous motor for electric vehicles according to claim 1, characterized in that: The electric control switch is an AC contactor, a DC relay, a solid-state relay, an IGBT or a MOS field effect tube.

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