Cooperative control method and device of multi-motor drive system and vehicle

Abstract

The application discloses a kind of collaborative control method, device and vehicle of multi-motor drive system, it is related to motor drive and control technical field.The control method includes by superior controller generates reference speed instruction and is issued to each motor controller;Each motor controller works in speed control mode, receives and drives corresponding motor according to reference speed instruction;Superior controller obtains the load operating parameter of each motor controller in real time;Based on load operating parameter, calculate the index for representing the load imbalance between each motor drive unit;According to load imbalance index, dynamically and differentially adjust the speed instruction issued to at least one motor controller, so that the load operating state of each motor drive unit tends to be balanced.The application actively balances the load operating parameter of each motor controller, fundamentally prevents the protective shutdown caused by single motor overload or overheating, and eliminates the sudden failure of vehicle running function.

Description

Technical Field

[0001] This invention belongs to the field of motor drive and control technology, and particularly relates to a collaborative control method, device and vehicle for a multi-motor drive system. Background Technology

[0002] In specialized industrial equipment such as electric aerial work platforms, which are driven by multiple motors, the mobility system typically employs a distributed layout where the vehicle controller coordinates the overall system, while multiple motor controllers drive their respective motors. Currently, the mobility control of this type of equipment generally uses a technical solution that differs from passenger cars and other engineering vehicles: its motor controllers do not operate in torque control mode based on vehicle dynamics requirements, but rather in speed control mode. Specifically, the vehicle controller issues a unified speed (rotational speed) command to each motor controller, and each controller independently controls its motor to strictly track this target rotational speed.

[0003] Under this rigid speed tracking mechanism, any load differences caused by mechanical structure (such as chassis frame design, motor mounting coaxiality error, vehicle center of gravity offset) or road surface (such as bumps, uneven adhesion coefficient) will directly translate into differences in drive current required to maintain synchronous speed—the heavier the load on the motor, the greater the current its controller needs to output to overcome resistance. The system completely accepts this current distribution passively determined by physical conditions, without any active intervention or balancing at the control strategy level.

[0004] However, this control strategy has inherent flaws. When there are dynamic differences in the actual loads of the drive wheels, in order to maintain a uniform speed, the controller output current of the motor with the larger load will be continuously or momentarily significantly higher than that of other motors. In the existing technology, each motor controller executes speed commands in isolation, and there is a lack of a coordinated management and dynamic balancing mechanism for the output current at the system level, which leads to the following problems:

[0005] (1) Risk of instantaneous overload: When the load changes rapidly (such as when one wheel encounters an obstacle), the drive current of individual motors may instantly exceed the overcurrent protection threshold of the motor controller, causing the drive unit to stop and the vehicle's driving power to be suddenly interrupted, posing a significant safety hazard.

[0006] (2) Risk of continuous overheating: Under long-term load bias conditions, the continuous high current operation of a specific motor will cause its temperature rise to be much higher than that of other motors. This not only accelerates the aging of the motor insulation, but also easily triggers the overheat protection, causing unplanned system shutdowns, which seriously affects the operating efficiency and equipment reliability.

[0007] Therefore, the existing technology lacks an effective coordination mechanism to solve the problem of autonomous current distribution among multiple motors in speed control mode, and cannot achieve dynamic load balancing, which constitutes a key technical bottleneck in improving the reliability, continuity and safety of the whole machine operation. Summary of the Invention

[0008] In view of the above-mentioned defects in the prior art, the purpose of the present invention is to provide a cooperative control method, device and vehicle for a multi-motor drive system, so as to solve the problem that multi-motors cannot achieve autonomous current distribution in speed control mode, and thus cannot achieve dynamic load balancing.

[0009] This invention solves the above-mentioned technical problems through the following technical solution: a cooperative control method for a multi-motor drive system, wherein the drive system includes at least two motor drive units, each motor drive unit includes a motor controller and a motor driven by the motor controller, and the cooperative control method is executed by a higher-level controller; the method includes:

[0010] The upper-level controller generates a reference speed command and sends it to each motor controller;

[0011] Each of the motor controllers operates in speed control mode, receiving and driving the corresponding motor according to the reference speed command;

[0012] The upper-level controller acquires the load operating parameters of each motor controller in real time; wherein, the load operating parameters are used to characterize the real-time load status of the motor.

[0013] Based on the load operating parameters, an index is calculated to characterize the load imbalance between each motor drive unit.

[0014] Based on the load imbalance index, the speed commands issued to at least one of the motor controllers are dynamically and differentially adjusted to make the load operation status of each motor drive unit tend to be balanced.

[0015] Traditional systems tend to ignore uneven load distribution, with each motor controller executing rigid speed commands in isolation. This invention, however, acquires real-time load operating parameters (such as output current or internal torque commands) from each motor controller, enabling the system to perceive the load status of each drive unit in real time, thus providing a data foundation for subsequent intelligent intervention.

[0016] In existing technologies, uneven load directly leads to uneven current, creating a vicious cycle of "high load → high current → overload / overheating → shutdown". This invention dynamically and differentially adjusts the speed commands sent to specific motor controllers based on a calculated load imbalance index. This means that when the system detects an excessive load on a motor, it strategically allows its speed to temporarily and slightly decrease. According to motor principles, this directly reduces the motor's slip, thereby reducing its output torque and current, effectively lightening the load on the overloaded motor and proactively breaking the vicious cycle, allowing it to return to a safe operating range. This invention's proactive load balancing control directly avoids protective shutdowns caused by overcurrent in a single motor controller or overheating of the motor, fundamentally solving the problem of overall vehicle failure and greatly improving equipment availability and operational efficiency.

[0017] Furthermore, the load operating parameter is the output current of the motor controller; or, the load operating parameter is the torque command value or torque feedback value generated internally by the motor controller in speed control mode in real time.

[0018] Output current is one of the most direct and easily acquired physical quantities for motor controllers. It can be obtained with high accuracy and high response speed using existing sensors (such as Hall effect current sensors) without the need for complex model calculations. This makes the invention easy to implement, cost-effective, and highly reliable.

[0019] In speed control mode, the torque command value (or the torque feedback value derived from it) calculated in real time by the motor controller to maintain the speed is the given target of the current loop. It directly and without delay reflects the load demand intention of the motor controller itself, leading the actual output current phase and being less affected by external factors such as bus voltage fluctuations and motor back EMF. Therefore, by using the torque command value or torque feedback value as load operating parameters, the system can more quickly and intrinsically predict and perceive load change trends.

[0020] Furthermore, the specific calculation process for the load imbalance index is as follows:

[0021] Calculate the integral value of the load operating parameters of each motor controller within a time window;

[0022] The arithmetic mean of the integral values ​​of all motor controllers is calculated, and the arithmetic mean is used as the load imbalance index.

[0023] This invention calculates the integral value within a time window, which essentially obtains the total load or average load level within that time period. The proportion of instantaneous spikes after integration is greatly reduced, allowing the load imbalance index to more realistically reflect continuous and trending load imbalances rather than short-term disturbances. This effectively suppresses instantaneous interference and current noise, making decision-making more robust.

[0024] Decisions based on integral averages avoid misjudgments caused by instantaneous fluctuations; the system will not reduce the speed command due to a momentary current spike, thereby greatly reducing the number of control actions, avoiding frequent changes in motor speed, and improving the stability and reliability of control.

[0025] Furthermore, based on the load imbalance index, the speed commands sent to the motor controller are dynamically and differentially adjusted, specifically including:

[0026] When the ratio of the load operating parameter of a certain motor controller to the load imbalance index is less than or equal to the set first threshold, the speed command issued to the motor controller remains unchanged.

[0027] When the ratio of the load operating parameter to the load imbalance index of a certain motor controller is greater than the set first threshold, the speed command sent to the motor controller is reduced according to the preset strategy.

[0028] This invention no longer performs uniform speed control on all motors. Instead, it accurately identifies motors with excessive loads and intervenes only on those drive units, avoiding the performance loss caused by a one-size-fits-all approach to speed reduction and maximizing load balancing efficiency. Furthermore, this invention no longer rigidly executes commands but proactively adapts to changing operating conditions (such as road bumps or center of gravity shift), thereby actively eliminating risks before overload or overheating failures occur. This represents a qualitative leap from passive protection to proactive prevention, fundamentally improving the system's safety and reliability.

[0029] Furthermore, the step-by-step adjustment method for reducing the speed command issued to the motor controller using a preset strategy includes:

[0030] Based on predefined rules, a speed adjustment amount is determined in each adjustment cycle, and the speed command issued to the motor controller is successively reduced according to the speed adjustment amount; wherein, the sum of the speed adjustment amounts in all adjustment cycles constitutes a cumulative adjustment amount, and the cumulative adjustment amount does not exceed a preset maximum speed adjustment amount.

[0031] To avoid oscillations caused by simple control, this invention can adopt a stepped adjustment strategy to ensure the smoothness of speed command changes and avoid shocks.

[0032] Furthermore, during the process of reducing the speed command of a certain motor controller, the method also includes a hysteresis recovery step:

[0033] If the ratio of the load operating parameter to the load imbalance index of a certain motor controller is less than or equal to the difference between the set first threshold and the hysteresis value, then the speed command of the motor controller is stopped from being reduced further. Subsequently, the recovery process is started to gradually restore the speed command issued to the motor controller to the reference speed command.

[0034] To avoid oscillations caused by simple control, this invention employs a hysteresis recovery strategy. Hysteresis recovery, by setting differentiated start and exit thresholds, prevents frequent switching of control modes near the critical point, greatly enhancing the system's stability and anti-interference capability.

[0035] Furthermore, the upper-level controller is a vehicle controller, or a motor controller designated as the main controller; the reference speed command is obtained by converting the target vehicle speed based on vehicle parameters.

[0036] Using the vehicle controller as the superior controller facilitates the integration of this invention into existing vehicle controllers, enabling centralized coordination and management. Using a motor controller designated as the master controller as the superior controller eliminates the need to modify or rely on the vehicle controller; the invention can be directly implemented within the existing motor controller network by designating one of the controllers as the master controller through software upgrades. This significantly lowers the barriers to implementation and reduces costs, allowing the invention to be rapidly applied to products with various architectures and price points.

[0037] Based on the same concept, the present invention also provides a cooperative control system for a multi-motor drive system, wherein the drive system includes at least two motor drive units, each motor drive unit includes a motor controller and a motor driven by the motor controller; each motor controller operates in speed control mode and is used to receive and drive the corresponding motor according to the speed command issued by the upper controller;

[0038] The control system includes a higher-level controller, which is used for:

[0039] Generate a reference speed command and send it to each motor controller;

[0040] The load operating parameters of each motor controller are acquired in real time; wherein the load operating parameters are used to characterize the real-time load status of the motor.

[0041] Based on the load operating parameters, an index is calculated to characterize the load imbalance between each motor drive unit.

[0042] Based on the load imbalance index, the speed commands issued to at least one of the motor controllers are dynamically and differentially adjusted to make the load operation status of each motor drive unit tend to be balanced.

[0043] Furthermore, based on the load imbalance index, the speed commands sent to the motor controller are dynamically and differentially adjusted, specifically including:

[0044] When the ratio of the load operating parameter of a certain motor controller to the load imbalance index is less than or equal to the set first threshold, the speed command issued to the motor controller remains unchanged.

[0045] When the ratio of the load operating parameter to the load imbalance index of a certain motor controller is greater than the set first threshold, the speed command sent to the motor controller is reduced according to the preset strategy.

[0046] Preferably, during the process of reducing the speed command of a certain motor controller, the upper-level controller also performs a hysteresis recovery step:

[0047] If the ratio of the load operating parameter to the load imbalance index of a certain motor controller is less than or equal to the difference between the set first threshold and the hysteresis value, then the speed command of the motor controller is stopped from being reduced further. Subsequently, the recovery process is started to gradually restore the speed command issued to the motor controller to the reference speed command.

[0048] Based on the same concept, the present invention also provides a vehicle, which is an electric vehicle or an aerial work platform, characterized in that the electric vehicle or aerial work platform includes a cooperative control system of the multi-motor drive system as described above.

[0049] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0050] This invention, by actively balancing the load operating parameters of each motor controller, fundamentally prevents protective shutdowns caused by single motor overload or overheating, eliminates the fault of sudden failure of the vehicle's walking function, and ensures the continuity and availability of operations.

[0051] This invention dynamically distributes the risk of uneven load among the drive units, improving the stability and safety redundancy of the equipment under complex and bumpy road conditions, and avoiding single point of failure.

[0052] This invention balances load operating parameters, avoiding prolonged exposure of specific motors to harsh conditions of high current and high temperature rise, thus slowing down the aging of the motor and controller and extending the overall service life of the system.

[0053] This invention employs strategies such as load judgment based on integral averaging, step adjustment, and hysteresis recovery, which makes the control process stable, has strong anti-interference ability, effectively prevents system oscillation, and improves control quality. Attached Figure Description

[0054] To more clearly illustrate the technical solution of the present invention, the drawings used in the following description of the embodiments will be briefly introduced. Obviously, the drawings described below are only one embodiment of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0055] Figure 1 This is a block diagram of the collaborative control system structure of the multi-motor drive system in an embodiment of the present invention;

[0056] Figure 2 This is a flowchart of the cooperative control method for a multi-motor drive system in an embodiment of the present invention;

[0057] Figure 3 This is a flowchart of the step adjustment method in an embodiment of the present invention. Detailed Implementation

[0058] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0059] The technical solution of the present invention will be described in detail below with reference to specific embodiments. These specific embodiments can be combined with each other, and the same or similar concepts or processes may not be described again in some embodiments.

[0060] Example 1

[0061] like Figure 1 As shown, the multi-motor drive system of this embodiment includes four motor drive units. Each motor drive unit includes a motor controller and a motor driven by the motor controller. The motor controller and the corresponding motor are connected via a power line, and each motor corresponds to one wheel. That is, the multi-motor drive system includes a left front drive unit, a right front drive unit, a left rear drive unit, and a right rear drive unit. The left front drive unit includes a left front motor controller and a left front motor; the right front drive unit includes a right front motor controller and a right front motor; the left rear drive unit includes a left rear motor controller and a left rear motor; and the right rear drive unit includes a right rear motor controller and a right rear motor. The left front motor corresponds to the left front wheel, the right front motor corresponds to the right front wheel, the left rear motor corresponds to the left rear wheel, and the right rear motor corresponds to the right rear wheel.

[0062] The collaborative control method provided by this invention is executed by a higher-level controller. In one specific embodiment of this invention, the higher-level controller is a vehicle controller, which is connected to the motor controllers of each motor drive unit via a CAN bus. In another specific embodiment of this invention, the higher-level controller is a motor controller designated as the master controller. For example, if the left front motor controller is designated as the master controller, then the right front motor controller, left rear motor controller, and right rear motor controller are all slave controllers, and the higher-level controller is the left front motor controller.

[0063] like Figure 2 As shown, the cooperative control method provided in this embodiment of the invention includes the following steps:

[0064] Step S1: The upper-level controller generates a reference speed command and sends it to each motor controller.

[0065] The upper-level controller acquires the target vehicle speed by collecting the accelerator pedal signal; based on the vehicle transmission parameters, it converts the target vehicle speed into a reference speed command; the upper-level controller sends the reference speed command to all motor controllers via the CAN bus at a preset cycle.

[0066] Step S2: Each motor controller operates in speed control mode, receiving and driving the corresponding motor according to the reference speed command.

[0067] Each motor controller operates independently in a speed closed loop, with the control objective of driving the motor to accurately track the reference speed command issued by the superior controller. This tracking process is based on the torque characteristics of a three-phase asynchronous motor. The electromagnetic torque formula for a three-phase asynchronous motor is:

[0068] (1)

[0069] in, This indicates the electromagnetic torque of the motor, measured in N·m. Indicates the torque coefficient; Indicates air gap magnetic flux; This represents the converted value of the rotor current, in amperes (A). This indicates the power factor on the rotor side of the motor.

[0070] According to formula (1), we can approximately obtain The motor controller is below the base frequency. It usually remains constant, therefore The current and torque are linearly related. Substituting the relevant parameters into formula (1) and expanding, we get:

[0071] (2)

[0072] in, Indicates the stator voltage; Indicates the synchronous angular velocity (determined by frequency); Indicates rotor resistance; Indicates equivalent leakage impedance; Indicates the slip ratio. ; Indicates synchronous speed; This indicates the actual rotational speed.

[0073] It can be seen that, below the base frequency of an asynchronous motor, with other parameters constant, the larger the slip s, the larger the output torque T. In speed control mode, when the load increases and the actual speed tends to decrease, the slip increases. To maintain the stability of the speed control target value, the motor controller will automatically increase the output torque T. According to the electromagnetic torque formula (… This will directly lead to an increase in the output current of the motor controller. The specific implementation process is as follows:

[0074] Each motor controller receives a reference speed command from the upper-level controller and sets it as the target speed control value for that motor controller. The motor controller acquires the actual motor speed in real time and calculates the error between the actual speed and the target speed control value. This error is input to the PID controller, whose output is the torque command value required for the actual speed to track the target speed control value. Based on the torque command value, the motor generates the target torque, thereby driving the load. According to the aforementioned motor principle, this process ultimately manifests as the motor controller outputting a corresponding drive current to the motor.

[0075] Through the above process, the output current of each motor in speed control mode is directly determined by the electromagnetic torque required to maintain the target speed control value, thus mapping the load difference on the mechanical side to the current difference on the electrical side. During this process, if the motor load increases, its slip s will increase according to the principles of motor theory. Based on the relationship between formula (2) and the electromagnetic torque formula, the output current of the motor controller will increase accordingly to maintain stable speed. This physical essence is the fundamental basis for the subsequent current monitoring and equalization control in this invention.

[0076] In the initial stage of control, the upper-level controller uniformly issues a reference speed command to each motor controller, meaning that each motor controller receives the same target speed control value.

[0077] Step S3: The upper-level controller obtains the load operating parameters of each motor controller in real time.

[0078] Load operating parameters are used to characterize the real-time load status of the motor. In one specific embodiment of the present invention, the load operating parameter is the output current of the motor controller. Each motor controller acquires two phases of the three-phase current output to the motor in real time through its internal current sensor (such as a Hall sensor or a sampling resistor); then, the microprocessor in the motor controller filters and calculates the acquired current values ​​to finally obtain the current (e.g., d-axis current, q-axis current) that can characterize the motor load.

[0079] In one specific embodiment of the present invention, the load operating parameters are the torque command value or torque feedback value generated internally by the motor controller in speed control mode. In speed control mode, the PID controller output value of the motor controller is the real-time torque command value.

[0080] Through any of the above methods, the upper-level controller can periodically and reliably obtain key parameters reflecting the real-time load status of each motor.

[0081] Step S4: Based on the load operating parameters, calculate the index used to characterize the load imbalance between each motor drive unit.

[0082] In one specific embodiment of the present invention, the specific calculation process of the load imbalance index is as follows:

[0083] Step S4.1: Calculate the integral value of the load operating parameters of each motor controller within a time window;

[0084] Step S4.2: Calculate the arithmetic mean of the integral values ​​of all motor controllers, and use the arithmetic mean as the load imbalance index.

[0085] Taking the load operating parameter as the output current as an example, let the output current of the i-th motor controller be... The formula for calculating the load imbalance index is:

[0086] (3)

[0087] in, The arithmetic mean of the integral values ​​of the output current represents the load imbalance index; M represents the number of motor controllers, and in this embodiment, M = 4. The value represents the size of the time window; t represents time.

[0088] The integral value within the calculation time window essentially obtains the total output current during that time period. The proportion of instantaneous current spikes after integration is greatly reduced, allowing the load imbalance index to more realistically reflect continuous and trending current imbalances (i.e., load imbalances) rather than transient disturbances. This effectively suppresses instantaneous interference and current noise, making decisions more robust.

[0089] Decisions based on integral average values ​​avoid misjudgments caused by instantaneous current fluctuations; the system will not reduce speed commands due to a momentary current spike, thereby greatly reducing the number of control actions, avoiding frequent changes in motor speed, and improving the stability and reliability of control.

[0090] Step S5: Based on the load imbalance index, dynamically and differentially adjust the speed commands issued to at least one motor controller so that the load operation status of each motor drive unit tends to be balanced.

[0091] In one specific embodiment of the present invention, the speed command issued to the motor controller is dynamically and differentially adjusted according to the load imbalance index, specifically including:

[0092] When the ratio of the load operating parameter of a certain motor controller to the load imbalance index is less than or equal to the set first threshold, the speed command issued to the motor controller remains unchanged.

[0093] Taking the load operating parameter as the output current as an example, the specific expression is: when When ≤r, , This indicates the speed command issued to the i-th motor controller. The reference speed command (obtained based on the target vehicle speed) is represented by r, which represents the set first threshold. In this embodiment, the first threshold r is set to 1.25, which was obtained through actual testing.

[0094] When the ratio of the load operating parameter to the load imbalance index of a certain motor controller is greater than the set first threshold, the speed command sent to the motor controller is reduced according to the preset strategy.

[0095] Taking the load operating parameter as the output current as an example, the specific expression is: when When the speed is greater than r, the speed command sent to the i-th motor controller is reduced using a step-by-step adjustment method.

[0096] In one specific embodiment of the present invention, the speed command issued to the i-th motor controller is reduced using a stepped adjustment method, including:

[0097] Based on predefined rules, a speed adjustment amount is determined in each adjustment cycle, and the speed command issued to the i-th motor controller is successively reduced according to the speed adjustment amount; wherein, the sum of the speed adjustment amounts in all adjustment cycles constitutes a cumulative adjustment amount, and the cumulative adjustment amount does not exceed a preset maximum speed adjustment amount N.

[0098] like Figure 3 As shown, the specific execution steps are as follows:

[0099] Based on predefined rules, the speed adjustment amount for the current adjustment cycle is calculated. (That is, the speed adjustment amount of the i-th motor controller in the j-th adjustment cycle), the speed adjustment amount in each adjustment cycle. It can be a fixed value or a dynamically calculated value based on the load imbalance index;

[0100] Calculate the current cumulative adjustment amount (Equal to the previous cumulative adjustment amount) and (sum of the sums), and determine the current cumulative adjustment amount. Does the maximum speed adjustment amount N have been exceeded? If so, abandon this adjustment or reduce the speed adjustment amount for the current adjustment cycle. This makes the current cumulative adjustment amount The speed adjustment shall not exceed the maximum speed adjustment amount N; otherwise, the speed adjustment shall be based on the current adjustment cycle. Update the speed command sent to the i-th motor controller: .in, This indicates the speed command issued to the i-th motor controller before the update. This indicates the speed command issued to the i-th motor controller after the update.

[0101] This invention achieves flexibility and smoothness in control through periodic decision-making, and ensures the safety and stability of the system by adjusting the maximum speed, preventing the motor speed from becoming too low due to continuous adjustment.

[0102] To prevent repeated oscillations during adjustment, a hysteresis value p is set. During the process of reducing the speed command of a motor controller, a hysteresis recovery step is also performed, specifically including:

[0103] like Figure 3 As shown, after each update of the speed command issued to the i-th motor controller, it is determined whether the ratio of the load operating parameters of the i-th motor controller to the load imbalance index is less than or equal to (r-p). If so, the speed command of the i-th motor controller is stopped from being reduced. Subsequently, the recovery process is started, and the speed command issued to the i-th motor controller is gradually restored to the reference speed command (by setting the incremental speed and setting the time, gradually restoring to the reference speed command) until a steady state is reached, that is, the speed commands of each motor controller are equal and are the reference speed commands.

[0104] Taking the load operating parameter as the output current as an example, before adjustment, the speed commands received by the four motor controllers are the same and are all reference speed commands, that is... , This indicates the reference speed command.

[0105] Assuming the wheel load corresponding to the fourth motor controller is greater than that of the other wheels, its slip rate will also be greater, and its output current will also be greater. In this case, reducing the speed command of the fourth motor controller within a certain range will also reduce its slip rate. According to formula (2), the output torque will decrease accordingly. Based on the electromagnetic torque approximation formula... The output current decreases synchronously, achieving the control objective, that is... ≤r.

[0106] Example 2

[0107] like Figure 1 As shown in the embodiment of the present invention, the cooperative control system of the multi-motor drive system includes four motor drive units. Each motor drive unit includes a motor controller and a motor driven by the motor controller. The motor controller and the corresponding motor are connected via a power line, and each motor corresponds to one wheel. That is, the multi-motor drive system includes a left front drive unit, a right front drive unit, a left rear drive unit, and a right rear drive unit. The left front drive unit includes a left front motor controller and a left front motor; the right front drive unit includes a right front motor controller and a right front motor; the left rear drive unit includes a left rear motor controller and a left rear motor; and the right rear drive unit includes a right rear motor controller and a right rear motor. The left front motor corresponds to the left front wheel, the right front motor corresponds to the right front wheel, the left rear motor corresponds to the left rear wheel, and the right rear motor corresponds to the right rear wheel.

[0108] The collaborative control system provided in this invention includes a higher-level controller. In one specific embodiment, the higher-level controller is a vehicle controller, which is connected to the motor controllers of each motor drive unit via a CAN bus. In another specific embodiment, the higher-level controller is a motor controller designated as the master controller. For example, if the left front motor controller is designated as the master controller, then the right front motor controller, left rear motor controller, and right rear motor controller are all slave controllers, and the higher-level controller is the left front motor controller.

[0109] Each motor controller operates in speed control mode and is used to receive and drive the corresponding motor according to the speed command issued by the upper controller.

[0110] The upper-level controller is used to: generate a reference speed command and send it to each motor controller; acquire the load operating parameters of each motor controller in real time; wherein the load operating parameters are used to characterize the real-time load status of the motor; calculate an index to characterize the load imbalance between each motor drive unit based on the load operating parameters; and dynamically and differentially adjust the speed command sent to at least one motor controller according to the load imbalance index so that the load operating status of each motor drive unit tends to be balanced.

[0111] In some specific embodiments of the present invention, the cooperative control system may incorporate the features of the cooperative control method in the embodiments of the present invention, and vice versa, which will not be elaborated here.

[0112] An embodiment of the present invention also provides an electric vehicle, which includes a cooperative control system for a multi-motor drive system as described in the present invention.

[0113] This invention also provides an aerial work platform, which includes a collaborative control system for the multi-motor drive system in this invention.

[0114] The above description only discloses specific embodiments of the present invention, but the scope of protection of the present invention is not limited thereto. Any changes or modifications that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention.

Claims

1. A cooperative control method for a multi-motor drive system, the drive system comprising at least two motor drive units, each motor drive unit comprising a motor controller and a motor driven by the motor controller, the cooperative control method being executed by a higher-level controller; characterized in that, The method includes: The upper-level controller generates a reference speed command and sends it to each motor controller; Each of the motor controllers operates in speed control mode, receiving and driving the corresponding motor according to the reference speed command; The upper-level controller acquires the load operating parameters of each motor controller in real time; wherein, the load operating parameters are used to characterize the real-time load status of the motor. Based on the load operating parameters, an index is calculated to characterize the load imbalance between each motor drive unit. Based on the load imbalance index, the speed commands issued to at least one of the motor controllers are dynamically and differentially adjusted so that the load operating state of each motor drive unit tends to be balanced. The specific calculation process for the load imbalance index is as follows: Calculate the integral value of the load operating parameters of each motor controller within a time window; The arithmetic mean of the integral values ​​of all motor controllers is calculated, and the arithmetic mean is used as the load imbalance index. Based on the load imbalance index, the speed commands sent to the motor controller are dynamically and differentially adjusted, specifically including: When the ratio of the load operating parameter of a certain motor controller to the load imbalance index is less than or equal to the set first threshold, the speed command issued to the motor controller remains unchanged. When the ratio of the load operating parameter of a certain motor controller to the load imbalance index is greater than the set first threshold, the speed command sent to the motor controller is reduced according to the preset strategy. The step-by-step adjustment method used to reduce the speed command sent to the motor controller according to the preset strategy includes: Based on predefined rules, a speed adjustment amount is determined in each adjustment cycle, and the speed command issued to the motor controller is successively reduced according to the speed adjustment amount; wherein, the sum of the speed adjustment amounts in all adjustment cycles constitutes a cumulative adjustment amount, and the cumulative adjustment amount does not exceed a preset maximum speed adjustment amount; In the process of reducing the speed command of a motor controller, the method further includes a hysteresis recovery step: If the ratio of the load operating parameter to the load imbalance index of a certain motor controller is less than or equal to the difference between the set first threshold and the hysteresis value, then the speed command of the motor controller is stopped from being reduced further. Subsequently, the recovery process is started to gradually restore the speed command issued to the motor controller to the reference speed command.

2. The cooperative control method of a multi-motor drive system according to claim 1, characterized by, The load operating parameter is the output current of the motor controller; or, the load operating parameter is the torque command value or torque feedback value generated internally by the motor controller in speed control mode.

3. The method of claim 1, wherein, The upper-level controller is either the vehicle controller or a motor controller designated as the main controller; the reference speed command is obtained by converting the target vehicle speed based on vehicle parameters.

4. A coordinated control system for a multi-motor drive system, the drive system comprising at least two motor drive units, each of the motor drive units comprising a motor controller and a motor driven by the motor controller. Each of the motor controllers operates in speed control mode and is used to receive and drive the corresponding motor according to the speed command issued by the upper controller; The control system includes a higher-level controller, characterized in that... The upper-level controller is used for: Generate a reference speed command and send it to each motor controller; The load operating parameters of each motor controller are acquired in real time; wherein the load operating parameters are used to characterize the real-time load status of the motor. Based on the load operating parameters, an index is calculated to characterize the load imbalance between each motor drive unit. Based on the load imbalance index, the speed commands issued to at least one of the motor controllers are dynamically and differentially adjusted to make the load operating state of each motor drive unit tend to be balanced. The specific calculation process for the load imbalance index is as follows: Calculate the integral value of the load operating parameters of each motor controller within a time window; The arithmetic mean of the integral values ​​of all motor controllers is calculated, and the arithmetic mean is used as the load imbalance index. Based on the load imbalance index, the speed commands sent to the motor controller are dynamically and differentially adjusted, specifically including: When the ratio of the load operating parameter of a certain motor controller to the load imbalance index is less than or equal to the set first threshold, the speed command issued to the motor controller remains unchanged. When the ratio of the load operating parameter of a certain motor controller to the load imbalance index is greater than the set first threshold, the speed command sent to the motor controller is reduced according to the preset strategy. The step-by-step adjustment method used to reduce the speed command sent to the motor controller according to the preset strategy includes: Based on predefined rules, a speed adjustment amount is determined in each adjustment cycle, and the speed command issued to the motor controller is successively reduced according to the speed adjustment amount; wherein, the sum of the speed adjustment amounts in all adjustment cycles constitutes a cumulative adjustment amount, and the cumulative adjustment amount does not exceed a preset maximum speed adjustment amount; The process of reducing the speed command of a motor controller also includes a hysteresis recovery step: If the ratio of the load operating parameter to the load imbalance index of a certain motor controller is less than or equal to the difference between the set first threshold and the hysteresis value, then the speed command of the motor controller is stopped from being reduced further. Subsequently, the recovery process is started to gradually restore the speed command issued to the motor controller to the reference speed command.

5. A vehicle, which is an electric vehicle or an aerial work platform, characterized by The electric vehicle or aerial work platform includes the collaborative control system of the multi-motor drive system as described in claim 4.

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