CN112590542A - Pure electric power assembly and control method thereof - Google Patents

Pure electric power assembly and control method thereof Download PDF

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Publication number
CN112590542A
CN112590542A CN202011601299.8A CN202011601299A CN112590542A CN 112590542 A CN112590542 A CN 112590542A CN 202011601299 A CN202011601299 A CN 202011601299A CN 112590542 A CN112590542 A CN 112590542A
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Prior art keywords
gear
motor
torque
shaft
speed
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CN202011601299.8A
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CN112590542B (en
Inventor
桂经良
王志新
高文进
丁大凯
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Weichai Power Co Ltd
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Weichai Power Co Ltd
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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60K—ARRANGEMENT OR MOUNTING OF PROPULSION UNITS OR OF TRANSMISSIONS IN VEHICLES; ARRANGEMENT OR MOUNTING OF PLURAL DIVERSE PRIME-MOVERS IN VEHICLES; AUXILIARY DRIVES FOR VEHICLES; INSTRUMENTATION OR DASHBOARDS FOR VEHICLES; ARRANGEMENTS IN CONNECTION WITH COOLING, AIR INTAKE, GAS EXHAUST OR FUEL SUPPLY OF PROPULSION UNITS IN VEHICLES
    • B60K1/00—Arrangement or mounting of electrical propulsion units
    • B60K1/02—Arrangement or mounting of electrical propulsion units comprising more than one electric motor
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60K—ARRANGEMENT OR MOUNTING OF PROPULSION UNITS OR OF TRANSMISSIONS IN VEHICLES; ARRANGEMENT OR MOUNTING OF PLURAL DIVERSE PRIME-MOVERS IN VEHICLES; AUXILIARY DRIVES FOR VEHICLES; INSTRUMENTATION OR DASHBOARDS FOR VEHICLES; ARRANGEMENTS IN CONNECTION WITH COOLING, AIR INTAKE, GAS EXHAUST OR FUEL SUPPLY OF PROPULSION UNITS IN VEHICLES
    • B60K17/00—Arrangement or mounting of transmissions in vehicles
    • B60K17/02—Arrangement or mounting of transmissions in vehicles characterised by arrangement, location, or kind of clutch
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60K—ARRANGEMENT OR MOUNTING OF PROPULSION UNITS OR OF TRANSMISSIONS IN VEHICLES; ARRANGEMENT OR MOUNTING OF PLURAL DIVERSE PRIME-MOVERS IN VEHICLES; AUXILIARY DRIVES FOR VEHICLES; INSTRUMENTATION OR DASHBOARDS FOR VEHICLES; ARRANGEMENTS IN CONNECTION WITH COOLING, AIR INTAKE, GAS EXHAUST OR FUEL SUPPLY OF PROPULSION UNITS IN VEHICLES
    • B60K17/00—Arrangement or mounting of transmissions in vehicles
    • B60K17/04—Arrangement or mounting of transmissions in vehicles characterised by arrangement, location, or kind of gearing
    • B60K17/06—Arrangement or mounting of transmissions in vehicles characterised by arrangement, location, or kind of gearing of change-speed gearing
    • B60K17/08—Arrangement or mounting of transmissions in vehicles characterised by arrangement, location, or kind of gearing of change-speed gearing of mechanical type
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60K—ARRANGEMENT OR MOUNTING OF PROPULSION UNITS OR OF TRANSMISSIONS IN VEHICLES; ARRANGEMENT OR MOUNTING OF PLURAL DIVERSE PRIME-MOVERS IN VEHICLES; AUXILIARY DRIVES FOR VEHICLES; INSTRUMENTATION OR DASHBOARDS FOR VEHICLES; ARRANGEMENTS IN CONNECTION WITH COOLING, AIR INTAKE, GAS EXHAUST OR FUEL SUPPLY OF PROPULSION UNITS IN VEHICLES
    • B60K17/00—Arrangement or mounting of transmissions in vehicles
    • B60K17/04—Arrangement or mounting of transmissions in vehicles characterised by arrangement, location, or kind of gearing
    • B60K17/12—Arrangement or mounting of transmissions in vehicles characterised by arrangement, location, or kind of gearing of electric gearing
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60L—PROPULSION OF ELECTRICALLY-PROPELLED VEHICLES; SUPPLYING ELECTRIC POWER FOR AUXILIARY EQUIPMENT OF ELECTRICALLY-PROPELLED VEHICLES; ELECTRODYNAMIC BRAKE SYSTEMS FOR VEHICLES IN GENERAL; MAGNETIC SUSPENSION OR LEVITATION FOR VEHICLES; MONITORING OPERATING VARIABLES OF ELECTRICALLY-PROPELLED VEHICLES; ELECTRIC SAFETY DEVICES FOR ELECTRICALLY-PROPELLED VEHICLES
    • B60L15/00—Methods, circuits, or devices for controlling the traction-motor speed of electrically-propelled vehicles
    • B60L15/20—Methods, circuits, or devices for controlling the traction-motor speed of electrically-propelled vehicles for control of the vehicle or its driving motor to achieve a desired performance, e.g. speed, torque, programmed variation of speed
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60L—PROPULSION OF ELECTRICALLY-PROPELLED VEHICLES; SUPPLYING ELECTRIC POWER FOR AUXILIARY EQUIPMENT OF ELECTRICALLY-PROPELLED VEHICLES; ELECTRODYNAMIC BRAKE SYSTEMS FOR VEHICLES IN GENERAL; MAGNETIC SUSPENSION OR LEVITATION FOR VEHICLES; MONITORING OPERATING VARIABLES OF ELECTRICALLY-PROPELLED VEHICLES; ELECTRIC SAFETY DEVICES FOR ELECTRICALLY-PROPELLED VEHICLES
    • B60L2220/00—Electrical machine types; Structures or applications thereof
    • B60L2220/10—Electrical machine types
    • B60L2220/14—Synchronous machines
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60L—PROPULSION OF ELECTRICALLY-PROPELLED VEHICLES; SUPPLYING ELECTRIC POWER FOR AUXILIARY EQUIPMENT OF ELECTRICALLY-PROPELLED VEHICLES; ELECTRODYNAMIC BRAKE SYSTEMS FOR VEHICLES IN GENERAL; MAGNETIC SUSPENSION OR LEVITATION FOR VEHICLES; MONITORING OPERATING VARIABLES OF ELECTRICALLY-PROPELLED VEHICLES; ELECTRIC SAFETY DEVICES FOR ELECTRICALLY-PROPELLED VEHICLES
    • B60L2220/00—Electrical machine types; Structures or applications thereof
    • B60L2220/40—Electrical machine applications
    • B60L2220/42—Electrical machine applications with use of more than one motor
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60L—PROPULSION OF ELECTRICALLY-PROPELLED VEHICLES; SUPPLYING ELECTRIC POWER FOR AUXILIARY EQUIPMENT OF ELECTRICALLY-PROPELLED VEHICLES; ELECTRODYNAMIC BRAKE SYSTEMS FOR VEHICLES IN GENERAL; MAGNETIC SUSPENSION OR LEVITATION FOR VEHICLES; MONITORING OPERATING VARIABLES OF ELECTRICALLY-PROPELLED VEHICLES; ELECTRIC SAFETY DEVICES FOR ELECTRICALLY-PROPELLED VEHICLES
    • B60L2240/00—Control parameters of input or output; Target parameters
    • B60L2240/40—Drive Train control parameters
    • B60L2240/42—Drive Train control parameters related to electric machines
    • B60L2240/423—Torque
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60L—PROPULSION OF ELECTRICALLY-PROPELLED VEHICLES; SUPPLYING ELECTRIC POWER FOR AUXILIARY EQUIPMENT OF ELECTRICALLY-PROPELLED VEHICLES; ELECTRODYNAMIC BRAKE SYSTEMS FOR VEHICLES IN GENERAL; MAGNETIC SUSPENSION OR LEVITATION FOR VEHICLES; MONITORING OPERATING VARIABLES OF ELECTRICALLY-PROPELLED VEHICLES; ELECTRIC SAFETY DEVICES FOR ELECTRICALLY-PROPELLED VEHICLES
    • B60L2240/00—Control parameters of input or output; Target parameters
    • B60L2240/40—Drive Train control parameters
    • B60L2240/42—Drive Train control parameters related to electric machines
    • B60L2240/425—Temperature
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60L—PROPULSION OF ELECTRICALLY-PROPELLED VEHICLES; SUPPLYING ELECTRIC POWER FOR AUXILIARY EQUIPMENT OF ELECTRICALLY-PROPELLED VEHICLES; ELECTRODYNAMIC BRAKE SYSTEMS FOR VEHICLES IN GENERAL; MAGNETIC SUSPENSION OR LEVITATION FOR VEHICLES; MONITORING OPERATING VARIABLES OF ELECTRICALLY-PROPELLED VEHICLES; ELECTRIC SAFETY DEVICES FOR ELECTRICALLY-PROPELLED VEHICLES
    • B60L2240/00—Control parameters of input or output; Target parameters
    • B60L2240/40—Drive Train control parameters
    • B60L2240/54—Drive Train control parameters related to batteries
    • B60L2240/545—Temperature

Abstract

The invention discloses a pure electric power assembly and a control method thereof, wherein the pure electric power assembly comprises a first motor, a second motor, a main gearbox and an auxiliary gearbox, the main gearbox comprises a main gearbox output shaft, a first input shaft, a second input shaft, a first gear shifting shaft and a second gear shifting shaft, the first input shaft and the second input shaft are fixedly connected with a first gear and a second gear, a first gear meshing gear and a second gear meshing gear are sleeved on the first gear shifting shaft and the second gear shifting shaft in a hollow manner and are fixedly connected with a gear shifting output gear, a gear shifting mechanism is arranged between the first gear meshing gear and the second gear meshing gear, the main gearbox output shaft is provided with a main gear meshed with the gear shifting output gear, the output end of the main gearbox output shaft is the input end of the auxiliary gearbox, and a speed reducing mechanism is arranged in the auxiliary gearbox. The invention can reduce the dynamic load of parts such as bearings and the like under the working condition of large torque and improve the reliability of the parts.

Description

Pure electric power assembly and control method thereof
Technical Field
The invention relates to the technical field of new energy vehicles, in particular to a pure electric power assembly and a control method thereof.
Background
With the continuous development of new energy vehicles, more and more pure electric vehicles become the mainstream of new energy vehicles at present. However, the existing pure electric vehicle power assembly, especially the dual-motor power assembly, still has the unreasonable arrangement of the power assembly, and cannot meet the application requirements of heavy commercial vehicles. The heavy commercial vehicle has application requirements of high-speed efficiency and large low-speed torque, the highest vehicle speed can reach 80 km/h-90 km/h, and the power assembly can exert very large torque in a low-speed area, for example, the urban construction dump truck requires the power assembly to output 20000-30000 N.m torque, and meanwhile, under the large torque, the dynamic load requirement on a bearing is very strict, the torque and power requirements on the motor are also very high, and the cost of the motor is increased. At present, the prior art mainly adopts a high-speed motor with the highest rotating speed exceeding 10000r/m to reduce the torque of the motor, however, the flux weakening loss and the like of the motor are correspondingly increased after the highest rotating speed is increased.
Therefore, how to reasonably design a pure electric power assembly and coordinate a control process of multi-motor torque or energy flow distribution management is a technical problem to be solved by those skilled in the art at present.
Disclosure of Invention
In view of this, the present invention provides a pure electric power assembly, which can reduce the dynamic load of components such as bearings under a large torque condition, and improve the reliability of the components. The invention also aims to provide a control method of the pure electric power assembly, which is matched with the pure electric power assembly to coordinate and control the torque or energy flow distribution of the motor and improve the energy utilization efficiency of the power assembly.
In order to achieve the purpose, the invention provides the following technical scheme:
a pure electric power assembly comprises a first motor, a second motor, a main gear box and an auxiliary gear box, wherein the main gear box comprises a main gear box output shaft, a first input shaft connected with the first motor and a second input shaft connected with the second motor, a first gear and a second gear are fixedly connected to the first input shaft and the second input shaft respectively, the main gear box further comprises a first gear shift shaft parallel to the first input shaft and a second gear shift shaft parallel to the second input shaft, a first gear meshing gear and a second gear meshing gear are sleeved on the first gear shift shaft and the second gear shift shaft in a free manner, a gear shifting mechanism is arranged between the first gear meshing gear and the second gear meshing gear, a gear shifting output gear is fixedly connected to the first gear shift shaft and the second gear shift shaft respectively, a main gear meshed with the gear shifting output gear is arranged at the input end of the gear box output shaft, the output end of the output shaft of the main gearbox is the input end of the auxiliary gearbox, and a speed reducing mechanism is arranged in the auxiliary gearbox.
This scheme keeps off the meshing gear with keeping off of first motor and second motor respectively and keeps off the meshing gear empty sleeve and install on first selector shaft and second selector shaft, compares in prior art, and this scheme can reduce the rotational speed of main gear box inner bearing under the condition of the same motor speed, reduces the dynamic load of bearing. The scheme adopts the structure of the preposed main gearbox and the postposition auxiliary gearbox, further speed reduction and torque increase are carried out in the auxiliary gearbox after gear shifting is completed in the main gearbox, torque shunting is realized simultaneously, and the bearings of the input shaft and the output shaft of the auxiliary gearbox are subjected to small radial load, so that the service life of the bearing of the auxiliary gearbox is prolonged.
Preferably, the speed reduction mechanism is a double-intermediate-shaft speed reduction mechanism or a planet carrier speed reduction mechanism.
Preferably, the first gear meshing gear is fixedly connected with a first gear engaging gear ring, the second gear meshing gear is fixedly connected with a second gear engaging gear ring, and the gear shifting mechanism comprises a spline hub, a sliding sleeve, the first gear engaging gear ring and the second gear engaging gear ring.
Preferably, the first gear engaging gear ring and the first gear engaging gear are of an integral structure, and the second gear engaging gear ring and the second gear engaging gear are of an integral structure.
Preferably, the first shift shaft and the second shift shaft each have the splined hub attached thereto.
Preferably, the first motor is a permanent magnet synchronous motor, and the second motor is a three-phase alternating current asynchronous motor.
The invention also provides a control method of the pure electric power assembly, which is applied to the pure electric power assembly, wherein the control method comprises the following steps of:
determining the required torque T of the power assembly according to the opening degree of an accelerator pedal, the opening degree of a brake pedal and the vehicle weightreq；
Determining a first motor power limit value and a second motor power limit value according to the SOC of the power battery, the SOH of the power battery, the temperature of the first motor and a controller thereof, and the temperature of the second motor and a controller thereof;
according to the required torque T of the power assemblyreqOutput speed n of power assemblycurCurrent transmission ratio i of the first electric machinexCurrent transmission ratio i of the second electric machineyDetermining first required torques of the first motor and the second motor according to the first motor power limit value and the second motor power limit value;
determining second required torques of the first motor and the second motor based on the first motor torque change rate calibration quantity and the second motor torque change rate calibration quantity according to the current actual torque of the first motor and the current actual torque of the second motor;
the second required torques of the first and second electric machines are used as the required torques of the first and second electric machines.
Preferably, the control method further includes a gear control logic of the electric machine:
when the vehicle starts, the first motor is in first gear engagement for main driving, and the second motor is in first gear engagement for auxiliary driving;
when the vehicle speed reaches a first gear shifting vehicle speed standard quantity, the first motor is driven by engaging two gears, and the second motor is kept at a first gear;
when the speed of a vehicle reaches a second gear shifting speed calibration quantity, the second motor is in secondary gear engagement to carry out main driving, and the first motor is kept in secondary gear to carry out auxiliary driving.
Preferably, in determining the first required torques of the first and second electric machines, the motor drive torque distribution control logic is based on the following equation:
Figure BDA0002871155950000041
Tx＝Txv/(ix·μx)；
Ty＝Tyv/(iy·μy)；
wherein n iscurIs the power assembly output speed at the current vehicle speed, ixAnd iyCurrent gear ratios, T, of the first and second electric machines, respectivelyxvThe first motor converts the torque demand, T, on the output shaftyvIs the torque demanded, mu, converted to the output shaft by the second motorxAnd muyMechanical transmission efficiency, mu, of the first and second electric machines at the current rotational speed and torque, respectivelymxAnd mumyThe motor system efficiencies of the first and second motors at the current rotational speed and torque, respectively.
Preferably, in determining the first required torques of the first and second electric machines, the electric machine braking torque distribution control logic is based on the following equation:
Figure BDA0002871155950000042
wherein n iscurIs the power assembly output speed at the current vehicle speed, ixAnd iyCurrent gear ratios, T, of the first and second electric machines, respectivelyxvThe first motor converts the torque demand, T, on the output shaftyvIs the torque demanded, mu, converted to the output shaft by the second motorxAnd muyMechanical transmission efficiency, mu, of the first and second electric machines at the current rotational speed and torque, respectivelymxAnd mumyFirst and second motors at current speed and torque, respectivelyThe motor system efficiency of the machine.
Through the control method provided by the invention, the required torques of the two motors can be reasonably distributed and coordinated under different rotating speeds, so that the two motors can operate in a high-efficiency area, and the efficiency of the two motors is improved.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the drawings without creative efforts.
FIG. 1 is a schematic structural arrangement diagram of a first electric-only powertrain according to an embodiment of the present invention;
FIG. 2 is a schematic structural arrangement diagram of a second electric-only powertrain according to an embodiment of the present invention;
FIG. 3 is a schematic structural diagram of a shift mechanism in an exemplary embodiment of the present invention;
fig. 4 is a flowchart of a control method of the pure electric powertrain in the embodiment of the present invention.
The meaning of the various reference numerals in figures 1 to 3 is as follows:
101-first electric machine, 102-second electric machine, 201-first input shaft, 202-second input shaft, 301-first gear, 302-second gear, 401-first gear, 402-second gear, 403-shift output gear, 500-shift mechanism, 501-first gear meshing gear, 502-second gear meshing gear, 503-first gear meshing gear ring, 504-second gear meshing gear ring, 505-sliding sleeve, 506-spline hub, 600-main transmission output shaft, 601-main transmission gear, 602-auxiliary transmission input gear, 700-main transmission, 800-auxiliary transmission, 801-first intermediate shaft, 802-second intermediate shaft, 803-intermediate shaft input gear, 804-intermediate shaft output gear, 805-auxiliary transmission output gear, 806-auxiliary gearbox output shaft, 807-sun gear, 808-planet carrier, 809-ring gear.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
Referring to fig. 1 and fig. 2, fig. 1 is a schematic structural arrangement diagram of a first pure electric powertrain according to an embodiment of the present invention; FIG. 2 is a schematic structural arrangement diagram of a second electric-only powertrain according to an embodiment of the present invention; fig. 3 is a schematic structural diagram of a shift mechanism in an embodiment of the present invention.
The invention provides a pure electric power assembly, which comprises a first motor 101, a second motor 102, a main gearbox 700 and an auxiliary gearbox 800, wherein the main gearbox 700 comprises a main gearbox output shaft 600, a first input shaft 201 connected with the first motor 101 and a second input shaft 202 connected with the second motor 102, the first input shaft 201 and the second input shaft 202 are fixedly connected with a first gear 301 and a second gear 302, the main gearbox 700 also comprises a first gear shifting shaft 401 parallel to the first input shaft 201 and a second gear shifting shaft 402 parallel to the second input shaft 202, a first gear meshing gear 501 and a second gear meshing gear 502 are arranged on the first gear shifting shaft 401 and the second gear shifting shaft 402 in a free sleeve mode (rotatably arranged through a bearing, a sliding bearing and the like), the first gear meshing gear 501 is meshed with the first gear 301, the second gear meshing gear 502 is meshed with the second gear 302, and a gear shifting mechanism 500 is arranged between the first gear meshing gear 501 and the second gear 502, the first gear shifting shaft 401 and the second gear shifting shaft 402 are fixedly connected with a gear shifting output gear 403, a main gear 601 meshed with the gear shifting output gear 403 is arranged at the input end of a main gear box output shaft 600, the output end of the main gear box output shaft 600 is the input end of an auxiliary gear box 800, and a speed reducing mechanism is arranged in the auxiliary gear box 800.
It should be noted that the shift mechanism 500 in the present invention can be designed as a sliding sleeve shift mechanism, a paddle shift mechanism, a pressure plate shift mechanism, etc., preferably, a sliding sleeve shift mechanism is adopted in this embodiment, specifically, as shown in fig. 3, the first-gear meshing gear 501 is fixedly connected with the first-gear engaging gear ring 503, the second-gear meshing gear 502 is fixedly connected with the second-gear engaging gear ring 504, and the shift mechanism 500 includes a spline hub 506, a sliding sleeve 505, the first-gear engaging gear ring 503 and the second-gear engaging gear ring 504. The spline hub 506 and the shift shaft on which the spline hub is arranged can be matched through splines to transmit torque, and in order to prevent the meshing gear and the spline hub 506 from shifting along the axial direction of the shift shaft, the spline hub is axially limited through a retaining ring or a shaft shoulder and the like. In addition, the spline hub 506 and the shift shaft located therein may be connected by other connection methods, such as key fitting or integral molding, and the spline hub 506 is preferably fixed to the first shift shaft 401 and the second shift shaft 402. The sliding sleeve 505 is slidably disposed outside the spline hub 506 and is engaged with the spline hub 506 through splines, and by moving the position of the sliding sleeve 505, the inner gear ring of the sliding sleeve 505 is engaged with the outer gear of the first gear engagement ring gear 503 or the second gear engagement ring gear 504, thereby shifting the main transmission case 700.
Note that the connection manner of the first stage engagement ring gear 503 and the first stage meshing gear 501 and the connection manner of the second stage engagement ring gear 504 and the second stage meshing gear 502 may be spline-fitted, or may be another connection manner, such as interference fit or integral molding. Preferably, in this embodiment, the first-gear engaging gear ring 503 and the first-gear engaging gear 501 are of an integral structure, and the second-gear engaging gear ring 504 and the second-gear engaging gear 502 are of an integral structure.
The main gear box 700 is further provided with a gear shifting executing mechanism and a control unit thereof, which are not described herein again.
It should be noted that in this embodiment, the speed reduction mechanism in the sub-transmission 800 may be designed as a double-intermediate-shaft speed reduction mechanism or a planet carrier speed reduction mechanism. As shown in fig. 1, the double-countershaft speed reducing mechanism includes a first countershaft 801 and a second countershaft 802, a portion of the main transmission output shaft 600 extending into the auxiliary transmission 800 is an auxiliary transmission input shaft, the auxiliary transmission input shaft is fixedly connected with an auxiliary transmission input gear 602, the first countershaft 801 and the second countershaft 802 are fixedly connected with a countershaft input gear 803 engaged with the auxiliary transmission input gear 602, the first countershaft 801 and the second countershaft 802 are fixedly connected with a countershaft output gear 804, and the auxiliary transmission output shaft 806 is fixedly connected with an auxiliary transmission output gear 805 engaged with the two countershaft output gears 804. As shown in fig. 2, the planetary carrier reduction mechanism includes a sun gear 807, a planetary carrier 808, and a ring gear 809, wherein the sun gear 807 is fixedly connected to the input shaft of the sub-transmission case, the ring gear 809 is fixedly connected to the casing of the sub-transmission case 800, and the planetary carrier 808 is fixedly connected to the output shaft 806 of the sub-transmission case.
Preferably, the first electric machine 101 is a permanent magnet synchronous machine and the second electric machine 102 is a three-phase alternating current asynchronous machine. The permanent magnet synchronous motor has higher efficiency and is used as a main driving motor, and the high-efficiency area of the permanent magnet synchronous motor is positioned in the medium-speed area; the three-phase alternating current asynchronous motor has no high-speed weak magnetic loss, and does not need extra current/energy to perform weak magnetic in the high-speed idling process, so that the three-phase alternating current asynchronous motor is used as an auxiliary driving motor, and the high-efficiency area of the three-phase alternating current asynchronous motor is positioned in a medium-high speed area. In addition, the power demand of the vehicle during high-speed cruising is small, the high-efficiency main driving motor is independently driven, the auxiliary driving second motor idles along with the vehicle, the flux weakening loss is avoided, and the electric energy utilization efficiency is improved.
According to the scheme, the first gear meshing gear 501 and the second gear meshing gear 502 of the first motor 101 and the second motor 102 are respectively installed on the first gear shifting shaft 401 and the second gear shifting shaft 402 in an empty mode, and compared with the prior art, the scheme can reduce the rotating speed of a bearing in the main gear shifting box 700 and reduce the dynamic load of the bearing under the condition of the same motor rotating speed. The scheme adopts the structure of the front main gearbox 700 and the rear auxiliary gearbox 800, further speed reduction and torque increase are carried out in the auxiliary gearbox 800 after gear shifting is completed in the main gearbox 700, torque split is realized simultaneously, and the bearings of the input shaft and the output shaft of the auxiliary gearbox are subjected to small radial load, so that the service life of the bearings in the auxiliary gearbox 800 is prolonged. Therefore, the pure electric power assembly provided by the invention can reduce the dynamic load of parts such as bearings and the like under the working condition of large torque, and improves the reliability of the parts.
In addition, when this scheme is in single motor work, perhaps when the output torque difference of two motors is great, this scheme adopts main gearbox 700 and the vice gearbox 800 of two jackshaft structures, can balance the radial force of each axle, simultaneously, has that the part is small in quantity, simple structure, advantage with low costs.
It should be noted that the motor has different efficiencies at different torques and rotation speeds, so that the efficiency of the motor can be improved only by reasonably distributing the torque of the motor, and the energy consumption of the motor is reduced. For example, assuming that the efficiency of the first motor 101 is 94% at the highest when the rotation speed is 6000-8000 r/m and the torque is 100-400N · m, and the efficiency of the second motor 102 is 93% at the highest when the rotation speed is 8000-10000 r/m and the torque is 100-400N · m, if the rotation speed is 7000r/m and the sum of the required motor torques is 300N · m, then it is desirable that the torques are all provided by the first motor 101, and the second motor 102 is idled, so that the highest motor operation efficiency can be achieved; if the sum of the required motor torques is 1000N · m at a rotational speed of 8000r/m, it is desirable that the torques are distributed to the first motor 101 and the second motor 102, and the torques and the required energy consumptions of the first motor 101 and the second motor 102 are the lowest.
Therefore, in order to coordinate the torque or energy flow distribution of the two electric machines and improve the energy utilization efficiency, the present invention further provides a control method of the pure electric powertrain, which is applied to the pure electric powertrain as described above, in the control method, the torque distribution of the first electric machine 101 and the second electric machine 102 includes the following steps, please refer to fig. 4:
s100: determining the required torque T of the power assembly according to the opening degree of an accelerator pedal, the opening degree of a brake pedal and the vehicle weightreqTorque requested T of power train in drivingreqPositive, powertrain demand torque T at braking energy recoveryreqIs a negative value; the purpose of this step is to analyze the driver's intention, when it is detected that the accelerator opening is increased, it indicates that the driver has an intention to accelerate driving, when it is detected that the brake opening is increased, it indicates that the driver has an intention to brake and decelerate, and at the same time, it is possible to determine the powertrain demand torque T in combination with the vehicle weight data inputted from the load calculation modulereq。
S200: determining a first motor power limit value and a second motor power limit value according to the SOC (state of charge) of a power battery, the SOH (battery health degree) of the power battery, the temperature of a first motor and a controller thereof, and the temperature of a second motor and a controller thereof; in the step, the charging and discharging power of the first motor 101 and the second motor 102 is controlled to avoid exceeding the upper limit value mainly through the charging and discharging power limiting module according to the state of charge, the health degree and the temperature of the current power battery and by combining the temperatures of the two motors and the controllers thereof.
The power of the battery, the motor controller, the motor and other components is affected by the temperature, for example, the suitable working temperature range of the battery is 20-45 ℃, if the temperature is too low, the chemical reaction speed is limited, and the power is further limited, if the temperature is too high, the battery works at high power, more heat is generated, the temperature is further increased, thermal runaway is easily caused, and safety accidents occur. For another example, if the operating temperature of the motor controller is too high, more heat is generated during high-power operation, so as to further raise the temperature, which is easy to cause accidents such as tube explosion and fire of the high-voltage power switch tube. For another example, if the temperature of the motor is too high, the rare earth permanent magnet material in the permanent magnet synchronous motor is easily demagnetized, so in the prior art, the maximum power limit of the motor is determined according to different temperatures. The SOC of the battery also limits the charge and discharge power of the battery, for example, the discharge power is large and the charge power is small when the SOC is high; conversely, when the SOC is low, the discharge power is small, and the charge power is large. The SOH of the battery has similar effects to the SOC, and the lower the SOH, the lower the charge/discharge power of the battery, in the case of the same SOC value.
S300: according to the required torque T of the power assemblyreqOutput speed n of power assemblycurCurrent gear ratio i of the first electric machine 101xCurrent gear ratio i of the second electric machine 102yFirst and second motor power limits, a first required torque T for the first motor 101 is determinedxAnd the first required torque T of the second electric machine 102y(ii) a This step may be accomplished by the motor torque distribution module.
Specifically, the motor driving torque distribution control logic of the motor torque distribution module is based on the following equation:
Figure BDA0002871155950000091
wherein, Tx＝Txv/(ix·μx)；
Ty＝Tyv/(iy·μy)；
The motor braking torque distribution control logic of the motor torque distribution module is based on the following equation:
Figure BDA0002871155950000101
wherein n iscurIs the power assembly output speed at the current vehicle speed, ixAnd iyThe current gear ratios, T, of the first and second electric machines 101 and 102, respectivelyxvThe first electric machine 101 translates to the required torque, T, on the output shaftyvIs the torque demand, mu, converted to the output shaft by the second electric machine 102xAnd muyMechanical transmission efficiency, μ, of the first and second electric machines 101, 102 at the current rotational speed and torque, respectivelymxAnd mumyThe motor system efficiencies of the first and second electric machines 101 and 102, respectively, at the current speed and torque.
S400: determining a second required torque of the first electric machine 101 and a second required torque of the second electric machine 102 based on the first electric machine torque rate-of-change calibrated quantity MAPC1 and the second electric machine torque rate-of-change calibrated quantity MAPC2, based on the current actual torque of the first electric machine 101 and the current actual torque of the second electric machine 102; this step may be accomplished by a torque vibration suppression module for the purpose of reducing vibration when the output torques of the two motors change. Where MAPC1 is the maximum amount of change in torque per unit time that is obtained by calibrating the torque rate limit MAP for the first electric machine 101 and MAPC2 is the maximum amount of change in torque per unit time that is obtained by calibrating the torque rate limit MAP for the second electric machine 102. The torque rate limits MAP for the two electric machines are related to the electrical and mechanical characteristics of the electric machines, the motor controllers, and the transmission components, as well as to the control algorithm, e.g., where the torque response is relatively slow, or where torque overshoot fluctuations occur, can affect the torque rate calibration for the two electric machines. The second required torques of the two electric machines are the corrected values of the first required torque described above, and if the first required torque results in a rate of change smaller than MAPC1 or MAPC2, then the second required torque is the first required torque; otherwise, the second requested torque is determined based on the maximum variation of the MAPC1 or the MAPC2 from a lookup table.
S500: the second required torque of the first motor 101 is taken as the required torque of the first motor 101, and the second required torque of the second motor 102 is taken as the required torque of the second motor 102.
Through the control method provided by the invention, the required torques of the two motors can be reasonably distributed and coordinated under different rotating speeds, so that the two motors can operate in a high-efficiency area, and the efficiency of the two motors is improved.
In order to ensure the continuity of the motor drive, the control method provided by the present invention preferably further comprises gear control logic of the first and second electric machines 101 and 102:
when the vehicle starts, the first motor 101 is in primary drive when being engaged with a first gear, and the second motor 102 is in auxiliary drive when being engaged with the first gear;
when the vehicle speed reaches a first gear-shifting vehicle speed calibration quantity MAPV1, the first motor 101 is driven by engaging the second gear, and the second motor 102 is kept at the first gear;
when the vehicle speed reaches the second gear-shifting vehicle speed calibration quantity MAPV2, the second motor 102 is in secondary gear to carry out main driving, and the first motor 101 is kept in secondary gear to carry out auxiliary driving.
The MAPV1 and the MAPV2 are shift speeds of the first motor 101 and the second motor 102, respectively, and can be determined in various ways, and mainly include: 1) judging through the vehicle speed; 2) judging according to the vehicle speed and the opening degree of an accelerator pedal; 3) and judging through the vehicle speed, the acceleration and the opening degree of an accelerator pedal. Through the gear control logic of the first electric machine 101 and the second electric machine 102, the gear shifting process of the two electric machines can be ensured to be smoother.
The power assembly can run in two modes, namely an economy mode and a power mode, wherein the economy mode is as follows: when the vehicle speed exceeds a certain calibrated rotating speed and the required torque of the motor of the auxiliary drive is 0, the motor is in neutral gear, when the required torque is not zero, the main drive motor increases the torque (according to the calibrated MAP) on the basis of the required torque obtained by checking the MAP, the torque requirement is supplemented, then the gear is engaged, and the auxiliary drive motor participates in the drive.
The power mode is as follows: whether the auxiliary drive motor or the main drive motor is connected with a corresponding gear, when the required torque of a certain motor is zero, the motor is in idle running.
It should be noted that, the control method provided by the present invention is also applicable to other pure electric power assemblies driven by two motors and each motor can be independently driven.
The previous description of the disclosed embodiments is provided to enable any person skilled in the art to make or use the present invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the generic principles defined herein may be applied to other embodiments without departing from the spirit or scope of the invention. Thus, the present invention is not intended to be limited to the embodiments shown herein but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims (10)

1. A pure electric power assembly is characterized by comprising a first motor, a second motor, a main gearbox and an auxiliary gearbox, wherein the main gearbox comprises a main gearbox output shaft, a first input shaft connected with the first motor and a second input shaft connected with the second motor, a first gear and a second gear are fixedly connected to the first input shaft and the second input shaft, the main gearbox further comprises a first gear and a second gear which are parallel to the first input shaft, the first gear and the second gear are sleeved on the first gear and the second gear, a gear shifting mechanism is arranged between the gear shifting mechanism and the second gear, a gear shifting output gear is fixedly connected to the first gear and the second gear, a main gearbox meshed with the gear shifting output gear is arranged at the input end of the output shaft of the main gearbox, the output end of the output shaft of the main gearbox is the input end of the auxiliary gearbox, and a speed reducing mechanism is arranged in the auxiliary gearbox.
2. A pure electric powertrain according to claim 1, characterised in that the reduction gear is a double layshaft reduction gear or a planet carrier reduction gear.
3. A pure electric powertrain according to claim 1, wherein the first engaging gear is fixedly connected with a first engaging gear ring, the second engaging gear is fixedly connected with a second engaging gear ring, and the gear shift mechanism includes a spline hub, a sliding sleeve, the first engaging gear ring and the second engaging gear ring.
4. A pure electric powertrain according to claim 3, characterized in that the first-gear engaging ring gear and the first-gear meshing gear are of an integral structure, and the second-gear engaging ring gear and the second-gear meshing gear are of an integral structure.
5. A pure electric powertrain according to claim 3, wherein the splined hubs are affixed to both the first shift shaft and the second shift shaft.
6. A pure electric powertrain according to any of claims 1-5, characterized in that the first electric machine is a permanent magnet synchronous machine and the second electric machine is a three-phase AC asynchronous machine.
7. A control method of a pure electric powertrain applied to the pure electric powertrain according to any one of claims 1 to 6, characterized in that the torque distribution of the first and second electric machines includes the steps of:
according to the opening degree of an accelerator pedal, the opening degree of a brake pedal and the vehicle weight,determining powertrain demand torque Treq；
Determining a first motor power limit value and a second motor power limit value according to the SOC of the power battery, the SOH of the power battery, the temperature of the first motor and a controller thereof, and the temperature of the second motor and a controller thereof;
determining first required torques of the first motor and the second motor according to the required torque of the power assembly, the output rotating speed of the power assembly, the current transmission ratio of the first motor, the current transmission ratio of the second motor, the power limit value of the first motor and the power limit value of the second motor;
determining second required torques of the first motor and the second motor based on the first motor torque change rate calibration quantity and the second motor torque change rate calibration quantity according to the current actual torque of the first motor and the current actual torque of the second motor;
the second required torques of the first and second electric machines are used as the required torques of the first and second electric machines.
8. The control method of a pure electric powertrain according to claim 7, further comprising a gear control logic of the electric machine:
when the vehicle starts, the first motor is in first gear engagement for main driving, and the second motor is in first gear engagement for auxiliary driving;
when the vehicle speed reaches a first gear shifting vehicle speed standard quantity, the first motor is driven by engaging two gears, and the second motor is kept at a first gear;
when the speed of a vehicle reaches a second gear shifting speed calibration quantity, the second motor is in secondary gear engagement to carry out main driving, and the first motor is kept in secondary gear to carry out auxiliary driving.
9. The control method of an electric-only powertrain according to claim 7, wherein the motor-drive torque distribution control logic, when determining the first required torques of the first and second electric machines, is based on the following equation:
Figure FDA0002871155940000021
Tx＝Txv/(ix·μx)；
Ty＝Tyv/(iy·μy)；
wherein n iscurIs the power assembly output speed at the current vehicle speed, ixAnd iyCurrent gear ratios, T, of the first and second electric machines, respectivelyxvThe first motor converts the torque demand, T, on the output shaftyvIs the torque demanded, mu, converted to the output shaft by the second motorxAnd muyMechanical transmission efficiency, mu, of the first and second electric machines at the current rotational speed and torque, respectivelymxAnd mumyThe motor system efficiencies of the first and second motors at the current rotational speed and torque, respectively.
10. The control method of an electric-only powertrain according to claim 7, wherein the motor braking torque distribution control logic, when determining the first required torques of the first and second electric machines, is based on the following equation:
Figure FDA0002871155940000031
wherein n iscurIs the power assembly output speed at the current vehicle speed, ixAnd iyCurrent gear ratios, T, of the first and second electric machines, respectivelyxvThe first motor converts the torque demand, T, on the output shaftyvIs the torque demanded, mu, converted to the output shaft by the second motorxAnd muyMechanical transmission efficiency, mu, of the first and second electric machines at the current rotational speed and torque, respectivelymxAnd mumyThe motor system efficiencies of the first and second motors at the current rotational speed and torque, respectively.
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