Dual-motor synchronous control method and system for driving dual motors by single inverter

Abstract

The application provides a double-motor synchronous control method and a system for driving double motors by a single inverter, and relates to the field of motor control. In the double-motor synchronous control method, on one hand, a nonlinear extended state observer is introduced from the motor to realize real-time active evaluation of system lumped disturbance estimation value and real-time offset of load mutation. Compared with a traditional PI observer, the dynamic convergence speed under the load imbalance condition is significantly improved, and the problem of step loss and oscillation of the slave motor is solved. On the other hand, the problem of singularity divergence of the analytical expression near the synchronization point of the master motor and the slave motor is solved by a continuous segmented injection function, the continuity of the injection current command at the switching boundary of the injection function is ensured, and the synchronous and smooth operation of the master motor and the slave motor is realized.

Description

Technical Field

[0001] This invention relates to the field of motor control technology, and in particular to a method for synchronous control of dual motors and a system for driving dual motors with a single inverter. Background Technology

[0002] As a compact and cost-effective multi-motor drive solution, the dual-parallel permanent magnet synchronous motor system driven by a single inverter is widely used in industrial transmission, fans, and pumps. However, this system is a typical strongly coupled and underdriven system, where the two motors are forced to share the same voltage vector, posing a significant challenge to achieving high-performance coordinated synchronization control. To maintain stable synchronization between the two motors, existing high-performance control solutions generally rely on installing mechanical speed / position sensors (such as photoelectric encoders) on each motor. This approach not only significantly offsets the cost advantages of the single-inverter architecture and increases wiring complexity, but also makes the mechanical sensors highly susceptible to failure in harsh environments such as high temperatures and vibrations, severely reducing system reliability.

[0003] To break free from the constraints of sensors, sensorless control has gradually become a research hotspot. However, sensorless control schemes have the following significant drawbacks: ① High requirements for hardware sampling and poor disturbance rejection; traditional sensorless algorithms usually still require a complete phase current sensor for each motor. Under sensorless control, the slave motor is in a "semi-open-loop" following state, which is highly susceptible to load disturbances, parameter uncertainties, and coupling effects. Existing conventional observers lack the ability to adaptively adjust to changes in system state, and are prone to severe observation lag when a sudden load is applied, leading to a sharp decline in dynamic performance or even loss of synchronization and shutdown; ② Control singularity and voltage saturation risk; the d-axis current injection has a mathematical singularity near the equilibrium point where the position difference between the two motors is close to zero. When the system operates close to the singularity, the control command is prone to divergence, leading to system instability and thus causing synchronization imbalance between the master and slave motors. Therefore, how to achieve synchronous control of dual motors is an urgent problem to be solved. Summary of the Invention

[0004] In view of this, the purpose of the present invention is to provide a dual-motor synchronous control method and a system for driving dual motors with a single inverter, so as to alleviate the above-mentioned technical problems.

[0005] In a first aspect, embodiments of the present invention provide a dual-motor synchronous control method applied to a system where a single inverter drives dual motors; wherein the dual motors include a master motor and a slave motor connected in parallel; the method includes: determining a target position error based on the three-phase currents of the master motor and the slave motor; wherein the target position error is used to characterize the actual physical position error between the master motor and the slave motor; determining the observed relative speed difference, the estimated system lumped disturbance, and the relative position error based on the target position error and a nonlinear extended state observer; determining the composite torque current compensation value of the slave motor based on the observed relative speed difference and the estimated system lumped disturbance; determining the upper limit of the injected current of the master motor, and determining a linearization switching threshold based on the upper limit of the injected current and the composite torque current compensation value; determining a target injected current based on a continuously segmented injection function, and based on the upper limit of the injected current, the composite torque current compensation value, the relative position error, and the linearization switching threshold; and driving the inverter according to the target injected current to enable the master motor and the slave motor to operate synchronously.

[0006] The aforementioned dual-motor synchronous control method, on the one hand, by introducing a nonlinear extended state observer from the slave motor, achieves real-time active evaluation of the system's lumped disturbance estimate and real-time offsetting of load mutations. Compared with the traditional PI observer, it significantly improves the dynamic convergence speed under unbalanced load conditions and solves the problem of slave motor easily losing synchronization and oscillation. On the other hand, by using a continuously segmented injection function, it solves the analytical singularity divergence problem near the synchronization point of the master and slave motors, ensuring the continuity of the injected current command at the switching boundary of the injection function, thereby achieving synchronous and stable operation of the master and slave motors.

[0007] Preferably, the above-mentioned injection function includes a first injection function and a second injection function; based on the continuously segmented injection function, and determining the target injection current according to the upper limit of the injection current, the composite torque current compensation value, the relative position error and the linearization switching threshold, the method includes: if the absolute value of the relative position error is greater than the linearization switching threshold, determining the target injection current according to the first injection function, the composite torque current compensation value and the relative position error.

[0008] Preferably, the above-mentioned injection function based on continuous segmentation, and the determination of the target injection current according to the upper limit of the injection current, the composite torque current compensation value, the relative position error and the linearization switching threshold, includes: if the absolute value of the relative position error is less than or equal to the linearization switching threshold, the target injection current is determined according to the second injection function, the upper limit of the injection current, the composite torque current compensation value, the relative position error and the linearization switching threshold.

[0009] Preferably, determining the composite torque current compensation value of the slave motor based on the observed relative speed difference and the estimated system lumped disturbance includes: setting the target relative speed difference between the master motor and the slave motor to 0, and inputting the observed relative speed difference to the PI controller so that the PI controller outputs an initial torque current compensation value; and determining the composite torque current compensation value based on the initial torque current compensation value and the estimated system lumped disturbance.

[0010] Preferably, determining the target position error based on the three-phase currents of the main motor and the slave motor includes: determining the position error of the main motor based on the three-phase current and motor parameters of the main motor, and determining the estimated speed and estimated position of the main motor based on the position error; wherein, the position error is used to characterize the error between the actual coordinate system of the main motor and the preset estimated coordinate system, and the motor parameters include stator resistance and stator inductance; determining the position observation deviation based on the three-phase current and motor parameters of the slave motor, and determining the target position error based on the position observation deviation, the estimated position, and the position error.

[0011] Preferably, the determination of the position error of the main motor based on the three-phase current and motor parameters of the main motor includes: determining the main current component of the main motor in the estimated coordinate system based on the three-phase current of the main motor; determining the main back electromotive force component of the main motor in the estimated coordinate system based on the main current component and motor parameters; and determining the position error of the main motor based on the main back electromotive force component.

[0012] Preferably, the determination of position observation deviation based on the three-phase current and motor parameters of the slave motor includes: determining the slave current component of the slave motor in the estimated coordinate system based on the three-phase current of the slave motor; determining the slave back electromotive force component of the slave motor in the estimated coordinate system based on the slave current component and motor parameters; and determining the position observation deviation based on the slave back electromotive force component; wherein, the position observation deviation is used to characterize the relative position error between the actual position of the slave motor and the estimated position of the master motor.

[0013] Preferably, before determining the target position error based on the three-phase currents of the main motor and the slave motor, the method further includes: acquiring the two-phase current of the main motor and determining the third-phase current of the main motor based on the two-phase current; reconstructing the total three-phase current based on the bus single-resistance reconstruction technology, and determining the three-phase current of the slave motor based on the total three-phase current and the three-phase current of the main motor.

[0014] Secondly, embodiments of the present invention also provide a system for driving dual motors with a single inverter, comprising: a controller, an inverter, and dual motors; wherein the dual motors include a master motor and a slave motor connected in parallel; the controller is used to drive the inverter using the method described in the first aspect above, so that the master motor and the slave motor operate synchronously.

[0015] Thirdly, embodiments of the present invention also provide a computer-readable storage medium storing a computer program, which, when executed by a processor, performs the steps of the method described in the first aspect.

[0016] The embodiments of the present invention bring the following beneficial effects: This invention provides a dual-motor synchronous control method and a system for driving dual motors with a single inverter. The method determines the target position error based on the three-phase currents of the master and slave motors, and determines the observed relative speed difference, the estimated system lumped disturbance, and the relative position error based on the target position error and a nonlinear extended state observer. It then determines the composite torque current compensation value for the slave motor based on the observed relative speed difference and the estimated system lumped disturbance. Finally, it determines the upper limit of the injected current for the master motor and determines the linearization switching threshold based on the upper limit of the injected current and the composite torque current compensation value. Based on a continuously segmented injection function, it determines the target injected current based on the upper limit of the injected current, the composite torque current compensation value, the relative position error, and the linearization switching threshold. Finally, it drives the inverter according to the target injected current to synchronize the master and slave motors. The above control method, on the one hand, by introducing a nonlinear extended state observer from the motor, realizes real-time active evaluation of the system's lumped disturbance estimate and real-time offsetting of load mutations. Compared with the traditional PI observer, it significantly improves the dynamic convergence speed under unbalanced load conditions and solves the problem of the slave motor easily losing synchronization and oscillating. On the other hand, by using a continuously segmented injection function, it solves the analytical singularity divergence problem near the synchronization point of the master motor and the slave motor, ensuring the continuity of the injected current command at the switching boundary of the injection function, thereby realizing the synchronous and stable operation of the master motor and the slave motor.

[0017] Other features and advantages of the invention will be set forth in the following description, and will be apparent in part from the description, or may be learned by practicing the invention. The objects and other advantages of the invention are realized and obtained through the structures particularly pointed out in the description and the drawings.

[0018] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, preferred embodiments are described below in detail with reference to the accompanying drawings. Attached Figure Description

[0019] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0020] Figure 1A flowchart of a dual-motor synchronous control method provided in an embodiment of the present invention; Figure 2 A schematic diagram of the spatial relationship between the master-slave motor and the observer coordinate system is provided for an embodiment of the present invention; Figure 3 A schematic diagram illustrating the sensitivity of the main motor's d-axis current injection to the torque of two motors, provided as an embodiment of the present invention; Figure 4 This invention provides a schematic diagram of injection function curves under two operating conditions as an embodiment of the present invention. Figure 5 This is a schematic diagram of the simulation results of speed control for dual parallel motors provided in an embodiment of the present invention; Figure 6 A schematic diagram of the current waveform experimental results of two parallel motors provided in an embodiment of the present invention; Figure 7 A flowchart of another dual-motor synchronous control method provided in an embodiment of the present invention. Detailed Implementation

[0021] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, 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.

[0022] To address the problem of synchronization imbalance in dual-motor control schemes without speed sensors, this invention provides a dual-motor synchronization control method and a system for driving dual motors with a single inverter. On one hand, by introducing a nonlinear extended state observer from the slave motor, it achieves real-time active evaluation of the system's lumped disturbance estimate and real-time compensation of load mutations. Compared with traditional PI observers, this significantly improves the dynamic convergence speed under unbalanced load conditions and solves the problems of slave motor loss of synchronization and oscillation. On the other hand, by using a continuously segmented injection function, it solves the analytical singularity divergence problem near the synchronization point of the master and slave motors, ensuring the continuity of the injected current command at the switching boundary of the injection function, thereby achieving synchronous and stable operation of the master and slave motors.

[0023] To facilitate understanding of this embodiment, the embodiments of the present invention will be described in detail below.

[0024] This invention provides a dual-motor synchronous control method applied to a system where a single inverter drives two motors. The dual motors include a master motor and a slave motor connected in parallel. In practical applications, for dual motors, one can be arbitrarily designated as the master motor and the other as the slave motor. Master and slave motors of the same model have the same motor parameters (also known as calibration parameters), which include, but are not limited to, stator resistance and stator inductance, and can be set according to actual conditions. Specifically, the structure of a system where a single inverter drives two motors can be referenced from existing technologies, and will not be described in detail here.

[0025] Based on the above system of a single inverter driving two motors, such as Figure 1 As shown, the dual-motor synchronous control method provided in this embodiment of the invention includes the following steps: Step S102: Determine the target position error based on the three-phase currents of the main motor and the slave motor.

[0026] The target position error is used to characterize the actual physical position error between the master motor and the slave motor, that is, the difference between the actual positions of the master motor and the slave motor. In practical applications, if a single inverter driving a dual-motor system uses position encoders, that is, mechanical position sensors (such as photoelectric encoders) are installed on the master motor and the slave motor respectively, the positions of the master motor and the slave motor can be directly obtained through the mechanical position sensors, and the target position error can be determined based on the positions of the master motor and the slave motor. However, this method not only significantly offsets the cost advantage brought by the single inverter architecture and increases the wiring complexity, but also makes the mechanical sensors prone to failure in harsh environments such as high temperature and vibration, which seriously reduces the reliability of the system.

[0027] Based on this, in order to significantly reduce sensor costs and wiring complexity and completely eliminate the reliance on mechanical sensors, the system of a single inverter driving two motors in this embodiment of the invention does not use mechanical sensors or speed sensors. Instead, it determines the target position error based on the three-phase current of the master motor and the slave motor, thereby significantly improving the system's environmental adaptability.

[0028] Step S104: Based on the target position error and the nonlinear extended state observer, determine the observed relative rotational speed difference, the estimated value of the system lumped disturbance, and the relative position error.

[0029] Step S106: Determine the composite torque current compensation value of the motor based on the observed relative speed difference and the estimated value of the system lumped disturbance.

[0030] Step S108: Determine the upper limit of the injection current of the main motor, and determine the linearization switching threshold based on the upper limit of the injection current and the composite torque current compensation value.

[0031] Step S110: Based on the continuous segmented injection function, the target injection current is determined according to the upper limit of the injection current, the composite torque current compensation value, the relative position error, and the linearization switching threshold.

[0032] Step S112: Drive the inverter according to the target injected current to make the main motor and the slave motor run synchronously.

[0033] The dual-motor synchronous control method provided in this invention, on the one hand, by introducing a nonlinear extended state observer from the slave motor, realizes real-time active evaluation of the system's lumped disturbance estimate and real-time offsetting of load mutations. Compared with the traditional PI observer, it significantly improves the dynamic convergence speed under unbalanced load conditions and solves the problem of slave motor easily losing synchronization and oscillation. On the other hand, by using a continuously segmented injection function, it solves the analytical singularity divergence problem near the synchronization point of the master motor and slave motor, ensuring the continuity of the injected current command at the switching boundary of the injection function, thereby realizing the synchronous and stable operation of the master motor and slave motor.

[0034] In one embodiment, before determining the target position error based on the three-phase currents of the main motor and the slave motor, the method further includes: acquiring the two-phase current of the main motor and determining the third-phase current of the main motor based on the two-phase current; reconstructing the total three-phase current based on the bus single-resistance reconstruction technique, and determining the three-phase current of the slave motor based on the total three-phase current and the three-phase current of the main motor.

[0035] In practical applications, the three-phase current of a motor is typically acquired using three current transformers. For example, the three-phase current of the main motor is acquired using three current transformers, and the three-phase current of the slave motor is acquired using another three current transformers. While this current sampling method can acquire the three-phase current of both the main and slave motors, it increases the hardware cost of sampling. Therefore, this invention employs a simplified sampling architecture of "single busbar resistor + dual current transformers," coupled with a self-decoupling algorithm, to achieve complete observation of the six-phase current of both motors. This not only significantly reduces system hardware costs and wiring complexity but also significantly improves the system's environmental adaptability.

[0036] Specifically, the system hardware uses only a single bus resistor and two current transformers for the main motor. For ease of explanation, this section uses the current transformers for phases A and B of the main motor as an example. The currents of phases A and B of the main motor are sampled and obtained using these current transformers. and Based on the currents in phases A and B, Kirchhoff's current law is used to determine the third-phase current of the main motor, i.e., phase C. It can be solved as follows: (1) in, tThis represents any time interval, in seconds (s). , and This represents the instantaneous value of the three-phase current of the main motor, all in amperes (A).

[0037] Furthermore, based on the bus single-resistor reconstruction technology, the total three-phase current is reconstructed. , , Based on the total three-phase current and the three-phase current of the main motor, the three-phase current of the slave motor is determined. Specifically, the instantaneous value of the three-phase current of the slave motor can be expressed as: (2) Therefore, the three-phase current of the main motor can be quickly determined using a simplified sampling architecture of "single busbar resistor + dual current transformer". , and ) and the three-phase current from the motor ( , and In particular, in the above formula (2), the units of the total three-phase current, the three-phase current of the main motor and the three-phase current of the slave motor are all A.

[0038] In one embodiment, in step S102, determining the target position error based on the three-phase currents of the main motor and the slave motor includes: (A1) determining the position error of the main motor based on the three-phase currents and motor parameters of the main motor, and determining the estimated speed and estimated position of the main motor based on the position error; wherein, the position error is used to characterize the error between the actual coordinate system of the main motor and the preset estimated coordinate system, and the motor parameters include stator resistance and stator inductance; (A2) determining the position observation deviation based on the three-phase currents and motor parameters of the slave motor, and determining the target position error based on the position observation deviation, the estimated position, and the position error.

[0039] In (A1), the position error of the main motor is determined based on the three-phase current and motor parameters of the main motor, including: determining the main current component of the main motor in the estimated coordinate system based on the three-phase current of the main motor; determining the main back electromotive force component of the main motor in the estimated coordinate system based on the main current component and motor parameters; and determining the position error of the main motor based on the main back electromotive force component.

[0040] Specifically, for the three-phase current of the main motor , and Using the estimated position output by the observer at the previous time step The transformation is performed to obtain the main motor in the estimated coordinate system. The main current component and Among them, such as Figure 2 As shown, d 1 axis and q One axis forms the real physical dq coordinate system of the main motor (i.e., the actual rotor coordinate system of the main motor). d 2-axis and q The two axes are composed of the actual physical dq coordinate system of the motor (i.e., the actual rotor coordinate system of the motor). shaft and Axis composition estimation coordinate system (i.e., the coordinate system of the main motor observer); in addition, shaft and The axes form a stationary coordinate system.

[0041] Therefore, based on the three-phase current of the main motor , and By performing a Clark transformation, the two-phase currents in the stationary coordinate system can be obtained, and the estimated position output from the observer at the previous moment can be used. By performing a Park transformation on the two-phase currents in the stationary coordinate system, the position of the main motor in the estimated coordinate system can be obtained. The main current component and Specifically, the superscript here indicates that the physical quantity is projected onto the estimated coordinate system, for example... Indicates the current from the motor In the estimated coordinate system of the main motor of Projection value on the axis.

[0042] Furthermore, based on the aforementioned main current components and motor parameters, the position of the main motor in the estimated coordinate system can be determined. The main back electromotive force component; wherein, the main back electromotive force component includes the main motor in the estimated coordinate system. of The main back electromotive force component on the axis and the main motor in the estimated coordinate system of The main back electromotive force component on the axis The specific formula for determining the main back electromotive force component is as follows: (3) in, This indicates the output of the main motor current loop at the current moment. d Shaft voltage command, unit: V. This indicates the output of the main motor current loop at the current moment. q Shaft voltage command, unit: V. This represents the stator resistance, measured in Ω. This represents stator inductance, measured in ohms (H). This represents the estimated electrical angular velocity of the main motor output by the observer at the previous moment, in rad / s. This indicates that the main motor is in the estimated coordinate system. of The main back electromotive force component on the axis, in V. This indicates that the main motor is in the estimated coordinate system. of The main back electromotive force component on the axis, in V; This indicates that the main motor is in the estimated coordinate system. of The main current component on the shaft, in amperes (A). This indicates that the main motor is in the estimated coordinate system. of The main current component on the shaft, in amperes (A).

[0043] Assuming the actual position of the main motor is If the unit is rad, then the position error of the main motor is defined as... The unit is rad. The true extended back EMF vector of the main motor. Constantly located in its real physical dq coordinate system q On axis 1, its amplitude is Project it onto the estimated coordinate system. We can obtain: (4) in, This represents the actual electrical angular velocity of the main motor, expressed in rad / s. This represents the flux linkage of a permanent magnet, measured in Wb. Notably, the unit rad is treated as dimensionless.

[0044] Extract the position error signal using the arctangent function. for: (5) Therefore, according to and The position error of the main motor can then be determined. Right now (Unit: rad), such as Figure 2 As shown, position error That is, the actual coordinate system of the main motor (i.e., the real physical dq coordinate system). d 1 axis and preset estimated coordinate system of Errors between axes. Then, The input is given to the PI controller, and the output of the PI controller is the estimated speed of the main motor at the current moment. After integration, the estimated position of the main motor at the current moment is obtained. The specific calculation formula is as follows: (6) in, K p and K i For the proportional and integral coefficients of the PI controller, 1 / S This represents the time-domain integral operator. It should be noted that... K p The unit is s -1 , K i The unit is s -2 , S Denotes the differential operator, with units of s. -1 .

[0045] Therefore, this closed-loop process forces So as to estimate the coordinate system Lock the actual rotor position of the main motor.

[0046] Further, in (A2), the position observation deviation is determined based on the three-phase current of the slave motor and the motor parameters, including: determining the slave current component of the slave motor in the estimated coordinate system based on the three-phase current of the slave motor; determining the slave back electromotive force component of the slave motor in the estimated coordinate system based on the slave current component and the motor parameters, and determining the position observation deviation based on the slave back electromotive force component; wherein, the position observation deviation is used to characterize the relative position error between the actual position of the slave motor and the estimated position of the master motor.

[0047] Specifically, firstly, the three-phase current of the motor will be... , and Estimated coordinate system projected onto the main motor Below, we obtain the coordinates of the motor in the estimated coordinate system. From the current component and The specific process for determining the slave current component can be referred to the above-described process for determining the main current component, and will not be elaborated further in this embodiment of the invention. Then, the slave back electromotive force component of the motor in the estimated coordinate system is determined based on the slave current component and the motor parameters. The formula for determining the slave back electromotive force component is as follows: (7) in, This indicates that the motor is in the estimated coordinate system of The component of back electromotive force on the axis, in V. This indicates that the motor is in the estimated coordinate system of The component of back electromotive force on the axis, in V. This indicates the output of the main motor current loop at the current moment. d Shaft voltage command, unit: V. This indicates the output of the main motor current loop at the current moment. q Shaft voltage command, unit: V. This represents the stator resistance, measured in Ω. This represents stator inductance, measured in ohms (H). This represents the estimated electrical angular velocity of the main motor output by the observer at the previous moment, in rad / s. This indicates that the motor is in the estimated coordinate system of The current component on the shaft, in amperes (A). This indicates that the motor is in the estimated coordinate system of The component of current along the axis, in amperes (A).

[0048] After the back EMF component is determined, since the true back EMF vector of the motor is located at its true... q On axis 2, it is The projection on the screen actually includes the actual position of the motor. Estimated position of the main motor The angle between them. For example... Figure 2 As shown, the actual motor d Estimated coordinate system of 2 axes and main motor of The angle between axes is defined as the position observation deviation. , is used to characterize the relative position error between the actual position of the slave motor and the estimated position of the master motor.

[0049] Among them, position observation deviation Based on the back electromotive force component, the specific calculation expression is as follows: (8) in, This can be understood as the original relative position error directly analyzed from the back electromotive force component, with units of rad. The actual position of the motor is given in rad. The estimated position of the main motor at the current moment, in rad.

[0050] Because the position error of the main motor is Then, the target position error is determined based on the position observation deviation, estimated position, and position error. Among them, the target position error The calculation formula is as follows: (9) Therefore, for target position error (Unit: rad) The position error of the main motor is precisely incorporated for feedforward compensation, that is, the position error output by the main motor observer is used. The position observation deviation derived from the back electromotive force component Real-time deduction compensation is performed to pre-determine the true physical position difference (i.e., target position error) between the master motor and slave motor during the dynamic fluctuations of the master motor's observer. Furthermore, it can determine the actual target position error between the master motor and the slave motor without using mechanical position sensors to detect their actual positions, thus further ensuring the synchronous and stable operation of the master motor and the slave motor.

[0051] Specifically, disregarding hardware costs, and using mechanical position sensors to detect the actual position of the main motor... and from the actual position of the motor According to and It can also quickly determine the target position error. .

[0052] In one implementation, in step S104, smooth state extraction and disturbance cancellation are achieved based on a Nonlinear Extended State Observer (NLESO). Specifically, according to Newton's laws of motion, the difference in the mechanical dynamics equations of the two motors operating in parallel can be expressed as the following relative motion equations: (10) in, Indicates relative position error The second derivative with respect to time, in rad / s 2 , Indicates relative position error The first derivative with respect to time, in rad / s. This represents the number of pole pairs of an electric motor; it is dimensionless. This represents the equivalent moment of inertia of the two motors, expressed in units of... , This represents the mechanical friction damping coefficient of the system, with units of 1000 kJ / m². , This represents the electromagnetic torque of the main motor, in units of... , This represents the electromagnetic torque of the motor, measured in units of... , This represents the external mechanical load torque of the main motor, in units of... , This represents the torque from the external mechanical load on the motor, measured in units of... Specifically, rad / s 2 equals 1 / s 2 .

[0053] In actual operation, the difference in external mechanical load torque It is characterized by suddenness and unpredictability, and the equivalent rotational inertia of the dual motors is also present. The mechanical friction damping coefficient of the system There are also parameter perturbations, as well as unavoidable inconsistencies in motor parameters between the master and slave motors during actual operation (such as thermal drift, manufacturing errors, etc.). For ease of explanation, these unknown dynamics and nonlinear frictions that are difficult to model precisely are packaged together and defined as the system lumped disturbance. f Specific system lumped disturbances f The expression is as follows: (11) in, This represents the difference in external mechanical load torque between the master motor and the slave motor, expressed in units of... , This represents the high-frequency component of the electromagnetic torque of the main motor that was not accurately modeled, in units of... , This represents the high-frequency component of the electromagnetic torque from an inaccurately modeled motor, in units of... t represents time, in seconds (s). The unit is rad / s 2 .

[0054] Furthermore, the active input quantity of the system is defined as... The control gain constant is The physical derivation value is The unit is In order to actively infer unknown system lumped disturbances through observers. f ,Will f It expands to become the third state variable of the system.

[0055] Specifically, set the system state variables: (here That is, the aforementioned target position error (unit: rad) (Relative electric speed difference, in rad / s) (System lumped disturbance, in rad / s) 2 Assume the lumped disturbance of the system has a bounded derivative. ,here The lumped disturbance of the system changes over time. In real physical systems, this rate of change is bounded. In the embodiments of this invention, when constructing the observer, it is not necessary to consider... With direct measurement or precise knowledge, the observer can dynamically track and estimate the system's lumped disturbance variable simply by relying on the output error feedback. Therefore, the relative motion system is transformed into an extended state-space model: (12) in, This represents the control gain constant. This represents the known current difference component generated by the subsequent injection system, in amperes (A). This represents the rate of change of the system's lumped disturbance over time, expressed in rad / s. 3 .

[0056] For the above extended state-space model, in order to filter out To reduce noise and achieve real-time estimation of relative rotational speed and system lumped disturbance, the third-order NLESO expression constructed in this embodiment of the invention is as follows: (13) in, , and The observers' views of the system's true state are respectively , and Real-time estimates, in rad, rad / s and rad / s respectively. 2 , This represents the position tracking error of the observer, measured in rad. , and This represents the observer error feedback gain. If rad is treated as dimensionless, the units are s. -1 s -2 and s -3 , This represents the control gain constant, whose physical derivation value is... , This represents the number of pole pairs of an electric motor; it is dimensionless. This represents the flux linkage of a permanent magnet, measured in Wb. Represents the equivalent moment of inertia, in units of 1. ; This represents a nonlinear power function, with units of rad. and Represents a nonlinear factor, dimensionless. This represents the width threshold of the linear interval, in rad.

[0057] For the above nonlinear power function Its analytical expression is defined as: (14) in, This represents the general error independent variable, as mentioned above. The unit is rad; This represents the nonlinear factor, with a value range of [value range missing]. Dimensionless, used to adjust the nonlinearity of error feedback; This is a dimensionless function representing the sign of the extracted error direction. Specifically, if the control implementation first... and After angle normalization, Dimensionless. And, The dimensions are determined by the observer error feedback gain ( and )absorb.

[0058] Therefore, this invention creates a "master-slave heterogeneous observer" architecture. The master motor establishes a steady-state reference, and the slave motor's self-disturbance rejection relative motion observer uses a third-order nonlinear extended state observer to directly observe the "relative quantity" and establishes a mathematical model with the target position error as the system state and external disturbances as the extended state. At the same time, a nonlinear power function is used to provide nonlinear feedback on the observation error to achieve the disturbance rejection tracking characteristics of "large error, small gain; small error, large gain". Thus, the third-order nonlinear extended state observer actively estimates the lumped disturbance of the system and cancels load mutations and parameter perturbations in real time. Compared with the traditional PI observer, it significantly improves the dynamic convergence speed under unbalanced load conditions and solves the problem of slave motors easily losing steps and oscillating. Even if there is an inconsistency in motor parameters within a reasonable range (such as 10% parameter difference), it can still ensure that the master motor and slave motor operate synchronously and smoothly.

[0059] In one embodiment, in step S106, determining the composite torque current compensation value of the slave motor based on the observed relative speed difference and the system lumped disturbance estimate includes: setting the target relative speed difference between the master motor and the slave motor to 0, and inputting the observed relative speed difference to the PI regulator so that the PI regulator outputs an initial torque current compensation value; and determining the composite torque current compensation value based on the initial torque current compensation value and the system lumped disturbance estimate.

[0060] Specifically, with the target relative speed difference between the master motor and the slave motor set to 0 as a given value, the observed relative speed difference output by the third-order nonlinear extended state observer in step S104 is used. (Right now As a feedback quantity, it is input to the PI regulator of the relative speed of the motor, at which point the PI regulator outputs the initial torque current compensation value. : (15) in, This represents the proportional gain from the motor's relative speed loop, in units of... , This represents the integral gain from the relative speed loop of the motor, expressed in A / rad.

[0061] Furthermore, in order to eliminate the impact of external load mutations on synchronization performance, the system lumped disturbance estimate output by the third-order nonlinear extended state observer in step S104 above is used. (Right now After physical dimension conversion, feedforward compensation is performed. The final compensation is based on the combined torque and current of the motor. The calculation formula is as follows: (16) Therefore, the system lumped disturbance estimate output by the third-order nonlinear extended state observer in step S104 above is used. (Right now By controlling the gain constant After the transformation, the feedforward injection is sent to the output of the relative speed regulator of the slave motor. This feedforward channel cancels the difference in external load torque between the master motor and the slave motor at the underlying dynamic level, which significantly improves the dynamic convergence speed under unbalanced load conditions, solves the problem of the slave motor being prone to step loss and oscillation, and further ensures the synchronous and stable operation of the master motor and the slave motor.

[0062] In one implementation, in step S108, a dynamic upper limit for the injected current is calculated based on the inverter voltage margin. Specifically, firstly, based on the measured value of the DC bus voltage, the maximum fundamental voltage amplitude that the inverter can output without entering the overmodulation region is calculated. The calculation formula is as follows: (17) in, This represents the measured value of the DC bus voltage, in volts (V). It represents the voltage utilization coefficient (usually taken as less than 0.9 to allow for dead zone compensation and control margin), and is dimensionless.

[0063] Then, since the master motor and slave motor are connected in parallel, their stator terminal voltage vectors are consistent. The q-axis voltage command output from the master motor current loop is used. Calculate the current voltage margin limit that can be allocated to the d-axis. The calculation formula is as follows: (18) Finally, based on the d-axis voltage equation of the permanent magnet synchronous motor ;in, Indicates stator resistance. L q = L s Indicates stator inductance, i d and i q express d shaft and q shaft current, This represents the electric angular velocity of the motor. In the estimated coordinate system of the main motor, this is the upper limit of the dynamic injection current of the main motor to ensure that the system voltage does not saturate. The following constraints must be met: (19) in, This represents the system's average q-axis current, expressed in amperes (A). It directly converts the total three-phase current of the system ( The total q-axis current projection obtained after coordinate transformation is expressed in A. This represents the stator resistance, measured in Ω. This represents stator inductance, measured in ohms (H). This represents the estimated electrical angular velocity of the main motor at the current moment, in rad / s.

[0064] In practical applications, traditional control schemes often employ fixed limiting, failing to consider the voltage margin contraction of the inverter during high-speed operation, which easily leads to overmodulation and current distortion. Therefore, this invention introduces a dynamic voltage margin evaluation mechanism for dynamic limiting. Specifically, based on the bus voltage and the current q-axis voltage command, the available voltage margin on the d-axis, i.e., the voltage margin limit, is calculated. ; and based on the voltage margin limit value Dynamically lower the upper limit of the dynamic injection current of the main motor d-axis To ensure that the upper limit of the injected current of the main motor is reached. The system adaptively contracts with the speed of the main motor and the bus voltage, thereby ensuring that the voltage requirements of the main control circuit are prioritized in the high-speed range. This effectively prevents current distortion and control failure caused by inverter over-modulation, and further ensures the synchronous and stable operation of the main motor and the slave motor.

[0065] Furthermore, for surface-mounted permanent magnet synchronous motors (SPMSMs), the d-axis and q-axis inductances are equal. At this time, d-axis current is injected into the main motor. It will not generate reluctance torque, that is, it will not change the electromagnetic torque of the main motor itself. However, it will change the electromagnetic torque from the motor. .like Figure 3 As shown, the horizontal axis represents the relative position error between the master motor and the slave motor. When using sensorless control, use (i.e., the output of the third-order nonlinear extended state observer in step S104 above) The coordinates are replaced by the units of radians (rad), and the vertical axis represents the normalized torque sensitivity in N. m / A; Main motor torque sensitivity through It is determined that the motor torque sensitivity is obtained through... Therefore, it can be concluded that when the main motor injects d-axis current... At this time, the electromagnetic torque of the main motor itself will not change. However, it will change the electromagnetic torque from the motor. .

[0066] Furthermore, based on the steady-state voltage equation of the dual motors, a partial derivative (sensitivity) model of the d-axis current of the main motor with respect to the torque of the slave motor is established. The specific expression of the model is as follows: (20) in, This represents the relative position error output by the third-order nonlinear extended state observer in step S104 above, i.e. .

[0067] To generate the required composite torque current compensation value By solving formula (20) in reverse, we can obtain the ideal analytical inverse proportional model for the non-singular region. The expression of this model is as follows: (twenty one) in, This represents the ideal synchronous injection current, expressed in amperes (A). This represents the composite torque current compensation value from the motor, expressed in amperes (A).

[0068] To address the singularity issue in the above formula (21), this embodiment of the invention employs a linearization strategy near the singularity point. The upper limit of the injection current calculated using the above formula (19) is... As a hard limiting condition, the final injected current must meet the following requirements: (twenty two) Substituting this constraint into the non-singular region ideal analytical inverse proportional model of the above formula (21), we can deduce the absolute value of the minimum safe angle that the system can withstand: (twenty three) Therefore, the linearization switching threshold is determined based on the upper limit of the injected current and the composite torque current compensation value. x Here, the threshold for linearization is switched. x The algorithm is used to divide the system into singular and non-singular regions, with the core objective of achieving a balance between control precision and system safety. In the non-singular region (where the error is relatively large), the algorithm pursues control precision, using an ideal analytical model to provide the most accurate synchronous compensation torque. In the singular region (where the error approaches zero), a dynamic threshold is used to activate the linear protection function, actively sacrificing theoretical precision to avoid mathematical divergence of the inverse sinusoidal proportional function near zero.

[0069] Among them, the linearization switching threshold x The calculation formula is as follows: (twenty four) in, This represents the saturation limiting function, used when injection demand is too high or voltage margin is insufficient. When shrinking drastically, the domain of the arcsin function is strictly protected from overflow, and both input and output are dimensionless. x The unit is rad.

[0070] In one implementation, step S110 includes a first injection function and a second injection function; determining the target injection current based on the continuously segmented injection function and according to the upper limit of the injection current, the composite torque current compensation value, the relative position error, and the linearization switching threshold includes: if the absolute value of the relative position error is greater than the linearization switching threshold, determining the target injection current according to the first injection function, the composite torque current compensation value, and the relative position error; if the absolute value of the relative position error is less than or equal to the linearization switching threshold, determining the target injection current according to the second injection function, the upper limit of the injection current, the composite torque current compensation value, the relative position error, and the linearization switching threshold.

[0071] Specifically, the linearization switching threshold calculated based on step S108 above. x This constructs a piecewise injection function (also known as a synchronous injection function) that is continuous and differentiable throughout the entire domain. The expression for the injection function is shown below: (25) in, This represents the target injection current, in amperes (A). The sign function is used to ensure that the polarity of the injected current near the singular point is strictly consistent with the direction of the compensation requirement, and is dimensionless.

[0072] According to formula (25), when the absolute value of the relative position error is greater than the linearization switching threshold, i.e. At that time, according to the first injection function Composite torque current compensation value and relative position error The target injection current can then be determined. When the absolute value of the relative position error is less than or equal to the linearization switching threshold, i.e. At that time, according to the second injection function Upper limit of injection current Composite torque current compensation value Relative position error and linearization switching threshold x Determine the target injection current .

[0073] Therefore, based on the real-time upper limit of the injection current. and composite torque current compensation value Determine the linearization switching threshold x The injection function is adaptively selected based on the linearization switching threshold, while the relative position error output by the third-order nonlinear extended state observer is utilized. Calculate the target injection current together Suppressing the target injection current The jitter problem was addressed by implementing a singularity avoidance strategy for dynamically linearizing the switching threshold through a continuously segmented injection function. This solved the analytical singularity divergence problem near the synchronization point of the master and slave motors, ensuring the continuity of the injected current command at the switching boundary of the injection function, thereby achieving synchronous and stable operation of the master and slave motors.

[0074] In practical applications, to ensure synchronization of the two motors, the master motor must compensate for the torque demand of the slave motor (i.e., the composite torque current compensation). The target injection current is the d-axis current injected into itself. This allows the coupling effect to be used to change the output torque of the motor. For example... Figure 4 As shown, the curves of the continuously segmented injection function, designed to avoid mathematical singularities, are intuitively presented when the system eliminates relative position errors. The horizontal axis represents the relative position error. The vertical axis represents the target injection current injected along the d-axis. Furthermore, the shaded area formed by M1 to M4 is a singularity linear protection zone, while the remaining areas are non-singular regions, and the line between M1 and M3 represents - x The line between M2 and M4 represents + x .

[0075] Based on the direction of the composite torque current compensation, the system can be divided into the following two typical operating conditions: (1) Operating condition A: At this time If the value is greater than 0, the injection function includes the piecewise continuous curves L1, L2, and L3.

[0076] Specifically, when the load on the slave motor suddenly increases, or its speed lags behind that of the main motor, the relative speed regulator will output a positive compensation demand, that is, at this time... If the value is greater than 0, the system is required to provide additional positive pulling torque to assist the slave motor in accelerating and synchronizing.

[0077] In the non-singular region, the relative position error between the two motors is relatively large, and the ideal analytical model is the analytical injection function. Since the molecule is positive, when hour, The calculated value is negative. When it is a negative value, it corresponds to Figure 4 Curve L3 in the fourth quadrant; when hour, If positive, the calculated A positive value corresponds to Figure 4 Curve L1 in the second quadrant.

[0078] Furthermore, in the singularity linear protection zone (i.e., the singularity region), when the relative position error... As the system approaches zero, the reciprocal of the sine function tends towards infinity, which can easily cause the system to diverge. At this point, the algorithm automatically switches to the linear interpolation region. Because... Greater than 0, sign function Substituting into formula (25) yields This is in Figure 4 The curve L2 is represented by a straight line passing through the origin with a negative slope. This line perfectly connects the two boundary points (+). x and- x This ensures the continuity of the injection command for the target injection current and strictly limits the injected target injection current to the dynamic safety upper limit. Within. Specifically, This indicates the upper limit of the injected current. This indicates the lower limit of the injection current.

[0079] (2) Operating condition B: At this time If less than 0, the injection function includes the piecewise continuous curves L4, L5, and L6.

[0080] Specifically, when the load on the slave motor suddenly decreases, or its speed leads that of the main motor, the relative speed regulator will output a negative compensation demand, that is, at this time... If the value is less than 0, the system is required to generate braking torque to suppress the leading tendency of the motor.

[0081] In the non-singular region, due to molecules When it becomes negative, the overall polarity reverses. When, the denominator of the formula It is also negative, and two negatives make a positive, so the calculated result is... A positive value corresponds to Figure 4 Curve L6 in the first quadrant; when When the denominator is positive, the calculated value is... A negative value corresponds to Figure 4 Curve L4 in the third quadrant.

[0082] Furthermore, similarly, in the linear protection zone of singular points, the sign function... Substituting into formula (25) yields This is in Figure 4 The curve L5 is represented by a straight line passing through the origin with a positive slope. This straight line also ensures the smooth transition and correct polarity of the current command injected at the zero point, thereby preventing current oscillation caused by the current command jump in the inverter and further ensuring the synchronous and stable operation of the main motor and the slave motor.

[0083] For example, if the upper motor is a permanent magnet synchronous motor, the simulation results of the speed control of the system with a single inverter driving two parallel permanent magnet synchronous motors are as follows: Figure 5 As shown in the figure, the horizontal axis represents time in seconds, and the vertical axis represents rotational speed in rpm. According to the simulation results, after adopting the dual-motor synchronous control method proposed in this embodiment of the invention, the rotational speeds of the two parallel motors remain consistent, thus achieving synchronous and stable operation of the dual motors and enabling the system to have good control performance.

[0084] In addition, the experimental results of the current waveforms of the two parallel motors are as follows: Figure 6 As shown, the horizontal axis represents time, 4ms / div (i.e., 4ms / division); the vertical axis represents current, 2A / div (2A / division). According to the simulation results, after adopting the dual-motor synchronous control method proposed in this embodiment, the current amplitudes of the two parallel motors are the same, and their phases remain synchronized. This further demonstrates that the two parallel motors can maintain consistent speed operation, thus achieving synchronous and stable operation of the master motor and the slave motor.

[0085] Furthermore, based on the above method embodiments, this invention provides another dual-motor synchronous control method, such as... Figure 7 As shown, the method includes the following steps: Step S702: Sample the bus current and the two-phase current of the main motor, and decouple and separate the three-phase current of the main motor and the three-phase current of the slave motor.

[0086] Step S704: Transform the three-phase current of the main motor to the estimated coordinate system, determine the position error of the main motor, and determine the estimated speed and estimated position of the main motor based on the position error.

[0087] Step S706: Determine the target position error based on the three-phase current of the slave motor and the position error of the master motor.

[0088] Step S708: Input the target position error into the third-order nonlinear extended state observer to obtain the observed relative rotational speed difference. System lumped disturbance estimate and relative position error .

[0089] Step S710: Determine the composite torque current compensation value from the motor based on the observed relative speed difference and the estimated system lumped disturbance. .

[0090] Step S712: Determine the upper limit of the injection current of the main motor. and linearization switching threshold x .

[0091] Step S714: Determine whether the absolute value of the relative position error is greater than the linearization switching threshold. If yes, proceed to step S716; otherwise, proceed to step S718.

[0092] Step S716, .

[0093] Step S718, .

[0094] Step S720, will The voltage is superimposed onto the main motor control loop to generate a space voltage vector drive inverter, so that the main motor and the slave motor can operate synchronously.

[0095] Therefore, the dual-motor synchronous control method provided in this embodiment of the invention achieves synchronous control of dual motors through a simplified hardware sampling architecture and an active disturbance rejection observation strategy based on a nonlinear extended state observer. It should be noted that the specific processes of each of the above steps can be referred to the foregoing embodiments, and will not be described in detail here.

[0096] Based on the above method embodiments, this invention also provides a system for driving dual motors with a single inverter, including: a controller, an inverter, and dual motors; wherein, the dual motors include a master motor and a slave motor connected in parallel; the controller is used to drive the inverter using the above method embodiments so that the master motor and the slave motor operate synchronously.

[0097] The system for driving two motors with a single inverter provided in this embodiment of the invention has the same technical features as the dual-motor synchronous control method provided in the above embodiment, so it can also solve the same technical problems and achieve the same technical effects.

[0098] This embodiment also provides a machine-readable storage medium storing machine-executable instructions. When the machine-executable instructions are called and executed by the processor, the machine-executable instructions cause the processor to implement the above-described dual-motor synchronous control method.

[0099] The computer program product of the dual-motor synchronous control method and the system of driving dual motors by a single inverter provided in the embodiments of the present invention includes a computer-readable storage medium storing program code. The instructions included in the program code can be used to execute the methods described in the preceding method embodiments. For specific implementation, please refer to the method embodiments, which will not be repeated here.

[0100] Those skilled in the art will clearly understand that, for the sake of convenience and brevity, the specific working process of the system and apparatus described above can be referred to the corresponding process in the foregoing method embodiments, and will not be repeated here.

[0101] Furthermore, in the description of the embodiments of the present invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in the present invention based on the specific circumstances.

[0102] If the aforementioned functions are implemented as software functional units and sold or used as independent products, they can be stored in a processor-executable, non-volatile, computer-readable storage medium. Based on this understanding, the technical solution of this invention, essentially, or the part that contributes to the prior art, or a portion of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute all or part of the steps of the methods described in the various embodiments of this invention. The aforementioned storage medium includes various media capable of storing program code, such as USB flash drives, portable hard drives, read-only memory (ROM), random access memory (RAM), magnetic disks, or optical disks.

[0103] In the description of this invention, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing the invention and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the invention. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0104] Finally, it should be noted that the above-described embodiments are merely specific implementations of the present invention, used to illustrate the technical solutions of the present invention, and not to limit it. The scope of protection of the present invention is not limited thereto. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that any person skilled in the art can still modify or easily conceive of changes to the technical solutions described in the foregoing embodiments within the technical scope disclosed in the present invention, or make equivalent substitutions for some of the technical features; and these modifications, changes, or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention, and should all be covered within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A dual-motor synchronous control method, applied to a system with a single inverter driving two motors; wherein, The dual motors include a master motor and a slave motor connected in parallel; characterized in that the method includes: The target position error is determined based on the three-phase currents of the master motor and the slave motor; wherein, the target position error is used to characterize the actual physical position error between the master motor and the slave motor; Based on the target position error and the nonlinear extended state observer, the observed relative rotational speed difference, the estimated system lumped disturbance, and the relative position error are determined. Based on the observed relative speed difference and the estimated system lumped disturbance, the composite torque current compensation value of the slave motor is determined; Determine the upper limit of the injected current of the main motor, and determine the linearization switching threshold based on the upper limit of the injected current and the composite torque current compensation value; The injection function is based on continuous segmentation, and the target injection current is determined according to the upper limit of the injection current, the composite torque current compensation value, the relative position error and the linearization switching threshold. The inverter is driven according to the target injection current to make the master motor and the slave motor operate synchronously.

2. The method according to claim 1, characterized in that, The injection function includes a first injection function and a second injection function; The injection function based on continuous segmentation, and the determination of the target injection current according to the upper limit of the injection current, the composite torque current compensation value, the relative position error, and the linearization switching threshold, includes: If the absolute value of the relative position error is greater than the linearization switching threshold, the target injection current is determined based on the first injection function, the composite torque current compensation value, and the relative position error.

3. The method according to claim 2, characterized in that, The injection function based on continuous segmentation, and the determination of the target injection current according to the upper limit of the injection current, the composite torque current compensation value, the relative position error, and the linearization switching threshold, includes: If the absolute value of the relative position error is less than or equal to the linearization switching threshold, the target injection current is determined based on the second injection function, the upper limit of the injection current, the composite torque current compensation value, the relative position error, and the linearization switching threshold.

4. The method according to claim 1, characterized in that, The step of determining the composite torque current compensation value of the slave motor based on the observed relative speed difference and the estimated system lumped disturbance includes: The target relative speed difference between the master motor and the slave motor is set to 0, and the observed relative speed difference is input to the PI controller so that the PI controller outputs the initial torque current compensation value. The composite torque current compensation value is determined based on the initial torque current compensation value and the system lumped disturbance estimate.

5. The method according to claim 1, characterized in that, The step of determining the target position error based on the three-phase currents of the main motor and the slave motor includes: The position error of the main motor is determined based on the three-phase current and motor parameters of the main motor, and the estimated speed and estimated position of the main motor are determined based on the position error; wherein, the position error is used to characterize the error between the actual coordinate system of the main motor and the preset estimated coordinate system, and the motor parameters include stator resistance and stator inductance; The position observation deviation is determined based on the three-phase current of the motor and the motor parameters, and the target position error is determined based on the position observation deviation, the estimated position, and the position error.

6. The method according to claim 5, characterized in that, The step of determining the position error of the main motor based on the three-phase current and motor parameters includes: The main current components of the main motor in the estimated coordinate system are determined based on the three-phase current of the main motor. The main back electromotive force component of the main motor in the estimated coordinate system is determined based on the main current component and the motor parameters, and the position error of the main motor is determined based on the main back electromotive force component.

7. The method according to claim 5, characterized in that, The determination of the position observation deviation based on the three-phase current of the slave motor and the motor parameters includes: The slave current component of the slave motor in the estimated coordinate system is determined based on the three-phase current of the slave motor; The slave back electromotive force component of the slave motor in the estimated coordinate system is determined based on the slave current component and the motor parameters, and the position observation deviation is determined based on the slave back electromotive force component; wherein, the position observation deviation is used to characterize the relative position error between the actual position of the slave motor and the estimated position of the master motor.

8. The method according to claim 1, characterized in that, Before determining the target position error based on the three-phase currents of the main motor and the slave motor, the method further includes: Obtain the two-phase current of the main motor, and determine the third-phase current of the main motor based on the two-phase current; The total three-phase current is reconstructed using the bus single-resistance reconstruction technology, and the three-phase current of the slave motor is determined based on the total three-phase current and the three-phase current of the master motor.

9. A system for driving two motors with a single inverter, characterized in that, include: The system includes a controller, an inverter, and two motors; wherein the two motors consist of a master motor and a slave motor connected in parallel. The controller is configured to drive the inverter using the method described in any one of claims 1-8, so that the main motor and the slave motor operate synchronously.

10. A computer-readable storage medium, characterized in that, The computer-readable storage medium stores a computer program, which, when executed by a processor, performs the steps of the method described in any one of claims 1-8.

Images