A torque distribution method for a dual-power drive system of an electric bus

Abstract

The present invention discloses a torque distribution method for a dual-power drive system of an electric bus, and relates to the technical field of pure electric buses. The dual-power drive system of the electric bus includes a first power battery, a first high-voltage distribution cabinet, a first motor controller, and a first motor connected in sequence, and also includes a second power battery, a second high-voltage distribution cabinet, a second motor controller, and a second motor connected in sequence; the first motor and the second motor rotate coaxially, and transmit the driving force to the front axle or the rear axle through a transmission shaft. The present invention is configured with two sets of independently operated drive systems, and the two motors in the drive system rotate coaxially, and the torques are superimposed on each other to jointly drive the front axle or the rear axle, thereby avoiding the phenomenon of overheating of a single motor caused by continuous large torque output, and ensuring the output balance of the two batteries, avoiding the situation of overloading of a single battery, thereby effectively extending the service life of the motor and the battery, and improving the stability and reliability of the drive system.

Description

Technical Field

[0001] The present invention relates to the technical field of pure electric buses, and in particular to a torque distribution method of a dual-power drive system of an electric bus. Background Art

[0002] Centralized drive is a common drive mode for traditional pure electric buses. Its power system generally includes batteries, motors, motor controllers and high-voltage distribution cabinets. The high-voltage distribution cabinet is connected between the battery and the motor controller to provide high-voltage power to the motor controller, thereby providing power to the entire vehicle through the motor. Existing electric buses generally only have one power system. When there is a torque demand, power can only be output through a single battery and driven by a single motor. However, when there is a continuous high torque demand, the motor may overheat or the battery balance may be affected, resulting in a reduction in the battery's allowable output power, and the vehicle's climbing performance and power are also affected. Summary of the invention

[0003] The present invention provides a torque distribution method for a dual-power drive system of an electric bus, the main purpose of which is to solve the above-mentioned problem.

[0004] The present invention adopts the following technical solution:

[0005] A dual-power drive system for an electric bus includes a first power battery, a first high-voltage distribution cabinet, a first motor controller and a first motor connected in sequence, and also includes a second power battery, a second high-voltage distribution cabinet, a second motor controller and a second motor connected in sequence; the first motor and the second motor rotate coaxially and transmit driving force to the front axle or the rear axle through a transmission shaft.

[0006] Furthermore, the electric dual-power drive system also includes a third high-voltage distribution cabinet arranged between the first high-voltage distribution cabinet and the second high-voltage distribution cabinet, and a first high-voltage switching switch and a second high-voltage switching switch are respectively provided between the above-mentioned third high-voltage distribution cabinet and the first high-voltage distribution cabinet and the second high-voltage distribution cabinet.

[0007] Furthermore, the electric dual-power drive system also includes a vehicle controller, and the above-mentioned first power battery, first high-voltage distribution cabinet, first motor controller, second power battery, second high-voltage distribution cabinet, second motor controller and third high-voltage distribution cabinet are all communicatively connected with the vehicle controller.

[0008] Furthermore, the electric bus dual-power drive system also includes an accelerator pedal and a brake pedal electrically connected to the vehicle controller.

[0009] Furthermore, the first motor and the second motor are dual-stator single-rotor motors integrated in the same motor housing, and the first motor controller is electrically connected to the first stator of the dual-stator single-rotor motor, and the second motor controller is electrically connected to the second stator of the dual-stator single-rotor motor.

[0010] A torque distribution method for the dual-power drive system of an electric bus as described above comprises the following steps:

[0011] (1) The vehicle controller collects signals from the accelerator pedal and brake pedal and calculates the total motor required torque based on them;

[0012] (2) setting a first motor allocation coefficient and a second motor allocation coefficient according to a peak torque ratio of the first motor and the second motor, and calculating the first motor required torque and the second motor required torque in combination with the total motor required torque;

[0013] (3) determining whether it is necessary to correct the first motor required torque and the second motor required torque according to the SOC difference between the first power battery and the second power battery in the current state, and if necessary, correcting both according to a pre-set correction coefficient;

[0014] (4) obtaining the maximum allowable discharge power or the maximum allowable discharge current of the first power battery and the second power battery in the current state, and calculating the first motor limit torque and the second motor limit torque based on the maximum allowable discharge power or the maximum allowable discharge current of the first power battery and the second power battery;

[0015] (5) Determine the first motor requested torque based on the first motor required torque obtained in step (3) and the first motor limited torque obtained in step (4); determine the second motor requested torque based on the second motor required torque obtained in step (3) and the second motor limited torque obtained in step (4).

[0016] Furthermore, in step (3), if the SOC difference does not exceed the preset deviation range, there is no need to correct the first motor demand torque and the second motor demand torque; if the SOC difference exceeds the preset deviation range, the first motor demand torque is corrected according to a pre-set correction coefficient, and the total motor demand torque is subtracted from the corrected first motor demand torque to obtain the corrected second motor demand torque.

[0017] Furthermore, when the vehicle is in a braking state, if the SOC difference exceeds the preset deviation range, the correction coefficient gradually decreases as the SOC difference increases; when the vehicle is in a driving state, if the SOC difference exceeds the preset deviation range, the correction coefficient gradually increases as the SOC difference increases.

[0018] Furthermore, the preset deviation range of the SOC difference between the first power battery and the second power battery is -5~5.

[0019] Furthermore, in step (5), the first motor required torque and the first motor limited torque are compared, and the minimum value of the two is taken as the first motor requested torque; the second motor required torque and the second motor limited torque are compared, and the minimum value of the two is taken as the second motor requested torque.

[0020] Compared with the prior art, the present invention has the following beneficial effects:

[0021] 1. The present invention is equipped with two sets of independently operated drive systems, and the two motors in the drive system rotate coaxially, and the torques are superimposed on each other to jointly drive the front axle or the rear axle, thereby avoiding the phenomenon of overheating of a single motor caused by continuous large torque output, and ensuring the output balance of the two batteries to avoid the overload of a single battery, thereby effectively extending the service life of the motor and battery and improving the stability and reliability of the drive system.

[0022] 2. The dual-power drive system provided by the present invention can promptly switch to a fault-free power battery and motor for use in conjunction with each other when a cross fault occurs, thereby ensuring uninterrupted output of the vehicle power supply system and avoiding the phenomenon of the vehicle being unable to operate due to a single drive system failure.

[0023] 3. The torque distribution method provided by the present invention can adjust and distribute the torque of the two motors in combination with the SOC difference of the two power batteries. When the SOC of the two power batteries deviates, the power battery with a higher SOC can output a higher power, and the power battery with a lower SOC can recover a higher braking power, thereby ensuring the balance of the SOC system of the two battery sets. When continuous high torque output is required, it can be shared by the two motors, which can ensure the power output, prevent the motor from overheating, and ensure that the output of the two power batteries is balanced and will not be in an overloaded state.

[0024] 4. The torque distribution method provided by the present invention utilizes sub-modes to perform real-time state tracking, which facilitates confirmation of whether the control is executed according to a predetermined process, simplifies the control method, and improves control efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 It is a structural schematic diagram of the present invention.

[0026] Figure 2 It is a schematic diagram of the whole vehicle control of the present invention.

[0027] Figure 3 It is a torque distribution flow chart of the present invention.

[0028] Figure 4 Schematic diagram of the correction coefficient (brake torque ratio) and SOC deviation under braking state.

[0029] Figure 5 Schematic diagram of the correction coefficient (driving torque ratio) and SOC deviation under driving state. DETAILED DESCRIPTION

[0030] The specific implementation of the present invention is described below with reference to the accompanying drawings. In order to fully understand the present invention, many details are described below, but for those skilled in the art, the present invention can be implemented without these details.

[0031] Reference Figure 1 , a dual-power drive system for an electric bus, comprising a first power battery 101, a first high-voltage distribution cabinet 102, a first motor controller 103 and a first motor 104 connected in sequence, and also comprising a second power battery 201, a second high-voltage distribution cabinet 202, a second motor controller 203 and a second motor 204 connected in sequence; the first motor 104 and the second motor 204 rotate coaxially, and transmit the driving force to the rear axle through a transmission shaft 300. The present invention is equipped with two sets of independently operated batteries, motors and motor controllers, and the two motors rotate coaxially, and the torques are superimposed on each other to jointly drive the rear axle, thereby avoiding the phenomenon of overheating of a single motor due to continuous large torque output, and ensuring the balance of the output of the two batteries, avoiding the situation of overloading of a single battery, effectively extending the service life of the motor and battery, and improving the stability and reliability of the drive system.

[0032] Reference Figure 1 , the drive system also includes a third high-voltage distribution cabinet 700 disposed between the first high-voltage distribution cabinet 102 and the second high-voltage distribution cabinet 202, and a first high-voltage switching switch K1 and a second high-voltage switching switch K2 are respectively disposed between the third high-voltage distribution cabinet 700 and the first high-voltage distribution cabinet 102 and the second high-voltage distribution cabinet 202. When a cross fault occurs, for example, when the first power battery 101 and the second motor 204 or the second motor controller 203 are simultaneously faulty, the first high-voltage switching switch K1 and the second high-voltage switching switch K2 can be closed, and the second power battery 201 can be controlled to supply power to the first motor 104, thereby achieving uninterrupted output of the vehicle power supply system and ensuring normal operation of the vehicle. When the second power battery 201 and the first motor 104 or the first motor controller 103 are simultaneously faulty, the same approach can be adopted to enable the first power battery 101 to supply power to the second motor 204. It can be seen from this that the dual-power drive system provided by the present invention can promptly switch to fault-free power batteries and motors for use in conjunction with each other when a cross fault occurs, thereby ensuring uninterrupted output of the vehicle's power supply system and avoiding the phenomenon of the vehicle being unable to operate due to a single drive system failure.

[0033] Reference Figure 1The drive system further includes a vehicle controller 400, and the first power battery 101, the first high-voltage distribution cabinet 102, the first motor controller 103, the second power battery 201, the second high-voltage distribution cabinet 202, the second motor controller 203 and the third high-voltage distribution cabinet 700 all communicate with the vehicle controller 400. During operation, the vehicle controller 400 detects the working status of each component in real time, and controls the opening and closing of the first high-voltage switching switch K1 and the second high-voltage switching switch K2 through the third high-voltage distribution cabinet 700.

[0034] Reference Figure 1 The driving system further includes an accelerator pedal 500 and a brake pedal 600 electrically connected to the vehicle controller 400. During operation, the vehicle controller 400 collects signals of the driver's intention through the accelerator pedal 500 and the brake pedal 600, and thereby performs basic control on the first motor controller 103 and the second motor controller 203, thereby achieving torque distribution.

[0035] Reference Figure 1 As a preferred solution, the first motor 104 and the second motor 204 are dual-stator single-rotor motors integrated in the same motor housing, and the first motor controller 103 is electrically connected to the first stator of the dual-stator single-rotor motor, and the second motor controller 203 is electrically connected to the second stator of the dual-stator single-rotor motor. The dual-stator single-rotor motor has the advantages of simple structure, stable and reliable operation, small size, high power and low overall loss. Its specific structure and working principle belong to the prior art, so it will not be repeated here.

[0036] Reference Figures 2 to 5 , a torque distribution method for a dual-power drive system of an electric bus, comprising the following steps:

[0037] 1. Vehicle operation process (refer to Figure 2 )

[0038] Initially, the vehicle controller 400 determines whether the vehicle is Ready (no serious faults). If so, it enters sub-mode 1, i.e., standby mode, and enters sub-mode 2, Ready mode, when it determines that the handbrake is released and the door is closed. Then it detects whether the gear is in D gear or R gear. If so, it enters sub-mode 3, Run mode, and waits for the driver's intention to perform driving or braking control.

[0039] 2. Braking control process (refer to Figure 3 and Figure 4 )

[0040] 2.1. After entering the RUN mode, when the vehicle controller 400 detects a brake signal, the vehicle enters sub-mode 9. The vehicle controller 400 calculates the total motor required braking torque according to the opening value of the brake pedal 600, and calculates the SOC difference between the first power battery 101 and the second power battery 201 in the current state (Diff_SOC = SOC1-SOC2). If the SOC difference is within the preset deviation range, the vehicle enters sub-mode 10. If the SOC difference exceeds the preset deviation range, the vehicle enters sub-mode 11.

[0041] 2.2. When entering sub-mode 10, the first motor allocation coefficient and the second motor allocation coefficient are set according to the peak torque ratio of the first motor 104 and the second motor 204, and the first motor allocation coefficient and the second motor allocation coefficient are respectively multiplied by the total motor required braking torque to obtain the first motor required torque and the second motor required torque; when entering sub-mode 11, the first motor required torque is multiplied by a preset correction coefficient on the basis of sub-mode 10 to obtain the corrected first motor required torque, and then enter sub-mode 12, subtract the corrected first motor required torque from the total motor required braking torque to obtain the corrected second motor required torque. Figure 4 As shown, when the vehicle is in a braking state, the preset SOC difference has a deviation range of -5 to 5. If the SOC difference exceeds the preset deviation range, the correction coefficient gradually decreases as the SOC difference increases. When the SOC difference increases from -30 to -5, the correction coefficient decreases from 1.3 to 1, and when the SOC difference increases from 5 to 30, the correction coefficient decreases from 1 to 0.7. In this way, when the SOC1 of the first power battery 101 is small, it can be responsible for returning more electricity, and the second power battery 201 can be responsible for returning less electricity; when the SOC1 of the first power battery 101 is high, it can be responsible for returning less electricity, and the second power battery 201 can be responsible for returning more electricity, thereby ensuring the SOC balance of the two sets of power batteries and preventing a single power battery from being in an overload condition.

[0042] 2.3. Then enter sub-mode 13, the vehicle controller 400 obtains the maximum allowable discharge power or the maximum allowable discharge current of the first power battery 101 and the second power battery 201 in the current state, and calculates the first motor limit torque and the second motor limit torque based on this; compares the first motor demand torque and the first motor limit torque, and takes the minimum value of the two as the first motor request torque; compares the second motor demand torque and the second motor limit torque, and takes the minimum value of the two as the second motor request torque; finally enters sub-mode 14, the vehicle controller 400 sends the first motor request torque and the second motor request torque to the first motor controller 103 and the second motor controller 203 for execution respectively.

[0043] 3. Drive control process (refer to Figure 3 and Figure 5 )

[0044] 3.1. After entering the RUN mode, if the vehicle controller 400 does not detect a brake signal, the vehicle enters sub-mode 4 and detects in real time whether there is a throttle signal. If a throttle signal is detected, the vehicle enters sub-mode 5. The vehicle controller 400 calculates the total motor required driving torque according to the opening value of the accelerator pedal 500, and calculates the SOC difference between the first power battery and the second power battery in the current state (Diff_SOC = SOC1-SOC2). If the SOC difference is within the preset deviation range, the vehicle enters sub-mode 6. If the SOC difference exceeds the preset deviation range, the vehicle enters sub-mode 7.

[0045] 3.2. When entering sub-mode 6, the first motor allocation coefficient and the second motor allocation coefficient are set according to the peak torque ratio of the first motor 104 and the second motor 204, and the first motor allocation coefficient and the second motor allocation coefficient are multiplied by the total motor required driving torque to obtain the first motor required torque and the second motor required torque; when entering sub-mode 7, the first motor required torque is multiplied by the preset correction coefficient on the basis of sub-mode 6 to obtain the corrected first motor required torque, and then enter sub-mode 8, subtract the corrected first motor required torque from the total motor required driving torque to obtain the corrected second motor required torque. Figure 5 As shown, when the vehicle is in a driving state, the preset SOC difference deviation range is between -5 and 5. If the SOC difference exceeds the preset deviation range, the correction coefficient gradually increases with the increase of the SOC difference. When the deviation increases from -30 to -5, the correction coefficient increases from 0.7 to 1, and when the deviation increases from 5 to 30, the correction coefficient increases from 1 to 1.3. In this way, when the SOC1 of the first power battery 101 is small, it can be made to output a smaller current, and the second power battery 201 can be responsible for outputting a larger current; when the SOC1 of the first power battery 101 is high, it can be made to output a larger current, and the second power battery 201 can be responsible for outputting a smaller current, thereby ensuring the SOC balance of the two power batteries and preventing a single power battery from being in an overload condition.

[0046] 3.3. Then enter sub-mode 13, the vehicle controller 400 obtains the maximum allowable discharge power or the maximum allowable discharge current of the first power battery 101 and the second power battery 201 in the current state, and calculates the first motor limit torque and the second motor limit torque based on this; compares the first motor demand torque and the first motor limit torque, and takes the minimum value of the two as the first motor request torque; compares the second motor demand torque and the second motor limit torque, and takes the minimum value of the two as the second motor request torque; finally enters sub-mode 14, the vehicle controller 400 sends the first motor request torque and the second motor request torque to the first motor controller 103 and the second motor controller 203 for execution respectively.

[0047] The above is only a specific implementation of the present invention, but the design concept of the present invention is not limited thereto. Any non-substantial changes to the present invention using this concept shall be deemed as an infringement of the protection scope of the present invention.

Claims

1. A torque distribution method for a dual-power drive system of an electric bus, characterized in that: The dual-power drive system of the electric bus includes a first power battery, a first high-voltage distribution cabinet, a first motor controller and a first motor connected in sequence, and also includes a second power battery, a second high-voltage distribution cabinet, a second motor controller and a second motor connected in sequence; the first motor and the second motor rotate coaxially and transmit the driving force to the front axle or the rear axle through a transmission shaft; also includes a vehicle controller, the first power battery, the first high-voltage distribution cabinet, the first motor controller, the second power battery, the second high-voltage distribution cabinet, the second motor controller and the third high-voltage distribution cabinet are all connected to the vehicle controller for communication; also includes an accelerator pedal and a brake pedal electrically connected to the vehicle controller; The torque distribution method comprises the following steps: (1) The vehicle controller collects signals from the accelerator pedal and brake pedal and calculates the total motor required torque based on them; (2) setting a first motor allocation coefficient and a second motor allocation coefficient according to a peak torque ratio of the first motor and the second motor, and calculating the first motor required torque and the second motor required torque in combination with the total motor required torque; (3) judging whether it is necessary to correct the first motor torque and the second motor torque according to the SOC difference between the first power battery and the second power battery in the current state, and if necessary, correcting both according to a preset correction coefficient; in this step, if the SOC difference does not exceed the preset deviation range, it is not necessary to correct the first motor torque and the second motor torque; If the SOC difference exceeds the preset deviation range, the first motor required torque is corrected according to a preset correction coefficient, and the corrected first motor required torque is subtracted from the total motor required torque to obtain a corrected second motor required torque; When the vehicle is in a braking state, if the SOC difference exceeds the preset deviation range, the correction coefficient gradually decreases as the SOC difference increases; when the vehicle is in a driving state, if the SOC difference exceeds the preset deviation range, the correction coefficient gradually increases as the SOC difference increases; (4) obtaining the maximum allowable discharge power or the maximum allowable discharge current of the first power battery and the second power battery in the current state, and calculating the first motor limit torque and the second motor limit torque based on the maximum allowable discharge power or the maximum allowable discharge current of the first power battery and the second power battery; (5) Determine the first motor requested torque based on the first motor required torque obtained in step (3) and the first motor limited torque obtained in step (4); determine the second motor requested torque based on the second motor required torque obtained in step (3) and the second motor limited torque obtained in step (4).

2. The torque distribution method of the dual-power drive system of an electric bus as claimed in claim 1, characterized in that: It also includes a third high-voltage distribution cabinet arranged between the first high-voltage distribution cabinet and the second high-voltage distribution cabinet, and a first high-voltage switching switch and a second high-voltage switching switch are respectively provided between the third high-voltage distribution cabinet and the first high-voltage distribution cabinet and the second high-voltage distribution cabinet.

3. The torque distribution method of the dual-power drive system of an electric bus as claimed in claim 1, characterized in that: The first motor and the second motor are dual-stator single-rotor motors integrated in the same motor housing, and the first motor controller is electrically connected to the first stator of the dual-stator single-rotor motor, and the second motor controller is electrically connected to the second stator of the dual-stator single-rotor motor.

4. The torque distribution method of the dual-power drive system of an electric bus as claimed in claim 1, characterized in that: The preset deviation range of the SOC difference between the first power battery and the second power battery is -5~5.

5. The torque distribution method of the dual-power drive system of an electric bus as claimed in claim 1, characterized in that: In step (5), the first motor required torque and the first motor limited torque are compared, and the minimum value of the two is taken as the first motor requested torque; the second motor required torque and the second motor limited torque are compared, and the minimum value of the two is taken as the second motor requested torque.

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