A torque balance control method for a multi-motor rigid gear transmission system

Abstract

A torque balance control method for a multi-motor rigid gear transmission system includes the following steps: Step 1: Real-time calculation of the electromagnetic torque of each motor; Step 2: Real-time compensation of each motor. The electromagnetic torque of each motor is subtracted from the electromagnetic torque of the other motors, summed, and then multiplied by the coupling gain coefficient to obtain the compensation torque for that motor. This compensation torque is then input into the motor's torque outer loop. This method ensures balanced torque output during system operation when disturbance errors occur, improving system safety and stability, and torque output synchronization, meeting the synchronization control requirements of most multi-motor rigid connection systems.

Description

Technical Field

[0001] The present invention relates to the technical field of multi-motor control, and in particular to a torque balance control method for a multi-motor rigid gear transmission system. Background Art

[0002] The multi-motor rigid connection structure is characterized by the motors being connected through a gear structure or a coaxial connection. In this way, the motors are forced to synchronize, but the output torques are coupled and affect each other. It is often used in high-power, low-speed situations in large-scale industrial operations, typically shield machines and bridge cranes.

[0003] For a multi-motor system with a gear transmission structure, if the motor parameters are identical and the gears connecting each motor are exactly the same, during normal system operation, each motor will be assigned the same load, and there will be no output torque imbalance. However, in reality, the motors and gears are unlikely to be exactly the same. Any deviation in the materials and parameters of the mechanical and electrical components will lead to uneven motor output. If a large disturbance or sudden load change occurs, the load torque distributed to each motor by the total system load will be seriously unbalanced, and the motor output torque will also be uneven. In severe cases, it can cause damage to the mechanical shaft or motor overload. Therefore, for multi-motor systems, it is particularly important to select an appropriate synchronous control strategy. It is necessary to achieve synchronous control of the motor part while considering the factors affecting the motor and load of the mechanical transmission part. This places higher demands on the field of multi-motor synchronous control and has very practical significance for the development of modern industry. Summary of the Invention

[0004] In order to solve the above technical problems, the present invention provides a torque balance control method for a multi-motor rigid gear transmission system. In order to ensure that the torque can maintain a balanced output when disturbance errors occur during the operation of the system, the system's safety and stability performance is improved, the torque output synchronization performance is improved, and the synchronization control requirements of most multi-motor rigid connection systems are met.

[0005] To achieve the above technical objectives, the technical solution adopted is: a torque balance control method for a multi-motor rigid gear transmission system, based on the multi-motor rigid gear transmission system, which includes multiple motors connected by gear structures or coaxially connected, and the multiple motors run synchronously, and the output torques are coupled with each other. The torque balance control method includes the following steps:

[0006] Step 1: Calculate the electromagnetic torque of each motor in real time;

[0007] Step 2: Perform real-time compensation on each motor. Subtract the electromagnetic torque of each motor from the electromagnetic torque of other motors, sum them up, and then multiply them by the coupling gain coefficient to obtain the compensation torque of the motor. The compensation torque of the motor is input into the torque outer loop of the motor.

[0008] Furthermore, the electromagnetic torque calculation method of the motor is:

[0009] T e =n p ψi st L m / L r

[0010] Among them, T e is the electromagnetic torque of the motor; n p is the number of motor pole pairs, ψ is the motor magnetic flux, L m is the excitation self-inductance, L r is the magnetizing inductance, i st is the stator current of the asynchronous motor t-axis in the two-phase stationary coordinate system.

[0011] Furthermore, the coupling gain coefficient is

[0012]

[0013] Among them, T emax 、T emin are the maximum and minimum values ​​of the electromagnetic torque output of all motors in the multi-motor rigid gear transmission system at the current moment, T ei is the electromagnetic torque of the i-th motor to be compensated.

[0014] The beneficial effects of the present invention are as follows: the traditional PI control method in the multi-motor rigid gear transmission system is difficult to effectively solve the problem of torque output imbalance caused by mechanical error or disturbance error. The present invention applies the speed deviation coupling control in the multi-motor uncoupled connection structure to the multi-motor rigid connection structure. By integrating the torque deviation information of all motors in the system and then selecting the appropriate coupling gain coefficient, the system torque synchronization error is reduced and the torque output fluctuation caused by the mechanical transmission structure is eliminated, making the output smoother and greatly enhancing the safety of the system operation. The results are as follows Figure 5-8 This method demonstrates that it can effectively reduce torque synchronization errors and eliminate torque output fluctuations in multi-motor rigid gear transmission systems. Compared with traditional PI control methods, this method has better control performance and provides a reference for more efficient and safer industry indicators in the multi-motor control industry. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 Schematic diagram of 4 motors and meshing gears;

[0016] Figure 2 Single motor control structure diagram;

[0017] Figure 3 Torque deviation coupling control principle diagram;

[0018] Figure 4 Simulation system structure diagram;

[0019] Figure 5 Torque of 4 motors under traditional PI control;

[0020] Figure 6 Torque of 4 motors under torque deviation coupling control;

[0021] Figure 7 Torque error of four motors under traditional PI control;

[0022] Figure 8 Torque errors of four motors under torque deviation coupling control. DETAILED DESCRIPTION

[0023] A torque balance control method for a multi-motor rigid gear transmission system is described. This method integrates all motor torque deviation information and, based on the Hurwitz stability principle, designs a new coupling gain coefficient to compensate for motor torque errors, thereby improving system stability. This method is implemented as a program in a processor (microcontroller, PLC, or DSP). The motor parameters required for calculation can be measured using the inverter's built-in monitoring equipment. After calculation, the processor inputs the compensation torque into the corresponding motor's outer torque loop.

[0024] The multi-motor rigid gear transmission system includes multiple motors connected by gear structures or coaxially connected. The multiple motors run synchronously and the output torques are coupled with each other. Figure 1 As shown, the four motors are rigidly connected with the gears and the four motors run synchronously.

[0025] The specific method is:

[0026] Step 1: Calculate the electromagnetic torque of each motor in real time.

[0027] The actual output mechanical torque of the system can be obtained from the motor-gear coupling model and the asynchronous motor vector control model. The motor-gear coupling model is as follows, and the motor control structure diagram is as follows: Figure 1 shown.

[0028]

[0029]

[0030] The electromagnetic torque equation of the motor is

[0031] T ei =n p ψi st L m / L r (3)

[0032] Among them, T ei is the electromagnetic torque of the i-th motor to be compensated, i = 1, 2...n.

[0033] The motor motion equation is

[0034]

[0035] The torque balance equation between the motor and the load can be established from equations (1) to (4):

[0036]

[0037] Step 2: Perform real-time compensation on each motor using the compensation torque equation. Subtract the electromagnetic torque of each motor from the electromagnetic torque of other motors, sum them up, and then multiply them by the coupling gain coefficient to obtain the compensation torque of the motor. The compensation torque of the motor is input into the torque outer loop of the motor.

[0038] In order to return the relative speed of each motor to zero during the transition period and torque disturbance, the traditional speed deviation coupling controller makes a difference between the output speed of the motor and the output speed of all other motors, and multiplies each difference by the speed feedback coupling gain coefficient K. ij Then sum it up to get the speed error compensation, so that the speed of the multi-motor system is synchronized, that is,

[0039]

[0040] Among them, K ij =J mi / J mj Referring to the speed deviation coupling control principle, the torque deviation coupling controller is defined, and the compensation torque equation is:

[0041]

[0042] Simplified

[0043]

[0044] After integrating all motor torque deviation information, the compensation torque T of motor i is obtained. e_ci After that, with the reference torque T e * , electromagnetic torque T e Subtract to get the t-axis reference current i st * , n is the total number of motors.

[0045] Select the coupling gain coefficient K Ci , define T emax 、T eminare the maximum and minimum values ​​of the system output torque at the same moment respectively. Then the coupling gain coefficient designed in this paper can be expressed as

[0046]

[0047] like Figure 4 , taking four motors as an example, the electromagnetic torque of the first motor is T e1 , calculate the corresponding coupling gain coefficient K by formula (8) C1 , the corresponding compensation torque is T e_c1 , T e_c1 Input into the torque outer loop of the first motor, and the other three motors are also coupled through the coupling gain coefficient K C1 , the compensation torque is calculated as T e_c2 、T e_c3 、T e_c4 , respectively input into the torque outer loop of the corresponding motor. The calculation process calculates compensation in real time according to the real-time changes of the torque of each motor.

[0048] The above is the designed torque compensation controller. The beneficial effects of the present invention are: the present invention is aimed at the problem that the traditional PI control method in the multi-motor rigid gear transmission system is difficult to effectively solve the torque output imbalance problem caused by mechanical error or disturbance error. The speed deviation coupling control in the multi-motor uncoupled connection structure is applied to the multi-motor rigid connection structure. By integrating the torque deviation information of all motors in the system and selecting the appropriate coupling gain coefficient, the system torque synchronization error is reduced and the torque output fluctuation caused by the mechanical transmission structure is eliminated, making the output smoother and greatly enhancing the safety of the system operation. The results are as follows: Figure 5-Figure 8 This method demonstrates that it can effectively reduce torque synchronization errors and eliminate torque output fluctuations in multi-motor rigid gear transmission systems. Compared with traditional PI control methods, this method has better control performance and provides a reference for more efficient and safer industry indicators in the multi-motor control industry.

Claims

1. A torque balance control method for a multi-motor rigid gear transmission system is provided. The multi-motor rigid gear transmission system includes multiple motors connected by a gear structure or coaxially connected. The multiple motors operate synchronously and their output torques are coupled to each other. The torque balance control method includes the following steps: Step 1: Calculate the electromagnetic torque of each motor in real time; Step 2: Perform real-time compensation on each motor, subtract the electromagnetic torque of each motor from the electromagnetic torque of other motors, sum them up and then multiply them by the coupling gain coefficient to obtain the compensation torque of the motor, and input the compensation torque of the motor into the torque outer loop of the motor; characterized in that, The coupling gain coefficient is Among them, T emax 、T emin are the maximum and minimum values ​​of the electromagnetic torque output of all motors in the multi-motor rigid gear transmission system at the current moment, T ei is the electromagnetic torque of the i-th motor to be compensated.

2. The torque balance control method for a multi-motor rigid gear transmission system according to claim 1, characterized in that: The calculation method of the electromagnetic torque of the motor is T e =n p ψi st L m / L r Among them, T e is the electromagnetic torque of the motor; n p is the number of motor pole pairs, ψ is the motor flux, L m is the excitation self-inductance, L r is the magnetizing inductance, i st is the stator current of the asynchronous motor t-axis in the two-phase stationary coordinate system.

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