A synchronization control method of a dual-motor drive system
Patent Information
- Application Number
- CN202611260615.7
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2026-08-19
- Publication Date
- 2026-10-09
AI Technical Summary
在整个运行过程中使用同一组参数，忽略了双电机驱动系统在不同运行阶段对控制参数需求的根本差异，在启动加速段，系统速度指令由零阶跃至目标值，两电机因负载差异和响应延迟必然产生瞬时速差，此时需要较大的耦合增益以快速拉回同步，该阶段积分作用的持续累积容易导致积分饱和，引发转速超调和系统振荡，在稳态运行段，系统速度趋于稳定，负载扰动是影响同步精度的主要因素，此时需要适度积分作用消除静态误差，但过强的耦合增益会使微小扰动引起持续的调节动作，反而降低稳态同步精度
该一种双电机驱动系统的同步控制方法，通过基于速度接近度和速度变化率协同识别的运行阶段实时判断方法，能够准确区分启动加速段与稳态运行段，为控制参数的精确切换提供可靠的触发条件，解决了传统方法中因阶段误判导致的参数错配问题，在启动加速段采用强耦合增益配合极小积分系数、在稳态运行段采用弱耦合增益配合正常积分系数的分段差异化参数配置策略，直接解决了固定参数控制中启动段强耦合与积分作用叠加导致的积分饱和及超调振荡问题，以及稳态段弱耦合无法消除静差的矛盾，使两阶段对控制参数的需求在同一框架下均得到满足，通过运行阶段切换时引入参数线性过渡机制，在预设切换窗口内将控制参数从切换前值渐进调整至切换后值，解决不平稳问题，保证控制的连续性和系统稳定性，基于当前阶段选定的耦合增益和实时同步误差生成补偿量，以相反符号分别叠加至两电机速度给定值，形成协同调节效果，使双电机在启动加速段快速趋于同步，在稳态运行段精确保持同步，同步精度显著提高。
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Figure CN122890929A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of motor synchronization control technology, and in particular to a synchronization control method for a dual-motor drive system. Background Technology
[0002] Dual-motor drive systems are widely used in industrial applications such as high-precision CNC machine tools, large conveying equipment, and robot joint drives. Compared with single-motor drives, dual-motor drives have advantages such as high output power, flexible structural layout, and high system redundancy. However, due to the inevitable differences in mechanical connections, inconsistent electrical parameters, and unbalanced external load disturbances between the two motors, asynchronous speeds occur during operation, which seriously affects the transmission accuracy and operational stability of the system. To address this, a cross-coupling control strategy has been proposed and widely applied. Its core idea is to use the speed difference between the two motors as a feedback signal to compensate for the speed setpoint of each motor in the opposite direction, thereby achieving synchronous adjustment.
[0003] However, existing cross-coupling control schemes, which generally use fixed parameters for cross-coupling gain and integral coefficients, have the following problems in practical applications: Using the same set of parameters throughout the entire operation ignores the fundamental differences in the control parameter requirements of the dual-motor drive system at different operating stages. During the start-up acceleration phase, the system speed command jumps from zero to the target value. Due to load differences and response delays, the two motors will inevitably have an instantaneous speed difference. At this time, a large coupling gain is required to quickly pull back to synchronization. The continuous accumulation of integral action in this phase can easily lead to integral saturation, causing speed overshoot and system oscillation. In the steady-state operation phase, the system speed tends to stabilize, and load disturbances are the main factors affecting synchronization accuracy. At this time, a moderate integral action is required to eliminate static errors. However, excessive coupling gain will cause small disturbances to cause continuous adjustment actions, which will reduce the steady-state synchronization accuracy.
[0004] To address the aforementioned technical shortcomings, a solution is proposed. Summary of the Invention
[0005] The present invention adopts the following technical solution: a synchronous control method for a dual-motor drive system, comprising the following steps: Step 1: Real-time acquisition of the actual speeds of the first and second motors and the speed commands given by the system; Calculation of the average speed and synchronization error speed of the two motors based on the actual speeds and speed commands. Step 2: Based on the speed command, average rotational speed, and synchronization error speed, calculate the speed proximity and speed change rate. Compare the speed proximity with the preset speed proximity threshold and the speed change rate status with the preset speed change rate threshold to determine the current operating stage, including the tunnel acceleration stage and the steady-state operating stage. Step 3: When it is determined that the system is in the startup acceleration phase, cross-coupling control is performed using the first coupling gain coefficient and the first integral coefficient. When it is determined that the system is in the steady-state operation phase, cross-coupling control is performed using the second coupling gain coefficient and the second integral coefficient. Step 4: Calculate the coupling compensation amount based on the synchronization error between the two motors and the currently selected coupling gain coefficient. Add the coupling compensation amount to the speed setpoints of the first motor and the second motor respectively with opposite signs to generate the compensated speed command. Step 5: When a switch occurs during the operation phase, within the preset switch transition time window, the control parameters gradually transition from the parameter values before the switch to the parameter values after the switch.
[0006] Furthermore, the actual speeds of the first and second motors, as well as the speed commands given by the system, are collected in real time. Based on the actual speeds and speed commands, the average speed, synchronization error, speed proximity, and speed change rate of the two motors are calculated. The specific process is as follows: The actual speeds of the first and second motors are collected at fixed sampling periods by encoders installed on the shafts of the first and second motors, and then filtered. Substitute the filtered actual speeds of the first and second motors into the average speed formula to calculate the average speed of the two motors, and calculate the instantaneous synchronization error between the first and second motors. The sign of the error indicates the direction of the speed deviation, and the absolute value reflects the degree of asynchrony between the two motors. The speed change rate is calculated by dividing the average speed difference between the current time and the previous sampling time by the sampling period. The speed change rate is used in the speed change rate criterion in the stage identification criterion to reflect whether the system is currently accelerating, decelerating or in steady state.
[0007] Furthermore, by comparing the speed proximity with a preset speed proximity threshold, and comparing the speed change rate status with a preset speed change rate threshold, the current operating stage is determined, including the acceleration start-up stage and the steady-state operating stage. The specific process is as follows: S21. Based on the speed command and the actual speed of the two motors, calculate the speed proximity criterion. The speed proximity criterion represents the degree of proximity between the current average speed and the target speed command. Based on the time change rate of the average speed of the two motors, calculate the speed change rate criterion. The speed change rate criterion represents the dynamic change state of the system, whether it is currently accelerating, decelerating or in a steady state. S22. Compare the speed proximity criterion with the preset speed proximity threshold, and compare the speed change rate criterion with the preset speed change rate threshold. When the speed proximity criterion is greater than the preset speed proximity threshold, determine that the current system is in the startup acceleration phase. When the speed change rate criterion is greater than the preset speed change rate threshold, determine that the current system is in the startup acceleration phase. S23. When the speed proximity criterion is less than or equal to the preset speed proximity threshold and the speed change rate criterion is less than or equal to the preset speed change rate threshold, the system is determined to be in a steady-state operation segment.
[0008] Furthermore, when the system is determined to be in the startup acceleration phase, cross-coupling control is performed using the first coupling gain coefficient and the first integral coefficient. When the system is determined to be in the steady-state operation phase, cross-coupling control is performed using the second coupling gain coefficient and the second integral coefficient. The specific process is as follows: S31. A first parameter group for the startup acceleration phase and a second parameter group for the steady-state operation phase are preset. The first parameter group includes a first coupling gain coefficient and a first integral coefficient, and the second parameter group includes a second coupling gain coefficient and a second integral coefficient. S32. When the system is determined to be in the startup acceleration phase, the coupling gain coefficient of the cross-coupling control is switched to the first coupling gain coefficient, and the integral coefficient is switched to the first integral coefficient. The value of the first coupling gain coefficient makes the system have a strong coupling effect in the startup phase, and the value of the first integral coefficient makes the integral effect suppressed to the minimum. When the system is in the startup acceleration phase, the integral coefficient is set to zero, and no integral accumulation occurs during the startup phase. When the speed proximity criterion first meets the steady-state entry condition, the integral coefficient of the startup phase is kept running for a preset delay time. After the system has fully entered the steady-state operation phase, the integral coefficient is gradually restored to the normal value. The preset delay time is greater than the sum of the response times of the system current loop and speed loop, ensuring that the system has exited the saturation region before the integral action is re-engaged. S33. When the system is determined to be in the steady-state operating segment, the coupling gain coefficient of the cross-coupling control is switched to the second coupling gain coefficient, and the integral coefficient is switched to the second integral coefficient. The value of the second coupling gain coefficient makes the system have a weak coupling effect in the steady-state stage, and the value of the second integral coefficient makes the integral action normally engaged to eliminate steady-state error.
[0009] Furthermore, the coupling compensation amount is calculated based on the synchronization error between the two motors and the currently selected coupling gain coefficient. The coupling compensation amount is then superimposed on the speed setpoints of the first motor and the second motor with opposite signs to generate the compensated speed command. The specific process is as follows: S41. Calculate the difference between the actual speed of the first motor and the actual speed of the second motor to obtain the synchronization error between the two motors. A positive value of the synchronization error indicates that the speed of the first motor is higher than that of the second motor, and a negative value indicates that the speed of the first motor is lower than that of the second motor. S42. Multiply the synchronization error by the currently selected coupling gain coefficient to obtain the coupling compensation amount. When the synchronization error is positive, the coupling compensation amount is positive and is used to reduce the speed command of the first motor and increase the speed command of the second motor. When the synchronization error is negative, the coupling compensation amount is negative and is used to increase the speed command of the first motor and reduce the speed command of the second motor. S43. The coupling compensation amount is superimposed on the speed setpoints of the first motor and the second motor with opposite signs. The speed command of the first motor after compensation is the original speed command plus the coupling compensation amount, and the speed command of the second motor after compensation is the original speed command minus the coupling compensation amount, so that the motor with higher speed decelerates and the motor with lower speed accelerates.
[0010] Furthermore, when a switch occurs during the operation phase, within a preset transition time window, the control parameters gradually transition from their pre-switch values to their post-switch values. The specific process is as follows: S51. When a switch occurs during the operation phase, record the switch trigger time and determine the length of the switch transition time window. The switch transition time window is greater than a single control cycle and less than the upper limit of the response delay that the system can tolerate. S52. Within the switching transition time window, calculate the control parameter values at the current moment using linear interpolation, so that the coupling gain coefficient and integral coefficient gradually change from the parameter values before switching to the parameter values after switching, with the rate of change being constant. S53. After the transition time window ends, the control parameters are completely switched to the target parameter values, and cross-coupling control continues with the switched parameter values.
[0011] Furthermore, after generating the synchronization compensation amount, the following compensation amount limiting protection steps are also performed: S801. Based on the rated torque of the first motor and the second motor and the current operating status, calculate the available torque margin of the first motor and the second motor respectively. The available torque margin is the maximum allowable output torque of the motor minus the current actual output torque. S802. Calculate the maximum permissible compensation amount for the first motor and the second motor in a single step based on the available torque margin. When the coupling compensation amount exceeds the maximum permissible compensation amount in a single step, limit the coupling compensation amount to the maximum permissible compensation amount in a single step, and add the limited compensation amount to the speed setpoint. S803. When the available torque margin of any motor is lower than the preset safety threshold, the synchronous control degradation mode is triggered. In the degradation mode, the coupling gain coefficient is switched to the preset safety gain value, and the compensation amount is generated with the safety gain value until the motor torque margin is restored to above the safety threshold.
[0012] In summary, due to the adoption of the above technical solution, the beneficial effects of the present invention are: This synchronous control method for a dual-motor drive system accurately distinguishes between the start-up acceleration phase and the steady-state operation phase through a real-time judgment method based on the collaborative identification of speed proximity and speed change rate. This provides reliable triggering conditions for precise switching of control parameters and solves the parameter mismatch problem caused by misjudgment of phases in traditional methods. The method employs a segmented differentiated parameter configuration strategy, using a strongly coupled gain with a minimal integral coefficient in the start-up acceleration phase and a weakly coupled gain with a normal integral coefficient in the steady-state operation phase. This directly solves the integral saturation and overshoot oscillation problems caused by the superposition of strong coupling and integral action in the start-up phase of fixed-parameter control. The contradiction that weak coupling in the steady-state section cannot eliminate steady-state error is addressed by ensuring that the control parameter requirements of both stages are met within the same framework. By introducing a linear transition mechanism for parameters during the switching of operating stages, the control parameters are gradually adjusted from the pre-switching value to the post-switching value within the preset switching window, solving the instability problem and ensuring the continuity of control and system stability. Based on the selected coupling gain and real-time synchronization error of the current stage, a compensation amount is generated and superimposed on the speed setpoints of the two motors with opposite signs to form a synergistic adjustment effect, enabling the two motors to quickly approach synchronization in the start-up acceleration stage and accurately maintain synchronization in the steady-state operation stage, significantly improving synchronization accuracy. Attached Figure Description
[0013] Figure 1 A schematic diagram of the overall steps of the method of the present invention is shown. Detailed Implementation
[0014] To further illustrate the technical means and effects of the present invention in achieving its intended purpose, the following detailed description of the specific implementation methods, structures, features and effects of the present invention, in conjunction with the accompanying drawings and preferred embodiments, is provided below.
[0015] Example: like Figure 1 As shown, a synchronous control method for a dual-motor drive system includes the following steps: Step 1: Real-time acquisition of the actual speeds of the first and second motors and the speed commands given by the system; Calculation of the average speed and synchronization error speed of the two motors based on the actual speeds and speed commands. Step 2: Based on the speed command, average rotational speed, and synchronization error speed, calculate the speed proximity and speed change rate. Compare the speed proximity with the preset speed proximity threshold and the speed change rate status with the preset speed change rate threshold to determine the current operating stage, including the tunnel acceleration stage and the steady-state operating stage. Step 3: When it is determined that the system is in the startup acceleration phase, cross-coupling control is performed using the first coupling gain coefficient and the first integral coefficient. When it is determined that the system is in the steady-state operation phase, cross-coupling control is performed using the second coupling gain coefficient and the second integral coefficient. Step 4: Calculate the coupling compensation amount based on the synchronization error between the two motors and the currently selected coupling gain coefficient. Add the coupling compensation amount to the speed setpoints of the first motor and the second motor respectively with opposite signs to generate the compensated speed command. Step 5: When a switch occurs during the operation phase, within the preset switch transition time window, the control parameters gradually transition from the parameter values before the switch to the parameter values after the switch.
[0016] The actual speeds of the first and second motors, as well as the speed commands given by the system, are collected in real time. Based on the actual speeds and speed commands, the average speed, synchronization error, speed proximity, and speed change rate of the two motors are calculated. The specific process is as follows: The actual speeds of the first and second motors are collected at a fixed sampling period by encoders installed on the shafts of the first and second motors, and then filtered. Substitute the filtered actual speeds of the first and second motors into the average speed formula to calculate the average speed of the two motors, and calculate the instantaneous synchronization error between the first and second motors. The sign of the error indicates the direction of the speed deviation, and the absolute value reflects the degree of asynchrony between the two motors. The speed change rate is calculated by dividing the average speed difference between the current time and the previous sampling time by the sampling period. The speed change rate is used in the speed change rate criterion in the stage identification criterion to reflect whether the system is currently accelerating, decelerating or in steady state.
[0017] The current operating phase is determined by comparing the speed proximity with a preset speed proximity threshold, and by comparing the speed change rate status with a preset speed change rate threshold. This includes the initial acceleration phase and the steady-state operating phase. The specific process is as follows: S21. Based on the speed command and the actual speed of the two motors, calculate the speed proximity criterion. The speed proximity criterion represents the degree of proximity between the current average speed and the target speed command. Based on the time change rate of the average speed of the two motors, calculate the speed change rate criterion. The speed change rate criterion represents the dynamic change state of the system, whether it is currently accelerating, decelerating or in a steady state. S22. Compare the speed proximity criterion with the preset speed proximity threshold, and compare the speed change rate criterion with the preset speed change rate threshold. When the speed proximity criterion is greater than the preset speed proximity threshold, determine that the current system is in the startup acceleration phase. When the speed change rate criterion is greater than the preset speed change rate threshold, determine that the current system is in the startup acceleration phase. Speed proximity threshold: This is set according to the system's accuracy requirements for dividing the start-up acceleration phase and the steady-state operation phase. The smaller the threshold, the more stringent the conditions for entering the steady state and the longer the start-up phase lasts. It should be determined based on the motor's rated speed and the allowable speed tracking error. Usually, 5%-10% of the rated speed is taken as an engineering reference value. Speed change rate threshold: determined based on the maximum acceleration capability and load inertia of the drive system, it reflects the judgment boundary of the system from the dynamic adjustment process to the steady state process. By measuring the speed change rate curve of the system during rated acceleration, 60%-80% of it is taken as the threshold, so that the system maintains the start-up control mode during normal acceleration and automatically switches to the steady state mode after acceleration ends. S23. When the speed proximity criterion is less than or equal to the preset speed proximity threshold and the speed change rate criterion is less than or equal to the preset speed change rate threshold, the system is determined to be in a steady-state operation segment.
[0018] When the system is determined to be in the startup acceleration phase, cross-coupling control is performed using the first coupling gain coefficient and the first integral coefficient. When the system is determined to be in the steady-state operation phase, cross-coupling control is performed using the second coupling gain coefficient and the second integral coefficient. The specific process is as follows: S31. A first parameter group for the startup acceleration phase and a second parameter group for the steady-state operation phase are preset. The first parameter group includes a first coupling gain coefficient and a first integral coefficient, and the second parameter group includes a second coupling gain coefficient and a second integral coefficient. S32. When the system is determined to be in the startup acceleration phase, the coupling gain coefficient of the cross-coupling control is switched to the first coupling gain coefficient, and the integral coefficient is switched to the first integral coefficient. The value of the first coupling gain coefficient makes the system have a strong coupling effect in the startup phase, and the value of the first integral coefficient makes the integral effect suppressed to the minimum. When the system is in the startup acceleration phase, the integral coefficient is set to zero, and no integral accumulation occurs during the startup phase. When the speed proximity criterion first meets the steady-state entry condition, the integral coefficient of the startup phase is kept running for a preset delay time. After the system has fully entered the steady-state operation phase, the integral coefficient is gradually restored to the normal value. The preset delay time is greater than the sum of the response times of the system current loop and speed loop, ensuring that the system has exited the saturation region before the integral action is re-engaged. S33. When the system is determined to be in the steady-state operating segment, the coupling gain coefficient of the cross-coupling control is switched to the second coupling gain coefficient, and the integral coefficient is switched to the second integral coefficient. The value of the second coupling gain coefficient makes the system have a weak coupling effect in the steady-state stage, and the value of the second integral coefficient makes the integral action normally engaged to eliminate steady-state error.
[0019] The coupling compensation amount is calculated based on the synchronization error between the two motors and the currently selected coupling gain coefficient. The coupling compensation amount is then superimposed on the speed setpoints of the first motor and the second motor with opposite signs to generate the compensated speed command. The specific process is as follows: S41. Calculate the difference between the actual speed of the first motor and the actual speed of the second motor to obtain the synchronization error between the two motors. A positive value of the synchronization error indicates that the speed of the first motor is higher than that of the second motor, and a negative value indicates that the speed of the first motor is lower than that of the second motor. S42. Multiply the synchronization error by the currently selected coupling gain coefficient to obtain the coupling compensation amount. The specific process is as follows: Startup acceleration segment parameters: ; Steady-state operating parameters: ; Calculate the coupling compensation amount: ; When the synchronization error is positive, the coupling compensation is positive, used to reduce the speed command of the first motor and increase the speed command of the second motor. When the synchronization error is negative, the coupling compensation is negative, used to increase the speed command of the first motor and reduce the speed command of the second motor.
[0020] In the above formula, The currently selected cross-coupling gain coefficient. The coupling gain coefficient used to start the acceleration phase. For the currently selected integration coefficient, The integral coefficient used to initiate the acceleration phase. These are the parameter values before the switch. Standard integral coefficients used for steady-state operation. This is the coupling compensation amount superimposed on the first motor. This is the coupling compensation amount superimposed on the second motor. This refers to the synchronization error between the two motors. = - , This represents the actual speed of the first motor. This is the actual speed of the second motor. To compensate for the speed command of the first motor, The speed command given by the system, The speed command for the second motor after compensation; First coupling gain coefficient: set according to the maximum allowable synchronization error of the system and the acceptable adjustment intensity during the startup phase. The value should ensure that the speed difference can be quickly pulled back under the worst startup conditions. It is usually 1.5 to 2 times the traditional fixed parameter. It is adjusted to the maximum value that does not cause oscillation through step response test. The second coupling gain coefficient is set according to the requirements of disturbance suppression and noise immunity during steady-state operation. The value should ensure that the system does not generate frequent adjustments under small disturbances. It is usually 0.5 to 0.7 times the traditional fixed parameter, with the steady-state synchronization error meeting the accuracy requirements and not oscillating as the criterion. First integral coefficient and second integral coefficient: The integral coefficient in the starting segment is set to 0 to directly avoid integral saturation; the integral coefficient in the steady-state segment is determined by the conventional PI tuning method, with the goal of eliminating steady-state error, and is determined by the cutoff frequency and phase margin of the system's open-loop transfer function. S43. The coupling compensation amount is superimposed on the speed setpoints of the first motor and the second motor with opposite signs. The speed command of the first motor after compensation is the original speed command plus the coupling compensation amount, and the speed command of the second motor after compensation is the original speed command minus the coupling compensation amount, so that the motor with higher speed decelerates and the motor with lower speed accelerates.
[0021] When a switch occurs during the operation phase, within a preset transition time window, the control parameters gradually transition from their pre-switch values to their post-switch values. The specific process is as follows: S51. When a switch occurs during the operation phase, record the switch trigger time and determine the length of the switch transition time window. The switch transition time window is greater than a single control cycle and less than the upper limit of the response delay that the system can tolerate. S52. Within the switching transition time window, calculate the control parameter values at the current moment using linear interpolation, so that the coupling gain coefficient and integral coefficient gradually change from the parameter values before switching to the parameter values after switching, with the rate of change being constant. The specific calculation for smooth parameter transition during switching is as follows:
[0022]
[0023] Let be the real-time coupling gain coefficient at time t. The target coupling gain coefficient after switching. As a normalized transition factor, The coupling gain coefficient before switching. For the current moment, To switch the trigger time, To facilitate the transition time window, this formula is used to achieve a smooth transition of control parameters during the switching phase of operation, avoiding torque shocks and speed fluctuations caused by sudden parameter changes. S53. After the transition time window ends, the control parameters are completely switched to the target parameter values, and cross-coupling control continues with the switched parameter values.
[0024] After generating the synchronization compensation amount, the following compensation amount limiting protection steps are also performed: S801. Based on the rated torque of the first motor and the second motor and the current operating status, calculate the available torque margin of the first motor and the second motor respectively. The available torque margin is the maximum allowable output torque of the motor minus the current actual output torque. S802. Calculate the maximum permissible compensation amount for the first motor and the second motor in a single step based on the available torque margin. When the coupling compensation amount exceeds the maximum permissible compensation amount in a single step, limit the coupling compensation amount to the maximum permissible compensation amount in a single step, and add the limited compensation amount to the speed setpoint. S803. When the available torque margin of any motor is lower than the preset safety threshold, the synchronous control degradation mode is triggered. In the degradation mode, the coupling gain coefficient is switched to the preset safety gain value, and the compensation amount is generated with the safety gain value until the motor torque margin is restored to above the safety threshold.
[0025] Safety threshold: Determined based on the motor's rated torque and the load torque requirement under current operating conditions, it is usually set to 20%-30% of the rated torque to ensure that the motor still has sufficient torque reserve to maintain synchronous operation when encountering sudden load disturbances. This value needs to be comprehensively calibrated in conjunction with the motor's overload capacity curve and the maximum allowable load fluctuation range of the system. When the actual torque margin is lower than this threshold, the system is judged to be in the heavy load danger zone, and it is necessary to switch to the strong coupling control mode or limit the load change rate.
[0026] The size of the interval and threshold is set to facilitate comparison. The size of the threshold depends on the amount of sample data and the number of bases set by those skilled in the art for each set of sample data; as long as it does not affect the ratio between the parameter and the quantized value.
[0027] The above formulas are all dimensionless calculations. The formulas are derived from software simulations based on a large amount of collected data to obtain the most recent real-world results. The preset parameters in the formulas are set by those skilled in the art according to the actual situation. In the embodiments provided in this application, it should be understood that the disclosed methods can be implemented in other ways; for example, the method embodiments described above are merely illustrative. For example, the division of modules is merely a logical functional division, and there may be other division methods in actual implementation. For example, multiple modules or components may be combined or integrated into another system, or some features may be ignored or not executed. Furthermore, the coupling or direct coupling or communication connection between the shown or discussed components may be indirect coupling or communication connection through some interfaces, devices or modules, and may be electrical, mechanical or other forms. The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make some modifications or alterations to the above-disclosed technical content to create equivalent embodiments without departing from the scope of the present invention. Any simple modifications, equivalent changes and alterations made to the above embodiments based on the technical essence of the present invention without departing from the scope of the present invention shall still fall within the scope of the present invention.
Claims
1. A synchronous control method for a dual-motor drive system, characterized in that, Includes the following steps: Step 1: Real-time acquisition of the actual speeds of the first and second motors and the speed commands given by the system; Calculation of the average speed and synchronization error speed of the two motors based on the actual speeds and speed commands. Step 2: Based on the speed command, average rotational speed, and synchronization error speed, calculate the speed proximity and speed change rate. Compare the speed proximity with the preset speed proximity threshold and the speed change rate status with the preset speed change rate threshold to determine the current operating stage, including the tunnel acceleration stage and the steady-state operating stage. Step 3: When it is determined that the system is in the startup acceleration phase, cross-coupling control is performed using the first coupling gain coefficient and the first integral coefficient. When it is determined that the system is in the steady-state operation phase, cross-coupling control is performed using the second coupling gain coefficient and the second integral coefficient. Step 4: Calculate the coupling compensation amount based on the synchronization error between the two motors and the currently selected coupling gain coefficient. Add the coupling compensation amount to the speed setpoints of the first motor and the second motor respectively with opposite signs to generate the compensated speed command. Step 5: When a switch occurs during the operation phase, within the preset switch transition time window, the control parameters gradually transition from the parameter values before the switch to the parameter values after the switch.
2. The synchronous control method for a dual-motor drive system according to claim 1, characterized in that, The actual speeds of the first and second motors, as well as the speed commands given by the system, are collected in real time. Based on the actual speeds and speed commands, the average speed, synchronization error, speed proximity, and speed change rate of the two motors are calculated. The specific process is as follows: The actual speeds of the first and second motors are collected at fixed sampling periods by encoders installed on the shafts of the first and second motors, and then filtered. Substitute the filtered actual speeds of the first and second motors into the average speed formula to calculate the average speed of the two motors, and calculate the instantaneous synchronization error between the first and second motors. The sign of the error indicates the direction of the speed deviation, and the absolute value reflects the degree of asynchrony between the two motors. The speed change rate is calculated by dividing the average speed difference between the current time and the previous sampling time by the sampling period. The speed change rate is used in the speed change rate criterion in the stage identification criterion to reflect whether the system is currently accelerating, decelerating or in steady state.
3. The synchronous control method for a dual-motor drive system according to claim 1, characterized in that, The current operating phase is determined by comparing the speed proximity with a preset speed proximity threshold, and by comparing the speed change rate status with a preset speed change rate threshold. This includes the initial acceleration phase and the steady-state operating phase. The specific process is as follows: S21. Based on the speed command and the actual speed of the two motors, calculate the speed proximity criterion. The speed proximity criterion represents the degree of proximity between the current average speed and the target speed command. Based on the time change rate of the average speed of the two motors, calculate the speed change rate criterion. The speed change rate criterion represents the dynamic change state of the system, whether it is currently accelerating, decelerating or in a steady state. S22. Compare the speed proximity criterion with the preset speed proximity threshold, and compare the speed change rate criterion with the preset speed change rate threshold. When the speed proximity criterion is greater than the preset speed proximity threshold, determine that the current system is in the startup acceleration phase. When the speed change rate criterion is greater than the preset speed change rate threshold, determine that the current system is in the startup acceleration phase. S23. When the speed proximity criterion is less than or equal to the preset speed proximity threshold and the speed change rate criterion is less than or equal to the preset speed change rate threshold, the system is determined to be in a steady-state operation segment.
4. The synchronous control method for a dual-motor drive system according to claim 1, characterized in that, When the system is determined to be in the startup acceleration phase, cross-coupling control is performed using the first coupling gain coefficient and the first integral coefficient. When the system is determined to be in the steady-state operation phase, cross-coupling control is performed using the second coupling gain coefficient and the second integral coefficient. The specific process is as follows: S31. A first parameter group for the startup acceleration phase and a second parameter group for the steady-state operation phase are preset. The first parameter group includes a first coupling gain coefficient and a first integral coefficient, and the second parameter group includes a second coupling gain coefficient and a second integral coefficient. S32. When the system is determined to be in the startup acceleration phase, the coupling gain coefficient of the cross-coupling control is switched to the first coupling gain coefficient, and the integral coefficient is switched to the first integral coefficient. The value of the first coupling gain coefficient makes the system have a strong coupling effect in the startup phase, and the value of the first integral coefficient makes the integral effect suppressed to the minimum. When the system is in the startup acceleration phase, the integral coefficient is set to zero, and no integral accumulation occurs during the startup phase. When the speed proximity criterion first meets the steady-state entry condition, the integral coefficient of the startup phase is kept running for a preset delay time. After the system has fully entered the steady-state operation phase, the integral coefficient is gradually restored to the normal value. The preset delay time is greater than the sum of the response times of the system current loop and speed loop, ensuring that the system has exited the saturation region before the integral action is re-engaged. S33. When the system is determined to be in the steady-state operating segment, the coupling gain coefficient of the cross-coupling control is switched to the second coupling gain coefficient, and the integral coefficient is switched to the second integral coefficient. The value of the second coupling gain coefficient makes the system have a weak coupling effect in the steady-state stage, and the value of the second integral coefficient makes the integral action normally engaged to eliminate steady-state error.
5. The synchronous control method for a dual-motor drive system according to claim 1, characterized in that, The coupling compensation amount is calculated based on the synchronization error between the two motors and the currently selected coupling gain coefficient. The coupling compensation amount is then superimposed on the speed setpoints of the first motor and the second motor with opposite signs to generate the compensated speed command. The specific process is as follows: S41. Calculate the difference between the actual speed of the first motor and the actual speed of the second motor to obtain the synchronization error between the two motors. A positive value of the synchronization error indicates that the speed of the first motor is higher than that of the second motor, and a negative value indicates that the speed of the first motor is lower than that of the second motor. S42. Multiply the synchronization error by the currently selected coupling gain coefficient to obtain the coupling compensation amount. When the synchronization error is positive, the coupling compensation amount is positive and is used to reduce the speed command of the first motor and increase the speed command of the second motor. When the synchronization error is negative, the coupling compensation amount is negative and is used to increase the speed command of the first motor and reduce the speed command of the second motor. S43. The coupling compensation amount is superimposed on the speed setpoints of the first motor and the second motor with opposite signs. The speed command of the first motor after compensation is the original speed command plus the coupling compensation amount, and the speed command of the second motor after compensation is the original speed command minus the coupling compensation amount, so that the motor with higher speed decelerates and the motor with lower speed accelerates.
6. The synchronous control method for a dual-motor drive system according to claim 1, characterized in that, When a switch occurs during the operation phase, within a preset transition time window, the control parameters gradually transition from their pre-switch values to their post-switch values. The specific process is as follows: S51. When a switch occurs during the operation phase, record the switch trigger time and determine the length of the switch transition time window. The switch transition time window is greater than a single control cycle and less than the upper limit of the response delay that the system can tolerate. S52. Within the switching transition time window, calculate the control parameter values at the current moment using linear interpolation, so that the coupling gain coefficient and integral coefficient gradually change from the parameter values before switching to the parameter values after switching, with the rate of change being constant. S53. After the transition time window ends, the control parameters are completely switched to the target parameter values, and cross-coupling control continues with the switched parameter values.
7. The synchronous control method for a dual-motor drive system according to claim 1, characterized in that, After generating the synchronization compensation amount, the following compensation amount limiting protection steps are also performed: S801. Based on the rated torque of the first motor and the second motor and the current operating status, calculate the available torque margin of the first motor and the second motor respectively. The available torque margin is the maximum allowable output torque of the motor minus the current actual output torque. S802. Calculate the maximum permissible compensation amount for the first motor and the second motor in a single step based on the available torque margin. When the coupling compensation amount exceeds the maximum permissible compensation amount in a single step, limit the coupling compensation amount to the maximum permissible compensation amount in a single step, and add the limited compensation amount to the speed setpoint. S803. When the available torque margin of any motor is lower than the preset safety threshold, the synchronous control degradation mode is triggered. In the degradation mode, the coupling gain coefficient is switched to the preset safety gain value, and the compensation amount is generated with the safety gain value until the motor torque margin is restored to above the safety threshold.