A multi-hub motor integrated modulation drive system and control method thereof

Abstract

The present invention discloses an integrated modulation drive system for multiple wheel hub motors of an electric vehicle and a control method thereof. The drive system consists of a vehicle controller, two integrated drivers with the same structure, and a multi-mode arbitrator. Each integrated driver consists of an integrated modulation controller and six half-bridge arm group drivers connected in series. The output end of the six half-bridge arm group driver in each integrated driver is connected to the two wheel hub motors on the corresponding side of the vehicle. Based on torque control, the two wheel hub motors on the same side of a distributed drive vehicle are used as an integrated system. Direct coordinated driving of the four wheel hub motors of the distributed drive electric vehicle is achieved through the two integrated drivers, and its integrated spatial voltage vector diagram is constructed. The two originally independent wheel hub motors are comprehensively considered, effectively sharing the computing load of the upper vehicle controller, taking into account the economy and overall efficiency of the electric vehicle, and comprehensively improving the handling performance of the electric vehicle under variable working conditions.

Description

Technical Field

[0001] The present invention relates to a multi-hub motor drive system, belongs to the field of multi-hub motor coordinated control, and is applied to distributed electric vehicles, specifically a distributed multi-hub motor drive system for electric vehicles and a control method thereof. Background Art

[0002] In recent years, the rapid development of electric vehicle powertrains has opened up broad prospects for improving the efficient driving performance and economic efficiency of electric vehicles, thanks to the advantages of distributed drive systems, such as high reliability, fast response, short drive chains, uniform tire adhesion distribution, and independent four-wheel control. Currently, effectively utilizing advanced intelligent control algorithms to achieve coordinated control of the four drive motors requires not only high computing performance from the upper-level vehicle controller, but also multi-processor redundancy and highly autonomous decision-making capabilities at the motor controller level to effectively improve control system reliability. This control structure has become the mainstream architecture for distributed drive electric vehicles.

[0003] As the main drive motor of the distributed drive system, the hub motor has the advantages of large torque, fast torque response, high drive efficiency, and no reduction mechanism. These advantages are conducive to the full electrification of the electric vehicle chassis and facilitate flexible control in the lateral, longitudinal and yaw directions. At present, the hub motor has been widely used in the electric vehicle drive system. However, the high flexibility of the hub motor also places high demands on the coordinated control of distributed electric vehicles driven by multiple hub motors. When electric vehicles face complex and changeable working conditions, they are easily affected by parameter perturbations between internal drive motors and external load disturbances. Therefore, the distributed drive system is required to respond to the drive requirements of each hub motor and to achieve coordinated control of multiple motors to reduce the slip and drag of the vehicle drive wheels and improve the smooth handling of the electric vehicle.

[0004] Currently, the four-wheel coordinated control architecture of distributed drive electric vehicles uses a vehicle controller as the master controller, four motor controllers, and four actuators as slave controllers, and designs the chassis control architecture in a top-down layered manner. For example, Chinese Patent Publication No. CN117962576A mentions a distributed drive electric tractor and a coordinated control method, which uses a controller to coordinate the output torque of four drive motors, and then uses four distributed motor controllers to receive torque signals, thereby directly driving the four drive motors, ensuring that the tractor obtains optimal power output in various operating conditions and road loads, effectively improving system efficiency and stability. However, there are problems with this: the number of controllers in the motor control layer is redundant, the optical fiber communication line is long, resulting in low communication transmission efficiency, the number of controllers is redundant, and there is internal communication coupling disturbance. Chinese patent publication CN109878348A proposes a method for distributed drive of electric vehicles on both front and rear axles. This method uses a pitch motion controller to receive external characteristic curves collected by an accelerator pedal analysis unit to determine the total required drive torque. Model predictive control is then used to calculate the required torque for each drive motor. The motor controller then receives these torque signals to control the drive motors on both axles. However, this method does not consider the internal control flow of the motor controller and the coordination algorithm within the motor controller to reduce the computational load on the upper-level controller. Summary of the Invention

[0005] The purpose of the present invention is to overcome the shortcomings of the prior art and propose an integrated modulation drive system for multiple hub motors to reduce the redundant number of motor controllers and actuators and the length of communication optical fibers, thereby improving the vehicle's optical fiber transmission efficiency. A control method for the drive system is also proposed to integrate the control and drive of multiple hub motors. Through the integrated driver, the coordinated control of multiple hub motors under variable operating conditions is achieved, effectively sharing the computing load of the upper-level vehicle controller, and adapting to the control requirements of distributed electric vehicles in complex road driving conditions.

[0006] To achieve the above objectives, the present invention adopts a technical solution for a multi-wheel hub motor integrated modulation drive system: the system comprises a vehicle controller, two integrated drivers with the same structure, and a multi-mode arbitrator. Each integrated driver is composed of an integrated modulation controller and six half-bridge arm group drivers connected in series. The output ends of the six half-bridge arm group drivers in each integrated driver are connected to the two wheel hub motors on the corresponding side of the vehicle.

[0007] The vehicle controller takes the actual speed of the four wheel hub motors and the driver's desired speed as input, and outputs four desired speeds and four electromagnetic torque given values ​​of the four wheel hub motors;

[0008] The desired rotational speeds of the four wheel hub motors are input into a multi-mode arbitrator for motion mode determination, and motion mode signals for straight-line or turning conditions on both sides of the vehicle are obtained. The motion mode signals, the desired rotational speeds, and the electromagnetic torque set values ​​are respectively input into the integrated modulation controller on the corresponding side of the vehicle;

[0009] Each integrated modulation controller includes a modulation hysteresis comparator, a torque and flux observer, an integrated sector judge and a multi-operating-state multi-voltage vector integrated modulation algorithm controller. Each torque and flux observer obtains the feedback flux of the two wheel hub motors on the same side, the flux of the feedback flux in the two-phase stationary coordinate system αβ and the electromagnetic torque feedback value T eb , the magnetic flux of the two-phase stationary coordinate system αβ and the motion mode on the same side are judged in real time by the integrated sector judger to determine the current sector signal;

[0010] The modulation hysteresis comparator outputs the flux modulation value and torque modulation value according to the flux difference and electromagnetic torque of the two motors on the same side;

[0011] The multi-voltage vector integrated modulation algorithm controller takes the flux modulation value, torque modulation value, sector signal, motion mode, expected speed and actual speed of the two motors on the same side as input, selects the optimal voltage combination vector, and outputs the corresponding duty cycle to each bridge arm of the six-half-bridge bridge arm group driver to achieve coordinated drive of the two hub motors on the same side.

[0012] The technical solution of a control method of a multi-hub motor integrated modulation drive system of the present invention includes the following steps:

[0013] Step 1): Model the hub motor on the same side and construct its integrated spatial voltage vector diagram:

[0014] Step 2): establishing a multi-voltage vector integrated modulation switch table based on the integrated space voltage vector diagram, dividing the space voltage vector plane into 12 sectors based on the space voltage vector diagram, using 16 groups of combinations formed by any pairwise combination of the flux modulation values ​​and the torque modulation values ​​as voltage vector selection rules, to form a multi-voltage vector integrated modulation switch table; based on the multi-voltage vector integrated modulation switch table, forming a frequency ratio-based and virtual vector-based switch table;

[0015] Step 3): Sampling the actual speed and three-phase current of the hub motor, based on the six-dimensional transformation matrix formula, the input of the torque and flux observer is the dq axis current, the feedback flux of the output hub motor, and its flux and electromagnetic torque feedback value in the two-phase stationary coordinate system αβ obtained through the six-dimensional transformation matrix;

[0016] Step 4): The integrated sector determiner selects a corresponding sector division method according to the switch table corresponding to the motion mode output by the multi-mode arbitrator and determines the corresponding sector signal;

[0017] Step 5): The multi-condition multi-voltage vector integrated modulation algorithm controller selects the corresponding switch table according to the motion mode signal. When the motion mode is 1, the frequency ratio-based switch table is selected, and the actual speed and expected speed of the hub motor, the sector signal, and the torque and flux modulation signal of the hub motor are used as input to output the optimal voltage vector; when the motion mode is 0, the virtual vector-based switch table is selected, and the sector signal and the torque and flux modulation signal of the hub motor are used as input to output the optimal voltage vector.

[0018] The beneficial effects of the present invention are:

[0019] (1) The present invention designs an integrated modulation drive system that realizes the coordinated control of multiple hub motors through a vehicle controller, a multi-mode arbitrator and two integrated drivers. Compared with the existing system of four hub motor drivers and four actuators, the number of controllers is reduced by half. At the same time, the number of actuators is reduced by using a six-half-bridge arm group driver, thereby effectively reducing the redundancy of the motor controllers and actuators, thereby reducing the redundancy and the impact of internal coupling disturbances, reducing the length of the communication optical fiber, and improving the communication transmission efficiency.

[0020] (2) The present invention is based on torque control, and uses the two hub motors on the same side of the distributed drive vehicle as an integrated system. It realizes the direct coordinated drive of the four hub motors of the distributed drive electric vehicle through two integrated drivers. Combined with the motion mode signals received by each hub motor when the vehicle is running, the two hub motors are regarded as an integrated system, and their integrated spatial voltage vector diagram is constructed. The two originally independent hub motors are taken into consideration in a coordinated manner, and the coordinated control of multiple hub motors is realized through the integrated controller, which effectively improves the coordinated performance and effectively shares the computing load of the upper vehicle controller, taking into account the economy and overall efficiency of the electric vehicle, and comprehensively improving the handling performance of the electric vehicle under variable working conditions.

[0021] (3) The frequency ratio-based multi-voltage vector integrated modulation switch table algorithm in the present invention is based on the mapping relationship between the speed command of each hub motor and the voltage vector selection, combined with the integrated space voltage vector diagram, and uses speed synchronization as a constraint condition, which further improves the synchronization of multiple hub motors of distributed electric vehicles under linear working conditions.

[0022] (4) The multi-voltage vector integrated modulation switch table algorithm based on virtual vector in the present invention reconstructs the virtual voltage vector synthesized by the long vector and the middle vector, thereby reducing odd-order current harmonics and increasing the output voltage vector amplitude to improve the bus voltage utilization rate, further improving the economy of distributed electric vehicles and the handling stability in steering conditions.

[0023] (5) The integrated sector determiner in the present invention has corresponding different sector division methods with the switch table algorithm in the multi-operating-condition multi-voltage vector integrated modulation algorithm controller, so that the voltage vector selected according to the modulation signal in each sector of each switch table algorithm is unique and optimal, effectively realizing precise coordinated control.

[0024] (6) The present invention outputs the motion mode through a multi-mode arbitrator to select the optimal switch table that adapts to the working condition, thereby improving the adaptability of distributed electric vehicles to complex road driving conditions. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 This is a structural block diagram of a multi-hub motor integrated modulation drive system of the present invention;

[0026] Figure 2 for Figure 1 The structural block diagram of the integrated modulation controller-Ⅰ;

[0027] Figure 3 for Figure 2 Principle block diagram of the modulation algorithm of the multi-operating-condition and multi-voltage vector integrated modulation algorithm controller;

[0028] Figure 4 for Figure 1 Block diagram of the driving principle of the six-way half-bridge arm group driver-Ⅰ driving the hub motor-Ⅰ and hub motor-Ⅱ;

[0029] Figure 5 for Figure 2 The three-dimensional integrated space voltage vector diagram formed by the hub motor-Ⅰ and hub motor-Ⅱ;

[0030] Figure 6 for Figure 5 The top-down perspective forms an integrated spatial voltage vector diagram in the αβ plane of the two-phase stationary coordinate system;

[0031] Figure 7 for Figure 3 Voltage vector diagram of multi-voltage vector integrated modulation switch table algorithm based on virtual vector. DETAILED DESCRIPTION

[0032] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below with reference to the accompanying drawings and implementation examples. It should be understood that the specific examples described herein are only used to explain the present invention and are not intended to limit the present invention.

[0033] See also Figure 1 The present invention discloses an integrated modulation drive system for multiple in-wheel motors, comprising a vehicle controller, two integrated drivers, and a multi-mode arbiter. The output of the vehicle controller is connected to the inputs of the two integrated drivers and the multi-mode arbiter, respectively. The output of the multi-mode arbiter is connected to the two integrated drivers. The two integrated drivers share the same structure, each consisting of an integrated modulation controller and six half-bridge arm drivers connected in series. The output of one integrated driver is connected to each of the two in-wheel motors, thus achieving coordinated drive of the multiple in-wheel motors.

[0034] The four in-wheel motors are Wheel Hub Motor I, Wheel Hub Motor II, Wheel Hub Motor III, and Wheel Hub Motor IV. Wheel Hub Motor I and Wheel Hub Motor II represent the two in-wheel motors on the same side of a distributed drive electric vehicle, such as the left front wheel and left rear wheel, or the right front wheel and right rear wheel. Wheel Hub Motor III and Wheel Hub Motor IV represent the other in-wheel motors on the same side. The outputs of the six half-bridge arm group drivers in each integrated drive are connected to the two in-wheel motors on the corresponding side. That is, the outputs of the first integrated drive are connected to the two in-wheel motors on one side of the vehicle, and the outputs of the second integrated drive are connected to the two in-wheel motors on the other side of the vehicle.

[0035] The vehicle controller uses the actual speed of the four wheel hub motors ω ea ,ω eb ,ω ec ,ω ed and the driver's desired speed V d As input, output four desired speeds of the four hub motors and four electromagnetic torque reference values

[0036] Expected speed of the four wheel hub motors Input into the multi-mode arbitrator, the multi-mode arbitrator outputs two motion modes S on both sides of the vehicle aMode , S bMode Signal. Expected speed The motion mode is determined by the multi-mode arbitrator: when the desired speed of the hub motor-Ⅰ and hub motor-Ⅱ on one side of the vehicle is At the same time, it is identified that the hub motor-Ⅰ and hub motor-Ⅱ are in the linear working mode. At this time, the motion mode S output by the multi-mode arbitrator is aModeOutput is 1; when the desired speed of hub motor-Ⅰ and hub motor-Ⅱ If they are different, the working condition wheel hub motor-Ⅰ and wheel hub motor-Ⅱ are identified as the motion mode of the steering working condition. At this time, the multi-mode arbitrator outputs the motion mode S aMode The output is 0; similarly, when the desired output of the hub motor-Ⅲ and hub motor-Ⅳ on the other side of the vehicle is When the speeds are the same, the hub motor-III and hub motor-IV are identified as linear motion modes. At this time, the working mode of the multi-mode arbitrator is S bMode Output is 1; when the hub motor-Ⅲ and hub motor-Ⅳ are expected When the speeds are different, the wheel hub motor-III and wheel hub motor-IV are identified as the steering working mode. At this time, the multi-mode arbitrator outputs the motion mode S bMode The output is 0.

[0037] The sports mode S output by the multi-mode arbitrator aMode The signal input to the integrated modulation controller-Ⅰ in the first integrated drive is the desired speed of the hub motor-Ⅰ and hub motor-Ⅱ and electromagnetic torque given value It is also input into the integrated modulation controller-Ⅰ in the first integrated driver. Similarly, the motion mode S output by the multi-mode arbitrator bMode The signal input to the integrated modulation controller-Ⅱ in the second integrated drive is the desired speed of the hub motor-Ⅲ and hub motor-Ⅳ and electromagnetic torque given value It is also input into the integrated modulation controller-Ⅱ in the second integrated drive.

[0038] because Figure 1 In the control system block diagram, the structures of the integrated modulation controller-Ⅰ and the integrated modulation controller-Ⅱ, the six-half-bridge arm group driver-Ⅰ and the six-half-bridge arm group driver-Ⅱ are completely consistent. Therefore, the hub motor I and the hub motor II are used as the controlled objects as specific cases to further explain the drawings of the present invention in detail.

[0039] See also Figure 2 The structural block diagram of the integrated modulation controller-Ⅰ is shown in FIG. The integrated modulation controller-Ⅰ includes a modulation hysteresis comparator, a torque and flux observer, an integrated sector judge, a six-dimensional transformation matrix and a multi-operating-state multi-voltage vector integrated modulation algorithm controller. The integrated sector judge outputs the current sector S fr signal, the modulation hysteresis comparator outputs the flux modulation value ε ψ and torque modulation value ε TThe optimal voltage combination vector of the hub motor-Ⅰ and the hub motor-Ⅱ is selected by the multi-voltage vector integrated modulation algorithm controller, thereby outputting the corresponding duty cycle S to each bridge arm of the six-half-bridge bridge arm group driver. a ,S b ,S c ,S x ,S y ,S z The coordinated driving of hub motor-Ⅰ and hub motor-Ⅱ is achieved by the switching state.

[0040] Collect the three-phase current i of the hub motor-Ⅰ a ,i b ,i c and electrical angle θ a And the three-phase current i of the hub motor-Ⅱ x ,i y ,i z and electrical angle θ b , these currents and electrical angles are transformed by the six-dimensional transformation matrix to obtain the dq axis currents i of the two hub motors di ,i qi , i=a,b. The dq axis current i of the two hub motors di ,i qi Input torque and flux observer to obtain the feedback flux ψ of the two hub motors sa ,ψ sb , the feedback flux in the two-phase stationary coordinate system αβ is the flux ψ αi ,ψ βi And the electromagnetic torque feedback value T ea ,T eb The feedback flux in the two-phase stationary coordinate system αβ is αi ,ψ βi Input integrated sector judgement, sports mode S aMode The signal is also input into the integrated sector judgement device, which judges the current sector S in real time. fr Signal. The feedback flux ψ sa ,ψ sb and electromagnetic torque feedback value T ea ,T eb One-to-one correspondence with the set flux linkage value ψ* sa ,ψ* sb and the input electromagnetic torque given value Make the difference and obtain the flux difference △ψ between hub motor-Ⅰ and hub motor-Ⅱ a ,△ψ b and electromagnetic torque △T ea ,△T eb The modulation hysteresis comparator is based on the flux difference △ψa ,△ψ b and electromagnetic torque △T ea ,△T eb As input, the flux modulation value ε ψ Signal and torque modulation value ε T The signal is output. The multi-operating-state multi-voltage vector integrated modulation algorithm controller uses the flux modulation value ε ψ , torque modulation value ε T , Current sector S fr , Sport Mode S aMode , the expected speed of hub motor-Ⅰ and hub motor-Ⅱ Actual speed ω ea ,ω eb As input, the optimal voltage vector U of hub motor-Ⅰ and hub motor-Ⅱ is obtained. M .

[0041] See also Figure 3 The controller is based on a multi-voltage vector integrated modulation algorithm. It uses a frequency ratio-based multi-voltage vector integrated modulation switching table algorithm and a virtual vector-based multi-voltage vector integrated modulation switching table algorithm. The choice of the two switching table algorithms depends on the motion mode S input by the multi-mode arbitrator. aMode , when the sport mode S aMode =1, when the frequency ratio-based multi-voltage vector integrated modulation switch table algorithm is selected, at this time, the expected speed of the hub motor-Ⅰ and hub motor-Ⅱ Actual speed ω ea ,ω eb , Current sector S fr , flux modulation value ε ψ , torque modulation value ε T As input, the output is the optimal voltage vector U M , realizing the coordinated driving of the integrated system. aMode = 0, the multi-voltage vector integrated modulation switch table algorithm based on virtual vector is selected. At this time, the current sector S fr , flux modulation value ε ψ , torque modulation value ε T As input, the optimal voltage vector U can be output M , realizing the coordinated driving of the integrated system.

[0042] See also Figure 4 The six half-bridge arm group driver-Ⅰ shown in the figure is driven by the bus voltage U dcPower supply, six half-bridge arm group driver-Ⅰ drives hub motor-Ⅰ and hub motor-Ⅱ, where a, b, c bridge arm groups drive hub motor-Ⅰ, and x, y, z bridge arm groups drive hub motor-Ⅱ. Since the upper and lower switching devices of each bridge arm work in complementary conduction states, each bridge arm has two switch states, namely "0" state and "1" state, representing the bridge arm off state and the bridge arm on state respectively. Therefore, there are a total of 64 switch states, corresponding to 64 voltage vectors. Each voltage vector is represented by an octal number, and the corresponding binary number represents the switch state of the six half-bridge arm group driver-Ⅰ, for example, U 64 The switch states represented are: 110100, which correspond to the six bridge arms abcxyz from high to low.

[0043] See also Figure 5 The three-dimensional integrated space voltage vector diagram is shown in the figure, in which the α-axis, β-axis and γ-axis are perpendicular to each other in space, respectively serving as the horizontal axis, vertical axis and vertical axis of the space rectangular coordinate system to form an α-β-γ coordinate system. A space voltage vector diagram is constructed in the α-β-γ coordinate system, in which the γ-axis is the vertical axis with the magnetic flux rotating magnetic field coupling as the constraint condition. The two basic voltage vector diagrams in the α-β plane of the two-phase stationary coordinate system with a difference of 30° are connected to form a three-dimensional integrated space voltage vector diagram, and the hub motor-Ⅰ and hub motor-Ⅱ are interconnected to achieve coordinated control, in which the independent voltage vector of the hub motor-Ⅰ is The independent voltage vector of the hub motor-II is In addition to the six independent voltage vectors for each motor mentioned above, it also includes Four zero voltage vectors. No voltage is generated when the zero voltage vector acts.

[0044] See also Figure 6 shown Figure 5 The top view of the two-phase stationary coordinate system forms an integrated space voltage vector diagram in the α-β plane, which includes 12 non-zero original voltage vectors defined as U 01 (000001) = V 10 、U 02 (000010) = V6, U 03 (000011) = V8, U 04 (000100) = V2, U 05 (000101) = V 12 、U 06 (000110) = V4, U 10 (001000) = V9, U 20 (010000) = V5, U 30 (011000) = V7, U 40 (100000) = V1, U50 (110000) = V 11 、U 60 (110000)=V3, corresponding to 24 switch states. The 12 non-zero original vectors are combined in pairs.

[0045] See also Figure 7 The voltage vector diagram of the multi-voltage vector integrated modulation switch table algorithm based on the virtual vector shown in the figure contains a total of 12 virtual voltage vectors, and the amplitude of the virtual voltage vector is 0.571U dc , effectively improving the bus voltage utilization rate. 12 virtual voltage vectors are composed of a time of 0.578T s The long voltage vector and action time is 0.422T s The medium voltage vector composition, T s is the control period, U dc is the bus voltage amplitude of the six half-bridge arm group driver power supply. The specific composition of the virtual voltage vector is:

[0046] In addition, the internal structure and principle of the second integrated modulation controller-Ⅱ and the six-half-bridge arm group driver-Ⅱ controlled by the hub motor-Ⅲ and hub motor-Ⅳ are similar to Figures 2 to 7 Similarly, in the second integrated modulation controller-Ⅱ, the actual speed of the hub motor-Ⅲ and the hub motor-Ⅳ is ω ec ,ω ed and desired speed Three-phase current i' a ,i' b ,i' c ,i' x ,i' y ,i' z , feedback flux and its flux in the two-phase stationary coordinate system αβ, electromagnetic torque feedback value, torque and flux difference, electrical angle θ c ,θ d and Sport Mode S bMode It is replaced by the parameters corresponding to hub motor-III and hub motor-IV.

[0047] The control steps of the multi-hub motor integrated modulation control method, which includes an integrated modulation controller-I and a six-half-bridge arm group driver-I, are as follows:

[0048] Step 1: Modeling preprocessing of hub motor-I and hub motor-II: Hub motor-I and hub motor-II are considered as an integrated system, and their integrated space voltage vector diagram is constructed. At the same time, the six-dimensional transformation matrix formula of the integrated system is preset:

[0049] (1) The hub motor-Ⅰ and hub motor-Ⅱ are regarded as an integrated system. The three-phase winding offset angle of hub motor-Ⅰ and hub motor-Ⅱ is set to 30°, and their Clarke-Park six-dimensional transformation matrix is:

[0050]

[0051] The matrix T1 and matrix T2 are:

[0052]

[0053] Among them, θ a ,θ b They are the electrical angles of hub motor-Ⅰ and hub motor-Ⅱ respectively.

[0054] (2) Considering the coupling disturbance of hub motor-Ⅰ and hub motor-Ⅱ, with the coupling of magnetic flux rotating magnetic field as the constraint condition, the two basic voltage vector diagrams in the αβ plane of the two-phase stationary coordinate system with a difference of 30° are connected to form the following: Figure 5 The three-dimensional integrated space voltage vector diagram is shown in FIG, in which the α-axis, β-axis and γ-axis are perpendicular to each other in space, respectively serving as the horizontal axis, vertical axis and vertical axis of the space rectangular coordinate system, forming an α-β-γ coordinate system; and the top view of the three-dimensional integrated space voltage vector diagram forms an integrated space voltage vector diagram in the αβ plane of the two-phase stationary coordinate system, as shown in FIG. Figure 6 As shown, it includes 12 non-zero original voltage vectors U 01 (U 71 ), U 02 (U 72 ), U 03 (U 73 ), U 04 (U 74 ), U 05 (U 75 ), U 06 (U 76 ), U 10 (U 17 ), U 20 (U 27 ), U 30 (U 37 ), U 40 (U 47 ), U 50 (U 57 ), U 60 (U 67 ), corresponding to 24 switching states, which is characterized by one of the motor voltage vectors being a three-phase zero vector, that is, one of the motor switching states is 0 or 7, such as U 60 and U 67The voltage vectors corresponding to these two switching states are exactly the same.

[0055] (3) According to Figure 4 The six-half-bridge arm group driver shown has 64 switching states, and each switching state corresponds to 64 voltage vectors in the fundamental α1-β1 space voltage vector plane, which corresponds one-to-one to the voltage vector of the harmonic α5-β5 space voltage vector plane. The fundamental α1-β1 space voltage vector plane is an electromechanical energy conversion plane, and the α1 axis and the β1 axis are perpendicular to each other, serving as the horizontal axis and vertical axis of the rectangular coordinate system respectively. The harmonic α5-β5 space voltage vector plane is a non-electromechanical energy conversion plane, which generates harmonic components, and the α5 axis and the β5 axis are perpendicular to each other, also serving as the horizontal axis and vertical axis of the rectangular coordinate system. The above 64 voltage vectors include 12 non-zero original vectors, namely the above Figure 6 The non-zero original voltage vectors in the 12 original vectors are combined in pairs to form 36 voltage vectors in the fundamental wave α1-β1 space voltage vector plane. The synthesis rule is U xy =U x0 +U 0y , for example, U 64 Can be U 60 (U 67 ) and U 04 (U 74 ) synthesis; in addition, it also contains four zero voltage vectors at the origin: U 00 、U 07 、U 70 、U 77 The voltage vectors in the fundamental α1-β1 space voltage vector plane and the harmonic α5-β5 space voltage vector plane are mapped one by one. The 64 voltage vectors in the fundamental α1-β1 space voltage vector plane and the harmonic α5-β5 space voltage vector plane can be expressed as follows:

[0056]

[0057] Where S i =1, it means that the upper bridge arm of the i-th bridge arm of the six-half-bridge bridge arm group driver is turned on, and S i = 0, indicating that the lower bridge arm of the i-th bridge arm of the six-half-bridge bridge arm group driver is turned on, i = a, b, c, x, y, z, e jm Represents a unit vector with an angle of m degrees with the positive horizontal axis of the coordinate system; U dc is the bus voltage amplitude of the six half-bridge arm group driver power supply. Based on this, the 60 non-zero voltage vectors can be divided into four groups according to the amplitude, namely: long vector, medium vector, original vector, and short vector. The amplitudes of the four groups of vectors |v| L 、|v| M 、|v| O、|v| S They are:

[0058]

[0059] Step 2: Preset the multi-operating-condition multi-voltage vector integrated modulation algorithm controller of the integrated modulation controller-I: Based on the integrated spatial voltage vector diagram of step 1, establish a multi-voltage vector integrated modulation switch table, and based on this, preset a frequency ratio-based multi-voltage vector integrated modulation switch table and a virtual vector-based multi-voltage vector integrated modulation switch table. The selection of the two preset switch tables is based on the motion mode output by the multi-mode arbitrator:

[0060] (1) Combination Figure 5 and Figure 6 , divide the fundamental wave α1-β1 space voltage vector plane into 12 sectors, that is, starting from 0°, every 30° is a sector, and the flux modulation value ε output by the modulating hysteresis comparator is ψ , torque modulation value ε T The 16 groups of combinations formed by any two-by-two random combinations are used as voltage vector selection rules to form a multi-voltage vector integrated modulation switch table, as shown in Table 1.

[0061] Table 1 Multi-voltage vector integrated modulation switch table

[0062]

[0063] In Table 1, for example, at any time, the stator flux of the hub motor-Ⅰ and the hub motor-Ⅱ is in sector 1, and the modulation hysteresis comparator output signal ε T =11 and ε ψ =11, the output voltage vector is V3V4, that is, U 60 +U 06 =U 66 Voltage vector, to achieve the coordinated control of hub motor-Ⅰ and hub motor-Ⅱ. In addition, the flux modulation value ε ψ From left to right, it can be divided into the flux linkage signal ε of hub motor-Ⅰ and hub motor-Ⅱ ψ1 and ε ψ2 When the flux linkage signal is 1, it means that the stator flux linkage amplitude of the motor needs to be increased. When the flux linkage signal is 0, it means that the stator flux linkage amplitude of the motor needs to be reduced. For example, ε ψ =10 means ε ψ1 =1 and ε ψ2 =0; similarly, ε T The values ​​of can be divided into the torque signals ε of hub motor-Ⅰ and hub motor-Ⅱ in order from left to right. T1 and ε T2When the torque signal is 1, it means that the electromagnetic torque of the motor needs to be increased. When the flux signal is 0, it means that the electromagnetic torque of the motor needs to be reduced. For example, ε T =01 means ε T1 = 0 and ε T2 =1;

[0064] (2) Based on the multi-voltage vector integrated modulation switch table, a multi-voltage vector integrated modulation switch table based on frequency ratio with speed synchronization as the constraint condition is constructed for linear working conditions: According to the magnetic field coupling relationship of the hub motor, the synchronization performance is improved with the frequency ratio as the constraint condition, and a multi-voltage vector integrated modulation switch table algorithm based on frequency ratio is designed. First, the actual frequency ratio Δn and the expected frequency ratio Δn* of the hub motor-Ⅰ and the hub motor-Ⅱ are calculated:

[0065]

[0066]

[0067] Where, f a is the frequency of the hub motor-Ⅰ, f b is the frequency of hub motor-Ⅱ, p a is the number of pole pairs of the hub motor-Ⅰ, p b is the number of pole pairs of the hub motor-Ⅱ, ω ea and ω * ea are the actual speed and expected speed of the hub motor-Ⅰ collected by the rotary transformer used by the hub motor-Ⅰ, ω eb and ω * eb The actual and expected speeds of the hub motor II are captured by the resolver. The difference between the actual frequency ratio Δn and the expected frequency ratio Δn* of the hub motor I and II is calculated, and a tolerance value based on the frequency ratio is set. When the actual frequency ratio is less than the expected frequency ratio and outside the tolerance value, the output signal is 0, indicating that the dual-motor synchronization performance needs to be improved and a faster voltage vector is selected for output. The specific function form is as follows:

[0068]

[0069] Therefore, based on the frequency ratio function form, the multi-voltage vector integrated modulation switch table in Table 1 is improved, the voltage vector of the hub motor-II is kept unchanged, and the voltage vector of the hub motor-I is changed. The multi-voltage vector integrated modulation switch table algorithm based on the frequency ratio under the synchronous working condition is obtained, as shown in Table 2. In addition, in order to facilitate the regular form of the switch table, combined with Table 1, the 12 sector division method starts from 0°, and each 30° is a sector, V U Indicates that the voltage vector does not change:

[0070] Table 2 Multi-voltage vector integrated modulation switch table based on frequency ratio

[0071]

[0072] (3) However, for the voltage vectors selected in Tables 1 and 2, in addition to the long vector and the middle vector, they also include short vectors and original vectors. The existence of multi-amplitude vectors will reduce the bus voltage utilization rate and increase the odd harmonics of the hub motor current. Therefore, a multi-voltage vector integrated modulation switch table based on virtual vectors is constructed based on the principle of synthesizing virtual vectors with long vectors and middle vectors for steering conditions: the long vector and middle vector of the fundamental α1-β1 space voltage vector plane are selected, and according to the volt-second balance principle, 12 virtual voltage vectors are synthesized with the goal of eliminating odd harmonics. Therefore, the fundamental α1-β1 space voltage vector plane is divided into 12 sectors, starting from -15°, with each 30° as a sector. The synthesis principle of the 12 virtual voltage vectors is:

[0073]

[0074] Where, the amplitude of the synthetic virtual vector in the fundamental wave α1-β1 space voltage vector plane is |VV S1 |, the amplitude in the harmonic α5-β5 space voltage vector plane is |VV S5 |. K L and K M They are control period T s The duty cycle of the medium length vector and the medium vector, and satisfy: K M +K L =1. To eliminate odd-order current harmonics, we have |VV S5 |=0, the 12 virtual voltage vector amplitudes, the duty ratios of the long vector and the middle vector can be calculated:

[0075]

[0076] 12 virtual voltage vectors such as Figure 7 As shown, it consists of the following long vector and middle vector:

[0077]

[0078] Therefore, the multi-voltage vector integrated modulation switch table based on the virtual vector is obtained as shown in Table 3. In addition, K is defined as the sector. Combined with Table 1, ε is defined as ψV =1 means ε ψ1 =1 or ε ψ2 =1, define ε ψV =0 means ε ψ1 =0 or ε ψ2 =0,εTV =1 means ε T1 =1 or ε T2 =1,ε TV =0 means ε T1 =0 or ε T2 =0:

[0079] Table 3 Multi-voltage vector integrated modulation switch table based on virtual vector

[0080]

[0081] Step 3. Simultaneously with step 2, preset the integrated sector determiner of the integrated modulation controller-Ⅰ: based on the integrated spatial voltage vector diagram of step 1, divide the spatial voltage vector plane into 12 sectors, thereby presetting the corresponding sector division method according to the multi-voltage vector integrated modulation switch table selected according to the motion mode signal in step 2.

[0082] Step 4: Use the rotary transformer to sample and obtain the actual speed ω of the hub motor-Ⅰ and hub motor-Ⅱ ea ,ω eb The three-phase current i of the hub motor-Ⅰ and hub motor-Ⅱ is sampled by analog-digital converter respectively. a ,i b ,i c and i x ,i y ,i z .

[0083] Step 5. Torque and flux observer calculation of integrated modulation controller-Ⅰ: Based on the six-dimensional transformation matrix formula of the integrated system in step 1, the torque and flux observer inputs the quadrature and direct axis currents i of the integrated system obtained through the six-dimensional transformation matrix. di ,i qi , output hub motor-Ⅰ, hub motor-Ⅱ feedback flux ψ sa ,ψ sb And its direction vector magnetic flux ψ in the two-phase stationary coordinate system αβ plane αi ,ψ βi and the electromagnetic torque feedback value T of hub motor-Ⅰ and hub motor-Ⅱ ea ,T eb .

[0084] (1) The AC and DC axis currents of the integrated system formed by the hub motor-I and hub motor-II can be expressed as:

[0085] [i da i qa i db i qb ] T =T3s / 2s [i a i b i c i x i y i z ] T .

[0086] (2) The quadrature and direct axis feedback fluxes of hub motor-Ⅰ and hub motor-Ⅱ are:

[0087]

[0088] Among them L da , L qa is the direct-axis inductance and quadrature-axis inductance of the hub motor-Ⅰ, L db , L qb is the direct-axis inductance and quadrature-axis inductance of the hub motor-Ⅱ, ψ fa , ψ fb is the stator flux parameter of hub motor-Ⅰ and hub motor-Ⅱ; therefore, the amplitude of the feedback flux of hub motor-Ⅰ and hub motor-Ⅱ is:

[0089]

[0090] The direction vectors of the feedback flux of hub motor-Ⅰ and hub motor-Ⅱ in the αβ plane of the two-phase stationary coordinate system are:

[0091]

[0092] (3) Electromagnetic torque feedback value T of hub motor-Ⅰ and hub motor-Ⅱ ea , T eb It can be expressed as:

[0093]

[0094] Step 6: Modulation hysteresis comparator operation of integrated modulation controller-I: The modulation hysteresis comparator receives the electromagnetic torque difference △T between hub motor-I and hub motor-II ea ,△T eb and the flux difference △ψ a ,△ψ b The difference between the torque and flux set values ​​and the torque and flux feedback values ​​of hub motor I and hub motor II is:

[0095]

[0096] Where, is the electromagnetic torque given value of hub motor I and hub motor II, is the given value of the flux linkage of hub motor I and hub motor II, Tea 、T eb is the electromagnetic torque feedback value of hub motor I and hub motor II obtained by the torque observer, ψ sa , ψ sb is the feedback flux value of hub motor I and hub motor II obtained by the flux observer.

[0097] (1) In order to effectively regulate the flux and torque loop, the modulation hysteresis comparator modulates the electromagnetic torque difference △T ea ,△T eb and the flux difference △ψ a ,△ψ b Compare with the upper and lower limits of the modulation hysteresis comparator to determine the signal that needs to increase or decrease the torque or flux, and its flux modulation value ε ψ Signal and torque modulation value ε T The signal principles are:

[0098]

[0099] Where, ε T =11 means that the electromagnetic torque of hub motor I and hub motor II needs to be increased, ε T =10 means that the electromagnetic torque of the hub motor I needs to be increased and the electromagnetic torque of the hub motor II needs to be reduced, ε T =01 means that the electromagnetic torque of the hub motor I needs to be reduced and the electromagnetic torque of the hub motor II needs to be increased, ε T =00 means that the electromagnetic torque of hub motor I and hub motor II needs to be reduced. ψ =11 means that the flux linkage of hub motor I and hub motor II needs to be increased, ε ψ =10 means that the flux linkage of hub motor I needs to be increased and the flux linkage of hub motor II needs to be reduced, ε ψ =01 means that the flux linkage of hub motor I needs to be reduced and the flux linkage of hub motor II needs to be increased, ε ψ =00 means that the magnetic flux of hub motor I and hub motor II needs to be reduced.

[0100] At the same time as step 7 and step 6, the integrated sector judge of the integrated modulation controller-I operates: the integrated sector judge selects the corresponding sector division method according to the switch table corresponding to the motion mode output by the multi-mode arbitrator, and judges the corresponding sector signal by the feedback magnetic flux of the hub motor-I and the hub motor-II obtained in step 5 in the αβ plane direction vector of the two-phase stationary coordinate system.

[0101] Step 8. Integrated modulation controller-Ⅰ multi-operating condition multi-voltage vector integrated modulation algorithm controller operation: the multi-operating condition multi-voltage vector integrated modulation algorithm selects the corresponding switch table according to the motion mode signal. When the motion mode S aMode=1, when the frequency ratio-based multi-voltage vector integrated modulation switch table algorithm is selected, the actual speed and expected speed of the hub motor-Ⅰ and hub motor-Ⅱ, the sector signal obtained in step 7, and the torque and flux modulation signal of the hub motor-Ⅰ and hub motor-Ⅱ obtained in step 6 are used as inputs, and the optimal voltage vector is output to realize the coordinated drive of the integrated system; when the motion mode S aMode =0, the multi-voltage vector integrated modulation switch table algorithm based on the virtual vector is selected. The sector signal obtained in step 7 and the torque and flux modulation signals of the hub motor-I and hub motor-II obtained in step 6 are used as inputs to output the optimal voltage vector to achieve coordinated drive of the integrated system.

[0102] (1) When the sport mode S aMode =1, select the optimal voltage vector U based on Table 1 and Table 2 M ; When the sport mode S aMode = 0, select the optimal voltage vector U based on Table 3 M ; According to the switch state corresponding to each voltage vector, output S a , S b , S c , S x , S y , S z The duty cycle of the six bridge arms realizes the driving of the six half-bridge bridge arm group drivers.

[0103] In addition, the hub motor-III and the hub motor-IV are also regarded as an integrated system, which is controlled by the integrated modulation controller-II and the six-half-bridge arm group driver-II. The control process of the integrated modulation control method of the hub motor-III and the hub motor-IV is exactly the same as the above steps. Among them, the integrated spatial voltage vector diagram, six-dimensional transformation matrix, the preset switch table in the multi-working condition multi-voltage vector integrated modulation algorithm controller of the integrated modulation controller-II, the sector division method in the integrated sector judgement and the modulation hysteresis comparator output rule are exactly the same as those of the integrated modulation controller-I. In the integrated modulation controller-II, the actual speed ω of the hub motor-III and the hub motor-IV is exactly the same as that of the integrated modulation controller-II. ec ,ω ed , expected speed Three-phase current i' a , i' b , i' c , i' x , i' y , i' z , the amplitude of the feedback flux ψ sc , ψ sd 、The direction vector ψ' of the feedback flux in the α-β plane of the two-phase stationary coordinate system αi , ψ' βi , electromagnetic torque feedback value Tec , T ed , torque and flux difference △T ec ,△T ed ,△ψ c ,△ψ d , frequency f c , f d , pole pair number p c , p d 、Electrical angle θ c ,θ d , Sport Mode S bMode It replaces the actual speed and expected speed of the original hub motor-Ⅰ and hub motor-Ⅱ, the three-phase current, the amplitude of the feedback flux and its direction vector in the α-β plane of the two-phase stationary coordinate system, the electromagnetic torque feedback value, the torque and flux difference, the frequency, the number of pole pairs, the electrical angle and the motion mode.

[0104] The preferred embodiment of the present invention is as follows: the multi-mode arbitrator receives the desired rotational speed of each hub motor transmitted by the vehicle controller, and converts the desired rotational speed of the hub motor I into the desired rotational speed of the hub motor I. and the desired speed of hub motor II Compare the size relationship and set the expected speed of hub motor III and the desired speed of the hub motor IV Compare the size relationships and then assign each motor working mode, so as to select the appropriate multi-voltage vector integrated modulation switch table. The details are as follows:

[0105] (1) The vehicle controller receives the desired vehicle speed V d , the actual speed ω collected by the four rotary transformers of hub motor I, hub motor II, hub motor III and hub motor IV ea 、ω eb 、ω ec and ω ed For example, the upper-level control torque distribution algorithm such as PID realizes the torque distribution of each hub motor and obtains the electromagnetic torque given value of hub motor I, hub motor II, hub motor III and hub motor IV. and The multi-mode arbitrator receives the desired speeds of the four hub motors output by the vehicle controller. When the desired speed of the hub motor III is When the sports mode S bMode Output is 1, when the desired speed of hub motor III When the sports mode S bMode The output is 0.

[0106] (2) Take hub motor I and hub motor II as examples. When the desired speed of hub motor I is When the dual-wheel motor is in synchronous working mode, the sports mode is S aMode The output is 1 and transmitted to the multi-operating-mode, multi-voltage integrated modulation algorithm controller, which selects the frequency ratio-based multi-voltage vector integrated modulation switch table algorithm. The desired frequency ratio is the ratio of the pole pairs of hub motor I and hub motor II. For example, when hub motor I has 25 pole pairs and hub motor II has 17 pole pairs, the desired frequency ratio is 1.47. When the actual frequency ratio Δn is less than 1.47, the output signal detn is 0, indicating that hub motor I is running slower than hub motor II, or hub motor II is running faster than hub motor I. Based on hub motor II, the voltage vector of hub motor I is changed to select a voltage vector that improves its speed, as shown in Table 1.

[0107] (3) When the desired speed of hub motor I When the dual-wheel motors are in asynchronous working mode, the vehicle steering command or the vehicle passes through complex road conditions, the sports mode S aMode The output is 0 and transmitted to the multi-operating-state multi-voltage integrated modulation algorithm controller, which selects the multi-voltage vector integrated modulation switch table algorithm based on the virtual vector, and outputs the ε according to the modulation hysteresis comparator. T , ε ψ And the integrated sector judge output sector S fr , a suitable voltage vector is selected from 12 virtual voltage vectors to realize the coordinated control of the dual-hub motors.

[0108] Therefore, the present invention constructs an integrated modulation drive system for multiple hub motors and designs an integrated driver to realize the integrated drive of multiple hub motors. The present invention constructs a multi-voltage vector integrated modulation algorithm controller based on multiple working conditions, selects a suitable unified voltage vector for the dual hub motors, and realizes the coordinated control of the dual hub motors in combination with the switch conduction state of the six-half-bridge arm group driver. Based on the mapping relationship between the voltage vectors of the two hub motors in the fundamental wave α1-β1 space voltage vector plane, the present invention constructs a multi-voltage vector integrated modulation switch table algorithm based on a virtual vector and a multi-voltage vector integrated modulation switch table algorithm based on a frequency ratio. In order to fully coordinate the advantages of the two hub motors, the present invention judges the motion mode of the hub motor according to the working conditions of each hub motor of the distributed electric vehicle, selects different switch table algorithms, and realizes the reduction of the redundant number of controllers and actuators under variable operating conditions while reducing the length of the communication optical fiber, thereby improving the transmission efficiency and fault tolerance of the distributed drive electric vehicle and effectively realizing the smooth operation of the electric vehicle. Compared with existing control technologies, the present invention comprehensively considers the redundant number of motor controllers and actuators in the multi-hub motor drive system. The design of the integrated controller effectively adapts to road conditions. The design of the multi-voltage vector integrated modulation algorithm controller for multiple working conditions improves the collaborative performance of the dual-hub motors, reduces the computing load of the upper-level controller, and comprehensively improves the handling performance of electric vehicles under variable working conditions.

[0109] The above implementation cases are only used to illustrate the design ideas and features of the present invention. Its purpose is to enable technical personnel in this field to understand the content of the present invention and implement it accordingly. The scope of protection of the present invention is not limited to the above implementation cases. Therefore, any equivalent changes or modifications made according to the principles and design ideas disclosed by the present invention are within the scope of protection of the present invention.

Claims

1. A multi-hub motor integrated modulation drive system, characterized by: It consists of a vehicle controller, two integrated drivers with the same structure, and a multi-mode arbitrator. Each integrated driver consists of an integrated modulation controller and six half-bridge arm group drivers in series. The output end of the six half-bridge arm group drivers in each integrated driver is connected to the two wheel hub motors on the corresponding side of the vehicle. The vehicle controller takes the actual speed of the four wheel hub motors and the driver's desired speed as input, and outputs four desired speeds and four electromagnetic torque given values ​​of the four wheel hub motors; The desired rotational speeds of the four wheel hub motors are input into a multi-mode arbitrator for motion mode determination, and motion mode signals for straight-line or turning conditions on both sides of the vehicle are obtained. The motion mode signals, the desired rotational speeds, and the electromagnetic torque set values ​​are respectively input into the integrated modulation controller on the corresponding side of the vehicle; Each integrated modulation controller includes a modulation hysteresis comparator, a torque and flux observer, an integrated sector judge and a multi-operating-state multi-voltage vector integrated modulation algorithm controller. Each torque and flux observer obtains the feedback flux of the two wheel hub motors on the same side, the flux of the feedback flux in the two-phase stationary coordinate system αβ and the electromagnetic torque feedback value T eb , the magnetic flux of the two-phase stationary coordinate system αβ and the motion mode on the same side are judged in real time by the integrated sector judger to determine the current sector signal; The modulation hysteresis comparator outputs the flux modulation value and torque modulation value according to the flux difference and electromagnetic torque of the two motors on the same side; The multi-voltage vector integrated modulation algorithm controller takes the flux modulation value, torque modulation value, sector signal, motion mode, expected speed and actual speed of the two motors on the same side as input, selects the optimal voltage combination vector, and outputs the corresponding duty cycle to each bridge arm of the six-half-bridge bridge arm group driver to achieve coordinated drive of the two hub motors on the same side.

2. The multi-hub motor integrated modulation drive system according to claim 1, characterized in that: The three-phase currents and electrical angles of the two hub motors on the same side are collected respectively. The currents and electrical angles are transformed by a six-dimensional transformation matrix to obtain the dq-axis currents. The dq-axis currents are input into the torque and flux observer to obtain the feedback flux of the two hub motors, the flux of the feedback flux in the two-phase stationary coordinate system αβ, and the electromagnetic torque feedback value.

3. The multi-hub motor integrated modulation drive system according to claim 2, characterized in that: The feedback flux and electromagnetic torque feedback values ​​are respectively subtracted from the set flux given value and the input electromagnetic torque given value in a one-to-one correspondence to obtain the flux difference and electromagnetic torque. The modulation hysteresis comparator takes the flux difference and electromagnetic torque as input and takes the flux modulation value signal and the torque modulation value signal as output.

4. A control method for a multi-hub motor integrated modulation drive system according to claim 1, characterized in that The following steps are involved: Step 1): Model the hub motor on the same side and construct its integrated spatial voltage vector diagram: Step 2): establishing a multi-voltage vector integrated modulation switch table based on the integrated space voltage vector diagram, dividing the space voltage vector plane into 12 sectors based on the space voltage vector diagram, using 16 groups of combinations formed by any pairwise combination of the flux modulation values ​​and the torque modulation values ​​as voltage vector selection rules, to form a multi-voltage vector integrated modulation switch table; based on the multi-voltage vector integrated modulation switch table, forming a frequency ratio-based and virtual vector-based switch table; Step 3): Sampling the actual speed and three-phase current of the hub motor, based on the six-dimensional transformation matrix formula, the input of the torque and flux observer is the dq axis current, the feedback flux of the output hub motor, and its flux and electromagnetic torque feedback value in the two-phase stationary coordinate system αβ obtained through the six-dimensional transformation matrix; Step 4): The integrated sector determiner selects a corresponding sector division method according to the switch table corresponding to the motion mode output by the multi-mode arbitrator and determines the corresponding sector signal; Step 5): The multi-condition multi-voltage vector integrated modulation algorithm controller selects the corresponding switch table according to the motion mode signal. When the motion mode is 1, the frequency ratio-based switch table is selected, and the actual speed and expected speed of the hub motor, the sector signal, and the torque and flux modulation signal of the hub motor are used as input to output the optimal voltage vector; when the motion mode is 0, the virtual vector-based switch table is selected, and the sector signal and the torque and flux modulation signal of the hub motor are used as input to output the optimal voltage vector.

5. The control method according to claim 4, characterized in that: The switching table based on frequency ratio: first calculate the actual frequency ratio Δn and the expected frequency ratio Δn* of the two wheel hub motors on the same side: the difference between the actual frequency ratio Δn and the expected frequency ratio Δn* is obtained. When the actual frequency ratio is less than the expected frequency ratio and outside the tolerance value, the output signal is 0, and the faster voltage vector is selected for output. The function form is: The multi-voltage vector integrated modulation switch table is improved according to the frequency ratio function form. The voltage vector of one hub motor on the same side is kept unchanged, and the voltage vector of the second hub motor is changed to obtain the frequency ratio-based switching table for synchronous working conditions.

6. The control method according to claim 4, characterized in that: The virtual vector-based switch table is a switch table based on the principle of synthesizing a virtual vector of a long vector and a middle vector for steering conditions. The space voltage vector plane is divided into 12 sectors, starting from -15°, with each sector being 30°. The 12 virtual voltage vector amplitudes, the duty ratios of the long vector and the middle vector are calculated, and the duty ratio K of the long vector is obtained. L The duty cycle of the vector in the sum satisfies K M +K L =1, get the switch table based on virtual vector.

7. The control method according to claim 4, characterized in that: The modulation hysteresis comparator converts the electromagnetic torque difference △T ea ,△T eb and the flux difference △ψ a ,△ψ b Compared with the upper and lower limits of the modulation hysteresis comparator, the flux modulation value ε ψ Signal and torque modulation value ε T The signal principles are: ε T =11 means that the electromagnetic torque of the two hub motors on the same side needs to be increased, ε T =10 means that the electromagnetic torque of the first hub motor on the same side needs to be increased and the electromagnetic torque of the second hub motor needs to be reduced, ε T =01 means that the electromagnetic torque of the first hub motor on the same side needs to be reduced and the electromagnetic torque of the second hub motor needs to be increased, ε T =00 means that the electromagnetic torque of the two hub motors on the same side needs to be reduced, ε ψ =11 means that the flux linkage of the two hub motors on the same side needs to be increased, ε ψ =10 means that the flux linkage of the first hub motor on the same side needs to be increased and the flux linkage of the second hub motor needs to be reduced, ε ψ =01 means that the flux linkage of the first hub motor needs to be reduced and the flux linkage of the second hub motor needs to be increased, ε ψ =00 means that the flux linkage of the two hub motors on the same side needs to be reduced.

8. The control method according to claim 4, characterized in that: Taking the coupling of the rotating magnetic field of the magnetic flux linkage as the constraint condition, the two basic voltage vector diagrams in the αβ plane of the two-phase stationary coordinate system with a difference of 30° are connected to form a three-dimensional integrated spatial voltage vector diagram.

9. The control method according to claim 8, characterized in that: In the integrated space voltage vector diagram, in the α-β plane of the two-phase stationary coordinate system, the α axis and the β axis are perpendicular to each other, and serve as the horizontal axis and vertical axis of the rectangular coordinate system respectively. Based on this definition, the α axis, β axis and γ axis are perpendicular to each other in space, and serve as the horizontal axis, vertical axis and vertical axis of the space rectangular coordinate system respectively, forming an α-β-γ coordinate system. The two hub motors on the same side are regarded as an integrated system. In the α-β-γ coordinate system, the magnetic flux rotating magnetic field coupling is used as the constraint condition as the vertical axis, and the two basic voltage vector diagrams in the α-β plane of the two-phase stationary coordinate system with a difference of 30° are connected to form a three-dimensional integrated space voltage vector diagram, including 12 non-zero original voltage vectors corresponding to 24 switching states.

10. The control method according to claim 9, characterized in that: When the motion mode is 0, the virtual vector-based switch table contains 12 virtual vectors in the α-β coordinate system, and the virtual voltage vector amplitude is 0.571U dc , U dc is the bus voltage of the six-arm driver, and the 12 virtual voltage vectors are generated by the action time of 0.578T. s The long voltage vector and action time is 0.422T s The medium voltage vector composition, T s is the control period.

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