An Adaptive Speed ​​Control Method for a Single-Inverter Dual-Parallel Permanent Magnet Synchronous Motor

Abstract

To improve the stability and disturbance rejection performance of a single-inverter dual-parallel motor drive system, this invention proposes an adaptive speed control method for a single-inverter dual-parallel permanent magnet synchronous motor. First, an equivalent mathematical model of the system is established through non-singular coordinate transformation, revealing the coupling relationship between the inverter output voltage and the system control objective. Based on this, a basic control framework for the dual-parallel motor drive system is constructed by combining the design concept of a backstepping controller. Based on the deterministic equivalence principle, an adaptive average speed controller is designed, significantly enhancing the system's robustness to parameter mismatch and load disturbances. An adaptive differential speed controller is designed using the gradient search method, and through online gradient correction of the controller gain, the risk of instability caused by system singularities is effectively avoided.

Description

Technical Field

[0001] This invention relates to the field of permanent magnet motor drive control, and in particular to an adaptive speed control method for a single-inverter dual-parallel permanent magnet synchronous motor. Background Technology

[0002] Dual-parallel motors are widely used in fields such as dual-rotor conveyors, industrial robots, and rail transportation. As a compact and low-cost multi-motor drive solution, dual-parallel permanent magnet synchronous motor systems driven by a single inverter have gradually become a hot topic in multi-motor cooperative control research. However, such systems are susceptible to load disturbances, parameter uncertainties, and inter-motor coupling effects during operation, leading to a decline in system dynamic performance and potentially even stability issues. Especially when facing high-performance control requirements, traditional fixed-parameter control methods often struggle to balance system robustness and dynamic response characteristics, lacking the ability to adaptively adjust to changes in system operating states. Furthermore, when the system approaches a singularity, control performance is prone to deterioration, potentially even leading to system instability. Therefore, it is urgent to design a dual-parallel motor control strategy with adaptive control gain adjustment capabilities to improve the system's stability and disturbance rejection performance under complex operating conditions. Summary of the Invention

[0003] This invention provides an adaptive speed control method for a single-inverter dual-parallel permanent magnet synchronous motor, aiming to improve the anti-disturbance performance of the dual-parallel motor drive system under the influence of uncertainties such as load disturbances and parameter mismatch. Simultaneously, this method addresses the potential instability problem caused by system singularities by performing online gradient correction of the controller gain.

[0004] To achieve the above objectives, the present invention provides an adaptive speed control method for a single-inverter dual-parallel permanent magnet synchronous motor, comprising:

[0005] Step 1: An equivalent mathematical model of the system is established through non-singular coordinate transformation, revealing the coupling relationship between the inverter output voltage and the system control target;

[0006] Step 2: Combining the design concept of the backstepping controller, the basic control framework of the dual parallel motor drive system was constructed.

[0007] Step 3: Based on the deterministic equivalence principle, an adaptive average speed controller was designed to improve the system's robustness to parameter mismatch and load disturbances.

[0008] Step 4: An adaptive differential velocity controller was designed using the gradient search method. By correcting the controller gain online using the gradient, the risk of instability caused by system singularities was effectively avoided.

[0009] Furthermore, the mathematical model of a dual-parallel permanent magnet synchronous motor with identical parameters in the dq rotating coordinate system is as follows:

[0010] ;

[0011] in , and They represent the first Complex vector representation of stator current and stator voltage on the dq axis of a trolley motor; Represents the imaginary unit. , and These represent the inductance, resistance, and moment of inertia of a parallel motor, respectively. and These represent the number of pole pairs and flux linkage of the parallel motor, respectively. , and These represent the mechanical rotor position, mechanical speed, and load torque of the k-th motor, respectively.

[0012] Define the average coordinate system and difference coordinate system for:

[0013] ;

[0014] The mathematical model of motor 1 is transformed by coordinates. The mathematical model of motor 2 is transformed by coordinate transformation. The equivalent mathematical model of the parallel motor is obtained as follows:

[0015] ;

[0016] Subscript and Let the mean variable and the difference variable represent the two variables, respectively, and they are defined as follows:

[0017] ;

[0018] Indicates a variable that is used in a general sense.

[0019] Furthermore, according to the equivalent model of a dual parallel motor (3-3), the inverter output voltage can only control the average current of the dq axis. Based on the design concept of the backstep controller, and combined with the equivalent models (3-2) and (3-5), it can be seen that the current... and It can be used as a virtual control input for the average speed loop and the differential speed loop, respectively.

[0020] Furthermore, the equivalent model (3-2) of the dual parallel motors can be rewritten in the form of state-space equations:

[0021] ;

[0022] in average speed , express , express , express , Represents the average current along the q-axis , Represents the d-axis differential current ;

[0023] Define average velocity tracking error

[0024] ;

[0025] in This represents the average speed reference value;

[0026] according to The average speed tracking error can be obtained. The dynamic equation is:

[0027] ;

[0028] in Represented as , Represented as ;

[0029] Based on the principle of deterministic equivalence in adaptive control, the average speed controller is designed as follows:

[0030] ;

[0031] in express The adaptive term estimate, express The adaptive term estimate is expressed as follows:

[0032] ;

[0033] in and These represent the adaptive term gain.

[0034] Furthermore, the equivalent model of the dual parallel motor (3-5) can be rewritten in the form of state-space equations:

[0035] ;

[0036] in average speed , express , Represents the average current along the d-axis , Represents the q-axis differential current ;

[0037] Define differential velocity tracking error

[0038] ;

[0039] in This represents the average speed reference value;

[0040] according to The differential velocity tracking error can be obtained. The dynamic equation is:

[0041] ;

[0042] in Represented as , Represented as ;

[0043] By combining the gradient search method, the differential velocity controller can be designed as follows:

[0044] ;

[0045] in Indicates the controller gain. and This indicates the gain of the PI controller.

[0046] The above-described solution of the present invention has the following beneficial effects:

[0047] This invention constructs an equivalent mathematical model of a dual-parallel motor system through non-singular coordinate transformation, revealing the coupling relationship between the inverter output voltage and the system control objective. Combining the design concept of a backstepping controller, a basic control framework for the dual-parallel motor drive system is constructed. Based on the deterministic equivalence principle, an adaptive average speed controller is designed, effectively improving the system's robustness to parameter mismatch and load disturbances. Furthermore, by correcting the controller gain through online gradient methods, the instability risk caused by system singularities is effectively avoided. Compared with existing technologies, this invention significantly enhances the system's adaptability to parameter uncertainties and external disturbances, eliminates the system instability risk caused by the coupling effect between the dual parallel motors, and effectively improves the system's control performance.

[0048] Other beneficial effects of the present invention will be described in detail in the following detailed description section. Attached Figure Description

[0049] Figure 1 Block diagram of an adaptive average speed controller for a dual parallel motor drive system;

[0050] Figure 2 Block diagram of an adaptive differential speed controller for a dual parallel motor drive system;

[0051] Figure 3 The overall control block diagram of the adaptive speed control scheme for a single inverter dual parallel permanent magnet synchronous motor;

[0052] Figure 4 The figure shows the simulation results of speed control for dual parallel motors.

[0053] Figure 5 The results show the experimental current waveforms of the dual parallel motors. Detailed Implementation

[0054] To make the technical problems, solutions, and advantages of this invention clearer, a detailed description will be provided below with reference to the accompanying drawings and specific embodiments. Obviously, the described embodiments are only some, not all, of the embodiments of this invention. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0055] like Figure 1 As shown, an embodiment of the present invention provides a block diagram of an adaptive average speed controller for a dual parallel motor drive system. The specific implementation steps are as follows:

[0056] Rewrite the equivalent model of the dual parallel motor in the form of state-space equations:

[0057] (5)

[0058] in average speed , express , express , express , Represents the average current along the q-axis , Represents the d-axis differential current .

[0059] Define average velocity tracking error

[0060] (6)

[0061] in This represents the average speed reference value.

[0062] According to (5), the average velocity tracking error can be obtained. The dynamic equation is:

[0063] (7)

[0064] in Represented as , Represented as .

[0065] Based on the principle of deterministic equivalence in adaptive control, the average speed controller can be designed as follows:

[0066] (8)

[0067] in express The adaptive term estimate, express The adaptive term estimate. Its specific expression is:

[0068] (9)

[0069] in and These represent the adaptive term gain.

[0070] like Figure 2 The diagram shows the block diagram of the adaptive differential speed controller for a dual parallel motor drive system. The specific implementation steps are as follows:

[0071] Rewrite the equivalent model of the dual parallel motor in the form of state-space equations:

[0072] (10)

[0073] in average speed , express , Represents the average current along the d-axis , Represents the q-axis differential current .

[0074] Define differential velocity tracking error

[0075] (11)

[0076] in This represents the average speed reference value.

[0077] According to (10), the differential velocity tracking error can be obtained. The dynamic equation is:

[0078] (12)

[0079] in Represented as , Represented as .

[0080] By combining the gradient search method, the differential velocity controller can be designed as follows:

[0081] (13)

[0082] in Indicates the controller gain. and This indicates the gain of the PI controller.

[0083] like Figure 3 The diagram shows the overall control block diagram of the adaptive speed control scheme for a single-inverter dual-parallel permanent magnet synchronous motor, including a three-phase inverter (1), space vector pulse width modulation (2), inverse Clark transform (3), inverse Park transform (4), current loop controller (5), adaptive average speed controller (6), adaptive differential speed controller (7), Clark transform (8), Park transform (9), common-differential mode coordinate transformation (10), position encoder one (11), position encoder two (12), permanent magnet synchronous motor one (13), and permanent magnet synchronous motor two (14). The control is achieved by collecting the total current of phase A. and the total current of phase B The control parameters are obtained through Clark transform 8 and Park transform 9. The velocity and position information in the common-mode coordinate system is obtained through the common-mode coordinate transformation 10. Combined with the adaptive average velocity controller 6, the adaptive differential velocity controller 7, and the current loop controller 5, the voltage reference in the rotating coordinate system is obtained. and Finally, the switching signal is obtained through inverse Park transform 4, inverse Clark transform 3, and space vector pulse width modulation 2 to control the three-phase inverter 1.

[0084] like Figure 4 The figure shown is a simulation result of the speed control of two parallel motors. The results show that, using the adaptive speed control method provided by this invention, the speeds of the two parallel motors remain consistent, achieving excellent control performance.

[0085] like Figure 5 The experimental results of the current waveforms of the two parallel motors are shown. The results indicate that, using the adaptive speed control method provided by this invention, the amplitudes of the currents in the parallel motors are equal, and the phases remain synchronized, indicating that the speeds of the parallel motors are consistent.

[0086] The above description represents the preferred embodiments of the present invention. It should be noted that those skilled in the art can make various improvements and modifications without departing from the principles of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. An adaptive speed control method for a single-inverter dual-parallel permanent magnet synchronous motor, characterized in that, include: Step 1: An equivalent mathematical model of the system is established through non-singular coordinate transformation, revealing the coupling relationship between the inverter output voltage and the system control target; The mathematical model of a dual-parallel permanent magnet synchronous motor with the same parameters in the dq rotating coordinate system is as follows: ； in , and They represent the first Complex vector representation of stator current and stator voltage on the dq axis of a trolley motor; Represents the imaginary unit. , and These represent the inductance, resistance, and moment of inertia of a parallel motor, respectively. and These represent the number of pole pairs and flux linkage of the parallel motor, respectively. , and These represent the mechanical rotor position, mechanical speed, and load torque of the k-th motor, respectively. Define the average coordinate system and difference coordinate system for: ； The mathematical model of motor 1 is transformed by coordinates. The mathematical model of motor 2 is transformed by coordinate transformation. The equivalent mathematical model of the parallel motor is obtained as follows: ； Subscript and Let the mean variable and the difference variable represent the two variables, respectively, and they are defined as follows: ； Indicates a variable used in a general sense; Step 2: Combining the design concept of the backstepping controller, the basic control framework of the dual parallel motor drive system was constructed. According to the equivalent model of a dual parallel motor (3-3), the inverter output voltage can only control the average current of the dq axis. Based on the design concept of the backstep controller, and combined with the equivalent models (3-2) and (3-5), it can be seen that the current... and It can be used as a virtual control input for the average speed loop and the differential speed loop, respectively; Step 3: Based on the deterministic equivalence principle, an adaptive average speed controller was designed to improve the system's robustness to parameter mismatch and load disturbances. Rewrite the equivalent model (3-2) of the dual parallel motor in the form of state-space equations: ； in average speed , express , express , express , Represents the average current along the q-axis , Represents the d-axis differential current ; Define average velocity tracking error ； in This represents the average speed reference value; according to The average speed tracking error can be obtained. The dynamic equation is: ； in Represented as , Represented as ; Based on the principle of deterministic equivalence in adaptive control, the average speed controller is designed as follows: ； in express The adaptive term estimate, express The adaptive term estimate is expressed as follows: ； in and These represent the adaptive term gain; Step 4: An adaptive differential velocity controller was designed using the gradient search method. By correcting the controller gain online using the gradient, the risk of instability caused by system singularities was effectively avoided. Rewrite the equivalent model (3-5) of the dual parallel motor in the form of state-space equations: ； in average speed , express , Represents the average current along the d-axis , Represents the q-axis differential current ; Define differential velocity tracking error ； in This represents the average speed reference value; according to The differential velocity tracking error can be obtained. The dynamic equation is: ； in Represented as , Represented as ; By combining the gradient search method, the differential velocity controller can be designed as follows: ； in Indicates the controller gain. and This indicates the gain of the PI controller.

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